CN109185871B

CN109185871B - Secondary air system of boiler

Info

Publication number: CN109185871B
Application number: CN201811209760.8A
Authority: CN
Inventors: 王家兴; 王超; 王勇; 彭建升; 程昌业; 崔强; 杜雨琛; 高全
Original assignee: Yantai Longyuan Power Technology Co Ltd
Current assignee: Yantai Longyuan Power Technology Co Ltd
Priority date: 2018-10-17
Filing date: 2018-10-17
Publication date: 2023-09-15
Anticipated expiration: 2038-10-17
Also published as: CN109185871A

Abstract

The invention belongs to the technical field of boiler transformation, and discloses a secondary air system of a boiler. The secondary air duct of the system is connected with a plurality of sets of secondary air duct assemblies, each set of secondary air duct assemblies corresponds to a hearth and is provided with a nozzle, and each set of secondary air duct assemblies comprises at least two sets of secondary air branch pipe assemblies; in each set of secondary air pipe assembly, one end of each set of secondary air branch pipe assembly, which is positioned in the secondary air channel, is mutually separated, and one end of each set of secondary air branch pipe assembly, which is positioned in the hearth, is communicated with the corresponding nozzle of the secondary air pipe assembly. According to the invention, through the mode that each group of secondary air branch pipe assemblies are arranged at one end of the secondary air channel and are mutually separated, and one end of the secondary air branch pipe assemblies at the hearth are communicated with the corresponding nozzles of the secondary air pipe assemblies, when the load is reduced, one group of secondary air branch pipe assemblies can be turned down or turned off, so that the flow velocity of other secondary air branch pipe assemblies in the secondary air branch pipe assemblies is not influenced, the momentum of secondary air passing through the nozzles is maintained, and the problem of poor secondary air penetrability caused by the reduction of the load is solved.

Description

Secondary air system of boiler

Technical Field

The invention relates to the technical field of boiler transformation, in particular to a secondary air system of a boiler.

Background

In a circulating fluidized bed boiler, a hearth is generally divided into a dense phase zone, a transition zone and a dilute phase zone according to different material concentrations, and solid particles in the dense phase zone have high concentration, high bed pressure and large heat capacity. When the boiler actually runs, because the concentration of solid particles in the dense-phase area is relatively high, the bed layer shows higher positive pressure of the hearth, so that the penetration resistance of secondary air flow is very high, the air is difficult to send into the dense-phase area, and the oxygen content of the hearth always shows a distribution trend of high surrounding and low middle. For the fluidized bed boiler, the primary air needs to ensure normal fluidization of the boiler, the minimum fluidization air quantity limit exists, the secondary air mainly plays roles in adjusting the load of the boiler and controlling the oxygen quantity of a hearth, the adjustment is larger along with the change of the load, and when the load is lower, the operation of the secondary air also needs to be stopped.

In the operation of the boiler, a secondary air system with conventional design is difficult to send secondary air into the middle part of a hearth; and especially, when the load is changed, the lower the load is, the required secondary air quantity is relatively reduced, and under the condition that the total number of nozzles and the area of the nozzles are unchanged, the wind speed of the nozzles is reduced, so that the jet power of the secondary air ports is reduced, and the penetrating capacity is reduced. The conventional method is to adjust the number of nozzles, when the load is higher, open all secondary air ports, randomly close part of the secondary air ports after the load is reduced, but the size and the number of the secondary air ports are mainly designed under full load, and the arrangement mode is mainly considered in terms of the uniformity and coverage of air distribution, the coordination with the bottom primary air, the arrangement correspondence of a hearth coal feeder and a material returning point, the distribution of hearth oxygen and the like. If part of the secondary air nozzles are directly turned off, uneven oxygen distribution in the furnace or larger deviation of a temperature field is easily caused.

Accordingly, there is a need to provide a new boiler overgrate air system that solves the above-mentioned problems.

Disclosure of Invention

The invention aims to provide a boiler secondary air system, which aims to solve the problem that the penetrability of secondary air is poor when the load of the existing boiler secondary air system is reduced.

To achieve the purpose, the invention adopts the following technical scheme:

a secondary air system of a boiler comprises a hearth and a secondary air channel connected with the hearth, wherein a plurality of sets of secondary air pipe assemblies are connected to the secondary air channel, each set of secondary air pipe assemblies comprises a secondary air box for containing secondary air, each set of secondary air pipe assemblies corresponds to the hearth and is provided with a nozzle, and each set of secondary air pipe assemblies comprises at least two sets of secondary air branch pipe assemblies;

in each set of secondary air pipe assembly, one end of each set of secondary air branch pipe assembly, which is positioned in the secondary air channel, is mutually separated, and one end of each set of secondary air branch pipe assembly, which is positioned in the hearth, is communicated with the corresponding nozzle of the secondary air pipe assembly.

Preferably, the parts of each group of secondary air branch pipe components close to the secondary air channels are provided with first regulating air doors, and the parts close to the hearth are provided with second regulating air doors.

Preferably, the first damper and the second damper are both electric dampers or manual dampers.

Preferably, a plurality of sets of secondary air pipe assemblies are symmetrically arranged on the whole body of the hearth.

Preferably, in each set of secondary air pipe assemblies, the parts, close to the hearth, of each two adjacent sets of secondary air branch pipe assemblies are sleeved with each other.

Preferably, the parts of each group of secondary air branch pipe assemblies close to the hearth are made of high-temperature resistant materials.

Preferably, each set of overgrate air manifold assembly is cast.

The invention has the beneficial effects that:

according to the invention, through the mode that each group of secondary air branch pipe assemblies are arranged at one end of the secondary air channel and are mutually separated, and one end of the secondary air branch pipe assemblies at the hearth are communicated with the corresponding nozzles of the secondary air pipe assemblies, when the load is reduced, one group of secondary air branch pipe assemblies can be turned down or turned off, so that the flow velocity of other secondary air branch pipe assemblies in the secondary air branch pipe assemblies is not influenced, the momentum of secondary air passing through the nozzles is maintained, and the problem of poor secondary air penetrability caused by the reduction of the load is solved.

Drawings

FIG. 1 is a schematic diagram of a configuration of a boiler overgrate air system provided by the present invention;

FIG. 2 is a schematic diagram of another configuration of the overfire air system of the boiler provided by the present invention.

In the figure:

1. a furnace; 2. a secondary air duct; 3. a secondary air duct assembly;

30. a secondary air box; 31. a spout; 32. a secondary air branch pipe assembly; 33. a first damper; 34. and a second damper.

Detailed Description

The technical scheme of the invention is further described below by the specific embodiments with reference to the accompanying drawings.

As shown in fig. 1 and fig. 2, the two are schematic structural diagrams of the boiler secondary air system provided by the invention. The secondary air system of the boiler comprises a hearth 1 and a secondary air channel 2 connected with the hearth 1, wherein the secondary air channel 2 is connected with a plurality of sets of secondary air pipe assemblies 3, each set of secondary air pipe assemblies 3 is provided with a nozzle 31 corresponding to the hearth 1, and each set of secondary air pipe assemblies 3 comprises at least two sets of secondary air branch pipe assemblies 32; in each set of secondary air pipe assemblies 3, one end of each set of secondary air branch pipe assemblies 32, which is positioned at the secondary air channel 2, is mutually separated, and one end of each set of secondary air branch pipe assemblies positioned at the hearth 1 is communicated with the corresponding nozzle 31 of each set of secondary air pipe assemblies 3. According to the invention, through the mode that each group of secondary air branch pipe assemblies 32 are arranged at one end of the secondary air channel 2 and are mutually separated, and one end of the secondary air branch pipe assemblies 32 at the hearth 1 is communicated with the corresponding nozzle openings 31 of the secondary air branch pipe assemblies 3, when the load is reduced, one group of secondary air branch pipe assemblies 32 can be turned down or turned off, the flow velocity of other secondary air branch pipe assemblies 32 in the secondary air branch pipe assemblies 3 is not influenced, so that the momentum of secondary air passing through the nozzle openings 31 is maintained, and the problem of poor secondary air penetrability caused by load reduction is solved.

Specifically, a first damper 33 is disposed at a portion of each set of secondary air branch pipe assemblies 32 close to the secondary air duct 2, a second damper 34 is disposed at a portion of each set of secondary air branch pipe assemblies close to the furnace 1, a secondary air box 30 for accommodating secondary air is disposed between the first damper 33 and the second damper 34, the first damper 33 serves as secondary air flow entering the secondary air box 30 from the secondary air duct 2, the second damper 34 serves as secondary air flow entering the furnace 1 from the secondary air box 30, and the secondary air box 30 serves as secondary air buffer for enabling secondary air to enter the furnace 1 uniformly and stably. The first damper 33 and the second damper 34 may be electric dampers or manual dampers, and in this embodiment, electric dampers are preferably used, and the secondary air flow rate of each set of secondary air branch pipe assemblies 32 may be adjusted by the first damper 33 and the second damper 34, so that when the load is reduced, the flow rate of one or several sets of secondary air branch pipe assemblies 32 is reduced, and the flow rate of other secondary air branch pipe assemblies 32 in the set of secondary air pipe assemblies 3 is not affected, thereby maintaining the momentum of secondary air passing through the nozzle 31, playing a role of reinforcing penetrating air supplement, that is, ensuring that the secondary air penetrating performance is still good when the load is reduced.

Specifically, the whole body of the furnace 1 is symmetrically provided with a plurality of sets of secondary air pipe assemblies 3 (only two sets are shown in fig. 1 and 2), so that the secondary air entering the furnace 1 can be ensured to be symmetrical and uniform, and the secondary air and the combustion coal in the furnace 1 can be favorably mixed.

Specifically, the part of each group of secondary air branch pipe assemblies 32 close to the hearth 1 is made of a high-temperature resistant material, and in order to prolong the service life of the secondary air branch pipe assemblies 32, the part of each group of secondary air branch pipe assemblies close to the hearth 1 is preferably made of the high-temperature resistant material, and further, a high-temperature resistant coating can be coated on the surface of the part.

Specifically, each group of secondary air branch pipe components 32 is formed by casting, and the secondary air branch pipe components 32 formed by casting reduce the cutting amount, and belong to the non-cutting processing with low processing cost.

Specifically, referring to fig. 2, the boiler overgrate air system provided in fig. 2 is a preferred embodiment of the present invention. Compared with the boiler overgrate air system provided in fig. 1, the overgrate air system provided in fig. 2 mainly differs in that: in each set of secondary air pipe assemblies 3, the parts of every two adjacent secondary air branch pipe assemblies 32 close to the hearth 1 are mutually sleeved, so that the secondary air flowing out from the secondary air branch pipe assemblies 32 can be ensured not to form resistance to other secondary air branch pipe assemblies 32 (corresponding to the same nozzle 31).

It is to be understood that the above examples of the present invention are provided for clarity of illustration only and are not limiting of the embodiments of the present invention. Other variations or modifications of the above description will be apparent to persons of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the invention are desired to be protected by the following claims.

Claims

1. The utility model provides a boiler overgrate air system, includes furnace (1) and with overgrate air way (2) that furnace (1) is connected, its characterized in that, overgrate air way (2) are connected with many sets of overgrate air pipe assembly (3), every set overgrate air pipe assembly (3) all include be used for holding overgrate air case (30), every set overgrate air pipe assembly (3) with furnace (1) corresponds there is a spout (31), every set overgrate air pipe assembly (3) all include two at least groups overgrate air branch pipe assembly (32);

in each secondary air pipe assembly (3), each secondary air branch pipe assembly (32) is located at one end of the secondary air channel (2) and is mutually separated, and one end of the hearth (1) is communicated with the corresponding nozzle (31) of the secondary air pipe assembly (3).

2. The boiler overgrate air system of claim 1 wherein each set of overair leg assemblies (32) is provided with a first damper (33) adjacent the overair duct (2) and a second damper (34) adjacent the furnace (1).

3. The boiler overgrate air system of claim 2, wherein the first damper (33) and the second damper (34) are both electric dampers or manual dampers.

4. A boiler overgrate air system according to claim 1, characterized in that the whole body of the furnace (1) is symmetrically provided with a plurality of sets of said overair duct assemblies (3).

5. A boiler overgrate air system according to claim 1, wherein in each set of said overair duct assemblies (3), every two adjacent sets of said overair duct assemblies (32) are nested in each other near the furnace (1).

6. The boiler overgrate air system of claim 5 wherein the portion of each set of overair leg assemblies (32) proximate to the furnace (1) is made of a high temperature resistant material.

7. A boiler overgrate air system according to any of claims 1-6, wherein each set of overair leg assemblies (32) is cast.