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Coproduction of Power, Steam, and Oxygen in Coal or Low Quality Fuel Combustion Systems

IP.com Disclosure Number: IPCOM000019343D
Publication Date: 2003-Sep-11
Document File: 4 page(s) / 2M

Publishing Venue

The IP.com Prior Art Database

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 High-purity oxygen permeate and nitrogen-enriched non-permeate products are withdrawn from the modules.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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Coproduction of Power, Steam, and Oxygen in Coal or Low Quality Fuel Combustion Systems

         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 High-purity oxygen permeate and nitrogen-enriched non-permeate products are withdrawn from the modules.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.

         A coal gasification system and a fluid bed combustor integrated with a combined cycle gas and steam turbine power generation system are shown in Figure 1. Coal is gasified with limestone and compressed air to produce a low-BTU gas which is burned in a gas turbine combustor. Additional coal is combusted with air and limestone in a fluid bed combustor to generate steam, the hot pressurized top gas from the fluid bed combustor is sent to the gas turbine combustor with additional compressed air for further combustion, and the pressure energy of the resulting combustion product is recovered in the gas turbine. Steam is generated by indirect heat exchange with boiler feedwater in the fluid bed combustor and by indirect heat exchange with the gas turbine exhaust gas, and the combined steam is expanded through a steam turbine. The gas and steam turbines operate generators which produce electric power. Alternatively, a low-grade fuel such as heavy fuel oil, petroleum residua, petroleum coke, or shale oil can be used to replace or supplement coal.

         The oxygen permeate product from a mixed conductor membrane, and at least a portion of the nitrogen-enriched non-permeate gas from the membrane if desired, can be utilized in the combustion system described above as illustrated in Figure 2. The hot pressurized top gas is filtered to remove entrained solids and is cooled if necessary. The resulting gas is passed through the ion transport membrane, which is preferably a pressure-driven mixed conductor membrane, and oxygen permeates through the membrane and is recovered at pressures between subatmospheric and about 10 psig. The oxygen can be cooled and withdrawn using a vacuum...