CIBO , May 2, 2014

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### Changes Needed **t o**  **t he Boiler MA** **CT and GA CT Startup**  **a nd Shutdow**  **n Provisions**

CIBO strongly agrees with EPA that work practices are the correct approach for applying a standard to boiler and process heater startup and shutdown periods. However, the definitions of startup and shutdown must be revised in order to accommodate the practica l and safety aspects of starting up and shutting down these units and to ensure achievability of the standards

. The following points summarize why these changes are necessary.

 The appropriate procedures for startup and shutdown vary by unit design, poll ution control type and configuration, and fuel firing mechanism. EPA should not set a work practice standard that is fundamentally incompatible with the safe and proper operation of certain units. The act of supplying heat, steam, or electricity , which d efines the end of startup in the current rule, does not represent the functional end of the startup period. The startup definition and procedures must ensure that the equipment is brought up to normal operating conditions in a safe manner, and startup end s when the boiler/process heater and its controls are fully functional.

 Because there is such diversity in the designs and operating modes of the boilers and process heaters being regulated by the major and area source rules, there is not a single load threshold or time period that would represent the functional end of startup for all units. If EPA incorporates a “load plus time” type of threshold similar to MATS into the MACT/GACT rule s to define the end of startup, it should vary by unit design, it should accommodate units that operate at low load or standby conditions , and there must also be a mechanism by which a facility can establish unit

- specific startup criteria and document those criteria in a site

specific s tartup plan if it is not technically feasible for them to meet the load plus time threshold in the rule

.

 Information gathered from CIBO members in an informal survey indicates that on a cold startup, fluidized bed boilers can take up to 2 6 hours to reach stable conditions after reaching 25% load, pulverized coal boilers can take up to 5 hours to reach stable conditions after reaching 25% load, and stoker and hybrid suspension grate type units can take up to 8 hours to reach stable conditions after reachin g 25% load (although the majority of units responding can reach stable conditions within 4 hours)

. Circulating fluidized bed boilers need adequate time to establish stable bed conditions such as reaching the temperature and pressure necessary for stable o peration and to calcine the limestone in the bed to begin achieving acid gas control within the bed. Although we only received 3 responses on bubbling fluidized bed units, it appears from that limited feedback that the time required for this design to ach ieve stable operation after 25% load is more similar to pulverized coal units. Liquid units can typically achieve stable operation within 4 hours of reaching 25% load. On a hot startup, responses indicate that fluidized bed boilers can take up to 1 3 hours to reach stable conditions after reaching 25% load, pulverized coal boilers can still take up to 5 hours to reach stable conditions after reaching 25% load (especially for units that come online with a clean fuel and transition to solid fuel) , and stoker and hybridCIBO , May 2, 2014

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### suspension grate type units can take up to 4 hours to reach stable conditions after reaching 25% load.

 Under the current rule, units equipped with control devices that are not specifically listed as exempt must either fire clean fuels during startup or engage the controls when coal, biomass, or residual oil is first introduced into the boiler or process heater. The list of clean fuels should be expanded. There are fuels other than those listed in the rule that should qualify as clean fuels to be fired during startup prior to engaging any control devices that are not exempted

.

 ESPs must be included in the list of exempted air pollution controls that must be started as expeditiously as possible. An ESP canno t safely be engaged until a certain flue gas temperature and/or oxygen level is reached. EPA recognizes this in the current rule for other control devices. Many units have a safety interlock that prevents the ESP from operating if the oxygen level is abo ve 10%.

 The shutdown definition currently states that shutdown begins when fuel is no longer being fired. The definition should be revised to accommodate units firing solid fuels on a grate or in a fluidized bed combustor where the residual material in th e unit keeps burning after fuel feed to the unit is stopped. EPA has already indicated in guidance that they consider fuel “being fired” to mean that fuel is being fed . EPA should make this clear in the rule

.

 EPA has indicated through guidance that if a shutdown is not completed to the point of both no fuel being fired and no steam or heat being supplied, then a shutdown has not occurred and therefore a startup cannot occur. There are situations where solid fuel feed is lost where the feed can be restore d before a complete shutdown takes place. The rule must take these periods into account so operators can have certainty in designing monitoring and recordkeeping systems and in determining compliance when these events occur.

More information and examples are provided in the attached table.CIBO , May 2, 2014

– Page 3 **Controls Scenario**  **Potential Compliance Issue Suggested Solution**  Any Startup on clean fuel,

engage non

- listed controls prior to adding solid fuel. Ma y be an issue with clean fuel availability. May have CO issue with transition from gas or liquid fuel to solid fuel, may not be an issue for 30

- day average depending on compliance margin. Exp and list of clean fuels to include all Other Gas 1 fuels, biodiesel, fuels that meet the HCl, Hg, TSM limits through fuel analysis, and other clean fuels as determined by permitting authorities. Provide adequate length of time for startup period to cover transition from startup fuel to solid fuel. (as defined below) Wet Startup on solid fuel Shouldn’t be an issue for operating parameter monitoring

– can start wet controls prior to startup (depending on design of wet controls, may not be able to meet opera ting parameter limits instantaneously, but should be able to meet 30

- day average).

Need to address units that share a common control device that startup separately.

Could have issues meeting 30

- day rolling CO CEMS limit if enough time is not given for startup. Need to differentiate between cold startup (need more time) and hot restart (need less time). Startup ends either when the boiler or process heater has continuously maintained a steam production rate of at least 25% of maximum steam or heat o utput at normal operating pressure for a certain number of continuous hours 1 af

ter a cold startup or a certain number of continuous hours hour after a hot restart and when all control devices are in stable operation or when the boiler or process heater is operating above an alternate minimum operationally stable output flow rate and pressure for a minimum time, as specified in a site

- specific start

- up plan. This would also apply to units sharing a common control device that start up at separate times (sepa rate startup period occurs for each unit). For units sharing a common control device that are starting up sequentially, startup ends either when the last boiler or process heater to start has continuously maintained a steam production rate of at least 25% of maximum steam or heat output at normal operating pressure for a certain number of continuous hours af ter a cold startup or a certain number of continuous hours after a hot restart and when all control devices are in stable operation or when the last boi ler or process heater is operating above an alternate minimum operationally stable output flow rate and pressure for a minimum time, as specified in a site

specific start

- up plan.

1 The time to reach stable conditions following 25% load will vary based on design, per our discussion on page 1 of this docume nt.CIBO , May 2, 2014

– Page 4 **Controls Scenario**  **Potential Compliance Issue Suggested Solution**  Dry Startup on solid fuel Can’t startup **ESP** until certain flue gas tempe rature and oxygen level are reached. NFPA 85

- Boiler and Combustion Systems Hazards Code, 2011 Edition, Section 6 Multiple Burner Boilers (firing oil, gas, or PC) requires purging of precipitators prior to initial firing to prevent a precipitator spark from igniting an explosive mixture of unburned fuel.

Manufacturer and operating company procedures may include a requirement to be operating on main burners with adequate flue gas temperature and low enough oxygen levels prior to ESP energization to limit potential ignition of unburned fuel by a precipitator spark.

Need time within the “startup” period for the combustion unit firing primary fuel(s) and all exempted air pollution controls to reach stable operating conditions relative to the start of steam or process heater output to the distribution system.

Need to get better definition of end of startup if heat or steam is immediately supplied upon ignition of fuel.

Need to address units that share a common control device that start up separately. Cou ld have issues meeting 24

- hour block opacity or 30

- day rolling CO CEMS limit if enough time is not given for startup.

Need to differentiate between cold restart (need more time) and hot restart (need less time) ESPs must be included in the Table 3, item 5 list of exempted air pollution controls that must be started as expeditiously as possible.

Startup ends either when the boiler or process heater has continuously maintained a steam production rate of at least 25% of maximum steam or heat output at normal operating pressure for a certain number of continuous hours after a cold restart or a certai n number of continuous hours after a hot restart and when all control devices are in stable operation or when the boiler or process heater is operating above a minimum operationally stable output flow rate and pressure for a minimum time, as specified in a site

specific start

- up plan. This would also apply to units sharing a common control device that start up at separate times (separate startup period occurs for each unit).

For units sharing a common control device that are starting up sequentially, star tup ends either when the last boiler or process heater to start has continuously maintained a steam production rate of at least 25% of maximum steam or heat output at normal operating pressure for a certain number of continuous hours af ter a cold startup o r a certain number of continuous hours after a hot restart and when all control devices are in stable operation or when the last boiler or process heater is operating above an alternate minimum operationally stable output flow rate and pressure for a minim um time, as specified in a site

specific start

- up plan.CIBO , May 2, 2014

– Page 5 **Controls Scenario**  **Potential Compliance Issue Suggested Solution**  Any Unit begins startup,

reaches a certain minimum stable load, then there is an equipment problem that results in “failed startup.” All of the above. Need to be sure that this entire period is con sidered startup, even if you reach the minimum load threshold. If, for example, the end of startup is 25% load plus 8 hours, the unit has to be over 25% for 8 continuous hours.

Wet Lose solid fuel feed,

takes time to get auxiliary fuel going to boiler or there is no auxiliary fuel available. Sometimes wet fuel can cause high O2 conditions, which will trip the ESP, which will trip the fuel feed. Sometimes there are problems with the equipment used to supply the solid fuel that cause loss of fuel feed. L osing fuel feed would trigger a shutdown

– however, shutdown as EPA currently interprets would not be completed if the unit continues supplying useful steam until fuel feed is restored. Wecan’t classify these periods as malfunctions in all cases and thes e periods are not normal operation. We need to be able to call them shutdown, or we don’t know how to set up recordkeeping because we don’t have certainty on how to classify these periods. Operating parameters would probably be okay on a 30

- day rolling a verage basis. Wh ether or not there was an issue meeting 30

- day rolling CO CEMS limit if this is not shutdown would depend on compliance margin and length of event. The shutdown definition should accommodate the scenario where fuel feed is reinitiated befo re the unit ceases to supply steam. Facilities need to be able to call it a shutdown, even if fuel supply is restored. Facilities should not be forced to take the boiler down fully before reinitiating a startup

– this would be uneconomical and could resu lt in more emissions. The end of this period is a hot restart, and then the startup work practices would apply until certain load and time conditions are met. Could revise end of shutdown definition: “Shutdown ends when there is **both** no steam or heat be ing supplied **and** no fuel being combusted in the boiler or process heater **or** when startup is initiated by reintroducing fuel to the boiler or process heater after fuel feed has been halted.”CIBO , May 2, 2014

– Page 6 **Controls Scenario**  **Potential Compliance Issue Suggested Solution**  Dry Lose solid fuel feed,

takes time to get auxiliary fuel going to boiler or there is no auxiliary fuel available. Sometimes wet fuel can cause high O2 conditions, which will trip the ESP, which will trip the fuel feed. Sometimes there are problems with the equipment used to supply the solid fuel that cause loss of fu el feed. Losing fuel feed would trigger a shutdown

– however, shutdown as EPA currently interprets would not be completed if the unit continues supplying useful steam until fuel feed is restored.

Also, NFPA 85 Boiler and Combustion Systems Hazards Cod e, 2011 Edition, Section 6 Multiple Burner Boilers (firing oil, gas, or PC) requires tripping of electrostatic precipitators as part of a master fuel trip (MFT) to prevent a precipitator spark from igniting an explosive mixture of unburned fuel.

Wecan’t classify these periods as malfunctions in all cases and these periods are not normal operation. Weneed to be able to call them shutdown, or we don’t know how to set up recordkeeping because we don’t have certainty on how to classify these period s. Could have issues meeting 24

- hour block opacity or 30

- day rolling CO CEMS limit if this is not shutdown, depending on compliance margin, type of unit, length of event. Need to be able to call it a shutdown, even if we get fuel back; emissions will be g reater if we have to complete a shutdown before we can start back up. The end of this period is a hot restart, and then the startup work practices would apply until certain load and time conditions are met. Could revise end of shutdown definition: “Shutd own ends when there is **both** no steam or heat being supplied **and** no fuel being combusted in the boiler or process heater **or** when startup is initiated by reintroducing fuel to the boiler or process heater after fuel feed has been halted.”

ESPs must be inclu ded in the Table 3, item 6 list of exempted air pollution controls that are not required to be operated during shutdown.

Any Begin shutdown upon

halting fuel feed to the boiler. For some designs, there is still fuel burning in the boiler. Current defin ition says “ Shutdown begins either when none of the steam and heat from the boiler or process heater is supplied for heating and/or producing electricity, or for any other purpose, or at the point of no fuel being fired in the boiler or process heater, whichever is earlier.” This could be interpreted that shutdown does not begin unless no fuel is burning or no steam/heat is being supplied. In some boiler designs, fuel continues to burn after fuel feed stops. EPA should clarify that fuel being fired in th is case means fuel being fed to the combustion unit.CIBO , May 2, 2014

– Page 7 **Controls Scenario**  **Potential Compliance Issue Suggested Solution**  Wet More than one unit vents

to a wet control device, one unit shuts down, the other unit stays operating. For some wet control designs, the pressure drop depends on the flow through the scrubber. If

o nly one unit is operating, the operating parameter limits established during the performance test with both units in operation may not be achievable. Not sure if there is a way to address this in the rule, or if EPA would advise facilities to submit a requ est for alternate monitoring and establish different operating scenarios, such as an alternate operating limit with fewer units in operation. This is similar to the question of whether operating parameters must be maintained if a unit burns gas for an extended period of time and emissions controls for PM, HCl, Hg are not needed. This is probably covered under a request to permit alternate operating scenarios as well. Any

– low load/ standby unit A unit operates for many

hours in standby mode, less than 25% load, either burning clean fuels or burning solid fuels with emissions controls in service. How to define the end of startup to accommodate a unit that operates in a low

- load mode after initial “ignition” (e.g., it never reaches 25% load). Facilities should not have to increase load above 25% just to reach the defined end of startup. Wh ere a 25% load+time threshold can’t be accommodated by a standby unit, the following types of concepts could be incorporated into the permit to identify the end of startup:

 The unit is firing its primary fuel for a period of time adequate to provide stable and non

interrupted fuel flow, stable and controlled air flows, and adequate operating temperatures to allow proper fuel drying and air preheat as applicable.

 Emis sions controls are in service with operating parameters such as flow rates and temperatures being controlled and stable.

 The unit is supplying steam to a common header system or energy user(s) at normal operating conditions including pressure and temperatu re, and is above the minimum operational stable output flow rate, as applicable to the unit.

 For stoker units, when the grate reaches an adequate level of coverage with solid fuel based on visual observation and stability of air, fuel, and steam flow rates

.