A concentration continuously adjustable dilution device based on critical flow technology

Abstract

The application discloses a dilution device with continuously adjustable concentration based on critical flow technology, which is composed of a sample gas critical flow path, a dilution gas critical flow path and a tank filling three-way component; the sample gas critical flow path comprises a sample gas pneumatic pressure regulating valve, a sample gas sample inlet pressure sensor, a sample gas critical flow path group and a multi-position gating valve which are sequentially connected through a gas conveying pipe; the dilution gas critical flow path comprises a dilution gas pressure regulating valve, a dilution gas sample inlet pressure sensor and a dilution gas critical flow path which are sequentially connected through a gas conveying pipe; the sample gas critical flow path and the dilution gas critical flow path are connected with the gas inlet of the tank filling three-way component, and the tank filling three-way component mixes the sample gas and the dilution gas and fills the tank. The application adopts the critical flow technology combined with the ultra-limit zero dead volume structure to realize the continuous dilution of the gas; the whole gas conveying pipeline is treated by silanization, and the tank filling three-way component realizes the static tank filling of the gas after the dilution is completed; the device has a long continuous working time, stable flow and a sample flow which can be as low as 0.5 mL / min.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gas dilution equipment, and particularly relates to a dilution device with continuously adjustable concentration based on critical flow technology. BACKGROUND

[0002] Standard gases belong to standard substances, and the standard substances are highly uniform, stable in performance and accurate in quantity value, and have a basic role of reproducing, preserving and transmitting quantity value. The standard substances are used in the fields of physics, chemistry, biology and engineering measurement to calibrate measuring instruments and measurement processes, evaluate the accuracy of measurement methods and the detection capability of detection laboratories, determine the characteristic quantity value of materials or products, and perform quantity arbitration. The standard gases can be used for quality control of gas products, detection and calibration of instruments, detection of atmospheric environmental pollution, medical health and clinical tests, etc.

[0003] The critical flow technology mainly embodies the efficiency of an acoustic nozzle based on the Venturi principle in flow control work, that is, under the condition that the gas pressure at the inlet of the acoustic nozzle is much greater than the gas pressure at the outlet of the acoustic nozzle, the size of the output flow is not affected by the change of the outlet gas pressure. This unique performance embodies the fact that the acoustic nozzle designed based on the critical flow technology is universally used in the fields of measurement and environmental protection to transmit the standard to other types of gas flow meters, and the acoustic nozzle can be directly traced to the national gas flow primary standard device. Therefore, the critical flow technology occupies an important position in the gas flow value traceability system, and is a key link to ensure the accuracy and reliability of gas flow measurement.

[0004] Due to the limitation of standard gas preparation technology, the preparation concentration of SO2, NO X , CO, CO2 and other standard gases is mostly above 10 ppm. Therefore, in order to meet the traceability requirements of trace-level gas concentration analyzers, a gas diluter is needed to dilute the standard gas in a certain range to output the standard gas with a target concentration, and complete the traceability of the trace-level gas concentration analyzer. The commonly used gas diluter on the market is mostly a flow ratio mixing method to realize the dilution of single or multiple gases. For example, when single standard gas is diluted, two other flow control components are used to control the flow of the standard gas to be diluted and the carrier gas respectively. Different dilution multiples are realized by selecting other flow control components with different ranges. When multiple standard gases are diluted, multiple flow control components are used to control the flow of different types of standard gases. However, the existing dilution device has the problems of long pipeline, many internal dead angles, large dead volume, obvious adsorption of gas, poor flow stability, and the like. SUMMARY

[0005] The application aims at overcoming the defects of the prior art and providing a dilution device with continuously adjustable concentration based on critical flow technology.

[0006] The application achieves the aim by the following technical scheme: a dilution device with continuously adjustable concentration based on critical flow technology, which is composed of a sample gas critical flow path, a dilution gas critical flow path and a tank filling three-way component.

[0007] The sample gas critical flow path comprises, in sequence through a gas conveying pipe, a sample gas pneumatic pressure regulating valve, a sample gas sample inlet pressure sensor, a sample gas critical flow path group and a multi-position on-off valve.

[0008] The dilution gas critical flow path comprises, in sequence through a gas conveying pipe, a dilution gas pressure regulating valve, a dilution gas sample inlet pressure sensor and a dilution gas critical flow path.

[0009] The sample gas critical flow path and the dilution gas critical flow path are connected with the gas inlet of the tank filling three-way component, and the tank filling three-way component mixes the sample gas and the dilution gas and fills the tank.

[0010] Further, the sample gas pneumatic pressure regulating valve is composed of a spring, a diaphragm, a control gas cavity, a controlled gas cavity, a two-position three-way electromagnetic valve, a control gas inlet, a control gas outlet, a controlled gas inlet, a controlled gas outlet, a movable valve core plug and a silanized stainless steel valve body.

[0011] The diaphragm divides the cavity wrapped by the silanized stainless steel valve body into an upper gas cavity and a lower gas cavity, the upper gas cavity is the control gas cavity, and the lower gas cavity is the controlled gas cavity; the control gas inlet and the control gas outlet are arranged on the upper part of the silanized stainless steel valve body, the control gas inlet is communicated with the control gas cavity, and the control gas outlet is communicated with the control gas cavity through the two-position three-way electromagnetic valve.

[0012] The silanized stainless steel valve body is provided with the controlled gas inlet and the controlled gas outlet at the lower part, both of which are communicated with the controlled gas cavity through channels; the controlled gas cavity is in the shape of a conical funnel, the movable valve core plug is vertically connected with the lower part of the diaphragm, the bottom of the movable valve core plug is connected with one end of the spring, the other end is connected with the inner wall of the bottom of the silanized stainless steel valve body, the movable valve core plug is in the same shape as the controlled gas cavity, and the movable valve core plug seals the controlled gas cavity and can move up and down in the controlled gas cavity.

[0013] Further, a sealing gasket is arranged on the sidewall of the silanized stainless steel valve body at the funnel mouth of the controlled gas cavity.

[0014] Further, the channels in the sample gas critical flow path group are connected in parallel, one end of each critical flow path is connected with the sample gas sample inlet pressure sensor, and the other end is connected with different gas inlets of the multi-position on-off valve respectively.

[0015] Further, the filling tank three-way component is composed of a silanized stainless steel base, a filling tank pressure sensor, a stirring pipe, a combined three-way sample gas inlet, a combined three-way dilution gas inlet, a device gas outlet and a emptying port, the silanized stainless steel base is T-shaped, a pressure detection groove is arranged on the vertical section of the base, the combined three-way sample gas inlet, the combined three-way dilution gas inlet, the device gas outlet and the emptying port are arranged on the horizontal section of the upper part of the silanized stainless steel base, and the detection end of the filling tank pressure sensor is embedded in the stainless steel base and extends into the pressure detection groove; the stirring pipe is arranged in the horizontal section of the upper part of the silanized stainless steel base, the combined three-way sample gas inlet and the combined three-way dilution gas inlet are communicated with the gas inlet of the stirring pipe, and the device gas outlet and the emptying port are communicated with the gas outlet of the stirring pipe and the pressure detection groove.

[0016] Further, the stirring pipe is a variable diameter pipe with gradually increasing diameter, a spiral winding pipe or a U-shaped pipe, and is prepared from a 1 / 8 inch diameter stainless steel pipe material treated by silanization.

[0017] Further, the gas pipeline of the sample gas critical flow passage and the dilution gas critical flow passage is a 1 / 4-1 / 16 inch diameter stainless steel pipeline treated by silanization.

[0018] Further, the flow range of the sample gas critical flow passage group is 0-300 ml / min, and the flow range of the dilution gas critical flow passage is 1000-5000 ml / min.

[0019] Further, the gas inlet of the multi-position selection valve is 2-12.

[0020] Further, the range of the sample gas inlet pressure sensor and the dilution gas inlet pressure sensor is 0-1Mpa, and the error is less than 0.1%; the internal control temperature of the concentration continuous adjustable device based on the critical flow technology is 20-60℃.

[0021] The present application has the following advantages:

[0022] 1. In the critical flow passage in the present application, the combination of the pneumatic pressure regulating valve, the pressure sensor and the multi-position selection valve is adopted, so that the continuous dilution of the gas is realized, and the pneumatic pressure regulating valve greatly reduces the line needed to be passed during the sample gas pressure regulation compared with the traditional electromagnetic valve, and the volume of the gas cavity squeezed by the pressure is small, so that the gas can be conveniently replaced for the purge during the dilution.

[0023] 2. The present application adopts the silanization treatment of the whole gas pipeline, and the filling tank three-way component can realize the static filling tank of the gas after the dilution, that is, the sample can be directly taken from the filled Suma tank and other containers for analysis. Therefore, the present application is suitable for NH3, H2S, Cl2, CH4, halogenated hydrocarbon and various VOCs and other environmental gases, and realizes the low adsorption, low residue and corrosion resistance of the whole device.

[0024] 3、The application adopts critical flow technology, combines with ultra-limit zero dead volume structure, can make the gas entering the device under different pressure keep stable and controllable flow, and further reduce dilution ratio error and gas adsorption. The dilution process is not affected by outlet pressure change, relaxes the requirements of the device to the use environment, and can be used for trace gas analysis. The device has long continuous working time, stable flow, and sample flow can be as low as 0.5 mL / min, reduces the use cost of standard substance, and can also be used for dilution of high adsorption and high corrosive gas. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a device structure schematic diagram of the application.

[0026] Figure 2 It is a structure schematic diagram of the sample gas pneumatic pressure regulating valve.

[0027] Figure 3 It is a longitudinal section schematic diagram of the tank filling tee component.

[0028] Figure 4 It is a top view structure diagram of the tank filling tee component.

[0029] Figure 5 It is a device flow stability test result diagram of the application.

[0030] Figure 6 It is a precision verification result diagram of the device diluting 20 times of the application.

[0031] Figure 7 It is a precision verification result diagram of the device diluting 50 times of the application.

[0032] Figure 8 It is a precision verification result diagram of the device diluting 100 times of the application.

[0033] Figure 9 It is a precision verification result diagram of the device diluting 200 times of the application.

[0034] Figure 10 It is a precision verification result diagram of the device diluting 500 times of the application.

[0035] Figure 11 It is a precision verification result diagram of the device diluting 1000 times of the application.

[0036] Figure 12 It is a device adsorption experiment result diagram of the application.

[0037] In the diagram, 1-dilution gas inlet, 2-sample gas inlet, 3-sample gas pneumatic pressure regulating valve, 301-spring, 302-diaphragm, 303-control gas chamber, 304-controlled gas chamber, 305-valve I, 306-valve II, 307-control gas inlet, 308-control gas outlet, 309-controlled gas inlet, 310-controlled gas outlet, 311-movable valve plug, 312-silanized stainless steel valve body, 313-sealing gasket, 4-dilution gas inlet. 5-Pressure sensor, 6-Dilution gas critical flow channel, 7-Gas delivery pipeline, 8-Dilution gas pressure regulating valve, 9-Sample gas inlet pressure sensor, 10-Sample gas critical flow channel group, 11-Multi-position selector valve, 11-Filling tank tee assembly, 111-Silanized stainless steel base, 112-Filling tank pressure sensor, 113-Stirring tube, 114-Combined tee sample gas inlet, 115-Combined tee dilution gas inlet, 116-Device outlet, 117-Exhaust port, 118-Pressure detection tank. Detailed Implementation

[0038] The present invention will be further described below with reference to the accompanying drawings and embodiments. The scope of protection of the present invention is not limited to the following description:

[0039] like Figure 1 As shown, a concentration-adjustable dilution device based on critical flow technology consists of a sample gas critical flow path, a dilution gas critical flow path, and a filling three-way assembly 11.

[0040] The critical flow path of the sample gas includes a sample gas pneumatic pressure regulating valve 3, a sample gas inlet pressure sensor 8, a sample gas critical flow channel group 9, and a multi-position selector valve 10, which are connected in sequence through a gas delivery pipe.

[0041] The dilution gas critical flow path includes a dilution gas pressure regulating valve 7, a dilution gas inlet pressure sensor 4, and a dilution gas critical flow channel 5, which are connected in sequence through a gas delivery pipe.

[0042] The critical flow path of the sample gas and the critical flow path of the dilution gas are connected to the air inlet of the filling three-way assembly 11, which mixes the sample gas and the dilution gas and fills the can.

[0043] The preferred ranges for the sample gas inlet pressure sensor 8 and the dilution gas inlet pressure sensor 4 are 0–1 MPa, with an error of less than 0.1%.

[0044] like Figure 2 As shown, the sample gas pneumatic pressure regulating valve 3 is composed of a spring 301, a diaphragm 302, a control gas chamber 303, a controlled gas chamber 304, a two-position three-way solenoid valve, a control gas inlet 307, a control gas outlet 308, a controlled gas inlet 309, a controlled gas outlet 310, a movable valve core plug 311, and a silanized stainless steel valve body 312.

[0045] The diaphragm 302 divides the cavity wrapped by the silanized stainless steel valve body 312 into an upper gas cavity and a lower gas cavity, the upper gas cavity being a control gas cavity 303 and the lower gas cavity being a controlled gas cavity 304; a control gas inlet 307 and a control gas outlet 308 are arranged on the upper part of the silanized stainless steel valve body 312, the control gas inlet 307 being in communication with the control gas cavity 303, and the control gas outlet 308 being in communication with the control gas cavity 303 through a two-position three-way electromagnetic valve;

[0046] The silanized stainless steel valve body 312 is provided with a controlled gas inlet 309 and a controlled gas outlet 310 on the lower part, both being in communication with the controlled gas cavity 304 through a passage; the controlled gas cavity 304 is in the shape of a conical funnel, the movable valve core plug 311 is vertically connected to the lower part of the diaphragm 302, the bottom of the movable valve core plug 311 is connected to one end of the spring 301, and the other end is connected to the inner wall of the bottom of the silanized stainless steel valve body 312, the shape of the movable valve core plug 311 is the same as that of the controlled gas cavity 304, the movable valve core plug 311 seals the controlled gas cavity 304 and can move up and down in the controlled gas cavity 304. The side wall of the silanized stainless steel valve body 312 at the funnel mouth of the controlled gas cavity 304 is further provided with a sealing gasket 313. The spring 301 is preferably made of Hastelloy material, and the sealing mode between the sealing gasket 313 and the movable valve core plug 311 is preferably an NPT hard sealing mode.

[0047] The diaphragm of the sample gas pneumatic pressure regulating valve 3 is an upwardly convex diaphragm, in the initial state, the movable valve core plug 311 seals the controlled gas cavity 304, when the control gas is introduced into the control gas cavity 303 from the control gas inlet 307, the pressure generated by the control gas cavity acts on the diaphragm 302, at this time the diaphragm 302 will be pressed downward, at the same time driving the movable valve core plug 311 to move downward, so that the movable valve core plug 311 moves downward, a gap is generated between the movable valve core plug 311 and the sealing gasket 313, and then the controlled gas can be transported from the left side of the controlled gas cavity 304 to the controlled gas outlet 310. In this process, through the regulation of the two-position three-way electromagnetic valve, the on-off of the sample gas valve is selected to introduce or exhaust the control gas, and then the size of the gas pressure in the control gas cavity 303 is adjusted to change the gap between the movable valve core plug 311 and the sealing gasket 313, and finally the function of adjusting the gas pressure at the front end of the sample gas of the dilution device is achieved.

[0048] As Figure 1As shown, the sample gas critical flow channel group 9 is multiple, six critical flow channel groups are shown in the figure, L1, L2, L3, L4, L5 and L6, each channel is connected in parallel, one end of each critical flow channel is connected with the sample gas inlet pressure sensor 8, and the other end is respectively connected with different gas inlets of the multi-position selector valve 10. A constant sample gas flow can be provided under stable pressure to participate in dilution, which is not affected by the pressure of the gas outlet, and the flow range of the sample gas critical flow channel group 9 is preferably 0-300 ml / min. When the flow of a single critical flow channel exceeds the adjustment range, it can be automatically switched to the next critical flow channel with corresponding flow, to realize automatic generation of different gas concentrations, and the multi-position selector valve 10 is preferably a one-turn multi-position corrosion-resistant valve with 2-12 gas inlets. The critical flow channel is preferably a critical flow nozzle, and the flow range of the dilution gas critical flow channel 5 is 1000-5000 ml / min.

[0049] As shown in Figure 3 The filling tank three-way assembly 11 is composed of a silanized stainless steel base 111, a filling tank pressure sensor 112, a stirring pipe 113, a combined three-way sample gas inlet 114, a combined three-way dilution gas inlet 115, a device gas outlet 116 and a emptying port 117. The silanized stainless steel base 111 is T-shaped, a pressure detection groove 118 is formed in the vertical section of the base, the combined three-way sample gas inlet 114, the combined three-way dilution gas inlet 115, the device gas outlet 116 and the emptying port 117 are arranged on the horizontal section of the upper part of the silanized stainless steel base 111, the detection end of the filling tank pressure sensor 112 is embedded in the silanized stainless steel base 111 and extends into the pressure detection groove 118, and the range is preferably (0-0.6 Mpa) with an error of less than 0.1%; the stirring pipe 113 is arranged in the horizontal section of the upper part of the silanized stainless steel base 111, the combined three-way sample gas inlet 114 and the combined three-way dilution gas inlet 115 are in communication with the gas inlets of the stirring pipe 113, and the device gas outlet 116 and the emptying port 117 are in communication with the gas outlet of the stirring pipe 113 and the pressure detection groove 118.

[0050] The stirring pipe 113 is a variable diameter pipe with gradually increasing diameter, which is a spiral winding pipe or a U-shaped pipe, and can be selected according to the different flow used by the dilution device. The sample gas and the dilution gas get some pressure rise at the front end of the stirring pipe 113 because of the small pipe diameter, and quickly enter the middle section of the stirring pipe 113 with large diameter, and the larger volume makes the sample gas and the dilution gas fully mixed and output. As shown in Figure 4 The stirring pipe 113 is a U-shaped pipe, which is made of a 1 / 8 inch diameter stainless steel pipe material treated by silanization.

[0051] When the sample gas and the dilution gas enter the filling three-way component 11 from the combined three-way sample gas inlet 114 and the combined three-way dilution gas inlet 115 respectively, the stirring pipe 113 and the filling pressure sensor 112 built in the filling three-way component 11 monitor the filling pressure in the tank in real time, and can regulate the size of the filling gas flow in combination with the set filling pressure and the front-end sample gas pneumatic pressure regulating valve 3, and serve as a volume for equivalent detection of the tank pressure during filling of the tank. After the sample gas and the dilution gas enter the filling three-way component 11, due to the structural design of the three-way component, the interference of the two gas flows in the T-shaped pipe is extremely low, and the whole gas conveying process is "zero dead volume", which maximally reduces the residue and keeps the outlet unobstructed, so that the working conditions of the critical flow component are relaxed.

[0052] The diameter of the gas conveying pipe of the sample gas critical flow path and the dilution gas critical flow path is 1 / 4-1 / 16 inch stainless steel pipeline, which is treated by silanization.

[0053] The whole device of the application is operated under temperature control, and the control temperature can be controlled according to the characteristics of the gas used, and is preferably selected in the range of 20-60℃.

[0054] The working principle of the present application is as follows: diluent gas is introduced into the diluent gas inlet 1 of the device, and the diluent gas flows in two routes, one of which flows to the diluent gas pressure regulating valve 7, and the diluent gas passes through the diluent gas pressure regulating valve 7, the diluent gas inlet pressure sensor 4, the diluent gas critical flow channel 5, and flows to the combined three-way sample gas inlet 114 of the filling tank three-way assembly 11, and the other flows to the sample gas pneumatic pressure regulating valve 3, and the control gas inlet 307 of the sample gas pneumatic pressure regulating valve 3 as control gas flows into the control gas cavity 303, the sample gas to be diluted is introduced into the sample gas inlet 2 of the device, and the sample gas enters the controlled gas cavity 304 through the control gas inlet 309 of the sample gas pneumatic pressure regulating valve 3, the flow rate of the control gas is adjusted, the pressure generated by the control gas cavity 303 acts on the diaphragm 302, generates downward pressure on the diaphragm 302, and drives the movable valve core plug 311 to move downward, a gap is formed between the movable valve core plug 311 and the sealing gasket 313, and then the controlled gas can be transported from the left side of the controlled gas cavity 304 to the controlled gas outlet 310, thereby realizing the pressure adjustment of the controlled gas, i.e. the sample gas, during the process, the gas valve I 305 and the gas valve II 306 of the two-position three-way electromagnetic valve are in the closed device, if the pressure of the controlled gas is too large, the gas valve I 305 is opened, the diluent gas in the control cavity flows out through the control gas outlet 308 along the channel I, thereby realizing the reduction of the pressure of the sample gas. Closing the gas valve I 305 and opening the gas valve II 306 form a passage with pressure maintaining function. The pressure-adjusted diluent gas flows into the sample gas inlet pressure sensor 8, the number of passages of the sample gas critical flow channel group 9 is determined according to the concentration of the diluent gas, the quantity of the diluent gas is controlled by opening the passages in the multi-position selector valve 10 and closing the other passages, the diluent gas flows into the stirring tube 113 through the combined three-way diluent gas inlet 115 of the filling tank three-way assembly 11, and the sample gas and the diluent gas are fully mixed in the stirring tube 113. Since the device outlet 116 and the emptying port 117 are connected with the outlet of the stirring tube 113 and the pressure detection groove 118, the device outlet 116 of the filling tank three-way assembly 11 is connected with the Suma tank and other containers, and the diluted gas can be directly filled into the tank. When filling the tank, the filling pressure in the tank is monitored in real time, and the filling pressure can be adjusted by combining the set filling pressure and the front-end sample gas pneumatic pressure regulating valve 3. At this time, the pressure detection groove 118 can be used as a volume for equivalent detection of the pressure in the tank, and the pressure is detected by the filling pressure sensor 112. The filling pressure can also be adjusted by controlling the emptying port 117 of the filling tank three-way assembly 11.

[0055] Example 1

[0056] The flow repeatability of the sample gas critical flow channel and the diluent gas critical flow channel of the diluent device based on the critical flow technology of the present application is tested by using a piston flow meter.

[0057] S1. Turn on and preheat the dilution device, close the sample gas inlet and waste gas outlet of the dilution device.

[0058] S2. After the preheating of the dilution device is completed, 99.999% N2 is connected to the dilution gas inlet of the device through a pressure reducing valve, and N2 is input into the critical flow path of the dilution gas of the device.

[0059] S3. The device is operated to adjust the inlet pressure to 500 Kpa (±0.5 Kpa) through a pressure regulating valve, and normal dilution activities are carried out.

[0060] S4. Connect the device outlet of the device to the inlet of the electronic piston flowmeter for flow testing.

[0061] S5. Record the flow value of the dilution gas critical flow path obtained by collection, draw a curve, and calculate the repeatability.

[0062] S6. After completing the flow repeatability test of the dilution gas end, 99.999% N2 is connected to the dilution gas inlet of the device through a pressure reducing valve, and N2 is input into the sample gas channel of the device.

[0063] S7. Repeat S3 to S4 to obtain the flow value of the sample gas channel, record it, draw a curve, and calculate the repeatability.

[0064] The flow stability collected in the specific experiment is shown in Figure 5 .

[0065] Example 2

[0066] This experiment uses an online drift compensation sampling method, i.e. an "ABAB" alternating sampling method. The n-hexane sample diluted by the device according to a certain dilution ratio is introduced into the Channel 2 of the FID, and the n-hexane standard gas with a concentration close to that after dilution by the device is introduced into the Channel 1 of the FID. The analyzed peak shape of Channel 1 is shown in Figures 6 to 11 , and the analyzed peak shape of Channel 2 is shown in Figures 6 to 11 . By comparing the peak height and peak area (concentration response) of the peak shape of each channel, the drift of the system is eliminated, and the precise verification of the dilution ratio is realized. According to the above method, six dilution points of dilution 20, 50, 100, 200, 500 and 1000 times are verified.

[0067] S1. Turn on and preheat the device, connect 99.999% N2 and 1000 ppm isobutane standard gas to the dilution gas inlet and sample gas inlet of the device, respectively.

[0068] S2. The input pressure of the dilution gas and the sample gas is adjusted to 500 Kpa or above by a pressure reducing valve.

[0069] S3. The desired dilution ratio is selected, and the device is adjusted by the feedback of the software to achieve accurate control of the dilution ratio. The outlet gas of the device passes through FID Channel 1, and isobutane standard gas with a concentration similar to that of the diluted gas is introduced into FID Channel 2.

[0070] S4. The dilution ratio verification of 20, 50, 100, 200, 500, and 1000 times is completed in sequence.

[0071] S5. On the chromatographic workstation, the peak height and peak area of the target peak obtained by dilution at each dilution ratio are intercepted, and the peak height and peak area of the corresponding standard gas are intercepted for comparison.

[0072] As shown in Figures 6 to 11 Peak shape 1 and peak shape 3 are both the peak shape of 10 ppm isobutane gas directly injected, and peak shape 2 and peak shape 4 are the peak shape of 1000 ppm isobutane standard gas diluted to 10 ppm by the device and then injected.

[0073] Example 3:

[0074] In this experiment, the online drift compensation injection method, i.e. the "ABAB" alternating injection method, is used. 0.100 ppm of 57-component VOCs gas is used, one path is introduced into the sample gas channel of the device, and then output from the outlet of the device. The output gas enters the mass spectrometry Channel 1 for injection analysis at a certain flow rate. At the same time, the other path is the same bottle of standard gas, which is split and introduced into the mass spectrometry Channel 2 for injection analysis at the same flow rate. This experiment is used to verify that there is no adsorption in the device.

[0075] S1. The 57-component VOCs standard gas with a concentration of 0.100 ppm is reduced in pressure by a passivation pressure reducing valve, and then connected to a passivation three-way pipe for two-way output. One path is connected to the mass spectrometry Channel 2 for direct injection, and the other path is connected to the sample gas inlet of the device.

[0076] S2. The device is started and preheated, and the 57-component VOC standard gas with a concentration of 0.100 ppm is connected to the sample gas inlet of the device and passes through the whole gas path of the device.

[0077] S3. The VOCs standard gas passing through the whole gas path of the device is introduced into the mass spectrometry Channel 1, and the flow rate is consistent with that of the path directly entering the mass spectrometry Channel 2.

[0078] S4. On the mass spectrometry workstation, the peak height and peak area of the two paths of gas are intercepted and compared.

[0079] The experimental results are shown in Table 1 and Figure 7 .

[0080] Table 1: Deviation results of each substance

[0081] .

[0082] As shown in Figure 12 : the blue peak shape (direct injection of 57-component VOC standard gas) and the red peak shape (full-line injection of 57-component VOC standard gas through the dilution device) are basically coincident, and the peak area values are also consistent.

[0083] The above merely describes preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art, according to the technical solution and inventive concept of the present application, can make equivalent replacements or changes within the technical range disclosed by the present application, which are all encompassed within the protection scope of the present application.

Claims

1. A dilution device based on critical flow technology with continuously adjustable concentration, characterized in that, The sample gas critical flow path, the dilution gas critical flow path and the tank filling three-way assembly are composed of; The sample gas critical flow path comprises a sample gas pneumatic pressure regulating valve, a sample gas inlet pressure sensor, a sample gas critical flow path group and a multi-position selector valve connected in sequence through a gas conveying pipe. The dilution gas critical flow path comprises a dilution gas pressure regulating valve, a dilution gas inlet pressure sensor and a dilution gas critical flow path connected in sequence through a gas conveying pipe. The sample gas critical flow path and the dilution gas critical flow path are connected with the gas inlet of the tank filling three-way assembly, and the tank filling three-way assembly mixes the sample gas and the dilution gas and fills the tank. The sample gas pneumatic pressure regulating valve is composed of a spring, a diaphragm, a control gas cavity, a controlled gas cavity, a two-position three-way electromagnetic valve, a control gas inlet, a control gas outlet, a controlled gas inlet, a controlled gas outlet, a movable valve core plug and a silanized stainless steel valve body. The diaphragm divides the cavity wrapped by the silanized stainless steel valve body into an upper gas cavity and a lower gas cavity, the upper gas cavity is the control gas cavity, and the lower gas cavity is the controlled gas cavity; the control gas inlet and the control gas outlet are arranged on the upper part of the silanized stainless steel valve body, the control gas inlet is communicated with the control gas cavity, and the control gas outlet is communicated with the control gas cavity through the two-position three-way electromagnetic valve. The lower part of the silanized stainless steel valve body is provided with the controlled gas inlet and the controlled gas outlet, which are both communicated with the controlled gas cavity through channels; the controlled gas cavity is in the shape of a conical funnel, the movable valve core plug is vertically connected with the lower part of the diaphragm, the bottom of the movable valve core plug is connected with one end of the spring, the other end is connected with the inner wall of the bottom of the silanized stainless steel valve body, the movable valve core plug is in the same shape as the controlled gas cavity, and the movable valve core plug seals the controlled gas cavity and can move up and down in the controlled gas cavity.

2. The concentration continuously adjustable diluter based on the critical flow technique according to claim 1, characterized in that, A sealing gasket is further arranged on the side wall of the silanized stainless steel valve body at the funnel mouth of the controlled gas cavity.

3. The concentration continuously adjustable diluter based on the critical flow technique according to claim 1, characterized in that, The channels in the sample gas critical flow path group are connected in parallel, one end of each critical flow path is connected with the sample gas inlet pressure sensor, and the other end is respectively connected with different gas inlets of the multi-position selector valve.

4. The continuously adjustable concentration diluter based on critical flow technology according to claim 1, characterized in that, The tank filling three-way assembly is composed of a silanized stainless steel base, a tank filling pressure sensor, a stirring pipe, a combined three-way sample gas inlet, a combined three-way dilution gas inlet, a device gas outlet and a venting port, the silanized stainless steel base is in the shape of T, a pressure detection groove is arranged in the vertical section of the base, the combined three-way sample gas inlet, the combined three-way dilution gas inlet, the device gas outlet and the venting port are arranged on the horizontal section of the upper part of the silanized stainless steel base, and the detection end of the tank filling pressure sensor is embedded in the silanized stainless steel base and extends into the pressure detection groove; the stirring pipe is arranged in the horizontal section of the upper part of the silanized stainless steel base, the combined three-way sample gas inlet and the combined three-way dilution gas inlet are communicated with the gas inlet of the stirring pipe, and the device gas outlet and the venting port are communicated with the gas outlet of the stirring pipe and the pressure detection groove.

5. A continuously adjustable concentration diluter based on critical flow technology according to claim 4, characterized in that, The stirring pipe is a variable diameter pipe with gradually increasing diameter, a spiral winding pipe or a U-shaped pipe, which is made of a 1 / 8 inch diameter stainless steel pipe material treated by silanization.

6. The continuously adjustable concentration diluter based on critical flow technology according to claim 1, characterized in that, The diameter of the gas pipeline of the sample gas critical flow path and the dilution gas critical flow path is 1 / 4-1 / 16 inch stainless steel pipeline, which is treated by silanization.

7. The continuously adjustable concentration diluter based on critical flow technology according to claim 1, characterized in that, The flow range of the sample gas critical flow path group is 0-300 ml / min, and the flow range of the dilution gas critical flow path is 1000-5000 ml / min.

8. The continuously adjustable concentration diluter based on critical flow technology according to claim 1, characterized in that, The number of the gas inlet of the multi-position gating valve is 2-12.

9. The continuously adjustable concentration diluter based on critical flow technology according to claim 1, characterized in that, The range of the sample gas inlet pressure sensor and the dilution gas inlet pressure sensor is 0-1 Mpa, and the error is less than 0.1%; the internal control temperature of the concentration continuously adjustable device based on the critical flow technology is 20-60°C.

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