CN115090379A - A medium-speed coal mill gas channel nozzle structure - Google Patents

Abstract

The invention relates to an air passage nozzle structure of a medium-speed coal mill, which comprises: the nozzle is obliquely and fixedly installed on a grinding disc of the coal mill, a nozzle air passage is arranged inside the nozzle and is coaxial with the side wall of the nozzle, an air inlet of the nozzle air passage is in a bell mouth shape, the side wall of an air outlet of the nozzle extends outwards in the circumferential direction to form an upper nozzle outer edge, and the bottom of the nozzle is close to the cylinder wall of the coal mill; the sealing baffle is fixedly arranged on the cylinder wall of the coal mill, the sealing baffle is positioned above the outer edge of the upper nozzle, and a horizontal gap is formed between the sealing baffle and the outer edge of the upper nozzle. The invention mainly aims to provide a nozzle structure of a medium-speed coal mill, which improves a primary air flow field and improves the capability of conveying pulverized coal, thereby improving the pulverizing efficiency of a pulverizing system.

Description

A medium-speed coal mill gas channel nozzle structure

technical field

The invention relates to a medium-speed coal pulverizer, in particular to a nozzle structure of the medium-speed coal pulverizer.

Background technique

The medium-speed vertical coal mill is a commonly used equipment in the pulverizing system of domestic coal-fired power plants. Its main function is to use grinding rollers to grind the raw coal into uniform pulverized coal, and the primary air enters the primary air chamber of the coal mill through the primary air duct. , the air-powder mixture that is ground into powder is conveyed upward through the nozzle. The primary air will bring the qualified fine powder out of the coal mill from the separator and send it to the burner for combustion, while the unqualified coal powder will fall back to the mill again. Grinding on rollers.

In the design and improvement of the coal mill, the determination of the nozzle flow rate of the coal mill is based on the average flow rate of the air ring calculated based on the inlet primary air flow rate and the nozzle flow area, without considering the different distribution of the primary air in the air chamber. uniformity. The uneven distribution of the primary air volume leads to disorder of the primary air flow field, the ability to transport pulverized coal decreases, and the pulverizing efficiency of the pulverizing system is reduced.

At the same time, the wind direction of the primary air at the air outlet of the nozzle and the static and dynamic gap, the radial angle between the air outlet of the nozzle and the grinding disc is usually close to a right angle, so that the wind direction of the primary air is relatively dispersed after entering the coal mill, which is easy to cause damage to the coal mill barrel wall and Blow damage to internal components such as separators.

In order to solve the above problems, a deflector is usually installed at the lower part of the nozzle, and the deflector only acts on the primary wind in a single direction, so the deflector only plays a guiding role to a certain extent, and has a limited effect on the uniformity of the primary air.

At the same time, in the prior art, in order to solve the problem of primary air blowing damage to internal components such as the barrel wall and separator of the coal mill, some baffles are installed at the static ring. The blowing damage of the cylinder wall has a certain effect, but the overall angle of the nozzle is still in the vertical direction, so it only plays a limiting role.

Therefore, the fixed inlet and outlet areas of the nozzle air passages, the single inlet and outlet wind directions, and the dynamic and static gaps in the vertical direction are not only easy to cause blowing damage to the inner structure such as the coal mill barrel wall and the separator above it, but also cause coal grinding. The flow field inside the machine is turbulent, and the operation cost and maintenance cost increase. Therefore, the uneven wind speed at the inlet and outlet of the primary air is likely to cause serious local wear, and to a large extent affects the ability of the coal mill to transport pulverized coal, thereby affecting the pulverizing efficiency of the pulverizing system.

SUMMARY OF THE INVENTION

The main purpose of the present invention is to provide a nozzle structure of a medium-speed coal pulverizer, improve the primary air flow field, improve the ability of conveying pulverized coal, and thereby improve the pulverizing efficiency of the pulverizing system.

In order to accomplish the above purpose, the present invention provides a medium-speed coal pulverizer air passage nozzle structure, comprising:

Nozzle, the nozzle is fixedly installed on the grinding disc of the coal mill, and there is a nozzle air channel inside the nozzle. The nozzle air channel is coaxial with the side wall of the nozzle. The air inlet of the nozzle air channel is bell-shaped. The outer edge of the upper nozzle extends circumferentially outward from the side wall, and the bottom of the nozzle is close to the barrel wall of the coal mill;

The sealing baffle is fixedly installed on the cylinder wall of the coal mill, the sealing baffle is located above the outer edge of the upper nozzle, and a horizontal gap is formed between the sealing baffle and the outer edge of the upper nozzle.

Preferably, an outer edge of the lower nozzle is provided on the side of the lower end of the nozzle close to the grinding disc, and the outer edge of the lower nozzle is screwed with the grinding disc.

Preferably, the ratio of the cross-sectional area at the air inlet of the nozzle to the cross-sectional area at the air outlet is greater than 4:1.

Preferably, the radial angle between the air outlet of the nozzle and the grinding disc is 85°-55°, and the circumferential angle is 30°-50°.

The beneficial effects of the present invention are:

(1) The inverted trumpet-shaped air passage structure of the nozzle set in this application, at the same time, the bottom of the nozzle is close to the cylinder wall, so that the air passage of the nozzle obtains a larger primary air inlet area, which is helpful for the uniform arrangement of the primary air; when the primary air enters After the nozzle air passage, through the venturi action, the outlet speed of the primary air passing through the air passage is increased, thereby improving the primary air flow field, improving the ability of conveying pulverized coal, and thus improving the pulverizing efficiency of the pulverizing system.

(2) The inclined arrangement of the nozzle air passage of the present application is to achieve the purpose of uniform powder feeding, and at the same time reduce the blowing damage of the primary air to the barrel wall of the coal mill, the dynamic and static ring sealing structure arranged on the barrel wall and the grinding roller frame. At the same time, due to the disturbance of the radial angle of the primary air, the pulverized coal particles with larger particle size are blown back to the center of the grinding table and ground again to increase the pulverized coal circulation rate and improve the fineness and uniformity of the pulverized coal.

(3) The sealing baffle of the air passage structure is fixed on the cylinder wall in the area above the outer edge of the upper nozzle, forming a horizontal gap with the outer edge of the upper nozzle. At the same time, there is also a vertical gap between the nozzle and the cylinder wall. The gap in the direction of the primary air enters the space enclosed between the sealing structure and the nozzle through the vertical gap, and the primary air enters the coal mill through the horizontal gap between the sealing baffle and the outer edge of the upper nozzle. Thereby reducing the direct blow damage to the cylinder wall.

(4) By fixing the upper and lower bolts of the nozzle, the nozzle is more stable, and the vibration of the nozzle is prevented due to the rapid change of the wind speed when the primary air passes through the nozzle air passage.

Description of drawings

The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

FIG. 1 is a schematic structural diagram of the nozzle structure of the medium-speed coal pulverizer of the present invention.

Description of reference numerals

110, cylinder wall; 120, grinding disc; 130, sealing baffle;

200, the nozzle; 210, the air passage of the nozzle; 220, the outer edge of the upper nozzle;

230, the outer edge of the lower nozzle; 240, the air inlet; 250, the air outlet.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Many specific details are set forth in the following description to facilitate a full understanding of the present invention, but the present invention can also be implemented in other ways different from those described herein, and those skilled in the art can do so without departing from the connotation of the present invention. Similar promotion, therefore, the present invention is not limited by the specific embodiments disclosed below.

As shown in FIG. 1 , this embodiment provides an air passage nozzle structure of a medium-speed coal mill, and the coal mill includes a cylinder wall 110 and a grinding disc 120 . The nozzle 200 is fixedly installed on the grinding disc 120 , and the sealing baffle 130 is fixedly installed on the cylinder wall 110 .

Specifically, in this embodiment, as shown in FIG. 1 , the nozzle 200 is obliquely and fixedly installed on the grinding disc 120 of the coal mill, and a nozzle air passage 210 is provided inside the nozzle 200, and the nozzle air passage 210 is connected to the side of the nozzle. The walls are arranged coaxially, so the nozzle air passage 210 and the grinding disc 120 are also arranged at a certain angle. Preferably, the radial angle between the air outlet 250 of the nozzle 200 (ie the nozzle air channel 210 ) and the grinding disc 120 is 85°˜55°, and the circumferential angle is 30°˜50°. Meanwhile, the air inlet 240 of the nozzle air passage 210 is in the shape of a bell mouth. Preferably, the ratio of the cross-sectional area at the air inlet 240 of the nozzle 200 to the cross-sectional area at the air outlet 250 is greater than 4:1, wherein the cross-sectional area at the air inlet 240 of the nozzle 200 is the air inlet in FIG. 1 As shown by the dashed line at 240 , the cross-sectional area at the air outlet 250 is shown by the dashed line at the air outlet 250 in FIG. 1 . That is, the cross-sectional area of the air inlet 240 of the nozzle 200 is the largest cross-sectional area at the air inlet, and the cross-sectional area at the air outlet 250 is the smallest cross-sectional area at the air outlet.

The inverted trumpet-shaped nozzle air passage 210 provided in this embodiment enables the nozzle air passage 210 to obtain a larger primary air inlet area, which is helpful for the uniform arrangement of the primary air; when the primary air enters the nozzle air passage 210, it passes through the venturi It can improve the outlet speed of the primary air through the nozzle air passage 210, thereby improving the primary air flow field, improving the ability to transport pulverized coal, and thus improving the pulverizing efficiency of the pulverizing system. In addition, the inclined arrangement of the nozzle air passage 210 in this embodiment is to achieve the purpose of uniform powder feeding, and at the same time reduce the impact of the primary air on the barrel wall 110 of the coal mill and the dynamic and static ring sealing structure (not shown in the figure) disposed on the barrel wall 110 out) and the blowing damage of the grinding roller stand (not shown in the figure). At the same time, due to the disturbance of the radial angle of the primary air, the pulverized coal particles with larger particle size are blown back to the center of the grinding table and ground again to increase the pulverized coal circulation rate and improve the fineness and uniformity of the pulverized coal.

In this embodiment, the side wall of the air outlet 250 of the nozzle 200 extends circumferentially outward with an upper nozzle outer edge 220 , the lower nozzle outer edge 230 is provided on the side of the lower end of the nozzle 200 close to the grinding disc, and the lower nozzle outer edge 230 Screwed to the grinding disc. In this embodiment, by fixing the upper and lower bolts of the nozzle 200 , the nozzle 200 is more stable, and the vibration of the nozzle 200 is prevented due to the rapid change of the wind speed when the primary air passes through the nozzle air passage 210 .

In this embodiment, as shown in FIG. 1 , the sealing baffle 130 is fixedly installed on the barrel wall 110 of the coal mill, and the sealing baffle 130 is located above the outer edge 220 of the upper nozzle, and the sealing baffle 130 is connected to the outer edge of the upper nozzle. A horizontal gap is formed between the edges 220 . At the same time, the bottom of the nozzle 200 is close to the barrel wall 110 of the coal mill, so that a vertical gap is also formed between the bottom of the nozzle 200 and the barrel wall 110 . The sealing baffle 130 of this embodiment is fixed on the cylinder wall in the area above the outer edge of the upper nozzle 220, and forms a horizontal gap with the outer edge of the upper nozzle, thereby forming a horizontal air channel structure. At the same time, the nozzle 200 There is also a vertical gap between the cylinder wall 110, so that the primary air enters the space enclosed by the cylinder wall 110, the sealing baffle 130 and the nozzle 200 through the vertical gap, and the primary air is recirculated. The coal pulverizer is entered through the horizontal gap between the sealing baffle 130 and the outer edge 220 of the upper nozzle, thereby reducing the direct blow damage to the drum wall and its components located above the drum wall.

Obviously, the described embodiments are only some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Claims (4)

1. The utility model provides a medium speed coal pulverizer air flue nozzle structure which characterized in that includes:

the nozzle is obliquely and fixedly installed on a grinding disc of the coal mill, a nozzle air passage is arranged in the nozzle, the nozzle air passage is coaxial with the side wall of the nozzle, an air inlet of the nozzle air passage is in a bell mouth shape, an upper nozzle outer edge extends outwards in the circumferential direction of the side wall at an air outlet of the nozzle, and the bottom of the nozzle is close to the cylinder wall of the coal mill;

the sealing baffle is fixedly arranged on the cylinder wall of the coal mill, the sealing baffle is positioned above the outer edge of the upper nozzle, and a horizontal gap is formed between the sealing baffle and the outer edge of the upper nozzle.

2. The medium speed coal mill air flue nozzle structure of claim 1, wherein a lower nozzle outer edge is arranged on one side of the lower end of the nozzle close to the grinding disc, and the lower nozzle outer edge is in threaded connection with the grinding disc.

3. The medium speed coal mill air passage nozzle structure of claim 1, wherein the ratio of the cross-sectional area at the air inlet to the cross-sectional area at the air outlet of the nozzle is greater than 4: 1.

4. The medium speed coal mill air flue nozzle structure according to claim 1, wherein the air outlet of the nozzle forms an angle of 85-55 ° with the radial direction of the grinding disc, and forms an angle of 30-50 ° with the circumferential direction.

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