CN216897367U

CN216897367U - Economizer flue gas bypass device and denitration flue gas bypass system

Info

Publication number: CN216897367U
Application number: CN202122617283.2U
Authority: CN
Inventors: 韩玉维; 马志刚; 房代宝; 李永旺; 江浩
Original assignee: China Power Conservation And Environmental Protection Co ltd
Current assignee: China Power Conservation And Environmental Protection Co ltd
Priority date: 2021-10-28
Filing date: 2021-10-28
Publication date: 2022-07-05
Anticipated expiration: 2031-10-28

Abstract

The utility model discloses a flue gas bypass device of an economizer, which comprises at least two bypass sub-flues which are parallel and parallel, wherein the inlets of the bypass sub-flues are communicated with the flue of the economizer, the outlets of the bypass sub-flues are communicated with a main flue of a denitration system, and the outlet of each bypass sub-flue is arranged to comprise at least two sub-outlets. The utility model also discloses a denitration flue gas bypass system which comprises a coal economizer flue and a denitration system main flue which are sequentially communicated, wherein the coal economizer is arranged in the coal economizer flue, a catalyst bed layer and an air preheater are sequentially arranged in the denitration system main flue, and the coal economizer flue gas bypass device is communicated with the coal economizer flue and the denitration system main flue. The flue gas bypass device and the system of the utility model enable the high-temperature flue gas from the primary economizer and the low-temperature flue gas from the secondary economizer to be mixed more uniformly, so that the overall flue gas temperature entering the catalyst bed is improved under the low-load operation condition of the system, the flue gas and ammonia gas are fully reacted, the denitration efficiency is improved, and the discharged flue gas meets the emission standard.

Description

Economizer flue gas bypass device and denitration flue gas bypass system

Technical Field

The utility model belongs to the field of industrial flue gas purification and environmental protection, and particularly relates to a flue gas bypass device of an economizer.

Background

At present, the SCR flue gas denitration technology applied to domestic thermal power generation generally requires 310-420 ℃ for the condition that the load of a common boiler is 50% -100% of the load. However, when the boiler load is lower than 50% and the low-load operation is performed, the flue gas temperature is generally lower than 310 ℃, so that the denitration catalyst loses activity, and a coal-fired unit cannot perform denitration normally, so that the flue gas cannot meet the emission requirement. In view of the commissioning problem of the low-load SCR denitration device, in order to realize full-load denitration, the main technical means at present is an economizer working medium bypass and an economizer flue gas bypass. The former is mainly to increase the smoke temperature at the outlet of the economizer by reducing the size of the heating surface of the economizer, and the method easily causes that the smoke temperature at the inlet of the SCR is too high when a boiler runs under high load, side reaction and NH (NH) can occur₃Oxidized into NO, causing the reduction reaction to be unable to carry out, and the high-temperature flue gas can also cause the sintering to the catalyst, greatly reducing catalyst life. So the circumstances of using economizer flue gas bypass scheme are more, but most all exist, and high low temperature flue gas mixes inhomogeneously, and final denitration efficiency is lower, and the denitration effect is still not good.

SUMMERY OF THE UTILITY MODEL

In view of the above problems, the present invention provides an economizer flue gas bypass device. By means of the economizer flue gas bypass device, two high-temperature and low-temperature flue gas can be mixed more uniformly, so that the average temperature of the flue gas entering a catalyst bed is improved to different degrees when a boiler operates at a low load, the temperature reaches above 310 ℃, the application requirement of denitration design is met, a denitration device can normally operate, the denitration efficiency during the operation of the low load is directly improved, and the requirement of a flue gas emission standard is met.

On one hand, the utility model provides a flue gas bypass device of an economizer, which comprises at least two bypass sub-flues which are parallel and parallel, wherein the inlets of the bypass sub-flues are communicated with the flue of the economizer, the outlets of the bypass sub-flues are communicated with a main flue of a denitration system, and the outlet of each bypass sub-flue is arranged to comprise at least two sub-outlets.

Optionally, at least two of the branch outlets of each bypass branch flue are configured to be arranged in a step manner in a longitudinal section of the main flue of the denitration system.

Optionally, the economizer flue gas bypass device further comprises a bypass main flue, wherein one end of the bypass main flue is connected with the economizer flue, and the other end of the bypass main flue is connected with the bypass branch flue.

Optionally, a damper door for controlling the flow of the flue gas is further arranged on the bypass main flue.

Optionally, the number of the bypass branch flues is set to be 2-8, and the number of the branch outlets is set to be 2-8.

On the other hand, the utility model provides a denitration flue gas bypass system which comprises a coal economizer flue and a denitration system main flue which are sequentially communicated, wherein a coal economizer is arranged in the coal economizer flue, a catalyst bed layer and an air preheater are sequentially arranged in the denitration system main flue, and the coal economizer flue gas bypass device is communicated with the coal economizer flue and the denitration system main flue.

Optionally, the economizer includes a primary economizer and a secondary economizer arranged in the economizer flue at intervals in sequence, and the bypass main flue is connected to the outer wall of the economizer flue between the primary economizer and the secondary economizer.

Optionally, an ammonia injection grid, a static mixer and a rectification grid which are positioned at the upstream of the catalyst bed layer are sequentially arranged in the main flue of the denitration system at intervals, and the branch outlet of the bypass branch flue is arranged at the upstream of the ammonia injection grid.

Optionally, a temperature monitoring device is arranged between the rectifying grating and the catalyst bed layer in the main flue of the denitration system, the temperature monitoring device is electrically connected with the baffle door, and the opening of the baffle door is controlled to increase when the temperature of the flue gas monitored by the temperature monitoring device is lower than a specified value.

Optionally, at least one flow guide device is further arranged in the main flue of the denitration system.

Compared with the prior art, the economizer flue gas bypass device at least has the following beneficial effects:

the high-temperature flue gas from the primary economizer and the low-temperature flue gas from the secondary economizer are guaranteed to be mixed more uniformly, the whole flue gas temperature entering a catalyst bed is directly increased, so that the flue gas can fully react with ammonia gas, the denitration efficiency is improved, and finally the flue gas discharged by the SCR denitration system can better meet the requirements of flue gas emission standards.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the utility model. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:

FIG. 1 is a schematic structural diagram of an economizer flue gas bypass device in an embodiment of the utility model.

Fig. 2 is a schematic structural diagram of a denitration flue gas bypass system in the embodiment of the utility model.

Description of reference numerals:

0: a boiler outlet flue; 1: a first-stage economizer; 2: a secondary economizer; 3: an ammonia injection grid; 4: a static mixer; 5: a flow guide device; 6: a rectifying grid; 7: a catalyst bed layer; 8: an economizer flue gas bypass device; 81: a flapper door; 82: an outlet of the bypass branch flue; 83: a bypass main flue; 84: a bypass branch flue; 9: a temperature monitoring device; 10: an air preheater; 11: a coal vessel flue; 12: denitration system flue.

Detailed Description

Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the utility model are shown in the drawings, it should be understood that the utility model can be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the utility model to those skilled in the art.

Unless otherwise defined, various technical terms involved in the present invention have meanings commonly understood by those skilled in the art.

Example 1

As shown in fig. 1, an economizer flue gas bypass device 8 according to embodiment 1 of the present invention includes: flapper door 81, bypass main stack 83, at least two bypass sub-stacks 84 in parallel juxtaposition, and outlet 82 of the bypass sub-stacks.

One end of the bypass main flue 83 is connected to the coal burner flue 11, and the other end of the bypass main flue 83 is connected to the bypass sub-flue 84. The outlet 82 of the bypass branch flue communicates with the denitration system main flue 12.

A damper door 81 is provided on the bypass main flue 83 for controlling the flow of flue gas. By adjusting the opening of the damper door 81, the flue gas flow entering the economizer flue gas bypass device 8 can be adjusted. The flue gas entering the economizer flue gas bypass device 8 passes through the bypass main flue 83 and the bypass branch flue 84 in sequence, and then flows out of the outlet 82 of the bypass branch flue.

2-8 bypass sub-flues 84 can be arranged and respectively extend into the main flue 12 of the denitration system. The specific number of the bypass branch flues 84 can be determined according to the width of the main flue 12 of the denitration system and the flue gas flow rate. In the present embodiment, 5 bypass branch flues 84 are provided, which, of course, is exemplary only.

The outlet of each bypass sub-flue 84 comprises at least two sub-outlets, for example, 2-8 sub-outlets are uniformly arranged along the depth direction of the main flue 12 of the denitration system. The specific number of the branch outlets can be determined according to the depth size and the flue gas flow of the main flue 12 of the denitration system. The split outlet of each bypass sub-stack 84 is configured to be stepped in the longitudinal section of the denox system main stack 12. In the present embodiment, the outlet of each bypass branch flue 84 includes 5 branch outlets, which, of course, is merely exemplary.

Example 2

As shown in fig. 2, a denitration flue gas bypass system according to embodiment 2 of the present invention includes an economizer flue and a denitration system main flue that are sequentially communicated, and the economizer flue gas bypass device 8 according to embodiment 1 communicates the economizer flue and the denitration system main flue.

The primary economizer 1 and the secondary economizer 2 are sequentially arranged in the economizer flue at intervals.

The main flue of the denitration system is sequentially provided with a catalyst bed layer 7 and an air preheater 10. An ammonia injection grid 3, a static mixer 4 and a rectification grid 6 are also arranged in sequence at the upstream of the catalyst bed layer 7. A temperature monitoring device 9 is arranged between the rectifying grid 6 and the catalyst bed 7. The temperature monitoring device 9 is electrically connected to the flapper door 81, and controls the opening of the flapper door 81 to increase when the temperature of the flue gas monitored by the temperature monitoring device 9 is lower than a prescribed value.

The bypass main flue 83 of the economizer flue gas bypass device 8 of embodiment 1 is connected to the economizer flue between the primary economizer and the secondary economizer. The outlet 82 of the bypass branch flue of the economizer flue gas bypass device 8 of embodiment 1 is disposed upstream of the ammonia injection grid 3, that is, between the secondary economizer 2 and the ammonia injection grid 3.

At least one flow guide device 5 is further arranged in the main flue of the denitration system, and the flow guide device is a flow guide plate for example. In the present embodiment, baffles are provided between the secondary economizer 2 and the ammonia injection grid 3 and between the static mixer 4 and the rectification grid 6, respectively, which, of course, is merely exemplary.

The denitration flue gas bypass system of the embodiment has the following working process:

when the load of the boiler is high, the flue gas from the boiler passes through a boiler outlet flue 0, firstly enters a primary coal economizer 1, then passes through a secondary coal economizer 2, and enters an SCR denitration system, wherein the flue gas from the secondary coal economizer sequentially passes through a flow guide device 5, an ammonia injection grid 3, a static mixer 4 and a rectifying grid 6 on the upper part of a catalyst bed layer, then enters a catalyst bed layer 7 of a denitration reactor for denitration reaction, the flue gas after denitration is finished enters a downstream air preheater 10 and other subsequent air treatment devices, and finally the flue gas reaching the standard after being treated by various processes such as denitration, desulfuration and dedusting is discharged through a chimney.

When the boiler load is low, the temperature monitoring device 9 monitors that the flue gas temperature is lower than a specified value (for example, 310 ℃), then the baffle door 81 is opened, the high-temperature flue gas led out from the outlet of the primary economizer 1 is adjusted in opening degree of the baffle door 81, the flow of the high-temperature flue gas entering the economizer flue gas bypass device 8 is adjusted, the high-temperature flue gas passes through the bypass main flue 83 and the bypass sub flue 84, then flows out of the outlet 82 of the bypass sub flue, is mixed with the main low-temperature flue gas from the secondary economizer 2, then passes through the ammonia injection grid 3, is further mixed with the injected ammonia gas, and enters the downstream catalyst bed layer 7 for denitration reaction.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the utility model has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention, and they should be construed as being included in the following claims and description. In particular, the technical features mentioned in the embodiments can be combined in any way as long as there is no structural conflict. It is intended that the utility model not be limited to the particular embodiments disclosed, but that the utility model will include all embodiments falling within the scope of the appended claims.

Claims

1. The coal economizer flue gas bypass device is characterized by comprising at least two parallel bypass sub-flues, wherein the inlets of the bypass sub-flues are communicated with the coal economizer flue, the outlets of the bypass sub-flues are communicated with a main flue of a denitration system, and the outlet of each bypass sub-flue is arranged to comprise at least two sub-outlets.

2. The economizer flue gas bypass arrangement according to claim 1, wherein at least two of the branch outlets of each bypass branch flue are configured to be stepped in a longitudinal section of the denox main flue.

3. The economizer flue gas bypass device according to claim 1, further comprising a bypass main flue, wherein one end of the bypass main flue is connected with the economizer flue, and the other end is connected with the bypass branch flue.

4. The economizer flue gas bypass device according to claim 3, wherein a damper door for controlling the flow of flue gas is further provided on the bypass main flue.

5. The economizer flue gas bypass device according to claim 4, wherein the number of bypass branch flues is set to 2-8, and the number of branch outlets is set to 2-8.

6. A denitration flue gas bypass system is characterized by comprising a coal economizer flue and a denitration system main flue which are sequentially communicated, wherein a coal economizer is arranged in the coal economizer flue, a catalyst bed layer and an air preheater are sequentially arranged in the denitration system main flue, and the coal economizer flue gas bypass device according to any one of claims 1 to 5 is communicated with the coal economizer flue and the denitration system main flue.

7. The denitration flue gas bypass system according to claim 6, wherein the economizer comprises a primary economizer and a secondary economizer which are arranged in the economizer flue at intervals in sequence, and the bypass main flue is connected to the outer wall of the economizer flue between the primary economizer and the secondary economizer.

8. The denitration flue gas bypass system of claim 7, wherein an ammonia injection grid, a static mixer and a rectification grid which are positioned at the upstream of the catalyst bed layer are sequentially arranged in the main flue of the denitration system at intervals, and a branch outlet of the bypass branch flue is arranged at the upstream of the ammonia injection grid.

9. The denitration flue gas bypass system according to claim 8, wherein a temperature monitoring device is arranged between the rectifying grid and the catalyst bed in the main flue of the denitration system, the temperature monitoring device is electrically connected with a baffle door, and the opening degree of the baffle door is controlled to be increased when the temperature of the flue gas monitored by the temperature monitoring device is lower than a specified value.

10. The denitration flue gas bypass system according to any one of claims 6 to 9, wherein at least one flow guide device is further arranged in the denitration system main flue.