PERMIT APPLICATION REVIEW SUMMARY

Transcription

1 PERMIT APPLICATION REVIEW SUMMARY New Hampshire Department of Environmental Services Air Resources Division P.O. Box 95, 29 Hazen Drive Concord, NH Phone: Fax: Location: South Main St., Franklin AFS #: Application #: FY Date: 4/18/07 Page 1 of 7 APPLICATION & OTHER COMMUNICATION: Date Description 6/23/06 Application received 7/14/06 Administrative Completeness Letter Sent PROJECT DESCRIPTION This application is for the renewal of State Permit to Operate, FP-S-0163 which expired on October 31, 2006 (application shield applies). FACILITY/PROCESS DESCRIPTION Webster Valve, Inc. (Webster) is a manufacturer of valves, regulators and backflow prevention devices for plumbing and heating and water quality applications. The operations at the Franklin facility include a non-ferrous foundry, operated under the internal business group termed Webster Foundry. The valve manufacturing operations (Webster Valve) are covered under State Permit to Operate, FP-S The company submitted a separate application, FY , to cover the renewal of this permit. Details of the Webster Valve operations are given in the application review summary for FY Webster s foundry operations produce bronze castings for use in the on-site manufacturing operations and for shipment to other manufacturing operations owned and operated by Webster s parent company, the Watts Regulator Company. Webster Foundry receives bronze ingot which is melted in electric induction furnaces and poured into sand molds to produce the castings made at the facility. The main operations in the foundry include: melting & pouring; core making; sand mold preparation; knock-out/shake-out, sand handling, and surface cleaning, grinding, chipping & trimming. Core Making Most of the castings produced by Webster Foundry are for valves and other flow-through devices. These types of devices require that the castings have interior as well as exterior details. This is accomplished through the use of mold cores. Cores are used to create the interior detail and dimensions of a hollow casting. Cores are made using penolic resin coated silica sand. The resin is heat set using core ovens, which utilize heated core boxes to form the shape of the finished core. Sand is gravity fed into the core box and the excess is poured out of the core box while the core is curing. Mold Preparation Sand molds are made using specialized, automated equipment. The prepared sand contains 3-4% moisture and does not generate dust during the process. Once a mold is made, it is conveyed to one of two turntables. Molds rotate two times through the turntable. On the first trip, the mold is poured. The mold is allowed to cool while it completes its second rotation. Bronze Melting and Pouring Webster Foundry operates three induction furnaces to support its metal casting operations. Each furnace is equipped with a fume hood and a fume-collecting device for pouring and slagging. The furnaces are charged using specially designed charge buckets, which deliver a 1,400 pound charge of bronze ingot and/or scrap bronze. Each charge bucket is equipped with a fume hood that collects any fume generated during the charging process. Each of the furnaces is charged approximately once per hour. Slag is removed from each furnace on a periodic basis. Once the bronze is melted and brought to the appropriate pouring temperature in the furnace, 300 to 500 pounds of molten metal is poured from the furnace to a pouring ladle. Each ladle is equipped with a hood and a travel vent which collects fume during pouring and transfer of the molten metal. The ladles are slagged at a ventilated slagging station. The metal is

2 AFS #: Application #: FY Date: 4/18/07 Page 2 of 7 then transferred to a holding furnace for automated pouring (Autopour) or poured directly into prepared sand molds at one of two pouring turntables. Prior to beginning manual pouring, a small amount of metal is poured from the ladle (called pigging) at a specially designed ventilated station. Manual pouring occurs at ventilated pour stations located on each of the two turntables. Due to the nature of the operations, a small fraction of the generated fume is not captured by the ventilation, and is instead emitted into building air around the melt deck. To prevent the uncaptured fume from entering other areas of the building, half-walls extend down from the ceiling and terminate 10 to 12 feet above floor level, isolating the melting and pouring area from the rest of the foundry building. Two roof fans are located above the area enclosed by the half-walls. Fugitive emissions from the melting and pouring operations rise with heat and are exhausted through the roof fans. It is estimated that the overall fume capture efficiency of the ventilation system is 95% with the remaining 5% emitted through the roof fans. Captured emissions are directed to two baghouses. The Autopour Baghouse is dedicated to automated pouring operations. The Melt Deck Baghouse controls emissions from all other melting and pouring operations. Knock-out/Shake-out Once a mold is poured, it remains on the turntable until it is knocked off by a new mold being loaded onto the turntable. The poured mold falls off onto a shaker table and breaks. Shaker tables, located beneath the foundry floor, carry the sand and castings away from the turntables and begin the process of cooling and separating the castings from the sand. The shake-out is a vibratory screen which separates most of the sand from the cast pieces. Sand that is removed by the shakeout is returned to the foundry sand system by an elevator. Castings, any sand that adheres to the casting surface, and large sand pieces that are not broken up by the action of the shake-out are passed on to the abrasive cleaning process. The conveyor, shake-out, and sand handling and preparation system are located within an isolation room that is maintained under a negative pressure, thereby effectively containing dust within the isolation room. Surface Cleaning, Grinding, Chipping and Trimming The primary abrasive cleaning machines are called wheel-blasts. The machines propel steel shot into a sealed, rotating drum containing the parts to be cleaned, to remove sand from the outer surface of the casting and remove any remaining pieces of the mold core from the inside of the cast part. The amount of metal processed by the primary wheel-blast machines is approximately equal to the total melt weight. The primary wheel-blasts utilize baghouses to control dust from the process. After the primary wheel-blast, good castings are separated from scrap metal which is returned to the bronze melt and pour process to be reused. The cleaned parts are sorted and cut as needed with an abrasive cut-off saw. The cutoff saw also uses a baghouse to control dust. Castings that proceed from the primary wheel-blasts to the secondary cleaning and finishing processes represent approximately 40% of the foundry s total melt weight. The castings are ground, chipped and/or trimmed as necessary to remove extraneous metal such as mold markings, unnecessary protrusions, and runners. Grinding and chipping occur at ventilated stations in the foundry grind room. Dust and metal grindings are collected in drop-out boxes and a baghouse. Trimming occurs with the use of presses and trim dies. The trimming process does not generate appreciable dust and has no emission points to the outside. The final stage in preparing castings for shipment is a secondary abrasive cleaning process. Two wheel-blast machines are used to achieve the final casting finish and to smooth out any markings made by the grinding and trimming process. Again, dust from the secondary wheel-blast equipment is controlled with baghouses. Sand Handling Prepared sand (the moist sand supplied to the molding machines) is comprised of silica sand, bentonite clay binder and water. These ingredients are prepared by mixing them together in a large mixer. Molding sand is continually reused within the sand system. Return sand from the shake-out is carried by an elevator, screened and stored in the main sand tank. New sand and clay binder are added to maintain the desired sand quality. The rate of new sand addition is proportional to the amount of metal being poured. As new sand is added, the volume of sand within the sand system exceeds the storage capacity of the sand tank. This excess sand (overflow sand) is displaced from the sand tank and recovered in portable bins.

3 AFS #: Application #: FY Date: 4/18/07 Page 3 of 7 The overflow sand is typically bagged and sent for recycling. The sand mixer, elevators and sand tank are all equipped with ventilation connected to a baghouse. Recyclable Material Handling Overflow sand, sand recovered from floors beneath equipment, baghouse dusts, and materials recovered from screening processes are loaded into bulk bags designed to hold up to 3,000 pounds of sand. Wherever possible, bags are filled directly from sand or dust discharge outlets. In this case, the bag is connected directly to the outlet and all dust remains in the bag. Sand that is not loaded directly into bags is brought to a central loading station in hoppers or barrels. The hoppers and barrels are emptied into an elevated bin, and the sand is discharged through a slide gate into a bag. The loading station is attached to a baghouse. Webster Foundry ships approximately 45,000 90,000 pounds of bagged sand for recycling each week. The following table summarizes the devices/processes located at the facility: Device Make/ Model # Startup Max. Capacity/ Control Device Date Usage Rate Three Induction Melting Inductotherm varies 5 tons metal/hr Melt Deck Baghouse Furnaces Manual Pour System Hunter tons metal/hr Melt Deck Baghouse Autopour charging and pouring Inductotherm tons metal/hr Autopour Baghouse Knock-out/Shake-out na? 5 tons metal/hr na all emission contained in isolation room Primary Wheel-Blast #1 Wheelabrator Super tons metal/hr Wheel-Blast Baghouse #1 Primary Wheel-Blast #2 Wheelabrator Super tons metal/hr Wheel-Blast Baghouse #2 Secondary Wheelabrator #1 Wheelabrator Tumblast tons metal/hr Wheelabrator Baghouse #1 Secondary Wheelabrator #2 Wheelabrator Tumblast tons metal/hr Wheelabrator Baghouse #2 Cut-off Saws Fox tons metal/hr Cut-off Saws Baghouse Grinding na? 5 tons metal/hr Grinding Baghouse Metal Marketer na tons sand/hr Metal Marketer Baghouse Bag Loading na tons sand/hr Metal Marketer Baghouse Sand Handling na tons metal/hr Sand System Baghouse Core Making Process Shalco, Redford tons resin coated core sand/hr Core Room Baghouse POLLUTION CONTROL EQUIPMENT The above table lists the pollution control devices for the various process devices at the facility. The following shows the collection efficiencies used for the calculation of emissions, as well as the typical pressure drop across the device: Control Device Capture Efficiency Removal Efficiency Typical Pressure Drop (in. water) Autopour Baghouse 95% 99.9% Melt Deck Baghouse 95% 99.5% Metal Marketer Baghouse 100% 99.9% Core Room Baghouse 95% 99.9% Cut-off Saws Baghouse 100% 99.9% Grinding Baghouse 100% 99.9% Sand System Baghouse 100% 99.9% Wheel-Blast Baghouse #1 100% 99.9% Wheel-Blast Baghouse #2 100% 99.9% Wheelabrator Baghouse #1 100% 99.9% Wheelabrator Baghouse #2 100% 99.9%

4 AFS #: Application #: FY Date: 4/18/07 Page 4 of 7 EMISSION CALCULATIONS/AIR TOXICS REVIEW Emissions were estimated using available emission factors, vendor/manufacturing data, analytical data and mass balance calculations. PM 10 emission factors were taken from the Emissions Inventory Improvement Program (EIIP) Document Series, Volume II, Chapter 14, Appendix A, Uncontrolled Emission Factor Listing for Criteria Air Pollutants, USEPA, EPA-454/R , June The EIIP document is a compilation of AP-42 and FIRE database emission factor data. Emission factors for grey iron foundries or steel foundries were used in the absence of data for brass/bronze foundries. The attached spreadsheet (Table 1) lists the emission factors used for the various processes. The following details the source of the factors. Core Making and Decomposition Emissions Emissions from core making occur as smoke and volatile compounds (phenol, formaldehyde and ammonia) generated when the core is made by heating the core sand in a core oven to set the resin. Emission rate data was obtained from the core sand manufacturer, Borden Chemical, Inc. Webster Foundry uses two core sand formulations, one with 3.0% resin content, the other with 1.75% resin content. Based upon the information supplied by Borden, the 3.0% resin sand produces higher emissions of RTAPs and was used to calculate the maximum emission rates. Quartz contained in the core sand remains encapsulated within the resin and is not emitted during the core making process. Further emissions from mold cores occur when the metal is cast. Thermal decomposition of the core resin occurs during the metal casting process. When the core is exposed to the heat of the molten metal, the emissions of a variety of compounds occurs. Emission rate data for the thermal decomposition of core sand was also provided by Borden Chemical. The attached spreadsheet (Table 2) shows the emission factors used for the core making process. The total potential VOC emissions from this process is 6.62 tpy. The facility-wide VOC emissions, which include the valve manufacturing process, have the potential to emit greater than 50 tpy, making the source a synthetic minor source of VOCs. Melting and Pouring Emissions from melting and pouring occur as particulate matter. Emission factors were developed in 2000 based on mass balance calculations using the amount of dust collected in the dust collectors and the capture and control efficiencies of the devices. The following assumptions were also used in developing the emission factors: The Melt Deck Baghouse dust collection rate is approximately three times higher than the Autopour Baghouse this is based upon the number and types of processes served. 80% of the dust collected by the Melt Deck Baghouse comes from charging and pouring operations. 20% of the dust collected by the Melt Deck Baghouse comes from manual pouring. All particulate is PM 10. Based upon the physicochemical properties of each element in the alloy, metal vapors are generated at the pouring temperature of 2100 F. Zinc boils at a much lower temperature (1664 F) compared to the other metals in the alloy and is readily volatilized at the pouring temperature. The zinc vapor is immediately oxidized to produce zinc oxide fume. Analytical results of the dust collected from the baghouses was used to determine the amount of RTAPs in the emissions. For zinc, an equivalent amount of zinc oxide was calculated using molecular weights. Tin data was estimated assuming that its concentration in the metallic fumes is less than or equal to that of copper. Details of the calculations used to develop the emission factors are given in Appendix A of the Air Toxics Impact Assessment dated December Surface Cleaning PM 10 emission factors for the primary and secondary abrasive cleaning operations were taken from the EIIP (used factor for grinding/cleaning). Individual RTAP emissions were determined using the weight % of the RTAP in the collected dust (see analytical data in 2000 air toxics report). For tin the concentration was calculated assuming that it is proportion to copper at the same % weight in the alloy used. For the cut-off saws the same PM 10 factor for grinding/cleaning from EIIP was used. Individual RTAPs were assumed to be equal to the composition of the bronze alloy.

5 AFS #: Application #: FY Date: 4/18/07 Page 5 of 7 Based upon particulate size data found in ACGIH, Industrial Ventilation, 19 th ed., 1986, the particulate emissions from the grinding operations were assumed to be greater than 10 microns in diameter, and are therefore not included in the RTAP analysis. Sand System A PM 10 emission factor from the EIIP for sand handling/grinding was used for the ventilated points of the sand system. Analytical data of the dust collected in the baghouse was used to determine individual RTAP emission rates. Metal Marketer The Metal Marketer is a sand handling/processing system in which sand is ground in a ball mill and screened to separate steel shot and bronze. The ball mill and screening processes are enclosed and vented to a baghouse which also serves the bag loader. An emission factor for sand handling/grinding was used to estimate the emissions from this device. Bag Loading Spent foundry sand that is to be sent off-site for reuse is bagged using a ventilated bagging station. It was assumed that this process has the same emissions characteristics as sand handling. The bag loader is vented to the same baghouse as the Metal Marketer. Air Toxics Review The attached spreadsheets show the maximum, daily emission rates based on the maximum capacity of the devices as stated in the permit application. Annual emissions are calculated by multiplying the maximum, daily emissions by 365 days/yr. Since the 2000 Air Toxics Report showed that controls are required for compliance, the controlled emission rates were used. Table 4 compares the emission rates to de minimus values and Table 5 calculates in-stack concentrations for pollutants that could not show compliance with de minimus emission rates. Nickel, toluene and xylene are emitted from Webster s valve manufacturing process and emissions of these compounds from the foundry operations were included in the air toxics review for the valve manufacturing process (see Permit Application Review Summary associated with application FY ). Some of the toxic metals are also expected to be emitted from an unpermitted waste oil burner. These emissions are included in this review. (Note all toxic emissions from the waste oil burner were evaluated in 2000 and it was determined that no permit is required for this device.) Attachment A summarizes the RTAPs emitted from Webster Foundry and the compliance determination method used to show compliance with the AALs. Hazardous Air Pollutants See Attachment B of the engineering summary for application FY for a list of HAPs and potential emission rates. STACK INFORMATION The following table details the stack parameters for the permitted devices at the source: Device Height (ft) Diameter (ft) Exit Area (ft 2 ) Flowrate (acfm) Temperature ( F) Exit Orientation Melt Deck Baghouse , vertical Autopour Baghouse , vertical Sand System Baghouse , vertical Primary Wheel-Blast # , vertical Primary Wheel-Blast # , vertical Secondary Wheelabrator # , vertical Secondary Wheelabrator # , vertical Cut-off Saws Baghouse , vertical Grinding Baghouse , vertical

6 AFS #: Application #: FY Date: 4/18/07 Page 6 of 7 Device Height (ft) Diameter (ft) Exit Area (ft 2 ) Flowrate (acfm) Temperature ( F) Exit Orientation Metal Marketer Baghouse 21 na , horizontal Core Room Baghouse , vertical Melt Deck Roof Stacks (1 and 2) 65 (each) 3.5 (each) ,000 (each) 70 vertical MODELING There are three air toxics, acrolein, benzene and hydrogen cyanide that required to be modeled in order to show compliance with Env-A Modeling was conducted for this source in April 2001 and compliance was shown. Since there have been no changes to the operations since that time, the modeling analysis is still valid and additional analysis is not required. EMISSION TESTING No emissions testing has been conducted at this source, and none will be required at this time. SITE VISITS/INSPECTIONS Date Description 9/21/05 Compliance inspection conducted by Ray Walters. No issues were found. 6/5/06 Barbara Dorfschmidt visited the facility to review operations and answer questions concerning the permit application. ANNUAL EMISSION REPORTS/FEES Annual emissions reports and fees for the facility are current through The following table shows the actual emissions from the facility for the past five years. (Note that emissions include those from both the foundry and the valve manufacturing operations). Year Particulates SO 2 NOx CO VOCs RTAPs Total CHANGES FROM PREVIOUS PERMIT Emissions from the Knock-out/Shake-out process are contained within the building and are therefore not an emission source. The process will not be listed as a permitted device. The current permit has restrictions on the total bronze melt and the amount of core sand processed. Since the facility is able to show compliance with Env-A 1400 without these limits, they will not be in the updated permit. The capture and control efficiencies of the baghouses shall not be listed in the updated permit. Since potential NOx emissions from permitted devices at the facility are < 10 tpy, additional NOx recordkeeping and reporting requirements are not applicable. REVIEW OF REGULATIONS State Regulations Env-A 600 Permitting (g) Applicable Actual VOC emissions from the facility are greater than 10 tpy (n) Applicable The source has accepted permit limits to classify itself as a synthetic minor source for VOCs and HAPs

7 AFS #: Application #: FY Date: 4/18/07 Page 7 of (v) Applicable The source needs controls and/or permit limits to maintain compliance with Env-A The table under Summary and Conclusions states the reason that the devices are required to be permitted. Env-A 700 Permit Fee System Applicable source subject to annual emission-based fees Env-A 900 Owner or Operator Recordkeeping and Reporting Obligations 903 Applicable 904 and 908 Applicable if VOC emissions > 10 tpy 905 and 909 Not Applicable potential NOx emissions from permitted devices < 10 tpy 907 Applicable annual emissions report 911 Only (b)(1) applicable to minor sources Env-A 1200 Prevention, Abatement, and Control of Stationary Source Air Pollution Not applicable because TPE of VOCs < 50 tpy for foundry operations (misc. source), and facility-wide emissions restricted to < 50 tpy. Env-A 1400 Regulated Toxic Air Pollutants 1402 Applicable The source requires controls and/or permit limits to show compliance with the AALs. Attachment A summarizes the RTAPs and associated emission rates evaluated for this permit application. Env-A 2400 Ferrous and Non-Ferrous Foundries, Smelters, and Investment Casting Operations Applicable TSP emissions shall be limited according to the formula stated in (c). E = 4.10P 0.67 Where E = maximum allowable particulate matter emission rate in lb/hr; and P = process weight rate in tons/hr - In addition particulate matter shall be limited to grains/dscf Table 6 of the attached spreadsheet calculates the particulate matter emissions from the various process and compares them to the above standards Applicable visible emissions shall not exceed 20% Federal Regulations 40 CFR 63, Subpart EEEEE National Emission Standards for Hazardous Air Pollutants for Iron and Steel Foundries (effective 4/22/04) Not applicable Webster Foundry is not a major source of HAPs. SUMMARY AND CONCLUSIONS The source is capable of meeting all applicable regulations. A State Permit to Operate has been drafted. The following table summarizes the devices at the facility requiring permits: Device Three Induction Melting Furnaces Manual Pour System Autopour charging and pouring Primary Wheel-Blast #1 Primary Wheel-Blast #2 Secondary Wheelabrator #1 Secondary Wheelabrator #2 Cut-off Saws Metal Marketer Bag Loading Sand Handling Core Making Process Grinding Reason Permit is or is not Required Facility-wide VOC emissions >10 tpy and restricted to < 50 tpy Controls are required for particulate compliance

8 ATTACHMENT A List of RTAPs and Emission Rates Evaluated RTAP CAS # Emission Rate Emission Rate Compliance (lb/day) (lb/yr) Determination Method Lead In-Stack Zinc Oxide (fume) In-Stack Zinc Oxide (dust) De minimus Copper (fume) In-Stack Copper (dust) In-Stack Quartz In-Stack Tin In-Stack Cadmium In-Stack Nickel In-Stack Antimony De minimus Phosphorous De minimus Formaldehyde In-Stack Phenol In-Stack Ammonia In-Stack Hydrogen Sulfide In-Stack Acrolein Modeling Benzene Modeling Hydrogen Cyanide Modeling Xylene Modeling Naphthalene De minimus Toluene In-Stack Notes: 1. Compounds listed in bold print require controls and/or permit limits in order to show compliance.