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Oxy-Fuel Boiler Using an Ion Transport Burner Disclosure Number: IPCOM000021004D
Publication Date: 2003-Dec-16
Document File: 3 page(s) / 31K

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Oxy-Fuel Boiler Using an Ion Transport Burner

Oxy-fuel boilers, with pure oxygen supplied by a cryogenic air separation plant, have been proposed as a possible option for carbon sequestration schemes, since the combustion flue gas is CO2 rich. Figure 1 provides a schematic of such a system. Cool flue gas is recycled to the oxy-fuel burners to moderate the combustion temperature. Typically the combustion is operated with excess oxygen to ensure complete fuel combustion. The flue gas thus contains oxygen, SO2 (from sulfur in the fuel), and inerts (from air leaks) in addition to the combustion products (CO2 and water vapor). These impurities can make CO2 sequestration more costly. In addition, the cost of oxygen can be a detriment to the overall economics of oxy-fuel combustion.

A new technology, ion transport membranes, offers capabilities that can make oxy-fuel combustion more attractive for carbon sequestration. These dense, non-porous membranes, operating at high temperature, allow oxygen ions to migrate through the crystal lattice based upon an oxygen partial pressure differential. Air is on the feed side of the membrane and pure oxygen is the permeate. Capital cost savings of more than 30 percent have been reported over traditional cryogenic air separation plants.

Use of these membranes as a combustion device has also been reported whereby a fuel is fed to the permeate side of the membrane and it reacts with the permeating oxygen to form combustion products. In this fuel-rich mode, the feed air can be maintained at a pressure near atmospheric pressure and still maintain sufficient driving force for oxygen ion transport, since the oxygen partial pressure on the permeate side is negligible. In fact, the permeate side can be operated at pressures above the air feed pressure and still maintain this driving force.

Use of the ion transport memb...