WO1999023037A1 - Method for neutralization of waste water - Google Patents

Method for neutralization of waste water Download PDF

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Publication number
WO1999023037A1
WO1999023037A1 PCT/NO1998/000328 NO9800328W WO9923037A1 WO 1999023037 A1 WO1999023037 A1 WO 1999023037A1 NO 9800328 W NO9800328 W NO 9800328W WO 9923037 A1 WO9923037 A1 WO 9923037A1
Authority
WO
WIPO (PCT)
Prior art keywords
absorber
waste water
seawater
alkality
sump
Prior art date
Application number
PCT/NO1998/000328
Other languages
French (fr)
Inventor
Göran Nyman
Arne Ellestad
Svein STRØMMEN
Original Assignee
ABB Fläkt AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ABB Fläkt AB filed Critical ABB Fläkt AB
Priority to AU97670/98A priority Critical patent/AU9767098A/en
Publication of WO1999023037A1 publication Critical patent/WO1999023037A1/en

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment

Definitions

  • the present invention is related to a method for neutralization of waste water from cleaning of flue gases emitted from power plants.
  • the method according to the present invention is providing a possibility to add some additional alkalinity to the sea water during only under these rare upset conditions that
  • CONFIRMATION COP* might appear less than 10 % of the time of the year.
  • S0 2 is absorbed into sea water in an absorber tower.
  • the effluent is normally neutralized only by the natural alkalinity in the seawater added in the absorber and the additional seawater mixed with the effluent prior to aeration.
  • the aeration basin (water flow and hold up time) is designed to maintain the required effluent pH for seawater alkalinity 's and sulphur in fuel occurring 90 % of the time of the year.
  • additional alkalinity in form of Ca(0H) 2 or any other suitable base is added in the absorber sump or in the outlet pipe from the absorber.
  • the concentration of added Ca(0H) 2 will be low, and any precipitation in the absorber sump will quickly be dissolved when the effluent is diluted with more seawater prior to aeration. Expensive and complicated auxiliary equipment for mixing are also avoided.
  • the addition of alkalinity is automatically controlled by continuous pH measurements in the aeration basin.
  • the size of the aeration basin and required seawater flow can, according to the invention, be designed for normal sea water alkalinity and normal sulphur content in the fuel. This results in smaller plants than if the plant and the total sea water flow would have to be designed for a seldom occurring low alkalinity in the seawater, or seldom occurring high sulphur content in the fuel .
  • any drop in the alkalinity of the sea water or any increase of the sulphur content in the fuel will automatically be compensated by an addition of lime or any other suitable base.

Abstract

Method for neutralizing waste water from cleaning of flue gases emitted from power plants, in an aeration basin for waste water, by which at the sump of the absorber or in the outlet pipe of the absorber, the waste water is neutralized with the natural alkality of seawater which is supplied to the absorber and the following aeration basin, continuously to monitor the pH of the waste water, and to add additional alkality, such as in the form of Ca(OH)2, to the sump of the absorber or in the outlet pipe of the absorber, before the water is mixed with the rest of the seawater amount for aeration, should the alkality of the seawater decrease or the sulphur content of the flue gases increase.

Description

Method for neutralization of waste water The present invention is related to a method for neutralization of waste water from cleaning of flue gases emitted from power plants.
When S02 in flue gases is absorbed into seawater in a once through operation, the water is acidified. In order to improve the quality of effluent so that it can be discharged back to the sea, the added S02 has to be neutralized. The following methods of doing this neutralization has been described:
A. Continuous supply of a base (calcium based alkali) in order to neutralize the addition of acid.
B. Channelling the effluent through a limestone bed.
C. Use of large volumes of seawater (spent power plant cooling water) and the natural carbonate content of this water.
By use of method "A" it is difficult to have all the added alkali dissolved due to the high concentrations required. Not dissolved alkali may lead to an undesirable visible white plume at the cooling water outlet. The use of method "B" in practice will lead to low rate of dissolvent of the limestone and thereby a requirement of large areas. Replacement of the bed will be necessary from time to time, which is time consuming and expensive.
When large amounts of spent cooling water are used according to the method "C", there will from time to time occur problems due to the variations of the natural carbonate content caused by impact of currents and weather conditions.
Today the entire neutralization system has to be designed for the worst possible conditions. These conditions might appear 1 to 2 % of the time of the year, and be significantly worse than average conditions.
In similar shorter period of time, it may also be desirable to burn fuel with higher sulphur content than normal .
In such periods of time (maximum 10 % of the operation time), there will not be sufficient seawater available to neutralize all the absorbed sulphur dioxide.
The method according to the present invention is providing a possibility to add some additional alkalinity to the sea water during only under these rare upset conditions that
CONFIRMATION COP* might appear less than 10 % of the time of the year.
The above is achieved with the method according to the invention as described with the features stated in the claims . S02 is absorbed into sea water in an absorber tower. The effluent is normally neutralized only by the natural alkalinity in the seawater added in the absorber and the additional seawater mixed with the effluent prior to aeration.
The aeration basin (water flow and hold up time) is designed to maintain the required effluent pH for seawater alkalinity 's and sulphur in fuel occurring 90 % of the time of the year. In situations were sea water alkalinity is lower or when sulphur in fuel is higher than design, additional alkalinity in form of Ca(0H)2, or any other suitable base is added in the absorber sump or in the outlet pipe from the absorber. By adding the alkalinity in the absorber sump, or in the outlet pipe where pH is relatively low, the dissolution will go much faster, compared with an addition in the aeration basin, where pH is higher. The concentration of added Ca(0H)2 will be low, and any precipitation in the absorber sump will quickly be dissolved when the effluent is diluted with more seawater prior to aeration. Expensive and complicated auxiliary equipment for mixing are also avoided.
The addition of alkalinity is automatically controlled by continuous pH measurements in the aeration basin. The size of the aeration basin and required seawater flow can, according to the invention, be designed for normal sea water alkalinity and normal sulphur content in the fuel. This results in smaller plants than if the plant and the total sea water flow would have to be designed for a seldom occurring low alkalinity in the seawater, or seldom occurring high sulphur content in the fuel .
With the method according to the present invention, any drop in the alkalinity of the sea water or any increase of the sulphur content in the fuel will automatically be compensated by an addition of lime or any other suitable base.

Claims

Patent Claim
Method for neutralizing waste water from cleaning of flue gases emitted from power plants, in an aeration basin for waste water, CHARACTERIZED IN at the sump of the absorber or in the outlet pipe of the absorber, the waste water is neutralized with the natural alkality of seawater which is supplied to the absorber and the following aeration basin, continuously to monitor the pH of the waste water, and to add additional alkality, such as in the form of Ca(0H)2, to the sump of the absorber or in the outlet pipe of the absorber, before the water is mixed with the rest of the seawater amount for aeration, should the alkality of the seawater decrease or the sulphur content of the flue gases increase.
PCT/NO1998/000328 1997-10-31 1998-10-30 Method for neutralization of waste water WO1999023037A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU97670/98A AU9767098A (en) 1997-10-31 1998-10-30 Method for neutralization of waste water

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NO19975030 1997-10-31
NO975030A NO975030L (en) 1997-10-31 1997-10-31 Procedure for neutralizing drainage water

Publications (1)

Publication Number Publication Date
WO1999023037A1 true WO1999023037A1 (en) 1999-05-14

Family

ID=19901279

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/NO1998/000328 WO1999023037A1 (en) 1997-10-31 1998-10-30 Method for neutralization of waste water

Country Status (3)

Country Link
AU (1) AU9767098A (en)
NO (1) NO975030L (en)
WO (1) WO1999023037A1 (en)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4337230A (en) * 1980-02-13 1982-06-29 Ab Svenska Flaktfabriken Method of absorbing sulfur oxides from flue gases in seawater
US5484535A (en) * 1994-05-19 1996-01-16 The Babcock & Wilcox Company Seawater effluent treatment downstream of seawater SO2 scrubber

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4337230A (en) * 1980-02-13 1982-06-29 Ab Svenska Flaktfabriken Method of absorbing sulfur oxides from flue gases in seawater
US5484535A (en) * 1994-05-19 1996-01-16 The Babcock & Wilcox Company Seawater effluent treatment downstream of seawater SO2 scrubber

Also Published As

Publication number Publication date
NO975030L (en) 1999-05-03
NO975030D0 (en) 1997-10-31
AU9767098A (en) 1999-05-24

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