# US 9,873,082 B2 · Wet type flue gas desulfurization apparatus and operation method of the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,873,082 B2 - Document ID: US9873082B2 - Status: Granted - Kind: B2 - Application number: 15/081,545 - Filed: 2016-03-25 - Published: 2016-09-29 - Granted: 2018-01-23 - Earliest claimed: 2015-03-27 - Assignees: Mitsubishi Hitachi Power Systems, Ltd. - Applicants: Mitsubishi Hitachi Power Systems, Ltd. - Inventors: Shintaro Honjo; Norikazu Inaba; Takuya Okamoto; Jun Hashimoto; Naoyuki Kamiyama - Web page: https://patentgrep.com/patent/US9873082B2 ## CPC - B01D 53/505: {in a spray drying process} - B01D 53/346: {Controlling the process} - B01D 53/508: {by treating the gases with solids} - B01D 53/80: Semi-solid phase processes, i.e. by using slurries - B01D 2251/404: of calcium - B01D 2251/606: Carbonates - B01D 2258/0283: Flue gases - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) ## Abstract Provided is an absorber that removes sulfur oxide in a flue gas with an absorbent, an absorbent storing unit that stores the absorbent that has absorbed the sulfur oxide, an oxidation-reduction potential meter that measures an oxidation-reduction potential of the absorbent in the absorbent storing unit, a reducing additive supplying unit that supplies a sulfur oxoacid reducing additive into the absorbent storing unit, and a control device that controls the reducing additive supplying unit based on a measured value of the oxidation-reduction potential of the absorbent measured with the oxidation-reduction potential meter, wherein the reducing additive supplying unit supplies the sulfur oxoacid reducing additive when the measured value of the oxidation-reduction potential has exceeded an upper limit of an appropriate range of the oxidation-reduction potential. ## Claims ### Claim 1 A wet type flue gas desulfurization apparatus comprising: an absorber that removes sulfur oxide in a flue gas with an absorbent; an absorbent storing unit that stores the absorbent that has absorbed the sulfur oxide; an oxidation-reduction potential meter that measures an oxidation-reduction potential of the absorbent in the absorbent storing unit; a reducing additive supplying unit that supplies a sulfur oxoacid reducing additive into the absorbent storing unit; and a control device that controls the reducing additive supplying unit based on a measured value of the oxidation-reduction potential of the absorbent measured with the oxidation-reduction potential meter, wherein the reducing additive supplying unit supplies the sulfur oxoacid reducing additive when the measured value of the oxidation-reduction potential has exceeded an upper limit of an appropriate range of the oxidation-reduction potential. ### Claim 2 (depends on 1) The wet type flue gas desulfurization apparatus according to claim 1, wherein the valence of the sulfur oxoacid reducing additive is two to four. ### Claim 3 (depends on 1) The wet type flue gas desulfurization apparatus according to claim 1, wherein the sulfur oxoacid reducing additive is at least one of sodium thiosulfate, sodium metabisulfite, and sodium dithionite. ### Claim 4 (depends on 1) The wet type flue gas desulfurization apparatus according to claim 1, wherein the appropriate range of the oxidation-reduction potential is 50 mV to 200 mV. ### Claim 5 (depends on 1) The wet type flue gas desulfurization apparatus according to claim 1, comprising: a flue gas duct that is connected to the absorber and discharges a purified gas that has passed through the absorber; and a mercury meter that is provided in the flue gas duct and measures the concentration of mercury in the purified gas discharged from the absorber, wherein the reducing additive supplying unit supplies the sulfur oxoacid reducing additive when a value of the mercury meter exceeds a predetermined threshold value. ### Claim 6 (depends on 1) The wet type flue gas desulfurization apparatus according to claim 1, further comprising an oxidizing additive supplying unit that supplies an oxidizing additive into the absorbent storing unit, wherein the control device controls the oxidizing additive supplying unit to supply the oxidizing additive into the absorbent storing unit when the measured value of the absorbent measured with the oxidation-reduction potential meter is lower than 50 mV as a result of supplying the sulfur oxoacid reducing additive. ### Claim 7 An operation method of a wet type flue gas desulfurization apparatus, comprising: adjusting the oxidation-reduction potential to be within the appropriate range by supplying a sulfur oxoacid reducing additive in a case where, when sulfur oxide in a flue gas is removed by an absorbent, an oxidation-reduction potential of the absorbent has exceeded an upper limit of an appropriate range of the oxidation-reduction potential. ### Claim 8 (depends on 7) The operation method of a wet type flue gas desulfurization apparatus according to claim 7, wherein the valence of the sulfur oxoacid reducing additive is two to four. ### Claim 9 (depends on 7) The operation method of a wet type flue gas desulfurization apparatus according to claim 7, wherein the sulfur oxoacid reducing additive is at least one of sodium thiosulfate, sodium metabisulfite, and sodium dithionite. ### Claim 10 (depends on 7) The operation method of a wet type flue gas desulfurization apparatus according to claim 7, wherein the appropriate range of the oxidation-reduction potential is 50 mV to 200 mV. ### Claim 11 (depends on 7) The operation method of a wet type flue gas desulfurization apparatus according to claim 7, wherein when the concentration of mercury in a purified gas discharged from an absorber is measured and the concentration exceeds a predetermined threshold value as a result of the mercury measurement, the sulfur oxoacid reducing additive is supplied to decrease the concentration of mercury to the predetermined threshold value or lower. ### Claim 12 (depends on 7) The operation method of a wet type flue gas desulfurization apparatus according to claim 7, wherein when a measured value of the oxidation-reduction potential of the absorbent is lower than 50 mV as a result of supplying the sulfur oxoacid reducing additive, an oxidizing additive is supplied. ### Claim 13 (depends on 12) The operation method of a wet type flue gas desulfurization apparatus according to claim 12, wherein the valence of the sulfur oxoacid reducing additive is two to four. ### Claim 14 (depends on 12) The operation method of a wet type flue gas desulfurization apparatus according to claim 12, wherein the sulfur oxoacid reducing additive is at least one of sodium thiosulfate, sodium metabisulfite, and sodium dithionite. ### Claim 15 (depends on 12) The operation method of a wet type flue gas desulfurization apparatus according to claim 12, wherein the appropriate range of the oxidation-reduction potential is 50 mV to 200 mV.