COAL GASIFICATION GASIFICATION ONLY REASONABLE WHEN PLANT IS INTEGRATED SOME PROCESSES ARE COMMERCIAL H 2 S REMOVAL BY THE CLAUS PROCESS H 2 S + O 2 = H 2 O + SO 2 H 2 S + SO 2 = S + H 2 O

Energy Content Summary…. TypeBtu/SCF Producer Gas Water Gas341 Low-Btu150 Intermediate-Btu SNG950 Methane1054

Probable Uses…. Low-Btu gas –Local electrical power generation –Cannot be used for home or commercial heating Intermediate-Btu gas –Electrical power generation –Feed stock for chemicals –Town gas High-Btu gas…. Same as natural gas

Selection of a Gasifier Type of bed Operating pressure Slagging, non-slagging Lurgi (fixed bed, high P, non-slagging) Koppers-Totzek (entrained bed, low P, slagging) Wellman-Galusha (fixed, low P, non-slagging) Winkler (fluidized, low P, non-slagging)

Figure 7-6. Pipeline gas from coal via Lurgi pressure gasification. COAL PREPARATION OXYGEN-BLOWN COAL GASIFIERS SCRUBBING AND COOLING CRUDE GAS SHIFT CONVERSION H 2 O+CO=H 2 +CO 2 RECTISOL GAS PURIFICATION METHANATION 3H 2 +CO=CH 4 +H 2 O COMPRESSION AND DEHYDRATION ELEMENTAL SULFUR * 128 LTPD CO 2 H 2 S+CO 2 GAS LIQUOR 25,303 8,920 Btu/lb FEED COAL GAS LIQUOR SEPARATION AND EFFLUENT WATER TREATMENT PIPELINE GAS Btu/Scf RECLAIMED WATER TO PLANT USE NAPHTHA COAL TAR COAL OIL PHENOLS AMMONIA TOTAL LIQUIDS 8940 BBLS/day 155 tons/day OILY GAS LIQUOR SULFUR PLANT TARRY GAS LIQUOR N2N2 OXYGEN PLANT AIR COAL FINES STEAM OXYGEN STEAM AND POWER PLANT ELECTRIC POWER TO PLANT USE

Figure The Texaco gasifier (also Shell, Eastman )

System for In-Situ Gasification of Coal From Wiser, 2000 Inject air and steam Produce low-Btu gas Chemical reactions

Financial Dilemma Synthetic natural gas cost ->$10.00/10 6 Btu Investment -75 x Btu/year plant, 30 year life -$8 billion Benchmark is cost of oil and gas energy sources -Need a floor on the price of energy over a long time frame