Two-stage dense-thin separation pulverized coal distributor

Abstract

The utility model discloses a two-stage dense-thin separation pulverized coal distributor which is used for combustion equipment of a coal-fired boiler, a connecting pipe (1) is used for being connected with a pulverized coal pipeline, and the connecting pipe (1), a first-stage separation chamber (2), a second-stage separation chamber (4) and a dense powder chamber (7) are sequentially connected; a plurality of supporting plates (3) are arranged in the end part, close to the primary separation chamber (2), of the secondary separation chamber (4), the supporting plates are uniformly distributed, two ends of a central body (6) are of cone structures, a non-cone part at one end is fixedly connected with the secondary separation chamber through the supporting plates, and a cone at the other end of the central body extends into the diluted powder chamber (7) for a certain distance; a plurality of deflecting separating plates (5) are fixedly connected with the central body (6) and are uniformly distributed along the circumferential direction; the thin powder chamber (8) is fixedly connected with the thick powder chamber (7); and the inlet section of the thin powder chamber (8) extends into the thick powder chamber (7) for a certain distance. Primary air pulverized coal airflow of a pulverized coal pipeline is divided into thick pulverized coal airflow and thin pulverized coal airflow, and the thick pulverized coal airflow and the thin pulverized coal airflow are independently led out through the two pulverized coal chambers respectively.

Description

Technical Field

[0001] The utility model relates to a two-stage thick-thin separation coal powder distributor. Background Art

[0002] With the rapid development of my country's renewable energy power generation technology, deep peak regulation of thermal power units and the consumption of renewable energy power generation have become the normal operation of many thermal power plants. In order to enhance the stable combustion ability of coal-fired boilers in thermal power plants under low-load conditions, increasing the concentration of pulverized coal in the primary air pulverized coal airflow has become one of the main technical measures. The thick and thin type pulverized coal burner has been successfully applied to the combustion equipment of coal-fired boilers. The common method is to add a guide device in the nozzle of the pulverized coal burner or use the centrifugal effect of the elbow to divide the primary air pulverized coal airflow in the burner into thick and thin two streams. The pulverized coal airflow under rich fuel conditions requires less ignition heat. After the ignition of the thick pulverized coal airflow, it can also provide an ignition heat source for the thin pulverized coal airflow, so that the combustion stability of the entire flame and the low-load stable combustion ability of the pulverized coal burner are enhanced. However, the existing thick and thin type pulverized coal burner does not achieve complete independence of the thick side and the thin side. There is still a certain degree of mixing at the burner nozzle, which reduces the actual effect of thick and thin separation. Some of the thick and thin separation devices installed on the pulverized coal pipeline adopt the principle of elbow centrifugal action, and some adopt built-in baffle separation. However, due to the centrifugal effect of the elbow, the concentration ratio of the elbow type is generally low; the built-in baffle type does not solve the problem of remixing in the channel, and the actual separation effect is not good. Especially when the boiler burns low-volatile coal, stable and independent concentrated and diluted air flows need to be sent to the furnace separately to achieve a good level of low-load stable combustion without adding combustion aids. Summary of the invention

[0003] The utility model provides a two-stage thick-thin separation coal powder distributor, which can realize the separation of the primary air coal powder airflow of the coal powder pipeline into two streams of thick powder airflow and thin powder airflow, which are independently led out through two powder chambers and sprayed into the furnace. The two airflows separated internally are not easy to interfere with mixing, which greatly improves the airflow concentration ratio, separation stability and separation effect.

[0004] In order to achieve the above purpose, the technical solution of the utility model is:

[0005] A two-stage thick and thin separation coal powder distributor is a combustion device for a coal-fired boiler, the distributor comprises a connecting pipe, a primary separation chamber, a support plate, a secondary separation chamber, a folding separation plate, a central body, a thick powder chamber and a thin powder chamber; the connecting pipe is used to connect to the coal powder pipeline, and the connecting pipe, the primary separation chamber, the secondary separation chamber and the thick powder chamber are connected in sequence; a plurality of support plates are arranged in the secondary separation chamber near the end of the primary separation chamber, the support plates are evenly distributed, the two ends of the central body are cone structures, the non-conical part at one end is fixedly connected to the secondary separation chamber through the support plate, and the cone at the other end of the central body extends into the thin powder chamber for a certain distance; a plurality of folding separation plates are fixedly connected to the central body and evenly distributed along the circumferential direction; one end of the folding separation plate is parallel to the axis direction of the central body, and the other end forms a certain angle with the axis of the central body; the thin powder chamber is fixedly connected to the thick powder chamber, and the entrance section of the thin powder chamber extends into the thick powder chamber for a certain distance.

[0006] Preferably, the central axis of the light powder chamber and the dark powder chamber form an acute angle.

[0007] Preferably, the primary separation chamber is of a flared structure, with an inlet diameter smaller than an outlet diameter.

[0008] Preferably, the inlet of the concentrated powder chamber is an expanding structure, and the outlet is a contracting structure.

[0009] Preferably, the connecting pipe, the primary separation chamber, the secondary separation chamber and the concentrated powder chamber are connected by a flange structure.

[0010] Preferably, the outlets of the thick powder chamber and the thin powder chamber are both equipped with adjustable shrinkage holes.

[0011] The utility model has the advantages that when the primary air pulverized coal airflow flows through the primary separation chamber and the secondary separation chamber, it is subjected to the impact separation effect of the cone section of the central body and the cyclone separation effect of the folded separation plate, realizing two-stage thick-thin separation, forming an annular pulverized coal concentration distribution with thick outside and thin inside on the cross section of the secondary separation chamber, and the airflow with high pulverized coal concentration on the outside is led out from the thick powder chamber through the joint guidance of the secondary separation chamber shell and the central body, and the airflow with low pulverized coal concentration on the inside is led out from the thin powder chamber. Compared with the original primary air pulverized coal airflow, the pulverized coal concentration of the thick pulverized coal airflow is greatly improved. Especially when the boiler is running at a low load or the quality of the coal used is deteriorated, the pulverized coal ignition will be difficult due to the increase of the air-to-coal ratio of the primary air pulverized coal airflow at the outlet of the pulverizer. The air-to-coal ratio of the thick pulverized coal airflow after the thick-thin separation of the utility model is significantly reduced, exceeding the initial design level, which will significantly reduce the ignition heat of the airflow, which is very beneficial to the rapid ignition of pulverized coal and stable combustion at low load. When the coal type changes and the unit load changes, it is beneficial to improve the stability and anti-interference ability of the combustion in the furnace. On the other hand, after the pulverized coal concentration in the dense pulverized coal side airflow increases, the fuel-rich combustion condition can reduce the NOx emission value, allowing the boiler to achieve a better environmental protection level. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1A schematic diagram of the structure of a two-stage thick-thin separation pulverized coal distributor;

[0013] Figure 2 A schematic diagram of the structure of another two-stage thick-thin separation pulverized coal distributor.

[0014] Figure numerals: connecting pipe 1, primary separation chamber 2, supporting plate 3, secondary separation chamber 4, folding separation plate 5, central body 6, thick powder chamber 7, thin powder chamber 8, adjustable shrinkage hole 9. DETAILED DESCRIPTION

[0015] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods, but the present invention is not limited to the following embodiments.

[0016] Example 1

[0017] like Figure 1 The figure shows a schematic diagram of the structure of a two-stage thick-thin separation pulverized coal distributor. The two-stage thick-thin separation pulverized coal distributor is composed of a pipe 1, a primary separation chamber 2, a support plate 3, a secondary separation chamber 4, a folding separation plate 5, a central body 6, a thick powder chamber 7 and a thin powder chamber 8. The primary separation chamber 2 is a flared structure, and the inlet diameter is smaller than the outlet diameter. The two ends of the central body 6 are cone structures, and one end is fixedly connected to the secondary separation chamber 4 through the support plate 3. The support plate 3 is generally four pieces, which are evenly distributed along the circumference. The cone at the other end of the central body 6 extends into the thin powder chamber 8 for a certain distance. Several folding separation plates 5 are fixedly connected to the central body 6 and are evenly distributed along the circumference, generally 6 to 10 pieces. One end of the folding separation plate 5 is along the axis direction of the central body 6, and the other end is at a certain angle to the axis of the central body 6. The thin powder chamber 8 is fixedly connected to the thick powder chamber 7. The inlet of the thick powder chamber 7 is a flared structure, and the outlet is a contracted structure. The inlet section of the thin powder chamber 8 extends into the thick powder chamber 7 for a certain distance, and the outlet is a contracted structure. The pipe 1 is used to connect with the pulverized coal pipeline, which can be connected by butt welding or flange structure. The pipe 1, the first separation chamber 2, the second separation chamber 4 and the concentrated powder chamber 7 are generally connected by flange structure, which is convenient for disassembly and maintenance. The two-stage concentrated and thin separation pulverized coal distributor can be manufactured by casting technology or by steel plate welding.

[0018] After the primary air pulverized coal airflow enters the primary separation chamber 2 from the connecting pipe 1, the pulverized coal particles will collide with the cone of the inlet section of the central body 6, and rebound and gather to the outside of the flow section. In this way, the pulverized coal concentration on the outside of the primary air pulverized coal airflow is high, and the pulverized coal concentration on the inside is low, forming the first-level thick-thin separation airflow. After the first-level thick-thin separation airflow enters the secondary separation chamber 4, it is rotated by the deflection separation plate 5. Under the action of centrifugal force, the pulverized coal particles further gather to the outside of the airflow, forming the second-level thick-thin separation airflow. After the above two-level thick-thin separation, the primary air pulverized coal forms an annular high-concentration ratio thick-thin separation state airflow in the secondary separation chamber 4, with a very high coal powder concentration on the outside and a very low coal powder concentration on the inside. Under the guidance of the central body 6 and the outer shell of the secondary separation chamber 4, the above-mentioned annular high-concentration ratio thick-thin separation state airflow flows all the way to the entrance of the thick powder chamber 7, and the outer thick powder airflow enters the thick powder chamber 7 from the annular channel between the thick powder chamber 7 and the thin powder chamber 8 and is then led out. The inner light powder airflow enters the light powder chamber 8 from the annular channel between the light powder chamber 8 and the cone section of the central body 6 and is then led out.

[0019] After the above process, the initial primary air pulverized coal airflow is separated into two streams, a dense pulverized coal airflow and a light pulverized coal airflow, which can be introduced into the boiler pulverized coal burner independently. The ratio of the pulverized coal flow of the dense and light airflows can reach 7:3 to 9:1, the pulverized coal concentration of the dense pulverized coal airflow is greatly increased, the air-coal ratio is significantly reduced, the ignition heat is significantly reduced, and the ignition and stable combustion capabilities are greatly enhanced, which is conducive to improving the boiler's ability to stabilize combustion without adding combustion aids under low load and the combustion adaptability to high activation energy coals, and can reduce the NOx generated in the early stage of pulverized coal combustion.

[0020] Example 2

[0021] like Figure 2 As shown, it is a schematic diagram of the structure of another two-stage thick and thin separation coal powder distributor. The difference between this embodiment and embodiment 1 is that the outlets of the thick powder chamber 7 and the thin powder chamber 8 are both equipped with adjustable shrinkage holes 9. By adjusting the opening of the adjustable shrinkage holes 9, the resistance of the thick powder airflow and the thin powder airflow can be adjusted respectively to achieve resistance balance or the resistance difference required by the design. The other structures are the same as embodiment 1.

[0022] The above is a preferred embodiment of the present utility model. It should be pointed out that for ordinary technicians in this technical field, several improvements and improvements can be made without departing from the principle of the present utility model. These improvements and improvements are also regarded as the protection scope of the present utility model. The protection scope of the present utility model shall be based on the definition of the claims.

Claims

1. A two-stage thick-thin separation pulverized coal distributor, used for combustion equipment of coal-fired boilers, characterized by: The distributor comprises a pipe (1), a primary separation chamber (2), a support plate (3), a secondary separation chamber (4), a folding separation plate (5), a central body (6), a thick powder chamber (7) and a thin powder chamber (8); The connecting pipe (1) is used to connect to the pulverized coal pipeline, and the connecting pipe (1), the primary separation chamber (2), the secondary separation chamber (4) and the concentrated powder chamber (7) are connected in sequence; A plurality of support plates (3) are arranged in the secondary separation chamber (4) near the end of the primary separation chamber (2), and the support plates are evenly distributed. Both ends of the central body (6) are cone structures, and the non-conical part at one end is fixedly connected to the secondary separation chamber through the support plate. The cone at the other end of the central body extends into the pale powder chamber (8) for a certain distance. A plurality of folding separation plates (5) are fixedly connected to the central body (6) and are evenly distributed along the circumferential direction; one end of the folding separation plate is parallel to the axis direction of the central body (6), and the other end forms a certain angle with the axis of the central body (6); The light powder chamber (8) is fixedly connected to the thick powder chamber (7), and the entrance section of the light powder chamber (8) extends into the thick powder chamber (7) by a certain distance.

2. A two-stage thick-thin separation pulverized coal distributor according to claim 1, characterized in that: The light powder chamber (8) forms an acute angle with the central axis of the thick powder chamber (7).

3. A two-stage thick-thin separation pulverized coal distributor according to claim 2, characterized in that: The primary separation chamber (2) is of a flared structure, and the inlet diameter is smaller than the outlet diameter.

4. A two-stage thick-thin separation pulverized coal distributor according to claim 2, characterized in that: The inlet of the concentrated powder chamber (7) is an expanding structure, and the outlet is a contracting structure.

5. A two-stage thick-thin separation pulverized coal distributor according to claim 2, characterized in that: The pipe (1), the primary separation chamber (2), the secondary separation chamber (4) and the concentrated powder chamber (7) are connected by a flange structure.

6. A two-stage thick-thin separation pulverized coal distributor according to claim 2, characterized in that: The outlets of the thick powder chamber (7) and the thin powder chamber (8) are both provided with adjustable shrinkage holes (9).

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