High-temperature tail gas waste heat recovery and mucus removal device

Abstract

The application relates to the technical field of high-temperature tail gas waste heat recycling, in particular to a high-temperature tail gas waste heat recycling and mucus removing device, which comprises a scraped wall heat exchanger, a scraped plate condenser and a vacuum pump mechanism. High-temperature tail gas enters the scraped wall heat exchanger arranged horizontally, a rotating shaft with a scraper is arranged in the scraped wall heat exchanger, a heat medium jacket is arranged outside the scraped wall heat exchanger, and mucus is collected at the bottom. The medium-temperature tail gas after cooling enters the scraped plate condenser arranged horizontally, a rotating shaft with a scraper is arranged in the scraped plate condenser, a liquid seal groove, a residue filter and a circulating pump are connected to the bottom, the circulating pump sends glycol to the spray nozzles at the top of a vertical cylinder through a first heat exchanger to cool the tail gas, and the vacuum pump mechanism is connected to the top of the vertical cylinder to discharge the incondensable tail gas. The high-temperature tail gas waste heat recycling and mucus removing device can capture the mucus generated in the tail gas heat exchange and cooling process, so that the blockage and frequent cleaning are avoided, and the equipment operation stability is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of high-temperature exhaust gas waste heat recovery technology, and in particular to a high-temperature exhaust gas waste heat recovery and desliming device. Background Technology

[0002] During the polycondensation reaction in polyester production, high-temperature exhaust gas at 200-300°C is generated. During cooling, this exhaust gas releases high-viscosity, condensable liquids such as oligomers. When conventional heat exchangers are used for heat recovery, this viscous liquid adheres to the inner wall of the heat exchanger, rapidly forming scale, coke, or even blockages. This leads to a sharp decline in heat exchange efficiency, requiring frequent shutdowns for cleaning, resulting in significant waste of heat and hindering continuous heat recovery.

[0003] Currently, most high-temperature exhaust gases from the polycondensation reaction in polyester production are cooled by direct spraying. While this can alleviate blockage, it does not effectively recover heat, resulting in low heat recovery and utilization rates. Summary of the Invention

[0004] In order to overcome the above-mentioned technical deficiencies, the present invention provides a high-temperature exhaust gas waste heat recovery and sludge removal device, which can realize the self-cleaning of the inner wall of the heat exchanger during the heat exchange process, so as to achieve the integration of exhaust gas cooling, sludge collection and waste heat recovery.

[0005] This invention discloses a high-temperature exhaust gas waste heat recovery and sludge removal device, including a scraped wall heat exchanger, a scraped plate condenser, and a vacuum pump mechanism; The scraped wall heat exchanger includes a cylindrical body with a hollow cylindrical cavity inside. A jacket is provided on the outside of the cylindrical body, and a heat medium inlet pipe and a heat medium outlet pipe are provided on the jacket. A high-temperature exhaust gas pipe is provided on the cylindrical body and communicates with the inside of the cylindrical body. A medium-temperature exhaust gas pipe is provided on the cylindrical body and is connected to a scraped plate condenser. The cylindrical body is horizontally placed, and a rotating shaft is horizontally placed inside the cylindrical body. One end of the rotating shaft extends to the outside of the cylindrical body. A first drive motor is provided outside the cylindrical body and is connected to the rotating shaft. A scraper is provided on the rotating shaft inside the cylindrical body and is in contact with the inner wall of the cylindrical body. A hopper is provided at the bottom of one end of the cylindrical body for collecting and discharging sludge. The scraper condenser includes a horizontally placed cylindrical body, which is hollow inside and closed at both ends. The intermediate-temperature exhaust gas pipe is connected to the cylindrical body. A vertical cylinder is located at one end of the cylindrical body, with its bottom connected to the cylindrical body and its top closed. A rotating shaft is rotatably mounted inside the cylindrical body, with one end extending to the outside of the cylindrical body. A second drive motor is located outside the cylindrical body and is connected to the rotating shaft. A scraper is provided on the rotating shaft. The scraper is in contact with the inner wall of the cylindrical body. A liquid seal tank is connected to the bottom of the cylindrical body through a pipe. A residue filter is connected to the bottom of the liquid seal tank through a pipe. The output port of the residue filter is connected to a circulating pump through a pipe. The outlet of the circulating pump is connected to a first heat exchanger. A spray nozzle is provided at the top inside the vertical cylinder. The first heat exchanger is connected to the top of the vertical cylinder through a pipe and extends into the vertical cylinder to connect with the spray nozzle. A refrigerant pipe is provided on the first heat exchanger. The vacuum pump mechanism is connected to the top of the vertical cylinder and delivers the exhaust gas outward.

[0006] A precooler is vertically mounted on the high-temperature exhaust gas pipeline before it enters the scraped wall heat exchanger. The precooler is hollow inside, and the high-temperature exhaust gas pipeline is connected to the inside of the precooler. The top of the precooler is connected to the interior of the columnar body of the scraped wall heat exchanger through a pipeline. An atomizing nozzle is installed at the upper part of the interior of the precooler, and the pipeline of the atomizing nozzle is connected to the outside of the precooler. A collection pipe is installed at the bottom of the precooler.

[0007] Ethylene glycol tubes are embedded in the inner wall of the columnar body of the scraped heat exchanger, and the ethylene glycol tubes extend to the outside of the columnar body. Spray holes are opened on the ethylene glycol tubes inside the columnar body.

[0008] A spray head is installed inside the columnar body at the end away from the night collection hopper. An ethylene glycol tube is connected to the spray head and extends to the outside of the columnar body. The spray head is located at the lower end inside the columnar body and faces the night collection hopper.

[0009] A circulation pump is connected to the bottom of the liquid seal tank via a pipe. The outlet of the circulation pump is connected to another first heat exchanger, which is also connected to the spray nozzles. A refrigerant pipe is also installed on the first heat exchanger.

[0010] The high-temperature exhaust gas waste heat recovery and sludge removal device obtained by the present invention adopts a scraped wall heat exchanger and a scraped plate condenser, which can capture the sludge generated during the exhaust gas heat exchange and cooling process, thereby avoiding blockage and frequent cleaning, and greatly improving the operational stability of the equipment. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the scraped wall heat exchanger of the present invention. Detailed Implementation

[0012] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below. Example 1:

[0013] like Figure 1 As shown, the present invention discloses a high-temperature exhaust gas waste heat recovery and desliming device, including a scraped wall heat exchanger 2, a scraped plate condenser 4, and a vacuum pump mechanism 9. The scraped wall heat exchanger 2 includes a cylindrical body 21 with a hollow cylindrical cavity inside. A jacket 24 is provided on the outside of the cylindrical body 21, and a heat medium inlet pipe and a heat medium outlet pipe are provided on the jacket 24. A high-temperature exhaust gas pipe 1 is provided on the cylindrical body 21 and communicates with the inside of the cylindrical body 21. A medium-temperature exhaust gas pipe 3 is provided on the cylindrical body 21 and is connected to a scraped plate condenser 4. The cylindrical body 21 is horizontally placed, and a rotating shaft is horizontally placed inside the cylindrical body 21. One end of the rotating shaft extends to the outside of the cylindrical body 21. A first drive motor 22 is provided on the outside of the cylindrical body 21 and is connected to the rotating shaft. A scraper 23 is provided on the rotating shaft inside the cylindrical body 21 and fits against the inner wall of the cylindrical body 21. A sludge collection hopper 25 is provided at the bottom of one end of the cylindrical body 21 for collecting and discharging sludge. The scraper condenser 4 includes a horizontally placed cylindrical body 41, which is hollow inside and closed at both ends. The medium-temperature exhaust gas pipe 3 is connected to the cylindrical body 41. A vertical cylinder 44 is provided at one end of the cylindrical body 41, with its bottom connected to the cylindrical body 41 and its top closed. A rotating shaft is rotatably arranged inside the cylindrical body 41, with one end extending to the outside of the cylindrical body 41. A second drive motor 42 is provided outside the cylindrical body 41 and is connected to the rotating shaft. A scraper 43 is provided on the internal rotating shaft. The scraper 43 is in contact with the inner wall of the cylindrical body 41. A liquid seal tank 5 is connected to the bottom of the cylindrical body 41 through a pipe. A residue filter 6 is connected to the bottom of the liquid seal tank 5 through a pipe. The output port of the residue filter 6 is connected to a circulation pump 7 through a pipe. The outlet of the circulation pump 7 is connected to a first heat exchanger 8. A spray nozzle 45 is provided at the top inside the vertical cylinder 44. The first heat exchanger 8 is connected to the top of the vertical cylinder 44 through a pipe and extends into the vertical cylinder 44 to connect with the spray nozzle 45. A refrigerant pipe is provided on the first heat exchanger 8. The vacuum pump mechanism 9 is connected to the top of the vertical cylinder 44 and delivers the exhaust gas outward.

[0014] In practical use, the high-temperature exhaust gas pipeline 1 is connected to the polycondensation reactor in polyester production, transporting the waste gas generated during the polycondensation reaction to the scraped wall heat exchanger 2. In the scraped wall heat exchanger 2, the high-temperature exhaust gas exchanges heat with the heat medium passing through it, heating the heat medium. The resulting high-temperature heat medium can be used for process heating, hot water preparation, preheating of combustion air, or generating low-pressure steam, achieving heat recovery and utilization from the high-temperature waste gas. The exhaust gas, after heat exchange with the heat medium, is then transported through the medium-temperature exhaust gas pipeline 3 to the scraped plate condenser 4. Low-temperature ethylene glycol is sprayed from the spray nozzles 45 in the condenser, thereby cooling the exhaust gas and dissolving and absorbing some of the ethylene glycol-soluble substances in the exhaust gas. The ethylene glycol in the scraped plate condenser 4 is then transported through a pipeline to the liquid seal tank 5. After passing through the residue filter 6 and the circulation pump 7, it is returned to the vertical cylinder 44 and connected to the spray nozzles 45, achieving the recycling of ethylene glycol. A first heat exchanger 8, which can be a plate heat exchanger, is installed on the pipeline between the spray nozzle 45 and the circulating pump 7. Because the ethylene glycol, after being sprayed onto the exhaust gas, exchanges heat with the exhaust gas, its temperature rises. To improve the continuous spray cooling effect, a refrigerant is introduced into the first heat exchanger 8 to cool the circulating ethylene glycol, maintaining the cooling effect on the exhaust gas. Since the ethylene glycol spraying process cools the medium-temperature exhaust gas in the scraped condenser 4, the internal pressure decreases, creating a negative pressure. To allow the exhaust gas to be smoothly discharged, a vacuum pump mechanism 9 is required. The vacuum pump mechanism 9 draws the pressure to a negative pressure, which must be lower than the internal pressure of the scraped condenser 4, allowing the exhaust gas inside to enter the vacuum pump mechanism 9 and be transported outwards. The vacuum pump mechanism 9 is a known existing technology, and its specific structure will not be described in detail here.

[0015] like Figure 2 As shown, the scraper-type heat exchanger 2 uses a hollow cylindrical body 21 with a horizontally positioned cylindrical cavity. A first drive motor 22 drives a rotating shaft, which in turn drives a scraper 23. Since the scraper 23 is in contact with the inner wall of the cylindrical body 21, it scrapes off the viscous fluid adhering to the inner wall during rotation, which is then discharged from the collection hopper 25. A jacket 24 is provided outside the cylindrical body 21, with channels for the heat exchange medium to flow through. As the heat exchange medium passes through the jacket 24, it exchanges heat with the high-temperature exhaust gas inside the cylindrical body 21. The wall thickness between the jacket 24 and the cylindrical body 21 should be relatively thin to improve heat exchange efficiency. The form of the jacket 24 is not specifically limited, as long as it provides channels for the heat exchange medium. In practical use, the scraper 23 can be arranged in a similar arc shape, that is, the two ends of the scraper 23 are circumferentially misaligned, which can drive the mucus on the inner wall to move towards the collection hopper 25 when rotating, thereby facilitating the collection and discharge of the mucus.

[0016] The cylindrical body 41 of the scraper condenser 4 contains a rotating shaft, i.e., a scraper 43, which is driven to rotate by a second drive motor 42. During the cooling process, a small amount of viscous liquid precipitates from the medium-temperature exhaust gas inside the scraper condenser 4 and adheres to the inner wall of the cylindrical body 41; this viscous liquid is scraped off by a scraper 23. The vertical cylinder 44 is equipped with spray nozzles 45, which spray a large amount of low-temperature ethylene glycol to directly cool the exhaust gas. As the ethylene glycol descends from top to bottom, it carries away the viscous liquid on the inner wall of the vertical cylinder 44, preventing scale buildup. The ethylene glycol at the bottom of the scraper condenser 4 flows into the liquid seal tank 5 through a pipe. Because the medium-temperature exhaust gas inside the scraper condenser 4 forms a negative pressure after cooling, and this negative pressure is maintained throughout the vacuum pump mechanism 9's pumping operation. Therefore, to prevent external air from entering, a liquid seal tank 5 is used to collect ethylene glycol. The ethylene glycol, under the action of the circulating pump 7, passes through a residue filter 6 to filter out residues, allowing it to be discharged externally. The filtered ethylene glycol then passes through the first heat exchanger 8, exchanging heat with the refrigerant to lower its temperature. The low-temperature ethylene glycol is then transported to the spray nozzles 45 and circulated into the vertical cylinder 44 to cool the medium-temperature exhaust gas. The ethylene glycol can be recycled. Of course, an ethylene glycol replenishment pipe can be installed on the liquid seal tank 5. Alternatively, ethylene glycol replenishment pipes can be installed in other locations to replenish ethylene glycol to the entire device, ensuring stable operation.

[0017] A precooler 10 is vertically mounted on the high-temperature exhaust gas pipe 1 before entering the scraped wall heat exchanger 2. The precooler 10 is hollow inside. The high-temperature exhaust gas pipe 1 is connected to the inside of the precooler 10. The top of the precooler 10 is connected to the inside of the columnar body 21 of the scraped wall heat exchanger 2 through a pipe. An atomizing nozzle 101 is provided at the upper end of the inside of the precooler 10. The pipe of the atomizing nozzle 101 is connected to the outside of the precooler 10. A collection pipe is provided at the bottom of the precooler 10.

[0018] Since the exhaust gas temperature generated during the polycondensation reaction is 200-300℃, in actual use, if the exhaust gas temperature exceeds 280℃ and is directly supplied to the scraped wall heat exchanger 2, it will cause instability in the operation of the equipment inside the scraped wall heat exchanger 2, such as the first drive motor 22. Therefore, a precooler 10 is installed on the high-temperature exhaust gas pipeline 1 before entering the scraped wall heat exchanger 2. Of course, a temperature sensor can be installed in the high-temperature exhaust gas pipeline 1 to detect the temperature of the high-temperature exhaust gas. When the detected temperature of the high-temperature exhaust gas is less than 280℃, it can directly enter the scraped wall heat exchanger 2 through the precooler 10. When the detected temperature of the high-temperature exhaust gas is higher than 280℃, the atomizing nozzle 101 in the precooler 10 can be opened to form ethylene glycol mist, which cools the high-temperature exhaust gas to below 280℃, thereby keeping the temperature of the high-temperature exhaust gas entering the scraped wall heat exchanger 2 below 280℃, making its operation more stable and reliable.

[0019] Ethylene glycol tubes are embedded in the inner wall of the cylindrical body 21 of the scraped wall heat exchanger 2, extending to the outside of the cylindrical body 21. Spray holes are opened on the ethylene glycol tubes inside the cylindrical body 21. Ethylene glycol tubes are embedded in the inner wall of the cylindrical body 21 of the scraped wall heat exchanger 2 according to actual needs, and spray holes are opened. In actual use, ethylene glycol is transported inward through the ethylene glycol tubes and sprayed into the hollow cylindrical cavity of the cylindrical body 21 under pressure. Under the action of the scraper 43, a liquid film can be formed on the inner wall of the cylindrical body 21. Therefore, the viscous liquid precipitated from the high-temperature exhaust gas is less likely to adhere to the inner wall of the cylindrical body 21, making scraping with the scraper 23 more convenient, improving cleaning efficiency and reliability.

[0020] A spray head 26 is installed inside the cylindrical body 21 at the end furthest from the collection hopper 25. An ethylene glycol tube is connected to the spray head 26, extending to the outside of the cylindrical body 21. The spray head 26 is located at the lower end inside the cylindrical body 21, facing the collection hopper 25. During the scraping of the slime on the inner wall of the cylindrical body 21 by the scraper 23, ethylene glycol is sprayed from the spray head 26. This allows the slime to be carried into the collection hopper 25 during the flow of ethylene glycol, thereby improving the efficiency and stability of the slime entering the collection hopper 25 and making the slime output more reliable.

[0021] A circulation pump 7 is connected to the bottom of the liquid seal tank 5 via a pipe. The outlet of the circulation pump 7 is connected to another first heat exchanger 8, which is also connected to the spray nozzle 45. A refrigerant pipe is also provided on the first heat exchanger 8.

[0022] Because the slime and residue need to be filtered through the residue filter 6 to ensure the cleanliness of the ethylene glycol, continuous circulation is possible. Of course, if the residue filter 6 becomes clogged, the circulation pump 7 can be switched to directly circulate the ethylene glycol in the liquid seal tank 5 to ensure the stable operation of the entire system.

[0023] In actual operation, the rotation speed of scraper 23 can be set to 0.5-2 r / min; the operating negative pressure of vacuum pump is -0.5~-3 kPa, and the total heat recovery rate can reach 60-75%.

[0024] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application 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, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0025] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the interaction relationship between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0026] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0027] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simplification, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A high-temperature exhaust gas waste heat recovery and sludge removal device, characterized in that: This includes wall-scraped heat exchangers, scraped condensers, and vacuum pump mechanisms. The scraped wall heat exchanger includes a cylindrical body with a hollow cylindrical cavity inside. A jacket is provided on the outside of the cylindrical body, and a heat medium inlet pipe and a heat medium outlet pipe are provided on the jacket. A high-temperature exhaust gas pipe is provided on the cylindrical body and communicates with the inside of the cylindrical body. A medium-temperature exhaust gas pipe is provided on the cylindrical body and is connected to a scraped plate condenser. The cylindrical body is horizontally placed, and a rotating shaft is horizontally placed inside the cylindrical body. One end of the rotating shaft extends to the outside of the cylindrical body. A first drive motor is provided outside the cylindrical body and is connected to the rotating shaft. A scraper is provided on the rotating shaft inside the cylindrical body and is in contact with the inner wall of the cylindrical body. A hopper is provided at the bottom of one end of the cylindrical body for collecting and discharging sludge. The scraper condenser includes a horizontally placed cylindrical body, which is hollow inside and closed at both ends. The intermediate-temperature exhaust gas pipe is connected to the cylindrical body. A vertical cylinder is located at one end of the cylindrical body, with its bottom connected to the cylindrical body and its top closed. A rotating shaft is rotatably mounted inside the cylindrical body, with one end extending to the outside of the cylindrical body. A second drive motor is located outside the cylindrical body and is connected to the rotating shaft. A scraper is provided on the rotating shaft. The scraper is in contact with the inner wall of the cylindrical body. A liquid seal tank is connected to the bottom of the cylindrical body through a pipe. A residue filter is connected to the bottom of the liquid seal tank through a pipe. The output port of the residue filter is connected to a circulating pump through a pipe. The outlet of the circulating pump is connected to a first heat exchanger. A spray nozzle is provided at the top inside the vertical cylinder. The first heat exchanger is connected to the top of the vertical cylinder through a pipe and extends into the vertical cylinder to connect with the spray nozzle. A refrigerant pipe is provided on the first heat exchanger. The vacuum pump mechanism is connected to the top of the vertical cylinder and delivers the exhaust gas outward.

2. The high-temperature exhaust gas waste heat recovery and sludge removal device according to claim 1, characterized in that: A precooler is vertically mounted on the high-temperature exhaust gas pipeline before it enters the scraped wall heat exchanger. The precooler is hollow inside, and the high-temperature exhaust gas pipeline is connected to the inside of the precooler. The top of the precooler is connected to the interior of the columnar body of the scraped wall heat exchanger through a pipeline. An atomizing nozzle is installed at the upper part of the interior of the precooler, and the pipeline of the atomizing nozzle is connected to the outside of the precooler. A collection pipe is installed at the bottom of the precooler.

3. The high-temperature exhaust gas waste heat recovery and sludge removal device according to claim 1, characterized in that: in Ethylene glycol tubes are embedded in the inner wall of the columnar body of the scraped heat exchanger, and the ethylene glycol tubes extend to the outside of the columnar body. Spray holes are opened on the ethylene glycol tubes inside the columnar body.

4. The high-temperature exhaust gas waste heat recovery and sludge removal device according to claim 3, characterized in that: A spray head is installed inside the columnar body at the end away from the night collection hopper. An ethylene glycol tube is connected to the spray head and extends to the outside of the columnar body. The spray head is located at the lower end inside the columnar body and faces the night collection hopper.

5. The high-temperature exhaust gas waste heat recovery and sludge removal device according to claim 1, characterized in that: A circulation pump is connected to the bottom of the liquid seal tank via a pipe. The outlet of the circulation pump is connected to another first heat exchanger, which is also connected to the spray nozzles. A refrigerant pipe is also installed on the first heat exchanger.

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