CN216281333U

CN216281333U - Economizer air preheater bypass

Info

Publication number: CN216281333U
Application number: CN202122423055.1U
Authority: CN
Inventors: 蒋俊芳
Original assignee: Jiangsu Huineng Heavy Industry Co ltd
Current assignee: Jiangsu Huineng Heavy Industry Co ltd
Priority date: 2021-10-09
Filing date: 2021-10-09
Publication date: 2022-04-12
Anticipated expiration: 2031-10-09

Abstract

The utility model relates to a main body performance part of a circulating fluidized bed boiler, in particular to an economizer air preheater bypass, which comprises an economizer gas system, an SCR denitration system and an anti-blocking air preheater system, wherein the SCR denitration system and the anti-blocking air preheater system are arranged in the middle of the economizer system, the air preheater system is arranged at the tail part of the economizer system, the economizer gas system comprises an upper-level economizer, a middle-level economizer and a lower-level economizer, the SCR denitration system is arranged between the upper-level economizer and the middle-level economizer, a bypass pipeline is arranged on one side of the upper-level economizer, and a regulating valve is arranged on the bypass pipeline.

Description

Economizer air preheater bypass

Technical Field

The utility model belongs to main body performance parts of a circulating fluidized bed boiler, and relates to a novel high-temperature separation core technology for efficient and environment-friendly circulating materials, in particular to an economizer air preheater bypass.

Background

Along with the macroscopic regulation and control of the country on the coal-fired unit and the increasingly strict requirement of the country on the environmental protection, the Nox original emission is implemented by a new standard which is less than or equal to 50mg/Nm 3. In general, in order to carry out denitration, an ammonia gun is arranged at a horizontal flue part for SNCR denitration, the denitration by adopting the method has higher requirement on the temperature interval of a hearth outlet, and the optimal reaction temperature interval is 800-900 ℃. The condition that the furnace outlet overtemperature occasionally appears under the high load condition, a large amount of ammonia water needs to be sprayed in for denitration. The consumption of ammonia water is large, so that the tail flue is easy to corrode, and the service life of the boiler is influenced. Under the condition of low load, the reaction temperature of the outlet of the hearth is lower than the optimal reaction temperature range of ammonia water, so that the denitration efficiency of the boiler is reduced.

To meet this emission standard at both overload and ultra-low load, most boilers denitrate in a coordinated manner with SNCR and SCR. Because SCR also needs a small amount of ammonia water, partial ammonia escape formed by SNCR just provides the ammonia water required by the reaction for SCR, and the SCR also plays a certain role in protecting the heating surface of the tail flue.

Although SCR is medium-temperature denitration, the SCR has certain requirements on the temperature of a reaction zone, usually 380-420 ℃, and can basically meet the requirements in design; because the boiler is in an ultra-low load state easily at night and on holidays when running, the lowest temperature reaction interval of the SCR cannot be effectively ensured, and the environmental protection pressure of the boiler is increased; the phenomenon that the tail flue air preheater part is hardened after ammonia escape is increased can also occur in long-term low-load operation, the boiler shutdown maintenance is required to be frequently carried out, and the operation time of a boiler is shortened, so that a coal economizer air preheater bypass is required to be designed.

SUMMERY OF THE UTILITY MODEL

In order to solve the problems, the utility model provides an economizer air preheater bypass, which has the following specific technical scheme:

an economizer air preheater bypass comprises an economizer system, an SCR denitration system and an anti-blocking air preheater system, wherein the SCR denitration system is arranged in the middle of the economizer system, the air preheater system is arranged at the tail of the economizer system, the economizer system comprises a higher-level economizer, a middle-level economizer and a lower-level economizer, the SCR denitration system is arranged between the higher-level economizer and the middle-level economizer, the SCR denitration system is arranged in the middle of the economizer system, the temperature in the middle of the economizer system is particularly important for the denitration efficiency of SCR, in order to ensure that the reaction temperature of SCR arranged between the higher-level economizer and the middle-level economizer is always between 380 ℃ and 420 ℃ under low overload, a bypass pipeline is arranged on one side of the higher-level economizer, a regulating valve is arranged on the bypass pipeline, and the bypass pipeline is controlled to be opened and closed by the regulating valve, the water of the upper-level economizer and the water of the middle-level economizer are mixed, so that the temperature interval between the arrangement and the SCR can be maintained in a constant range, and the temperature of the SCR region is adjusted by utilizing the opening degree of the regulating valve under different loads, so that the SCR can be efficiently utilized.

The utility model is further improved in that: the anti-blocking air preheater system comprises a first return air preheater, a second return air preheater and a third return air preheater.

The utility model is further improved in that: the first return stroke air preheater is arranged through a pipe of 60mm, the pitch is 110mm, and the spare gap in the middle of the arrangement of the air preheater is 40 mm.

The utility model is further improved in that: the second return air preheater is arranged through a 40mm pipe, the pitch is 60mm, and the middle aperture is 20 mm.

The utility model is further improved in that: and a spoiler is arranged in the second return air preheater.

The utility model is further improved in that: the spoiler is a thin plate with the thickness of 1mm and the width of 30mm, and two ends of the spoiler are fixed inside the pipeline of the air preheater in a spot welding mode.

The utility model is further improved in that: the third return air preheater is arranged through a pipe of 40mm, the pitch is 60mm, the middle hole is 20mm, the flow speed of flue gas is controlled to be about 9m/s, and heat absorption is effectively carried out on a high-temperature section.

The utility model has the beneficial effects that:

according to the utility model, the reaction temperature at the SCR position is subjected to temperature adjustment control according to the temperature interval requirement of the SCR, so that the lowest temperature reaction interval of the SCR can be effectively ensured, the denitration requirement can be met, the air preheater part is reasonably arranged, the dust deposition at the air preheater part is reduced, the furnace shutdown maintenance time can be reduced, and the operation working time of the boiler is prolonged.

Drawings

FIG. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is a side view of the air preheater of the present invention;

FIG. 3 is a schematic structural diagram of a stabilized air preheater according to the present invention;

reference numerals: the system comprises a 1-economizer system, a 2-SCR denitration system, a 3-air preheater system, a 4-upper-level economizer, a 5-middle-level economizer, a 6-lower-level economizer, a 7-regulating valve, an 8-first return air preheater, a 9-second return air preheater, a 10-third return air preheater, an 11-first return inlet, a 12-first return outlet, a 13-second return outlet, a 14-second return inlet, a 15-spoiler, a 16-third return outlet and a 17-third return inlet.

Detailed Description

For the purpose of enhancing the understanding of the present invention, the present invention will be described in further detail with reference to the accompanying drawings and examples, which are provided for the purpose of illustration only and are not intended to limit the scope of the present invention.

The embodiment provides an economizer air preheater bypass, which comprises an economizer system 1, an SCR denitration system 2 arranged in the middle of the economizer system 1 and an anti-blocking air preheater system 3, wherein the air preheater system 3 is arranged at the tail of the economizer system 1, the economizer system 1 comprises an upper-level economizer 4, a middle-level economizer 5 and a lower-level economizer 6, the SCR denitration system 2 is arranged between the upper-level economizer 4 and the middle-level economizer 5, because the SCR denitration system 2 is arranged in the middle of the economizer system 1, the temperature in the middle of the economizer system 1 is particularly important for the denitration efficiency of SCR, in order to ensure that the reaction temperature of SCR arranged between the upper-level economizer 4 and the middle-level economizer 5 is always between 380 ℃ and 420 ℃ under low overload, one side of the upper-level economizer 4 is provided with a bypass pipeline 6, the bypass pipeline 6 is provided with an adjusting valve 7, the bypass pipeline 6 is controlled to be opened and closed by the adjusting valve 7, water of the upper-level economizer 4 and water of the middle-level economizer 5 are mixed, the temperature interval between the arrangement and the SCR can be maintained in a constant range, the temperature of the SCR area can be adjusted by the opening degree of the adjusting valve 7 under different loads, and the SCR can be efficiently utilized.

Its temperature interval adopts adjustable mode to control reaction temperature, traditional economizer gets into higher level from the subordinate, the mode that the temperature rises gradually goes on, in this embodiment, wholly become one-level, the temperature is even, there is not the difference in temperature, because SCR deNOx systems requires highly to reaction temperature, such setting can make the temperature control in whole economizer system 1 be the best reaction temperature, and can also adjust exhaust gas temperature like this, because too low exhaust gas temperature can lead to the afterbody dewfall, the bag is stuck with paste to the dust remover, denitration efficiency and exhaust gas temperature can effectively be improved to this kind of structure.

The anti-blocking air preheater system 3 comprises a first return air preheater 8, a second return air preheater 9 and a third return air preheater 10, cold air in the anti-blocking air preheater system 3 enters from the lower end, hot air is discharged from the upper end, the right end of the first return air preheater 8 is a first return inlet 11, the left end of the first return air preheater is a first return outlet 12, pipes of 45 mm-60 mm are arranged in the first return air preheater, the pitch of the air preheaters is 95 mm-110 mm, and the gap between the adjusted pipes is 40 mm-50 mm; when ash containing ammonia escaping from the flue gas passes through the first return air preheater 8, the phenomenon of caking at the position of the section of air preheater is avoided, so that the flue gas can smoothly pass through; because the air pre-heaters of the first return stroke are arranged in a pipe diameter of 45-60 mm, the resistance of primary air and secondary air can be effectively reduced when the air pre-heaters pass through the air pre-heaters; the right end of the second return air preheater 9 is a second return outlet 13, the left end is a second return inlet 14, pipes of 40mm are arranged in the second return air preheater, the pitch of the air preheater is 60mm, and the middle gap after the air preheater is arranged is 20 mm; because the first return low-temperature section air preheater has the defect of reduced heat absorption capacity after the pitch is increased during arrangement, the spoiler 15 needs to be arranged in the second return air preheater 9, so that the air which should directly pass through the air preheater tube forms wall flow in the second return air preheater 9 tube when entering the tube, the rotation is formed in the air preheater tube, the retention time in the tube is increased, and the heat absorption capacity is increased.

The pitch of the first return low-temperature section air preheater is increased for use; the spoiler is made of a thin plate with the thickness of 1mm and the width of 30mm, and the number of turns of the spoiler is adjusted in an adaptive manner according to the length of the air preheater pipe; in order to prevent mechanical wear caused by the turbulence plate 15 shaking inside the pipe; spot welding and fixing two ends of the spoiler 15; the right side of the third return air preheater 10 is the third return inlet 17, the left side is the third return outlet 16, because the position of the third return air preheater 10 is behind the economizer system, the third return air preheater still has higher temperature and better ash activity, and the heat absorption is increased by utilizing the characteristics of the third return air preheater as much as possible when the third return air preheater is arranged, 40mm enamel pipes are arranged in the third return air preheater, the pitch is controlled to be 60mm, a gap of 20mm is reserved, the flow rate of flue gas is controlled to be about 9m/s, and the heat absorption is effectively carried out on a high-temperature section.

Claims

1. The utility model provides an economizer air preheater bypass which characterized in that: the SCR denitration system comprises an economizer system, an SCR denitration system arranged in the middle of the economizer system and an anti-blocking air preheater system, wherein the air preheater system is arranged at the tail part of the economizer system, the economizer system comprises an upper-level economizer, a middle-level economizer and a lower-level economizer, the SCR denitration system is arranged between the upper-level economizer and the middle-level economizer, one side of the upper-level economizer is provided with a bypass pipeline, and the bypass pipeline is provided with an adjusting valve.

2. The economizer air preheater bypass according to claim 1, wherein: the anti-blocking air preheater system comprises a first return air preheater, a second return air preheater and a third return air preheater.

3. The economizer air preheater bypass according to claim 2, wherein: the first return stroke air preheater is arranged through a pipe of 60mm, the pitch is 110mm, and the spare gap in the middle of the arrangement of the air preheater is 40 mm.

4. The economizer air preheater bypass according to claim 2, wherein: the second return air preheater is arranged through a 40mm pipe, the pitch is 60mm, and the middle aperture is 20 mm.

5. The economizer air preheater bypass according to claim 4, wherein: and a spoiler is arranged in the second return air preheater.

6. The economizer air preheater bypass according to claim 5, wherein: the spoiler is a thin plate with the thickness of 1mm and the width of 30mm, and two ends of the spoiler are fixed inside the pipeline of the air preheater in a spot welding mode.

7. The economizer air preheater bypass according to claim 6, wherein: the third return air preheater is arranged through a 40mm pipe, the pitch is 60mm, and the middle aperture is 20 mm.