Oxyfuel Boiler and Control Method for Oxyfuel Boiler

Abstract

An oxyfuel boiler structured so as to mix oxygen separated from air with a part of exhaust gas branched from exhaust gas discharged from the boiler for generating vapor and supplying to a vapor demand facility by burning coal fuel, and supply the mixed gas to the boiler as an oxidizing gas for burning the coal, wherein an air separation unit for separating air and manufacturing oxygen from air, an oxygen supply system for leading the oxygen manufactured by the air separation unit to the oxyfuel boiler, a recirculation system for leading a part of exhaust gas branched from the exhaust gas discharged from the oxyfuel boiler to the oxyfuel boiler, and a recirculation fan for supplying the exhaust gas to the recirculation system are installed, respectively.

Description

CLAIM OF PRIORITY[0001]The present application claims priority from Japanese patent application serial No. 2009-165492, filed on Jul. 14, 2009, the content of which is hereby incorporated by reference into this application.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a coal thermal power plant aiming at capturing CO2 and more particularly to an oxyfuel boiler suitable for capturing the CO2 of the coal thermal power plant and a control method for the oxyfuel boiler.[0004]2. Description of Related Art[0005]As a global warming countermeasure, the action of discharge reduction of CO2 (carbon dioxide) that is one of the green house gases is taken all over the world. The thermal power plant is one of the facilities discharging a large quantity of CO2 and particularly, the coal thermal power plant including a coal boiler of burning coal containing a large quantity of carbon and generating a large quantity of CO2 in combustion exhaust gas ...

AI Technical Summary

Benefits of technology

[0022]Particularly, when the heat absorption efficiency of the coal boiler is reduced due to deterioration over time, the oxygen concentration supplied to compensate for the reduction of the heat absorption efficiency of the boiler is controlled so as to increase, so that the gas temperature of the furnace rises in accordance with it, thus the heat absorption rate of the furnace increases, and the thermal damage of the material advances more.

[0028]According to the present invention, when a coal boiler operated as an existing air-fuel boiler is operated as an oxyfuel boiler, the expense required for modification can be suppressed, and the damage to the oxyfuel boiler due to high-temperature gas is prevented, thus a highly reliable oxyfuel boiler capable of operating stably over a long period of time and a control method for the oxyfuel boiler can be realized.

Problems solved by technology

Furthermore, in some of the heat exchangers, if the heat absorption rate is excessively larger than that under the air-fuel combustion condition, the heat absorption rate exceeds the limit of the heat resistance of the material and it may result in damage to the material.

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