Process Descriptions

The process is composed of a pretreatment process and a liquefaction process, using pyrolysis of melted dehydrochlorinated plastic, similar to other liquefaction processes. 

The evolving gas, composed of HCI and light hydrocarbon, is incinerated at 1000°C or higher and quenched by a water spray to make a 10% HCI solution as well as to control dioxins. The composition of melted dehydrochlorinated plastic is shown in Table 26.5. 

The total chlorine consists mainly of inorganic chlorides, which are formed by reaction of HCI gas from PVC and PVDC materials, and metallic materials in the finff dnring the dehydrochlorination. This has been reported already from IKV [2]. The degree of dehydrochlorination was almost 95% [3]. 

The melted dehydrochlorinated plastic is then sent to a vertical tank pyrolyzer, fitted with a scraper for removing carbonaceons material on the reactor wall. Energy for pyrolysis is fed from a jacket heater and a high-temperatnre gas heater in a circulating fnmace, and blown into the bottom of the reactor, holding the temperature at 420°C. 

The carbonaceous material and foreign materials for liqnefaction are intermittently extracted from the bottom of the reactor with a part of the reaction mixtnre and cooled as residne. The pyrolysis gas emerging is carried to a distillation colnmn and condensed as light, medium and heavy fractions. 

Process Description Different energetic materials provide propulsive or explosive functions in rocket motors, munitions, and similar devices. These materials are made of different chemicals and have different characteristics of solubility, sensitivity to ignition, bum rate, and energy content. The potential for reuse varies widely depending on the physical form, chemical content, and reactive characteristics of the materials. 

The energetic materials to be recovered may be present in obsolete devices or in contaminated soils, sludges, or manufacturing residues. Obsolete devices may be refurbished and reused for their original purpose, or may be disassembled so that the energetic materials can be removed. The removed energetic materials may be purified and reused, processed to recover useful chemicals, or burned for energy recovery. 

200 Chemical Weapons/Explosive Waste/Unexploded Ordnance 

Rocket motors are thin metal casings containing an energetic material held in place with a binder. The energetic material typically is a mixture of ammonium perchlorate oxidizer and aluminum metal fuel, held by a polymer binder. 

Most glycol dehydration processes are continuous. That is, gas and glycol flow continuously through a vessel (the contactor or absorber ) where they come in contact and the glycol absorbs the water. The glycol flows from the contactor to a reboiler (sometimes called reconcentrator or regenerator where the water is removed or stripped from the glycol and is then pumped back to the contactor to complete the cycle. 

The contactor works in the same manner as a condensate stabilizer tower described in Chapter 6. As the glycol falls from tray to tray it becomes richer and richer in water. As the gas rises it becomes leaner and leaner in water vapor. Glycol contactors will typically have between 6 and 12 trays, depending upon the water dew point required. To obtain a 7 Ib/MMscf specification, 6 to 8 trays are common. 

It is possible to inject glycol in a gas line and have it absorb the water vapor in co-current flow. Such a process is not as efficient as countercurrent flow, since the best that can occur is that the gas reaches near equilibrium with the rich glycol as opposed to reaching near equilibrium with 

The gas from the glycol/condensate separator can be used for fuel gas. In many small field gas packaged units this gas is routed directly to fire tubes in the reboiler, and provides the heat for reconcentrating the glycol. This se[ .irator is sometimes referred to as a gas/glycol separator or pump gas separator. 

ct glycol from the separator flows through a sock filter to remove. solids and a charcoal filter to absorb small amounts of hydrocarbons that may build up in the circulating glycol. Sock filters are normally designed for the removal of 5-micron solids. On units larger than 10 gpm 

This section of the report describes the process used at the Modesto Energy Project. 

Tires for the boilers are obtained from the adjacent tire pile and from the community. Altogether, about 4.5 million tires per year are burnedI The Modesto Energy Project is required to obtain about half of these tires from the existing tire pile, and is permitted to acquire about half of its fuel from the community (referred to as the flow ). For example, 2.6 of the 4.8 million tires burned in 1990 at the facility were from the flow. This arrangement exists to balance the need to reduce the size of the hazardous tire pile with the desire of the company to obtain the most economical source possible of tires. Oxford Energy currently (1991) pays about 0.25 per tire for tires from the tire pile, but receives money for each tire acquired from the flow. The size of the tire pile will be decreased until a tire reserve remains of about 4 million tires.1 

Modesto has created a subsidiary, Oxford Tire and Recycle, to collect and transport tires from tire dealers. The company sorts the tires to remove good used tires for resale for recapping or retreading. The remaining scrap tires (approximately 80 percent) are fed whole to the boilers.1 

Parts cleaning and stripping are integral process operations for industries that repair, maintain, or manufacture parts and equipment. Manufacturing groups generating metal wastes include metal furniture manufacturers, metal fabricators, machinery manufacturers, electric and electronic equipment manufacturers, instrument manufacturers, and many others. 

Mechanical action might involve such activities as abrasion, deformation, heat or flame cleaning, and electrocleaning, which involves direct current hydrogen scrubbing at the cathode. Metal-bearing wastes associated with these actions would be due to the metalbearing contamination removed in the process as well as any of the metal substrate removed. 

The recommended strategy for developing effective waste minimization options for parts cleaning operations relies on systematic exploration of the following sequence of steps  

This strategy is consistent with the multi-media approach and general emphasis of reducing the waste at the source. Each step is discussed in the following sections. 

In many instances, by controlling the factors that contribute to surface contamination of the parts, the need for cleaning can be reduced or eliminated altogether. Control of parts contamination starts with a study of contamination sources. Sources can be incoming soils applied by metal vendors or soils applied in house. 

2 Feed Optimization for Fluidized Catalytic Cracking 9.2.1 Process Description 

The schematic layout of the FCC feed surge drum (72SD1) considered in this work is illustrated in Fig. 9.1. Altogether, there are a total of 7 different feed streams  

Tag no. Description Flow range (metre cubic/h) Specific Density range (kilogram/litre)  

Thermoplastic sheet forming turns a flat composite laminate, which contains reinforcing fibres aligned in one or more directions, into a shaped structure with the characteristics a design needs. Sheet forming can be the final process for the component however, thermoplastics allow for sheet forming steps and additional processing. 

the process equipment heats the prelaminate, which is typically a flat panel, until the matrix is molten and flowable. Heat arrives by surface convection, surface irradiation or combined convection and irradiation. Second, pressure forces the molten prelaminate to move towards the tool. Pressure sources include tool surfaces and fluid pressure from compressible gas or incompressible liquid. During this motion, the pressure can drive the matrix to flow between and through the fibres as the prelaminate changes to the component shape. 

As the prelaminate moves and the matrix flows, the fibres can move under the influence of the matrix flow and the applied pressure. Fibres angles can shift and the process can draw continuous fibres into the new shape as the prelaminate conforms to the tool. Discontinuous fibres can slide relative to one another and accommodate stretching without drawing fibres into the tool from the prelaminate s edges. At high forming rates, the viscous drag induced by shear lag can put fibres into tension and break the fibres. 

Once the prelaminate reaches the tool surface and takes on its new shape, the pressure acts to consolidate the pUes to make a fully dense component. Finally, the pressure holds the composite against the tool until the component has enough strength to survive as it is removed from the tool. 

2 Successful sheet forming requires interactive design and development. 

The predominant separation mechanism in scrubbing is impact due to the inertia of a particle with density relatively higher than that of the liquid. In such a way, the relative velocity between the particle and the liquid droplet is an important factor and the process may depend on the acceleration of, both, the particle and the droplet in relation to the point of impact. The process may be controlled by varying the droplet velocity, in order for the particle to collapse with it. The efficiency of the scrubbers is normally expressed as the fraction of particles collected from a volume of gas, determined by the projected area of the receiving body To achieve this, a separation number Se (Maas, 1979), may be defined as 

Understanding of the technological process and identification of subprocesses are essential for proper ventilation design, especially when designing process ventilation but also in enclosure air technology. The purpose of process description is to identify possible emission sources, occupational areas, the effects of environmental parameters on production, needs for enclosure and ventilation equipment, etc. One purpose is to divide the process into parts such that their inputs and outputs (e.g., process, piping and duct connections, electricity, exposure) to environment can be defined. Parts here can he different departments, and inside them, subprocesses. See Fig. 3.4. 

possible specific secondary sources of energy should be studied at this stage. 

Tools for this task could include databases and further expert systems. 

The development of the Spherizone technology started in 1995 and was subsequently scaled up from pilot plant to commercial size in 2002, when the new multi-zone circulating reactor (MZCR) was installed at Basell s plant in Brindisi, Italy. 

The Spherizone process, using Basell s high yield/high selectivity catalysts, produces spherical polymer particles with an outstanding morphology control directly in the reactor. 

It is a modular technology and is typically composed of the following sections  

The catalyst is fed continuously to the multi-zone circulating reactor, which is the core of this new technology. This loop reactor consists of two distinct reaction zones, each operating under its own peculiar fluid-dynamic regime. 

In the top of the reactor the riser gas is then separated from the solids, which enter the so-called downcomer. This section operates as a moving packed bed, with the polymer flowing downwards. As it operates dose to an adiabatic regime, the reaction heat will increase the temperature of the solid bed as the polymer descends. Therefore, care is taken to recirculate enough polymer to prevent the formation of hot spots and generally excessively high temperatures along the bed, which may jeopardize the flowability of the polymer and the recirculation itself. 

The various components of a typical fluid bed spray granulation unit are depicted in Fig. 7.8. Fluidizing gas (usually air) at 2 or 3 psig (14 to 21 kPa) is heated externally to the fluid bed and passes to the base of the unit. Here a suitable distributor such as a perforated plate or tubes with nozzles passes the gas to the particle bed uniformly over its cross-section. Jets formed at 

Liquid feed is most often dispersed into the bed by a two-fluid spray nozzle which is flexible in operation and less prone to blockage, especially if heated air is used to atomize crystallizing liquors. Liquid feed may be directed onto the bed surface from the space above the upper bed surface or introduced directly beneath the surface of the bed material. The liquid spray is less likely to dry as a spray before contacting the bed particles in this latter arrangement. 

The flowsheet is based on a Stanford Research Institute report for the production of methanol (SRI 43C, March 2000). The flowrate of the fresh feed of synthesis gas is 11,450 kmol/h at a pressure of 51.2 bar and a temperature of 38°C. The composition is 67.4 mol% hydrogen, 23 mol% carbon monoxide, 6.9 mol% carbon dioxide, 2.2 mol% methane, and small amounts of nitrogen and water. Table 6.11 gives information on the 

Lets you select the phase n whitfi reaction ocans. 

The synthesis gas is compressed in a two-stage compressor with interstage cooling to 92.7 bar and combined with a recycle stream that is 30,660 kmol/h with a composition that is quite different from that of the synthesis gas. The inert components (nitrogen and methane) are allowed to build up to fairly high levels (24.3 mol% methane, 3.8 mol% nitrogen) so that the losses of reactants in the vent stream are kept small. The vent stream is only 893 kmol/h. 

The combined stream is preheated to 122°C in a FEHE. A heater (HX3) is installed after the FEHE so that inlet temperature of the coolant stream in REACT2 can be adjusted to satisfy the energy balance when the exit temperature of the coolant stream is specified in this countercurrent tubular reactor. This temperature is 150°C, and the heat load in HX3 is 9.34 x 106 kcal/h. The stream is further preheated to 265°C in the tube side of reactor REACT2 by the heat transfer from the reactions that are occurring in the hot shell side of this vessel. There is no catalyst on the cold tube side, so the feed stream does not react but its temperature is increased. The stream is then fed to reactor REACT 1, which contains 48,000 kg of catalyst. This reactor is cooled by generating steam. The coolant temperature is 265°C (51 bar steam). This vessel contains 3750 tubes, 0.0375 m in diameter, and 12.2 m in length. The overall heat transfer coefficient between the process gas and the steam is 244 kcal h-1 m-2 °C 1. The heat transfer rate is 42 x 106 kcal/h. 

The reactor effluent, consisting of a mixture of unreacted A with the products Pi and P2, is separated in the distillation column. The reactor effluent is fed to the column on the feed stage TV) (stages are numbered 1,N from top to bottom) at a flow rate F. The reactant A is the lightest component of the reactor-effluent mixture and separates at the top of the column, being subsequently completely 

Process systems with significant material recycling 

Under the above modeling assumptions, the dynamic model of the reactor-column-recycle system consists of the material balance for the total molar holdup of the reactor, condenser, and reboiler, and component-wise balances for the reactant A and product Pi in the reactor, condenser, reboiler, and column trays, having a total of 2N + 9 differential equations. Specifically, 

Note that the model in Equation (3.27) does not include the secondary column required to separate Pi and P2. This unit is not part of the material recycle loop and has no dynamic interaction with the reactor or the first column. Consequently, the control problem for this column can be formulated and addressed independently and will not be considered in the remainder of the present study. 

Solid PVC resin is combined with water in a stirred tank to make a slurry (a suspension of solid particles in a liquid) containing about 10 wt% PVC. The slurry is pumped to a continuous chlorine absorber, a vessel equipped with an impeller that keeps the contents agitated. A stream of chlorine vapor at 25°C also enters the absorber. The absorber operates at 25°C. 

The chlorine absorber is enclosed by a jacket through which a hot or cold fluid can be pumped to maintain the absorber contents at any desired temperature. A pressure relief pipe emerging from a point near the top of the absorber is equipped with a rupture disk, a thin metal membrane designed to break if the absorber pressure rises above a certain value. If this happens, gas flows from the absorber through the relief pipe to a surge tank, lowering the pressure in the absorber while containing the released gas. 

Step 2. The chlorine that will eventually be fed to the absorber is stored in a tank as a liquid under pressure at 22°C. Liquid is pumped from this tank through a chlorine flow control valve to a chlorine vaporizer, a tall tank about half of which is filled with chlorine liquid and the other half with chlorine vtipor. The liquid and vapor are in equilibrium at 5°C. Saturated steam at 2 bar absolute is fed through a steam flow control valve into a coil submerged in the liquid that is in the vaporizer, and the heat transferred through the coil wall vaporizes chlorine. Chlorine vapor flows from the top of the vaporizer. 

The pressure and liquid level in the chlorine vaporizer are controlled automatically. As vapor flows out the top. the pressure in the tank begins to decrease. A pressure sensor detects the drop and sends a signal to the steam flow control valve. The valve opens and feeds more steam to the coil, causing more liquid chlorine to evaporate and raising the pressure back to the desired value. As the liquid evaporates, the liquid level in the tank begins to drop. A liquid level sensor detects the drop and sends a signal to the liquid chlorine flow control valve. The valve opens, and more liquid enters the tank to replace the liquid that evaporated, raising the liquid level back to the set-point (desired) value. 

Step 3. The chlorine vapor leaving the vaporizer passes through an adiabatic expansion valve, then through a chlorine vapor heat exchanger. In the exchanger, the vapor comes in thermal contact with a hot flue gas from a furnace to be described in Step 15. The heat transferred from the flue gas is used to raise the temperature of the chlorine vapor to 25°C. The healed vapor is the chlorine feed to the absorber mentioned in Step 1. 

Such plants can operate very economically, but may no longer be built due to current legislation concerning nitrous gas emissions. 

The residual gas is heated up with the aid of compression heat to ca. 250 to 300°C to improve energy recovery and released into the atmosphere by way of expansion gas driven turbines (with or without precleaning). 

In monopressure plants there is no nitrous gas compressor. In plants operating at high pressures e.g. H/H-or M/H-plants, the absorption volume is much smaller at 10 bar the volume is only one tenth that necessary at 4.6 bar, so only one tower is necessary. 

At low pressures only weaker acids can be produced, due to too high Nox-values with little proce.ss water 

The most common use of chlorine in sewage treatment is for disinfection, which usually is the last treatment step in a secondary biological wastewater treatment plant. Where the treated secondary effluent is fed into a stream to be used for water supply or for recreational purposes, chlorination is effective in destroying the disease-producing pathogens found in treated wastewater. Other principal uses of chlorine are odor control and control of bulking in activated sludge. 

Chlorine may be fed into the wastewater automatically, with the dosage depending on the degree of treatment. The wastewater then flows into a tank, where it usually is held for about 30 min to allow the chlorine to react with the pathogens (Fig. 1). Chlorine often is used either as a gas, or a solid or liquid compound. Liquid chlorine, or hypochlorite, has been used mostly in small systems (fewer than 5000 persons), or in large systems, where safety concerns related to handling chlorine gas outweigh economic concerns. The use of chlorine has proven to be a very effective means of disinfection. 

Chlorine is also used in advanced wastewater treatment (AWT) for nitrogen removal, through a process known as breakpoint chlorination. For nitrogen removal, enough chlorine is added to the wastewater to convert all the ammonium nitrogen to nitrogen gas. To do this, about 10 mg/L of chlorine must be added per mg/L of ammonia nitrogen in the wastewater—about 40 or 50 times more chlorine than normally used in a wastewater plant for disinfection only. 

CHLORINE RESIDUAL, MG/L MODIFIED STARCH - IODIDE METHOD Fig. 2. MPN coliform vs. chlorine residual. 

Naturally occurring subsurface brines occur in porous sandstone or other porous rocks and are regarded as connate or buried seawater. Some brines form locally by solution of rock salt beds. The most important subsurface brines of the United States are those in Mississippian and Pennsylvanian beds and also in Michigan, Ohio, New York, and West Virginia. 

The chemistry of brine varies from source to source depending on the original source of the salts however, typical Manistee, Michigan brine, has the following composition  

The magnesium chloride content of this brine could theoretically yield about 195 kg (430 lb) of magnesium oxide equivalent for every 3785 L (1000 gal) of brine. However, freshwater may be added to the brine at the well head in order to prevent salting out in the well casings. 

The synthesis of methyl acetate from methanol and acetic acid is a slightly exothermic equilibrium-limited liquid-phase reaction  

The low equilibrium constant and the strongly nonideal system thermodynamics that gives rise to the binary azeotropes methyl acetate/methanol and methyl ace- 

A semibatch distillation column with a column diameter of 100 mm and a reactive packing height of 2m (MULTIPAK I ) in the bottom section and an additional meter of conventional packing (ROMBOPAK 6M ) in the top section was used. The flow sheet of the column is shown in Fig. 10.5. 

At first, the distillation still is charged with methanol - the low boiling reactant - and heated under total reflux until steady-state conditions are achieved. At this moment, acetic acid - the high boiling reactant - is fed above the reaction zone to the second distributor. After 30 min the reflux ratio is turned from infinity to two and the product withdraw at the top of the column begins. During the column operations, the liquid-phase concentration profiles along the column and the temperature profiles are measured. For the determination of the liquid-phase composition, two methods are applied simultaneously. On the one hand, samples 

Location Country Shaft area (m Year started Max zinc output (t/.yr) Max lead output (t/yr) 

The top of the furnace is sealed and gases are taken through a side off-take to the condenser chamber. The standard furnace has one condenser chamber whereas the larger Avonmouth furnace design incorporated two condenser chambers located at opposite sides of the furnace. 

Furnace feed consists primarily of sinter of the appropriate composition to give the required slag formulation, and coke preheated to around 700°C. Other feed materials such as briquettes made from zinc oxides, and metallic scrap can also be added to the furnace feed. Feed is charged to the furnace using weighed buckets, which are dumped into a double bell seal hopper arrangement located in the furnace roof. The bell seals are water-cooled steel construction and efficient sealing is very important. 

At the tuyere zone of the furnace, carbon combustion takes place predominantly forming CO and generating most of the heat required to operate the furnace. Temperatures up to 1600 C are generated in the blast zone or tuyere raceways. As gases rise through the shaft, zinc and lead oxides are reduced by CO, and carbon is consumed by the CO2 so generated to reform CO. These reactions are endothermic and temperatures decline towards the top of the shaft. 

Coke will usually add significant quantities of sihca (up to 50 per ceut of sinter feed amounts) and will alter these ratios for blast furnace slag, which is the ultimate target. 

Feed from the Toluene tower is preheated (1) by the MX tower distillate product and then enters the MX tower (2) at approximately the middle tray. The MX tower overhead is totally condensed using heated water firom the gas fired reboiler (3). Steam is produced in the condenser (4) and dehv-ered to a utility header. Flow of water into the shell side of the condenser is manipulated by a level controller. The condensed MX tower overhead material is collected in an accumulator (5). A level controller manipulates the reflux to the tower to maintain the accumulator level. The overhead product flow is set externally, either by an advanced controller or manually. At the bottom of the MX tower the flow is divided into two streams. One of the streams is circulated through the gas fired reboiler, where it is partially vaporized and then returned to the MX tower. The vaporization rate is set 

The following variables were selected as the dependent variables (process outputs)  

The independent variables (process inputs), with the first three being designated as manipulated variables, were then selected as  

Overhead MX tower product flow this variable indirectly manipulates the reflux flow to the MX tower through the accumulator level controller. 

U3 Temperature setpoint at the bottom of OX tower determines the steam flow to the reboiler. 

Start-up User Name/location Country t/d Product References 

1994 Nuon/Vattenfell Buggenum IGCC Plant Netherlands 2000 Power [2,6,7] 

2006 Sinopec Zhejiang Zhejiang, Hubei China 2000 Ammonia [4,7-11] 

2006 Sinopec Yueyang and Shell Yueyang, Hunan (Dongting) China 2000 Ammonia [4,6-8,10,11] 

The technique developed by Klett et al was followed a wrapping wire mandrel was used to facilitate the towpreg lay-up and the coated tow is wrapped around an aluminum mandrel by rotating end-over-end. A limitation of this procedure is that the fibers in one layer are misaligned with respect to another layer. 

The energy utilization factor (EUF) and the cogeneration efficiency are given by 

The distillated products of atmospheric distillation unit (ADU) are limited to the boiling fractions under 350 C such as gasoline and diesel because pietroleum fractions tend to thermally degrade in high tempieratures. To recover additional distillates and gas oils, the refinery uses vaaium distillation unit (VDU) following the ADU. The reduced operating pressure ofVDU allows recovery of heavy boiling fraction above 560 C from the atmospheric residue. 

There are two major types of VDU ojjerations in a modem refinery -feedstock preparation and lubricant production. Feedstock preparation is the most common ojjeration that recovers gas oU from the atmospheric residue as a feed to the downstream conversion units (e.g. FCC and hydrocracking units), which converts the gas oil into more valuable liquid products such as gasoline and diesel. Lubricant production is designed to extract petroleum fractions from the atmospheric residue to produce luboil with desirable viscosity and other related properties. 

This chapter presents the methodology to simulate the VDU for feedstock preparation, because it is the most popular operation however, most of the guidelines in our methodology are also applicable to lubricant production units. 

Refinery Engineering Integrated Process Modeling and Optimization, First Edition. 

The reaction for acetic acid (HAc) esterification with ethanol (EtOH) to produce ethyl acetate (EtAc) and water (H2O) can be expressed as 

This corresponds to an exothermic reaction with an equilibrium constant slighter greater than 1. In the process simulation, a catalyst density of 770kg/m is assumed to calculate the total volume occupied by the catalyst in a reactive tray. 

TABLE 16.5 Normal Boiling Point Ranking for Pure Components and Azeotropes 

To account for nonideal vapor-liquid equilibrium and possible VLLE for this quaternary system, the NRTL model is used to calculate the activity coefficients. Model parameters are taken from Chapter 7. Vapor-phase nonideality caused by the dimerization of acetic acid is also taken into consideration using the Hayden-O Connell second virial coefficient model. Aspen Plus built-in parameters values are used. 

FIGURE 3.1 Typical soaker visbreaking unit. (Adapted from Stratiev, D. and Nikolaev, N., Petrol. Coal, 51(2), 140, 2009.) 

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KLAMECKI,B.E.- HANCHI,J. Wear Process Description Based on Acoustic Emission. Journal of Tribology, Vol.l 12, July 1990, p.469-476. 

In the laboratory or process research section a laboratory procedure for a fine chemical is worked out. The resulting process description provides the necessary data for the determination of preliminary product specifications, the manufacture of semicommercial quantities in the pilot plant, the assessment of the ecological impact, an estimation of the manufacturing cost in an industrial-scale plant, and the vaHdation of the process and determination of raw material specifications. 

Resin grade Processing Description Main uses... 

AMMONIA Raw material Process description Feedstock conversion reaction V012... 

Process flow sheets and process descriptions given herein are estimates of the various commercial processes. There are also several potential commercial processes, including variations on the chlorohydrin process, variations on the hydroperoxide process, and direct oxidation of propylene. 

Process Description. Reactors used in the vapor-phase synthesis of thiophene and aLkylthiophenes are all multitubular, fixed-bed catalytic reactors operating at atmospheric pressure, or up to 10 kPa and with hot-air circulation on the shell, or salt bath heating, maintaining reaction temperatures in the range of 400—500°C. The feedstocks, in the appropriate molar ratio, are vaporized and passed through the catalyst bed. Condensation gives the cmde product mixture noncondensable vapors are vented to the incinerator. 

A model s abiUty to correctly predict pollutant dynamics and to apportion source contributions depends on the accuracy of the individual process descriptions and input data, and the fidehty with which the framework reflects the interactions of the processes. 

Asbestos and Mica Asbestos is no longer mined in the United States because of the severe health hazard, but it is still mined and processed in Canada. See previous editions of this handbook for process descriptions. 

Process Description lectrodialysls (ED) is a membrane separation process in which ionic species are separated from water, macrosolutes, and all uncharged solutes. Ions are induced to move by an electrical potential, and separation is facilitated by ion-exchange membranes. Membranes are highly selective, passing either anions or cations andveiy little else. The principle of ED is shown in Fig. 22-56. 

Process Description Reverse osmosis (RO) and nanofiltration (NF) processes utilize a membrane that selectively restricts flow of solutes while permitting flow of the solvent. The processes are closely related, and NF is sometimes called loose RO. They are kinetic processes, not equilibrium processes. The solvent is almost always water. 

Process Description Microfiltration (MF) separates particles from true solutions, be they liquid or gas phase. Alone among the membrane processes, microfiltration may be accomplished without the use of a membrane. The usual materi s retained by a microfiltra-tion membrane range in size from several [Lm down to 0.2 [Lm. At the low end of this spectrum, very large soluble macromolecules are retained by a microfilter. Bacteria and other microorganisms are a particularly important class of particles retained by MF membranes. Among membrane processes, dead-end filtration is uniquely common to MF, but cross-flow configurations are often used. 

Process Description Gas-separation membranes separate gases from other gases. Some gas filters, which remove hquids or sohds from gases, are microfiltration membranes. Gas membranes generally work because individual gases differ in their solubility and diffusivity through nonporous polymers. A few membranes operate by sieving, Knudsen flow, or chemical complexation. 

Process Descriptions Selectively permeable membranes have an increasingly wide range of uses and configurations as the need for... 

Process Description When organic wastes are added to the soil, they are subjected simnltaneonsly to the following processes (1) bacterial and chemical decomposition, (2) leachating of water-sohible components in the original wastes and from the decomposition products, and (3) volatilization of selected components in the original wastes and from the prodticds of decomposition. 

Process Description The installation of deep wells for the injection of wastes closely follows the practices used for the drilling and completion of oil and gas wells. 

FCC process description adapted by permission from Fluid Catalytic Cracking Handbook, R. Sadeghbeigi, Gulf Publishing Company, Houston, Texas, 2000, pp. 3—17. 

E S i c - ai it O Component/ assembly process description 9 e M a Failure Mode Description and FMEA Severity Rating (S) ... 

According to the process description, the following activities take place at yourfacility involving lead and lead compounds ... 

Once the candidate corrective measure alternatives have been identified, a more detailed evaluation of each alternative needs to be undertaken. From an engineering perspective, the first step in the evaluation process would include the development of a conceptual design for each alternative. The conceptual design would consist of a process description, a process flow diagram and a layout drawing. Preliminary sizing of equipment and utility and land requirements would be developed. In addition, chemical requirements and residuals produced can be estimated. From the conceptual design, permitability and residuals disposal issues can be identified and addressed. 

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