July 9, 2012



### Subject : 

### Design Narrative

1.0 Introduction
This design has been proposed in order to meet th e intent of the new emissions standards proposed by the United States Environmental Pr otection Agency (EPA) for the collection and control of process fugitive emissions. During the field visit on May, 23 2012 several point source emission sources were identified, these sources are tapping; casting; crushing/screening and skimming/slag raking. The proposed design addre sses and provides solutions for each of these sources and describes the desi gn intent for meeting the EPA objectives. See Appendix 1 for conceptual drawings outlining these solutions. All capture systems shall have a minimum hood face capture velocity of 300 FPM as per acceptable engineering standards.


### 2.0 Repairing existing direct exhaust system
The existing ventilation system for the furnaces consists of three separate baghouses for each furnace and supplemental exhaust fans for other operations. Makeup air is provided through door openings and building infiltration. Th is ventilation system provides direct exhaust for the furnace and casting/tapping processes. This system was no t originally designed for the lower temperature ferroalloy process, which has resulted in a lower ventilation rate of approximately 180,000 CFM’s compared to the original rate of 250,000 CFM’s, a 30% decrease in capacity. New fans and motors sized for the current process will rest ore the existing system to the original design capacity. The existing fans have 1,500 HP motors, due to the lower temperatures and higher fan efficiencies available only 600 HP motors are required to provide 250,000 CFM of ventilation.
The casting nests will be provided with new cas ting shields with a built in overhang over the nest, which will capture and direct emissions towards the casting hood for a total minimum efficiency of 90%.
To increase the capture rates for the tapping process, the tapping area will be enclosed to contain emissions generated during the process. The enclosure will consist of a solid floor and ceiling, including full height movable partitions to allow the operators access to the tap hole. The existing tap hole fans will exhaust emissions generated within this enclosure. An estimated total minimum capture efficiency of 95% is expected with these changes.
Each crusher has its own dedicated baghouse, #1 crusher has three baghouses and #2 crusher has two baghouses. The baghouses are directly ducted to each crusher/screener and provide direct exhaust at each emission source on the equipment. A recent test report indicates that the functioning baghouses are running approximately 50% below design capacity at 4,320 CFM and7,673 CFM instead of the design capacities of 10,000 CFM and 12,000 CFM respectively. See Appendix 2 for a copy of the test reports. New fa ns/motors will be provided to bring the system up to the original design capacity. This add itional ventilation capacity coupled with the secondary exhaust system outlined below will impr ove the total capture efficiencies at both crushers to a minimum of 85%.


### 3.0 Installing a secondary exhaust system.
While the improvement to the direct exhaust system will increase the capture rate of fugitive emissions, it is infeasible for this system to capture all of the generated emissions at each process. In order to increase th e overall capture rate a secondary exhaust system is proposed to provide general exhaust.
Our investigation showed that fugitive emissions emitted in the hot metal bay were collected in the roof monitors and pitched roof, as shown in the photograph below.

A general exhaust system is proposed to exhaus t all emissions collected above the rafters, capturing fugitives missed by the direct exhaust system. This general exhaust system will provide 12 air changes per hour (ACH), which in essence exhausts the entire volume of air above the rafters every 5 minutes. The general exhaust sy stem in the hot metal bay was selected for 12 ACH instead of 6 ACH due to the large emissions generated by the furnaces and skimming/slag raking processes. Providing 12 ACH for genera l exhausts requires approximately 120,000 CFM of fan capacity. This additional capacity can be provided at eith er the existing baghouses with larger motors/fans, or can be provided at a separate new baghouse. New ductwork will be ducted to three of the existing roof monitors which act as natural collection poin ts. The remaining roof monitors will be removed and new skylights are proposed which will provide natural sunlight for illumination. This roof exhaust system is estimated to have a total minimum capture efficiency of 90%.
The secondary exhaust system will also capture emissions generated during the skimming/slag raking processes, as these occur within the middl e of the hot metal bay. Any emissions generated by the casting process that was not captured by the direct exhaust system would also be captured by the secondary exhaust system. The emissions woul d naturally rise into th e roof rafters and be

CHU AND GASSMANCHU AND GASSMAN exhausted from the roof monitors. Source control of these emissions is not possible due to the location of the process, as a ny ductwork located to capture em issions locally would interfere with overhead crane traffic.
The crushing/screening area is also proposed to have a new genera l exhaust system. Each crusher will have its own dedicated general exhaust sy stem providing 6 ACH of ventilation around the crusher, which is approximately 140,000 CFM each. This general exhaust system will serve to capture and contain emissions missed by the dire ct exhaust system, and will provide general ventilation in the area as well. As the crushe r/screening equipment is the main source of emissions there is no need to exhaust the entire crusher/screen ing area. A proposed curtain wall will be provided between the hot metal bay and crushing/screening area to reduce cross contamination between the two areas and contain th e fugitives within each respective area. This system is estimated to have a total minimum 85% capture efficiency rate.
The proposed secondary exhaust system will be opera ted on an intermittent basis, because of this no dedicated makeup tempered s upply air system is required.


### 4.0 Conclusion
The proposed design improves the existing direct exhaust system while providing a secondary exhaust system in order to fully capture and contain process fugitive emissions that are generated. The use of both a direct exhaust syst em and a general secondary exhaust system in conjunction is estimated to provide a TOTAL building capture rate of approximately 95%, including the tapping; casting; crushing/screening and skimmi ng/slag raking processes.

The field visit also witnessed th e charging of the electric arc furn aces, no emissions were seen to be generated by the charging process.CHU AND GASSMAN 

## APPENDIX 1 – DESIGN DRAWINGSCHU AND GASSMAN 

## APPENDIX 2 – TEST REPORTFlow Rate ACFM 7,673 Horsepower 25 2 Yearly Hours in Operation (approx) : 8322 Flow Rate SCFM 7,715 Amps 29 3 Plant Cost per kW/hr: $0.042
Flow Rate lbs/ hr 34,560 Volts 460 Fan Operating Cost per Year: $7,109 Temperature F 41 RPM 1775 Fan Energy Usage, Megawatt Hrs/Yr 169.3 Density lbs/ ft 3 0.0751 SF 1.00 Motor HP per Inch Pressure Loss 3.9 Fan Inlet Damper % open No Damper Cost per Inch of Pressure Loss, yr $1,010 Fan Inlet Velocity Pressure in H2O 0 Fan Inlet Pressure in H2O -8.2 Estimated HP @ 70% Fan Efficiency: 12.8 Fan Outlet Pressure in H2O -0.2 Fan Operating Cost per Year: $3,332

1 Fan Static Pressure in H2O 7.4 Energy Savings per Year: $3,776 Fan Shaft Speed RPM 1050 Fan Energy Usage, Megawatt Hrs/Yr 79.3
Fan Motor Power Amps 31.0 Motor HP per Inch Pressure Loss 1.8
Fan Motor Power HP 27 Cost per Inch of Pressure Loss, yr $473 Fan Efficiency, % % 32.8

1 Fan static pressure calculated using AMCA 203-90. (Outlet Static - Inlet Static - Inlet VP)
2 Hour estimated based on 95% operating time 52 weeks/year.
3 Plant cost per kW/hr based on data provided by Felman Production, Inc. Estimated Annual Energy Cost @ 70% Fan Efficiency 

### January 28, 2011 Letart, West Virginia

Production Rate: Normal

Existing Annual Energy Cost (approx) 

## #2 Crusher Baghouse Fan (Hill Side)

Nameplate Fan Motor Data Fan OperationFlow Rate ACFM 4,320 Horsepower 20 2 Yearly Hours in Operation (approx) : 8322 Flow Rate SCFM 4,379 Amps 24 3 Plant Cost per kW/hr: $0.042
Flow Rate lbs/ hr 19,616 Volts 460 Fan Operating Cost per Year: $2,629 Temperature F 38 RPM 1775 Fan Energy Usage, Megawatt Hrs/Yr 62.6 Density lbs/ ft 3 0.0757 SF 1.15 Motor HP per Inch Pressure Loss 1.6 Fan Inlet Damper % open No Damper Cost per Inch of Pressure Loss, yr $415 Fan Inlet Velocity Pressure in H2O 0 Fan Inlet Pressure in H2O -7.4 Estimated HP @ 70% Fan Efficiency: 6.5 Fan Outlet Pressure in H2O -0.2 Fan Operating Cost per Year: $1,688

1 Fan Static Pressure in H2O 6.7 Energy Savings per Year: $941 Fan Shaft Speed RPM 1791 Fan Energy Usage, Megawatt Hrs/Yr 40.2
Fan Motor Power Amps 14.3 Motor HP per Inch Pressure Loss 1.0
Fan Motor Power HP 10 Cost per Inch of Pressure Loss, yr $267 Fan Efficiency, % % 44.9

1 Fan static pressure calculated using AMCA 203-90. (Outlet Static - Inlet Static - Inlet VP)
2 Hour estimated based on 95% operating time 52 weeks/year.
3 Plant cost per kW/hr based on data provided by Felman Production, Inc. Estimated Annual Energy Cost @ 70% Fan Efficiency 

### January 28, 2011 Letart, West Virginia

Production Rate: Normal

Existing Annual Energy Cost (approx) 

## #2 Crusher Baghouse Fan (Road Side)

Nameplate Fan Motor Data Fan Operation