Gas-phase semi-volatile organic matter generating device, its assembling method and generating method

Abstract

Provided are a gas-phase semi-volatile organic compound generating device, an assembling method thereof, and a generating method thereof. The gas-phase semi-volatile organic compound generating device comprises a containing shell and an adsorption carrier. The containing shell is internally provided with a first passage. The adsorption carrier is internally provided with a second passage in a meandering shape, for adsorbing semi-volatile organic compounds and containing the semi-volatile organic compounds in the second passage. The adsorption carrier fills the interior of the shell body, and the path of the first passage passes through the second passage. Wherein, the carrier gas entering the first passage can flow through the second passage, so that the semi-volatile organic compounds leave the first passage in the form of gas phase with the carrier gas. In this way, the generating device can continuously and stably generate gas-phase semi-volatile organic compounds.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of testing, more particularly to a gas-phase semi-volatile organic compound generating device and an assembling method and a generating method thereof. BACKGROUND

[0002] Semi-volatile organic compounds (SVOCs) are substances with low boiling point, low saturated vapor pressure and strong adsorption. Phthalate acid esters (PAEs) are a typical SVOC, which can cause serious harm to the human body. In order to carry out mechanism research on the physical and chemical properties of PAEs, gas-phase PAEs need to be obtained as research objects.

[0003] The existing gas-phase generating device has problems of unstable generation and insufficient generation, so that the gas-phase generating device is difficult to generate continuously and stably. SUMMARY

[0004] The present application is made in view of the above state of the art. The purpose of the present application is to provide a gas-phase semi-volatile organic compound generating device and an assembling method and a generating method thereof, which can overcome at least one of the shortcomings described in the background art.

[0005] In order to achieve the above-mentioned purpose, the present application adopts the following technical solution.

[0006] The present application provides a gas-phase semi-volatile organic compound generating device, which comprises a containing shell, a first passage is arranged inside the shell body of the containing shell; and an adsorption carrier, a second passage with a tortuous shape is arranged inside the adsorption carrier, which is used for adsorbing semi-volatile organic compounds and containing the semi-volatile organic compounds in the second passage, the adsorption carrier fills the inside of the shell body, and the path of the first passage passes through the second passage, wherein the carrier gas entering the first passage can flow through the second passage, so that the semi-volatile organic compounds leave the first passage in the form of gas phase with the carrier gas.

[0007] In an optional solution, the adsorption carrier is activated carbon filter cotton, which comprises a substrate made of polyurethane foam and activated carbon coated on the inner surface of the substrate, the porous structure of the polyurethane foam forms the second passage, and the activated carbon is used for adsorbing the semi-volatile organic compounds.

[0008] In an optional solution, the shell body has a cylindrical structure, the hollow area of the shell body forms the first passage, and the adsorption carrier has a columnar structure corresponding to the shell body, and the adsorption carrier fills the hollow area of the shell body.

[0009] In an alternative, the housing further comprises a housing cover, the housing cover covers both ends of the housing body, and a central portion of the housing cover is provided with a cylindrical communication portion, the communication portion extends along the axial direction of the housing body and communicates the inside of the housing body with the outside of the housing body.

[0010] In an alternative, at least a portion of the housing cover is formed in a shape tapering from the housing body towards the communication portion.

[0011] In an alternative, the ratio of the specific surface area of the adsorption carrier to the porosity of the adsorption carrier satisfies the following mass transfer equation:

[0012]

[0013] wherein the central axis of the adsorption carrier is the x-axis, the flow direction of the carrier gas along the first passage is the positive direction of the x-axis, the carrier gas flows from one side end surface of the adsorption carrier to the other side end surface, the intersection of the one side end surface and the central axis is the zero point of the x-axis, t is time, u is the flow velocity of the carrier gas in the positive direction of the x-axis, C air is the mass concentration of the semi-volatile organic compound in the gas inside the second passage, C sur is the mass concentration of the semi-volatile organic compound on the inner surface of the adsorption carrier, h m is the convective mass transfer coefficient of the semi-volatile organic compound, a f is the specific surface area of the adsorption carrier, and ε is the porosity of the adsorption carrier.

[0014] In an alternative, the generating device further comprises a temperature control box, the temperature control box comprises a heating element, a temperature sensor and a controller, the temperature control box can accommodate a heat transfer medium, the housing body is installed in the temperature control box and can be in contact with the heat transfer medium, and the controller is connected with the heating element and the temperature sensor.

[0015] In an alternative, the temperature control box further comprises a box body, a box cover and an insulation layer, the box body has a cylindrical structure, the box cover covers both ends of the box body, the housing body and the heat transfer medium are located in the hollow region of the box body, and the insulation layer covers the box body and / or the box cover.

[0016] The application further provides an assembly method of a gas-phase semi-volatile organic compound generating device, which comprises the following steps: immersing the adsorption carrier in the semi-volatile organic compound so that the adsorption carrier adsorbs the semi-volatile organic compound and the semi-volatile organic compound is contained in the second passage; taking out the adsorption carrier after adsorbing the semi-volatile organic compound and placing it for a predetermined time; and filling the adsorption carrier in the housing body.

[0017] The application also provides a generation method of the gas-phase semi-volatile organic matter generation device, which comprises the following steps: introducing the carrier gas into the first passage; sampling the carrier gas discharged from the first passage, calculating the generation concentration of the gas-phase semi-volatile organic matter relative to the carrier gas to determine the stability of the generation concentration; and introducing the carrier gas into the downstream pipeline after the generation concentration is stable.

[0018] By adopting the technical scheme, the adsorption carrier can adsorb the semi-volatile organic matter and contain the semi-volatile organic matter in the tortuous second passage, the second passage can sufficiently disturb the carrier gas and increase the contact area between the adsorption carrier and the carrier gas, and the mass transfer process is strengthened. The generation device can continuously and stably generate the gas-phase semi-volatile organic matter. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 A perspective view of a gas-phase semi-volatile organic matter generation device according to an embodiment of the application is shown.

[0020] Figure 2 A perspective view of a partial structure of the gas-phase semi-volatile organic matter generation device in Figure 1 is shown, in which part of the thermal insulation cotton is omitted.

[0021] Figure 3 An exploded view of the containing shell and the temperature control box in Figure 1 is shown.

[0022] Figure 4 A sectional view of the shell body and the shell cover and the path of the carrier gas in Figure 3 is shown.

[0023] REFERENCE SIGNS

[0024] 1 containing shell; 11 shell body; 11a first passage; 12 shell cover; 121 communication part;

[0025] 2 activated carbon filter cotton; 2a second passage;

[0026] 3 temperature control box; 31 box body; 32 box cover; 32a through hole; 33 electric heating belt; 34 temperature sensor; 35 display screen; 36 thermal insulation cotton;

[0027] 4 base. DETAILED DESCRIPTION

[0028] The exemplary embodiments of the application are described below with reference to the accompanying drawings. It should be understood that the specific description is only used to illustrate how to implement the application for those skilled in the art, and is not used to exhaust all possible ways of the application, nor to limit the scope of the application.

[0029] Figures 1 to 4A gas-phase semi-volatile organic compound generation device according to an embodiment of the present application is shown.

[0030] The gas-phase semi-volatile organic compound generation device includes a housing 1, an activated carbon filter cotton 2 (adsorption carrier), a temperature control box 3, and a base 4. The housing 1 includes a housing body 11 and a housing cover 12. The housing body 11 has a cylindrical structure with both ends open, and the hollow region of the housing body 11 forms a first passage 11a, and the housing cover 12 covers both ends of the housing body 11. The activated carbon filter cotton 2 includes a substrate made of polyurethane foam and activated carbon coated on the inner surface of the substrate, and the porous structure of the polyurethane foam forms a tortuous second passage 2a, and the activated carbon can adsorb phthalate (semi-volatile organic compound). The activated carbon filter cotton 2 has a columnar structure corresponding to the housing body 11, which is coaxially filled in the hollow region of the housing body 11. Specifically, the activated carbon filter cotton 2 has a porosity of 30 ppi, a diameter of 20 mm, and a length of 150 mm.

[0031] When the activated carbon filter cotton 2 adsorbs phthalate and nitrogen gas (carrier gas) is introduced into the first passage 11a from one end of the housing body 11, the nitrogen gas entering the first passage 11a can flow through the second passage 2a, and the nitrogen gas in the second passage 2a occurs convective mass transfer. Specifically, the mathematical description of the convective mass transfer process of nitrogen gas on the inner surface of the activated carbon filter cotton 2 can be written as:

[0032]

[0033]

[0034] wherein the central axis of the activated carbon filter cotton 2 is the x-axis, and the flow direction of the nitrogen gas along the first passage 11a is the positive direction of the x-axis. The nitrogen gas flows from one side end face to the other side end face of the activated carbon filter cotton 2, and the intersection of the side end face and the central axis is the zero point of the x-axis. t is time, unit is s; C air is the mass concentration of phthalate in the gas inside the second passage 2a, unit is μg / m 3 ; V air is the volume of the pore inside the activated carbon filter cotton 2, unit is m 3 ; is the evaporation amount of phthalate on the inner surface of the activated carbon filter cotton 2 in the infinitesimal volume, unit is μg / s; h m is the convective mass transfer coefficient of the activated carbon filter cotton 2; C sur is the mass concentration of phthalate on the inner surface of the activated carbon filter cotton 2, unit is μg / m 3 ; A in is the inner surface area of the activated carbon filter cotton 2, unit is m 2 . Two parameters characterizing the structure of porous materials are introduced, which can be written as:

[0035]

[0036]

[0037] wherein a f is the specific surface area of the activated carbon filter cotton 2, in m 2 / m 3 ; V tot is the total volume of the activated carbon filter cotton 2, in m 3 ; and ε is the porosity of the activated carbon filter cotton 2. By combining equations (1) to (4), the mass transfer equation is obtained:

[0038]

[0039] Through the above mass transfer equation, the user can reasonably set the ratio between the specific surface area and the porosity of the activated carbon filter cotton 2 according to the needs.

[0040] After the nitrogen gas flows through a certain length of the second passage 2a, the concentration of the gas-phase phthalate relative to the nitrogen gas reaches saturation. After the nitrogen gas continues to flow through the remaining length of the second passage 2a, the nitrogen gas carrying the saturated concentration of the gas-phase phthalate leaves the activated carbon filter cotton 2. In this way, the inner surface of the activated carbon filter cotton 2 is coated with activated carbon, so that the second passage 2a can adsorb phthalate. The tortuous second passage 2a can fully disturb the nitrogen gas and increase the contact area between the activated carbon filter cotton 2 and the nitrogen gas, strengthening the mass transfer process, so that the generation device can continuously and stably generate the gas-phase phthalate.

[0041] The temperature control box 3 includes a box body 31 and a box cover 32. The box body 31 has a cylindrical structure with both ends open, and its interior can accommodate heat-conducting oil (heat transfer medium). The box body 31 is capped with the box cover 32 at both ends, and the box cover 32 is provided with through holes 32a corresponding to the cross-sectional diameter of the shell body 11. The shell body 11 passes through the through holes 32a at both ends of the box body 31, so that the axial direction of the shell body 11 is parallel to the axial direction of the box body 31, and the two ends of the shell body 11 are substantially flush with the two ends of the box body 31. A sealing structure is provided in the gap between the outer peripheral surface of the shell body 11 and the through hole 32a to prevent the heat-conducting oil from leaking from the gap, and the outer peripheral surface of the shell body 11 can be completely immersed in the heat-conducting oil. The box cover 32 is provided with four groups of such through holes 32a, which are uniformly arranged along the circumference of the box body 31, and four shell bodies 11 are respectively installed in the four groups of through holes 32a. In this way, the temperature control box 3 is installed with multiple shell bodies 11, so that the generation device can simultaneously generate multiple paths of gas-phase phthalate, and the generation device has high generation efficiency and use flexibility.

[0042] The shell cover 12 is connected to the box cover 32 by bolts, and a sealing ring is arranged between the shell cover 12 and the box cover 32. When a pre-tightening force is applied to the bolts, the shell cover 12 abuts against the end surface of the shell body 11, so that the shell body 11 cannot move along the axial direction of the shell body 11. The shell cover 12 extrudes the sealing ring and is fixed to the box cover 32, preventing nitrogen and gas-phase phthalic acid ester from leaking from the gap between the box cover 32 and the shell cover 12. The central part of the shell cover 12 is provided with a cylindrical communication part 121 with an outer diameter of 6 mm, which extends along the axial direction of the shell body 11 and communicates the inside and outside of the shell body 11. The gas source and the downstream pipeline can be respectively connected to the communication parts 121 at both ends of the shell 1, so that nitrogen can enter the first passage 11a through the communication part 121 on one side of the shell body 11 and enter the downstream pipeline through the communication part 121 on the other side. Among them, a part of the shell cover 12 connected to the downstream pipeline is formed in a shape tapering from the shell body 11 towards the communication part 121, so that nitrogen can be smoothly discharged from the shell 1.

[0043] The temperature control box 3 is also provided with an electric heating belt 33 (heating element), a temperature sensor 34, a display screen 35, a programmable controller (controller) and thermal insulation cotton 36 (thermal insulation layer). Three electric heating belts 33 are arranged at intervals along the axial direction of the box body 31, and each electric heating belt 33 is wound around the outer circumferential surface of the temperature control box 3 along the circumferential direction of the box body 31, so that the electric heating belt 33 can heat the heat conducting oil in the temperature control box 3. Two temperature sensors 34 are respectively installed on the box covers 32 on both sides of the temperature control box 3, and the probes of the temperature sensors 34 penetrate through the box covers 32 and extend into the interior of the temperature control box 3, so that the temperature sensors 34 can directly measure the temperature of the heat conducting oil. The electric heating belt 33, the temperature sensor 34, the display screen 35 and the programmable controller are connected. The outer circumferential surface of the box body 31 is covered with thermal insulation cotton 36 with a thickness of 10 mm, and the electric heating belt 33 is located between the temperature control box 3 and the thermal insulation cotton 36, thereby improving the heating efficiency of the generating device.

[0044] When it is necessary to make the generating device generate at a specified temperature, the user can send instructions to the programmable controller through the display screen 35 and set the specified temperature, and the electric heating belt 33 heats the heat conducting oil according to the instructions of the programmable controller. The programmable controller adjusts the working state of the electric heating belt 33 according to the temperature information collected from the temperature sensor 34, realizing closed-loop control of the working temperature of the generating device. In this way, the generating device can work at a specified temperature and can ensure the constancy of the working temperature, and the generating device can stably generate gas-phase phthalic acid ester.

[0045] The temperature control box 3 is erected on the base 4, so that the axial direction of the box body 31 can be parallel to the horizontal plane. The programmable controller is arranged inside the base 4, and the display screen 35 is arranged on the outer surface of the base 4.

[0046] The assembly method of the above-mentioned gas-phase semi-volatile organic matter generating device will be described below.

[0047] Step 1: Soak activated carbon filter cotton 2 in phthalate pure liquid and stand for 10 to 20 hours to allow activated carbon to fully adsorb phthalate pure liquid.

[0048] Step 2: Take out activated carbon filter cotton 2 from phthalate pure liquid and place it in a sealed container with a lumpy metal mesh at the bottom and stand for 15 to 25 hours to drain the excess unstable phthalate liquid droplets inside the activated carbon filter cotton 2. The lumpy metal mesh prevents the activated carbon filter cotton 2 from coming into contact with the drained phthalate pure liquid, allowing the activated carbon filter cotton 2 to dry quickly.

[0049] Step 3: Take out activated carbon filter cotton 2 from the container and fill it into the shell body 11. At this time, the gas in the second passage 2a is a mixture of gas-phase phthalate and air.

[0050] Step 4: Install the shell body 11 in the temperature control box 3 and install the shell cover 12 at both ends of the shell body.

[0051] The above steps complete the assembly of the generation device, and the following describes the generation method of the above-mentioned gas-phase semi-volatile organic matter generation device.

[0052] Step 1: After filling the activated carbon filter filled with phthalate pure liquid into the shell body 11, connect the gas source and the downstream pipeline to the communication part 121 located at both sides of the shell body 11. A mass flow meter is provided between the gas source and the communication part 121, and the downstream pipeline is connected to the adsorption tube. The adsorption tube can be a Tenax-TA adsorption tube or a 2,6-p-phenyl diphenyl ether porous polymer-graphitized carbon black-X composite adsorption tube.

[0053] Step 2: Set the working temperature of the generation device to 25°C and preheat the generation device.

[0054] Step 3: After the working temperature reaches 25°C, pass nitrogen gas through the communication part 121 on one side of the shell body 11 into the first passage 11a at a flow rate of, for example, 100 mL / min, and the nitrogen gas carrying the gas-phase phthalate enters the adsorption tube through the communication part 121 on the other side.

[0055] Step 4: Use a gas chromatograph-mass spectrometer (GC-MS) to sample the gas in the adsorption tube multiple times within a certain time period to measure the concentration change of the gas-phase phthalate within a certain time period. According to the concentration change of the gas-phase phthalate, the stability of the generated concentration is determined.

[0056] Step 5: After the concentration of the gas-phase phthalate stabilizes, pass the nitrogen gas in the downstream pipeline into the experimental cabin to obtain a continuous and stable supply of gas-phase phthalate.

[0057] The present application has at least the following advantages.

[0058] (i) The adsorption carrier can adsorb semi-volatile organic matter and contain the semi-volatile organic matter in the tortuous second passage 2a, which can sufficiently disturb the carrier gas and increase the contact area between the adsorption carrier and the carrier gas, strengthening the mass transfer process. The generation device can continuously and stably generate gas-phase semi-volatile organic matter.

[0059] (ii) The temperature control box 3 is provided with multiple shells 11, so that the generation device can simultaneously generate multiple channels of gas-phase semi-volatile organic matter, and has high generation efficiency and flexible use.

[0060] (iii) At least a part of the shell cover 12 is formed in a shape tapering from the shell 11 towards the communication part 121, so that the carrier gas can be smoothly discharged from the containing shell 1.

[0061] (iv) The temperature control box 3 is provided with heating equipment such as an electric heating belt 33, a temperature sensor 34, and a controller, so that the generation device can work at a specified temperature and ensure the constancy of the working temperature, and can stably generate gas-phase semi-volatile organic matter.

[0062] It should be understood that the above embodiments are only exemplary and are not intended to limit the present application. Those skilled in the art can make various modifications and changes to the above embodiments under the teaching of the present application without departing from the scope of the present application.

[0063] It should be understood that the present generation device is not limited to generating phthalate esters, and can be used to generate other kinds of semi-volatile organic matter, and can also be used to generate other kinds of substances other than semi-volatile organic matter. The carrier gas is not limited to nitrogen, and can also be hydrogen, helium, argon, carbon dioxide, or air.

[0064] It should be understood that the adsorption carrier is not limited to activated carbon filter cotton 2, and can be any carrier with a containing function and a tortuous second passage 2a. The base body of the activated carbon filter cotton 2 is not limited to being made of polyurethane foam, and can be made of any possible material. The activated carbon filter cotton 2 is not limited to a columnar structure, and can be a cuboid or an irregular shape. The pore density of the activated carbon filter cotton 2 is not limited to 30 ppi, and can be 15 ppi to 60 ppi.

[0065] It should be understood that the generating device is not limited to generating at high temperature, it can also include a cooling element so that the generating device is able to generate at low temperature. The working temperature of the generating device is not limited to 25℃, the working temperature of the generating device can be any possible temperature that the heating element and the cooling element can reach. The heating element is not limited to be an electric heating band 33, it can also be an electric heating tube. When the heating element is an electric heating tube, the electric heating tube can be arranged inside the temperature control box 3 and in contact with the heat conducting oil, so that the electric heating tube is able to directly heat the heat conducting oil. The heat conducting medium is not limited to be heat conducting oil, it can also be water. The temperature sensor 34 is not limited to directly measure the temperature of the heat conducting medium, it can measure the temperature of the outer surface of the temperature control box 3. The heat preservation layer is not limited to be made of heat preservation cotton 36, it can be made of any possible heat preservation material. The controller is not limited to be a programmable controller, it can also be a micro control unit (MCU).

[0066] It should be understood that the time length of each step of the assembling method of the generating device can be changed. For example, when the volume of the activated carbon filter cotton 2 used is small, the time length of step 1 and step 2 in the assembling method can be reduced accordingly. Conversely, when the volume of the activated carbon filter cotton 2 used is large, the time length can be increased accordingly.

[0067] It should be understood that in step 3 of the generating method of the generating device, the flow rate of nitrogen is not limited to be 100 mL / min. The user can adjust the flow rate of nitrogen according to the use requirement. In step 4 and step 5 of the generating method of the generating device, the judgment method and the judgment standard of the stability of the generated concentration are variable. The user can adopt a suitable judgment method and make a suitable judgment standard according to the use requirement.

Claims

1. A gas-phase semi-volatile organic compound generator, characterized in that, include: The housing (1) has a first passage (11a) inside its shell (11). as well as An adsorbent carrier has a tortuous second passage (2a) inside, used to adsorb semi-volatile organic compounds and contain them within the second passage (2a). The adsorbent carrier fills the interior of the shell (11), and the path of the first passage (11a) passes through the second passage (2a). The adsorbent carrier is activated carbon filter cotton (2), which includes a matrix made of polyurethane foam and activated carbon coated on the inner surface of the matrix. The porous structure of the polyurethane foam forms the second passage (2a). The activated carbon is used to immerse itself in the semi-volatile organic compounds to adsorb them. The carrier gas entering the first passage (11a) can flow through the second passage (2a) so that the semi-volatile organic compounds leave the first passage (11a) in the form of gas along with the carrier gas. The ratio of the specific surface area to the porosity of the adsorbent carrier satisfies the following mass transfer equation: Wherein, the central axis of the adsorbent carrier is taken as the x-axis, the flow direction of the carrier gas along the first passage (11a) is the positive direction of the x-axis, the carrier gas flows from one end face of the adsorbent carrier to the other end face, the intersection of the one end face and the central axis is the zero point of the x-axis, t is time, u is the flow velocity of the carrier gas in the positive direction of the x-axis, and C air C represents the mass concentration of the semi-volatile organic compound in the gas inside the second passage (2a). sur h represents the mass concentration of the semi-volatile organic compounds on the inner surface of the adsorbent carrier. m Let a be the convective mass transfer coefficient of the semi-volatile organic compound. f ε represents the specific surface area of ​​the adsorbent carrier, and ε represents the porosity of the adsorbent carrier.

2. The gas-phase semi-volatile organic compound generator according to claim 1, characterized in that, The shell (11) has a cylindrical structure, and the hollow area of ​​the shell (11) forms the first passage (11a). The adsorbent carrier has a columnar structure corresponding to the shell (11), and the adsorbent carrier fills the hollow area of ​​the shell (11).

3. The gas-phase semi-volatile organic compound generator according to claim 2, characterized in that, The housing (1) further includes a cover (12), which covers both ends of the housing body (11). The central part of the cover (12) is provided with a cylindrical connecting part (121), which extends along the axial direction of the housing body (11) and connects the interior of the housing body (11) and the exterior of the housing body (11).

4. The gas-phase semi-volatile organic compound generator according to claim 3, characterized in that, At least a portion of the cover (12) is formed in a shape that tapers from the body (11) toward the connecting portion (121).

5. The gas-phase semi-volatile organic compound generating apparatus according to any one of claims 1 to 4, characterized in that, The generating device also includes a temperature control box (3), which includes a heating element, a temperature sensor (34) and a controller. The temperature control box (3) can contain a heat transfer medium. The shell (11) is installed in the temperature control box (3) and can contact the heat transfer medium. The controller is connected to the heating element and the temperature sensor (34).

6. The gas-phase semi-volatile organic compound generator according to claim 5, characterized in that, The temperature control box (3) also includes a box body (31), a box cover (32) and an insulation layer. The box body (31) has a cylindrical structure. The box cover (32) covers both ends of the box body (31). The shell (11) and the heat transfer medium are located in the hollow area of ​​the box body (31). The insulation layer covers the box body (31) and / or the box cover (32).

7. A method for assembling a gas-phase semi-volatile organic compound generating device according to any one of claims 1 to 6, characterized in that, include: The adsorbent carrier is immersed in the semi-volatile organic compound, so that the adsorbent carrier adsorbs the semi-volatile organic compound, and the semi-volatile organic compound is contained in the second passage (2a); Remove the adsorbent carrier after it has adsorbed the semi-volatile organic compounds and let it stand for a predetermined time; The adsorbent carrier is filled into the shell (11).

8. A method for generating gaseous semi-volatile organic compounds using an apparatus according to any one of claims 1 to 6, characterized in that, include: The carrier gas is introduced into the first passage (11a); The carrier gas discharged from the first passage (11a) is sampled, and the concentration of gaseous semi-volatile organic compounds relative to the carrier gas is calculated to determine the stability of the concentration. Once the concentration has stabilized, the carrier gas is introduced into the downstream pipeline.

Images