Tail gas recovery system for online analytical instrument

Abstract

The invention relates to a tail gas recovery system for an on-line analysis instrument, and belongs to the technical field of tail gas treatment of the on-line analysis instrument, the tail gas recovery system comprises a pressure regulating unit, a monitoring and flow regulating unit, an amplifying and pressurizing unit, a trace flow limiting unit, a pressure monitoring and regulating unit, a main pipeline and a protective gas inlet; the main pipeline and the amplifying and pressurizing unit are jointly connected with an injection pump, and the amplifying and pressurizing unit is connected with a protective gas inlet; the monitoring and flow adjusting unit is mounted on the main pipeline; the pressure adjusting unit is connected with the shielding gas inlet and the gas inlet end of the main pipeline; the pressure monitoring and adjusting unit is arranged at the exhaust end of the main pipeline, the pressure monitoring and adjusting unit is further connected with the micro flow limiting unit and the amplifying and pressurizing unit, and the micro flow limiting unit is connected with the pressure adjusting unit. The device has the advantages that tail gas is collected under constant pressure, and normal operation of an analysis instrument is guaranteed.

Description

Technical Field

[0001] This application relates to the technical field of tail gas treatment for on-line analytical instruments, and particularly to a tail gas recovery system for on-line analytical instruments. Background Art

[0002] An on-line analytical instrument is a device that can automatically detect and analyze gases in a production process in real time, continuously, or at high frequencies, without manual sampling or laboratory off-line detection. It is directly integrated into the industrial process and transmits data to the control system in real time through sensors or analysis modules to achieve immediate monitoring and optimization of process parameters. However, due to technical requirements, when the on-line analytical instrument is operating normally, a stable back pressure is required at the sample discharge point, and changes in pressure will have a serious impact on the detection results of the analytical instrument. Even slight pressure fluctuations will cause huge errors in the analysis results.

[0003] However, during the analysis of tail gas, since the tail gas usually cannot be directly discharged into the atmosphere after being discharged from the on-line analytical instrument, but needs to be recovered into the process pipeline and burned. In the prior art, generally, inert gases such as nitrogen and argon are used as carrier gases to push the tail gas into the collection pipeline to prevent oxidation or explosion of oxygen-sensitive gases (such as certain reaction intermediates). However, the pressure during the combustion treatment of the tail gas is dynamic. Controlling the delivery of the carrier gas flow with a simple pressure regulating valve and pressure measuring device is likely to cause unstable pressure in the pipeline, and controlling the delivery of the carrier gas flow with a simple pressure regulating valve and pressure measuring device is still likely to cause fluctuations in the back pressure of the analytical instrument. Summary of the Invention

[0004] In order to collect tail gas at a constant pressure and ensure the normal operation of the analytical instrument, this application provides a tail gas recovery system for on-line analytical instruments.

[0005] The tail gas recovery system for on-line analytical instruments provided by this application adopts the following technical solutions: A tail gas recovery system for on-line analytical instruments includes a pressure regulating unit, a monitoring and flow regulating unit, an amplifying and pressurizing unit, a micro-limiting flow unit, a pressure monitoring and regulating unit, a main pipeline, and a protective gas inlet; The main pipeline and the amplifying and pressurizing unit are jointly connected to a jet pump. The amplifying and pressurizing unit is connected to the protective gas inlet. The amplifying and pressurizing unit is used to pressurize the protective gas and discharge it to the jet pump, and the gas in the main pipeline is sucked out through the jet pump; The monitoring and flow regulating unit is installed on the main pipeline and is used to detect the air pressure in the main pipeline and regulate the discharge flow rate; The pressure regulating unit is connected to the protective gas inlet and the intake end of the main pipeline. The pressure regulating unit is used to regulate the pressure of the protective gas so that the protective gas with stable pressure is mixed with the tail gas of the main pipeline to regulate the air pressure at the intake end of the main pipeline. The pressure monitoring and regulating unit is arranged at the exhaust end of the main pipeline, and the pressure monitoring and regulating unit is further connected to the micro flow limiting unit and the amplification and pressurization unit. The micro flow limiting unit is connected to the pressure regulating unit. The micro flow limiting unit is used to shunt the protective gas regulated by the pressure regulating unit and reduce the flow rate, and make the limited-flow protective gas serve as the regulating signal of the amplification and pressurization unit. The pressure monitoring and regulating unit is used to detect the negative pressure at the exhaust end of the main pipeline and regulate the flow rate of the protective gas discharged to the outside by the micro flow limiting unit, so as to regulate the pressure of the protective gas in the micro flow limiting unit.

[0006] By adopting the above technical solution, the protective gas is pressure-regulated by the pressure regulating unit and then mixed with the tail gas to quickly compensate for the sudden change in the intake end pressure and regulate the back pressure at the exhaust end of the analytical instrument. The back pressure situation at the exhaust end of the analytical instrument is observed through the monitoring and flow regulating unit, and the mixed gas is regulated to be discharged to the ejector pump at the required flow rate. The protective gas is also shunted and flows through the ejector pump after passing through the amplification and pressurization unit, so that the ejector pump sucks the gas in the main pipeline and discharges it together with the pressurized protective gas. When the pressure at the discharge end of the ejector pump fluctuates, the pressure monitoring and regulating unit detects the fluctuation and timely adjusts the pressure of the protective gas passing through the micro flow limiting unit, so that the amplification and pressurization unit timely regulates the pressure of the protective gas, thereby changing the entrainment gas flow rate and suction of the ejector pump, quickly offsetting the pressure fluctuation at the discharge end, maintaining the system back pressure stable until the pressure detected by the pressure monitoring and regulating unit returns to normal.

[0007] The micro flow limiting shunts the protective gas and reduces the flow rate. There is a lag in the conduction of the air pressure disturbance, and the pressure monitoring and regulating unit adjusts through a fast feedback mechanism, so that the pressure monitoring and regulating unit will not affect the air pressure of the pressure regulating unit when adjusting the air pressure. Similarly, since the flow rate at the exhaust end of the monitoring and flow regulating unit is less than its intake end, there is a lag in the conduction of the air pressure disturbance. The pressure monitoring and regulating unit adjusts through a fast feedback mechanism, so that the pressure monitoring and regulating unit will not affect the air pressure at the intake end of the monitoring and flow regulating unit when adjusting the air pressure. Furthermore, the isolation between the sample gas path and the control signal gas path is realized, the reverse conduction of the fluctuation is reduced, and the tail gas is collected under a constant pressure to ensure the normal operation of the analytical instrument.

[0008] Optionally, the amplification and pressurization unit includes a gas pressure amplifier. The adjustment end of the gas pressure amplifier is connected to the micro current-limiting unit. The intake end of the gas pressure amplifier is connected to the protective gas inlet. The exhaust end of the gas pressure amplifier is connected to the jet pump. A first pressure gauge is provided between the gas pressure amplifier and the jet pump.

[0009] By adopting the above technical solution, when the pressure at the discharge end of the jet pump fluctuates, the pressure monitoring and adjustment unit adjusts the gas pressure at the exhaust end of the micro current-limiting unit. The change in the gas pressure at the exhaust end of the micro current-limiting unit is transmitted through the gas to the adjustment end of the gas pressure amplifier, so that the gas pressure amplifier adjusts the output pressure at its exhaust end proportionally according to the air pressure value at its adjustment end, thereby quickly correcting the suction capacity of the jet pump and maintaining the stability of the system back pressure. The first pressure gauge provides real-time monitoring, and abnormal conditions can be detected in time to prevent the risks of overpressure or underpressure.

[0010] Optionally, the pressure adjustment unit includes a pressure regulating valve and an ultra-micro pressure reducing valve. The intake end of the pressure regulating valve is connected to the protective gas inlet. The exhaust end of the pressure regulating valve is connected to the ultra-micro pressure reducing valve. The exhaust end of the ultra-micro pressure reducing valve is connected to the intake end of the main pipeline.

[0011] By adopting the above technical solution, a two-stage pressure reduction structure is adopted. The pressure regulating valve realizes the rough adjustment of the protective gas pressure, and the ultra-micro pressure reducing valve completes the fine adjustment of the pressure. The two cooperate to quickly stabilize the pressure at the intake end of the main pipeline and can more accurately maintain the back pressure at the exhaust end of the gas online analyzer.

[0012] Optionally, the micro current-limiting unit includes a filter and a flow-limiting orifice plate. The exhaust end of the pressure regulating valve is connected to the filter. The filter is connected to the flow-limiting orifice plate. The exhaust end of the flow-limiting orifice plate is simultaneously connected to the control end of the amplification and pressurization unit and the intake end of the pressure monitoring and adjustment unit.

[0013] By adopting the above technical solution, the filter can intercept particulate matter in the protective gas to prevent the flow-limiting orifice plate from being blocked; the flow-limiting orifice plate accurately controls the flow rate of the protective gas within a small range to form a stable low-pressure control signal. This structure makes the gas delivered to the control end of the amplification and pressurization unit clean and pressure-stable, ensuring that there is no fluctuating interference in the gas signal change, improving the system adjustment accuracy and reliability, making the back pressure control at the exhaust end of the online analyzer more accurate, and such a design makes the conduction of air pressure disturbance have hysteresis, that is, during the process of the gas pressure signal changing and returning to the original value, the gas pressure at the intake end of the flow-limiting orifice plate will not fluctuate, thereby maintaining the stability of the back pressure at the exhaust end of the online analyzer.

[0014] Optionally, a second pressure gauge for monitoring the pressure of the gas after its adjustment is installed on the pressure regulating valve.

[0015] By adopting the above technical solutions, the working state of the pressure regulating valve can be visually displayed, facilitating the quick discovery of abnormal pressure regulation, providing a reference for the pre-pressure of the ultra-micro pressure reducing valve. When the pressure exceeds the set range, it can be promptly detected to prevent subsequent damage to the flow limiting unit and the amplifying and supercharging unit due to abnormal pressure.

[0016] Optionally, the pressure monitoring and regulating unit includes a flow limiting valve. The control end of the flow limiting valve is connected to the exhaust end of the main pipeline. A negative pressure gauge is arranged between the flow limiting valve and the main pipeline. The intake end of the flow limiting valve is connected to the exhaust end of the flow limiting orifice plate, and the exhaust end of the flow limiting valve communicates with the outside atmosphere.

[0017] By adopting the above technical solutions, when the pressure at the discharge port of the ejector pump fluctuates, causing a change in the negative pressure at its suction port, the negative pressure gauge detects the pressure signal in real time and transmits it to the flow limiting valve. The flow limiting valve changes the positive pressure at the exhaust end of the flow limiting orifice plate by adjusting the exhaust flow rate of the protective gas. This positive pressure serves as the adjustment signal for the amplifying and supercharging unit, driving the amplifying and supercharging unit to adjust the power gas pressure of the ejector pump, thereby quickly stabilizing the negative pressure at the suction port and achieving closed-loop automatic regulation.

[0018] Optionally, the monitoring and flow regulating unit includes a differential pressure gauge and a flow meter. Both the differential pressure gauge and the flow meter are arranged on the main pipeline. The pressure regulating unit is located between the intake end of the differential pressure gauge and the intake port of the main pipeline. The pressure monitoring and regulating unit is located between the flow meter and the amplifying and supercharging unit.

[0019] By adopting the above technical solutions, the differential pressure gauge is used to monitor the back pressure of the on-line analytical instrument, and the flow meter is used to regulate the gas flow rate from the main pipeline to the suction port of the ejector pump and can monitor the flow rate value.

[0020] Optionally, a check valve is connected to the intake end of the ejector pump, and the intake end of the check valve is connected to the flow meter.

[0021] By adopting the above technical solutions, the check valve effectively prevents gas backflow during the operation of the ejector pump, ensuring the unidirectional flow of the gas to the intake end of the ejector pump. By arranging the pressure monitoring and regulating unit between the flow meter and the check valve, the gas pressure entering the ejector pump can be monitored in real time and accurately regulated, and feedback regulation is immediately carried out when abnormal pressure is detected.

[0022] Optionally, the filter is a straight-through fine filter.

[0023] By adopting the above technical solutions, it can efficiently intercept particulate impurities in the protective gas, while keeping the flow resistance below 0.01 MPa, ensuring that the flow limiting orifice plate is not contaminated and blocked, and not affecting the response speed of gas flow, so as to keep the pressure and flow rate of the control signal gas stable.

[0024] In summary, the present application includes at least one of the following beneficial technical effects: 1. The micro current limiting divides the protective gas flow and reduces the flow rate. The flow rate at the exhaust end of the monitoring and flow regulation unit is less than that at its intake end. Therefore, there is a lag in the conduction of air pressure disturbances. The pressure monitoring and regulation unit adjusts through a fast feedback mechanism, so that the pressure monitoring and regulation unit will not affect the air pressure of the pressure regulation unit and the air pressure at the intake end of the monitoring and flow regulation unit when adjusting the air pressure, realizing the isolation of the sample gas path and the control signal gas path, reducing the reverse conduction of fluctuations, collecting the tail gas under a constant pressure, and ensuring the normal operation of the analytical instrument; 2. The two-stage decompression structure is adopted. The pressure regulating valve realizes the rough adjustment of the protective gas pressure, and the ultra-micro pressure reducing valve completes the fine adjustment of the pressure. The two cooperate to quickly stabilize the pressure at the intake end of the main pipeline and can more accurately maintain the back pressure at the exhaust end of the gas online analyzer; 3. When the pressure fluctuation at the discharge port of the ejector pump causes the change of the negative pressure at its suction port, the negative pressure gauge detects the pressure signal in real time and transmits it to the flow limiting valve. The flow limiting valve changes the positive pressure at the exhaust end of the flow limiting orifice plate by adjusting the external exhaust flow rate of the protective gas. This positive pressure serves as the adjustment signal of the amplification and pressurization unit, driving the amplification and pressurization unit to adjust the power gas pressure of the ejector pump, thereby quickly stabilizing the negative pressure at the suction port and realizing closed-loop automatic adjustment; 4. The flow rate of the protective gas is accurately limited within a micro range through the flow limiting orifice plate, only providing the necessary control signal gas. Moreover, the pressure monitoring and regulation unit dynamically adjusts the opening degree of the flow limiting valve according to the negative pressure feedback, and only releases a small amount of protective gas to the atmosphere when the external exhaust pressure is abnormal, rather than directly discharging it, avoiding the waste of the protective gas. Description of the Drawings

[0025] Figure 1 is the process schematic diagram of the embodiment of the present application.

[0026] Figure 2 is the structural schematic diagram of the embodiment of the present application for embodying the first pressure gauge, the second pressure gauge, the negative pressure gauge and the differential pressure gauge.

[0027] Figure 3 is the structural schematic diagram of the embodiment of the present application for embodying the first three-way joint and the pressure regulating valve.

[0028] Figure 4 is the structural schematic diagram of the embodiment of the present application for embodying the second three-way joint and the flow limiting valve.

[0029] Description of reference numerals: 1. Pressure regulating unit; 11. Pressure regulating valve; 12. Ultra-micro pressure reducing valve; 2. Monitoring and flow regulating unit; 21. Differential pressure gauge; 22. Flow meter; 3. Amplifying and boosting unit; 31. Gas pressure amplifier; 32. First pressure gauge; 4. Micro-limiting flow unit; 41. Second pressure gauge; 42. Filter; 43. Restriction orifice plate; 44. First three-way joint; 5. Pressure monitoring and regulating unit; 51. Flow limiting valve; 52. Second three-way joint; 53. Negative pressure gauge; 6. Main pipeline; 7. Inlet of protective gas; 8. Check valve; 9. Ejector pump; 10. Housing. Detailed implementation manners

[0030] The following further describes the present application in conjunction with the Figures 1-4 accompanying drawings.

[0031] The embodiment of the present application discloses an exhaust gas recovery system for an on-line analyzer.

[0032] As Figure 1 , the exhaust gas recovery system for an on-line analyzer includes a pressure regulating unit 1, a monitoring and flow regulating unit 2, an amplifying and boosting unit 3, a micro-limiting flow unit 4, a pressure monitoring and regulating unit 5, a main pipeline 6, and an inlet 7 of protective gas; The inlet end of the main pipeline 6 is connected to the exhaust gas main pipe, the branch pipe of the main pipeline 6 is connected to the pressure regulating unit 1, the monitoring and flow regulating unit 2 is installed on the main pipeline 6, the pressure regulating unit 1 is located between the exhaust gas main pipe and the monitoring and flow regulating unit 2, a check valve 8 is installed at the exhaust end of the main pipeline 6, and the check valve 8 is connected to an ejector pump 9; The pressure regulating unit 1 is used to regulate the pressure of the protective gas so that the protective gas with stable pressure is mixed with the exhaust gas of the main pipeline 6 to regulate the air pressure at the inlet end of the main pipeline 6. The pressure regulating unit 1 has the functions of primary regulation and secondary regulation. The primary regulation is used to achieve rough adjustment of the protective gas pressure, and the secondary regulation is used to complete fine pressure adjustment. At the exhaust end of the primary regulation of the pressure regulating unit 1, it is branched and connected to the micro-limiting flow unit 4; The exhaust end of the micro-limiting flow unit 4 is branched into two paths. One path of the exhaust end of the micro-limiting flow unit 4 is connected to the inlet end of the pressure monitoring and regulating unit 5, the exhaust end of the pressure monitoring and regulating unit 5 communicates to the outside, the monitoring and control end of the pressure monitoring and regulating unit 5 is connected to the main pipeline 6, and the monitoring end of the pressure monitoring and regulating unit 5 is located between the check valve 8 and the monitoring and flow regulating unit 2; The other end of the exhaust end of the micro-limiting flow unit 4 is connected to the control end of the amplifying and boosting unit 3, the inlet end of the amplifying and boosting unit 3 is connected to the inlet 7 of protective gas, and the exhaust end of the amplifying and boosting unit 3 is connected to the driving port of the ejector pump 9.

[0033] The monitoring and flow regulating unit 2 is used to detect the air pressure of the main pipeline 6 and regulate the discharge flow rate; The micro flow limiting unit 4 is used to shunt and reduce the flow rate of the protective gas adjusted by the pressure regulating unit 1, and make the limited-flow protective gas serve as the gas signal of the amplification and pressurization unit 3; The pressure monitoring and regulating unit 5 is used to detect the negative pressure at the exhaust end of the main pipeline 6 (i.e., the negative pressure at the suction port of the ejector pump 9), and regulate the flow rate of the protective gas discharged from the micro flow limiting unit 4 to the outside, so as to regulate the gas signal of the micro flow limiting unit 4 (i.e., the pressure of the gas discharged by the micro flow limiting unit 4); The amplification and pressurization unit 3 is used to receive the gas signal of the micro flow limiting unit 4, pressurize the protective gas and discharge it to the ejector pump 9. The ejector pump 9 is used to suck the mixed gas (tail gas and protective gas) of the main pipeline 6, and discharge the protective gas discharged by the amplification and pressurization unit 3 and the mixed gas of the main pipeline 6 together.

[0034] After the protective gas is pressure-regulated by the pressure regulating unit 1, it is mixed with the tail gas, quickly compensates for the sudden change in the intake end pressure, and regulates the back pressure at the exhaust end of the analytical instrument; The back pressure situation at the exhaust end of the analytical instrument is observed through the monitoring and flow regulating unit 2, and the mixed gas is regulated to be discharged to the ejector pump 9 at the required flow rate. The protective gas is also shunted, flows through the amplification and pressurization unit 3 and then through the ejector pump 9, so that the ejector pump 9 sucks the gas in the main pipeline 6 and discharges it together with the pressurized protective gas; When the pressure at the discharge end of the ejector pump 9 fluctuates, the pressure monitoring and regulating unit 5 detects the fluctuation and timely adjusts the pressure of the protective gas passing through the micro flow limiting unit 4, so that the amplification and pressurization unit 3 timely regulates the pressure of the protective gas, thereby changing the entrainment gas flow rate and suction force of the ejector pump 9, quickly offsetting the pressure fluctuation at the discharge end, maintaining the stability of the system back pressure until the pressure detected by the pressure monitoring and regulating unit 5 returns to normal.

[0035] The micro flow limiting shunts and reduces the flow rate of the protective gas, and there is a lag in the conduction of the air pressure disturbance. The pressure monitoring and regulating unit 5 adjusts through a fast feedback mechanism, so that the pressure monitoring and regulating unit 5 will not affect the air pressure of the pressure regulating unit 1 when adjusting the air pressure; Similarly, since the flow rate at the exhaust end of the monitoring and flow regulating unit 2 is less than that at its intake end, there is a lag in the conduction of the air pressure disturbance. The pressure monitoring and regulating unit 5 adjusts through a fast feedback mechanism, so that the pressure monitoring and regulating unit 5 will not affect the air pressure at the intake end of the monitoring and flow regulating unit 2 when adjusting the air pressure. Furthermore, the isolation between the sample gas path and the control signal gas path is realized, the reverse conduction of the fluctuation is reduced, and the tail gas is collected under a constant pressure, ensuring the normal operation of the analytical instrument.

[0036] Such as Figure 1, the amplification and pressurization unit 3 includes a gas pressure amplifier 31. The adjustment end of the gas pressure amplifier 31 is connected to the micro current-limiting unit 4. The air inlet end of the gas pressure amplifier 31 is connected to the protective gas inlet 7. The exhaust end of the gas pressure amplifier 31 is connected to the drive port of the jet pump 9. A first pressure gauge 32 is installed between the gas pressure amplifier 31 and the jet pump 9.

[0037] The pressure adjustment unit 1 includes a pressure regulating valve 11 and an ultra-micro pressure reducing valve 12. The pressure regulating valve 11 has a main air inlet, a main exhaust port, a micro exhaust port, and a pressure gauge interface. The main air inlet of the pressure regulating valve 11 is connected to the protective gas inlet 7. The main exhaust port of the pressure regulating valve 11 is connected to the ultra-micro pressure reducing valve 12. The exhaust end of the ultra-micro pressure reducing valve 12 is connected to a branch of the air inlet end of the main pipeline 6.

[0038] As Figure 1 and Figure 3 , the micro current-limiting unit 4 includes a second pressure gauge 41, a filter 42, and a current-limiting orifice plate 43. The second pressure gauge 41 is connected to the pressure gauge interface of the pressure regulating valve 11. The second pressure gauge 41 is used to detect the gas pressure after the pressure regulating valve 11 is adjusted. The air inlet end of the filter 42 is connected to the micro exhaust port. The filter 42 is a straight-through fine filter 42. The exhaust end of the filter 42 is connected to the current-limiting orifice plate 43. The current-limiting orifice plate 43 is connected to a first three-way joint 44. One exhaust end of the first three-way joint 44 is connected to the adjustment end of the gas pressure amplifier 31, and the other exhaust end of the first three-way joint 44 is connected to the air inlet end of the pressure monitoring and adjustment unit 5.

[0039] As Figure 1 and Figure 4 , the pressure monitoring and adjustment unit 5 includes a flow-limiting valve 51. The control end of the flow-limiting valve 51 is connected to a second three-way joint 52. One end of the second three-way joint 52 is connected to the control end of the flow-limiting valve 51, one end is connected to a negative pressure gauge 53, and one end is connected to the exhaust end of the monitoring and flow adjustment unit 2. The air inlet end of the flow-limiting valve 51 is connected to an exhaust end of the second three-way joint 52 (i.e., an exhaust end of the current-limiting orifice plate 43). The exhaust end of the flow-limiting valve 51 communicates with the outside atmosphere.

[0040] The monitoring and flow adjustment unit 2 includes a differential pressure gauge 21 and a flow meter 22. The flow meter 22 is connected in series on the main pipeline 6. The differential pressure gauge 21 is connected in parallel on the main pipeline 6. The ultra-micro pressure reducing valve 12 is located between the air inlet end of the pipeline connected to the differential pressure gauge 21 and the air inlet of the main pipeline 6. The flow-limiting valve 51 is located between the flow meter 22 and the air pressure amplifier.

[0041] The implementation principle of the embodiment of this application is as follows: The protective gas first passes through the pressure regulating valve 11 for rough adjustment of the protective gas pressure, and then passes through the ultra-micro pressure reducing valve 12 to complete the fine pressure adjustment. At the same time, the tail gas discharged from the tail gas main pipe is mixed with the protective gas that has completed the fine pressure adjustment. The differential pressure gauge 21 monitors the tail gas pressure condition of the main pipe 6 (i.e., the back pressure condition of the on-line analyzer). Then, the mixed gas in the main pipe 6 passes through the flow meter 22 for flow adjustment and is discharged to the suction port of the check valve 8 and the ejector pump 9 in sequence.

[0042] At the same time, another path of the protective gas also passes through the gas pressure amplifier 31 for pressurization, and then is discharged into the driving port of the ejector pump 9, so that the mixed gas in the main pipe 6 and the pressurized protective gas are mixed together and discharged to the torch for combustion treatment.

[0043] When the pressure at the discharge port of the ejector pump 9 fluctuates, the negative pressure gauge 53 monitors the fluctuation and acts on the flow limiting valve 51 with the signal. The opening of the flow limiting valve 51 is dynamically adjusted according to the negative pressure feedback. The flow limiting valve 51 changes the positive pressure at the exhaust end of the orifice plate 43 by adjusting the external discharge flow of the protective gas. This positive pressure serves as the adjustment signal for the gas pressure amplifier 31. The gas pressure amplifier 31 adjusts the air pressure of the pressurized protective gas, thereby adjusting the power gas pressure of the ejector pump 9, and then quickly stabilizing the negative pressure at the suction port to achieve closed-loop automatic adjustment.

[0044] During the process of automatic adjustment, the orifice plate 43 precisely controls the flow of the protective gas within a small range to form a stable low-pressure control signal, and the flow meter 22 also limits the discharge of the mixed gas. This causes a lag in the conduction of the air pressure disturbance. That is, during the entire process from the pressure fluctuation at the discharge port of the ejector pump 9 to its return to normal (i.e., the gas pressure signal changes and then returns to the original value), the gas pressure at the inlet end of the orifice plate 43 does not fluctuate, and thus the back pressure at the exhaust end of the on-line analyzer is maintained stable.

[0045] Such as Figure 2 、 Figure 3 and Figure 4, the tail gas recovery system for on-line analytical instruments further includes a housing 10. The protective gas inlet and the jet pump 9 are both located at one end of the housing 10, and the main pipeline 6 is located at the other end of the housing 10. The protective gas inlet, the exhaust port of the jet pump 9, and the inlet of the main pipeline 6 are all installed at the bottom of the housing 10. The pressure regulating valve 11 and the gas pressure amplifier 31 are installed inside the housing 10, and the pressure regulating valve 11 and the gas pressure amplifier 31 are arranged at the same end as the jet pump 9. The flowmeter 22 and the flow limiting valve 51 are both installed inside the housing 10, and the flowmeter 22 and the flow limiting valve 51 are arranged at the same end as the main pipeline 6. The ultra-micro pressure reducing valve 12 is installed inside the housing 10 and is located in the middle of the housing 10. The adjusting rotations of the pressure regulating valve 11, the ultra-micro pressure reducing valve 12, the flowmeter 22, and the flow limiting valve 51 are all located at the front side of the housing 10. The first pressure gauge 32, the second pressure gauge 41, the negative pressure gauge 53, and the differential pressure gauge 21 are all installed at the front side of the housing 10. The system is integrated, and the staff only needs to observe the data of the corresponding detection gauges from the front side of the housing 10 and directly make adjustments at the front side of the housing 10, which is convenient for adjustment.

[0046] The above are all the preferred embodiments of the present application, and the protection scope of the present application is not limited thereby. Therefore, all equivalent changes made according to the structure, shape, and principle of the present application shall be covered within the protection scope of the present application.

Claims

1. A tail gas recovery system for an online analytical instrument, characterized in that: It comprises a pressure regulating unit (1), a monitoring and flow regulating unit (2), an amplifying and pressurizing unit (3), a micro-current limiting unit (4), a pressure monitoring and regulating unit (5), a main pipeline (6) and a protective gas inlet (7); The main pipeline (6) and the amplifying and pressurizing unit (3) are commonly connected to a jet pump (9); the amplifying and pressurizing unit (3) is connected to the protective gas inlet (7); the amplifying and pressurizing unit (3) is used to pressurize the protective gas and discharge it to the jet pump (9); the gas in the main pipeline (6) is sucked out by the jet pump (9); The monitoring and flow regulating unit (2) is installed on the main pipeline (6) and is used to detect the air pressure of the main pipeline (6) and regulate the discharge flow; The pressure regulating unit (1) is connected to the protective gas inlet (7) and the air inlet end of the main pipeline (6), and the pressure regulating unit (1) is used to regulate the pressure of the protective gas so that the protective gas with stable pressure is mixed with the tail gas of the main pipeline (6) to regulate the air pressure at the air inlet end of the main pipeline (6); The pressure monitoring and regulating unit (5) is arranged at the exhaust end of the main pipeline (6), and the pressure monitoring and regulating unit (5) is also connected to the micro-current limiting unit (4) and the amplifying and boosting unit (3). The micro-current limiting unit (4) is connected to the pressure regulating unit (1). The micro-current limiting unit (4) is used to divert and reduce the flow of the protective gas regulated by the pressure regulating unit (1), and use the limited flow protective gas as the regulating signal of the amplifying and boosting unit (3). The pressure monitoring and regulating unit (5) is used to detect the negative pressure at the exhaust end of the main pipeline (6), and regulate the flow of the protective gas discharged from the micro-current limiting unit (4) to the outside, so as to regulate the protective gas pressure in the micro-current limiting unit (4).

2. The tail gas recovery system for online analytical instruments according to claim 1, characterized in that: The amplifying and pressurizing unit (3) comprises a gas pressure amplifier (31), the regulating end of the gas pressure amplifier (31) is connected to the micro current limiting unit (4), the air inlet end of the gas pressure amplifier (31) is connected to the protective gas inlet (7), the exhaust end of the gas pressure amplifier (31) is connected to the jet pump (9), and a first pressure gauge (32) is provided between the gas pressure amplifier (31) and the jet pump (9).

3. The tail gas recovery system for online analytical instruments according to claim 1, characterized in that: The pressure regulating unit (1) comprises a pressure regulating valve (11) and an ultra-micro-pressure reducing valve (12); an air inlet end of the pressure regulating valve (11) is connected to the protective gas inlet (7); an air outlet end of the pressure regulating valve (11) is connected to the ultra-micro-pressure reducing valve (12); and an air outlet end of the ultra-micro-pressure reducing valve (12) is connected to an air inlet end of the main pipeline (6).

4. The tail gas recovery system for online analysis instrument according to claim 3, characterized in that: The micro current limiting unit (4) comprises a filter (42) and a current limiting orifice (43); the exhaust end of the pressure regulating valve (11) is connected to the filter (42); the filter (42) is connected to the current limiting orifice (43); the exhaust end of the current limiting orifice (43) is simultaneously connected to the control end of the amplifying and boosting unit (3) and the air inlet end of the pressure monitoring and regulating unit (5).

5. The tail gas recovery system for online analysis instrument according to claim 4, characterized in that: The pressure regulating valve (11) is provided with a second pressure gauge (41) for monitoring the pressure of the gas regulated by the pressure regulating valve (11).

6. The tail gas recovery system for online analysis instrument according to claim 4, characterized in that: The pressure monitoring and regulating unit (5) comprises a flow limiting valve (51), a control end of the flow limiting valve (51) is connected to the exhaust end of the main pipeline (6), a negative pressure gauge (53) is provided between the flow limiting valve (51) and the main pipeline (6), an air inlet end of the flow limiting valve (51) is connected to the exhaust end of the flow limiting orifice (43), and the exhaust end of the flow limiting valve (51) is connected to the outside atmosphere.

7. The tail gas recovery system for online analytical instruments according to claim 1, characterized in that: The monitoring and flow regulating unit (2) comprises a differential pressure gauge (21) and a flow meter (22), wherein the differential pressure gauge (21) and the flow meter (22) are both arranged on the main pipeline (6), the pressure regulating unit (1) is located between the air inlet end of the differential pressure gauge (21) and the air inlet of the main pipeline (6), and the pressure monitoring and regulating unit (5) is located between the flow meter (22) and the amplifying and boosting unit (3).

8. The tail gas recovery system for online analysis instrument according to claim 7, characterized in that: The air inlet end of the jet pump (9) is connected to a one-way valve (8), and the air inlet end of the one-way valve (8) is connected to the flow meter (22).

9. The tail gas recovery system for online analysis instrument according to claim 4, characterized in that: The filter (42) is a straight-through fine filter (42).

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