Power coal coarse slime dehydration method

Abstract

The invention provides a dehydration method for coarse slime of power coal, and belongs to the technical field of coal washing and selecting. The method comprises the following steps: carrying out primary dehydration on coarse slime by using centrifugal equipment, fully scattering the coarse slime subjected to primary dehydration through a screw feeder, and then conveying the coarse slime into a Venturi feeding pipe; the Venturi feeding pipe further scatters the coarse slime through negative pressure generated by fed high-pressure and high-temperature air flow, the coarse slime is fed into the cyclone for secondary dehydration, and cyclone underflow is fed into the other Venturi feeding pipe, further scatters the coarse slime under the assistance of the fed high-pressure and high-temperature air flow and is fed into the other cyclone for tertiary dehydration; the underflow of the cyclone after three times of dehydration is the final dehydrated coarse slime product. And full dehydration of coarse slime and comprehensive utilization of waste hot air of a coal preparation plant are realized.

Description

Technical Field

[0001] The invention belongs to the technical field of coal washing, and in particular relates to a method for dehydrating coarse coal slime of thermal coal. Background Art

[0002] At present, the coarse coal slime of thermal coal is generally dehydrated by horizontal scraper unloading centrifuge. The process configuration is that the material from the coal slime bucket is classified by the classification cyclone, the bottom flow is pre-dehydrated by the curved screen, and the part above the screen is fed into the centrifuge for dehydration. In order to improve the dehydration effect of coarse coal slime, the existing coal preparation plant replaces the curved screen with a composite vibrating screen or a high-frequency screen to stabilize the feeding properties of the coarse coal slime centrifuge, and has achieved good results.

[0003] However, since the horizontal scraper centrifuge mainly relies on centrifugal force to remove moisture, the dehydration method that relies solely on centrifugal force is reaching its limit due to limitations in processing capacity, equipment structure, and wear resistance. Due to the strong water holding capacity of thermal coal, centrifugal dehydration is difficult and the moisture content of coarse coal slime is always maintained above 20%.

[0004] At present, due to the high moisture content of the dehydrated products of crude coal slime centrifuge, the coal slime products can only be mixed with mixed coal for sale, which greatly wastes precious coal resources. At present, the research on crude coal slime centrifuge is mainly focused on large-scale and intelligent aspects, and there are relatively few studies on improving the dehydration effect; crude coal slime of thermal coal has fine particle size and strong water holding capacity, so it is difficult to remove moisture. The centrifugal field is used to remove the moisture of crude coal slime, and the moisture content of crude coal slime of thermal coal has a great influence on its quality, so it is necessary to further reduce the moisture content quickly. The disadvantage of the prior art is that it is difficult to further reduce the moisture content of crude coal slime by relying solely on the centrifugal field, resulting in the crude coal slime of thermal coal can only be mixed with mixed coal, which reduces the value of the product. The purpose of the present invention is to further reduce the moisture content of crude coal slime and improve the value of crude coal slime of thermal coal by using a secondary dehydration process. Summary of the invention

[0005] In view of the shortcomings of the prior art, a method for dehydrating coarse coal slime from thermal coal is provided, which has simple steps, is easy to use, and is suitable for industrial, continuous and efficient coarse coal dehydration treatment.

[0006] To achieve the above technical objectives, the present invention discloses a method for dehydrating coarse coal slime from thermal coal, wherein a centrifugal device is used to perform a primary dehydration on the coarse coal slime, the coarse coal slime after the primary dehydration is fully dispersed by a spiral feeder and then transported into a venturi feed pipe, the venturi feed pipe utilizes the negative pressure generated by the introduced high-pressure and high-temperature airflow to further disperse the coarse coal slime and feed it into a cyclone for secondary dehydration, the cyclone bottom flow is fed into another venturi feed pipe, and is further dispersed with the assistance of the introduced high-pressure and high-temperature gas and fed into another cyclone for a third dehydration, and the cyclone bottom flow after the third dehydration is the final coarse coal slime product after dehydration.

[0007] The specific steps are as follows: The coarse coal slime is fed into a horizontal scraper discharge centrifuge for primary dehydration; The coarse coal slime product after the primary dehydration is fed into the Venturi feed pipe 1 from the feed port through the screw feeder. In this process, the screw feeder initially breaks up the coarse coal slime product after the dehydration by rotating and transporting the coarse coal slime product, thereby achieving uniform feeding and providing a good premise for uniform contact between the coarse coal slime product and the air; A high-speed high-temperature airflow is fed into the air inlet of the venturi feed pipe 1, so that the coarse coal slime product fed into the venturi feed pipe 1 through the feed port is mixed with the high-speed high-temperature airflow and then fed into the cylindrical cyclone 1 through the discharge port; the high-speed high-temperature airflow forms an air negative pressure in the venturi feed pipe 1, and the high-speed high-temperature airflow is fully mixed with the coarse coal slime product and then fed into the cylindrical cyclone 1 for secondary dehydration; The cylindrical cyclone 1 separates the mixed product of the high-speed high-temperature airflow and the coarse coal slime product into an overflow 1 and an underflow. The underflow and the high-speed high-temperature airflow are continuously fed into the feed port of the venturi feed pipe 2. Meanwhile, the high-speed high-temperature airflow is supplemented to the air inlet of the venturi feed pipe 2. The venturi feed pipe 2 feeds the underflow further mixed with the high-speed high-temperature airflow into the cylindrical cyclone 2 through the discharge port for further solid-liquid separation. The cylindrical cyclone 2 dehydrates the mixed product of the high-speed high-temperature airflow and the underflow three times to discharge the overflow 2 and the dehydrated coarse coal slime. The overflow 1 and overflow 2 are both fed into the steam-water separator for treatment, the overflow of the steam-water separator enters the atmosphere, and the bottom flow is discharged as coal slurry water.

[0008] Furthermore, the high-speed and high-temperature airflow is the waste air generated in the air compressor room, which passes through the induced draft fan and the air compressor to increase the speed and pressure of the waste air, so that the waste air flow pressure is increased to above 0.3Mpa, and the temperature is increased to above 80°.

[0009] Furthermore, the pressure of the high-speed high-temperature airflow fed into the Venturi feed pipe 1 is controlled at 0.15-0.2 MPa, which is used to loosen and dehydrate the coarse coal slime to prevent the coarse coal slime from agglomerating; the pressure of the high-speed high-temperature airflow fed into the Venturi feed pipe 2 is controlled at 0.25-0.3 MPa, which is used to deeply dehydrate the coarse coal slime.

[0010] Furthermore, the cylindrical cyclone 1 discharges overflow 1 through the overflow port at the top, and the cylindrical cyclone 2 discharges overflow 2 through the overflow port at the top; the material and gas in the venturi inlet pipe 1 and the venturi inlet pipe 2 enter tangentially through the inlet of the cylindrical cyclone 1 and the cylindrical cyclone 2 set at the middle position.

[0011] Furthermore, the diameters of the cylindrical cyclone swirler 1 and the cylindrical cyclone swirler 2 are the same, and the overflow port of the cylindrical cyclone swirler 1 is connected in series with the feed port of the cylindrical cyclone swirler 2 through the venturi feed pipe 2.

[0012] Furthermore, both the cylindrical cyclone 1 and the cylindrical cyclone 2 have a two-stage multi-feed port structure, in which the upper port is inclined downward by 10-15 degrees, and the lower feed port is inclined upward by 10-15 degrees. The bottom flow port of the cylindrical cyclone 1 is connected to the feed port of the Venturi feed pipe 2, and the material enters the secondary dehydration by gravity and negative pressure.

[0013] Furthermore, the coal slurry water is fed into the coal slurry water system for recycling.

[0014] Beneficial effects: This method uses coarse coal slime for rapid secondary dehydration. The coarse coal slime is first dehydrated by a centrifuge to make it basically dispersed, and the coarse coal slime has a fine particle size, which is very conducive to dehydration again. After that, two sets of Venturi feed pipes and cyclone cyclones are used to further dehydrate the coarse coal slime twice. In this process, the waste air from the compressor room is pressurized and heated again, and the coarse coal slime is further dispersed and fed into the Venturi feed pipe, and the cyclone cyclone is used to complete the two dehydrations. The dehydration effect is good, and the moisture content of the final product can be basically maintained at 16-18%. The full dehydration of the coarse coal slime and the comprehensive utilization of the waste hot air from the coal preparation plant are achieved; compared with the previous plan on site, the moisture content is greatly reduced and the product quality is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The schematic diagram of the process of dehydrating the crude coal slime of thermal coal of the present invention; Figure 2 Schematic diagram of the structure of a cylindrical cyclone swirler used in an embodiment of the present invention; FIG. a is a front view of the cylindrical cyclone swirler, and FIG. b is a top view of the cylindrical cyclone swirler.

[0016] In the figure: A-vertical and horizontal scraper discharge centrifuge, B-screw feeder, C-induced draft fan, D-air compressor, E-Venturi inlet pipe 1, F-cylindrical cyclone 1, G-Venturi inlet pipe 2, H-cylindrical cyclone 2, I-steam-water separator. DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with the accompanying drawings: like Figure 1As shown, the present invention discloses a method for dehydrating coarse coal slime of thermal coal. The coarse coal slime is first dehydrated by a horizontal scraper unloading centrifuge. The dehydrated product is fed into a spiral feeder, which plays a role in transferring materials on the one hand and breaking up the coarse coal slime to achieve uniform feeding on the other hand, and provides a good premise for the coarse coal slime product to be uniformly contacted with air. The waste air temperature of the on-site air compressor is 40° and the flow rate is 1000m3 / h. After being fed into the air compressor by the induced draft fan, the waste air temperature is raised to above 80°. A part of this waste air is fed into the venturi feed pipe 1 to generate negative pressure. Under the action of the air negative pressure and the spiral feeder, the waste air is fully mixed with the coarse coal slime and then fed into the cylindrical cyclone cyclone 1 for secondary dehydration to be divided into overflow and underflow; the underflow of the cylindrical cyclone cyclone 1 and another part of the waste air are fed into the venturi feed pipe 2, and the waste air is fully mixed with the coarse coal slime and then fed into the cylindrical cyclone cyclone 2 for tertiary dehydration to be divided into overflow and underflow.

[0018] A thermal coal preparation plant in western China uses a horizontal scraper unloading centrifuge to remove moisture from coarse coal slime. Due to the strong water holding capacity of thermal coal, centrifugal dehydration is difficult and the moisture content of the coarse coal slime is always maintained above 20%.

[0019] The present invention proposes a method for dehydrating coarse coal slime of thermal coal. The method comprises the steps of primary dehydration of a horizontal scraper discharge centrifuge, waste air input, secondary dehydration of a cyclone cyclone, etc. The coarse coal slime is dehydrated once by a horizontal scraper discharge centrifuge, and the waste hot air from the coal preparation plant is divided. A part of it is fully mixed with the centrifuge discharge in a negative pressure turbulent environment, and then tangentially fed into a primary cyclone cyclone through a unidirectional and unidirectional inlet, and a part of it is mixed with the bottom flow of the primary cyclone through negative pressure turbulence and fed into a secondary cyclone cyclone, so as to achieve full dehydration of the coarse coal slime and comprehensive utilization of the waste hot air of the coal preparation plant.

[0020] Specifically: The coarse coal slime is fed into the horizontal scraper discharge centrifuge A for primary dehydration; The coarse coal slime product after the primary dehydration is fed into the Venturi feed pipe 1E from the feed port through the screw feeder B. In this process, the screw feeder B initially breaks up the coarse coal slime product after the dehydration by rotating and transporting the coarse coal slime product, thus achieving uniform feeding and providing a good premise for uniform contact between the coarse coal slime product and the air; A high-speed high-temperature airflow is fed into the air inlet of the venturi feed pipe 1E, so that the coarse coal slime product fed into the venturi feed pipe 1E through the feed port is mixed with the high-speed high-temperature airflow and then fed into the cylindrical cyclone 1F through the discharge port; the high-speed high-temperature airflow forms an air negative pressure in the venturi feed pipe 1E, and is fully mixed with the discharge of the horizontal scraper discharge centrifuge A in the negative pressure turbulent flow environment in the venturi feed pipe 1E, and then is tangentially fed into the cylindrical cyclone 1F through the same-direction and different-position feed ports, and is subjected to secondary dehydration in the cylindrical cyclone 1F; The cylindrical cyclone 1F separates the mixed product of the high-speed high-temperature airflow and the coarse coal slime product into overflow 1 and underflow. The underflow and the high-speed high-temperature airflow are continuously fed into the feed port of the venturi feed pipe 2G, and the high-speed high-temperature airflow is supplemented to the air inlet of the venturi feed pipe 2G. The venturi feed pipe 2G further mixes the negative pressure turbulence generated by the fed underflow and the high-speed high-temperature airflow and feeds it into the cylindrical cyclone 2H through the discharge port for further solid-liquid separation. The cylindrical cyclone 2H dehydrates the mixed product of the high-speed high-temperature airflow and the underflow for three times to discharge the overflow 2 and the dehydrated coarse coal slime. The overflows of cylindrical cyclone 1F and cylindrical cyclone 2H are combined and enter the steam-water separator I. The overflow of steam-water separator I flows into the atmosphere, and the bottom flow is fed into the coal slurry water system for recovery. The bottom flow of cylindrical cyclone 2H becomes the final dehydrated product. After a period of stable operation, the moisture content of the final product is maintained at 16-18%. Compared with the previous plan on site, the moisture content is greatly reduced and the product quality is significantly improved; The cylindrical cyclone cyclone 1F and the cylindrical cyclone cyclone 2H have the same diameter, the overflow port of the cylindrical cyclone cyclone 1F is connected in series with the feed port of the cylindrical cyclone cyclone 2H through the venturi feed pipe 2G, and the inclination angle of the cylindrical cyclone cyclone 1F and the cylindrical cyclone cyclone 2H is 30°-60°; like Figure 2 As shown, both the cylindrical cyclone 1F and the cylindrical cyclone 2H are two-stage multi-feed port structures, wherein the upper port is inclined downward by 10-15 degrees, and the lower feed port is inclined upward by 10-15 degrees. The bottom flow port of the cylindrical cyclone 1F is connected to the feed port of the venturi feed pipe 2G, and the material enters the secondary dehydration by gravity and negative pressure.

Claims

1. A method for dehydrating coarse steam coal slime, characterized in that: The coarse coal slime is dehydrated once by using centrifugal equipment. The coarse coal slime after the first dehydration is fully broken up by a screw feeder and then conveyed to a venturi feed pipe. The venturi feed pipe uses the negative pressure generated by the high-pressure and high-temperature airflow to further break up the coarse coal slime and feed it to a cyclone for secondary dehydration. The cyclone bottom flow is fed to another venturi feed pipe and further broken up with the assistance of the high-pressure and high-temperature gas and fed to another cyclone for a third dehydration. The cyclone bottom flow after the third dehydration is the final coarse coal slime product after dehydration.

2. The method for dehydrating crude thermal coal slime according to claim 1, characterized in that: The specific steps are as follows: The coarse coal slime is fed into a horizontal scraper discharge centrifuge (A) for primary dehydration; The coarse coal slime product after the primary dehydration is fed into the Venturi feed pipe 1 (E) from the feed port through the screw feeder (B). During this process, the screw feeder (B) initially breaks up the coarse coal slime product after the dehydration by rotating and transporting the coarse coal slime product, thereby achieving uniform feeding and providing a good premise for the coarse coal slime product to be uniformly contacted with air; A high-speed high-temperature airflow is fed into the air inlet of the venturi feed pipe 1 (E), so that the coarse coal slime product fed into the venturi feed pipe 1 (E) through the feed inlet is mixed with the high-speed high-temperature airflow and then fed into the cylindrical cyclone 1 (F) through the discharge port; the high-speed high-temperature airflow forms an air negative pressure in the venturi feed pipe 1 (E), and the high-speed high-temperature airflow is fully mixed with the coarse coal slime product and then fed into the cylindrical cyclone 1 (F) for secondary dehydration; The cylindrical cyclone 1 (F) separates the mixed product of the high-speed high-temperature airflow and the coarse coal slime product into an overflow 1 and an underflow. The underflow and the high-speed high-temperature airflow are continuously fed into the feed port of the venturi feed pipe 2 (G). Meanwhile, the high-speed high-temperature airflow is supplemented to the air inlet of the venturi feed pipe 2 (G). The venturi feed pipe 2 (G) feeds the underflow further mixed with the high-speed high-temperature airflow into the cylindrical cyclone 2 (H) through the discharge port to continue solid-liquid separation. The cylindrical cyclone 2 (H) dehydrates the mixed product of the high-speed high-temperature airflow and the underflow three times to discharge the overflow 2 and the dehydrated coarse coal slime. The overflow 1 and overflow 2 are both fed into the steam-water separator (I) for treatment. The overflow of the steam-water separator (I) flows into the atmosphere, and the bottom flow is discharged as coal slurry.

3. The method for dehydrating crude thermal coal slime according to claim 2, characterized in that: The high-speed high-temperature airflow is the waste air generated by the air compressor room, which passes through the induced draft fan (C) and the air compressor (D) to increase the speed and pressure of the waste air, so that the waste air flow pressure is increased to above 0.3Mpa, and the temperature is increased to above 80°.

4. The method for dehydrating crude thermal coal slime according to claim 2, characterized in that: The pressure of the high-speed high-temperature airflow fed into the Venturi feed pipe 1 (E) is controlled at 0.15-0.2 MPa, which is used to loosen and dehydrate the coarse coal slime to prevent the coarse coal slime from agglomerating; the pressure of the high-speed high-temperature airflow fed into the Venturi feed pipe 2 (G) is controlled at 0.25-0.3 MPa, which is used to deeply dehydrate the coarse coal slime.

5. The method for dehydrating crude thermal coal slime according to claim 2, characterized in that: The cylindrical cyclone 1 (F) discharges overflow 1 through the overflow port at the top, and the cylindrical cyclone 2 (H) discharges overflow 2 through the overflow port at the top; the material and gas in the venturi inlet pipe 1 (E) and the venturi inlet pipe 2 (G) enter tangentially through the inlet of the cylindrical cyclone 1 (F) and the cylindrical cyclone 2 (H) set at the middle position.

6. The method for dehydrating crude thermal coal slime according to claim 5, characterized in that: The cylindrical cyclone 1 (F) and the cylindrical cyclone 2 (H) have the same diameter, and the overflow port of the cylindrical cyclone 1 (F) is connected in series with the feed port of the cylindrical cyclone 2 (H) through the venturi feed pipe 2 (G).

7. The method for dehydrating crude thermal coal slime according to claim 6, characterized in that: Both the cylindrical cyclone 1 (F) and the cylindrical cyclone 2 (H) have a two-stage multi-feeding port structure, wherein the upper port is inclined downward by 10-15 degrees, and the lower feed port is inclined upward by 10-15 degrees. The bottom flow port of the cylindrical cyclone 1 (F) is connected to the feed port of the venturi feed pipe 2 (G), and the material enters the secondary dehydration by gravity and negative pressure.

8. The method for dehydrating crude thermal coal slime according to claim 4, characterized in that: The coal slurry water is fed into the coal slurry water system for recycling.

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