A system for detecting the content of all components in the process gas at the outlet of a methane synthesis reactor

Abstract

The present invention belongs to the technical field of methane production equipment, and specifically relates to a system for detecting the content of all components in process gas at the outlet of a methane synthesis reactor, comprising a sampling cooler, a sample gas separation tank and an online chromatograph. The sampling cooler air inlet pipeline is provided with a sample gas flow meter, a sample gas total flow regulating valve, a sample gas pressure gauge, a sample gas thermometer, and a cooling water flow control valve is provided on the cooling circulating water upper water pipeline of the sampling cooler. The outlet pipeline of the sampling cooler is connected to the sample gas separation tank, and the sample gas separation tank air outlet pipeline is provided with an online chromatograph, a second pressure gauge, a second thermometer, and a second flow meter. The present invention also provides a method for detecting using the above-mentioned full component content detection system. The present invention can accurately detect the content of each component in the process gas, so that process personnel can timely judge whether the water content in the furnace meets the process requirements based on the detection results, thereby preventing the occurrence of carbon deposition reaction.

Description

Technical Field

[0001] The invention belongs to the technical field of methane production equipment, and in particular relates to a system for detecting the content of all components in process gas at an outlet of a methane synthesis reactor. Background Art

[0002] The methane synthesis process adopts carbon monoxide methanogenic synthesis technology. The reactors of this process are respectively loaded with nickel-based catalysts. The methane synthesis reaction is carried out in multiple reactors in sequence. The carbon deposition reaction of CO can generate elemental carbon and adhere to the surface of the catalyst, covering the catalytic active substances in the catalyst, reducing the activity of the catalyst; in addition, since the catalyst has a porous structure, the elemental carbon generated by the reaction accumulates to a certain extent, which can break the micropores in the catalyst, thereby causing the catalyst to break, resulting in poor permeability of the catalyst bed, affecting the air intake of the reactor, and catalyst carbon deposition has become a key factor restricting the normal operation of the methane synthesis unit. Due to CO2 The structure is stable and no reaction of precipitation of elemental carbon will occur. In the methane synthesis process, a certain water content must be guaranteed to increase the conversion rate of CO in its shift reaction, ensure the CO2 content in the reaction gas, and reduce the CO content, thereby preventing the carbon deposition reaction from occurring. Therefore, it is necessary to timely grasp the content of each component of the gas in the methane reactor to determine whether the reactor contains enough water. If the water content is too low, additional water needs to be added to increase the water content and control the water content in the reactor to above 21.95% (volume fraction). In the prior art, process gas component detection is generally performed by manual sampling. In order to prevent high-temperature gas from scalding the sampling personnel, the sampling must be The sample gas collected in the device is cooled by circulating cooling water, and the liquid water is separated by a gas-liquid separator before being collected. Analysts use a gas chromatograph to analyze the sample gas. Before the sample gas enters the gas chromatograph, in order to ensure the analysis accuracy, the sample gas is further dried and dehydrated by passing through a drying column filled with water-absorbing materials. Therefore, the water content in the sample gas cannot be detected. Only the content of each component in the dry-based sample gas (the sample gas with water removed) can be detected, which cannot represent the content of each component in the gas at the outlet of the main reactor. The process personnel cannot grasp the content of each component in the gas at the outlet of the main reactor in time, and thus cannot guarantee the water content in the main reactor, which can easily lead to carbon deposition reaction. Summary of the invention

[0003] In view of the above problems, the purpose of the present invention is to provide a system for detecting the content of all components in the process gas at the outlet of a methane synthesis reactor, which can avoid scalding of sampling personnel, accurately detect the content of each component in the process gas, enable process personnel to promptly judge whether the water content in the furnace meets the process requirements, and prevent the occurrence of carbon deposition reaction.

[0004] The object of the present invention is achieved through the following technical scheme: a system for detecting the content of all components in the process gas at the outlet of a methane synthesis reactor, comprising a sampling cooler, a sample gas separation tank and an online chromatograph, wherein a sample gas flow meter, a sample gas total flow regulating valve, a sample gas pressure gauge and a sample gas thermometer are arranged on the air inlet pipeline of the sampling cooler, the air inlet pipeline of the sampling cooler is connected to the methane synthesis reactor through a sampling branch pipe, a sampling control valve is arranged on the sampling branch pipe, a cooling water flow control valve is arranged on the cooling circulating water upper water pipeline of the sampling cooler, the outlet pipeline of the sampling cooler is connected to the sample gas separation tank, a wire mesh demister is arranged in the sample gas separation tank, and a liquid level meter is arranged on the outer wall, an online chromatograph is arranged on the air outlet pipeline of the sample gas separation tank, and a second pressure gauge, a second thermometer and a second flow meter are arranged on the air outlet pipeline between the sample gas separation tank and the online chromatograph.

[0005] Furthermore, the gas outlet pipeline of the sample gas separation tank is connected to a drying system.

[0006] Furthermore, the air outlet pipeline is connected to a manual closed sampler through a connecting pipe, and a valve is provided at the inlet of the manual closed sampler.

[0007] Furthermore, a condensate flowmeter and a liquid level regulating valve for regulating the liquid level of the sample gas separation tank are provided on the condensate outlet pipeline of the sample gas separation tank.

[0008] Furthermore, the sample gas flow meter, the sample gas total flow regulating valve, the sample gas pressure gauge, and the sample gas temperature gauge on the air inlet pipeline of the sampling cooler are connected to the DCS control system.

[0009] Furthermore, the cooling water flow control valve, the second pressure gauge, the second temperature gauge, and the second flow meter are all connected to the DCS control system, and the DCS control system is connected to a human-machine interface and an alarm.

[0010] The present invention also provides a method for detecting using the above-mentioned full component content detection system, comprising the following steps:

[0011] Step 1, sample gas collection: when it is necessary to detect the content of all components of the process gas at the outlet of the methane synthesis reactor, the corresponding sampling control valve is opened, and the process gas (sample gas) at the outlet of the methane synthesis reactor flows into the sampling cooler through the sampling branch pipe and the sampling cooler air inlet pipeline in sequence;

[0012] Step 2, total sample gas flow measurement: Since the sampling cooler air inlet pipeline is provided with a sample gas flow meter, a sample gas total flow regulating valve, a sample gas pressure gauge, and a sample gas thermometer, the sample gas passes through the sample gas flow meter, and the total volume flow of the sample gas is detected, and combined with the values ​​measured by the sample gas pressure gauge and the sample gas thermometer, it is converted into a total volume flow under standard conditions (101.325KPa, 20°C), represented by F1 (unit: Nm3 / h), and then the total sample gas flow is regulated and controlled by the sample gas total flow regulating valve to stabilize it at a fixed value;

[0013] Step 3, sample gas separation tank outlet temperature control: the sample gas is cooled by the sampling cooler, the cooling water flow control valve is adjusted, and the sample gas temperature at the sample gas separation tank outlet is automatically controlled at a fixed temperature not higher than 40°C in combination with the display signal of the second thermometer. The wire mesh demister on the upper part of the sample gas separation tank separates the liquid water in the sample gas to avoid affecting the calculation accuracy of the device;

[0014] Step 4, calculation of the volume fraction of water: Since the temperature of water in the sample gas at the outlet of the sample gas separation tank does not change, the corresponding saturated vapor pressure does not change either. Since the sample gas contains about 20% water by volume, a large amount of water will be separated in the sample gas separation tank. After the water is separated, the sample gas contains saturated water at the current pressure and temperature. The partial pressure of water in the sample gas at the current pressure is equal to the saturated vapor pressure corresponding to water at the current temperature. Thus, the partial pressure of water in the current sample gas is obtained, which is represented by P1. The sample gas pressure at the outlet of the sample gas separation tank is measured by the second pressure gauge, which is represented by P2. The volume fraction of water in the sample gas at the outlet of the sample gas separation tank is V1= P1 / P2.

[0015] Step 5, calculation of the total volume flow rate of water in the sample gas: the volume flow rate of the sample gas at the outlet of the sample gas separation tank is measured by the second flowmeter at the current temperature and pressure, and combined with the second pressure gauge and the second temperature gauge, it is converted into the volume flow rate F2 (unit: Nm3 / h) under the standard state (101.325KPa, 20℃), then the volume flow rate of water in the sample gas at the outlet of the sample gas separation tank is F3= F2* V1= F2* P1 / P2; since the sample gas separates a part of water in the sample gas separation tank, therefore, F2<F1, the volume flow rate of water separated by the sample gas separation tank is F4= F1- F2, thus, the total volume flow rate of water contained in the process gas at the outlet of the methane synthesis reactor is F5= F3+ F4= F2* P1 / P2+ F1- F2, thus, it can be deduced that the volume percentage of water in the process gas at the outlet of the methane synthesis reactor is V= F5 / F1= (F2* P1 / P2+ F1- F2) / F1;

[0016] Step 6, determination of other component contents in the sample gas: the online chromatograph is used to measure the sample gas in the outlet pipeline. Before the sample gas enters the chromatographic column, it is thoroughly dried and dehydrated. Therefore, the contents of each component analyzed by the online chromatograph are the volume percentages of each component in the water-free dry sample gas.

[0017] Furthermore, in step 6, the methane content is determined: the methane volume fraction measured by the sample gas online chromatograph is V2, then the methane volume flow rate is F8= (F2- F3) * V2, from which it can be inferred that the methane volume content is V3= F8 / F1= (F2- F3) * V2 / F1= (F2- F2* P1 / P2) * V2 / F1, and the algorithms for other components are the same as in this example.

[0018] Furthermore, since the measurement values ​​of the sample gas flowmeter and the second flowmeter have a certain range of errors, in order to avoid excessive measurement errors, the total sample gas flow rate is controlled to maintain stability by the sample gas total flow rate regulating valve, and the liquid level of the sample gas separation tank is controlled to remain unchanged by the liquid level regulating valve, and the separated water flow rate in the sample gas separation tank is measured by the condensate flowmeter, which is represented by F6 (in kg / h). This is the mass flow rate of water, compared with the volume flow rate F4= F1-F2 of water separated from the sample gas separation tank calculated in step 5. Since the volume of 1 mol of water vapor is converted into a standard state of 22.4L=0.0224Nm3, and the molecular weight of water is 18g / mol, the mass flow rate of water F7= F4*18 / 22.4 (in kg / h) can be obtained; if the two algorithms differ too much, one of the flow meters must be inaccurate and needs to be calibrated in time; in order to discover this problem in time, the error of the two measurement schemes is set to D=(F7- F6) / F7 requires D to be between -0.02 and 0.02. If it exceeds this range, an alarm will be issued in the control system to remind the operator to take relevant measures.

[0019] Furthermore, to verify the measurement accuracy of the online chromatograph analyzer in step 6, manual sampling is performed at the manual closed sampler, and the chromatograph is replaced for measurement. The measurement errors of the two are compared to ensure that the errors are within the allowable range.

[0020] Furthermore, in order to improve the detection and calculation efficiency of the system, each calculation formula is automatically calculated in the DCS control system through configuration, and the calculation results are displayed on the human-computer interaction interface; a low water content alarm and a low interlock are set. When a low alarm occurs, the process personnel will add water to the main reactor in time. When a low interlock occurs, the methane synthesis unit will automatically stop.

[0021] Furthermore, to avoid waste of sample gas, the present invention finally discharges the sample gas into the drying system after the methane synthesis unit. To avoid disorderly discharge of process condensate, the present invention discharges the water separated from the sample gas separation tank into the process condensate treatment system of the methane synthesis unit.

[0022] Beneficial effects: The present invention can avoid scalding of sampling personnel, accurately detect the content of each component in the process gas, enable process personnel to timely judge whether the water content in the furnace meets the process requirements based on the test results, and prevent the occurrence of carbon deposition reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The specific structure of this application is given by the following drawings and embodiments:

[0024] Figure 1 : A schematic diagram of the structure of Embodiment 1 of the present invention;

[0025] Figure 2 : A schematic structural diagram of embodiment 2 of the present invention.

[0026] In the figure: 1. sampling cooler, 2. sample gas separation tank, 3. online chromatograph, 4. manual closed sampler, 11. sampling cooler air inlet pipeline, 12. sample gas flow meter, 13. sample gas total flow regulating valve, 14. sample gas pressure gauge, 15. sample gas temperature gauge, 16. sampling branch pipe, 17. sampling control valve, 18. cooling circulating water supply pipeline, 19. cooling water flow control valve, 21. wire mesh demister, 22. liquid level meter, 23. air outlet pipeline, 24. second pressure gauge, 25. second temperature gauge, 26. second flow meter, 27. condensate flow meter, 28. liquid level regulating valve, 41. valve. DETAILED DESCRIPTION

[0027] The specific implementation of the present invention is given below to further explain the content of the invention in detail. This does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the content of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

[0028] In the present invention, for the convenience of description, the relative position relationship of each component is described according to the layout of the drawings in the specification, such as: the position relationship of up, down, left, right, etc. is determined according to the layout direction in the drawings in the specification.

[0029] Example 1, reference Figure 1A system for detecting the content of all components in the process gas at the outlet of a methane synthesis reactor comprises a sampling cooler 1, a sample gas separation tank 2 and an online chromatographic analyzer 3. The sampling cooler 1 has a sample gas flow meter 12, a sample gas total flow regulating valve 13, a sample gas pressure gauge 14, and a sample gas temperature gauge 15 arranged on the air inlet pipeline 11. The sampling cooler 1 has a sampling branch pipe 16 connected to the methane synthesis reactor, the sampling branch pipe 16 has a sampling control valve 17, and the cooling circulating water supply pipeline 18 of the sampling cooler 1 is provided with a sampling control valve 18. A cooling water flow control valve 19 is provided, the outlet pipeline of the sampling cooler 1 is connected to the sample gas separation tank 2, a wire mesh demister 21 is provided in the sample gas separation tank 2, and a liquid level meter 22 is provided on the outer wall, an online chromatograph 3 is provided on the gas outlet pipeline 23 of the sample gas separation tank 2, and a second pressure gauge 24, a second thermometer 25, and a second flow meter 26 are provided on the gas outlet pipeline 23 between the sample gas separation tank 2 and the online chromatograph 3, and the gas outlet pipeline 23 of the sample gas separation tank 2 is connected to a drying system.

[0030] The gas outlet pipeline 23 is connected to the manual closed sampler 4 through a connecting pipe, and a valve 41 is provided at the inlet of the manual closed sampler 4 .

[0031] The sample gas flow meter 12, the sample gas total flow regulating valve 13, the sample gas pressure gauge 14, and the sample gas temperature gauge 15 on the air inlet pipeline 11 of the sampling cooler 1 are connected to the DCS control system, the cooling water flow control valve 19, the second pressure gauge 24, the second temperature gauge 25, and the second flow meter 26 are all connected to the DCS control system, and the DCS control system is connected to the human-computer interaction interface and the alarm.

[0032] The present invention also provides a method for detecting using the above-mentioned full component content detection system, comprising the following steps:

[0033] Step 1, gas sample collection: when it is necessary to detect the content of all components of the process gas at the outlet of the methane synthesis reactor, the corresponding sampling control valve 17 is opened, and the process gas (sample gas) at the outlet of the methane synthesis reactor flows into the sampling cooler 1 through the sampling branch pipe 16 and the gas inlet pipeline 11 of the sampling cooler 1 in sequence;

[0034] Step 2, total sample gas flow measurement: Since the sample cooler 1 air inlet pipeline 11 is provided with a sample gas flow meter 12, a sample gas total flow regulating valve 13, a sample gas pressure gauge 14, and a sample gas thermometer 15, the sample gas passes through the sample gas flow meter, and the total volume flow of the sample gas is detected, and combined with the values ​​measured by the sample gas pressure gauge and the sample gas thermometer, it is converted into a total volume flow under standard conditions (101.325KPa, 20°C), represented by F1 (unit: Nm3 / h), and then the total sample gas flow is regulated and controlled by the sample gas total flow regulating valve to stabilize it at a fixed value;

[0035] Step 3, sample gas separation tank 2 outlet temperature control: the sample gas is cooled by the sampling cooler 1, the cooling water flow control valve 19 is adjusted, and the sample gas temperature at the sample gas separation tank 2 outlet is automatically controlled at a fixed temperature not higher than 40°C in combination with the display signal of the second thermometer 25. The wire mesh demister 21 on the upper part of the sample gas separation tank 2 separates the liquid water in the sample gas to avoid affecting the calculation accuracy of the device;

[0036] Step 4, calculation of the volume fraction of water: since the temperature of the water in the sample gas at the outlet of the sample gas separation tank 2 does not change, the corresponding saturated vapor pressure also does not change. Since the sample gas contains about 20% water by volume, a large amount of water will be separated in the sample gas separation tank. After the water is separated, the sample gas contains saturated water at the current pressure and temperature. The partial pressure of water in the sample gas at the current pressure is equal to the saturated vapor pressure corresponding to the water at the current temperature. Thus, the partial pressure of water in the current sample gas is obtained, which is represented by P1. The sample gas pressure at the outlet of the sample gas separation tank 2 is measured by the second pressure gauge 24, which is represented by P2. The volume fraction of water in the sample gas at the outlet of the sample gas separation tank 2 is V1= P1 / P2.

[0037] Step 5, calculation of the total volume flow rate of water in the sample gas: the volume flow rate of the sample gas at the outlet of the sample gas separation tank 2 is measured by the second flowmeter 26 at the current temperature and pressure, and combined with the second pressure gauge 24 and the second temperature gauge 25, it is converted into a volume flow rate F2 (in Nm3 / h) under the standard state (101.325KPa, 20°C), then the volume flow rate of water in the sample gas at the outlet of the sample gas separation tank 2 is F3= F2* V1= F2* P1 / P2; since the sample gas separates a part of water in the sample gas separation tank, therefore, F2<F1, the volume flow rate of water separated by the sample gas separation tank is F4= F1- F2, thus, the total volume flow rate of water contained in the process gas at the outlet of the methane synthesis reactor is F5= F3+ F4= F2* P1 / P2+ F1- F2, thus, it can be deduced that the volume percentage of water in the process gas at the outlet of the methane synthesis reactor is V= F5 / F1= (F2* P1 / P2+ F1- F2) / F1;

[0038] Step 6, determination of other component contents in the sample gas: the online chromatograph 3 measures the sample gas in the gas outlet pipeline 23. Before the sample gas enters the chromatographic column, it is thoroughly dried and dehydrated. Therefore, the contents of each component analyzed by the online chromatograph 3 are the volume percentage contents of each component in the dry sample gas without water.

[0039] In step 6, the determination of methane content: the methane volume fraction measured by the sample gas online chromatograph 3 is V2, and the methane volume flow rate can be obtained as F8= (F2- F3) * V2, from which it can be deduced that the methane volume content is V3= F8 / F1= (F2-F3) * V2 / F1= (F2- F2* P1 / P2) * V2 / F1. The calculation method for other components is the same as this example;

[0040] To verify the measurement accuracy of the online chromatograph analyzer 3 in step 6, manually sample at the manual closed sampler 4, replace the chromatograph for measurement, and compare the measurement errors of the two to ensure that the errors are within the allowable range; at the same time, when the online chromatograph analyzer 3 is damaged, manually sample at the manual closed sampler 4 and replace the online chromatograph analyzer in time;

[0041] In order to improve the detection and calculation efficiency of this system, all calculation formulas are automatically calculated in the DCS control system through configuration, and the calculation results are displayed on the human-computer interaction interface; low water content alarm and low interlock are set. When a low alarm occurs, the process personnel replenish water in time, and when a low interlock occurs, the methane synthesis unit automatically stops;

[0042] To avoid waste of sample gas, the present invention finally discharges the sample gas into the drying system after the methane synthesis unit. To avoid disorderly discharge of process condensate, the present invention discharges the water separated by the sample gas separation tank 2 into the process condensate treatment system of the methane synthesis unit.

[0043] Example 2, reference Figure 2 As a further optimized design of Example 1, a condensate flowmeter 27 and a liquid level regulating valve 28 for regulating the liquid level of the sample gas separation tank are provided on the condensate outlet pipeline of the sample gas separation tank 2. Since the measurement values ​​of the sample gas flowmeter 12 and the second flowmeter 26 have a certain range of errors, in order to avoid excessive measurement errors, the total sample gas flow is controlled to be stable by the sample gas total flow regulating valve 13, and the liquid level regulating valve 28 is used to control the liquid level of the sample gas separation tank 2 to remain unchanged. The separated water flow in the sample gas separation tank 2 is measured by the condensate flowmeter 27 and is represented by F6 (in kg / h). This is the mass flow rate of water. Compared with the volume flow rate F4= F1- F2 of water separated from the sample gas separation tank 2 calculated in step 5, since the volume of 1 mol of water vapor is converted into a standard state of 22.4L=0.0224Nm3, and the molecular weight of water is 18g / mol, the mass flow rate of water F7= F4*18 / 22.4 (unit: kg / h); If the difference between the two algorithms is too large, one of the flow meters must be inaccurate and needs to be calibrated in time; In order to detect this problem in time, the error between the two measurement schemes is set to D= (F7- F6) / F7, and D is required to be between -0.02 and 0.02. If it exceeds this range, an alarm will be issued in the control system to remind the operator to take relevant measures.

Claims

1. A system for detecting the content of all components in the process gas at the outlet of a methane synthesis reactor, characterized in that: It comprises a sampling cooler, a sample gas separation tank and an online chromatograph analyzer, wherein a sample gas flow meter, a sample gas total flow regulating valve, a sample gas pressure gauge and a sample gas temperature gauge are arranged on the air inlet pipeline of the sampling cooler, the air inlet pipeline of the sampling cooler is connected with a methane synthesis reactor through a sampling branch pipe, a sampling control valve is arranged on the sampling branch pipe, a cooling water flow control valve is arranged on the cooling circulating water upper water pipeline of the sampling cooler, the outlet pipeline of the sampling cooler is connected with the sample gas separation tank, a wire mesh demister is arranged in the sample gas separation tank, the wire mesh demister on the upper part of the sample gas separation tank separates liquid water in the sample gas, and a liquid level meter is arranged on the outer wall, an online chromatograph analyzer is arranged on the air outlet pipeline of the sample gas separation tank, and a second pressure gauge, a second temperature gauge and a second flow meter are arranged on the air outlet pipeline between the sample gas separation tank and the online chromatograph analyzer; The gas outlet pipeline is connected to a manual closed sampler through a connecting pipe, and a valve is provided at the inlet of the manual closed sampler; The condensate outlet pipeline of the sample gas separation tank is provided with a condensate flow meter and a liquid level regulating valve for regulating the liquid level of the sample gas separation tank; The sample gas flow meter, sample gas total flow regulating valve, sample gas pressure gauge and sample gas temperature gauge on the sampling cooler air inlet pipeline are connected to the DCS control system; The cooling water flow control valve, the second pressure gauge, the second temperature gauge, and the second flow meter are all connected to the DCS control system, and the DCS control system is connected to a human-machine interface and an alarm.

2. A method for detecting using the full component content detection system as claimed in claim 1, characterized in that: The following steps are involved: Step 1, gas sample collection: when it is necessary to detect the content of all components of the process gas at the outlet of the methane synthesis reactor, the corresponding sampling control valve is opened, and the process gas sample at the outlet of the methane synthesis reactor flows into the sampling cooler through the sampling branch pipe and the sampling cooler air inlet pipeline in sequence; Step 2, total sample gas flow measurement: Since the sampling cooler air inlet pipeline is provided with a sample gas flow meter, a sample gas total flow regulating valve, a sample gas pressure gauge, and a sample gas thermometer, the sample gas passes through the sample gas flow meter, and the total volume flow of the sample gas is detected, and combined with the values ​​measured by the sample gas pressure gauge and the sample gas thermometer, it is converted into a total volume flow under standard conditions, represented by F1, and the unit is Nm3 / h. After that, the total sample gas flow is regulated and controlled by the sample gas total flow regulating valve to stabilize it at a fixed value; Step 3, sample gas separation tank outlet temperature control: the sample gas is cooled by the sampling cooler, the cooling water flow control valve is adjusted, and the sample gas temperature at the sample gas separation tank outlet is automatically controlled at a fixed temperature not higher than 40°C in combination with the display signal of the second thermometer. The wire mesh demister on the upper part of the sample gas separation tank separates the liquid water in the sample gas to avoid affecting the calculation accuracy of the device; Step 4, calculation of the volume fraction of water: Since the temperature of water in the sample gas at the outlet of the sample gas separation tank remains unchanged, the corresponding saturated vapor pressure also remains unchanged. Since the sample gas contains about 20% water by volume, a large amount of water will be separated in the sample gas separation tank. After the water is separated, the sample gas contains saturated water at the current pressure and temperature. The partial pressure of water in the sample gas at the current pressure is equal to the saturated vapor pressure corresponding to water at the current temperature. Thus, the partial pressure of water in the current sample gas is obtained, which is represented by P1. The sample gas pressure at the outlet of the sample gas separation tank is measured by the second pressure gauge, which is represented by P2. The volume fraction of water in the sample gas at the outlet of the sample gas separation tank is V1= P1 / P2. Step 5, calculation of the total volume flow rate of water in the sample gas: the volume flow rate of the sample gas at the outlet of the sample gas separation tank is measured by the second flowmeter at the current temperature and pressure, and combined with the second pressure gauge and the second temperature gauge, it is converted into a volume flow rate under the standard state, represented by F2, and the unit is Nm3 / h, then the volume flow rate of water in the sample gas at the outlet of the sample gas separation tank is F3= F2×V1= F2×P1 / P2; since the sample gas separates a part of water in the sample gas separation tank, therefore, F2<F1, the volume flow rate of water separated by the sample gas separation tank is F4= F1- F2, thus, the total volume flow rate of water contained in the process gas at the outlet of the methane synthesis reactor is F5= F3+F4= F2×P1 / P2+ F1- F2, thus, it can be deduced that the volume percentage of water in the process gas at the outlet of the methane synthesis reactor is V= F5 / F1= (F2×P1 / P2+ F1- F2) / F1; Step 6, determination of other component contents in the sample gas: the online chromatograph is used to measure the sample gas in the outlet pipeline. Before the sample gas enters the chromatographic column, it is thoroughly dried and dehydrated. Therefore, the contents of each component analyzed by the online chromatograph are the volume percentages of each component in the water-free dry sample gas.

3. The method according to claim 2, characterized in that In step 6, the methane content is determined as follows: the methane volume fraction measured by the online chromatograph of the sample gas is V2, and the methane volume flow rate is F8 = (F2- F3) × V2. From this, it can be inferred that the methane volume content is V3 = F8 / F1 = (F2- F3) × V2 / F1 = (F2- F2 × P1 / P2) × V2 / F1.

4. The method according to claim 2, characterized in that The total sample gas flow rate is controlled to maintain stability by the sample gas total flow rate regulating valve, and the liquid level of the sample gas separation tank is controlled to remain unchanged by the liquid level regulating valve. The separated water flow rate in the sample gas separation tank is measured by the condensate flowmeter, which is represented by F6 in kg / h, which is the mass flow rate of water. Compared with the volume flow rate F4= F1- F2 of water separated from the sample gas separation tank calculated in step 5, since the volume of 1 mol of water vapor is converted into a standard state of 22.4L=0.0224Nm3, and the molecular weight of water is 18g / mol, the mass flow rate of water F7= F4×18 / 22.4 can be obtained, which is in kg / h; if the two algorithms differ too much, one of the flow meters must be inaccurate and needs to be calibrated in time; in order to discover this problem in time, the error of the two measurement schemes is set to D= (F7- F6) / F7, and D is required to be between -0.02 and 0.

02.

5. The method according to claim 2, characterized in that To verify the measurement accuracy of the online chromatograph in step 6, manually take a sample at the manual closed sampler and replace the chromatograph for measurement.

Images