AU6282190A - Method for reducing wear on nozzles or other supply means - Google Patents
Method for reducing wear on nozzles or other supply meansInfo
- Publication number
- AU6282190A AU6282190A AU62821/90A AU6282190A AU6282190A AU 6282190 A AU6282190 A AU 6282190A AU 62821/90 A AU62821/90 A AU 62821/90A AU 6282190 A AU6282190 A AU 6282190A AU 6282190 A AU6282190 A AU 6282190A
- Authority
- AU
- Australia
- Prior art keywords
- flue gas
- reactor
- fly ash
- particles
- fraction
- 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
- 238000000034 method Methods 0.000 title claims description 12
- 230000001603 reducing effect Effects 0.000 title claims description 5
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 28
- 239000003546 flue gas Substances 0.000 claims description 28
- 239000010881 fly ash Substances 0.000 claims description 25
- 230000002745 absorbent Effects 0.000 claims description 20
- 239000002250 absorbent Substances 0.000 claims description 20
- 239000002002 slurry Substances 0.000 claims description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 11
- 239000003344 environmental pollutant Substances 0.000 claims description 8
- 231100000719 pollutant Toxicity 0.000 claims description 8
- 239000011362 coarse particle Substances 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 7
- 239000010419 fine particle Substances 0.000 claims description 5
- 239000007788 liquid Substances 0.000 claims description 4
- 239000007795 chemical reaction product Substances 0.000 claims description 2
- 239000000843 powder Substances 0.000 claims description 2
- 150000001768 cations Chemical class 0.000 claims 1
- 239000002245 particle Substances 0.000 description 26
- 230000000712 assembly Effects 0.000 description 6
- 238000000429 assembly Methods 0.000 description 6
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 4
- 239000000920 calcium hydroxide Substances 0.000 description 4
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 4
- 235000011116 calcium hydroxide Nutrition 0.000 description 4
- 239000000428 dust Substances 0.000 description 4
- 238000004064 recycling Methods 0.000 description 4
- 238000004140 cleaning Methods 0.000 description 3
- 239000003245 coal Substances 0.000 description 3
- 238000002485 combustion reaction Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000012717 electrostatic precipitator Substances 0.000 description 2
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 2
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 2
- 239000003595 mist Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 241000517645 Abra Species 0.000 description 1
- 239000003082 abrasive agent Substances 0.000 description 1
- 239000002956 ash Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 238000005194 fractionation Methods 0.000 description 1
- ZZUFCTLCJUWOSV-UHFFFAOYSA-N furosemide Chemical compound C1=C(Cl)C(S(=O)(=O)N)=CC(C(O)=O)=C1NCC1=CC=CO1 ZZUFCTLCJUWOSV-UHFFFAOYSA-N 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- JTJMJGYZQZDUJJ-UHFFFAOYSA-N phencyclidine Chemical class C1CCCCN1C1(C=2C=CC=CC=2)CCCCC1 JTJMJGYZQZDUJJ-UHFFFAOYSA-N 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
- 239000002594 sorbent Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 235000010269 sulphur dioxide Nutrition 0.000 description 1
- 239000004291 sulphur dioxide Substances 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
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
- B01D53/68—Halogens or halogen compounds
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Biomedical Technology (AREA)
- Environmental & Geological Engineering (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Treating Waste Gases (AREA)
- Perforating, Stamping-Out Or Severing By Means Other Than Cutting (AREA)
Description
METHOD FOR REDUCING WEAR ON NOZZLES OR OTHER SUPPLY MEANS
Field of the Invention
The present invention relates to a method for reduc- ing wear on nozzles or other supply means when finely di¬ viding a slurry consisting of a particulate absorbent suspended in water, in a reactor for separating gaseous pollutants from flue gas containing fly ash. The flue gas, with a substantial portion of its fly ash contents, is supplied to the reactor. The finely divided slurry is mixed with the flue gas. The water is evaporated and re¬ sulting reaction products as well as unreacted absorbent and fly ash are separated as a dry powder from the flue gas in the reactor and/or in a subsequent filter, where- upon a portion of this separated material is classified so as to form a first fraction of fine particles and a second fraction of coarse particles, only said first fraction being recycled to the reactor to be used again. Description of the Prior Art Prior apparatus for cleaning flue gas from combustion of e.g. coal frequently comprise but dust separators for separating the fly ash of the flue gas. The gaseous pol¬ lutants of the flue gas, such as sulphuric dioxide and gaseous hydrogen chloride, are however usually not removed but are emitted to the atmosphere where they are a consid¬ erable strain on the environment.
This strain on the environment can be reduced to a considerable extent if the apparatus for cleaning flue gas is supplemented with a contact reactor. In the contact reactor, the flue gas is mixed with an absorbent reacting with the gaseous pollutants and converting them into par¬ ticulate pollutants which can be separated in ordinary separators. When rebuilding the apparatus, the contact reactor therefore is in most cases positioned upstream of the existing separators so as not to necessitate an addi¬ tional separator downstream of the contact reactor.
The absorbent which is supplied to the contact reac¬ tor cannot be fully utilised in a single passage through the system. To reduce the working expenses, the absorbent is usually recycled a number of times before removal. Un- reacted absorbent is separated together with reaction pro¬ ducts and fly ash and recycled to the contact reactor, for example in the form of a slurry which is finely divided when flowing out at a high velocity from compressed-air nozzles or rotary means. Since the fly ash includes rela- tively coarse, very hare particles, it will have an abra¬ sive effect on nozzles or equivalent supply means for fine division.
This means that the nozzles or equivalent means must be replaced frequently, which is both expensive and time- consuming.
Summary of the Invention
Technical problem Fly ash, especially fly .ash from coal, includes a large amount of oxides which are used in many contexts as abrasives. Problems are therefore always involved in con¬ veying fly ash or material including fly ash by means of a flowing gas or liquid. The wear on the conveying devices highly depends on the velocity of the fly ash particles. The higher the ve¬ locity, the greater will the wear be. In bends and narrow passages and in stop valves, this wear may require repairs at short intervals. The object of the present invention therefore is to provide a simple and effective method for reducing the wear on the nozzles of a contact reactor or equivalent supply means.
Solution of the problem
The present invention reduces the problems with wear on nozzles or other supply means when finely dividing a slurry in a contact reactor where the absorbent is re- cycled, in that the portion of the fly ash having the greatest particles is separated before or in the recycling system proper. Since the heaviest particles have the highest kinetic energy and the highest momentum, they cause substantially more wear than the smaller particles of the same composition.
The coarse fly ash particles can be sorted out in several different ways and according to a number of physical principles. Gravitation, inertial forces and electric or magnetic forces etc. may be utilised. The sorting out can take place before or in the contact reactor or in the recycling part of the system.
A single cyclone or screen-type separator mounted before the reactor can separate the very biggest particles already before they reach the reactor. A suitably designed reactor can, if adapted to use inertia effects or gravita¬ tion, also function as a separator. A certain fractiona- tion of the fly ash portion in the recycled material can be effected if that separated in the reactor is not re¬ cycled at all, but only that separated in a subsequent filter.
However, the work done in the flue gas ducts usually involves considerable expense and necessitates a long shut down during assembly. The present invention therefore sug¬ gests that coarse fly ash particles be separated in the recycling process itself.
This can be effected in essentially the same manner as in the flue gas duct, but at least brings the advantage that the flows to be treated are substantially smaller. One condition is however that the coarse fly ash particles significantly differ from particles containing incom¬ pletely reacted absorbent. Otherwise, also useful material is separated in an unfavourable fashion.
The fly ash usually has such a size distribution that a large portion is coarser than the absorbent, preferably particles of slaked lime, which is suspended in water to be introduced into contact reactors of the type involved in this application. Thus there is a theoretical possibil¬ ity of separating a portion of the fly ash without a great portion of the absorbent being also removed. In practice, the slaked lime is however composed of agglomerates of particles. These agglomerates can be of the same size as the fly ash particles that are desired to be separated. Common dynamic separators will therefore not always yield satisfactory results.
Therefore, the present invention suggests that the separation be performed in liquid phase. This is suitably performed in that the dry pulverulent material intended for recycling is suspended in a liquid, such as water, so that any agglomerates formed from the absorbent are decomposed, whereupon the resulting slurry is conducted through a device to be divided into one fraction of coarse particles and one fraction of fine particles. This divi¬ sion can be effected by e.g. electric or magnetic forces under certain conditions, but is preferably performed by means of a dynamic separator, such as a hydrocyclone. Description of a proposed embodiment The invention will now be described in more detail with reference to the accompanying drawing which shows an apparatus for cleaning flue gas from a coal-fired central boiler plant, said apparatus comprising a suitable device for carrying out the method according to the present invention.
The flue gas formed during combustion of coal in the central boiler plant 1 shown in the drawing is conducted to an air preheater 2. This is adapted to transfer heat from the hot flue gas to combustion air which via a duct 2a is supplied to the central boiler plant by means of a fan 3.
Subsequently, the flue gas is conducted, without prior separation of its fly ash contents, via a duct 4 to a contact reactor 5 where it is mixed with a particulate absorbent, preferably slaked lime, said absorbent being reactive with the gaseous pollutants of the flue gas, such as sulphur dioxide and gaseous hydrogen chloride. The ab¬ sorbent is supplied in the form of an aqueous slurry via a conduit 7 to nozzle assemblies 6 mounted in the upper part of the reactor. The preparation of the slurry and the composition thereof will be described in greater detail later on in the specification.
The nozzle assemblies can be designed for example as disclosed in European Patents 82110320.7 and 85850112.5. In the nozzle assemblies, the slurry is finely divided by means of air which is supplied to the nozzle assemblies via a conduit 8 at a pressure above the pres¬ sure of the slurry. In the nozzle assemblies, air flows at a high velocity through the slurry and decomposes this so that it leaves the nozzles of the nozzle assemblies in the form of finely divided jets of mist 9.
These jets of mist are sprayed into the interior of the contact reactor 5 so that effective mixing of the flue gas and the slurry is achieved. The water of the slurry is- evaporated while contacting the flue gas, and the gaseous pollutants of the flue gas simultaneously react with the absorbent and are transformed into particulate pollutants.
The heavier particles of these particulate pollu¬ tants, unreacted absorbent and the fly ash contents of the flue gas drop into dust hoppers 10 formed in the bottom of the contact reactor. The remaining particles are conducted by the flue gas via a duct 12 to an electrostatic preci- pitator 13. In this, these particles are separated from the flue gas which is led through a duct 14 to a flue gas fan 15 which, through a duct 16, feeds the flue gas cleaned of particulate and gaseous pollutants to a chimney 17 for emission into the atmosphere.
The particles separated in the electrostatic precipi- tator 13 are collected in dust hoppers 18 formed in the bottom thereof. These particles are conveyed by means of air through a conduit 19 to a container 20 in which they are mixed, by means of an agitator 22, with water supplied through a conduit 21. As a result, any agglomerates formed from the particles of the absorbent are decomposed, see the introductory part of the specification, whereupon the resulting slurry is passed through a conduit 23 to a hydrocyclone 24.
In the hydrocyclone, the water-borne particles are classified so that the coarse particles, mainly fly ash particles, are thrown against the walls of the hydro¬ cyclone and drop onto the funnel-shaped bottom thereof. From here, these particles are conveyed together with the part of the water of the slurry that is collected on the bottom of the hydrocyclone through a conduit 25 to a mixer 26. In the mixer, the coarse particles of the slurry are mixed with the particles which are collected in the dust hoppers 10 and supplied to the mixer through a conduit 27. By mixing the last-mentioned particles which mainly con¬ sist of heavy fly ash particles, with the water-borne coarse particles of the slurry, a sufficiently moist resi¬ dual product is obtained, without necessitating the use of a special humidifier. The residual product then is con¬ veyed to a storage bin 28 through a conduit 29.
On the other hand, the fine particles of the slurry accompany the major part of the water of the slurry out of the central part of the hydrocyclone and from there through a conduit 30 to a container 31 where it is mixed, by means of an agitator 33, with a fresh absorbent, preferably slaked lime, supplied through a conduit 32. Subsequently, this mixture is supplied to the contact re¬ actor 5 through the conduit 7, see ne beginning of the description of the figures.
The invention is of course not restricted to the embodiment described above but can be modified in various ways within the scope of the appended claims.
For example, the division of the particles into one fraction of fine particles and one fraction of coarse particles can be provided by means of electric or magnetic forces instead of by means of dynamic separators, such as cyclones.
Claims (6)
1. Method for reducing wear on nozzles or other sup- ply means when finely dividing a slurry consisting of a particulate absorbent suspended in water, in a reactor (5) for separating gaseous pollutants from flue gas containing fly ash, said flue gas with a substantial portion of its fly ash contents being introduced into said reactor to which the the finely divided slurry is supplied and in which it is mixed with the flue gas, the water being evaporated and resulting reaction products as well as unreacted absorbent and fly ash being separated as a dry powder from the flue gas in said reactor and/or in a subsequent filter (13), whereupon a portion of this separated material is classified so as to form a first fraction of fine particles and a second fraction of coarse particles, only the first fraction being recycled to said reactor (5) to be used again, c h a r a c t e r i s - e d in that said portion of the separated material is suspended in a liquid before being classified.
2. Method as claimed in claim 1, c h a r a c t e r ¬ i s e d in that said liquid is water.
3. Method as claimed in claim 1 or 2, c h a r a c - t e r i s e d in that said first fraction is mixed with fresh absorbent before being recycled to said reactor (5).
4. Method as claimed in any one of the preceding claims, c h a r a c t e r i s e d in that the classifi¬ cation is carried out by means of a dynamic separator (24).
5. Method as claimed in claim 4, c h a r a c t e r ¬ i s e d in that: said dynamic separator is a hydrocyclone (24).
6. Method as claimed in any one of claims 1-3, c h a r a c t e r i s e d in that said classification is carried out by means of electric or magnetic forces .
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE8902797A SE465955B (en) | 1989-08-22 | 1989-08-22 | PROVIDED TO REDUCE NOZZLE OF THE NOZZLE OR OTHER SUPPLY ORGANIZATIONS BY FINDING A SLURRY OF A PARTICULAR ABSORBENT |
| SE8902797 | 1989-08-22 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| AU6282190A true AU6282190A (en) | 1991-04-03 |
| AU635327B2 AU635327B2 (en) | 1993-03-18 |
Family
ID=20376714
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU62821/90A Ceased AU635327B2 (en) | 1989-08-22 | 1990-08-13 | Method for reducing wear on nozzles or other supply means |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0491742A1 (en) |
| JP (1) | JPH05500024A (en) |
| AU (1) | AU635327B2 (en) |
| CA (1) | CA2059535A1 (en) |
| SE (1) | SE465955B (en) |
| WO (1) | WO1991002583A1 (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2695678B2 (en) * | 1990-06-20 | 1998-01-14 | 三菱重工業株式会社 | Flue gas desulfurization method |
| CN1039677C (en) * | 1990-11-28 | 1998-09-09 | 三菱重工业株式会社 | Process and unit for desulfuration of flue gases |
| JP3035015B2 (en) * | 1991-08-13 | 2000-04-17 | 三菱重工業株式会社 | Desulfurization method |
| US5194076A (en) * | 1991-10-23 | 1993-03-16 | The Babcock & Wilcox Company | Low pressure drop dry scrubber |
| TR28397A (en) * | 1992-10-22 | 1996-05-30 | Babcock & Wilcox Co | Low pressure dry gas cleaner. |
| CN102941009B (en) * | 2012-11-28 | 2015-09-09 | 佛山市合璟节能环保科技有限公司 | A kind of flue gas continous treatment process and device |
| CN114423511A (en) * | 2019-07-23 | 2022-04-29 | 克莱纳电力解决方案有限公司 | Purification composition, method for producing a purification composition and method for purifying flue gas by means of a purification composition |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4571330A (en) * | 1983-09-29 | 1986-02-18 | Joy Manufacturing Company | Flue gas desulfurization |
| BE902935A (en) * | 1984-07-27 | 1985-11-18 | Hitachi Shipbuilding Eng Co | METHOD AND DEVICE FOR PURIFYING EXHAUST GAS. |
| US4604269A (en) * | 1985-03-22 | 1986-08-05 | Conoco Inc. | Flue gas desulfurization process |
-
1989
- 1989-08-22 SE SE8902797A patent/SE465955B/en not_active IP Right Cessation
-
1990
- 1990-08-13 JP JP51205190A patent/JPH05500024A/en active Pending
- 1990-08-13 AU AU62821/90A patent/AU635327B2/en not_active Ceased
- 1990-08-13 WO PCT/SE1990/000524 patent/WO1991002583A1/en not_active Application Discontinuation
- 1990-08-13 CA CA 2059535 patent/CA2059535A1/en not_active Abandoned
- 1990-08-13 EP EP19900912989 patent/EP0491742A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| CA2059535A1 (en) | 1991-02-23 |
| SE8902797L (en) | 1991-02-23 |
| WO1991002583A1 (en) | 1991-03-07 |
| JPH05500024A (en) | 1993-01-14 |
| AU635327B2 (en) | 1993-03-18 |
| SE465955B (en) | 1991-11-25 |
| EP0491742A1 (en) | 1992-07-01 |
| SE8902797D0 (en) | 1989-08-22 |
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