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<br />~.., <br />en <br />~ <br />w <br /> <br />additional costs incurred in obtaining a still higher quality. The treatment <br /> <br />proc~dures are: <br /> <br />stripping ammonia and carbon dioxide <br />solvent extraction <br /> <br />biological oxidation <br />adsorption <br /> <br />Stripping <br />Ammonia is derived from nitrogen in the coal. Except for the very few <br />gasifiers run so hot that ~onia is not formed, i~ is produced in large <br />quantities whether or not organic molecules are produced. Because of its very <br />high solubility, ammonia is removed from ~~e gas stream in the condensate. <br />The condensate is ci=culatec, if necessary, to scrub all the ammonia out of <br /> <br />the gas. <br />The wastewater is steam stripped and the ~onia either recoveree from <br /> <br />t~e stripper overhead gases, or incinerated. It is usual to keep ~'e stripper <br /> <br />between 20 and 40 trays {lOO to 300 ppm <br />0.9 lbs steam per gal wastewater (about <br /> <br />bottoms NH3) at a <br />$2.7/1000 gals for <br /> <br />steam :ate 0: about <br />6 <br />steam at $3/10 <br /> <br />8t~). Ammonia recovery is capital and/or ener~1 intensive depending on the <br />process selected, but can be economical at high ammonia ~'roughputs. A 2,000 <br />gpm 14,000 pp~ N was~ewater stream, which migh~ be obtai~ed from a Lurgi <br />commercial scale plant, can economically yield about 190 ten/day anhydrous <br />ammonia. ~~ 85 f~ high 12 ft diameter $300,000 (uninstalled) stripFe~ would <br />re~ove 99% of the ammonia producing a treated effluent containing 180 FFm NH3 <br />The total installed cost would be approximately 3.75 times the uninstalled cost. <br />~his ~onia concentration is 5ui~able for a downstream biological purification <br />step, and will not cause problems in the cooling tower circuit. Should a <br />concentration of 500 ppm ammonia prove acceptable, the stripper column can be <br />reduced in height and, therefore, in cost by about 8~. This is a saving in <br />installed cost of about S90,000 for which the charges amount to about 1. 4e/1000 <br />6 <br />gals. or O.le/10 Btu product output at an arnorti~ation rate of 15 percent per <br />year. <br /> <br />If ~e stripped ~~onia is incinerated, stripper anc steam costs are <br /> <br />essentially the total cost of ammonia separation. If ammonia is recovered, <br /> <br />acditional plant, steam and coolinq water are required. The USS Engineers <br /> <br />and Cc~sultants PHOSAM-W process, which prOduces anhydrous ammonia,appears to <br /> <br />38 <br />