In-situ, real-time, and continuous measurement device and method for volume changes in chemical reactions involving gases

Abstract

This invention belongs to the field of detection instrument technology, specifically disclosing a device and method for in-situ, real-time, and continuous measurement of volume changes in chemical reactions involving gases. The device includes at least two gas cylinders, a valve positioner, gas pipelines, and a true density meter. One gas cylinder contains the measuring gas, while the other cylinders contain the reaction gas. The true density meter is connected to each gas cylinder via gas pipelines. The valve positioner is located on the gas pipelines. The true density meter includes a sample chamber, an auxiliary chamber, a pressure sensor, a first valve, a second valve, and a third valve. The input end of the sample chamber is connected to the gas pipeline, and the auxiliary chamber is connected to the sample chamber. The first valve is installed at the input end of the sample chamber, the second valve is located between the sample chamber and the auxiliary chamber, and the pressure sensor is installed between the sample chamber and the second valve. Using this technical solution, the coordinated operation of these components enables in-situ, real-time, and continuous measurement of volume changes occurring in chemical reactions involving gases.

Description

Technical Field

[0001] This invention belongs to the field of detection instrument technology, and relates to a device and method for in-situ, real-time, and continuous measurement of volume changes in chemical reactions involving gases. Background Technology

[0002] True density analyzers can perform in-situ, non-destructive, continuous, and automated testing of the absolute volume of solid or slurry substances under normal temperature and pressure. Their accuracy has been widely recognized by scholars in various industries both domestically and internationally. In the field of building materials, true density analyzers can be used to monitor the absolute volume changes of cement paste in the early stages of cement hydration in real time. This provides feasibility for studying the influence and mechanism of admixtures on the cement hydration process and paste volume changes.

[0003] True density analyzers utilize Archimedes' principle (gas displacement method and Bohr's law (PV=nRT)) to accurately determine the volume of cement samples by measuring changes in pressure within the sample cell. The gas expansion displacement method in true density analyzers uses gas instead of liquid to determine the volume displaced from the sample. This method avoids measurement errors caused by sample dissolution in immersion methods and does not damage the sample. However, current true density analyzers on the market still have the following technical problems:

[0004] (1) To measure the volume change produced by the reaction of gas with solid or liquid, the main method is to subtract the volumes of reactants and products measured sequentially and separately. The measurement process requires stopping the reaction first, and then removing the reactants or products from the reaction system before measurement (stopping the reaction and removing the reaction system inevitably introduces impurities and increases errors, which are detrimental to the normal progress of the reaction). It is impossible to measure reactants and products in the reaction system in situ and continuously. At the same time, it is also impossible to measure reactants or products that are in the process of reaction in real time and continuously.

[0005] (2) Existing true density analyzers can measure the volume of the reaction system in the reaction chamber in situ, in real time, and continuously with high accuracy. However, this equipment requires all reactants to be placed in the reaction chamber and the chamber to be closed before measurement. It cannot measure reactions involving gases (firstly because gases do not have a fixed form, making experimental operation extremely difficult; secondly because if the reaction gas is injected into the sample chamber in advance and mixed with the reactants, the two will react before measurement, resulting in a large error. Moreover, the reaction gas injected in advance will create a negative pressure in the sample chamber after reaction, significantly affecting the basic premise of the true density analyzer to measure the sample volume, which is the change in measurement pressure; thirdly, the design of existing true density analyzers is basically complete, and the relevant modules do not have the functions of storing reaction gas before reaction, releasing gas during reaction, and removing impurities after reaction. Therefore, existing technology does not allow the reaction gas to be injected into the sample chamber in advance), especially when gas is added to participate in the reaction during the process. Summary of the Invention

[0006] The purpose of this invention is to provide an in-situ, real-time, and continuous measurement device and method for volume changes in chemical reactions involving gases, enabling in-situ, real-time, and continuous measurement of volume changes occurring in chemical reactions involving gases.

[0007] To achieve the above objectives, the basic solution of the present invention is: an in-situ, real-time, and continuous measurement device for volume changes in chemical reactions involving gases, comprising at least two gas cylinders, a valve positioner, a gas pipeline, and a true density meter.

[0008] One of the at least two gas cylinders contains a measuring gas, and the other gas cylinders contain a reaction gas.

[0009] The true density meter is connected to the gas cylinder via gas pipelines, and the valve positioner is installed on the gas pipelines.

[0010] The working principle and beneficial effects of this basic scheme are as follows: This technical scheme introduces the gas participating in the chemical reaction (i.e., the reactant gas) into the corresponding gas cylinder. The reactant gas will react chemically with the sample and form a parallel connection with the gas used to measure the volume of the substance (i.e., the measuring gas). Based on the characteristics of the reaction to be measured (such as reaction time), the reaction and measurement process is obtained. After the true density meter is calibrated and adjusted using a standard system and method composed of standard substances and standard gases, the measurement is performed, and finally the volume change of the reactants before and after the reaction with the gas is determined.

[0011] Furthermore, the true density meter includes a sample chamber for placing the reaction sample, an auxiliary chamber for balancing the pressure inside the sample chamber, a pressure sensor, a first valve, a second valve, and a third valve;

[0012] The input end of the sample chamber is connected to the gas pipeline, and the auxiliary chamber is connected to the sample chamber;

[0013] The first valve is installed at the input end of the sample chamber, the second valve is located between the sample chamber and the auxiliary chamber, the third valve is located at the output end of the auxiliary chamber, and the pressure sensor is installed between the sample chamber and the second valve.

[0014] The pressure inside the sample chamber is balanced by using an auxiliary chamber, a first valve, a second valve, and a third valve. The pressure signal of the sample chamber is then collected to facilitate subsequent volume determination.

[0015] Furthermore, the valve positioner is either a single-acting valve positioner or a double-acting valve positioner.

[0016] A single-acting valve positioner can control the on / off state of a single pipe, while a double-acting valve positioner can control the on / off state of two pipes simultaneously. Choosing the appropriate valve positioner according to your needs is beneficial for its use.

[0017] The present invention also provides a method for in-situ, real-time, and continuous measurement of volume changes in chemical reactions involving gases using the apparatus described herein, comprising the following steps:

[0018] S1, Place the sample into the sample chamber, open the gas cylinder, open the valve positioner of the gas pipeline connected to the gas cylinder containing the measuring gas, open the first valve, the second valve and the third valve, and let the measuring gas flow through the inside of the device as an environmental medium to remove the air from the sample chamber, the auxiliary chamber and the gas pipeline.

[0019] S2, close the second and third valves and open the first valve. When the pressure difference between the sample chamber and the external environment reaches the preset value, the first valve closes and the valve positioner of the gas pipeline connected to the gas cylinder containing the measured gas is closed.

[0020] Once the pressure inside the sample chamber stabilizes, the pressure P1 inside the sample chamber is measured.

[0021] Open the second valve to connect the sample chamber and the auxiliary chamber. When the pressure in the sample chamber and the auxiliary chamber stabilizes, measure the pressure P2 in the sample chamber and the auxiliary chamber. Then open the third valve and calculate the absolute volume of the sample at this time.

[0022] S3, open the valve positioner of the gas pipeline in the gas cylinder containing the reaction gas, open the first valve, the second valve and the third valve, and clear the measuring gas in the sample chamber, the auxiliary chamber and the gas pipeline; and the reaction gas enters the sample chamber and reacts chemically with the sample;

[0023] S4, close the second and third valves and open the first valve. When the pressure difference between the sample chamber and the external environment reaches the preset value, the first valve closes and the valve positioner of the gas pipeline of the gas cylinder containing the reaction gas is closed.

[0024] Once the pressure inside the sample chamber stabilizes, the pressure P3 inside the sample chamber is measured.

[0025] Open the second valve to connect the sample chamber and the auxiliary chamber. When the pressure in the sample chamber and the auxiliary chamber stabilizes, measure the pressure P4 in the sample chamber and the auxiliary chamber, and then open the third valve.

[0026] S5, open the valve positioner of the gas pipeline connected to the gas cylinder containing the measuring gas, and open the first valve, the second valve and the third valve;

[0027] S6, repeat steps S2-S5, and measure the final pressure P inside the sample chamber. N Calculate the absolute volume and volume change of the sample at this time.

[0028] This method allows for real-time and continuous measurement of the volume of reactants or products in a reaction without stopping the reaction or removing the reactants or products from the reaction system, thus increasing the accuracy of the data.

[0029] Furthermore, the absolute volume V of the sample is calculated. P The method is as follows:

[0030] ，

[0031] Among them, V C V is the volume of the sample chamber. A P1 is the volume of the auxiliary chamber, P2 is the pressure inside the sample chamber, and P2 is the pressure inside both the sample chamber and the auxiliary chamber.

[0032] It is simple to operate and easy to use.

[0033] Furthermore, the method for calculating the sample volume change is as follows:

[0034] Calibration and adjustment are required before reaction and measurement, with the sample chamber empty:

[0035] First measurement of gas: Ventilation time t2 min;

[0036] First reaction gas: Ventilation time t1 min;

[0037] Second gas flow measurement: Ventilation time t2 min;

[0038] Second reaction gas: Ventilation time t1 min;

[0039] And so on, to obtain the nth measurement of the gas and the reaction gas. for:

[0040] ,

[0041] Alternatively, the absolute volume of the gas measured in the nth pass is:

[0042] V p(2n-1) =Vc+V A / (1-P 4n-3 / P 4n-2 ),

[0043] The absolute volume of the gas in the nth reaction is:

[0044] V p(2n) =Vc+V A / (1-P 4n-1 / P 4n ),

[0045] Among them, V C V is the volume of the sample chamber. A P is the volume of the additional compartment. n P is the pressure inside the sample chamber. n+1 The pressure within the sample chamber and the auxiliary chamber;

[0046] If V p5 =V p3 V p6 =V p4 If the gas measured has completely purged the reactant gas, then it can be deduced that the gas measured has completely purged the reactant gas; otherwise, it indicates that the gas measured has not completely purged the reactant gas, and the time for the gas measured to purge the reactant gas in the experiment should be increased.

[0047] The absolute volume V of the sample is measured in the nth cycle. pn Subtract the absolute volume V of the sample measured for the first time p1 The volume change (V) before and after the reaction of the reactants with the gas was obtained. pn -V p1 ).

[0048] The calculation of sample volume change is simple and easy to use. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the structure of a single-acting valve positioner used in the present invention for in-situ, real-time, and continuous measurement of volume changes in chemical reactions involving gas.

[0050] Figure 2This is a schematic diagram of the structure of a double-acting valve positioner used in the present invention for in-situ, real-time, and continuous measurement of volume changes in chemical reactions involving gas.

[0051] Figure 3 This is a schematic diagram of the true density meter, which is a device for in-situ, real-time, and continuous measurement of volume changes in chemical reactions involving gases, according to the present invention.

[0052] The reference numerals in the accompanying drawings include: first gas cylinder 1, second gas cylinder 2, single-acting valve positioner 3, double-acting valve positioner 4, gas pipeline 5, true density meter 6, sample chamber 7, auxiliary chamber 8, pressure sensor 9, first valve 10, second valve 11, and third valve 12. Detailed Implementation

[0053] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0054] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0055] In the description of this invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to mechanical or electrical connections, or internal connections between two components. They can be direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0056] This invention discloses an in-situ, real-time, and continuous measurement device for volume changes in chemical reactions involving gases, such as... Figure 1 and Figure 2 As shown, it includes at least two gas cylinders, a valve positioner, a gas pipeline 5, and a true density meter 6.

[0057] At least one of the two gas cylinders (as shown in the attached diagram, cylinder 1) contains a measuring gas that will not react with the sample; helium is recommended. Helium is the preferred choice due to its small molecular weight, easy diffusion, stability as an inert gas, and the fact that its monatomic molecules are closer to an ideal gas. The remaining gas cylinders (as shown in the attached diagram, cylinder 2) contain a reactant gas that can chemically react with the reactants. Users can choose the reactant gas according to their needs; for example, carbon dioxide can be used to study the carbonization of Ca(OH)₂. The outlet pressure of cylinder 1 should be controlled at approximately 100–120 kPa, and the outlet pressure of cylinder 2 should be controlled below 1 MPa.

[0058] The true density meter 6 is connected to the gas cylinder via the gas pipeline 5, and the valve positioner is installed on the gas pipeline 5.

[0059] Preferred, such as Figure 1 As shown, the valve positioner uses a single-acting valve positioner 3, which controls the opening and closing of the gas pipeline 5. One single-acting valve positioner 3 can only control the inlet and outlet of one gas pipeline 5. Two single-acting valve positioners 3 are used to control the pipelines for the measuring gas from the first gas cylinder 1 and the reaction gas from the second gas cylinder 2, respectively. A controller can be installed on the single-acting valve positioner 3 to control the opening and closing of the two valves separately. The controller can be used via a mobile phone to time and precisely open / close the two valves. Additional reaction gases can be added as needed, such as adding one or more third or fourth gas cylinders, enabling the sample to react with multiple gases.

[0060] In another preferred embodiment, such as Figure 2 As shown, the valve positioner uses a double-acting valve positioner 4. The double-acting valve positioner 4 controls the opening and closing of the gas pipeline 5. It can simultaneously control the inlet and outlet of two gas pipelines 5, with gas entering at both ends and exiting at one end. Using the double-acting valve positioner 4 allows for centralized control of the pipelines where the gas measured by the first gas cylinder 1 reacts with the gas in the second gas cylinder 2. For example, the gas pipeline 5 of the first gas cylinder 1 can be open while the gas pipeline 5 of the second gas cylinder 2 can be closed; or the gas pipeline 5 of the first gas cylinder 1 can be closed while the gas pipeline 5 of the second gas cylinder 2 can be open; or both can be open and both closed. Using only one double-acting valve positioner 4 to control the valve's opening and closing improves efficiency, saves time, and reduces costs.

[0061] This technical solution introduces the gas involved in the chemical reaction (i.e., the reactant gas) into a corresponding gas cylinder. The reactant gas reacts chemically with the sample and forms a parallel connection with the gas used to measure the volume of the substance (i.e., the measuring gas). A reaction and measurement procedure is developed based on the characteristics of the reaction to be measured (such as reaction time). After calibrating and adjusting the procedure using a standard system and method composed of standard substances and standard gases, detection is performed, ultimately determining the volume change of the reactants before and after the reaction with the gas.

[0062] The True Density Analyzer 6 provides real-time, continuous measurement of the volume of reactants or products in a reaction process, without requiring the reaction to be stopped or the reactants or products to be removed from the reaction system, thus increasing data accuracy. The modified True Density Analyzer 6 can freely accommodate desired reaction gases and can measure the volume of the reaction system within the reaction chamber in situ, in real-time, and continuously, significantly improving measurement efficiency.

[0063] In a preferred embodiment of the present invention, such as Figure 3 As shown, the true density meter 6 includes a sample chamber 7 for holding the reaction sample, an auxiliary chamber 8 for balancing the pressure inside the sample chamber 7, a pressure sensor 9, a first valve 10, a second valve 11, and a third valve 12. The input end of the sample chamber 7 is connected to the gas pipeline 5, and the auxiliary chamber 8 is connected to the sample chamber 7. The first valve 10 is installed at the input end of the sample chamber 7, the second valve 11 is located between the sample chamber 7 and the auxiliary chamber 8, the third valve 12 is located at the output end of the auxiliary chamber 8, and the pressure sensor 9 is installed between the sample chamber 7 and the second valve 11.

[0064] The pressure inside the sample chamber 7 is balanced by the auxiliary chamber 8, the first valve 10, the second valve 11, and the third valve 12, and the pressure signal of the sample chamber 7 is collected by the pressure signal for subsequent volume determination.

[0065] The present invention also provides a method for in-situ, real-time, and continuous measurement of volume changes in chemical reactions involving gases using the apparatus described herein, comprising the following steps:

[0066] S1. Place the sample into the sample chamber 7, open the gas cylinder, open the valve positioner of the gas pipeline 5 connected to the gas cylinder containing the measuring gas, and open the first valve 10, the second valve 11, and the third valve 12. The measuring gas is used as an environmental medium to flow through the inside of the device, clearing the air from the sample chamber 7, the auxiliary chamber 8, and the gas pipeline 5, thus removing impurities and creating an ideal gas environment for subsequent testing to ensure the accuracy of the test. The impurity removal time can be set according to the characteristics of the sample (powder, block, liquid, or slurry) and the accuracy requirements.

[0067] S2, close the second valve 11 and the third valve 12, open the first valve 10, when the pressure difference between the sample chamber 7 and the external environment reaches the preset value (usually recommended to be 19 psi), the first valve 10 closes, and closes the valve positioner of the gas pipeline 5 connected to the gas cylinder containing the measured gas.

[0068] Once the pressure inside sample chamber 7 stabilizes, the pressure P1 inside sample chamber 7 is measured.

[0069] Open the second valve 11 to connect the sample chamber 7 and the auxiliary chamber 8. When the pressure in the sample chamber 7 and the auxiliary chamber 8 stabilizes, measure the pressure P2 in the sample chamber 7 and the auxiliary chamber 8. Open the third valve 12 and calculate the absolute volume of the sample at this time.

[0070] S3, open the valve positioner of the gas pipeline 5 of the gas cylinder containing the reaction gas, open the first valve 10, the second valve 11 and the third valve 12, and clear the measuring gas in the sample chamber 7, the auxiliary chamber 8 and the gas pipeline 5; and the reaction gas enters the sample chamber 7 and reacts chemically with the sample.

[0071] S4, close the second valve 11 and the third valve 12, open the first valve 10, when the pressure difference between the sample chamber 7 and the external environment reaches the preset value (usually recommended to be 19 psi), the first valve 10 closes, and the valve positioner of the gas pipeline 5 of the gas cylinder containing the reaction gas is closed.

[0072] Once the pressure inside sample chamber 7 stabilizes, the pressure P3 inside sample chamber 7 is measured.

[0073] Open the second valve 11 to connect the sample chamber 7 and the auxiliary chamber 8. When the pressure in the sample chamber 7 and the auxiliary chamber 8 stabilizes, measure the pressure P4 in the sample chamber 7 and the auxiliary chamber 8, and then open the third valve 12.

[0074] S5, open the valve positioner of the gas pipeline 5 connected to the gas cylinder containing the measuring gas, and open the first valve 10, the second valve 11 and the third valve 12;

[0075] S6, repeat steps S2-S5, and measure the final pressure P in sample chamber 7. N The absolute volume and volume change of the sample are calculated at this point. This technique enables continuous measurement throughout the duration of the chemical reaction, eliminating the need to remove reactants and products from the instrument and thus avoiding errors caused by transfer. Therefore, the cessation of the cycle depends on the duration of the chemical reaction.

[0076] In a preferred embodiment of the present invention, the absolute volume V of the sample is calculated. P The method is as follows:

[0077] ,

[0078] Among them, V C V is the volume of the sample chamber. A P1 is the volume of the auxiliary chamber, P2 is the pressure inside the sample chamber, and P2 is the pressure inside both the sample chamber and the auxiliary chamber.

[0079] In a preferred embodiment of the present invention, the method for calculating the sample volume change is as follows:

[0080] Calibration and adjustment are required before reaction and measurement, assuming sample chamber 7 is empty:

[0081] First measurement of gas: Ventilation time t2 min;

[0082] First reaction gas: Ventilation time t1 min;

[0083] Second gas flow measurement: Ventilation time t2 min;

[0084] Second reaction gas: Ventilation time t1 min;

[0085] And so on, to obtain the nth measurement of the gas and the reaction gas. for:

[0086] ,

[0087] Alternatively, the absolute volume of the gas measured in the nth pass is:

[0088] V p(2n-1) =Vc+V A / (1-P 4n-3 / P 4n-2 ),

[0089] The absolute volume of the gas in the nth reaction is:

[0090] V p(2n) =Vc+V A / (1-P 4n-1 / P 4n ),

[0091] Among them, V C V is the volume of the sample chamber. A P is the volume of the additional compartment. n P is the pressure inside the sample chamber. n+1 The pressure within the sample chamber and the auxiliary chamber;

[0092] If V p5 =V p3 V p6 =Vp4 If the gas measured has completely purged the reactant gas, then it can be deduced that the gas measured has completely purged the reactant gas; otherwise, it indicates that the gas measured has not completely purged the reactant gas, and the time for the gas measured to purge the reactant gas in the experiment should be increased.

[0093] The absolute volume V of the sample is measured in the nth cycle. pn Subtract the absolute volume V of the sample measured for the first time p1 The volume change (V) before and after the reaction of the reactants with the gas was obtained. pn -V p1 ).

[0094] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0095] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for in-situ, real-time and continuous measurement of volume change of a chemical reaction involving gas, the device for in-situ, real-time and continuous measurement of volume change of a chemical reaction involving gas comprising at least two gas cylinders, a valve positioner, a gas pipeline and a true density instrument; one of the at least two gas cylinders contains a measuring gas, and the rest contain a reaction gas; The true density instrument is communicated with the gas cylinder through a gas pipeline, and the valve positioner is arranged on the gas pipeline. the method comprising the following steps: S1, placing a sample in a sample chamber, opening the gas cylinders, opening the valve positioner of the gas pipeline connected to the gas cylinder containing the measuring gas, opening the first valve, the second valve and the third valve, and flowing the measuring gas as an environmental medium through the inside of the device to remove air in the sample chamber, the additional chamber and the gas pipeline; S2, closing the second valve and the third valve, opening the first valve, and closing the first valve and the valve positioner of the gas pipeline connected to the gas cylinder containing the measuring gas when the pressure difference between the sample chamber and the external environment reaches a preset value; measuring the pressure P1 in the sample chamber when the pressure in the sample chamber is stable; opening the second valve to connect the sample chamber and the additional chamber, measuring the pressure P2 in the sample chamber and the additional chamber when the pressure in the sample chamber and the additional chamber is stable, and opening the third valve; S3, opening the valve positioner of the gas pipeline of the gas cylinder containing the reaction gas, opening the first valve, the second valve and the third valve, and removing the measuring gas in the sample chamber, the additional chamber and the gas pipeline; and the reaction gas enters the sample chamber and reacts with the sample; S4, closing the second valve and the third valve, opening the first valve, and closing the first valve and the valve positioner of the gas pipeline connected to the gas cylinder containing the reaction gas when the pressure difference between the sample chamber and the external environment reaches a preset value; measuring the pressure P3 in the sample chamber when the pressure in the sample chamber is stable; opening the second valve to connect the sample chamber and the additional chamber, measuring the pressure P4 in the sample chamber and the additional chamber when the pressure in the sample chamber and the additional chamber is stable, and opening the third valve; S5, opening the valve positioner of the gas pipeline connected to the gas cylinder containing the measuring gas, opening the first valve, the second valve and the third valve; S6, repeating steps S2-S5 to measure the pressure P in the final sample cell N , calculating the absolute volume and volume change of the sample at this time.

2. The method of in situ, real-time, continuous measurement of volume change of a chemical reaction involving a gas according to claim 1, wherein, the true density instrument comprises a sample chamber for placing a reaction sample, an additional chamber for balancing the pressure in the sample chamber, a pressure sensor, a first valve, a second valve and a third valve; the input end of the sample chamber is connected to the gas pipeline, and the additional chamber is connected to the sample chamber; the first valve is installed at the input end of the sample chamber, the second valve is arranged between the sample chamber and the additional chamber, and the third valve is arranged at the output end of the additional chamber; the pressure sensor is installed between the sample chamber and the second valve.

3. The method of in situ, real-time, continuous measurement of volume change of a chemical reaction involving a gas according to claim 1, wherein, The valve positioner adopts a single-acting valve positioner or a double-acting valve positioner.

4. The method for in-situ, real-time, and continuous measurement of volume changes in chemical reactions involving gases as described in claim 1, characterized in that, The absolute volume V of the sample is calculated P The method is as follows: ， where V C is the volume of the sample chamber, V A is the volume of the additional chamber, P1 is the pressure in the sample chamber, and P2 is the pressure in the sample chamber and the additional chamber.

5. The method for in-situ, real-time, and continuous measurement of volume changes in chemical reactions involving gases as described in claim 1, characterized in that, The method for calculating the volume change of the sample is as follows: Before the reaction and measurement, calibration and debugging are required, and the sample chamber is empty: First pass measurement of gas: , ventilation time t2 min; First pass of the reaction gas: for a time t1 min; Second pass measurement gas: Pass time t2 min; Second time the reaction gas is passed: for a time t1 min; By analogy, the nth time the measurement gas, the reaction gas is obtained is: ， Alternatively, the absolute volume of the n-th time of passing the measuring gas is: V p(2n-1) = Vc+ V A / (1-P 4n-3 / P 4n-2 ), the absolute volume of the n-th time of passing the reaction gas is: V p(2n) =Vc+V A / (1-P 4n-1 / P 4n ), where V C is the volume of the sample chamber, V A is the volume of the additional chamber, P n is the pressure in the sample chamber, P n+1 is the pressure in the sample chamber and the additional chamber; If V p5 = V p3 ; V p6 = V p4 , it can be concluded that the measuring gas has completely replaced the reaction gas; otherwise, it indicates that the measuring gas has not completely replaced the reaction gas, and the time for the measuring gas to replace the reaction gas in the experiment should be increased. The absolute volume V of the sample is measured at the nth cycle pn The absolute volume V of the sample is measured at the first cycle p1 The volume change (V pn -V p1 ) of the reactant before and after the reaction with the gas is obtained.

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