Method for reducing oxygen content in a boiler exhaust gas
AssigneeMitsubishi Heavy Industries, Ltd.
InventorsMasaki Iijima, Tetsuya Imai
Life of this patent
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Abstract
A process is provided for producing a nitrogen gas, useful in the petroleum industry, by combusting fuel with air in a “once through”-type boiler and injecting a supplemental fuel, such as natural gas, into the exhaust gas at a location just before a combustion catalyst that promotes the reaction between this supplemental fuel and the residual oxygen present in the exhaust gas. This oxygen-diminished, exhaust gas is then passed through a heat exchanger, where it transfers its heat to the air entering the boiler.
Claims14
A method for reducing oxygen content in an exhaust gas from a boiler, comprising:
- supplying an oxygen reducing fuel to the exhaust gas at just before a combustion catalyst portion disposed downstream or at the intermediate portion of a convectional heat transfer portion of the boiler,
- burning said oxygen reducing fuel at said combustion catalyst portion to increase a CO2 content and reduce an oxygen gas content of an exhaust gas, thereby obtaining an exhaust gas which is comprised mainly of nitrogen gas and has an oxygen gas concentration not greater than 1,000 ppm, and
- transferring heat, using a heat exchange device that is free of air leakage, from the obtained exhaust gas to air supplied to an input of the boiler to thereby increase the efficiency of the removal of oxygen from the gas.
A method of reducing the oxygen content of an exhaust gas from a boiler, comprising the steps of:
- introducing an oxygen reducing fuel into the exhaust gas just before a combustion catalyst portion of the boiler, which portion is disposed downstream from or at the intermediate portion of a convectional heat transfer portion of the boiler;
- and
- burning the oxygen reducing fuel at the combustion catalyst portion to increase the concentration of CO2 and to reduce the concentration of oxygen in the exhaust gas sufficiently to thereby obtain an exhaust gas which is composed primarily of nitrogen gas and which has an oxygen gas concentration that is not greater than 1,000 ppm.
Dependencies are inferred from the claim text.