Thermal-state sponge iron pneumatic conveying gas treatment system

Abstract

The utility model belongs to the technical field of ferrous metallurgy, and relates to a thermal-state sponge iron pneumatic conveying gas treatment system which comprises a charging bucket, a waste heat recovery device and a dry type dust removal device, and the charging bucket is connected to the tail end of a thermal-state high-temperature direct reduction iron pneumatic conveying pipeline. The charging bucket is used for receiving hot-state high-temperature direct reduction iron and dust-containing high-temperature crude conveying gas, the charging bucket is sequentially connected with a waste heat recovery device, a dry dust removal device and a pressurizing device through a gas conveying pipeline, and the pressurizing device is connected with a hot-state high-temperature direct reduction iron pneumatic conveying pipeline through a gas conveying pipeline; and bin pumps are arranged at the bottoms of the waste heat recovery device and the dry dust removal device and are used for depositing dust in the dust-containing high-temperature crude conveying gas. By means of the indirect waste heat recovery device and the dry dust removal device, no sewage and sludge treatment system is achieved, direct contact between water and thermal sponge iron is isolated, heat release and hydrogen caused by direct contact between water and thermal sponge iron are avoided, and the hidden danger of spontaneous combustion and explosion is avoided.

Description

Technical Field

[0001] The utility model belongs to the technical field of iron and steel metallurgy, and relates to a gas treatment system for pneumatic conveying of hot sponge iron. Background Technique

[0002] High-temperature hot direct reduced iron (sponge iron) is pneumatically conveyed through a pipeline by a gas (usually nitrogen) to a steelmaking workshop. During the pneumatic conveying process, the conveying gas exchanges heat with the high-temperature hot direct reduced iron in the conveying pipeline, causing the temperature of the conveying gas at the end of the conveying to rise, and being mixed with direct reduced iron dust. Direct reduced iron easily reacts with water or air to release heat, so it is easy to generate self-heat to provide heat sources. The reaction of direct reduced iron at normal temperature is very slow, but when the temperature reaches above 200 °C, the reaction rate will increase significantly, 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 ignite". 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 prone to explosion.

[0003] During the process of pneumatically conveying hot sponge iron with a gas, considering the danger of hot sponge iron, generally a large amount of water is used to cool the conveying gas entraining the sponge iron to make it drop to a safe temperature, and at the same time, the sponge iron dust is removed to realize the treatment process of recycling the conveying gas. This process still has the following technical problems:

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

[0005] (2) The water in the wet washing process and the saturated water remaining in the conveying gas after wet dust removal will inevitably generate hydrogen when directly contacting the sponge iron, and an explosive atmosphere environment is likely to occur when the ventilation is poor or hydrogen accumulates, there are potential safety hazards.

[0006] (3) The conveying gas is cooled and dust-removed by the water washing method, forming a large amount of turbid circulating water, which requires supporting turbid circulating water treatment and sludge treatment, covering a large area and having poor environmental protection effects.

[0007] (4) After the conveying gas is treated by water washing and then sent back to the beginning of the pneumatic conveying, the temperature is relatively low, consuming more heat carried by the high-temperature direct reduced iron itself during the pneumatic conveying process, resulting in a decrease in the temperature at the end of the conveying, and further leading to an increase in the energy consumption in the subsequent steelmaking process and poor economy.

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

[0009] In summary, the root cause of the technical problems existing in the gas purification and cooling process of pneumatic conveying of hot sponge iron lies in the lack of a reliable gas recycling system. Summary of the Invention

[0010] In view of this, the purpose of the present invention is to provide a hot sponge iron pneumatic conveying gas treatment system to solve potential hazards such as spontaneous combustion and explosion risks 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 in the steelmaking process.

[0011] To achieve the above purpose, the present invention provides the following technical solutions:

[0012] A hot sponge iron pneumatic conveying gas treatment system includes a storage tank, a waste heat recovery device, and a dry dust removal device. The storage tank is connected to the end of the hot high-temperature direct reduced iron pneumatic conveying pipeline for receiving hot high-temperature direct reduced iron and dusty hot waste conveying gas. The storage tank is sequentially connected to the waste heat recovery device, the dry dust removal device, and a pressurizing device through a gas conveying pipeline, and the pressurizing device is connected to the hot high-temperature direct reduced iron pneumatic conveying pipeline through a gas conveying pipeline to recycle the dusty hot waste conveying gas treated by the waste heat recovery device, the dry dust removal device, and the pressurizing device to the hot high-temperature direct reduced iron pneumatic conveying pipeline;

[0013] Silo pumps are provided at the bottoms of both the waste heat recovery device and the dry dust removal device for depositing the dust ash in the dusty hot waste conveying gas.

[0014] Further, the storage tank includes a first storage tank and a second storage tank. The end of the hot high-temperature direct reduced iron pneumatic conveying pipeline is connected to the top of the first storage tank, and the top of the first storage tank is connected to the waste heat recovery device through a gas conveying pipeline;

[0015] The second storage tank is connected to the bottom of the first storage tank to receive the hot high-temperature direct reduced iron in the first storage tank.

[0016] Further, iron-containing dust ash pipelines are connected to the silo pumps of both the waste heat recovery device and the dry dust removal device, and the iron-containing dust ash pipelines are connected to the second storage tank to recover the dust ash at the bottoms of the waste heat recovery device and the dry dust removal device.

[0017] Further, iron-containing dust ash pipelines are connected to the silo pumps of both the waste heat recovery device and the dry dust removal device. After the iron-containing dust ash pipelines are aggregated, they are respectively connected to the second storage tank and a transfer tank, and a first valve and a second valve are provided on the pipelines connecting the second storage tank and the transfer tank respectively.

[0018] Further, iron-containing dust ash pipelines are connected to the silo pumps of the waste heat recovery device and the dry dust removal device, and the iron-containing dust ash pipelines are connected to transfer tanks to recover the dust ash at the bottoms of the waste heat recovery device and the dry dust removal device.

[0019] Further, the dry dust removal device is equipped with a reverse blowing and dust cleaning device to perform reverse blowing and dust cleaning on the dry dust removal device during the gap of purification and dust removal.

[0020] Further, it also includes an air venting device and an air supplementing device. The air venting device is arranged at the top of the dry dust removal device or the gas transmission pipeline behind it, and the air supplementing device is arranged on the gas transmission pipeline and is located behind the air venting device.

[0021] Further, the pressurizing device is connected to the starting end of the hot-state high-temperature direct reduced iron pneumatic conveying pipeline through a gas transmission pipeline.

[0022] The beneficial effects of the present utility model are as follows:

[0023] 1. A hot-state sponge iron pneumatic conveying gas treatment system provided by the present invention uses an indirect waste heat recovery device to recover the sensible heat of the dusty high-temperature raw conveying gas and by-produces steam, achieving waste heat recovery. The iron-containing dust in the dusty high-temperature raw conveying gas recovered by the dry dust removal device is directly supplied to steelmaking users for use or transported out, improving the utilization of raw materials and saving raw materials. Moreover, through the indirect waste heat recovery process and the dry dust removal process, a sewage and sludge treatment system is not required, with remarkable environmental benefits, small system footprint, simple operation, and investment savings.

[0024] 2. The present invention uses a pressurizing machine to pressurize the clean conveying gas and then send it back to the starting end of the hot-state high-temperature direct reduced iron pneumatic conveying pipeline, increasing the temperature of the pneumatic conveying gas, reducing the heat loss of the hot-state direct reduced iron during pneumatic conveying, thereby increasing the temperature of the hot sponge iron entering the steelmaking user and reducing the energy consumption in the steelmaking process.

[0025] 3. The present invention isolates the direct contact between water and the hot sponge iron, avoiding a large amount of heat release and a large amount of hydrogen, and preventing potential hidden dangers of spontaneous combustion and explosion.

[0026] Other advantages, objectives, and features of the present utility model will be described to some extent in the subsequent description, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be taught from the practice of the present utility model. The objectives and other advantages of the present utility model can be achieved and obtained through the following description. Description of the Drawings

[0027] To make the objectives, technical solutions and advantages of the present utility model clearer, the present utility model will be described in detail and preferably below in conjunction with the accompanying drawings, where:

[0028] Figure 1 It is a schematic structural diagram of a hot sponge iron pneumatic conveying gas treatment system in the present invention;

[0029] Figure 2 It is a schematic structural diagram of a hot sponge iron pneumatic conveying gas treatment system in Embodiment 1;

[0030] Figure 3 It is a schematic structural diagram of a hot sponge iron pneumatic conveying gas treatment system in Embodiment 2.

[0031] 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. Specific embodiments

[0032] The following uses specific specific examples to illustrate the implementation manners of the present utility model. Those skilled in the art can easily understand other advantages and effects of the present utility model from the content disclosed in this specification. The present utility model can also be implemented or applied through different specific implementation manners. The details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present utility model. It should be noted that the drawings provided in the following embodiments only illustrate the basic concept of the present utility model in a schematic manner. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0033] Among them, the drawings are only for illustrative purposes, showing only schematic diagrams, not physical diagrams, and cannot be understood as a limitation to the present utility model; in order to better illustrate the embodiments of the present utility model, some components in the drawings will be omitted, enlarged or reduced, which does not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0034] In the drawings of the embodiments of the present utility model, the same or similar reference numerals correspond to the same or similar components; in the description of the present utility model, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and cannot be understood as a limitation to the present utility model. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0035] Please refer to Figure 1 , which is a hot-state sponge iron pneumatic conveying gas treatment system, including a first storage tank 1, a second storage tank 2, a waste heat recovery device 3, a dry dust removal device 4, a pressurization device 5 and a transfer tank 6. The first storage tank 1 is connected to the end of the hot-state high-temperature direct reduced iron pneumatic conveying pipeline. A valve (specifically, it can be a dome valve, a material separating valve, a bar gate valve or a wear-resistant manual ball valve) is provided at the bottom of the first storage tank 1, and the valve is connected to the second storage tank 2 through a closed pipeline or a gravity chute. The top of the first storage tank 1 is sequentially connected with a waste heat recovery device 3, a dry dust removal device 4 and a pressurization device 5 through a gas reuse treatment pipeline, and the gas reuse treatment pipeline is connected to the beginning of the hot-state high-temperature direct reduced iron pneumatic conveying pipeline;

[0036] And storage pumps are provided at the bottoms of the waste heat recovery device 3 and the dry dust removal device 4 respectively for collecting the dust in the dusty high-temperature raw conveying gas and the dusty medium-temperature raw conveying gas. The storage pumps are connected to the second storage tank 2 or the transfer tank 6 through an iron-containing dust ash pipeline. Specifically, the iron-containing dust ash pipelines are aggregated and then connected to the second storage tank and the transfer tank respectively, and a first valve and a second valve are provided on the pipelines connecting to the second storage tank and the transfer tank respectively to achieve a one-choice-two for the second storage tank and the transfer tank.

[0037] Preferably, a nitrogen source is connected to the iron-containing dust ash pipeline to pneumatically convey and reuse the iron-containing dust ash into the second storage tank 2 or the transfer tank 6 for subsequent electric arc furnace steelmaking use or the iron-containing dust ash is sucked away by a tank truck.

[0038] Specifically, the sensible heat of the dusty high-temperature raw conveying gas is recovered in the waste heat recovery device 3, and by-product steam is produced.

[0039] 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 filter, a bag filter, an electrostatic precipitator or a cyclone dust collector, and uses a high-temperature-resistant metal filter element and has a bag reverse blowing and dust cleaning device; the pressurization device 5 uses a centrifugal or screw compressor.

[0040] Specifically, the technological process of this hot-state sponge iron pneumatic conveying gas treatment system includes the following steps:

[0041] The hot-state high-temperature direct reduced iron from the hot-state high-temperature direct reduced iron pneumatic conveying pipeline accumulates in the lower part of the first storage tank 1, and the dusty high-temperature raw conveying gas after pneumatic conveying is stored in the upper part of the first storage tank 1;

[0042] The dusty high-temperature raw conveying gas is discharged from the top of the first storage tank 1, enters the waste heat recovery device 3 to recover waste heat, and is cooled to a dusty medium-temperature raw conveying gas;

[0043] The dusty medium-temperature waste conveying gas enters the dry dust removal device 4 for dust removal and purification, and the separated dust is accumulated at the bottom of the dry dust removal device 4, and the purified conveying gas after dust removal is discharged from the upper part of the dry dust removal device 4;

[0044] After being pressurized by the pressurizing device 5, the purified conveying gas is recycled to the beginning of the hot-state high-temperature direct reduced iron pneumatic conveying pipeline for hot-state high-temperature direct reduced iron pneumatic conveying;

[0045] 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 storage tank 2 for recycling or sent out by the transfer tank 6.

[0046] Preferably, the temperature of the dusty high-temperature waste conveying gas discharged from the end of the hot-state 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 purified conveying gas at the outlet of the dry dust removal device 4 is not lower than 60 °C, and the pressure of the purified conveying gas at the outlet of the pressurizing device 5 is not lower than 0.8 MPa.

[0047] Preferably, the pressurizing device adopts a high-temperature pressurizer with an inlet temperature of 60 °C to 200 °C and an outlet temperature of 60 °C to 300 °C, so that no water spraying is required for cooling during the pressurizing process of the pressurizing device.

[0048] Example 1

[0049] As Figure 2 shown, the 600 °C hot-state high-temperature direct reduced iron conveyed from the pneumatic conveying pipeline is accumulated at the lower part of the first storage tank 1, and the high-temperature waste conveying gas with a pressure of 0.6 MPa, a temperature of 500 °C, and a dust content of 10 g / Nm 3 is discharged from the upper part of the first storage tank 1; the high-temperature waste conveying gas enters from the bottom of the waste heat boiler and exchanges heat indirectly with soft water inside the waste heat boiler and then comes out from the top of the waste heat boiler. At this time, the temperature of the high-temperature waste conveying gas drops to 180 °C, and the waste heat boiler produces steam with a pressure of 1.0 MPa and a temperature of 200 °C.

[0050] The medium-temperature waste conveying gas coming out of the waste heat boiler enters the dry dust removal device 4 from the bottom for fine dust removal and outputs the purified conveying gas. The purified conveying gas comes out from the top of the dry dust removal device, with a temperature of about 170 °C, a pressure of about 0.58 MPa, and a dust content of 10 mg / Nm 3 . The purified conveying gas enters the centrifugal pressurizing device 5 to be boosted to 0.68 MPa and a temperature of about 200 °C, and then is incorporated into the hot-state high-temperature direct reduced iron pneumatic conveying inlet as the high-pressure purified conveying gas.

[0051] An air venting device is installed at the top of the dry dust removal device 4. When the pressure exceeds 0.62 MPa, the air vent valve in the air venting device will automatically open.

[0052] A gas supplementing device is installed on the gas pipeline at the outlet of the pressurizing device 5. Nitrogen with a pressure of 2.0 MPa and a volume of 10 m is supplemented every 2 hours 3 to supplement the circulating gas volume lost due to pneumatic conveying.

[0053] A 1m 3 silo pump is installed at the bottom of each of the waste heat boiler and the dry dust removal device and is connected to the iron-containing dust ash pipeline. Nitrogen with a pressure of 0.8 MPa is introduced into the iron-containing dust ash pipeline every 30 minutes. The iron-containing dust ash is recycled into the transfer tank 6 through pneumatic conveying and is sucked away by a tank truck.

[0054] Specifically, the transfer tank is provided with two outlets, namely the top gas phase outlet and the bottom dust ash outlet.

[0055] Example 2

[0056] As Figure 3 shown, the 580 °C hot state direct reduced iron transported from the pneumatic conveying pipeline accumulates at the lower part of the first storage tank 1, and the high-temperature raw conveying gas with a pressure of 0.8 MPa, a temperature of 500 °C, and a dust content of 10 g / Nm is discharged from the upper part of the first storage tank 1; the high-temperature raw conveying gas enters from the bottom of the heat exchanger, exchanges heat with soft water inside the heat exchanger, and exits from the top of the heat exchanger. At this time, the temperature of the high-temperature raw conveying gas drops to 180 °C, and the heat exchanger produces steam with a pressure of 1.0 MPa and a temperature of 200 °C.

[0057] The medium-temperature raw conveying gas coming out of the heat exchanger enters the dry dust removal device from the bottom for fine dust removal. The clean conveying gas exits from the top of the dry dust removal device, with a temperature of about 170 °C, a pressure of about 0.78 MPa, and a dust content of 10 mg / Nm 3 . The clean conveying gas enters the centrifugal pressurizing device to be pressurized to 1.0 MPa and a temperature of about 200 °C, and then is incorporated into the pneumatic conveying inlet for the hot state direct reduced iron as the high-pressure clean conveying gas.

[0058] An air venting device is installed at the top of the dry dust removal device. When the pressure exceeds 0.82 MPa, the air vent valve in the air venting device will automatically open.

[0059] A gas supplementing device is installed on the gas pipeline at the outlet of the pressurizing device. Nitrogen with a pressure of 2.0 MPa and a volume of 10 m is supplemented every 2 hours 3 to supplement the circulating gas volume lost due to pneumatic conveying.

[0060] A 1m silo pump is installed at the bottom of the dry dust removal device 3For the silo pump, nitrogen gas at 0.8 MPa is introduced into the iron-containing dust ash pipeline every 9 minutes, and the pneumatic conveying time each time is 5 seconds. The iron-containing dust ash is recycled through pneumatic conveying and enters the second storage tank 2 for subsequent use in electric arc furnace steelmaking.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not restrictive. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the present technical solution, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A hot-state sponge iron pneumatic conveying gas treatment 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 pneumatic conveying pipeline of hot state high-temperature direct reduced iron, and is used to receive hot state high-temperature direct reduced iron and dusty hot raw conveying gas. The material tank is sequentially connected to the waste heat recovery device, the dry dust removal device and a pressurizing device through a gas conveying pipeline, and the pressurizing device is connected to the pneumatic conveying pipeline of hot state high-temperature direct reduced iron through a gas conveying pipeline, so as to recycle the purified dusty hot raw conveying gas after being treated by the waste heat recovery device, the dry dust removal device and the pressurizing device back to the pneumatic conveying pipeline of hot state high-temperature direct reduced iron; Silo pumps are provided at the bottoms of both the waste heat recovery device and the dry dust removal device to deposit the dust ash in the dusty hot raw conveying gas.

2. The hot-state sponge iron pneumatic conveying gas treatment system according to claim 1, wherein: The material tank includes a first material tank and a second material tank. The end of the pneumatic conveying pipeline of hot state high-temperature direct reduced iron 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 a gas conveying pipeline; The second material tank is connected to the bottom of the first material tank to receive the hot state high-temperature direct reduced iron in the first material tank.

3. The hot sponge iron pneumatic conveying gas treatment system according to claim 2, wherein: Iron-containing dust ash pipelines are connected to the silo pumps of both the waste heat recovery device and the dry dust removal device, and the iron-containing dust ash pipelines are connected to the second material tank to recover the dust ash at the bottoms of the waste heat recovery device and the dry dust removal device.

4. The hot-state sponge iron pneumatic conveying gas treatment system according to claim 2, wherein: Iron-containing dust ash pipelines are connected to the silo pumps of both the waste heat recovery device and the dry dust removal device. After the iron-containing dust ash pipelines are aggregated, they are respectively connected to the second material tank and a transfer tank, and a first valve and a second valve are respectively provided on the pipelines connecting the second material tank and the transfer tank.

5. The hot-state sponge iron pneumatic conveying gas treatment system according to claim 1, characterized in that: Iron-containing dust ash pipelines are connected to the silo pumps of both the waste heat recovery device and the dry dust removal device, and the iron-containing dust ash pipelines are connected to the transfer tank to recover the dust ash at the bottoms of the waste heat recovery device and the dry dust removal device.

6. The hot sponge iron pneumatic conveying gas treatment system according to claim 1, characterized in that: The dry dust removal device is equipped with a reverse blowing and dust cleaning device to perform reverse blowing and dust cleaning on the dry dust removal device during the gap of purification and dust removal.

7. The hot-state sponge iron pneumatic conveying gas treatment system according to claim 1, characterized in that: It also includes a venting device and a gas supplementing device. The venting device is arranged at the top of the dry dust removal device or the gas conveying pipeline behind it, and the gas supplementing device is arranged on the gas conveying pipeline and is located behind the venting device.

8. The hot sponge iron pneumatic conveying gas treatment system according to claim 1, characterized in that: The pressurizing device is connected to the starting end of the pneumatic conveying pipeline of hot state high-temperature direct reduced iron through a gas conveying pipeline.

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