# ATTACHMENT 1

Generic Flow Diagrams for PVC Production06/25/08Fig 1. Suspension and Dispersion Processes Flow DiagramSD1VCStorageUnloadingHolding TankWeighingTankPolymerizationReactorPolymerStrippingVesselKnock-outPotVC RecoverySystemBlend TanksDryingCyclone & orScreeningPVC Storage& ShippingProcess StepsSD1. VC Unloading and StorageSD2. Mixing, Weighing and HoldingSD3. Polymerization ReactionSD4. Resin StrippingSD5. Recovery SystemSD6. BlendingSD7. DryingSD8. PVC StorageSD9. “In Process” Wastewater StrippingSD10. Control Device System (e.g. Incinerator)ToWastewaterStripperCentrifugeToWastewater TreatmentControlDeviceCausticNat. GasWater“In Process” wastewater1) H2O from Double Mechanical Sealson all Pumps, Compressors andAgitators2) H2O from Reactor Evacuating Priorto Opening3) Knock-Out PotsWastewaterStripper“In Process”WastewaterTo ControlDeviceSteamTo WastewaterStripperSD6SD3SD2SD5SD7SD10SD4SD9SD806/25/08Fig 2. Bulk Process Flow DiagramB1VCStorageUnloadingHolding TankWeighingTankPrePolymerizationReactorPostPolymerizationReactorKnock-outPotVC RecoverySystemBlend TanksPVC Storage& ShippingProcess StepsB1. VC Unloading and StorageB2. Mixing, Weighing and HoldingB3. Pre-Polymerization ReactionB4. Post-PolymerizationB5. Recovery SystemB6. Blending and ScreeningB7. “In Process” Wastewater StrippingB8. PVC StorageB9. Control Device System (e.g. Incinerator)ToWastewaterStripperControlDeviceCausticNat. GasWater“In Process” wastewater4) H2O from Double Mechanical Sealson all Pumps5) Condensed Steam from ReactorEvacuating Prior to Opening6) Condensed steam from PolymerStrippingWastewaterStripper“In Process”WastewaterTo PondSteamTo WastewaterStripperB6B7B9B4B8B3B2SD5RefluxCondenserCourseScreeningFineTo ControlDevice

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### 1 06/25/08 Production of Polyvinyl Chloride: Process Description

Note: The majority of the information represented in this document is taken from EPA’s February 1982
document entitled: Vinyl Chloride- A Review of National Emission Standards (EPA-450/3-82-003). Where necessary, minor changes were made to represent current operations.

In the United States, four polymerization processes are being used currently to manufacture PVC
resins:
1. Suspension
2. Dispersion (emulsion)
3. Bulk (mass); and,
4. Solution.

Figure 1 in Attachment 1 shows a generic flow diagram for PVC production by the suspension and dispersion processes. The process steps, which are numbered, are described below. The potential emission points for each of the process steps shown in Figure 1 are listed in Table 1 along with a summary of VCM NESHAP requirements for control of emissions.

Figure 2 shows a generic flow diagram for PVC production by the bulk process. The potential emission points for each of the process steps shown in Figure 2 are listed in Table 2 along with a summary of VCM NESHAP requirements for control of emissions.

Note that it is the Vinyl Institute’s understanding that Dow, Freeport, TX operates the only solution PVC production process in the United States. Dow, the only US PVC producer who is not a Vinyl Institute member, has been contacted and information has been shared.

Many companies have licensed some phase of their particular process such as stripping technology or clean reactor technology. The licensing of these process phases has evolved from the intensive research work done to reduce residual vinyl chloride monomer (RVCM) levels in finished resins, limit worker exposure, and reduce emissions to the atmosphere.

After polymerization, VCM may be present in any of three forms in the polymerization reactor depending on the particular process. VCM will always be present separately as a gas or liquid in the reactor and will also be trapped within the newly formed polymer resin. In the suspension, dispersion, and solution processes, VCM will be trapped in the process water.

The resins produced by a process are categorized as to the “type” of resins. Those processes responsible for more than one variation of their type of resin are further subdivided into “grades.” The resin grade is developed to allow compounding and fabrication to yield the desired product.

A plant manufacturing polymers containing any amount of polymerized VCM is subject to the current VCM NESHAP at 40 CFR Part 61 Subpart F.

Free Radical Polymerization Polymerization is the chemistry of combining simp le molecules (monomers) into long chains of repeating molecular units (polymers). There are two types of polymerization – addition and condensation. PVC resins are commercially produced by addition polymerization and, in general, polymerization is induced by the use of free radical initiators (Nass, 1977, p. 34). Thermal decomposition of the initiator, which is combined with the VCM and other constituents in the polymerization reactor, yields free radical molecules having one unshared electron. This free radical reacts with additional VCM molecules by removing an electron from the VCM double covalent bond

### Attachment 2



### 2 and sharing an electron with the free radical. The remaining unshared electron moves along the chain becoming the new radical bond site. Another VCM molecule may then become a part of the polymer chain by reacting with the polymer radical.

Radicals are transferred from the polymer by a reaction with the VCM to yield a polymer and a free radical. The transfer reaction increases with increasing temperature. This characteristic of the reaction kinetics allows a desired molecular weight to be obtained by controlling reaction temperature (Cameron, 1979, pg 39). Radicals are also transferred by reacting with hydrogen atoms obtained from VCM or solvent in the reactor. Another way of transferring radical sites from the growing polymer chain is by using chain transfer agents (CTA). These CTAs are used to regulate the molecular weight of the polymer to a desired level. In all transfer reactions, the radical is released and able to initiate another polymerization reaction. The reaction is terminated when two polymers with radical sites are combined. Polymerization rate is controlled by choice of the appropriate initiator.

The polymerization reaction is exothermic and the reaction rate must not be allowed to accelerate to the extent that the heat of reaction cannot be removed by reactor control devices. Reaction rates tend to increase as the temperature increases. If the heat of reaction is not removed, a runaway reaction can develop and the rapid increase in temperature will increase the pressure inside the reactor vessel beyond safe limits.

The monomer structure of VCM is capable of several variations in chain structure, but free radical polymerizations generally produce atactic structures, (random orientation of monomer unit in the chain structure) (Nass, 1977, p. 46). Tendency towards syndiotactic structure (regular alternating
orientation of the monomer unit in the chain stru cture) and crystallinity are both increased by reduced polymerization temperatures.

Suspension Polymerization Process Step SD1: Unloading at PVC Plant Sites Under the current VCM NESHAP, VCM emissions from loading and unloading lines, which are opened to the atmosphere, must be reduced in the opened lines to 0.0038 cubic meters (0.13 cubic feet) or less at standard temperature and pressure (STP). Also, the VCM removed from loading and unloading lines in order to meet this requirement of the VCM NESHAP must be vented to a control device system from which the concentration of VCM in the exhaust gas does not exceed 10 ppm. When PVC plants are not located close enough to receive VCM by pipeline, it is shipped by railcar, tank car, barge, or marine vessels.

The VCM is normally unloaded at PVC plants by disp lacement. This is accomplished by pumping vapor from storage tanks into the transfer vessel which displaces the liquid VCM from the transport vessel through the unloading line. When the liquid VCM is displaced, the compressor line is reversed and used as suction to evacuate remaining liquids as vapor. The remaining liquid VCM is allowed to boil during tank car evacuation for its removal as a gas. This vaporization of the VCM usually takes 20 to 30 minutes (Mukerji, 1977, p. 155). Lines between tank car compressor and storage tank can be switched without disconnection by incorporating a 4-way valve in the pumping lines. Instrumentation of the system usually incorporates a turbine meter, a flow totalizer to measure the VCM flowrate and quantities unloaded, and storage tank level indicators.

Unloading and transfer lines may be purged with nitrogen to reduce VCM to the required level before disconnection of the unloading lines. In some cases, the portion of the unloading line which is opened to the atmosphere has been reduced to diminish the amount of VCM that will escape to the levels below those required by the VCM NESHAP.

Unloading of relatively small amounts of additive materials can involve various containers, such as
drums or totes.

### Attachment 2



### 3 Process Step SD2: Mixing, Weighting and Holding Vessels Storage spheres, storage tanks, gasholders, wastewater storage tanks, knockout pots, and surge tanks are representative of vessels covered under sections 61.64(c) of the VCM NESHAP for mixing, weighing, and holding vessels. These vessels are used to hold liquid or gaseous VCM and PVC slurry during various stages of the PVC process. Some of these vessels were open to the atmosphere prior to promulgation of the VCM NESHAPs, but have since been enclosed and are usually ducted to the recovery system and/or the primary control device. The number and types of vessels will vary from plant to plant depending on the size and type of process used to produce the PVC resin. The majority of small additive tanks or totes are open to atmosphere, but emissions are minor and/or may be exempt from control under other Maximum Achievable Control Technology (MACT) Standards, such as the Organic Liquids Distribution MACT.

Section 61.64(c) of the VCM NESHAP requires the concentration of VCM in all exhaust gases discharged to the atmosphere from mixing, weighing, and holding containers “in VCM Service” not to exceed 10 ppm. Any piece of equipment that contains or contacts a fluid that is 10 percent by weight, VCM, or gas that is at least 10% by volume, is considered “in VCM Service.” There are no requirements in the VCM NESHAP for mixing, we ighing or holding containers used in the process after the stripping of the PVC resins providing resin stripping is used. This not unlike the recently promulgated Miscellaneous Organic NESHAP (MON) regulation (see MON’s definition of Miscellaneous organic chemical manufacturing process at 40 CFR 63.2550).

Process Step SD3: Suspension Polymerization The suspen sion process for producing PVC resins (see Figure 1) is characterized by the formation of polymers in droplets of the liquid VCM (or other co-monomers) suspended in water. These droplets are formed by agitation and the use of protective colloids or suspending agents. Protective colloids commonly used are water-soluble polymers such as modified cellulose or partially hydrolyzed polyvinyl acetate. The process is started by evacuating the polymerization reactor to remove oxygen and other contaminants that may inhibit the reactor initiator. Water and VCM may be simultaneously added to the reactor with the protective colloids, or they may be added separately (water and colloids first, followed by the liquid monomer). The water used is deionized and deaerated in order not to inhibit free radical initiator formation. Water and other ingredients charged to the reactors must be carefully measured prior to charging. In some cases the reactor is on a scale and the amount of material charged is weighed in the reactor. More often, a separate weigh tank is used to measure materials charged to the reactor. A flow meter can be used to record the amount of water added. Reactor operators manually charge additives that are used in small proportions. The initiator is usually the last ingredient charged to the reactor. Initiators commonly used in the suspensions process are peresters, peroxycarbonates, peroxides, or azo compounds. The initiators are soluble in VCM and allow formation of PVC in the monomer droplets. Some initiators have low levels of impurities and can produce low levels of decomposition products.

After all the materials are in the reactor, the batch is brought up to reaction temperature by passing steam through the reactor jackets which allows free radical initiators to be formed. Reaction temperatures are varied in order to produce a resin grade of a particular molecular weight. Once polymerization is initiated, the reaction becomes exothermic and cooling water must be circulated through the reactor jacket to remove heat of reaction. In some instances reflux condensers have also been used to control reaction temperature and remove excess heat.

After approximately 6 hours in the reactor, the batch temperature and pressure drop. This signifies that nearly all the VCM has reacted (75% to 90% of the VCM usually reacts) and the remaining or residual VCM (RVCM), which is in the liquid or gaseous state or trapped in the resin particles, must be stripped. This RVCM is usually stripped with st eam under vacuum. The suspension process yields a

### Attachment 2



### 4 particle size distribution of a much wider range than other polymerization processes. Particle size may range from 90 micrometers to 130 micrometers (0.0035 inches to 0.0050 inches) with low to medium molecular weights.

Process Step SD4: Resin Stripping The VCM NESHAP req uires that RVCM levels for suspension resins not exceed 400 ppm of the PVC product. PVC resin, unreacted VCM (in the water, in the headspace, and trapped in the resin) and water are the constituents remaining in the reacto r after polymerization. This polymer slurry may be steam-stripped of RVCM batch wise in the reactor or is a separate vessel. B. F. Goodrich has developed a continuous stripping operation which strips the resin with steam running countercurrent to the PVC slurry. Most plants strip batch wise with steam in separate vessels or in the continuous stripping column. In all cases, water accompanying the PVC product is stripped with the slurry and then removed by centrifugation.

Batch stripping procedures use temperatures up to 87 deg. C (190 deg. F) and a vacuum of 91 kilopascals (27 inches of mercury) or more (Na ss, 1977, pg 83). Heat is applied by steam injected directly into the batch or by steam passed through the reactor wall jackets. If stripping is used to meet RVCM levels, any downstream processes or equipm ent (e.g., water treatment, vents from mixing tanks, centrifuges, dryers, etc.) are not required to meet any other requirements of the VCM NESHAP.

Process Step SD6: Blending After stripping, the bat ch is transferred to blend tanks which mix the batch with other batches to ensure product uniformity. The mixed batches are then fed to a continuous centrifuging operation that separates the polymer from the water in the slurry. Both mixing tanks and centrifuges are vented to the atmosphere if stripping is utilized. The water from centrifuging is not required to be stripped of VCM because most of the VCM is removed during resin stripping. Therefore, the centrifuge water is recycled back to the process or discharged to the plant’s wastewater treatment system.

Process Step SD7: Drying The wet cake from centrifuging is conveyed to a rotary dryer for further removal of the remaining (usually 25 percent) moisture (Nass, 1977, p 83). Mo st of the RVCM not removed during stripping will be released during the drying operation. Counter-current air temperatures in the dryer range from 65 deg. C to 100 deg. C (150 deg. F to 201 deg. F). Drying time is generally short, but large volumes of air containing RVCM are released.

Process Step SD8: PVC Storage After drying, the resin may be screened to remove agglomerates. The resin is then bagged or stored in silos for bulk shipment by trucks or rail car. Uniformity of suspension resin batches is dependant on
control of variable such as:

 Impurities (noncondensable gases present in the reac tor prior to polymerization or impurities in raw materials charged to the reactor),

 Rate of temperature increase to reaction temperature,

 Agitation speed and schedule (speed varies as the slurry becomes more dense),

 Charging rate of raw materials, and

 Temperature of raw materials charged.

In some of the newer PVC facilities, these variables are closely monitored by level of computer control. In the older plants, many variables such as cooling water flow rates, pump operation, agitator motors, temperature, and pressure are monitored and controlled manually from the control room panel or at the reactor. More versatility is possible with computer assistance. A reactor linked to computerized control elements can produce different grades of resin by using programs designed to yield specific reactor conditions (e.g., agitation, temperature, amount, and type of materials charged)

### Attachment 2



### 5 that will produce the desired resin product. Computers can also monitor operating conditions and respond to emergencies (such as high pressure in the reactor). They can be programmed to take necessary action to bring an upset condition under control (e.g., choosing the best compensatory action.)

The use of large reactor systems has increased quality control and allowed incorporation of equipment and procedures that reduce VCM emissions. Large reactors, approximately 8,000 gallons (30 cubic meters) and up, offer lower plant cost, improved product uniformity, and increased productivity. However, certain PVC units utilize smaller reactors.

Process Step SD9: “In Process” Wastewater
Water used in the PVC process can become contaminated with VCM and be a source of secondary emissions if not contained and controlled. Even though the requirements of the VCM NESHAP for fugitive emission controls (equipment specificat ions, operational procedures and leak detection and elimination programs) are not applicable to inprocess wastewater, it is still categorized as a fugitive emissions source. The VCM NESHAP requires the concentration of VCM in each wastewater stream containing greater than 10 ppm VCM measured imm ediately as it leaves a piece of equipment, and before being mixed with other wastewater, be reduced to 10 ppm VCM or less. This concentration in the water must be attained prior to mixing with other inprocess wastewater containing 10 ppm or less VCM, before being discharged to a wastewater treatment process or plant, or before being discharged untreated to a body of water.

There are several sources of inprocess wastewater in PVC plants. VCM contaminated inprocess wastewater is generated from the following sources:

 Water used to evacuate reactors prior to opening in order to meet reactor opening loss (ROL) requirements;

 Water used as sealing fluid for double mechanical seals on pumps, compressors and agitators;

 Water removed by knock-out pots used in the monomer recovery system; and,

 Water used to seal gasholders.

Depending on the methods used to attain the ROL requirement, large quantities of inprocess wastewater can be generated.

Inprocess wastewater from ROL methods, seals, and knock-out pots is usually collected in a vessel and then steam stripped of VCM. Water used to seal gasholders is in contact with VCM contaminated gases and by definition is an inprocess wastewater. This water is always exposed to atmosphere without treatment. Actual VCM concentrations of this seal water are generally not available, but for one plant using a water-sealed gasholder, emissions to the atmosphere from the seal were calculated to be approximately 0.79 kilograms (1.75 pounds) per year (Battye, 1978).

Removal of VCM dissolved in water is usually accomplished by a distillation column. The water collected by fugitive emission sources, and usually held in a vessel prior to the column, is close to saturation. Thus, separation in the stripping column is simple because the vapor pressure of VCM is much greater than water.

Process Step SD10: Control Device Most of the requirements of the VCM NESHAP pertain to PVC plants because these facilities contribute proportionality more emissions than VCM plants. The characteristics inherent in the batch processes of PVC plants account for the relative difficulty in emission control implementation.

### Attachment 2



### 6 Control devices, applied to reduce VCM emissi ons when exhaust gases are discharged to the atmosphere, include:

Incineration – This method represents the most prevalent means of primary control and is the only method used by both VCM and PVC plants (collocated). (Solvent absorption and carbon adsorption are also used as primary controls in PVC plants, but in VCM plants they are used on a smaller scale as part of the process or as a means to reduce fugitives).

Although thermal incineration is most commonly used, in the past, two plants used catalytic oxidation systems. At least one of those plants has been shutdown. In most cases, thermal incineration is reducing emissions below the required 10 ppm. Most units have scrubbers to prevent HCl emissions.

Solvent Absorption – This method is effective in reducing emissions below 10 ppm. It is used as primary control only in PVC plants. VCM is recovered by this method, rather than destroyed (as with incineration).

Dispersion Polymerization The Process Steps for dispersion resins are similar to those of suspension resins.

Although dispersion (emulsion) resins are formed in reactors similar to those used for suspension type resins, reaction kinetics of polymer formation vary gr eatly. In general, dispersion resins are of a high density with small particle size. The process is initiated by charging the necessary ingredients (water, liquid, VCM, emulsifiers, and a free radical initiator) to an evacuated reactor. Proportions of these ingredients and other minor additives will vary depending on the type of resin and the resin grade. Emulsifiers (soaps and surfactants) are used to disperse VCM in the water phase. Soap micelles (i.e., colloidal aggregates that are formed above a critical emulsifier concentration) also contain small amounts of VCM and are the site of polymer formation. Initiators used are water soluble (versus VCM soluble initiators used in suspension polymerization) and penetrate soap micelles to begin polymerization. Commonly used initiators are hydrogen peroxide, organic peroxide, and peroxydisulfates.

Two general types of resins are produced by the dispersion process- latex and dispersion. If the latex type resin is to be produced, only a small amount of VCM and initiator are normally charged. The reactor is heated by injecting steam into the reactor jackets to initiate formation of free radicals. Agitation is used to disperse the monomer and other ingredients in the water medium. Once polymerization begins, the heat of reaction is removed by circulation of cooling water through the reactor jackets. Small amounts of initiato r and monomer are then continuously added during polymerization until the correct particle size is attained. Conversion of VCM to latex polymer is almost complete. Latex resin particle sizes range from 0.05 micrometer to 2 micrometers.

The residual VCM is removed from the latex resins by completely reacting the free VCM with additional catalyst (post-catalysis). This is done in the reactor or in a separate vessel. The VCM NESHAP requires that latex resins be stripped to 400 ppm RVCM. Latex resins are usually sold in solution, and drying or separation of resin from the polymer slurry is not necessary.

The process for formation of dispersion type resins follows that described for latex except that some monomer is added to allow particles to grow to a larger size. In some cases the process may call for “seed” latex. The “seed” latex is formed by starting a batch in a separate reactor. Before this batch reaches 60 percent conversion it is transferred to other reactors with more VCM and emulsifiers. This allows formation of larger emulsion particles which are used in plastisol and stir-in resins. These dispersion type resins range from 0.2 micrometers to 5 micrometers in particle size and are more sensitive to heat and mechanical agitation than suspension resins. Because the dispersion resins are

### Attachment 2



### 7 more sensitive, stripping the resin may take longer because lower stripping temperatures are used. The VCM NESHAP requires that dispersion ty pe resins be stripped to 2,000 ppm RVCM.

After polymerization is complete, the dispersion resins are usually spray dried. Spray-dried resins contain emulsifiers that inhibit the absorption of plasticizers. In many applications where heat is applied during fabrication, this property is acceptable because the heat melts the resins which allows plasticizer absorption. In some fabrication processes (such as calendaring), plasticizers must be absorbed prior to fabrication because temperatures used are not high enough to melt the resin. If removal of the soaps from the dispersion resin is desired, coagulation of emulsifiers with salts is usually performed. The salts (calcium or magnes ium) are added to the polymer slurry and the emulsifiers precipitate and are rinsed out with water. The resin and water are then separated and the resin is dried in a rotary or pan dryer (Erdman, 1980).

Bulk Polymerization

The following Process Steps for bulk resins are similar to those of suspension and dispersion resins: B1: Unloading at PVC Plant Sites B2: Mixing, Weighing and Holding Vessels B5: Recovery System B7: “In Process” Wastewater Stripping B8: PVC Storage B9: Control Device

Bulk (mass) polymer resins are produced by a tw o-stage polymerization process. A simple diagram of the bulk process is shown in Figure 2 and requi rements of the VCM NESHAP for bulk plants aresummarized in Table 2. The first stage is the formation of a “seed” resin in a vertical prepolymerization (Pre-Po) reactor. The “seed” resin is transferred to a horizontal post-polymerization (Po-Po) reactor in the second stage of the process. More VCM is added to the Po-Po which allows the “seed” resin to grow in size to the finished resin product. The bulk process differs from the dispersion process in that no water is used in the reaction – the process is anhydrous. The bulkprocess used in this country is licensed by Rhone-Poulenc of France. A new version of the RhonePoulenc process utilizing a vertical Po-Po reactor is now available, but is not currently being used in the United States.

Process Step B3. Pre-Polymerization The Pre-Po reactor is charged with liquid VCM and enough initiator to carry the reaction to approximately seven to twelve percent conversion. Initiators used are those commonly used in the suspension process – an oil soluble, free radical catalyst (Nass, 1977). The Pre-Po reactor is brought to an operating temperature of 40°C to 70°C (130°F to 184°F) by injecting steam into the reactor jackets. Strong agitation is used to form small particles of approximately 1 micrometer (Nass, 1977, p. 75). These small particles provide the “seed” that grows in size to form resin beads in the Po-Po reactor. The remaining liquid VCM and seed resin are pumped to the Po-Po reactor at approximately 7 to 12 percent conversion.

Total cycle time for the Pre-Po is 2 hours (Dubec, 1980) which is normally one-fifth the duration of the Po-Po cycle. Thus one Pre-Po reactor can be used to feed as many as six Po-Po reactors.

Process Step B4. Post-Polymerization After the “seed” polymer and remaining liquid VCM is pumped from the Pre-Po to the Po-Po, more VCM and initiator are added to the Po-Po for completion of the reaction. Small amounts of additional additives may be charged to the reactor for heat stability and particle size control (Dubec, 1980). The number of PVC particles in the Po-Po is determined by the amount of seed resin charged from the

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### 8 Pre-Po. The “seed” resin absorbs the VCM and at about 20 percent conversion the batch becomes solid and powdery, thus the agitator in the Po-Po must be of rugged construction. When the conversion to PVC has reached 70 percent to 90 percent, the jacket is heated with steam and a vacuum is pulled on the reactor to remove RVCM from the PVC resin particles. This represents the bulk stripping procedure that takes place in the Po-Po reactor. Exhaust gases from this stripping procedure are vented to recovery and the primary control so that VCM emissions do not exceed 10 ppm. VCM recovered from the reactors is sent ba ck to the charge tank for reuse. The VCM NESHAP requires bulk resins be stripped to 400 ppm RVCM as determined on a dry solids basis.

In producing PVC resins by the bulk process, temperature is the major control variable for determining the molecular weight of the polymer. One disadvantage of the bulk process is that there is not a good medium for heat transfer from the polymer reaction to the reactor wall. Reflux condensers are used to help control the reactor vessel temperature. The condensers remove gas from the reactor headspace, condense the gas, and then return the liquid VCM to the reactor. Heat from the gas is removed by cooling water in the reflux condensers.

The Po-Po is opened monthly for cleaning.

Process Step B6: Blending VCM conce ntrations that are emitted when the Po-Po reactor is opened may be determined by actual measurement or by calculation as approved by the Administrator. Polymer removed from the Po-Po reactor (already dry) is pneumatically conveyed to screens that remove oversize particles. Batches may be blended to improve product uniformity.

Bulk resins range in size from 0.1 to 1.0 micr ometers and exhibit excellent qualities for dry-blending compounds. The beads are of uniform size and porosity which allows uniform adsorption of plasticizer. Also, because suspending agents and surfactants are not used, the finished resin has a higher purity and therefore better heat stability than suspension or dispersion resins (Nass, 1977, p. 75).

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### 9 Table 1: Point Source Emissions Typical Of Su spension And Dispersion PVC Plants

Process Step Potential Emission Points VCM NESHAP Requirements
SD1 VCM Unloading and Storage Loading lines, VCM Storage Tank Emissions from loading lines must be reduced so that upon opening of line to the atmosphere emissions do not exceed
0.0038m 3 of VCM at Standard Temperature and Pressure (STP)

VCM removed from lines to meet this
criteria must be controlled to < 10 ppm upon exhaust to the atmosphere. Concentration of exhaust gases discharged to the atmosphere from storage tanks must not exceed 10 ppm.
SD2 Mixing, weighing and holding tanks before stripping operation Mixing, weighing and holding tank

vents Concentration of VCM exhaust gases discharged to the atmosphere must not exceed 10 ppm

SD3 Polymerization Polymerization reactor opening loss (ROL)

Polymerization reactor relief valve discharges

Polymerization reactor rupture disc discharge ROL from each reactor is not to exceed 0.02 g VCM/kg PVC product

No discharge to the atmosphere except for an emergency relief discharge

Concentration of the VCM exhaust gases discharged to the atmosphere must not exceed 10 ppm. Not required to be reported.
SD4 Stripping Stripping vessel vent Co ncentration of VCM exhaust gases discarded to the atmosphere must not exceed 10 ppm.
SD5 Monomer recovery system Recovery system exhaust vent knock-out pot Concentration of VCM exhaust gases discharged to the atmosphere must not exceed 10 ppm.
SD6 Blending (mixing, weighing and holding tanks after stripping operation) Slurry blend tanks and holding
tank vents Not regulated under the VCM NESHAP if the PVC Unit is using stripping to control VCM emissions.

SD7 Drying, sizing, screening of
dewatered resin Centrifuge vents, dryer vent stacks, storage silos, baghouse vents, screening operation vents Not regulated under the VCM NESHAP if the PVC Unit is using stripping to control VCM emissions.
SD8 PVC loading and storage Storage silos Not regulated under the VCM NESHAP if the PVC Unit is using stripping to control VCM emissions.
SD9 “In process” wastewater stripper Wastewater storage tank and wastewater stripper column VCM removed from “In process“ water is ducted to a control system from which the concentration of VCM in exhaust gas does not exceed 10 ppm.
SD10 Control Device System Incinerator, carbon adsorber, and/or scrubber VCM emissions must be reduced to 10

ppm.

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### 10 Table 2: Point Source Emissions Typical of Bulk PVC Plants

Process Step Potential Emission Points VCM NESHAP Requirements
B1 VCM Unloading and storage Loading lines, VCM storage tank Emissions from loading lines must be reduced so that upon opening of line to the atmosphere emissions do not
exceed 0.0038 m 3 of VCM at STP.
B2 Mixing, weighing and holding tanks before stripping operation Mixing, weighing and holding tank

vents Concentration of VCM exhaust gases discharged to the atmosphere must not exceed 10 ppm.
B3 Pre-polymerization Polymerization reactor opening loss (ROL)

Polymer reactor relief valve discharges

Polymerization reactor rupture disc discharges ROL from each reactor is not to exceed 0.02 g VCM/kg PVC products.

No discharge to the atmosphere except for an emergency relief discharge

Concentration of VCM exhaust gases discharged to atmosphere must not exceed 10 ppm. Not required to be reported.
B4 Post-polymerization (stripping in reactor) Polymerization reactor opening loss (ROL)

Polymerization reactor relief valve discharges

Polymerization reactor rupture disc discharges ROL from each reactor is not to exceed 0.02 g VCM/kg PVC products.

No discharge to the atmosphere except for an emergency relief discharge.

Concentration of VCM exhaust gases discharged to atmosphere must not exceed 10 ppm. Not required to be reported.
B5 Monomer recovery system Recovery system exhaust vent knock-out pot Concentration of VCM exhaust gases discharged to atmosphere must not exceed 10 ppm.
B6 Blending (mixing, weighing and holding tanks after stripping operation) Dry resin blend tanks and screening operation baghouse

vents Not regulated under the VCM NESHAP if the PVC Unit is using stripping to control VCM emissions.

B7 “In-process” wastewater stripper Wastewater storage tank Wastewater stripper column VCM removed from in process water is to be ducted to a control system from which concentration of VCM in exhaust gas does not exceed 10 ppm.
B8 PVC loading and storage Storage silos Not regulated under the VCM NESHAP if the PVC Unit is using stripping to control VCM emissions.
B9 Control Device system Incinerator, carbon adsorber, and/or scrubber VCM emissions must be reduced to 10 ppm.Vinyl Institute, Inc.

(Lb/hr) (T/Y) (Lb / mmLb PVC)

SD7 Dryer Scrubber, Centrifuge Vent, fugitive emissions from

additive 0.007 - 1.30 0.03 - 33.28 0.06 - 39.38 1, 2, 3, 4: LDAR monitoring

SD2, SD6, SD7,
SD9 Additive Make-up tanks, Blend Tank Vents, Centrifuge and Dryer Stacks, WW Treatment

Plant 0.057 - 1.38 0.092 - 35.42 0.50 - 39.38 2, 3

SD1-10 Incinerator; Dryer & Centrifuge

Vents and Wastewater Treatment Plant; VCM Railcar

Disconnect & Area fugitive emissions, ROL, EOL; Blend Tanks Vent emissions; PVC

Silo Storage emissions;

Wastewater Emissions 7.49E-09 -

0.53 1.48E-07 - 2.32 1.48E-07 - 3.40 1, 2, 3, 4: lab data / modeling

SD7, 9, 10 Dryer & Centrifuge Vents; Wastewater Treatment Plant;

Cooling Tower; Fugitives;

Incinerator < Limit of

Detection -

0.13 < Limit of

Detection -

0.57 < Limit of Detection -

1.08 1, 2, 4: lab data

SD1-10 Incinerator; Dryer & Centrifuge

Vent and Wastewater Treatment Plant; VCM Railcar

Disconnect & Area fugitive emissions, ROL, EOL; Blend Tanks Vent emissions; PVC

Silo Storage emissions;

Wastewater Emissions 3.00E-09 -

0.16 1.31E-08 - 0.71 5.90E-08 - 1.30 1, 2, 3, 4: lab data / modeling

SD1 - 10 Incinerator; Dryer & Centrifuge

Vent and Wastewater Treatment Plant; VCM Railcar

Disconnect & Area fugitive emissions, ROL, EOL; Blend Tanks Vent emissions; PVC

Silo Storage emissions;

Wastewater Emissions 7.49E-09 -

2.22 1.48E-07 - 9.52 1.48E-07 - 12.53 1, 2, 3, 4: lab data / modeling

SD1-10 Incinerator; Dryer & Centrifuge

Vents and Wastewater Treatment Plant; VCM Railcar

Disconnect & Area fugitive emissions, ROL, EOL; Blend Tanks Vent emissions; PVC

Silo Storage emissions;

Wastewater Emissions 1.19E-09 -

0.26 2.36E-08 - 1.15 2.36E-08 - 7.9 3 Compound Emission Ranges Across All Facilities

Basis for Estimate Key: 1 = Stack Test; 2 = Material Balance based on liquid/solid samples; 3 = Estimate from usage rate; 4 = other Incinerators = As used here the term includes all exhaust gas control devices, primarily thermal oxidizers

Ethyl Chloride (Chloroethane)

Chloroform

Ethylene Dichloride (1,2 Dichloroethane) Additive decomposition product; impurity, initiator delivery

Suspending agent diluent; impurity

VCM Impurity

Methyl Chloride (Chloromethane)

1-3 Butadiene VCM Impurity Basis

for Estimate Estimated Emission Rate Ranges

Methanol

VCM Impurity Process Step Emission Source Description of
Possible HAP Source

VCM Impurity VCM Impurity

June 26, 2008 Page 1 of 3Vinyl Institute, Inc.

(Lb/hr) (T/Y) (Lb / mmLb PVC) Compound Emission Ranges Across All Facilities

Basis for Estimate Key: 1 = Stack Test; 2 = Material Balance based on liquid/solid samples; 3 = Estimate from usage rate; 4 = other Incinerators = As used here the term includes all exhaust gas control devices, primarily thermal oxidizers

Basis

for Estimate Estimated Emission Rate Ranges Process

Step Emission Source Description of
Possible HAP Source

SD1-10 Incinerator; Dryer & Centrifuge

Vent and Wastewater Treatment Plant; VCM Railcar

Disconnect & Area fugitive emissions, ROL, EOL; Blend Tanks Vent emissions; PVC

Silo Storage emissions;

Wastewater Emissions 1.50E-10 -

0.18 6.56E-10 - 0.80 2.95E-09 - 5.50 1, 3

SD6, 7, 9 Centrifuges; Blend Tanks; Dryers; Cooling Tower; Waste Water Stripper; Dryer Stacks & Centrifuge Vents 0.01 - 2.75 0.02 - 3.48 0.09 - 7.10 1, 2

SD1-10 Incinerator; Dryer & Centrifuge

Vent and Wastewater Treatment Plant; VCM Railcar

Disconnect & Area fugitive emissions, ROL, EOL; Blend Tanks Vent emissions; PVC

Silo Storage emissions;

Wastewater Emissions 5.99E-09 -

1.36E-06 2.62 E-08 -

1.34E-06 1.18E-07 - 1.09E-05 1, 3

SD7, 9 Waste Water treatment, Dryer and Centrifuge Vent, Fugitives 0.00 - 0.61 0.00 - 2.67 0.00 - 1.55 1, 2

SD9, 10, Utilities

Area Control Device Vent; Cooling Tower; Waste Water Treatment Plant; Fugitives 7.00E-04 -

0.59 0.00 - 2.30 5.50 - 15.90 1, 3, 4: lab data

B9, SD9-10 Control Device Vent; incineration (located in VCM

plant); Scrubber; Caustic scrubber; Incinerator Stack;
Thermal Oxidizer 0 - 0.12 0 - 3.7 0 - 5.12 1, 2, 3

SD7, 10 Incinerator 0.00 0.00 0.00 1

SD7, 9, 10 Dryer and Centrifuge Vents; Waste Water Treatment Plant; Dryer Stacks; Fugitives 0 - 0.46 0 - 11.68 0 - 25.98 1, 2, 4

SD1, 2 Fugitives, 3 Dryers, Catalyst make-up tanks 0 - 0.17 0 - 0.75 0 - 3.37 3

SD7, 9 Waste Water treatment; Dryer and Centrifuge Vent 0 - 0.2 0 - 5.04 0 - 5.88 2, 4

SD7, 9, 10 Incinerator; Dryer & Centrifuge

Vent and Wastewater Treatment Plant; Fugitives No Data No Data No Data No Data VCM Impurity Initiator Impurity

Initiator decomposition product Additive decomposition product

VCM combustion decomposition product

Initiator decomposition product VCM Impurity Formaldehyde

Hydrochloric Acid

Chloroprene

Acetophenone

Vinyl Bromide Cumene VCM Impurity

Chlorine Acetaldehyde

Vinylidene Chloride VCM Impurity

Additive decomposition product

VCM Combustion, Disinfectant for cooling tower and treatment plant effluent

June 26, 2008 Page 2 of 3Vinyl Institute, Inc.

(Lb/hr) (T/Y) (Lb / mmLb PVC) Compound Emission Ranges Across All Facilities

Basis for Estimate Key: 1 = Stack Test; 2 = Material Balance based on liquid/solid samples; 3 = Estimate from usage rate; 4 = other Incinerators = As used here the term includes all exhaust gas control devices, primarily thermal oxidizers

Basis

for Estimate Estimated Emission Rate Ranges Process

Step Emission Source Description of
Possible HAP Source

SD5, 7, 9 Recovery System, Waste water treatment plant; Dryer and Centrifuge Vent 0.00 - 0.063 0.00 - 0.278 No data / Insignificant 3

SD7, 9 Dryer and Centrifuge Vent;

Waste Water Treatment Plant 0 - 0.01 0 - 0.02 0 - 0.09 2, 4

SD7, 9, 10 7 Dryer Stacks & Centrifuge Vents; Vent Gas Absorber 0.00 - 0.62 0.00 - 2.72 0.00 - 12.24 ND

SD5, 7 Dryer and Centrifuge Vent; Added by small timed pump < Limit of

Detection -

0.03 < Limit of

Detection -

0.13 < Limit of Detection -

0.90 2, 3

No Data No Data No Data No Data No Data No Data

SD2, 7, 9 Storage, Drying 0 - 15.70 0 - 13.50 0 - 344 2 Copolymer 2,2,4 Trimethylpentane

Coolant in vent gas absorber

& seal fluid in double

mechanical seals Initiator decomposition product; Vent gas absorbing
fluid

Vinyl Acetate Methyl Ethyl Ketone

Phenol Corrosion/Water Chemistry

Additive

Ethylene Glycol VCM Recovery; Initiator decomposition product Hydroquinone

Initiator decomposition product

June 26, 2008 Page 3 of 3