Process and system for recycling pneumatic conveying gas of hot-state high-temperature direct reduced iron

Abstract

The invention belongs to the technical field of ferrous metallurgy, and relates to a hot-state high-temperature direct reduction iron pneumatic conveying gas recycling process and system.The process comprises the following steps that a hot-state high-temperature direct reduction iron pneumatic conveying pipeline is connected with a material tank, and hot-state high-temperature direct reduction iron is accumulated in the material tank; dust-containing high-temperature crude conveying gas is discharged from the charging bucket, waste heat is recovered through the indirect waste heat recovery device, clean conveying gas is formed after dust removal and purification of the dry dust removal device, and then the clean conveying gas is reused to the thermal-state high-temperature direct reduction iron pneumatic conveying pipeline. The indirect waste heat recovery device is adopted for recovering sensible heat and byproduct steam of the dust-containing high-temperature crude conveying gas, waste heat recovery is achieved, iron-containing dust in the dust-containing high-temperature crude conveying gas recovered by the dry dust removal device is directly used by a steelmaking user or transported outwards, utilization of raw materials is improved, and the raw materials are saved; in addition, no sewage and sludge treatment system is realized through an indirect waste heat recovery process and a dry dust removal process.

Description

Technical Field

[0001] The invention belongs to the technical field of iron and steel metallurgy, and relates to a process and system for recycling gas by pneumatic conveying of hot high-temperature direct reduced iron. Background Art

[0002] High-temperature hot direct reduced iron (sponge iron) is transported to the steelmaking workshop through pipelines by gas (usually nitrogen) in a pneumatic conveying manner. During the pneumatic conveying process, the conveying gas and the high-temperature hot direct reduced iron undergo heat exchange in the conveying pipeline, which increases the temperature of the conveying gas at the end of the conveying and contains direct reduced iron dust. Direct reduced iron and water or air are prone to react and release heat, so they are prone to self-heating to provide a heat source. The reaction of direct reduced iron is very slow at room temperature, but when the temperature reaches above 200°C, the reaction speed will be significantly accelerated, generating a large amount of heat and hydrogen. If the ambient temperature continues to rise or there is a large amount of moisture, the generated hydrogen will continue to react, generating a large amount of heat, causing the direct reduced iron to "spontaneously combust". At the same time, the lower explosion limit of hydrogen is about 4%, and once a large amount of hot hydrogen leaks into the atmosphere, it is easy to explode.

[0003] In the process of using gas to transport hot sponge iron, considering the danger of hot sponge iron, a large amount of water is generally used to cool the transport gas carrying sponge iron to a safe temperature, and at the same time, the sponge iron dust is removed to achieve the recycling of the transport gas. This process still has the following technical problems:

[0004] (1) A large amount of waste heat from the high-temperature transport gas is not recovered.

[0005] (2) The water in the wet scrubbing process and the saturated water remaining in the conveying gas after wet dust removal will inevitably produce hydrogen when in direct contact with sponge iron. In addition, an explosive atmosphere may easily occur when ventilation is poor or hydrogen accumulates, posing a safety hazard.

[0006] (3) The conveying gas is cooled and dusted by water washing, which forms a large amount of turbid circulating water, which requires supporting turbid circulating water treatment and sludge treatment, which occupies a large area and has poor environmental protection effect.

[0007] (4) After the conveying gas is washed with water, the temperature of the gas returned to the beginning of the pneumatic conveying is relatively low. During the pneumatic conveying process, more heat energy carried by the high-temperature direct reduced iron itself is consumed, resulting in a decrease in the temperature at the end of the conveying, which in turn leads to an increase in energy consumption in the subsequent steelmaking process, resulting in poor economic efficiency.

[0008] (5) The sludge (dust) in the turbid circulating water can only be recovered as solid waste and cannot be directly used for steelmaking.

[0009] In summary, the technical problems existing in the gas purification and cooling process of the above-mentioned hot sponge iron pneumatic conveying are rooted in the lack of a reliable gas recycling process and system. Summary of the invention

[0010] In view of this, the purpose of the present invention is to provide a hot high-temperature direct reduced iron pneumatic conveying gas recycling process and its system to solve the hidden dangers of spontaneous combustion and explosion hazards that may occur in the existing conveying gas treatment process, while completely recovering the direct reduced iron dust in the pneumatic conveying gas and reducing the energy consumption of smelting in the steelmaking process.

[0011] In order to achieve the above object, the present invention provides the following technical solutions:

[0012] A hot high-temperature direct reduced iron pneumatic conveying gas recycling process comprises the following steps:

[0013] The pneumatic conveying pipeline from hot high-temperature direct reduced iron is connected to the material tank, in which the hot high-temperature direct reduced iron is accumulated, and the dusty high-temperature waste conveying gas is discharged from the material tank, and is formed into a clean conveying gas after the waste heat is recovered by an indirect waste heat recovery device and the dust is removed and purified by a dry dust removal device, and then reused to the pneumatic conveying pipeline for hot high-temperature direct reduced iron.

[0014] Furthermore, the dusty high-temperature waste gas at least meets one of the following conditions:

[0015] (1) Temperature is 300℃~650℃;

[0016] (2) The pressure is 0.1MPa to 1.0MPa;

[0017] (3) Dust content is 1g / Nm 3 ~20g / Nm 3 .

[0018] Furthermore, the indirect waste heat recovery device is a waste heat boiler, which uses the waste heat boiler to recover the sensible heat of the dust-containing high-temperature waste transport gas and produce steam as a by-product, and cools the dust-containing high-temperature waste transport gas to 100°C to 200°C to form dust-containing medium-temperature waste transport gas.

[0019] Furthermore, the indirect waste heat recovery device is an indirect heat exchanger, which recovers the waste heat of the dust-containing high-temperature waste transport gas through heat exchange with other refrigerants to form dust-containing medium-temperature waste transport gas.

[0020] Furthermore, the dry dust removal device adopts a dry filter bag dust collector or a dry electric dust collector;

[0021] And / or, the dust content of the clean conveying gas after dust removal and purification by the dry dust removal device is less than or equal to 10 mg / Nm 3 .

[0022] Furthermore, the dust and ash accumulated by the dust-containing high-temperature waste gas at the bottom of the waste heat recovery device and the bottom of the dry dust removal device are transported to the material tank through a closed pipeline or a gravity chute for subsequent steelmaking.

[0023] Furthermore, the dust and ash accumulated at the bottom of the waste heat recovery device and the bottom of the dry dust removal device by the dust-containing high-temperature waste gas are transported to the transfer tank through a closed pipeline and transported out by a tank truck.

[0024] Furthermore, the net conveying gas is pressurized by a pressurizing device and then recycled to the hot high-temperature direct reduced iron pneumatic conveying pipeline.

[0025] Furthermore, the pressurizing device adopts a high-temperature pressurizing machine, and the inlet temperature is 60°C to 200°C.

[0026] Furthermore, the pressure of the net conveying gas after being pressurized by the pressurizing device is 0.2MPa to 1.4MPa.

[0027] Furthermore, the net conveying gas is nitrogen or a mixed gas mainly composed of nitrogen.

[0028] Furthermore, the net conveying gas is recycled to the beginning of the hot high-temperature direct reduced iron pneumatic conveying pipeline through the gas conveying pipeline.

[0029] Furthermore, a venting device and a gas supply device are provided on the gas delivery pipeline to adjust the gas volume in the gas delivery pipeline;

[0030] And / or, the air-supplementing medium in the air-supplementing device is nitrogen.

[0031] Furthermore, the material tank is located at the end of the hot high-temperature direct reduced iron pneumatic conveying pipeline.

[0032] On the other hand, the present invention also provides a gas recycling system for pneumatic conveying of hot high-temperature direct reduced iron, comprising a material tank, a waste heat recovery device and a dry dust removal device. The material tank is connected to the end of the pneumatic conveying pipeline of the hot high-temperature direct reduced iron, and is used to receive the hot high-temperature direct reduced iron and dust-containing high-temperature iron conveying gas. The material tank is connected to the waste heat recovery device and the dry dust removal device in sequence through the gas conveying pipeline, and the dry dust removal device is connected to the starting end of the pneumatic conveying pipeline of the hot high-temperature direct reduced iron through the gas conveying pipeline.

[0033] Furthermore, it also includes a pressurizing device connected after the dry dust removal device.

[0034] Furthermore, the material tank comprises a first material tank and a second material tank, the end of the hot high-temperature direct reduced iron pneumatic conveying pipeline is connected to the top of the first material tank, and the top of the first material tank is connected to the waste heat recovery device through the gas conveying pipeline;

[0035] The second material tank is connected to the bottom of the first material tank to receive the hot high-temperature direct reduced iron in the first material tank.

[0036] Furthermore, iron-containing dust pipelines are provided at the bottom of the waste heat recovery device and the dry dust removal device, and the iron-containing dust pipelines are connected to a second material tank to recover the dust at the bottom of the waste heat recovery device and the dry dust removal device.

[0037] Furthermore, iron-containing dust ash pipelines are provided at the bottom of the waste heat recovery device and the dry dust removal device, and the iron-containing dust ash pipelines are connected to a transfer tank to recover the dust ash at the bottom of the waste heat recovery device and the dry dust removal device.

[0038] Furthermore, it also includes a venting device and an air supply device, wherein the venting device is arranged on the top of the gas conveying pipeline at or behind the dry dust removal device, and the air supply device is arranged on the gas conveying pipeline and is located after the venting device.

[0039] Furthermore, the dry dust removal device has a back-blowing and cleaning device to back-blow and clean the dry dust removal device in the intervals between purification and dust removal.

[0040] The beneficial effects of the present invention are:

[0041] 1. The present invention provides a hot high-temperature direct reduced iron pneumatic conveying gas recycling process and system, which adopts an indirect waste heat recovery device to recover the sensible heat of the dust-containing high-temperature waste conveying gas and produce steam as a by-product, thereby realizing the recovery of waste heat. The iron-containing dust in the dust-containing high-temperature waste conveying gas recovered by a dry dust removal device is directly used by steelmaking users or transported out, thereby improving the utilization of raw materials and saving raw materials. In addition, the indirect waste heat recovery process and the dry dust removal process realize a sewage and sludge treatment system, with significant environmental benefits. The system occupies a small area, is simple to operate, and saves investment.

[0042] 2. The present invention uses a compressor to pressurize the net conveying gas and then sends it back to the starting end of the hot high-temperature direct reduced iron pneumatic conveying pipeline, thereby increasing the temperature of the pneumatic conveying gas and reducing the heat loss of the hot direct reduced iron during the pneumatic conveying process, thereby increasing the temperature of the hot sponge iron entering the steelmaking user and reducing the energy consumption of the steelmaking process.

[0043] 3. The present invention isolates water from direct contact with hot sponge iron, thereby avoiding the generation of large amounts of heat and hydrogen, and preventing the potential hazards of spontaneous combustion and explosion.

[0044] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0046] Figure 1 It is a schematic flow diagram of a gas recycling process for pneumatic conveying of hot high-temperature direct reduced iron in the present invention;

[0047] Figure 2 A schematic flow diagram of a gas recycling process for pneumatic conveying of hot high-temperature direct reduced iron in Example 1;

[0048] Figure 3 This is a schematic flow chart of a hot high-temperature direct reduced iron pneumatic conveying gas recycling process in Example 2.

[0049] Reference numerals: first material tank 1 , second material tank 2 , waste heat recovery device 3 , dry dust removal device 4 , pressurizing device 5 , transfer tank 6 . DETAILED DESCRIPTION

[0050] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0051] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0052] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0053] See also Figure 1 , which is a hot high-temperature direct reduced iron pneumatic conveying gas recycling process, comprising the following steps:

[0054] The hot high-temperature direct reduced iron from the hot high-temperature direct reduced iron pneumatic conveying pipeline is stored in the lower part of the first material tank 1, and the dusty high-temperature waste conveying gas after pneumatic conveying is stored in the upper part of the first material tank 1;

[0055] The dusty high-temperature waste gas is discharged from the top of the first material tank 1, enters the waste heat recovery device 3 to recover waste heat, and is cooled to become dusty medium-temperature waste gas;

[0056] The dust-laden medium-temperature conveying gas enters the dry dust removal device 4 for dust removal and purification, and the separated dust is stored at the bottom of the dry dust removal device 4, and the clean conveying gas after dust removal and purification is discharged from the upper part of the dry dust removal device 4;

[0057] After being pressurized by the pressurizing device 5, the net conveying gas is recycled to the beginning of the hot high-temperature direct reduced iron pneumatic conveying pipeline for use in the hot high-temperature direct reduced iron pneumatic conveying;

[0058] The dust accumulated at the bottom of the waste heat recovery device 3 and the dust accumulated at the bottom of the dry dust removal device 4 are transported to the second material tank 2 for reuse.

[0059] Specifically, the present embodiment provides a gas recycling system for pneumatic conveying of hot high-temperature direct reduced iron for the above-mentioned process, the system comprising a first material tank 1, a second material tank 2, a waste heat recovery device 3, a dry dust removal device 4, a pressurizing device 5 and a transfer tank 6, the first material tank 1 is connected to the end of the pneumatic conveying pipeline of the hot high-temperature direct reduced iron, a valve is provided at the bottom of the first material tank 1 (the valve can be specifically set to one of a dome valve, a material isolation valve, a rod valve or a wear-resistant manual ball valve), and the valve is connected to the second material tank 2 through a closed pipe or a gravity chute, the top of the first material tank 1 is connected in sequence with the waste heat recovery device 3, the dry dust removal device 4 and the pressurizing device 5 through a gas recycling treatment pipeline, and the gas recycling treatment pipeline is connected to the starting end of the pneumatic conveying pipeline of the hot high-temperature direct reduced iron.

[0060] At the bottom of the waste heat recovery device 3 and the dry dust removal device 4, a silo pump is provided to collect dust ash in the dust-containing high-temperature waste gas and the dust-containing medium-temperature waste gas, respectively. The silo pump is connected to the second material tank 2 or the transfer tank 6 through the iron-containing dust ash pipeline. Specifically, the iron-containing dust ash pipeline is connected to the second material tank and the transfer tank respectively after being collected, and a first valve and a second valve are provided on the pipeline connecting the second material tank and the transfer tank, respectively, to realize the selection of the second material tank and the transfer tank.

[0061] Preferably, a nitrogen source is connected to the iron-containing dust pipeline to pneumatically transport the iron-containing dust back into the second material tank 2 or transfer tank 6 for subsequent electric furnace steelmaking or to transport the iron-containing dust away by tank trucks.

[0062] Specifically, the dust-containing high-temperature waste gas is transported to recover sensible heat in the waste heat recovery device 3 and produce steam as a by-product.

[0063] Preferably, the temperature of the dusty high-temperature waste conveying gas discharged from the end of the hot high-temperature direct reduced iron pneumatic conveying pipeline is not lower than 300°C, the temperature of the dusty medium-temperature waste conveying gas at the outlet of the waste heat recovery device 3 is controlled to be not lower than 100°C, the temperature of the net conveying gas at the outlet of the dry dust removal device 4 is not lower than 60°C, and the pressure of the net conveying gas at the outlet of the pressurizing device 5 is not lower than 0.8MPa.

[0064] Specifically, the waste heat recovery device 3 is an indirect waste heat recovery device, preferably a waste heat boiler; the dry dust removal device 4 is one of a cartridge dust collector, a bag dust collector, an electrostatic precipitator or a cyclone dust collector, and adopts a high-temperature resistant metal filter element, and has a bag back-blowing cleaning device; the pressurizing device 5 adopts a centrifugal or screw pressurizer.

[0065] Preferably, the pressurizing device adopts a high-temperature pressurizing machine with an inlet temperature of 60℃~200℃ and an outlet temperature of 60℃~300℃, so that during the pressurizing process of the pressurizing device, there is no need to spray water for cooling, so as to ensure that the gas returned to the beginning of the pneumatic conveying pipeline after pressurization has a higher temperature, thereby saving energy consumption in subsequent steelmaking processes.

[0066] Furthermore, a heat preservation measure is provided on the gas delivery pipeline between the pressurizing device and the starting end of the pneumatic delivery pipeline to avoid temperature loss of the net delivered gas.

[0067] Example 1

[0068] like Figure 2 As shown in the figure, the 600℃ hot high-temperature direct reduced iron transported from the pneumatic conveying pipeline is accumulated in the lower part of the first material tank 1. The 0.6MPa, 500℃, 10g / Nm 3 The high-temperature waste gas is discharged from the upper part of the first material tank 1; the high-temperature waste gas enters from the bottom of the waste heat boiler, and after indirect heat exchange with soft water inside the waste heat boiler, it comes out from the top of the waste heat boiler. At this time, the temperature of the high-temperature waste gas drops to 180℃, and the waste heat boiler produces 1.0MPa, 200℃ steam as a by-product.

[0069] The medium-temperature raw gas from the waste heat boiler enters the dry dust removal device 4 from the bottom for fine dust removal, and outputs the clean gas. The clean gas comes out from the top of the dry dust removal device with a temperature of about 170°C, a pressure of about 0.58MPa, and a dust content of 10mg / Nm 3 The net conveying gas enters the centrifugal pressurizing device 5 and is pressurized to 0.68 MPa and a temperature of about 200° C., and then is incorporated into the pneumatic conveying inlet of the heating state high-temperature direct reduced iron as high-pressure net conveying gas.

[0070] A venting device is arranged on the top of the dry dust removal device 4. When the pressure exceeds 0.62 MPa, the venting valve in the venting device is automatically opened.

[0071] A gas supply device is installed on the gas delivery pipeline at the outlet of the pressurizing device 5, which replenishes 2.0MPa and 10m 3 of nitrogen to make up for the circulating gas lost due to pneumatic conveying.

[0072] A 1m 3 The silo pump is connected to the iron-containing dust pipeline, and 0.8MPa nitrogen is introduced into the iron-containing dust pipeline every 30 minutes. The iron-containing dust is pneumatically transported and recycled into the transfer tank 6, and the iron-containing dust is sucked away by the tank truck.

[0073] Specifically, the transfer tank is provided with two outlets, namely a top gas phase outlet and a bottom dust ash outlet.

[0074] Example 2

[0075] like Figure 3 As shown, the 580℃ hot high-temperature direct reduced iron transported from the pneumatic conveying pipeline is accumulated in the lower part of the first material tank 1, and the 0.8MPa, 500℃, 10g / Nm3 high-temperature rough conveying gas after pneumatic conveying is discharged from the upper part of the first material tank 1; the high-temperature rough conveying gas enters from the bottom of the heat exchanger, exchanges heat with soft water inside the heat exchanger, and then comes out from the top of the heat exchanger. At this time, the temperature of the high-temperature rough conveying gas drops to 180℃, and the heat exchanger produces 1.0MPa, 200℃ steam as a byproduct.

[0076] The medium-temperature raw gas from the heat exchanger enters the dry dust removal device from the bottom for fine dust removal. The clean gas comes out from the top of the dry dust removal device with a temperature of about 170°C, a pressure of about 0.78MPa, and a dust content of 10mg / Nm 3 After the net conveying gas enters the centrifugal pressurizing device and is pressurized to 1.0 MPa and a temperature of about 200°C, it is incorporated into the pneumatic conveying inlet of the heating state high-temperature direct reduced iron as high-pressure net conveying gas.

[0077] A venting device is set on the top of the dry dust removal device. When the pressure exceeds 0.82MPa, the vent valve in the venting device will be automatically opened.

[0078] There is a gas supply device on the gas pipeline at the outlet of the pressurizing device to replenish 2.0MPa, 10m 3 of nitrogen to make up for the circulating gas lost due to pneumatic conveying.

[0079] Set up a 1m 3 A silo pump is used to introduce 0.8 MPa of nitrogen into the iron-containing dust pipeline every 9 minutes. The pneumatic conveying time for each time is 5 seconds. The iron-containing dust is recycled into the second material tank 2 through pneumatic conveying for subsequent electric furnace steelmaking.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A process for recycling gas from hot high-temperature direct reduced iron pneumatic conveying, characterized in that: The following steps are involved: The pneumatic conveying pipeline from hot high-temperature direct reduced iron is connected to the material tank, in which the hot high-temperature direct reduced iron is accumulated, and the dusty high-temperature waste conveying gas is discharged from the material tank, and is formed into a clean conveying gas after the waste heat is recovered by an indirect waste heat recovery device and the dust is removed and purified by a dry dust removal device, and then reused to the pneumatic conveying pipeline for hot high-temperature direct reduced iron.

2. The hot high-temperature direct reduced iron pneumatic conveying gas recycling process according to claim 1 is characterized in that: The dusty high-temperature waste gas conveying method satisfies at least one of the following conditions: (1) Temperature is 300℃~650℃; (2) The pressure is 0.1MPa to 1.0MPa; (3) Dust content is 1g / Nm 3 ~20g / Nm 3 .

3. The process for recycling gas from pneumatic conveying of hot high-temperature direct reduced iron according to claim 1, characterized in that: The indirect waste heat recovery device is a waste heat boiler, which uses the waste heat boiler to recover the sensible heat of the dust-containing high-temperature waste transport gas and produce steam as a by-product, and cools the dust-containing high-temperature waste transport gas to 100°C to 200°C to form dust-containing medium-temperature waste transport gas.

4. The process for recycling gas from pneumatic conveying of hot high-temperature direct reduced iron according to claim 1, characterized in that: The indirect waste heat recovery device is an indirect heat exchanger, which recovers the waste heat of the dust-containing high-temperature waste transport gas through heat exchange with other refrigerants, and forms dust-containing medium-temperature waste transport gas.

5. The process for recycling gas from pneumatic conveying of hot high-temperature direct reduced iron according to claim 1, characterized in that: The dry dust removal device adopts a dry filter bag dust collector or a dry electric dust collector; And / or, the dust content of the clean conveying gas after dust removal and purification by the dry dust removal device is less than or equal to 10 mg / Nm 3 .

6. The process for recycling gas from pneumatic conveying of hot high-temperature direct reduced iron according to claim 1, characterized in that: The dust and ash accumulated by the dust-containing high-temperature waste gas at the bottom of the waste heat recovery device and the bottom of the dry dust removal device are transported to the material tank through a closed pipeline or a gravity chute for subsequent steelmaking.

7. The process for recycling gas from hot high-temperature direct reduced iron pneumatic conveying according to claim 1, characterized in that: The dust and ash accumulated by the dust-containing high-temperature waste gas at the bottom of the waste heat recovery device and the bottom of the dry dust removal device are transported to the transfer tank through a closed pipeline and transported out by a tank truck.

8. The process for recycling gas from hot high-temperature direct reduced iron pneumatic conveying according to any one of claims 1 to 7, characterized in that: The net conveying gas is pressurized by a pressurizing device and then recycled to the hot high-temperature direct reduced iron pneumatic conveying pipeline.

9. The process for recycling gas from hot high-temperature direct reduced iron pneumatic conveying according to claim 8, characterized in that: The pressurizing device adopts a high-temperature pressurizing machine, and controls the inlet temperature to be 60°C to 200°C and the outlet temperature to be 60°C to 300°C.

10. The process for recycling gas from pneumatic conveying of hot high-temperature direct reduced iron according to claim 8, characterized in that: The pressure of the net conveying gas after being pressurized by the pressurizing device is 0.2MPa to 1.4MPa.

11. The process for recycling gas from pneumatic conveying of hot high-temperature direct reduced iron according to claim 1, characterized in that: The net conveying gas is nitrogen or a mixed gas mainly composed of nitrogen.

12. The process for recycling gas from hot high-temperature direct reduced iron pneumatic conveying according to claim 1, characterized in that: The net conveying gas is recycled to the beginning of the hot high-temperature direct reduced iron pneumatic conveying pipeline through the gas conveying pipeline.

13. The process for recycling gas from hot high-temperature direct reduced iron pneumatic conveying according to claim 12, characterized in that: The gas delivery pipeline is provided with a venting device and a gas supply device to adjust the gas volume in the gas delivery pipeline; And / or, the air-supplementing medium in the air-supplementing device is nitrogen.

14. The process for recycling gas from hot high-temperature direct reduced iron pneumatic conveying according to claim 12, characterized in that: The material tank is located at the end of the hot high-temperature direct reduced iron pneumatic conveying pipeline.

15. A hot high-temperature direct reduced iron pneumatic conveying gas recycling system, characterized in that: It includes a material tank, a waste heat recovery device and a dry dust removal device. The material tank is connected to the end of the hot high-temperature direct reduced iron pneumatic conveying pipeline and is used to receive the hot high-temperature direct reduced iron and dust-containing high-temperature iron conveying gas. The material tank is connected to the waste heat recovery device and the dry dust removal device in sequence through the gas conveying pipeline, and the dry dust removal device is connected to the starting end of the hot high-temperature direct reduced iron pneumatic conveying pipeline through the gas conveying pipeline.

16. The hot high-temperature direct reduced iron pneumatic conveying gas recycling system according to claim 15, characterized in that: The invention also comprises a pressurizing device connected after the dry dust removing device.

17. The hot high-temperature direct reduced iron pneumatic conveying gas recycling system according to claim 16, characterized in that: The material tank comprises a first material tank and a second material tank, the end of the hot high-temperature direct reduced iron pneumatic conveying pipeline is connected to the top of the first material tank, and the top of the first material tank is connected to the waste heat recovery device through the gas conveying pipeline; The second material tank is connected to the bottom of the first material tank to receive the hot high-temperature direct reduced iron in the first material tank.

18. The hot high-temperature direct reduced iron pneumatic conveying gas recycling system according to claim 17, characterized in that: Iron-containing dust pipelines are provided at the bottom of the waste heat recovery device and the dry dust removal device, and the iron-containing dust pipelines are connected to a second material tank to recover the dust at the bottom of the waste heat recovery device and the dry dust removal device.

19. The hot high-temperature direct reduced iron pneumatic conveying gas recycling system according to claim 17, characterized in that: Iron-containing dust pipelines are provided at the bottom of the waste heat recovery device and the dry dust removal device, and the iron-containing dust pipelines are connected to a transfer tank to recover the dust at the bottom of the waste heat recovery device and the dry dust removal device.

20. The hot high-temperature direct reduced iron pneumatic conveying gas recycling system according to claim 15, characterized in that: It also includes a venting device and an air supply device. The venting device is arranged on the top of the gas conveying pipeline at or behind the dry dust removal device, and the air supply device is arranged on the gas conveying pipeline and is located after the venting device.

21. The hot high-temperature direct reduced iron pneumatic conveying gas recycling system according to claim 15, characterized in that: The dry dust removal device is provided with a back-blowing and dust-cleaning device to perform back-blowing and dust-cleaning on the dry dust removal device during intervals of dust purification and dust removal.

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