Wet flue gas desulfurization device and method of operating wet flue gas desulfurization device

Abstract

The invention relates to a wet flue gas desulfurization device and a method of operating the wet flue gas desulfurization device. The present invention comprises: an absorption tower 11 that removes sulfur oxides in an exhaust gas with an absorbent solution 14; an absorbent solution storage unit 11b that stores the absorbent solution that has absorbed the sulfur oxides; a redox potential meter 18 that measures the redox potential of the absorbent solution 14; a reducing-additive supply unit 20 that supplies a sulfur oxoacid-based reducing-additive 19 into the absorbent solution 14 or the absorbent solution storage unit 11b; and a control device 50 that controls the reducing-additive supply unit 20 on the basis of the redox potential measurement value for the absorbent solution 14 measured by the redox potential meter 18. If the redox potential measurement value exceeds an upper limit of a suitable range for the redox potential, the control device 50 controls the reducing additive supply unit 20 so as to supply the sulfur oxoacid-based reducing-additive 19.

Description

technical field [0001] The invention relates to a wet-type flue gas desulfurization device and an operation method of the wet-type flue gas desulfurization device. Background technique [0002] For example, as a desulfurization device for removing sulfur oxides in exhaust gas generated by burning heavy oil, coal, etc. in a thermal power plant, etc., the exhaust gas is mixed with a slurry-like absorption liquid (a substance composed of calcium compounds such as limestone) in an absorption tower. ) contact, absorb sulfur oxides in exhaust gas into a slurry-like absorbing liquid, oxidize the slurry-like absorbing liquid after contact, and separate solid-liquid to produce gypsum by-product. [0003] Among the sulfur oxides in the exhaust gas in this case, sulfur dioxide (SO 2 ) is absorbed by the absorption liquid through the reaction, reacts with the oxygen in the exhaust gas and the oxygen supplied from the outside, and generates gypsum. [0004] However, the oxygen concentr...

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Problems solved by technology

Furthermore, due to the natural oxidation caused by the contact between the exhaust gas in the absorption tower and the absorbing liquid, the absorbing liquid becomes overoxidized, and there is a problem that it cannot be controlled to a desired ORP.

[0008] For example, even if the ORP is designed to be controlled at an appropriate value, the ORP is a very high value of 200 to 1000 mV, and it changes unstablely and becomes an overoxidized state. For example, the formation of manganese oxide from which manganese is oxidized, the coloring of gypsum, the generation of manganese scale, the malfunction of pH meters, the clogging of nozzles, and the clogging of solid-liquid separators, etc.

In addition, the selenium in the absorption solution is changed from the 4-valent selenium (Se 4+ ) state becomes difficult to remove hexavalent selenium (Se 6+ ) state, and persulfuric acid is generated in the absorption liquid, so there is a problem that the absorption liquid cannot maintain the wastewater treatment standard and needs to be treated in another way

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