CN216307795U - Flue gas recirculation system - Google Patents
Flue gas recirculation system Download PDFInfo
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- CN216307795U CN216307795U CN202121876355.9U CN202121876355U CN216307795U CN 216307795 U CN216307795 U CN 216307795U CN 202121876355 U CN202121876355 U CN 202121876355U CN 216307795 U CN216307795 U CN 216307795U
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- flue gas
- recirculation system
- gas recirculation
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Abstract
The utility model provides a flue gas recirculation system which comprises a rotary kiln, a fixed end, a secondary combustion chamber, an induced draft fan and a chimney which are sequentially connected, wherein the flue gas recirculation system also comprises a secondary fan and a circulating fan, the secondary fan is used for supplying oxygen for flue gas incineration, and the circulating fan is used for extracting part of flue gas of the induced draft fan, mixing the flue gas with secondary air after the secondary fan and spraying the mixed flue gas into the fixed end so as to reduce the generation of nitrogen oxides and improve the uniformity of the temperature of the flue gas. The flue gas recirculation system is low in operation cost, the rotary kiln incineration system can effectively reduce the emission of nitrogen oxides in flue gas in the operation process, the high-temperature coking problem at the fixed end of the incineration system can be relieved, the operation cost of the system is effectively reduced, and the stability of the system is improved.
Description
Technical Field
The utility model relates to a flue gas treatment technology, in particular to a flue gas recirculation system.
Background
With the development of national industrialization, the yield of hazardous wastes is increased day by day, and the main disposal mode of the hazardous wastes is incineration disposal at present. Because the hazardous waste is various in types and complex in properties, and the nitrogen content in part of hazardous waste is high, the concentration of nitrogen oxides in the flue gas is high, and simultaneously, the requirement of 1100 ℃ and 2s is required for the incineration flue gas of the hazardous waste required by national standards, so that more nitrogen oxides are generated in the flue gas. At present, modes for reducing nitrogen oxides in smoke in dangerous waste incineration systems comprise SNCR, PNCR, SCR and the like, and most dangerous waste incineration plants use the SNCR mode to reduce the emission of the nitrogen oxides in the smoke due to the fact that the PNCR and the SCR are high in use cost. However, with the increasing regulatory pressure of environmental protection departments, the emission standard becomes tighter and tighter, and it is difficult to achieve the environmental protection requirement by reducing the emission of nitrogen oxides in the flue gas only in the SCNR manner.
The related art provides a flue gas recirculation system which injects flue gas from a secondary air port into the system by extracting part of the outlet flue gas of a draught fan. However, the flue gas recirculation system is only suitable for the waste incineration system, mainly aiming at reducing the emission of nitrogen oxides in the flue gas of the waste incineration system, and the flue gas injection position is related to the incinerator, so the flue gas recirculation system cannot be suitable for the counter-flow rotary kiln incineration system in the hazardous waste incineration system.
Therefore, there is a need to provide a flue gas recirculation system that solves at least the above-mentioned problems of the prior art.
SUMMERY OF THE UTILITY MODEL
In order to solve at least one of the above problems, according to an aspect of the present invention, there is provided a flue gas recirculation system including a rotary kiln, a fixed end, a secondary combustion chamber, an induced draft fan, and a chimney, which are connected in sequence, wherein: the rotary kiln is used for burning hazardous wastes; the fixed end is used for connecting the rotary kiln and the secondary combustion chamber; the secondary combustion chamber is used for burning flue gas; the induced draft fan is used for maintaining the negative pressure of the flue gas recirculation system; the chimney is used for discharging flue gas, and, flue gas recirculation system still includes secondary air fan and circulating fan, secondary air fan is used for burning the flue gas and carries out the oxygen suppliment, circulating fan is used for extracting the part the flue gas of draught fan makes it with secondary air after the secondary air fan mixes the back and spouts the stiff end to reduce nitrogen oxide's formation and improve flue gas temperature's homogeneity
In some embodiments, the rotary kiln is a counter-flow rotary kiln.
In some embodiments, the flue gas recirculation system further comprises a waste heat boiler connected to the outlet of the secondary combustion chamber for recovering the heat energy of the flue gas.
In some embodiments, the flue gas recirculation system further comprises a quench tower connected to the outlet of the waste heat boiler for reducing the flue gas temperature to avoid regeneration of dioxins.
In some embodiments, the flue gas recirculation system further comprises a bag-type dust collector connected to the outlet of the quench tower for capturing particulate matter in the flue gas.
In some embodiments, the flue gas recirculation system further comprises a wet tower connected between the outlet of the bag-type dust collector and the induced draft fan for desulfurization.
The flue gas recirculation system provided by the utility model has low operation cost, can effectively reduce the emission of nitrogen oxides in flue gas in the operation process of a rotary kiln incineration system, can relieve the high-temperature coking problem at the fixed end of the incineration system, effectively reduces the operation cost of the system and improves the stability of the system.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail embodiments of the present invention with reference to the attached drawings. The accompanying drawings are included to provide a further understanding of the embodiments of the utility model and are incorporated in and constitute a part of this specification, illustrate embodiments of the utility model and together with the description serve to explain the principles of the utility model and not to limit the utility model. In the drawings, like reference numbers generally represent like parts or steps.
FIG. 1 shows a schematic view of a flue gas recirculation system according to an embodiment of the utility model.
The reference numerals in fig. 1 are explained as follows:
1 Rotary kiln
2 fixed end
3 Secondary fan
4 second combustion chamber
5 waste heat boiler
6 quench tower
7 bag dust collector
8 wet tower
9 induced draft fan
10 chimney
11 circulating fan
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, exemplary embodiments according to the present invention will be described in detail below with reference to the accompanying drawings. It is to be understood that the described embodiments are merely a subset of embodiments of the utility model and not all embodiments of the utility model, with the understanding that the utility model is not limited to the example embodiments described herein. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the utility model described herein without inventive step, shall fall within the scope of protection of the utility model.
With the development of national industrialization, the yield of hazardous wastes is increased day by day, and the main disposal mode of the hazardous wastes is incineration disposal at present. Because the hazardous waste is various in types and complex in properties, and the nitrogen content in part of hazardous waste is high, the concentration of nitrogen oxides in the flue gas is high, and simultaneously, the requirement of 1100 ℃ and 2s is required for the incineration flue gas of the hazardous waste required by national standards, so that more nitrogen oxides are generated in the flue gas. At present, modes for reducing nitrogen oxides in smoke in dangerous waste incineration systems comprise SNCR, PNCR, SCR and the like, and most dangerous waste incineration plants use the SNCR mode to reduce the emission of the nitrogen oxides in the smoke due to the fact that the PNCR and the SCR are high in use cost. However, with the increasing regulatory pressure of environmental protection departments, the emission standard becomes tighter and tighter, and it is difficult to achieve the environmental protection requirement by reducing the emission of nitrogen oxides in the flue gas only in the SCNR manner.
The related art provides a flue gas recirculation system which injects flue gas from a secondary air port into the system by extracting part of the outlet flue gas of a draught fan. However, the flue gas recirculation system is only suitable for the waste incineration system, mainly aiming at reducing the emission of nitrogen oxides in the flue gas of the waste incineration system, and the flue gas injection position is related to the incinerator, so the flue gas recirculation system cannot be suitable for the counter-flow rotary kiln incineration system in the hazardous waste incineration system.
The main difference of the hazardous waste incineration system compared to the general waste incineration system is the difference of the incinerator. At present, a grate furnace is generally adopted in a waste incineration system, and in order to remove dioxin, the temperature of flue gas is required to be 950 ℃ for 2 s. The hazardous waste incineration system currently and generally adopts a rotary kiln (including a forward flow type and a reverse flow type), and the hazardous waste incineration flue gas requirement is 1100 ℃ for 2 s. The main sources of NOx in the flue gas comprise a thermal type, a fuel type and a rapid type, wherein the thermal type is that N2 in air is oxidized to generate NOx due to high temperature, and the fuel type is NOx generated by N reaction in combustion materials, so that compared with the waste incineration, the flue gas temperature in a hazardous waste incineration system is higher, the materials are more complex, more materials contain larger N content, and the generation amount of NOx is larger.
At present, the reduction means of NOx in the smoke purification of waste incineration and hazardous waste incineration are basically the same, mainly SNCR or SCR.
The utility model provides a flue gas recirculation system which is suitable for hazardous waste incineration. Hazardous waste incineration is different from waste incineration in that the incineration system includes a rotary kiln and a secondary combustion chamber, rather than the whole furnace. The fixed end is the connecting part of the rotary kiln and the second combustion chamber, and can be understood as a part of the second combustion chamber. The temperature of the flue gas from the rotary kiln is too high, and can exceed 1200 ℃, even reach 1300 ℃, which can cause the fly ash at the fixed end to melt or coke, and the thermal NOx to be generated.
Therefore, the flue gas recirculation system provided by the utility model can properly reduce the temperature of the hearth on one hand and disturb the flow field of the fixed end on the other hand by spraying the mixture of the flue gas and the secondary air at the fixed end, thereby improving the temperature uniformity and avoiding the phenomenon of overhigh local temperature. Thereby alleviating the possibility of fly ash melting and coking and reducing the generation of thermal NOx.
A flue gas recirculation system according to an embodiment of the present invention is specifically described below with reference to fig. 1.
As shown in fig. 1, a flue gas recirculation system, it includes rotary kiln, stiff end, second combustion chamber, draught fan and the chimney that connects gradually, wherein: the rotary kiln is used for burning hazardous wastes; the fixed end is used for connecting the rotary kiln and the secondary combustion chamber; the secondary combustion chamber is used for burning flue gas; the induced draft fan is used for maintaining the negative pressure of the flue gas recirculation system; the chimney is used for discharging flue gas, and, flue gas recirculation system still includes secondary air fan and circulating fan, secondary air fan is used for burning the flue gas and carries out the oxygen suppliment, circulating fan is used for extracting the part the flue gas of draught fan makes it with spout after the overgrate air behind the secondary air fan mixes the stiff end to reduce nitrogen oxide's formation and improve the homogeneity of flue gas temperature.
In some embodiments, the flue gas recirculation system further comprises a waste heat boiler connected to the outlet of the secondary combustion chamber for recovering the heat energy of the flue gas.
In some embodiments, the flue gas recirculation system further comprises a quench tower connected to the outlet of the waste heat boiler for reducing the flue gas temperature to avoid regeneration of dioxins.
In some embodiments, the flue gas recirculation system further comprises a bag-type dust collector connected to the outlet of the quench tower for capturing particulate matter in the flue gas.
In some embodiments, the flue gas recirculation system further comprises a wet tower connected between the outlet of the bag-type dust collector and the induced draft fan for desulfurization.
Specifically, the rotary kiln 1 is used for hazardous waste incineration; the fixed end 2 is used for connecting the rotary kiln 1 and the secondary combustion chamber 4; the secondary fan 3 is used for supplementing secondary air in the incineration system; the secondary combustion chamber 4 is a part of an incineration system, and the part of the flue gas reaching 1100 ℃ for 2s is used for carrying out flue gas incineration; the waste heat boiler 5 is used for recovering the heat energy of the flue gas; the temperature of the flue gas of the quenching tower 6 is reduced from 550 ℃ to 200 ℃, so that the regeneration of dioxin is avoided; the bag-type dust collector 7 collects the particulate matters in the flue gas; desulfurizing in a wet tower 8; the induced draft fan 9 is used for maintaining the negative pressure of the whole system; the chimney 10 is used for discharging flue gas; the circulating fan 11 is used for extracting the flue gas in the flue gas recirculation system.
The flue gas recirculation system operates as follows: flue gas generated in the dangerous waste incineration of the rotary kiln 1 sequentially passes through a secondary combustion chamber 4, a waste heat boiler 5, a cooling tower 6, a bag-type dust remover 7, a wet tower 8 and a draught fan 9 through a fixed end 2 and then is discharged into the atmosphere through a chimney 10. The circulating fan 11 extracts part of the flue gas from the induced draft fan 9, enters the secondary air pipe, mixes with the secondary air and then sprays into the fixed end 2, so as to achieve the purposes of reducing the temperature of the fixed end 2 and disturbing the flow field of the fixed end 2. The amount of flue gas extracted is adjusted by controlling the operating load of the circulation fan 11.
According to some embodiments of the utility model, the rotary kiln is a counter-flow rotary kiln.
The whole smoke temperature of the fixed end in the smoke recirculation system exceeds 1200 ℃, and the temperature of the mixed air of the smoke and the secondary air is lower, so that the whole smoke temperature can be reduced by spraying the mixed air into the fixed end. Meanwhile, the disturbance of the flue gas flow field at the fixed end can improve the flue gas mixing degree and the heat and mass transfer efficiency, and improve the uniformity of the flue gas temperature, thereby reducing the over-high local temperature.
By utilizing the flue gas recirculation system provided by the utility model, low-temperature flue gas at the rear part of the induced draft fan is sprayed into a high-temperature area in the fixed end, so that the generation of nitrogen oxides in the high-temperature area is reduced, the uniformity of a flow field in the high-temperature area is improved, and the phenomenon of melting and coking of the fixed end is relieved. Specifically, the overall combustion temperature of the fixed end is effectively reduced, the generation of nitrogen oxides in a high-temperature area is reduced, the aim of reducing the concentration of the nitrogen oxides in flue gas is fulfilled, and the system operation cost is reduced; in addition, the uniformity of a flue gas flow field in a high-temperature area of the fixed end is improved, the local high-temperature phenomenon in the fixed end is effectively relieved, and the probability of the fly ash fusion coking phenomenon at the fixed end is greatly reduced.
Therefore, the flue gas recirculation system provided by the utility model has the advantages that: through passing through the low temperature flue gas stiff end, can effectively reduce the whole combustion temperature of stiff end, reduce high temperature zone nitrogen oxide's formation from this, reach the purpose that reduces nitrogen oxide concentration in the flue gas to when guaranteeing that the fume emission is up to standard, reduce the SNCR consumption, reduce system's running cost. Meanwhile, the low-temperature flue gas is sprayed into the fixed end, the uniformity of a flue gas flow field in the area can be improved, the local high-temperature phenomenon in the fixed end is effectively relieved, and the probability of the fly ash melting coking phenomenon at the fixed end is greatly reduced.
The utility model provides a flue gas recirculation system which is low in running cost, can effectively reduce the emission of nitrogen oxides in flue gas in the running process of a rotary kiln incineration system, can relieve the problem of high-temperature coking at the fixed end of the incineration system, effectively reduces the running cost of the system and improves the stability of the system.
Although the illustrative embodiments have been described herein with reference to the accompanying drawings, it is to be understood that the foregoing illustrative embodiments are merely exemplary and are not intended to limit the scope of the utility model thereto. Various changes and modifications may be effected therein by one of ordinary skill in the pertinent art without departing from the scope or spirit of the present invention. All such changes and modifications are intended to be included within the scope of the present invention as set forth in the appended claims.
In the description provided herein, numerous specific details are set forth. It is understood, however, that embodiments of the utility model may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.
Similarly, it should be appreciated that in the description of exemplary embodiments of the utility model, various features of the utility model are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. However, the method of the present invention should not be construed to reflect the intent: that the utility model as claimed requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.
It will be understood by those skilled in the art that all of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or elements of any method or apparatus so disclosed, may be combined in any combination, except combinations where such features are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise.
Furthermore, those skilled in the art will appreciate that while some embodiments described herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the utility model and form different embodiments. For example, in the claims, any of the claimed embodiments may be used in any combination.
The above description is only for the specific embodiment of the present invention or the description thereof, and the protection scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and the changes or substitutions should be covered within the protection scope of the present invention. The protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (6)
1. The utility model provides a flue gas recirculation system which characterized in that, includes rotary kiln, stiff end, second combustion chamber, draught fan and the chimney that connects gradually, wherein:
the rotary kiln is used for burning hazardous wastes;
the fixed end is used for connecting the rotary kiln and the secondary combustion chamber;
the secondary combustion chamber is used for burning flue gas;
the induced draft fan is used for maintaining the negative pressure of the flue gas recirculation system;
the chimney is used for discharging the flue gas,
and flue gas recirculation system still includes secondary air fan and circulating fan, secondary air fan is used for burning the flue gas and carries out the oxygen suppliment, circulating fan is used for extracting the part the flue gas of draught fan makes it with secondary air behind the secondary air fan mixes the back and spouts the stiff end to reduce nitrogen oxide's formation and improve the homogeneity of flue gas temperature.
2. The flue gas recirculation system of claim 1, wherein the rotary kiln is a counter-flow rotary kiln.
3. The flue gas recirculation system of claim 1, further comprising a waste heat boiler connected to the outlet of the secondary combustion chamber for recovering flue gas heat energy.
4. The flue gas recirculation system according to claim 3, further comprising a quench tower connected to the outlet of the waste heat boiler for reducing the flue gas temperature to avoid regeneration of dioxins.
5. The flue gas recirculation system of claim 4, further comprising a bag-type dust collector connected to the outlet of the quench tower for capturing particulate matter in the flue gas.
6. The flue gas recirculation system of claim 5, further comprising a wet column connected between the outlet of the bag-type dust collector and the induced draft fan for desulfurization.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121876355.9U CN216307795U (en) | 2021-08-11 | 2021-08-11 | Flue gas recirculation system |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121876355.9U CN216307795U (en) | 2021-08-11 | 2021-08-11 | Flue gas recirculation system |
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| CN216307795U true CN216307795U (en) | 2022-04-15 |
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| CN202121876355.9U Active CN216307795U (en) | 2021-08-11 | 2021-08-11 | Flue gas recirculation system |
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| CN (1) | CN216307795U (en) |
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- 2021-08-11 CN CN202121876355.9U patent/CN216307795U/en active Active
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