CA2123884A1 - A gas treatment installation - Google Patents
A gas treatment installationInfo
- Publication number
- CA2123884A1 CA2123884A1 CA 2123884 CA2123884A CA2123884A1 CA 2123884 A1 CA2123884 A1 CA 2123884A1 CA 2123884 CA2123884 CA 2123884 CA 2123884 A CA2123884 A CA 2123884A CA 2123884 A1 CA2123884 A1 CA 2123884A1
- Authority
- CA
- Canada
- Prior art keywords
- bed
- heaters
- air
- combustion
- gas treatment
- 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.)
- Abandoned
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G7/00—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals
- F23G7/06—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of waste gases or noxious gases, e.g. exhaust gases
- F23G7/061—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of waste gases or noxious gases, e.g. exhaust gases with supplementary heating
- F23G7/065—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of waste gases or noxious gases, e.g. exhaust gases with supplementary heating using gaseous or liquid fuel
- F23G7/066—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of waste gases or noxious gases, e.g. exhaust gases with supplementary heating using gaseous or liquid fuel preheating the waste gas by the heat of the combustion, e.g. recuperation type incinerator
- F23G7/068—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of waste gases or noxious gases, e.g. exhaust gases with supplementary heating using gaseous or liquid fuel preheating the waste gas by the heat of the combustion, e.g. recuperation type incinerator using regenerative heat recovery means
Landscapes
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Air Supply (AREA)
- Incineration Of Waste (AREA)
- Devices And Processes Conducted In The Presence Of Fluids And Solid Particles (AREA)
- Gas Burners (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
Abstract
A gas treatment installation of the type known as a combustion exchanger, comprising a generative combustion bed in which one or several heaters are located to heat the bed and to initiate the chemical reaction. The heaters for initiating the reaction are placed out-of-center in the bed, i.e. outside the central part of the bed.
Description
W093/l~t 21 2 3 8 8 ~ PCT/SE92/~574 A GAS TREATMENT INSTALLATION
In the destruction of pollutants through combustion in a gas treatment installation of the type known as a S combustion exchanger (see US-A-4 741 690~ electric heaters are often used to malntain the correct operational temperature in the middle of the combustion bed. If the chemical energy developed in the form of heat during the destruction of the pollutants is sufficient, there is, however, no need for supply of electric energy. The installation is, in this case, self-sustaining and the electric h~aters need only be used to start the operation of the installation. The start-up requirement is that the temperature to sufficiently high to ensure continuation of the reaction of destruction. Once the reaction has started, it generates by itself~the heat required *o maintain the te~perature level, provided the chemical energy from the reacting pollutants is sufficient.
When the energy emanating from the pollutant is lnsufficient to maintain the operational temperature in the bed at the required level, it is possible, instead of usIng the electric heaters, to mix addltional fuel into the air to be cleaned, in order to provide the required heat. For instance, natural gas or propane could be added to the polluted stream of alr. Also vaporized solvents are sometimes used. Often the prices of energy make it less expensive to add fuel than to resort to heating by - electricity.
The dimensions of the electric heating system in an electrically heated combustion exchanger generally are chosen to ensure that the installation can be operated at full air flow and maintain the operational temperature, also when the air temporarily contains no pollutants that generate energy~. In-other words, the installation should 35 ~be~able to function also with clean air.;One consequence - ~ ~ of;this is that the electric connections must be ; d1mensioned for considerable power requirements. However, , ,, ~ ~ ,, 2~1 PCT/SE92/00S74 212~-884 2 it is costly to have to provide for considerable power for the electrlc heaters with consequential large connected power, which means considerable costs, although the equipment perhaps is in use only very unfrequently. The use of equipment designed to supply extra~fuel ~to the strem of air to be cleaned may, under these circumstances, result in cost savings, since it becomes possible to reduce the electric power connections. This is prior-art technology and is used in many cases in con;unction with conventional combustion exchangers.
In a conventionally constructed, electrically heated combustion exchanger, the electric heaters are positioned in the hottest zone of the bed. In operation, the tem-perature is high in this zone (about 1000C), with con-sequential high demands on the corrosive resistance of thematerials of which the heaters are made. This is true whether the heat is supplied by electricity, by the pollutants or by the fuel added to the flow. The problem i8 identical when using other types of heaters than electrlc heaters.
By means of the invention defined in the following a combustion exchanger may be arranged in such a manner that any heaters lncorporated therein are spared long-term presence in high temperatures. One embodiment of the invention is illustrated in Fig. 1.
The incoming air to be cleaned enters through a conduit 1 and is supplied to an air-direction changing apparatus 2 in which the air is alternatingly directed upwards to an air distribution space 3 and downwards to 30i an air d~istribution space 4. F'rom there, the air passes through a combustlon bed 5 in which the chemical reaction takes place~ Via the a~r distribution space 4, alter-natingly the air distribution spoce 3, the air then returns to the air-direction changing apparatus 2 and flnally the cleaned air exits thorugh a condult 6. For the purpose of maintaining a hot zone in the middle of the bed 5 the direction of the air is changed at regular WO93/1238l 2 1 2 3 ~ 8 ~ PCT~SE92/00574 intervals, in accordance with the principle described in the US Patent Specification referred to in the afore-going. During normal operating condltions, heat losses are compensated for by the heat developed in the reaction process with the pollutants and/or with the fuels mixed wlth the air for this very purpose.
A higher temperature is, however, required initially in order to initiate the chemical reactions. The necessary starting temperature in the bed is achieved by means of one or several heaters 7 which are positioned vertically out of center, i.e. displaced from the central part of the bed, and which preferably are located at the upper part of the bed.
When the installation is to be started-up from cold conditions, the heaters 7 are activated. They are used to heat a layer in the bed up to a starting temperature which need not be as high as the normal operational temperature.
It is sufficient if the temperature level is such as to ensure tha* the mixture of pollutants/fuel and air starts to react during its passage through the layer and that the reaction progresses to a point where more heat is devel-oped inside the layer than is removed therefrom. The temperature inside the layer will therefore rise while the installation is in operation. When the correct start-up temperature levsl has been achleved by means of the heaters, the latter thus are stopped and by starting the supply of the air flow and the supp}y of pollutants/fuel, the temperature of the hottest layer will soon increase up to the normal operational temperature.
Because the path from the hot layer to the environ-ment is shorter towards the upper side of the bed than ~ towards the lower one, the layer will lose more heat ;~ upwards than downwards. Consequently, the heat has a tendency to move downwards and eventually it will be centered ln ~he bed.
;
WO93/12381 ~ PCT/SE92/~5?4 212388~ 4 By controlling the air-directing mechanism in such a manner that a larger volume of air passes downwards through the bed than upwards, this process may be accel-erated and become so rapld that the heaters, having starionary positions inside the bed, will never~be exposed to the normal worklng temperature. The simplest way to achieve thls is to allow the flow to pass upwards and downwards at intervals of mutually different lengths, but lt is likewise possible to keep the interval times of equal length but instead vary the flow volumes per time unit.
With our without such predetermined control the end result will be a centration of the hottest layer to the middle of the bed and the asymmetrically located heaters lS will constantly find themselves in a cooler part of the bed that ls positioned externally of the hottest layer.
From then on, the combustion exchanger will be run, when desired with extra fuel added to the flow, without the heaters ever being exposed to the high temperature of the hottest zone.
One consequence of this is that the heaters may be made from cheaper materials and that their serviceable life increases while at the same time they will need less servic$n~ and maintenance.
In accordance with the previous exemplary embodiment of the invention the heaters are positioned asymmetrically inside the bed in such a manner that they are closer to the upper face of the bed than to the lower one. This position facilitates servicing work on or replacement of the heatèrs, as lt eliminates the need of removing large quantities of material to make the heaters accessible. In principle, and within the scope of the invention, they could of course also or instead have been positioned in the lower part of the bed. Further, a vertical flow of air through the bed has been assumed above. Also in the case of a horizontal air flow the principle of the out-of-the-center position with respect of the heaters could, of ' course, be adopted~ In the latter case it should be understood that the bed arrangement is turned accordingly, whereby "upwards and downwards" are replaced by "left and right n .
The most common type of heaters in co~bustion-exchangers is electric heaters. The principle of asymmetrically positioned heaters as defined in the sub~ect invention is applicable also to other types of heaters, such as oil or gas fuelled heaters.
" ~ ~
~ 35 ,, .
:
- ~-
In the destruction of pollutants through combustion in a gas treatment installation of the type known as a S combustion exchanger (see US-A-4 741 690~ electric heaters are often used to malntain the correct operational temperature in the middle of the combustion bed. If the chemical energy developed in the form of heat during the destruction of the pollutants is sufficient, there is, however, no need for supply of electric energy. The installation is, in this case, self-sustaining and the electric h~aters need only be used to start the operation of the installation. The start-up requirement is that the temperature to sufficiently high to ensure continuation of the reaction of destruction. Once the reaction has started, it generates by itself~the heat required *o maintain the te~perature level, provided the chemical energy from the reacting pollutants is sufficient.
When the energy emanating from the pollutant is lnsufficient to maintain the operational temperature in the bed at the required level, it is possible, instead of usIng the electric heaters, to mix addltional fuel into the air to be cleaned, in order to provide the required heat. For instance, natural gas or propane could be added to the polluted stream of alr. Also vaporized solvents are sometimes used. Often the prices of energy make it less expensive to add fuel than to resort to heating by - electricity.
The dimensions of the electric heating system in an electrically heated combustion exchanger generally are chosen to ensure that the installation can be operated at full air flow and maintain the operational temperature, also when the air temporarily contains no pollutants that generate energy~. In-other words, the installation should 35 ~be~able to function also with clean air.;One consequence - ~ ~ of;this is that the electric connections must be ; d1mensioned for considerable power requirements. However, , ,, ~ ~ ,, 2~1 PCT/SE92/00S74 212~-884 2 it is costly to have to provide for considerable power for the electrlc heaters with consequential large connected power, which means considerable costs, although the equipment perhaps is in use only very unfrequently. The use of equipment designed to supply extra~fuel ~to the strem of air to be cleaned may, under these circumstances, result in cost savings, since it becomes possible to reduce the electric power connections. This is prior-art technology and is used in many cases in con;unction with conventional combustion exchangers.
In a conventionally constructed, electrically heated combustion exchanger, the electric heaters are positioned in the hottest zone of the bed. In operation, the tem-perature is high in this zone (about 1000C), with con-sequential high demands on the corrosive resistance of thematerials of which the heaters are made. This is true whether the heat is supplied by electricity, by the pollutants or by the fuel added to the flow. The problem i8 identical when using other types of heaters than electrlc heaters.
By means of the invention defined in the following a combustion exchanger may be arranged in such a manner that any heaters lncorporated therein are spared long-term presence in high temperatures. One embodiment of the invention is illustrated in Fig. 1.
The incoming air to be cleaned enters through a conduit 1 and is supplied to an air-direction changing apparatus 2 in which the air is alternatingly directed upwards to an air distribution space 3 and downwards to 30i an air d~istribution space 4. F'rom there, the air passes through a combustlon bed 5 in which the chemical reaction takes place~ Via the a~r distribution space 4, alter-natingly the air distribution spoce 3, the air then returns to the air-direction changing apparatus 2 and flnally the cleaned air exits thorugh a condult 6. For the purpose of maintaining a hot zone in the middle of the bed 5 the direction of the air is changed at regular WO93/1238l 2 1 2 3 ~ 8 ~ PCT~SE92/00574 intervals, in accordance with the principle described in the US Patent Specification referred to in the afore-going. During normal operating condltions, heat losses are compensated for by the heat developed in the reaction process with the pollutants and/or with the fuels mixed wlth the air for this very purpose.
A higher temperature is, however, required initially in order to initiate the chemical reactions. The necessary starting temperature in the bed is achieved by means of one or several heaters 7 which are positioned vertically out of center, i.e. displaced from the central part of the bed, and which preferably are located at the upper part of the bed.
When the installation is to be started-up from cold conditions, the heaters 7 are activated. They are used to heat a layer in the bed up to a starting temperature which need not be as high as the normal operational temperature.
It is sufficient if the temperature level is such as to ensure tha* the mixture of pollutants/fuel and air starts to react during its passage through the layer and that the reaction progresses to a point where more heat is devel-oped inside the layer than is removed therefrom. The temperature inside the layer will therefore rise while the installation is in operation. When the correct start-up temperature levsl has been achleved by means of the heaters, the latter thus are stopped and by starting the supply of the air flow and the supp}y of pollutants/fuel, the temperature of the hottest layer will soon increase up to the normal operational temperature.
Because the path from the hot layer to the environ-ment is shorter towards the upper side of the bed than ~ towards the lower one, the layer will lose more heat ;~ upwards than downwards. Consequently, the heat has a tendency to move downwards and eventually it will be centered ln ~he bed.
;
WO93/12381 ~ PCT/SE92/~5?4 212388~ 4 By controlling the air-directing mechanism in such a manner that a larger volume of air passes downwards through the bed than upwards, this process may be accel-erated and become so rapld that the heaters, having starionary positions inside the bed, will never~be exposed to the normal worklng temperature. The simplest way to achieve thls is to allow the flow to pass upwards and downwards at intervals of mutually different lengths, but lt is likewise possible to keep the interval times of equal length but instead vary the flow volumes per time unit.
With our without such predetermined control the end result will be a centration of the hottest layer to the middle of the bed and the asymmetrically located heaters lS will constantly find themselves in a cooler part of the bed that ls positioned externally of the hottest layer.
From then on, the combustion exchanger will be run, when desired with extra fuel added to the flow, without the heaters ever being exposed to the high temperature of the hottest zone.
One consequence of this is that the heaters may be made from cheaper materials and that their serviceable life increases while at the same time they will need less servic$n~ and maintenance.
In accordance with the previous exemplary embodiment of the invention the heaters are positioned asymmetrically inside the bed in such a manner that they are closer to the upper face of the bed than to the lower one. This position facilitates servicing work on or replacement of the heatèrs, as lt eliminates the need of removing large quantities of material to make the heaters accessible. In principle, and within the scope of the invention, they could of course also or instead have been positioned in the lower part of the bed. Further, a vertical flow of air through the bed has been assumed above. Also in the case of a horizontal air flow the principle of the out-of-the-center position with respect of the heaters could, of ' course, be adopted~ In the latter case it should be understood that the bed arrangement is turned accordingly, whereby "upwards and downwards" are replaced by "left and right n .
The most common type of heaters in co~bustion-exchangers is electric heaters. The principle of asymmetrically positioned heaters as defined in the sub~ect invention is applicable also to other types of heaters, such as oil or gas fuelled heaters.
" ~ ~
~ 35 ,, .
:
- ~-
Claims (3)
1. A gas treatment installation of the type known as a combustion exchanger, comprising a generative combustion bed in which one or several heaters are located for the purpose of heating the bed and initiating the chemical reaction, c h a r a c t e r i z e d in that the heaters for initiating the chemical reaction are positioned out of center in the bed, i.e. outside the central part of the bed.
2. A combustion exchanger as claimed in claim 1, c h a r a c t e r i z e d in that the heaters (7) are positioned in the upper part of the bed.
3. A combustion exchanger as claimed in claim 1, c h a r a c t e r i z e d in that it is provided with air-direction changing equipment designed to displace the hottest zone to the middle of the bed rapidly following start-up.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE9103786-1 | 1991-12-19 | ||
| SE9103786A SE9103786L (en) | 1991-12-19 | 1991-12-19 | GAS TREATMENT ESTABLISHMENT OF S K FURNITURE EXCHANGE TYPE |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2123884A1 true CA2123884A1 (en) | 1993-06-24 |
Family
ID=20384676
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2123884 Abandoned CA2123884A1 (en) | 1991-12-19 | 1992-08-24 | A gas treatment installation |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0616673B1 (en) |
| JP (1) | JP3217364B2 (en) |
| AU (1) | AU2697392A (en) |
| CA (1) | CA2123884A1 (en) |
| DE (1) | DE69217503T2 (en) |
| ES (1) | ES2097510T3 (en) |
| SE (1) | SE9103786L (en) |
| WO (1) | WO1993012381A1 (en) |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE441623B (en) * | 1984-06-21 | 1985-10-21 | Heed Bjoern | PROCEDURE AND DEVICE FOR COMBUSTION AND / OR DISTRIBUTION OF POLLUTANTS |
| SE463940B (en) * | 1989-06-28 | 1991-02-11 | Adtec Ab | GAS PURIFICATION DEVICES TO DIRECTLY CHANGE PREVENTION TO PREVENT POLLUTION GAS EMISSIONS |
-
1991
- 1991-12-19 SE SE9103786A patent/SE9103786L/en not_active IP Right Cessation
-
1992
- 1992-08-24 AU AU26973/92A patent/AU2697392A/en not_active Abandoned
- 1992-08-24 WO PCT/SE1992/000574 patent/WO1993012381A1/en active IP Right Grant
- 1992-08-24 ES ES93911644T patent/ES2097510T3/en not_active Expired - Lifetime
- 1992-08-24 EP EP93911644A patent/EP0616673B1/en not_active Expired - Lifetime
- 1992-08-24 DE DE69217503T patent/DE69217503T2/en not_active Expired - Lifetime
- 1992-08-24 CA CA 2123884 patent/CA2123884A1/en not_active Abandoned
- 1992-08-24 JP JP51082393A patent/JP3217364B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| DE69217503D1 (en) | 1997-03-27 |
| WO1993012381A1 (en) | 1993-06-24 |
| JPH07502106A (en) | 1995-03-02 |
| EP0616673B1 (en) | 1997-02-12 |
| EP0616673A1 (en) | 1994-09-28 |
| JP3217364B2 (en) | 2001-10-09 |
| DE69217503T2 (en) | 1997-07-03 |
| ES2097510T3 (en) | 1997-04-01 |
| AU2697392A (en) | 1993-07-19 |
| SE469293B (en) | 1993-06-14 |
| SE9103786L (en) | 1993-06-14 |
| SE9103786D0 (en) | 1991-12-19 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |