Raw coal drying device for medium-speed mill

Abstract

The utility model relates to a medium-speed mill raw coal drying device which comprises a coal mixing box, and the coal mixing box is connected between a first coal dropping pipe and a second coal dropping pipe to jointly form a coal dropping pipe outside a coal mill. One side of the coal mixing box is connected with the hot air pipeline, the side, away from the coal mixing box, of the hot air pipeline is connected with a hot primary air mother pipe, and a mixing area of hot primary air and raw coal is formed in the coal mixing box. The raw coal drying device is installed on the coal falling pipe outside the coal mill, the raw coal is dried to a certain degree before entering the coal mill, hot primary air can be directly mixed with the raw coal by directly connecting the hot air pipeline to the coal mixing box, the contact efficiency of hot air and the raw coal is improved through the design, and the raw coal drying efficiency is improved. When the raw coal falls on the millstone, the water content of the raw coal is reduced, so that the output of the coal mill is obviously improved, and the device is particularly suitable for the raw coal with high water content.

Description

Technical Field

[0001] The utility model relates to the technical field of coal powder milling, and more specifically, to a medium-speed coal mill raw coal drying device. Background Art

[0002] The structure of the existing medium-speed coal mill is shown in the appendix Figure 2 , and the raw coal enters the inside of the coal mill from the coal dropping pipe 10 and falls on the grinding table 11. As the grinding table 11 rotates, the raw coal spreads to the area of the grinding roller 12 and is ground between the grinding table 11 and the grinding roller 12. The ground raw coal overflows from the outer edge of the grinding table 11 and is mixed with the hot primary air that enters the inside of the coal mill through the driven air ring 13 from the hot primary air inlet 14. The hot primary air dries the raw coal and transports the fine coal powder to the separator 15. After being separated by the separator 15, the qualified coal powder is discharged from the coal mill, and the unqualified coal powder is returned to the grinding table 11 for re-grinding.

[0003] The raw coal contains a certain amount of moisture. Usually, the moisture content of the as-received raw coal (referring to the moisture content in the coal directly mined from the mine without any treatment) is between 5% and 30%. After the moisture content of the raw coal exceeds 10%, it has a great impact on the coal powder production capacity (output) of the coal mill. In DL / T5145-2012 "Technical Regulations for Design and Calculation of Coal Powder Preparation Systems in Thermal Power Plants", in Section 4.3, Performance Parameter Calculation of Wheel-Type Coal Mills (MPS), in 4.3.1, Calculation of Grinding Output, in the first part, Calculation of Grinding Output of Medium-Speed Coal Mills,

[0004] M t ≤10%, the correction coefficient f of the moisture content of the raw coal on the output of the coal mill M =1.0,

[0005] M t >10%, f M =1.0+(10 - M t )×0.0114;

[0006] Calculated according to the above formula, when the moisture content of the raw coal is 20%, f M =0.886, when the moisture content of the raw coal is 25%, f M =0.829. It can be seen that as the moisture content of the raw coal increases, the output of the coal mill decreases. The output with a moisture content of 25% decreases by 1 - 0.829 / 0.886 = 6.43% compared with that at 20%. Thus, it can be seen that reducing the moisture content of the raw coal entering the mill has an obvious effect on improving the output of the coal mill.

[0007] Therefore, how to reduce the moisture content of the raw coal entering the mill is an urgent problem to be solved by those skilled in the art. Content of the Utility Model

[0008] To this end, the purpose of the present utility model is to provide a medium-speed coal mill raw coal drying device, which reduces the moisture content of the raw coal entering the mill and improves the powder-making capacity.

[0009] The technical solution of the present utility model is a medium-speed coal mill raw coal drying device, including:

[0010] A coal mixing box, which is connected between the first coal dropping pipe and the second coal dropping pipe, and together constitutes the coal dropping pipe outside the coal mill;

[0011] A hot air pipeline, one side of the coal mixing box is connected to the hot air pipeline, the side of the hot air pipeline far from the coal mixing box is connected to the primary hot air main pipe, and a mixing area of the primary hot air and the raw coal is formed inside the coal mixing box.

[0012] According to the technical solution of the present utility model, a regulating valve is installed on the hot air pipeline.

[0013] According to the technical solution of the present utility model, the coal mixing box is vertically arranged, having a first flange connected to the first coal dropping pipe at its top, a second flange connected to the second coal dropping pipe at its bottom, and a third flange connected to the hot air pipeline on its side wall.

[0014] According to the technical solution of the present utility model, a grate plate is provided at the place where the coal mixing box faces the hot air pipeline, a plurality of grid plates are arranged inside the coal mixing box, and an annular area is formed between the inner wall of the coal mixing box and the grid plates. The air inlet holes of the grate plate are communicated with the annular area, and the primary hot air enters the mixing area through the gaps between adjacent grid plates.

[0015] According to the technical solution of the present utility model, the gap sizes between all adjacent grid plates gradually increase from the grate plate to both sides, so that the primary air enters the mixing area evenly.

[0016] According to the technical solution of the present utility model, the grate plate is of an arc-shaped structure, connected to the inner wall of the coal mixing box at the place where it faces the hot air pipeline, and is covered with air inlet holes.

[0017] According to the technical solution of the present utility model, the top of the grid plate is fixedly connected to the outer wall of the first straight pipe located in the upper part inside the coal mixing box, and a first reinforcing ring is connected to the outer wall at its bottom, and the first reinforcing ring is fixed to the inner wall at the bottom of the coal mixing box; a second reinforcing ring is connected to the middle of the grid plate, and the second reinforcing ring is fixed to the inner wall in the middle of the coal mixing box.

[0018] According to the technical solution of the present utility model, the first reinforcing ring includes a plurality of first arc-shaped segments arranged in the circumferential direction, and there is a gap of 3-5 mm between adjacent first arc-shaped segments; the second reinforcing ring includes a plurality of second arc-shaped segments arranged in the circumferential direction, and there is a gap of 3-5 mm between adjacent second arc-shaped segments.

[0019] According to the technical solution of the present utility model, the inner walls of each of the first arc segments and the inner walls of each of the second arc segments are connected to the outer wall of the grille plate through a first connecting plate, and the outer walls of each of the first arc segments and the outer walls of each of the second arc segments are connected to the inner wall of the coal blending box through a second connecting plate.

[0020] According to the technical solution of the present utility model, a second cone tube and a second straight tube are successively connected downward at the bottom of the coal blending box. The second cone tube is provided with an anti-wear lining, and a first cone tube is connected to the lower part of the first straight tube; the first flange is installed above the first straight tube, the second flange is installed below the second straight tube, and a square air inlet passage is connected to the side wall of the coal blending box corresponding to the third flange.

[0021] It can be seen from the above technical solutions that compared with the prior art, the present utility model has the following beneficial effects:

[0022] The raw coal drying device provided by the present utility model is installed on the coal dropping pipe outside the coal mill. Before the raw coal enters the coal mill, the raw coal is dried to a certain extent. By directly connecting the hot air pipeline to the coal blending box, the hot primary air can directly mix with the raw coal. Such a design improves the contact efficiency between the hot air and the raw coal. When the raw coal falls onto the grinding table, the water content of the raw coal is reduced, so the output of the coal mill is significantly improved. This device is especially suitable for raw coal with high water content.

[0023] The regulating valve is used to control the amount of hot primary air entering the coal blending box and accurately regulate the amount of hot air entering the coal blending box according to the water content of the raw coal.

[0024] The design inside the coal blending box, including the structure of the grille plate and the grate plate inside it, ensures that the hot primary air can evenly enter the mixing area and evenly contact the raw coal, reducing the water content of the raw coal.

[0025] By using the first flange, the second flange and the third flange, the installation and maintenance process of the equipment is simplified. The flange connection provides the equipment with convenient disassembly and assembly capabilities, which is particularly important when regular maintenance and cleaning are required.

[0026] The design such as the anti-wear lining on the second cone tube in the present utility model helps to protect the equipment and extend its service life. Description of the Drawings

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0028] Figure 1 It is a schematic structural diagram of a medium-speed coal mill raw coal drying device provided by the present invention for a medium-speed coal mill.

[0029] Figure 2 It is a schematic structural diagram of a medium-speed coal mill in the prior art.

[0030] Figure 3 It shows a perspective view of the coal blending box.

[0031] Figure 4 It is a partial cross-sectional view of the coal blending box.

[0032] Figure 5 It is a layout schematic diagram of the grate plate and the grille plate.

[0033] Figure 6 It shows a connection schematic diagram of the grate plate and the coal blending box.

[0034] Figure 7 It shows a connection schematic diagram of the first reinforcing ring, the first connecting plate, the second connecting plate and the coal blending box. Detailed Embodiment

[0035] The following will describe in detail the embodiments of the present invention. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present invention, but should not be construed as a limitation of the present invention.

[0036] In recent years, the quality of raw coal for power generation has been decreasing year by year. Medium-speed coal mills are forced to start grinding a large amount of raw coal with a moisture content exceeding 20%. For the existing medium-speed coal mills, see the attached Figure 2 , in which the hot primary air is introduced into the coal mill, and it cannot directly participate in reducing the moisture content of the raw coal, resulting in a reduction in the output of the coal mill and affecting the normal operation of the generator set. In view of this, the present invention provides a medium-speed coal mill raw coal drying device, see the attached Figure 1, including: a mixed coal bin 20, the mixed coal bin 20 is connected between a first coal dropping pipe 21 and a second coal dropping pipe 22, jointly forming a coal dropping pipe outside the coal mill; a hot air pipeline 30, one side of the mixed coal bin 20 is connected to the hot air pipeline 30, the side of the hot air pipeline 30 away from the mixed coal bin 20 is connected to the primary hot air main pipe, and a mixing area X of the primary hot air and raw coal is formed inside the mixed coal bin 20.

[0037] The raw coal drying device provided by the utility model is installed on the coal dropping pipe outside the coal mill. Before the raw coal enters the coal mill, the raw coal is dried to a certain extent. By directly connecting the hot air pipeline to the mixed coal bin, the primary hot air can be directly mixed with the raw coal. Such a design improves the contact efficiency between the hot air and the raw coal. When the raw coal falls onto the grinding table, the water content of the raw coal is reduced, so the output of the coal mill is significantly improved. This device is especially suitable for raw coal with high water content.

[0038] In an embodiment of the utility model, a regulating valve 31 is installed on the hot air pipeline 30. The regulating valve can be an existing mechanical valve or an existing electronic valve, and accurately regulates the hot air volume entering the mixed coal bin according to the water content of the raw coal.

[0039] In the description of the utility model, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "vertical", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the utility model.

[0040] See the attached Figure 3 , in an embodiment of the utility model, the mixed coal bin 20 is vertically arranged, its top has a first flange 23 connected to the first coal dropping pipe 21, its bottom has a second flange 24 connected to the second coal dropping pipe 22, and its side wall has a third flange 25 connected to the hot air pipeline 30, which is convenient for disassembly and maintenance.

[0041] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the utility model, "a plurality" means two or more unless otherwise specifically defined.

[0042] In an embodiment of the utility model, see the attached Figure 4 and 5, a grate plate 201 is provided at the coal blending box 20 facing the hot air pipeline 30. A plurality of grid plates 202 are arranged inside the coal blending box 20, and an annular area is formed between the inner wall of the coal blending box 20 and the grid plates 202. The air inlet holes of the grate plate 201 communicate with the annular area, and the primary hot air enters the mixing area X through the gaps between adjacent grid plates 202.

[0043] Advantageously, the sizes of the gaps between all adjacent grid plates 202 gradually increase from the grate plate 201 to both sides, so that the primary air enters the mixing area X evenly.

[0044] In other embodiments of the present invention, refer to the appendix Figure 6 , the grate plate 201 is of an arc-shaped structure and is connected to the inner wall of the coal blending box 20 facing the hot air pipeline 30, and is covered with air inlet holes. The upper and lower ends of the grate plate 201 are welded in the square opening of the coal blending box 20, and equal gaps are left between the left and right sides and the square opening.

[0045] When the present invention works, hot air enters the inside of the coal blending box from the hot air pipeline. The grate plate deflects and disperses the incoming primary hot air, so that the primary hot air enters the annular area between the outer shell of the coal blending box and the grid plate, avoiding excessive air volume at the air inlet. See Figure 5 , the primary hot air passes through the grid gaps and enters the mixing area. In order to make the primary hot air enter the mixing area as evenly as possible, according to the distance from the third flange from far to near, the grid gaps gradually decrease, that is, the closer to the third flange, the smaller the grid gaps. Due to the functions of the grate plate and the grid plate, the primary hot air enters the mixing area evenly along the circumferential direction of the mixing area through the grid gaps, and is fully mixed with the raw coal entering from the first flange, achieving the drying effect on the raw coal. After the raw coal and the primary hot air are fully mixed in the mixing area, they are jointly discharged from the second flange of the coal blending box and enter the falling coal pipe.

[0046] In some other embodiments of the present invention, refer to the appendix Figure 4 , the top of the grid plate 202 is fixedly connected to the outer wall of the first straight pipe 203 located in the upper part of the coal blending box 20, and a first reinforcing ring 205 is connected to the outer wall of its bottom. The first reinforcing ring 205 is fixed to the inner wall of the bottom of the coal blending box 20; a second reinforcing ring 206 is connected to the middle of the grid plate 202, and the second reinforcing ring 206 is fixed to the inner wall of the middle of the coal blending box 20.

[0047] Advantageously, the first reinforcing ring 205 includes a plurality of first arc segments arranged in the circumferential direction, and there is a gap of 3-5 mm between adjacent first arc segments; the second reinforcing ring 206 includes a plurality of second arc segments arranged in the circumferential direction, and there is a gap of 3-5 mm between adjacent second arc segments.

[0048] Since each reinforcing ring is not a complete circular ring, it is prone to deformation when subjected to radial force, thus avoiding jamming when the coal blending box is sleeved into the reinforcing ring.

[0049] However, soft sundries such as straw, woven bags, and fine iron wires are often mixed in raw coal. In the above solution, there is a defect that when the reinforcing ring is directly welded to the grille plate, these soft sundries will pass through the gaps of the grille plate and stick to the reinforcing ring, thereby causing blockage of the coal blending box.

[0050] In another preferred solution of the present utility model, refer to the attached Figure 7 , the inner walls of each of the first arc segments and the inner walls of each of the second arc segments are connected to the outer wall of the grille plate 202 through the first connecting plate 207, and the outer walls of each of the first arc segments and the outer walls of each of the second arc segments are connected to the inner wall of the coal blending box 20 through the second connecting plate 2071.

[0051] Among them, the first connecting plate and the second connecting plate can be blocks. The second connecting body plays a role in radially fixing the reinforcing ring, and the first connecting body keeps the reinforcing ring away from the grille plate, preventing sundries from sticking and avoiding blockage of the coal blending box.

[0052] In the present utility model, unless otherwise clearly specified and defined, terms such as "installation", "connection", "connection", "fixation" and other terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0053] In any of the above embodiments of the present utility model, the bottom of the coal blending box 20 is sequentially connected with a second conical pipe 208 and a second straight pipe 209 downward. The second conical pipe 208 is provided with an anti-wear lining, and the lower part of the first straight pipe 203 is connected with a first conical pipe 210; the first flange 23 is installed above the first straight pipe 203, the second flange 24 is installed below the second straight pipe 209, and a square air inlet passage is connected to the side wall of the coal blending box 20 corresponding to the third flange 25.

[0054] Among them, the grate plate 201 is smaller than the square air inlet passage, and there are square air inlet channels on both sides of it.

[0055] Through the above technical solutions of the present utility model, the problem that in recent years, the coal quality of raw coal for power generation has been decreasing year by year, and medium-speed coal mills have been forced to start grinding a large amount of raw coal with a water content exceeding 20%, resulting in a reduction in the output of the coal mill and affecting the normal operation of the generator set has been solved.

[0056] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0057] Although the embodiments of the present utility model have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present utility model. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present utility model.

Claims

1. A medium-speed grinding raw coal drying device, characterized in that: include: A coal mixing box (20), the coal mixing box (20) being connected between the first coal dropping pipe (21) and the second coal dropping pipe (22), and together forming a coal dropping pipe outside the coal mill; A hot air pipeline (30), one side of the coal mixing box (20) is connected to the hot air pipeline (30), and the side of the hot air pipeline (30) away from the coal mixing box (20) is connected to the hot primary air main pipe, so that a mixing area (X) of hot primary air and raw coal is formed inside the coal mixing box (20).

2. A medium-speed grinding raw coal drying device according to claim 1, characterized in that: A regulating valve (31) is installed on the hot air pipeline (30).

3. The medium-speed grinding raw coal drying device according to claim 1 is characterized in that: The coal mixing box (20) is arranged vertically, has a first flange (23) on its top connected to the first coal dropping pipe (21), has a second flange (24) on its bottom connected to the second coal dropping pipe (22), and has a third flange (25) on its side wall connected to the hot air pipeline (30).

4. A medium-speed mill raw coal drying device according to claim 3, characterized in that: The coal mixing box (20) is provided with a grate plate (201) facing the hot air pipeline (30), a plurality of grille plates (202) are provided inside the coal mixing box (20), and an annular area is formed between the inner wall of the coal mixing box (20) and the grille plates (202), the air inlet holes of the grate plates (201) are connected to the annular area, and the hot primary air enters the mixing area (X) through the gaps of the adjacent grille plates (202).

5. A medium-speed mill raw coal drying device according to claim 4, characterized in that: The gap sizes of all adjacent grid plates (202) gradually increase from the grate plate (201) to both sides, so that the primary air enters the mixing area (X) evenly.

6. A medium-speed mill raw coal drying device according to claim 4, characterized in that: The grate plate (201) is an arc-shaped structure, connected to the inner wall of the coal mixing box (20) facing the hot air pipeline (30), and is covered with air inlet holes.

7. The medium-speed grinding raw coal drying device according to claim 4 is characterized in that: The top of the grid plate (202) is fixedly connected to the outer wall of the first straight pipe (203) located in the upper inner part of the mixed coal box (20), and the bottom outer wall thereof is connected to a first reinforcement ring (205), and the first reinforcement ring (205) is fixed to the bottom inner wall of the mixed coal box (20); the middle of the grid plate (202) is connected to a second reinforcement ring (206), and the second reinforcement ring (206) is fixed to the middle inner wall of the mixed coal box (20).

8. The medium-speed grinding raw coal drying device according to claim 7 is characterized in that: The first reinforcement ring (205) comprises a plurality of first arc segments arranged in a circumferential direction, with a gap of 3-5 mm between adjacent first arc segments; the second reinforcement ring (206) comprises a plurality of second arc segments arranged in a circumferential direction, with a gap of 3-5 mm between adjacent second arc segments.

9. A medium-speed mill raw coal drying device according to claim 8, characterized in that: The inner wall of each of the first arc segments and the inner wall of each of the second arc segments are connected to the outer wall of the grid plate (202) via a first connecting plate (207), and the outer wall of each of the first arc segments and the outer wall of each of the second arc segments are connected to the inner wall of the mixed coal box (20) via a second connecting plate (2071).

10. A medium speed grinding raw coal drying device according to any one of claims 7 to 9, characterized in that: The bottom of the mixed coal box (20) is connected downward in sequence with a second conical tube (208) and a second straight tube (209); the second conical tube (208) is provided with an anti-wear lining; the lower part of the first straight tube (203) is connected with a first conical tube (210); the first flange (23) is installed above the first straight tube (203); the second flange (24) is installed below the second straight tube (209); and a square air intake passage is connected to the side wall of the mixed coal box (20) corresponding to the third flange (25).

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