CA1303019C - Apparatus for the recuperative preheating of air fed to a lime shaft kiln or the like - Google Patents
Apparatus for the recuperative preheating of air fed to a lime shaft kiln or the likeInfo
- Publication number
- CA1303019C CA1303019C CA000527837A CA527837A CA1303019C CA 1303019 C CA1303019 C CA 1303019C CA 000527837 A CA000527837 A CA 000527837A CA 527837 A CA527837 A CA 527837A CA 1303019 C CA1303019 C CA 1303019C
- Authority
- CA
- Canada
- Prior art keywords
- chamber
- heat exchange
- recuperator
- preliminary
- gas
- 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.)
- Expired - Fee Related
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2/00—Lime, magnesia or dolomite
- C04B2/10—Preheating, burning calcining or cooling
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- F27B1/00—Shaft or like vertical or substantially vertical furnaces
- F27B1/02—Shaft or like vertical or substantially vertical furnaces with two or more shafts or chambers, e.g. multi-storey
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- F27B1/00—Shaft or like vertical or substantially vertical furnaces
- F27B1/10—Details, accessories, or equipment peculiar to furnaces of these types
- F27B1/22—Arrangements of heat-exchange apparatus
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Structural Engineering (AREA)
- Thermal Sciences (AREA)
- Materials Engineering (AREA)
- Physics & Mathematics (AREA)
- Organic Chemistry (AREA)
- Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
- Furnace Details (AREA)
- Air Supply (AREA)
- Drying Of Solid Materials (AREA)
- Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
- Coating Apparatus (AREA)
- Muffle Furnaces And Rotary Kilns (AREA)
Abstract
ABSTRACT
An apparatus for the recuperative preheating of cold air, more particularly fresh air, fed to a lime shaft kiln or the like, such as an annular or double inclined kiln, by trans-ferring heat from the air, more particularly the waste gas, heated in the lime shaft kiln, with a recuperator comprising a chamber, or the like, traversed by a plurality of heat exchange tubes, in which the hotter waste gas flows through the heat exchange tubes, while the cooler fresh air flows through the chamber surrounding them, in which a preliminary recuperator, having a chamber traversed by heat exchange tubes or the like, precedes a main recuperator comprising the heat exchange tubes traversed by the waste gas, the waste gas flowing through the chamber and the cold air flowing through the heat exchange tubes.
An apparatus for the recuperative preheating of cold air, more particularly fresh air, fed to a lime shaft kiln or the like, such as an annular or double inclined kiln, by trans-ferring heat from the air, more particularly the waste gas, heated in the lime shaft kiln, with a recuperator comprising a chamber, or the like, traversed by a plurality of heat exchange tubes, in which the hotter waste gas flows through the heat exchange tubes, while the cooler fresh air flows through the chamber surrounding them, in which a preliminary recuperator, having a chamber traversed by heat exchange tubes or the like, precedes a main recuperator comprising the heat exchange tubes traversed by the waste gas, the waste gas flowing through the chamber and the cold air flowing through the heat exchange tubes.
Description
This invention is concerned with an apparatus for the recuperative preheating of cold air, more especially fresh air fed to a lime shaft kiln or the like.
A lime shaft kiln may in particular comprise an annular or double inclined kiln which preheats cold air by transferring heat from the air, more particularly the waste gas, heated in the kiln, with a recuperator which comprises a chamber traversed by a plurality of heat exchange tubes, in which the hotter waste gas flows through the heat exchange tubes, while the cooler fresh air flows through the chamber surrounding them.
In the case of lime shaft kilns, more particularly annu1ar kilns or double inclined kilns, use is often made of recuperators of the type described hereinbefore, in which gas heated in the furnace shaft, usually waste gas, before being discharged into the atmosphere, and also before being recir-culated in the furnace process, flows through the group of heat exchange tubes in the recuperator, while the air, for example fresh air, which sweeps over the outer surface of the heat exchange tubes, and which is to be heated, is heated by transfer of the waste gas heat. In the case of annular shaft kilns and double inclined kilns, the heat releasing gas is waste gas while the heat absorbing gas is air which is required for calcining or for burning the fuel in the furnace shaft.
However, recuperators of the above mentioned kind, to which the invention relates, and the recuperator according to the invention, are also used in a more general sense in lime shaft .f ~
` .
~303019 kilns for other purposes, but it is always a matter of using heat from the heat releasing waste gas, flowing through the heat exchange tubes, to heat the heat absorbing gas sweeping the outer surface of the heat exchange tubes.
Recuperators of the above mentioned kind have been found completely satisfactory. There is, however, one problem, namely that the heat releasing gas flowing through the heat exchange tubes, referred to hereinafter as waste gas, contains more or less dust or the like, from the furnace process through which it has previously passed and, in the course of time, this dust is deposited upon the insides of the heat exchange tubes which are, of necessity, of relatively small cross-section.
Especially under the normal operating conditions obtaining in annular shaft kilns and double inclined kilns, for example, the presence of alkalis and/or other contaminants in the lime-stone to be calcined may cause difficulties in operating the known recuperator. The deposits formed in the heat exchange tubes are difficult or impossible to remove without damaging the heat exchange tubes. Heretofore, it has usually been necessary to clean the recuperator heat exchange tubes about every three or four weeks. This often resulted in destruction of the highly heat resistant tubes and these were no longer available for further heat transfer. If such frequent cleaning is omitted, the cleaning process becomes particularly time consuming and there is a greater risk of mechanical destruction of the tubes during the cleaning process. Postponement of the 13030i 9 necessary cleaning also leads to drastic impairment of efficient heat transfer in the recuperator.
Although attempts have already been made to reduce the above mentioned deposits in recuperator heat exchange tubes by lowering the temperature at which the waste gas enters the recuperator, this not only reduces the despoits, but also detracts from the efficiency of the furnace installation and frequently also fails to achieve any substantial increase in the life of the heat exchange tubes.
The present invention seeks to provide an apparatus of this type in such a manner as to reduce, or preferably com-pletely eliminate, the problems associated with the formation of coatings, or the deposit of solid waste gas components, or the like, in the heat exchange tubes.
In the case of an apparatus of the general type mentioned at the beginning hereof, this purpose is accomplished, according to the invention, in that a preliminary recuperator, having a chamber traversed by heat exchange tubes or the like, precedes a main recuperator, and in which in the preliminary recuperator the heat exchange tubes are traversed by the waste gas, the waste gas flowing through the chamber of the prelimi-nary recuperator and the cold air flowing through the heat exchange tubes of the preliminary recuperator.
- According to one particular configuration of the invention, the heat exchanging surface of the preliminary recuperator is smaller than the heat exchanging surface of the main recuperator.
i3~3~9 Provision may also be made for the ratio between the heat exchanging surface of the preliminary recuperator and that of the main recuperator to be approximately 1:4.
The invention furthermore proposes that the prelimi-nary recuperator comprise a device for cleaning, if necessary, deposits from the outer surface, swept by the waste gas, of the heat exchange tubes, and this may be accomplished in that the cleaning device operates automatically during adjustable time intervals.
According to another embodiment of the invention, the cleaning device comprises a pressure container, or the like, from which a gaseous cleaning fluid, such as air, may be intro-duced abruptly and at intervals, into the chamber of the preliminary recuperator.
According to the invention, provision may also be made for the pressure container to be topped up automatically with cleaning fluid under pressure.
The invention furthermore proposes that the chamber of the preliminary recuperator be provided with a gate, or the like, for the removal of deposits which have been cleaned off.
Finally, the gate device may be caused to operate automatically at adjustable time intervals.
The invention is based upon the surprising knowledge that, since the known recuperator is divided into a preliminary recuperator and a main recuperator, with the waste gases loaded with dust and alkalis flowing, in the preliminary recuperator, around the heat exchange tubes, but flowing in the main 13~30i9 recuperator, after leaving the preliminary recuperator, through the heat exchange tubes as heretofore, complete elimination of dust deposits in the heat exchange tubes is possible. It is only in the preliminary recuperator that dust deposits are formed, but these deposits are, of course, formed on the out-side of the heat exchange tubes, thus making easy and effective cleaning possible. Moreover, this cleaning may be carried out with no interruption of the furnace operation, with the greatest possible care of the heat exchange tubes and, preferably, com-pletely automatically, i.e. without the assistance of expensivepersonnel. Automatic cleaning of the group of heat exchange tubes in the preliminary recuperator is preferably carried out by means of a gaseous medium, for example, air which is expanded abruptly into the chamber surrounding the group of heat exchange tubes and which may be drawn from a storage container located externally on the housing of the preliminary recuperator. Dust cleaned out of the preliminary recuperator may be removed from the preferably provided gate device, through appropriate out-lets in the preliminary recuperator housing, by suitable conveying elements.
In accordance with another aspect of the invention, there is provided an installation comprising a lime shaft kiln and the apparatus of the invention, in which the kiln has outlet means for waste gas communicating with the chamber of the preliminary recuperator.
In accordance with another aspect of the invention, there is provided a method for the recupera-tive preheating of 1303~i9 cold gas employing the apparatus of the invention; thus in particular there is provided a method for the recuperative preheating of cold gas comprising feeding a hot waste first gas into a chamber of a preliminary recuperator in heat exchange relationship with a cold second gas fed through heat exchange tubes in said chamber, feeding the resulting cooled waste gas from said chamber through heat exchange tubes in a main recuperator in heat exchange relationship with the resulting heated second gas, and recovering the heated second gas.
Additional characteristics and advantages of the invention may be gathered from the following description in which an embodiment is explained in conjunction with the drawing showing a schematic representation attached hereto, and which shows a flow chart for a device according to the invention.
With further reference to the drawing, an apparatus of the invention comprises a preliminary recuperator 10 and a main recuperator 12. In the preliminary recuperator 10, which is traversed by heat exchange tubes (not shown), a waste gas inlet 14 carries heat-releasing waste gas into the chamber surrounding the heat exchange tubes in preliminary recuperator 10, while a cold air inlet 16 carries heat-absorbing gas, which is naturally free of dust and the like into the group of heat exchange tubes in the preliminary recuperator 10.
~ rom preliminary recuperator 10, a fresh air line 18, connected to the interior of the group of heat exchange tubes in preliminary recuperator 10, runs to main recuperator 12 and is in communication with a chamber of the main recuperator surround-ing the group of heat exchange tubes provided therein. A waste gas line 20 communicates, on the one hand, with the chamber surrounding the group of heat exchange tubes in the preliminary recuperator 10 and, on the other hand, with the interior of the group of heat exchange tubes in the main recuperator 12. Running from main recuperator 12 is a fresh air outlet 22 for the heated fresh air with which the chamber surrounding the group of heat exchange tubes in the main recuperator communicates, and a waste gas outlet 24 which is connected to the interior of the group of heat exchange tubes in the main recuperator 12. Connected to the housing of the preliminary recuperator 10 is a pressure con-tainer 26 which is adapted to be topped up automatically with air under pressure.
The apparatus described hereinbefore operates as follows.
Hot waste gas arriving from the furnace process passes, through waste gas inlet 14 into the chamber surround-ing the group of heat exchange tubes in preliminary recuperator10, where it releases a part of its heat to cold air which reaches the interior of the group of heat exchange tubes in the preliminary recuperator 10, and which flows through the heat exchange tubes, through cold air inlet 16. The waste gas then flows through waste gas line 20, finally reaching the interior of the group of heat exchange tubes in main recuperator . . .
, :,., - - , ~303019 12, where it releases its residual heat to the fresh air flowing through the main recuperator chamber 12 to which it is fed through fresh air line 18, the fresh air having already been preheated in the preliminary recuperator. The waste gas finally leaves recuperator 12 through waste gas outlet 24. The cold or fresh air, arriving through cold air inlet 16, flows through the interiors of the heat exchange tubes in the preliminary recuperator 10, passes thence, already preheated, through fresh air line 18, into the chamber of main recuperator 12 and, after final heating, leaves through fresh air outlet 22 in the main recuperator 12, whereupon it may be introduced into the furnace process in the desired form. A particular characteristic of the invention is that, in the course of the foregoing procedure, dust contained in the waste gas, and arriving through inlet 14, is deposited upon the outside of the heat exchange tubes in the preliminary recuperator 10, whence it may easily be discharged, automatically, through appropriate gate devices or the like, by abrupt, periodic expansion of the compressed air present in pressure container 26.
The advantage of the foregoing method of operation wherein, in a novel manner, a preliminary recuperator 10 precedes the main recuperator 12 and the waste gases in the preliminary recuperator 10 do no pass through the heat exchange tubes but around them, is that dust-like substances in the waste gas are deposited upon the outside of the group of heat exchange tubes in preliminary recuperator 10 and dust is no g longer deposited inside the sensitive heat exchange tubes in the main recuperator 12; that the dust-like substances, since they are deposited upon the outer surfaces of the heat exchange tubes in the preliminary recuperator 10, can generally be cleaned off simply with no danger of damaging the tubes; and, finally, that this cleaning may be effected automatically, as described hereinbefore, with the advantage that the recuperator installation need never be shut down for the purpose; whereas, in order to clean recuperators in which the heat releasing gases also flow within the heat exchange tubes, it has hither-to been necessary to shut the installation down for the clean-ing operation. This frequently took several hours, resulting in a drop in production and other drawbacks.
The characteristics of the invention disclosed in the foregoing specification, claims and drawing may be employed in the invention, in its various examples and embodiment, either individually or in any desired combination.
. .
A lime shaft kiln may in particular comprise an annular or double inclined kiln which preheats cold air by transferring heat from the air, more particularly the waste gas, heated in the kiln, with a recuperator which comprises a chamber traversed by a plurality of heat exchange tubes, in which the hotter waste gas flows through the heat exchange tubes, while the cooler fresh air flows through the chamber surrounding them.
In the case of lime shaft kilns, more particularly annu1ar kilns or double inclined kilns, use is often made of recuperators of the type described hereinbefore, in which gas heated in the furnace shaft, usually waste gas, before being discharged into the atmosphere, and also before being recir-culated in the furnace process, flows through the group of heat exchange tubes in the recuperator, while the air, for example fresh air, which sweeps over the outer surface of the heat exchange tubes, and which is to be heated, is heated by transfer of the waste gas heat. In the case of annular shaft kilns and double inclined kilns, the heat releasing gas is waste gas while the heat absorbing gas is air which is required for calcining or for burning the fuel in the furnace shaft.
However, recuperators of the above mentioned kind, to which the invention relates, and the recuperator according to the invention, are also used in a more general sense in lime shaft .f ~
` .
~303019 kilns for other purposes, but it is always a matter of using heat from the heat releasing waste gas, flowing through the heat exchange tubes, to heat the heat absorbing gas sweeping the outer surface of the heat exchange tubes.
Recuperators of the above mentioned kind have been found completely satisfactory. There is, however, one problem, namely that the heat releasing gas flowing through the heat exchange tubes, referred to hereinafter as waste gas, contains more or less dust or the like, from the furnace process through which it has previously passed and, in the course of time, this dust is deposited upon the insides of the heat exchange tubes which are, of necessity, of relatively small cross-section.
Especially under the normal operating conditions obtaining in annular shaft kilns and double inclined kilns, for example, the presence of alkalis and/or other contaminants in the lime-stone to be calcined may cause difficulties in operating the known recuperator. The deposits formed in the heat exchange tubes are difficult or impossible to remove without damaging the heat exchange tubes. Heretofore, it has usually been necessary to clean the recuperator heat exchange tubes about every three or four weeks. This often resulted in destruction of the highly heat resistant tubes and these were no longer available for further heat transfer. If such frequent cleaning is omitted, the cleaning process becomes particularly time consuming and there is a greater risk of mechanical destruction of the tubes during the cleaning process. Postponement of the 13030i 9 necessary cleaning also leads to drastic impairment of efficient heat transfer in the recuperator.
Although attempts have already been made to reduce the above mentioned deposits in recuperator heat exchange tubes by lowering the temperature at which the waste gas enters the recuperator, this not only reduces the despoits, but also detracts from the efficiency of the furnace installation and frequently also fails to achieve any substantial increase in the life of the heat exchange tubes.
The present invention seeks to provide an apparatus of this type in such a manner as to reduce, or preferably com-pletely eliminate, the problems associated with the formation of coatings, or the deposit of solid waste gas components, or the like, in the heat exchange tubes.
In the case of an apparatus of the general type mentioned at the beginning hereof, this purpose is accomplished, according to the invention, in that a preliminary recuperator, having a chamber traversed by heat exchange tubes or the like, precedes a main recuperator, and in which in the preliminary recuperator the heat exchange tubes are traversed by the waste gas, the waste gas flowing through the chamber of the prelimi-nary recuperator and the cold air flowing through the heat exchange tubes of the preliminary recuperator.
- According to one particular configuration of the invention, the heat exchanging surface of the preliminary recuperator is smaller than the heat exchanging surface of the main recuperator.
i3~3~9 Provision may also be made for the ratio between the heat exchanging surface of the preliminary recuperator and that of the main recuperator to be approximately 1:4.
The invention furthermore proposes that the prelimi-nary recuperator comprise a device for cleaning, if necessary, deposits from the outer surface, swept by the waste gas, of the heat exchange tubes, and this may be accomplished in that the cleaning device operates automatically during adjustable time intervals.
According to another embodiment of the invention, the cleaning device comprises a pressure container, or the like, from which a gaseous cleaning fluid, such as air, may be intro-duced abruptly and at intervals, into the chamber of the preliminary recuperator.
According to the invention, provision may also be made for the pressure container to be topped up automatically with cleaning fluid under pressure.
The invention furthermore proposes that the chamber of the preliminary recuperator be provided with a gate, or the like, for the removal of deposits which have been cleaned off.
Finally, the gate device may be caused to operate automatically at adjustable time intervals.
The invention is based upon the surprising knowledge that, since the known recuperator is divided into a preliminary recuperator and a main recuperator, with the waste gases loaded with dust and alkalis flowing, in the preliminary recuperator, around the heat exchange tubes, but flowing in the main 13~30i9 recuperator, after leaving the preliminary recuperator, through the heat exchange tubes as heretofore, complete elimination of dust deposits in the heat exchange tubes is possible. It is only in the preliminary recuperator that dust deposits are formed, but these deposits are, of course, formed on the out-side of the heat exchange tubes, thus making easy and effective cleaning possible. Moreover, this cleaning may be carried out with no interruption of the furnace operation, with the greatest possible care of the heat exchange tubes and, preferably, com-pletely automatically, i.e. without the assistance of expensivepersonnel. Automatic cleaning of the group of heat exchange tubes in the preliminary recuperator is preferably carried out by means of a gaseous medium, for example, air which is expanded abruptly into the chamber surrounding the group of heat exchange tubes and which may be drawn from a storage container located externally on the housing of the preliminary recuperator. Dust cleaned out of the preliminary recuperator may be removed from the preferably provided gate device, through appropriate out-lets in the preliminary recuperator housing, by suitable conveying elements.
In accordance with another aspect of the invention, there is provided an installation comprising a lime shaft kiln and the apparatus of the invention, in which the kiln has outlet means for waste gas communicating with the chamber of the preliminary recuperator.
In accordance with another aspect of the invention, there is provided a method for the recupera-tive preheating of 1303~i9 cold gas employing the apparatus of the invention; thus in particular there is provided a method for the recuperative preheating of cold gas comprising feeding a hot waste first gas into a chamber of a preliminary recuperator in heat exchange relationship with a cold second gas fed through heat exchange tubes in said chamber, feeding the resulting cooled waste gas from said chamber through heat exchange tubes in a main recuperator in heat exchange relationship with the resulting heated second gas, and recovering the heated second gas.
Additional characteristics and advantages of the invention may be gathered from the following description in which an embodiment is explained in conjunction with the drawing showing a schematic representation attached hereto, and which shows a flow chart for a device according to the invention.
With further reference to the drawing, an apparatus of the invention comprises a preliminary recuperator 10 and a main recuperator 12. In the preliminary recuperator 10, which is traversed by heat exchange tubes (not shown), a waste gas inlet 14 carries heat-releasing waste gas into the chamber surrounding the heat exchange tubes in preliminary recuperator 10, while a cold air inlet 16 carries heat-absorbing gas, which is naturally free of dust and the like into the group of heat exchange tubes in the preliminary recuperator 10.
~ rom preliminary recuperator 10, a fresh air line 18, connected to the interior of the group of heat exchange tubes in preliminary recuperator 10, runs to main recuperator 12 and is in communication with a chamber of the main recuperator surround-ing the group of heat exchange tubes provided therein. A waste gas line 20 communicates, on the one hand, with the chamber surrounding the group of heat exchange tubes in the preliminary recuperator 10 and, on the other hand, with the interior of the group of heat exchange tubes in the main recuperator 12. Running from main recuperator 12 is a fresh air outlet 22 for the heated fresh air with which the chamber surrounding the group of heat exchange tubes in the main recuperator communicates, and a waste gas outlet 24 which is connected to the interior of the group of heat exchange tubes in the main recuperator 12. Connected to the housing of the preliminary recuperator 10 is a pressure con-tainer 26 which is adapted to be topped up automatically with air under pressure.
The apparatus described hereinbefore operates as follows.
Hot waste gas arriving from the furnace process passes, through waste gas inlet 14 into the chamber surround-ing the group of heat exchange tubes in preliminary recuperator10, where it releases a part of its heat to cold air which reaches the interior of the group of heat exchange tubes in the preliminary recuperator 10, and which flows through the heat exchange tubes, through cold air inlet 16. The waste gas then flows through waste gas line 20, finally reaching the interior of the group of heat exchange tubes in main recuperator . . .
, :,., - - , ~303019 12, where it releases its residual heat to the fresh air flowing through the main recuperator chamber 12 to which it is fed through fresh air line 18, the fresh air having already been preheated in the preliminary recuperator. The waste gas finally leaves recuperator 12 through waste gas outlet 24. The cold or fresh air, arriving through cold air inlet 16, flows through the interiors of the heat exchange tubes in the preliminary recuperator 10, passes thence, already preheated, through fresh air line 18, into the chamber of main recuperator 12 and, after final heating, leaves through fresh air outlet 22 in the main recuperator 12, whereupon it may be introduced into the furnace process in the desired form. A particular characteristic of the invention is that, in the course of the foregoing procedure, dust contained in the waste gas, and arriving through inlet 14, is deposited upon the outside of the heat exchange tubes in the preliminary recuperator 10, whence it may easily be discharged, automatically, through appropriate gate devices or the like, by abrupt, periodic expansion of the compressed air present in pressure container 26.
The advantage of the foregoing method of operation wherein, in a novel manner, a preliminary recuperator 10 precedes the main recuperator 12 and the waste gases in the preliminary recuperator 10 do no pass through the heat exchange tubes but around them, is that dust-like substances in the waste gas are deposited upon the outside of the group of heat exchange tubes in preliminary recuperator 10 and dust is no g longer deposited inside the sensitive heat exchange tubes in the main recuperator 12; that the dust-like substances, since they are deposited upon the outer surfaces of the heat exchange tubes in the preliminary recuperator 10, can generally be cleaned off simply with no danger of damaging the tubes; and, finally, that this cleaning may be effected automatically, as described hereinbefore, with the advantage that the recuperator installation need never be shut down for the purpose; whereas, in order to clean recuperators in which the heat releasing gases also flow within the heat exchange tubes, it has hither-to been necessary to shut the installation down for the clean-ing operation. This frequently took several hours, resulting in a drop in production and other drawbacks.
The characteristics of the invention disclosed in the foregoing specification, claims and drawing may be employed in the invention, in its various examples and embodiment, either individually or in any desired combination.
. .
Claims (21)
1 An apparatus for the recuperative preheating of cold air comprising:
a main recuperator comprising a main chamber traversed by a plurality of main heat exchange tubes, in which hotter waste gas flows through said main tubes and cooler gas flows through said main chamber surrounding said tubes, and a preliminary recuperator comprising a preliminary chamber traversed by a plurality of preliminary heat exchange tubes, preceding said main recuperator in which the hotter waste gas flows through said preliminary chamber and the cooler gas flows through said preliminary tubes.
a main recuperator comprising a main chamber traversed by a plurality of main heat exchange tubes, in which hotter waste gas flows through said main tubes and cooler gas flows through said main chamber surrounding said tubes, and a preliminary recuperator comprising a preliminary chamber traversed by a plurality of preliminary heat exchange tubes, preceding said main recuperator in which the hotter waste gas flows through said preliminary chamber and the cooler gas flows through said preliminary tubes.
2. An apparatus according to claim 1, wherein a heat exchanging surface of the preliminary recuperator is smaller than a heat exchanging surface of the main recuperator.
3. An apparatus according to claim 2, wherein the ratio between said heat exchanging surface of the preliminary recuperator and that of the main recuperator is about 1:4.
4. An apparatus according to claim 1, further including a device for cleaning deposits from an outer surface, swept by the waste gas, of the preliminary heat exchange tubes.
5. An apparatus according to claim 4, wherein the clean-ing device operates automatically during adjustable time intervals.
6. An apparatus according to claim 4, wherein the clean-ing device comprises a pressure container from which a gaseous cleaning fluid may be introduced abruptly and at intervals into said preliminary chamber.
7. An apparatus according to claim 5, wherein the clean-ing device comprises a pressure container from which a gaseous cleaning fluid may be introduced abruptly and at intervals into said preliminary chamber.
8. An apparatus according to claim 6 or 7, wherein the pressure container may be topped up, under automatic control, with cleaning fluid under pressure.
9. An apparatus according to claim 4, 5 or 6, wherein said preliminary chamber is provided with a gate for the removal of cleaned off deposits.
10. An apparatus according to claim 4, 5 or 6, wherein said preliminary chamber is provided with a gate device for removal of cleaned off deposits which operates automatically at adjustable time intervals.
11. An apparatus for the recuperative preheating of cold gas comprising:
a preliminary recuperator having first heat exchange members surrounded by a first chamber, a main recuperator having second heat exchange members surrounded by a second chamber, means for gas flow communication of said first heat exchange members with said second chamber, and means for gas flow communication of said first chamber and said second heat exchange members.
a preliminary recuperator having first heat exchange members surrounded by a first chamber, a main recuperator having second heat exchange members surrounded by a second chamber, means for gas flow communication of said first heat exchange members with said second chamber, and means for gas flow communication of said first chamber and said second heat exchange members.
12. An apparatus according to claim 11, including first inlet means for communicating said first chamber with a hot waste gas, and second inlet means for communicating said first heat exchange members with a cold gas.
13. An apparatus according to claim 11 or 12, wherein said first and second members are tubular members.
14. An apparatus for the recuperative preheating of cold air comprising:
a preliminary recuperator having a first chamber traversed by first heat exchange members therein, first inlet means for communicating said first chamber with a first hot waste gas, second inlet means for communicating an interior of said first heat exchange members with a second cooler gas, a main recuperator having a second chamber traversed by second heat exchange members therein, first communication means communicating said second chamber with said interior or said first heat exchange members for flow of the second gas from said first exchange members to said second chamber, and second communication means communicating an interior of said second heat exchange members with said first chamber for flow of the first gas from said first chamber to said second heat exchange members.
a preliminary recuperator having a first chamber traversed by first heat exchange members therein, first inlet means for communicating said first chamber with a first hot waste gas, second inlet means for communicating an interior of said first heat exchange members with a second cooler gas, a main recuperator having a second chamber traversed by second heat exchange members therein, first communication means communicating said second chamber with said interior or said first heat exchange members for flow of the second gas from said first exchange members to said second chamber, and second communication means communicating an interior of said second heat exchange members with said first chamber for flow of the first gas from said first chamber to said second heat exchange members.
15. An installation comprising a lime shaft kiln and an apparatus as defined in claim 1, said kiln having outlet means for hot waste gas communicating with said preliminary chamber.
16. An installation comprising a lime shaft kiln and an apparatus as defined in claim 11, said kiln having outlet means for hot waste gas communicating with said first chamber.
17. An installation comprising a lime shaft kiln and an apparatus as defined in claim 14, said kiln having outlet means for hot gas with said first inlet means.
18. A method for the recuperative preheating of cold gas comprising:
feeding a hot waste first gas into a chamber of a preliminary recuperator in heat exchange relationship with a cold second gas fed through heat exchange tubes in said chamber, feeding the resulting cooled waste gas from said chamber through heat exchange tubes in a main recuperator in heat exchange relationship with the resulting heated second gas, and recovering the heated second gas.
feeding a hot waste first gas into a chamber of a preliminary recuperator in heat exchange relationship with a cold second gas fed through heat exchange tubes in said chamber, feeding the resulting cooled waste gas from said chamber through heat exchange tubes in a main recuperator in heat exchange relationship with the resulting heated second gas, and recovering the heated second gas.
19. A method according to claim 18, wherein said hot waste gas is fed to said preliminary recuperator from a lime kiln shaft.
20. A method according to claim 19, wherein the recovered heated second gas is cycled to said lime kiln shaft.
21. A method according to claim 18, 19 or 20, including a step of removing deposits from exterior surfaces of said heat exchange tubes in said preliminary recuperator.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19863601572 DE3601572A1 (en) | 1986-01-21 | 1986-01-21 | DEVICE FOR RECUPERATIVE PREHEATING FROM A LIMEWELL OVEN OR THE LIKE SUPPLIED AIR |
| DEP3601572.5 | 1986-01-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1303019C true CA1303019C (en) | 1992-06-09 |
Family
ID=6292242
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000527837A Expired - Fee Related CA1303019C (en) | 1986-01-21 | 1987-01-21 | Apparatus for the recuperative preheating of air fed to a lime shaft kiln or the like |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0233462B1 (en) |
| CN (1) | CN1021365C (en) |
| AT (1) | ATE63159T1 (en) |
| CA (1) | CA1303019C (en) |
| DE (2) | DE3601572A1 (en) |
| ES (1) | ES2023123B3 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6261092B1 (en) * | 2000-05-17 | 2001-07-17 | Megtec Systems, Inc. | Switching valve |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2538701A (en) * | 1945-06-21 | 1951-01-16 | Bbc Brown Boveri & Cie | Gas turbine plant heat exchanger cleaning apparatus |
| DE1014916B (en) * | 1953-01-08 | 1957-08-29 | Rheinische Kalksteinwerke | Process for burning limestone, dolomite or magnesite in a gas-fired shaft furnace with exhaust gas circulation |
| FR1246618A (en) * | 1959-02-16 | 1960-11-18 | Air Preheater | continuous recovery heat exchanger for hearth or crucible furnaces |
| FR1440786A (en) * | 1965-04-21 | 1966-06-03 | Sofim Saar Saarofenbau Fuer In | Method for firing limestone and device for carrying out this process |
| US3702242A (en) * | 1971-07-21 | 1972-11-07 | Combustion Eng | Downdraft cupola incorporating means to preheat the charge |
| CH637760A5 (en) * | 1978-09-15 | 1983-08-15 | Maerz Ofenbau | Method for burning mineral, carbonate-containing raw materials in the co-current regenerative shaft furnace |
| FR2470942A1 (en) * | 1979-11-30 | 1981-06-12 | Setrem | PROCESS AND DEVICE FOR RECOVERING HEAT FROM OVEN FUMES, ESPECIALLY GLASS OVENS |
-
1986
- 1986-01-21 DE DE19863601572 patent/DE3601572A1/en active Granted
-
1987
- 1987-01-13 DE DE8787100300T patent/DE3769666D1/en not_active Expired - Fee Related
- 1987-01-13 AT AT87100300T patent/ATE63159T1/en not_active IP Right Cessation
- 1987-01-13 ES ES87100300T patent/ES2023123B3/en not_active Expired - Lifetime
- 1987-01-13 EP EP87100300A patent/EP0233462B1/en not_active Expired - Lifetime
- 1987-01-21 CN CN87100817A patent/CN1021365C/en not_active Expired - Fee Related
- 1987-01-21 CA CA000527837A patent/CA1303019C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| EP0233462A3 (en) | 1988-04-13 |
| CN1021365C (en) | 1993-06-23 |
| CN87100817A (en) | 1987-09-23 |
| ATE63159T1 (en) | 1991-05-15 |
| ES2023123B3 (en) | 1992-01-01 |
| DE3769666D1 (en) | 1991-06-06 |
| EP0233462B1 (en) | 1991-05-02 |
| DE3601572A1 (en) | 1987-08-06 |
| DE3601572C2 (en) | 1989-06-01 |
| EP0233462A2 (en) | 1987-08-26 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |