Transcription

ARKANSAS DEPARTMENT OF POLLUTION CONTROL AND ECOLOGYDIVISION OF AIR POLLUTION CONTROLSummary Report Relative to Permit ApplicationSubmittedBy:CSN: 01-0008Submittals:Riceland Foods, Inc., Soya DivisionH wy 79 and Park AvenueStuttgart, AR 72160Arkansas CountyContact Position: Environmental Engineer, Neil WashburnPhone Number: (501) 673-5337Permit No.: 908-AR-6Date Issued:10-18-96February 7, 1996SummaryRiceland Foods, Inc. (Riceland) operates a soybean processing mill, rice bran oil extraction plantand a grain dryer in Stuttgart, Arkansas.Permit modifications include the addition of agasification facility at Riceland and the incorporation of new AP-42 emission factors for grainhandling and vegetable oil processing. Permitted emissions from the facility will consist of231.1 tons per year of particulate matter, 1.4 tons per year of sulfur dioxide, 197.0 tons peryear of nitrogen oxides, 47.6 tons per year of carbon monoxide and 640.0 tons per year ofvolatile organic compounds. This reflects a decrease in particulate matter, sulfur dioxide andvolatile organic compound emissions and an increase in nitrogen oxides and carbon monoxideemissions.Permitted emissions from this facility will also include various hazardous air pollutants.Hexane, diethyl ether and petroleum ether are used at Riceland. These sources were modeledto determine their impact on air quality. The results obtained did not exceed the levels ofsignificance for any of the species.Process DescriptionDryer No.4Complex (SN-Ol through SN-16, SN-76 and SN-77)Dryer No.4 handles rice, soybeans, wheat, corn and oats. The complex consists of two units.One unit is referred to as the "West End" and was the original dryer permitted on May 26,1978, under permit 468-A. The other unit is designated as the "Annex" and was permittedunder permit 469-A.'Reviewed By: Melissa J. BlumenthalApplicable Regulation:Air CodeApprovedNSPSSIP4By: Keith A. Michaels

Riceland Foods, Inc., Soya DivisionPermit # 908-AR-6CSN: 01-0008The West End receives, cleans, dries, stores and loads out rice. The rice is scalped as it isreceived, placed into bins based on its moisture content and grade, dried and is then stored untilit can be sent to Riceland's Stuttgart Rice Mill. Soybeans are also received, scalped andtemporarily stored until they can be sent to the Soybean Terminal by conveyor. Also, wheat isreceived, dried and stored untilloadout.The Annex receives, cleans, dries, stores and loads out rice. The rice is scalped as it isreceived, binned by moisture content and grade, dried and stored untilloadout to Riceland'sStuttgart Rice Mill. In addition, soybeans are received, scalped and stored. The Annex alsoreceives oats and com. The com is dried, temporarily stored and then shipped from the facility.The oats require no processing and are placed in temporary storage upon receipt.All grain movement is accomplished through the use of belt conveyors, screw conveyors, dragconveyors and elevator legs. The conveying equipment is aspirated by the nuisance dustsystems. All other equipment such as receiving pits, grain dryers and grain cleaners havededicated dust collection systems.Terminal and Blending (SN-17 through SN-36)The BlendingElevator at the Stuttgart Soybean Division of Riceland is used to receive soybeansfrom the Terminal Elevators. These beans are transported from the terminal to the blendingelevator via a belt conveyor. The blending elevator also receives soybeans hauled by bulktransport trucks that are unloaded in the elevator dump pit.After the beans are received, they are stored according to their type, grade and/or moisturecontent. The different grades of soybeans are dried, cleaned and/or blended in this elevator toachieve the desired quality of beans before sending them to Prep to begin processing.The equipment used in the Blending and Terminal Elevators is simply grain drying, moving,handling and cleaning equipment such as dryers, belt and drag conveyors, cup elevators,scalperators and scales.Preparation and Extraction (SN-37 through SN-42)PreparationRaw soybeans are conveyed from storage on a belt conveyor which discharges into an in-processscale hopper. The scale hopper discharges batch-wise into a gyratory screener (bean cleaner)which separates oversize material. The oversize material is aspirated both from the top surfaceof the screener and as it is discharged into the oversize outlet on the side of the machine theoversize material is aspirated into the cyclones where it is separated from the air stream anddischarged through rotary valves into the top tray of the hull toaster.5

Riceland Foods, Inc., Soya DivisionPermit # 908-AR-6CSN: 01-0008Currently, soybeansare dried to lO % moisture and conveyed to the soybean preparation plant.This prep process removes the hulls from the beans and presses the bean meats into flakes thatare ready for the solvent extraction process.Soybeans are uniformly heated in the heater from ambient temperature to about 140 F. Thisbrings moisture to the surface of the beans. The heated beans are then passed through the jetdryer. This elevatesthe surface temperature of the beans, releasing the bond adhering the hullto the meat and driving off moisture. The recirculated air stream is passed through a cycloneto remove fines and loose hulls before being reheated.The hulloosenator splits the soybeans in half along the naturally existing bean division and rollsthe soybeanhull off the soybean meat. This separation is accomplished without the creation offines. The split soybeans and loose hulls fall from the hulloosenator into the top of theaspirator. The spilt beans cascade downward through a countercurrent stream of air. Theloosened hulls are aspirated out of the top of the aspirator into a cyclone and sent directly togrinding or toasting with no further separation needed.The cracking rolls fracture the beans into an appropriate size for flaking. The cracked meatsand remaining hulls drop into the conditioner. The meats cascade downwards, exiting at thebase of the machine conditioned to the proper temperature and moisture content for flaking.Hulls and fines are aspirated out of the top of the conditioner by a counter-flow stream of air.This air-hull mixture is separated in a cyclone and the air is recirculated.The hull screener separates the product aspirated from the conditioner. Large hulls are sent tohull toasting and grinding. Small hulls and small meats are sent to secondary aspiration. Finespass through to the flaking rolls.The secondary aspiration system separatesthe small hulls from the small meats. The small hullsare sent to grinding or toasting. The small meats are sent to the flaking rolls.Conditionedbeans discharge from the bottom of the bean conditioner into a leg which feeds theflaking mill feed screw. This screw conveyor discharges into six flaking mills which press thebean meats into flakes of thickness between ten thousandths (O.OlO)and sixteen thousandths(0.16) of an inch. The flakes fall out of the mills into a drag conveyor which moves themtowards the extraction plant. Excess bean meats which do not feed into the flaking mill areconveyed into an overflow bin which feeds a screw conveyor returning them to the beanconditioner.ExtractionSoybean flakes of thickness O.OlO" to 0.016" are conveyed to the plant in an inclined dragconveyor. This conveyor discharges into a short plug screw conveyor which feeds the extractor.The extractor is designed to process flakes from 1500 tons per day of raw soybeans. The hotdehull system allows Riceland to process 1600 tons per day of raw soybeans.6

Riceland Foods, Inc., Soya DivisionPermit # 908-AR-6CSN: 01-0008As the flakes are conveyed through the extractor, oil is removed with a series of hexane washes.Each hexane wash stream has a different but fairly constant concentration of oil. The mostconcentrated hexane stream is called the full miscella and is pumped to the distillation sectionof the plant for oil separation and solvent recovery. This section of the plant will be discussedlater in the description.The fully extracted soybean flakes drop out of the extractor into a vapor-tight inclined dragconveyor.This conveyor discharges into a short plug screw conveyor which feeds thedesolventizer-toaster-dryer-cooler (DTDC) vessel. This vessel consists of nine trays in a verticalarrangement. The flakes are held up for some time on each tray before being discharged to thetray below through a gate that opens and shuts to hold a constant level on each tray. On theupper three trays the flakes are heated indirectly with steam that is inside the steam chest of thetray. This drives the volatile hexane solvent and some of the moisture out of the flakes and intothe large overhead vapor line. These three trays comprise the desolventizing section of thevessel.The next two trays, or toaster section, also heat the flakes with indirect steam and serve toremove residual hexane, dry flakes further and kill any urease activity that remains on the flakes.The next tray is a sparge tray which distributes live steam into the vessel. The steam passesthrough holes in the upper five trays and helps to heat up the flakes so as to evaporate hexaneand water.The next two trays are the drying section of the vessel. Air is blown into the chest of thesetrays with an external fan and exits through holes that distributes air through the meal.By this time the flakes are broken up through drying and handling and the product can be termedmeal. Depending on ambient conditions, air is sometimes heated with steam coils before itenters the trays. The air exits the trays into two cyclones which remove meal dust andsuspended particles before the air is discharged into the atmosphere.The final tray serves to cool the meal before it is discharged from the vessel. Part of the airfrom the fan is diverted into the cooling tray. The air is not heated and it discharges into acyclone before exiting into the atmosphere. The dried and cooled meal is conveyed back to thebean preparation building where it is ground before being conveyed to storage.The full miscella (25-30% oil) is pumped into the tube side of the first stage evaporator. Thefirst stage is a vertical shell and tube heat exchanger. The shell side heat source is the vaporstream from the overhead of the DTDC. The hexane vapors that are boiled off in the tube sideof this evaporator go to the evaporator condenser where the hexane in condensed with coolingwater and recovered. The shell side vapors that are not condensed in the first evaporator passinto the vapor contactor where they are partially condensed with a stream of direct contacthexane. Residual vapors from this vessel pass into the DT condenser where they are furthercondensed with cooling water. The concentrated liquid miscella from the first stage evaporatoris preheated with product oil in a heat exchanger before being fed to the second stage7

Riceland Foods, Inc., Soya DivisionPermit # 908-AR-6CSN: 01-0008evaporator.This evaporator uses steam as its heat source. The overhead vapors from thisevaporator are also condensed in the evaporator condenser.The miscella that leaves thisevaporator is 90 % or above in oil concentration and is pumped to the oil stripper.The oil stripper is a distillation column with disc and doughnut internal distributors. The columnoperates under a high vacuum and removes the remaining hexane from the oil with livestripping. The overhead vapors are condensed in the stripper condenser and recovered. Thepure crude oil is pumped from the bottom of this column through a heat exchanger to be cooledand then transferred to the storage tanks.Vapors from the DT condenser, work tank, solvent water separator, waste water reboiler,extractor column and mineral oil stripper are all routed to the vent condenser where they arecooled and condensed with cooling water.Non-condensible and residual hexane from this condenser flow to the mineral oil absorber wherehexane is absorbed from the mineral oil. The mineral oil is heated and pumped to the mineraloil stripper where the hexane is stripped back out of the mineral oil with live steam. The steamand hexane vapors are routed to the vent condenser for recovery. The small amount of gasesthat exit the mineral oil absorber are vented to the atmosphere. This stream is primarily aircontaining approximately 2 % hexane.Meal Handling (SN-43 through SN-48 and SN-75)Soybean meal is a product of the grinding process and is stored in two locations (flat storage andmeal storage). The meal that is routed from the grinding process directly to flat storage iscarried by drag conveyors to an elevator. The meal is elevated to a drag conveyor on top of themeal storage facility. This conveyor also fills bins in meal storage and has a spout to feed flatstorage. Meal coming to flat storage can be routed either to storage or directly to trucks forloadout.Meal storage has a bag filter to minimize dust from the conveyors and elevators. Flat storagehas a bag filter to minimize emissions from the conveyor, elevator and truck loadout. Bentoniteis used in the meal handling operations to improve the flow characteristics and prevent mealfrom sticking to itself and equipment. The bentonite adds a slickness to the meal.Boiler and Heaters (SN-49 through SN-52. SN-66 and SN-69)Riceland employs the use of two boilers to generate steam for various processes throughout thesoybean mill. These boilers (#3 and #4) are natural gas fired with no supplemental firing of fueloil.In the refmery two heaters are used for Dowtherm heating and recirculation. These heaters (#3and #4) are natural gas fired. Dowtherm is also lost as a fugitive emission.8

Riceland Foods, Inc., Soya DivisionPermit # 908-AR-6CSN: 01-0008The gas plant has a natural gas fired refonner furnace.of hydrogen gas, which is used in the refinery.This furnace is used for the generationRice Bran Extraction Plant (SN-53 through SN-62)The Bran Oil Extraction Plant takes stabilized bran (pellets) received from the bran plants andextracts the oil. This crude oil is then sent to the refinery for processing into the final product.The stabilized bran is delivered to the extraction plant by truck. The trucks dump into thereceiving pit and the bran is conveyed to the stabilized bran bin. The bran bin is outfitted witha bin vent filter to control particulate emissions that are generated during the bin fillingoperation. From the storage bin the bran will be to the oil extractor.The extraction process produces hexane vapors, bran oil and solvent soaked (solventized) bran.The bran oil is collected and sent to the refinery for further processing, the hexane vapors arecondensed and the hexane is reused in the extraction process.The solventized bran istransferred to the DTDC for further processing.The solventized bran enters the DTDC where both steam and hot air are used to volatilize theexcess solvent. The steam stage of the DTDC produces hexane vapors that are collected andcondensed and the hexane is reused in the extraction process. The hot air stage of the DTDCproduces emissions of bran particulate and hexane vapors. High efficiency cyclones are usedto control the particulates generated from this process but the hexane emissions are uncontrolled.Once the bran leaves the DTDC it has had the oil removed, is dried and free of any solvent.This is known as defatted bran.The defatted bran is conveyed to the defatted bran bin where it is stored until it can be loadedout for reuse in the by-products plant. The defatted bran bin has a bin vent to control emissionsgenerated during the bin filling process and from the hammennill.Hexane vapors generated from the extractor and the DTDC are sent a vapor condenser thatgenerates liquid hexane and puts it back into the hexane storage tank. Vapors from thecondenser that do not become liquefied enter a mineral oil absorber system. This system usesmineral oil to capture as much remaining solvent as possible. The mineral oil system also ventsuncontrolled hexane vapors to the atmosphere.Lecithin Plant (SN-63 through SN-65. SN-68 and SN-72)Crude oil lecithin is received at the lecithin plant by truck. The crude lecithin is then fed to theextractors. Acetone is the solvent used in the extraction process. Crude oil rises to the top andthe bottoms are pumped to a slurry tank for further separation. The slurry is routed to a filterdrum, under vacuum, where a cake is pulled onto a cloth. This cloth is then dried and scraped9

Riceland Foods, Inc., Soya DivisionPennit # 908-AR-6CSN: 01-0008off to recover lecithin.to the granulator.The cake has about 40 % acetone which passes through a chute and onThe granules are then placed on a dryer bed. The dryer bed consists of two heating sections andconditioned air. Acetone vapors are pulled out of the dryer. Dry material is carried by screwconveyor and air to the rotex. The rotex grades out the granules as powder, granules and large.Each grade is drummed, sold and shipped by truck.The acetone vapors are routed to the VIC system. The VIC system consists of three carbonvessels. Two are always absorbing while the third is under a steam cycle. The three rotate onthis cycle. Condensed acetone is recirculated to the feed tank. The overhead crude oil from theextractor is sent to the settling tank. This is then sent to the evaporator. The first stage of theevaporator removes approximately 90% of the acetone. This acetone goes to the rework tank.The second stage removes the remainder of the acetone. Oil in the system is sent to an outsidetank and on to the refinery.An incline bag filter minimizes granule carry over from the dryer bed to the VIC system.Refinery (SN-70 and SN-71)The refmery receives various vegetable oils (soybean, rice bran, sunflower, peanut, etc.) fromoutside delivery and from within the facility itself. The purchased and manufactured crude oilsare stored at the refinery.Phosphoric acid is added to the oil to begin the process. The oilrange of 80 to 100 F. Caustic is added to the oil. The oilretention mixers. This mixture is then heated to about 180 F inthat the temperature and caustic levels are acceptable the oil isis then heated to a temperatureand caustic are then mixed inthe refinery heaters. Providedcentrifuged.Raw soap stock is drawn off, caustic added for saponification and sent to storage.sulfuric acid is added in the acidulator. Acidulated soapstock is then stored.From storageThe refmed oil is sent through a wash water heater and then to the scale tanks. The free fattyacid content of the oil is then checked. Oil that meets specification is sent to the bleachingdepartment and to storage. Rejected oil is reprocessed. From storage refined oil is processedin the converter. The converter hydrogenates the oil as necessary. The oil is then furthercleaned, filtered and refined to its final product. Due to the extremely low vapor pressure ofthese oils, emissions are insignificant.Wastewater Treatment (SN-73 and SN-74)Emissions from the wastewater treatment system are negligible.Wastewater sources areRiceland's downtown parboil plant, soya boiler blowdown and the refinery. The lime tank binvent does emit minimal particulate emissions.10

Riceland Foods, Inc., Soya DivisionPermit # 908-AR-6CSN: 01-0008Gasification - Cogeneration (SN-79 through SN-82)Rice hulls are delivered to the facility by hopper trucks which are unloaded into a receivinghopper that is equipped with screw conveyors that deliver the hulls to a bucket elevator. Theelevator conveys the hulls to another screw conveyor which will discharge the hulls into one oftwo storage tanks. Each storage tank will be equipped with a variable rate bin discharger thatwill deliver hulls to a second bucket elevator that will convey hulls to the gasifier metering bin.The system is designed to receive and store 75 tons per hour of hulls. The system can deliverup to 28 tons per hour to the gasification system.The receiving hopper will be located in a drive-through type shed to minimize fugitive emissionsfrom the unloading process and prevent rain from entering the hull conveying system,The gasification metering bin provides the surge capacity necessary to compensate for thevariations between the delivery and gasification rates. It is equipped with three variable speedscrew conveyors that deliver hulls to the gasification unit in response to the output of the plantmaster controller.The gasifier has three separate gasification units that convert the hulls to pyrolysis gas and ash.This is accomplished by the controlled application of air through the gasification unit grate asthe hulls are agitated in the fuel bed maintained on the grate. Air is provided by the gasificationair fan through a system of ducts and control dampers. Each gasification unit is a refractorylined, vertical steel chamber sized to provide the residence time required to complete thegasification process and minimize the quantity of particulate matter carried over with thepyrolysis gas.Ash is discharged from the bottom of each gasification unit into water cooled screw conveyorsthat cool the ash. It is then transported to a pneumatic conveying system that is part of the ashconveying and storage system. Pyrolysis gas is discharged from the top of the gasification unitsto the S-TECS thermal energy conversion system (TECS). The gas produced from the rice hullswill then be used as a fuel.The gasification system is designed to consume 52,200 pounds per hour of rice hulls and deliver206.7 MMBtu per hour of high temperature pyrolysis gas to the TECS. The gas temperaturewill vary between 11000P and 1500oP, depending on the desired ash quality. The quantity ofash produced will be approximately 16,000 pounds per hour at rated capacity.The ash conveying and storage system includes pneumatic conveying systems that will receiveash from the cooling conveyor discharge on the three gasification units and transport it to threestorage tanks. Each storage tank is equipped with a pneumatic receiver that will discharge ashto the storage tank and exhaust conveying air to a common header. The air will be directedthrough a fabric filter to control particulate emissions from the conveying system.11

Riceland Foods, Inc., Soya DivisionPermit # 908-AR-6CSN: 01-0008The storage tanks will be designed for unloading into trucks that will transport the ash to off-siteutilization or disposal facilities. The system will be designed to load trucks at the rate ofapproximately 24 tons per hour. The truck loading area will be enclosed in a drive-through typeshed to minimize fugitive emissions from the truck loading area.12

Riceland Foods, Inc., Soya DivisionPennit # 908-AR-6CSN: 01-0008Specific Conditions1.Emissions shall not exceed the emission limits set forth in Table I of this permit.Emissions from any point source not specifically listed in Table 1 of this permit shall beconsidered a violation of this permit.2.Visible emissions from each source shall not exceed the opacity limits specified in Table Iof this permit as measured by EP A Reference Method 9.3.No ground-level visible emissions that reasonably can be expected to become materiallyinjurious to human, plant or animal life, or property; or which unreasonably interfere withenjoyment of life or use of property; shall be permitted beyond the facility property line.4.Grain received at Riceland shall not exceed the limits set forth in the following consecutiveYearlyLimit- duringany 12 month periodSoybeansDescription(tons/yr)tnsatCompliance with Specific Condition #4 shall be verified by maintaining monthly recordsof the amount of raw ingredients received over the previous 12 month period. Theserecords shall be updated no later than the 15th day of the month following the month whichthe records represent.Records shall be kept on site and shall be made available toDepartment personnel upon request.5.Pipeline quality natural gas shall be the only fuel used at this facility.6.Natural gas usage shall not exceed 229 million standard cubic feet (set) per month or 2,748million scf during any consecutive 12 month period. The permittee shall maintain monthlynatural gas records for the previous 12 month period, updated on a monthly basis. Theserecords shall be updated no later than the 15th day of the month following the month whichthe records represent. Records shall be kept on site and made available to Departmentpersonnel upon request.13

Riceland Foods, Inc., Soya DivisionPermit # 908-AR-6CSN: 01-00087.The permittee shall not receive in excess of 353,300 gallons of hexane per twelveconsecutive months.The permittee shall maintain records of the amount of hexanereceived. Records shall be updated by the last day of the following month, kept on siteand provided to Department personnel upon request.8.The permittee shall not receive in excess of 130,000 gallons of acetone per twelveconsecutive months. The permittee shall maintain records of the amount of acetonereceived. Records shall be updated by the last day of the following month, kept on siteand provided to Department personnel upon request.9.The permittee shall keep monthly and annual records of all hexane, diethyl ether andpetroleum ether received and used at the facility on site. A yearly VOC usage report (Jan.- Dec.) shall be submitted to the Department at the address listed below. The next annualreport shall be due by February 1, 1997.Arkansas Department of Pollution Control and EcologyAir DivisionAttn: Compliance Inspector SupervisorP.O. Box 8913Little Rock, AR 72219-891310.The gasifier hull receiving tanks (SN-80) shall not receive in excess of 245,280 tons of ricehulls per twelve consecutive months. The permittee shall maintain records of the amountof rice hulls received. Records shall be updated by the last day of the following month,kept on site and provided to Department personnel upon request.11.The permittee shall not unload into trucks in excess of 24 tons of rice hull ash per hourfrom the gasifier ash loadout area (SN-82) or 70,080 tons of rice hull ash per twelveconsecutive months. The permittee shall maintain records of rice hull ash loadout intotrucks. Records shall be updated by the last day of the following month, kept on site andprovided to Department personnel upon request.12.The permittee shall comply with the applicable provisions of the Arkansas Air PollutionControl Code (Air Code) and the regulations of the Arkansas Plan of Implementation forAir Pollution Control (SIP).13.The permittee shall comply with all regulations under the New Source PeiformanceStandards (NSPS) of 40 CFR Part 60, Subpart DD - Standards of Performance for GrainElevators.14.Particulate emissions from any NSPS source, except grain dryers, shall not exceed 0.023grams per dry standard cubic meter (0.01 grains per dry standard cubic foot) at any time.14

Riceland Foods, Inc., Soya DivisionPermit # 908-AR-6CSN: 01-000815. The control equipment associated with this plant shall be maintained and operated inserviceable condition as prescribed by the manufacturer during operation of this plant.16. The permittee shall modify this permit prior to making any changes in production oroperation which would increase emissions above the allowable permit limits. Physicalmodifications, construction and reconstruction which results in emission changes notspecifically allowed under Section 19.4(k) of Regulation 19 will require a full permitmodification prior to their implementation.17. Permit #908-AR-6 shall supersede all previously issued air permits. Permit #908-AR-5 ishereby revoked.15

Riceland Foods, Inc., Soya DivisionPermit # 908-AR-6CSN: 01-0008TABLE etedPMIOPM310CyclonesALLOW ABLE EMISSION RATES16

Riceland Foods, Inc., Soya DivisionPermit # 908-AR-6CSN: b/hr1010 10PM 10PMPMPMALLOW ABLE EMISSION RATES17

Riceland Foods, Inc., Soya DivisionPermit # 908-AR-6CSN: PM 10ALLOW ABLE EMISSION RATES18

Riceland Foods, Inc., Soya DivisionPermit # 908-AR-6CSN: egulation%lb/hr10PM 1010ALLOW ABLE EMISSION RATES19

Riceland Foods, Inc., Soya DivisionPermit # 908-AR-6CSN: 0.70.23.4SIPIP.5252013.34042.0Vent2.51.21.50 evatorElevatorSystem-1977Description%Bagh

Arkansas County Contact Position: Environmental Engineer, Neil Washburn Phone Number: (501) 673-5337 CSN: 01-0008 Permit No.: 908-AR-6 Date Issued: 10-18-96 Submittals: February 7, 1996 Summary Riceland Foods, Inc. (Riceland) operates a soybean processing mill, rice bran oil extraction plant and a grain dryer in Stuttgart, Arkansas.