CN109185872B

CN109185872B - Secondary air system of boiler

Info

Publication number: CN109185872B
Application number: CN201811210128.5A
Authority: CN
Inventors: 王家兴; 王超; 王勇; 彭建升; 程昌业; 高全; 崔强; 杜雨琛
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: 2023-09-19
Anticipated expiration: 2038-10-17
Also published as: CN109185872A

Abstract

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

in each group of secondary air pipes, one end of each secondary air branch pipe positioned in the secondary air box is mutually separated, and one end positioned in the hearth is communicated with the corresponding nozzle of the secondary air pipe.

Preferably, a damper is arranged at a part of each secondary air branch pipe close to the secondary air box.

Preferably, the damper is an electric damper or a manual damper.

Preferably, a plurality of groups of secondary air pipes are symmetrically arranged on the whole body of the hearth.

Preferably, in each group of secondary air pipes, the parts of every two adjacent secondary air branch pipes close to the hearth are mutually sleeved.

Preferably, the part of each secondary air branch pipe close to the hearth is made of high-temperature resistant materials.

Preferably, each secondary air branch pipe is cast.

The invention has the beneficial effects that:

according to the invention, through the mode that each secondary air branch pipe is arranged at one end of the secondary air box and is mutually separated, and one end of the secondary air branch pipe which is arranged at the hearth is communicated with the corresponding nozzle of the secondary air pipe, when the load is reduced, one secondary air branch pipe can be turned down or turned off, so that the flow velocity of other secondary air branch pipes in the secondary air pipe group is not influenced, the momentum of secondary air passing through the nozzle is maintained, and the problem of poor secondary air penetrability caused by load reduction 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 box; 3. a secondary air duct;

31. a spout; 32. secondary air branch pipes; 33. and (5) adjusting the air door.

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 box 2 connected with the hearth 1, wherein the secondary air box 2 is connected with a plurality of groups of secondary air pipes 3, each group of secondary air pipes 3 is provided with a nozzle 31 corresponding to the hearth 1, and each group of secondary air pipes 3 comprises at least two secondary air branch pipes 32; in each group of secondary air pipes 3, one end of each secondary air branch pipe 32 positioned in the secondary air box 2 is mutually separated, and one end positioned in the hearth 1 is communicated with the corresponding nozzle 31 of the group of secondary air pipes 3. According to the invention, through the mode that each secondary air branch pipe 32 is arranged at one end of the secondary air box 2 and is mutually separated, and one end of the secondary air branch pipe 32 at the hearth 1 is communicated with the corresponding nozzle 31 of the group of secondary air pipes 3, when the load is reduced, one secondary air branch pipe 32 can be turned down or turned off, so that the flow velocity of other secondary air branch pipes 32 in the group of secondary air pipes 3 is not influenced, the momentum of secondary air passing through the nozzle 31 is maintained, and the problem of poor secondary air penetrability caused by the reduction of the load is solved.

Specifically, the part of each secondary air branch pipe 32 close to the secondary air box 2 is provided with a damper 33, the damper 33 can be an electric damper or a manual damper, in this specific embodiment, the electric damper is preferably adopted, the secondary air flow of each secondary air branch pipe 32 can be adjusted through the damper 33, when the load is reduced, the flow rate of one or more secondary air branch pipes 32 is reduced, the flow rate of other secondary air branch pipes 32 in the group of secondary air pipes 3 is not influenced, so that the momentum of secondary air passing through the nozzle 31 is maintained, the effect of reinforcing penetrating air supplement is achieved, and the advantage that the secondary air penetrating performance is still good when the load is reduced is ensured.

Specifically, the whole body of the furnace 1 is symmetrically provided with a plurality of groups of secondary air pipes 3 (only two groups 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 secondary air branch pipe 32 near 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 32, the part near the hearth 1 is preferably made of a high temperature resistant material, and further, a high temperature resistant coating can be coated on the surface of the part.

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

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 group of secondary air pipes 3, the parts of every two adjacent secondary air branch pipes 32 close to the hearth 1 are mutually sleeved, so that the secondary air flowing out between the secondary air branch pipes 32 can be ensured not to form resistance to other secondary air branch pipes 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 secondary air system of the boiler comprises a hearth (1) and a secondary air box (2) connected with the hearth (1), and is characterized in that the secondary air box (2) is connected with a plurality of groups of secondary air pipes (3), each group of secondary air pipes (3) is provided with a nozzle (31) corresponding to the hearth (1), and each group of secondary air pipes (3) comprises at least two secondary air branch pipes (32);

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

2. A boiler overgrate air system according to claim 1, characterized in that each of said overair branch pipes (32) is provided with a damper (33) in a portion adjacent to said overair box (2).

3. A boiler overgrate air system according to claim 2, characterized in that the damper (33) is an electric damper or a manual damper.

4. The 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 groups of overair ducts (3).

5. A boiler overgrate air system according to claim 1, characterized in that in each group of said overair ducts (3), every two adjacent overair branch ducts (32) are nested in each other near the furnace (1).

6. The overgrate air system of claim 5 wherein a portion of each of said overair legs (32) adjacent said 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 of said overair legs (32) is cast.