Coal gas heat exchange device

Abstract

The utility model relates to a coal gas heat exchange device belongs to metallurgical chemical industry technical field. Set up in the coal gas export end of shaft furnace, including the dust remover, primary heat exchanger, secondary heat exchanger, tertiary heat exchange system that connect in proper order, the import end of dust remover connects the coal gas export end of shaft furnace, and the cold end coal gas entrance, cold end coal gas export are equipped with respectively on primary heat exchanger, secondary heat exchanger, and tertiary heat exchange system includes cooling water circulation loop and organic rankine circulation loop, and cooling water circulation loop includes the tertiary heat exchanger, circulating pump and evaporator that connect in proper order along the cooling water flow direction, and organic rankine circulation loop includes the evaporator, expander, condenser, working medium pump that connect in proper order, and still be equipped with heating water entrance, heating water export on the tertiary heat exchanger. The utility model preheats low temperature coal gas through primary, secondary heat exchanger, heats the heating water with tertiary heat exchanger, can also adopt organic rankine cycle ORC power generation, prevents the heat exchanger from happening the blockage through the dust remover.

Description

Technical Field

[0001] This utility model belongs to the field of metallurgical and chemical technology, and relates to a gas heat exchange device. Background Technology

[0002] Gas-based vertical shaft furnace direct reduction (DRR) is a crucial non-blast furnace ironmaking process that dominates the global DRR production field, making it the world's largest non-blast furnace ironmaking technology in terms of DRR output. Due to its inherent properties, DRR has become a high-quality raw material for various industries, including electric arc furnaces, converters, blast furnaces, and powder metallurgy, and has received increasing attention from national and metallurgical industry personnel in recent years.

[0003] Direct reduced iron (DRI) offers significant advantages in electric arc furnace (EAF) steelmaking. It effectively improves the purity of molten steel and is an indispensable high-quality raw material for special steel smelting. For EAF enterprises with unstable scrap steel quality, the addition of DRI can dilute harmful elements in the steel, stabilize its quality, and provide a strong guarantee for producing high-quality steel. Furthermore, the DRI process does not use coke, and iron ore does not require sintering. This not only saves valuable coking coal resources but also reduces the two key stages of coking and sintering, which generate the largest amounts of waste gas in steel enterprises. Compared to traditional blast furnace processes, it has a clear advantage in environmental protection.

[0004] However, during the operation of gas-based vertical shaft furnaces, there are many technical problems that urgently need to be solved in the waste heat recovery process of the furnace top gas. Currently, existing waste heat recovery devices for gas-based vertical shaft furnaces mainly recover waste heat by heating the pellets with the furnace top gas. However, this traditional method has obvious drawbacks: the waste heat recovery rate is low, and a large amount of heat energy is lost during the recovery process, resulting in serious energy waste and failing to meet the current industrial development requirements of energy conservation and emission reduction.

[0005] To improve this situation, a new waste heat recovery device for gas-based vertical shaft furnace top gas has been proposed. The design involves introducing the top gas into the coils of the heat exchanger to heat the pellets, attempting to achieve more efficient utilization of the waste heat. However, practical testing has shown that this solution does not fundamentally solve the problem; the heat utilization efficiency remains low and cannot meet the demands for efficient energy recovery and utilization in actual production.

[0006] Another proposal suggests installing a waste heat recovery device for a gas-based vertical shaft furnace with a heat exchange chamber. This allows heat exchange between the material inside the chamber and the furnace top gas, after which the top gas is discharged from the chamber. Essentially, this device still uses the furnace top gas to heat the pellets, offering no substantial improvement in heat utilization efficiency. More problematic is the large amount of dust contained in the furnace top gas. During heat exchange, this dust easily adheres to the inner wall of the heat exchange device, causing blockages over time. Blockage not only affects waste heat recovery and reduces production efficiency but also increases maintenance costs and repair difficulty, negatively impacting the company's production and operations.

[0007] Therefore, it is urgent to develop efficient and reliable waste heat recovery technology for furnace top gas. Utility Model Content

[0008] In view of this, the purpose of this utility model is to provide a gas heat exchange device to improve the utilization efficiency of waste heat from the furnace top gas and prevent heat exchanger blockage.

[0009] To achieve the above objectives, this utility model provides the following technical solution: A gas heat exchange device is installed at the gas outlet end of a vertical shaft furnace, comprising a dust collector, a primary heat exchanger, a secondary heat exchanger, and a tertiary heat exchange system connected in sequence. The inlet end of the dust collector is connected to the gas outlet end of the vertical shaft furnace, and the gas outlet end of the dust collector is connected to the gas inlet end of the primary heat exchanger. The primary and secondary heat exchangers are respectively provided with a cold-end gas inlet and a cold-end gas outlet. The tertiary heat exchange system includes a cooling water circulation loop and an organic Rankine circulation loop. The cooling water circulation loop includes a tertiary heat exchanger, a circulation pump, and an evaporator connected in sequence along the cooling water flow direction. The organic Rankine circulation loop includes the evaporator, an expander, a condenser, and a working fluid pump connected in sequence. The first inlet end of the evaporator is connected to the outlet end of the circulation pump, the first outlet end of the evaporator is connected to the inlet end of the tertiary heat exchanger, the second outlet end of the evaporator is connected to the inlet end of the expander, and the second inlet end of the evaporator is connected to the outlet end of the working fluid pump. The tertiary heat exchanger is also provided with a heating water inlet and a heating water outlet.

[0010] Optionally, the dust collector is an electrostatic precipitator or a metal bag filter dust collector.

[0011] Optionally, the primary heat exchanger and the secondary heat exchanger are plate heat exchangers.

[0012] Optionally, the plate heat exchanger is externally encased in a metal shell.

[0013] Optionally, the primary heat exchanger and the secondary heat exchanger are shell-and-tube heat exchangers.

[0014] Optionally, the three-stage heat exchanger is a coiled tube heat exchanger.

[0015] Optionally, the gas inlet ends of the dust collector, the primary heat exchanger, and the tertiary heat exchanger are respectively equipped with a butterfly valve and a slide gate valve; the gas outlet end of the tertiary heat exchanger is respectively equipped with a butterfly valve and a slide gate valve; the butterfly valve is used to regulate the flow rate and pressure of the medium inside the pipeline, and the slide gate valve is used to achieve safe shut-off of the medium inside the pipeline.

[0016] Optionally, the cold-end gas inlet of the primary heat exchanger and the secondary heat exchanger are respectively equipped with a cold-end gas inlet valve, and the cold-end gas outlet is respectively equipped with a cold-end gas outlet valve, so as to control the entry and exit of the cold-end gas; the heating water inlet of the tertiary heat exchanger is equipped with a heating water inlet valve, and the heating water outlet is equipped with a heating water outlet valve, so as to control the entry and exit of the heating water.

[0017] Optionally, the three-stage heat exchanger is equipped with a cooling water outlet valve at the cooling water outlet end and a cooling water inlet valve at the cooling water inlet end to control the opening and closing of the cooling water.

[0018] The beneficial effects of this utility model are as follows: This utility model's gas heat exchange device connects the high-temperature, high-pressure gas at the vertical furnace gas outlet to a high-temperature dust collector, making the heat exchanger less prone to clogging. It also features a three-stage heat exchanger, where the first and second stages can preheat the high-temperature and low-temperature gas respectively, according to different process requirements. A cooling water circulation loop is connected to the third-stage heat exchanger, which can be used to heat heating water. A condenser, expander, and working fluid pump are added to the cooling water circulation loop, forming an organic Rankine loop. In areas where heating is not required in summer or year-round, the heat pump system and the organic Rankine loop are coupled to generate electricity, not only meeting the process cooling gas requirements but also achieving a waste heat utilization efficiency of over 90%. Furthermore, placing the working fluid pump in the second-stage circulation loop allows the high-temperature, high-pressure gas to undergo preliminary heat exchange in the cooling water circulation loop before passing through the second-stage organic Rankine loop, reducing the overall investment cost of the circulation loop and improving economic efficiency.

[0019] The primary and secondary heat exchangers of this invention employ plate heat exchangers, with a metal shell surrounding each plate heat exchanger. In the event of a gas leak, the leaked gas enters the metal shell instead of escaping, ensuring the safety of high-pressure, high-volume gas heat exchange. The tertiary heat exchanger uses a coiled-tube heat exchanger to heat the heating water. Compared to other types of heat exchangers, the coiled-tube heat exchanger has a larger heat exchange area and smaller volume, making it suitable for high-volume operation.

[0020] Other advantages, objectives, and features of this invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination and study, or may be learned from practice of this invention. The objectives and other advantages of this invention can be realized and obtained through the following description. Attached Figure Description

[0021] To make the objectives, technical solutions, and advantages of this utility model clearer, the preferred embodiments of this utility model will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the overall design of this utility model.

[0022] Figure label: 1. Butterfly valve; 2. Gate valve; 3. Dust collector; 4. Gas inlet butterfly valve for primary heat exchanger; 5. Gas inlet gate valve for primary heat exchanger; 6. Primary heat exchanger; 7. Secondary heat exchanger; 8. Gas inlet butterfly valve for tertiary heat exchanger; 9. Gas inlet gate valve for tertiary heat exchanger; 10. Tertiary heat exchanger; 11. Gas outlet butterfly valve for tertiary heat exchanger; 12. Gas outlet gate valve for tertiary heat exchanger; 13. Gas inlet valve for cold end of primary heat exchanger; 14. Gas outlet valve for cold end of primary heat exchanger; 15. Gas inlet valve for cold end of secondary heat exchanger; 16. Gas outlet valve for cold end of secondary heat exchanger; 17. Heating water inlet valve for tertiary heat exchanger; 18. Heating water outlet valve for tertiary heat exchanger; 19. Cooling water inlet valve for tertiary heat exchanger; 20. Cooling water outlet valve for tertiary heat exchanger; 21. Circulating pump; 22. Evaporator; 23. Expander; 24. Condenser; 25. Working fluid pump; 26. Vertical shaft furnace. Detailed Implementation

[0023] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this utility model. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0024] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the present invention. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0025] In the accompanying drawings of this utility model, the same or similar reference numerals correspond to the same or similar components. In the description of this utility model, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting this utility model. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0026] Please see Figure 1 This is a gas heat exchange device installed at the gas outlet end of a vertical shaft furnace 26. It includes a dust collector 3, a primary heat exchanger 6, a secondary heat exchanger 7, and a tertiary heat exchange system connected in sequence. The inlet end of the dust collector 3 is connected to the high-temperature, high-pressure gas at the gas outlet end of the vertical shaft furnace 26, and the gas outlet end of the dust collector 3 is connected to the gas inlet end of the primary heat exchanger 6. The primary heat exchanger 6 and the secondary heat exchanger 7 are respectively provided with a cold-end gas inlet and a cold-end gas outlet. The tertiary heat exchange system includes a cooling water circulation loop and an organic Rankine circulation loop. The cooling water circulation loop includes a cooling water flow path... The three-stage heat exchanger 10, the circulating pump 21, and the evaporator 22 are connected in sequence in the direction of movement. The organic Rankine loop includes the evaporator 22, the expander 23, the condenser 24, and the working fluid pump 25 connected in sequence. The first inlet end of the evaporator 22 is connected to the outlet end of the circulating pump 21, the first outlet end of the evaporator 22 is connected to the inlet end of the three-stage heat exchanger 10, the second outlet end of the evaporator 22 is connected to the inlet end of the expander 23, and the second inlet end of the evaporator 22 is connected to the outlet end of the working fluid pump 25. The three-stage heat exchanger 10 is also provided with a heating water inlet and a heating water outlet.

[0027] In some embodiments of this utility model, the dust collector 3 is an electrostatic precipitator or a metal bag filter dust collector. The primary heat exchanger 6 and the secondary heat exchanger 7 are plate heat exchangers or shell-and-tube heat exchangers. The tertiary heat exchanger 10 is a coiled tube heat exchanger.

[0028] Furthermore, the plate heat exchanger includes a hot-side inlet, a hot-side outlet, a cold-side inlet, a cold-side outlet, heat exchange plates, and a shell, with a metal outer casing covering the outside of the plate heat exchanger. Currently, traditional plate heat exchangers do not have an external shell, making them prone to gas leakage during heat exchange. This invention, however, by encasing the plate heat exchanger in a metal shell, prevents gas leakage in the event of a gas leak, ensuring the safety of high-pressure, high-volume gas heat exchange.

[0029] Furthermore, the gas inlet ends of the dust collector 3, the primary heat exchanger 6, and the tertiary heat exchanger 10 are respectively equipped with butterfly valve 1, butterfly valve 4, butterfly valve 8 and slide gate valve 2, slide gate valve 5, and slide gate valve 9; the gas outlet end of the tertiary heat exchanger 10 is respectively equipped with butterfly valve 11 and slide gate valve 12; butterfly valve 1, butterfly valve 4, butterfly valve 8, and butterfly valve 11 are used to regulate the flow and pressure of the medium inside the pipeline, and slide gate valve 2, slide gate valve 5, slide gate valve 9, and slide gate valve 12 are used to achieve safe shut-off of the medium inside the pipeline. The cold-end gas inlets of the primary heat exchanger 6 and the secondary heat exchanger 7 are respectively equipped with cold-end gas inlet valves 13 and 15, and cold-end gas outlets are respectively equipped with cold-end gas outlet valves 14 and 16, to control the opening and closing of the cold-end gas flow. The heating water inlet of the tertiary heat exchanger 10 is equipped with a heating water inlet valve 17, and the heating water outlet is equipped with a heating water outlet valve 18, to control the opening and closing of the heating water flow. The cooling water outlet of the tertiary heat exchanger 10 is equipped with a cooling water outlet valve 20, and the cooling water inlet is equipped with a cooling water inlet valve 19, to control the opening and closing of the cooling water flow.

[0030] This utility model's gas heat exchange device connects the high-temperature, high-pressure gas at the outlet of the vertical furnace 26 to the high-temperature dust collector 3, making the heat exchanger less prone to clogging. The primary heat exchanger 6 and secondary heat exchanger 7 preheat the low-temperature gas according to different process requirements; the tertiary heat exchanger 10 heats the heating water, cooling the inlet gas (above 450℃) to below 40℃. The tertiary heat exchanger 10 is also connected to a cooling water circulation loop and equipped with an expander 23 and a working fluid pump 25. When there are no heating users in summer, it can achieve Organic Rankine Cycle (ORC) power generation, not only meeting the process cooling gas requirements but also achieving a waste heat utilization efficiency of over 90%. The primary heat exchanger 6 and secondary heat exchanger 7 use plate heat exchangers. Plate heat exchangers have a large heat exchange area per unit volume, ensuring a small equipment size for large-volume gas heat exchange. Furthermore, the plate heat exchanger has an external shell, ensuring the safety of high-pressure, large-volume gas heat exchange. The three-stage heat exchanger 10 uses a coiled tube heat exchanger to heat the heating water. Since the coiled tube heat exchanger has a larger heat exchange area per unit volume compared to other types of heat exchangers, it can adapt to such large volume operating conditions and can improve the waste heat utilization efficiency of coal gas to a higher level.

[0031] In the gas heat exchange device of this invention, if heat exchange is directly performed between the gas and the organic Rankine loop, the working fluid in the three-stage heat exchanger 10 is organic. Since the cost of the organic working fluid is high and the volume of the three-stage heat exchanger 10 is large, the investment cost of the entire three-stage heat exchange system is high, and the switching between heating and power generation cannot be achieved. To reduce the investment cost of the three-stage heat exchange system and enable the switching between heating and power generation, this invention defines two circulation loops: a cooling water circulation loop and an organic Rankine loop. The high-temperature, high-pressure gas first undergoes preliminary heat exchange through the cooling water circulation loop, and then the organic working fluid and the cooling water heated by the gas exchange heat in the evaporator 22 through the organic Rankine loop. This reduces the overall investment cost of the circulation loop and improves economic efficiency.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model without departing from the spirit and scope of this technical solution, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A gas heat exchange device, characterized in that: The gas outlet end of the vertical shaft furnace (26) includes a dust collector (3), a primary heat exchanger (6), a secondary heat exchanger (7), and a tertiary heat exchange system connected in sequence. The gas inlet end of the dust collector (3) is connected to the gas outlet end of the vertical shaft furnace (26), and the gas outlet end of the dust collector (3) is connected to the gas inlet end of the primary heat exchanger (6). The primary heat exchanger (6) and the secondary heat exchanger (7) are respectively provided with a cold end gas inlet and a cold end gas outlet. The tertiary heat exchange system includes a cooling water circulation loop and an organic Rankine circulation loop. The cooling water circulation loop includes a tertiary heat exchanger (10) connected in sequence along the cooling water flow direction. The circulating pump (21) and the evaporator (22) are included in the organic Rankine circulation loop, which includes the evaporator (22), the expander (23), the condenser (24), and the working fluid pump (25) connected in sequence. The first inlet end of the evaporator (22) is connected to the outlet end of the circulating pump (21), the first outlet end of the evaporator (22) is connected to the inlet end of the three-stage heat exchanger (10), the second outlet end of the evaporator (22) is connected to the inlet end of the expander (23), and the second inlet end of the evaporator (22) is connected to the outlet end of the working fluid pump (25). The three-stage heat exchanger (10) is also provided with a heating water inlet and a heating water outlet.

2. The gas heat exchanger according to claim 1, characterized in that: The dust collector (3) is an electrostatic precipitator or a metal bag filter dust collector.

3. The gas heat exchanger according to claim 1, characterized in that: The primary heat exchanger (6) and the secondary heat exchanger (7) are plate heat exchangers.

4. The gas heat exchanger according to claim 3, characterized in that: The plate heat exchanger is externally encased in a metal shell.

5. The gas heat exchanger according to claim 1, characterized in that: The primary heat exchanger (6) and the secondary heat exchanger (7) are shell-and-tube heat exchangers.

6. The gas heat exchanger according to claim 1, characterized in that: The three-stage heat exchanger (10) is a coiled tube heat exchanger.

7. The gas heat exchanger according to claim 1, characterized in that: The gas inlet ends of the dust collector (3), the primary heat exchanger (6), and the tertiary heat exchanger (10) are respectively equipped with butterfly valves (1, 4, 8) and gate valves (2, 5, 9); the gas outlet end of the tertiary heat exchanger (10) is respectively equipped with butterfly valves (11) and gate valves (12); the butterfly valves (1, 4, 8, 11) are used to regulate the flow rate and pressure of the medium inside the pipeline, and the gate valves (2, 5, 9, 12) are used to achieve safe shut-off of the medium inside the pipeline.

8. The gas heat exchanger according to claim 1, characterized in that: The cold-end gas inlet valves (13, 15) of the first-stage heat exchanger (6) and the cold-end gas outlet valves (14, 16) of the second-stage heat exchanger (7) are respectively provided to control the opening and closing of the cold-end gas inlet and outlet; the heating water inlet valve (17) of the third-stage heat exchanger (10) is provided to the heating water inlet valve (17) and the heating water outlet valve (18) of the heating water outlet valve (18) are provided to control the opening and closing of the heating water inlet and outlet.

9. The gas heat exchanger according to claim 1, characterized in that: The three-stage heat exchanger (10) is equipped with a cooling water outlet valve (20) at the cooling water outlet end and a cooling water inlet valve (19) at the cooling water inlet end to control the opening and closing of the cooling water.

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