Device and method for removing phase change substances in blast furnace

Abstract

The invention discloses a device and a method for removing phase-change substances in a blast furnace, and belongs to the field of metallurgy. The device comprises a blast furnace, branch gas pipes, an annular pipeline, a stop valve I, a gravity dust collector, a stop valve II, a regulating valve, a stop valve III, a nitrogen backflushing pipe and a valve, a nitrogen cleaning pipe and a valve, a nitrogen cleaning gas diffusing pipe and a valve, a phase change material recovery tank, and a phase change material discharge hole and a valve. According to the characteristics of phase-change substances in the furnace, a furnace section with large vapor pressure is selected, holes are formed in the furnace wall, part of coal gas is led out, the coal gas is conveyed to the position from the top of the blast furnace to the front portion of a dust remover, meanwhile, the phase-change substances are discharged out of the furnace along with the coal gas, and the temperature of the coal gas is controlled to be lower than the bearable temperature of a dust removal filter material through natural cooling or forced cooling measures. The temperature of the mixed coal gas is lower than the freezing point temperature of the phase-change substance, and the phase-change substance can be captured in the dust remover. By adopting the scheme, the blast furnace gas utilization rate can be obviously improved, the comprehensive coke ratio is reduced, and the blast furnace gas permeability is obviously improved.

Description

Technical Field

[0001] The invention belongs to the field of metallurgy, and in particular relates to a device and a method for removing phase-change substances in a blast furnace. Background Art

[0002] Blast furnace ironmaking is still the most important ironmaking process. It is generally believed that it is a high-energy-consuming ironmaking process. However, from the perspective of carbon footprint, it is entirely possible to become a green and low-carbon full-process ironmaking process. How to reduce the energy consumption of this process has always been an important issue in the steel industry.

[0003] A blast furnace is a very special smelting equipment. The maximum temperature in the tuyere area of ​​the furnace can reach about 2400℃, the molten pool temperature is about 1500℃, and the furnace top is only about 200℃. Since the furnace is full of charge, the temperature field distribution changes relatively evenly. Many substances in the blast furnace exist in three states of gas, liquid and solid. These substances are gasified in the high temperature zone. As the gas rises and the temperature decreases, the saturated vapor pressure of these substances decreases. They will precipitate condensation or solidification on the surface of the charge, and then descend with the charge. After the descending temperature rises, they will be gasified again and ascend again, circulating and enriching in the furnace. Condensation prevents the metallurgical reaction between the charge and the coal gas, reduces the smelting efficiency and increases the overall energy consumption; condensation on the charge surface adheres to dust, deteriorates the charge permeability, increases the consumption of blast kinetic energy, and also reduces the smelting efficiency; some substances solidify in the coke gaps, and due to the large difference in expansion coefficients, the coke strength will be reduced and pulverized, which will increase the coke consumption and deteriorate the charge permeability; these substances will also condense on the furnace wall, and after condensation and adhesion of dust, the furnace wall will be nodulated, resulting in the charge not being able to descend smoothly, and in severe cases, the smelting cannot be carried out. This phenomenon exists in almost all blast furnace smelting, but the severity varies, and it has seriously restricted the advantages of blast furnace smelting.

[0004] At present, the usual method to remove these substances is to overdevelop the central airflow, so that the central airflow temperature is higher than the solidification temperature of the phase change material, and the phase change material is removed in the gaseous state. The disadvantage of this removal method is high energy consumption. When the central airflow is overdeveloped, the edge airflow will weaken, the edge charge temperature will decrease, the condensation of the phase change material will increase, the air permeability will deteriorate, the edge iron flow will weaken, and the molten iron temperature at the edge of the furnace will decrease, which will cause the titanium carbide and titanium nitride in the furnace to precipitate and scale, which will not only swell the furnace bottom, but also cause the furnace wall to thicken. Changes in the furnace body structural parameters will bring a series of problems to the operation of the blast furnace. Therefore, it is very important to develop a suitable device and method for removing phase change materials from the blast furnace. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention aims to provide a device and method for removing phase change materials in a blast furnace.

[0006] According to the characteristics of the phase change material in the furnace, the furnace section with a larger vapor pressure is selected, and a hole is opened in the furnace wall to lead out part of the coal gas, and the coal gas is sent to the top of the blast furnace to the front part of the dust collector. At the same time, the phase change material is discharged from the furnace with the coal gas. Through natural cooling or forced cooling measures, the coal gas temperature is controlled to be lower than the temperature that the dust removal filter material can withstand. After mixing, the coal gas temperature is lower than the freezing point temperature of these phase change materials, and these phase change materials will be captured in the dust collector. After drainage and elimination, the vapor pressure of the phase change material in the furnace will gradually decrease, and the side effects of the phase change material will continue to decrease. When the vapor pressure of the phase change material in the furnace is reduced to a level that has no effect on the operation of the blast furnace, that is, when it returns to the normal smelting state, the coal gas drainage is stopped. When the resistance in the furnace increases, the drainage and elimination are started again. During the transmission of coal gas in the transmission pipeline, due to the consideration of the temperature that the dust bag can withstand, through natural cooling or forced cooling measures, some phase change materials will condense on the transmission pipeline. Therefore, when designing the pipeline, it is necessary to simultaneously consider collecting and discharging these substances to avoid pipeline blockage.

[0007] The phase change material described in the present invention refers to a material including zinc, potassium sodium alkali, cadmium, antimony, etc., which can form a gas-liquid-solid three-state cyclic change in a blast furnace.

[0008] A device for removing phase change material in a blast furnace comprises a blast furnace, a bronchial pipe, a ring pipeline, a stop valve I, a gravity dust collector, a stop valve II, a regulating valve, a stop valve III, a nitrogen recoil pipe and valve, a nitrogen purge pipe and valve, a nitrogen purge gas release pipe and valve, a phase change material recovery tank, and a phase change material discharge hole and valve.

[0009] A plurality of air intake holes are provided at the same height selected on the blast furnace body, and are connected to one end of a plurality of bronchial pipes, and the other end of the bronchial pipe is connected to the set annular pipe, and the annular pipe sends the drawn gas to the gravity dust collector through the pipeline, and a stop valve II is arranged between the annular pipe and the gravity dust collector. After the coal gas is dusted by the gravity dust collector, it is sent to any position in front of the gravity dust collector from the furnace top through the pipeline, and finally enters the coal gas recovery system. A stop valve I is arranged on each bronchial pipe, and a nitrogen recoil pipe and valve are added in front of the stop valve I to clean the blocked materials, and the corresponding stop valve I is closed when the recoil nitrogen is started. A nitrogen purge pipe and valve are arranged on the annular pipe. A regulating valve is arranged between the gravity dust collector and the coal gas recovery system, and a stop valve III is arranged between the regulating valve and the coal gas recovery system. A nitrogen purge gas release pipe and valve are arranged between the regulating valve and the stop valve III. At the lowest point of the pipe connecting the gravity dust collector and the gas recovery system, a phase change material recovery tank is installed, and a phase change material discharge hole and valve are installed. The gravity dust collector and the pipes and valves in front of the gravity dust collector need to be insulated. The phase change material recovery tank needs to be insulated, and the pipe connecting the gravity dust collector and the gas recovery system is not insulated. It needs to be cooled naturally or enhanced by increasing the circulation and heat dissipation area to reduce the gas flow rate, or adding fins to the pipe wall to increase the heat dissipation area. Spray cooling measures can also be taken. The material selection of the entire system should focus on the gas temperature factor.

[0010] The selection of the position of the air intake holes needs to be in an area above the boiling point of the phase change material to be removed, and in an area with a high vapor pressure of the pre-excluded phase change material. The high vapor pressure of the phase change material in the drawn-out coal gas can increase the speed of removing the phase change material, and can also reduce the amount of air intake, reducing the heat loss of the drawn-out coal gas. Therefore, when specifically selecting the position of the air intake holes, first, it is necessary to determine the area with a high vapor pressure of the phase change material to be removed based on the saturated vapor pressure curve of the phase change material to be removed; second, the position of the air intake holes should be higher than the fluctuation area of ​​the soft melting zone of the blast furnace to avoid the soft melting material from blocking the air intake pipe; third, when selecting the air intake area, the heat resistance of the air intake pipe material should also be considered to ensure the safety of the air intake process. Based on the above three factors, the position of the air intake holes is finally determined.

[0011] The speed at which phase change material is produced in the furnace is determined by the speed at which the precursor of the phase change material is brought into the furnace. Therefore, the speed at which the precursor is brought into the furnace can be calculated based on the composition of the furnace charge, and the production speed of the phase change material can be predicted through the precursor.

[0012] The design of the air intake volume and air intake holes is calculated based on the predicted maximum speed of phase change material generation in the furnace. The speed of phase change material brought out by the drawn gas must be greater than or equal to the maximum speed of phase change material generation in the furnace. Then, based on the vapor pressure of the phase change material at the determined position of the air intake hole, the concentration of phase change material in the gas under the drawn-out working condition per cubic meter is calculated, and the amount of drawn gas (referred to as the air intake volume) is calculated accordingly. If a continuous exclusion method is adopted, it is sufficient to ensure that the speed of removing the phase change material is slightly greater than the speed of generating the phase change material; if a staged exclusion method is adopted, a large amount of gas can be drawn out to quickly remove the phase change material. After the furnace condition returns to normal, the coal gas is stopped, and the phase change material removal operation is terminated. When the enrichment of phase change material occurs again and affects the normal operation of smelting, the phase change material removal operation is started again. The main manifestations of phase change material enrichment are poor permeability of the charge, increased blast resistance, and reduced furnace top pressure. In order to reduce the impact of increased air intake on smelting, it is recommended that the air intake should not exceed 20% of the total gas volume of the blast furnace, preferably controlled at less than 10% of the total gas volume of the blast furnace. After determining the air intake, determine the flow rate of the drawn gas. It is recommended that the flow rate of the drawn gas be less than 15 m / s, preferably less than 10 m / s, to avoid excessive flow rate and the airflow taking out the charge. After the air intake and the flow rate of the drawn gas are determined, the total drawn gas flow cross-sectional area can be calculated. In order to reduce the impact of the drawn gas on the distribution of the blast furnace gas flow, a multi-point air intake method is adopted, and multiple holes are opened in the blast furnace wall. The more holes are opened, the smaller the impact on the distribution of the blast furnace gas flow, but the more holes are opened, the more control points are located, the greater the construction amount, and the more investment is made. However, opening small holes does not require changing the water-cooled wall, and holes can be opened in the gap between the water-cooled tubes. If large holes are opened, the construction amount is small, the control points are few, and the investment is small, but the water-cooled wall design needs to be changed and the water-cooled wall needs to be remade. According to the actual situation of each blast furnace, the number of air intake holes is determined, and the cross-sectional area of ​​each air intake hole is divided by the number of holes to obtain the cross-sectional area of ​​each air intake hole, and the hole diameter is calculated based on the cross-sectional area.

[0013] The design principle of the air duct holes is: the sum of the internal flow areas of all air ducts and bronchi ≥ the calculated total gas flow cross-sectional area.

[0014] In order to ensure that the drawn-out coal gas will not cause high-temperature damage to the gas recovery system when it enters the gas recovery system, cooling measures must be taken on the gas pipeline at the rear of the gravity dust collector, or heat dissipation fins must be installed on the pipeline to naturally cool the drawn-out coal gas by natural wind, or by reducing the flow rate and increasing the heat dissipation area, or by using water spray to enhance cooling.

[0015] Insulation measures are taken for the front pipeline and annular pipeline of the gravity dust collector to prevent the phase change material from condensing and precipitating at the front of the gravity dust collector, causing dust to agglomerate inside the gravity dust collector or adhere to the dust collector wall.

[0016] A method for removing phase change substances in a blast furnace, operation process:

[0017] 1. System cleaning and pressurization: Stop valves I and III, phase change material discharge holes and valves, and dust collector ash discharge system are all in the closed state. Open stop valve II and regulating valve, open nitrogen purge pipe and valve, open nitrogen purge gas release pipe and valve, and purge the system with nitrogen for 10-15 minutes to remove air in the system. Close the nitrogen purge gas release pipe and valve, pressurize the system to the pressure in the blast furnace close to the air vent, close the nitrogen purge pipe and valve and regulating valve, and end system cleaning and pressurization.

[0018] 2. Open stop valve I and stop valve III in sequence, and then gradually open the regulating valve to remove the phase change material system and put it into working state.

[0019] 3. Regularly discharge dust: The dust collector discharge system uses a two-stage valve. When discharging dust from the dust collector, first close the upper valve and then open the lower valve.

[0020] 4. In order to prevent the high-temperature coal gas from damaging the dust removal system, the connection pipe between the gravity dust collector and the coal gas recovery system adopts an enhanced cooling mode. After the coal gas is cooled, phase change substances will condense and precipitate. In order to avoid pipe blockage, a phase change substance recovery tank is set at the lowest point of this section of the pipeline to recover various condensed precipitates. The phase change substance recovery tank needs to be equipped with a liquid level gauge. When the precipitate liquid level reaches the design upper limit, the phase change substance discharge hole and valve are opened to discharge the condensed phase change substance. When the discharge reaches the lower limit of the liquid level, the phase change substance discharge hole and valve are closed.

[0021] 5. If the continuous elimination mode is selected, it will always operate in this mode. If the staged elimination mode is selected, when the blast furnace operation resistance returns to normal, close the stop valve I and stop valve III, the phase change material elimination system stops working, and the blast furnace enters the normal smelting state. When the blast furnace air permeability deteriorates, start the phase change material elimination system again. When the phase change material elimination system stops working, open the phase change material discharge hole and valve to completely release the phase change condensed material.

[0022] Advantages and effects of the present invention:

[0023] 1. Compared with the prior art, the present invention does not remove the blast furnace phase change material by developing the central airflow, and has low energy consumption. It not only overcomes the problems of increased condensation of the edge phase change material and poor air permeability in the prior art, but also overcomes the problems of precipitation and scaling of titanium carbide and titanium nitride in the furnace due to weakening of the edge iron flow and lowering of the molten iron temperature at the edge of the furnace, which leads to swelling of the furnace bottom and thickening of the furnace wall.

[0024] 2. After adopting the technical solution of the present invention, the utilization rate of blast furnace gas is significantly improved, the comprehensive coke ratio is reduced, the permeability of the blast furnace is significantly improved, the resistance of the blast furnace charge is significantly reduced, and the utilization coefficient of the blast furnace is improved.

[0025] 3. Since the problem of cyclic enrichment of phase-change materials in blast furnaces has been solved, the control of phase-change elements in blast furnace charging can be relaxed. Various zinc-containing materials and alkali metal-containing materials that could not be used in blast furnaces can be used for smelting in blast furnaces by using the technology of the present invention, which can greatly reduce the procurement cost of blast furnace charging. Various solid wastes that could not be used before have now become valuable raw materials, which can be said to be turning waste into treasure. It not only handles solid waste, but also increases social resources.

[0026] 4. Compared with the traditional process of eliminating phase change materials, this process is flexible in operation, thorough in elimination, has little impact on the smelting process, and is low in cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The overall structure diagram of a device for removing phase change materials in a blast furnace is shown;

[0028] Figure 2 A schematic diagram of the structure of a blast furnace portion of a device for removing phase-change materials in a blast furnace;

[0029] Figure 3 It is a partial structural schematic diagram of a device for removing phase-change materials in a blast furnace, from a gravity dust collector to a gas recovery system;

[0030] Figure 4 It is a schematic diagram of the structure between the regulating valve and the stop valve III of a device for removing phase change materials in a blast furnace;

[0031] In the figure, 1-blast furnace, 2-bronchial pipe, 3-annular pipeline, 4-stop valve I, 5-gravity dust collector, 6-stop valve II, 7-regulating valve, 8-stop valve III, 9-nitrogen recoil pipe and valve, 10-nitrogen purge pipe and valve, 11-nitrogen purge gas release pipe and valve, 12-phase change material recovery tank, 13-phase change material discharge hole and valve. DETAILED DESCRIPTION

[0032] like Figure 1-4As shown, a device for removing phase change material in a blast furnace comprises a blast furnace 1, a bronchial pipe 2, an annular pipe 3, a stop valve I4, a gravity dust collector 5, a stop valve II6, a regulating valve 7, a stop valve III8, a nitrogen recoil pipe and a valve 9, a nitrogen purge pipe and a valve 10, a nitrogen purge gas release pipe and a valve 11, a phase change material recovery tank 12, and a phase change material discharge hole and a valve 13; a plurality of air intake holes are provided on the body of the blast furnace 1, and are connected to one end of a plurality of bronchial pipes 2, the other end of the bronchial pipe 2 is connected to the annular pipe 3, the annular pipe 3 sends the drawn-out coal gas to the gravity dust collector 5 through a pipeline, and a gas outlet is provided between the annular pipe 3 and the gravity dust collector 5. A stop valve II6 is arranged, and the coal gas finally enters the coal gas recovery system after dust removal by the gravity dust collector 5; a regulating valve 7 is arranged between the gravity dust collector 5 and the coal gas recovery system, and a stop valve III8 is arranged between the regulating valve 7 and the coal gas recovery system; a nitrogen purge gas release pipe and a valve 11 are arranged between the regulating valve 7 and the stop valve III8; a stop valve I4 is arranged on each bronchial pipe 2, and a nitrogen recoil pipe and a valve 9 are added in front of the stop valve I4; a nitrogen purge pipe and a valve 10 are arranged on the annular pipe 3; a phase change material recovery tank 12 is arranged at the lowest point of the pipeline connecting the gravity dust collector 5 and the coal gas recovery system, and a phase change material discharge hole and a valve 13 are arranged.

[0033] Example 1

[0034] A 1080m3 blast furnace in a steel plant had excessive zinc load, poor blast furnace permeability, decreased gas utilization, increased comprehensive coke ratio, decreased utilization coefficient, and furnace wall nodules due to the addition of some converter dust into the charge. Overdeveloped central airflow was used to remove zinc, resulting in a furnace bottom swelling phenomenon and poor furnace conditions. In order to completely solve the zinc enrichment problem, the device and method of the present invention were used to remove zinc.

[0035] On the furnace wall of blast furnace 1 at a temperature of 850℃-900℃, 12 air intake holes with a diameter of 380mm are evenly opened at the same height. One ends of 12 bronchial pipes 2 are respectively connected to the air intake holes, and the other ends of the 12 bronchial pipes 2 are connected through pipes to form an annular pipe 3 with a diameter of 1300mm. A stop valve I4 is provided on each bronchial pipe 2, a nitrogen recoil pipe and a valve 9 are added in front of the stop valve I4, a nitrogen purge pipe and a valve 10 are provided on the annular pipe 3, the annular pipe 3 sends the drawn-out gas to the gravity dust collector 5 through a pipeline, and a stop valve II6 is provided on the pipeline between the annular pipe 3 and the gravity dust collector 5, a regulating valve 7 and a stop valve III8 are provided at a position before the pipeline from the gravity dust collector 5 to the gas recovery system enters the gas recovery system, a nitrogen purge gas release pipe and a valve 11 are provided between the regulating valve 7 and the stop valve III8, an external cooling pipeline system is provided between the gravity dust collector 5 and the regulating valve 7, and heat dissipation fins are provided on the gas transmission pipeline to cool the gas by natural wind. A phase change material recovery tank 12 (for recovering zinc) is provided at the lower end of the external cooling pipeline system, and a phase change material discharge hole and a valve 13 are provided at the bottom thereof, and a stop valve is provided between the phase change material recovery tank 12 and the external cooling pipeline system; the purpose of cooling is, first, to prevent excessive coal temperature from damaging the filter material of the dust collector; second, to reduce the cost of pipeline and valve materials; and third, to recover some zinc. In the scheme of the present invention, the front end pipeline of the gravity dust collector 5 and the annular pipeline 3 are both insulated to reduce the precipitation of zinc on the pipeline and dust, which causes the pipeline to be blocked by a paste, and also reduces the waste of zinc.

[0036] The method of removing phase change material (zinc) in a blast furnace by using the above device is as follows:

[0037] 1. System cleaning and pressurization: The stop valve I4 and stop valve III8, the phase change material discharge hole and valve 13, and the dust collector dust discharge system are all in the closed state. Open the stop valve II6 and the regulating valve 7, open the nitrogen purge pipe and valve 10, open the nitrogen purge gas release pipe and valve 11, and purge the system with nitrogen for 12 minutes to remove the air in the system. Close the nitrogen purge gas release pipe and valve 11, pressurize the system to 250kPa, close the nitrogen purge pipe and valve 10 and the regulating valve 7, and end the system cleaning and pressurization.

[0038] 2. Open the stop valve I4 and stop valve III8 in sequence, and then gradually open the regulating valve 7, and the zinc removal system enters the working state. The air intake volume is controlled within the range of less than 10% of the total gas volume of the blast furnace, and the flow rate of the exhaust gas is controlled within the range of less than 10 m / s.

[0039] 3. Regularly discharge dust ash: The ash discharge system uses a two-stage valve. When discharging ash, first close the upper valve and then open the lower ash discharge valve.

[0040] 4. In order to prevent the high-temperature coal gas from damaging the dust removal system, the connection pipe between the gravity dust collector 5 and the coal gas recovery system adopts an enhanced cooling mode. Zinc will condense and precipitate after the coal gas is cooled. In order to avoid clogging the pipeline, a zinc recovery tank is set at the lowest point of this pipeline. The recovery tank needs to be equipped with a liquid level gauge. When the precipitated zinc liquid level reaches the design upper limit, the phase change material discharge hole and valve 13 are opened to discharge liquid metal zinc. When the discharge reaches the lower limit of the liquid level, the phase change material discharge hole and valve 13 are closed.

[0041] In the first week after the equipment was started up, more than 3 tons of metallic zinc could be recovered every day. In the next two weeks, the amount of metallic zinc recovered was about 2 tons per day, and then gradually decreased. In the fifth week, the amount of zinc recovered per day was about 1 ton. The utilization rate of blast furnace gas was significantly improved, the comprehensive coke ratio was reduced, the permeability of the blast furnace was significantly improved, and the blast furnace utilization coefficient was increased by 0.3 tons / m3·day.

[0042] Since the zinc enrichment problem has been solved, the steel plant has injected the previously discarded blast furnace dust into the blast furnace through the coal injection system. The carbon content of the blast furnace dust is about 30%, the iron content is about 40%, and the zinc content is about 8%. The daily injection volume is about 100 tons, and more than 10 tons of zinc are recovered every day, and about 35 tons of iron are recovered every day. The economic benefits are remarkable. The blast furnace dust has been turned into treasure.

[0043] Due to the injection of blast furnace dust removal ash, in order to keep the blast furnace in operation, the zinc removal equipment has been kept running, the effect is good, and there is no abnormality. Preparations are being made to carry out this technical transformation on other blast furnaces.

[0044] Example 2

[0045] A 1280m3 blast furnace in a steel plant has excessive sodium load due to the addition of red mud from the alumina industry to the charge, resulting in poor permeability and nodules on the furnace wall. To solve this problem, the device and method of the present invention are used, 12 air intake holes with a diameter of 400mm are evenly opened on the ninth layer of the furnace wall, one end of the 12 bronchial tubes 2 is connected to the air intake holes respectively, and the other end of the 12 bronchial tubes 2 is connected to the annular pipeline 3 with a diameter of 1500mm, and the coal gas from the 12 air intake holes is centrally sent to the set annular pipeline 3, each bronchial tube is provided with a stop valve I4, and a nitrogen recoil pipe and valve 9 are provided in front of each stop valve I4, a nitrogen purge pipe and valve 10 are provided on the annular pipeline 3, a gravity dust collector 5 is provided behind the annular pipeline 3, and a stop valve II6 is provided on the pipeline between the annular pipeline 3 and the gravity dust collector 5, and the gravity dust collector 5 and its front-end pipeline valves are all treated with heat preservation. After the coal gas is drawn out and dusted, it is sent to the coal gas recovery system pipeline through a pipeline, and a regulating valve 7 and a stop valve III8 are respectively set at the ends of this section of the pipeline, and a nitrogen purge gas release pipe and a valve 11 are set between the regulating valve 7 and the stop valve III8. In order to accelerate the cooling of the coal gas, a spray water system is added to the outside of this section of the pipeline, and a phase change material recovery tank 12 (recovering alkali metals) is set at the lowest point of this section of the pipeline to prevent the phase change material vapor such as alkali metals from precipitating and condensing when the coal gas is cooled, which will cause the pipeline to be blocked. The bottom of the phase change material recovery tank 12 (recovering alkali metals) is provided with a phase change material discharge hole and a valve 13, and a liquid level meter.

[0046] All gas pipelines and valves are made of high-temperature heat-resistant stainless steel.

[0047] The method of removing phase change substances (alkali metals) in a blast furnace by using the above device has the following operation procedures:

[0048] 1. System cleaning and pressurization: The stop valve I4 and stop valve III8, the phase change material discharge hole and valve 13, and the dust collector dust discharge system are all in the closed state. Open the stop valve II6 and the regulating valve 7, open the nitrogen purge pipe and valve 10, open the nitrogen purge gas release pipe and valve 11, and purge the system with nitrogen for 12 minutes to remove the air in the system. Close the nitrogen purge gas release pipe and valve 11, pressurize the system to 280kPa, close the nitrogen purge pipe and valve 10 and the regulating valve 7, and end the system cleaning and pressurization.

[0049] 2. Open the stop valve I4 and stop valve III8 in sequence, and then gradually open the regulating valve 7, and the alkali metal removal system enters the working state. The air intake volume is controlled to be less than 10% of the total gas volume of the blast furnace, and the flow rate of the intake gas is controlled to be less than 10 m / s.

[0050] 3. Regularly discharge dust ash: When discharging ash from the ash discharge system, close stop valve II6 and stop valve III8 to prevent pressure relief and splashing.

[0051] 4. In order to prevent the high-temperature coal gas from damaging the dust removal system, the connection pipe between the gravity dust collector 5 and the coal gas recovery system adopts a spray-enhanced cooling mode. After the coal gas is cooled, phase-change substances will condense and precipitate. In order to avoid causing pipe blockage, a phase-change substance recovery tank 12 is set at the lowest point of this section of the pipeline. The phase-change substance recovery tank 12 is provided with a liquid level gauge. When the precipitated liquid level reaches the design upper limit, the phase-change substance discharge hole and valve 13 are opened to discharge the liquid phase-change condensed substance. When the discharge reaches the lower limit of the liquid level, the phase-change substance discharge hole and valve 13 are closed.

[0052] After one week of operation, the resistance of blast furnace charge was significantly reduced, the utilization coefficient of blast furnace increased by 0.35 tons / m3·day, the comprehensive coke ratio decreased by 5 kg / ton iron, 2.5 tons of alkali metal compounds were recovered every day in the early stage, and about 2.2 tons of alkali metal compounds were recovered every day in the later stage. When recovering alkali metals, a small amount of metallic zinc was also recovered at the same time. It has been running normally for 8 months.

Claims

1. A device for removing phase change materials in a blast furnace, characterized in that: It comprises a blast furnace (1), a bronchial pipe (2), a ring pipe (3), a stop valve I (4), a gravity dust collector (5), a stop valve II (6), a regulating valve (7), a stop valve III (8), a nitrogen recoil pipe and a valve (9), a nitrogen purge pipe and a valve (10), a nitrogen purge gas release pipe and a valve (11), a phase change material recovery tank (12), and a phase change material discharge hole and a valve (13); A plurality of air intake holes are provided on the body of the blast furnace (1) and are connected to one end of a plurality of bronchial pipes (2). The other end of the bronchial pipe (2) is connected to an annular pipe (3). The annular pipe (3) delivers the drawn coal gas to a gravity dust collector (5) through a pipeline. A stop valve II (6) is provided between the annular pipe (3) and the gravity dust collector (5). The coal gas finally enters a coal gas recovery system after being dusted by the gravity dust collector (5). A regulating valve (7) is provided between the gravity dust collector (5) and the coal gas recovery system. A stop valve III (8) is arranged between the control valve (7) and the stop valve III (8); a nitrogen purge gas release pipe and a valve (11) are arranged between the regulating valve (7) and the stop valve III (8); a stop valve I (4) is arranged on each bronchial pipe (2), and a nitrogen recoil pipe and a valve (9) are added in front of the stop valve I (4); a nitrogen purge pipe and a valve (10) are arranged on the annular pipe (3); a phase change material recovery tank (12) is arranged at the lowest point of the pipeline connecting the gravity dust collector (5) and the gas recovery system, and a phase change material discharge hole and a valve (13) are arranged.

2. The device for removing phase change materials in a blast furnace according to claim 1, characterized in that: The gravity dust collector (5) and the pipeline and valve in front of the gravity dust collector (5) are insulated; the phase change material recovery tank (12) is insulated; the pipeline connecting the gravity dust collector (5) and the gas recovery system is not insulated, and natural cooling or enhanced cooling is required.

3. The device for removing phase change materials in a blast furnace according to claim 1, characterized in that: When selecting the location of the air holes, first, it is necessary to determine the area with higher vapor pressure of the phase change material to be excluded based on the saturated vapor pressure curve of the phase change material to be excluded; second, the location of the air holes should be higher than the fluctuation area of ​​the soft melting zone of the blast furnace to avoid the soft melting material from clogging the air duct; third, when selecting the air entrainment area, the heat resistance of the air duct material should also be considered to ensure the safety of the air entrainment process.

4. The device for removing phase change materials in a blast furnace according to claim 1, characterized in that: Phase change materials refer to substances including zinc, potassium, sodium, alkali, cadmium and antimony that can form a gas-liquid-solid three-state cyclic change in a blast furnace.

5. The device for removing phase change materials in a blast furnace according to claim 1, characterized in that: The design of the air intake volume and the air intake holes is calculated based on the predicted maximum speed of the phase change material in the furnace. The speed at which the phase change material is brought out by the drawn-out coal gas is greater than or equal to the maximum speed at which the phase change material is generated in the furnace. Then, based on the vapor pressure of the phase change material at the determined position of the air intake holes, the concentration of the phase change material in the coal gas under the operating conditions per cubic meter of the drawn-out gas is calculated, and the air intake volume is calculated accordingly. The air intake volume shall not exceed 20% of the total coal gas volume of the blast furnace. After the air intake volume is determined, the flow rate of the drawn-out coal gas is determined, and the flow rate of the drawn-out coal gas is less than 15 m / s. After the air intake volume and the flow rate of the drawn-out coal gas are determined, the total cross-sectional area of ​​the drawn-out coal gas flow is calculated, and the cross-sectional area of ​​each air intake hole is obtained by dividing the calculated total cross-sectional area of ​​the drawn-out coal gas flow by the number of openings, and the diameter of the opening is calculated based on the cross-sectional area.

6. A method for removing phase change substances in a blast furnace, characterized in that: The device for removing phase change materials in a blast furnace according to any one of claims 1 to 5 is implemented, comprising the following steps:

1. System cleaning and pressurization: The stop valve I (4) and the stop valve III (8), the phase change material discharge hole and valve (13) and the dust collector dust discharge system are all in the closed state. The stop valve II (6) and the regulating valve (7) are opened, the nitrogen purge pipe and valve (10) are opened, and the nitrogen purge gas release pipe and valve (11) are opened to purge the system with nitrogen for 10-15 minutes to remove the air in the system; then the nitrogen purge gas release pipe and valve (11) are closed, and the system is pressurized to the blast furnace pressure close to the air inlet hole, and the nitrogen purge pipe and valve (10) and the regulating valve (7) are closed to end the system cleaning and pressurization; 2. Open the stop valve I (4) and stop valve III (8) in sequence, and then gradually open the regulating valve (7) to remove the phase change material system and put it into working state; 3. Regularly discharge dust: The dust collector discharge system uses a two-stage valve. When discharging dust from the dust collector, close the upper valve first, and then open the lower valve.

4. The phase change material recovery tank (12) is provided with a liquid level gauge. When the precipitate liquid level reaches the design upper limit, the phase change material discharge hole and valve (13) are opened to discharge the condensed phase change material. When the discharge reaches the liquid level lower limit, the phase change material discharge hole and valve (13) are closed.

5. If the continuous removal working mode is selected, the system will continue to operate in that mode; if the staged removal mode is selected, when the blast furnace operating resistance returns to normal, the stop valve I (4) and the stop valve III (8) are closed, the phase change material removal system stops working, and the blast furnace enters a normal smelting state. When the blast furnace air permeability deteriorates, the phase change material removal system is started again. When the phase change material removal system stops working, the phase change material discharge hole and valve (13) are opened to release the phase change condensed material.

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