CN112725556B - Method and device for heating pulverized coal by using blast furnace molten iron dedusting circulating hot flue gas - Google Patents

Abstract

The invention relates to a method and a device for heating coal powder by using circulating hot flue gas for blast furnace molten iron dust removal, belonging to the technical field of metallurgical iron-making coal injection processes and equipment. The technical scheme is as follows: the hot metal tank and the hot metal runner dedusting circulation hot flue gas in the blast furnace smelting tapping process are used as main heat sources, the hot flue gas generated by a gas combustion furnace or a burner is used as an auxiliary heat source, the pulverized coal injected into the blast furnace is heated, and the hot flue gas is recycled, so that the hot metal heat in the blast furnace smelting tapping process is utilized to the maximum extent. The invention has the following positive effects: the heat of molten iron is recovered to the maximum extent, the temperature of coal powder entering the blast furnace is increased, the burning rate of the coal powder is increased, the fuel ratio of the blast furnace is reduced, the coal powder replacement ratio is increased, the energy is saved, the consumption is reduced, and the carbon emission is reduced. The surrounding environment of a blast furnace casting house is improved, considerable economic benefit is created by increasing the temperature of the coal powder of the furnace, and the overall cost of the coal powder heating device is reduced.

Description

A method and device for heating pulverized coal by utilizing hot flue gas of blast furnace molten iron dust removal and circulation

technical field

The invention relates to a method and a device for heating pulverized coal by utilizing blast furnace molten iron dedusting and circulating hot flue gas, and belongs to the technical field of metallurgical ironmaking and coal injection technology and equipment.

Background technique

At present, in the field of metallurgical ironmaking, the pulverized coal heating technology for blast furnace injection can effectively improve the combustion efficiency of pulverized coal, reduce the fuel ratio of the blast furnace, and improve the pulverized coal replacement ratio. Created considerable economic benefits. However, the prior art pulverized coal heating technology uses blast furnace hot blast stove waste flue gas or combustion furnace hot flue gas to heat pulverized coal. Thermal process methods, etc., the above-mentioned existing technologies have problems: the utilization efficiency of thermal energy is low, and the hot flue gas (about 120°C below) of the combustion furnace after the pulverized coal is heated is discharged into the atmosphere, and this part of the thermal energy is wasted in vain. Lose.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method and a device for heating pulverized coal by utilizing the hot flue gas of blast furnace molten iron dedusting and circulating, making full use of the heat exchanged between molten iron and dedusting flue gas in the blast furnace smelting and tapping process to heat pulverized coal by pulverized coal injection. The exhausted hot flue gas is returned to the dust removal hood of the molten iron tank and the hot metal ditch is circulated and reciprocated, and the heat of molten iron in the process of smelting and tapping of the blast furnace is utilized to the maximum extent, the energy utilization efficiency is high, and the economic benefit is significant. .

The technical scheme of the present invention is:

A method for heating pulverized coal by utilizing hot flue gas of blast furnace molten iron dust removal and circulation, utilizing hot flue gas of hot metal tank and hot metal ditch dedusting circulation as main heat source, and hot flue gas generated by gas burner or burner as auxiliary The heat source is used to heat the blast furnace blown pulverized coal. The invention makes full use of the heat exchanged between molten iron and dedusting flue gas in the blast furnace smelting and tapping process, heats the blown pulverized coal, and uses it cyclically to make the most of the molten iron heat in the blast furnace smelting and tapping process.

The hot flue gas after the heat exchange between the molten iron and the dedusting flue gas heats the pulverized coal, and the heated pulverized coal is injected into the blast furnace. Heat exchange, and the hot flue gas heats the pulverized coal.

The utility model relates to a device for heating pulverized coal by using hot flue gas from blast furnace molten iron dust removal and circulation. Above the molten iron tank is a dust removal cover for the molten iron tank. The pulverized coal heater is provided with a pulverized coal heating pipe. One end of the pulverized coal heating pipe is connected to the blast furnace coal injection pipeline through the pulverized coal and gas separation device, and the other end is connected to the coal injection gun through the coal powder collecting and powder injector. The pulverized coal is injected into the blast furnace; the flue gas outlet of the pulverized coal heater is connected to the dust collector and the circulating induced draft fan through the second flue gas pipeline; an outlet flue gas distributor is provided between the hot metal tank and the hot metal ditch dust removal cover and the molten iron tank , the circulating induced draft fan is connected to the outlet flue gas distributor through the circulating pipeline.

The outlet flue gas distributor is an annular pipe arranged around the outer edge of the upper mouth of the molten iron tank, the bottom of the annular pipe is densely covered with air outlet holes, and the air outlet holes face the inside of the molten iron tank; the annular pipe is connected with the circulating pipeline; the outlet flue gas distributor is arranged in a horizontal ring shape , the outlet flue gas distributor is connected with the outlet of the circulating induced draft fan through the circulation pipeline, and the exhausted flue gas forms a layer of hot smoke screen between the cold air outside the molten iron tank and the dust removal cover of the molten iron ditch, which reduces the cold air entering the molten iron in the molten iron tank. The ditch dust cover increases the temperature of circulating hot flue gas.

The flue gas pipeline is connected to the combustion furnace or the burner.

The circulating induced draft fan is connected to the chimney through the first valve; the circulating induced draft fan is connected to the circulating pipeline through the second valve.

A pulverized coal and gas separation device is arranged between the blast furnace coal injection pipeline and the pulverized coal heating pipe. The pulverized coal and gas separation device is a static separation bin body, and the interior is divided into left and right parts by ash blocking bars or ash blocking tows. , the right part of the space is divided into an upper chamber and a lower chamber through the ash blocking filter layer, the upper chamber is connected with the left part of the space through the ash blocking strip or the ash blocking tow, and the side wall of the lower chamber penetrates with the blast furnace coal injection The coal inlet pipe connected by the pipeline, the bottom of the lower chamber is provided with a coal powder outlet connected with the coal powder heating pipe; the top of the left part of the space is provided with a gas release device.

The pulverized coal collecting and pulverizing injector comprises two parts, a collecting section and a blowing section, which are communicated with each other through a communication pipeline; It is used to store pulverized coal; a plurality of connecting pipes connected to the pulverized coal heating pipe are evenly distributed around the cylindrical surface of the powder collecting section; There is an air inlet hole, the injection section is connected with the pressure discharge pipeline of the pulverized coal and gas separation device, and at the same time is connected with the injection pressure pipeline. Fluidized pulverized coal. The fluidizing device is a commercially available device well known in the art.

The bottom of the pulverized coal outlet is provided with an upper sealing plate, a plurality of upper plate holes are arranged on the upper sealing plate, and a plurality of pulverized coal heating pipes are respectively connected with the respective upper plate holes.

The ash blocking filter layer is composed of mesh belts and stones. The mesh belt is a grid frame composed of two layers of steel wire or other materials. Stones are installed inside. After touching the surface of the stone, it was blocked and lost its upward power to fall.

The ash blocking strip or the ash blocking tow is composed of filaments and hangs down in the static separation bin. After the surface of the ash-blocking strip or the ash-blocking tow is blocked, it loses power to fall.

The left part of the space is connected with the cyclone dust collector through a pressure discharge pipeline; the upper part of the dust blocking filter layer is matched with a sound wave dust cleaning device.

The pulverized coal outlet is provided with a sealing tank, the bottom of the lower chamber is a funnel structure, and the center of the funnel enters the sealing tank in the pulverized coal outlet through a feeding pipe to seal the pulverized coal outlet to ensure the separation of the pulverized coal and the gas. closedness.

The end of the coal inlet pipe is provided with a buffer tank, and the pulverized coal entering the lower chamber can reduce the impact force through the buffer tank.

The acoustic wave cleaning device, the gas dispersing device, the cyclone dust collector, the combustion furnace or the burner, etc. involved in the present invention are commercially available products.

The number of the pulverized coal heating pipes is multiple, arranged in a tube bundle arrangement, and the pulverized coal heating pipes are seamless steel pipes with fins to increase the heat exchange area.

The dedusting hood for the molten iron ditch is a common dedusting hood, and the dedusting hood for the molten iron ditch is arranged above the molten iron tank and the molten iron ditch; , electrostatic precipitator and filter cartridge precipitator, etc.

The combustion furnace or burner is an ordinary combustion furnace and burner, the combustion gas is a combustible gas, and the flue gas pipeline between the hot flue gas outlet of the combustion furnace or the burner and the dust removal cover of the molten iron tank and the hot metal ditch and the pulverized coal heater Connected.

The circulating induced draft fan is a common induced draft fan, the suction inlet of the circulating induced draft fan is communicated with the flue gas outlet of the pulverized coal heater, and the outlet of the circulating induced draft fan is communicated with the outlet flue gas distributor and the chimney.

The first flue gas pipeline, the second flue gas pipeline and the circulation pipeline are provided with thermal insulation layers to reduce heat loss.

The chimney is a conventional design exhaust chimney.

The outer shell of the pulverized coal heater is a steel intermediate outer shell with a thermal insulation layer on the outside. A plurality of pulverized coal heating pipes are arranged in the outer shell, and hot flue gas passes through the outer shell to exchange heat with the pulverized coal heating pipes. for heating pulverized coal.

The intermediate outer shell is in the shape of a long cylinder, arranged horizontally, one end is connected with the flue gas pipeline, and the other end is connected with the second flue gas pipeline; the side wall of the top of the intermediate outer shell is provided with an upper connecting cylinder, which is connected with the pulverized coal outlet. The bottom side wall of the intermediate outer casing is provided with a lower connecting cylinder, which is connected with the pulverized coal collector and powder injector; the tube bundle formed by a plurality of pulverized coal heating pipes enters the intermediate casing through the upper connecting cylinder for heating, and then passes through the lower connecting cylinder and the coal powder. The powder collecting and powder blowing device is connected; the bottom of the lower connecting cylinder is provided with a lower sealing plate, the lower sealing plate is provided with a plurality of lower plate holes, and the plurality of pulverized coal heating pipes are respectively connected with the respective lower plate holes. The pulverized coal heating pipe is connected with the connecting pipeline of the pulverized coal collecting and pulverizing injector through the hole of the lower plate.

The positive effect of the invention is that the heat of the hot flue gas after the heat exchange between the molten iron and the dust-removing flue gas in the blast furnace smelting and tapping process is fully utilized to heat the pulverized coal, and the discharged hot flue gas is returned to the dust-removing cover of the molten iron tank. , reciprocating, reusing, maximizing the recovery of the heat of molten iron, increasing the temperature of pulverized coal entering the blast furnace, increasing the burning rate of pulverized coal, reducing the fuel ratio of the blast furnace, improving the pulverized coal replacement ratio, saving energy and reducing consumption, Reduce carbon emissions. It enhances the dust removal effect of the casting yard, improves the surrounding environment of the blast furnace casting yard, and is especially suitable for the reconstruction of blast furnaces with insufficient dust removal capacity in the blast furnace casting yard. It not only improves the surrounding environment of the casting yard, but also creates a considerable economic benefits. Compared with other existing pulverized coal heating technologies, it can not only create more benefits, but also reduce the overall cost of the pulverized coal heating device.

Description of drawings

1 is an overall schematic diagram of an embodiment of the present invention;

2 is a schematic structural diagram of a pulverized coal heater according to an embodiment of the present invention;

3 is a schematic structural diagram of a pulverized coal and gas separation device according to an embodiment of the present invention;

Fig. 4 is the A-A sectional schematic diagram of the pulverized coal and gas separation device according to the embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a pulverized coal collector and powder injector according to an embodiment of the present invention;

6 is a schematic structural diagram of a molten iron tank and a dust hood according to an embodiment of the present invention;

FIG. 7 is a schematic view of the B-direction structure of the outlet flue gas distributor according to the embodiment of the present invention;

In the figure: 1, dust collector 2, burner or burner 3, circulating induced draft fan 4, outlet flue gas distributor 5, flue gas pipeline 1 6, chimney 7, pulverized coal heater 8, pulverized coal and gas separation device 9, pressure discharge pipeline 10, pulverized coal collection and powder injector 11, pulverized coal heating pipe 12, coal injection gun 13, blast furnace 14, intermediate outer casing 15, injection pressure pipeline 16, Coal inlet pipe 17, static separation bin body 18, gas release device 19, sonic ash cleaning device 20, cyclone dust collector 21, ash blocking filter layer 22, ash blocking strip or ash blocking wire bundle 23, coal powder outlet 24, grid Belt 25, stone 26, powder collecting section 27, injection section 28, coal outlet 29, air inlet 30, fluidization device 31, molten iron tank 32, air outlet 33, flue gas pipeline 2 34, valve 1 35, The second valve 36 , the buffer tank 37 , the sealing tank 38 , the circulation pipeline 39 , the upper connecting cylinder 40 , the lower connecting cylinder 41 , the connecting pipeline 42 , and the connecting pipeline 43 .

Detailed ways

Below in conjunction with accompanying drawing and embodiment, the present invention will be further described:

A method for heating pulverized coal by utilizing hot flue gas of blast furnace molten iron dust removal and circulation, utilizing hot flue gas of hot metal tank and hot metal ditch dedusting circulation as main heat source, and hot flue gas generated by gas burner or burner as auxiliary The heat source is used to heat the blast furnace blown pulverized coal. The invention makes full use of the heat exchanged between molten iron and dedusting flue gas in the blast furnace smelting and tapping process, heats the blown pulverized coal, and uses it cyclically to make the most of the molten iron heat in the blast furnace smelting and tapping process.

The hot flue gas after the heat exchange between the molten iron and the dedusting flue gas heats the pulverized coal, and the heated pulverized coal is injected into the blast furnace. Heat exchange, and the hot flue gas heats the pulverized coal.

A device for heating pulverized coal by using hot flue gas from blast furnace molten iron dust removal and circulation. Above the molten iron tank 32 is a dust removal cover 1 for the molten iron tank. The pulverized coal heater 8 is provided with a pulverized coal heating pipe 12. One end of the pulverized coal heating pipe 12 is connected to the blast furnace coal injection pipeline through the pulverized coal and gas separation device 9, and the other end is injected through the pulverized coal collection and pulverized coal. The device 11 is connected to the coal injection gun 13, and the coal injection gun 13 injects pulverized coal into the blast furnace 14; the flue gas outlet of the pulverized coal heater 8 is connected to the dust collector 2 and the circulating induced draft fan 4 through the second flue gas pipeline 34; the molten iron An outlet flue gas distributor 5 is arranged between the tank iron ditch dust removal cover 1 and the molten iron tank 32 , and the circulating induced draft fan 4 is connected to the outlet flue gas distributor 5 through a circulation pipeline 39 .

The outlet flue gas distributor 5 is an annular pipe arranged around the outer edge of the upper mouth of the molten iron tank, the bottom of the annular pipe is densely covered with air outlet holes 33, and the air outlet holes 33 face the inside of the molten iron tank; the annular pipe is connected with the circulation pipeline 39; the outlet flue gas is distributed The flue gas distributor 5 is arranged in a horizontal ring, and the outlet flue gas distributor 5 is communicated with the outlet of the circulating induced draft fan 4 through the circulation pipeline 39. The smoke screen reduces the cold air entering the hot metal ditch dust cover 1 of the molten iron tank, and increases the temperature of the circulating hot flue gas.

The flue gas pipeline one 6 is connected to the combustion furnace or the burner 3 .

The circulating induced draft fan 4 is connected to the chimney 7 through the valve one 35 ; the circulating induced draft fan 4 is connected to the circulating pipeline 39 through the valve two 36 .

A pulverized coal and gas separation device 9 is arranged between the blast furnace coal injection pipeline and the pulverized coal heating pipe 12. The pulverized coal and gas separation device 9 is a static separation bin 18, and the interior is separated by ash blocking bars or ash blocking tows 23. It is a left and right part of the space. The right part of the space is divided into an upper chamber and a lower chamber by the ash blocking filter layer 22. The wall penetrates into the coal inlet pipe 17 connected with the blast furnace coal injection pipeline, and the bottom of the lower chamber is provided with a coal powder outlet 24 connected with the coal powder heating pipe 12;

The pulverized coal collecting and powder injector 11 includes two parts, a powder collecting section 27 and a spraying section 28, which are connected to each other through a communication pipeline 43; the powder collecting section is cylindrical, and a plurality of connecting pipelines 42 are evenly arranged around the cylindrical surface, The inner side is a cavity for storing pulverized coal; a plurality of connecting pipes 42 communicating with the pulverized coal heating pipe 12 are evenly distributed around the cylindrical surface of the powder collecting section; the injection section 28 is provided with one or more coal outlets 29 and The coal injection gun 13 is communicated, and the upper part of the injection section 28 is provided with an air inlet 30. The injection section 28 is communicated with the exhaust pressure pipeline 10 of the pulverized coal and gas separation device 9, and is also communicated with the injection pressure pipeline 16. The lower part of the blowing section 28 is provided with a fluidizing device 31 for fluidizing the pulverized coal when the pulverized coal is blown. The fluidizing device is a commercially available device well known in the art.

The bottom of the pulverized coal outlet 24 is provided with an upper sealing plate, a plurality of upper plate holes are arranged on the upper sealing plate, and the plurality of pulverized coal heating pipes 12 are respectively connected with the respective upper plate holes.

The ash blocking filter layer 22 is composed of a mesh belt 25 and a stone 26. The mesh belt 25 is a grid frame composed of two layers of steel wire or other materials. The stone 26 is installed inside, and the function is to allow dust and gas to pass through. When the stone 26 is in the gap, after the dust contacts the surface of the stone 26, it is blocked and loses its upward power to fall.

The ash-blocking strips or ash-blocking tows 23 are made of filaments and hang down in the static separation bin body 18. The function is that the gas with dust can pass through the gaps of the ash-blocking strips or the ash-blocking tows. After the pulverized coal contacts the surface of the ash blocking strip or the ash blocking tow, it is blocked and loses power to fall.

The left part of the space is connected with the cyclone dust collector 21 through the pressure discharge pipeline 10 ; the upper part of the dust blocking filter layer 22 is matched with the acoustic wave dust cleaning device 20 .

The pulverized coal outlet 24 is provided with a sealing tank 38, the bottom of the lower chamber is a funnel structure, and the center of the funnel enters the sealing tank 38 in the pulverized coal outlet 24 through a feeding pipe to seal the pulverized coal outlet 24 to ensure the pulverized coal and the airtightness of the gas separation device 9.

A buffer tank 37 is provided at the end of the coal inlet pipe 17 , and the pulverized coal entering the lower chamber passes through the buffer tank 37 to reduce the impact force.

The acoustic wave cleaning device 20, the gas dispersing device 19, the cyclone 21, the combustion furnace or the burner 3, etc. involved in the present invention are commercially available products.

The number of the pulverized coal heating pipes 12 is multiple and arranged in a tube bundle arrangement. The pulverized coal heating pipes 12 are seamless steel pipes and are provided with fins to increase the heat exchange area.

The hot metal ditch dust removal hood 1 is a common dust removal hood, and the molten iron ditch dust removal hood 1 is arranged above the molten iron tank 32 and the molten iron ditch; the dust collector 2 is a conventional dust collector, such as a cyclone dust collector, a multi-tube dust collector , bag filter, electrostatic precipitator and filter cartridge filter, etc.

The burner or burner 3 is an ordinary burner and burner, and the combustion gas is a combustible gas. The gas pipeline one 6 is connected.

The circulating induced draft fan 4 is a common induced draft fan, the suction inlet of the circulating induced draft fan 4 is communicated with the flue gas outlet of the pulverized coal heater 8 , and the outlet of the circulating induced draft fan 4 is communicated with the outlet flue gas distributor 5 and the chimney 7 .

The first flue gas pipeline 6, the second flue gas pipeline 34 and the circulating pipeline 39 are provided with insulation layers to reduce heat loss.

The chimney 7 is a conventional design exhaust chimney.

The outer shell of the pulverized coal heater 8 is a steel intermediate outer shell 15 with a thermal insulation layer on the outside. A plurality of pulverized coal heating pipes 12 are arranged in the outer shell. Heat exchange for heating pulverized coal.

The intermediate outer casing 15 is in the shape of a long cylinder, arranged horizontally, one end is communicated with the flue gas pipeline 1 6, and the other end is communicated with the second flue gas pipeline 34; the side wall of the top of the intermediate outer casing 15 is provided with an upper connecting cylinder 40. , is connected to the pulverized coal outlet 24, and the bottom side wall of the intermediate outer casing 15 is provided with a lower connecting cylinder 41, which is connected to the pulverized coal collecting and pulverizing injector 11; The outer casing 15 is heated inside, and then connected to the pulverized coal powder injector 11 through the lower connecting cylinder 41; the bottom of the lower connecting cylinder 41 is provided with a lower sealing plate, and the lower sealing plate is provided with a plurality of lower plate holes, many The pulverized coal heating pipes 12 are respectively connected to the respective lower plate holes, and the plurality of pulverized coal heating pipes 12 pass through the lower plate holes and are connected to the connecting pipeline 42 of the pulverized coal collecting and blowing device 11 .

The specific technological process of the present embodiment:

The inlet of the circulating induced draft fan 4 is communicated with the outlet of the dust hood 1 of the molten iron tank and the hot metal ditch through the dust collector 2, the flue gas pipeline two 34, the pulverized coal heater 8 and the flue gas pipeline one 6 in turn, and the outlet of the circulating induced draft fan 4 passes through the circulating pipe. The road 39 is connected with the outlet flue gas distributor 5;

When the system is working, the gas from the outlet of the circulating induced draft fan 4 is sprayed to the molten iron tank 32 from top to bottom through the air outlet 33 of the outlet flue gas distributor 5, and then rises under the action of the suction of the circulating induced draft fan 4, and is mixed with the molten iron. The flowing molten iron in the molten iron ditch exchanges heat, and the hot flue gas is sucked into the flue gas pipeline 1 6. At the same time, the high-temperature flue gas from the combustion furnace or burner 3 is also sucked into the flue gas pipeline 1 6, and the two flue gases are mixed to the setting. Set the temperature, enter the pulverized coal heater 8, and the hot flue gas exchanges heat with the pulverized coal in the pulverized coal heating pipe 12 in the pulverized coal heater 8. The heating temperature of the pulverized coal can pass the high temperature hot flue gas of the combustion furnace or the burner 3. The flue gas after heat exchange enters the dust collector 2 through the second flue gas pipeline 34 for dust removal, and then enters the circulating induced draft fan 4 and returns to the outlet flue gas distributor 5 through the circulating pipeline 39 . The hot flue gas forms a layer of hot smoke between the dust cover 1 of the molten iron tank and the outside air of the molten iron tank 32, which reduces the cold air entering the dust cover 1 of the molten iron tank and the flue gas in the dust cover 1 of the molten iron tank. It exchanges heat with molten iron and high-temperature radiant heat energy, further heats the flue gas temperature, and the hot flue gas is sucked into the flue gas pipeline 1 6 again, and the cycle is repeated.

The pulverized coal from the blast furnace coal injection pipeline enters the pulverized coal and gas separation device 9 to separate the pulverized coal and gas; the separated gas is dedusted by the cyclone dust collector 21 and then enters the pressure discharge pipeline 10, and then enters the pulverized coal collection and injection Blower 11; the separated pulverized coal enters the pulverized coal heating pipe 12, and conducts heat exchange with the hot flue gas outside the pulverized coal heating pipe 12 in the pulverized coal heater 8, and the heated pulverized coal enters the pulverized coal collection and powder injection The pulverized coal collection section 27 of the pulverized coal collector 11 enters the injection section 28 of the pulverized coal collection and pulverized injector 11 through the communication pipeline 43, and is fluidized in the injection section 28. The injection gas is injected into the blast furnace 14 through the coal injection gun 13 under the combined action of the pulverized coal from the pressure discharge pipeline 10 and the gas pressure generated by the gas separation device 9 .

The combustion furnace or burner 3 in the present invention can be used all the time to adjust the heating temperature of the pulverized coal, or it can be stopped after the normal production of the blast furnace and the heating temperature of the pulverized coal is stable.

The present invention can adjust and control most or all of the hot flue gas to return to the outlet flue gas distributor 5 through the circulation pipeline 39 through the opening and closing of the first valve 35 and the second valve 36, and a small part is discharged from the chimney 7.

Claims (7)

1. a device utilizing blast furnace molten iron dedusting circulating hot flue gas to heat pulverized coal, is characterized in that: the top of the molten iron tank (32) is provided with a dedusting cover (1) for a molten iron tank and a molten iron ditch, and a dedusting cover (1) for a molten iron trench in a molten iron tank. The collected flue gas enters the pulverized coal heater (8) through the flue gas pipeline 1 (6). The pulverized coal heater (8) is provided with a pulverized coal heating pipe (12), and one end of the pulverized coal heating pipe (12) passes through The pulverized coal and gas separation device (9) is connected to the blast furnace coal injection pipeline, and the other end is connected to the coal injection gun (13) through the coal powder collecting powder injector (11), and the coal injection gun (13) is injected into the blast furnace (14) pulverized coal; the flue gas outlet of the pulverized coal heater (8) is connected to the dust collector (2) and the circulating induced draft fan (4) through the second flue gas pipeline (34); An outlet flue gas distributor (5) is arranged between the tanks (32), and the circulating induced draft fan (4) is connected to the outlet flue gas distributor (5) through a circulation pipeline (39); A pulverized coal and gas separation device (9) is arranged between the blast furnace coal injection pipeline and the pulverized coal heating pipe (12). The bar or the ash-blocking tow (23) is divided into left and right parts, the right part of the space is divided into an upper chamber and a lower chamber by the ash-blocking filter layer (22), and the upper chamber is passed through the ash-blocking bar or the ash-blocking tow. (23) Connected with the left part of the space, the side wall of the lower chamber penetrates into the coal inlet pipe (17) connected with the blast furnace coal injection pipeline, and the bottom of the lower chamber is provided with pulverized coal connected to the pulverized coal heating pipe (12) outlet (24); a gas release device (19) is provided at the top of the left part of the space. 2. A device for heating pulverized coal by using blast furnace molten iron dedusting circulating hot flue gas according to claim 1, characterized in that: the pulverized coal collecting and pulverizing injector (11) comprises a communication pipeline (43) that The powder collecting section (27) and the blowing section (28) are connected in two parts; the powder collecting section is cylindrical, a plurality of connecting pipes (42) are evenly arranged around the cylindrical surface, and the inner side is a cavity for storing pulverized coal; A plurality of connecting pipelines (42) communicating with the pulverized coal heating pipe (12) are evenly distributed around the cylindrical surface of the powder collecting section; the injection section (28) is provided with one or more coal outlets (29) and a coal injection gun (13) Connected, the upper part of the injection section (28) is provided with an air inlet (30), the injection section (28) is communicated with the pressure discharge pipeline (10) of the pulverized coal and gas separation device (9), and at the same time with the injection The blowing and pressurizing pipeline (16) is connected, and the lower part of the blowing section (28) is provided with a fluidizing device (31) for fluidizing the pulverized coal when the pulverized coal is sprayed. 3. A device for heating pulverized coal by using blast furnace molten iron dedusting circulating hot flue gas according to claim 1, characterized in that: the bottom of the pulverized coal outlet (24) is provided with an upper sealing plate, and the upper sealing plate is provided with an upper sealing plate. A plurality of upper plate holes, and a plurality of pulverized coal heating pipes (12) are respectively connected with the respective upper plate holes. 4. A device for heating pulverized coal using blast furnace molten iron dedusting circulating hot flue gas according to claim 1, characterized in that: the outlet flue gas distributor (5) is an annular pipe arranged around the outer edge of the upper mouth of the molten iron tank , the bottom of the annular pipe is densely covered with air outlet holes (33), and the air outlet holes (33) face into the molten iron tank; the annular pipe is connected with the circulation pipeline (39); the outlet flue gas distributor (5) is arranged in a horizontal ring, and the outlet flue gas distributor (5) The circulating pipe (39) is connected to the outlet of the circulating induced draft fan (4), and the exhausted flue gas forms a layer of hot smoke between the cold air outside the molten iron tank (32) and the dust cover (1) of the molten iron tank. , reducing the cold air entering the hot metal ditch dust cover (1) of the molten iron tank, and increasing the temperature of the circulating hot flue gas. 5. A device for heating pulverized coal by using blast furnace molten iron dedusting circulating hot flue gas according to claim 1, characterized in that: said flue gas pipeline one (6) is connected to a combustion furnace or a burner (3). 6. A device for heating pulverized coal using blast furnace molten iron dedusting circulating hot flue gas according to claim 1, characterized in that: the outer shell of the pulverized coal heater (8) is a steel intermediate outer shell (15) , the outside is provided with a thermal insulation layer, a plurality of pulverized coal heating pipes (12) are arranged in the shell, and hot flue gas passes through the shell to exchange heat with the pulverized coal heating pipes (12) for heating pulverized coal. 7. A device for heating pulverized coal using blast furnace molten iron dedusting and circulating hot flue gas according to claim 6, characterized in that: the intermediate outer casing (15) is in the shape of a long cylinder, arranged horizontally, and one end is connected to the flue gas The first pipe (6) is communicated with the other end of the flue gas pipe (34); the side wall of the top of the intermediate outer shell (15) is provided with an upper connecting cylinder (40), which is connected with the pulverized coal outlet (24), and the middle The bottom side wall of the outer casing (15) is provided with a lower connecting cylinder (41), which is connected to the pulverized coal collecting and pulverizing injector (11); the tube bundle formed by the plurality of pulverized coal heating pipes (12) enters through the upper connecting cylinder (40). The middle outer casing (15) is heated inside, and then connected to the pulverized coal powder injector (11) through the lower connecting cylinder (41); the bottom of the lower connecting cylinder (41) is provided with a lower sealing plate, and the lower sealing plate is A plurality of lower plate holes are provided, and a plurality of pulverized coal heating pipes (12) are respectively connected with the respective lower plate holes.

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