Pulverized coal returning device of pulverized coal bunker of blast furnace

Abstract

A pulverized coal returning device of a blast furnace pulverized coal bunker belongs to the technical field of blast furnace coal injection equipment and is used for returning pulverized coal of the blast furnace pulverized coal bunker. According to the technical scheme, a pulverized coal bunker is connected with an injection tank through a pulverized coal discharging pipe, the injection tank is connected with an injection branch pipe, an injection tank coal feeding valve is installed on the injection branch pipe, and a coal injection main pipeline is connected with a blast furnace. One end of the powder return pipeline from the injection tank to the mill is connected to the injection branch pipe of one of the injection tanks, the joint is positioned on the injection branch pipe between an outlet at the lower end of the injection tank and a coal feeding valve of the injection tank, and the other end of the powder return pipeline from the injection tank to the mill is opposite to a feeding hole of the medium-speed mill; and the powder return pipeline stop valve from the injection tank to the mill is arranged on the powder return pipeline from the injection tank to the mill. The device is simple in structure and convenient to use, solves the problems of long storage time in the pulverized coal bunker, poor flowability of pulverized coal containing impurities, difficulty in injection and easiness in gun blockage, and is an innovation of a pulverized coal returning technology for returning the pulverized coal in the injection tank to the pulverized coal bunker.

Description

Technical Field

[0001] The utility model relates to a device for returning pulverized coal in a blast furnace pulverized coal bin, belonging to the technical field of blast furnace coal injection equipment. Background Art

[0002] Pulverized coal injection in blast furnace is to inject finely ground anthracite, bituminous coal or a mixture of the two into the blast furnace from the tuyere. It is an important technological measure to reduce the coke ratio and pig iron cost. The pulverized coal injection process in blast furnace includes two processes: pulverizing system and injection system. The task of pulverizing system is to safely process raw coal into pulverized coal that meets the injection requirements and store it in the pulverized coal bin for injection.

[0003] When the blast furnace encounters a general planned wind stop, in order to prevent the injection tank from dissipating heat and cooling, and the coal powder condenses, the coal powder in the injection tank is usually returned to the coal powder bin. When the blast furnace encounters a long period of suffocation, the coal powder in the coal powder bin usually needs to be emptied or a small amount of coal powder needs to be stored. If a large amount of coal powder is stored in the coal powder bin for special reasons and the storage time is too long, the coal powder in the coal powder bin will cool down and condense. The reason is that the coal powder bin needs to continuously introduce safety nitrogen, which will reduce the temperature of the coal powder; the coal powder in the coal powder bin will cool down faster in winter. Cooling and condensation will make the fluidity of coal powder worse, which will cause frequent gun blockage of the injection branch pipe. In addition, if the coal powder vibrating screen fails, it will also cause coarse particles of coal powder or debris mixed in the coal powder to enter the coal powder bin, which will also affect the injection.

[0004] The existing pulverized coal return technology of the injection tank is to return the pulverized coal in the injection tank that is not sprayed for a short period of time to the pulverized coal bin through a special pulverized coal return pipeline, so as to prevent the pulverized coal from condensing due to heat dissipation and cooling of the injection tank. This technology solves the pulverized coal return problem in the injection tank, but it is powerless to prevent the pulverized coal in the pulverized coal bin from condensing due to special reasons if the pulverized coal is stored for too long and the cooling time is too long. Therefore, the existing pulverized coal return device cannot solve the problem that the pulverized coal stored for a long time in the pulverized coal bin is difficult to spray and easy to block the gun, and it is urgently needed to be improved. Utility Model Content

[0005] The technical problem to be solved by the utility model is to provide a pulverized coal returning device for a blast furnace pulverized coal bin. The pulverized coal returning device can allow the pulverized coal stored in the pulverized coal bin for a long time to re-enter the discharge port of the mill, and enter the mill together with the raw coal for secondary pulverizing. The pulverized coal with qualified particle size and temperature can then enter the pulverized coal bin again, thereby fundamentally solving the problems of long storage time of pulverized coal in the pulverized coal bin, reduced temperature, condensation of pulverized coal, and difficulty in spraying.

[0006] The technical solution to solve the above technical problems is:

[0007] A pulverized coal return device for a blast furnace pulverized coal bin comprises a pulverized coal bin, a pulverized coal discharge pipe, a pulverized coal discharge pipe cut-off valve, an injection tank, an injection branch pipe, an injection tank coal delivery valve, a coal injection main pipeline, a medium-speed mill, a medium-speed mill smoke outlet pipeline, a bag box, and a pulverized coal vibrating screen. The pulverized coal bin is connected to the injection tank through the pulverized coal discharge pipe. Each blowing tank is equipped with an blowing branch pipe, and each blowing branch pipe is equipped with a blowing tank coal delivery valve. One end of the blowing branch pipe is connected to the lower end of the blowing tank, and the other end is connected to the coal injection main pipeline. Multiple blowing branch pipes are finally connected to the coal injection main pipeline. The raw coal discharge port is connected to the feed port of the medium-speed mill, the medium-speed mill flue gas outlet pipe is connected to the bag box, the bag box is connected to the coal powder vibrating screen, the coal powder vibrating screen is connected to the feed port of the coal powder bin, and there is a powder return pipeline from the blowing tank to the coal powder bin and a shut-off valve for the powder return pipeline from the blowing tank to the coal powder bin between the coal injection main pipeline and the coal powder bin. The improvement is that it adds a powder return pipeline from the blowing tank to the mill and a powder return pipeline shut-off valve from the blowing tank to the mill. One end of the powder return pipeline from the blowing tank to the mill is connected to the blowing branch pipe of one of the blowing tanks, and the connection is located on the blowing branch pipe between the blowing tank outlet and the blowing tank coal delivery valve. The other end of the powder return pipeline from the blowing tank to the mill is opposite to the feed port of the medium-speed mill, and the powder return pipeline shut-off valve from the blowing tank to the mill is installed on the powder return pipeline from the blowing tank to the mill.

[0008] The pulverized coal return device of the blast furnace pulverized coal bin is provided with a plurality of blowing tanks, each of which is provided with a blowing branch pipe at the lower end, each of which has its own coal delivery valve, and the plurality of blowing branch pipes are finally connected to the coal injection main pipe. The blowing branch pipe of one of the blowing tanks is connected to the powder return pipe from the blowing tank to the mill, the feed inlet of the powder return pipe from the blowing tank to the mill is located on the blowing branch pipe between the outlet of the blowing tank and the coal delivery valve of the blowing tank, and the discharge port of the powder return pipe from the blowing tank to the mill is opposite to the feed inlet of the medium-speed mill.

[0009] The beneficial effects of the utility model are:

[0010] The powder return pipeline of the utility model is connected to the injection branch pipe at the lower end of the injection tank. The coal powder that has been stored in the coal powder bin for a long time and contains impurities can be transported back to the mill through the powder return pipeline to be re-pulverized together with the raw coal, and the newly produced qualified coal powder enters the coal powder bin again.

[0011] The utility model has a simple structure and is easy to use. It solves the problems of long storage time in the coal powder bin, poor fluidity of coal powder containing impurities, difficulty in injection, and easy gun blockage. It is an innovation of the existing technology of returning coal powder in the injection tank to the coal powder bin. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the structure of the utility model.

[0013] The markings in the figure are as follows: pulverized coal bin 1, pulverized coal discharge pipe 2, pulverized coal discharge pipe shut-off valve 3, injection tank 4, injection branch pipe 5, injection tank coal delivery valve 6, coal injection main pipeline 7, blast furnace 8, raw coal discharge port 9, medium-speed mill 10, medium-speed mill flue gas outlet pipe 11, bag box 12, pulverized coal vibrating screen 13, pulverized coal main pipeline to pulverized coal bin return pipeline 14, pulverized coal return pipeline shut-off valve from injection tank to mill 15, pulverized coal return pipeline from injection tank to mill 16, shut-off valve on the pulverized coal main pipeline to pulverized coal bin return pipeline 17. DETAILED DESCRIPTION

[0014] The utility model comprises a pulverized coal bin 1, a pulverized coal feeding pipe 2, a pulverized coal feeding pipe cut-off valve 3, a blowing tank 4, a blowing branch pipe 5, a blowing tank coal delivery valve 6, a coal injection main pipeline 7, a medium-speed mill 10, a medium-speed mill smoke outlet pipeline 11, a bag box 12, a pulverized coal vibrating screen 13, a pulverized coal return pipeline cut-off valve 15 from the blowing tank to the mill, and a pulverized coal return pipeline 16 from the blowing tank to the mill.

[0015] The figure shows that the pulverized coal bunker 1 is connected to the injection tank 4 through the pulverized coal feeding pipe 2 and the pulverized coal feeding pipe cut-off valve 3, the outlet of the injection tank 4 is connected to the upper end of the injection branch pipe 5, the lower end of the injection branch pipe 5 is connected to the coal injection main pipeline 7, the injection tank coal delivery valve 6 is installed on the injection branch pipe 5, and the coal injection main pipeline 7 is connected to the blast furnace 8. The raw coal feeding port 9 is connected to the feed port of the medium-speed mill 10, the medium-speed mill flue gas outlet pipe 11 is connected to the bag box 12, the bag box 12 is connected to the pulverized coal vibrating screen 13, and the pulverized coal vibrating screen 13 is connected to the feed port of the pulverized coal bunker 1. These devices operate normally during the pulverizing operation of the blast furnace 8.

[0016] As shown in the figure, in order to solve the problems of long storage time in the coal powder bin, poor fluidity of coal powder containing impurities, difficulty in spraying, and easy gun clogging, the utility model adds a powder return pipeline 16 from the spray tank to the mill and a powder return pipeline shut-off valve 15 from the spray tank to the mill to the existing powder spraying equipment.

[0017] As shown in the figure, the lower outlet of the injection tank 4 is connected to the injection branch pipe 5, one end of the powder return pipe 16 from the injection tank to the mill is connected to the injection branch pipe 5, the connection point is located on the injection branch pipe 5 between the lower outlet of the injection tank and the coal delivery valve 6 of the injection tank, the other end of the powder return pipe 16 from the injection tank to the mill is opposite to the feed port of the medium-speed mill 10, and the powder return pipe cut-off valve 15 from the injection tank to the mill is installed on the powder return pipe 16 from the injection tank to the mill.

[0018] In the above structure, the inlet end of the powder return pipe 16 from the injection tank to the mill is connected to the injection branch pipe 5 between the outlet of one of the injection tanks and the injection tank coal delivery valve 6, instead of being connected to the coal injection main pipe 7. This is mainly to prevent one of the injection tanks 3 from returning powder and interfering with the normal coal injection operation of the other two injection tanks.

[0019] At the same time, the outlet end of the powder return pipe 16 from the blowing tank to the mill is connected to the raw coal discharge port 9. Since the medium-speed mill 10 adopts negative pressure to pulverize the raw coal, the raw coal discharge port 9 is in a negative pressure state, while the coal injection branch pipe of the blowing tank 3 is in a positive pressure state, and the powder return pipe 16 from the blowing tank to the mill is also in a positive pressure state. Therefore, it is relatively easy to realize the flow from the coal powder bin 1 to the blowing tank 4 and then through the powder return pipe 16 from the blowing tank to the mill to enter the medium-speed mill 10.

[0020] The figure shows that there are three spray tanks 4, and the lower end of each spray tank is connected to its own spray branch pipe, and each spray branch pipe has its own coal delivery valve. The spray branch pipe 5 of one of the spray tanks is connected to the feed port of the powder return pipe 16 from the spray tank to the mill, and the feed port of the powder return pipe 16 from the spray tank to the mill is located on the spray branch pipe 5 between the lower end outlet of the spray tank 3 and the coal delivery valve 6 of the spray tank.

[0021] The working process of the utility model is as follows:

[0022] During normal operation, raw coal enters the medium-speed mill 10 from the raw coal discharge port 9 for grinding, and the coal powder is transported to the bag box 12 through the medium-speed mill outlet pipe 11, and is screened by the coal powder vibrating screen 13 below the bag box 12. Qualified coal powder enters the coal powder bin 1, and the coal powder bin 1 transports coal powder to the injection tank 4 through the coal powder discharge pipe 2 and the coal powder discharge pipe cut-off valve 3. The injection tank coal delivery valve 6 on the injection branch pipe 5 below the injection tank 4 is opened, and the coal powder is transported from the injection tank 4 to the coal injection main pipeline 7 for coal injection operation. During normal coal injection operation, the cut-off valve 15 on the return pipeline from the injection tank to the mill and the cut-off valve 17 on the return pipeline from the coal injection main pipeline to the coal powder bin are both in a closed state.

[0023] When the coal powder stored in the coal powder bin 1 is difficult to spray due to a long time (or contains impurities), and the gun is frequently blocked, the coal powder stored in the coal powder bin 1 needs to be returned to the medium-speed mill 10 for re-pulverization. At this time, the medium-speed mill 10 starts normally and starts pulverizing. The coal powder in the coal powder bin 1 enters the injection tank 4 through the coal powder discharge pipe 2 and the coal powder discharge pipe cut-off valve 3 by gravity. Then close the coal powder discharge pipe cut-off valve 3 and the injection tank coal delivery valve 6, and the injection tank 4 is pressurized with nitrogen. Open the cut-off valve 15 on the return pipe 16 from the injection tank to the mill, adjust the tank pressure of the injection tank 4, return the powder to the medium-speed mill 10 through the return pipe 16 from the injection tank to the mill, and the coal powder entering the medium-speed mill 10 is pulverized together with the raw coal.

[0024] Under the action of the carrier waste gas, the coal powder with qualified particle size and temperature passes through the medium-speed mill outlet pipe 11 to the bag box pipe, and enters the bag box 12 for gas-solid separation. The solid coal powder passes through the coal powder vibrating screen 13 for impurity filtration, and finally enters the coal powder bin 1, thus completing the cycle of re-pulverizing.

[0025] When the pulverized coal in the pulverized coal bin does not need to be returned to the mill, the three injection tanks take turns to spray the blast furnace. When the pulverized coal in the pulverized coal bin needs to be returned to the mill, one of the injection tanks performs the return operation, and the other two injection tanks can alternately spray the blast furnace, so that the return and injection operations can be achieved without interfering with each other.

[0026] An embodiment of the present utility model is as follows:

[0027] The diameter of the pulverized coal bunker 1 is 11750 mm and the height is 17800 mm;

[0028] The diameter of the pulverized coal feeding pipe 2 is DN300mm and the length is 6577mm;

[0029] There are three spray tanks 3 with an effective volume of 75m³;

[0030] The diameter of the injection branch pipe 5 is 25 mm and the length is 82 m;

[0031] The model of the coal delivery valve 6 of the injection tank is Q641Y-25G;

[0032] The diameter of the coal injection main pipeline 7 is DN150mm;

[0033] The model of the medium speed mill 10 is HPS1103;

[0034] The model of the pulverized coal vibrating screen 13 is WZDM-80-300;

[0035] The diameter of the powder return pipe 15 of the spray tank is DN80mm and the length is 21000mm;

[0036] The model of the shut-off valve 16 of the powder return pipeline from the spray tank to the mill is a carbon steel ball valve DN80.

Claims

1. A pulverized coal return device for a blast furnace pulverized coal bunker, comprising a pulverized coal bunker (1), a pulverized coal feed pipe (2), a pulverized coal feed pipe cut-off valve (3), a blowing tank (4), a blowing branch pipe (5), a blowing tank coal delivery valve (6), a coal injection main pipe (7), a medium-speed mill (10), a medium-speed mill smoke outlet pipe (11), a bag box (12), and a pulverized coal vibrating screen (13). The pulverized coal bunker (1) is connected to the blowing tank (4) through the pulverized coal feed pipe (2) and the pulverized coal feed pipe cut-off valve (3). The outlet of the blowing tank (4) is connected to the pulverized coal bunker (1). The outlet (9) is connected to the upper end of the injection branch pipe (5), the lower end of the injection branch pipe (5) is connected to the coal injection main pipe (7), the injection tank coal delivery valve (6) is installed on the injection branch pipe (5), the coal injection main pipe (7) is connected to the blast furnace (8), the raw coal discharge port (9) is connected to the feed port of the medium-speed mill (10), the medium-speed mill outlet pipe (11) is connected to the bag box (12), the bag box (12) is connected to the coal powder vibrating screen (13), and the coal powder vibrating screen (13) is connected to the feed port of the coal powder bin (1), Features: It adds a powder return pipeline (16) from the blowing tank to the mill and a powder return pipeline shut-off valve (15) from the blowing tank to the mill. One end of the powder return pipeline (16) from the blowing tank to the mill is connected to the blowing branch pipe (5), and the connection point is located on the blowing branch pipe (5) between the blowing tank outlet and the blowing tank coal delivery valve (6). The other end of the powder return pipeline (16) from the blowing tank to the mill is opposite to the feed port of the medium-speed mill (10). The powder return pipeline shut-off valve (15) from the blowing tank to the mill is installed on the powder return pipeline (16) from the blowing tank to the mill.

2. The pulverized coal return device of the blast furnace pulverized coal bunker according to claim 1, Features: There are a plurality of blowing tanks (4), the outlet at the lower end of each blowing tank is connected to the upper end of its own blowing branch pipe (5), the lower ends of the blowing branch pipes (5) are finally connected to the coal injection main pipe (7), the blowing branch pipe of one of the blowing tanks is connected to the powder return pipe (16) from the blowing tank to the mill, the feed port of the powder return pipe (16) from the blowing tank to the mill is located on the blowing branch pipe between the outlet of the blowing tank and the coal delivery valve (6) of the blowing tank, and the discharge port of the powder return pipe from the blowing tank to the mill is opposite to the feed port of the medium speed mill.

Images