CN219036697U - Cold primary air bypass arrangement structure for boiler combustion system - Google Patents

Abstract

The utility model discloses a cold primary air bypass arrangement structure for a boiler combustion system, which comprises an air preheater, wherein a primary air inlet, a secondary air inlet, a primary air outlet and a secondary air outlet are arranged on the air preheater, the primary air inlet and the primary air outlet are respectively connected with a cold primary air pipeline and a hot primary air pipeline, a cold primary air bypass expansion pipeline is communicated between the cold primary air pipeline and the hot primary air pipeline, and a pneumatic adjusting air valve is arranged on the cold primary air bypass expansion pipeline. The utility model discloses a cold primary air bypass arrangement structure for a boiler combustion system, which belongs to the technical field of air supply of coal-fired boilers, is reasonable in structural design, is provided with a cold primary air bypass expansion pipeline, expands the volume of the cold primary air bypass, is additionally provided with a pneumatic adjusting air valve, and can be opened to enlarge the conveying flow of cold primary air under the condition that the temperature of a primary air box is reduced due to no exhaust gas when a coal mill stops grinding.

Description

Cold primary air bypass arrangement structure for boiler combustion system

Technical Field

The present utility model relates to the art of coal-fired boiler air supply, and more particularly, to a cold primary air bypass arrangement for a boiler combustion system.

Background

In the operation of the boiler, wind (air) and fuel are required to be continuously fed into a hearth, the fuel is combusted under the combustion supporting of oxygen in the air supply to release a large amount of heat energy, water in a boiler barrel (shell) is heated to generate steam or hot water required by people, and then flue gas is discharged into the atmosphere through a flue and a chimney. If the exhaust gas temperature is certain, the air supply temperature is improved, so that the activity of oxygen combustion supporting can be enhanced, the heat absorption quantity of a large amount of gas which does not participate in combustion in air supply can be reduced, and the energy conservation is facilitated. At present, an air preheater adopted by a boiler utilizes the principle that: the air preheater is arranged on the flue, and the preheated air is sent into the hearth by the boiler blower by utilizing a longer air pipe, so that the air supply temperature of the boiler can be increased, and the waste heat of flue gas can be utilized.

Main equipment such as a coal pulverizing system and a boiler burner at present are designed and checked aiming at low-volatile bituminous coal mixing, the dry ashless base volatile component of the designed coal is 24.31%, the generated heat of the received base low-position is 21.616MJ/kg, and the design scheme of a steel ball coal mill medium-storage type hot air powder feeding system and a boiler stable combustion system is adopted. The coal mill drying medium is high-temperature furnace smoke extracted from the bottom of a hearth and low-temperature furnace smoke extracted from an outlet of a draught fan, and the temperature-adjusting air is secondary air and low-temperature furnace smoke at an outlet of an air preheater. The outlet temperature of the coal mill is designed to be 100 ℃, the temperature of hot primary air is 332.2 ℃, and the temperature of the air-powder mixture in the powder feeding pipeline is more than 230 ℃.

Because the coal types designed by the original boiler are mixed coals such as low-volatile bituminous coal, lean coal and the like, the high-volatile bituminous coal and the lignite are required to be mixed and burned in a large proportion after the modification. According to the specification of 4.1.8 in DLT5203-2005 of explosion-proof design technical regulations of coal and powder preparation systems of thermal power plants: when the silo-type pulverizing system adopts hot air for powder feeding, the temperature of the hot air is selected so that the temperature of the air-powder mixture at the inlet connecting pipe of the burner is not more than 160 ℃ and the temperature of the lignite is not more than 100 ℃. When the original low-volatile mixed coal is burned under the BMCR working condition of the boiler, the temperature of hot primary air is 332.2 ℃, and the temperature of air-powder mixture in the powder feeding pipeline is more than 230 ℃. Because the boiler pulverizing system is originally designed as a middle storage bin type hot air powder feeding system, the pulverized coal pipeline is longer, the number of the elbows is more, the powder bins and the like can have positions and opportunities of powder accumulation, the spontaneous combustion of the accumulated pulverized coal can be caused after the temperature exceeds the range, and the burning loss of the pulverized coal pipeline or the spontaneous combustion explosion of the pulverized coal in the powder bins and the like can be caused when the temperature exceeds the range. Therefore, after the bituminous coal and the lignite are burned, the powder feeding temperature must be reduced to below 160 ℃ for safety.

Therefore, the cold primary air pipeline needs to be designed and modified to reduce the temperature of the air-powder mixture in the powder feeding pipeline.

Disclosure of Invention

The technical problem underlying the present utility model is that of addressing some of the above-mentioned drawbacks of the prior art, and it is an object of the present utility model to provide a cold primary air bypass arrangement for a boiler combustion system.

In order to achieve the above purpose, the utility model provides a cold primary air bypass arrangement structure for a boiler combustion system, which comprises an air preheater, wherein one end of the air preheater is provided with a primary air inlet and a secondary air inlet, the other end of the air preheater is provided with a primary air outlet and a secondary air outlet, the upper side of the air preheater is provided with a flue gas inlet pipe connected with a boiler furnace exhaust pipe, the lower side of the air preheater is provided with a flue gas outlet pipe, the primary air inlet and the primary air outlet are respectively connected with a cold primary air pipeline and a hot primary air pipeline, a cold primary air bypass expansion pipeline is communicated between the cold primary air pipeline and the hot primary air pipeline, and a pneumatic adjusting air valve is arranged on the cold primary air bypass expansion pipeline.

Further, a primary fan is arranged on the cold primary air pipeline, and the connection point of the cold primary air bypass expansion pipeline and the cold primary air pipeline is positioned at the downstream of the primary fan.

Further, a secondary air blower is arranged at the secondary air inlet.

Furthermore, the joint of the cold primary air pipeline and the primary air inlet is provided with a pipe joint, the side part of the pipe joint is provided with a bypass branch pipe which is obliquely extended, and the cold primary air bypass expansion pipeline is communicated with the bypass branch pipe.

Further, the included angle between the bypass branch pipe and the pipe joint is smaller than 60 degrees.

Further, the flue gas exit pipe department is connected with the draught fan through the pipeline.

Advantageous effects

Compared with the prior art, the cold primary air bypass arrangement structure for the boiler combustion system has the following beneficial effects: this a cold primary air bypass arrangement structure for boiler combustion system, structural design is reasonable, has set up cold primary air bypass dilatation pipeline, expands the volume to cold primary air bypass to increased pneumatic regulation blast gate, realized remote control, ensured not having the exhaust gas when the coal pulverizer stops grinding and reduced the condition of primary air bellows temperature under, can open pneumatic regulation blast gate, increase the transport flow of cold primary air, quick will send the powder temperature to reduce below 160 ℃.

Drawings

FIG. 1 is a schematic structural view of a cold primary air bypass arrangement for a boiler combustion system of the present utility model;

FIG. 2 is a block diagram of a duct arrangement of a cold primary air bypass arrangement for a boiler combustion system in accordance with the present utility model.

In the figure: 1. an air preheater; 2. a primary air inlet; 3. a secondary air inlet; 4. a primary air outlet; 5. a secondary air outlet; 6. a flue gas inlet pipe; 7. a flue gas outlet pipe; 8. a cold primary air duct; 9. a hot primary air duct; 10. a cold primary air bypass expansion pipeline; 12. a pneumatic adjusting air valve; 13. a primary air blower; 14. a secondary air blower; 15. a pipe joint; 16. a bypass branch pipe; 17. and (5) a draught fan.

Detailed Description

The utility model is further described below in connection with the examples, which are not to be construed as limiting the utility model in any way, but rather as falling within the scope of the claims.

The specific embodiments of the present utility model are as follows: referring to fig. 1-2, a cold primary air bypass arrangement structure for a boiler combustion system comprises an air preheater 1, wherein one end of the air preheater 1 is provided with a primary air inlet 2 and a secondary air inlet 3, the other end of the air preheater 1 is provided with a primary air outlet 4 and a secondary air outlet 5, the upper side of the air preheater 1 is provided with a flue gas inlet pipe 6 connected with a boiler furnace exhaust pipe, the lower side of the air preheater 1 is provided with a flue gas outlet pipe 7, the primary air inlet 2 and the primary air outlet 4 are respectively connected with a cold primary air pipeline 8 and a hot primary air pipeline 9, a cold primary air bypass expansion pipeline 10 is communicated between the cold primary air pipeline 8 and the hot primary air pipeline 9, a pneumatic adjusting air valve 12 is arranged on the cold primary air bypass expansion pipeline 10, a conventional pneumatic adjusting air valve 12 which can be purchased in the market is arranged on the cold primary air bypass expansion pipeline 10, an electromagnetic valve on a gas pipe connected with the pneumatic adjusting air valve 12 can be controlled through a remote control circuit, and the opening angle of a throttle of the pneumatic adjusting air valve 12 is controlled through controlling the opening time of the electromagnetic valve, so that the flow rate of cold primary air in the cold primary air bypass expansion pipeline 10 is controlled.

In the cold primary air bypass arrangement structure for the boiler combustion system, the cold primary air bypass expansion pipeline 10 is expanded, the pneumatic adjusting air valve 12 capable of remotely controlling the opening angle of the air door is arranged on the cold primary air bypass expansion pipeline 10, whether the air-powder mixture is lower than 160 ℃ or not can be detected according to a temperature sensor, the opening angle of the pneumatic adjusting air valve 12 is automatically controlled through the controller on the control box, the flow velocity of cold primary air of the cold primary air bypass expansion pipeline 10 is controlled, and the purpose of adjusting the temperature of the air-powder mixture is achieved.

This a cold primary air bypass arrangement structure for boiler combustion system has increased pneumatic regulation blast gate 12, realizes remote control, ensures that under the circumstances that does not have the exhaust gas to reduce primary air bellows temperature when the coal pulverizer stops grinding, can open pneumatic regulation blast gate 12, increases the transport flow of cold primary air, and quick will send the powder temperature to below 160 ℃.

In this embodiment, the primary air duct 8 is provided with a primary air fan 13, and the connection point between the cold primary air bypass expansion duct 10 and the cold primary air duct 8 is located downstream of the primary air fan 13.

In this embodiment, a secondary air blower 14 is provided at the secondary air inlet 3.

In this embodiment, a pipe joint 15 is provided at the joint of the cold primary air pipe 8 and the primary air inlet 2, a bypass branch pipe 16 extending obliquely is provided at the side of the pipe joint 15, the bypass branch pipe 16 and the pipe joint 15 are welded into a three-way structure, and the cold primary air bypass expansion pipe 10 is communicated with the bypass branch pipe 16.

In this embodiment, the included angle between the bypass branch pipe 16 and the pipe joint 15 is smaller than 60 °, that is, the included angle between the air supply direction of the bypass branch pipe 16 and the linear air supply direction of the pipe joint 15 is smaller than 60 °, in this embodiment, the included angle between the bypass branch pipe 16 and the pipe joint 15 is designed to be 45 °, so that cold air in the cold primary air pipeline 8 enters the bypass branch pipe 16, and then is conveyed out by the cold primary air bypass expansion pipeline 10 on the bypass branch pipe 16, so as to reduce the resistance to the cold primary air.

In this embodiment, the flue gas outlet pipe 7 is connected with an induced draft fan 17 through a pipeline.

The foregoing is merely a preferred embodiment of the present utility model, and it should be noted that modifications and improvements can be made by those skilled in the art without departing from the structure of the present utility model, and these do not affect the effect of the implementation of the present utility model and the utility of the patent.

Claims (6)

1. The utility model provides a cold primary air bypass arrangement structure for boiler combustion system, includes air heater (1), its characterized in that, the one end of air heater (1) is equipped with primary air inlet (2), overgrate air inlet (3), the other end of air heater (1) is equipped with primary air outlet (4), overgrate air outlet (5), the upside of air heater (1) is equipped with flue gas intake pipe (6) of being connected with boiler furnace blast pipe, the downside of air heater (1) is equipped with flue gas exit tube (7), primary air inlet (2), primary air outlet (4) do not are connected with cold primary air pipeline (8), hot primary air pipeline (9) respectively, the intercommunication has cold primary air bypass dilatation pipeline (10) between cold primary air pipeline (8) and hot primary air pipeline (9), be equipped with pneumatic regulation air valve (12) on cold primary air bypass dilatation pipeline (10).

2. A cold primary air bypass arrangement for a boiler combustion system according to claim 1, characterized in that a primary air fan (13) is provided on the cold primary air duct (8), the connection point of the cold primary air bypass expansion duct (10) and the cold primary air duct (8) being located downstream of the primary air fan (13).

3. A cold primary air bypass arrangement for a boiler combustion system according to claim 1, characterized in that a secondary air fan (14) is provided at the secondary air inlet (3).

4. A cold primary air bypass arrangement for a boiler combustion system according to claim 1 or 2 or 3, characterized in that the cold primary air duct (8) is provided with a pipe joint (15) at the connection with the primary air inlet (2), the side of the pipe joint (15) is provided with a bypass branch (16) extending obliquely, the cold primary air bypass expansion duct (10) being in communication with the bypass branch (16).

5. A cold primary air bypass arrangement for a boiler combustion system according to claim 4, characterized in that the angle between the bypass branch (16) and the pipe connection (15) is less than 60 °.

6. A cold primary air bypass arrangement for a boiler combustion system according to claim 4, characterized in that the flue gas outlet pipe (7) is connected with an induced draft fan (17) by means of a pipe.

Images