A blast furnace pulverized coal injection return device and return method

Abstract

A return device and return method for blast furnace coal powder injection, belonging to the technical field of blast furnace coal injection equipment and injection method, is used for returning blast furnace coal powder injection. Its technical scheme is: it adds a coal powder return pipeline, a coal powder complementary pipeline and a coal powder return pipeline. The coal powder return pipeline is installed between the blast furnace coal injection tank and the coal powder bin, and the coal powder in the blast furnace coal injection tank can be returned to the blast furnace coal powder bin; the coal powder complementary pipeline is installed between two blast furnace coal powder return pipelines, so that the material levels of the two coal powder bins are complementary, which can ensure the normal coal injection amount of the blast furnace; the coal powder return pipeline is installed between the blast furnace coal injection tank and the coal powder mill, and the coal powder can be returned to the coal powder mill for re-grinding. The present invention has a simple structure and is easy to operate. When the blast furnace stops coal or the coal injection tank needs to be repaired, the coal powder in the coal injection tank can be transported back to the coal powder bin, and the tank can be refilled when the blast furnace is fed with coal. The two blast furnace coal powder bins can be used complementary to ensure the uniformity of coal injection and avoid coal powder discharge to pollute the environment.

Description

Technical Field

[0001] The invention relates to a return device and a return method for blast furnace coal powder injection, belonging to the technical field of blast furnace coal injection equipment and injection methods. Background Art

[0002] According to the blast furnace coal injection process, it is divided into direct injection process and indirect injection process. The direct injection process includes two processes: pulverizing and injection. After the qualified coal powder is taken by the coal mill, it is directly injected into the blast furnace. This method is mostly used for coal injection in large blast furnaces. The indirect injection process includes three processes: pulverizing, conveying, and injection. After centralized pulverizing, it is transported to the injection station through the coal injection pipeline and then sprayed into the blast furnace. This method is suitable for small blast furnaces or blast furnaces with a large number of blast furnaces. 3 The blast furnace adopts the direct injection process. After the qualified coal powder is ground by the mill, it is pumped into the bag box. The coal powder passes through the ash hopper, ash discharge valve, vibrating screen, and enters the coal powder bin. The 1# mill only corresponds to the 1# coal powder bin, which is used for coal injection in the 1# blast furnace; the 2# mill corresponds to the 1# coal powder bin and the 2# coal powder bin, which can be used for coal injection in both the 1# blast furnace and the 2# blast furnace; the 3# mill only corresponds to the 2# coal powder bin, which is used for coal injection in the 2# blast furnace. The coal injection of the two blast furnaces adopts double series and tank injection. This direct injection process equipment has the following shortcomings: (1) When the blast furnace suddenly stops coal, the coal powder stays in the coal injection tank for more than 10 hours. When it is injected again, the coal powder temperature drops, the fluidity deteriorates, the coal injection rate fluctuates greatly, and even blocks the pipeline, affecting the normal smelting of the blast furnace. (2) When the blast furnace is in normal production, the material level of the pulverized coal bin is maintained at more than 300 tons. When the blast furnace is shut down, the material level is within 50 tons. The pulverized coal is ground after the blast furnace is supplied with air to ensure that the storage time of the pulverized coal in the pulverized coal bin is less than 10 hours. When the blast furnace is shut down unplanned, the pulverized coal bin stores more than 300 tons of pulverized coal. Although the outer wall of the pulverized coal bin has an insulation structure, the temperature of the pulverized coal will decrease if it is stored for more than 1 day, which is not conducive to injection. (3) The overhaul cycle of the mill is 2 to 3 years, and the overhaul period takes more than 15 days. The two pulverized coal bins cannot complement each other. Once a mill fails and cannot grind coal, it will not be able to meet the blast furnace's coal injection volume. The blast furnace is forced to reduce or stop coal, affecting normal smelting. (4) Due to damage to equipment such as vibrating screens and iron removers, impurities enter the coal powder bin and then the injection tank, or due to high moisture content and low temperature of the coal powder, the blast furnace frequently experiences gun blockage, making it impossible to inject normally. The coal powder has to be discharged externally, affecting the uniformity of coal injection in the blast furnace and polluting the environment. (5) When the blast furnace is in normal production, the coal injection tank needs to be temporarily repaired and the coal powder in the tank needs to be manually discharged through the manhole, which is time-consuming and labor-intensive and pollutes the environment. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a return device and a return method for blast furnace coal powder injection. The return device and the return method can transport the coal powder in the coal injection tank back to the coal powder bin when the blast furnace is shut down or the coal injection tank needs to be repaired, and then refill the tank and inject it when the blast furnace is fed with coal. The coal powder bins of the two blast furnaces can be used complementary to ensure the uniformity of coal injection and avoid coal powder discharge to pollute the environment.

[0004] The technical solution to solve the above technical problems is:

[0005] A return device for blast furnace pulverized coal injection, comprising a 1# pulverized coal bin, a 1# blast furnace coal injection tank, a 2# pulverized coal bin, a 2# blast furnace coal injection tank, a pulverized coal mill, a coal bin and a coal feeder. The 1# pulverized coal bin and the 1# blast furnace coal injection tank, the 2# pulverized coal bin and the 2# blast furnace coal injection tank are respectively connected by conveying pipelines, and the coal bin is connected to the pulverized coal mill through the coal feeder. The improvement is that the 1# blast furnace pulverized coal return pipeline is installed between the 1# blast furnace coal injection tank and the 1# pulverized coal bin, the 2# blast furnace pulverized coal return pipeline is installed between the 2# blast furnace coal injection tank and the 2# pulverized coal bin, the pulverized coal complementary pipeline is installed between the 1# blast furnace pulverized coal return pipeline and the 2# blast furnace pulverized coal return pipeline, the 1# blast furnace pulverized coal return mill pipeline is installed between the 1# blast furnace coal injection tank and the pulverized coal mill, and the 2# blast furnace pulverized coal return mill pipeline is installed between the 2# blast furnace coal injection tank and the pulverized coal mill.

[0006] The above-mentioned blast furnace pulverized coal injection return device, the pipeline inlet of the 1# blast furnace coal powder return pipeline is connected between the 1# blast furnace coal injection tank coal outlet valve and the 1# blast furnace coal injection tank coal supply valve of the coal injection pipeline at the lower part of the 1# blast furnace coal injection tank, the 1# blast furnace coal powder return pipeline is installed with the 1# blast furnace coal powder return valve, and the 1# blast furnace coal powder bin inlet valve is installed at the pipeline inlet between the 1# blast furnace coal powder return pipeline and the 1# blast furnace coal powder bin.

[0007] The above-mentioned blast furnace pulverized coal injection return device, the pipeline inlet of the 2# blast furnace coal powder return pipeline is connected between the 2# blast furnace coal injection tank coal outlet valve and the 2# blast furnace coal injection tank coal supply valve of the coal injection pipeline of the 2# blast furnace coal injection tank, the 2# blast furnace coal powder return pipeline is installed with the 2# blast furnace coal powder return valve, and the pipeline outlet between the 2# blast furnace coal powder return pipeline and the 2# blast furnace coal powder bin is installed with the 2# blast furnace coal powder bin inlet valve.

[0008] The above-mentioned blast furnace pulverized coal return device has a 1# blast furnace pulverized coal complementary connecting valve and a 2# blast furnace pulverized coal complementary connecting valve installed at both ends of the pulverized coal complementary pipeline between the 1# blast furnace pulverized coal return pipeline and the 2# blast furnace pulverized coal return pipeline.

[0009] The above-mentioned blast furnace pulverized coal return device, the 1# blast furnace pulverized coal return pipe is equipped with a 1# blast furnace pulverized coal inlet valve at the entrance of the pulverized coal mill, and the 2# blast furnace pulverized coal return pipe is equipped with a 2# blast furnace pulverized coal inlet valve at the entrance of the pulverized coal mill.

[0010] A method for returning pulverized coal to a blast furnace using the pulverized coal return device for blast furnace injection includes a return operation process, a complementary operation process, and a mill feed operation process. The steps of the three operation processes are as follows:

[0011] The coal powder return operation process of the 1# blast furnace coal injection tank:

[0012] The first step is to open the conical fluidizing valve of the 1# blast furnace coal injection tank and the bottom fluidizing valve of the 1# blast furnace coal injection tank, and pressurize the 1# blast furnace coal injection tank to between 0.1 and 0.12 MPa;

[0013] The second step is to open the 1# blast furnace coal powder return valve and the 1# coal powder bunker inlet valve in sequence, and close the 1# blast furnace coal powder complementary connecting valve;

[0014] The third step is to open the coal outlet valve of the 1# blast furnace coal injection tank, close the coal supply valve of the 1# blast furnace coal injection tank, control the flow rate of the fluidizing valve at the bottom of the 1# blast furnace coal injection tank to 80m3 / h, and control the flow rate of the fluidizing valve at the cone of the 1# blast furnace coal injection tank to 60m3 / h, and pour the pulverized coal in the 1# blast furnace coal injection tank back to the 1# pulverized coal bin;

[0015] Coal powder complementary operation process of 1# blast furnace coal injection tank:

[0016] The first step is to open the lower coal valve of the 1# pulverized coal bunker and the coal inlet valve of the 1# blast furnace coal injection tank in sequence. After the 1# blast furnace coal injection tank is filled with 15~20t of pulverized coal, close the lower coal valve of the 1# pulverized coal bunker and the coal inlet valve of the 1# blast furnace coal injection tank in sequence.

[0017] The second step is to open the conical fluidizing valve of the 1# blast furnace coal injection tank and the bottom fluidizing valve of the 1# blast furnace coal injection tank, and pressurize the 1# blast furnace coal injection tank to between 0.12 and 0.15 MPa;

[0018] The third step is to open the 1# blast furnace coal powder return valve, close the 1# coal powder bunker inlet valve, open the 1# blast furnace coal powder complementary connecting valve and the 2# blast furnace coal powder complementary connecting valve, and open the 2# blast furnace coal powder return valve and the 2# coal powder bunker inlet valve;

[0019] Step 4: Open the coal outlet valve of the 2# blast furnace coal injection tank, close the coal supply valve of the 2# blast furnace coal injection tank, control the flow rate of the fluidizing valve at the bottom of the 2# blast furnace coal injection tank to 100m3 / h, control the flow rate of the conical fluidizing valve at the 2# blast furnace coal injection tank to 80m3 / h, and pour the pulverized coal in the 1# blast furnace coal injection tank back to the 2# pulverized coal bin;

[0020] The operation process of feeding the coal injection tank into the mill of No. 1 blast furnace:

[0021] The first step is to open the upper gate valve, coal feeder, lower gate valve and coal pulverizer in sequence to carry out normal coal pulverizing operation;

[0022] The second step is to open the lower coal valve of the 1# pulverized coal bunker and the coal inlet valve of the 1# blast furnace coal injection tank. After the 1# blast furnace coal injection tank is filled with 15-20t of pulverized coal, the lower coal valve of the 1# pulverized coal bunker and the coal inlet valve of the 1# blast furnace coal injection tank are closed in sequence;

[0023] The third step is to open the conical fluidizing valve of the 1# blast furnace coal injection tank and the bottom fluidizing valve of the 1# blast furnace coal injection tank, and pressurize the 1# blast furnace coal injection tank to between 0.08 and 0.10 MPa;

[0024] Step 4: Close the 1# blast furnace coal powder return valve and open the 1# blast furnace coal powder inlet valve.

[0025] The fifth step is to open the coal outlet valve of No. 1 blast furnace coal injection tank, close the coal supply valve of No. 1 blast furnace coal injection tank, control the flow rate of the fluidizing valve at the bottom of No. 1 blast furnace coal injection tank to 60m3 / h, and control the flow rate of the cone fluidizing valve of No. 1 blast furnace coal injection tank to 50m3 / h, to ensure that the inlet and outlet pressure difference of the pulverized coal mill is controlled at about 3.0kpa, and the pulverized coal in No. 1 blast furnace coal injection tank is returned to the pulverized coal mill. After the pulverized coal is re-ground, it enters No. 1 pulverized coal bin or No. 2 pulverized coal bin through the bag box, ash unloading valve and vibrating screen for blast furnace injection.

[0026] The beneficial effects of the present invention are:

[0027] The coal powder return device of the present invention is composed of a coal powder return pipeline, a coal powder complementary pipeline and a coal powder return grinding pipeline.

[0028] The coal powder return pipeline can return the coal powder in a blast furnace coal injection tank to the coal powder bin of the blast furnace, and then refill and inject it when the blast furnace is fed with coal, which prevents the coal powder from staying in the blast furnace coal injection tank for too long. When it is injected again, the coal powder temperature drops, the fluidity becomes worse, and the coal injection rate fluctuates greatly, affecting the normal smelting of the blast furnace. When the blast furnace coal injection tank needs temporary maintenance, the coal powder in the tank can also be returned to the coal powder bin, saving time and labor, and avoiding environmental pollution.

[0029] The pulverized coal complementary pipeline realizes the complementary material level of two pulverized coal bins. One blast furnace coal injection tank can return pulverized coal to the pulverized coal bin connected to another blast furnace coal injection tank through the pulverized coal complementary pipeline, and supply the pulverized coal to the other blast furnace coal injection tank for injection. During the overhaul of the pulverized coal mill or when the equipment fails, the normal blast furnace coal injection amount can be guaranteed, the stability of the blast furnace coal injection can be guaranteed, and the peripheral conditions for the normal smelting of the blast furnace can be provided. When a blast furnace is out of service for more than 24 hours, the pulverized coal can be returned to the pulverized coal bin of other blast furnaces for injection by other blast furnaces, avoiding the pulverized coal staying in the pulverized coal bin for a long time, which will reduce the temperature of the pulverized coal and deteriorate its fluidity.

[0030] The coal powder return pipeline connects the blast furnace coal injection tank and the coal powder mill. If the coal powder is stored for too long, the temperature is too low, or the coal powder particle size and moisture content are unqualified, or there are too many impurities in the coal powder, the gun is frequently blocked, and it cannot be sprayed normally, the coal powder can be returned from the blast furnace coal injection tank to the coal powder mill for re-grinding for blast furnace injection, ensuring the uniformity of coal injection and avoiding coal powder discharge to pollute the environment.

[0031] The present invention is the first of its kind in blast furnace pulverized coal injection equipment and technology, and has the advantages of simple structure, easy operation and stable effect. When the blast furnace is shut down or the coal injection tank needs to be repaired, the coal powder in the coal injection tank can be transported back to the coal powder bin, and then refilled and injected when the blast furnace is supplied with coal. The coal powder bins of the two blast furnaces can be used complementary to ensure the uniformity of coal injection and avoid coal powder discharge to pollute the environment. It has significant economic and social benefits and is worthy of promotion and application in the industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the structure of the existing blast furnace pulverized coal injection equipment;

[0033] Figure 2 It is a structural schematic diagram of the present invention.

[0034] Marked in the figure: 1# pulverized coal bin 1, 1# pulverized coal bin lower coal valve 2, 1# blast furnace coal injection tank coal inlet valve 3, 1# blast furnace coal injection tank 4, 1# blast furnace coal injection tank cone fluidization valve 5, 1# blast furnace coal injection tank bottom fluidization valve 6, 1# blast furnace coal injection tank coal outlet valve 7, 1# blast furnace coal injection tank coal feeding valve 8, coal powder mill 9, coal bin 10, upper gate valve 11, coal feeder 12, lower gate valve 13, 2# pulverized coal bin 14, 2# pulverized coal bin lower coal valve 15, 2# blast furnace coal injection tank coal inlet valve 16, 2# blast furnace coal injection tank 17, 2# blast furnace coal injection tank cone fluidization valve 18, 2# blast furnace coal injection tank bottom Partial fluidizing valve 19, No. 2 blast furnace coal injection tank coal supply valve 20, No. 2 blast furnace coal injection tank coal outlet valve 21, No. 1 blast furnace coal powder return pipe 22, No. 2 blast furnace coal powder return pipe 23, coal powder complementary pipe 24, No. 1 blast furnace coal powder return mill pipe 25, No. 2 blast furnace coal powder return mill pipe 26, No. 1 blast furnace coal powder return valve 27, No. 1 coal powder bin inlet valve 28, No. 1 blast furnace coal powder complementary connecting valve 29, No. 1 blast furnace coal powder inlet valve 30, No. 2 blast furnace coal powder return valve 31, No. 2 coal powder bin inlet valve 32, No. 2 blast furnace coal powder complementary connecting valve 33, No. 2 blast furnace coal powder inlet valve 34. DETAILED DESCRIPTION

[0035] Figure 1It is shown that the existing blast furnace pulverized coal injection equipment consists of 1# pulverized coal bin 1, 1# blast furnace coal injection tank 4, 2# pulverized coal bin 14, 2# blast furnace coal injection tank 17, coal powder mill 9, coal bin 10, and coal feeder 12. 1# pulverized coal bin and 1# blast furnace coal injection tank 4, 2# pulverized coal bin 14 and 2# blast furnace coal injection tank 17 are connected by conveying pipelines respectively, and coal bin 10 is connected to coal powder mill 9 through coal feeder 12.

[0036] Figure 1 It is shown that the 1# pulverized coal bin lower coal valve 2, the 1# blast furnace pulverized coal tank inlet valve 3, the 1# blast furnace pulverized coal tank cone fluidization valve 5, the 1# blast furnace pulverized coal tank bottom fluidization valve 6, the 1# blast furnace pulverized coal tank outlet valve 7, and the 1# blast furnace pulverized coal tank feed valve 8 are installed in the 1# pulverized coal bin, the 1# blast furnace pulverized coal tank 4 and the connecting pipeline. The 2# pulverized coal bin lower coal valve 15, the 2# blast furnace pulverized coal tank inlet valve 16, the 2# blast furnace pulverized coal tank cone fluidization valve 18, the 2# blast furnace pulverized coal tank bottom fluidization valve 19, the 2# blast furnace pulverized coal tank feed valve 20, and the 2# blast furnace pulverized coal tank outlet valve 21 are installed in the 2# pulverized coal bin 14, the 2# blast furnace pulverized coal tank 17 and the connecting pipeline. The upper plug valve 11 and the lower plug valve 13 are installed on the pipelines between the coal pulverizer 9, the coal bin 10 and the coal feeder 12.

[0037] The present invention adds a coal powder return pipeline, a coal powder complementary pipeline and a coal powder return grinding pipeline.

[0038] Figure 2 It is shown that the coal powder return pipe includes a 1# blast furnace coal powder return pipe 22 and a 2# blast furnace coal powder return pipe 23. The 1# blast furnace coal powder return pipe 22 is installed between the 1# blast furnace coal injection tank 4 and the 1# blast furnace coal powder bin 1, and is used to return the coal powder in the 1# blast furnace coal injection tank 4 to the 1# blast furnace coal powder bin 1; the 2# blast furnace coal powder return pipe 23 is installed between the 2# blast furnace coal injection tank 17 and the 2# blast furnace coal powder bin 14, and is used to return the coal powder in the 2# blast furnace coal injection tank 17 to the 2# blast furnace coal powder bin 14.

[0039] Figure 2 It is shown that the coal powder complementary pipeline 24 is installed between the 1# blast furnace coal powder return pipeline 22 and the 2# blast furnace coal powder return pipeline 23, and is used to transport the coal powder of the 1# blast furnace coal injection tank 4 to the 2# blast furnace coal powder bin 14, and supply it to the 2# blast furnace coal injection tank 17 for injection; or to transport the coal powder of the 2# blast furnace coal injection tank 17 to the 1# blast furnace coal powder bin 1, and supply it to the 1# blast furnace coal injection tank 4 for injection.

[0040] Figure 2It is shown that the coal powder recycling pipeline includes the 1# blast furnace coal powder recycling pipeline 25 and the 2# blast furnace coal powder recycling pipeline 26. The 1# blast furnace coal powder recycling pipeline 25 is installed between the 1# blast furnace coal injection tank 4 and the coal powder mill 9, and the 2# blast furnace coal powder recycling pipeline 26 is installed between the 2# blast furnace coal injection tank 17 and the coal powder mill 9, which respectively transport the coal powder from the 1# blast furnace coal injection tank 4 and the 2# blast furnace coal injection tank 17 back to the coal powder mill 9 for re-grinding.

[0041] Figure 2 It is shown that the pipeline inlet of the 1# blast furnace coal powder return pipe 22 is connected between the 1# blast furnace coal injection tank coal outlet valve 7 and the 1# blast furnace coal injection tank coal supply valve 8 of the coal injection pipe at the lower part of the 1# blast furnace coal injection tank 4, a 1# blast furnace coal powder return valve 27 is installed in the 1# blast furnace coal powder return pipe 22, a 1# blast furnace coal powder bin inlet valve 28 is installed at the pipeline inlet of the 1# blast furnace coal powder return pipe 22 and the 1# blast furnace coal powder bin 1, and a 1# blast furnace coal powder complementary connecting valve 29 is installed at the connection between the 1# blast furnace coal powder return pipe 22 and the coal powder complementary pipe 24.

[0042] Figure 2 It is shown that the pipeline inlet of the 2# blast furnace coal powder return pipe 23 is connected between the 2# blast furnace coal injection tank coal outlet valve 21 and the 1# blast furnace coal injection tank coal supply valve 20 of the coal injection pipe at the lower part of the 2# blast furnace coal injection tank 17, a 2# blast furnace coal powder return valve 31 is installed in the 2# blast furnace coal powder return pipe 23, a 2# blast furnace coal powder bin inlet valve 32 is installed at the pipeline inlet of the 2# blast furnace coal powder return pipe 23 and the 2# blast furnace coal powder bin 14, and a 1# blast furnace coal powder complementary connecting valve 33 is installed at the connection between the 2# blast furnace coal powder return pipe 23 and the coal powder complementary pipe 24.

[0043] Figure 2 It is shown that the 1# blast furnace coal powder return mill pipeline 22 is equipped with a 1# blast furnace coal powder inlet valve 30 at the entrance of the coal powder mill 9, and the 2# blast furnace coal powder return mill pipeline 23 is equipped with a 2# blast furnace coal powder inlet valve 34 at the entrance of the coal powder mill 9.

[0044] The invention comprises a back-turning operation process, a complementary operation process, and a grinding operation process.

[0045] The rewinding operation process of the present invention is applicable to the following situations:

[0046] First, when the blast furnace suddenly stops supplying coal, the pulverized coal is stored in the coal injection tank for t≤10h, and the temperature of the pulverized coal is 70℃≤T≤80℃. At this time, the pulverized coal can be poured back from the coal injection tank to the pulverized coal bunker of the blast furnace;

[0047] Second, when the coal injection tank needs temporary maintenance, the coal powder in the coal injection tank needs to be emptied, and the manhole needs to be opened for inspection. The coal powder can be poured back into the coal powder bin of the blast furnace.

[0048] The pulverized coal return operation process of the 1# blast furnace coal injection tank 4 is carried out according to the following steps:

[0049] The first step is to open the 1# blast furnace coal injection tank cone fluidizing valve 5 and the 1# blast furnace coal injection tank bottom fluidizing valve 6 of the 1# blast furnace coal injection tank 4, and pressurize the 1# blast furnace coal injection tank 4 to between 0.1 and 0.12 MPa;

[0050] The second step is to open the 1# blast furnace coal powder return valve 27 and the 1# coal powder bunker inlet valve 28 in sequence, and close the 1# blast furnace coal powder complementary connecting valve 29;

[0051] The third step is to open the coal outlet valve 7 of the 1# blast furnace coal injection tank, close the coal supply valve 8 of the 1# blast furnace coal injection tank, control the flow rate of the fluidizing valve 6 at the bottom of the 1# blast furnace coal injection tank to 80m3 / h, control the flow rate of the cone fluidizing valve 5 of the 1# blast furnace coal injection tank to 60m3 / h, and pour the coal powder in the 1# blast furnace coal injection tank 4 back to the 1# blast furnace coal powder bin 1.

[0052] The coal powder return operation process of the coal injection tank 17 of the 2# blast furnace is the same as the coal powder return operation process of the coal injection tank 4 of the 1# blast furnace.

[0053] The complementary operation process of the present invention is applicable to the following situations:

[0054] First, when the blast furnace is out of service for more than 24 hours, the pulverized coal stored in the pulverized coal bin is more than 50 tons, the storage time t≤24 hours, and the pulverized coal temperature T≥70℃, the pulverized coal needs to be returned to another pulverized coal bin for injection into the blast furnace;

[0055] Second, during the overhaul of the pulverized coal mill of this blast furnace, when the other two pulverized coal mills malfunctioned and could not grind coal, the pulverized coal had to be returned to another pulverized coal bin for use in blast furnace injection.

[0056] The pulverized coal complementary operation process of the 1# blast furnace coal injection tank 4 is carried out according to the following steps:

[0057] The first step is to open the lower coal valve 2 of the 1# pulverized coal bin and the coal inlet valve 3 of the 1# blast furnace coal injection tank in sequence. After the 1# blast furnace coal injection tank 4 is loaded with 15-20t of pulverized coal, the lower coal valve 2 of the 1# pulverized coal bin and the coal inlet valve 3 of the 1# blast furnace coal injection tank are closed in sequence.

[0058] The second step is to open the conical fluidizing valve 5 of the 1# blast furnace coal injection tank and the bottom fluidizing valve 6 of the 1# blast furnace coal injection tank, and pressurize the 1# blast furnace coal injection tank 4 to between 0.12 and 0.15 MPa;

[0059] The third step is to open the 1# blast furnace coal powder return valve 27, close the 1# coal powder bunker inlet valve 28, open the 1# blast furnace coal powder complementary connecting valve 29 and the 2# blast furnace coal powder complementary connecting valve 33, and open the 2# blast furnace coal powder return valve 31 and the 2# coal powder bunker inlet valve 32;

[0060] The fourth step is to open the coal outlet valve 21 of the 2# blast furnace coal injection tank, close the coal supply valve 20 of the 2# blast furnace coal injection tank, control the flow rate of the bottom fluidizing valve 19 of the 2# blast furnace coal injection tank to 100m3 / h, and control the flow rate of the cone fluidizing valve 18 of the 2# blast furnace coal injection tank to 80m3 / h, and pour the pulverized coal in the 1# blast furnace coal injection tank 4 back to the 2# pulverized coal bin 14.

[0061] The pulverized coal complementary operation process of the pulverized coal injection tank 17 of the 2# blast furnace is the same as the pulverized coal complementary operation process of the pulverized coal injection tank 4 of the 1# blast furnace.

[0062] The milling operation procedure of the present invention is applicable to the following situations:

[0063] First, the coal powder is stored in the coal powder bin for t≥24h and the temperature is T≤70℃, and the coal powder needs to be re-ground;

[0064] Second, the particle size of qualified coal powder is -200 mesh accounting for more than 70%, and the moisture content is less than 2.0%. If the particle size is unqualified or the moisture content exceeds the standard, it should be put into the mill for re-grinding;

[0065] Third, due to damage to equipment such as vibrating screens and iron removers, impurities entered the pulverized coal bin and then the injection tank. The blast furnace frequently experienced gun blockages, making normal injection impossible and the pulverized coal needed to be re-ground.

[0066] The operation process of feeding the coal injection tank 4 of the 1# blast furnace into the mill is carried out according to the following steps:

[0067] The first step is to open the upper gate valve 11, the coal feeder 12, the lower gate valve 13, and the coal powder mill 9 in sequence to perform normal coal powder grinding operations;

[0068] The second step is to open the lower coal valve 2 of the 1# pulverized coal bin and the coal inlet valve 3 of the 1# blast furnace coal injection tank. After the 1# blast furnace coal injection tank 4 is loaded with 15-20t of pulverized coal, the lower coal valve 2 of the 1# pulverized coal bin and the coal inlet valve 3 of the 1# blast furnace coal injection tank are closed in sequence.

[0069] The third step is to open the conical fluidizing valve 5 of the 1# blast furnace coal injection tank and the bottom fluidizing valve 6 of the 1# blast furnace coal injection tank, and pressurize the 1# blast furnace coal injection tank 4 to between 0.08 and 0.10 MPa;

[0070] Step 4: Close the 1# blast furnace coal powder return valve 27 and open the 1# blast furnace coal powder inlet valve 30 in sequence;

[0071] The fifth step is to open the coal outlet valve 7 of the 1# blast furnace coal injection tank, close the coal supply valve 8 of the 1# blast furnace coal injection tank, control the flow rate of the fluidizing valve 6 at the bottom of the 1# blast furnace coal injection tank to 60m3 / h, and control the flow rate of the conical fluidizing valve 5 of the 1# blast furnace coal injection tank to 50m3 / h, so as to ensure that the inlet and outlet pressure difference of the pulverized coal mill 9 is controlled at about 3.0kpa, and the pulverized coal in the 1# blast furnace coal injection tank 4 is returned to the pulverized coal mill 9. After the pulverized coal is re-ground, it enters the 1# pulverized coal bin 1 or 2# pulverized coal bin 14 through the bag box, ash discharge valve, and vibrating screen for use in blast furnace injection.

[0072] The operation procedure of feeding the coal injection tank 17 of the 2# blast furnace into the mill is the same as the operation procedure of feeding the coal injection tank 4 of the 1# blast furnace into the mill.

[0073] An embodiment of the present invention is as follows:

[0074] The diameter of the 1# blast furnace coal powder return pipe 22 and the 2# blast furnace coal powder return pipe 23 is 100 mm, and the material is wear-resistant steel pipe with a wall thickness of 5 mm;

[0075] The coal powder complementary pipeline 24 has a pipe diameter of 100 mm, is made of stainless steel, and has a wall thickness of 5 mm;

[0076] The pipe diameter of the 1# blast furnace coal powder recycling pipe 25 and the 2# blast furnace coal powder recycling pipe 26 is 100 mm, the material is stainless steel, and the wall thickness is 5 mm;

[0077] The 1# blast furnace coal powder return valve 27, the 2# blast furnace coal powder return valve 31, the 1# coal powder bin inlet valve 28, the 2# coal powder bin inlet valve 32, the 1# blast furnace coal powder complementary connecting valve 29, the 2# blast furnace coal powder complementary connecting valve 33, the 1# blast furnace coal powder inlet valve 30, the 2# blast furnace coal powder inlet valve 34 all adopt the same model:

[0078] Name: Pneumatic hemispheric valve Model: BQ641M-1 Nominal diameter: DN100mm Pressure: 25Mpa.

Claims

1. A method for returning pulverized coal to a blast furnace of a pulverized coal injection device, characterized in that: The blast furnace pulverized coal injection return device comprises a 1# pulverized coal bin (1), a 1# blast furnace coal injection tank (4), a 2# pulverized coal bin (14), a 2# blast furnace coal injection tank (17), a pulverized coal mill (9), a coal bin (10), and a coal feeder (12). The 1# pulverized coal bin (1) and the 1# blast furnace coal injection tank (4), the 2# pulverized coal bin (14) and the 2# blast furnace coal injection tank (17) are respectively connected by conveying pipelines. The coal bin (10) is connected to the pulverized coal mill (9) via the coal feeder (12). A pulverized coal return pipeline, a pulverized coal complementary pipeline (24), and a pulverized coal return mill pipeline are added. The 1# blast furnace pulverized coal return pipeline The pipeline (22) is installed between the 1# blast furnace coal injection tank (4) and the 1# pulverized coal bin (1), the 2# blast furnace coal powder return pipeline (23) is installed between the 2# blast furnace coal injection tank (17) and the 2# pulverized coal bin (14), the pulverized coal complementary pipeline (24) is installed between the 1# blast furnace coal powder return pipeline (22) and the 2# blast furnace coal powder return pipeline (23), the 1# blast furnace coal powder return pipeline (25) is installed between the 1# blast furnace coal injection tank (4) and the pulverized coal mill (9), and the 2# blast furnace coal powder return pipeline (26) is installed between the 2# blast furnace coal injection tank (17) and the pulverized coal mill (9); The pipeline inlet of the 1# blast furnace coal powder return pipeline (22) is connected between the 1# blast furnace coal injection tank coal outlet valve (7) and the 1# blast furnace coal injection tank coal supply valve (8) of the coal injection pipeline at the lower part of the 1# blast furnace coal injection tank (4), the 1# blast furnace coal powder return pipeline (22) is equipped with a 1# blast furnace coal powder return valve (27), and the pipeline inlet between the 1# blast furnace coal powder return pipeline (22) and the 1# coal powder bin (1) is equipped with a 1# coal powder bin inlet valve (28); The pipeline inlet of the 2# blast furnace coal powder return pipeline (23) is connected between the 2# blast furnace coal injection tank coal outlet valve (21) and the 2# blast furnace coal injection tank coal supply valve (20) of the coal injection pipeline at the lower part of the 2# blast furnace coal injection tank (17), the 2# blast furnace coal powder return pipeline (23) is equipped with a 2# blast furnace coal powder return valve (31), and the pipeline outlet between the 2# blast furnace coal powder return pipeline (23) and the 2# coal powder bin (14) is equipped with a 2# coal powder bin inlet valve (32); The pulverized coal complementary pipeline (24) between the pulverized coal return pipeline (22) of the 1# blast furnace and the pulverized coal return pipeline (23) of the 2# blast furnace is respectively installed with a 1# blast furnace pulverized coal complementary connecting valve (29) and a 2# blast furnace pulverized coal complementary connecting valve (33); The 1# blast furnace coal powder return mill pipeline (25) is provided with a 1# blast furnace coal powder inlet valve (30) at the inlet of the coal powder mill (9), and the 2# blast furnace coal powder return mill pipeline (26) is provided with a 2# blast furnace coal powder inlet valve (34) at the inlet of the coal powder mill (9); It includes the back-up operation process, the complementary operation process, and the grinding operation process. The steps of the three operation processes are as follows: The coal powder return operation process of the No. 1 blast furnace coal injection tank (4): The first step is to open the conical fluidizing valve (5) of the 1# blast furnace coal injection tank and the bottom fluidizing valve (6) of the 1# blast furnace coal injection tank, and pressurize the 1# blast furnace coal injection tank (4) to between 0.1 and 0.12 MPa; Step 2: Open the 1# blast furnace coal powder return valve (27) and the 1# coal powder bunker inlet valve (28) in sequence, and close the 1# blast furnace coal powder complementary connecting valve (29); The third step is to open the coal outlet valve (7) of the 1# blast furnace coal injection tank, close the coal supply valve (8) of the 1# blast furnace coal injection tank, and control the flow rate of the bottom fluidizing valve (6) of the 1# blast furnace coal injection tank to 80m 3 / h, the flow rate of the cone fluidizing valve (5) of the 1# blast furnace coal injection tank is controlled to 60m 3 / h, the pulverized coal in the 1# blast furnace coal injection tank (4) is returned to the 1# pulverized coal bin (1); Coal powder complementary operation process of No. 1 blast furnace coal injection tank (4): The first step is to open the lower coal valve (2) of the 1# pulverized coal bin and the coal inlet valve (3) of the 1# blast furnace coal injection tank in sequence. After the 1# blast furnace coal injection tank (4) is loaded with 15-20 tons of pulverized coal, the lower coal valve (2) of the 1# pulverized coal bin and the coal inlet valve (3) of the 1# blast furnace coal injection tank are closed in sequence. The second step is to open the conical fluidizing valve (5) of the 1# blast furnace coal injection tank and the bottom fluidizing valve (6) of the 1# blast furnace coal injection tank, and pressurize the 1# blast furnace coal injection tank (4) to between 0.12 and 0.15 MPa; The third step is to open the 1# blast furnace coal powder return valve (27), close the 1# coal powder bunker inlet valve (28), open the 1# blast furnace coal powder complementary connecting valve (29) and the 2# blast furnace coal powder complementary connecting valve (33), and open the 2# blast furnace coal powder return valve (31) and the 2# coal powder bunker inlet valve (32); Step 4: Open the coal outlet valve (21) of the 2# blast furnace coal injection tank, close the coal supply valve (20) of the 2# blast furnace coal injection tank, and control the flow rate of the bottom fluidizing valve (19) of the 2# blast furnace coal injection tank to 100m 3 / h, the flow rate of the cone fluidizing valve (18) of the 2# blast furnace coal injection tank is controlled to 80m 3 / h, the pulverized coal in the 1# blast furnace coal injection tank (4) is returned to the 2# pulverized coal bin (14); The operation process of feeding the coal injection tank (4) of the 1# blast furnace into the mill: The first step is to open the upper gate valve (11), the coal feeder (12), the lower gate valve (13), and the coal pulverizer (9) in sequence to perform normal coal pulverization operations; The second step is to open the lower coal valve (2) of the 1# pulverized coal bin and the coal inlet valve (3) of the 1# blast furnace coal injection tank. After the 1# blast furnace coal injection tank (4) is loaded with 15-20 tons of pulverized coal, the lower coal valve (2) of the 1# pulverized coal bin and the coal inlet valve (3) of the 1# blast furnace coal injection tank are closed in sequence. The third step is to open the conical fluidizing valve (5) of the 1# blast furnace coal injection tank and the bottom fluidizing valve (6) of the 1# blast furnace coal injection tank, and pressurize the 1# blast furnace coal injection tank (4) to between 0.08 and 0.10 MPa; Step 4: Close the 1# blast furnace coal powder return valve (27) and open the 1# blast furnace coal powder inlet valve (30) in sequence; Step 5: Open the coal outlet valve (7) of the 1# blast furnace coal injection tank, close the coal supply valve (8) of the 1# blast furnace coal injection tank, and control the flow rate of the bottom fluidizing valve (6) of the 1# blast furnace coal injection tank to 60m 3 / h, the flow rate of the cone fluidizing valve (5) of the 1# blast furnace coal injection tank is controlled to 50m 3 / h, to ensure that the pressure difference between the inlet and outlet of the coal powder mill is controlled at 3.0 kPa, the coal powder in the No. 1 blast furnace coal injection tank (4) is returned to the coal powder mill (9), and after the coal powder is re-ground, it enters the No. 1 coal powder bin (1) or the No. 2 coal powder bin (14) through the bag box, ash discharge valve, and vibrating screen for use in blast furnace injection.

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