Wet quenching waste heat utilization and dust removal system and method

Abstract

A wet quenching waste heat utilization and dust removal system and method belong to the technical field of energy saving and environmental protection in coking industry. The system comprises a quenching water pool, a primary heat exchanger, a secondary heat exchanger, and a backwashing device. The quenching water pool stores quenching water. The primary heat exchanger is arranged in the quenching water pool. The secondary heat exchanger is arranged in a high-temperature steam rising channel of an upper part of a quenching tower. The water inlet end of the secondary heat exchanger is communicated with the water outlet end of the primary heat exchanger. The backwashing device is arranged at the secondary heat exchanger and is used for flushing the surface of the secondary heat exchanger. The water inlet end of the backwashing device is communicated with the water outlet end of the primary heat exchanger. The original internal space of the quenching tower is fully utilized. The secondary heat exchanger directly replaces the original dust removal device. The original tower structure does not need to be changed and sealed. External large fans and additional sealing pressure bearing facilities do not need to be added. The construction and transformation costs are greatly reduced. The occupied area is not additionally increased.

Description

Technical Field

[0001] This invention belongs to the field of energy conservation and environmental protection technology in the coking industry, specifically relating to a wet quenching waste heat utilization and dust removal system and method. Background Technology

[0002] Wet quenching is a quenching method that uses water as the quenching medium. A quenching car receives red-hot coke from the coke oven and transports it to the bottom of the quenching tower. Once inside the tower, multiple spray nozzles on the upper part of the quenching car spray quenching water. The water reacts instantly with the red-hot coke, generating a large amount of steam that rapidly cools the coke temperature to a safe range. The upper part of the quenching tower is equipped with a water mist collection device and a dust removal device to remove some pollutants from the steam. The cooled wastewater flows into a coke powder settling tank, where coke powder is separated, and the clear water is returned to the quenching water tank for recycling. However, this method does not recover the sensible heat contained in the red-hot coke (900℃~1100℃), which is instead lost as steam through water evaporation, resulting in a loss of 35%~45% of the total heat consumed in coking production. Producing one ton of coke requires 0.5 tons of water and generates a large amount of corrosive steam containing coke powder, phenols, cyanides, and sulfides, causing atmospheric dust and toxic gas emissions, polluting the surrounding environment, and corroding equipment.

[0003] Existing technologies employ various methods to treat the high-temperature steam generated during wet quenching, summarized as follows: (1) Seal the quenching tower. There is a quenching tower inlet and outlet at the bottom of the quenching tower. During the quenching process, a large amount of steam is generated instantaneously. It is extremely difficult to completely seal the quenching tower. Subsequent equipment will be subjected to the impact of high temperature and high pressure steam. (2) After the quenching tower is sealed, a high-temperature steam is drawn out of the quenching tower using an induced draft fan. Cooling devices, heat exchange devices, or dust removal devices are added to exchange heat and purify the high-temperature steam. This method requires a lot of large equipment, occupies a large area, has a high investment cost, and has a very low cost-effectiveness. (3) After the coke quenching tower is sealed, heat exchange is carried out inside the coke quenching tower. However, the heat exchange equipment is arranged in multiple layers, and the dust removal and heat exchange effects are not considered, resulting in low efficiency.

[0004] It is evident that existing technologies often require sealing the quenching tower, with the lower sides and top of the tower being open. According to the coking schedule, coke matures at intervals, and the quenching car, pulled by an electric locomotive, travels along the quenching track to deliver the coke into the quenching tower. During the quenching process, only the quenching car enters the tower, necessitating a device to isolate the electric locomotive, making complete sealing extremely difficult. Furthermore, the quenching process generates a large amount of high-temperature steam instantaneously, requiring large blower equipment to remove it. This type of equipment occupies a large area, involves high investment, and has extremely low cost-effectiveness.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] To address the technical problems of existing wet quenching waste heat recovery systems, such as the need for sealed quenching towers, high investment costs, large footprint, and difficulty in simultaneously achieving efficient heat exchange and dust removal, this invention provides a wet quenching waste heat utilization and dust removal system and method.

[0007] The first aspect of this invention provides a wet quenching waste heat utilization and dust removal system, comprising: The quenching water pool contains quenching water, which is warm water that has absorbed the heat from the quenching process. A primary heat exchanger is installed inside the quenching water tank; The secondary heat exchanger is installed in the high-temperature steam rising channel at the top of the quenching tower, and the water inlet of the secondary heat exchanger is connected to the water outlet of the primary heat exchanger; for the existing quenching tower, the secondary heat exchanger is installed at the original dust removal device at the top of the quenching tower. A backwashing device is installed at the secondary heat exchanger to rinse the surface of the secondary heat exchanger. The inlet of the backwashing device is connected to the outlet of the primary heat exchanger.

[0008] In some embodiments, a water storage tank is also included, the inlet of which is connected to the outlet of the secondary heat exchanger and the outlet of which leads to the user end.

[0009] In some embodiments, the secondary heat exchanger includes multiple layers of staggered heat exchanger pipes, each layer of heat exchanger pipes being arranged symmetrically at an angle α of 30° to 45° with respect to the horizontal plane.

[0010] In some embodiments, the outer wall surface of the heat exchanger pipe is provided with ribs along the circumferential direction.

[0011] In some embodiments, the backflushing device includes an upper flushing pipe disposed above the secondary heat exchanger and a lower flushing pipe disposed below the secondary heat exchanger.

[0012] In some embodiments, both the upper flushing pipe and the lower flushing pipe are arranged at an angle α to the horizontal plane and are arranged parallel to the secondary heat exchanger.

[0013] In some embodiments, piping and valves are also included, said piping and valves being arranged as follows: The water inlet transport section includes a water supply pipeline, on which a water supply gate valve and a water pump as a fluid drive device are connected in series. A check valve and a main control gate valve are connected in series downstream of the outlet of the water pump. Downstream of the main control gate valve, the preheating and bypass heat exchange section is divided into two parallel fluid branches for the makeup water inlet pipeline. The first branch flows through the quenching water tank and is connected in series with the front gate valve, the primary heat exchanger, and the rear gate valve. The second branch forms a bypass pipe, on which a maintenance gate valve is installed. In the fluid reversing and distribution section, the first branch and the second branch merge downstream and are connected together to the fluid inlet end of the three-way valve; In the terminal feed section, the three-way valve has a first fluid outlet and a second fluid outlet, wherein the first fluid outlet is connected to the water inlet of the secondary heat exchanger, and the second fluid outlet is connected to the flushing manifold to feed flushing water to the backwashing device.

[0014] In some implementations, the following are included: The self-circulating pipe has two ends connected to the water storage tank and the water inlet of the water pump, respectively, and the self-circulating pipe is equipped with a self-circulating pipe gate valve. An external circulation pipe is provided, with its two ends connected to the user end and the water inlet end of the water pump, respectively. An external circulation pipe gate valve is provided on the external circulation pipe.

[0015] A second aspect of the present invention provides a method for utilizing waste heat from wet quenching and dust removal using the above-described system, comprising the following steps: Preheating stage: The medium (such as water) is pumped into the primary heat exchanger and preheated with the coke quenching water in the quenching water tank. The preheated medium is then sent into the secondary heat exchanger through a three-way valve. Secondary heat exchange in-situ dust removal and purification stage: The high-temperature steam generated by wet quenching rises in the quenching tower and passes through the secondary heat exchanger. The steam cools down and condenses into condensate on the surface of the secondary heat exchanger, while dissolving the toxic gases in the steam. The condensate falls into the bottom of the quenching tower and finally flows back to the quenching water pool. The medium in the secondary heat exchanger absorbs heat and enters the water storage tank. Backwashing stage: During the coke quenching interval, switch the three-way valve to allow the medium that has been preheated by the primary heat exchanger to enter the backwashing device, and spray and wash the surface of the secondary heat exchanger from both the top and bottom ends simultaneously.

[0016] In some implementations, a cyclic heating step is also included: When the water temperature in the storage tank does not meet the user's needs, close the water replenishment gate valve and open the self-circulation pipe gate valve so that the water in the storage tank flows back to the water pump through the self-circulation pipe for recirculation and heating. Alternatively, when using a recyclable heat medium at the user end, close the replenishment water gate valve and open the external circulation pipe gate valve to allow the return water to flow back to the water pump for heat exchange via the external circulation pipe.

[0017] Compared with existing technologies, the technical effects achieved by this invention are as follows: (1) This invention makes full use of the original internal space of the quenching tower and directly replaces the original dust removal device with a secondary heat exchanger. There is no need to change or seal the original tower structure, nor is there a need to add external large fans and additional sealing and pressure-bearing facilities. This greatly reduces the construction and renovation costs and does not increase the floor space.

[0018] (2) This invention breaks through the limitations of the prior art in solving single-point problems in isolation (such as only considering heat exchange or only considering dust removal). It highly integrates the cold medium preheating device, the coke quenching steam heat exchange device, the backwashing device, the recycling device, and the fault repair bypass device into the same fluid pipeline system. Although it integrates five complex functions, through the clever reuse of electric three-way valves, parallel pipelines, and in-situ replacement design, the entire system does not require the addition of expensive large-scale power fans, nor does it require additional expansion of the plant or sealing of the coke quenching tower. With the minimum footprint and pipeline modification cost, it solves the five major industry pain points of whitening (steam removal), dust removal, detoxification, energy saving, and water saving, and has extremely high practicality.

[0019] (3) The heat medium that has been preheated once in the quenching water tank is introduced as the flushing water. Because the high temperature water has lower viscosity, better fluidity, and stronger turbulence, it can dissolve and wash away the coke powder and impurities attached to the secondary heat exchanger more quickly under the same flow rate and pressure. The ingenious combination of 120° fins and 30°~45° tilt angle of the secondary heat exchanger causes the liquid film to break into small droplets under the high-speed steam shear of the bottom fins, which greatly increases the gas-liquid contact area, strengthens heat exchange, and washes and captures toxic gases (such as phenols and cyanides) and dust. The top fins effectively prevent the accumulation of continuous liquid film and prevent water blockage.

[0020] (4) Two sets of logics, self-circulation and external circulation, are introduced to flexibly adjust the water temperature of the water storage tank according to the needs of the user, so as to save the amount of cold replenishment water to the greatest extent. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a wet quenching waste heat utilization and dust removal process provided in an embodiment of the present invention; Figure 2 for Figure 1 Schematic diagram of the secondary heat exchanger layout (partial enlargement, A); Figure 3 for Figure 2 A schematic diagram of the secondary heat exchanger and the upper flushing pipe arrangement from direction B; Figure 4 for Figure 2A schematic diagram of the arrangement of the secondary heat exchanger and the lower flushing pipe from direction C; Figure 5 for Figure 3 Schematic diagram of the DD cross-section (flushing range of the upper flushing pipe); Figure 6 for Figure 4 Schematic diagram of the DD cross-section (flushing range of the lower flushing pipe); In the picture: 1. Makeup water gate valve; 2. Water pump; 3. Check valve; 4. Main control gate valve; 5. Makeup water inlet pipe; 6. Front gate valve; 7. Primary heat exchanger; 8. Rear gate valve; 9. Three-way valve; 10. Secondary heat exchanger; 11. Water storage tank; 12. Bypass pipe; 13. Maintenance gate valve; 14. Self-circulation pipe gate valve; 15. Self-circulation pipe; 16. Flushing main pipe; 17. Lower flushing pipe; 18. Upper flushing pipe; 19. External circulation pipe gate valve; 20. External circulation pipe; 21. Fin. Detailed Implementation

[0022] The technical solution of the present invention will be described below with reference to the accompanying drawings and specific embodiments. It should be understood that one or more steps mentioned in the present invention do not preclude the existence of other methods and steps before or after the combined steps, or that other methods and steps may be inserted between these explicitly mentioned steps. It should also be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise stated, the numbering of each method step is only for the purpose of identifying each method step, and not for limiting the order of each method or limiting the scope of the invention. Changes or adjustments to their relative relationships, without substantial changes to the technical content, can also be considered within the scope of the present invention.

[0023] The raw materials and instruments used in the examples are not subject to any specific restrictions on their source; they can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0024] like Figure 1 , Figure 2 As shown, a wet quenching waste heat utilization and dust removal system includes: The quenching water tank contains warm water that has absorbed the heat from the quenching process. A primary heat exchanger 7 is installed inside the quenching water tank; The secondary heat exchanger 10 is installed in the high-temperature steam rising channel at the top of the quenching tower. The water inlet of the secondary heat exchanger 10 is connected to the water outlet of the primary heat exchanger 7. For existing quenching towers, the secondary heat exchanger is installed at the original dust removal device at the top of the quenching tower. A backwashing device is installed at the secondary heat exchanger 10 to rinse the surface of the secondary heat exchanger 10. The inlet of the backwashing device is connected to the outlet of the primary heat exchanger 7. The water storage tank 11 has its inlet connected to the outlet of the secondary heat exchanger 10, and its outlet connected to the user end. The external cold medium is preheated by the primary heat exchanger 7 and the warm water in the quenching water tank, and then enters the secondary heat exchanger 10 to exchange heat with the quenching steam. The heat medium after heat exchange flows into the water storage tank 11.

[0025] It also includes piping and valves, which are arranged as follows: The water inlet transport section includes a water supply inlet pipeline 5, on which a water supply gate valve 1 and a water pump 2 as a fluid drive device are connected in series. A check valve 3 and a main control gate valve 4 are connected in series downstream of the outlet of the water pump 2. Downstream of the main control gate valve 4, the preheating and bypass heat exchange section is divided into two parallel fluid branches in the makeup water inlet pipe 5. The first branch flows through the quenching water tank and is connected in series with the front gate valve 6, the primary heat exchanger 7, and the rear gate valve 8. The second branch forms a bypass pipe 12, on which a maintenance gate valve 13 is installed. In the fluid reversing and distribution section, the first branch and the second branch merge downstream and are connected together to the fluid inlet end of the three-way valve 9; In the terminal feed section, the three-way valve 9 has a first fluid outlet and a second fluid outlet, wherein the first fluid outlet is connected to the water inlet of the secondary heat exchanger 10, and the second fluid outlet is connected to the flushing manifold 16 to feed flushing water to the backwashing device.

[0026] In one embodiment, the secondary heat exchanger 10 is formed by bending pipes and consists of multiple layers of pipes, including multiple layers of heat exchanger pipes arranged in a staggered pattern. Figure 2 The diagram shows two layers, but multiple layers can be arranged according to actual conditions. The heat exchanger pipes in each layer are arranged symmetrically at an angle α to the horizontal. α is set between 30° and 45°. If α is too small, liquid accumulation and blockage will occur, forming water plugs. If α is too large, the heat exchanger pipes will be too long, the vertical dimensions will be too large, and installation will be inconvenient. The spacing between the heat exchanger pipes is D, and the upper and lower layers of heat exchangers are arranged alternately, as shown in the diagram. Figure 4 As shown, the outermost pipe of the lower heat exchanger is H away from the quenching tower, as... Figure 3 As shown, the outermost pipe of the upper heat exchanger is H+D / 2 away from the quenching tower. The pipes of the upper and lower heat exchangers do not overlap horizontally, and the spacing is D / 2. To improve heat exchange and dust removal efficiency, ribs 21 are provided circumferentially on the outer wall of the pipes of the upper and lower heat exchangers, as shown. Figure 5 , 6 As shown, the fins are evenly distributed at 120° intervals, dividing the surface of the heat exchanger pipes into three regions: a, b, and c. The heat exchanger is divided into multiple sections for easy transportation and installation, and the connections can be made using flanges or welding.

[0027] At the start of quenching, the quenching steam condenses into water upon encountering the secondary heat exchanger. An initial continuous liquid film forms on the lower outer wall of the heat exchanger pipes and the surface of the two lower fins. However, at this time, the quenching steam velocity is high, and the liquid film is sheared and torn by the upward steam, breaking into a large number of fine droplets. Some of these droplets are carried upward by the airflow, while the remaining liquid water flows away along the curved wall under gravity. This enhances liquid film heat transfer and increases heat exchange efficiency. The fins at the top of the heat exchanger pipes serve to separate the two water streams and prevent the accumulation of a continuous liquid film at the top. The oblique fin arrangement of the heat exchanger not only increases the heat transfer efficiency on the outer surface of the heat exchanger pipes but also increases the length of the heat exchanger pipes, thereby increasing the heat exchange and dust removal area.

[0028] The secondary heat exchanger replaces the dust removal device in the original quenching tower, which not only removes dust but also utilizes waste heat. This device can be used not only in new projects but also in the renovation of existing projects. It does not change the original structure of the quenching tower and is simple in terms of equipment, small in area, and low in investment.

[0029] In one embodiment, the backwashing device includes an upper flushing pipe 18 disposed above the secondary heat exchanger 10 and a lower flushing pipe 17 disposed below the secondary heat exchanger 10.

[0030] like Figure 5 As shown, the upper flushing pipe 18 is arranged on the upper layer of the heat exchanger, coinciding longitudinally with the upper secondary heat exchanger and forming a certain angle α with the horizontal (the same angle as the secondary heat exchanger). Because there are fewer impurities accumulating above the heat exchanger, the spray pipes are spaced apart, with the number of spray pipes being half the number of pipes in the upper secondary heat exchanger. The lower part of the flushing pipes has evenly spaced openings, spraying areas a and b of the upper heat exchanger pipes and areas a and b of the lower heat exchanger pipes. Areas a and b of the lower heat exchanger pipes are further flushed by the water flowing from the lower flushing pipes into area c of the upper heat exchanger pipes, and the sprayed water from areas a and b of the upper heat exchanger pipes also flows into areas a and b of the lower heat exchanger pipes.

[0031] like Figure 6 As shown, the lower flushing pipe 17 is arranged in the lower layer of the secondary heat exchanger, coinciding with the longitudinal direction of the lower secondary heat exchanger and forming a certain angle α with the horizontal (the same angle as the secondary heat exchanger). Because the quenching steam in the quenching tower rises from the bottom, it mainly contacts the pipes and fins in area c of the heat exchanger, resulting in a greater accumulation of impurities. The spray pipes are densely arranged, with the number of spray pipes matching the number of pipes in the upper secondary heat exchanger. The flushing pipes have evenly spaced openings at the top, spraying area c of both the lower and upper heat exchanger pipes.

[0032] The number of layers in the secondary heat exchanger can be set according to local environmental protection requirements. When the number of heat exchanger layers increases, the number of flushing pipe layers also increases accordingly to ensure that the entire surface of the heat exchanger can be flushed.

[0033] In one embodiment, the wet quenching waste heat utilization and dust removal system further includes: The self-circulation pipe 15 has its two ends connected to the water storage tank 11 and the water inlet of the water pump 2, respectively. The self-circulation pipe 15 is equipped with a self-circulation pipe gate valve 14. An external circulation pipe 20 is provided with an external circulation pipe gate valve 19 on its two ends, which are respectively connected to the user end and the water inlet end of the water pump 2.

[0034] The above-mentioned wet quenching waste heat utilization and dust removal method includes the following steps: Preheating stage: The cold medium is pumped into the primary heat exchanger 7 and preheated by the quenching water in the quenching water pool. The preheated medium is then sent into the secondary heat exchanger 10 through the three-way valve 9. Secondary heat exchange in-situ dust removal and purification stage: The high-temperature steam generated by wet quenching rises in the quenching tower and passes through the secondary heat exchanger 10. The steam cools down and condenses into condensate on the surface of the secondary heat exchanger, while dissolving the toxic gases in the steam. The condensate falls to the bottom of the quenching tower and finally flows back to the quenching water pool. After the medium in the secondary heat exchanger 10 absorbs heat, it enters the water storage tank 11. Backwashing stage: During the coke quenching interval, switch the three-way valve 9 to allow the hot medium that has been preheated by the primary heat exchanger 7 to enter the backwashing device and spray and wash the surface of the secondary heat exchanger 10 from both the top and bottom ends simultaneously. Circulating heating steps: Self-circulation mode: When the water temperature in the water storage tank 11 does not meet the user's needs, close the water replenishment gate valve 1 and open the self-circulation pipe gate valve 14 so that the water in the water storage tank 11 flows back to the water pump 2 through the self-circulation pipe 15 for recirculation and heating. External circulation mode: When using the user-end recyclable heat medium, close the replenishment water gate valve 1 and open the external circulation pipe gate valve 19, so that the return water flows back to the water pump 2 through the external circulation pipe 20 for heat exchange.

[0035] The two circulation modes greatly reduce the need for external replenishment of pure water.

[0036] In one embodiment, the process flow of the present invention is as follows: During normal operation of the coke quenching steam heat exchanger: the coke quenching car receives red-hot coke from the coke oven and transports it to the bottom of the quenching tower. After the coke enters the quenching tower, multiple sets of spray heads installed on the upper part of the coke quenching car spray quenching water. The water generates a large amount of steam instantly upon contact with the red-hot coke. The large amount of high-temperature steam generated in this transient process rises naturally inside the tower and passes through the staggered secondary heat exchanger 10 pipe network. The steam undergoes a violent heat exchange with the cold medium inside the pipes. After releasing latent heat, the steam quickly condenses into liquid water on the outer wall of the heat exchange tube 5, causing the originally huge steam volume to decrease drastically due to phase change, thereby eliminating the visible "white smoke" emitted into the atmosphere from a physical source. The 120° fins distributed circumferentially on the outer wall of the heat exchange pipes greatly increase the gas-liquid contact surface area, and the steam condenses on the fins and pipe walls to form a continuous condensate film. Under the shearing action of the rapidly rising steam, a large number of fine droplets are formed, constructing a dense spatial washing water curtain. The fine coke powder carried in the steam is adhered and captured by the moist liquid film. At the same time, toxic gases such as phenols, cyanides and sulfides contained in the steam are rapidly dissolved in the condensate film, realizing gas-liquid phase mass transfer detoxification. Since the secondary heat exchanger 10 is arranged at an angle of 30°~45°, the polluted condensate containing dust and dissolved toxic gases will not accumulate in the airflow channel to form a water block. Instead, it flows smoothly down the inclined surface of the heat exchange tube and the bottom fins, and finally collects in the form of drips into the sedimentation tank at the bottom of the quenching tower. The harmful substances enter the sewage sedimentation and subsequent biochemical treatment system in the plant area with the water flow, thereby blocking the unorganized emission of toxic gases and dust into the surrounding atmosphere. At this time, the quenching water supply enters the variable frequency water pump 2 through the water supply gate valve 1. The variable frequency water pump 2 adjusts its flow rate to the maximum. The water pump outlet check valve 3 and the main control gate valve 4 are both open. The supply water enters the cold medium preheating device. The maintenance gate valve 13 is closed, while the front gate valve 6 and the rear gate valve 8 are open. The cold medium exchanges heat with the quenching water in the quenching water tank in the primary heat exchanger 7. After passing through the preheating device, the cold medium enters the secondary heat exchanger 10 (quenching steam heat exchange device, located at the original dust removal device) through the three-way valve 9 (electric three-way valve). After exchanging heat with the quenching steam, it enters the water storage tank 11, and the hot medium is supplied to the user. When quenching is completed, the quenching car drives out of the quenching tower, the variable frequency water pump 2 reduces its flow rate, and the valve status remains unchanged.

[0037] Cold medium preheating device: Before the cold medium enters the quenching tower and exchanges heat with the quenching steam, it is preheated in the quenching water tank. The temperature of the quenching water in the tank can reach up to 80℃. This heat is recovered and reduces the temperature of the quenching spray water, thus reducing the flow rate of the spray water and saving energy. In traditional wet quenching, the hot water (about 80℃) after spraying the red-hot coke flows directly back to the quenching water tank and then dissipates heat naturally in the tank, which is a waste. This invention adds a heat exchanger to the quenching water tank to fully absorb the heat from the 80℃ hot water, so the water in the quenching water tank naturally cools down (for example, to 50℃). In actual operation, the water is recycled, and the water in the quenching water tank is pumped back up by the quenching water pump to spray the next batch of red-hot coke. Therefore, the water used for spraying the next batch is cooled down. It is evident that this invention absorbs the sensible heat of the quenching water return from the quenching water tank through a primary heat exchanger, achieving not only initial recovery of low-grade waste heat but also increasing the endothermic value per unit mass of quenching water by lowering the temperature of the quenching spray water in the next cycle. This configuration significantly reduces the rated flow requirement of the quenching water pump, thereby reducing power consumption and decreasing the total amount of high-temperature steam generated at the source.

[0038] Backwashing Device: After multiple quenching cycles in the quenching tower, impurities accumulate on the secondary heat exchanger 10, requiring backwashing to prevent impact on heat exchange and dust removal efficiency. During the quenching interval, the three-way valve 9 opens the passage to the main flushing pipe 16 and closes the passage to the secondary heat exchanger 10. Flushing water enters the upper flushing pipe 18 and the lower flushing pipe 17, simultaneously flushing the secondary heat exchanger 10 from both the top and bottom. The flushing water is selected from the medium that has undergone heat exchange with the quenching water in the quenching pool at approximately 80℃. At this temperature, the flushing water has a higher temperature than the makeup water, lower viscosity, and better fluidity and stronger turbulence under the same flow rate and pressure. Impurities on the dust collector dissolve and are washed away more quickly under the action of the higher-temperature flushing water. The flushing pipes are arranged in upper and lower layers, with a reasonable layout, enabling rapid and comprehensive flushing of impurities on the secondary heat exchanger. After flushing is complete, switch the three-way valve 9 to open the passage to the secondary heat exchanger 10 and close the passage to the flushing main pipe 16.

[0039] Recycling Device: The recycling device includes self-circulation and external circulation. When the water temperature in the storage tank 11 cannot meet the user's needs, the self-circulation device is used. The self-circulation pipe gate valve 14 is opened, and the makeup water gate valve 1 is closed, allowing the water in the storage tank 11 to flow into the inlet of the water pump 2 through the self-circulation pipe 15 for reheating until the temperature in the storage tank meets the requirements. When the medium is sent to the user end for heat exchange and can be recovered, the external circulation pipe gate valve 19 is opened, and the makeup water gate valve 1 is closed, allowing the circulating water to flow into the inlet of the water pump 2 through the external circulation pipe 20, reducing the amount of makeup water used.

[0040] Troubleshooting and Repair Device: When the primary heat exchanger malfunctions or requires maintenance, close the front gate valve 6 and the rear gate valve 8, and open the maintenance gate valve 13. The cold medium is then sent to the heat exchanger through the bypass pipe 12. After the fault is resolved, the valves are returned to their original state. When the secondary dust collector malfunctions or requires maintenance, shut off the water pump 2, quickly locate the fault point in the secondary dust collector, and perform repairs. If the problem cannot be resolved promptly, due to the multi-section design of the heat exchanger, the damaged section of the heat exchanger can be removed and replaced with a new one, and the water pump can be restored to operation.

[0041] Throughout the process, the condensate generated when the quenching steam comes into contact with the secondary heat exchanger and the flushing water used to rinse the secondary heat exchanger both fall to the bottom of the quenching tower. After a series of sedimentations, they eventually enter the quenching water pool and continue to exchange heat with the primary heat exchanger.

[0042] The wet quenching waste heat utilization and dust removal system provided by this invention integrates a cold medium preheating device, a quenching steam heat exchange device, a backwashing device, a recycling device, and a fault repair device into a single unit. It completes the waste heat utilization of high-temperature steam in wet quenching, condensate collection, and self-washing dust removal. It fully considers various usage scenarios and features simple equipment, small footprint, and low investment.

[0043] This invention eliminates the need for a sealed quenching tower, does not require additional facilities for a sealed quenching tower, and the quenching tower does not need to withstand additional pressure.

[0044] This invention uses a primary heat exchanger to preheat the cold medium in the quenching water tank. The temperature of the quenching water in the quenching water tank can reach up to 80°C. This heat is recovered and the temperature of the quenching spray water is reduced, which can reduce the flow rate of the quenching spray water and save energy.

[0045] This invention designs a secondary heat exchanger suitable for coke quenching towers. The heat exchange tubes are finned and arranged at an angle to enhance heat exchange and dust removal efficiency. The secondary heat exchanger replaces the original dust removal device in the coke quenching tower, not only removing dust but also recovering heat from the quenching steam. This invention does not alter the original coke quenching tower structure, and this device can be used not only in new projects but also in the retrofitting of existing projects.

[0046] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A wet quenching waste heat utilization and dust removal system, characterized in that, include: The quenching water pool contains quenching water. A primary heat exchanger is installed inside the quenching water tank; A secondary heat exchanger is installed in the high-temperature steam rising channel at the top of the quenching tower, and the water inlet of the secondary heat exchanger is connected to the water outlet of the primary heat exchanger. A backwashing device is installed at the secondary heat exchanger to rinse the surface of the secondary heat exchanger. The inlet of the backwashing device is connected to the outlet of the primary heat exchanger.

2. The wet quenching waste heat utilization and dust removal system according to claim 1, characterized in that, It also includes a water storage tank, the inlet of which is connected to the outlet of the secondary heat exchanger, and the outlet of which leads to the user end.

3. The wet quenching waste heat utilization and dust removal system according to claim 1, characterized in that, The secondary heat exchanger includes multiple layers of staggered heat exchanger pipes, each layer of which is arranged symmetrically at an angle α of 30° to 45° with respect to the horizontal plane.

4. The wet quenching waste heat utilization and dust removal system according to claim 3, characterized in that, The outer wall of the heat exchanger pipe is provided with ribs along the circumference.

5. The wet quenching waste heat utilization and dust removal system according to claim 4, characterized in that, The backwashing device includes an upper flushing pipe disposed above the secondary heat exchanger and a lower flushing pipe disposed below the secondary heat exchanger.

6. The wet quenching waste heat utilization and dust removal system according to claim 5, characterized in that, Both the upper flushing pipe and the lower flushing pipe are arranged at an angle α to the horizontal plane and are parallel to the secondary heat exchanger.

7. The wet quenching waste heat utilization and dust removal system according to claim 2, characterized in that, It also includes piping and valves, which are arranged as follows: The water inlet transport section includes a water supply pipeline, on which a water supply gate valve and a water pump as a fluid drive device are connected in series. A check valve and a main control gate valve are connected in series downstream of the outlet of the water pump. Downstream of the main control gate valve, the preheating and bypass heat exchange section is divided into two parallel fluid branches for the makeup water inlet pipeline. The first branch flows through the quenching water tank and is connected in series with the front gate valve, the primary heat exchanger, and the rear gate valve. The second branch forms a bypass pipe, on which a maintenance gate valve is installed. In the fluid reversing and distribution section, the first branch and the second branch merge downstream and are connected together to the fluid inlet end of the three-way valve; In the terminal feed section, the three-way valve has a first fluid outlet and a second fluid outlet, wherein the first fluid outlet is connected to the water inlet of the secondary heat exchanger, and the second fluid outlet is connected to the flushing manifold to feed flushing water to the backwashing device.

8. The wet quenching waste heat utilization and dust removal system according to claim 7, characterized in that, Also includes: The self-circulating pipe has two ends connected to the water storage tank and the water inlet of the water pump, respectively, and the self-circulating pipe is equipped with a self-circulating pipe gate valve. An external circulation pipe is provided, with its two ends connected to the user end and the water inlet end of the water pump, respectively. An external circulation pipe gate valve is provided on the external circulation pipe.

9. A method for utilizing waste heat from wet quenching and dust removal using the system described in any one of claims 1-8, characterized in that, Includes the following steps: Preheating stage: The medium is pumped into the primary heat exchanger and preheated using the quenching water in the quenching water tank. The preheated medium is then sent into the secondary heat exchanger through a three-way valve. Secondary heat exchange in-situ dust removal and purification stage: The high-temperature steam generated by wet quenching rises in the quenching tower and passes through the secondary heat exchanger. The steam cools down and condenses into condensate on the surface of the secondary heat exchanger, while dissolving the toxic gases in the steam. The condensate falls into the bottom of the quenching tower and finally flows back to the quenching water pool. The medium in the secondary heat exchanger absorbs heat and enters the water storage tank. Backwashing stage: During the coke quenching interval, switch the three-way valve to allow the medium that has been preheated by the primary heat exchanger to enter the backwashing device, and spray and wash the surface of the secondary heat exchanger from both the top and bottom ends simultaneously.

10. The method according to claim 9, characterized in that, It also includes a circulating heating step: When the water temperature in the storage tank does not meet the user's needs, close the water replenishment gate valve and open the self-circulation pipe gate valve so that the water in the storage tank flows back to the water pump through the self-circulation pipe for recirculation and heating. Alternatively, when using a recyclable heat medium at the user end, close the replenishment water gate valve and open the external circulation pipe gate valve to allow the return water to flow back to the water pump for heat exchange via the external circulation pipe.

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