GB2131715A - Removal of solid product from flue gas scrubber using lime (stone) slurry - Google Patents
Removal of solid product from flue gas scrubber using lime (stone) slurry Download PDFInfo
- Publication number
- GB2131715A GB2131715A GB08328691A GB8328691A GB2131715A GB 2131715 A GB2131715 A GB 2131715A GB 08328691 A GB08328691 A GB 08328691A GB 8328691 A GB8328691 A GB 8328691A GB 2131715 A GB2131715 A GB 2131715A
- Authority
- GB
- United Kingdom
- Prior art keywords
- suspension
- lime
- washing suspension
- scrubber
- solids
- Prior art date
- Legal status (The legal status 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 status listed.)
- Granted
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/48—Sulfur compounds
- B01D53/50—Sulfur oxides
- B01D53/501—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/46—Sulfates
- C01F11/464—Sulfates of Ca from gases containing sulfur oxides
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Inorganic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Geology (AREA)
- Biomedical Technology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Treating Waste Gases (AREA)
- Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
A method for the continuous extraction of washing suspension solids from a tower scrubber 1 of a flue-gas desulphurizing plant working with lime or limestone as an absorbing medium, in which a circulating flow is imposed on the washing suspension in the residence tank 2 of the scrubber and washing suspension is drawn off from the zones having an increased concentration of solids which form in the course of this. In one embodiment the washing suspension is drawn off from the zone with an increased concentration of solids forming in the central bottom region of the residence tank. <IMAGE>
Description
SPECIFICATION
Method for the continuous extraction of washing suspension with an increased solids concentration from a tower scrubber of a fluegas desulphurizing plant working with lime or limestone as an absorbing medium
The invention relates to a method for the continuous extraction of washing suspension with an increased solids concentration from a tower scrubber of a flue-gas desulphurizing plant working with lime or limestone as an absorbing medium.
It is known to bring flue gases from combustion processes into contact with suspensions containing lime in order to separate out the sulphur oxides contained therein. The absorbed sulphur oxides react in the washing solution with the absorbing medium lime, in the course of which the following compounds are primarily formed: Cay03. 2 H20 (calcium sulphite semihydrate) and CaSO4.2H2O (calcium sulphate dihydrate). It is known to oxidize the calcium sulphite semihydrate almost completely into calcium sulphate dihydrate by blowing air into the scrubber sump. The reaction product calcium sulphate dihydrate forming in this manner is only water-soluble to a small extent. The washing circuit therefore consists mainly of a suspension with a solids content of various heights.During conventional conduct of the process, a component stream of this suspension is drawn off and supplied to a multi-stage dewatering. The first dewatering stage serves to concentrate the solids content to such an extent that the necessary final moistness of < 10% by weight can be achieved in the following second stage with the appropriate conventional apparatus.
It is a disadvantage of this conduct of the process that the dewatering has to be carried out in a plurality of stages. Considerable expenditure on apparatus is necessary for this.
It is the object of the invention to be able to extract the washing suspension from the washing circuit with an increased solids concentration through an appropriate formation of the circulating flow in the residence tank and through an appropriate selection of the extraction position in the residence tank, the solids extracted predominantly containing the coarser grain fractions and the finer grain fractions remaining in the washing circuit for further growth.
In order to solve this problem, according to the invention a method is proposed which is characterised in that a circulating flow is imposed on the washing suspension in the residence tank of the scrubber and washing suspension is drawn off from the zones o#f increased solids concentration forming in the course of this.
According to a preferred form of execution of the method according to the invention, washing suspension is drawn off from the zone with an increased solids concentration forming in the central bottom region of the residence tank.
The advantages which are achieved by the method according to the invention consist in that the conventional conduct of the process can be made simpler, particularly so far as the rapid and effective reaching of a residual moisture content of < 10% by weight is concerned. As a result of the fact that a formation of the circulating flow which allows forces to be effective on the solid particles in the suspension which lead to an accumulation of solids in specific zones of the suspension, is effected already in the residence tank, an extraction position for suspension with an increased solids concentration can be provided already in the residence tank without having to provide expensive following concentration systems.As a result of the production of a circulating flow, the coarser grain fractions predominantly enter the possible offtake zones while the finer grain fractions remain in the washing circuit for.further grain growth. This effect has a positive effect on the consumption of absorbing medium and improves the ability to dewater the calcium sulphate dihydrate.
The conventional conduct of the method and the conduct of the method according to the invention are described in connection with examples of embodiment with reference to the
Figures illustrated in the drawings.
Figure 1 shows an example of carrying out a conventional conduct of the method,
Figure 2 shows a possible conduct of the method according to the invention.
Flue gas is brought into contact with the washing suspension containing lime in a tower scrubber 1. In the course of this, calcium sulphite semihydrate is formed and, according to the oxygen content of the flue gas, certain amounts of calcium sulphate dihydrate. For the disposal, it is necessary to oxidize the calcium sulphite to calcium sulphate. This can be effected by blowing air into the scrubber sump 2. A component stream is taken from the scrubber sump 2 via the pipeline 3 with pump 4 and supplied to the dewatering.
The dewatering usually consists of two stages connected in series. The first stage 5 may, for example, be constructed in the form of a sedimentation clarifier or as a hydro-cyclone. In this stage, the suspension is concentrated to solids contents of 30~50% by weight of solids.
The suspension thickened to this extent is then supplied to a second stage 6 via a pipeline 7 with pump 8. This second stage 6 may consist 0: vacuum filters or centrifuges. Here the end product is dewatered down to the required residual moistness of < 10% by weight.
So far as the flue-gas treatment is concerned, the method according to the invention corresponds to the method described in Figure 1.
The essential difference consists in that the suspension is subjected to a deliberate circulating flow in the scrubber sump as a result of which the solid components contained in the suspension, particularly those with a coarser grain fraction, lead to a local accumulation of solids in certain zones out of which a suspension with an increased concentration of solids can then be extracted. An accumulation of solids in the suspension, encouraged in this manner, makes a further thickening superfluous so that the suspension can be supplied directly to the final dewatering end stage 11. This is effected via a pipeline 9 with pump 10. In principle, the same dewatering apparatus can be used for the final dewatering end stage as in the conventional method as shown in
Figure 1.
The course of the method described in Figure 2 presupposes that a preliminary concentration of 25~40% by weight is achieved in the scrubber sump. If such a result cannot be achieved and preliminary concentrations below 25% by weight are withdrawn from the scrubber sump, then a two-stage dewatering is again necessary, but in this case the first dewatering stage can be made distinctly smaller in comparison with the conventional method as shown in Figure 1 and in addition the classifying effect described above is still effective.
Claims (3)
1. A method for the continuous extraction of washing suspension with an increased solids concentration from a tower scrubber of a flue-gas desulphurizing plant working with lime or limestone as an absorbing medium, characterised in that a circulating flow is imposed on the washing suspension in the residence tank of the scrubber and washing suspension is withdrawn from the zones of increased solids concentration forming in the course of this.
2. A method as claimed in Claim 1, characterised in that washing suspension is withdrawn from the zone with increased solids concentration forming in the central bottom region of the residence tank.
3. A method for the continuous extraction of washing suspension with an increased solids concentration from a tower scrubber of a flue-gas desulphurizing plant working with lime or limestone as an absorbing medium, as claimed in
Claim 1 and substantially as hereinbefore described with reference to the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19823241540 DE3241540A1 (en) | 1982-11-10 | 1982-11-10 | METHOD FOR THE CONTINUOUS REMOVAL OF WASHING SUSPENSION WITH INCREASED SOLIDS CONCENTRATION FROM A WASHING TOWER OF A SMOKE GAS DESULPATION SYSTEM WORKING WITH LIME OR LIMESTONE AS AN ABSORPTION AGENT |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8328691D0 GB8328691D0 (en) | 1983-11-30 |
| GB2131715A true GB2131715A (en) | 1984-06-27 |
| GB2131715B GB2131715B (en) | 1986-08-06 |
Family
ID=6177763
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08328691A Expired GB2131715B (en) | 1982-11-10 | 1983-10-27 | Removal of solid product from flue gas scrubber using lime (stone) slurry |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS5998718A (en) |
| DE (1) | DE3241540A1 (en) |
| FR (1) | FR2535618A1 (en) |
| GB (1) | GB2131715B (en) |
| ZA (1) | ZA838276B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4900524A (en) * | 1987-06-29 | 1990-02-13 | Vth Ag Verfahrenstechnik Fur Heizung | Method for separation of sulfur dioxide from gases |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3537949A1 (en) * | 1985-10-25 | 1987-04-30 | Hoelter Heinz | SO2 and NOx gas purification plant having sodium sulphate end product |
| DE3601454A1 (en) * | 1986-01-20 | 1987-07-30 | Hoelter Heinz | Process for removing HCl, HF, SO3, SO2 and NOx from combustion exhaust gases by simultaneous wet scrubbing with controlled scrubbing water circulation and specific addition of lime |
| CN101559313B (en) * | 2008-04-18 | 2012-08-08 | 上海汇友精密化学品有限公司 | Method for reducing sewage discharge in washed method |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB364256A (en) * | 1930-07-31 | 1932-01-07 | Mendel Frey | Separation of solid particles from flue gases |
| GB2042924A (en) * | 1979-02-21 | 1980-10-01 | Denken Mechanical Services Ltd | Water Spray Dust Separator |
| EP0017348A1 (en) * | 1979-03-06 | 1980-10-15 | Peabody Process Systems, Inc. | Flue gas scrubbing process using fly ash alkali |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2447165A1 (en) * | 1974-04-01 | 1976-04-22 | Heinz Hoelter | Gas purification to remote sulphur dioxide - with calcium cpds in presence of sulphuric and other acids to prevent deposition of calcium carbonate |
| DE2444819B2 (en) * | 1974-09-19 | 1980-01-03 | Steag Ag, 4300 Essen | Process for cleaning the gas produced in the gasification process |
| DE2458157C3 (en) * | 1974-12-09 | 1984-03-15 | Werner Dr.-Ing. 7531 Kieselbronn Weber | Rain basin for sewage systems |
| DE2613578C3 (en) * | 1974-12-09 | 1981-09-17 | Werner Dr.-Ing. 7531 Kieselbronn Weber | Rain basin for sewage systems |
-
1982
- 1982-11-10 DE DE19823241540 patent/DE3241540A1/en active Granted
-
1983
- 1983-10-27 GB GB08328691A patent/GB2131715B/en not_active Expired
- 1983-11-07 FR FR8317622A patent/FR2535618A1/en not_active Withdrawn
- 1983-11-07 ZA ZA838276A patent/ZA838276B/en unknown
- 1983-11-10 JP JP58209998A patent/JPS5998718A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB364256A (en) * | 1930-07-31 | 1932-01-07 | Mendel Frey | Separation of solid particles from flue gases |
| GB2042924A (en) * | 1979-02-21 | 1980-10-01 | Denken Mechanical Services Ltd | Water Spray Dust Separator |
| EP0017348A1 (en) * | 1979-03-06 | 1980-10-15 | Peabody Process Systems, Inc. | Flue gas scrubbing process using fly ash alkali |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4900524A (en) * | 1987-06-29 | 1990-02-13 | Vth Ag Verfahrenstechnik Fur Heizung | Method for separation of sulfur dioxide from gases |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5998718A (en) | 1984-06-07 |
| GB2131715B (en) | 1986-08-06 |
| GB8328691D0 (en) | 1983-11-30 |
| DE3241540C2 (en) | 1987-10-08 |
| DE3241540A1 (en) | 1984-05-10 |
| FR2535618A1 (en) | 1984-05-11 |
| ZA838276B (en) | 1984-06-27 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |