Emissions from processes control

The primary concern abont hazardons processes is that they be operated in a safe manner so that fires, deflagrations, detonations, and releases of flammable and toxic gases into the atmosphere or inside process bnildings are eliminated or minimized. Also of great concern from an environmental standpoint is the control and minimization of volatile organic componnd (VOC) emissions from process vents and fugitive sources. 

FGD is used to control S02 emissions from coal and oil combustion from electric utilities and industrial sources. Impingement scrubbers are one wet scrubber configuration used to bring exhaust gases into contact with a sorbent designed to remove the S02. On occasion, wet scrubbers have been applied to S02 emissions from processes in the primary non-ferrous metals industries (e.g., copper, lead, and aluminum), but sulfuric acid or elemental sulfur plants are more popular control devices for controlling the high S02 concentrations associated with these processes. 

The emission from a controlled-release formulation is generally limited by a diffusion process which is controlled by the concentration gradient across a barrier to free emission and the parameters of the barrier itself (3). The rate of release follows approximate zero order kinetics if the concentration gradient remains constant i.e., the rate is independent of the amount of material remaining in the formulation except near exhaustion. A large reservoir of pheromone is generally used to attain a zero order release. Most formulations, however, tend to follow first order kinetics, in which the rate of emission depends on the amount of pheromone remaining. With first order kinetics, In [CQ/C] = kt where CQ is the initial concentration of pheromone, C is the residual pheromone content at time t, and k is the rate of release. When C 1/2 CQ, the half-life, of the formulation is 0.693/k. Discussions of the theoretical basis for release rates appear elsewhere (4- 7)... 

Alternative Control Techniques Document - NO Emissions from Process Heaters (Revised) U. S. Environmental Protection Agency Bulletin EPA-453/R-93-034, September 1993. 

Table 53.1 lists the types of devices that can be used to control emissions from process dryers. The selection procedure is always dictated by experience, reviewing the advantages and disadvantages of each type of air pollution control equipment, and capability of the equipment to meet the technical requirements of the process and to achieve compliance with the regulations at the lowest overall cost. In some drying installations, the cost of the equipment needed to comply with regulations can exceed that of the dryer itself. 

ECVM (2004). "Identification, measurement and control of fugitive emissions from process equipment leaks". 

The atmospheric pollution by cadmium is a result both of natural and man-made activities, such as the combustion processes based on fossil fuels (in particular coal and oil) and the emission from processes in the pyro-metallurigical non-ferrous metal industries. The deposition, transport, and inhalation processes are controlled predominantly by the size of the atmospheric aerosols, so that the primary type of speciation of interest to atmospheric chemists is the metal size distribution. However, chemical speciation (in terms of the distribution of both the dissolved/ particulate species and the inorganic/organic complexes) is important in governing... 

The control of carbon dioxide emission from burning fossil fuels in power plants or other industries has been suggested as being possible with different methods, of which sequestration (i.e., collecting CO2 and injecting it to the depth of the seas) has been much talked about recently. Besides of the obvious cost and technical difficulties, this would only store, not dispose of, CO2 (although natural processes in the seas eventually can form carbonates, albeit only over very long periods of time). 

Selective catalvtic reduc tion (SCR) has been used to control NO emissions from utility boilers in Europe and Japan for over a decade. Applications of SCR to control process NO emissions in the chemical industiy are becoming increasingly common. A typical SCR system is shown in Fig. 25-22. 

Emissions from industrial processes are varied and often complex (4). These emissions can be controlled by applying the best available technology. The emissions may vary slightly from one facility to another, using apparently similar equipment and processes, but in spite of this slight variation, similar control technology is usually applied (5). For example, a... 

Iron and steel industries have been concerned with emissions from their furnaces and cupolas since the industry started. Pressures for control have forced the companies to such a low level of permissible emissions that some of the older operations have been closed rather than spend the money to comply. The companies controlling these operations have not gone out of business but rather have opened a new, controlled plant to replace each old plant. Table 6-3 illustrates the changes in the steelmaking processes that have occurred in the United States. 

The most widely used pulping process is the kraft process, as shown in Fig. 6-11, which results in recovery and regeneration of the chemicals. This occurs in the recovery furnace, which operates with both oxidizing and reducing zones. Emissions from such recovery furnaces include particulate matter, very odorous reduced sulfur compounds, and oxides of sulfur. If extensive and expensive control is not exercised over the kraft pulp process, the odors and aerosol emissions will affect a wide area. Odor complaints have been reported over 100 km away from these plants. A properly controlled and operated kraft plant will handle huge amounts of material and produce millions of kilograms of finished products per day, with little or no complaint regarding odor or particulate emissions. 

Arizona has traditionally been a large copper-producing state. SO, emissions from copper smelters near Phoenix and Tucson are shown in Fig. 10-10 (1). Phoenix is located 100 km from the nearest smelter, and Tucson is 60 km from the nearest smelter. The improvement in visibility in the 1967-1968 period was due to a decrease in SO, emissions when there was 9-month shutdown caused by a strike. Improvement in visibility in the mid-1970 was the result of better control technology and process changes. 

Regulatory control is governmental imposition of limits on emission from sources. In addition to quantitative limits on emissions from chimneys, vents, and stacks, regulations may limit the quantity or quality of fuel or raw material permitted to be used the design or size of the equipment or process in which it may be used the height of chimneys, vents, or stacks the location of sites from which emissions are or are not permitted or the times when emissions are or are not permitted. Regulations usually also specify acceptable methods of test or measurement. 

Control of stationary sources of air pollution requires the application of either the control concepts mentioned in Chapter 28 of the control devices mentioned in Chapter 29. In some cases, more than one system or device must be used to achieve satisfactory control. The three general methods of control are (1) process change to a less polluting process or to a lowered emission from the existing process through modification of the operation,... 

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