Air pollution control devices

Flue and waste gases from power plants and other industrial operations where coal is used as a feedstock invariably contain constituents that are damaging the climate or environment—these will be constituents such as carbon dioxide (CO2), nitrogen oxides (NOx), sulfur oxides (SOx), dust, and particles and toxins such as dioxin and mercury. 

The processes that have been developed for gas cleaning (Mokhatab et al 2006 Speight, 2007, 2008) vary from a simple once-through wash operation to complex multistep systems with options for recycle of the gases (Mokhatab et al., 2006). In some cases, process complexities arise because of the need for recovery of the materials used to remove the contaminants or even recovery of the contaminants in the original, or altered, form. 

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FIG. 25-23 Fractional efficiency curves for conventional air-pollution-control devices. [Chem. Eng., 87(13), 83 (June 30, 1980).]... 

Disposal The final func tional element in the sohd-waste-management system is disposal. Disposal is the ultimate fate of all solid wastes, whether they are wastes collected and transported direc tly to a landfQl site, semisolid wastes (sludge) from industrial treatment plants and air-pollution-control devices, incinerator residue, compost, or other substances from various solid-waste processing plants that are of no further use. 

Provide a list of all air pollution control devices and identify point and fugitive emission air pollution sources. 

Many control districts have very tight controls over petroleum refineries. Suppose these refineries produce 100 million liters of products per day and required air pollution control devices to recover all of the 2% which was previously lost. What are the savings in dollars per year at an average product cost of 10 cents per liter How does this compare to the estimate that the refineries spent 400 million for control equipment over a 10-year period ... 

Direct-flame afterburners are the most commonly used air pollution control device in which combustible aerosols, vapors, gases, and odors are to be controlled. The components of the afterburner are shown in Fig. 29-15. 

List the major types of air pollution control devices used for particulate removal. Visit the Web and make a list of equipment suppliers for these hardware. 

Add-on Control Device an air pollution control device such as carbon absorber or incinerator that reduces the pollution in an exhaust gas. The control device usually does not affect the process being controlled and thus is "add-on" technology, as opposed to a scheme to control pollution though altering the basic... 

Air Pollution Control Device Meehanism or equipment that eleans emissions generated by a source (e.g., an incinerator, industrial smokestack or an automobile exhaust system) by removing pollutants that would otherwise be released to the atmosphere. 

Clearly the largest application for filtration is air pollution control. On a worldwide basis the annual sales revenues for all types of pollution control equipment is around 150 billion dollars, with air pollution control devices being a substantial part of tliese equipment sales. The following is a summary of Web sites recommended to be consulted for specific vendor information on air filtration devices. A brief description of each site is provided. Many of these sites will link the reader to other sites containing additional information on product information. 

The incineration process may be viewed as consisting of four parts (1) preparation of the feed materials for placement in the incinerator (pretreatment), (2) incineration or combustion of the material in a combustion chamber, (3) cleaning of the resultant air stream by air pollution control devices (APCDs) which are suitable for the application at hand, and (4) disposal of the residues from the application of the process (including ash, and air pollution control system residues). 

Residuals Produced Fluidized bed incineration produces no separate ash as such, but solids are carried over in the gas stream and will require removal. Residuals from the air pollution control devices may require additional treatment prior to disposal. 

Largest source wet air pollution control devices Typical wastewater volume 120gal/t of sinter... 

Wet scrubbers are air pollution control devices used to remove particulates and fumes from air by entraining the pollutants in a water spray. 

For effective volatilization using an enclosed mechanical aeration system, contaminated soil is mixed in a pug mill or rotary drum. The gasoline components are released from the soil matrix by the churning action of the air/soil contact. The induced airflow within the chamber captures the gasoline emissions and passes them through an air pollution control device (e.g., a water scrubber or vapor-phase carbon adsorption system) before they are discharged through a properly sized stack. 

U.S. EPA has shown that 90% of process water can be recycled to the front end of the system for slurry preparation, and the rest must be treated on site or transported to an off-site facility.80 During the aerobic process, some contaminated air may be formed and emitted from the reactor. Depending on the air characteristics, a compatible air pollution control device may be used, such as activated carbon. Slurry biodegradation has been shown to be successful in treating soils contaminated with soluble organics, PAHs, and petroleum waste. The process has been most effective with contaminant concentrations ranging from 2500 mg/kg to 250,000 mg/kg. 

Air pollution control devices, checklist of applicable, 26 678t... 

Exhaust gases leaving the kiln pass through highly efficient air pollution control devices such as baghouse filters or electrostatic precipitators. The high temperatures required to make cement destroy 99.99% or more of the organic hazardous wastes. The content of hydrocarbons... 

Under USEPA s BIF mle, manufacturers are required to closely monitor numerous conditions in the kiln and to observe limits on the following aspects of the process (a) the maximum feed rate of hazardous waste fuel (b) the maximum feed rate of metals from both raw materials and fuels (c) the maximum feed rate of chlorine from raw materials and fuels (d) the maximum feed rate of raw materials (e) the maximum temperature at the inlet to the air pollution control devices (f) the maximum concentration of carbon monoxide and total hydrocarbons in the flue gas (g) the maximum temperature in the combustion zone or minimum temperature at the kiln inlet and (h) any decrease of pressure at the baghouses or any decline in the strength of the electric field of electrostatic precipitators (both are types of air pollution control devices). 

Electrostatic precipitator (ESP) An air pollution control device that uses electrostatic charges to remove particles from flue gas. 

The lack of a correlation was also appreciated in a follow-up study in which the data presented in the Dutch report20 (particulate concentration, water content, carbon monoxide concentration, furnace temperature, etc.) were compared with the PCDD/F emissions using statistical regression techniques.21 The aim was to determine which operating and emission parameters were strongly related to PCDD/F emissions. The data set was divided into two groups on the basis of the type of air pollution control device installed ... 

Ross Grafton, Ohio 10/1/2000 Low-temperature DRE, high solids, air pollution control device detuned... 

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