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Power Production in Coal Gasification Combined Cycle Systems with Integrated Oxygen Production

IP.com Disclosure Number: IPCOM000019342D
Publication Date: 2003-Sep-11
Document File: 4 page(s) / 580K

Publishing Venue

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Abstract

Oxygen can be recovered from air at high temperatures by passing hot compressed oxygen-containing gas, preferably air, at temperatures above 500oC over a selectively permeable solid ceramic membrane containing selected inorganic oxide compounds. These membranes, known in the art generically as ion transport membranes, utilize a voltage or pressure differential across the membrane which causes oxygen ions to migrate through the membrane. The ions recombine to form oxygen gas and electrons, and the electrons move through the membrane in a direction opposite to the oxygen flux. Membranes which operate under a pressure differential typically are defined as mixed conductor membranes. Membranes can be fabricated as tubes or flat plates which are arranged in modules for efficient contacting with hot compressed air. High-purity oxygen permeate and nitrogen-enriched non-permeate products are withdrawn from the modules. A comprehensive review of ion transport membranes is given by J. D. Wright and R. J. Copeland in Report No. TDA-GRI-90/0303 prepared for the Gas Research Institute, September 1990.

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Power Production in Coal Gasification Combined Cycle Systems

with Integrated Oxygen Production

Oxygen can be recovered from air at high temperatures by passing hot compressed oxygen-containing gas, preferably air, at temperatures above 500oC over a selectively permeable solid ceramic membrane containing selected inorganic oxide compounds. These membranes, known in the art generically as ion transport membranes, utilize a voltage or pressure differential across the membrane which causes oxygen ions to migrate through the membrane. The ions recombine to form oxygen gas and electrons, and the electrons move through the membrane in a direction opposite to the oxygen flux. Membranes which operate under a pressure differential typically are defined as mixed conductor membranes. Membranes can be fabricated as tubes or flat plates which are arranged in modules for efficient contacting with hot compressed air. High-purity oxygen permeate and nitrogen-enriched non-permeate products are withdrawn from the modules. A comprehensive review of ion transport membranes is given by J. D. Wright and R. J. Copeland in Report No. TDA-GRI-90/0303 prepared for the Gas Research Institute, September 1990.

Electric power is produced in a coal gasification combined cycle (CGCC) system as shown in Figure 1 in which the coal is gasified with oxygen and steam to produce combustible synthesis gas containing primarily hydrogen and carbon monoxide. The synthesis gas is cleaned and fired with pressurized air in a gas turbine combustor and the combustion products are expanded through a gas turbine which generates shaft power to provide the pressurized combustion air and operate an electric generator. Hot turbine exhaust is utilized to raise additional steam which is expanded through a steam turbine to generate additional electric power. Oxygen for the coal gasification step is provided by an air separation unit, typically a cryogenic air separation unit, and pressurized nitrogen product (PR-3 of Figure 1) is introduced into the gas turbine combustor to control nitrogen oxides and to recover the pressure energy in the nitrogen. Additional nitrogen is used for inerting and coal transfer in the gasification system.

The operation of a CGCC system in which the oxygen for coal gasification is provided by an ion transport membrane system is illustrated in Figure 2. Heat for operation of the membrane system is provided by combustion of a portion of the treated synthesis gas from the coal gasification system. If required,...