Online analysis system for acetic acid production line

Abstract

The invention relates to an acetic acid production line on-line analysis system, and relates to the field of on-line gas analysis equipment.The acetic acid production line on-line analysis system comprises a pretreatment box and an analysis cabinet, the pretreatment box is connected with an acetic acid production line through a sample feeding pipe and connected with the analysis cabinet through a sample conveying pipe, and a pretreatment module is arranged in the pretreatment box; the pretreatment module comprises a sample pressure reduction unit and a heating unit, the sample pressure reduction unit is connected between the sample feeding pipe and the sample conveying pipe, and the heating unit is arranged adjacent to the sample pressure reduction unit and the sample conveying pipe and is connected with the analysis cabinet; a pretreatment module, an analysis module and a tail gas treatment module are arranged in the analysis cabinet, the pretreatment module comprises a bypass unit and a flow stabilizing unit, the bypass unit is arranged between the sample conveying pipe and the tail gas treatment module, the flow stabilizing unit is connected between the sample conveying pipe and the analysis module, and the tail gas treatment module is connected with the analysis module; the stability and the real-time performance of a sample detection result of an online analysis system can be improved.

Description

Technical Field

[0001] The present application relates to the field of online gas analysis equipment, and in particular to an online analysis system for an acetic acid production line. Background Art

[0002] Acetic acid is an organic compound widely used in the fields of chemical industry, medicine, food, etc. It is often used in food seasoning, drug synthesis, solvent preparation, etc. In industry, acetic acid is usually synthesized by chemical reactions. Among them, the ethylene method is a common method for synthesizing acetic acid in industry. This method firstly oxidizes ethylene to obtain vinyl alcohol, then oxidizes vinyl alcohol to acetaldehyde by oxygenation reaction, and finally oxidizes acetaldehyde to acetic acid by oxygenation reaction. It has the characteristics of high efficiency, high yield and continuous production and is widely used.

[0003] In the process of producing acetic acid by ethylene method, the concentration of oxygen has an important influence on the reaction rate, product purity and production efficiency. Too high or too low oxygen concentration in the production process may lead to unstable production, reduced product quality or increased energy consumption. Real-time monitoring and control of oxygen concentration is of great significance for optimizing the production process, improving product quality and reducing production costs. In order to monitor the oxygen concentration at different stages of the production line in real time, sample gas is usually extracted from different sections of the acetic acid production line and transported to the online analysis equipment for real-time detection of oxygen concentration. The sample gas extracted from the production line not only has a high temperature, but also contains corrosive and flammable gases, so the sample gas needs to be pretreated in the analysis system.

[0004] The existing online analysis system usually only performs simple pretreatment such as decompression and cooling on the sample gas extracted from the acetic acid production line before delivering the sample gas to the analyzer, which not only affects the accuracy of the analyzer's test results, but also easily causes damage to the analyzer. In serious cases, the liquefaction of the flammable gas in the sample gas may cause pipeline blockage or explosion. In addition, the flow rate of the sample gas is usually much larger than the sample volume required for analysis, which will cause the sample gas to be retained in the pipeline, resulting in a delayed gas sample detected by the analyzer. The test results cannot reflect the real-time concentration of oxygen on the production line, and thus cannot accurately and dynamically adjust the oxygen concentration in the production line. Summary of the invention

[0005] In order to improve the stability and real-time performance of sample detection results of an online analysis system, the present application provides an acetic acid production line online analysis system.

[0006] The acetic acid production line online analysis system provided in this application adopts the following technical solutions: An acetic acid production line online analysis system comprises a pretreatment box and an analysis cabinet, wherein the pretreatment box is connected to the acetic acid production line through a sample feeding pipe and is connected to the analysis cabinet through a sample conveying pipe, wherein a pretreatment module is arranged in the pretreatment box, wherein the pretreatment module comprises a sample decompression unit and a heating unit, wherein the sample decompression unit is connected between the sample feeding pipe and the sample conveying pipe, wherein the heating unit is arranged adjacent to the sample decompression unit and the sample conveying pipe and is connected to the analysis cabinet; wherein a pretreatment module, an analysis module and an exhaust gas treatment module are arranged in the analysis cabinet, wherein the pretreatment module comprises a bypass unit and a flow stabilization unit, wherein the bypass unit is arranged between the sample conveying pipe and the exhaust gas treatment module, wherein the flow stabilization unit is connected between the sample conveying pipe and the analysis module, wherein the exhaust gas treatment module is connected to the analysis module so as to be able to recycle the sample gas while maintaining the pressure of the sample gas stable.

[0007] By adopting the above technical scheme, by setting the pretreatment module in the pretreatment box, and setting the pretreatment module, analysis module and exhaust gas treatment module in the analysis cabinet, it is possible to separate the sample gas with higher pressure and temperature from the analysis module, prevent the high-temperature and high-pressure sample gas from affecting the detection accuracy of the analysis instrument, and shorten the transmission path of the high-temperature and high-pressure sample gas, which is beneficial to improving the stability and safety of the analysis system; by using the pretreatment module composed of a bypass unit and a flow stabilization unit, while ensuring the stability of the sample gas flow transmitted to the analysis module, the excess sample gas can be transported to the exhaust gas treatment module through the bypass for treatment, preventing the sample gas from being retained in the transmission pipeline, and improving the stability and real-time performance of the sample gas transmitted to the analysis module; by using the exhaust gas treatment module to maintain the stability of the sample gas pressure flowing out of the analysis module, it is possible to improve the stability of the sample gas back pressure detected in the analysis module, and ensure the accuracy of the oxygen concentration detection by the analysis module.

[0008] In a specific possible implementation scheme, the sample pressure reducing unit includes a pre-filter and a sample pressure reducing valve, the inlet of the pre-filter is connected to the sample feed pipe, and the sample pressure reducing valve is connected between the outlet of the pre-filter and the sample delivery pipe; the heating unit includes a first steam accompanying pipeline and a second steam accompanying pipeline, the first steam accompanying pipeline is arranged along the sample pressure reducing valve, the pre-filter and the sample feed pipe, and the second steam accompanying pipeline is arranged along the sample delivery pipe and connected to the analysis cabinet.

[0009] By adopting the above technical scheme, by using a sample pressure reducing valve arranged between the sample feed pipe and the sample delivery pipe and a pre-filter arranged at the front end of the sample pressure reducing valve, it is possible to filter out the condensed liquid of the sample gas and the solid impurities mixed in the sample gas, and after the sample gas is decompressed, a lower pressure is formed to deliver it to the analysis module, thereby improving the safety of sample gas delivery and reducing the risk of sample gas leakage; by using a first steam accompanying pipeline arranged along the sample pressure reducing valve, the pre-filter and the sample feed pipe, and a second steam accompanying pipeline arranged along the sample delivery pipe, it is possible to heat the sample gas during the transmission and decompression process, thereby preventing the sample gas temperature from dropping during the transmission process, and preventing the temperature drop during the decompression process from making it easier for high-boiling point components in the sample gas, such as acetic acid, to condense into liquid, thereby affecting the transmission of the sample gas and even blocking the delivery pipeline, thereby ensuring the stability and safety of the sample gas delivery pipeline.

[0010] In a specific feasible implementation scheme, a steam input interface and a steam condensate return interface are provided on the pretreatment box, one end of the first steam accompanying pipeline is connected to the steam input interface, and the other end is connected to the steam condensate return interface, a first steam regulating valve is connected between the first steam accompanying pipeline and the steam input interface, the second steam accompanying pipeline is connected to the steam input interface, and a second steam regulating valve is connected between the second steam accompanying pipeline and the steam input interface; the heating unit also includes a pretreatment box heating pipe, which is arranged in the pretreatment box, one end of the pretreatment box heating pipe is connected to the steam input interface, and the other end is connected to the steam condensate return interface, a third steam regulating valve is connected between the pretreatment box heating pipe and the steam input interface, and a second steam trap is connected between the pretreatment box heating pipe and the steam condensate return interface.

[0011] By adopting the above technical scheme, the space inside the entire pretreatment box can be heated by utilizing the pretreatment box heating pipe arranged in the pretreatment box, thereby ensuring the heating effect of the pretreatment module and its connecting pipelines; by utilizing the first steam trap arranged between the first steam accompanying pipeline and the steam condensate return interface, and the second steam trap arranged between the pretreatment box heating pipe and the steam condensate return interface, liquid water formed by steam condensation in the first steam accompanying pipeline and the pretreatment box heating pipe can be removed, thereby ensuring the heating effect of the first steam accompanying pipeline and the pretreatment box heating pipe.

[0012] In a specific feasible implementation scheme, an analysis chamber and a pretreatment chamber are provided in the analysis cabinet, the pretreatment module and the exhaust gas treatment module are provided in the pretreatment chamber, the analysis module is provided in the analysis chamber, the pretreatment chamber is also provided with a pretreatment chamber heating pipe, the pretreatment chamber heating pipe is connected to the heating unit, a cooling unit is provided in the analysis chamber, the cooling unit includes an instrument air interface, an instrument air pressure reducing valve and a vortex cooler, the air inlet of the instrument air pressure reducing valve is connected to the instrument air interface, the air outlet opens in the analysis chamber, and the vortex cooler is provided on the outer wall of the analysis chamber and communicates with the internal space of the analysis chamber.

[0013] By adopting the above technical scheme, the analysis chamber and the pretreatment chamber are isolated from each other in the analysis cabinet, and the analysis module can be arranged in the pretreatment chamber, while the pretreatment module and the exhaust gas treatment module are arranged in the pretreatment chamber, so as to realize the separation of the analysis module from the pretreatment module and the exhaust gas treatment module, thereby reducing the influence of the pretreatment module and the exhaust gas treatment module on the analysis module and improving the accuracy of the detection result of the analysis module; by using the pretreatment chamber heating tube arranged in the pretreatment chamber, the overall temperature in the pretreatment chamber can be increased to prevent the condensation of high-boiling point components in the sample gas in the sample conveying pipeline; by using the instrument air pressure reducing valve and the vortex cooler arranged in the analysis chamber, instrument air can be injected into the analysis chamber to form a positive pressure, and a vortex airflow can be formed in the vortex cooler to produce a cooling effect, thereby preventing the high temperature in the pretreatment chamber from causing an excessive increase in the temperature in the analysis chamber, and ensuring the accuracy of the detection result of the analysis module.

[0014] In a specific implementation scheme, the pretreatment module also includes a bypass filter, the inlet of the bypass filter is connected to the sample delivery tube, the bypass port of the bypass filter is connected to the bypass unit, and the outlet of the bypass filter is connected to the flow stabilization unit.

[0015] By adopting the above technical solution, using the bypass filter arranged between the sample delivery pipe and the bypass unit and the flow stabilization unit, part of the filtered sample gas can be transmitted to the flow stabilization unit for pressure adjustment and component detection, and the unfiltered sample gas is transmitted to the exhaust gas treatment module through the bypass unit for treatment, ensuring that the sample gas is delivered to the analysis module in time through the flow stabilization unit, preventing excessive sample gas from being retained and delayed in the delivery pipeline, and improving the timeliness of oxygen concentration detection of the sample gas.

[0016] In a specific implementation scheme, the exhaust gas treatment module includes a nitrogen input interface, a first nitrogen pressure reducing valve, a nitrogen preheating pipe, a jet pump, an exhaust gas incineration interface, a buffer tank and a back pressure valve, the inlet of the first nitrogen pressure reducing valve is connected to the nitrogen input interface, and the outlet is connected to the nitrogen preheating pipe, the inlet of the jet pump is connected to the nitrogen preheating pipe, the outlet is connected to the exhaust gas incineration interface, the suction port is connected to the buffer tank, the buffer tank is connected to the back pressure valve, and the back pressure valve is connected to the analysis module.

[0017] By adopting the above technical scheme, a nitrogen flow with stable pressure can be formed by utilizing the first nitrogen pressure reducing valve connected to the nitrogen input interface, and the exhaust gas detected by the analysis module is sucked by the jet pump to actively recover the sample exhaust gas; the buffer tank and the back pressure valve arranged between the suction port of the jet pump and the analysis module can buffer the pressure fluctuation of the suction port of the jet pump, improve the stability of the sample exhaust gas pressure in the sample exhaust gas recovery pipeline connected to the analysis module, form a stable back pressure of the sample gas in the analysis module, and further ensure the detection accuracy of the analysis module for the oxygen concentration in the sample gas.

[0018] In a specific feasible implementation scheme, the bypass unit includes a bypass regulating valve, a bypass flowmeter, a normally open switch valve and a normally closed switch valve, one end of the bypass regulating valve is connected to the bypass port of the bypass filter, and the other end is connected to the bypass flowmeter, the normally open switch valve is arranged between the bypass flowmeter and the buffer tank, and the normally closed switch valve is arranged between the bypass flowmeter and the outlet of the jet pump.

[0019] By adopting the above technical scheme, the bypass regulating valve and bypass flowmeter connected to the bypass port of the bypass filter can be used to adjust and observe the flow of the sample gas flowing out through the bypass unit, thereby improving the real-time performance of the sample gas detection while ensuring that the sample flow delivered to the analysis module meets the detection requirements; by using the normally open switch valve arranged between the bypass flowmeter and the buffer tank, and the normally closed switch valve arranged between the bypass flowmeter and the outlet of the jet pump, the sample gas flowing out through the bypass unit can be delivered to the buffer tank through the normally open switch valve under normal conditions, thereby improving the stability of the pressure in the buffer tank; and when the exhaust gas treatment module fails and causes the exhaust gas pressure of the analysis module to be too high, the sample gas diverted through the bypass unit will be directly delivered to the exhaust gas incineration interface through the normally closed switch valve, thereby alleviating the further increase of the sample gas pressure in the analysis module.

[0020] In a specific possible implementation scheme, the flow stabilization unit includes a sample flow regulating valve, a sample flow meter, a pneumatic switching valve and a filter, the sample flow regulating valve is connected to the outlet of the bypass filter, the sample flow meter is connected between the sample flow regulating valve and the inlet of the pneumatic switching valve, the outlet of the pneumatic switching valve is connected to the filter, the control port of the pneumatic switching valve is connected to the reference gas circuit of the analysis module, the filter is connected to the analysis module, and an electric heating insulation belt is arranged on the connecting pipeline between the filter and the analysis module.

[0021] By adopting the above technical solution, using the sample flow regulating valve and sample flow meter arranged between the filter outlet of the bypass filter and the pneumatic switch valve, it is possible to adjust and observe the flow of the sample gas delivered to the analysis module, thereby ensuring that the sample gas flow delivered to the analysis module meets the detection requirements; using the pneumatic switch valve arranged on the sample gas channel of the analysis module, it is possible to link the supply of sample gas with the reference gas supply of the analysis module, thereby ensuring the supply of sample gas when the analysis module is working normally, thereby preventing invalid input of sample gas.

[0022] In a specific feasible implementation scheme, the analysis module includes an analyzer and a purge explosion-proof unit, the analyzer is connected to the flow stabilization unit and the exhaust gas treatment module, an emergency discharge unit is arranged on the connecting pipeline between the analyzer and the exhaust gas treatment module, and the emergency discharge unit is connected to the outside of the analysis cabinet; the purge explosion-proof unit is arranged adjacent to the analyzer, and includes a second nitrogen pressure reducing valve and a purge, the inlet of the second nitrogen pressure reducing valve is connected to the nitrogen input interface arranged on the analysis cabinet, and the outlet is connected to the purge, the purge is connected to the analyzer, and the discharge pipe of the purge opens to the outside of the analysis cabinet.

[0023] By adopting the above technical scheme, by utilizing the emergency discharge unit arranged on the connecting pipeline between the analyzer and the exhaust gas treatment module, the exhaust gas of the analyzer can be discharged through the emergency discharge unit when a failure occurs in the exhaust gas treatment module, thereby ensuring the continuous and stable detection work of the analyzer; by utilizing the purge device connected to the analyzer, the nitrogen from the second nitrogen pressure reducing valve can be used to continuously suck the inside of the analyzer, thereby preventing the accumulation of flammable gas due to the leakage of sample gas in the analyzer, and the leaked gas can be diluted and discharged from the analysis cabinet, thereby preventing the accumulation of sample gas due to the leakage of sample gas, and preventing the pressure in the analyzer and the analysis cabinet from being too high, thereby ensuring the safety of the online analysis system.

[0024] In a specific feasible implementation scheme, the analysis module also includes a calibration unit, which includes a zero gas interface, a range gas interface, a calibration pressure reducing valve and a calibration three-way valve. The zero gas interface and the range gas interface are both arranged on the analysis cabinet, the zero gas interface is connected to the analyzer and the calibration pressure reducing valve, a sample passage three-way valve is arranged between the bypass unit and the flow stabilization unit, and the calibration three-way valve is respectively connected to the calibration pressure reducing valve, the range gas interface and the sample passage three-way valve.

[0025] By adopting the above technical scheme, by utilizing the reference and zero gas interface and the span gas interface arranged on the analysis cabinet, the span gas and the zero gas can be introduced respectively when the analyzer is regularly calibrated, and the span point and the zero point of the analyzer can be adjusted; and when the sample gas is detected, the reference gas can be introduced, and the concentration of oxygen in the sample gas can be detected by comparison with the reference gas; by utilizing the calibration pressure reducing valve arranged between the reference and zero gas interface, the zero gas can be decompressed and then transported to the analyzer through the calibration three-way valve, the sample passage three-way valve and the flow stabilization unit, so as to calibrate the detection zero point of the analyzer.

[0026] In summary, the present application includes at least one of the following beneficial technical effects: By arranging the pretreatment module in the pretreatment box, and arranging the pretreatment module, the analysis module and the tail gas treatment module in the analysis cabinet, the high temperature and high pressure pretreatment module and the pretreatment module, the analysis module and the tail gas treatment module are separated, so as to prevent the high temperature and high pressure of the pretreatment module from affecting the analysis module, ensure the accuracy and stability of the detection results of the analysis module, shorten the transmission distance of the high temperature and high pressure sample gas, and improve the safety of the online analysis system; The sample pressure reducing valve is used to greatly reduce the pressure of the sample gas, and the sample flow regulating valve is used to accurately control the flow of the sample gas, thereby improving the stability of the pressure and flow of the sample gas entering the analyzer. The back pressure valve is used to improve the stability of the pressure of the sample tail gas flowing out of the analyzer, thereby ensuring the stability and accuracy of the analyzer's test results. The bypass unit is set to bypass the excess sample gas to prevent the sample gas from being retained in the pipeline, thereby improving the timeliness of the sample gas detection. By means of a pretreatment box heating tube arranged in the pretreatment box, a pretreatment chamber heating tube arranged in the pretreatment chamber, a first steam accompanying pipeline arranged along the sample pressure reducing valve, the prefilter and the sample feeding pipe, and a second steam accompanying pipeline arranged along the sample conveying pipe, the sample gas in the process of pressure reduction and conveying can be heated to prevent the condensation of high-boiling-point components in the sample due to the decrease in sample gas temperature during the conveying process and the pressure reduction process, thereby affecting the smooth flow of the sample gas conveying channel and even causing the blockage of the sample gas conveying channel, thereby improving the stability and safety of the sample gas conveying; By setting up an emergency exhaust unit and a purge explosion-proof unit, the sample exhaust gas generated by the analyzer detection and the sample gas leaked in the analyzer are discharged to the outside of the analysis cabinet. This can ensure the normal operation of the analyzer while ensuring the smooth flow of the sample gas, prevent the accumulation of leaked sample gas in the analysis cabinet, and ensure the safety of the online analysis system. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of an embodiment of the present application.

[0028] Figure 2 This is a partial schematic diagram of the pre-processing box in one embodiment of the present application.

[0029] Figure 3 This is a schematic diagram of a pre-treatment box in one embodiment of the present application.

[0030] Figure 4 This is a schematic diagram of the internal structure of a pre-processing box in one embodiment of the present application.

[0031] Figure 5 A schematic diagram of a cabinet portion is analyzed in one embodiment of the present application.

[0032] Figure 6 A schematic diagram of an analysis cabinet in one embodiment of the present application.

[0033] Figure 7 A schematic diagram of the internal structure of a cabinet is analyzed in one embodiment of the present application.

[0034] Figure 8 This is a schematic diagram of the back side of an analysis cabinet in one embodiment of the present application.

[0035] Explanation of reference numerals: 1. pretreatment box; 11. sample feed pipe; 12. sample delivery pipe; 13. steam input interface; 14. steam condensate return interface; 15. pretreatment sample input interface; 16. pretreatment sample output interface; 2. analysis cabinet; 21. analysis chamber; 22. pretreatment chamber; 221. pretreatment chamber heating pipe; 222. third steam trap; 23. cooling unit; 231. instrument air interface; 232. instrument air pressure reducing valve; 233. vortex cooler; 24. analysis sample input interface; 25. cabinet condensate return interface; 26. drain port; 3. pretreatment module; 31. sample pressure reducing unit; 311. prefilter; 312. sample pressure reducing valve; 32. heating unit; 321. first steam accompanying pipeline; 322. second steam accompanying pipeline; 323, first steam regulating valve; 324, first steam trap; 325, second steam regulating valve; 326, pre-treatment box heating pipe; 327, third steam regulating valve; 328, second steam trap; 4, pre-treatment module; 41, bypass unit; 411, bypass regulating valve; 412, bypass flow meter; 413, normally open switch valve; 414, normally closed switch valve; 42, flow stabilization unit; 421, sample flow regulating valve; 422, sample flow meter; 423, pneumatic switch valve; 424, filter; 43, bypass filter device; 44, sample passage three-way valve; 5, analysis module; 51, analyzer; 511, emergency discharge unit; 52, purge explosion-proof unit; 521, second nitrogen pressure reducing valve; 522, purge device; 53, calibration unit; 531, reference zero gas interface; 532, range gas interface; 533, calibration pressure reducing valve; 534, calibration three-way valve; 6, tail gas treatment module; 61, nitrogen input interface; 62, first nitrogen pressure reducing valve; 63, nitrogen preheating tube; 64, jet pump; 65, tail gas incineration interface; 66, buffer tank; 67, back pressure valve. DETAILED DESCRIPTION

[0036] The specific implementation of the present application is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present application, and is not used to limit the present application.

[0037] The terms "first", "second" and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features defined as "first", "second" and "third" may explicitly or implicitly include one or more of the said features.

[0038] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0039] An embodiment of the online analysis system of the acetic acid production line of the present application is as follows: Figures 1 to 8 As shown, it includes a pretreatment box 1 and an analysis cabinet 2. The pretreatment box 1 is set in the vicinity of the acetic acid production line and is connected to the sample gas sampling mechanism on the acetic acid production line through a sample feeding pipe 11. It is used to receive the sample gas with high pressure and high temperature extracted from the acetic acid production line by the sample gas sampling mechanism for preliminary treatment, greatly reduce the pressure of the sample gas, and stabilize the temperature of the sample gas at a lower level. The pretreatment box 1 is connected to the analysis cabinet 2 through a sample delivery pipe 12, and the pretreated sample gas is delivered to the analysis cabinet 2 for oxygen concentration detection. The analysis cabinet 2 is set at a distance from the pretreatment box 1, which can reduce the impact of the high-temperature treatment process in the pretreatment box 1 on the detection accuracy of the analytical instrument and ensure the safety of the detection process.

[0040] A pre-processing module 3 is provided in the pre-processing box 1, and the pre-processing module 3 includes a sample decompression unit 31 and a heating unit 32. Since the sample gas extracted from a certain section of the acetic acid production line is usually at the same pressure and temperature as that in the section of the acetic acid production line, the pressure and temperature are usually high, which exceeds the range that the analytical instrument can withstand. The sample decompression unit 31 is connected between the sample feed pipe 11 and the sample delivery pipe 12, and can reduce the pressure of the sample gas extracted from the acetic acid production line and transmitted in the sample feed pipe 11.

[0041] Since the sample gas contains a certain amount of acetic acid, and the boiling point of acetic acid at normal pressure is as high as 117.9°C, and the boiling point under high pressure is even higher, when the temperature of the sample gas drops below the boiling point of acetic acid, the acetic acid in the sample gas will liquefy to form liquid acetic acid, which will not only occupy the flow channel of the sample gas, but also easily accumulate in the low position area of ​​the channel to cause channel blockage, affect the transmission of the sample gas and even cause safety risks. The heating unit 32 is arranged adjacent to the sample decompression unit 31, the sample feeding pipe 11 and the sample delivery pipe 12, and is connected to the analysis cabinet 2 along with the sample delivery pipe 12, and is used to heat the sample gas in the sample decompression unit 31 and the sample feeding pipe 11 and the sample delivery pipe 12, while ensuring that the acetic acid in the sample gas remains in a gaseous state, the sample gas is stabilized at a lower temperature level, so that the temperature of the sample gas is neither too high nor excessively reduced due to pressure reduction and transmission, causing high boiling point components in the sample gas, such as acetic acid, to condense into liquid, thereby ensuring the normal detection of the sample gas.

[0042] The analysis cabinet 2 is provided with a pretreatment module 4, an analysis module 5 and an exhaust gas treatment module 6. The pretreatment module 4 is used for further processing the sample gas to improve the stability of the sample gas pressure and flow rate, as well as the timeliness of the sample gas transmission; the analysis module 5 is connected to the pretreatment module 4 and is used for analyzing and detecting the oxygen concentration of the sample gas; the exhaust gas treatment module 6 is connected to the analysis module 5 and is used for processing the exhaust gas of the sample gas after detection by the analysis module 5 to prevent the harmful components therein from being discharged into the air and causing air pollution.

[0043] The pretreatment module 4 includes a bypass unit 41 and a flow stabilization unit 42. The bypass unit 41 is connected between the sample delivery pipe 12 and the exhaust gas treatment module 6. It can directly bypass and deliver part of the sample gas delivered by the sample delivery pipe 12 to the exhaust gas treatment module 6 for treatment and discharge, thereby ensuring that the flow rate of the sample gas entering the flow stabilization unit 42 is consistent with the demand for the sample gas by the analysis module 5, and preventing the supply flow rate of the sample gas from exceeding the processing capacity of the analysis module 5, resulting in a large amount of sample gas being retained in the pipeline, so that the time delay between the analysis result of the analysis module 5 and the real-time oxygen concentration in the acetic acid production line is too long, and the reference value for adjusting the oxygen concentration in the acetic acid production line is lost.

[0044] The flow stabilization unit 42 is connected between the sample delivery tube 12 and the analysis module 5, and can accurately control the flow rate of the output sample gas, so that the sample gas is delivered to the analysis module 5 at a stable flow rate under a stable pressure state, thereby ensuring the accuracy of the oxygen concentration detection result in the sample gas by the analysis module 5.

[0045] The tail gas treatment module 6 is connected to the analysis module 5, and is used to actively discharge the sample tail gas formed by the sample gas detected by the analysis module 5 from the analysis cabinet 2, and transport it to the incineration mechanism for incineration treatment, or transport it to the filtering mechanism for filtering and absorbing the harmful components therein with a specific treatment agent. The tail gas treatment module 6 can use various suitable power drive devices to suck and transport the sample tail gas, so as to ensure the pressure of the sample tail gas discharged from the analysis module 5 is stable, form a stable back pressure in the analysis module 5, and ensure the accuracy of the oxygen concentration detection result of the analysis module 5 in the sample gas.

[0046] In some embodiments of the acetic acid production line online analysis system of the present application, Figures 2 to 4 As shown, the sample decompression unit 31 includes a pre-filter 311 and a sample decompression valve 312. The inlet of the pre-filter 311 is connected to the sample feeding pipe 11, and the outlet is connected to the sample decompression valve 312. A switch valve for cutting off the channel for delivering sample gas to the forward processing module 3 may also be provided between the pre-filter 311 and the sample feeding pipe 11. The pre-filter 311 may be selected from a variety of materials that can filter out solid particles in the sample gas to prevent the solid particles from adhering to the sample gas delivery pipeline and affecting the smooth flow of the pipeline; or entering the analysis module 5 and affecting the normal operation of the analysis module 5.

[0047] The sample pressure reducing valve 312 is connected between the pre-filter 311 and the sample delivery tube 12, and can reduce the pressure of the sample gas in the sample feed tube 11, so that the pressure of the sample gas entering the sample delivery tube 12 is greatly reduced, and is transmitted to the analysis cabinet 2 at a lower pressure.

[0048] The heating unit 32 includes a first steam accompanying pipeline 321 and a second steam accompanying pipeline 322. Using steam as a heat source to heat the pretreatment module 3 and the sample gas delivery pipeline can heat the sample gas to a temperature above the boiling point of acetic acid, while ensuring that the temperature of the heat source is not too high and avoiding the formation of open flames, thereby preventing the deflagration of flammable components in the sample gas and ensuring the safety of the analysis system.

[0049] The first steam accompanying pipeline 321 is arranged along the sample pressure reducing valve 312, the pre-filter 311 and the sample feeding tube 11, and can heat the sample pressure reducing valve 312, the pre-filter 311 and the sample feeding tube 11 to prevent the boiling point of the sample gas from increasing under high pressure and liquefying into liquid at a higher temperature. In particular, heat will be absorbed during the pressure reduction process of the sample gas, causing the temperature of the sample gas to drop, which is more likely to cause condensation of high-boiling point components in the sample gas. The heating of the first steam accompanying pipeline 321 can prevent the temperature of the sample pressure reducing valve 312 from dropping, and keep the temperature of the pre-filter 311 and the sample feeding tube 11 above the boiling point of acetic acid in the sample gas, preventing the condensation of acetic acid into liquid and blocking the transmission pipeline.

[0050] The second steam accompanying pipeline 322 is arranged along the sample delivery pipe 12, and is used to heat the sample delivery pipe 12 to prevent the sample gas temperature from dropping and causing acetic acid condensation. The second steam accompanying pipeline 322 and the sample delivery pipe 12 are connected from the pretreatment box 1 to the analysis cabinet 2, and enter the analysis cabinet 2 to provide a heat source for the components in the analysis cabinet 2 that need to be heated.

[0051] In a preferred embodiment of the acetic acid production line online analysis system of the present application, as Figure 3 and Figure 4 As shown, the pretreatment box 1 is connected with a steam input interface 13 and a steam condensate return interface 14. The steam input interface 13 is connected to the first steam accompanying pipeline 321 and the second steam accompanying pipeline 322 through a three-way joint. The first steam accompanying pipeline 321 and the second steam accompanying pipeline 322 usually use metal pipes to facilitate the heat of the steam in the pipeline to be transferred through the pipe wall to heat the sample gas delivery pipeline. A first steam regulating valve 323 is connected between the first steam accompanying pipeline 321 and the steam input interface 13, and a second steam regulating valve 325 is connected between the second steam accompanying pipeline 322 and the steam input interface 13. The first steam regulating valve 323 and the second steam regulating valve 325 usually use needle valves, which is conducive to improving the regulation accuracy of the steam flow.

[0052] The first steam accompanying pipeline 321 passes through the side wall of the pretreatment box 1 and enters the pretreatment box 1, accompanies the sample delivery pipe 12 and the sample feed pipe 11, and passes through the shell of the sample pressure reducing valve 312 to enter the sample pressure reducing valve 312, fully heating the sample pressure reducing valve 312 to prevent the sample gas from absorbing heat due to pressure reduction, which causes the temperature of the sample pressure reducing valve 312 to drop. A pretreatment sample input interface 15 and a pretreatment sample output interface 16 are provided on the side wall of the pretreatment box 1. The sample feed pipe 11 passes through the pretreatment sample input interface 15 and enters the pretreatment box 1, and is connected to the prefilter 311. The first steam accompanying pipeline 321 passes through the pretreatment sample input interface 15 and accompanies the sample feed pipe 11, bends to leave the sample feed pipe 11 at the sample gas sampling mechanism, and is connected to the steam condensate return interface 14. A first steam trap 324 is connected between the first steam accompanying pipeline 321 and the steam condensate return interface 14 . The first steam trap 324 can remove moisture formed by steam condensation in the first steam accompanying pipeline 321 , thereby ensuring smooth flow of the first steam accompanying pipeline 321 .

[0053] The second steam accompanying pipeline 322 passes through the side wall of the pre-processing box 1 into the pre-processing box 1 , and passes through the pre-processing sample output interface 16 along with the sample delivery pipe 12 to reach the outside of the pre-processing box 1 , and extends and is connected to the analysis cabinet 2 .

[0054] The heating unit 32 also includes a pre-treatment box heating pipe 326, which is arranged in the pre-treatment box 1 and is used to heat the space in the pre-treatment box 1 to increase the overall temperature inside the pre-treatment box 1. One end of the pre-treatment box heating pipe 326 passes through the side wall of the pre-treatment box 1 and is connected to the steam input interface 13, and the other end passes through the side wall of the pre-treatment box 1 at different positions and is connected to the steam condensate return interface 14. A third steam regulating valve 327 is connected between the pre-treatment box heating pipe 326 and the steam input interface 13. The third steam regulating valve 327 also uses a needle valve. The third steam regulating valve 327 can be used to adjust the steam flow through the pre-treatment box heating pipe 326, thereby controlling the heating temperature of the pre-treatment box heating pipe 326. A second steam trap 328 is connected between the pre-treatment box heating pipe 326 and the steam condensate return interface 14. The second steam trap 328 can discharge the moisture formed by the condensation of steam in the pre-treatment box heating pipe 326 to ensure the smooth flow of the pre-treatment box heating pipe 326.

[0055] In some embodiments of the acetic acid production line online analysis system of the present application, Figures 5 to 8As shown, the inner space of the analysis cabinet 2 is divided into an analysis chamber 21 and a pretreatment chamber 22 which are isolated from each other. The pretreatment module 4 and the exhaust gas treatment module 6 are arranged in the pretreatment chamber 22, and the analysis module 5 is arranged in the analysis chamber 21. The isolation between the analysis chamber 21 and the pretreatment chamber 22 can form a relatively suitable detection environment in the analysis cabinet 2, eliminate the influence of the high temperature and high humidity environment of the pretreatment module 4 and the exhaust gas treatment module 6 on the analysis module 5, and ensure the detection accuracy of the analysis module 5.

[0056] An analysis sample input interface 24 is provided on the side wall of the analysis cabinet 2 of the pretreatment chamber 22, and the second steam accompanying pipeline 322 and the sample delivery pipe 12 pass through the analysis sample input interface 24 to enter the pretreatment chamber 22. A pretreatment chamber heating pipe 221 is also provided in the pretreatment chamber 22, and the pretreatment chamber heating pipe 221 is used to heat the space in the pretreatment chamber 22. A cabinet condensate return interface 25 is also provided on the side wall of the analysis cabinet 2 of the pretreatment chamber 22, one end of the pretreatment chamber heating pipe 221 is connected to the second steam accompanying pipeline 322, and the other end is connected to the cabinet condensate return interface 25, and a third steam trap 222 is provided between the pretreatment chamber heating pipe 221 and the cabinet condensate return interface 25, and the third steam trap 222 is used to discharge the moisture formed by the condensation of steam in the pretreatment chamber heating pipe 221 to ensure the unblocked pretreatment chamber heating pipe 221.

[0057] A cooling unit 23 is provided in the analysis chamber 21, and the cooling unit 23 includes an instrument air interface 231, an instrument air pressure reducing valve 232, and a vortex cooler 233. The instrument air interface 231 is provided on the side wall of the analysis cabinet 2 at a portion opposite to the analysis chamber 21, and is used to connect to an external instrument air source. The air inlet of the instrument air pressure reducing valve 232 is connected to the instrument air interface 231, and is used to reduce the pressure of the instrument air provided by the instrument air source. The air outlet of the instrument air pressure reducing valve 232 opens in the analysis chamber 21, and discharges the reduced pressure instrument air into the analysis chamber 21, forming a positive pressure in the analysis chamber 21. The vortex cooler 233 can use various existing vortex coolers, such as the Weier vortex cooler. The vortex cooler 233 is installed on the outer wall of the analysis chamber 21 and is connected to the internal space of the analysis chamber 21. It can use the positive pressure in the analysis chamber 21 to generate a vortex airflow, thereby generating a cooling effect to lower the temperature in the analysis chamber 21, and prevent the temperature in the analysis chamber 21 from rising due to the heat in the pretreatment chamber 22, thereby ensuring the detection accuracy of the analysis module 5 and the stability of the detection results.

[0058] In a preferred embodiment of the acetic acid production line online analysis system of the present application, as Figures 5 to 7As shown, the pretreatment module 4 also includes a bypass filter 43. The inlet of the bypass filter 43 is connected to the sample delivery tube 12, and a switch ball valve can be provided between the bypass filter 43 and the sample delivery tube 12, and the switch ball valve is used to control whether the sample gas in the sample delivery tube 12 enters the pretreatment module 4. The bypass port of the bypass filter 43 is connected to the bypass unit 41, and part of the sample gas that has not been filtered by the bypass filter 43 is directly delivered to the exhaust gas treatment module 6 through the bypass unit 41 for treatment; the outlet of the bypass filter 43 is connected to the flow stabilization unit 42, and part of the sample gas filtered by the bypass filter 43 is stabilized by the flow stabilization unit 42 to form a stable pressure and flow and is transmitted to the analysis module 5 for oxygen concentration detection, thereby ensuring the detection accuracy of the analysis module 5. The bypass filter 43 can reduce the filtering flow of the sample gas and improve the filtering effect of the sample gas delivered to the analysis module 5.

[0059] In a preferred embodiment of the acetic acid production line online analysis system of the present application, as Figures 5 to 7 As shown, the tail gas treatment module 6 includes a nitrogen input interface 61, a first nitrogen pressure reducing valve 62, a nitrogen preheating pipe 63, a jet pump 64, a tail gas incineration interface 65, a buffer tank 66 and a back pressure valve 67. The nitrogen input interface 61 is fixed to the side wall of the analysis cabinet 2 opposite to the analysis chamber 21, and is used to connect to the gas source of the external factory nitrogen to introduce the external factory nitrogen.

[0060] The inlet of the first nitrogen pressure reducing valve 62 is connected to the nitrogen input interface 61, and a switch valve may be provided between the first nitrogen pressure reducing valve 62 and the nitrogen input interface 61 to control the on-off of the nitrogen delivered to the tail gas treatment module 6. The outlet of the first nitrogen pressure reducing valve 62 is connected to the nitrogen preheating pipe 63 in the pretreatment chamber 22 through a nitrogen pipeline. The nitrogen preheating pipe 63 usually uses a spiral copper pipe, and of course other shapes of tortuous and spiral metal pipes can also be used. The high temperature environment in the pretreatment chamber 22 is used to perform heat exchange with the nitrogen in the nitrogen preheating pipe 63, and the nitrogen is heated to a temperature equivalent to that of the sample gas, so as to prevent the addition of nitrogen from causing the sample gas and the sample tail gas formed by the sample gas to decrease in temperature, resulting in liquefaction of acetic acid therein.

[0061] The inlet of the jet pump 64 is connected to the nitrogen preheating pipe 63, the outlet of the jet pump 64 is connected to the tail gas incineration interface 65 arranged on the side wall of the analysis cabinet 2, and the suction port of the jet pump 64 is connected to the buffer tank 66. The pressure of the nitrogen from the nitrogen preheating pipe 63 can form a high-speed airflow inside the jet pump 64, and the sample gas temporarily stored in the buffer tank 66 and the sample tail gas after detection are sucked through the suction port, mixed with nitrogen, and then transported to the tail gas incineration interface 65 through its outlet, and then transported to the incineration treatment device outside the pretreatment chamber 22 for incineration treatment, so as to prevent the harmful components therein from polluting the air.

[0062] The buffer tank 66 is connected to the back pressure valve 67, and can temporarily store the sample tail gas sent to the jet pump 64 to wait for processing, which is beneficial to improve the stability of the pressure of the sample tail gas waiting for processing, and also keeps the flow rate of the sample tail gas sucked by the jet pump 64 stable. The back pressure valve 67 is connected to the sample tail gas outlet of the analysis module 5, and a switch valve can be provided between the back pressure valve 67 and the analysis module 5. The sample tail gas from the analysis module 5 is transported to the buffer tank 66 for temporary storage through the back pressure valve 67. The back pressure valve 67 can control the pressure of the sample tail gas output from the sample tail gas outlet of the analysis module 5, so that the pressure of the sample gas detected by the analysis module 5 remains stable, thereby improving the detection accuracy of the analysis module 5 for the oxygen concentration in the sample gas.

[0063] A liquid drain port 26 is provided on the side wall of the analysis cabinet 2 , and a back pressure valve 67 is connected to the liquid drain port 26 via a switch valve for discharging the condensed liquid in the sample exhaust pipeline.

[0064] As a specific implementation of the acetic acid production line online analysis system of the present application, Figures 5 to 7 As shown, the bypass unit 41 includes a bypass regulating valve 411, a bypass flowmeter 412, a normally open switch valve 413 and a normally closed switch valve 414. The bypass regulating valve 411 usually uses a needle valve, and the bypass regulating valve 411 is connected to the bypass port of the bypass filter 43. The bypass regulating valve 411 can adjust the flow rate of the sample gas diverted by the bypass unit 41, so that the flow rate of the sample gas flowing to the analysis module 5 is adapted to the detection requirements of the analysis module 5, thereby preventing the sample gas from being retained in the transmission pipeline and improving the real-time performance of the sample gas detection.

[0065] The bypass flowmeter 412 is connected to the bypass regulating valve 411 and is arranged on the wall of the pretreatment chamber 22. The bypass flowmeter 412 can intuitively display the flow value of the sample gas diverted by the bypass unit 41, which serves as a reference for adjusting the bypass regulating valve 411. The normally open switch valve 413 is arranged between the bypass flowmeter 412 and the buffer tank 66. Under normal circumstances, the diverted sample gas is transported to the buffer tank 66 for temporary storage of the sample tail gas. The normally closed switch valve 414 is arranged between the bypass flowmeter 412 and the outlet of the jet pump 64. When an abnormality occurs in the tail gas treatment module 6, it is opened to directly transport the sample gas to the tail gas incineration interface 65 for discharge treatment, thereby ensuring the safety of the online analysis system of the acetic acid production line of the present application.

[0066] In some embodiments of the acetic acid production line online analysis system of the present application, Figures 5 to 7As shown, the flow stabilization unit 42 includes a sample flow regulating valve 421, a sample flow meter 422, a pneumatic switch valve 423 and a filter 424. The sample flow regulating valve 421 usually uses a needle valve, and the sample flow regulating valve 421 is connected to the outlet of the bypass filter 43 to adjust the flow of the sample gas flowing from the bypass filter 43 to the flow stabilization unit 42, so that the flow of the sample gas is adapted to the detection requirements and detection speed of the analysis module 5. The sample flow regulating valve 421 is connected to the sample flow meter 422, which can intuitively display the flow of the sample gas as a basis for adjusting the sample flow regulating valve 421.

[0067] The pneumatic switch valve 423 usually uses a pneumatic ball valve, the inlet of the pneumatic switch valve 423 is connected to the sample flow meter 422, the outlet of the pneumatic switch valve 423 is connected to the filter 424, and the control port of the pneumatic switch valve 423 is connected to the reference gas circuit of the analysis module 5. Since the analysis module 5 needs to compare and analyze the sample gas with the reference gas when performing sample gas detection, the reference gas is necessary for the operation of the analysis module 5. The control port of the pneumatic switch valve 423 is connected to the reference gas circuit of the analysis module 5, and the on-off of the pneumatic switch valve 423 can be controlled by the pressure of the reference gas in the reference gas circuit. When the analysis module 5 has a reference gas supply, the pneumatic switch valve 423 is opened to transport the sample gas to the analysis module 5; and when the analysis module 5 has no reference gas supply, the pneumatic switch valve 423 is closed, which can prevent invalid input of the sample gas in the analysis module 5.

[0068] The filter 424 is connected between the analysis module and the analysis module 5, and can filter and remove particulate matter in the sample gas to ensure the accuracy of the detection result of the analysis module 5. An electric heating insulation belt is provided on the connecting pipeline between the filter 424 and the analysis module 5, and the electric heating insulation belt is accompanied by the sample gas supply pipeline and the sample exhaust gas exhaust pipeline of the analysis module 5 at the same time, and is used to heat the sample gas and the sample exhaust gas in the pipeline to prevent the acetic acid therein from condensing due to the temperature drop.

[0069] In some embodiments of the acetic acid production line online analysis system of the present application, Figures 5 to 7 As shown, the analysis module 5 includes an analyzer 51 and a purge explosion-proof unit 52. The analyzer 51 can use various existing analyzers that can detect the oxygen content in the sample gas extracted from the acetic acid production line, such as Siemens 6F series analyzers. The sample gas inlet of the analyzer 51 is connected to the flow stabilization unit 42, which is used to receive the sample gas supplied by the flow stabilization unit 42 to detect the oxygen concentration; the sample tail gas detected by the analyzer 51 is connected to the tail gas treatment module 6 through the sample tail gas discharge pipeline, and the sample tail gas is transported to the tail gas treatment module 6 for discharge and treatment.

[0070] An emergency discharge unit 511 is provided on the connecting pipeline between the analyzer 51 and the tail gas treatment module 6. An emergency discharge unit 511 includes a discharge normally closed switch valve, a flame arrester and an emergency discharge pipe. One end of the discharge normally closed switch valve is connected to the sample tail gas discharge pipeline, and the other end is connected to the emergency discharge pipe through the flame arrester. The emergency discharge pipe is fixed on the top of the analysis cabinet 2. The opening height of the emergency discharge pipe is at least 1.5 meters higher than the cabinet top. In an emergency, the discharge normally closed switch valve is opened, and the untreated sample tail gas is temporarily discharged to a safe area in the air through the emergency discharge pipe to prevent damage to the analysis system and the occurrence of safety accidents. The flame arrester can prevent external fire from entering the analyzer 51 through the emergency discharge unit 511, thereby improving the safety performance of the analysis system.

[0071] The purge explosion-proof unit 52 is arranged in the vicinity of the analyzer 51, and includes a second nitrogen pressure reducing valve 521 and a purge device 522. A nitrogen input interface 61 is arranged on the analysis cabinet 2, the inlet of the second nitrogen pressure reducing valve 521 is connected to the nitrogen input interface 61, and a switch ball valve is arranged between the second nitrogen pressure reducing valve 521 and the nitrogen input interface 61. The purge device 522 can use various existing positive pressure purge devices, the outlet of the second nitrogen pressure reducing valve 521 is connected to the positive pressure gas source inlet of the purge device 522, the air intake port of the purge device 522 is connected to the analyzer 51, and the discharge pipe of the purge device 522 extends out of the analysis cabinet 2 through the side wall of the analysis cabinet 2 and opens to the outside of the analysis cabinet 2.

[0072] The switch ball valve connected to the second nitrogen pressure reducing valve 521 is opened, and the industrial nitrogen after the pressure reduction by the second nitrogen pressure reducing valve 521 enters the purge 522, forming a high-speed airflow in the purge 522, and forming a negative pressure at the air inlet of the purge 522, so that the sample gas leaked from the analyzer 51 is sucked into the purge 522 and discharged through the discharge pipe of the purge 522 together with the industrial nitrogen. At the same time, the purge 522 can also transport part of the industrial nitrogen to the analyzer 51 to dilute the sample gas leaked from the analyzer 51. Since the amount of the leaked sample gas is small and the discharged sample gas has been fully diluted by the industrial nitrogen, its concentration is extremely low and does not cause safety risks.

[0073] In the acetic acid production line online analysis system of the present application, Figures 5 to 8 As shown, the analysis module 5 also includes a calibration unit 53. The calibration unit 53 includes a zero gas interface 531, a range gas interface 532, a calibration pressure reducing valve 533 and a calibration three-way valve 534. The zero gas interface 531 and the range gas interface 532 are respectively fixedly arranged on the analysis cabinet 2, and a sample passage three-way valve 44 is arranged on the sample gas passage connecting the flow stabilization unit 42 and the bypass unit 41. Specifically, the sample passage three-way valve 44 is connected between the bypass filter 43 and the sample flow regulating valve 421.

[0074] The calibration three-way valve 534 and the sample passage three-way valve 44 are both electrically controlled three-way valves with a normally closed interface and a normally open interface. The reference zero gas interface 531 is connected to the analyzer 51 through a pipeline to form a reference gas path. The reference zero gas interface 531 is also connected to the air inlet of the calibration pressure reducing valve 533 through a pipeline, the air outlet of the calibration pressure reducing valve 533 is connected to the normally open interface of the calibration three-way valve 534, the normally closed interface of the calibration three-way valve 534 is connected to the range gas interface 532, the common interface of the calibration three-way valve 534 is connected to the normally closed interface of the sample passage three-way valve 44, the normally open interface of the sample passage three-way valve 44 is connected to the bypass filter 43, and the common interface of the sample passage three-way valve 44 is connected to the sample flow regulating valve 421.

[0075] When the analyzer 51 is working normally, the normally open interface of the sample passage three-way valve 44 is connected to the public interface, and the sample gas is transmitted to the analyzer 51 through the flow stabilization unit 42; at the same time, the reference zero gas interface 531 is connected to the reference gas source, and the reference gas enters the analyzer 51 through the reference gas path, and the analyzer 51 analyzes and detects the oxygen concentration in the sample gas.

[0076] When the analyzer 51 is zeroed, the normally closed interface of the sample passage three-way valve 44 is connected to the common interface, and the supply path of the sample gas is disconnected; at the same time, the reference zero gas interface 531 is connected to the zero gas source, and the common interface of the calibration three-way valve 534 is connected to the normally open interface. After the zero gas is reduced in pressure by the calibration pressure reducing valve 533, it is transmitted to the analyzer 51 through the calibration three-way valve 534, the sample passage three-way valve 44 and the flow stabilization unit 42 for zero point calibration. Zero gas does not contain oxygen, and does not need to be analyzed and compared with the reference gas during the zeroing process, so there is no need to supply reference gas.

[0077] When performing range calibration of the analyzer 51, the normally closed interface of the sample passage three-way valve 44 is connected to the common interface, and the supply path of the sample gas is disconnected; the common interface of the calibration three-way valve 534 is connected to the normally closed interface, and the range gas input from the range gas interface 532 is transmitted to the analyzer 51 through the calibration three-way valve 534, the sample passage three-way valve 44 and the flow stabilization unit 42; at the same time, the reference zero gas interface 531 is connected to the reference zero gas interface 531 and the reference gas source, and the reference gas enters the analyzer 51 through the reference gas path for range calibration, thereby ensuring the accuracy of the detection results of the analyzer 51.

[0078] In the description of the present application, the description with reference to the terms "one embodiment", "specific embodiment", "preferred embodiment", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0079] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. An acetic acid production line online analysis system, characterized in that: The invention comprises a pre-treatment box (1) and an analysis cabinet (2), wherein the pre-treatment box (1) is connected to an acetic acid production line via a sample feeding pipe (11), and is connected to the analysis cabinet (2) via a sample conveying pipe (12), wherein a pre-treatment module (3) is arranged in the pre-treatment box (1), and the pre-treatment module (3) comprises a sample decompression unit (31) and a heating unit (32), wherein the sample decompression unit (31) is connected between the sample feeding pipe (11) and the sample conveying pipe (12), and the heating unit (32) is arranged adjacent to the sample decompression unit (31) and the sample conveying pipe (12), and is connected to the analysis cabinet (2). The analysis cabinet (2) is connected to a sample conveying pipe (12) and an analysis module (5); a pre-treatment module (4), an analysis module (5) and an exhaust gas treatment module (6) are arranged in the analysis cabinet (2); the pre-treatment module (4) comprises a bypass unit (41) and a flow stabilization unit (42); the bypass unit (41) is arranged between the sample conveying pipe (12) and the exhaust gas treatment module (6); the flow stabilization unit (42) is connected between the sample conveying pipe (12) and the analysis module (5); the exhaust gas treatment module (6) is connected to the analysis module (5) so as to be able to recover the sample gas while maintaining the pressure of the sample gas stable.

2. The acetic acid production line online analysis system according to claim 1, characterized in that: The sample pressure reducing unit (31) comprises a pre-filter (311) and a sample pressure reducing valve (312), wherein the inlet of the pre-filter (311) is connected to the sample feeding pipe (11), and the sample pressure reducing valve (312) is connected between the outlet of the pre-filter (311) and the sample conveying pipe (12); the heating unit (32) comprises a first steam accompanying pipeline (321) and a second steam accompanying pipeline (322), wherein the first steam accompanying pipeline (321) is arranged along the sample pressure reducing valve (312), the pre-filter (311) and the sample feeding pipe (11), and the second steam accompanying pipeline (322) is arranged along the sample conveying pipe (12) and is connected to the analysis cabinet (2).

3. The acetic acid production line online analysis system according to claim 2, characterized in that: The pre-treatment box (1) is provided with a steam input interface (13) and a steam condensate return interface (14); one end of the first steam accompanying pipeline (321) is connected to the steam input interface (13), and the other end is connected to the steam condensate return interface (14); a first steam regulating valve (323) is connected between the first steam accompanying pipeline (321) and the steam input interface (13); a first steam trap (324) is connected between the first steam accompanying pipeline (321) and the steam condensate return interface (14); the second steam accompanying pipeline (322) is connected to the steam input interface (13); 2) a second steam regulating valve (325) is connected between the pre-treatment box heating pipe (326) and the steam input interface (13); the heating unit (32) further comprises a pre-treatment box heating pipe (326), the pre-treatment box heating pipe (326) is arranged in the pre-treatment box (1), one end of the pre-treatment box heating pipe (326) is connected to the steam input interface (13), and the other end is connected to the steam condensate return interface (14), a third steam regulating valve (327) is connected between the pre-treatment box heating pipe (326) and the steam input interface (13), and a second steam trap (328) is connected between the pre-treatment box heating pipe (326) and the steam condensate return interface (14).

4. The acetic acid production line online analysis system according to claim 1, characterized in that: An analysis chamber (21) and a pretreatment chamber (22) are arranged in the analysis cabinet (2); the pretreatment module (4) and the tail gas treatment module (6) are arranged in the pretreatment chamber (22); the analysis module (5) is arranged in the analysis chamber (21); a pretreatment chamber heating pipe (221) is also arranged in the pretreatment chamber (22); the pretreatment chamber heating pipe (221) is connected to the heating unit (32); a cooling unit (23) is arranged in the analysis chamber (21); the cooling unit (23) comprises an instrument air interface (231), an instrument air pressure reducing valve (232) and a vortex cooler (233); an air inlet of the instrument air pressure reducing valve (232) is connected to the instrument air interface (231); an air outlet opens in the analysis chamber (21); the vortex cooler (233) is arranged on the outer wall of the analysis chamber (21) and is connected to the internal space of the analysis chamber (21).

5. The acetic acid production line online analysis system according to claim 4, characterized in that: The pretreatment module (4) further comprises a bypass filter (43), the inlet of the bypass filter (43) being connected to the sample delivery tube (12), the bypass port of the bypass filter (43) being connected to the bypass unit (41), and the outlet of the bypass filter (43) being connected to the flow stabilization unit (42).

6. The acetic acid production line online analysis system according to claim 5, characterized in that: The exhaust gas treatment module (6) comprises a nitrogen input interface (61), a first nitrogen pressure reducing valve (62), a nitrogen preheating pipe (63), an injection pump (64), an exhaust gas incineration interface (65), a buffer tank (66) and a back pressure valve (67); the inlet of the first nitrogen pressure reducing valve (62) is connected to the nitrogen input interface (61), and the outlet is connected to the nitrogen preheating pipe (63); the inlet of the injection pump (64) is connected to the nitrogen preheating pipe (63), the outlet is connected to the exhaust gas incineration interface (65), the suction port is connected to the buffer tank (66), the buffer tank (66) is connected to the back pressure valve (67), and the back pressure valve (67) is connected to the analysis module (5).

7. The acetic acid production line online analysis system according to claim 6, characterized in that: The bypass unit (41) comprises a bypass regulating valve (411), a bypass flowmeter (412), a normally open switch valve (413) and a normally closed switch valve (414); one end of the bypass regulating valve (411) is connected to the bypass port of the bypass filter (43), and the other end is connected to the bypass flowmeter (412); the normally open switch valve (413) is arranged between the bypass flowmeter (412) and the buffer tank (66); and the normally closed switch valve (414) is arranged between the bypass flowmeter (412) and the outlet of the jet pump (64).

8. The acetic acid production line online analysis system according to claim 5, characterized in that: The flow stabilization unit (42) comprises a sample flow regulating valve (421), a sample flow meter (422), a pneumatic switch valve (423) and a filter (424); the sample flow regulating valve (421) is connected to the outlet of the bypass filter (43); the sample flow meter (422) is connected between the sample flow regulating valve (421) and the inlet of the pneumatic switch valve (423); the outlet of the pneumatic switch valve (423) is connected to the filter (424); the control port of the pneumatic switch valve (423) is connected to the reference gas path of the analysis module (5); the filter (424) is connected to the analysis module (5); and an electric heating insulation belt is provided on the connection pipeline between the filter (424) and the analysis module (5).

9. The acetic acid production line online analysis system according to any one of claims 1 to 8, characterized in that: The analysis module (5) comprises an analyzer (51) and a purge explosion-proof unit (52); the analyzer (51) is connected to the flow stabilization unit (42) and the tail gas treatment module (6); an emergency discharge unit (511) is provided on the connection pipeline between the analyzer (51) and the tail gas treatment module (6); the emergency discharge unit (511) is connected to the outside of the analysis cabinet (2); the purge explosion-proof unit (52) is arranged adjacent to the analyzer (51), and comprises a second nitrogen pressure reducing valve (521) and a purge (522); the inlet of the second nitrogen pressure reducing valve (521) is connected to a nitrogen input interface (61) provided on the analysis cabinet (2), and the outlet is connected to the purge (522); the purge (522) is connected to the analyzer (51), and the discharge pipe of the purge (522) opens to the outside of the analysis cabinet (2).

10. The acetic acid production line online analysis system according to claim 9, characterized in that: The analysis module (5) further comprises a calibration unit (53), the calibration unit (53) comprising a zero gas interface (531), a range gas interface (532), a calibration pressure reducing valve (533) and a calibration three-way valve (534), the zero gas interface (531) and the range gas interface (532) being both arranged on the analysis cabinet (2), the zero gas interface (531) being connected to the analyzer (51) and the calibration pressure reducing valve (533), a sample passage three-way valve (44) being arranged between the bypass unit (41) and the flow stabilization unit (42), and the calibration three-way valve (534) being respectively connected to the calibration pressure reducing valve (533), the range gas interface (532) and the sample passage three-way valve (44).

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