Non-waste water flue gas treatment system and non-waste water flue gas treatment method

Patent metadata

Field	Value
Publication number	US-11325850-B2
Application number	US-201816489505-A
Country	US
Kind code	B2
Filing date	Mar 27, 2018
Priority date	Mar 31, 2017
Publication date	May 10, 2022
Grant date	May 10, 2022

Abstract

An apparatus is disclosed including a desulfurization device which removes sulfur oxides contained in boiler flue gas, a spray drying device which sprays desulfurization waste water discharged from the desulfurization device and which dries the waste water by introducing a drying gas, a flue gas supplying line L13 which returns, to a main flue L11, flue gas obtained after the desulfurization waste water is evaporated and dried, an alkaline agent supplying unit which adds an alkaline agent to a desulfurization waste water line L21, and a pH meter which measures the pH in the desulfurization waste water at locations before and after the alkaline agent supplying unit in the desulfurization waste water line L21, wherein the alkaline agent is added in accordance with a measurement result of a measured pH to cause the desulfurization waste water added with the alkaline agent to have a pH fall within a predetermined pH.

First claim

The invention claimed is:

1. A non-waste water flue gas treatment system, comprising:
a boiler configured to combust fuel;
a heat recovering device provided in a main flue that discharges a boiler flue gas from the boiler and configured to recover heat of the boiler flue gas;
a desulfurization device configured to remove a sulfur oxide contained in the boiler flue gas with a desulfurization absorbing liquid;
a spray drying device configured to spray waste water including desulfurization waste water discharged from the desulfurization device;
a flue gas introduction line configured to introduce a drying gas for evaporating and drying the desulfurization waste water into the spray drying device;
a flue gas supplying line configured to return a flue gas obtained after the desulfurization waste water being evaporated and dried in the spray drying device back to the main flue;
an alkali supplying unit configured to add an alkaline agent to a desulfurization waste water line that connects the desulfurization device and the spray drying device; and
a pH meter configured to measure a pH in the desulfurization waste water in the desulfurization waste water line before and after the alkali supplying unit, wherein
the alkali supplying unit adds the alkaline agent in accordance with a measurement result of a measured pH to cause a pH value of desulfurization waste water after addition of the alkaline agent to fall within pH 6 to 10.

2. The non-waste water flue gas treatment system according to claim 1 , further comprising:
a solid-liquid separator provided in the desulfurization waste water line that discharges the desulfurization waste water and configured to separate a solid; and
a separated water introduction line configured to supply separated water from the solid-liquid separator to the spray drying device, wherein
the alkali supplying unit is provided in the separated water introduction line between the solid-liquid separator and the spray drying device,
the pH meter is provided in the separated water introduction line at least upstream or downstream of the alkali supplying unit, and
the alkali supplying unit adds the alkaline agent in accordance with a measurement result of a measured pH to cause a pH value of separated water after addition of the alkaline agent to fall within pH 6 to 10.

3. The non-waste water flue gas treatment system according to claim 1 , wherein
a solid removal device configured to remove a solid in flue gas is provided in the flue gas supplying line.

4. A non-waste water flue gas treatment system, comprising:
a boiler configured to combust fuel;
a heat recovering device provided in a main flue that discharges a boiler flue gas from the boiler and configured to recover heat of the boiler flue gas;
a desulfurization device configured to remove a sulfur oxide contained in the boiler flue gas with a desulfurization absorbing liquid;
a spray drying device configured to spray waste water including desulfurization waste water discharged from the desulfurization device;
a flue gas introduction line configured to introduce a drying gas for evaporating and drying the waste water into the spray drying device;
a flue gas supplying line configured to return a flue gas after the waste water being evaporated and dried in the spray drying device back to the main flue;
an alkali supplying unit configured to add an alkaline agent to a desulfurization waste water line that connects the desulfurization device and the spray drying device, or to the flue gas supplying line; and
a chlorine ion measurement device provided in any one of or a plurality of the main flue, the flue gas supplying line and the desulfurization waste water line and configured to measure a concentration of a chlorine ion, wherein
the alkali supplying unit adds the alkaline agent to the desulfurization waste water or the flue gas in accordance with a result of a measured chlorine ion concentration to cause a molar ratio of alkaline agent and chlorine (Cl) ion to fall within a predetermined range.

5. The non-waste water flue gas treatment system according to claim 4 , further comprising:
a solid-liquid separator provided in the desulfurization waste water line that discharges the desulfurization waste water and configured to separate a solid; and
a separated water introduction line configured to supply separated water from the solid-liquid separator to the spray drying device, wherein
the chlorine ion measurement device and the alkali supplying unit are provided in the separated water introduction line between the solid-liquid separator and the spray drying device, and
the alkali supplying unit adds the alkaline agent to the separated water in accordance with a result of a measured chlorine ion concentration to cause a molar ratio of alkaline agent and chlorine (Cl) ion to fall within a predetermined range.

6. The non-waste water flue gas treatment system according to claim 4 , wherein
the alkaline agent added to the flue gas supplying line is liquid or powder.

7. A non-waste water flue gas treatment system, comprising:
a boiler configured to combust fuel;
a heat recovering device provided in a main flue that discharges a boiler flue gas from the boiler and configured to recover heat of the boiler flue gas;
a desulfurization device configured to remove a sulfur oxide contained in the boiler flue gas with a desulfurization absorbing liquid;
a spray drying device configured to spray waste water including desulfurization waste water from the desulfurization device;
a flue gas introduction line configured to introduce a drying gas for evaporating and drying the desulfurization waste water into the spray drying device;
a flue gas supplying line configured to return a flue gas obtained after the desulfurization waste water being evaporated and dried in the spray drying device back to the main flue;
an alkali supplying unit configured to add an alkaline agent to a desulfurization waste water line that connects the desulfurization device and the spray drying device, or to the flue gas supplying line; and
an electrical conductivity meter provided in any one of or both of the desulfurization device and the desulfurization waste water line and configured to measure electrical conductivity in liquid, wherein
the alkali supplying unit adds the alkaline agent to the desulfurization waste water or the flue gas in accordance with a result obtained by obtaining a chlorine ion concentration in liquid from a relationship between previously obtained electrical conductivity and a chlorine ion to cause a molar ratio of alkaline agent and chlorine (Cl) ion to fall within a predetermined range.

8. The non-waste water flue gas treatment system according to claim 7 , further comprising:
a solid-liquid separator provided in the desulfurization waste water line that discharges the desulfurization waste water and configured to separate a solid; and
a separated water introduction line configured to supply separated water from the solid-liquid separator to the spray drying device, wherein
the electrical conductivity meter and the alkali supplying unit are provided in the separated water introduction line, and
the alkali supplying unit adds the alkaline agent to separated water in accordance with a result obtained by obtaining a chlorine ion concentration in the separated water from a relationship between previously obtained electrical conductivity and a chlorine ion to cause a molar ratio of alkaline agent and chlorine (Cl) ion to fall within a predetermined range.

9. A non-waste water flue gas treatment method, comprising:
a desulfurization step of removing a sulfur oxide contained in a boiler flue gas with a desulfurization absorbing liquid;

Assignees

• Mitsubishi Hitachi Power Sys Ltd
• Mitsubishi Power Ltd

Inventors

• Kamiyama Naoyuki
• Ukai Nobuyuki
• Hirayama Koichiro
• Sugita Satoru
• Ushiku Tetsu
• Fukuda Toshihiro

Classifications

• C02F1/04

  by distillation or evaporation · CPC title

• B01D53/50 Primary

  Sulfur oxides (B01D53/60 takes precedence) · CPC title

• B01D53/18

  Absorbing units; Liquid distributors therefor (B01D3/16, B01D3/26, B01D3/30 take precedence; packing elements B01J19/30, B01J19/32) · CPC title

• B01D53/32

  by electrical effects other than those provided for in group B01D61/00 · CPC title

• B01D53/68

  Halogens or halogen compounds · CPC title