Method of controlling a wet scrubber useful for removing sulphur dioxide from a process gas

Patent metadata

Field	Value
Publication number	US-2016346730-A1
Application number	US-201615231899-A
Country	US
Kind code	A1
Filing date	Aug 9, 2016
Priority date	Oct 7, 2011
Publication date	Dec 1, 2016
Grant date	—

Abstract

A wet scrubber for cleaning a process gas containing sulphur dioxide comprises an absorption vessel for contacting the process gas with an absorption liquid to absorb sulphur dioxide from the process gas, a sensor for measuring a concentration in the absorption liquid, and a control unit. The control unit is adapted to receive a measurement signal from the sensor and to control, based on the measured concentration, at least one wet scrubber operating parameter influencing the concentration in the absorption liquid.

First claim

1 . A method of controlling a wet scrubber used to clean a process gas containing sulphur dioxide, the method comprising:
contacting the process gas with an absorption liquid in an absorption vessel to absorb sulphur dioxide from the process gas; measuring a concentration of sulphite in the absorption liquid to obtain a sulphite concentration measurement; and controlling, based on the sulphite concentration measurement, at least one scrubber operating parameter influencing the concentration of sulphite in the absorption liquid.

2 . A method according to claim 1 , further comprising:
comparing the sulphite concentration measurement to a set point therefore; and effecting, when the sulphite concentration measurement exceeds the set point, at least one of:
increasing a supply of a gas containing oxygen to the absorption liquid;
reducing a pH of the absorption liquid; and
supplying an absorption enhancing additive to the absorption liquid.

3 . A method according to claim 1 , further comprising:
comparing the sulphite concentration measurement to a set point therefore; and effecting, when the sulphite concentration measurement exceeds the set point, a reduction of a pH of the absorption liquid accompanied by at least one of:
increasing a liquid to gas ratio in the absorption vessel; and
increasing a supply of an absorption enhancing additive to the absorption liquid.

4 . A method according to claim 1 , further comprising:
comparing the sulphite concentration measurement to a set point therefore; and effecting, when the sulphite concentration measurement is below the set point, at least one of:
reducing a supply of a gas containing oxygen to the absorption liquid;
increasing a pH of the absorption liquid; and
reducing a supply of an absorption enhancing additive to the absorption liquid.

5 . A method according to claim 1 , further comprising:
comparing the sulphite concentration measurement to a set point therefore; and effecting, when the sulphite concentration measurement is below the set point, an increase of a pH of the absorption liquid accompanied by at least one of:
reducing a liquid to gas ratio in the absorption vessel; and
reducing a supply of an absorption enhancing additive to the absorption liquid.

6 . A method according to claim 1 , further comprising:
collecting absorption liquid after sulphur dioxide absorption by the absorption liquid from the process gas; and measuring a sulphite concentration of the collected absorption liquid to obtain a sulphite concentration measurement prior to mixing the absorption liquid with absorbent material.

7 . A method according to claim 1 , further comprising:
collecting absorption liquid after sulphur dioxide absorption by the absorption liquid from the process gas; and measuring a sulphite concentration of the collected absorption liquid to obtain a sulphite concentration measurement prior to mixing the absorption liquid with absorbent material and prior to bubbling an oxygen containing gas through the absorption liquid.

8 . A method according to claim 1 , further comprising:
collecting absorption liquid after sulphur dioxide absorption by the absorption liquid from the process gas; and measuring the concentration of sulphite within 1 minute of collecting the absorption liquid from the absorption vessel.

9 . A method according to claim 1 , further comprising:
collecting absorption liquid after sulphur dioxide absorption by the absorption liquid from the process gas and prior to bubbling an oxygen containing gas through the absorption liquid; measuring a first concentration of sulphite of the collected absorption liquid to obtain a first measurement; collecting absorption liquid after the absorption liquid is exposed to a bubbling of oxygen containing gas; measuring a second concentration of sulphite of the exposed absorption liquid to obtain a second measurement, and comparing the first measurement to the second measurement to determine whether the concentration of sulphite is increasing or decreasing.

10 . A method according to claim 1 , further comprising:
detecting, based on a comparison between a first sulphite concentration measurement and a second sulphite concentration measurement, if the sulphite concentration of the absorption liquid is increasing; and effecting, when the sulphite concentration is increasing, at least one of:
increasing a supply of a gas containing oxygen to the absorption liquid;
reducing a pH of the absorption liquid; and
supplying an absorption enhancing additive to the absorption liquid.

Assignees

• Alstom Technology Ltd

Inventors

• Brogaard Fredrik Jens
• Forsgren Kerstin Margareta
• Larsson Mikael
• Håkansson Rikard Bjoernsture

Classifications

• B01D2257/2047

  Hydrofluoric acid · CPC title

• B01D2252/602

  Activators, promoting agents, catalytic agents or enzymes · CPC title

• B01D53/504

  characterised by a specific device · CPC title

• G01N33/0042

  SO2 or SO3 · CPC title

• B01D53/346 Primary

  Controlling the process · CPC title