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**VIA E -** **MAIL AND OVERNIGHT MAIL**  August 6 , 2014
Ms. Susan Fairchild Sector Policies and Programs Division Metals and Minerals Group (D243
- 02) Office of Air Quality

Planning and Standards U.S. Environmental Protection Agency 4930 Old Page Road Durham, NC 27703 RE: NAIMA’s Responses To EPA’s Questions

– Work Practices For Startup and Shutdown of Mineral Wool Cupolas Dear Ms. Fairchild: IN TRODUCTION The North American Insulation Manufacturers Association (“NAIMA”) appreciates the opportunity

to provide work practices employed by mineral wool insulation manufacturers during startup and shutdown. As NAIMA stated in its written comments, emissions data are not available f

or startup and shutdown, and the work practices set forth herein provide a sound approach to keeping emissions low during startup and shutdown for mineral wool cupolas
. NAIMA and its members would be willing to elaborate or expand on the information set f orth herein. The work practices described herein reflect input from NAIMA’s mineral wool companies. The work practices and related information are organized herein by providing aggregated responses to four questions that were posed to member companies by NAIMA, as suggested by conversations with the Environmental Protection Agency ( “EPA”). These work practices set forth herein may

not be used at all facilities. The work practices vary by company depending on the particular design of each facility ’s proc ess and emissions control equipment. Not all work practices are or could be employ ed at every

facility
. QUESTION 1 Question: What work practices or housekeeping measure s are used by mineral wool

companies to keep particulate matter (“PM”) and carbonyl sulfide (“COS”) emissions l ow during startup and shutdown?Ms . Susan Fairchild

August 6, 2014 Page 2

 Cupola (furnace) emission s are generally controlled with some form of drop out section that separates heavy

p articulate

– a thermal oxidizer or combustor

– in which any combustib le gases are ignited and burned, and a baghouse or other particulate control may b e used
. Natural gas burners provide the ignition source and any n ecessary supplemental fuel for the oxidizer. Oxidizer exhaust ty pically goes through a heat exchanger to preheat cupola combustion air (combustion “blast” air) to 900
- 1000 °F. Many facilities also inject oxygen into the cupola for combustion (oxygen enrichment).  Some facilities inject dry s orbent or l ime into the area immediately after the combustor and before the baghouse to control sulfur emissions. Other facilities may limit the sulfur content of the fuel (ty

pically coke) to control sulfur emissions.  Use of preheat and oxygen enrichment reduces the fuel (ty pically coke) required in the cupola.  Facilities that use a cupola generally close the stack cap to route the cupola emissions through the control devices either prior to or within five minutes of lighting the cupola, depending on how well the oxidizer handles the thermal shock of the cap closure.  During shutdown, the oxidizer and the other controls are in use until oxygen enrichment and blast air are removed from the cupola. At that point, the oxidizer is by passed and shutdown, and the cupola is drained after that point.  During scheduled startup s and shutdown s , facilities ty pically have additional personnel and necessary

supervision to ensure startup procedures are followed.  Operators insure all equipment is operational by visually checking electronics and computer screens, as well as the equipment. QUESTION 2 Question: Based on this statement from NAIMA’s comments

– ‘emissions of some

pollutants likely

are higher during the startup period than at normal steady
- state operations, and emission of other pollutants likely are lower
. . .’ (see NAIMA’s February 3 , 2012 comments to EPA on p. 49 )

– EPA believes that there may b e variations in emissions from rock and slag wool plants during startup and shutdown. If variations occur, what are the variations attributable to? What other factors might explain variations? Emissions of some pollutants presumably are higher during the startup period than at normal, steady
- state operations. F or example, emissions of COS and CO likely are higher than usual during startup and shutdown because only fuel (ty pically coke ) is being burned initially. Emissions of other pollutants likely are lower, for example, because the batch has not yetmelted during startup. Given the emission limits are on a pound per ton of melt basis, the emissions are almost certainly higher on that basis, given the lack of melt, independent of the relative level of absolute emissions.Ms . Susan Fairchild

August 6, 2014 Page 3 Emissions control equipment may not be as effective during startup and shutdown periods as it is during steady
- state operations. There are numerous reasons why a source might not always meet , during periods of startup or shutdown, the emission limitations established based on performance during steady
- state operation, even if the control devices used are started up before the process units and are operational during the shutdown phase of a process. F or example, a control device may

be less efficient until it reaches its design operating temperature, or it may be less efficient when the pollutant concentrations in the gases to be treated are lower than during steady
- state operation (as they o ften will be when a process is starting up or shutting down). 1 For instance, even if an oxidizer is operational prior to cupola lighting, the inlet temperature of the oxidizer will rapidly

rise as the hotter gases enter it and then level off. D epending on how the temperature controls of the oxidizer respond, the control efficiency c an easily

f luctuate. On the other hand, until a manufacturing process reaches steady- state operation, that process may generate higher emissions, either on a total mass basis or on a mass per unit of production basis. 2 The startup and shutdown periods are very brief, representing a small portion of the overall operating cycle, and that brevity therefore undercuts any potentially perceived need for new or different requirements during these periods. Cupolas ty pically operate for a one - to two -week period, (this is not representative of all facilities) and the startup period for a cupola generally is 1 to 2 hours and the shutdown period ranges from 0.5 to 2 hours. A ssuming that the combined startup and shutdown period is 4.0 hours, these combined periods are roughly 2 p ercent of an approximately

one -week production run and 1 percent of an approximately two -week production run. These time frames are averages, not precisely a pplicable to all facilities. Further, control devices are operational on at least the majority of the startup and shutdown periods. There could be higher emissions for the very short period that the oxidizer is being by passed after the cupola is lit (both PM and COS) than during normal operations. But even in these instances, the oxidizer is brought up to the required destruction temperature before the cupola is lit. Because it takes a while to obtain melt, on a pound per ton basis, the emissions remain higher than normal for a period even after the oxidizer is put on line, even though absolute emissions should no longer be elevated. Not all cupolas ( furnaces ) are designed to by pass oxidizers and filters. These additional details provide further explanation on reasons for possible variations:

 During cupola startup, at some facilities, only the fuel (ty

pically coke) is burning until a sufficient "coke bed" is established in the bottom of the cupola. Then raw materials are placed on top.  Products of fuel (typically coke) combustion would be evident in emissions on startup.  Products of fuel (typically coke) combustion and raw material melting would be evident in emissions during startup as well as shutdown conditions.

1 See, e.g. , 68 Fed. Reg. 1,276 , 1,287
- 88 (Jan
. 9, 2003). 2 See, e.g. , 76 Fed. Reg. 63,878, 63,883 (Oct
. 14, 2011).Ms . Susan Fairchild

August 6, 2014 Page 4

 In many facilities, pollution control equipment would be running the majority of the time in each of these conditions.  Equipment malfunction emergencies may also cause variations in emissions , although malfunctions are outside the scope of the questions posed. QUESTION 3 Question: For emissions during startup and shutdown :

 Are emissions monitored during startup and shutdown currently? Emission levels are not measure d during startup or shutdown. EPA standard emission testing methods require testing be conducted during steady
- state operating conditions, which do not occur during the startup and shutdown period. Control device parameters and the equipment itself are monitored. In some cases, opacity is monitored visually.

 What issues might be detected during monitoring? Insufficient air flow, pressure readings, motors not running, water not flowing, oxygen not flowing , insufficient temperature in control devices, etc.

 Does the monitoring inform you about specific actions that need to be taken to reduce the emissions? Operators are trained on the entire cupola melting operation. Standard procedures specify specific actions to be taken during the startup and shutdown periods. Experienced supervisors are present during the startup and shutdown periods as well. QUESTION 4 Question: What additional measures (work practices or housekeeping measures) can be

undertaken by

c ompanies to make certain that emissions levels are maintained throughout the startup and shutdown period?

 Follow company startup and shutdown procedures
.  Prior to startup after extended down times (not counting cupola drops) , cupolas ( furnaces ) and all associated environmental abatement and control systems are inspected, cleaned, maintained, and work performed documented as set forth in a preventive maintenance program or operation, maintenance, and monitoring plan
.  Facilities maintain logs that record routine regular inspections of operating components of emissions control equipment.Ms . Susan Fairchild

August 6, 2014 Page 5

 During a portion of the startup, some facilities use clean fuel ( natural gas) to heat up afterburners, raw materials, and eventually ignite the fuel source.  Routine observation of working equipment to assure proper function of emissions control equipment.  During startup, melting cupolas (furnace) and abatement equipment are monitored by temperature controls, air pressure and flow gauges within a specific operational range to ensure optimal and safe operations and low emissions.  Raw material quality is monitored via certificates of analysis when received from outside vendors.  If a malfunction occurs during startup, trained operators will quickly rectify the problem or move the cupola ( furnace ) into relief mode (pause startup and tap furnace). When problems have been rectified, startup can continue from where it was aborted. I f you have any questions, please do not hesitate to contact me. Sincerely, Angus E. Crane Executive Vice President, General Counsel cc: Mr. Keith W. Barnett Group Leader, Office of Air Quality and Planning Standards Sector Policies and Programs Divis ion, Mineral and Manufacturing Group U.S. Environmental Protection Agency 4930 Old Page Road Durham, NC 27703