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Title:
DEVICE FOR PURIFYING FUMES
Document Type and Number:
WIPO Patent Application WO/1987/007357
Kind Code:
A1
Abstract:
A device for purifying fumes from for instance a refuse disposal furnace comprises a separation unit (4) inserted in a fume channel (2) where the fumes via deflecting means (12) may touch a separation surface (5) of the separation surface. The separation unit (4) is percolated by an LNG gas cooled down to a temperature of preferably -140�C and coming from a container (8) such as a cooling ship. When the gas in the separation unit cooled down to liquid state, comes in contact with the fumes which preferably are cooled by means of a heat exchanger (3) provided in the fume channel it will again come into the gaseous state and part of the combustible gas is fed to the furnace (1) by means of a conduit (11) while another part thereof may be tapped for driving a gas engine or for distribution to consumers. In the contact between the fumes and the separation surface a deposit of harmful constituents takes place and due to the inclined position of the surface (5) and the polished surface thereof the deposits will fall down into an ash bin (17).

Inventors:
HAEGGSTROEM GUNNAR (SE)
Application Number:
PCT/SE1987/000258
Publication Date:
December 03, 1987
Filing Date:
May 25, 1987
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
HAEGGSTROEM GUNNAR (SE)
International Classes:
F23J15/06; F23K5/22; F23M9/00; (IPC1-7): F23J15/00
Foreign References:
US4227647A1980-10-14
DE3424927A11986-02-06
FR2219717A51974-09-20
US2864439A1958-12-16
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Claims:
CLAIMS
1. Device for purifying fumes, c h a r a c t e r i z e d in that it comprises a hollow separation unit (4) provided in a fume channel (2) and having a cooling surface (5) made from heat conducting material and being so located in the fume channel that the fumes at their passage therethrough are forced to follow said cooling surface, that through said separation unit is transported a combustible gas which is so strongly cooled down preferably to at least 100° C that there wi 1 be deposited upon said cooling surface solid deposits of constituents in the fume when said fumes come in contact with said cooling surface and that arrangements are made to continuously remove said deposits.
2. Device according to claim ^ c h a r a c t e r i z e d in that in the fume channel (2) in front of the separation unit (4) there is arranged a heat exchanger (3) for recovering part of the heat content in the fumes and as a consequence thereof a reduction of the heat con¬ tent of the fumes.
3. Device according to claim 1, c h a r a c t e r i z e d in that the separation unit (4) comprises a substantially boxshaped unit which is obliquely placed in the fume channel (2) in such a manner that the separation surface (5) thereof will be touched by the fumes when they are passing through the fume channel and that the deposits on said separation surface to a big extent will fall down into a collecting container (17) located beneath the separation surface.
4. Device according to claims 13 inclusive, c h a r a c t e r i z e d in that it has deflection means (12) by means of which the fume stream will be forced to touch the separation surface (4) of the separation unit (4) during its passage through the fume channel and then continue towards a chimney possibly via one or several further separation units (4).
5. Device according to claim 1, c h a r a c t e r i z e d in that the separation unit (4) has an insulating wall (6) remote to the separation surface (5) .
6. Device according to claim 1, c h a r a c t e r i z e d in that the conduit (7) leading to the separation unit (4) and/or the conduit (9) which leads from said separation unit has branches for tapping of cooled or readytouse combustible gas.
7. Device according to claim 1, c h a r a c t e r i z e d in that con¬ trol means are provided for leading to a furnace (1) such an amount of combustible gas received from the separation unit (4) that an optimum combustion as regards to effect and/or purity is obtained.
Description:
The present invention refers to a device for purifying fumes. As will appear from the following the invention preferably may be realized in connection with an eneregy plant where this expression has to be given a very wide interpretation since it may include so different things as electric power stations, stockyards for ready-to-use combustible gas, refuse disposal units and the like as well as combinations thereof. Primarily but not exclusively a combined plant comprising a stockyard for combustible gas and a combustion plant is intended.

The primary object of the invention is to provide a plant which is forbearing to the environment, i.e. a plant which to the environment delivers a minimum of harmful substances. Another object has been to provide a plant which combines simplicity in construction and attendance with a favourable operating economy.

To accomplish these and further objects the invention has the charac¬ teristics according to the claims.

The accompanying drawing illustrates an exemplary embodiment of the invention in which the drawing figure schematically shows a refuse disposal unit in con- for ity with the invention.

The illustrated plant includes a refuse disposal furnace, generally denoted 1, from which the fumes escape through a fume channel 2. In said channel there is in a manner known per se arranged a heat ex¬ changer 3 to utilize part of the heat content of the fumes and to diminish the fume temperature. Provided in the fume channel is further a separation unit, generally designated k , which in the illustrated embodiment consists of an obliquely arranged substantially box-shaped unit with a relatively thin walled separation surface 5, preferably made from a material with good heat conducting properties. The separa- tion surface preferably has an even and plane, probably polished sur¬ face.

The wall 6 of the separation unit which is remote from the separation surface 5 is in contradistinction to the separation surface 5 made insulating. The separation unit is further closed upwardly and down-

wardly. The separation unit is provided to continually transport a cooled combustible gas and has for this purpose a feed conduit 7 leading to a container 8 for such cooled gas. The container in question consists in the example of a container barge, containing LNG gas originally cooled down to a temperature of -160° C. At such a temperature the LNG gas is in a liquid state and it is known to store and transport such gas in special cooling ships. In practice the temperature inside the separation unit will be 1 0 C.

From the separation unit further extends an outlet conduit 9 which leads to a blowing fan 10 and from this blower fan a conduit 11 leads to the refuse disposal furnace 1. From the conduit 7 a -not shown- conduit can extend and through said conduit part of the cooled gas flowing through the conduit 7 can be transported to a stock for di¬ stribution of liquid LNG-gas and from the conduit 9 there may in the same manner be branched a conduit by means of which part of the LNG gas now in a gaseous state is transported to a stock for distribution of ready-to-use combustible gas. In order to control the flow there are of course arranged valves, sensors and similar control means which as being known to its construction as well as to the function will - not be described more in detail.

In the fume channel 2 there is further provided a deflection plate 12, which as appears from the drawing has for its purpose to impart to the fumes flowing through the fume channel a movement which forces them to follow the separation surface from the top to the bottom and then change direction and escape in the direction of the arrow through the slot which is provided between the upper part of the separation unit k and the deflection plate 12 respectively the upper wall of the fume channel 2. After the separation unit an electrostatic filter 1 or the like may be arranged for removal of such impurities which have not already been removed by the separation unit.

The fume channel leads to a chimney 15. The fume channel continues near to the separation unit in a funnel-shaped ash bin 16, below which a container 17 for receiving the waste separated by the separating unit may be introduced.

The plant now described functions - as mentioned - in such a manner that

cooling medium preferably continuously flows through the separation unit. When the relatively hot fumes flow along the strongly cooled down separa¬ tion surface 5 a crystal linic deposit of primarily heavy metals but also other stuffs harmful to the environment occurs which means that the fume which continues to flow towards the electrostatic filter 14 has lost a major part of its harmful constituents. At the same time the cooling medium flowing through the separation unit has changed its state of aggregate from liquid to gaseous state and it is obvious that this means that one has achieved the double effect of bringing the cooling medium to the state in which it is used and of carrying out an effective cleaning of the smoke. By using part of the gas so obtained in the refuse disposal furnace be introducing a quantity of said gas in the furnace via the blower fan 10 and the conduit 11 a more effective combustion is obtained which in turn leads to an effec- tive reduction of the harm of the fumes. Since it further -as mentioned- is possible to tap cooled gas as well as ready-to-use gas an extremely useful plant is achieved in which cheap fuels may be used for produc¬ tion of heat or power and where natural gas can be delivered to various consumers.

Owing to the inclination of the separation unit and the surface struc¬ ture of the separation surface 5 the deposits on the latter will to the major part fall down into the waste container through the ash bin 16 but it is of course also possible to provide the separation unit with means to continuously or in pulses draw off such deposits which have not got loose automatically. Such a means may comprise a scraper but also of a current fed loop filament which may be operated in pulses and provided in the separation surface.

Instead of letting the fume stream turn to pass through an upper slot it is of course possible to have it to pass a lower slot and it may in cer- tain circumstances be suitable to arrange two or more separation units behind each other in the fume channel in which case the latter may have deflection means acting to direct the fume stream in such paths through the fume channel that optimal effects a re achieved.

A plant of the general design shown and described is useful in coal and oil power stations but also in for instance steel works, aluminum works and the like where the amount of harmful stuffs often is high. It is of importance that the cleaning obtained according to the invention has been obtained by means of a dry method. The ash obtained by this method

may often be used as a component in asphalt bricks or the like in which the harmful stuffs will be encapsuled. It is also advantageous to use the gas in a separate plant such as a gas motor of the type TOTEM which has an efficiency 0 f up to 92, and where electricity may be obtained and at the same time a 90° hot water from the cooling system of the motor or from a heat exchanger in the fume channel.

In order to obtain the intended separation the gas should be cooled down to at least -100°C and preferably when natural gas is concerned to -140°C.

Injection of lime powder may preferably take place near to the ash bin.




 
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