Characterization of hydrogen cyanide production in coal gasification. [Including sample preservation]

• Main Author: Nakles, D.V.
• Language: unknown
• Published: 2020
• Subjects: 01 COAL; LIGNITE; AND PEAT; CARBON; CHEMICAL REACTIONS; FUEL GAS; IMPURITIES; HYDROCYANIC ACID; CHEMICAL ANALYSIS; STABILITY; HYDROGEN; NITROGEN; AMMONIA; CHEMICAL COMPOSITION; CHEMICAL EFFLUENTS; CHEMICAL REACTION YIELD; COAL GASIFICATION; HYDROCARBONS; METHANE; ORGANIC NITROGEN COMPOUNDS; PH VALUE; PYRIDINE; QUENCHING; SAMPLE PREPARATION; SAMPLING; TEMPERATURE DEPENDENCE; THIOCYANATES; WASTE WATER; ALKANES; AZINES; CARBONIC ACID DERIVATIVES; CRYOGENIC FLUIDS; ELEMENTS; ENERGY SOURCES; FLUIDS; FUELS; GAS FUELS; GASES; GASIFICATION; HEAT TREATMENTS; HETEROCYCLIC COMPOUNDS; HYDRIDES; HYDROGEN COMPOUNDS; INORGANIC ACIDS; LIQUID WASTES; NITROGEN COMPOUNDS; NITROGEN HYDRIDES; NONMETALS; ORGANIC COMPOUNDS; ORGANIC SULFUR COMPOUNDS; Carbonic acid
• Online Access: http://www.osti.gov/servlets/purl/5955891; https://www.osti.gov/biblio/5955891; https://doi.org/10.2172/5955891

In the past, the characterization of hydrogen cyanide production has been accomplished by the examination of the raw product gas quench condensate. Based on these examinations, a normalized hydrogen cyanide production in the range of 3(10/sup -6/) to 4(10/sup -2/) pounds per ton of moisture-and-ash-free (MAF) coal has been determined. These production rates imply that the processing and treatment problems associated with hydrogen cyanide may be minimal in coal gasification. However, the previous quench condensate characterization efforts were inadequate due to: The lack of verified sampling methods; the lack of verified preservation and analytical techniques; and the inefficiency of the quench operation in removing cyanide from the raw product gas. Improved characterization techniques have focused on the characterization of both the liquid and gas phase quench effluents as well as the raw product gas prior to the quench operation. In particular, the quench condensates have been characterized using preservation and analytical techniques tailored to address the idiosyncrasies of the gasification wastewaters. These techniques were developed and verified on a variety of synthetic and pilot plant process samples. The quenched product gas was examined using a specially designed on-line sample train. The combined results of these efforts were used to determine the efficiency of cyanide removal in the various quench operations and provide an estimate of total hydrogen cyanide production. Based on these efforts, hydrogen cyanide production in coal gasification has been assessed to be in the range of 0.01 to 1.3 pounds per ton of MAF coal. These data are significantly higher than previous results and indicate that cyanide production may be significant and should not be considered negligible when considering various liquid and gas phase effluent treatment. (LTN)