Control method and control device of gas chromatography electronic gas circuit and gas chromatography system

Abstract

The invention discloses a control method of a gas chromatography electronic gas circuit, which comprises the following steps: detecting the change of the gas pressure at the outlet of a gas chromatography system, the change of the gas pressure at the outlet characterizing the difference between the previous gas pressure value at the outlet before the atmospheric pressure is changed and the later gas pressure value after the atmospheric pressure is changed; under the condition that the detected air pressure change at the outlet is larger than a set change threshold value, the air pressure at the outlet is obtained to be a current pressure value collected by each pressure sensor under the condition that the air pressure at the outlet is a rear air pressure value, and the pressure sensors are distributed in a gas path of the gas chromatography system; and correcting a given target pressure value after the air pressure at the outlet is changed by using the obtained current pressure values and previous pressure values when the air pressure at the outlet, which is collected by the pressure sensors, is the previous atmospheric pressure value, so as to obtain a corrected given target pressure value, and according to the corrected given target pressure value, correcting the air pressure at the outlet according to the corrected given target pressure value. And a control valve in a gas path of the gas chromatography system is adjusted. According to the invention, the compensation precision during outlet air pressure fluctuation is improved.

Description

Technical Field

[0001] The present invention relates to the field of measuring instruments, and in particular to a control method and a control device for a gas chromatography electronic gas circuit, and a gas chromatography system. Background Art

[0002] Gas chromatography (GC) is an analytical technique used to separate and analyze components in gas or volatile liquid mixtures. During the analysis process, flow control of the analyte sample is an important factor in ensuring the accuracy and reproducibility of the analysis results. It relies on the precise control of the carrier gas flow rate to ensure that the analyte sample migrates at a consistent speed in the chromatographic column. Any fluctuation in the carrier gas flow rate will result in changes in the peak position of the spectrum, which will affect the identification of the analyte sample and the accuracy of the analysis results. Summary of the invention

[0003] The invention provides a method for controlling a gas chromatograph electronic gas circuit to improve the control accuracy.

[0004] A first aspect of the present invention provides a method for controlling a gas chromatograph electronic gas circuit, the method comprising: Detect the change of gas pressure at the outlet of the gas chromatography system. The change of gas pressure at the outlet represents the difference between the previous gas pressure value at the outlet before the atmospheric pressure changes and the subsequent gas pressure value at the outlet after the atmospheric pressure changes. When the detected change in the outlet pressure is greater than a set change threshold, the current pressure value collected by each pressure sensor when the outlet pressure is the subsequent outlet pressure value is obtained, wherein each pressure sensor is distributed in the gas path of the gas chromatography system, By using the acquired current pressure values ​​and the previous pressure values ​​collected by the pressure sensors when the air pressure at the outlet is the previous air pressure value at the outlet, the given target pressure value after the air pressure at the outlet changes is corrected, so that the response delay caused by the gas path length of the gas chromatography system is suppressed, and the corrected given target pressure value is obtained. According to the corrected given target pressure value, the control valve in the gas circuit of the gas chromatography system is adjusted so that the pressure value collected by the pressure sensor used to detect the target pressure value reaches the corrected given target pressure value.

[0005] As an implementation method, the gas path length is the gas path length from the carrier gas source to the outlet; As an implementation mode, the method of using the acquired current pressure values ​​and the previous pressure values ​​collected by the pressure sensors when the air pressure at the outlet is the previous air pressure value at the outlet to correct the given target pressure value after the air pressure at the outlet changes includes: For any pressure sensor, calculate the ratio between the current pressure value collected by the pressure sensor and the previous pressure value, All calculated ratios are weighted averaged to obtain the first correction coefficient for compensating for the pressure fluctuation at the outlet. The product of the first correction coefficient and the given target pressure value after the air pressure at the outlet changes is calculated to obtain the corrected given target pressure value.

[0006] As an embodiment, the given target pressure value after the air pressure at the outlet changes is determined based on at least the carrier gas flow rate, carrier gas viscosity, gas path length, gas path cross-sectional size, current carrier gas temperature, the subsequent air pressure value at the outlet, the reference pressure value of the carrier gas, and the reference temperature of the carrier gas input into the gas chromatography system.

[0007] As an embodiment, the given target pressure value after the outlet pressure changes is determined based on at least the carrier gas flow rate, carrier gas viscosity, gas path length, gas path cross-sectional size, current carrier gas temperature, the subsequent gas pressure value at the outlet, the reference pressure value of the carrier gas, and the reference temperature, including: Calculate the product of the carrier gas flow rate, carrier gas viscosity, gas path length, current carrier gas temperature, the ratio of the reference pressure value of the carrier gas to the reference temperature, and a constant to obtain the product result, where the constant is the ratio of a value of 16 to pi. Calculate the ratio between the product result and the fourth power function value of the gas path cross-sectional radius, add the ratio to the square value of the subsequent gas pressure value and then take the square root to obtain the carrier gas pressure value. The difference between the carrier gas pressure value and the subsequent gas pressure value at the outlet is calculated to obtain a given target pressure value after the gas pressure at the outlet changes.

[0008] As an implementation mode, the carrier gas pressure value is corrected by a second correction coefficient for compensating for the delayed response to the pressure fluctuation at the outlet, wherein the second correction coefficient is related to the gas path length. The longer the gas path length, the larger the second correction coefficient. The calculating the difference between the carrier gas pressure value and the rear gas pressure value at the outlet comprises: Calculate the difference between the corrected carrier gas pressure value and the back gas pressure value at the outlet.

[0009] As an implementation manner, each of the pressure sensors at least includes: One or more pre-column pressure sensors located before the inlet of the chromatographic column and one or more post-column pressure sensors located after the outlet of the chromatographic column in the chromatographic column branch of the gas chromatography system; The pressure sensor for detecting the target pressure value is a pressure sensor for characterizing the pressure value inside the injector of the gas chromatography system; The reference pressure value of the carrier gas is the pressure value under standard working conditions, and the reference temperature of the carrier gas is the temperature under standard working conditions.

[0010] As an embodiment, each of the pressure sensors further comprises: pressure sensors located in other branches except the chromatographic column branch, wherein the number of pressure sensors in any other branch is determined according to the gas path length of the branch and the position of interest. The pressure sensor used to characterize the pressure value inside the injector of the gas chromatography system is a purge pressure sensor located in the purge branch of the gas chromatography system. The gas path length is the gas path length between the carrier gas source and the purge pressure sensor.

[0011] As an embodiment, the pressure sensors located in other branches except the chromatographic column branch include: one or more detector pressure sensors located in the detector outlet branch of the gas chromatography system; As an implementation mode, adjusting the control valve in the gas circuit of the gas chromatography system according to the corrected given target pressure value includes: According to the corrected given target pressure value, a shunt control valve located in the shunt path of the gas chromatography system is adjusted in a proportional integral differential (PID) manner so that the pressure value collected by the purge pressure sensor reaches the corrected given target pressure value; The method further comprises: detecting the change of the gas pressure at the outlet of the gas chromatography system; According to the set time, trigger the detection of changes in gas pressure at the outlet of the gas chromatography system.

[0012] A second aspect of the present invention provides a control device for a gas chromatograph electronic gas circuit, the device comprising: The detection module is used to detect the change of the air pressure at the outlet of the gas chromatography system. The change of the air pressure at the outlet represents the difference between the previous air pressure value at the outlet before the atmospheric pressure changes and the subsequent air pressure value at the outlet after the atmospheric pressure changes. The pressure value acquisition module is used to obtain the current pressure value collected by each pressure sensor when the detected outlet pressure change is greater than the set change threshold value, wherein the outlet pressure is the outlet pressure value after the outlet pressure, wherein the pressure sensors are distributed in the gas path of the gas chromatography system, The given target pressure value determination module is used to correct the given target pressure value after the air pressure at the outlet changes by using the acquired current pressure values ​​and the previous pressure values ​​collected by the pressure sensors when the air pressure at the outlet is the previous air pressure value at the outlet, so that the response delay caused by the gas path length of the gas chromatography system is suppressed, and the corrected given target pressure value is obtained. The control module is used to adjust the control valve in the gas circuit of the gas chromatography system according to the corrected given target pressure value, so that the pressure value collected by the pressure sensor used to detect the target pressure value reaches the corrected given target pressure value.

[0013] A second aspect of the present invention provides a gas chromatography system, which includes a memory and a processor, wherein the memory stores a computer program, and the processor is configured to execute the computer program to implement the steps of any of the above-mentioned gas chromatography electronic gas circuit control methods.

[0014] The control method of the electronic gas circuit of the gas chromatograph provided in the embodiment of the present application corrects the given target pressure value after the outlet air pressure changes by using the acquired current pressure values ​​and the previous pressure values ​​collected by the pressure sensors when the air pressure at the outlet is the previous air pressure value at the outlet. It not only integrates the previous pressure information collected by the pressure sensors before the outlet air pressure changes, but also integrates the current pressure information collected by the pressure sensors after the outlet air pressure changes, so that the given target pressure value after the outlet air pressure changes can be accurately corrected, thereby improving the control accuracy. It is beneficial to obtain a constant flow rate, thereby facilitating improving the accuracy of identification and analysis results of samples to be analyzed; a given target pressure value after the outlet pressure changes is determined according to the carrier gas flow rate, carrier gas viscosity, gas path length, gas path cross-sectional size, current carrier gas temperature, the subsequent gas pressure value, the reference pressure value of the carrier gas, and the reference temperature of the input gas chromatography system, so that the degree of influence transmitted to the injector when the outlet pressure fluctuates can be accurately estimated, thereby improving the accuracy of the given target pressure value, further improving the control accuracy, and, there is no need to repeatedly calibrate the system, and the operation is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A flow chart of a method for controlling the electronic gas circuit of a gas chromatograph according to an embodiment of the present application.

[0016] Figure 2 Schematic diagram of the structure of the gas chromatography gas circuit in the gas chromatography system of this embodiment.

[0017] Figure 3 A flow chart of the method for controlling the electronic gas circuit of the gas chromatography in this embodiment.

[0018] Figure 4 A schematic diagram of a control device for a gas chromatograph electronic gas circuit according to an embodiment of the present application.

[0019] Figure 5 Another schematic diagram of the control device of the gas chromatography electronic gas circuit according to the embodiment of the present application. DETAILED DESCRIPTION

[0020] In order to make the objectives, technical means and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings.

[0021] The applicant found that since the outlet of the gas chromatography system leads directly to the atmosphere, when the atmospheric pressure fluctuates, the flow rate in the gas chromatography system will fluctuate. Therefore, when the pressure at the outlet fluctuates during the operation of the gas chromatography system, it is very necessary to compensate for the pressure at the inlet of the system. In order to compensate for the flow difference caused by the change in the pressure at the outlet, it is necessary to test multiple standard reference curves under different working conditions. Not only is the process cumbersome, but if the value points of the standard curve are too coarse, it will not be able to radiate to certain pressure fluctuation amplitude points that have not been taken. If the components such as pipelines cannot be kept consistent with the calibration during the production and manufacturing process of the gas chromatography system or the later material replacement process, there will be errors in the compensation.

[0022] The applicant also found that the overall gas path length in the gas chromatography system is relatively long, especially when a capillary column is used, which is generally more than 30 meters. In addition, due to its low density and viscosity, the gas becomes a good pressure wave buffer carrier. Once the atmospheric pressure outside the gas chromatography system fluctuates, the energy transferred from the outlet of the gas chromatography system to the inlet of the gas chromatography system is continuously dissipated. Therefore, if the inlet pressure is calculated directly based on the outlet pressure, the calculated inlet pressure will have deviations in the case of short-term transient fluctuations in the outlet air pressure.

[0023] In view of this, an embodiment of the present application provides a method for controlling a gas chromatography electronic gas circuit, which improves the control accuracy of the pressure in the gas circuit when the gas pressure at the outlet changes by integrating the pressure values ​​at the sampling points set in the gas circuit of the gas chromatography system.

[0024] See also Figure 1 As shown, Figure 1 This is a flow chart of a method for controlling a gas chromatograph electronic gas circuit according to an embodiment of the present application. The method comprises: Step 101, detecting the change of the gas pressure at the outlet of the gas chromatography system, wherein the change of the gas pressure at the outlet represents the difference between the previous gas pressure value at the outlet before the atmospheric pressure outside the gas chromatography system changes and the subsequent gas pressure value at the outlet after the atmospheric pressure changes. As an example, the detection of the gas pressure at the outlet of the gas chromatography system is triggered according to the set time. For example, the gas pressure value at the outlet is detected at a first time as the previous gas pressure value, and the gas pressure value at the outlet is detected at a second time as the subsequent gas pressure value, wherein the first time is earlier than the second time. It should be understood that since the gas output volume at the outlet of the gas chromatography system is small, its effect on the outlet air pressure is small and can be ignored in practical applications. In this way, the outlet air pressure can be the atmospheric pressure at any outlet of the gas chromatography system leading to the atmosphere, but the present application is not limited to this. The outlet air pressure can also be the actual air pressure value when considering the influence of the gas output volume, for example, the air pressure value detected by the pressure sensor at the outlet.

[0025] Step 102, when the detected change in the outlet pressure is greater than a set change threshold, obtain the current pressure value collected by each pressure sensor when the outlet pressure is the outlet pressure value after the outlet pressure changes, so as to obtain the current pressure value in the gas path after the outlet pressure changes, wherein the pressure sensors are distributed in the gas path of the gas chromatography system, As an example, each pressure sensor includes at least: one or more pre-column pressure sensors located before the chromatographic column inlet in the chromatographic column branch, and one or more post-column pressure sensors located after the chromatographic column outlet. The specific number can be determined by the gas path length of the chromatographic column branch and the position that needs attention.

[0026] As another example, each pressure sensor may further include: a pressure sensor located in other branches except the chromatographic column branch, wherein the number of pressure sensors in any other branch is determined according to the gas path length of the branch and the position of interest, for example, one or more detector pressure sensors located in the detector outlet branch of the gas chromatography system, Step 103, using the acquired current pressure values ​​and the previous pressure values ​​collected by the pressure sensors when the air pressure at the outlet is the previous air pressure value at the outlet, the given target pressure value after the air pressure at the outlet changes is corrected to suppress the response delay caused by the gas path length of the gas chromatography system, and obtain the corrected given target pressure value. As an example, the gas path length is the gas path length between the carrier gas source and the outlet, and more precisely, it can be the gas path length between the carrier gas source and the pressure sensor in the branch where the outlet is located, for example, If the outlet is located at the outlet of the purge branch, the gas path length is the gas path length from the carrier gas source to the purge pressure sensor in the purge branch; If the outlet is located at the outlet of the outlet branch of the detector, the gas path length is the gas path length between the carrier gas source and the detector pressure sensor in the outlet branch of the detector; If the outlet is the system outlet where any two or more branches of the purge branch, the detector outlet branch, or the diversion branch converge, the gas path length is the sum of the gas path lengths from the carrier gas source to the pressure sensors in the converged branches.

[0027] As an example, for any pressure sensor, the ratio between the current pressure value collected by the pressure sensor and the previous pressure value is calculated. All calculated ratios are weighted averaged to obtain the first correction coefficient for compensating for the pressure fluctuation at the outlet. The product of the first correction coefficient and the given target pressure value after the air pressure at the outlet changes is calculated to obtain the corrected given target pressure value.

[0028] As an example, a given target pressure value after the outlet pressure changes is obtained by the Poiseuille-Hagen law combined with the ideal gas state equation. For example, it is determined at least based on the carrier gas flow rate, carrier gas viscosity, gas path length, gas path cross-sectional size, current carrier gas temperature, post-pressure value at the outlet, reference pressure value of the carrier gas, and reference temperature of the input gas chromatography system.

[0029] Step 104, according to the corrected given target pressure value, adjust the control valve in the gas circuit of the gas chromatography system so that the pressure value collected by the pressure sensor for detecting the target pressure value reaches the corrected given target pressure value.

[0030] As an example, the pressure sensor for detecting the target pressure value may be any pressure sensor in the system, or may be a purge pressure sensor located in a purge branch of the gas chromatography system. According to the corrected given target pressure value, the diversion control valve located in the diversion branch of the gas chromatography system is adjusted in a PID manner so that the pressure value collected by the purge pressure sensor reaches the corrected given target pressure value, which is beneficial to improve the adjustment efficiency.

[0031] The control method of the gas chromatography electronic gas circuit provided in the embodiment of the present application corrects the given target pressure value after the air pressure at the outlet changes by utilizing the acquired current pressure values ​​and the previous pressure values ​​collected by the pressure sensors when the air pressure at the outlet is the previous air pressure value at the outlet, thereby eliminating the need to test multiple standard reference curves under different working conditions. In this way, not only does it not require calibration and is easy to operate, but it also improves the accuracy of the given target pressure value, thereby facilitating maintaining a constant flow rate, eliminating interference caused by the gas chromatography system itself, facilitating the stability of the chromatogram, and improving the accuracy of the component type and component amount in the analysis results.

[0032] To facilitate understanding of the embodiments of the present application, the following is an example of a gas chromatography electronic gas path control method for a gas chromatography system. It should be understood that the embodiments of the present application are not limited to the gas path structure of the gas chromatography system, and gas chromatography systems with other gas path structures may also be applicable.

[0033] See also Figure 2 As shown, Figure 2The diagram is a schematic diagram of the structure of the gas chromatography gas circuit in the gas chromatography system of this embodiment. The carrier gas from the carrier gas source flows through the total flow control valve and is input to the injection port of the injector to carry the sample in the injector. The injector is connected to the purge branch, the flow branch and the chromatographic column branch respectively, and the cooperation of each branch ensures the effective separation and detection of the sample. Among them, The purge branch is used for the carrier gas flow to blow out the residue in the system to prevent the impurities introduced by the previous analysis sample or the system due to injection from affecting the current analysis results; The split flow path is activated during injection, and a portion of the sample directly enters the atmosphere or bypass pipe for splitting to avoid excessive sample load on the chromatographic column, while the other portion of the sample enters the chromatographic column. The split ratio is adjusted to adjust the ratio of the sample entering the chromatographic column to the sample entering the split flow path, and the amount of sample injected into the chromatographic column is controlled to maintain the optimal working conditions of the chromatographic column. The chromatographic column splits are used to separate the sample.

[0034] The actual amount of gas entering the column branch is the amount of carrier gas entering the injection port minus the remaining amount of gas entering the purge branch and the split branch. The sample gas entering the chromatographic column enters the detector through the column branch for detection and is then output to the atmosphere. The sample gas entering the split branch is output to the atmosphere, and the gas entering the purge branch is output to the atmosphere.

[0035] As an example, the purge branch includes a purge pressure sensor M and a purge control valve. The shunt path includes a shunt control valve, and may also include a trap and a shunt main valve. The chromatographic column branch includes: a pre-column pressure sensor A, a chromatographic column, and a post-column pressure sensor B, wherein the pre-column pressure sensor A is located at the inlet side of the chromatographic column, and the post-column pressure sensor B is located at the outlet side of the chromatographic column.

[0036] The outlet branch of the detector may also include a detector pressure sensor C.

[0037] Since it is not easy to install a pressure sensor inside the injector, the pressure measured by the purge pressure sensor M on the purge branch is usually used to equal the pressure inside the injector. Therefore, the flow control of the gas chromatography column branch is based on the pressure value collected by the purge pressure sensor M on the purge branch to control the diversion control valve in the diversion branch, thereby controlling the pressure in the injector within the target value.

[0038] See also Figure 3 As shown, Figure 3 The figure is a flow chart of a method for controlling the electronic gas circuit of a gas chromatograph in this embodiment. The method comprises: Step 301, obtaining an initial target pressure value at a given flow rate and an initial outlet pressure value.

[0039] Poiseuille-Hagen law, also known as Poiseuille formula, is a basic principle in fluid dynamics, mainly used to describe the flow of fluid through a cylindrical pipe. In Poiseuille formula, the flow rate of fluid through a section of pipeline is related to the pressure drop between the inlet and outlet of the pipeline, the fluid viscosity, the length of the pipeline and the diameter of the pipeline. Poiseuille formula is only applicable to incompressible fluids (liquids), Newtonian fluids, and laminar flows. There is an increased error in the pipeline flow described for gases and compressible fluids. Poiseuille formula is expressed mathematically as:

[0040] Among them, Q is the fluid flow rate, r is the radius of the pipe diameter, u is the fluid viscosity, L is the pipe length, P o is the outlet pressure of the pipeline, P i is the inlet pressure of the pipeline.

[0041] Compared with liquid chromatography theory, the difference between gas chromatography theory and liquid chromatography theory is that the fluidity is highly compressible due to the gaseous state. Based on the Poiseuille model, the compressibility of the fluid can be considered and extended to the gas. In order to reflect the influence of the pressure at both ends of the pipeline, a dimensionless parameter is introduced: the ratio of the average value of the sum of the inlet and outlet pressures of the pipeline to the inlet pressure. The relationship between the flow rate of the gas flowing through a section of the pipeline and the inlet and outlet pressure drop, gas viscosity, pipeline length and pipe diameter can be expressed as:

[0042] Given that gas is highly compressible and is greatly affected by ambient temperature and pressure, the ideal gas state equation satisfies the following relationship: PV=nRT in, is the gas pressure, V is the gas volume, n is the number of moles of the gas, T is the gas temperature, and R is the ideal gas constant.

[0043] Therefore, for the same number of gas moles, it satisfies:

[0044] Among them, P o is the pressure value of the gas at the pipeline outlet, V o is the gas volume at the pipeline outlet, T o is the gas temperature at the pipeline outlet, P ref is the reference pressure value, V ref is the reference volume, T ref is the reference temperature.

[0045] According to equations 1 and 2, under the premise of a given flow rate, the gas source pressure can be calculated as follows, assuming that the gas pressure at the outlet remains constant:

[0046] Among them, T real is the actual temperature of the gas source.

[0047] In view of the fact that the overall gas path length of the gas chromatograph is relatively long and that gas is a good pressure wave buffer carrier compared to liquid, a correction factor related to the gas path length is introduced into the gas source pressure calculation formula for correction, which can be expressed as follows:

[0048] Among them, α is the correction factor, which is used to compensate for the delayed response of the gas chromatography system to the pressure fluctuation at the outlet. It is also called the second correction factor. It increases with the increase of the gas path length. Its relationship with the gas path length can be determined based on the relationship curve between the correction factor and the gas path length obtained from experimental data.

[0049] The pressure value collected by the purge pressure sensor M is usually used to control the gas source pressure. Therefore, considering the inlet and outlet pressures, gas path length, pipe diameter, gas temperature, and ambient pressure and temperature of the gas chromatography system, the relationship between the actual control flow in the gas path and the pressure difference between the gas source pressure and the outlet pressure can be expressed as follows:

[0050] Among them, P M is the pressure difference between the gas source pressure and the outlet pressure, μ is the viscosity of the carrier gas, Q is the given gas volume of the gas source, T real is the temperature of the carrier gas, P o is the initial outlet pressure value, that is, the current atmospheric pressure value, is the gas path length from the carrier gas source to the purge pressure sensor M, α is the correction factor corresponding to the gas path length L, P ref The value is the standard operating pressure of the carrier gas, T ref is the temperature of the carrier gas under standard operating conditions, usually 25°C.

[0051] The pressure difference calculated according to Formula 3 is used as the initial target pressure value.

[0052] Step 302, adjusting the flow splitting control valve in the flow splitting path so that the pressure value collected by the purge pressure sensor M reaches the initial target pressure value, and obtaining the initial pressure value collected by each pressure sensor when the pressure value collected by the purge pressure sensor M reaches the initial target pressure value as the previous pressure value of each pressure sensor; As an example, keep the gas source pressure unchanged and adjust the diversion control valve in the diversion path through PID control logic. Step 303, triggering the detection of the air pressure at the outlet according to the set duration, and when it is detected that the air pressure at the outlet changes by more than the set change threshold, obtaining the current pressure value collected by each pressure sensor, As an example, the current atmospheric pressure is detected by the atmospheric pressure detection sensor according to the set time length as the subsequent atmospheric pressure value after the atmospheric pressure changes. For example, the atmospheric pressure detection is performed in real time. When the detected atmospheric pressure change at the outlet is greater than the set change threshold, the current pressure value collected by each pressure sensor is obtained to obtain the current pressure value collected by each pressure sensor after the atmospheric pressure changes. In this embodiment, the current pressure values ​​collected by pressure sensors A, B, and C are obtained.

[0053] The atmospheric pressure detection sensor may be located at the outlet leading to the atmosphere of any branch of the diversion branch, the purge branch, or the detector outlet branch.

[0054] Step 304, according to Formula 3, calculate the given target pressure value after the outlet pressure changes, As an example, the product of the carrier gas flow rate, the carrier gas viscosity, the gas path length, the current carrier gas temperature, the ratio of the reference pressure value of the carrier gas to the reference temperature, and a constant is calculated to obtain a product result, wherein the constant is the ratio of a value of 16 to pi, Calculate the ratio between the product result and the fourth power function value of the gas path cross-sectional radius, add the ratio to the square value of the subsequent gas pressure value and then take the square root to obtain the carrier gas pressure value, which represents the carrier gas pressure value after the gas pressure at the outlet changes. The difference between the carrier gas pressure value and the subsequent gas pressure value is calculated to obtain a given target pressure value after the gas pressure at the outlet changes.

[0055] Considering that the ratio between the product result and the fourth power function value of the gas path cross-section radius remains unchanged during the same measurement process of the gas chromatography system, the ratio calculated when determining the initial target pressure value can be stored to reduce computing power and improve computing efficiency; since the gas pressure change at the outlet at this time is the subsequent gas pressure value, the carrier gas pressure value changes with the change of the subsequent gas pressure value, and the given target pressure value will also change.

[0056] The given target pressure value determined in the above manner can accurately determine the degree of influence transmitted to the injector when the gas pressure at the outlet fluctuates.

[0057] In order to compensate for the delayed response of the gas chromatography system to the pressure fluctuation at the outlet, the carrier gas pressure value is corrected by using the second correction coefficient to obtain the corrected carrier gas pressure value. The difference between the corrected carrier gas pressure value and the subsequent pressure value at the outlet is calculated to obtain the given target pressure value after the pressure change at the outlet.

[0058] Step 305, using the current pressure values ​​obtained in step 303 and the previous pressure values ​​obtained in step 302, the given target pressure value after the pressure change at the outlet is corrected to obtain a corrected given target pressure value. As an example, the correction is as follows: For each pressure sensor, a ratio between a current pressure value collected by the pressure sensor and each previous pressure value collected by the pressure sensor is calculated. The ratios of all pressure sensors are weighted averaged to obtain the first coefficient for compensating the pressure fluctuation at the outlet. The first correction coefficient is multiplied by the given target pressure value after the air pressure at the outlet changes to obtain a corrected given target pressure value.

[0059] The above correction method is expressed mathematically as follows:

[0060] Among them, P′ M is the corrected given target pressure value, P M is the given target pressure value after the outlet pressure changes, β i is the weighting coefficient of pressure sensor i,

[0061] In this embodiment, i=3, which are pressure sensors A, B, and C respectively.

[0062] Step 306, according to the corrected given target pressure value, adjust the diversion control valve until the pressure value collected by the purge pressure sensor M reaches the corrected given target pressure value, and obtain the current pressure value collected by each pressure sensor as the previous pressure value; As an example, keep the gas source pressure unchanged and adjust the diversion control valve in the diversion path through PID control logic. Step 307, return to step 304 until the current test process ends.

[0063] In this embodiment, it should be understood that the regulated control valve may be a plurality of control valves in the system, including but not limited to a purge control valve, a total flow control valve, and the like.

[0064] See also Figure 4 As shown, Figure 4 This is a schematic diagram of a control device for a gas chromatograph electronic gas circuit according to an embodiment of the present application. The device comprises: The outlet pressure detection module is used to detect the change of the outlet pressure of the gas chromatography system. The change of the outlet pressure represents the difference between the outlet pressure value before the atmospheric pressure changes and the outlet pressure value after the atmospheric pressure changes. The pressure value acquisition module is used to obtain the current pressure value collected by each pressure sensor when the detected outlet pressure change is greater than the set change threshold value, wherein the outlet pressure is the outlet pressure value after the outlet pressure, wherein the pressure sensors are distributed in the gas path of the gas chromatography system, a given target pressure value determination module, for correcting the given target pressure value after the air pressure at the outlet changes by using the acquired current pressure values ​​and the previous pressure values ​​collected by the pressure sensors when the air pressure at the outlet is the previous air pressure value at the outlet, to obtain a corrected given target pressure value, The control module is used to adjust the control valve in the gas circuit of the gas chromatography system according to the corrected given target pressure value, so that the pressure value collected by the pressure sensor used to detect the target pressure value reaches the corrected given target pressure value.

[0065] As an example, the given target pressure value determination module is also used to determine the given target pressure value after the outlet gas pressure changes based on at least the carrier gas flow rate, carrier gas viscosity, gas path length, gas path cross-sectional size, current carrier gas temperature, the subsequent gas pressure value at the outlet, the reference pressure value of the carrier gas, and the reference temperature of the input gas chromatography system.

[0066] See also Figure 5 As shown, Figure 5 Another schematic diagram of a control device for a gas chromatography electronic gas circuit or a gas chromatography system according to an embodiment of the present application. The device includes a processor and a memory, the memory stores a computer program, the processor inputs pressure values ​​collected from various pressure sensors, and the processor is configured to execute the computer program to execute the steps of the control method for the gas chromatography electronic gas circuit according to the embodiment of the present application to output a control signal to the control valve.

[0067] The memory may include a random access memory (RAM) or a non-volatile memory (NVM), such as at least one disk memory. Optionally, the memory may also be at least one storage device located away from the aforementioned processor.

[0068] The above-mentioned processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0069] An embodiment of the present invention further provides a computer-readable storage medium, in which a computer program is stored. When the computer program is executed by a processor, the steps of the method for controlling the gas chromatography electronic gas circuit described in the embodiment of the present application are implemented.

[0070] As for the apparatus / network-side device / storage medium embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0071] In this article, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for controlling a gas chromatography electronic gas circuit, characterized in that: The method includes: Detect the change of gas pressure at the outlet of the gas chromatography system. The change of gas pressure at the outlet represents the difference between the previous gas pressure value at the outlet before the atmospheric pressure changes and the subsequent gas pressure value at the outlet after the atmospheric pressure changes. When the detected change in the outlet pressure is greater than a set change threshold, the current pressure value collected by each pressure sensor when the outlet pressure is the subsequent outlet pressure value is obtained, wherein each pressure sensor is distributed in the gas path of the gas chromatography system, By using the acquired current pressure values ​​and the previous pressure values ​​collected by the pressure sensors when the air pressure at the outlet is the previous air pressure value at the outlet, the given target pressure value after the air pressure at the outlet changes is corrected, so that the response delay caused by the gas path length of the gas chromatography system is suppressed, and the corrected given target pressure value is obtained. According to the corrected given target pressure value, the control valve in the gas circuit of the gas chromatography system is adjusted so that the pressure value collected by the pressure sensor used to detect the target pressure value reaches the corrected given target pressure value.

2. The control method according to claim 1, characterized in that: The gas path length is the gas path length from the carrier gas source to the outlet; The method uses the acquired current pressure values ​​and the previous pressure values ​​collected by the pressure sensors when the air pressure at the outlet is the previous air pressure value at the outlet to correct the given target pressure value after the air pressure at the outlet changes, including: For any pressure sensor, calculate the ratio between the current pressure value collected by the pressure sensor and the previous pressure value, All calculated ratios are weighted averaged to obtain the first correction coefficient for compensating for the pressure fluctuation at the outlet. The product of the first correction coefficient and the given target pressure value after the air pressure at the outlet changes is calculated to obtain the corrected given target pressure value.

3. The control method according to claim 2, characterized in that: The given target pressure value after the outlet pressure changes is determined based on at least the carrier gas flow rate, carrier gas viscosity, gas path length, gas path cross-sectional size, current carrier gas temperature, the subsequent gas pressure value at the outlet, the reference pressure value of the carrier gas, and the reference temperature of the carrier gas.

4. The control method according to claim 3, characterized in that: The given target pressure value after the outlet pressure changes is determined based on at least the carrier gas flow rate, carrier gas viscosity, gas path length, gas path cross-sectional size, current carrier gas temperature, the subsequent gas pressure value at the outlet, the reference pressure value of the carrier gas, and the reference temperature of the carrier gas, including: Calculate the product of the carrier gas flow rate, carrier gas viscosity, gas path length, current carrier gas temperature, the ratio of the reference pressure value of the carrier gas to the reference temperature, and a constant to obtain the product result, where the constant is the ratio of a value of 16 to pi. Calculate the ratio between the product result and the fourth power function value of the gas path cross-sectional radius, add the ratio to the square value of the rear gas pressure value at the outlet and then take the square root to obtain the carrier gas pressure value. The difference between the carrier gas pressure value and the subsequent gas pressure value at the outlet is calculated to obtain a given target pressure value after the gas pressure at the outlet changes.

5. The control method according to claim 4, characterized in that: The carrier gas pressure value is corrected by a second correction coefficient for compensating for the delayed response to the pressure fluctuation at the outlet, wherein the second correction coefficient is related to the gas path length. The longer the gas path length, the larger the second correction coefficient. The calculating the difference between the carrier gas pressure value and the rear gas pressure value at the outlet comprises: Calculate the difference between the corrected carrier gas pressure value and the back gas pressure value at the outlet.

6. The control method according to claim 5, characterized in that: Each of the pressure sensors at least comprises: One or more pre-column pressure sensors located before the inlet of the chromatographic column and one or more post-column pressure sensors located after the outlet of the chromatographic column in the chromatographic column branch of the gas chromatography system; The pressure sensor for detecting the target pressure value is a pressure sensor for characterizing the pressure value inside the injector of the gas chromatography system; The reference pressure value of the carrier gas is the pressure value under standard working conditions, and the reference temperature of the carrier gas is the temperature under standard working conditions.

7. The control method according to claim 6, characterized in that: The pressure sensors also include pressure sensors located in other branches except the chromatographic column branch, wherein the number of pressure sensors in any other branch is determined according to the gas path length of the branch and the position to be concerned. The pressure sensor used to characterize the pressure value inside the sample injector of the gas chromatography system is a purge pressure sensor located in the purge branch of the gas chromatography system. The gas path length is the gas path length between the carrier gas source and the purge pressure sensor.

8. The control method according to claim 7, characterized in that: The pressure sensors located in other branches except the chromatographic column branch include: one or more detector pressure sensors located in the detector outlet branch of the gas chromatography system; The method of adjusting the control valve in the gas circuit of the gas chromatography system according to the corrected given target pressure value comprises: According to the corrected given target pressure value, a shunt control valve located in the shunt path of the gas chromatography system is adjusted in a proportional integral differential (PID) manner so that the pressure value collected by the purge pressure sensor reaches the corrected given target pressure value; The method further comprises: detecting the change of the gas pressure at the outlet of the gas chromatography system; According to the set time, trigger the detection of changes in gas pressure at the outlet of the gas chromatography system.

9. A control device for a gas chromatography electronic gas circuit, characterized in that: The device includes: The detection module is used to detect the change of the air pressure at the outlet of the gas chromatography system. The change of the air pressure at the outlet represents the difference between the previous air pressure value at the outlet before the atmospheric pressure changes and the subsequent air pressure value at the outlet after the atmospheric pressure changes. The pressure value acquisition module is used to obtain the current pressure value collected by each pressure sensor when the detected outlet pressure change is greater than the set change threshold value, wherein the outlet pressure is the outlet pressure value after the outlet pressure, wherein the pressure sensors are distributed in the gas path of the gas chromatography system, The given target pressure value determination module is used to correct the given target pressure value after the air pressure at the outlet changes by using the acquired current pressure values ​​and the previous pressure values ​​collected by the pressure sensors when the air pressure at the outlet is the previous air pressure value at the outlet, so that the response delay caused by the gas path length of the gas chromatography system is suppressed, and the corrected given target pressure value is obtained. The control module is used to adjust the control valve in the gas circuit of the gas chromatography system according to the corrected given target pressure value, so that the pressure value collected by the pressure sensor used to detect the target pressure value reaches the corrected given target pressure value.

10. A gas chromatography system, characterized in that: The system comprises a memory and a processor, wherein the memory stores a computer program, and the processor is configured to execute the computer program to implement the steps of the method for controlling the electronic gas circuit of a gas chromatograph as claimed in any one of claims 1 to 8.

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