A lean-rich methanol heat exchanger internal leakage monitoring and anti-shutdown device for a low-temperature methanol washing device

Abstract

The application discloses a device for monitoring and preventing shutdown of internal leakage of lean-rich methanol heat exchanger of low-temperature methanol washing device, and belongs to the field of acid gas purification in coal chemical industry. The device comprises a lean methanol tank, a lean-rich methanol heat exchanger, a normal-temperature nitrogen gas stripping tower, a thermal regeneration tower and a variable-frequency thermal regeneration tower bottom pump, a nitrogen gas access pipe is connected to a lean methanol pipeline from the lean-rich methanol heat exchanger to the lean methanol tank, the lean methanol tank is provided with a nitrogen gas leading-out pipe and is installed with a total sulfur on-line detector to monitor the internal leakage, the normal-temperature nitrogen gas stripping tower is additionally provided with a nitrogen gas flow adjusting assembly and a liquid level control valve is moved to a rich methanol inlet of the lean-rich methanol heat exchanger to reduce a pressure difference of a shell side of the lean-rich methanol heat exchanger, and the variable-frequency thermal regeneration tower bottom pump is matched with a feedforward-feedback combined control unit to be switched to a pressure difference control mode in the case of internal leakage. The device can identify the internal leakage of the lean-rich methanol heat exchanger in the first time, can maintain safe and stable operation of the system under the internal leakage condition, can reduce leakage amount and system energy consumption, and can avoid non-planned shutdown of the device and blind replacement of equipment.

Description

Technical Field

[0001] This application relates to a device for monitoring and preventing shutdown of internal leakage in a methanol heat exchanger used in a low-temperature methanol washing unit, belonging to the field of acid gas purification in the coal chemical industry. Background Technology

[0002] In coal chemical production, the low-temperature methanol washing process is a core technology for removing acidic gases such as CO2 and H2S from raw gas. Its principle is to use physical absorption, employing methanol as a solvent to selectively absorb acidic gases. A typical process flow is as follows: The methanol-rich solution, having absorbed CO2 and H2S, is depressurized, stripped, flashed, and cooled before being transported to a room-temperature nitrogen stripping tower (C-007). Nitrogen stripping further removes some acidic gases. Subsequently, the methanol-rich solution is pressurized by a transfer pump (P-008) and sent to a lean-rich methanol heat exchanger (E-010), where it exchanges heat with lean methanol from a thermal regeneration tower (C-004) to raise its temperature before finally entering the thermal regeneration tower (C-004). In the thermal regeneration tower (C-004), the methanol-rich solution undergoes heating and regeneration to remove the remaining CO2 and H2S. The resulting lean methanol is then reused as a circulating solvent.

[0003] Because methanol needs to be recycled, after prolonged operation, water and solid impurities such as carbon black and catalyst ash from upstream processes will accumulate in the methanol solution. To solve this problem, the reboiler of the thermal regeneration tower (C-004) is equipped with an intermediate partition (such as...). Figure 1 As shown, when the methanol solution vaporizes in the matching reboiler (E-011), water and solid impurities will accumulate on the side of the baffle closer to the reboiler (E-011). At the same time, some methanol is drawn out from this side, pressurized by the bottom pump of the thermal regeneration tower (P-005), and sent to the precision filter (S-001) to filter impurities. Part of the filtered methanol is sent to the methanol / water separator to remove water, and the remaining part is combined with the purified methanol on the other side of the baffle and then sent to the lean methanol heat exchanger (E-010) for heat exchange before entering the lean methanol tank (V-004).

[0004] However, existing low-temperature methanol washing systems have significant technical defects: in the lean-rich methanol heat exchanger (E-010), the pressure on the rich methanol side is higher than that on the lean methanol side. Once an internal leak occurs, H2S and CO2 in the rich methanol will seep into the lean methanol, causing lean methanol pollution. This will lead to excessive H2S and CO2 content in the downstream purified gas, causing unplanned shutdowns of the unit. In addition, after an internal leak occurs, the leak point is difficult to pinpoint, or even impossible to find. Usually, the entire heat exchanger needs to be replaced, resulting in serious waste of equipment resources and increased production costs. Utility Model Content

[0005] The purpose of this utility model is to overcome the shortcomings of the prior art and provide a device for monitoring and preventing shutdown of the internal leakage of the lean and rich methanol heat exchanger in a low-temperature methanol washing unit, so as to solve the abnormal operating conditions caused by the internal leakage of the heat exchanger leading to lean methanol pollution and excessive sulfur content in the purified gas, resulting in unplanned shutdown of the unit.

[0006] The technical solution adopted in this application is as follows: This utility model provides a device for monitoring internal leakage and preventing shutdown of a methanol-rich or lean methanol heat exchanger in a low-temperature methanol washing unit, comprising: Lean methanol tank, lean and rich methanol heat exchanger, ambient temperature nitrogen stripping tower, thermal regeneration tower and thermal regeneration tower bottom pump; The lean methanol outlet pipeline of the lean methanol heat exchanger is connected to the inlet of the lean methanol tank, and a nitrogen inlet pipe is connected to the lean methanol pipeline from the lean methanol heat exchanger to the lean methanol tank. The lean methanol tank is equipped with a nitrogen outlet pipe, and an online total sulfur detector is installed on the nitrogen outlet pipe; The methanol-rich outlet of the ambient temperature nitrogen stripping tower is connected to the methanol-rich inlet of the methanol-lean heat exchanger via a pump. The methanol-rich outlet of the methanol-lean heat exchanger is connected to the inlet of the thermal regeneration tower. The methanol-lean outlet of the thermal regeneration tower is connected to the methanol-lean inlet of the methanol-lean heat exchanger.

[0007] In one embodiment of this utility model, the detection accuracy of the online total sulfur analyzer is 0.01 ppmV.

[0008] In one embodiment of the present invention, a liquid level control valve is further included, which is installed on the rich methanol inlet pipe of the lean and rich methanol heat exchanger; a nitrogen flow regulating component is provided on the ambient temperature nitrogen stripping tower, which is used to increase the nitrogen consumption of the ambient temperature nitrogen stripping tower.

[0009] In one embodiment of the present invention, the reboiler of the thermal regeneration tower is provided with a middle partition plate, and the thermal regeneration tower is equipped with a reboiler. The middle partition plate divides the reboiler of the thermal regeneration tower into a first region close to the reboiler and a second region far from the reboiler. The inlet of the bottom pump of the thermal regeneration tower is connected to the first area, and the outlet of the bottom pump of the thermal regeneration tower is divided into two paths. One path is connected to a precision filter, and the outlet of the precision filter is divided into two paths. One path is connected to the methanol / water separator, and the other path is connected to the second area.

[0010] In one embodiment of this utility model, the bottom pump of the thermal regeneration tower is a variable frequency pump; it also includes a shut-off valve, which is disposed on the pipeline connecting the outlet of the precision filter and the second area; The lean-rich methanol heat exchanger is equipped with a shell-and-tube pressure differential monitoring component. The variable frequency pump is connected to the shell-and-tube pressure differential monitoring component and is used to switch to pressure differential control mode when there is internal leakage in the lean-rich methanol heat exchanger.

[0011] In one embodiment of this utility model, a feedforward-feedback combined control unit is further included, which is connected to the total sulfur online detector, the shell-and-tube differential pressure monitoring component and the frequency converter pump signal respectively; After receiving the detection signal from the online total sulfur analyzer, the feedforward-feedback joint control unit adjusts the speed of the variable frequency pump through feedforward control to change the pressure difference between the shell and tube sides of the lean and rich methanol heat exchanger. At the same time, it receives the pressure difference signal from the shell and tube side pressure difference monitoring component and eliminates the pressure difference deviation through feedback control.

[0012] In one embodiment of the present invention, a steam flow regulating unit is further included, which is connected to the steam inlet pipe of the reboiler; The lean methanol regeneration quality monitoring component is installed on the lean methanol outlet pipeline of the thermal regeneration tower. The steam flow regulation unit is signal-connected to the lean methanol regeneration quality monitoring component and is used to adjust the steam supply of the reboiler according to the lean methanol regeneration quality.

[0013] In one embodiment of this utility model, the thermal regeneration tower is equipped with a sensitive plate temperature monitoring component and a temperature compensation control unit, which is connected to the sensitive plate temperature monitoring component and the total sulfur online detector respectively. When the total sulfur online detector detects an internal leak in the methanol-lean heat exchanger, the temperature compensation control unit adjusts the detection value of the sensitive plate temperature monitoring component to compensate for the internal leak and eliminate the abnormal influence of the internal leak on the sensitive plate temperature.

[0014] In one embodiment of this utility model, it further includes a hot regeneration tower differential monitoring component and a regeneration effect judgment unit. The hot regeneration tower differential monitoring component is disposed on the hot regeneration tower, and the regeneration effect judgment unit is signal connected to the hot regeneration tower differential monitoring component and the sensitive plate temperature monitoring component, respectively, and outputs the regeneration effect judgment result of the hot regeneration tower by coupling the tower differential data and the sensitive plate temperature data.

[0015] In one embodiment of this utility model, the lean methanol tank is equipped with a liquid level monitoring component and a pressure balancing component; The liquid level monitoring component is used to monitor the lean methanol liquid level in the lean methanol tank, and the pressure balancing component works in conjunction with the nitrogen outlet pipe to maintain stable pressure in the lean methanol tank.

[0016] In one embodiment of this utility model, a nitrogen flow control valve is provided on the nitrogen inlet pipe. The nitrogen flow control valve is connected to the total sulfur online detector. When the total sulfur online detector detects an abnormal sulfur content, the nitrogen flow control valve adjusts the nitrogen inlet flow to enhance the gas lifting effect.

[0017] The beneficial effects that this application can produce include: 1) This application introduces an appropriate amount of nitrogen into the lean methanol pipeline leading to the lean methanol tank. After the nitrogen enters the lean methanol tank, it is led out and an online total sulfur detector is installed on the lead-out pipeline. By comparing the total sulfur analysis results, the internal leakage of the lean and rich methanol heat exchanger can be detected in a timely manner.

[0018] 2) This application addresses the problem of gas-liquid two-phase flow interference in the reheating process of rich methanol in a lean-rich methanol heat exchanger by increasing the nitrogen usage in the nitrogen stripping tower at ambient temperature and further analyzing the nitrogen at ambient temperature to reduce the CO2 content. This allows the liquid level control valve to be moved from the outlet to the inlet of the lean-rich methanol heat exchanger, effectively reducing the tube / shell pressure differential and further minimizing leakage.

[0019] 3) This application utilizes a variable frequency drive (VFD) for the bottom pump of the thermal regeneration tower. During normal operation of the lean-rich methanol heat exchanger, only bypass flow control is applied. In the event of internal leakage in the lean-rich methanol heat exchanger, the shut-off valve is closed, and differential pressure control is switched to the control mode. The differential pressure setting employs a feedforward-feedback combined control method to maintain safe and stable system operation even in the event of internal leakage. When the total sulfur analyzer detects an increase, the feedforward control improves the lean methanol quality by promptly increasing the shell-side differential pressure of E010 tube. Feedback control is used to eliminate deviations and reduce fluctuations. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the reboiler structure in a thermal regeneration tower in the prior art; Figure 2 This is a schematic diagram of the overall process of the internal leakage monitoring and anti-shutdown device for the lean and rich methanol heat exchanger used in the low-temperature methanol washing unit in this application. Figure label: V-004 is a lean methanol tank; E-010 is a lean and rich methanol heat exchanger; C-007 is an ambient temperature nitrogen stripping tower; C-004 is a thermal regeneration tower; P-005 is a thermal regeneration tower bottom pump; P-008 is a pump; E-011 is a reboiler; S-001 is a precision filter; XV-001 is a shut-off valve. Detailed Implementation

[0021] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0022] Please refer to Figures 1-2This application provides a device for monitoring and preventing shutdown of internal leakage in a lean and rich methanol heat exchanger for a low-temperature methanol washing unit. This device is suitable for the acid gas purification system of low-temperature methanol washing in the coal chemical industry, and includes: lean methanol tank V-004, lean and rich methanol heat exchanger E-010, ambient temperature nitrogen stripping tower C-007, thermal regeneration tower C-004, thermal regeneration tower bottom pump P-005, pump P-008, reboiler E-011, precision filter S-001, shut-off valve XV-001, and supporting monitoring and control components.

[0023] The specific connection relationships of each component are as follows: (1) Connection between the lean and rich methanol heat exchanger, E-010, and the core storage tank / tower: On the lean methanol side: the lean methanol outlet pipe of the thermal regeneration tower C-004 is connected to the lean methanol inlet of the lean-rich methanol heat exchanger E-010, and the lean methanol outlet pipe of the lean-rich methanol heat exchanger E-010 is directly connected to the inlet of the lean methanol tank V-004, forming a lean methanol circulation path. On the methanol-rich side: The methanol-rich outlet of the ambient temperature nitrogen stripping tower C-007 is pressurized by the transfer pump P-008 and connected to the methanol-rich inlet of the lean-rich methanol heat exchanger E-010. The methanol-rich outlet of the lean-rich methanol heat exchanger E-010 is connected to the inlet of the thermal regeneration tower C-004, forming a heat exchange path before methanol-rich regeneration.

[0024] (2) Setting up the core components for internal leakage monitoring: A nitrogen inlet pipe (diameter matched to the lean methanol pipeline, typically DN25~DN50) is vertically connected to the lean methanol pipeline from the lean methanol heat exchanger E-010 to the lean methanol tank V-004. This pipe is used to introduce a suitable amount of low-pressure nitrogen (pressure 0.12~0.15MPa, flow rate adjusted by a subsequent control valve) into the lean methanol. Simultaneously, a nitrogen outlet pipe is installed at the top of the lean methanol tank V-004. A total sulfur online detector (model such as SICK GM70, with a detection accuracy strictly controlled to 0.01ppmV%) is connected in series on this outlet pipe to monitor the total sulfur content in the nitrogen after stripping in real time. If the lean methanol heat exchanger E-010 leaks internally, H2S from the rich methanol will seep into the lean methanol. After nitrogen stripping, the total sulfur detector will capture the signal, providing an immediate warning of the internal leak.

[0025] (3) Impurity and moisture removal structure of thermal regeneration tower C-004: The reboiler of thermal regeneration tower C-004 is fixedly equipped with a middle partition plate, dividing the reboiler into two independent areas: a first area near the reboiler E-011 (used to enrich residual water, carbon black, catalyst ash, and other impurities after methanol solution evaporation), and a second area away from the reboiler E-011 (used to collect purified methanol). The inlet of the bottom pump P-005 of the thermal regeneration tower is connected to the first area via a pipeline, and the outlet is divided into two paths: one path connects to the precision filter S-001, with a filtration accuracy of 10μm and a filter element material of polytetrafluoroethylene, and the other path is reserved; the outlet of the precision filter S-001 is further divided into two paths: one path connects to the methanol / water separator (used to remove water from methanol), and the other path connects to the second area via a pipeline with a shut-off valve XV-001, realizing the reflux reuse of filtered methanol.

[0026] It should be noted that, in order to achieve closed-loop control of "internal leakage monitoring - differential pressure regulation - system stability", this device has added multiple sets of control components. The structure and function of each component are as follows: (1) Methanol-rich side differential pressure optimization component: The top of the ambient temperature nitrogen stripping tower C-007 is equipped with a nitrogen flow regulating component (specifically an electric nitrogen flow control valve, such as Fisher DVC6200), which can increase the nitrogen consumption of the ambient temperature nitrogen stripping tower C-007 according to system instructions (the nitrogen consumption under normal operating conditions is 500~800 Nm³ / h, and can be increased to 1000~1200 Nm³ / h in case of internal leakage). By enhancing the room temperature desorption effect and reducing the CO2 content in rich methanol, the formation of a gas-liquid two-phase flow due to CO2 precipitation during the reheating process of rich methanol in the lean methanol heat exchanger E-010 is avoided, thereby eliminating heat exchange interference. At the same time, the liquid level control valve, which is traditionally located at the rich methanol outlet of the lean methanol heat exchanger E-010, is moved to the rich methanol inlet pipe of the lean methanol heat exchanger E-010. By adjusting the inlet liquid level, the pressure difference between the tube side (rich methanol side) and the shell side (lean methanol side) of the lean methanol heat exchanger E-010 is directly reduced, thereby reducing internal leakage from the source.

[0027] (2) Variable frequency pump and differential pressure combined control assembly: The bottom pump P-005 of the thermal regeneration tower is a variable frequency pump. During normal operation, the variable frequency pump operates in "bypass filter flow control" mode, and is only used to transport methanol containing impurities in the first zone to the precision filter S-001 for filtration. The tube side and shell side of the lean and rich methanol heat exchanger E-010 are respectively equipped with differential pressure monitoring components (specifically two pressure transmitters and one differential pressure calculator). These components are connected to the variable frequency pump and the shut-off valve XV-001 through the PLC control system signal. When the total sulfur online detector detects that the sulfur content exceeds 0.02ppmV% (internal leakage warning threshold), the system automatically closes the shut-off valve XV-001 and switches the variable frequency pump to differential pressure control mode.

[0028] (3) Feedforward-feedback joint control unit: This unit is integrated into the PLC control system and is connected to the online total sulfur analyzer, differential pressure monitoring component, and frequency converter pump signal. Feedforward control: When the total sulfur meter detects an increase in sulfur content, it immediately triggers a feedforward command to increase the amount of lean methanol delivered from the thermal regeneration tower C-004 to the lean-rich methanol heat exchanger E-010 by increasing the speed of the variable frequency pump. This increases the shell-side (lean methanol side) pressure of the lean-rich methanol heat exchanger E-010, reduces the shell-tube pressure difference, and improves the quality of lean methanol. Feedback control: The differential pressure monitoring component collects the shell-and-tube differential pressure data of the lean and rich methanol heat exchanger E-010 in real time and feeds it back to the control unit. If the actual differential pressure deviates from the set value (0.1MPa), the control unit automatically adjusts the speed of the variable frequency pump to eliminate the deviation and reduce system fluctuations.

[0029] (4) Components to ensure the regeneration effect of the thermal regeneration tower: Steam flow regulation unit: An electric steam flow control valve is installed on the steam inlet pipe of reboiler E-011, and a lean methanol regeneration quality monitoring component is installed on the lean methanol outlet pipe of thermal regeneration tower C-004; when the analyzer detects that the purity of lean methanol is lower than 99.5%, the system automatically opens the steam flow control valve to increase the steam supply to lean and rich methanol heat exchanger E-011, ensuring that the lean methanol regeneration is qualified; Sensitive plate temperature compensation unit: The thermal regeneration tower C-004 is equipped with a sensitive plate temperature monitoring component, which is connected to the total sulfur online detector and PLC control system signal; when the internal leakage of the lean and rich methanol heat exchanger E-010 causes abnormal fluctuations in the sensitive plate temperature, the control unit automatically compensates for the temperature detection value to eliminate the interference of internal leakage on temperature monitoring. Regeneration effect judgment unit: A differential pressure monitoring component (specifically a differential pressure transmitter) is installed between the top and bottom of the thermal regeneration tower C-004. This component and the sensitive plate temperature monitoring component are both connected to the regeneration effect judgment unit. The unit outputs the regeneration effect judgment result of the thermal regeneration tower by coupling the tower differential pressure data and the sensitive plate temperature data.

[0030] (5) Lean methanol tank V-004 stability assurance components: The side wall of the lean methanol tank V-004 is equipped with a liquid level monitoring component (specifically a magnetic float level gauge) to monitor the lean methanol liquid level in the tank in real time and prevent the downstream absorption tower from running out of material due to excessively low liquid level. The top of the tank is also equipped with a pressure balancing component (specifically a pressure regulating valve). This component works in conjunction with the nitrogen outlet pipe. When the pressure inside the tank fluctuates due to the introduction of nitrogen, the pressure regulating valve automatically opens and closes to maintain the pressure inside the tank and ensure uniform nitrogen stripping effect.

[0031] (6) Nitrogen stripping enhancement component: A nitrogen flow control valve is installed on the nitrogen inlet pipe. This valve is connected to the signal of the total sulfur online detector. When the total sulfur detector detects an abnormal sulfur content, the control valve automatically opens to increase the nitrogen inlet flow, enhance the stripping effect on lean methanol, and accelerate the removal of H2S.

[0032] It should be noted that the following describes in detail the working process of a leak monitoring and shutdown prevention device for a methanol-rich / lean methanol heat exchanger used in a low-temperature methanol washing unit: (1) Normal operating conditions Lean methanol cycle: The lean methanol regenerated by the thermal regeneration tower C-004 enters the shell side of the lean-rich methanol heat exchanger E-010, where it exchanges heat with the rich methanol in the tube side, and is then transported through pipelines to the lean methanol tank V-004 for storage and use by the downstream absorption tower. Methanol-rich pretreatment: After some CO2 is removed by nitrogen stripping in the ambient temperature nitrogen stripping tower C-007, the methanol-rich in the tower is pressurized by pump P-008 and sent to the tube side of the lean methanol-rich heat exchanger E-010. After exchanging heat with the lean methanol, it enters the thermal regeneration tower C-004 for regeneration. Impurity and moisture removal: The methanol containing impurities in the first zone of the bottom of the thermal regeneration tower C-004 is pumped by the bottom pump P-005 to the precision filter S-001 for filtration. After filtration, part of the methanol is sent to the methanol / water separator to remove moisture, and part is returned to the second zone through the shut-off valve XV-001 to merge with the purified methanol. Monitoring and control: The total sulfur content in nitrogen detected by the online total sulfur analyzer remained stable below 0.01 ppmV%, the shell-and-tube pressure difference of the lean and rich methanol heat exchanger E-010 remained stable at 0.1~0.15 MPa, the steam flow rate, sensitive plate temperature, and tower differential pressure were all within the normal range, and there were no alarms in the system.

[0033] (2) Internal leakage occurrence and response conditions Internal Leak Monitoring: If the rich and lean methanol heat exchanger E-010 experiences internal leakage due to corrosion or wear, the rich methanol (containing H2S and CO2) in the tube side will seep into the lean methanol in the shell side. The lean methanol will carry H2S into the lean methanol tank V-004. The nitrogen introduced through the nitrogen inlet pipe will strip the lean methanol, and H2S will be discharged from the outlet pipe along with the nitrogen. If the total sulfur online detector detects that the sulfur content has risen to above 0.02 ppmV%, the internal leak alarm will be triggered immediately. Differential pressure regulation: The system automatically closes the shut-off valve XV-001 and switches P-005 to "differential pressure control" mode; the feedforward control command is triggered, and the speed of the bottom pump P-005 of the thermal regeneration tower is increased to 45~50Hz, increasing the amount of lean methanol delivered to the lean and rich methanol heat exchanger E-010, increasing the shell-side pressure, and reducing the tube-shell-side pressure difference; the feedback control corrects the differential pressure deviation in real time to ensure differential pressure stability; Methanol-rich optimization: The nitrogen flow regulation component of the ambient temperature nitrogen stripping tower C-007 automatically increases the nitrogen flow rate to 1000~1200 Nm³ / h, which enhances the CO2 desorption effect of methanol-rich gas, avoids gas-liquid two-phase flow interference in the methanol-lean heat exchanger E-010, and further reduces the tube-side pressure. Regeneration assurance: If the purity of lean methanol decreases, the steam flow regulation unit automatically increases the steam supply to reboiler E-011; when the temperature of the sensitive plate is abnormal, the temperature compensation unit is activated to eliminate interference; the regeneration effect judgment unit confirms that the thermal regeneration tower C-004 is qualified for regeneration by coupling the tower difference with the temperature, thus ensuring the quality of lean methanol. System stability: The flow control valve of the nitrogen inlet pipe is opened wider to enhance the gas stripping effect, and the liquid level and pressure balance components of the lean methanol tank V-004 maintain the stability inside the tank; ultimately, the system can achieve non-stop operation without internal leakage. At the same time, the degree of internal leakage can be assessed in real time by the trend of total sulfur content change and differential pressure data, providing a basis for subsequent equipment maintenance.

[0034] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A device for monitoring and preventing shutdown of internal leakage in a methanol-rich or lean methanol heat exchanger used in a low-temperature methanol washing unit, characterized in that, include: Lean methanol tank (V-004), lean and rich methanol heat exchanger (E-010), ambient temperature nitrogen stripping tower (C-007), thermal regeneration tower (C-004) and thermal regeneration tower bottom pump (P-005). The lean methanol outlet pipeline of the lean methanol heat exchanger (E-010) is connected to the inlet of the lean methanol tank (V-004), and a nitrogen inlet pipe is connected to the lean methanol pipeline from the lean methanol heat exchanger (E-010) to the lean methanol tank (V-004). The lean methanol tank (V-004) is equipped with a nitrogen outlet pipe, and an online total sulfur detector is installed on the nitrogen outlet pipe; The methanol-rich outlet of the ambient temperature nitrogen stripping tower (C-007) is connected to the methanol-rich inlet of the methanol-lean heat exchanger (E-010) via a pump (P-008). The methanol-rich outlet of the methanol-lean heat exchanger (E-010) is connected to the inlet of the thermal regeneration tower (C-004). The methanol-lean outlet of the thermal regeneration tower (C-004) is connected to the methanol-lean inlet of the methanol-lean heat exchanger (E-010).

2. The apparatus according to claim 1, characterized in that, The detection accuracy of the online total sulfur analyzer is 0.01 ppmV.

3. The apparatus according to claim 1, characterized in that, It also includes a level control valve, which is installed on the rich methanol inlet pipe of the lean and rich methanol heat exchanger (E-010); the ambient temperature nitrogen stripping tower (C-007) is equipped with a nitrogen flow regulating component, which is used to increase the nitrogen consumption of the ambient temperature nitrogen stripping tower (C-007).

4. The apparatus according to claim 1, characterized in that, The reboiler of the thermal regeneration tower (C-004) is equipped with a middle partition plate, and the thermal regeneration tower (C-004) is equipped with a reboiler (E-011). The middle partition plate divides the reboiler of the thermal regeneration tower (C-004) into a first region close to the reboiler (E-011) and a second region away from the reboiler (E-011). The inlet of the thermal regeneration tower bottom pump (P-005) is connected to the first area, and the outlet of the thermal regeneration tower bottom pump (P-005) is divided into two paths, one of which is connected to a precision filter (S-001), and the outlet of the precision filter (S-001) is divided into two paths, one of which is connected to a methanol / water separator, and the other of which is connected to the second area. The thermal regeneration tower bottom pump (P-005) is a variable frequency pump; it also includes a shut-off valve (XV-001), which is installed on the pipeline connecting the outlet of the precision filter (S-001) and the second area; The lean-rich methanol heat exchanger (E-010) is equipped with a shell-and-tube pressure differential monitoring component. The variable frequency pump is connected to the shell-and-tube pressure differential monitoring component and is used to switch to the pressure differential control mode when there is internal leakage in the lean-rich methanol heat exchanger (E-010).

5. The apparatus according to claim 4, characterized in that, It also includes a feedforward-feedback combined control unit, which is connected to the total sulfur online detector, the shell-and-tube differential pressure monitoring component and the frequency converter pump signal respectively; After receiving the detection signal from the online total sulfur analyzer, the feedforward-feedback joint control unit adjusts the speed of the variable frequency pump through feedforward control to change the pressure difference between the shell and tube sides of the lean and rich methanol heat exchanger (E-010). At the same time, it receives the pressure difference signal from the shell and tube side pressure difference monitoring component and eliminates the pressure difference deviation through feedback control.

6. The apparatus according to claim 4, characterized in that, It also includes a steam flow regulating unit, which is connected to the steam inlet pipe of the reboiler (E-011); The lean methanol regeneration quality monitoring component is installed on the lean methanol outlet pipeline of the thermal regeneration tower (C-004). The steam flow regulation unit is connected to the lean methanol regeneration quality monitoring component and is used to adjust the steam supply of the reboiler (E-011) according to the lean methanol regeneration quality.

7. The apparatus according to claim 1, characterized in that, The thermal regeneration tower (C-004) is equipped with a sensitive plate temperature monitoring component and a temperature compensation control unit. The temperature compensation control unit is connected to the sensitive plate temperature monitoring component and the total sulfur online detector. When the total sulfur online detector detects an internal leak in the lean and rich methanol heat exchanger (E-010), the temperature compensation control unit compensates and adjusts the detection value of the sensitive plate temperature monitoring component to eliminate the abnormal influence of the internal leak on the sensitive plate temperature.

8. The apparatus according to claim 7, characterized in that, It also includes a thermal regeneration tower differential monitoring component and a regeneration effect judgment unit. The thermal regeneration tower differential monitoring component is installed on the thermal regeneration tower (C-004). The regeneration effect judgment unit is connected to the thermal regeneration tower differential monitoring component and the sensitive plate temperature monitoring component respectively. It outputs the regeneration effect judgment result of the thermal regeneration tower (C-004) by coupling the tower differential data and the sensitive plate temperature data.

9. The apparatus according to claim 1, characterized in that, The lean methanol tank (V-004) is equipped with a liquid level monitoring component and a pressure balancing component; The liquid level monitoring component is used to monitor the lean methanol liquid level in the lean methanol tank (V-004), and the pressure balancing component works in conjunction with the nitrogen outlet pipe to maintain the pressure stability in the lean methanol tank (V-004).

10. The apparatus according to claim 1, characterized in that, The nitrogen inlet pipe is equipped with a nitrogen flow control valve, which is connected to the total sulfur online detector. When the total sulfur online detector detects an abnormal sulfur content, the nitrogen flow control valve adjusts the nitrogen inlet flow to enhance the gas extraction effect.

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