OXYGEN-BLOWN GASIFICATION COMBINED-CYCLE - CARBON-DIOXIDE RECOVERY, TRANSPORT, AND DISPOSAL

This project emphasizes CO2-capture technologies combined with integra ted gasification combined-cycle (IGCC) power systems, CO2 transportati on, and options for the long-term sequestration of CO2. The intent is to quantify the CO2 budget, or an ''equivalent CO2'' budget, associate d with each of the individual energy-cycle steps, in addition to proce ss design capital and operating casts. The base case is a 458-MW (gros s generation) IGCC system that uses an oxygen-blown Kellogg-Rust-Westi nghouse (KRW) agglomerating fluidized-bed gasifier, bituminous coal fe ed, and low-pressure glycol sulfur removal, followed by Claus/SCOT tre atment, to produce a saleable product. Mining, feed preparation, and c onversion result in a net electric power production for the entire ene rgy cycle of 411 MW, with a CO2 release rate of 0.801 kg/kWhe. For com parison, in two cases, the gasifier output was taken through water-gas shift and then to low-pressure glycol H2S recovery, followed by eithe r low-pressure glycol or membrane CO2 recovery and then by a combustio n turbine being fed a high-hydrogen-content fuel. Two additional cases employed chilled methanol for H2S recovery and a fuel cell as the top ping cycle, with no shift stages. From the IGCC plant, a 500-km pipeli ne takes the CO2 to geological sequestering. For the optimal CO2 recov ery case, the net electric power production was reduced by 37.6 MW fro m the base case, with a CO2 release rate of 0.277 kg/kWhe (when makeup power was considered). In a comparison of air-blown and oxygen-blown CO2-release base cases, the cost of electricity for the air-blown IGCC was 56.86 mills/kWh, while the cost for oxygen-blown IGCC was 58.29 m ills/kWh. For the optimal cases employing glycol CO2 recovery, there w as no clear advantage; the cost for air-blown IGCC was 95.48 mills/kWh , and the cost for the oxygen-blown IGCC was slightly lower, at 94.55 mills/kWh. (C) 1997 Elsevier Science Ltd.