A method and system for removing SO 3 and SO 2 from a flue gas produced by the burning of a fossil fuel. Particulates are removed from the flue gas to produce partially cleaned flue gas. A sufficient amount of calcium-based, sodium based or magnesium-based dry sorbent, preferably having a particle size larger than 1.0-2.0 microns, is injected into the flue gas to react with and remove substantially all of the SO 3 from the partially cleaned flue gas to produce a substantially SO 3 -free flue gas containing reacted and unreacted dry sorbent. The substantially SO 3 -free flue gas is conveyed to wet scrubber means for removing SO 2 to produce cleaned flue gas. In a first embodiment, sufficient dry sorbent is provided to remove desired amounts of SO 3 and SO 2 . In a second embodiment, a make-up reagent provided to the wet scrubber means wets the dry sorbent, removes both the reacted and unreacted dry sorbent from the substantially SO 3 -free flue gas, and makes the unreacted dry sorbent available as a reagent for SO 2 removal, the make-up reagent and the unreacted dry sorbent reacting with and removing the SO 2 from the substantially SO 3 -free flue gas to produce cleaned flue gas.

Method and system for so2 and so3 control by dry sorbent/reagent injection and wet scrubbing

PURPOSE: A method for treating a gas is provided to efficiently and safely neutralize SO3 and mist of sulfuric acid contained in flue gas which are generated by combustion of sulfur contained fuels for facilities such as boilers. CONSTITUTION: The method for treating a gas containing SO3 comprises the step of adding a mixture of sodium bicarbonate powder having an average particle diameter of 20 microns or less and an anti-caking agent for sodium bicarbonate into a SO3 contained gas having a temperature of 60 deg.C or more in an amount of 0.1 to 5 wt.% based on the sodium bicarbonate powder so as to neutralize SO3 in the gas, wherein sodium bicarbonate is added into a gas in an amount of 0.5 to 5 equivalents based on SO3, the anti-caking agent is particulate having an average particle diameter of 0.005 to 0.1 microns, and the anti-caking agent is silica.

Method for treating gas

PURPOSE:To lower the concentration of sulfurous acid gas in flue gas finally discharged to the atmosphere to increase desulfurization efficiency by taking off part of flue gas from between a heat exchanger for preheating the furnace and a reactor and providing a bypass flue supplying the gas to a region on the downstream side of the central part of the reactor and on the upstream side of the termination position. CONSTITUTION:From a flue 14 between a heat exchanger 16 and a reactor 18, branches off a bypass flue 28 which is connected to the place on time downstream side of the central part of the reactor 18 and on the upstream side of the termination part. Flue gas which is introduced into the reactor 18 through the main flue 14 is cooled by water sprayed with a nozzle 20 to a temp. corresponding to the dew point and mixed with hot flue gas introduced through the bypass flue 28 on the way to the termination. Thereby the flue gas is desulfurize with efficiency corresponding to the temp. of the mixed gas, so that the overall desulfurization efficiency of the reactor 18 is increased.

Flue gas desulfurization equipment

The present invention controls an inlet temperature 14a to be a set temperature of an acid dew point or higher such that: a combustion gas bypass line 12 that allows combustion gas to bypass a preheater 4 is provided, and a combustion gas flow rate adjustment damper 13 is provided on the combustion gas bypass line 12; the inlet temperature 14a of a dedusting apparatus 6 is measured by a thermometer 14; the inlet temperature 14a measured by the thermometer 14 is then inputted to a control unit 15; and an opening degree adjustment signal 13a is outputted from the control unit 15 to the combustion gas flow rate adjustment damper 13 on the basis of a comparison result between the measured inlet temperature 14a and the set temperature of the acid dew point or higher preset at the control unit 15.

Method and apparatus for controlling inlet temperature of dedusting apparatus in oxygen combustion boiler equipment

An exhaust gas treatment facility according to one embodiment of the present invention is so configured that a bypass amount adjustment section is controlled in such a manner that the bypass amount can be reduced when the sulfur oxide concentration in a combined exhaust gas becomes higher than a specified concentration as measured by a sulfur oxide concentration measurement section, and then a desulfurization device is controlled in such a manner that the desulfurization performance of the desulfurization device can be improved when the temperature of the combined exhaust gas, which is measured by a combined exhaust gas temperature measurement section, becomes lower than a specified white smoke generation prevention temperature, and then the bypass amount adjustment section is controlled in such a manner that the bypass amount can increase.

Exhaust gas treatment facility and method for controlling same

PURPOSE: To prevent the accumulation of a solid in a dust collecting apparatus, in an exhaust gas desulfurizer equipped with a desulfurizing reactor and a dust collector, by providing a gas heater controlling the temp. of the gas flowing in the dust collector. CONSTITUTION: The temp. of the exhaust gas 2 from a boiler 1 is lowered by an air heater 3 to guide the exhaust gas 2 to a desulfurizing reactor 4. A desulfurizing agent 5 is sprayed to a flue 6 by a nozzle 11 and the exhaust gas is guided to the desulfurizing reactor 4. Water is sprayed into the desulfurizing reactor 4 from a nozzle 12 to lower the temp. of the exhaust gas. The exhaust gas issued from the desulfurizing reactor 4 is guided to a dust collector 8 while the temp. thereof is controlled to the condensing point of water or the dew point of sulfuric acid or higher. By this method, the condensation of water or sulfuric acid causing scale can be prevented. COPYRIGHT: (C)1992,JPO&Japio

Yasuyuki Nishimura

Papers

Exhaust gas desulfurizer