CN202253618U - Controllable backflow type pulverized coal burner - Google Patents

Abstract

The utility model belongs to the field of pulverized coal combustion devices, and particularly discloses a controllable backflow type pulverized coal burner. The controllable return type pulverized coal burner includes a primary air pipe, and is characterized in that: the last elbow of the primary air pipe toward the furnace is connected with a pulverized coal concentration distributor, and the end of the pulverized coal concentration distributor is connected with a vertically arranged The underpants pipe, the upper pipe of the underpants pipe is connected to the DC burner through the light coal powder flow nozzle, the lower pipe of the pants pipe is connected to the pre-combustion chamber through the thick coal powder flow nozzle, and the direct-flow combustion chamber and the pre-combustion chamber are respectively connected to the furnace. The utility model has a wide range of adaptability to coal types and coal qualities, strong ability to prevent fire and stable combustion, long service life to prevent burning and wear, simple structure, convenient refitting and arrangement, can effectively reduce the emission of nitrogen oxides, and is beneficial to environmental protection.

Description

Controlled return type pulverized coal burner

(1) Technical field

The utility model belongs to the field of pulverized coal combustion devices, in particular to a controllable backflow pulverized coal burner.

(2) Background technology

At present, the thermal coal situation of thermal power plants in China is very tense. The amount of coal that meets the design coal types of power plant boilers is small, and a large amount of incoming coal deviates from the design and efficiency coal types. For example: (1) Boiler of a factory in the south The resources of bituminous coal, the originally designed type of coal, have been exhausted, and they are forced to use lean coal and anthracite; (2) The coal from a factory in the north is very messy, including Russian lean coal, North Korean anthracite, Indonesian bituminous coal, Australian bituminous coal, etc.; (3 ) The designed and effective nuclear coal used by the boiler in a factory is bituminous coal from a large local mine. The quality of the coal is very good, but the amount of incoming coal only accounts for 40% of the total incoming coal, and the remaining 60% of incoming coal has an ash content of about 40%. Low-quality bituminous coal with a calorific value of more than 3,000 calories.

In short, many thermal power plants in the country have the above situation. Due to the messy incoming coal, it is very difficult to mix it evenly. This results in the ups and downs of the coal immersed in the furnace. Therefore, the boiler often has unstable combustion, fire extinguishing, coking, Accidents and abnormal situations such as burnt out of the burner, overheating of the superheater, explosion of the fly ash combustibles, explosion of the pulverizing system, etc. occurred.

At the same time, many pulverized coal burners currently in use cannot adapt to changes in the current situation of electric coal, such as: (1) For ordinary once-through burners that use bituminous coal, when there is little normal bituminous coal, 50% of inferior quality must be blended Bituminous coal, and when faults occur due to uneven blending, the negative pressure of the furnace will suddenly become unstable and boiler fires will occur; (2) For block-type, louver-type and other thick-lean pulverized coal burners that use low-quality bituminous coal and lean coal, when When the amount of lean coal is small and some anthracite with very low volatile content must be blended, due to the uneven blending time, there are often accidents and abnormal situations such as boiler fire extinguishing, combustion center rise, main steam overtemperature, superheater tube burst, etc. happened. (3) For boilers burning lean coal and low-quality lean coal with low volatile content, double-channel burners are used. If the coal into the furnace is messy, there are bituminous coal, lean coal, and anthracite, and sometimes these coals are mixed unevenly. Accidents and abnormalities such as burner burnout and coking will occur in the boiler.

While the above-mentioned burners are not suitable for the change of the coal type in the furnace, there are still some deficiencies. For example, the block-type and louver-type dense and light pulverized coal burners are difficult to design and easy to wear. When the boiler is refitted, it is vulnerable to site conditions. It is difficult to restrict the layout. For the elbow of the primary air pipe in the vertical direction, the horizontal concentration cannot be realized; the coal stability performance of the double-channel pulverized coal burner is very good. It divides the air powder flow in the primary air pipe into two streams from the rectangular combustion chamber The upper and lower inlets enter the pre-combustion chamber and then enter the furnace from the exit. Under the high-speed state, the two streams of pulverized coal flow form a negative pressure zone in the middle of the pre-combustion chamber, resulting in strong hot flue gas backflow. The burner burns lean coal or volatile matter. Very low quality lean coal is fine, but a mixture of lean coal and bituminous coal is very easy to burn out.

(3) Contents of the invention

In order to make up for the deficiencies of the prior art, the utility model provides a controllable backflow pulverized coal burner which is convenient for refitting and arrangement, has a long service life, and has strong fire prevention and stable combustion capabilities.

The utility model is achieved through the following technical solutions:

A controllable return type pulverized coal burner, including a primary air pipe, characterized in that: the last elbow of the primary air pipe in the direction of the furnace is connected with a pulverized coal thick-lean distributor, and the end of the pulverized coal thick-lean distributor is connected with a vertically arranged The upper tube of the pants tube is connected to the DC burner through the light pulverized coal flow nozzle, and the lower tube of the pants tube is connected to the pre-combustion chamber through the thick coal powder gas flow nozzle, and the DC combustion chamber and the pre-combustion chamber are respectively connected to the furnace.

The utility model utilizes the centrifugal force of the last elbow of the primary air pipe toward the furnace to divide the pulverized coal airflow in the primary air pipe into two streams of pulverized coal airflow, thick and thin, and enters the underpants pipe after passing through the pulverized coal thick and light distributor, so that the upper pipe is ventilated. The pulverized coal airflow is combusted by the once-through burner, and the dense pulverized coal airflow is passed through the lower pipe, combusted in the pre-combustion chamber, and then sent to the furnace in a concentrated manner, which realizes the purpose of coal quality treatment and multi-range application.

The more optimal scheme of the present utility model is:

In order to make the burner have wider adaptability to coal types and good anti-burning performance, a control air nozzle is arranged on the rear upper part of the pre-combustion chamber, and the control air box connected to the control air nozzle is connected with the external control air pipe. An automatic regulating door is installed on the pipe, and the automatic regulating door adjusts the air volume according to the temperature of the pre-combustion chamber through the hot spot temperature measuring device and program installed on the pre-combustion chamber to realize the control of the size of the return flow, so that the pre-combustion The temperature of the chamber is controlled within a safe range.

The combustion of the dense pulverized coal flow in the pre-combustion chamber is a reducing atmosphere, and the light pulverized coal flow is also a reducing atmosphere. Therefore, the burner has the function of effectively reducing nitrogen oxides.

The biggest invention point of this utility model is to overcome the shortcomings of some original burners, and combine the technologies of thick and thin combustion, pre-combustion chamber combustion, secondary air controllable heat return, etc., so that the burner has a wide range of coal types Coal quality adaptability and good resistance to burning loss.

The utility model has a wide range of adaptability to coal types and coal qualities, strong ability to prevent fire and stable combustion, long service life to prevent burning and wear, simple structure, convenient refitting and arrangement, can effectively reduce the emission of nitrogen oxides, and is beneficial to environmental protection.

(4) Description of drawings

Below in conjunction with accompanying drawing, the utility model is further described.

Fig. 1 is the main view structure schematic diagram of the utility model;

Fig. 2 is a left view structure diagram of the utility model.

In the figure, 1 primary air duct, 2 elbow, 3 pulverized coal concentration distributor, 4 underpants pipe, 5 control bellows, 6 thick pulverized coal air flow nozzle, 7 control air nozzle, 8 pre-combustion chamber, 9 light pulverized coal air flow nozzle , 10 automatically adjust the door, 11 control the air duct. the

(5) Specific implementation methods

Accompanying drawing is a kind of concrete embodiment of the utility model. This embodiment includes a primary air duct 1, the last elbow 2 of the primary air duct 1 towards the furnace is connected with a pulverized coal concentration distributor 3, and the end of the pulverized coal concentration distributor 3 is connected with a vertically arranged underpants pipe 4, the underpants pipe The upper pipe of 4 communicates with the DC burner through the light coal powder flow nozzle 9, and the lower tube of the pants pipe 4 communicates with the pre-combustion chamber 8 through the dense coal powder gas flow nozzle 6, and the direct-flow combustion chamber and the pre-combustion chamber 8 communicate with the furnace respectively; The upper rear of the pre-combustion chamber 8 is provided with a control wind spout 7, and the control bellows 5 communicating with the control wind spout 7 is connected with the external control air duct 11, and the control air duct 11 is equipped with an automatic regulating door 10.

Utilizing the centrifugal force of the last elbow 2 of the primary air duct 1 towards the furnace, the pulverized coal flow in the pipe is divided into two streams of pulverized coal, thick and thin; these two streams of pulverized coal pass through a thick and thin distributor 3 and then enter the vertically arranged pants pipe 4. The air flow of light pulverized coal is in the upper pipe, and the air flow of dense pulverized coal in the lower pipe; the dense pulverized coal air flow in the lower pipe enters the pre-combustion chamber 8 through the entrance below the rectangular (or circular) pre-combustion chamber 8, and then enters the furnace from its exit . When the dense pulverized coal flow passes through the bottom of the pre-combustion chamber 8 at a speed of 23-26m/s, a negative pressure zone will be formed in the pre-combustion chamber 8, which will cause strong hot flue gas backflow, so that the burner has It has a fairly good combustion stability; the light pulverized coal gas flow in the lower tube passes through a direct-flow burner and directly enters the furnace for combustion

In order for the burner to have a wider adaptability to coal types and good anti-burning performance, we added a control air nozzle 7 on the rear upper part of the pre-combustion chamber 8, and the control air enters from the connecting pipe between the control air box 5 and the tuyere In the pre-combustion chamber, the control air duct 11 is provided with an automatic adjustment door 10, which adjusts the air volume according to the temperature of the pre-combustion chamber through the thermoelectric temperature measuring device and program installed on the pre-combustion chamber 8 to The size of the return flow can be controlled, so that the temperature of the pre-combustion chamber can be controlled within a safe range.

The utility model is well combined with technologies such as thick and thin combustion, pre-combustion chamber combustion, and secondary air controllable heat return. The automatic control and adjustment of the return flow rate, the return area and the position of the return area can enhance the stable combustion performance of the burner to the boiler, prevent the boiler from extinguishing fire and prevent the burner from burning, and can effectively improve the safety and economy of the boiler operation. At the same time, it can effectively reduce the emission of nitrogen oxides.

Claims (2)

1. A controllable backflow pulverized coal burner, including a primary air duct (1), characterized in that: the last elbow (2) of the primary air duct (1) toward the furnace is connected with a pulverized coal concentration distributor (3), the end of the pulverized coal thick-lean distributor (3) is connected with a vertically arranged underpants pipe (4), and the upper pipe of the underpants pipe (4) is connected to the DC burner through the light pulverized coal airflow nozzle (9), and the underpants pipe (4) ) is connected to the pre-combustion chamber (8) through the dense pulverized coal flow nozzle (6), and the direct-flow combustion chamber and the pre-combustion chamber (8) are respectively connected to the furnace. 2. The controllable backflow type pulverized coal burner according to claim 1, characterized in that: a control air nozzle (7) is arranged on the upper rear of the pre-combustion chamber (8), and is connected to the control air nozzle (7). The control bellows (5) is connected with the external control air duct (11), and an automatic adjustment door (10) is installed on the control air duct (11).

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