Anti-clogging and detection device for coal outlet pipe of parallel pulverized coal injection tank

Abstract

This utility model discloses a parallel pulverized coal injection tank coal outlet pipe anti-blockage and detection device, relating to the field of pulverized coal injection technology. It includes several injection tanks, each connected to a coal conveying branch pipe. The other end of each coal conveying branch pipe is connected to a main coal conveying pipe, which in turn connects to the blast furnace tuyeres. Each coal conveying branch pipe includes a coal discharge valve connected to the main coal conveying pipe. A corresponding auxiliary blowing valve branch pipe is also connected between each coal discharge valve and the main coal conveying pipe. The other end of each auxiliary blowing valve branch pipe is connected to a nitrogen source. Each auxiliary blowing valve branch pipe includes an auxiliary blowing shut-off valve and a flow switch. The auxiliary blowing shut-off valve controls the opening and closing of the auxiliary blowing valve branch pipe to prevent pipe blockage. The flow switch detects whether the auxiliary nitrogen flow rate in the auxiliary blowing valve branch pipe is normal, thereby determining whether the pipe is blocked. This device can prevent large fluctuations in injection and coal blockage accidents caused by pulverized coal backflow, and provides early warning by determining whether the pipe is blocked, thus achieving the effect of preventing coal shortage accidents caused by pulverized coal backflow.

Description

Technical Field

[0001] This utility model relates to the field of pulverized coal injection technology, and in particular to a device for preventing and detecting blockage in the coal outlet pipe of a parallel pulverized coal injection tank. Background Technology

[0002] Pulverized coal injection systems are standard equipment in modern blast furnace smelting production. Nowadays, most blast furnaces are developing towards higher capacity and higher efficiency, and the pulverized coal injection load is also increasing, with injection tank volumes generally exceeding 40 cubic meters. Given the large tank volume and height, coupled with plant height restrictions, injection tanks now mostly use a parallel tank configuration to continuously supply pulverized coal to the blast furnace. Common configurations include two parallel tanks or three tanks circulating injection, and the make-up gas circuit typically has two different configurations: a shared single circuit and independent multi-circuit circuits.

[0003] In systems where the supplementary gas supply circuit is a shared single-circuit gas supply, the length of the coal outlet pipe from each injection tank to the supplementary gas mixer is relatively long, resulting in greater coal flow resistance and significant fluctuations during tank switching. Especially when the system has been running for an extended period and there are minor internal leaks in the system valves, coal dust backflow can occur in the coal outlet pipe branches not in injection mode. Minor external leaks in the equipment can also cause coal dust backflow. When the leak only isolates the coal dust through gas, coal dust will gradually accumulate in the coal outlet pipe branches, leading to pipe blockage and coal supply interruption accidents.

[0004] Therefore, in order to prevent pipe blockage and ensure continuous and stable pulverized coal injection in the blast furnace, it is necessary to take certain technical measures to eliminate the current situation of continuous pulverized coal backflow, reduce injection fluctuations during transfer, and reduce the probability of pipe blockage accidents where coal is not produced. Utility Model Content

[0005] The purpose of this invention is to provide a device for preventing and detecting blockages in the coal outlet pipe of a parallel pulverized coal injection tank. An auxiliary blowing valve is designed on the coal conveying pipe at the rear end of each coal outlet valve in the parallel tank. A small amount of nitrogen is pulsed into the auxiliary blowing valve to prevent pulverized coal backflow, thereby preventing significant fluctuations in injection and blockage accidents caused by pulverized coal backflow. The auxiliary blowing valve is opened for a certain period before the tank is switched over, and the flow rate of the injected nitrogen is detected to determine if the pipeline is blocked, thus providing early warning and preventing coal shortage accidents during tank switching.

[0006] The above-mentioned technical objective of this utility model is achieved through the following technical solution:

[0007] A device for preventing and detecting blockage of coal outlet pipes of parallel pulverized coal injection tanks includes several injection tanks, each injection tank being connected to a coal conveying branch pipe, the other end of each coal conveying branch pipe being connected to a main coal conveying pipe, and the main coal conveying pipe being connected to the blast furnace tuyeres.

[0008] Each coal conveying branch pipe includes a coal discharge valve connected to the main coal conveying pipe. Each coal discharge valve and the main coal conveying pipe are also connected to a corresponding auxiliary blowing valve branch pipe. The other end of the auxiliary blowing valve branch pipe is connected to a nitrogen source. The auxiliary blowing valve branch pipe includes an auxiliary blowing shut-off valve and a flow switch. The auxiliary blowing shut-off valve controls the opening and closing of the auxiliary blowing valve branch pipe to prevent pipe blockage. The flow switch detects whether the flow rate of auxiliary blowing nitrogen in the auxiliary blowing valve branch pipe is normal, thereby determining whether the pipe is blocked.

[0009] Furthermore, the blowing valve pipeline branch also includes a one-way check valve to control the blowing valve pipeline branch to blow nitrogen into the coal conveying branch in one direction.

[0010] Furthermore, the purging valve pipeline branch also includes a manual shut-off valve to control and adjust the flow rate of nitrogen gas.

[0011] Furthermore, the blow-assisted shut-off valve is a pneumatic shut-off valve.

[0012] Furthermore, the coal conveying branch pipe includes a manually operated maintenance ball valve connected to one or both sides of the coal discharge valve.

[0013] Furthermore, the main coal conveying pipe includes a coal conveying valve, which controls the opening and closing of the main coal conveying pipe.

[0014] Furthermore, the main coal conveying pipe includes a gas-making mixer, one inlet end of which is connected to each coal conveying branch pipe, the other inlet end of which is connected to the gas-making branch, and the outlet end of which is connected to the blast furnace tuyeres. The gas-making branch includes a gas-making gas source and a gas-making shut-off valve.

[0015] Furthermore, the supplementary air source is a compressed air source.

[0016] In summary, this utility model has the following beneficial effects:

[0017] By adding a blowing valve pipeline and intermittently adding a small amount of nitrogen, it is possible to effectively prevent the continuous backflow of coal dust caused by slight internal or external leakage of valves, facilities, and connectors in the coal conveying pipeline section, and to prevent the increase in resistance caused by coal dust accumulation in the branch pipeline, which could lead to a tank-turning blockage accident. By detecting the continuity of nitrogen flow rate over a longer period before tank-turning, it is possible to determine whether the branch pipeline is already blocked, thereby providing early warning and allowing for manual intervention to eliminate the blockage. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall principle of a parallel coal powder injection tank coal outlet pipe anti-blocking and detection device according to the present invention.

[0019] Figure 2 This is a schematic diagram of the structure of a parallel coal powder injection tank coal outlet pipe anti-blocking and blockage detection device (the branch of the blowing valve pipeline is not shown).

[0020] In the diagram: 001, coal conveying valve; 002, gas mixing unit; 003, gas shut-off valve; 004, manual maintenance ball valve; 005, coal discharge valve; 101, branch of the first auxiliary blowing valve pipeline; 102, branch of the second auxiliary blowing valve pipeline; 103, branch of the third auxiliary blowing valve pipeline; 104, one-way check valve; 105, manual shut-off valve; 106, flow switch; 107, auxiliary blowing shut-off valve. Detailed Implementation

[0021] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings. These embodiments do not constitute a limitation on this utility model. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this application.

[0022] A device for preventing and detecting blockage in the coal outlet pipe of a parallel pulverized coal injection tank, such as Figure 1 and Figure 2 As shown, it includes several injection tanks, which are connected to coal conveying branch pipes. The other end of each coal conveying branch pipe is connected to the main coal conveying pipe, which is connected to the blast furnace tuyeres.

[0023] Each coal conveying branch pipe includes a coal discharge valve 005 connected to the main coal conveying pipe. Each coal discharge valve 005 and the main coal conveying pipe are also connected to a corresponding auxiliary blowing valve pipeline branch. The other end of the auxiliary blowing valve pipeline branch is connected to a nitrogen source. (An auxiliary blowing valve pipeline branch is set on the coal conveying pipe at the rear end of the coal discharge valve 005 of each injection tank. In this embodiment, there are three injection tanks, namely injection tank A, injection tank B and injection tank C, which are respectively connected to the first auxiliary blowing valve pipeline branch 101, the second auxiliary blowing valve pipeline branch 102 and the third auxiliary blowing valve pipeline branch 103.)

[0024] like Figure 1 As shown, each purging valve pipeline branch includes a purging shut-off valve 107 and a flow switch 106. The purging shut-off valve 107 controls the opening and closing of the purging valve pipeline branch to prevent pipe blockage. The flow switch 106 detects whether the flow rate of the purging nitrogen in the purging valve pipeline branch is normal. It is used to detect whether the flow rate of the replenished nitrogen is normal. When the flow rate is less than the set value for a certain period of time, the pipeline is determined to be blocked.

[0025] The blowing valve pipeline branch specifically includes a blowing shut-off valve 107, a flow switch 106, a manual shut-off valve 105, and a one-way check valve 104, arranged sequentially from the nitrogen source. The blowing shut-off valve 107 is a pneumatic shut-off valve connected to the nitrogen source. It opens in a pulsed manner within a certain period to replenish a small amount of nitrogen to compensate for coal powder backflow caused by minor internal or external leakage of the system pipeline facilities and to prevent pipe blockage. The blowing shut-off valve 107 is opened for 60 seconds 5 minutes before the tank is transferred. The flow switch 106 detects whether the blowing nitrogen flow is normal, thereby achieving the purpose of detecting blockage. In some embodiments, the blowing shut-off valve 107 can be automatically opened and closed at timed intervals by means of a PLC control system or other means. When it is opened, nitrogen is replenished into the coal conveying pipeline branch after the coal valve 005 of the corresponding blowing tank to clear the pipeline.

[0026] The manual shut-off valve 105 controls and adjusts the flow rate of nitrogen (usually maintained at a certain opening degree without change; the opening value is set during commissioning. When the flow rate is large, the nitrogen will cause fluctuations in the amount of pulverized coal injected. When the flow rate is small, it may not be enough to eliminate the coal dust backflow phenomenon, and the flow switch 106 will not be able to detect it properly. Therefore, it needs to be fixed to a suitable opening value after commissioning). The one-way check valve 104 controls the nitrogen to be blown into the coal conveying branch pipe in one direction through the auxiliary blowing valve pipe branch, which is used to prevent coal dust from flowing back into the auxiliary blowing valve pipe branch and causing blockage of the auxiliary blowing valve pipe branch.

[0027] like Figure 1 As shown, each coal conveying branch pipe includes a manual maintenance ball valve 004 connected to one or both sides of the coal discharge valve 005. In this embodiment, there are two sides. One manual maintenance ball valve 004 is located between the corresponding injection tank and the coal discharge valve 005, and the other is located on the other side of the coal discharge valve 005 and between the corresponding auxiliary blowing valve pipeline branch and the main coal conveying pipe.

[0028] like Figure 1 As shown, the main coal conveying pipe includes a coal conveying valve 001 and a supplementary gas mixer 002. One inlet end of the supplementary gas mixer 002 is connected to each coal conveying branch pipe, and the other inlet end is connected to the supplementary gas branch. The outlet end is connected to the coal conveying valve 001, and the other end of the coal conveying valve 001 is connected to the blast furnace tuyeres. The coal conveying valve 001 controls the opening and closing of the main coal conveying pipe. The supplementary gas branch includes a supplementary gas source and a supplementary gas cut-off valve 003 (in this embodiment, the supplementary gas source is a compressed air source). The supplementary gas cut-off valve 003 controls the opening and closing of the supplementary gas branch, so that the compressed air source supplements gas to the main coal conveying pipe.

[0029] Working principle;

[0030] 1. During normal production, one of the three injection tanks is always in a pressurized injection state, while the other two tanks are in a work cycle of unloading pressure, loading coal powder, replenishing pressure and fluidization, and waiting for the tank to be switched for injection.

[0031] In existing technology, when the pressure in a certain tank is low, assuming there is a slight internal leakage in the coal discharge valve 005 connected to the main coal conveying pipe, the pulverized coal in the tank during the injection process will flow back to the tank through the connected coal conveying pipe. Due to the difference in leakage characteristics between gas and powder, the amount of leaked gas is greater than the amount of powder, so the concentration of pulverized coal in the return pipe section gradually increases, and the resistance becomes greater and greater. When the coal is transferred to the tank for injection, the tank pressure may not be sufficient to push the pulverized coal out of the tank, thus causing a blockage and coal supply interruption accident.

[0032] There is also a second type of leakage hazard, which is a minor external leakage. If there is an external leakage in the coal down valve 005, manual ball valve, flexible connection, cleaning valve and other facilities of the injection tank under low tank pressure, a certain amount of coal powder backflow will also occur, which may also cause a blockage and coal interruption accident.

[0033] Nitrogen is used as the gas medium for pressurizing, fluidizing, and boiling the blast furnace. The pressure of the compressed air source and nitrogen source is usually high, around 1.2 MPa. The blast furnace tuyeres are also pressurized. Therefore, the coal conveying pipe, which is always conveying pulverized coal, maintains a high pressure. The system pressure at the initial conveying end is close to 0.7 MPa. Therefore, when a tank is depressurized to zero pressure, a very high pressure difference is formed between the coal conveying pipe and the zero-pressure tank. Even slight internal or external leakage will cause pulverized coal backflow to occur significantly. Considering the normal service life and replacement cycle of the equipment, it is usually not possible to guarantee that all equipment will be free of defects during operation. Therefore, it is necessary to consider targeted strategies for minor leakage hazards.

[0034] 2. Therefore, in this embodiment, the newly designed blast furnace auxiliary valve pipeline solves the problem of continuous pulverized coal backflow caused by slight internal and external leakage of the facility. Normally, during normal production, the coal discharge valve 005 of one tank is open at any time. The high tank pressure maintained by this tank supplies the pulverized coal in the tank into the coal conveying pipe, where it is mixed with the make-up gas medium in the make-up gas mixer 002. Normally, the make-up gas shut-off valve 003 and the coal conveying valve 001 are both normally open, allowing the mixed pulverized coal to be supplied into the blast furnace tuyeres.

[0035] After the tank is switched over, the coal valve 005 of the tank body that stops purging will be closed. Then the empty tank will start to depressurize to near zero pressure, and then coal powder will be loaded. Then the tank pressure will be established through pressurization, fluidization and boiling gas, waiting for the tank to be switched over and purged.

[0036] When the coal discharge valve 005 of a certain tank is in the closed state, and the tank is still in automatic injection cycle, the auxiliary injection shut-off valve 107 of the auxiliary injection valve pipeline will be opened in a pulse-type manner, and the logic is as follows:

[0037] Logic 1: Every 3 minutes, the blow-off valve 107 opens for 5 seconds (the specific opening time can be increased by adjusting the probability of pipe blockage).

[0038] Logic 2: During the purging cycle, when the weight of the tank body in the purging state drops to a preset value of X tons (this weight lasts for about 5 minutes until the tank body is purged), the purging shut-off valve 107 is opened for 60 seconds. At the same time, the signal of the corresponding flow switch 106 is tracked. If the valve opening signal and the flow signal cannot be in the same state simultaneously for more than 10 seconds, a pipe blocking command is output.

[0039] When a pipe blockage alarm occurs, manual intervention is required immediately. The blocked pipe can be cleared by tapping or vibrating the blocked branch, or by intermittently and continuously opening the blow-off valve 107 until the flow switch 106 signal of the blow-off branch remains at an interval.

[0040] If the blockage cannot be cleared in time, the blocked tank must be removed from the automatic circulation, and emergency pressurization or other operations should be performed on another tank to maintain the continuity of tank-switching and purging. For tanks removed from circulation, in addition to clearing the blockage again through the purging pipeline, the blockage can also be cleared by cleaning and emptying the pipeline. After the fault is cleared, the faulty tank should be manually switched back into the tank-switching cycle, and then gradually switched back into the automatic tank-switching cycle.

[0041] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model. Those skilled in the art can make various modifications or equivalent substitutions to the present utility model within its substance and protection scope, and such modifications or equivalent substitutions should also be considered to fall within the protection scope of the present utility model's technical solution.

Claims

1. A device for preventing and detecting blockage in the coal outlet pipe of a parallel pulverized coal injection tank, characterized in that: It includes several injection tanks, which are connected to coal conveying branch pipes. The other end of each coal conveying branch pipe is connected to the main coal conveying pipe, which is connected to the blast furnace tuyeres. Each coal conveying branch pipe includes a coal discharge valve connected to the main coal conveying pipe. Each coal discharge valve and the main coal conveying pipe are also connected to a corresponding auxiliary blowing valve branch pipe. The other end of the auxiliary blowing valve branch pipe is connected to a nitrogen source. The auxiliary blowing valve branch pipe includes an auxiliary blowing shut-off valve and a flow switch. The auxiliary blowing shut-off valve controls the opening and closing of the auxiliary blowing valve branch pipe to prevent pipe blockage. The flow switch detects whether the flow rate of auxiliary blowing nitrogen in the auxiliary blowing valve branch pipe is normal, thereby determining whether the pipe is blocked.

2. The parallel coal injection tank outlet pipe anti-blocking and blocking detection device according to claim 1, characterized in that: The branch of the purging valve pipeline also includes a one-way check valve, which controls the purging valve pipeline branch to purge nitrogen gas into the coal conveying branch in one direction.

3. The parallel coal injection tank outlet pipe anti-blocking and blocking detection device according to claim 1 or 2, characterized in that: The purging valve pipeline branch also includes a manual shut-off valve to control and adjust the flow rate of nitrogen gas.

4. The parallel pulverized coal injection tank coal pipe anti-blocking and blocking detection device according to claim 1, characterized in that: The blow-assisted shut-off valve is a pneumatic shut-off valve.

5. The parallel coal injection tank outlet pipe anti-blocking and blocking detection device according to claim 1 or 4, characterized in that: The coal conveying branch pipe includes a manually operated maintenance ball valve connected to one or both sides of the coal delivery valve.

6. The parallel pulverized coal injection tank coal pipe anti-blocking and blocking detection device according to claim 1, characterized in that: The main coal conveying pipe includes a coal conveying valve, which controls the opening and closing of the main coal conveying pipe.

7. The parallel coal injection tank outlet pipe anti-blocking and blocking detection device according to claim 1 or 6, characterized in that: The main coal conveying pipe includes a gas-making mixer. One inlet end of the gas-making mixer is connected to each coal conveying branch pipe, the other inlet end is connected to the gas-making branch, and the outlet end is connected to the blast furnace tuyeres. The gas-making branch includes a gas-making gas source and a gas-making shut-off valve.

8. The parallel pulverized coal injection tank coal pipe anti-blocking and blocking detection device according to claim 7, characterized in that: The supplementary air source is a compressed air source.

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