Ammonia scrubbing process

Processes based on the absorption of SO2 in ammonia solutions have been commercialized in Japan, Russia, and Germany, while development work on advanced concepts has been conducted in France and the United States (Breed and HoUinden, 1974). As of 1993, there were four commercial ammonia scrubbing processes the Walther, ATS Technology , General Electric (GEESI), and the Nippon Kokan (NKK) processes. The ABS and the Com-inco processes, described in the next section, have seen no development since 1979 and 1985, respectively (Patterson, 1992 Meyer, 1992). 

Ammoniak-rest, m. ammonia residue (amidogen, NH2). -rohr, n. ammonia tube or pipe, -salpeter, m. ammonia saltpeter (ammonium nitrate), -salz, n. ammonium salt, -selfe,/. ammonia soap, -soda, /. ammonia soda, Solvay soda, -stickstoff, m. ammonia nitrogen. -verbindung, /, ammonia compound ammonium compound, -verfahren, n. ammonia process, -wasche, /. ammonia scrubbing ammonia recovery plant, -wascher,... 

The ammonia scrubbing of loaded anion exchange extractants, e.g., [R3NH]2[ZnCl4](org), proceeds similarly (see also Section 9.17.5.1.2), and thus in each case the mixed extractant system achieves the overall process,... 

Tail gas scmbbers are sometimes used on single absorption plants to meet S02 emission requirements, most frequently as an add-on to an existing plant, rather than on a new plant. Ammonia (qv) scrubbing is most popular, but to achieve good economics the ammonia value must be recovered as a usable product, typically ammonium sulfate for fertilizer use. A number of other tail gas scrubbing processes are available, including use of hydrogen peroxide, sodium hydroxide, lime and soda ash. Other tail gas processes include active carbon for wet oxidation of S02, molecular sieve adsorbents (see MoLECULARSIEVEs), and the absorption and subsequent release of S02 from a sodium bisulfite solution. 

Figure 17 Ammonia hydrogen sulfide circulation scrubbing process for the coke oven gas purification (right) and H2S absorber (left).

Koppers CAS [Cyanogen, Ammonia, Sulfur] A scrubbing process for removing hydrogen cyanide, ammonia, and hydrogen sulfide from coal gas using a polythionate solution. Described in 1945 but probably never commercialized. 

Ammonia scrubbing is one of many processes for removing sulfur dioxide from flue gases. The gases are bubbled through an aqueous solution of ammonium sulfite, and the SO2 reacts to form ammonium bisulfite ... 

Scrubbing processes use various removal media including limestone, lime, dolomite, magnesium carbonate, sodium carbonate, ammonia, molten carbonate, or activated carbon. 

Nippon Kokan has developed and tested an ammonia-base doublealkali scrubbing process for sinter plants (27). Both in this system and the Mitsubishi process, lime will precipitate the sulfur oxides as well as the fluoride that is probably present. 

Walther process Ammonia scrubbing Alkazid scrubbing... 

Processes that use aqueous ammonia to remove H2S and CO2 are still offered for coke-oven gas purification, and many such plants are in operation in the U.S. and Europe however, it appears that the trend for new operations is toward the use of other absorbents. Other absorption processes that may be applicable for COG purification include the Takahax, Stretford, Vacuum Carbonate, Potassium Carbonate, and Sulfiban (MEA) processes. These processes can be designed to avoid serious adverse effects of trace impurities in the gas, and generally provide somewhat higher H2S removal efficiency than ammonia scrubbing. The processes are described in detail in other chapters (see index). 

Figure 4-26. Krupp Wilputte H2S/NH3-circulation scrubbing process for desulfurization and ammonia removal. Krupp Wilputte Corp. (1988)...

Particulate emissions from zinc processing are collected in baghouses or ESPs. SO2 in high concentrations is passed directly to an acid plant for production of sulfuric acid by the contact process. Low-concentration SO2 streams are scrubbed with an aqueous ammonia solution. The resulting ammonium sulfate is processed to the crystalline form and marketed as fertilizer. 

Continuing further with the recovery aspects from coke oven gas reference may be drawn to the recovery of light oil (crude benzol). In a typical process used, the coke oven gas (from which benzol is to be recovered) after removal of tar, ammonia etc. is passed through the benzol scrubber where the benzol vapours are scrubbed by wash oil flowing countercurrent to the gas. Benzolised wash oil is then pumped to the recovery section where the crude benzol, absorbed in the wash oil is stripped off by steam. The steam vapour mixture, com-... 

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