A polyester process column off-gas system control device

Abstract

The utility model discloses a polyester process column tail gas system controlling means in the polyester process column field is constituted by process column, esterification water circulating pump, esterification water storage jar, pressure control valve group, hot water control valve group, cooling fan, steam delivery pipeline etc., wherein, esterification process column top is equipped with steam export no.

Description

Technical Field

[0001] This utility model belongs to the field of polyester process towers, and specifically relates to a control device for the tail gas system of a polyester process tower. Background Technology

[0002] Currently, most polyester spinning equipment uses continuous polymerization spinning. Because the mixed process steam produced by the esterification reaction in the production process has a high ethylene glycol content and a high steam temperature, most manufacturers only use plate heat exchangers or fans to cool the steam at the top of the process tower during the process steam treatment process. The exhaust gas is treated by the exhaust gas scrubbing tower before being discharged into the atmosphere. Incomplete exhaust gas treatment can easily cause pollution and waste a lot of heat energy in the steam.

[0003] However, this invention utilizes a control device for the tail gas system of the polyester process tower to fully leverage the plate heat exchanger to replace the heat in the top steam of the tower with heat in the hot water circulation system, which is then ultimately sent to a hot water chiller for chilled water production. After the top steam is cooled, the condensate enters the esterification water storage tank. Different esterification water levels and extraction pipelines are used to control the oxygen content entering the system, providing stable conditions for the subsequent tail gas combustion. Utility Model Content

[0004] The purpose of this invention is to provide a control device for the tail gas system of a polyester process tower, which can stabilize the quality indicators of the separated ethylene glycol product, reduce the heat energy wasted due to large fluctuations, and ensure stable combustion of ethylene glycol or tail gas, thereby reducing costs and unnecessary tail gas emissions.

[0005] The purpose of this utility model is achieved as follows: A control device for the tail gas system of a polyester process tower includes an esterification process tower. The top of the esterification process tower has a steam outlet. The steam outlet is connected to a hot water plate heat exchanger and a tower top fan cooler via parallel pipes one and two, respectively. The hot water plate heat exchanger has heat exchange channels one and two inside. The end of pipe one is connected to the inlet of heat exchange channel one, and the outlet of heat exchange channel one is connected to the inlet of an esterification water tank via a pipe. The inlet of heat exchange channel two is connected to the drain outlet of a chiller, and the outlet of heat exchange channel two is connected to the inlet of a chiller. The tower top fan cooler includes an outer shell, inside which two parallel condenser tubes are installed. The end of pipe two is connected to two parallel branch pipes, which are respectively... The tank is connected to the ends of two condenser tubes, the other ends of which are connected to the side of a collection pipe. Several cooling fans corresponding to each condenser tube are installed on the outer casing. Several parallel condensing esterification water pipes and several parallel uncondensed esterification tail gas pipes are connected to the other side of the collection pipe. The height of each condensing esterification water pipe is lower than the height of each uncondensed esterification tail gas pipe. Multiple inlets are provided on the upper side of the esterification water tank. Each condensing esterification water pipe is connected to a corresponding inlet of the esterification water tank. The ends of each uncondensed esterification tail gas pipe are connected to nozzles on the side of the stripping tower. An overflow outlet is provided on the upper side of the esterification water tank, and the overflow outlet is also connected to nozzles on the side of the stripping tower via a pipe. An esterification water pipe is connected to the lower side of the esterification water tank, and the end of the esterification water pipe is connected to the inlet of the esterification process tower.

[0006] As a further improvement of this utility model, the nozzle is located at the inlet of the middle part of the stripping tower.

[0007] As a further improvement of this utility model, the top of the esterification process tower is also connected to a regulating steam pipe, the end of which is connected to the two sides of the pipeline. Bypass passage one and bypass passage two are respectively connected in parallel to the sides of pipeline one and pipeline two. The bypass passages facilitate adjustment and can handle unexpected situations.

[0008] As a further improvement of this utility model, the two condenser tubes are arranged vertically and horizontally, with multiple fins on each tube, and the cooling fans are arranged downwards. The fins increase the heat dissipation area.

[0009] As a further improvement of this utility model, the upper side of the esterification water tank is provided with a demineralized water inlet, and the lower side of the esterification water tank is provided with a discharge port. The discharge port is connected to the esterification water collection tank through a discharge pipeline. A return esterification tail gas pipe is connected to the side of the discharge pipeline. The return esterification tail gas pipe is connected to a nozzle on the side of the stripping tower. A return pipe connected to the side of the return esterification tail gas pipe is connected to a return pipe connected to the side of the discharge pipeline.

[0010] As a further improvement of this utility model, the esterification water pipeline is provided with a filter and an esterification water pump one in sequence, and a bypass passage three is provided in parallel on the side of the esterification water pipeline, and a bypass valve and an esterification water pump two are provided in sequence on the bypass passage three.

[0011] As a further improvement of this utility model, a return pipe is connected to the side of the esterified water pipe, and the end of the return pipe is connected to the corresponding inlet of the esterified water tank. A return valve is provided on the return pipe.

[0012] In operation, the steam generated by the esterification reaction enters the process tower. By adjusting the spray volume of esterification water, the ethylene glycol in the steam is captured and refluxed back to the bottom of the process tower for reuse. The remaining steam with a qualified concentration of ethylene glycol is divided into two paths, which enter a hot water plate heat exchanger and a tower top fan respectively. One path of esterification steam enters the hot water plate heat exchanger through the hot water regulating valve group. Steam flows on one side of the plate heat exchanger, and circulating hot water flows on the other side. The hot water carries away the heat of the steam entering the plate heat exchanger through circulation. At this time, the hot water temperature is controlled at 80-98℃ and enters the hot water chiller. After the chiller is running, the hot water continues to circulate, so that the steam can be continuously condensed into esterification water and enter the esterification water tank. The other path of esterification steam enters the tower top fan through the pressure regulating valve group for cooling and pressure adjustment of the process tower. The steam enters the tower top fan, and the fan is started to condense it into esterification water and enter the esterification water tank.

[0013] The residual steam after processing in the process tower is mainly used by the chiller through a hot water plate heat exchanger. Steam exceeding the heat required by the chiller is cooled by a pressure regulating valve group and then fed into the top fan of the tower to ensure the pressure stability of the esterification system. The uncondensed gas from the cooled steam fed into the top fan is connected to the tail gas main. Due to the temperature of the condensed esterified water (50-80℃), some gas and some uncondensed gas will be generated and enter the esterified water tank. A tail gas pipe is installed at the top of the esterified water tank to lead the tail gas from the tank to the tail gas main. Similarly, the esterified water extraction pipeline will also carry and generate some gas, and a tail gas pipe is also installed at the highest point of the pipeline to connect to the tail gas main. The tail gas from the tail gas main is drawn into the stripping tower by a nozzle set in the upper part of the stripping tower for treatment. The uncondensed tail gas after treatment in the stripping tower enters the heat medium furnace for incineration. The esterified water in the esterified water tank overflows to the esterified water collection tank of the water treatment unit for further treatment. Compared with the prior art, the beneficial effects of this utility model are as follows: the process tower exhaust gas is cleaner and the esterification water is of higher quality; the complementary action of the tower top pressure regulating valve and the hot water regulating valve can ensure the stable operation of the tower bottom under different outputs, and ensure the stable heat replacement of hot water to achieve the rational utilization of steam heat; the liquid seal of the pipeline, the fixed gas phase space and the reflux adjustment of the esterification water pump can ensure the reduction of COD and ethylene glycol content in the esterification water to achieve the purpose of clean production; the exhaust gas enters the gas stripping tower for treatment and then is incinerated, reducing the emission of waste gas. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of this utility model.

[0015] Figure 2 for Figure 1 A magnified view of a portion of the image.

[0016] Figure 3 for Figure 1 A magnified view of a portion of the image.

[0017] The components include: 1. Esterification process tower; 2. Steam outlet one; 3. Pipeline one; 4. Pipeline two; 5. Hot water plate heat exchanger, 5a. Inlet of heat exchange channel one; 5b. Outlet of heat exchange channel one; 5c. Inlet of heat exchange channel two; 5d. Outlet of heat exchange channel two; 6. Tower top fan cooler, 6a. Outer shell; 6b. Condenser tubes; 7. Esterification water tank. 8. Refrigeration unit drain outlet; 9. Refrigeration unit inlet; 10. Branch pipe; 11. Main pipe; 12. Cooling fan; 13. Condensed esterification water pipe; 14. Uncondensed esterification tail gas pipe; 15. Stripping tower; 16. Esterification water pipe; 17. Regulating steam pipe; 18. Bypass passage one; 19. Bypass passage two; 20. Fins; 21. Demineralized water inlet; 22. Discharge outlet; 23. Discharge pipe; 24. Esterification water collection tank; 25. Return esterification tail gas pipe; 26. Return pipe; 27. Filter; 28. Esterification water pump one; 29. ​​Bypass passage three; 30. Bypass valve; 31. Esterification water pump two; 32. Return pipe; 33. Return valve; 34. Overflow outlet. Detailed Implementation

[0018] like Figure 1-3The diagram shows a control device for a polyester process tower tail gas system, comprising an esterification tower 1. The top of the esterification tower 1 has a steam outlet 2. The steam outlet 2 is connected to a hot water plate heat exchanger 5 and a tower top fan cooler 6 via parallel pipes 3 and 4. The top of the esterification tower 1 is also connected to a regulating steam pipe 17, the end of which is connected to the side of pipe 4. Bypass passages 18 and 19 are connected in parallel to the sides of pipes 3 and 4, respectively. The bypass passages facilitate adjustment and respond to emergencies. Heat exchanger 5 has a heat exchange channel 1 and a heat exchange channel 2 inside. The end of pipe 1 3 is connected to the inlet 5a of heat exchange channel 1, and the outlet 5b of heat exchange channel 1 is connected to the inlet of esterification tank 7 via a pipe. The inlet 5c of heat exchange channel 2 is connected to the drain outlet 8 of the chiller, and the outlet 5d of heat exchange channel 2 is connected to the water inlet 9 of the chiller. The tower top fan cooler 6 includes an outer shell 6a, inside which are two parallel condenser tubes 6b. The end of pipe 2 4 is connected to two parallel branch pipes 10, which are respectively connected to the two condenser tubes 6b. The ends of the two condenser pipes 6b are connected, and the other ends of both pipes are connected to the side of the main pipe 11. Several cooling fans 12, corresponding to each condenser pipe 6b, are installed on the outer casing 6a. The two condenser pipes 6b are arranged vertically and horizontally, with multiple fins 20 on each pipe. Each cooling fan 12 faces downwards; the fins 20 increase the heat dissipation area. Several parallel condensing esterification water pipes 13 and several parallel uncondensed esterification exhaust pipes 14 are connected to the other side of the main pipe 11. The height of each condensing esterification water pipe 13 is lower than that of each uncondensed esterification exhaust pipe 14. The height of the esterification tail gas pipe 14 is such that multiple inlets are provided on the upper side of the esterification water tank 7, and each condensing esterification water pipe 13 is connected to a corresponding inlet of the esterification water tank 7. The ends of each uncondensed esterification tail gas pipe 14 are connected to nozzles on the side of the stripping tower 15, and the nozzles are located at the middle inlet of the stripping tower 15. An overflow outlet 34 is provided on the upper side of the esterification water tank 7, and the overflow outlet 34 is also connected to the nozzles on the side of the stripping tower 15 via a pipe. An esterification water pipe 16 is connected to the lower side of the esterification water tank 7, and the end of the esterification water pipe 16 is connected to the inlet of the esterification process tower 1.

[0019] The upper side of the esterification water tank 7 is provided with a demineralized water inlet 21, and the lower side of the esterification water tank 7 is provided with a discharge port 22. The discharge port 22 is connected to the esterification water collection tank 24 via a discharge pipe 23. The side of the discharge pipe 23 is connected to a return esterification tail gas pipe 25. The return esterification tail gas pipe 25 is connected to a nozzle on the side of the stripping tower 15. The side of the return esterification tail gas pipe 25 is connected to a return pipe 26 connected to the side of the discharge pipe 23.

[0020] A filter 27 and an esterification water pump 28 are sequentially installed on the esterification water pipeline 16. A bypass passage 3 29 is connected in parallel on the side of the esterification water pipeline 16. A bypass valve 30 and an esterification water pump 2 31 are sequentially installed on the bypass passage 3 29.

[0021] The side of the esterification water pipe 16 is connected to a return pipe 32, the end of which is connected to the corresponding inlet of the esterification water tank 7, and a return valve 33 is provided on the return pipe 32.

[0022] In operation, the steam generated by the esterification reaction enters the process tower. By adjusting the spray volume of esterification water, the ethylene glycol in the steam is captured and refluxed back to the bottom of the process tower for reuse. The remaining steam with a qualified concentration of ethylene glycol is divided into two paths, which enter the hot water plate heat exchanger 5 and the tower top fan respectively. One path of esterification steam enters the hot water plate heat exchanger 5 through the hot water regulating valve group. Steam flows on one side of the plate heat exchanger, and circulating hot water flows on the other side. The hot water carries away the heat of the steam entering the plate heat exchanger through circulation. At this time, the hot water temperature is controlled at 80-98℃ and enters the hot water chiller. After the chiller is running, the hot water continues to circulate, so that the steam can be continuously condensed into esterification water and enter the esterification water tank 7. The other path of esterification steam enters the tower top fan through the pressure regulating valve group for cooling and pressure adjustment of the process tower. The steam enters the tower top fan, and the fan is started to condense it into esterification water and enter the esterification water tank 7.

[0023] The remaining steam after processing in the process tower is mainly used by the hot water plate heat exchanger 5 to supply the chiller. Steam exceeding the heat required by the chiller enters the tower top fan through the pressure regulating valve group for cooling to ensure the pressure stability of the esterification system. The uncondensed gas after cooling of the steam entering the tower top fan is connected to the tail gas main pipe. Due to the temperature of the condensed esterified water (50-80℃), some gas and some uncondensed gas will be generated and enter the esterified water tank 7. A tail gas pipe is installed at the top of the esterified water tank 7 to lead the tail gas in the tank to the tail gas main pipe. The esterified water extraction pipeline will also carry and generate some gas. A tail gas pipe is also installed at the highest point of the pipeline to connect to the tail gas main pipe. The tail gas in the tail gas main pipe is drawn into the gas stripping tower by negative pressure through the nozzles set in the upper part of the gas stripping tower for treatment. The uncondensed tail gas after treatment in the gas stripping tower enters the heat medium furnace for incineration. The esterified water in the esterified water tank 7 overflows to the esterified water collection tank 24 of the water treatment unit for further treatment. Compared with the prior art, the beneficial effects of this utility model are as follows: the process tower exhaust gas is cleaner and the esterification water is of higher quality; the complementary action of the tower top pressure regulating valve and the hot water regulating valve can ensure the stable operation of the tower bottom under different outputs, and ensure the stable heat replacement of hot water to achieve the rational utilization of steam heat; the liquid seal of the pipeline, the fixed gas phase space and the reflux adjustment of the esterification water pump can ensure the reduction of COD and ethylene glycol content in the esterification water to achieve the purpose of clean production; the exhaust gas enters the gas stripping tower for treatment and then is incinerated, reducing the emission of waste gas.

[0024] This invention employs a nozzle installed in the upper part of the gas stripping tower to continuously supply exhaust gas into the tower, which is then treated and sent to the heat medium furnace for combustion. An overflow valve is installed in the esterification water tank 7 to ensure a stable gas phase space within the tank. Since the esterification water overflow pipeline will not be full, some steam will be carried over during the overflow process. A vent pipe is installed to remove residual steam, reducing COD in the esterification water. Sufficient gas phase space is maintained in the esterification water tank 7 because the temperature of the esterification water (approximately 50-80℃) will generate some gas, reducing the COD content in the esterification water. Traditional methods using bottom-feeding pipes are prone to clogging; the overflow method ensures a stable gas phase space within the tank and prevents pipe clogging. Because the pipes inside the esterification water tank 7 and the cooling fan 12 are under slight negative pressure, the esterification water flows from high to low during the overflow process, preventing the pipes from becoming full.

[0025] This utility model is not limited to the above embodiments. Based on the technical solutions disclosed in this utility model, those skilled in the art can make some substitutions and modifications to some of the technical features without creative labor, and these substitutions and modifications are all within the protection scope of this utility model.

Claims

1. A control device for a polyester process tower tail gas system, characterized in that, The system includes an esterification process tower. The esterification process tower has a steam outlet at its top. The steam outlet is connected to a hot water plate heat exchanger and a tower top fan cooler via parallel pipes 1 and 2, respectively. The hot water plate heat exchanger has two internal heat exchange channels: a first heat exchange channel and a second heat exchange channel. The end of pipe 1 is connected to the inlet of heat exchange channel 1, and the outlet of heat exchange channel 1 is connected to the inlet of an esterification water tank via a pipe. The inlet of heat exchange channel 2 is connected to the drain outlet of a chiller, and the outlet of heat exchange channel 2 is connected to the inlet of a chiller. The tower top fan cooler includes an outer shell. Inside the outer shell are two parallel condenser tubes. The end of pipe 2 is connected to two parallel branch pipes, which are respectively connected to the ends of two condenser tubes. The other end of each pipe is connected to the side of the collection pipe. Several cooling fans corresponding to each condenser pipe are installed on the outer casing. Several parallel condensing esterification water pipes and several parallel non-condensing esterification tail gas pipes are connected to the other side of the collection pipe. The height of each condensing esterification water pipe is lower than the height of each non-condensing esterification tail gas pipe. Multiple inlets are provided on the upper side of the esterification water tank. Each condensing esterification water pipe is connected to a corresponding inlet of the esterification water tank. The end of each non-condensing esterification tail gas pipe is connected to a nozzle on the side of the stripping tower. An overflow outlet is provided on the upper side of the esterification water tank. The overflow outlet is also connected to a nozzle on the side of the stripping tower via a pipe. An esterification water pipe is connected to the lower side of the esterification water tank. The end of the esterification water pipe is connected to the inlet of the esterification process tower.

2. The control device for the tail gas system of a polyester process tower according to claim 1, characterized in that, The nozzle is located at the inlet in the middle of the stripping tower.

3. A control device for a polyester process tower tail gas system according to claim 1 or 2, characterized in that, The top of the esterification process tower is also connected to a regulating steam pipe, the end of which is connected to the two sides of the pipeline. The sides of the pipeline are respectively connected in parallel to bypass passage one and bypass passage two.

4. A control device for a polyester process tower tail gas system according to claim 1 or 2, characterized in that, The two condenser tubes are arranged vertically and horizontally, with multiple fins on each tube, and each cooling fan is positioned downwards.

5. A control device for a polyester process tower tail gas system according to claim 1 or 2, characterized in that, The esterification water tank is provided with a demineralized water inlet on the upper side and a discharge port on the lower side. The discharge port is connected to the esterification water collection tank via a discharge pipeline. A return esterification tail gas pipe is connected to the side of the discharge pipeline. The return esterification tail gas pipe is connected to a nozzle on the side of the stripping tower. A return pipe connected to the side of the discharge pipeline is connected to the side of the return esterification tail gas pipe.

6. A control device for a polyester process tower tail gas system according to claim 1 or 2, characterized in that, The esterification water pipeline is equipped with a filter and an esterification water pump one in sequence. A bypass passage three is connected in parallel on the side of the esterification water pipeline. A bypass valve and an esterification water pump two are installed in sequence on the bypass passage three.

7. The polyester process tower tail gas system control device according to claim 6, characterized in that, The esterified water pipeline is connected to a reflux pipeline on its side. The end of the reflux pipeline is connected to the corresponding inlet of the esterified water tank, and a reflux valve is installed on the reflux pipeline.

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