Method of control for a wet lime-gypsum process desulfurization plant

• US 4,582,692 A
• Filed: 04/26/1984
• Issued: 04/15/1986
• Est. Priority Date: 04/26/1983
• Status: Expired due to Term

• Current Assignee: Mitsubishi Jukogyo Kabushiki Kaisha (Mitsubishi Heavy Industries, Ltd.)
• Original Assignee: Mitsubishi Jukogyo Kabushiki Kaisha (Mitsubishi Heavy Industries, Ltd.)
• Inventors: Kono, Susumu, Hamanaka, Kengo, Morinaga, Katsuyuki, Nonogaki, Yutaka
• Primary Examiner(s): HELLER, GREGORY
• Application Number:
  US06/604,362
• Time in Patent Office: 719 Days
• Field of Search: 423/242 A, 423/242 R, 423/244 A, 423/244 R, 55/73, 422/62, 436/122
• US Class Current: 423/243.01
• CPC Class Codes: B01D 53/501 by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound

Abstract

In an absorption tower of a wet lime-gypsum process desulfurization plant which desulfurizes an exhaust gas by bringing an incoming exhaust gas into contact with an absorbent liquid circulated therethrough by means of a plurality of pumps, an optimum pH value of the absorbent liquid and an optimum number of working pumps are set according to an amount of an exhaust gas load of the absorption tower, and a feed rate of the absorbent liquid and a number of working pumps are controlled on the basis of these set values. According to one mode of embodiment of the invention, a variation rate of the exhaust gas load and a desulfurization ratio are detected, and when the amount of exhaust gas load is constant or rising and also the desulfurization ratio is lower than a desired desulfurization ratio, the number of working pumps is correctively increased. According to another mode of embodiment of the invention, there are provided first and second simulation model, in the first simulation model a pH value of an absorbent liquid and a desulfurization ratio are calculated on the basis of an exhaust gas flow rate, an inlet SO₂ concentration, an absorbent liquid circulation flow rate and a feed rate of a neutralizing agent of the absorbent liquid, these calculated values are compared with detected values of the pH value and the desulfurization ratio during operation, a reaction constant set within the first and second simulation model is corrected on the basis of deviations between the compared values, and said two optinum set values are calculated by the corrected second simulation model.

Claims

1. In a method for controlling a wet lime-gypsum process desulfurization plant, wherein an absorption tower is provided which desulfurizes an exhaust gas by bringing an incoming exhaust gas into contact with an absorbant liquid circulated therethrough by means of a plurality of pumps, the improvement wherein a pH value of the absorbent liquid and a number of working pumps value are set according to the amount of the exhaust gas load of said absorption tower referring to set values which determines the lowest pH value of the absorbent liquid and the minimum number of working pumps for a given amount of desulfurization for each gas load, wherein said set values are prepared by performing a process simulation, and the feed rate of the absorbent liquid and the number of working pumps are controlled on the basis of said set values, and in which said process simulation is created by providing first and second simulation models, in the first simulation model the pH value of the absorbent liquid and the desulfurization ratio are calculated on the basis of the exhaust gas flow rate, the inlet SO₂ concentration, the absorbent liquid circulations flow rate and the feed rate of a neutralizing agent of the absorbent liquid, these calculated values are compared with the detected values of the pH value and the desulfurization ratio during operation, a reaction constant set within the first and second simulation models is corrected on the basis of deviations between the compared values, and said set values are thus created by the corrected second simulation model, whereby economy and capability to accept variation of the load of said plant are improved.