Flue gas cleanup

New units can be ordered having dry, low NO burners that can reduce NO emissions below 25 ppm on gaseous fuels in many cases, without back-end flue-gas cleanup or front-end controls, such as steam or water injection which can reduce efficiency. Similar in concept to low NO burners used in boilers, dry low NO gas turbine burners aim to reduce peak combustion temperatures through staged combustion and/or improved fuel—air mixing. 

Gangwal, S. K., McMichael, W. J., Howe, G. B., Spivey, J. J., and Siiveston, P. L., Low-temperature carbon-based process for flue-gas cleanup. IChemE Symp. Series, No. 

C.D. Livengood, H.S. Huang, M.H. Mendelsohn and J.M. Wu, Development of Mercury Control Enhancements for Flue-Gas Cleanup Systems, Proc. EPRI/DOE International Conference of Managing Hazardous and Particulate Air Pollutants, Toronto, Ontario, Canada, (1995). 

R.J. Walker, C.J. Drummond and J.M. Ekmann, Evaluation of Advanced Separation Techniques for Application to Flue Gas Cleanup Processes for the Simultaneous Removal of Sulfur Dioxide and Nitrogen Oxides, Department of Energy Report, DE85102227 (May, 1985). 

The path to commercialization for flue gas cleanup processes is difficult of 189 processes under development, only 10 processes can claim 100 MW(e) or greater of total flue gas desulfurization capacity Q). In light of the magnitude of the problem, and the current costs of its solution, it is worthwhile to review the reasons for these successes and failures. Examination of the strengths and weaknesses of current process development practices may suggest a more efficient research path for the future. 

Appreciable interest has been generated in the use of activated carbons for flue gas cleanup, especially for the removal of SOx and NO the adsorption of mercury from flue gases was discussed earlier. From the environmental point of view, emissions from the combustion of fossil fuels in power plants and similar industrial processes are major contributors to a lowering of air quality. The flue ga.ses carry traces of SOi and NO, which can be oxidized and converted to their acid forms in the presence of atmospheric water vapor, and they may also combine with other volatile organics to form ozone and smog. Similarly, low level SOj and NOx emissions from automobiles, while insignificant for individual vehicles, become a large source of pollution when multiplied by the millions of vehicles that are on the roads. 

CASST with fuel gas cleanup CASST with flue gas cleanup Air-blown gasifier... 

When cleanup of the flue gas produced by the combustion of volatiles is required, the total hardware costs for a CASST/CC system are sli tly higher than for an ABG/CC. The necessity for flue gas cleanup depends on a numbtf of foctors ... 

The behaviour of ash in the CASST process at a relatively low carbon conversion in the gasifier, it will be necessary to use the energy content of unconverted carbon in the combustion process resulting in flue gas cleanup. At high carbon conversions in the gasifier the amount of ash transported to the combustion process will be negligible, and flue gas cleanup will not be required. 

Capture of the C02 produced by combustion of natural gas as the reformer fuel is not addressed in the above-described scenarios. The possible approaches to sequester C02 from the reformer furnace would be (i) oxycombustion or (ii) flue gas cleanup. For oxycombustion, natural gas would be burned in pure 02, producing a waste gas containing only C02 and H20. The water can be removed by compression and cooling to produce a pure C02 stream at pressure for sequestration. Removal of C02 from the flue gas would involve either scrubbing of the waste gas with aqueous or nonaqueous solvents or the use of another adsorption-based C02 removal process. 

Chars (coke) are also used at low temperatures (363-393 K). Kassebohm and Wolfering [141] developed a reactor system for the simultaneous removal of NO.v and SO2. It is a moving-bed reactor, the catalyst is char (Fig. 23) In the application of this reactor type for flue gas cleanup of a waste incinerator, the char removes both SO2 and HCl. Moreover, very low levels of mercury and polychlorinated hydrocarbons were found at the exit of the reactor. 

Flue gas from waste incinerators is composed of NO c, CO, HCl, HF, and SO2 Metals such as Cd, Hg, Zn, and Pb, and organic compounds such as dioxines and furanes are also observed. The flue gas cleanup system downstream a waste incinerator is comparable to that of a power plant. Again, a number of locations of SCR may be distinguished leading to flue gases with different compositions. These are sulfur, alkaline metals, HCl, HF, dioxines and furanes containing gases with no dust, flue gas without sulfur and dust, and clean flue gas. 

Rubel, AM. Stencel, J.M. Ahmed, S.N. Preprints Symposium on Flue Gas Cleanup Processes ACS, Division of Fuel Chem. Denver. CO. 1993 38(2), 726-733. 

The stoker system, however, did have several advantages (1) the coal does not have to be pulverized, (2) only a low level of particulate emissions occurs, simplifying flue gas cleanup, and (3) the stoker is easy to operate and can be built in sizes varying from small to large. 

Lizzio, A.A. DeBarr, J.A., and Kruse, C.W., Production of activated char from Illinois coal for flue gas cleanup. Energy Fuels, 11(2), 250-259 (1997). 

Gas/Solid Catalytic Haldor Tops0e WSA-SNOX Degussa Catalytic B W SNRB Parsons Flue Gas Cleanup... 

Parsons Flue Gas Cleanup Process. The Parsons Flue Gas Cleanup (FGC) process consists of three steps ... 

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