CN107486046B - High-concentration organic matter standard mixed gas generating device and application method thereof - Google Patents
High-concentration organic matter standard mixed gas generating device and application method thereof Download PDFInfo
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
- B01F23/70—Pre-treatment of the materials to be mixed
- B01F23/706—Evaporating solvents or dispersion liquids, e.g. water, at least partially
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
- B01F23/10—Mixing gases with gases
- B01F23/12—Mixing gases with gases with vaporisation of a liquid
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
- B01F23/10—Mixing gases with gases
- B01F23/19—Mixing systems, i.e. flow charts or diagrams; Arrangements, e.g. comprising controlling means
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F35/00—Accessories for mixers; Auxiliary operations or auxiliary devices; Parts or details of general application
- B01F35/71—Feed mechanisms
- B01F35/711—Feed mechanisms for feeding a mixture of components, i.e. solids in liquid, solids in a gas stream
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F35/00—Accessories for mixers; Auxiliary operations or auxiliary devices; Parts or details of general application
- B01F35/71—Feed mechanisms
- B01F35/712—Feed mechanisms for feeding fluids
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F35/00—Accessories for mixers; Auxiliary operations or auxiliary devices; Parts or details of general application
- B01F35/80—Forming a predetermined ratio of the substances to be mixed
- B01F35/88—Forming a predetermined ratio of the substances to be mixed by feeding the materials batchwise
- B01F35/883—Forming a predetermined ratio of the substances to be mixed by feeding the materials batchwise using flow rate controls for feeding the substances
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/0004—Gaseous mixtures, e.g. polluted air
- G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
- G01N33/007—Arrangements to check the analyser
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D27/00—Simultaneous control of variables covered by two or more of main groups G05D1/00 - G05D25/00
- G05D27/02—Simultaneous control of variables covered by two or more of main groups G05D1/00 - G05D25/00 characterised by the use of electric means
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F2101/00—Mixing characterised by the nature of the mixed materials or by the application field
- B01F2101/23—Mixing of laboratory samples e.g. in preparation of analysing or testing properties of materials
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/0004—Gaseous mixtures, e.g. polluted air
- G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
- G01N33/007—Arrangements to check the analyser
- G01N2033/0072—Arrangements to check the analyser by generating a test gas
Abstract
The invention provides a high-concentration organic matter standard mixed gas generating device which comprises a high-pressure gas source, a mass flow controller, a precise injection pump, an airtight type injector with a needle, a liquid volatilizer, a constant temperature box and a gas mixer, wherein the liquid volatilizer is a three-way pipe arranged in the constant temperature box, three pipe orifices of the three-way pipe are respectively a first pipe orifice, a second pipe orifice and a third pipe orifice, the first pipe orifice is connected in series with the mass flow controller and communicated with the high-pressure gas source, the second pipe orifice is communicated with the needle of the airtight type injector, the third pipe orifice is communicated with an inlet of the gas mixer, an outlet of the gas mixer is communicated with a first flow path and a second flow path, the first flow path is used for being communicated with an instrument to be detected, the second flow path is used as an emptying port, the first flow path is provided with a first valve, the second flow path is provided with a second valve, and a piston of the airtight type injector is connected with the precise injection pump. And also relates to a use method. The method provides a metering standard with accurate magnitude and convenient use for the organic gas explosion early warning alarm.
Description
Technical Field
The invention relates to the technical field of standard mixed gas preparation, in particular to a high-concentration organic matter standard mixed gas generating device and a using method thereof.
Background
Gas component analysis is widely used in the fields of industrial production, atmospheric environment monitoring and the like. To ensure the reliability of the measurement results, standard mixed gas with known concentration is usually required to calibrate the indication of the analytical instrument. The standard mixed gas is prepared mainly by a permeation tube/diffusion tube method and a weighing method.
The common practice of the weighing method for preparing the standard mixed gas is to fill different kinds of raw material gases with determined mass into a gas cylinder through a gas distribution device, and mix the different kinds of gases in the gas cylinder to obtain the standard mixed gas with target concentration. The method is generally used for preparing raw materials at normal temperatureThe standard mixed gas of gaseous substances is pressed down, and the obtained mixed gas has higher pressure, usually about 10MPa, so as to be convenient to use. For raw materials which are liquid at normal temperature and pressure, such as ethanol, acetone, etc., only low concentration (10 -6 A mol/mol concentration level) can realize higher gas pressure and is convenient to use. If a high concentration (10) -2 The mol/mol concentration level), the gas pressure in the gas cylinder is too low, and the use value is lost.
The permeation tube/diffusion tube method is to put the raw materials into the permeation tube/diffusion tube, carry out the raw materials permeated or diffused from the permeation tube/diffusion tube by carrier gas with a certain flow rate, and form mixed gas. The method is also mainly used for preparing low-concentration standard mixed gas, and high-concentration standard gas cannot be prepared due to low permeation or diffusion rate.
However, in industrial production, a gas alarm for low explosion limit warning is often encountered. The alarm is installed in a factory building and is used for early warning the concentration of combustible and explosive gases in the factory building space. When the early warning value is reached, the instrument gives out a warning to protect the production safety and the safety of staff. According to the rule of metering method in China, the equipment belongs to a metering device for manufacturing, the accuracy of the metering device needs to be metered or calibrated, and standard mixed gas is needed to be used in the calibration process. A significant part of these gas alarms are directed to organic components that are liquid at normal temperature and pressure, since high concentrations of organic vapors are an important safety hazard.
The metering verification or calibration of the gas alarm of the organic component requires high-concentration organic standard mixed gas, but the conventional weighing method and the permeation tube/diffusion tube method can not obtain convenient and practical high-concentration mixed gas. No special mixed gas generating system is reported at home and abroad.
Disclosure of Invention
In view of the current state of the art, the invention aims to provide a high-concentration organic matter standard mixed gas generating device and a using method thereof, which provide a metering standard with accurate magnitude and convenient use for an organic gas explosion early warning alarm, solve the problem of preparing the high-concentration organic matter standard mixed gas which cannot be solved by the conventional weighing method gas cylinder standard gas and permeation tube and diffusion tube dynamic generation technology, and fill the technical defects of the conventional common weighing method and permeation tube/diffusion tube method. In order to achieve the above purpose, the technical scheme of the invention is as follows:
the utility model provides a standard mixed gas generating device of high concentration organic matter, includes high-pressure air supply, mass flow controller, accurate syringe pump, takes airtight type syringe, liquid volatilizer, incubator and gas mixer of syringe needle, liquid volatilizer is for arranging three-way pipe in the incubator, three mouth of pipe of three-way pipe is first mouth of pipe, second mouth of pipe and third mouth of pipe respectively, first mouth of pipe establish ties mass flow controller intercommunication extremely the high-pressure air supply, the second mouth of pipe intercommunication the syringe needle of airtight type syringe, the third mouth of pipe intercommunication extremely the entry of gas mixer, the export intercommunication of gas mixer has first flow path and second flow path, first flow path is used for being linked together with the instrument that waits to detect, the second flow path is used as the evacuation mouth, be provided with first valve on the first flow path, the second valve is provided with on the flow path, the piston of airtight type syringe is connected accurate syringe pump.
Preferably, the high-concentration organic matter standard mixed gas generating device further comprises a gas pressure regulating valve, and the gas pressure regulating valve is arranged between the high-pressure gas source and the mass flow controller in series.
Preferably, the first orifice communicates with the mass flow controller via a gas line, the gas line being a 1/8 inch gas line.
Preferably, the first valve and the second valve are needle valves.
Preferably, a spacer is used to seal the needle of the airtight syringe and the liquid volatilizer.
Preferably, the high-pressure gas source adopts a high-pressure gas cylinder, and the carrier gas of the high-pressure gas cylinder is high-purity nitrogen or high-purity synthetic air.
Preferably, the high-concentration organic matter standard mixed gas generating device further comprises a temperature controller and a computer containing control software, the incubator is electrically connected with the temperature controller through a first data line, the temperature controller is electrically connected with the computer containing control software through a second data line, the computer containing control software can control the temperature of the incubator through the temperature controller, the precise injection pump is electrically connected with the computer containing control software through a third data line, and the mass flow controller is electrically connected with the computer containing control software through a fourth data line.
The application method of the high-concentration organic matter standard mixed gas generating device comprises the following steps of:
step 1: sucking a certain amount of organic reagent by using an airtight syringe;
step 2: the airtight type injector is arranged on the precise injection pump, the piston of the precise injection pump is tightly contacted with the push rod of the airtight type injector, and after the airtight type injector is arranged, the tip of the needle of the airtight type injector is inserted into the middle part of the three-way liquid volatilizer so as to ensure that the organic reagent is fully volatilized and taken away by carrier gas; the connection part of the needle head and the liquid volatilizer is sealed by a spacer, so that the connection part is sealed and airtight;
step 3: the temperature of the temperature controller and the injection speed V of the airtight type injector are respectively preset by a computer containing control software 1 Carrier gas flow V of mass flow controller 2 ；
Step 4: calculating the quantity n=PV of the substance flowing out of the carrier gas by the mass flow controller in unit time according to the gas temperature T, the pressure P and the ideal state equation during the gas flow measurement 2 R is a gas constant; the carrier gas flowing out of the mass flow controller and the gas formed by volatilizing the organic reagent are primarily mixed in the liquid volatilizer and then enter the gas mixer together, and are fully mixed to form standard mixed gas with uniform concentration;
step 5: adjusting the first valve and/or the second valve to enable the gas flow of the standard mixed gas flowing out of the first flow path to meet the requirement of an instrument to be detected;
step 6: and (3) calibrating or calibrating the instrument to be detected by using the standard mixed gas flowing out of the first flow path.
Preferably, step 3 further comprises the steps of:
step 3.1, calculating the actual concentration C of the standard mixed gas
The actual concentration C of the standard mixed gas obtained per unit time is:
step 3.2, determining the target concentration of the mixed gas according to the physicochemical parameters of the organic reagent, wherein the target concentration is as follows:
calculating the injection speed V of the airtight syringe according to the formula (1) 1 And flow V of the mass flow controller 2 Is a flow ratio of (1);
i.e.
Where M is the molar mass of the organic reagent, p is the mass purity of the substance of the organic reagent, ρ is the density of the organic reagent.
Preferably, the method for using the high-concentration organic matter standard mixed gas generating device further includes a step of calculating a standard uncertainty u (C) of the standard gas concentration, the standard uncertainty u (C) of the standard gas concentration being calculated using the following formula:
wherein: u (V) 1 )、u(ρ)、u(p)、u(M)、u(V 2 ) U (P), u (R) and u (T) are each V 1 、ρ、p、M、V 2 Standard uncertainty of, P, R and T, and:
the beneficial effects of the invention are as follows:
the high-concentration organic matter standard mixed gas generating device and the use method thereof are used for producing high-concentration organic matter standard mixed gas, the injection speed of liquid is controlled by a precise injection pump, the flow rate of carrier gas is controlled by a mass flow controller, the liquid with stable flow rate is mixed with gas, the liquid is heated and gasified, and the high-concentration standard mixed gas with target concentration is obtained through uniformly mixing, so that a metering standard with accurate magnitude and convenient use is provided for an organic gas explosion early warning alarm, the problem of preparation of the high-concentration organic matter standard mixed gas which cannot be solved by the conventional weighing method gas cylinder standard gas and permeation tube and diffusion tube dynamic generation technology is solved, and the technical defects of the conventional weighing method and the conventional permeation tube/diffusion tube method are overcome.
Through the computer that contains control software, not only can carry out the settlement of relevant parameter, can gather the data of flow moreover, combines the physicochemical parameter of input simultaneously, and this standard mixed gas generator system can carry out concentration magnitude and uncertainty's calculation voluntarily, also can design injection rate and the gas velocity of liquid according to target concentration, just so can make things convenient for the use of device greatly, the operation of being convenient for has promoted the accuracy, has also improved work efficiency. The designed computer software control system can accurately control the flow rate and stabilize, and is convenient for adjusting the parameters, so that the system is simpler and more convenient to operate.
The invention also provides a concentration calculation formula of the standard mixed gas and a concentration uncertainty calculation formula obtained by the method, and also provides a control formula for calculating the flow rates of the injected liquid and the carrier gas according to the concentration target, so that the concentration magnitude and the uncertainty calculation of the concentration magnitude are more reliable and more accurate.
Drawings
FIG. 1 is a schematic diagram of a high concentration organic standard mixed gas generator according to an embodiment of the present invention; reference numerals illustrate:
1. a high pressure air source; 2. a gas pressure regulating valve; 3. a mass flow controller; 4. a precision syringe pump;
5. a gas line; 6. an airtight syringe; 7. a liquid volatilizer; 8. a constant temperature box;
9. a gas mixer; 10. a first valve; 11. an evacuation port; 12. a standard mixed gas outlet;
13. a temperature controller; 14. a first data line; 15. a second data line; 16. a third data line;
17. a fourth data line; 18. a computer containing control software; 19. and a second valve.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the following describes the high concentration organic matter standard mixed gas generating device and the method for using the same in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Referring to fig. 1, the high concentration organic standard mixed gas generating device according to an embodiment of the present invention includes a high pressure gas source 1, a mass flow controller 3, a precision syringe pump 4, a needle airtight syringe 6, a liquid volatilizer 7, a constant temperature box 8, and a gas mixer 9.
The liquid volatilizer 7 is a three-way pipe arranged in the constant temperature box 8, and three pipe orifices of the three-way pipe are a first pipe orifice, a second pipe orifice and a third pipe orifice respectively. The first orifice is connected in series with the mass flow controller 3 and is connected to the high pressure gas source 1, the second orifice is connected to the needle of the airtight syringe 6, and the third orifice is connected to the inlet of the gas mixer 9. The outlet of the gas mixer 9 communicates with a first flow path and a second flow path.
The first flow path is used for communication with the instrument to be tested, the standard mixture outlet 12 of the first flow path in fig. 1 is used for communication with the instrument to be tested, and the second flow path is used as the evacuation port 11. The first flow path is provided with a first valve 10, the second flow path is provided with a second valve 19, and the piston of the airtight syringe 6 is connected with the precision syringe pump 4. The high-pressure gas source 1 can adopt a high-pressure gas cylinder, and the carrier gas of the high-pressure gas cylinder is high-purity nitrogen or high-purity synthetic air.
Preferably, a gas pressure regulating valve 2 is also provided in series between the high pressure gas source 1 and the mass flow controller 3. A dry filter can be arranged in series between the high-pressure air source 1 and the air pressure regulating valve 2. The first orifice may be in communication with the mass flow controller 3 via a gas line 5, preferably a 1/8 inch gas line 5. The first valve 10 and the second valve 19 may each employ a needle valve. In other embodiments, electronic valves may be used for the first valve 10 and the second valve 19.
The space between the needle of the airtight syringe 6 and the liquid volatilizer 7 is also sealed by a spacer. The connection part of the needle head and the liquid volatilizer 7 is sealed by a spacer, so that the connection part is sealed and airtight.
As a preferable embodiment, the high-concentration organic matter standard mixed gas generating device further comprises a temperature controller 13 and a computer 18 containing control software, the incubator 8 is electrically connected with the temperature controller 13 through a first data line 14, the temperature controller 13 is electrically connected with the computer 18 containing control software through a second data line 15, the computer 18 containing control software can control the temperature of the incubator 8 through the temperature controller 13, the precision injection pump 4 is electrically connected with the computer 18 containing control software through a third data line 16, and the mass flow controller 3 is electrically connected with the computer 18 containing control software through a fourth data line 17.
In this embodiment, the high-concentration organic standard mixed gas generating device mainly comprises three parts, namely a carrier gas source part, a mixed gas generating part and a control part. The carrier gas source part supplies carrier gas to the whole generating device, and comprises a high-pressure gas cylinder and a gas pressure regulating valve 2. The mixed gas generating part is used for generating standard mixed gas and comprises a gas mass flow controller 3, a precision injection pump 4, a needle airtight type injector 6, a liquid volatilizer 7, an incubator 8, a gas mixer 9, a needle valve and the like. The control part takes a computer 18 containing control software as a core, is respectively connected with the mass flow controller 3, the precise injection pump 4, the temperature controller 13 and the incubator 8 through data wires, collects working parameters of each part through the computer, and controls and adjusts the working state of each part so as to generate target mixed gas with accurate magnitude.
The method for using the high-concentration organic matter standard mixed gas generating device in the above embodiment comprises the following steps:
step 1: sucking a certain amount of organic reagent by using an airtight syringe 6;
step 2: the airtight type injector 6 is arranged on the precise injection pump 4, the piston of the precise injection pump 4 is closely contacted with the push rod of the airtight type injector 6, and after the airtight type injector 6 is arranged, the needle tip of the airtight type injector 6 is inserted into the middle part of the three-way liquid volatilizer 7 so as to ensure that the organic reagent is fully volatilized and taken away by carrier gas; the connection part of the needle head and the liquid volatilizer 7 is sealed by a spacer, so that the connection part is sealed and airtight;
step 3: the temperature of the temperature controller 13 and the injection speed V of the airtight syringe 6 are preset by a computer 18 containing control software 1 Carrier gas flow V of mass flow controller 3 2 ；
Step 4: calculating the amount n=pv of the substance of the carrier gas flowing out of the mass flow controller 3 per unit time based on the gas temperature T, the pressure P and the ideal state equation at the time of gas flow measurement 2 R is a gas constant; the carrier gas flowing out of the mass flow controller 3 is primarily mixed with the gas formed by volatilizing the organic reagent in the liquid volatilizer 7 through the gas pipeline 5, and then enters the gas mixer 9 together, and is fully mixed to form standard mixed gas with uniform concentration;
step 5: adjusting the first valve 10 and/or the second valve 19 to enable the gas flow of the standard mixed gas flowing out of the first flow path to meet the requirement of an instrument to be detected;
step 6: and (3) calibrating or calibrating the instrument to be detected by using the standard mixed gas flowing out of the first flow path.
9. The method of using a high concentration organic standard mixed gas generating device according to claim 8, wherein step 3 further comprises the steps of:
step 3.1, calculating the actual concentration C of the standard mixed gas;
the actual concentration C of the standard mixed gas obtained per unit time is:
step 3.2, determining the target concentration of the mixed gas according to the physicochemical parameters of the organic reagent, wherein the target concentration is as follows:
calculating the injection speed V of the airtight syringe (6) according to the formula (1) 1 And a flow V of the mass flow controller (3) 2 Is a flow ratio of (1);
i.e.
Where M is the molar mass of the organic reagent, p is the mass purity of the substance of the organic reagent, ρ is the density of the organic reagent.
As a preferable mode, the method for using the high-concentration organic matter standard mixed gas generating device further includes a step of calculating a standard uncertainty u (C) of the standard gas concentration, the standard uncertainty u (C) of the standard gas concentration being calculated using the following formula:
wherein: u (V) 1 )、u(ρ)、u(p)、u(M)、u(V 2 ) U (P), u (R) and u (T) are each V 1 、ρ、p、M、V 2 Standard uncertainty of, P, R and T, and:
in the actual operation, a certain amount of the organic pure reagent (assuming that the purity of the pure reagent substance is p (mol/mol) and the density is ρ (g/mL)) is first sucked by the airtight syringe 6. Then the airtight syringe is mounted on the precision syringe pump 4, the syringe is fixed, and the piston of the syringe pump is tightly contacted with the push rod of the syringe, so that the push rod of the syringe can be effectively pushed to move. The precision syringe pump may be a commercially available precision syringe pump, the speed of movement of the piston of which may be manually set by a computer 18 containing control software. If the advancing speed of the piston is set to V 1 (mL/min), the mass of the injected liquid per unit time is V 1 ρ (g/min). The corresponding amount of the substance of the liquid injected in unit time is V 1 ρ/M (mol/min), where M is the molar mass (g/mol) of the neat reagent. Based on the purity of the pure reagent, the amount of the main component substance, V, in the pure reagent injected in a unit time can be calculated 1 ρp/M(mol/min)。
After the syringe is installed, the tip of the needle of the syringe should be inserted into the middle part of the three-way-shaped liquid volatilizer 7 to ensure that the liquid organic reagent volatilizes sufficiently and is carried away by the carrier gas. The connection part of the needle head and the liquid volatilizer should adopt sealing means in the form of a spacer and the like to ensure that the connection part is sealed and airtight. The spacer may be an annular spacer which is sleeved outside the needle of the airtight syringe 6. The periphery of the liquid volatilizer is provided with an incubator 8 which is connected with a temperature controller 13 through a data line 14. The temperature controller can control the set temperature of the incubator to heat the liquid volatilizer so as to promote the liquid flowing out from the tip of the needle to be gasified rapidly. The temperature of the incubator can be set according to the boiling point of the liquid used.
The carrier gas is derived from a high-pressure gas source 1, can be high-purity nitrogen or high-purity synthetic air, and enters a mass flow controller 3 through a pressure stabilizing valve 2. The carrier gas flow rate may be controlled and set by a mass flow meter, e.g. V 2 (m 3 /min，10 6 mL/min). Then according to the gas temperature T, pressure P and ideal state equation when the gas flow is measured, calculating the quantity of the substance flowing out of the carrier gas in unit time, namely PV 2 RT (R is a gas constant). The carrier gas is initially mixed with the gas formed by the volatilization of the liquid in the liquid volatilizer 7 through the gas pipeline 5 with the length of 1/8' inch, and then enters the gas mixer 9 together, and is fully mixed to form standard mixed gas with uniform concentration. The actual concentration C (mol/mol) of the standard gas mixture obtained is:
one path of the obtained standard mixed gas passes through the standard mixed gas outlet 12 and is connected with an instrument to be detected, so that the instrument can be subjected to related measurement work; the other path is discharged through the drain 11. In order to make the gas flow rate of the standard gas mixture outlet meet the requirements of the instrument to be tested, a first valve 10 of the standard gas mixture outlet and a second valve 19 of the evacuation port can be mechanically adjusted. Of course, the first valve 10 of the electronic standard mixture outlet and the second valve 19 of the evacuation port can also be used. When the first valve 10 is fully opened and the second valve 19 is closed, the flow of the emptying port is reduced, and the flow of the standard mixed gas outlet is increased; when the second valve 19 is fully opened and the first valve 10 is closed, the evacuation port flow increases and the standard mixing port flow decreases.
The flow rate of the mass flow controller 3, the injection speed of the precision injection pump and the temperature of the temperature controller are precisely controlled by a computer 18 containing control software. The mass flow controller 3 may also be replaced by a mass flow meter.
Of course, if the physicochemical parameters of a liquid reagent are known and the target concentration of the mixed gas is determined, the airtight injection with needle can be calculated according to the formula (1)Injection speed V of the device 6 1 And the flow V of the mass flow controller 3 2 Is provided.
I.e.
For example, acetone is liquid at normal temperature, but is extremely volatile, and the lower explosion limit is 2.5% (V/V), namely, the lower explosion limit is reached by acetone in air with the mass concentration of 0.025mol/mol, and then explosion can occur if open fire is encountered. An acetone explosion limit alarm installed in an industrial place usually starts to alarm when the concentration of acetone reaches half of the explosion lower limit, so that the safety of the work place is ensured. I.e. when the concentration of acetone in the air reaches 0.0125mol/mol, the instrument gives an alarm. In order to verify the accuracy of the instrument alarm point, the instrument must be calibrated or calibrated using standard gas at that concentration value.
However, the acetone standard gas with the concentration of C=0.0125 mol/mol cannot be prepared into steel bottle gas by a weighing method or can not be prepared by a common diffusion tube or permeation tube method.
The invention can solve the preparation problem of the standard gas. Let the atmospheric pressure in the working environment be p=101325 Pa and the temperature t=298.15K (i.e. 25 ℃). The density of acetone at 25 ℃ is ρ=0.788 g/mL, the purity of the acetone reagent p=0.995 mol/mol, and the molecular weight of acetone m=58.08 g/mol. The gas constant r= 8.314J/(mol·k).
Can be obtained according to formula (2), under which condition V 1 /V 2 = 0.00003833. If the injection speed V of the airtight syringe 6 with needle is set 1 =0.1 mL/min. The flow V of the mass flow controller 3 is set 2 = 2608.9mL/min. Meanwhile, according to the property that the boiling point of acetone is 56 ℃ under normal pressure, the temperature of the incubator 8 is controlled to 60 ℃ by the temperature controller 13, so that the acetone liquid flowing out from the tip of the needle of the airtight syringe 6 can be completely gasified. Thus, the acetone standard gas with the concentration of 0.0125mol/mol can be obtained, and the requirement of the alarm point test of the alarm is met.
The calculation formula of the standard uncertainty u (C) of the standard gas concentration can be calculated according to the formula (1):
wherein: u (V) 1 )、u(ρ)、u(p)、u(M)、u(V 2 ) U (P), u (R) and u (T) are each V 1 、ρ、p、M、V 2 Standard uncertainty of P, R and T.
And:
the above concentration and standard uncertainty calculation formula for concentration,namely, the formula (1) and the formula (3), can be written into a computer 18 containing control software, and the parameters p, p, M, R, P, T and the collected parameters V are input 1 、V 2 The concentration value of the generated standard mixed gas and the standard uncertainty of the concentration value are automatically calculated by the computer 18 containing control software. Equation (2) can also be written into the computer 18 containing control software, and if the parameters ρ, p, M, R, P, T and the target mixed gas concentration C are known, the computer 18 containing control software can automatically calculate V 1 And V 2 Is a ratio of the magnitudes of (2). If one of the values is fixed again, the other value can also be calculated accurately by the computer 18 containing the control software.
Through the computer that contains control software, not only can control the setting value of relevant temperature and flow, can gather flow data moreover, combines the physicochemical parameter of input simultaneously, and this standard mixed gas generator system can carry out the calculation of relevant volume automatically, just so can make things convenient for the use of device greatly, has promoted the accuracy, has also improved work efficiency.
Through verification, the standard mixed gas generating device with the high-concentration organic matter standard and the using method thereof are adopted, the accuracy of the standard mixed gas prepared by the device is high, the calculation of the uncertainty of the concentration value and the concentration value is more reliable and accurate, and the working efficiency is higher.
The high-concentration organic matter standard mixed gas generating device and the using method thereof are used for producing high-concentration organic matter standard mixed gas, controlling the injection speed of liquid through a precise injection pump, controlling the flow rate of carrier gas through a mass flow controller, mixing liquid with stable flow rate with gas, heating to gasify the liquid, and uniformly mixing to obtain high-concentration standard mixed gas with target concentration, thereby providing a metering standard with accurate magnitude and convenient use for an organic gas explosion warning alarm, solving the preparation problem of high-concentration organic matter standard mixed gas which cannot be solved by the conventional weighing method gas cylinder standard gas and permeation tube and diffusion tube dynamic generation technology, and filling the technical defects of the weighing method and the permeation tube/diffusion tube method which are commonly used at present.
The designed computer software control system can accurately control the flow rate and stabilize, and is convenient for adjusting the parameters, so that the system is simpler and more convenient to operate. Through the computer that contains control software, not only can carry out the settlement of relevant parameter, can gather the data of flow moreover, combines the physicochemical parameter of input simultaneously, and this standard mixed gas generator system can carry out concentration magnitude and uncertainty's calculation voluntarily, also can design injection rate and the gas velocity of liquid according to target concentration, just so can make things convenient for the use of device greatly, the operation of being convenient for has promoted the accuracy, has also improved work efficiency.
The invention also provides a concentration calculation formula of the standard mixed gas and a concentration uncertainty calculation formula obtained by the method, and also provides a control formula for calculating the flow rates of the injected liquid and the carrier gas according to the concentration target, so that the concentration magnitude and the uncertainty calculation of the concentration magnitude are more reliable and more accurate.
It should be noted that the above embodiments and features in the embodiments may be combined with each other without conflict.
The foregoing examples illustrate only a few embodiments of the invention and are described in detail herein without thereby limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention.
Claims (9)
1. The utility model provides a standard mixed gas generating device of high concentration organic matter, its characterized in that includes high pressure gas supply (1), mass flow controller (3), precision injection pump (4), take airtight syringe (6) of syringe needle, liquid volatilizer (7), thermostated container (8), temperature controller (13) and gas mixer (9), liquid volatilizer (7) are for arranging in the three-way pipe in thermostated container (8), three mouth of pipe are first mouth of pipe, second mouth of pipe and third mouth of pipe respectively, first mouth of pipe is established ties mass flow controller (3) communicate to high pressure gas supply (1), first mouth of pipe communicates through gas line (5) mass flow controller (3), the second mouth of pipe communicates the syringe needle of airtight syringe (6), the syringe needle tip of airtight syringe (6) inserts the middle part of three-way molding liquid volatilizer (7), the third mouth of pipe communicates to gas mixer (9)'s entry, gas mixer (9) exit, second flow path (9) are connected with each other, second flow path (4) are equipped with the second flow path is used for detecting, the second flow path is equipped with precision flow path (4), the second flow path is equipped with piston (11) is equipped with and is used for waiting to empty the measuring instrument, the temperature controller (13) is used for setting the temperature of the incubator (8).
2. The high-concentration organic matter standard mixed gas generating device according to claim 1, further comprising a gas pressure regulating valve (2), the gas pressure regulating valve (2) being disposed in series between the high-pressure gas source (1) and the mass flow controller (3).
3. The high concentration organic standard mixed gas generating device according to claim 1, wherein the gas line (5) is a 1/8 inch gas line.
4. The high concentration organic matter standard mixed gas generating device according to claim 1, wherein the first valve (10) and the second valve (19) are needle valves.
5. The high-concentration organic matter standard mixed gas generating device according to claim 1, wherein a spacer seal is adopted between the needle of the airtight syringe (6) and the liquid volatilizer (7).
6. The high-concentration organic matter standard mixed gas generating device according to claim 1, wherein the high-pressure gas source (1) adopts a high-pressure gas cylinder, and the carrier gas of the high-pressure gas cylinder is high-purity nitrogen or high-purity synthetic air.
7. The high-concentration organic matter standard mixed gas generating device according to any one of claims 1 to 6, further comprising a computer (18) containing control software, wherein the incubator (8) is electrically connected to the temperature controller (13) through a first data line (14), the temperature controller (13) is electrically connected to the computer (18) containing control software through a second data line (15), the computer (18) containing control software is capable of controlling the temperature of the incubator (8) through the temperature controller (13), the precision syringe pump (4) is electrically connected to the computer (18) containing control software through a third data line (16), and the mass flow controller (3) is electrically connected to the computer (18) containing control software through a fourth data line (17).
8. A method of using the high concentration organic matter standard mixed gas generating device of claim 7, characterized in that the method comprises the steps of:
step 1: sucking a certain amount of organic reagent by using an airtight syringe (6);
step 2: the airtight type injector (6) is arranged on the precise injection pump (4), the piston of the precise injection pump (4) is closely contacted with the push rod of the airtight type injector (6), and after the airtight type injector (6) is arranged, the needle tip of the airtight type injector (6) is inserted into the middle part of the three-way liquid volatilizer (7) so as to ensure that the organic reagent is fully volatilized and taken away by carrier gas; the connection part of the needle head and the liquid volatilizer (7) is sealed by a spacer, so that the connection part is sealed and airtight;
step 3: the temperature of the temperature controller (13) and the injection speed V of the airtight type injector (6) are respectively preset by a computer (18) containing control software 1 Carrier gas flow V of mass flow controller (3) 2 The method comprises the steps of carrying out a first treatment on the surface of the The temperature controller (13) is used for setting the temperature of the incubator (8); step 4: based on gas flow measurementsThe gas temperature T, the pressure P and an ideal state equation, and the quantity n=PV of the substance flowing out of the carrier gas by the mass flow controller (3) in unit time is calculated 2 R is a gas constant; the carrier gas flowing out of the mass flow controller (3) and the gas formed by volatilizing the organic reagent are primarily mixed in the liquid volatilizer (7) and then enter the gas mixer (9) together, and are fully mixed to form standard mixed gas with uniform concentration;
step 5: adjusting the first valve (10) and/or the second valve (19) to enable the gas flow of the standard mixed gas flowing out of the first flow path to meet the requirement of an instrument to be detected;
step 6: calibrating or calibrating the instrument to be detected by using the standard mixed gas flowing out of the first flow path;
wherein, step 3 further comprises the following steps:
step 3.1, calculating the actual concentration C of the standard mixed gas
The actual concentration C of the standard mixed gas obtained per unit time is:
step 3.2, determining the target concentration of the mixed gas according to the physicochemical parameters of the organic reagent, wherein the target concentration is as follows:
calculating the injection speed V of the airtight syringe (6) according to the formula (1) 1 And a flow V of the mass flow controller (3) 2 Is a flow ratio of (1);
i.e.
Where M is the molar mass of the organic reagent, p is the mass purity of the substance of the organic reagent, ρ is the density of the organic reagent.
9. The method of using a high concentration organic matter standard mixed gas generating device according to claim 8, further comprising the step of calculating a standard uncertainty u (C) of the standard gas concentration, the standard uncertainty u (C) of the standard gas concentration being calculated using the following formula:
wherein: u (V) 1 )、u(ρ)、u(p)、u(M)、u(V 2 ) U (P), u (R) and u (T) are each V 1 、ρ、p、M、V 2 Standard uncertainty of, P, R and T, and:
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