Air emissions controls

In the early 1970s, air pollution requirements led to the adoption of the double contact or double absorption process, which provides overall conversions of better than 99.7%. The double absorption process employs the principle of intermediate removal of the reaction product, ie, SO, to obtain favorable equiUbria and kinetics in later stages of the reaction. A few single absorption plants are stiU being built in some areas of the world, or where special circumstances exist, but most industriali2ed nations have emission standards that cannot be achieved without utili2ing double absorption or tad-gas scmbbers. A discussion of sulfuric acid plant air emissions, control measures, and emissions calculations can be found in Reference 98. 

A U.S. EPA study (41) showed that soil vapor extraction (SVE) is an effective treatment for removing volatile contaminants from the vadose zone. Sandy soils are more effectively treated than clay or soils with higher organic content because higher air flows are possible in sand and clays—organic soils tend to adsorb or retain more contaminants. Removal of volatiles is rapid in the initial phase of treatment and thereafter decreases rapidly thereafter-an important consideration in the design of air emissions control over the life of the project. 

Recent air pollution regulations limit the amount of volatile organic carbon (VOC) that can be discharged from wastewater treatment plants. Benzene is a particular case in which air emission controls are required if the concentration of benzene in the influent wastewater exceeds 10 mg/L. 

In addition, restrictions on industrial air emissions under the Clean Air Act (CAA) as amended in 1977, the Clean Air Act Amendments (CAAA) of 1990, and other state and local statutes and regulations have universal impact on the storage of toxic materials, with direct and significant effects on the design and operation of toxic material storage facilities. Whereas the primary factors which once determined how air emissions from storage tanks were handled were fire protection and loss prevention, in recent years environmental protection concerns nearly always determine the extent and nature of the air emission controls required to be installed. 

Ozog, H., and Erny, W. J. 1999. Safety Hazards Associated with Air-Emission Controls. Paper 5d. Proe. 33rd Annual AIChE Loss Prevention Symposium, March 14-17, 1999, Houston, TX. American Institute of Chemical Engineers, New York, NY. 

Direct acidihcation of cyanide waste streams was once a relatively common treatment. Cyanide is acidified in a sealed reactor that is vented to the atmosphere through an air emission control system. Cyanide is converted to gaseous hydrogen cyanide, treated, vented, and dispersed. 

In order to protect air resources, TSDFs are required to install unit controls to prevent organic emissions from escaping into the air. The air emission controls apply to process vents, equipment leaks, containers, surface impoundments, and tanks. 

Pollutants and sludges extracted from CAA air emission control devices are subject to RCRA hazardous waste regulations if hazardous... 

Vogel, G.A., Air emission control at hazardous waste management facilities, J. Air Pollut. Control... 

Wang, L.K. and Kurylko, L., Liquid Treatment System with Air Emission Control, US Patent No. 5399267, Office of Patents and Trademarks, Washington, DC, March 1995. 

Both air emission control and sludge disposal are extremely important in a steel acid pickling plant.18-20... 

For indoor air quality control, in addition to the air emission control technologies identified above, ventilation and air conditioning are frequently adopted by plant managers [36,85,86]. 

The capital cost includes covered tank, carhon feed system. O M costs cited are for groundwater treatment, air emissions control/treatment, sludge dewatering/disposal, and analytical. 

Also, there is serious question as to whether such a system would be capable of obtaining a RCRA Part B Permit to operate without formal air emission control systems. These open tank systems are designed to be crude but effective. When one begins to collect flammable and toxic gases over such open tanks and to allow access of fork lift trucks to deliver and retrieve hoppers of slag, the logic of the system falls apart very quickly and one returns to the reactor concept or other options. 

Some of the principal variations between these processes are different operating temperatures, different operating pressures and different concentrations of the nitric acid product. Other differences include catalysts and spent catalyst recovery systems. In the 1990 s, new air emission control requirements necessitated the modification of some plants and prompted the re-evaluation of processes for new plants. This resulted in a trend toward plants... 

The incineration of DPE suits (which are made of a mixture of polyvinyl chloride, chlorinated polyethylene, resins, plasticizers, and metal stabilizers) is subject to the same dioxin emission limits at industrial incineration facilities as they are at chemical agent disposal facilities. Thus the waste feed load and incineration bum conditions for any of these chlorinated materials into incineration units may be regulated to meet air emission control requirements. These emission control limits and resulting incineration performance requirements are spelled out in the RCRA and Clean Air Act Title 5 permits for each site. 

The pharmaceutical industry is characterized by the diversity in the process design. Therefore, it is impossible to provide a single process flow diagram. However, most of the processes involve common steps such as reaction vessel, separation units, purification, wastewater treatment, air emission control, and others. A simplified process flow diagram for drug synthesis is given in Fig. 10.4 [16]. 

T. Cesta and L.M. Wrona., Optimization of BOF air emission control systems. Iron Steel Eng. 72, 23-31, July (1995). 

RACT/BACT/LAER clearinghouse provides state and local pollution control agencies, EPA regional offices, and other interested parties with current information on air emissions control technology determinations. 

Deactivation of Stationary Source Air Emission Control Catalysts... 

The present review provides a summary of the literature dealing with the causes, effects, and correction strategies for deactivation of stationary source air emissions control catalysts. Other authors have dealt with catalyst deactivation in general or with automotive catalyst deactivationl". ... 

Deactivation Mechanisms- To provide a perspective on the nature of catalyst deactivation in air emissions control systems, consider first the general characteristics of the catalyst itself. The catalyst can be employed generally in the form of pellets or in a monolithic form often called a... 

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