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-Chapter 01
-PPA Obligations
-1. What is the Declared Annual Dependable Capacity of LP/PG for
-current year?
-Declared annual dependable capacity or ADC of Lalpir and Pakgen is as follows
-Lalpir Power Limted: 350 MW Net Sent out
-Pakgen Power Limited: 350 MW Net Sent Out
-2. What are the Scheduled Outage months for LP/PG? In which WAPDA
-notification they are covered?
-Pursuant to Section 6.2(a)(i) of PPA , WAPDA has to send “Year Ahead
-Notification” to the company mentioning “Maintenance Months”. After its receipt,
-within 45 days, company shall propose to WAPDA its schedule outage period
-within those mentioned “Maintenance Months”.
-3. How and when Maintenance Outage can be taken?
-Maintenance outage can be taken any time during the year. As the need arises,
-company shall inform to WAPDA / NPCC of such need mentioning
-commencement and duration of such outage. NPCC / WAPDA will then
-approve/allow such outage in light of their need for energy from the unit and the
-necessity of the outage.
-4. What is the difference between Scheduled Outage and Maintenance
-Outage?
-Scheduled Outage is the outage planned within the consent of NPCC/WAPDA
-during maintenance months designated in “Year Ahead Notification”.
-Whereas Maintenance Outage is the outage requested to NPCC / WAPDA for
-necessary maintenance of the equipment and half of its duration in hours will be
-deducted from maintenance allowance of 500 hours
-5. What is the difference between Forced Outage and Partial Forced
-Outage?
-Forced Outage is the non-availability of complex to dispatch electricity to NPCC
-due to any reason
-Partial forced outage is partial availability of complex. In other words during
-partial forced outage complex is unable to meet NPCC / WAPDA demand.
-6. What links are provided to communicate with WAPDA?
-Hotline, Direct Number and Cell Phone (to Shift Managers)
-7. What is dependable capacity, when it is required to demonstrate?
-Dependable capacity is the full capacity of complex, which can be delivered to
-WAPDA/NPCC.
-To continue receiving “Capacity Purchase Price” per month , it is required to
-demonstrate complex capacity for consecutive six hours on any day mutually
-agreed by both parties within the “Demonstration Period”.
-8. What are the benefits of ADC on capacity payment?
-ADC has direct impact on “Capacity Purchase Price”.
-“CPP” has two portions of capacity payment. Capped Capacity & Added
-Capped Capacity
-Lalpir capacity is capped at 347.3 MW while Pakgen Capacity is capped at
-343.7 MW. Complex Capacity above this capped capacity is termed as Added
-Added Capped Capacity.
-Any Increase in capacity will result in increase in added capped capacity portion
-of “CPP” and vice versa.Lalpir/Pakgen Power Plant 4
-CCR Qualification Book
-9. What are liquidated damages with respect to forced outage/ partial
-de-rating?
-As per PPA, Company has been provided with 500 hours of maintenance
-allowance against each MW. For each forced outage and partial forced outage
-(Partial De-rating) , MW are calculated. If hours calculated during total forced
-outage and partial forced outage duration exceeds 500 hours maintenance
-allowance, Company will have to pay penalty equivalent to 1.6 times of Capacity
-purchase price against each exceeded MWh.Lalpir/Pakgen Power Plant 5
-CCR Qualification Book
-10. What is the weighting factor applicable to FO/PD/MO during peak & non-
-peak hours? What are new Weighting Factors effective from year 2021?
-Following are the weighting factors applicable to FO, PD, and MO.
-Month PEAK N.PEAK SUN
-1 2.50 2.00 1.50
-2 0.90 0.30 0.20
-3 0.80 0.50 0.50
-4 1.50 0.75 0.50
-5 1.50 0.75 0.50
-6 1.50 0.90 0.50
-7 1.50 0.90 0.50
-8 0.95 0.60 0.40
-9 0.95 0.60 0.40
-10 0.95 0.60 0.40
-11 0.90 0.30 0.21
-12 2.00 1.50 1.00
-Weighting factor effective from next agreement year
-Month PEAK N.PEAK SUN
-1 1.00 0.80 0.65
-2 1.00 0.80 0.65
-3 1.00 0.80 0.65
-4 1.00 0.80 0.65
-5 2.20 1.50 1.20
-6 2.20 1.50 1.20
-7 2.20 1.50 1.20
-8 2.20 1.50 1.20
-9 0.40 0.35 0.35
-10 0.40 0.35 0.35
-11 0.40 0.35 0.35
-11. Ho1w2 WA0P.4D0 A ca0.n35 disp0a.3t5c h both complexes?
-WAPDA/NPCC requests for dispatch as per merit list revised fortnightly based
-on different factors including fuel cost, variable O&M cost, any other specific
-cost in terms of Rs/kWhLalpir/Pakgen Power Plant 6
-CCR Qualification Book
-12. What are the technical limits regarding to Unit start up? (NTS)
-Technical limits regarding to Unit startup (NTS) are as follows
-Standby/shutdown duration less than 2 hours: 50 Min
-Standby/shutdown duration less than 8 hours 90 Min
-Standby/shutdown duration less than 32 Hours 130 Min
-Standby/shutdown duration less than 150 hours 300 Min
-Standby/shutdown duration More than 150 hours 400 Min
-13. Describe classification of start-up of the unit?
-As per PPA Unit startup is classified as follows
-NTS within 8 hours of shutdown: Hot
-NTS within 150 hours of shutdown: WARM
-NTS within 8 hours of shutdown: Cold
-14. What are the limits of start-up regarding to (numbers)/ years?
-Limits of Startups per year are as follows
-Hot start 52 per year & 500 Total Startups during the PPA Term
-Warm start 26 per year & 600Total Startups during the PPA Term
-Cold start 6 per year & 60 Total Startups during the PPA Term
-15. What is complex load ramping rate?
-Cold Rate Hot Rate
-Gen Load Run up Rate Run up Rate
-0 – 90 MW 1% of Gross Capacity 1% of Gross Capacity
-90 – 180 MW 1% of Gross Capacity 2% of Gross Capacity
-180 – MCR 1% of Gross Capacity 3% of Gross Capacity
-16. What is stabilization time? During load ramping during cold /warm/hot
-start?
-Stabilization time is time given for turbine temperature stabilization e.g its casing
-expansion, its casing/rotor diff expansion.
-Cold Rate Hot Rate
-Gen Load Hold time Hold time
-On Sync 30 Mins 0
-At 90 MW 10 min 10 min
-180 MW 10 min 10 min
-17. What are Generator technical limits for frequency/power
-factor/voltage?
-Frequency technical limit is ±5% on 50 Hz
-Power factor technical limit is 0.85 lagging and 0.90 leading power factors on 24
-kV,
-Voltage range is ±10% on the 220 kV systems
-18. What advantage does the Company get if it reduces the Scheduled
-Outage period below thirty days?
-For each 24 hours reduction in scheduled outage, company gets 12 hours of
-maintenance allowance in addition to 500 hours.
-For thirty days reduction in scheduled outage, company will get additional 15
-days hours of maintenance allowance.Lalpir/Pakgen Power Plant 7
-CCR Qualification Book
-19. Under what conditions WAPDA shall be entitled to suspend the
-Capacity Payments? How these payments will be restored?
-If for a period of consecutive 18 days , company fails to deliver more than 50%
-of the dispatch level requested by NPCC/WAPDA, then capacity payment will
-be suspended (subjected to the event other than schedule outage, maintenance
-outage or force majeure)
-When company is able to meet dispatch level requested by NPCC / WAPDA, it
-will notify and have to deliver more than 50% of the dispatch level consecutively
-for 3 hours , only then capacity payments will be restored.
-20. What is tolerance level of dispatch level is case of:
-a. Ramping
-b. Steady load
-For ramping , tolerance limit is 4.5% of the net electrical output and for steady
-load tolerance is 3% of the net electrical output.
-21. What is FTADL amount in Rs/kWh for each kWh outside the
-tolerance?
-FTADL Amount in Rs / kWh = 0.3×IE × kWh outside the tolerance
-t
-22. If the Company is unable to meet the requested Dispatch for a
-continuous period of three (3) hours, then how shall such shortfall
-be treated as?
-It will be treated as Partial forced outage due to FTADL, and the non-
-compliance MW’s will be deducted from 500 hours of maintenance allowance.
-23. What are consequences if we do not meet NTS time
-a. We synchronize the unit late
-b. We synchronize the unit early
-In case of Late Unit Sync, delayed time will be treated as forced outage and
-partial forced outage till the time company meets WAPDA/NPCC demand
-In case of early sync, FTADL will be given by NPCC/WAPDA
-24. What are droop ranges of Automatic Voltage Regulator (AVR) and
-Turbine Governor as per PPA? What is current droop setting of
-Turbine Governor?
-The AVR will control the generator voltage over the range of – 10% of rated
-voltage with a droop characteristic of – 0.5%.
-The Unit/Turbine governor droop is adjustable in the range 1.5% to 8%.Lalpir/Pakgen Power Plant 8
-CCR Qualification Book
-25. What is meant by Force Majeure?
-A "Force Majeure Event" is any event or circumstance or combination of events
-or circumstances that is beyond the reasonable control.
-26. What does “Prudent Utility Practices” mean?
-Operating the complex within the technical limits and as per merit order is
-normally termed as “Prudent Utility Practice”
-27. What is MDI? How is it calculated? What is current rate of MDI
-penalty?
-MDI is maximum demand index.
-Maximum kWh imported during any half hour in a month is MDI and it is
-calculated as “Max kWh Imported in half hour × prevailing MDI Rate × 2”
-28. What is Power Factor Penalty? How is it calculated?
-If import power factor is less than 90%, then company has to pay power factor
-penalty. It is calculated as “2 × MDI Panely × Differential P.F”
-
-Chapter 02
-Safety & Environmental Management
-1. Write down the salient features of Lalpir Safety & Environmental
-Policy?
-Salient features of Lalpir Safety & Environmental Policy are
-• Comply with or exceed requirements of global, national, state, and local
-statutes, regulations, and standards protecting the environment, human
-health and safety. In the absence of laws and regulations, or where they
-are simply not adequate for our operations, we will apply sound
-Occupational, health and safety (OHS) management practices.
-• Strive for continual improvement in Environment, health and safety to a
-world class performance using external bench marking system.
-• Establish global EHS standards that are robust, scientifically sound, and
-protective of the environment, human health and safety.
-• Implement EHS management systems to identify and manage EHS
-risks, obligations, and opportunities.
-• Conduct regular audits to verify compliance with regulatory
-requirements and company standards.
-• Establish specific EHS metrics to measure and report on our
-performance.
-• Incorporate EHS considerations into our business decision-making
-processes.
-• Work to prevent ill health, accidents, injuries, and unsafe work
-conditions; promote energy and water conservation; encourage the
-reuse and recycling of materials; and reduce waste, emissions and the
-use of hazardous substances in our operations.
-• Monitor emerging issues and keep abreast of regulatory changes,
-technological innovations, and stakeholder interests.
-• Strive to develop effective and sustainable solutions to EHS challenges
-arising from our business activities.
-• Regularly communicate relevant and meaningful information about our
-EHS performance to our internal and external stakeholders.
-2. Define safety & environmental management system in light of ISO
-14001 & 45001? Also give an overview of QMS & EMS?
-ISO 14001 covers the implementation of an Environmental Management
-System (EMS), placing focus on an organisation’s impact on the external
-environment. The standard aims to reduce an organisation’s waste, pollution
-and energy consumption.
-ISO 45001 on the other hand, focuses on an organisation’s internal
-environment. Whilst ISO 14001 requires the implementation of an EMS, ISO
-45001 is based on an OHSMS (Occupational Health and Safety Management
-System).
-The standard aims to reduce workplace injuries and illnesses and provide a
-framework for managing health and safety responsibilities.
-Getting certified in ISO 14001 displays a commitment to the environment, while
-ISO 45001 shows a commitment to your employees
-QMS is a Quality Management System also known as ISO 9001.
-EMS is an Environmental Management System also known as ISO 14001Lalpir/Pakgen Power Plant 10
-CCR Qualification Book
-3. Define environmental Aspects and Impacts? Write down the factors to
-be considered while determining the environmental Aspects and
-Impacts?
-The elements of organization’s activities or services that can interact with the
-environment are called environmental aspects.
-• Air emission
-• Liquid hazardous waste
-• Noise
-• Transportation of material
-Environmental Impacts:
-Any change to the environment, whether adverse or beneficial Resulting from
-the company's activities, products and services
-• Increase in ambient, CO, SOx, NOx etc.
-• Ground water contamination
-• Deterioration of hearing capability
-• Spillage & leakage of hazardous waste
-4. What are the requirements of EPA permits? List down the
-environmental limits for effluents and stack emissions?
-Parameters Limits and units
-Effluent Flow (M3/hr)
-PH 6-9
-Temperature: 40 oC
-Temperature rise =< 3 oC
-TSS 200 mg/l
-Oil & Greases 10 mg/l
-Gaseous Emission Monitoring
-Emissions Emission Standards and Units
-Carbon monoxide 800 mg/Nm3
-Oxide of Nitrogen (NOx) 600 mg/Nm3
-Sulphur Oxide (SOx) 1700 mg/Nm3 x mg/Nm3
-Particulate Matter 300 mg/Nm3
-5. List down the priority parameters those need to be reported to EPA
-for effluents and stack emissions?
-Effluents parameters are; pH, TSS and Oil & Greases
-Stack Emission Parameters are: CO, NOx, Sox and Particulate matter
-6. What are the environmental targets and objectives of Lalpir?
-Safety and environmental targets and objectives of AES Lalpir thermal power
-station are as follows;
-• To be always in compliance with all applicable laws and regulations
-• To work for continuous improvement of environmental management
-system
-• To prevent environmental excursions/threats
-• Identifying environmental Aspects and impacts
-• Improving environmental efficiencyLalpir/Pakgen Power Plant 11
-CCR Qualification Book
-7. Write down On Line monitoring system for stack emission and
-effluents?
-Following on line systems are present to monitor the effluents and the emissions
-of industrial gases:
-CEMS (Continuous Emission Monitoring System) to monitor the parameters of
-stack emissions.
-On line monitoring system to check the chemistry of effluents.
-8. List down the operational controls on environment taken by Lalpir?
-The Operational Controls taken by LalPir are as follows;
-• NOx Emission Control
-• Fugitive Emission Control:
-• Effluent Treatment
-• Noise Management Program:
-• SO2 Emission Control
-9. Define the types of NO and describe NO control in Lalpir?
-x x
-a) Two-Stage Combustion Process to Control NOx
-The two Staged combustion processes significantly reduce NOx emissions. In
-the initial stage of combustion, the air supplied to the burners through fuel air
-dampers is less than the amount required to completely burn the fuel. During
-this stage, fuel bound Nitrogen is released but cannot be oxidized due to
-deficient Oxygen, so it forms stable molecules of harmless molecular Nitrogen
-(N2). Other components of the fuel are also released without being fully
-oxidized. By adding a second stage combustion through auxiliary air dampers
-the flame temperature doesn’t increase up to level where NOx be generated.
-b) Over Fire Combustion Process to Control NOx
-The over fire air is used at the top of the flame because the temperature is very
-high at the top of the flame and here is the possibility of thermal NOx formation.
-The over fire air passes through the nozzle type dampers and its velocity is high
-which is sufficient for reducing the temperature of the flame at the top. This
-reduction in temperature in NOx formation zone controls the excess NOx
-formation.
-c) GRF Re-circulation Process to Control NOx
-Basically, the flue gas re-circulation is used to control the re-heat outlet steam
-temperature in the boiler. But at the same time it is used to control the NOx.
-d) Burner Tilting Process to Control the NOx
-Basically, burner tilting causes to lift the flame up wards and increases the re-
-heat outlet steam temperature. It is also used to control the NOx. By lifting the
-flame up wards the greater portion of the fireball comes in front of the nozzle
-type over fire air dampers. Hence, the temperature of the flame goes down
-immediately due to the turbulence and hence NOx formation is controlled.
-e) Corner Firing Process to Control the NOx
-Basically, the corner firing system is used to form one continuous flame and it
-causes the equal distributed heat transfer throughout the furnace. In this flame
-the temperatures are very high at top and the ultra violet rays are also present
-at this stage, here the over fire dampers are provided to control the NOx by
-causing reduction in temperatures through creating turbulence.Lalpir/Pakgen Power Plant 12
-CCR Qualification Book
-10. Define SO and how it can be controlled?
-2
-Lalpir and Pakgen units are High Sulphur Heavy Fuel Oil (HSFO) Fired Power
-Plants. The range of Sulphur present in HSFO may vary between 2.5 to 3.5 %.
-During combustion of HSFO, Sulphur which is present in the fuel is oxidizes to
-sulfur dioxide (SO2).
-(To be in compliance with environmental regulations of World Bank regarding
-SOx (for Pak Gen), a provision has been made for the Sulphur dioxide removal
-plant (FGD).
-This plant has been designed to reduce SO2 emission to 90 %).
-11. Define particulate matter and Fugitive emission, also describe their
-control?
-The particulate matter is formed due to inefficient combustion control in the
-furnace and high level of ash contents in High Sulphur Furnace Oil (HSFO). To
-be always in compliance with environmental requirements Lalpir and Pakgen
-units are using Less than 0.03% of ash content in the HSFO.
-Lalpir and Pak Gen units have a very precise and optimized combustion control
-process with very low Carbon monoxide emission rate.
-Fugitive emissions may be expected from the fuel oil storage tanks or through
-distributed piping. Petroleum hydrocarbons vapors may be released into the
-atmosphere due to vapor pressure of the fuel at ambient temperature.
-At Lalpir the fugitive emissions are minimized by providing cone roofs to the
-storage tanks. Fugitive emissions from distributed piping are controlled by
-sealed system, proper maintenance and leakage monitoring.
-12. What is the purpose of constructing high stack chimney?
-The purpose of high stack is to provide the draft to flue gases for emission into
-atmosphere. At that point flue gases would mix easily in air.Lalpir/Pakgen Power Plant 13
-CCR Qualification Book
-13. What are EIA and EIS? Why are these necessary?
-EIA
-Environmental Impact Assessment (EIA) is the term applied to the systematic
-examination of the likely impacts of development proposals on the environment
-prior to the beginning of any activity.
-UNEP defines Environmental Impact Assessment (EIA) as a tool used to
-identify the environmental, social and economic impacts of a project prior to
-decision-making. It aims to predict environmental impacts at an early stage in
-project planning and design, find ways and means to reduce adverse impacts,
-shape projects to suit the local environment and present the predictions and
-options to decision-makers. By using EIA both environmental and economic
-benefits can be achieved, such as reduced cost and time of project
-implementation and design, avoided treatment/clean-up costs and impacts of
-laws and regulations.
-EIS
-Those proposing to undertake certain projects had to show that their projects
-were not going to significantly affect the environment. They had to produce what
-is called an Environmental Impact Statement (EIS) to show the nature and scale
-of their project, the affected environment, and the likely impacts and measures
-taken to reduce/monitor these impacts.
-A description of the likely significant effect, direct and indirect, on the
-environment of the development, explained by relevance to its possible impact
-on:
-• Human beings
-• Flora
-• Fauna
-• Soil
-• Water
-• Air
-• Climate
-• The landscape
-14. Write down important environmental parameters those need to be
-considered before issuing modification?
-Important Environmental parameters are as follows;
-• Emission Control
-• Effluent Treatment/Control
-• Noise Management Program
-• Areas Aspects and their operational controls
-• Spillage Control
-• Hazards associated with EnvironmentLalpir/Pakgen Power Plant 14
-CCR Qualification Book
-15. What is Waste Management? Write down the benefits of waste
-management? What control Lalpir has on waste?
-Lalpir Power Ltd has a documented waste management procedure defining the
-types of waste along with the responsibilities for collection and disposal. Our
-waste disposal program briefly given below,
-Waste Type Storage Handling / Plan
-Red dust Transferred to Scrap yard at designated place
-Paper
-bin and then to outside.
-General solid Green dust Transferred to Scrap yard at designated place
-waste bin and then to outside.
-Metallic Green dust Transferred to Scrap yard at designated place
-Waste bin and then to outside.
-Oily Cotton Yellow dust
-Transferred to Scrap yard at designated place.
-rags bin
-Drain the container in HFO pump house oil pit
-Used Oil In container
-and then transfer it to HFO tank.
-Soot Drums Transferred in open yard and stored.
-16. Discuss the tag out lockout procedure; prepare a tag out order from
-beginning to completion.
-LOTO Procedure
-Pre-Requisites
-Tag out Request/ Application/Request for an Isolation Guarantee
-Preparation of a Switching Order and Preparation for Shutdown
-Switching Order Verification
-Preparing for Equipment Shutdown
-Equipment Shutdown
-Application Steps
-Step # 1 – Equipment & Job Description
-Step # 2 – Tags description
-Step # 3 - Isolation (Application of Tags)
-Step # 4 - Verifications
-Step # 5 - CRE Approval and Authorization to work
-Step # 6 - Craft Acceptance / Release
-Step # 7 - Completion
-Step # 8 - Equipment restored for operational use:
-17. What is TTR, when it required, how you will proceed when some
-request a TTR?
-TTR is temporary tag out release. It is required when a tagout is accepted by
-two or more than two craft person and one craft person has completed his job or
-a part of job and it requires partial restoration of equipment to check the job
-progress or equipment status.
-TTR will be requested by any one or more than one craft person.
-All craft person has to release the tagout , remove their locks,
-Released tagout tags will be placed in lock box
-CRE/Shift Manager will start the procedure for TTR as per safety form
-Person who has requested the TTR, will accept the TTR
-After the job completion , TTR will be released by the craft person
-Tags will be re-applied and verified by area engineer
-Craft person(s) will re-accept the tag
-CRE/Shift Manager will re-authorize the tagoutLalpir/Pakgen Power Plant 15
-CCR Qualification Book
-18. Describe how to issue a hot work permit?
-A Hot Work Permit is required when any work that produces a spark or flame
-that may cause ignition of flammable substances in the vicinity of that activity.
-a) Welding and allied processes
-b) Heat treating
-c) Grinding
-d) Thawing pipes
-e) Hot riveting
-f) Similar applications producing a spark, flame, or heat
-Following steps are taken before issuing a hot work permit
-A. Physical Inspection by area engineer
-B. Environment Testing and logging
-C. Fire Watch availability
-D. Fire extinguisher availability
-E. Craft AcceptanceLalpir/Pakgen Power Plant 16
-CCR Qualification Book
-19. Discuss the confined space entry procedure, prepare a confined
-space entry?
-Steps for Preparation for Confined Space Entry are as follows
-• Confined Space Isolation through tagout
-• Ventilation of Confined Space
-• Protection of Confined Space: Appropriate barriers, boundaries and
-signs to be established surrounding Entry Points and other openings of
-Confined Spaces to prevent unauthorized persons from Entering the
-Confined Space
-• Communication with Entrants: Equipping entrants with communication
-device (Radio). At least one Entrant must, at all times, have a radio in
-plant critical confined spaces
-• Atmospheric Testing: Using certified and in working condition gas
-detector, Tester will test the atmosphere of Confined space for the
-presence of any toxic gases.Following conditions must be met before
-giving entry permission for confined space
-Oxygen content: The oxygen concentration level shall be
-o
-monitored continuously and shall be in the 19.5% to 23.5%
-range
-Flammable gases or vapors: Concentrations shall not exceed
-o
-10% of the LEL. If the area’s oxygen level is not in the range
-given above, check that the Gas Detector is functioning
-properly.
-Chlorine Content: The chlorine concentration level shall be
-o
-monitored and shall be less than 0.5ppm.
-CO Content: The CO (Carbon Monoxide) concentration level
-o
-shall be monitored and be less than 2ppm.
-• Heat: The Tester shall also sense the temperature inside the Permit
-Required Confined Space where deem necessary. Although the limit is
-what ever is bearable for the Entrant, an indication of the temperature
-inside will give the Entrant guidance as to the duration that he will feel
-comfortable inside the Confined Space.
-• Dust: Airborne Combustible dust: Dust levels must not exceed its LEL.
-.
-After the completion of above steps, Confined Space Entry Permit shall be
-issued by entering following information in the form.
-• Name of permit space to be entered,
-• Name of requester / craft person
-• Atmospheric Test results
-• Tester's initials or signature
-• Purpose of entry and known space hazards
-• The minimum environmental conditions which are acceptable for entry
-and working in the space
-• Measures to be taken to isolate permit spaces and to eliminate or
-control space hazards
-• Date and authorized duration of entry
-• Communication equipment to maintain contact during entry
-• Any personal protective equipment that is necessary for the entry or
-rescue of the workers in the confined space.
-• If hot work will be necessary in the space, it must be authorized on the
-Entry Permit or a separate Hot Work permit must be attached to the
-entry permit. In this case, the issuance of the Hot Work permit is then
-noted on the entry permit itself.
-• Any other information needed to ensure employee safety.
-• A means for assuring and certifying that all pre-entry requirements have
-been met.Lalpir/Pakgen Power Plant 17
-CCR Qualification Book
-20. Define Risk Assessment and hazard categories? Prepare sample risk
-assessment of any hazard? List down risk control measures?
-Overall process comprising a risk analysis (Identification of hazards, estimation
-of risk) and a risk evaluation (evaluating the significance of risk)
-The hazard identification process involves two main activities:
-1. Workplace Hazard Identification
-2. Job Hazard Analysis
-After approval of risk control measures, the concerned Area Team Leader shall
-be responsible for implementing the Risk Control measures. The Safety
-Committee shall monitor and follow-up the implementation of risk control
-measures and evaluate whether the risk control measures are effective to
-eliminate or reduce the risks. In case the control measures are found ineffective,
-new control measures shall be identified or recommended, which will be
-reviewed and then approved for implementation.
-21. What is the difference between TTR and IRF?
-Temporary Tag Out Release (TTR)
-There may be occasions when testing, positioning, making adjustments or to
-perform other work on an isolated equipment or system, a TTR procedure is
-necessary. It should be remembered that the TTR should only be used for the
-approved work.
-Only one Craft Person or Craft Group Leader shall accept a TTR at a time. Any
-other Craft Person or Craft Group Leader can only accept a TTR once the TTR
-has been released by the previous Craft Person or Craft Group Leader. The
-only exception to this is during a craft shift change when the arriving Craft
-Person or Craft Group Leader will accept the TTR before the leaving Craft
-Person or Craft Group Leader Releases the TTR.
-IRF (Item Release Form)
-The IRF can be issued by the CRE who will be responsible to ensure the safety
-of the relevant Lockout Tag out Order.
-In case of a block permit, when many jobs are in progress under one Tag out
-Order, where change in any one or more Isolation point’s position is required,
-IRF may be requested.
-The portable earth / ground wires shall be removed before issuance of IRF
-where applicable.
-The Area Team leader will review the risk assessment and approves issuance
-of IRF.
-Craft People will signs off in release column of IRF in verification of the fact
-that work has been suspended on that particular equipment and portable earth /
-ground wires has been removed where applicable.
-After the change of Isolation, job will be performed and IRF will be completed.
-
-Chapter 03
-DCS
-1. Briefly describe the main architecture of DCS.
-DCS has following sub systems.
-APC – Automatic Plant Control
-BMS – Burner Management System
-DEH – Digital electro Hydraulic
-SEQ1– Sequence 1
-SEQ2 – Sequence 2
-IPU– Input Output Unit
-Each system has two CPU’s. One remains in service and 2nd is standby.
-In addition to these, Accessories control stations are also provided for logging
-events and reports.
-Though, initially DCS had separate printer for Report, Event and Alarm, but now
-system is modified and one printer is used for every print function.
-2. Identify the functions of various keys on the keyboard?
-3. Discuss the alarm list and event tracing?
-In alarm summary all the alarms are summarized in sequence. 20 alarms can
-be displayed in one screen and 200 alarm massages can be displayed as the
-maximum.
-Alarm Summary page has 6 columns and show following information
-Sr #, Level, Time Stamp, Tag, Description, Limit , current , Unit
-Alarm number is defined according to time sequence.
-No. 1 means latest alarm and No. 200 means oldest alarm
-Alarm mark and color are distinguished according to alarm grade
-Alarm mark has the function of touch target to confirm and reset each alarm
-In Event Tracing, 34 recorded events are shown in 8 columns per page as per
-time stamp. Event page columns are as follows.
-No. Type, Level, Time Stamp, Tag, Description, Status, Equipment
-Event list keeps all the entries recorded for a particular time and during this
-specific time alarms or event list can be retrieved for a particular period of time
-or particular KKS number. Event list doesn't delete like alarm summary when
-alarm returns to its normal position.Lalpir/Pakgen Power Plant 19
-CCR Qualification Book
-4. Which filters we can apply on Alarm List and Event Tracing?
-In alarm summary filter can be applied by Equipment or by priority or by both.
-In Event Tracing filter can be applied on Date/time, Tag Message, and
-Type/State
-5. How can we put ‘soft lock’ on drives on DCS?
-Go to “Drive Loop Plate” Click on “Tagging”, Click on 2nd button from left with
-screen tip as “Put a new Tag”, Enter required information against each heading ,
-select “Forbid” in Mode section, and click on Registration. This will put soft lock
-on drive and it can not be started now.
-6. How a control loop can be locked and unlocked on OPS?
-Open control loop , click on “Lock” button . Now control loop is locked and
-operator / CRE can perform function manually .
-7. How to set a new trend explain to display and scan a trend?
-Press “OPS Explorer” navigate to Lalpir/Pakgen  Master Data Real Time
-Trend Function  Trends or Trend
-Various trends are pre-configured in DCS. They can be edited to include or
-exclude any selectable function.
-Each trend can plot maximum 16 parameters with an option of “ON/OFF” , “∆”,
-Scale. Each parameter line color can be selected from the preset options.
-Maximum last 30 days data can be plotted on each trend with the time scale of
-1 sec to one day.
-Each parameter value along with graph is displayed in trend, and adding time
-mark will show the spot value in trend.
-8. How you will print a report from OPS?
-Press “OPS Explorer” navigate to Lalpir/Pakgen  Master Data OPS
-functions  Online printing /Storage management
-This “online printing /storage management” log and store pre-configured log
-reports in “Report Group Management” folder. All reports in this folder are saved
-in DC (Data Collection) PC folder “ D:\ACEExtSave\LGD”. From Data collection
-PC these reports can be printed and can be written on DVD
-9. How you will print a trend or graphic on printers?
-Pressing Hard Copy on keyboard will print current screen on printer.
-To print trend , open it, and press Hard Copy.
-Similarly to print a graphic , press Hard Copy on keyboardLalpir/Pakgen Power Plant 20
-CCR Qualification Book
-10. Describe main sequence and sub sequence and drive level control?
-Main Sequence:
-Main sequence is the system for start-up and shutdown of set of equipment’s. It
-is configured as per start-up and shut down program and sends command for
-start-up and shut down when system meets all the requirements.
-This system take cares of all the following.
-a. Time, when they are required to start and when they are required to
-shut down, countdown of start-up time for all the equipment’s involved
-in that sequence and if it exceeds from the specific time limit it initiates
-an abnormal alarm to alert operator to take necessary action. Ultimately
-sequence will not proceed forward for the next step.
-b. Interlocks, it takes care of all the interlocks required for all the major
-equipments as well as all the associated equipments.
-c. It provides start-up and shutdown permissive requirements and if
-system doesn't meet the all required start or shutdown permissive, it
-restricts the CRE to start or shutdown the equipments.
-d. In case of maintenance system or equipments start-up can be locked
-from the main group, so that equipments can be isolated to get a safe
-maintenance of the equipments.
-e. It provides redundancy of all the group equipments based on order of
-selectivity if next equipment meets the requirement.
-f. It looks after all the steps involved in the safe and proper start-up and
-shutdown of set of equipments.
-Sub Sequence:
-Sub sequence is the system for start-up and shutdown of individual equipment's
-and its associated accessories. This system take cares of all the following.
-a. Time when they are required to start and when they are required to shut
-down, countdown of start-up time for set of equipments involved in that
-sub sequence and if it exceeds from the specific time limit it initiates an
-abnormal alarm to alert operator to take necessary action. Ultimately
-sequence will not proceed forward for the next step.
-b. Interlocks, it takes care of all the interlocks required for all the sub group
-equipments as well as all the associated equipments.
-c. It provides start-up and shutdown permissive requirements and if
-system doesn't meet the all required start-up or shutdown permissive, it
-restricts the operator to start or shutdown the equipments.
-d. In case of maintenance, sub-system or equipments start-up can be
-locked from the main group, so that equipments can be isolated to get a
-safe maintenance of the equipments.
-Drive Control:
-Drive control is the system for start-up and shutdown of individual equipment.
-This system take cares of all the following.
-a. Drive control system provides the direct start stop facility of the
-equipment like hard-wired control systems.
-b. Interlocks, it takes care of all the interlocks required for the equipment.
-c. It provides start-up and shutdown permissive requirements and if
-equipment doesn't meet the all required start-up or shutdown
-permissive, it restricts the operator to start or shutdown the equipment.
-d. In case of maintenance, equipment start-up can be locked from the
-CRT, so that equipments can be isolated to get a safe maintenance of
-the equipment.Lalpir/Pakgen Power Plant 21
-CCR Qualification Book
-11. What are the sources of power supply for OPS, how you can change
-the power from UPS to 110V AC emergency services?
-There are two sources of power supply.
-a. UPS AC 110 volt.
-b. Emergency MCC 110 volt.
-c. Tie in b/w unit-1 and unit-2 only for OPS 3&4.
-When it is required to change over the power supply from UPS to Emergency
-MCC or UPS, switch is having three following positions.
-a) UPS
-b) Off
-c) 110 volt
-Select from one power supply to other power supply. (This operation is
-preferred to perform in the presence of E&I personal)
-12. What is the function of interlock?
-Interlock means operating protection of equipment or system, when Interlock is
-"IN" interlock is effective. If system does not meet the interlock requirement, it
-will not let the interlock activate.
-When Interlock is "OUT" interlock is not effective. When some system error
-appears, system is capable to go to manual and it can be cared manually.
-13. Demonstrate the understanding of following logic gates w.r.t. DCS
-logic tracing:
-a. Function of AND,OR,NOT gates
-b. Function of Set/Reset latch
-Demonstrated to Shift Manager
-14. Demonstrate the logic tracing of the following:
-a. Start permissive of any boiler feed water pump
-b. Start permissive of HFO transfer pump
-Demonstrated to Shift Manager
-
-Chapter 04
-Boiler Logic's
-1. What is the furnace purge permissive, why it is important?
-Furnace purge permissive is the “Conditions that must be fulfilled” before
-starting furnace Purge. Mainly all boiler main equipments operation is included
-in this permissive e.g Igniter Oil , Diesel Oil, Flame detectors, Auxiliary dampers
-modulation, Any FDF & GRF Operation, at least one BCP operation and MFT
-condition.
-These conditions are important as their healthy operation is necessary for boiler
-operation and to remove combustible mixture from boiler. In case of
-unavailability of any condition we will not be able to operate boiler.
-2. How long furnace purge will take to complete? What is the basis of
-selection of this time duration?
-Furnace purge takes 300 seconds (5 minutes) to complete. This time is required
-to pass air from whole boiler to remove any unburned fuel oil from furnace.
-3. How much time is required for leak test to complete?
-All leak tests (Igniter Oil, diesel Oil, HFO) duration is 180 seconds.
-4. What conditions will be required to be fulfilled before starting HFO,
-diesel and igniter oil leak test?
-Igniter Oil Leak Test Permissive
-a) Air flow >30%
-b) All auxiliary dampers modulated
-c) All igniters off
-d) All Igniters Shut off Valve close (MFT)
-e) Igniter Oil supply pressure : Normal
-Diesel Oil Leak Test Permissive
-a) Air flow >30%
-b) All auxiliary dampers modulated
-c) All diesel oil burner valves close
-d) All burners Shut off Valve close (MFT)
-e) Diesel Oil supply pressure : Normal
-f) Any Diesel Oil pump in service
-HFO Leak Test Permissive
-a) Air flow >30%
-b) All auxiliary dampers modulated
-c) All fuel oil burner valves close
-d) All burners Shut off Valve close (MFT)
-e) HFO supply pressure : NormalLalpir/Pakgen Power Plant 23
-CCR Qualification Book
-5. Explain in sequence the different steps of HFO, diesel and igniter oil
-leak test?
-On furnace purge command, Igniter / Diesel leak test will start automatically.
-(Igniter / Diesel can be started individually through their respective loop plate,
-but it is recommended to let them start on auto)
-Step 1: Diesel, Igniter main shut off valve open for 10 seconds to develop
-pressure in their respective header
-Step 2: Diesel, Igniter shut off valve close
-Step 3: If pressure in header remains constant and it do not decrease by 1 Bar,
-Leak lest will be completed.
-In case of pressure drop to 1 bar or more, leak test is un-successful and it has
-to be restarted.
-For HFO leak test all steps are same.
-Before starting HFO Leak test, close HFO stabilizing valve manually.
-Following are oil pressure of HFO, Diesel, and Igniter.
-HFO > 24 KG / cm2
-Igniter & Diesel oil > 10 kg / cm2
-.
-6. When does HFO warm up MOV goes to full close position on auto
-demand?
-On HFO Leak test it will close on auto demand and after Unit synchronization,
-When 3rd Burner is fired, HFO WARM UP valve close on auto.
-
-Chapter 05
-Boiler Permissive
-1. What conditions must exist for light up igniters?
-“Igniter Oil Conditions” Established and
-For Lighting up full row igniters , all four igniters must on on “Main” and give
-them Startup Command from their respective loop plate from BMS screen
-For Individual igniter light up, select it on sub first and give On command from
-Furnace flame screen.
-Igniter Oil Conditions include following conditions further
-a) MFT Reset
-b) Atomizing Air pressure
-c) Igniter Oil Header Pressure
-d) Igniter Oil shutoff Valve in Open Position
-e) Igniter Oil header temp normal.
-f) Flame detector cooling air in service
-g) Air flow is greater than 30%
-2. At what conditions we can shift diesel oil firing to HFO firing?
-We can shift to HFO firing after completion of HFO Leak test and achieving HFO
-header temperature equal to or greater than 90 Deg C. It is recommended to
-raise Stack inlet flue gases temperature greater than 100 Deg C before taking
-HFO burners in service.
-3. What is the starting permissive of:
-a) FD fans
-Start Permissive
-Respective fan’s side Air Heater in service
-Instrument and cooling air available
-b) Air heaters
-Start Permissive
-Its Lube Oil temp less 55 Deg C or its respective Lube oil pump on Auto
-Instrument and cooling air available
-c) Cooling air fans
-It can be started manually. No Specific permissive required.
-d) Igniter fan
-It can be started manually. No Specific permissive required.
-e) GR fans
-Respective side FDF in service along with AH and
-Instrument air & Cooling water normal
-f) BCP
-BCP Motor side caity temp less than 57 Deg C
-Cooling water flow normal
-Boiler drum Level is greater than low levelLalpir/Pakgen Power Plant 25
-CCR Qualification Book
-g) Boiler feed pumps
-Main Feed Water pumps Startup permissive
-Casing Temperature normal
-Lube Oil pressure is normal
-DA level Normal
-Header pressure greater than 160 kg/cm2 , If it is less than 160kg/cm2
-then following valve position must be ensured.
-Valve Position
-Pump’s Minimum flow valve open
-Pump’s Disch Valve close
-Feed water MOV’s (main and backup) Close
-Feed water CV close
-SH & RH DSH Shutoff Valves Close
-4. When do we get Air and Gas OFF permit while shutting down the
-boiler?
-After 5 minutes of MFT. This is to ensure removal of any un-burnt fuel
-mixture from the furnace.
-5. On what conditions do we get Air Heaters OFF permit?
-Air Heater’s respective FDF in Off Position will give AH Off permit in its
-respective sub-sequence control loop plate.
-6. On what conditions do we get AC Cooling Fan OFF permit?
-On Boiler drum metal temperatures less than 100 Deg C , AC Cooling
-fan off permit appears.
-
-Chapter 06
-MFT
-1. What is MFT?
-MFT stands for Master Fuel Trip. In case, any Boiler/Turbine trip
-protection operates, MFT also operates simultaneously.
-2. What conditions cause the MFT, explain briefly?
-Boiler Manual Trip
-Boiler Interlocks for MFT
-a) Both FDF Trip
-b) Both AH Trip
-c) Both AC , DC cooling fan trip
-d) Both BCP Trip
-a. Low Diff Pressure 0.5kg/cm2 for greater than 3
-seconds
-e) V.Low HFO burner header pressure (7kg/cm2)
-f) V.Low Atomizing steam header pressure (Less than 6 kg/cm2)
-g) V.Low DO burner header pressure
-h) V.Low Atomizing air pressure
-i) Air flow less than 30% for more than 3 seconds
-j) High furnace pressure for more than 3 seconds
-k) All Flame loss
-l) RH Protection (if unit is in startup mode)
-m) 3rd Burner in service (If unit is in startup mode)
-n) BMS Power loss
-o) APC Failure
-Turbine Trip
-Generator Trip
-3. What actions are required on occurrence of MFT, explain in detail your checks and actions?
-There are two cases for MFT
-a. Controlled Unit Shut down
-b. Unit Tripping
-Controlled Unit Shutdown
-In controlled unit shutdown, MFT occurs after all burner guns have been
-retracted and all igniters are turned off. In this case after 5 minutes Air and
-Gas Off permit will appear. Turn off Air and Gas sequence and put it on
-Hot Banking or Normal as per requirement
-Unit Tripping
-52C-Generator Breaker and Excitation breaker 41E1 Open, If not , open
-them from mimic panel
-Confirm turbine trip, If not, trip Turbine
-Confirm all Fuel Shutoff Valves are Close (Igniter, Diesel, and Furnace Oil)
-Close SH & RH DSH Shutoff valves
-Both GRF stopped and their Turning gear came in service
-Both Air heater rotor drive is in service
-Confirm opening of turbine drains,
-Turbine MSV , GV, and RSV , ICV’s are close
-Turbine AOP in service.
-Follow “Shut Down” Check sheet furthur
-
-Chapter 07
-Air and Gas System
-1. Explain in sequence the startup of air and gas system; what is
-required to be checked at DCS before starting the air and gas
-system?
-Pre Check for Air and Gas system start command:
-• FDF(s), GRF(s) 11kv breakers are close and their VFD’s are
-energized.
-• Instrument air pressure normal
-• Cooling water (BCWP) in service.
-• MFT exists.
-Air and Gas start sequence.
-When air and gas sequence On command is given from “Air and Gas”
-main sequence, following main steps are performed in order.
- Step 1: A/B Air Heater On
- Step 2: A-FDF On
- Step 3: B-FDF On
- Step 4: AC Cooling Fan On
- Step 5: A-GRF On
- Step 6: B-GRF On
-2. What do you mean by excess air, what are its effects on combustion
-and what is its setting at different load?
-Air in excess to theoretical air required for complete combustion is
-excess air. At maximum load it’s range is from 1% to 2% while at 50%
-load , it is 2~3%. At 20% load , it ranges from 7~8%
-3. Why it is important to keep wind box pressure higher than furnace?
-It is important to keep wind box pressure higher than furnace to keep
-Positive air combustion air flow towards furnace. Also in case of less
-wind box pressure, hot flue gases will travel towards wind box.
-4. What is the purpose of fuel air, aux. Air and over fire dampers?
-Fuel air dampers.
-Fuel air dampers modulate to adjust fuel air as per requirement. Each
-burner has its own fuel air damper.
-Aux air dampers.
-Auxiliary air dampers maintain differential pressure between wind box
-and furnace. Each burner has two aux. air dampers.
-Over fire dampers.
-Over fire damper maintains No level, two over fire dampers are provided on each corner top.
-5. What is the importance of combined back end temperature, what is
-the safe limit of this temp at our plant and how you will achieve that?
-Combined back end temperature is the average temperature of Steam
-Air Heater air outlet temperature and AH flue gas outlet temperature.
-The importance of this temperature is to maintain the dew point at air
-heaters. Combined back temperature should be maintained with in limit
-to avoid achieving dew point at AH cold end, flue gas duct and stack
-inlet.
-Safe Limit, 1250C
-Controlling the air temperature at AH inlet by SAH can control the
-combined back end temperatureLalpir/Pakgen Power Plant 28
-CCR Qualification Book
-6. What is the purpose of GR fans and burner tilt?
-GR fans are used to re-circulate flue gases from economizer outlet to
-furnace. This increase in volume of flue gases increases re-heat
-temperatures. GR fans have now Variable voltage variable frequency
-drives installed and their frequency is managed to increase/decrease
-re-heat temperatures. When selected on Commercial mode, their outlet
-vanes are manipulated to control re-heat temperatures.
-Burner Tilt controls the fire ball position in the furnace, +ve change in
-burner tilt increases re-heat temperature and vice versa.
-7. Where cooling and sealing air is being used and why it is important to
-provide a DC cooling air fan in the system?
-Cooling and sealing air cools down and seals various equipment to
-avoid leakage of hot flue gases through respective equipment. The
-areas where cooling and sealing air is used are TV camera; flame
-detectors, Dampers shaft seals, Burners guns, igniters, peepholes.
-DC cooling air fan is provided to avoid the failure of flame scanners due
-to high Temperature, which causes the MFT. In case of AC cooling fan
-failure the DC cooling air fan will cut in automatically to avoid the
-damaging of flame scanners.
-8. What do you mean by the corrected NOx and what is its allowable limit?
-NO is abbreviation of gasses formed by the reaction of Nitrogen and Oxygen, where x is the number of oxygen atoms reacted with the Nitrogen.
-At high temperatures in furnace, nitrogen in air and nitrogen in fuel
-reacts with oxygen and form oxides of nitrogen. (Nitrous oxide, Nitric
-Oxide, Nitrogen dioxide, Nitrogen monoxide, and nitrogen pentaoxide)
-As oxides of nitrogen are mostly toxic and are harmful , therefore they
-are diluted by giving excess air.
-Concentration of NOx gases after the addition of excess air is known as
-corrected NOx.
-As per World Bank requirements, its allowable limit is 130 gm/Gj
-NOx is continuously monitored through online analyzer. Its calculation
-formula is as follows.
-NOx (PPM) ÷ [1-(O2 % ÷ 20.95)]
- 
-9. What is opacity, what is its limit?
-Opacity is the opaqueness of flue gasses. It is the measurement of
-stack inlet flue gas density. The more flue gases are dense, the more
-opacity is. Less opacity co-relates to less density of flue gases and less
-pollution.
-Opacity depends mainly on unburnt fuel , soot content and excess air.
-Its allowable limit is less than 40% and normal limit is 10 ~ 15%Lalpir/Pakgen Power Plant 29
-CCR Qualification Book
-10. What is the importance of SOx and NOx , how it can be controlled to safe limits?
-SOx is the abbreviation of oxides of sulfur, where x is the number of
-oxygen atoms reacted with sulfur atom. When oxides of sulfur are
-released in the atmosphere, they react with hydrogen in the atmosphere
-or get absorbed in the moisture and forms sulfuric acid. In rainy season,
-SOx becomes more dangerous as they results in acidic rain. 
-SOx is controlled by using low sulfuric acid fuel and using flue gas de-
-sulphurizer Unit (FGD). Its allowable limit as per World bank was 0.2
-Ton/MW/Day. Though Lalpir/Pakgen no more follow world bank
-standards, but it is our moral obligation not to pollute atmosphere
-NOx is abbreviation of gasses formed by the reaction of Nitrogen and
-
-Oxygen, where x is the number of oxygen atoms reacted with the
-Nitrogen.
-NOx is controlled by managing excess air and over fire air dampers.
-11. Give different reasons of furnace explosion, how it can be avoided?
-The main reason of Furnace explosion is accumulation of fuel oil and its
-uncontrolled ignition. Fuel oil accumulation may be due to
-Accumulation of unburnt fuel in furnace
-• Any off-load burner fuel shutoff valve passing (be it HFO or HSD)
-• Diesel Oil passing from any off-load igniter
-• Improper Fuel Combustion
-Other contributing reasons include Human error, bypassing furnace
-purging during startups and shutdowns
-Furnace explosion can be avoided by proper furnace purging during
-startups and shutdowns, removal of all oil leaks in furnace, and periodic
-testing of Boiler Interlocks.
-12. What is the biggest loss in the boiler, how it can be reduced with in
-safe limits?
-Chimney losses is the biggest loss of boiler, other losses are as follows.
-• Radiation losses due to poor refractory (insulation).
-• Valve leakage / passing.
-• Soot deposits on the boiler tubes.
-• Scaling due to poor chemistry.
-• Poor fuel quality
-• CBD
-These losses can be reduced by
-• Maintaining AH flue gas outlet temperature just above due
-point.
-• Any steam/water/fuel leakage or passing shall be rectified
-• CBD operation as per LAB recommendation only
-• Continuous check on chemical parameters of Boiler water and
-steam
-• Sootblowing
-• Periodic maintenance and replacement (if required) of refractory
-and insulation
-13. Which drives in Air and Gas system are fed from 400V Emergency
-Bus?
-• A&B AH rotor drives
-• GRF turning gear motorsLalpir/Pakgen Power Plant 30
-CCR Qualification Book
-14. What are Furnace pressure High, HH and trip limits?
-Lalpir
-Furnace Pressure High 550 mm H2O
-Furnace Pressure HH 575 mm H2O
-Trip Limit 590 mm H2O greater than 3 Seconds
-PakGen
-Furnace Pressure High 550 mm H2O
-Furnace Pressure HH 575 mm H2O
-Trip Limit 590 mm H2O greater than 3 Seconds
-15. What action should be taken on receiving above mentioned alarms to
-avoid boiler tripping?
-• Check O2 and O2 Bias. O2 shall be on auto and its bias shall be 0
-• Check auxiliary dampers. They should be on auto.
-• Check FDF VVVF . It should be on auto and its bias shall be 0
-• Both air heaters Gas inlet dampers. They shall be open and on auto
-• Check air and gas side parameters to confirm blockage in furnace
-If above mentioned all things are checked and are found OK,
-immediately drop Load until furnace pressure drops and becomes
-normal.
-16. Describe the single leg operation of Air and Gas system? What
-precautions should be taken while operating in this mode?
-Lalpir /Pakgen boiler has two FDF’s with their respective Steam Air
-Heater, Gas Air Heater and GRF
-Each FDF with its respective SAH, GAH and GRF is termed as One
-Leg.
-Unavailability of one FDF or one GAH makes whole leg un-available,
-and operating unit with only one FDF with its respective GAH is termed
-as One Leg Operation or Single Leg operation.
-Precautions for Single Leg Operation of Air & Gas System:
-Close all dampers of unavailable Leg (FDF inlet, FDF Outlet, GAH inlet
-and GAH Outlet).
-Make sure unavailable side GAH rotor drive is in service.
-Monitor unavailable side temperature parameters.
-17. What is difference between VFD and commercial mode for FDF? How
-can we change from VFD to commercial and vice versa?
-VVVFD’s (Variable Voltage, Variable frequency drives) are installed at
-both FDF’s to control air flow as per unit load by varying FDF input
-frequency and voltages.
-In VVVF mode, air flow is primarily controlled by varying voltage,
-frequency and secondary controlled by FDF Inlet Guide Vanes.
-Due to any reason, if VVVF system is not available, VVVF system can
-be put on bypass from DCS by selecting “Commercial” as a start mode
-from loop plate at A/B FDF top side on Air and Gas flow screen.
-In commercial mode, frequency will remain constant at 50 Hz and FDF
-IGV’s will modulate to maintain air flow.Lalpir/Pakgen Power Plant 31
-CCR Qualification Book
-18. What is difference between VFD and commercial mode for GRF?
-VFD’s (Variable frequency drives) are installed at both GRF’s to control
-flue gases air flow as per requirement to control Reheater super heater
-temperatures by varying GRF’s input frequency
-In commercial mode, frequency will remain constant at 50 Hz and GRF
-IGV’s will be modulated to maintain air flow.
-19. How can we change from VFD to commercial and vice versa?
-Due to any reason, if VFD system is not available, VFD system can be
-put on bypass from DCS by selecting “BY-PASS” as a start mode from
-loop plate at A/B GRF top side on Air and Gas flow screen.
-20. Write down the energy optimization procedure from shutdown to cold
-conditions and in different seasons?
-• Stop both BCP’s as soon as unit is shutdown
-• Take out last burner, Turn Off all igniters.
-• Keep only one HFO pump in service.
-• Stop Igniter Oil pump
-• Put Boiler on Hot Banking as soon as permit is available.
-• At GAH inlet temp less than 90 Deg C , Stop GAH turning motor
-• At GRF inlet temp less than 90 Deg C, Stop GRF turning motor
-• At drum metal temperature less than 100 Deg C, stop AC Cooling fan
-• At drum metal temperature less than 100 Deg C , use spool piece for
-drum filling
-21. How you will handle high fuel and low air situation?
-High Fuel:
-• Observe burner header pressure at burner firing and burner shutdown.
-• Ask area engineer to have a through round and check pressure at
-each individual burner, and report of any difference.
-• Ask area engineer to check FCV and PCV position and get it matched
-from DCS
-Low Air Situation
-• Check O2 and O2 Bias. It should not be –ve
-
-• Check for –ve Bias on FDF’s VVVF. It should be Zero.
-• Check FDF’s inlet guide vanes. They should be open, on auto and
-should not have –ve bias
-
-Chapter 08
-Boiler Drains
-1. What is the purpose of economizer re-circulation valve, when it opens
-and closes automatically?
-During boiler start-up there is no continuous feed water flow through
-economizer. So there is chance of overheating or steaming in the economizer
-due to heat exchange from flue gases.
-Recirculation valve is provided to maintain continuous feed water flow through
-economizer to avoid overheating and steaming in economizer tube.
-Economizer recirculation valve remains open till 20% load and closes at load
-greater than 20%.
-2. Why it is important to use boiler drains, what is the role of these
-drains to achieve the steam conditions?
-Drains are provided in boiler at all super heaters (1ry, 2ry, 3ry), Steam drum
-blow down, Economizer, mud drum, HRH drain and Leg Drain. These drains
-are manipulated for different needs. At DCS , control is provided for following
-drains.
-• Primary SH Drain
-• Tertiary SH Drain
-• Steam drum Blowdown
-• Hot Reheat drain
-• Leg Drain
-Primary SH & Tertiary SH Drain
-These drains are used primarily in startup to drain any condensate and to
-achieve required steam parameters as per startup mode. They are also used
-in forced outage for boiler forced cooling
-Steam Drum Blow Down (CBD)
-It is used to control the boiler chemistry. If chemical parameters (mainly Iron
-and Silica) are poor, then it is opened as per Lab recommendation to drain
-steam drum in controlled way.
-Hot Reheat Drain
-It is used to remove accumulated condensate in hot reheat line. It can be
-opened either towards CBD tank or towards Condenser.
-Leg Drain
-This drain is used to drain accumulated moisture from main steam line to avoid
-travelling of condensate towards HP Turbine. It is also used to achieve steam
-parameters during startup.
-3. What is the function of main steam leg drain, what interlock is
-associated with this valve, what you will check before opening this
-valve?
-This drain is used to drain accumulated moisture from main steam line to avoid
-travelling of condensate towards HP Turbine. Therefore its opening is
-configured in its auto operation on MFT. During unit shut down , it is
-recommended to keep it close on manual to avoid its opening due to this
-configuration.
-This valve’s auto control is also configured in turbine stress control and its
-opening / closing is manipulated on auto to control turbine stress during
-startup. If this valve is on manual, SP1 permit will not appear. It has to be on
-auto before SP1 command.Lalpir/Pakgen Power Plant 33
-CCR Qualification Book
-During startup, when HP bypass opening is not available, this valve is opened
-on manual to achieve turbine inlet steam parameters for startup.Before
-opening this valve, it is recommended to keep temperature difference between
-main steam line and super heater outlet less than 50 Deg C to avoid
-hammering of steam and accumulated condensate in main steam line.
-4. Why we have CBD provided with steam drum, what is the role of this
-valve in chemistry control?
-CBD is used to control the boiler chemistry. If chemical parameters (mainly
-Iron and Silica) are poor, then it is opened as per Lab recommendation to drain
-steam drum in controlled way. Addition of fresh water then dilutes iron and
-silica concentration in steam drum and after periodic testing, when these
-parameters came within limits, CBD is closed.
-5. How many safety valves are provided on steam drum, SH, RH and
-what is their setting?
-Super Heater Outlet
-Sr # Popping Pressure Reset Pressure
-1 181.8 179.5
-2 185.4 179.5
-Steam Drum
-1 199 191.4
-2 204.9 197.1
-3 204.9 197.1
-4 204.9 197.1
-Reheat Inlet
-1 46 44.3
-2 47.5 45.5
-3 47.5 45.5
-4 47.5 45.5
-5 47.5 45.5
-6 47.5 45.5
-Reheat Inlet
-1 42.5 40.9
-2 43.5 41.8
-Auxilaty Steam Header
-1 21 19.53
-Soot Blower Header
-1 35 32.55
-Aux Steam To DA
-1 10 9.3
-Dearator
-1 10 9.3Lalpir/Pakgen Power Plant 34
-CCR Qualification Book
-6. Why SH safety valve setting is low as compared to drum safety
-valve?
-Safety valve is used to release excess pressure by opening & blowing steam
-in the atmosphere. Super Heaters are in fire / radiation zone inside furnace,
-and steam flow maintain super heater tubes temperatures by absorbing heat.
-As super heater safety valve pressure is set point is low, therefore it will lift and
-release pressure in atmosphere earlier as compared to steam drum safety
-valve. Steam will travel from steam drum towards Super heaters and save
-them from starvation due to absence of steam.
-7. What will the effect be of SH safety valve popping on the system,
-what action you will take to handle the situation?
-On SH safety valve popping, steam will rush from steam drum, resulting in its
-level fluctuation. Increased flow of cold make up water inside steam drum will
-reduce steam temperatures and pressure. To maintain steam parameters,
-boiler master will increase fuel flow. To match fuel air for complete combustion,
-FDF’s VVVF drives and their IGV’s will respond. If SH safety valve remains
-popping, this phenomenon will occur again and again resulting in abnormal
-parameters.
-If safety valve keeps popping or it does not closes properly, then reduce steam
-pressure, load till the time it closes properly. If problem persists , unit has to be
-shut down and safety valve has to be restored in closed position for safe unit
-operation.
-
-Chapter 09
-BCP
-1. Explain the function of BCP.
-BCP is the abbreviation of Boiler circulation pump.
-Circulation wise , there are two type of boilers.
-a. Natural circulation type
-b. Forced circulation type
-In natural circulation type boilers, water in furnace water walls rises naturally,
-whereas in forced circulation boilers, pumps are used to circulate water
-between steam drum and water drum (bottom reservoir for water).
-2. What are the advantages of providing a BCP over the natural
-circulation boiler?
-Forced circulation of water between steam drum and mud drum, increases
-heat transfer, reduces furnace height , increased rate of temperature rise.
-(110oC as compared to 60OC in natural circulation), reduces chances of
-overheating during startups and shutdown
-During shutdown, they also facilitate for even distribution of chemicals.
-3. What is the temperature limitation of BCP cavity?
-BCP Cacity maximum limit for temperature is 57OC, on reaching cavity
-temperatures to 60oC pump will trip.
-Normal operating temperatures are 40oC .
-4. In case of loss of power or cooling water flow, what automatic actions
-will take place to keep cool the cavity of the BCP?
-BCP cooling water has two sources.
-a. From BCWP Cooling water header (Main source)
-b. From Service water header (Backup Source)
-In case of loss of power, service water is available as service water pump A is
-on emergency bus bar. In this case, BCP cooling water SOV will close and
-BCP cooling water drain blow valve will open to maintain cooling water flow in
-BCP cavity coolers.
-5. While BCP sequence is on, when second BCP will cut in
-automatically?
-At 30 kg/cm2 steam drum pressure second BCP will cut in on auto
-6. What are the pre start checks in local and in control room before
-starting 1st BCP?
-• Permit: BCP Cooling water flow must be greater than 7 m3/hr
-• Drum Level is normal (Low Low alarm is not standing)
-• BCP Cooler inlet / outlet valves are open and cooling water medium is
-BCWP
-• BCP cavity temperature is less than 57OC
-• Instrument air pressure is normalLalpir/Pakgen Power Plant 36
-CCR Qualification Book
-7. Write down the BCP cooler cleaning procedure when unit is at
-maximum, minimum and is shut down?
-BCP Cleaning at Maximum Load, minimum load :
-Though it is not recommended to clean BCP cooler at full load, but if it is
-inevitable to clean BCP cooler, following is the procedure.
-• Increase Feed Water Header pressure appox 10 kg/cm2 than
-prevailing pressure at Steam Drum.
-Flushing valves are available at each step for the rust removal from lines.
-Please flush each line before taking it in service
-• Open cavity purging water valve from BFP Header (Area Acitvity)
-• Take purge water cooler in service by opening its cooling water inlet
-/outlet valve
-• Open cavity purging water cooler outlet valve
-• Open cavity purging water cooler supply to cavity valve
-Purging will be started, control pressure and temperature within limits
-• Close cooling water supply valve to cavity cooler
-• Close cooling water return valve to cavity cooler
-• Observe the temperatures ( They must remain stable)
-• Go ahead to open cooler inlet side flange with the help of MMD
-• Back flush the cooler by opening its outlet valve
-• Install cooler inlet side flange with the help of MMD
-• Open Cooler inlet/outlet cooling water supply valves
-• Close purge cavity supply valve
-• Close cavity purging water valve from BFP header
-• Open any drain from system to de-pressure the system and close it after de-pressurization
-Check valve line up thoroughly and observe cavity temperatures.
-During Shutdown, close cooling water supply and return valves, open cooler
-inlet side flange and open cooling water supply outlet valve for back flushing.
-During this activity, remove any external media form tubes by mechanical
-means (Rodding) with the help of MMD
-8. Why do we prefer BCP-A to take into service on first priority?
-BCP motor is of 6.6kV and initially both A&B BCP transformers were dry type
-and were installed in 11kV room. At startup, when BCP A was started, its dry
-type transformer tripped multiple times and had to be replaced with oversize oil
-type transformer installed out of 11kV room near PFI panel.
-As , it has oil type transformer sufficient enough to maintain its temperatures at
-high currents, it is therefore preferred to start on first priority.
-
-Chapter 10
-Auxiliary Steam
-1. How many sources of aux steam are available at our plant?
-There are three sources of auxiliary steam at our plant.
-a. From 3ry SH side inlet header
-b. From Cold Re-Heat header
-c. Auxiliary boiler
-In addition to these two sources, an inter unit tie is also provided to support
-other unit auxiliary header.
-2. What is the normal value of aux steam header pressure?
-Normal value of auxiliary steam header is 15 kg/cm2
-3. If aux steam from 3ry side not available at low load, how you can
-manage the system?
-As stated above, an inter unit tie is provided to support 2nd unit in case of
-emergency/requirement. However, if aux steam is not available from other unit,
-following measures will be taken to keep aux steam line up from cold reheat
-header, as aux steam header pressure will drop at low load
-• Stop main ejector and take vacuum pumps in service.
-• Close SAH TCV’s
-In addition to this, auxiliary boiler may be taken in service for auxiliary steam to
-support the unit
-4. Why aux steam flow is less at high load and more at low load?
-At full load following main aux steam consumers are out of service, therefore
-aux steam flow is less at high load as compared to low load.
-• SAH – Heating steam is from Extraction 5
-• DA – Heating steam is from Extraction 5
-• Gland Steam – Spill over takes control of gland steam header
-5. Where aux steam is being used?
-Aux Steam consumers are as follows
-• SAH
-• Steam Jet Air Ejector
-• Turbine gland steam
-• Steam converter (Primary Steam )
-	>Steam converter bypass (HFO suction/discharge heater, HFO tank heaters)
-• HFO decanting (Discontinued)
-• Atomizing Steam
-• Dearator
-6. What precautions are required when you open the crosstie between
-unit 1 and unit 2?
-While opening the Aux steam tie valve observe Aux steam header pressure
-and open the tie valve very slowly with the coordination of both CRE’s.
-• Crack open the tie valve for initial heating and make sure there is no
-condensation on receiving end to avoid hammering.
-• Divert steam converter condensate to the aux steam supply unit
-• Close steam converter condensate shutoff valve to LP-2 heater of Aux
-steam receiving unit
-
-Chapter 11
-Fuel Oil System
-1. What permissive are required opening the HFO shut off valve?
-HFO Shut Off Valve is main protection of boiler furnace to close fuel supply in
-case of Boiler tripping. Following are required conditions for its opening
-• Furnace purging is completed
-• HFO Leak test is completed.
-After successful completion of above two conditions , HFO Shut Off valve will
-open.
-2. How much time is provided for flame to stabilize before igniter goes
-off?
-After firing burner, igniter must be kept in service for minimum 30 seconds to
-stabilize respective burner flame. If igniter turns off for any reason before 30
-seconds, its respective burner will trip.
-3. Explain the sequence of events that occurs when a burner is coming
-in service?
-Sequence of event for burner firing (Cut In) is as follows
-• Igniter On
-• Burner gun will advance
-• Atomizing steam SOV will open
-• Combustion air dampers will open.
-• Burner fuel supply SOV will open.
-4. Explain the sequence of events that occurs when a burner is going
-out of service?
-Sequence of event on burner off command (Cut In) is as follows
-• Igniter On
-• Burner fuel supply SOV will close
-• Atomizing steam SOV will close
-• Burner purge SOV will open for 60 seconds of burner Off command
-• Burner purge SOV will close
-• Burner gun will retract.
-5. Discuss how to put HFO control oil on auto and how to shift diesel oil
-firing to HFO firing?
-Shifting from Diesel Oil firing to HFO firing
-• HFO Leak test is completed.
-• HFO temperature at burner header are equal to or more than 90OC
-• Stack inlet gas temperatures are greater than 100OC
-• Take Stage-B igniters in service from BMS screen (all 4 igniters will
-come in service in this way)
-• Put B-Row burners on “SUB” from their respective loop plate on
-Furnace flame screen
-• Take one diesel burner out of service
-• Give only One HFO burner from B row “On Command”
-• After B-Row burner is fired successfully, take remaining A-Row burner
-out of service.
-• Change fuel and atomizing media selection from Diesel to HFO and
-Air to Steam from BMS screenLalpir/Pakgen Power Plant 39
-CCR Qualification Book
-Shift HFO Control Oil on auto
-HFO Control oil can be shifted on auto after unit Synchronization in following
-way
-• Unit is synchronized and block load is achieved
-• Increase HFO Header pressure up to 18~20 kg/cm2 so that on firing
-next burner, header pressure may not drop to its low limit. In worst
-case if header pressure is dropped to 6 kg/cm2, MFT will occur.
-• Give Burner On command to 3rd HFO Burner
-• HFO Warm Up MOV (return line MOV) will start closing and this will
-increase burner header pressure
-• Take HFO Control Valve control loop on Small increment mode and
-reduce its opening to keep burner header pressure within limit (Less
-than 21 kg/cm2)
-• After HFO Warm up MOV is fully closed , put HFO control valve
-control on auto.
-• Make sure , BMS control is on auto.
-6. When BMS is on auto, in what sequence burners cut in and cut out on
-load demand?
-Burners Cut in sequence on Load Demand when BMS is on auto
-Burners (“cut in”) came in service in the form of pair (stage wise) when BMS is
-on auto.
-After synchronization when 3rd burner is fired and HFO control is shifted on
-auto, B-Row (Stage-B) 4th HFO burner had to be fired on manual. Then as per
-load demand following burners will cut in on auto
-Stage – C burners (C – 1 , C – 3)
-Stage – C burners (C – 2 , C – 4)
-Stage – A burners (A – 1 , A – 3)
-Stage – A burners (A – 2 , A – 4)
-Stage – D burners (D – 1 , D – 3)
-Stage – D burners (D – 2 , D – 4)
-Burners Cut out sequence on Load Demand when BMS is on auto
-On load decrease command, burners will come out of service in the following
-way
-Stage – D burners (D – 2 , D – 4)
-Stage – D burners (D – 1 , D – 3)
-Stage – A burners (A – 2 , A – 4)
-Stage – A burners (A – 1 , A – 3)
-Stage – C burners (C – 2 , C – 4)
-Stage – C burners (C – 1 , C – 3)
-On further load decrease, take BMS on manual and take B rows burners out of
-service manually.
-7. What is the purpose of atomizing steam, what is its normal pressure
-and temp?
-Atomizing steam is used to disburse HFO in the form of fine droplets / mist in
-furnace for its better combustion.
-Atomizing Steam pressure = 12 kg/cm2
-Atomizing Steam temp. = 190ºC
-Tripping pressure = < 5.0 kg/cm2
-8. What is the purpose of HFO stabilizing and warm up valve?
-Stabilizing valve:-
-After MFT, HFO shutoff valve is closed so HFO is circulated through
-Stabilizing valve back to HFO tank.Lalpir/Pakgen Power Plant 40
-CCR Qualification Book
-HFO Warm Up MOV:-
-HFO warm up MOV opens after HFO Leak test is completed and HFO Shutoff
-Valve is open. This MOV re-circulates HFO from HFO Ring header to HFO
-tank through HFO pumps. This MOV remains open till 3rd HFO burner comes
-in service. On 3rd HFO burner firing, this MOV closes automatically (if its
-control is on auto)
-Similarly , while shutting down the unit, this MOV opens on auto as soon as 3rd
-HFO burner is taken out of service ( remaining HFO burners are 2).
-9. Why we maintain the HFO temp, what are the temp settings at
-different locations?
-HFO is pre-heated in different stages near to its flash point for its complete
-combustion. Stage wise / Location wise temperature settings are as follows
-• HFO tank = 35 – 45ºC
-• HFO suction heater outlet = 60ºC
-• HFO discharge heater outlet = 100 – 120ºC
-If HFO temperature is less than 90OC, burner On permit will not appear, as this
-temperature is much less than HFO flash point.
-10. Discuss the alarms and trips associated with fuel oil and atomizing
-steam & air?
-Alarms on HFO:-
-• HFO tank level low. 4.0 meter
-• HFO tank level low low. 3.7 meter
-• HFO tank level high. 14.3meter
-• HFO tank level high high. 14.5meter
-• HFO pump suction temperature low. <40ºC
-• HFO firing pump suction pressure low. 0 kg/cm2
-• HFO firing pump discharge heater temp low. 90ºC
-• HFO firing pump discharge heater temp high. 130ºC
-• HFO burner header pressure low. <7.0 kg/cm2
-• HFO burner header pressure low low (trip). <6.0 kg/cm2
-• HFO burner header pressure high. >27 kg/cm2
-• HFO receiving strainer dp high. >0.2 kg/cm2
-• HFO pump suction strainer dp high. >0.2 kg/cm2
-• HFO pump discharge strainer dp high. >0.2 kg/cm2
-• Drain oil tank level high. >1.6 meter
-• Drain oil tank level high high. >1.63 meter
-• Drain oil tank level low low. 0.3 meter
-• Drain oil pump discharge pressure high. >6.0 kg/cm2
-• Drain oil pump suction strainer dp high. >0.2 kg/cm2
-• Burner drain oil tank level high high. >1.15 meter
-• Burner drain oil tank level low low >0.2 meter
-• Drain oil pump discharge pressure high burner area >4.5 kg/cm2
-• Drain oil pump suction strainer dp high. >0.2 kg/cm2
-• APC upper limit.
-• Fuel upper limit.
-• BMS abnormal.
-• Load program on manual.
-Trips on HFO:-
-• HFO pressure v.low.
-• HFO tank level v. low.
-• Atomizing steam pressure v. low.
-• Reheat protection due to oil flow high.Lalpir/Pakgen Power Plant 41
-CCR Qualification Book
-Alarm on Diesel Oil:-
-• Diesel oil tank level low. 1.5 meter
-• Diesel oil tank level high 8.4 meter
-• Diesel oil tank level high high 8.6 meter
-• Diesel oil burner header pressure low 6.0 kg/cm2
-• Diesel oil burner header pressure low low 3.0 kg/cm2
-• Diesel oil burner header pressure high >13 kg/cm2
-• Diesel oil burner header pressure high at low load >23 kg/cm2
-• Diesel oil burner temp low 10ºC
-• Diesel oil burner temp high 40ºC
-• Diesel oil pump discharge pressure low low <9.0 kg/cm2
-• Diesel oil pump discharge pressure low low at low load <12 kg/cm2
-• Diesel oil and igniter oil pump suction pressure low <0.5 kg/cm2
-• Diesel oil igniter header pressure low <3.0 kg/cm2
-• Diesel oil igniter header pressure high >7.0 kg/cm2
-• Igniter oil burner temperature high 40ºC
-• Igniter oil burner temperature low 10ºC
-Trips On Diesel Oil: -
-Diesel oil burner pressure v.low 3.5 kg/cm 2
-Diesel oil tank level v. low.
-Above tripping only takes place when only diesel oil burners are in service.
-Atomizing Steam:-
-Atomizing steam pressure low. <7.0 kg/cm2
-Atomizing steam pressure low low <5.0 kg/cm2
-Atomizing steam pressure high high >13 kg/cm2
-Atomizing steam temp low 180ºC
-Atomizing steam temp low low 150ºC
-Atomizing steam temp high 230ºC
-Atomizing steam temp high high 300ºC
-Trips On Atomizing Steam:-
-Atomizing steam pressure v.low.
-Atomizing Air:-
-a) Burner atomizing air pressure low <4.0 kg/cm2
-b) Igniter atomizing air pressure low <4.0 kg/cm2
-Trips on Atomizing Air
-Atomizing air pressure v .low.
-
-Chapter 12
-Feed Water System
-1. What alarms and trips are associated with feed water system?
-De-aerator Alarms:-
-De-aerator level high. >+200 mm
-De-aerator level high high. >+350 mm
-De-aerator level high high high. >+500 mm
-De-aerator level low -200 mm
-De-aerator level low low -400 mm
-De-aerator level low low low -2060 mm
-De-aerator overflow CV open. >+640 mm
-De-aerator inlet steam cut off operate >+500 mm
-De-aerator pressure high >8.0 kg/cm2
-De-aerator pressure low <1.2 kg/cm2
-BFP Alarms: -
-Suction strainer differential pressure high. >0.25 kg/cm2
-BFP lube oil filter differential pressure high.
-BFP suction flow low <150 T/H
-BFP suction flow low low <130 T/H
-Boiler feed water conductivity high >0.4 ms/cm
-BFP lube oil pressure low <1.5 kg/cm2
-BFP lube oil pressure low low <1.0 kg/cm2
-BFP lube oil cooler outlet lube oil temp high 48ºC
-BFP lube oil tank level low <380 mm
-BFP booster pump DE bearing temp high 70ºC
-BFP booster pump NDE bearing temp high 70ºC
-BFP gearbox high speed DE journal bearing temp high 115ºC
-BFP gearbox high speed NDE journal bearing temp high 115ºC
-BFP gearbox low speed DE journal bearing temp high 115ºC
-BFP gearbox low speed DE thrust bearing temp high 115ºC
-BFP gearbox low speed NDE thrust bearing temp high 115ºC
-BFP main oil pump DE seal water temp high 85ºC
-BFP main oil pump NDE seal water temp high 85ºC
-Seal water filter differential pressure high.
-TRIPS:-
-D/A level v. low. ( BFP trip due to low suction flow )
-Lube oil pressure v. low. ( BFP trip )
-Bearing temp . v. high.
-Feed water system alarms:-
-HP heater#6 conductivity high >0.4 ms/cm
-HP heater#6 level low -50.8 mm
-HP heater#6 level high +203.2 mm
-HP heater#6 level high high +253.2 mm
-HP heater#7 conductivity high >0.4 ms/cm
-HP heater#7 level low -50.8 mm
-HP heater#7 level high +203.2 mm
-HP heater#7 level high high +253.2 mm
-HP heater#8 conductivity high >0.4 ms/cm
-HP heater#8 level low -63.5 mm
-HP heater#8 level high +200 mm
-HP heater#8 level high high +272.3 mmLalpir/Pakgen Power Plant 43
-CCR Qualification Book
-2. How a feed water pump can be started on main group sequence and
-sub group sequence?
-Feed Water pump Start from main sequence
-11kV breaker is Closed
-VFD’s are energized
-DA Level is normal and condensate pump is in service
-Respective Pump’s AOP in service and put it on auto
-Close Discharge MOV put it on auto and Minimum flow shutoff valve on auto
-Select pump priority
-Pump on auto from its loop plate.
-Give on command from sequence (After unlocking it , if it’s lock)
-Feed Water pump Start from Sub sequence
-11kV breaker is Closed
-VFD’s are energized
-DA Level is normal and condensate pump is in service
-Close Discharge MOV and Minimum flow shutoff valve on auto
-Lock main sequence
-Give on command from sub sequence
-3. What will happen if one feed water pump trip at full load and what will
-be your action?
-In case of feed pump tripping at full load, Standby pump (3rd BFP) will cut in on
-auto. In case it fails to cut in , Unit run back will operate and unit load will drop
-to 50%.
-Action:
-Try to start stand by pump if fails to start watch closely the drum level,
-combustion, Deaerator level, Deaerator pressure, Drum pressure, condenser
-level and turbine TSI. If runback occurs, do not try to take any control on
-manual. After run back, take thorough observations of unit by scrolling all
-graphic screens. Inform to NPCC accordingly.
-4. What is the purpose of minimum flow valve in feed water pump?
-Every centrifugal pump provided with minimum flow line back to its reservoir
-equipped with its control valve. This is designed to protect pump from
-cavitation and maintain flow through the pump.
-As an impeller's move through a fluid, low-pressure areas are formed as the
-fluid accelerates around and moves past the blades. The faster the blade
-moves, the lower the pressure can become around it. As it reaches vapor
-pressure, the fluid vaporizes and forms small bubbles of gas. This is cavitation.
-When the bubbles collapse later, they typically cause very strong local shock
-waves in the fluid, which may be audible and may even damage the blades.
-5. What is a single element and three-element control, when control can
-be shifted from single element to three elements?
-Single Element:
-In single element control, feed water control valve follows only one parameter
-i.e. Drum Level.
-Three Element;
-In three element control, feed water control valve regulates/control feed water
-against three parameters i.e. Steam Drum Level, Main Steam Flow, and Feed
-water flow.
-When selected on auto, Feed water control shifts automatically from 1 Element
-to 3 Element after unit synchronization at 80 MW Gross.
-6. When main feed water control can be put on auto?
-Main feed water control can be put on auto at 130 kg/cm2 steam drum
-pressureLalpir/Pakgen Power Plant 44
-CCR Qualification Book
-7. How you will change the drum level control from main feed control
-valve to back up control valve and vice versa?
-Steam drum level is controlled primarily by BFP’s VVVF , however feed water
-control valves has secondary control on drum level.
-To change control from main to back FW CV, follow following steps.
-Open backup Feed water control valve inlet MOV
-Slightly open backup feedwater control valve and put it on auto.
-Observe steam drum level and BFP’s frequency.
-Select backup control from feed water control graphic as a main controller.
-Close main feedwater control valve and its inlet MOV
-To change FW CV selection when it is selected as a main controller follow
-following steps.
-Make sure main feedwater control valve is on auto.
-Slightly open backup feedwater control valve.
-Observe steam drum level, Main feed water control valve will respond by
-closing to maintain drum level.
-When main feedwater control valve is fully closed, put it on manual
-Select backup control from feed water control graphic as a main controller and
-put it on auto.
-Close inlet MOV of main feed water control valve.
-Same procedure has to be followed to shift control from backup feedwater
-control valve to main feedwater valve
-8. Why the aux steam is being used in deaerater?
-Boiler feed water is stored in dearator storage tank after pre-heating from Low
-pressure heaters. At LP 4 outlet, its temperature & pressure is above boiling
-point at standard temperature and pressure. Therefore, it is necessary to keep
-dearator pressurized so that feedwater remains below its saturation
-temperature by providing auxiliary steam.
-In addition to this, though our condenser is under vacuum, still a part of non
-condensable gases ingress in the closed cycle and are absorbed in
-condensate. Those non condensable gases are removed by dearation with the
-help of auxiliary steam on Dearator.
-Auxilary steam also contributes to BFP’s NPSH.
-9. At what rate you will fill the drum when the boiler is hot standby?
-Steam drum filling will be done at very slow rate to avoid thermal stress,
-preferably at 80~100 Tons per our.
-10. How feed water cycle efficiency is improved?
-Feed water cycle efficiency can be improved by maintaining feed water
-heater’s DCA and TTD
-11. When 2nd BFP will cut-in and cut-out during load ramp up and ramp
-down respectively?
-Feed water sequence when selected on auto, will automatically give On
-command to 2nd BFP at steam flow greater than 575 T/hr and will cut out 2nd
-BFP at steam flow less than 500 T/hr
-12. What will happen if 2nd BFP does not cut-in on auto demand during
-load ramping-up?
-3rd BFP will cut in on auto demand. In case it also fails to cut in , unit load will
-not increase.Lalpir/Pakgen Power Plant 45
-CCR Qualification Book
-13. What is difference between VFD and commercial mode for BFP? How
-can we change from VFD to commercial and vice versa?
-On VFD mode, VFD is main cotroler for steam drum level and it changes
-BPF’s frequency to maintain steam drum. Whereas on commercial mode,
-Frequency is constant at 50 Hz and does not changes w.r.t steam drum level.
-In this mode, Feed Water control valve is on main control to maintain steam
-drum level.
-We can change its selection from VFD to commercial or vice versa from
-pump’s control loop plate.
-14. Write down the energy optimization procedure from shutdown to cold
-conditions and in different seasons?
-Energy Optimization regarding feed water system:
-Stop main feed water pump by filling steam drum upto 600 mm approx..
-Stop all AOP’s for BFP’s
-Open their 11kV breakers.
-Turn off HVAC system of BFP’s VVVF Room ( Local Operation) after
-maintaining proper temperature.
-Use BFP D for steam drum filling as and when required.
-15. When we take BFP D in service, what is its benefit?
-BFP D is taken in service during startup till 80 MW gross load. It consumes
-less power as compared to main feed water pumps and hence not only
-reduces import electricity but also reduces MDI during startup.
-16. Describe the logic for main and backup feed water control valve
-briefly?
-Each feedwater control valve is designed for full load, Backup feedwater
-control valve is provided to increase system availability.
-
-Chapter 13
-Feed Water Heaters
-1. What is the purpose of feed water heaters in feed cycle, how these
-affect the plant efficiency?
-Feed water heaters increase the feedwater temperature / system enthalpy
-before entering the economizer. This regenerative feedwater heating reduces
-heat load on boiler as feedwater will be at higher temperature when entering
-the steam drum.
-HP , IP and LP steam turbine is compact and is designed in such a way that
-specific volume of steam is required at a set temperature and pressure to get
-required output/work done.
-As steam passes through the turbine blades, it expands after work done and
-hence its volume is increased. This expanded volume is reduced by providing
-extractions from different stages of steam turbine. These extractions are then
-used to pre-heat the feed water through feed water heaters. This increases
-overall efficiency of the plant.
-2. At what load feed water heaters will come in services, if a feed water
-heater fails to come in service on sequence how you will take these in
-service?
-LP Heaters will start to cut in automatically at 54 MW and HP heaters will cut in
-at 74 MW load, if sequence is on AUTO.
-If sequence fails LPH & HPH should be taken into service manually as follows:
-Lock the Main sequence.
-• Select Extraction MOV on manual.
-• Ensure heaters LCV on AUTO.
-• Partial open the extraction MOV to respective heater for pre-heating
-and then slowly open to full.
-• Open ext. steam v/v in sequence 3,4 and 5 accordingly.
-• Note that after full opening of ext. steam v/v, drains should be closed
-• on AUTO.
-Follow above procedure for taking HPH in sequence of 6,7 and 8.
-3. Explain cascade drain system?
-In cascade drain system, High pressure heater drain goes towards low
-pressure heater as a heating steam. Cascade sequence for HP and IP Heaters
-is as follows
-HP heater 8 Drain goes as heating steam to HP heater 7
-HP heater 7 Drain goes as heating steam to HP heater 6
-HP heater 6 Drain goes to Dearator
-LP heater 4 Drain goes as heating steam to LP heater 3
-LP heater 3 Drain goes as heating steam to LP heater 2
-LP heater 2 Drain goes as heating steam to LP heater 1
-And LP heater 1 drain goes to condenser.
-4. What is the purpose of startup vent and continuous vent?
-Heaters startup vent is used to vent accumulated gases in heater during long
-unit shutdown. Whereas continuous vent is provided to continuously remove
-non-condensable gases from heater shell side.
-5. Why heater trips on high level?
-As heaters heating steam is extraction from turbine, therefore on high level,
-there is possibility that condensate might reach turbine blades and may
-damage them as they are not designed for condensate at high RPM. Heaters
-trip on high level to save turbine from this happening.Lalpir/Pakgen Power Plant 47
-CCR Qualification Book
-6. What will the effect on boiler and turbine on tripping of one HP heater
-and on all HP heaters, what will be your action as a CRE?
-One HP heater trip:
-On HP Heater tripping, its inlet steam MOV (Extraction MOV) will close,
-resulting in
-• Increase in pressure at HP turbine 1st Stage if HP Heater 8 Trips
-(Minor Load Increase)
-• Slight increase in Cold Re-heat if HP heater 7 Trips
-• IP turbine inlet pressure will increase if HP 6 Trips (Minor Load
-Increase)
-• Slight decrease in feedwater to economizer, which will result in slight
-increase in SH temperatures due to increased fuel flow
-All HP Heaters Trip:
-On all HP heaters trip event, all extraction MOV’s will be closed and as a result
-of increase in turbine first stage pressure, increase in IP Inlet pressure, Unit
-load will increase. Turbine efficiency will drop also.
-Effect on Boiler
-Feedwater inlet temperature to boiler economizer will decrease, this will result
-in more heat transfer from flue gases to feed water. Consequently, this will
-reduce flue gases temperatures bear to or below their dew point. To increase
-outlet flue gas temperatures, inlet air temperatures had to be increased by
-opening more auxiliary steam towards Steam air heater.
-Fuel flow will increase to increase low feed water temperatures, this will result
-in increased SH temperatures. Consequently, more De-super heater spray
-would be required, this will increase load on BFP’s.
-Air flow will also increase as soon as fuel flow increases, this will put FDF’s
-under load and furnace pressure will increase resultantly.
-As a CRE, one should judge, if problem is resolvable, decrease unit load by
-20% to maintain parameters like fuel , air , SH temperature in control and take
-HP heaters in service one by one in ascending order (Starting from 6 to 8).
-If it is not possible to take HP Heaters in service, shut down the unit and
-address the problem as continuous operation in this condition may increase
-turbine stress and thermal load on boiler.
-7. What are the load limitations with different sets of feed water heaters
-out of service?
-The load limitations are,
-a) If one HPH will out, 10% load should be decreased manually if on MCR.
-b) If all HPH out 20 % load should be decreased manually.
-8. What are the advantages of erecting LP heaters1&2 inside the
-condenser?
-To gain the maximum thermal efficiency of LP turbine as these heaters remain
-under slightly vacuum so these are also used to minimize the moisture
-contents at LP turbine and off course play an important role in gaining overall
-system efficiency.Lalpir/Pakgen Power Plant 48
-CCR Qualification Book
-9. How you will monitor the performance of a heater, what are the
-possible causes of poor performance of a heater? Explain TTD and
-DCA and what are their impacts on heater performance?
-We can observe / calculate the efficiency of HPH from differential temp. Of FW
-Causes of Poor Efficiency:-
-a) Due to high level in HPH.
-b) Due to low level in HPH.
-c) Leakage.
-d) Poor insulation ( Radiation losses )
-e) Scaling on tubes.
-f) Poor automation in control system.
-g) Any passing in drains.
-
-Chapter 14
-Boiler Temperature & Pressure
-1. What is the nominal temperature and pressure of our boiler at MCR,
-what is the importance of this temp and pressure?
-Boiler SH out pressure (176 kg/cm 2)
-Boiler outlet temp. (540ºC)
-Cold reheat pressure (41 kg/cm 2)
-Cold reheat temp. (338ºC)
-Hot reheat pressure (38 kg/cm 2)
-Hot reheat temp. (540ºC)
-Our turbine is designed on these temperatures and pressure parameters. Any
-deviation in these parameters ultimately contribute to turbine stress.
-2. How main steam temp is being controlled, from where temperature
-control valves taking sense to control the temp?
-Main steam temperature is controlled by attemperators (De-
-Superheater spray) installed at the inlet of both tertiary Super heater inlet
-headers (Right and Left). These attemperators take sensing from 3ry SH outlet
-steam temperature.
-3. Why de-super heater spray introduced at the inlet of 3ry super
-heater?
-De-Superheater uses feed water nearly at 250 Deg C to control main steam
-temperatures. Reason to introduce it at the inlet of 3ry SH inlet header is to
-convert this spray into dry super-heated steam.
-4. What is the normal temp of hot reheat steam and how it is being
-controlled?
-Hot reheat temperature normal temperature is 540 Deg C. It is controlled
-mainly by GRF, Burner Tilt and by De-superheater at cold re-heat inlet header.
-5. What is the function of GRF and burner tilt in controlling reheater
-temp?
-GRF increases re-heat temperatures by re-circulating portion of hot flue gases
-from economizer to furnace.
-Burner tilt controls the reheat temperatures by controlling the height of fire ball
-with the help of burner guns vertical angle manipulation. Maximum burner tilt isa± 300
-6. What are the possible reasons of temp difference at LH side and RH
-side of 3ry-inlet header?
-Following are the possible reasons of temperature difference at LHS and RHS
-of 3ry SH inlet header
-DSH control valve passing.
-Due to uneven deposition of soot on different sections of super heaters
-In-sufficient steam flow from super heaters
-7. At what pressure vents can be opened?
-At 2.0 Bar it is safe to open boiler vents.
-8. At what temp boiler water can be drained?
-At less than 75oC , it is safe to drain boiler waterLalpir/Pakgen Power Plant 50
-CCR Qualification Book
-9. What is the minimum allowable SH and RH metal temperature?
-SH metal temp (550ºC) Normal (600ºC) Alarm.
-RH metal temp. (550ºC) Normal (580ºC) Alarm.
-10. Give some reasons of flue gases temperature high at air heater outlet,
-how it can be kept in safe limits?
-High flue gas temperatures at air heater outlet can be due to high cold end
-metal temperature set point at steam air heaters. Lowering steam air heater
-TCV set points can lower flue gas temperatures.
-
-Chapter 15
-Turbine Lube Oil System
-1. How many pumps have been provided in lube oil system, explain the
-function of each one briefly?
-Four lube oil pumps are provided in lube oil system. They are
-a. AOP (AOP provides HP oil and LP oil at less than 2950 rpm)
-b. TOP (Provides lube oil, when turbine is on turning gear)
-c. EOP (Provide lube oil in case of A/C TOP failure, it is in fact back up of
-TOP)
-d. Turbine shaft mounted MOP (Provide HP oil & lube oil while turbine is
-running at 3000 rpm)
-2. What is the function of jacking oil pump, at which bearings jacking oil
-has been provided?
-JOP provides HP pressure oil to bearing number 3 & 4 to lift the rotor while
-turbine is on turning gear
-3. What is the difference between HP oil, Auto stop oil and control oil,
-what is their normal value and what is their function?
-HP Oil:
-Operate the MSV’s / GV’s / RSV’s/ ICV’s. its pressure is 20~22 kg/cm 2
-Auto Stop Oil :
-It will drain through solenoid v/v in case of any protection operates. Its
-pressure is 9.0 - 10 kg/cm 2
-Control Oil:
-It is used to operate the servo motor of MSV’s / GV’s / RSV’s/ ICV’s. Its
-normal pressure is 3.0 kg/cm 2
-4. When turbine is on normal operation, how lube oil pressure being
-maintained and how suction to main oil pump being provided?
-When turbine remains in normal operation main oil pump supplies lube oil to
-T/G bearing through ejector and gets suction oil pressure through an ejector
-which is fed from MOP discharge line.
-MOP discharge Pressure 22 kg/cm 2
-MOP suction pressure 1.2 kg/cm 2
-5. During run up, when jacking oil pump and aux oil pump will cut out?
-JOP: -
-Jacking oil pump cut out at 800 rpm while increasing speed
-AOP: -
-AOP will cut in when condenser vacuum reaches to 550 mm Hg and will cut
-out at 2950 rpm turbine speed while increasing speed
-TOP: -
-It will cut out at 550 mmHg of condenser vacuum
-6. During run down when AOP, JOP and TOP will cut in?
-During run down when turbine speed comes below 2950 RPM, AOP will cut in
-on auto . It will also cut in on auto if lube oil pressure drops to 0.85 kg/cm2 or
-when MOP discharge pressure drops to or below 17.0 kg/cm2
-JOP will cut in at 800 rpm while decreasing speed.
-TOP will cut in when turbine speed comes down to 100 rpm and and also, will
-cut in if lube oil pressure drops to 0.75 kg/cm 2
-7. How the lube oil temperature being controlled?
-There are two lube oil coolers with a common TCV on discharge line, which
-controls the cooling water flow to maintain lube oil temperature.Lalpir/Pakgen Power Plant 52
-CCR Qualification Book
-8. Why it is recommended to keep oil temp at 35 C during turning gear
-operation?
-At 35 Deg C, lube oil has required viscosity for 3 RPM on turning gear.
-9. What is the purpose of vapor extractor?
-Vapor extractor fan extract / pull out the gases/ vapors from the main oil tank.
-It maintains slightly negative pressure 150 to 200 mm H2O
-
-10. What are the possible causes of main oil tank level increase?
-Following are the possible causes of main oil tank level increase.
-• Mixing of water in oil due to early condensation of gland steam at
-labyrinth
-  >This may be due to failure of gland steam condenser exhauster fan or due to higher gland steam pressure.
-• Over filling of tank.
-• Increase in oil temperature will also increase oil volume.
-• During unit shut down all system oil will drain to main oil tank, it can
-cause the high level.
-• Seal oil tank over flow to main oil tank.
-• Due to Instrument malfunctioning.
-11. Describe the lube oil cooler duty changeover, what important
-parameter need to closely watch during this changeover?
-Normally both coolers remained in service. But if there is due to some reason
-1 cooler in service and we have to take 2nd cooler out of service. The
-procedure is as under.
-a. First confirm the cooling water inlet/outlet valves are opened and
-air is purged.
-b. Then slowly open the oil balancing line valve to fill the standby
-cooler
-c. Open vent to confirm air purging.
-d. When oil is coming from stand by cooler and air is purged slowly
-opened the selective valve towards stand by cooler
-e. Close the balance line valve
-f. Standby cooler is in service.
-12. What is our turbine run down time, what indicates if this time
-increases or decreases?
-Turbine run down time is approx. 60 minutes. Increase in its coasting down
-time indicates steam passing from MSV’s / GV’s and lower lube oil viscosity ( it
-may be due to high lube oil temperatures). Decrease in coasting time may be
-due to higher lube oil viscosity (It may be due to lower lube oil temperatures)
-
-Chapter 16
-Turning Gear/ TSI / Turbine Proper
-1. What is the purpose of turning gear?
-Large steam turbines are equipped with a turning gear assembly to slowly
-rotate the turbine and generator rotors during periods of cooling down after a
-shutdown, while warming during startup, and during periods when the unit is
-off-line and on standby. Turbine components, especially rotors, can be
-damaged as a result of thermal stresses when uneven cooling or heating is
-allowed to take place.
-Rotation of the turbine rotors helps even out the internal temperature
-distribution within the turbine shells and internal components with respect to
-the rotor. This helps reduce chances of thermal stress damage, such as rotor
-bowing and subsequently steam seal damage. By slowly rotating, the turbine
-rotors stay in a substantially straight and balanced condition during cooling,
-warming, and standby
-2. What is the start permissive of turning gear?
-The start permissive of turning gear is,
-• Instrument air pressure normal.
-• Bearing oil pressure normal.
-• Hydrogen/stator coolant differential pressure not low.
-• Liquid chamber level not high.
-• GCCC alarm power supply healthy.
-• Gen. Seal oil differential pressure normal 0.3 kg/cm 2
-• Jacking oil pump in service. (<50 kg/cm2)
-3. At what speed turning gear will engage and disengage automatically?
-Turning gear will engage at Zero Speed and will disengage at RPM greater
-than 3
-4. When lube oil solenoid valve will open and how you can provide lube
-oil if solenoid valve fail to open?
-At 100 RPM lube oil solenoid valve opens and if it fails to open , its bypass
-valve is also provided, it should be opened to maintain lube oil supply
-5. What do you understand about eccentricity and why it is important to
-bring eccentricity normal before rolling?
-Eccentricity is distance between central axis of rotation and actual axis of
-rotation in turbine
-When a turbine rotor has temporary bowing, it is likely to have high vibration
-during startup and until it straightens out with heat. The eccentricity probe
-system basically shows whether the eccentricity is consistent with previous
-startups and whether the rotor bowing is stable or changing while on turning
-gear.
-It should be normal before rolling as high eccentricity would indicate a bow in
-rotor and difference between central axis of rotation and actual axis of rotation.
-6. What is differential expansion, what is its normal operating range?
-The difference between rotor and casing expansion is called differential
-expansion. Normal operating range is +15.5 to – 1.7 mm
-7. What are the maximum allowable bearing metal temp and bearing
-drain oil temp?
-• Bearing metal temperature range 107 ( alarm) & 113 ( Tripping)
-• Bearing oil temperature range 85 (alarm).Lalpir/Pakgen Power Plant 54
-CCR Qualification Book
-8. What is the purpose of thrust bearing, what do you understand about
-thrust wear?
-Every turbine has a thrust bearing assembly responsible for keeping the
-stationary and rotating elements in their proper axial relationships. The thrust
-wear protection system monitors the rotor axial position for evidence of thrust
-bearing wear and will alarm and possibly shut the turbine down when the
-thrust bearing fails or might be expected to fail within a short period. The
-turbine thrust bearing assembly holds the rotor and the stationary components
-in their correct relative axial position.
-9. What are the high bearing vibration alarm and trip settings for turbine
-and generator?
-Bearing vibration 125 mm ( alarm) & 250 mm ( tripping)
-10. What are the possible causes of high bearing vibration?
-The causes of high bearing vibration are,
-• Turbine blade broken.
-• High eccentricity.
-• Lube oil temp very high / very low.
-• Bearing misalignment.
-• Lube oil contamination.
-• Sharp load variation.
-• Water induction.
-• Over loading.
-• Critical speed.
-• Instrumentation malfunctioning.
-• Vibration transfer nearby machine.
-• Shaft imbalance.Lalpir/Pakgen Power Plant 55
-CCR Qualification Book
-11. What is the purpose of balance (dummy) piston, where its leak off
-goes?
-Balance piston is provided in steam turbines and more particularly to reheat
-steam turbines, wherein two opposed flow turbine elements are disposed in a
-single casing and are supplied by two separately actuated valve sets supplying
-the two respective turbine elements.
-Common turbine design today for reheat cycle steam turbines often utilize an
-opposed flow configuration within a single casing for the high pressure and
-intermediate pressure turbine elements. For normal operation, this
-configuration is inherently almost balanced with respect to axial thrust along
-the shaft generated by the two opposed flow elements. The residual or net
-thrust developed can be carried by a thrust bearing of reasonable capacity. As
-the thrust bearing size increases, the frictional losses increase, and economy
-dictates a small thrust bearing.
-Under certain conditions, the "control" valves (MSV’s / GV’s) supplying high-
-pressure steam to the high-pressure turbine element may remain open, while
-the "intercept" valves (RSV’s/ICV’s) supplying reheat steam to the
-intermediate pressure element may close. In this event, a transiently high axial
-thrust will be developed by the high-pressure element, and it has been
-necessary to provide a thrust bearing which is large enough to accommodate
-this temporary phenomena. Consequently, it would be desirable to minimize
-the thrust bearing size so as to avoid large losses during normal operation and
-yet be able to accommodate the aforesaid transient conditions.
-Therefore thrust balancing or "dummy" piston at the packing is provided to
-compensate for axial thrust imposed in the opposite direction on the shaft due
-to steam flowing through the blading,
-12. What is turbine soaking, why it is required on 2200 rpm only?
-Heat soaking is the time given for a cold steam turbine to be warmed up so
-that all the internal parts approach operating temperatures before it is put on
-load or before unit synchronization.
-Metals expand and contract at high temperatures and at low temperatures
-respectively. At cold startup mode when turbine first stage metal temperature
-is less than 120 Deg C, temperature of HP-IP shell and of LP Shell is at
-ambient condition and thermal expansion in turbine rotor is negligible.
-After unit synchronization, turbine would have to operate continuously at high
-temperature and high pressure, it’s rotating and stationary parts will expand.
-Therefore before unit synchronization, after completion of Set point 2 i.e. 2200
-RPM, steam flow is sufficient to uniformly increase the temperature of turbine
-components/internals.Lalpir/Pakgen Power Plant 56
-CCR Qualification Book
-13. What is turbine force cooling, when it is required and how you will do
-it?
-Operating steam turbine at low pressure and temperature will cool down its
-internals. It is required to carry out maintenance job on turbine components /
-internals.
-Reduce the unit load to (20% load)
-During the load reduction, main steam temperature shall be reduced by using
-De-SH, burner tilt and GRF inlet damper manually.
-Main burner shall be changed from Stage-B to Stage-A
-When the Turbine 1st stage metal temperature is reduced to 350 ~ 360 deg C,
-turbine forced cooling down can be finished.
-Keep an eye on first stage metal temperature. Main steam temperature should
-always +55 0C superheat
-During forced cooling keep thermal stress, vibration and rotor expansion in
-range.
-1st stage metal temp rate should not increase > 24oC /Hr
-Follow the graph for controlling force cooling parameters
-
-Chapter 17
-Vacuum and Gland Steam System
-1. How many devices are provided for vacuum pulling, explain briefly the
-purpose of each?
-3 type of vacuum devices are provided for vacuum pulling.
-1) Startup Ejector ( Hogging ejector) – Used during startup to establish
-vacuum upto 550 mm of Hg
-2) Main Ejector – Remains in service throughout the unit operation and
-maintains vacuum in condenser
-3) Vacuum pumps – Assist in maintaining vacuum in case of air ingress
-in condenser or as a backup of main ejector.
-2. What is the normal vacuum of condenser, what are the effects of low
-vacuum?
-Normal condenser vacuum is 692 mmHg.
-Effects of low vacuum: -
-• Steam consumption / kWh will increase.
-• Exhaust hood temp. Will increase.
-• Boiler fuel consumption will increase.
-• Heat rate will increase.
-• Over all plant efficiency will drop.
-3. What are the possible reasons of low vacuum, what will be your
-actions in case of vacuum drop?
-There can be one of the following reasons:
-• Due to malfunctioning of steam jet ejector trap.
-• Due to trap vent.
-• Air ingress.
-• High Cooling water temperatures.
-• Inadequate Supply Steam pressure to ejector.
-• Scaling on condenser tubes.
-• High Condenser level.
-• Low Condenser level.
-• Low efficiency of cooling tower.
-• Cooling water flow is less than the requirement.
-• Due to rupturing or damaging of LP turbine rupture disc.
-ACTION:
-• Start vacuum pump
-• Check auxiliary steam pressure.
-• Check main ejector steam and air MOV’s
-• Request area engineer to take area round and check LP turbine
-rupture disks.
-• Cooling water parameters ( CT fans , their frequency)
-• If vacuum continues to drop, drop the unit load till the point vacuum
-becomes normal.
-4. When vacuum breaker will open and close automatically, what type of
-power is provided for this valve, identify the power breaker?
-Vacuum breaker will open on 400 rpm while shutting down the unit and will
-close on 100 mmHg during vacuum pulling in startup.
-Vacuum breaker is DC powered and is located in UPS roomLalpir/Pakgen Power Plant 58
-CCR Qualification Book
-5. What is the role of sealing water in vacuum system, how sealing
-water header pressure being maintained?
-Sealing water is provided to all valves connected to vacuum system, and
-condenser to avoid air ingress through their glands into the condenser.
-An orifice is provided from condensate pumps discharge header to maintain
-the sealing water pressure in secondary header. Pressure can also be
-adjusted by manual isolation v/v.
-6. What is the purpose of gland steam, where gland steam has been
-provided?
-Purpose of gland steam is to provide a positive seal to avoid air ingress inside
-turbine or to avoid steam leakage form the turbine .it is provided on HP and LP
-cylinder glands through labyrinth seal.
-7. What is the gland steam normal header pressure and how it is being
-maintained?
-Normal header pressure is 0.20 to 0.35 kg/ cm2 and it is maintained through
-PCV. Steam is supplied by auxiliary steam header up to 30% load after that
-leak off steam from turbine glands is sufficient to fulfill the requirements
-8. What is the purpose of gland steam exhauster, what will happen if
-running fan trip and standby did not cut in, what will be your actions?
-Gland steam exhauster maintains vacuum > 500 mm H2O to evacuate the
-gland steam before condensation at seals. If steam condenses at seals there
-are chances that this water may mix with lube oil.
-If, for any reason both are not available, then we have provision of a spray v/v
-(water supplied by condensate pump discharge header) on steam path.
-Opening that valve will maintain temperature delta due to which steam flow will
-be maintained.
-9. What is the importance of exhaust hood temp, how vacuum affects
-this temp, at what temp spray will start?
-The likely causes of high exhaust hood temperature are either low condenser
-vacuum or continuous operation at a very low steam flow.
-Exhaust Hood Temperature plays a vital role to save LP turbine blades in the
-last few stages of the turbine. “Exhaust Hood Temperature” is the chief
-criterion for “Condenser Vacuum V. Low” which signifies the lower density and
-lower mass flow rate in the last stages of LP Turbine so the temperature in the
-exhaust hood rises as less heat is removed to the condenser and more stays
-in the hood area (Famously known as churning), which in turn causes un even
-thermal expansion of last stage LP Turbine blades and ultimately damage to
-these turbine blades.
-Condenser vacuum is inversely proportional to condenser exhaust hood
-temperature. Exhaust hood temperatures will increase as soon as condenser
-vacuum drops.
-At 70 Deg C exhaust hood temperatures, exhaust hood spray will open.
-10. What is the normal temp of LP gland steam, how it is being controlled,
-what will your action if this temp start to increase?
-Normal temperature of LP gland steam is 150 to 180 0C It is controlled by
-spray water, which is supplied by condensate pumps outlet.
-If LP gland steam temp start increase then check the behavior of TCV, if it is
-malfunctioning, try to control with bypass iso valve.Lalpir/Pakgen Power Plant 59
-CCR Qualification Book
-11. Explain briefly the procedure to take vacuum system in services?
-Pre-requisites;
-• BCWP (any) in service (for main CP-motor cooling)
-• Main condensate pump (any) in service
->As all vacuum system related valves gland sealing water is
- supplied from main condensate pump header
->Condensate of auxiliary steam from main ejector is used to preheat condensate in Gland steam condenser. In the
-absence of condensate water, gland steam condenser tubes may overheat.
-• Auxiliary steam header pressure is greater than 13 kg/cm2
-• Turbine on turning gear
-• Instrument air pressure is normal
-• Vacuum system condensate trap bypass valves open (local activity to
-remove any accumulated condensate)
-Action On CRT:-
-Confirm following equipments status as
-• Condenser vacuum breaker v/v ON AUTO.
-• Gland steam condenser exhauster fan ON AUTO.
-• Gland steam PCV inlet MOV ON AUTO.
-• Startup ejector air & steam MOV ON AUTO.
-• Main ejector air & steam MOV ON AUTO.
-• Both vacuum pumps subsequence LOCK.
-Give “ON” command from turbine sequence master. Vacuum system will start
-as per following steps.
-1) Selected Gland steam exhauster fan will start as per priority.
-2) Gland steam MOV will open about 15 to 20 % to warm up the system.
-3) After warming up, gland steam MOV will full open , PCV will take
-control and maintain the pressure between 0.35 to 0.40 kg/cm2.
-4) Startup ejector steam side MOV will open, and then airside MOV will
-open.
-5) At 100 mmHg condenser vacuum, vacuum breaker MOV will close.
-6) It is good practice to start both vacuum pumps to achieve the vacuum
-easily and efficiently.
-7) At 550 mmHg condenser vacuum start up ejector will cut out and main
-ejector will take load automatically.
-8) At 550 mmHg condenser vacuum AOP will cut in and TOP will cut off
-automatically.
-9) AT 650 mmHg turbine by pass open permissive will appear.
-
-Chapter 18
-Condensate System
-1. How you will start the 1st condensate pump?
-• Fill condenser up to normal level (Zero mm)
-• Start BCWP for its motor cooling water
-• Make sure instrument air pressure is normal
-• Lock condensate pump sequence.
-• Put condensate pump’s recirculation valve on auto
-• Coordinate with area engineer (He will partially close its discharge
-valve to save motor from drawing high current)
-• Give start command from pump control loop plate
-2. What is the purpose of minimum flow valve, when it opens and close?
-The purpose of minimum flow recirculation is to keep the sufficient flow
-through steam jet air ejector and gland steam condenser during unit start up
-condition for steam cooling.
-It has interlock with de-aerator LCV. When de-aerator LCV starts to open it
-starts to close. When de-aerator LCV closes below 20%, condensate pump
-recirculation starts to open
-3. How hot well level is being maintained, what are the effects of low and
-high hot well level?
-Hot well level can be maintained by the condenser makeup water (LCV)
-through condensate storage tank (normal lineup) or through demin pumps
-common header bypassing condensate storage tank (Shutdown / Startup
-lineup).
-At hot well level very low condensate pumps will also trip on –200 mm.
-At very high level spill over will open to condensate storage tank in order to
-maintain level.
-4. What is the purpose of condensate storage tank, how its level is being
-maintained?
-The purpose of condensate storage tank is to hold the sufficient amount of
-makeup water to maintain condenser level.
-In case of high hot well level it absorbs the water through spill over v/v.
-Its level is maintained from the demin water pumps header through LCV.
-5. Why spill over valve is provided, when it opens and closes, where spill
-over water will go?
-Spill over v/v is provided to maintain condenser / hot well level.
-It opens at 250 mm condenser level and closes at 100 mm. Spilled water goes
-back to condensate storage tank.
-6. What are the systems using condensate water?
-Systems using condensate water are,
-• Boiler feed water storage tank (DA Storage Tank).
-• For gland sealing of condensate pumps / vacuum pumps / valves.
-• Exhaust hood spray.
-• LP gland steam spray.
-• HP by pass spray.
-• BCP motor cavity filling.
-• Condensate pump strainers back washing.Lalpir/Pakgen Power Plant 61 CCR Qualification Book
-7. When the 2nd condensate pump will cut in and cut out on sequence?
-At 145 MW Gross condensate pump will cut in increasing load.
-At unit load less than 135 MW gross , 2nd condensate pump can be stopped
-
-Chapter 19
-Circulating & Cooling Water System
-1. What is the start permissive of a CWP?
-Start permissive of a CWP has only two conditions
-Any (A/B) CWP lube water pump On and CWP lube water outlet pressure is
-normal
-2. What are the steps when a CWP start command given from Main or
-sub sequence?
-Pre-checks
-Lube water pump for CWP’s bearing is in service and its pressure /flow is
-normal
-CWP Start command from main Sequence
-Go to Aux Sequence 1 screen
-Select Aux 1 Sequence “Circulation water sequence Master group”
-“Lock” the sequence
-Put desired pump and its discharge valve control mode on “auto”
-Set priority as per desired pump
-Check On permit on main sequence
-Unlock the main sequence.
-Give on command to sequence.
-This will give on command to priority selected CWP
-CWP Start command from Sub Sequence
-Go to Aux Sequence 1 screen
-Select Aux 1 Sequence “Circulation water sequence Master group”
-“Lock” the sequence
-Put desired pump and its discharge valve control mode on “auto”
-Give on command to desired pump from its sub sequence.
-This will give on command to selected CWP
-3. What are the sources of lube/ cooling water for CWP bearing?
-There are two sources of lube/cooling water for CWP
-1) CWP cooling water pump taking suction from CT basin
-2) Discharge line from CWP’s discharge line.
-4. What is the normal temp difference across the condenser, what
-indicates the increase or decrease of this temp difference?
-Differential temp across the condenser is 10 ~ 15 0C
-Increase in temperature indicates that cooling tower efficiency is not up to
-mark.
-• Effect of Humidity and atmospheric temp.
-• Restriction of flow in cooling water.
-Decrease in temp indicates that there is some scaling inside the tubes or on
-outer surface of the tubes.
-• Maximum CW flow at minimum requirements.
-• More Cooling tower fans are in service than required.
-5. How cooling towers efficiency affects the unit heat rate?
-The primary task of a cooling tower is to reject heat into the atmosphere. At
-our unit, cooling water absorbs heat from steam through condenser and rejects
-it into the atmosphere in the continuous cycle.
-If for any reason, it absorbs less heat or rejects less heat into the atmosphere,
-it will not effectively condense steam and hence it will increase backpressure
-on turbine. This will increase fuel flow and have –ve impact on unit heat rate.Lalpir/Pakgen Power Plant 63
-CCR Qualification Book
-6. Explain condenser tube leak detection and plugging? Is it possible at
-minimum load, write the procedure for it?
-Condenser Tube Leakage Detection
-• Reduce unit load <50%.
-• Isolate half portion of condenser cooling water.
-• Drain the water Box.
-• Perform LOTO
-• Open inlet and outlet cooling water side man holes.
-It is preferable to drain the water boxes and open the access doors while the
-condenser tube sheet is still hot. This helps leak detection by drying off the
-outside of the tube sheet faster.
-Method-1 (Off load)
-• Fill the condenser shell side through the hot well
-• Monitor the level as it rises.
-• Continue filling until the level is above the upper tubes
-• Inspect the tube sheet for leaks from the tubes or from the tube-to-
-tube sheet joints
-• Mark any leaky points.
-Method-2 (On load)
-• Try to detect leaky tube with the help of candle flame.
-• Where the candle flame moves towards tube, mark the tube.
-• Confirm these suspected leaky tubes from the other end of condenser
-with the same candle flame procedure.
-Defective Tube plugging
-• Insert a plug (brass or nylon) into the tube end and drive it in lightly
-	using a hammer until snug.
-• Insert a plug into the opposite end of the tube and drive it in lightly.
-• Both ends of a defective tube must be plugged.
-
-Chapter 20
-Canal Water System
-1. What are the start permissives of canal water pump, describe the
-procedure to start the canal water pump from sequence?
-Permissives:-
-• A-Canal water pump cooling water “ON” or
-• B-Canal water cooling water pump “ON”
-• A-Canal water pump cooling water flow < Low “NOT”
-Start up:
-• Lock the main sequence.
-• Lock the sub sequence.
-• Select the settling basin.
-• Put selection on RAINY.
-• Select WELL & CANAL.
-• Check cooling water pump on “AUTO”
-• Check the selected pump on “AUTO”.
-• Make sure that pump suction and discharge v/v are open in field.
-• Recirculation v/v should on “ AUTO”. (Its setting is on 2.1bar).
-• Settling basin LCV should on AUTO.
-• Unlock the sub sequence.
-• Unlock the main sequence.
-• Give “ON” command.
-2. How well water sequence works, discuss the procedure to change
-canal water to well water and vice versa?
-Shifting from Canal Water to Well Water
-• Lock the main sequence.
-• Lock the sub sequence.
-• Put selection on “DRY”
-• Put line selection on “WELL LINE”.
-• A/B settling basin level should be “NORMAL”.
-• Make sure that the discharge v/v is open for the selected pumps.(local check)
-• Stop canal water pump
-• Start well water pump as per cooling tower makeup and filter water basin filling
-requirement
-As well pumps conductivity and calcium hardness differs from each other, so their priority
-is set as per chemical analysis in Lab. To follow their priority, they are kept on manual and
-started as per requirement.
-Shifting from Canal Water to Well Water
-Pre-checks (Local Activity)
-Clarifier and DMF system is in service and Canal level is normal
-• Lock the main sequence
-• Lock subsequence of canal water pumps
-• Put selection on Rainy
-• Put main pump and its cooling water pump on auto
-Stop well water pumps
-Unlock & give on command to canal water pump from sub sequence.
-Unlock & give on command to main sequence.Lalpir/Pakgen Power Plant 65
-CCR Qualification Book
-3. Which settling basin can be used for both units, explain how you can
-select this basin with unit 2?
-Settling basin B can be used for both units, to select it for unit 2, open its LCV
-from Unit 1. Ask area engineer to divert well water pumps of Unit 2 towards
-settling basin B
-
-Chapter 21
-Chemistry
-1. What is the importance of chemistry in a power plant?
-Chemical parameters directly affect the plant life as they are important to avoid
-corrosion, scaling, silica, pitting, pH control and other similar parameters.
-Plant outward waste chemical parameters are also important to reduce waste /
-excess usage of chemical and to protect the environment.
-2. What type of chemical dosing is being done in feed water system,
-what is the purpose of each, indicate the different dosing points?
-The different types of chemicals use for feed water system are,
-Hydrazine :
-It is helpful in scavenging of oxygen & dissolved gases.
-Hydrazine dosing points are situated after de-aerator.
-• One point is given for the filling of economizer through demineralized
-water in startups (by adding spool piece on boiler 5th floor).
-Ammonia:
-Its purpose is to control the pH
-Ammonia dosing points are situated right after de-aerator at discharge of
-condensate pumps.
-3. What is the role of Deaerater in chemistry control, how it works?
-D/A is open tray type heat exchanger where oxygen other non-condensable
-gases are removed by thermal de-aeration.
-Condensate water is fed from the top of de-aerator and de-aerating
-Steam is supplied from the bottom.
-Condensate water is distributed in fine droplets over the steam through trays
-and its path is diverted through baffle plates. This phenomenon causes flash
-between steam and condensate and thus non condensable gases get
-separated from water.
-4. What do you know about hideout phenomenon?
-Sodium tri phosphate is being used in the boiler to dissolve the silicates.
-In high pressure boilers sodium tri phosphate sticks with the walls on high load
-if there is uneven temperature distribution. Therefore in normal tests it cannot
-be detected. At low load the sticky layer of phosphate can be dissolved in the
-system and can be measured
-5. What is the purpose of Vanadium Inhibitor dosing, what type
-Vanadium Inhibitor is being used in Lalpir?
-Vanadium Inhibitor is Magnesium based solution and is injected in the fuel
-header just before entrance in boiler. It reacts with vanadium and converts into
-vanadium penta oxide due to which vanadium sticking temperature range
-increases and gets carried over with flue gases into stack. As a result it
-increase the boiler efficiency and increase the life of air heaters as pH of soot
-increases from 3.5 to 5.0 due to which it does not forms the sulfuric acid at air
-heater on cold end.
-6. What alarms and indications relating to chemical dosing available on
-CRT?
-• Low / High pH. (Condensate pump / sampling rack / cooling water system).
-• Conductivity high.
-7. What is the first indication of condenser tube leak?
-Condensate conductivity increase is the first indication. (Condensate
-conductivity normal range is 2 to 6 micro siemens)Lalpir/Pakgen Power Plant 67
-CCR Qualification Book
-8. What are the pH and conductivity limits in condensate water, feed
-water, drum water and main steam?
-Parameter pH Conductivity (Micro
-Siemens)
-Condensate Water 8.8 ~ 9.2 2 ~ 6
-Feed Water 8.8 ~ 9.2 2 ~ 6
-Drum Water 9.0 ~ 9.8 <38
-Steam 8.8 ~ 9.2 2 ~ 6
-9. What is the silica limit in make-up water, condensate water, drum and
-main steam?
-Make up Water, Cond. Water, and Main Steam silica should be less than 20
-ppb & drum silica should be less than 200 ppb
-10. What is the purpose of N blanketing, what are the systems where N
-2 2
-blanketing facility has been provided?
-N2 blanketing is used for preservation purpose. Positive pressure of N2 is
-maintained to avoid the presence/ingress of air, which can cause the
-corrosion.
-N is also used to purge out the inflammable hazards from system.
-2
-N is provided on Boiler, D/A, HPH and HFO header.
-2
-
-Chapter 22
-Generator and Auxiliaries
-1. What is the technical data of our generator, what parameters relating
-to generator are available on CRT?
-Rating 365 MW
-Nominal rated capacity at 4.5 bars abs. hydrogen pressure 430,000 kVA
-Power factor 0.85 lagging
-0.90 leading
-Rated Hyd. Pressure 4.5 bar abs
-Number of phases 3
-Number of poles 2
-Frequency 50 Hz
-Rated Speed 3000 rpm
-Terminal voltage 24 Kv
-Excitation System. Static excitation.
-Parameter on CRT:-
-• Active Power
-• Reactive Power
-• Apparent Power
-• Power Factor
-• Different core temp.
-• Stator and rotor temp.
-• Hydrogen pressure.
-2. Discuss the capability curve of generator, what are the effects if we go
-beyond this curve?
-If we look at the capability curve it is drawn on x-axis and y-axis. On y-axis
-there is MW and on X-axis there are MVAR leading and lagging sides are on
-left and right sides respectively.
-There is one white parabolic cure showing the extreme MVAR limits and blue
-line reflects the MW limits, along with these lines dotted lines indicate power
-factor and curser position shows the present running status point.
-3. Discuss in detail how to synchronize the generator with system?
-If we will be on beyond the limits on leading side then our synchronous tie with
-system will be very weak and any minute deflection in system can cause de
-synchronization and ultimately we will be cut off from the system as generator
-breaker will open. Before this following alarms will appear.
-a) AVR limit exceeds.
-b) AVR below manual restriction.
-If we will be on positive side beyond the limits then excitation current will start
-to increase which will result in increase of rotor temperatures.
-On top of the curve if we will exceed the MW then generator load high alarm
-will appear. Even then if we will go up to 380 MW (or load will increase 10% of
-full load due to system problem), then there will be run back up to 300 MW.
-4. What interlock is provided for generator field breaker 41E to be closed
-during unit start up and why?
-Generator isolator has to be closed before closing the generator field breaker.Lalpir/Pakgen Power Plant 69
-CCR Qualification Book
-5. Why hydrogen is being used as a cooling media in generator, what is
-the maximum Allowable temp of cold gas?
-Hydrogen has good heat transfer characteristics and has good heat transfer
-coefficient as compared to air. It removes heat from generator through
-hydrogen coolers. It has less windage losses and light in weight. Allowable
-Temp limits:
-Normal set point is 400 C.
-High alarm on 47 0C.
-High . High alarm at 50 0C.
-6. What is the purpose of seal oil system, what is the importance of seal
-oil/ H2 differential pressure?
-Seal oil system is provided for proper sealing of hydrogen in generator casing
-so that it may not be in direct contact with air.
-Seal oil pressure is higher than hydrogen and its differential is about 0.8 bar
-which does not allow the hydrogen to come out of the generator casing and
-avoid air ingress to avoid any explosion.
-7. What is the purpose of stator coolant water, what is the importance of
-conductivity of this system and how it is being maintained?
-The purpose of stator cooling water is to provide a cooling media for stator as
-due to high current flow its temp increases.
-Stator cooling water is demineralized water. Due to low conductivity (< 0.5
-micro.S/ cm) it is bad conductor and there are no chances of any current flow.
-Its conductivity is being maintained by providing polisher (mixed bed) in close
-loop. Approx. 30% of total water passes through this polisher
-8. How you will come to know if there is cooling water leak inside
-generator casing?
-There are no chances that cooling water will leak inside the generator as
-hydrogen pressure is kept greater than cooling water pressure. One indicator
-of leakage on stator coolers is that hydrogen pressure will drop frequently
-If hydrogen seal oil system is working efficiently and on cooling water cycle
-detraining chamber is releasing the gas frequently it means that gas is mixing
-somewhere in water and the most critical area is stator itself
-9. What are the generator protections, explain briefly?Lalpir/Pakgen Power Plant 70
-CCR Qualification Book
-Device / Function
-Relay
-Number
-21 Distance — Backup for system and generator zone phase faults.
-24 Volts/Hz — Protection for generator over-excitation.
-25 Synchronism Check — Synchronism verification when
-paralleling
-27 Under voltage — Under voltage protection.
-27-3N Under voltage — Third harmonic under voltage protection.
-32 Reverse Power — Anti-motoring protection
-400 Loss-of-field — Protection for failure of the excitation system,
-reactance based.
-40Z Loss-of-field — Protection for failure of the excitation system,
-impedance based.
-46 Current Negative Sequence — Unbalance current protection
-47 Voltage Negative Sequence — Unbalance voltage protection
-49 Temperature — Stator thermal protection
-51 Time Overcurrent — Phase Overcurrent protection
-51G Time Overcurrent — Ground Overcurrent protection
-51 N Time Overcurrent — Neutral Overcurrent protection
-51V Time Overcurrent — Overcurrent with voltage-controlled or
-voltage-restrained. Backup protection for system or generator
-phase faults.
-59 Overvoltage — Generator overvoltage protection for phase
-and/or ground faults.
-59N Ground Overvoltage — Generator ground fault protection
-60 Voltage Balance — Detection of blown voltage transformer fuses
-(loss of phase)
-62 Time Delay — Provide a time delay for either the opening or
-closing of a contact.
-63 Pressure Switch — Transformer overpressure fault protection
-64 F Field Ground — Detection of a generator field ground
-78 Out-of-Step — Protection for out-of-step or pole slip conditions
-810 Over frequency — Protection for over frequency
-81 U Under frequency — Protection for Under frequency
-86 Lockout Relay — A latching trip relay or device that requires an
-operator to reset.
-87G Differential — Generator current differential protection
-87N Differential — Ground differential protection
-87T Differential — Transformer current differential protection
-10. What is the purpose of lockout relay, where it is located?
-Gen. lock out relay will operate in case of any generator protections actuates
-and it provides easiest path for track down.
-It is situated on mezzanine floor inside relay room.Lalpir/Pakgen Power Plant 71
-CCR Qualification Book
-11. What is reverse power, what is its setting on our unit?
-Reverse power is a type of protection which protects the generator from
-motoring effect. This protection is provided for the turbine to avoid windage
-losses. It will operate at 3 MW generator load (approx.).
-12. Why and how Generator neutral is grounded?
-Generator neutral is ground through NGR
-
-Chapter 23
-Electrical System
-1. What are the voltage limits of 220kV system? What is our role in
-controlling this voltage?
-As per clause 1.3 of Schedule 2 of PPA , Lalpir / Pakgen is designed to
-operate within ±10% on the 220kV high voltage system. So 220kV voltage limit
-is between 198 kV to 242 kV.
-The Complex is subject to tripping if voltage fluctuations outside the ranges
-stated in PPA schedule 2 clause 1.3(b) occur
-GSU is equipped with on load tap changer. Increasing its tap will decrease
-220kV system voltages and decreasing its tap will increase 220kV system
-voltages.
-Operation of GSU tap changer is recommended in consultation with Shift
-manager and NPCC (If required)
-2. What is the 220kV lines maximum capacity?
-1200 Amperes is the maximum capacity of each 220kV line
-3. Draw a single line diagram of 220kV switchyard.
-4. What do we mean by a Bay? How many bays are there in Lalpir
-220kV switchyard?
-In electrical terminology, combination of connecting mechanism of a circuit to
-other high voltage bus bar is termed as bay. Each bay consist of a circuit
-breaker, isolator, and CT’s & PT’s (optional)
-There are total 8 bays in each unit’s switchyard. (5 on bur bars , one on GSU ,
-and one on each 220kV line)
-5. What is the function of Wave Trap?
-Switchyard components are designed to operate at 50 hz frequency.
-Frequency higher than 50 Hz ±5% may damage the components.
-To prevent these high frequency waves from entering the switchyard, wave
-traps are used to create high impedance to the high frequency waves (typically
-carrier wave high frequencies)Lalpir/Pakgen Power Plant 73
-CCR Qualification Book
-6. What is the purpose of Current Transformer?
-Current transformers are used on high voltage transmission lines to produce
-an alternating current in its secondary side in proportional to the AC current in
-its primary side. Measuring instruments can be used on its secondary side.
-7. What is the purpose of Potential Transformer? What is CCVT? Why
-CCVT is required and how many CCVTs are there in Lalpir 220kV
-switchyard?
-Potential Transformer or Voltage transformer or Capacitor-coupled voltage
-transformer (CCVT), is a transformer used in power systems to step down
-extra high voltage signals and provide a low voltage signal, for metering or
-operating a protective relay.
-There are total 6 CCVT (PT’s) in Lalpir/Pakgen switchyard.
-1 on each line, bus bar and on GSU , SUT
-8. What is the function of Isolators? What interlock is provided with
-Circuit Breaker and its associated isolators?
-Isolator is a mechanical device to connect or disconnect an electrical circuit
-from other electrical circuit. They are of two types, On Load and Off Load.
-At Lalpir and Pakgen they are of Off Load type and interlock is provided to stop
-their on-Load operation.
-In addition to their interlock with circuit breaker, Isolators on Bus Bar 1 have
-other interlock with the open/close position of the respective bay’s Bus Bar 2
-isolator. Either bus bar 1 isolator can be closed or bus bar 2. No two isolators
-at same bay can be closed at same time.
-9. How the line side disconnect switch (isolator) is interlocked with line
-ground switch and why?
-Ground switch also known as earthing switch is used to ground the residual
-charge in power lines after disconnecting the line from source. When a circuit
-is broken or open by the circuit breaker and Isolator, there is a residual charge
-remaining in the circuit. So to discharge the charge earthing switch is used.
-Mechanical interlock is provided on all 220kV line isolators to prevent the
-closing of earthing switch in closed line isolator operation. To close the
-earthing switch, respective line isolator must have to be in open position.
-This interlock is provided to avoid human error in closing energized line’s
-earthing switch.
-10. What is the purpose of Bus Coupler?
-Bus coupler is a combination of isolator and circuit breaker to connect one high
-voltage bus bar to the other high voltage bus bar
-11. What type of Circuit Breakers is provided in 220kV switchyard? What
-quenching media is used and what is operating mechanism of these
-breakers?
-3 pole single chamber Air operated circuit breaker is used in 220KV switch
-yard. SF6 gas is used as quenching media in 220KV breakers
-12. What are normal pressure of SF6 and Air used in 220kV breakers?
-
-Normal pressure of SF6 gas is 6.5~7 bar and normal air pressure is 1.7~2.0
-bar.Lalpir/Pakgen Power Plant 74
-CCR Qualification Book
-13. What will be 220kV breaker state if
-a. SF6 pressure is low low
-b. Air pressure is low low
-The SF6 is the insulation and arc-quenching medium. 220kV circuit breaker
-will be un-responsive / inoperative if SF6 pressure is low low as in case of
-operation it is quite possible that insulation and arc quenching medium is
-insufficient.
-220kV circuit breaker will open if air pressure is low low.
-14. Why DC power is supplied in 220kV switchyard?
-110V DC control power is supplied for switching of 220kV isolators and
-breakers.
-15. Why dual power (AC) is provided in switchyard?
-In case of power failure or any maintenance activity on respective unit AC
-power supply , alternate AC supply is provided from the other unit to operate
-isolators, circuit breakers.
-16. Explain the procedure of isolating and grounding a 220kv line?
-Communication and approval from NPCC is required for such activity.
-• If unit is in service or SUT is in service, Confirm 2nd line load. It should
-be normal.
-• Confirm Close position of bus coupler or energized line must be
-connected on same bus as that of GSU/SUT.
-• Open line controlling circuit breaker.
-• Open respective circuit breaker’s line isolators.
-• Confirm de-energisation and isolation from 2nd end (NPCC Hot line/fax)
-• Confirm “Zero Voltage” on CCR Switchyard Control Panel.
-• Close ground isolator.
-17. How you will changeover aux load from UAT to SUT and vice versa,
-what is the generator load limitation with this changeover?
-Switchover / changeover from UAT to SUT and vice versa is recommended at
-Generator load greater than 50 MW.
-Steps to changeover from UAT to SUT and vice versa
-• Confirm generator load is greater than 50 MW
-• Press 52/1ABT (to take SUT in service) or press 52/UAT1 ( to take UAT
-in service) on synchro panel
-• “Synchro Check Relay” on synchro panel will match the conditions of
-both supplies and on matching the conditions , it will give “1” indication,
-indicating that all parameters are in synchronization.
-• Pull and turn clockwise 52/UAT1 lever (To take UAT in service ,
-52/1ABT-11kV bus bar tie breaker will trip automatically) or 52/1ABT (To
-take SUT in service , 52-UAT1 breaker will trip automatically) on
-synchro panel
-18. What is the purpose of 11kv inter tie, when it can be used, what is
-load limitation with this inter tie?
-Both units 11kV bus bar B is inter-connected with 11kV breaker to support
-other unit auxiliary load in case of power unavailability.
-11kV inter unit tie breaker 2BCA18 is of same rating as of 11kv bus bar A&B
-tie breaker 52/ABT. However, if other unit is also shut down, it is
-recommended to operate minimum possible auxiliaries to avoid excessive
-import and keep MDI within range.Lalpir/Pakgen Power Plant 75
-CCR Qualification Book
-19. After a complete blackout, what are the important things to be
-checked, how you will normalize the system?
-• Check that generator D.C. seal oil pump (DC Lube oil pump will cut in by its
-pressure switch and it will take some time) & D.C. operated turbine lube oil
-pump have cut in on AUTO. If not then start by manually from CRT or
-annunciator panel in CCR.
-• Make sure that Emergency Diesel Generator has cut in on auto & 400 volts
-Emergency Services MCC has been energized. If EDG not cut in on AUTO then
-energize 400 volts Emergency Services MCC as per procedure.
-• Make sure that generator breaker is open, if not open it manually.
-• Make sure turbine is coasting down.
-• Make sure that boiler is on natural purging i.e. all dampers are open to remove
-combustibles from furnace.
-• Be ready to open LP turbine manholes to avoid over pressurization.
-• Open economizer recirculation valve manually to provide circulation.
-• If service air is not available, arrange to rotate the air heaters manually.
-• Change over DC equipments to AC as emergency bus energized from EGD.
-• Watch BCP cavity temperatures and arrange service water by opening tie valve
-or by starting service water pump.
-• Close ejector steam isolation valve to avoid hammering in ejector condenser.
-• Close gland steam isolation valve to avoid hammering in gland condenser.
-• Open vacuum breaker valve as turbine speed reaches to 1800 rpm to reduce
-coasting down time.
-• One of the CRE must Contact with NPCC to ask him for restoration of power
-supply.
-• Seek help from E&I along with area engineer, check which relays operated and
-why? In the light of operation of these relays, make decision to energize the
-electrical system.
-• Check that stator coolant pump (Stator coolant pumps are not supplied from
-emergency bus, it will be started after restoration of normal power) , Boiler A.C.
-cooling fan, Service water pump, Lube oil tank vapor extractor fan , GRF turning
-motor, Air Heaters rotor drives are in operation. All these motors to be started
-manually after energizing emergency bus.
-• Ask area engineer to start Service air compressor-A
-• Have a close look on TSI, turbine exhaust hood temperature, Turbine drains,
-H.P. turbine by pass temperature, boiler drum level.
-• Determine the reason of tripping, if CRE is satisfied & E& I give go ahead then
-after coordinating with NPCC close the 220 K.V. lines breaker D3Q1& D5Q1.
-(Lock out relay need to be reset before closing the 220 KV lines and Lines will
-be closed through Synch check.)
-• After restoration of power, take extra care for filling the drum with very slow rate
-to avoid stress in economizer which is at about 350 C and feed water
-temperature is already low. Try to maintain filling rate 30 to 40 t/h
-• Watch drum pressure carefully and if it comes down very fast during hot
-condition, there are chances of hammering in economizer.
-NOTE: Actions taken should be deliberate, in a logical manner, neither
-rushing nor causing undue delay. Nothing should be taken for granted.
-• Have a look that SUT 220 K.V. breaker D2Q1, its related isolators D2Q11 or
-D2Q12 & D2Q10 are in closed position. (Lock out relay need to be reset before
-closing the SUT 220 KV breaker and breaker will be closed through Synch
-check.)
-• Now come at the unit synchronizing panel & synchronize the SUT 11 K.V
-incoming breaker 1BCA 16 (52/ SUT1). (Lock out relay in 11KV room need to
-be reset by closing SUT 11 KV breaker.)Lalpir/Pakgen Power Plant 76
-CCR Qualification Book
-• Close 11 K.V. breaker 1BBA17 & 1BCA13 feeding 11 K.V. unit switch gear 1-C
-& 1-D
-• Asked area Engineer to Close 11 K.V. breaker 1BBA 45 feeding LalPir
-community.
-• After coordination with area engineer close 11 K.V.breakers located at 11 K.V.
-UNIT SWITCH GEAR 1B & supplying as follows.
-• 1BCA20 administration building transformer 0T7
-• 1BCA26, unit common –B transformer 1T6
-• 1BCA12 , boiler/turbine B transformer 1T4
-• 1BCA 14 raw water intake – B transformer 1T2
-• Now come at 11 K.V. UNIT SWITCH GEAR 1A & close 11 K.V. breakers as
-follows,
-• 1BBA20 unit common A transformer,
-• 1BBA18 boiler / turbine –A transformer
-• 1BBA16 feeding raw water intake –A transformer.
-• Now come at MCC page, close 400 volts incoming breakers as follows,
-• 1BFC20GS101F unit common motor control center 1A
-• 1BFC48GS108F unit common motor control center 1B. Lighting on the
-plant will be available.
-• 1BFK13GS104F Raw water intake motor control center 1-A
-• 1BFK41GS101F raw water intake motor control center 1-B.
-• 0BHA11GS201F feeding administration building 400 volts MCC. (This
-breaker normally do not open on under voltage)
-• Open Boiler / Turbine Power Center 1A, 1B Page at CRT.
-• Close incoming breaker 1BFA20 for Boiler Turbine Power Center 1-A
-1BFA10.
-• Close incoming breaker 1BFA50 for Boiler Turbine Power 1-B 1BFA40.
-• Check & Close following 400 volts breakers located at Boiler Turbine
-Power Center Buses 1A &1B.
->1BFA18 Feeding Boiler 400 volts MCC 1A 1BFD10.
->1BFA16 Feeding Turbine 400 volts MCC 1A 1BFE10.
-
->1BFA42 Feeding Boiler 400 volts MCC 1B 1BFF10.
->1BFA46 Feeding Turbine 400 volts MCC 1B 1BFG10.
-
-(These breakers do not open on under voltage)
-Make sure by monitoring the amperes on CRT or by asking area / electrical
-engineer that Boiler, Turbine MCC 1A & 1B have been energized.
-• Open 11 K.V. Unit Switch Gear 1C & 1D page at CRT & coordinate with BOP
-Engineer. Close following breakers located at 11K.V. Unit Switch Gear 1C & 1D
-bus 1BBA40 & 1BCA40 respectively.
->1BBA46 Water Treatment -A transformer 1T9.
->1BBA44 Cooling Tower “A” Transformer 1T11.
->1BCA42 Cooling Tower “B” Transformer 1T12
->1BCA44. Water Treatment -B transformer 1T10
-
-• Open Cooling Tower Power Center 1A, 1B page at CRT. After confirming that
-cooling tower transformers 1T11 & 1T12 have been energized & 400 volts are
-appearing at their secondary side.
-• Close 400 Volts incoming breaker 1BFB16 supplying Cooling Tower
-Power Center Bus 1-A 1BFB10.
-• Close 400 volts incoming breaker 1BFB42 supplying Cooling Tower
-Power Center 1-B 1BFB 40.
-Close following 400 Volts breakers located at Cooling Tower Power Center 1A &1B.Lalpir/Pakgen Power Plant 77
-CCR Qualification Book
-1BFB24 Cooling Tower 400 Volts MCC 1A.
-1BFB50 Cooling Tower 400 Volts MCC 1B.
-Ask area Engineer to make sure from Local that Cooling Tower MCC 1A &1B have
-been energized.
-Open water treatment MCC page at CRT. After making sure that Water Treatment
-transformers 1T9 & 1T10 have been energized, close following breakers.
-• 1BFJ12GS108F 400 Volts incoming breaker for Water Treatment
-MCC1-A 1BFJ10.
-• 1BFJ48GS108F 400 Volts incoming breaker for Water Treatment
-MCC1-B 1BFJ40.
-• Normalize the 400 volts Emergency Services MCC 1BMA10 as per procedure
-20. How you can control 11kV voltage?
-21. aaa
-22. What do you understand about ATS, what are the three incoming
-sources and which bus it is supplying?
-ATS stands for Auto Transfer Switch and it has three incoming sources:
-a. Primary ATS, source is Boiler Turbine Power Center-A
-b. Secondary ATS, source is Boiler Turbine Power Center-B
-c. Third source is Emergency Diesel Generator.
-23. Explain briefly about DC system and UPS?
-DC System
-DC bus is energized through voltage compensation device being fed from Plant DC
-Distribution panel A & B.
-Plant DC distribution panel A&B has dual power source.
-a) Plant battery charger A&B , C&D
-b) 110 Cell 3400 Amp hr plant battery bank for each distribution panel
-c) Plant battery chargers are fed from Emergency Service Bus bar through
-ATS.
-DC source is has following main services:
-a. Switch yard.
-b. A different protection supplies.
-c. Interlock supplies.
-d. DC seal oil pump.
-e. DC lube oil pump. (EOP)
-f. DC jacking oil pump.
-g. DC cooling fan.
-h. DC lights.
-UPS System:
-UPS-Uninterrupted power supply, system provides a reliable, regulated, filtered &
-uninterrupted 110V, 50Hz, single phase AC electrical power to essential plant
-auxiliary & low voltage load & control system.
-In addition, it provides for a safe unit shut down in the event of a unit power system
-blackout.
-“110V , 50hz AC essential services distribution panel” is being fed from Plant DC
-distrubtion panel A&B through primary and secondary UPS. In addition to this ,
-“110V , 50hz AC essential services distribution panel” is also supplied with third
-source i.e regulating transformer which is being fed directly from emergency bus
-bar.
-UPS system has following main consumers.
-a. APC
-b. DEH
-c. SEQ-1
-d. SEQ-2
-e. BMS
-f. DAS
-g. IPU
-h. ALARM PRINTERS
-i. OPS
-
-Chapter 24
-Turbine Trips
-1. Discuss the various trip signals that will cause to trip the turbine?
-The various trip signals which causes to trip the turbine are,
-• Bearing vibration very high. 250 mm.
-• Rotor position abnormal. ±1 mm.
-• Lube oil pressure very low 0.5 kg/cm2
-• Condenser vacuum very low. 535 mm Hg.
-• Turbine bearing temp. very high 113 C.
-• Generator Trip.
-• Boiler trip.
-• Manual Trip.
-• Remote trip.
-• Over speed. 110 % & 111 % of normal speed.
-2. What are your actions on turbine trip?
-The actions on turbine trip are,
-• First check, gen. Breaker and gen. Excitation breaker open.
-• Check MSV, ICV & RSV fully close.
-• Turbine all drains should open.
-• Extraction NRVS should close.
-• Check turbine speed is coming down.
-• AOP should start at 2950 rpm.
-• Stop one CW pump and CT fans.
-• Check JOP, it should cut in at 800 rpm.
-• At 400 rpm give off command to gland steam sequence.
-• TOP cut in at 100 rpm and AOP cut off on auto.
-• At zero speed turning gear should cut in on auto.
-3. What happens to turbine when turbine trips?
-When turbine trips, Generator breaker opens and unit is no more synchronized
-with the system. In synchronous condition, its RPM are controlled by frequency
-and load as per following formula.
-Ns=120f/P, where Ns is the number of turns/speed in RPM, f is frequency and
-P is the number of poles.
-In unsynchronized condition, there are chances that turbine RPM may
-increase beyond safe limits, therefore its controlling valves (MSV, GV, RSV,
-ICV) will close to reduce its speed.
-4. Discuss the conditions that will permit the turbine to reset?
-The conditions that will permit the turbine reset are,
-• MFT reset.
-• Gen. Lock out relay reset.
-• No any protection for turbine should in operating conditions.
-• AOP running.
-• Turbine casing top and bottom temp with in limit.
-• Turbine differential expansion normal.
-• Bearing oil drain temp normal.
-• Turbine bolt differential temp normal.
-• HP valve metal differential temperature normal.
-• GV setter on auto standby mode.
-• LL setter on AUTO.
-• Valve transfer on AUTO mode.
-• Turbine rolling parameters should be normal.
-• Condenser vacuum is normal.Lalpir/Pakgen Power Plant 80
-CCR Qualification Book
-5. Explain the difference between electrical and mechanical over speed,
-which is back up?
-Mechanical over speed: Mechanical over speed trip mechanism is installed
-on the turbine rotor extension shaft with a thread opposite to the direction of
-the rotation and is locked in place by a setscrew. The trip weight is carried in a
-transverse hole in the body, with its center of gravity offset from the axis of
-rotation so that centrifugal force tends to move it outward at all times. Normally
-this weight is held in its inner position by the compression spring and weight
-spring retainer. If the speed of the turbine increases to the point (about 110%
-of normal speed) for which mechanism is set to operate, the increased
-centrifugal force overcomes the compression of spring and trip weight move
-outward. In this outer position, the weight strikes the trip trigger and rotates it
-on fulcrum pin and moves the trip relay, which causes to drain the trip oil.
-The drainage of trip oil cause to drain auto stop oil. The drainage of auto stop
-oil cause to drain MSV, GV, RSV and ICV control oil at respective E/H
-converters and MSVs, GVs, RSVs and ICVs get close.
-Electrical over speed: Electrical over speed trip mechanism is watching the
-turbine speed, If turbine doesn't trip on MOST protection, at 112% of normal
-speed the EOST mechanism will operate over speed trip solenoid valve and
-drain the trip oil.
-The drainage of trip oil cause to drain auto stop oil. The drainage of auto stop
-oil cause to drain MSV, GV, RSV and ICV control oil at respective E/H
-converters and MSVs, GVs, RSVs and ICVs get close.
-The EOST protection is the back up of MOST protection.
-6. What is OPC (over speed control), how it works?
-OPC will operate in case of tribune tends to over speed 107 % of rated speed
-that is 3210 rpm. When OPC protection operates, the OPC solenoid valves are
-energized, draining the control oil between the E/H converter and servomotor
-and thereby closing the servomotors, while decreasing the governing valves
-(GVs) and interceptor valves (ICVs) E/H converter also closes the
-servomotors.
-When speed of the turbine decreases towards rated speed after the steam
-entrapped in the reheat system is dissipated, the interceptor valves are open.
-At rated speed, the governor valves will take over the control of turbine and
-keep the unit at rated speed.
-
-Chapter 25
-Tests
-1. What are the different tests required to be carried out on routine
-basis, what is purpose of these tests?
-Lube oil pumps cut in test – Turbine: (Weekly Routine)
-This test is performed to test and ensure the healthiness of lube oil pressure
-transmitter and lube oil pumps . This test include following pump’s cut in test
-AOP Auto Cut-in
-TOP Auto Cut-in
-EOP Auto Cut-in
-Turbine Protective Devices Test:
-This test is performed on first Monday of every month to test and ensure the
-healthiness of turbine protective devices. This test inclue
-Condenser Low Vacuum Test
-Thrust Wear Failure
-Overspeed Oil Trip Test
-Lube Oil Pressure Low
-Turbine Valves Freedom Test
-This test is performed Bi-Weekly (Alternate Monday) to ensure MSV’s and
-GV’s healthiness. Following valves test is performed.
-RH MSV/GV's
-LH MSV/GV's
-RH RSV/ICV's
-LH RSV/ICV's
-LP and HP Heaters High Level Protection Test
-This test is performed annually; once after annual outage at least. H&HH alarm
-appears on CRT and extraction MOV closes in this test. LP heater 3,LP heater
-4,HP heater 6,HP heater 7,HP heater 8 high level protection test is performed.
-Turbine Overspeed test (EOST or MOST)
-This test is performed Weekly (Every Monday) to ensure overspeed protective
-device.
-Hydro Test on Boiler:
-This test is performed after every outage , be it annual or forced outage. This
-test is performed to detect any leakage in boilerLalpir/Pakgen Power Plant 82
-CCR Qualification Book
-2. Explain the stem free test procedure, what is the load limitation with
-this test?
-MSV/GVs Test:
-a. Turbine load must be 25% to 70% i.e. 279 MW or less.
-b. Put DEHC on manual from “DEHC Valve Test” display. Turbine Master
-will be shifted on Manual and mode will be shifted on Boiler follow.
-c. Change Turbine Master on manual mode.
-d. Select ‘IMP in’ and on ‘auto’.
-e. Select the ‘LH Test’ mode from the ‘LH-MSV/GV Test’ block on the
-screen and at local, watch smooth closing of LH side GVs l and 3 and
-the MSV. Also watch the bearing temperatures & GVs of the right
-hand side 2 and 4 opening (for maintaining constant load).
-f. In CCR, check close indication of both GVs and MSV of LH side.
-g. Select the (LH Reset)’push button to restore initial conditions.
-h. At local, check re-opening of LH side MSV and then GVs and closing
-of RH side (GVs for load adjustment).
-h. Follow the same steps 5 to 8 mentioned above for testing RH side
-MSV und GVs by selecting ‘RH Test’ mode from RH-MSV/GV Test’
-block on the screen.
-Once the above test is completed, proceed with the following:
-RSV/ICV Test:
-i. Select ‘LH Test’ push button on ‘LH RSV/ICV test block on the screen
-and at local, watch smooth closing of LH side ICV and RSV. In CCR,
-check close indication of LH side ICV and RSV.
-j. Select ‘LH Reset’ push button to restore initial conditions.
-k. At local, check re-opening of LH side RSV and ICV.
-l. Repeat steps 1-4 mentioned above, for testing RH side RSV and ICV
-by selecting ‘RH Test’ push button from ‘RH-RSV/ICV Test’ block on
-the screen.
-m. Select IMP out’ and ‘auto’ to ‘manual’.
-n. DEHC from manual to auto mode.
-w. Change Unit control from Boiler follow to coordinate control.
-Refer to section 4-6-13 of turbine manual for the above rests.
-Test sequence for each set of valves
-Do a functional test of the (Main Stop) and reheat stop valves weekly with the
-turbine under load. The purpose of the test is to help maintain proper operation
-of these valves.
-a) A maintenance technician observes valve operation during the
-following test sequence for each set of valves.
-Check that movement of the valve linkage is smooth and free. Jerky or
-intermittent motion indicates:
-a. Buildup of deposits on the valve shaft (s) or stem (s) (such
-deposits may require cleaning)
-b. Bent valve stem (s) or shaft (s).
-c. EH converter oil pressure fluctuation.
-d. Valve misalignment.
-b) Find and correct the cause for shaft or stem deposits.Lalpir/Pakgen Power Plant 83
-CCR Qualification Book
-3. Describe the procedure of turbine protective device test from turbine
-deck, how turbine prevented from actual trip?
-During turbine protective device test procedure, turbine is prevented from
-actual trip by pressing the “Test Lever” on turbine deck. This lever block the
-draining port of auto stop oil from servo motor. Before normalizing and
-releasing this lever area engineer ensures the normal pressure of auto stop oil.
-All of the Turbine protective test can be performed in one go by pressing Test
-Lever, or they can be performed individually.
-4. Describe lube oil pumps auto cut in test, what actions required from
-control room during this test?
-Lube Oil cut in test is performed to confirm the healthiness of lube oil system.
-This test includes starting of AOP, TOP, and EOP one by one.
-During this test, when
-AOP starts, it has to be shifted on manual has to be stopped on manual to
-check next pump operation in case of its unavailability at low lube oil pressure.
-After stopping AOP , again lube oil pressure is lowered from local gauge, this
-time TOP will cut in . It has to be shifted on manual and has to be stopped on
-manual to check next pump operation in case of its unavailability.
-After stopping TOP , again lube oil pressure is lowered from local gauge, this
-time DC TOP (EOP) will cut in .
-Stop the EOP pump on manual , wait for the area engineer to normalize the
-valves at local , and after his confirmation , turn bank EOP, TOP and AOP on
-auto.
-5. At what conditions actual over speed test can be carried out, how
-frequent it is required?
-
-Chapter 26
-Unit control
-1. What do you understand about: -
-a) APC b) DEH c) BMS d) SEQ 1&2 e) IPU
-a) APC - It is abbreviation of AUTO PLANT COTROL and is related with
-all critical signals, which coordinates the boiler and turbine and it sums
-analog as well as digital signals
-b) DEH - It is abbreviation of DIGITAL ELECTRO HYDRAULIC system
-and it includes all signals related with governing system of turbine.
-c) BMS: It is abbreviation of BURNER MANAGEMET SYSTEM and it
-includes burners cut in cut out sequence / demand, and HFO leak
-tests, dampers and associated alarms for this particular system.
-d) SEQ-1: It includes mostly boiler related Logics, some generator and
-turbine related sequences like seal oil and stator coolant.
-e) SEQ-2: It includes mostly turbine related Logics and electrical stuff like
-11 kv. MCC and power center.
-f) DAS: It is abbreviation of DATA AQUESITION SYSTEM and is related
-with alarm and report printers’ data acquisition.
-2. Explain the following modes:
-(a) Turbine follow
-(b) Boiler follow
-(c) Co-ordinate control
-Turbine Follow:-
-In turbine-following mode the boiler master following the turbine parameters
-and turbine master is in automatic mode. The turbine master controls boiler
-steam pressure by modulating the turbine governor valves (GV’s). Megawatts
-are then produced in the generator and pushed to the grid as a function of the
-boiler load
-Boiler follow:-
-In this mode of operation, the boiler master is in automatic and the turbine is
-not. Turbine GV’s will respond to boiler pressure.
-Coordinate Control:-
-Means both turbine and boiler masters are on AUTO and will follow the each
-other parameters.
-3. What is the function of IPR and vacuum unloader? Explain in detail?
-IPR:
-If at any stage due to any reason main steam set point pressure reduces down
-to 10 % of set value then this protections operates and start to reduce the load
-until the parameters does not come in control.
-Vacuum Unloader:
-If due to any reasons condenser vacuum drops down up to 630 mm Hg, then
-this protection operates and starts to reduce the load until the parameter does
-not come in range.Lalpir/Pakgen Power Plant 85
-CCR Qualification Book
-4. What is the difference between governor control and load limiter
-control, which is preferable?
-Actually these both are load controls :
-Governor Control:-
-Stands for governor control and it watches the system frequency and droop
-and adjust the load accordingly by opening or closing G.Vs. and its setting is
-5% more than L.L on our unit.
-Load Limiter(L.L):-
-L.L stands for load limitter as it is clear from terminology that it follows the
-manual load target. If due to any system trouble our load exceeds up to 380
-MW then our unit control shifts on BF and turbine master goes on Manual and
-automatically unit run back starts and load reduces up to 10 % i.e. about 320
-MW.
-• As our unit is commercial unit and we are not attached with NPCC via
-LDC so it is preferable to remain unit on L.L to avoid load fluctuations
-due to change in frequency.
-5. What is stress control, how it works?
-Stress control is designed to maintain / control the “mismatch” of the turbine
-and its casing expansion”. If stress control is on Auto position, and actual
-stress increases up to 90ºC, this system will not allow increasing turbine speed
-(during rolling) or load will not increase during normal operation.
-Actually this system is very active to control the thermal stability of the turbine
-6. What is speed droop and what is our unit droop set?
-Our unit droop set is 5%. It means when turbine speed reduced or increased to
-5% of rated speed then governor valve take action to maintain the turbine
-speed. In this way governor valve hunting can be avoided
-7. What is the run back, what is the equipment which causes run back?
-What are CREs actions when Run Back operates?
-Run back mean decreasing of load automatically to maintain the system
-parameters.
-Following are the equipment’s, whom un-availability tripping will initiate run
-back
-Pump Run Back Load Ramp Rate
-Target
-BFP 146 MW 18.25 MW/S
-FDF 182.5 MW 18.25 MW/S
-AH 182.5 MW 18.25 MW/S
-BCP 219 MW 6.08 MW/S
-CP 200.75 MW 6.08 MW/S
-CWP 200.75 MW 6.08 MW/S
-Run back permit: Turbine Master on auto, Feed Water CV on auto, Fuel CV on
-auto
-Run back active: Gross Load equal to or above 115 MWLalpir/Pakgen Power Plant 86
-CCR Qualification Book
-8. Define the cold, warm and hot start: -
-a) According to PPA
-b) With reference to technical limits?
-WARM WARM
-HOT COLD
-I II
-Shutdown
-PPA Duration in 8 32 <150 >150
-hrs
-Turbine 1st
-Tech Stage Upto Greater than Less than
-Limits Metal 350 C 120 C 120 C
-Temp
-9. Discuss the turbine rolling; what are the permissive for turbine reset,
-sp1, sp2 and sp3?
-Turbine Reset & SP1 Permissive are as follows (They can also be found from DCS
-on “DEHC” screen)
-• Bearing vibration normal
-• Diff expansion normal.
-• Rotor position normal.
-• Bearing oil pressure normal.
-• HP oil pressure normal.
-• Bearing metal temperature normal.
-• Bearing oil drain temp normal.
-• Oil cooler oil temp normal.
-• HP casing metal temp differential normal.
-• Turbine bolt Diff. temp normal.
-• HP control valve metal Diff. temp normal.
-• Condenser vacuum normal.
-• GOV setter Auto stand by mode.
-• LL setter Auto stand by mode.
-• Speed setter Auto mode.
-• Speed rate setter Auto mode.
-• Valve transfer Auto mode.
-• Stress control in service.
-• Turbine is reset.
-• Start mode selected
-• Steam temp and pressure conditions fulfilled.
-• Speed rate Auto selected.
-• Main steam super heat degree >55ºC.
-• GV LH full open.
-• GV RH full open.
-Note: For SP2 all above conditions along with SP1 should be fulfilled. Similarly for
-SP3, SP1 & SP2 conditions should be fulfilled.
-SP1 command: When SP1-Set Point 1 command is given to the turbine, MSV’s
-open and steam admission is started. Turbine speed is increased to 500 RPM and
-lube oil temperature set point remains as 35ºC.
-After the completion of “Set Point 1” SP1, Rub check is performed to ensure smooth
-turbine rooling.
-SP2 command: SP2 command increases turbine speed up to 2200 RPM. When
-SP2 command is given to the turbine, at 800 RPM jacking oil pumps will stop and at
-900 RPM lube oil temperature control valve set point changes to 45ºC.Lalpir/Pakgen Power Plant 87
-CCR Qualification Book
-During cold startup turbine speed is kept hold at this point for heat soaking of
-turbine as per OEM provided graph.
-SP3 command: SP3 command increases turbine speed up to 3000 RPM. At
-turbine speed 2950 RPM AOP will stop automatically.
-10. What is full arc admission and partial arc admission, what are the
-benefits of full arc admission during start up, what are the conditions
-required to be fulfilled before valve transfer?
-Full Arc admission: In full Arc condition steam flow is control by the MSV’s
-while GV’s are full open and partial Arc admission is vise versa.
-The benefits of full arc are,
-a. Even heating.
-b. Time reduction i.e. rolling time.
-It is preferable for large turbine.
-Valve transfer permissive:
-a. GV setter on Auto mode.
-b. LL setter on Auto standby mode.
-c. V/V transfer on Auto mode.
-d. Stress control in service.
-e. Initial load achieved. (for cold startup)
-
-Chapter 27
-Transformers
-1. Write down the rating of following transformers
-a) GSU
-Rated Power: 430 MVA, 3 Phase, 50 Hz
-Primary Side: 24kV ,
-Secondary Side 220kV
-Cooling Method: ONAN-ONAF-OFAF
-Rated Current: (HV) 1128.5A (LV) 10344A
-Tapping Range: 193.6 kV to 255.2 kV (1 to 15 High)
-b) SUT
-Rated Power: 44 MVA, 3 Phase, 50 Hz
-Primary Side: 220kV ,
-Secondary Side 11kV
-Cooling Method: ONAN-ONAF
-Rated Current: (HV) 115.5A (LV) 2309.4A
-Tapping Range: 242 kV /198 kV (1 to 17) High
-c) UAT
-Rated Power: 40 MVA, 3 Phase, 50 Hz
-Primary Side: 220 kV ,
-Secondary Side 11 kV
-Cooling Method: ONAN-ONAF
-Rated Current: (HV) 962.3A (LV) 2099.5A
-Tapping Range: 252 kV /228 kV (1 to 17) High
-d) Excitation Transformer
-Rated Power: 2.546 MVA, 3 Phase, 50 Hz
-Primary Side: 24kV ,
-Secondary Side 489V
-Cooling Method: ONAN
-Rated Current: (HV) 61.25A (LV) 3006A
-2. What protections are provided on above mentioned transformers?
-Transformer differential protection To protect against short circuit faults
-Excessive volts protection To protect against high volts
-A high set instantaneous element To protect against heavy close-in faults
-A restricted ground differential zone element
-Phase and ground time over-current back-up relays
-Buchholz relay for detecting faults in the transformer main windings
-An oil surge protective relay. For detecting a fault in the OLTC compartment.
-Two over pressure relief devices for the main tank. Each of these devices
-initiates trippingLalpir/Pakgen Power Plant 89
-CCR Qualification Book
-3. GSU radiator fans are out of order, what will be its effect of
-transformer performance? What limitations will be imposed in this
-scenario?
-The losses occurring in the GSU transformer are converted into heat which
-increases the temperature of the windings and the core. In order to dissipate
-the heat generated cooling should be done.
-To dissipate this heat, GSU transformer is equipped with radiator and cooling
-fan for radiator.
-The radiator of transformer accelerates the cooling rate of transformer.
-Transformer cooling fans accelerate the cooling process in oil-cooled GSU.
-They circulate air around the exterior of the transformer's radiator as oil works
-its way through the inside to dissipate heat and reduce the temperature of the
-windings and the core.
-In case, radiator fans are out of order, higher peak load cannot be achieved as
-heat produced at higher load cannot be dissipated and this will increase oil
-temperature beyond its flash point. At temperature beyond flash point, oil may
-catch fire.
-In addition to high oil temperatures, insulation of transformer windings are
-designed at specific temperatures. At higher temperatures, transformer
-winding insulation will also damage, reducing the useful life of transformer.
-4. Why tap changing facility is provided on transformers? On which
-transformers on-load tap changers are provided?
-Transformer with tap-changing facility constitutes an important means of
-controlling voltage throughout the system at all voltage levels by changing tap
-levels. On SUT and GSU online tap changers are provided
-5. What precautions will be observed while operating On-Load Tap
-Changer provided on GSU?
-Generator MVAR’s and Power Factor as well as load in capability curve. In any
-case , cursor shall not exceed safe limits defined in capability curve
-6. Why silica gel is used in transformer breather tank and when its
-replacement is done?
-Silica gel is used in breather transformers for controlling the level of moisture
-and prevents it from entering the equipment. They are mainly useful in
-protecting the transformer oil from the damaging effects of moisture. When its
-color is changed or moisture deposits are found , it shall be replacedLalpir/Pakgen Power Plant 90
-CCR Qualification Book
-7. Draw a single line diagram of plant distribution system showing
-distribution transformers?
-
-8. What type of transformer is installed in MCC room? Why temperature
-monitor is provided in these transformers?
-Dry type transformers are installed in MCC room. Temperature sensors
-provide continuous real-time monitoring of dry type transformer temperature at
-winding to quickly detect overload and fault conditions
-
-Chapter 28
-Unit Startup and Shutdown
-1. Explain briefly the main steps of complete unit start-up.
-Main Steps of complete unit startup are as follows
-• Cooling tower basin filling
-• Demin Tank top up
-• Boiler Drain – If required
-• Condenser filling– If required
-• DA Filling– If required
-• Drum Filling– If required
-  >From Demin pumps header through Eco Spool Piece (Cold Startup)
-  >From BFP (Preferably by BFP D) for Warm & Cold Startup
-• Cooling Water On Command
-  >CWP
-  >BCWP
-• Removal of Eco Spool Piece
-• Air & Gas Sequence On Command
-• Furnace Purge & Leak Test
-• Boiler Firing (Keep Metal temp rise rate < 110 Deg C)
-• Operation of Boiler drain valves as per requirement to meet steam
-conditions as per Startup
-• Aux Header Charging
-• Vacuum Pulling
-• HFO Leak Test and HFO Burners
-• HP Bypass operation at Vacuum above 635 mm of Hg
-• Meet Steam parameters by opening of SH’s , Leg Drain MOV’s
-	>Steam Conditions as per turbine Startup type
-		 Hot – 100 kg/cm2 & 420 Deg C
-		 Warm – 80 kg/cm2 & 360 Deg C
-		 Hot – 60 kg/cm2 & 350~420 Deg C
-• Turbine Rest
-• SP1, Rub Check, SP2, SP3 & valve transfer (Hot & WARM start only)
-• Close Generator Isolator
-• Close Excitation breaker – 41E1
-• Turn 52C – Generator Breaker ON
-• Put Sync selection on Auto
-• Unit Sync
-• Valve Transfer (Cold Only)
-• Load Target
-• Main Steam Target (Subjected to chemistry)
-• HP-LP Heaters in service
-• CBD operation
-2. Technically how many types of startups are available? What is the
-Criteria for the type of technical start-up?
-Technical startup is of 3 types based on turbine first stage metal temperatues.
-	 Hot – 100 kg/cm2 & 420 Deg C
-	 Warm – 80 kg/cm2 & 360 Deg C
-	 Hot – 60 kg/cm2 & 350~420 Deg C
-3. How will you decide from where to (Lalpir or Pakgen) import power for
-start-up in following scenarios?
-a. When both units are shut down, one unit’s start-up is required
-and solar power is available.Lalpir/Pakgen Power Plant 92
-CCR Qualification Book
-b. When both units are shut down, one unit’s start-up is required
-and solar power in not available.
-c. When both units are shut down, both unit’s start-up is required
-and solar power in not available.
-d. When one unit is in service and other unit’s start-up is required.
-	a) For Both units Off Bar with solar power available, Community will be
-	connected to the unit under startup to take advantage of solar power.
-	b) For Both units Off Bar with solar power available, Community will be
-	connected to the unit in shut down mode.
-	c) Both units SUT will be taken in service and PFI will be connected with Lalpir
-	d) Connect the 2nd unit under startup with the On Bar unit to save import
-	power and MDI
-4. When will you change over fuel from HSD to HFO in case of
-	a. Hot start-up
-	b. Warm start-up
-	c. Cold start-up ?
-	
-Switching from HSD to HFO for all three startup modes can be done after HFO
-leak test completion and achieving HFO temperatures more than 90 Deg C
-and cold end metal temperatures more than 100 Deg C
-5. One unit’s start-up is in progress and 11kV unit tie breaker 2BCA18 is
-closed to import power from running unit. When will you take start-up
-unit’s SUT in service? What precautions will you take while this
-changeover?
-On unit under startup mode, when its turbine SP3 is completed and Valve
-transfer is also completed (for Hot and WARM only), SUT for unit under startup
-mode can be taken in service.
-Before taking SUT in service, make sure that its 11kV breaker is Rack In , and
-its Lock out ralay is Reset. In addition to this, confirm it’s close permit from
-SUT 11kV breaker loop plate
-6. When do we require to open following drain valves? When are they
-closed?
-a. SP lower header drain valve
-b. 2ry Super Heater drain valve
-SP lower header drain valve is opened during startup after forced outage
-2ry super heater drain valve is opened to meet steam conditions during
-startups
-7. What action will you take to keep MDI within its KPI for different types
-of start-ups i.e. hot, warm and cold?
-Take BFP-D in service that too on minimum possible frequency
-Operate GRF on possible minimum frequency
-Minimize operation of Waste water pumps, canal/well pumps
-Community shall be connected to other unit (If solar power is not available)
-Controlled operation of Condenser dumping and boiler CBD
-8. Which stage of PFI plant is taken into service during unit start-up and
-why?
-2nd Stage of PFI plant is taken into service to import less MVAR’s as more
-11kV motors are in serviceLalpir/Pakgen Power Plant 93
-CCR Qualification Book
-9. Both units are under start-up mode. One unit is under hot start-up
-mode and other unit’s cold start-up is just initiated. To which unit you
-will connect the PFI plant?
-PFI Plant will be connected to Unit under Hot Startup Mode.
-10. Explain briefly the main steps of complete unit shutdown.
-• Set Load target to 18 MW
-• Stop 2nd BFP, CWP & CP as per Load and 2nd HFO pump at minimum
-load.
-• Reduce main steam pressure and take aux steam MOV on manual
-• Take 11kV bus tie breaker 52AB/T in service and take UAT out of
-service
-• Ask area engineer to close Reheat TCV isolation valve
-• Check all turbine drains opened at <20% steam flow
-• Check economizer recirculation MOV opened at <20% steam flow
-• Check HP extraction out and its drain valves are open at load <50 MW
-• Select Main steam leg drain to manual (To avoid its opening on MFT)
-• BMS on manual and last stage burner selected manual
-• Turbine tripped from “Trip Sequence” at < 20 MW
-• Make sure all MSV, GV, RSV and ICV closed
-• Check Generator breaker opened on low forward power
-• Check excitation breaker opened
-• Check AOP cut in on turbine tripped
-• Take PFI in service
-• Check MFT do not occur on turbine trip
-• Lock BFP’s and Condensate Pumps sequence
-• All cooling tower fans stopped
-• Give Vacuum System OFF command
-• Take out last burner
-• Switch off BCP’s.
-• Make up drum level and stop main BFP
-• Close DA PCV & ask A/E to by-pass Condensate Storage Tank
-• Condenser spill over CV Shift to manual / closed
-• Take igniters out of service after last burner purging
-• Switch off igniter oil pump
-• Close SAH TCV ( Take care of Aux steam header pressure)
-• Select boiler on “Hot Bank” and give “OFF” command to Air & Gas
-sequence after its post purging time completed
-• Check Air & Gas system completed and all dampers are closed
-• Open generator breaker isolator
-• Check AC jacking oil pump cut in at turbine speed 800 rpm
-• Check vacuum breaker opened at turbine speed 400 rpm
-• Check Gland steam MOV closed at vacuum < 50 mmHg
-• Check TOP cut in and AOP stopped at turbine speed 50 rpm
-• Close aux steam MOV 3ry side (open tie if required)
-• Check T/G motor started at turbine zero speed and turning gear
-engaged. Confirm turbine triggering on TSI panel. Note down turbine
-coasting down time
-11. When will you stop following auxiliaries after unit shutdown?
-a. Main Condensate water pump
-	Main Condensate water pump can be stopped after 8 hours of shut down
-b. Main Circulating water pump and BCWP
-	Main CWP and BCWP can be stopped after 8 hours of shutdown
-c. Open 11kV breakers of BFPs and FDFsLalpir/Pakgen Power Plant 94 CCR Qualification Book
-After 8 hours of shut down they can be opened
-d. Optimize BFP, FDF,GRF and CT fans VFD room HVAC
-After 8 hours of unit shut down when 11kV breakers are opened
-e. Service air compressor
-As soon as other unit also shut down , one SAC can be took in service for
-both off bar units.
-f. Stator coolant pump
-After 8 hours of unit shut down
-g. Turbine turning gear and lube oil system
-As soon as turbine first stage metal temperature reaches to or below 120
-Deg C
-h. AC cooling fan
-As soon as drum metal temperature reaches to or below 100 Deg C
-i. GAH rotor drive
-As soon as GAH inlet temp decreases to or below 90 Deg C
-j. GRF turning gear
-As soon as GRF inlet temp decreases to or below 90 Deg C
-k. HFO firing pump
-After 32 hours of Unit shutdown (WARM II)
-12. With which frequency will you operate following equipment during unit
-cold mode
-a. Turbine turning gear
-Weekly routine to take in service for 1 hour duration
-b. BCP with Hydrazine in dozed in boiler
-As per requirement for 15 minutes
-c. CWP
-As per requirement to maintain chemistry
-d. Stator coolant pump
-Fortnightly routine to start for approx. 2~3 hours (subjected to conductivity
-normalization)
-e. Air and Gas dampers
-Fortnightly routine
-f. Fuel air dampers
-Fortnightly routine
-13. Which stage of PFI plant will you take in service during unit shutdown
-condition?
-In shutdown condition , PFI 1st stage will be taken into service
-14. When will you connect hot air blower to low pressure turbine?
-When turbine first stage temperature reaches below 120 Deg CLalpir/Pakgen Power Plant 95
-CCR Qualification Book
-15. How will you perform boiler forced cooling? What is the criterion to
-terminate forced cooling? How will you optimize electricity import
-during boiler forced cooling?
-Thumb Rule for maximum allowable change in boiler metal
-temperature is 110oC per hour. Whenever there is need for boiler
-forced cooling, this rate must be followed. In addition to this, VFD’s
-are installed on FDF’s and BFP’s , Keep their frequency on possible
-minimum requirement.
-If boiler is at high pressure, first open Boiler drains (Leg drain , 1ry,
-2ry, 3ry SH drains) upto 15% till the pressure decreases to 30
-kg/cm2.
-From 30 kg/cm2 to 10 kg/cm2 , increase Leg drain . 1ry and 3ry SH
-drain MOV opening to 50%
-From 10 kg/cm2 to 02 kg/cm2 , increase Leg drain . 1ry and 3ry SH
-drain MOV opening to 100%
-On reaching 02 kg/cm2 drum pressure, ask boiler area engineer to
-open steam drum vents.
-CBD can be opened upto 15% initially till 30kg/cm2 and its opening
-can be increased afterwards keeping steam drum level in range and
-cooling rate in range..
-Please make sure to keep eco recirculation valve in fully open
-position during this activity.
-On reaching drum pressure upto 60kg/cm2 , air and gas system can
-be started depending on the requirement.
-As per standard forced cooling can be terminated at boiler drum metal
-temperature of 90Deg C