Air-Pollution-ControlFALL2015.ppt

1、AIR POLLUTION CONTROL,Learning outcomes,Understand pollution prevention methods for air pollution Understand and define the sources of air pollutants Be familiar with commonly used methods of air pollution control technologies for PM Gases (SO, NO, CO, and CO2),Pollution Prevention,Process Change Wi

2、nd, Geothermal, Hydroelectric, or Solar Unit instead of Fossil fired Unit. Change in Fuel e.g. Use of Low Sulfur Fuel, instead of High Sulfur fuel. Good Operating Practices Good Housekeeping Maintenance Plant Shutdown,COMMONLY USED METHODS FOR AIR POLLUTION CONTROL,PARTICULATE Cyclones Electrostatic

3、 Precipitators Fabric Filter Wet Scrubbers GASES Adsorption Towers Thermal Incernation Catalytic Combustion,PARTICULATE MATTER CONTROL Range: 20 to 40000 mg/m*3 First step: Process control Second step: Use of collection device,INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS,Iron & Steel Mills, the blast

4、 furnaces, steel making furnaces. Petroleum Refineries, the catalyst regenerators, air-blown asphalt stills, and sludge burners. Cement industry Asphalt batching plants Production of sulfuric acid Production of phosphoric acid Soap and Synthetic detergent manufacturing Glass & glass fiber industry I

5、nstant coffee plants,EFFECTSOFPARTICULATE EMISSIONS,Primary Effects Reduction of visibility size distribution and refractive index of the particles direct absorption of light by particles direct light scattering by particles 150 micro g / m3 concentration average visibility of 5 miles ( satisfactory

6、 for air and ground transportation ) Soiling of nuisance increase cost of building maintenance, cleaning of furnishings, and households threshold limit is 200 - 250 micro g / m3 ( dust ) levels of 400 - 500 micro g / m3 considered as nuisance,GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS,Five

7、 Basic Types of Dust Collectors : Gravity and Momentum collectors Settling chambers, louvers, baffle chambers Centrifugal Collectors Cyclones, Mechanical centrifugal collectors Fabric Filters Baghouses, Fabric collectors Electrostatic Precipitators Tubular, Plates, Wet, Dry,Tubular Dust Collector Ar

8、rangement for an ESP,VAPOR and GAS CONTROL First step: Fuel change Second step: Control Chemical Methods,GENERAL METHODS FOR CONTROL OF Gas and Vapor EMISSIONS,Change to Low Sulfur Fuel Natural Gas Low Sulfur Oil Low Sulfur Coal Use Desulfurized and Denitrogenized Fuel Build Tall Stacks Redistributi

9、on of Stack Gas Velocity Profile Modification of process,COMBUSTION (Incineration),Controlled Combustion The operating conditions can be modified to achieve significant reductions in the rate of thermal NOx production Reduce peak temperatures of the flame zone. Reduce residence time in the flame zon

10、e. Reduce Oxygen concentration in the flame one. This can be accomplished by: decreasing the excess air controlled mixing of fuel and air using a fuel rich primary flame zone,STAGED COMBUSTION,STAGED COMBUSTION,PRINCIPLE Initially, less air is supplied to bring about incomplete combustion Nitrogen i

11、s not oxidized. Carbon particles and CO are released. In the second stage, more air is supplied to complete the combustion of carbon and carbon monoxide. 30% to 50% reductions in NOx emissions are achieved.,FORMATION OF CARBON MONOXIDE,Due to insufficient oxygen Factors affecting Carbon monoxide formation: Fuel-air ratio Degree of mixing Temperature,GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS,Reducing energy consumption, increasing the efficiency of energy conversion Switching to less carbon intensive fuels Increa