Oxygen combustion system and method for operating same

摘要

An oxygen combustion system includes a boiler to burn fuel using combustion gas composed of oxygen-rich gas and circulating flue gas, a dust remover disposed in a flue through which flue gas discharged from the boiler flows, a second flue leading the combustion gas to the boiler, the combustion gas being made by mixing the circulating flue gas extracted downstream of the dust remover with the oxygen-rich gas, a combustion gas heater exchanging heat between the flue gas flowing between the boiler and dust remover and the combustion gas flowing through the second flue, and a flue gas cooler disposed between the heater and the dust remover to cool the flue gas. A control unit controls at least one of a flow rate and cooling medium temperature of the flue gas cooler such that temperature of the flue gas introduced into the dust remover will be between 90° C. and 140° C.

主权项

1. An oxygen combustion system comprising:
a boiler adapted to burn fuel using combustion gas composed of a mixture of oxygen-rich gas and circulating flue gas containing 25% to 40% of water; a dust remover disposed in a flue through which flue gas discharged from the boiler flows; a combustion gas pipe adapted to lead the combustion gas to the boiler, the combustion gas being made by mixing the circulating flue gas extracted from the flue on a downstream side of the dust remover with the oxygen-rich gas; a combustion gas heater adapted to exchange heat between the flue gas flowing through the flue between the boiler and the dust remover and the combustion gas flowing through the combustion gas pipe; a flue gas cooler disposed in the flue between the combustion gas heater and the dust remover and adapted to cool the flue gas by exchanging heat between the flue gas running through the flue and a cooling medium; and control means adapted to control at least one of a flow rate and temperature of the cooling medium of the flue gas cooler such that temperature of the flue gas introduced into the dust remover will be between and including 90° C. and 140° C., wherein SO3 in the flue gas condenses on an inlet side of the dust remover, forming sulfuric acid mist, and is removed by the dust remover, sticking to soot particles in the flue gas, and temperature of the flue gas never falls below an acid dew-point temperature, and acid dew-point corrosion and clogging with soot particles of ducts are inhibited.