Simultaneous removal of H{sub 2}S and NH{sub 3} in coal gasification processes. [Quarterly] report, September 2, 1993--December 31, 1993
Nitrogen (N{sub 2}) occurs in coal in the form of tightly bound organic ring compounds typically at levels of 1 to 2 wt % on a dry-ash-free basis. During, coal gasification, this fuelbound nitrogen is released principally as ammonia and nitrogen, with smaller levels of HCN. The formation of NH{sub 3} in a coal gasification processes is a function of the fuel gas composition and the gasifier operating conditions. During the use of coal gas to generate electricity in gas-fired turbines, fuel bound (N{sub 2}) is converted to nitrogen oxides (NO{sub x}), which are difficult to remove and are highly undesirable as atmospheric pollutants. Recent results indicate that while the efficiency of molten carbonate fuel cell (MCFC) anodes is not effected by exposure to NH{sub 3}, NO{sub x} is generated during combustion of the anode exhaust gas. Thus, NH{sub 3} must be removed from the coal gas before it is used in IGCC or MCFC applications. The product stream from a high temperature, oxygen-blown gasifier, such as Texaco, contains about 2000 ppmv of NH{sub 3}, where higher concentrations (about 5000 ppmv) occur when the gasification is conducted at lower temperatures, such as in the Lurgi or GE air-blown gasifier. A range of 1500 to 3000 ppmv is considered for this study. Removal of H{sub 2}S using zinc-based sorbents, particularly zinc titanate, to < 20 ppmv levels has been well established (Lew et al., 1989; Jothimurugesan and Harrison, 1990; Woods et al., 1990; Gupta and Gangwal, 1993,). Studies of NH{sub 3} decomposition indicated that Ni, Ir, Co, Mo, Mn and Ru have high catalytic activities (Krishnan et al., 1988). If desulfurization sorbents such as zinc titanate could be used along with above metals to decompose ammonia present in hot coal then the number of unit processes necessary to clean hot coal gas could be reduced by one.
- Research Organization:
- Hampton Univ., VA (United States). Dept. of Engineering
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG22-93MT93005
- OSTI ID:
- 10160683
- Report Number(s):
- DOE/MT/93005-1; ON: DE94013987; BR: AA1525150
- Resource Relation:
- Other Information: PBD: [1993]
- Country of Publication:
- United States
- Language:
- English
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Simultaneous removal of H{sub 2}S and NH{sub 3} in coal gasification processes. Final report