Author: Frediano V. Bracco

Publisher:

Published: 1978

Total Pages: 20

ISBN-13:

The review of data on NH3 and HCN concentrations in the low /medium-Btu off-gases from the Mond, Riley-Morgan, Lurgi, Koppers-Totzek, Hygas and Synthane coal gasifiers indicates that NH3 is present at concentrations of 385-11,000 ppmV and HCN at concentrations up to 300 ppmV. There is a tendency for NH3 concentration to increase as the heating value of the low /medium-Btu gas increases. The observed NH3 concentrations are consistently greater than calculated equilibrium values even when the lowest possible gasifier temperatures (at the outlet) are assumed. The fraction of coal-bound nitrogen converted to NH3 + HCN is 12 to 91 percent. A rough estimate of the amount of NH3 + HCN in raw low/medium-Btu gases can be obtained by subtracting the nitrogen in gasifier byproducts (ash, char and tar) from the amount of coal-bound nitrogen and assuming complete conversion of the difference to NH3 + HCN. The reported concentrations of NH3 and HCN in purified low/medium-Btu gases indicate that levels of 1 to 10 ppmV NH3 and 1 to 100 ppmV HCN can be reached in low temperature cleanup at the expense of sensible heat.