A gas flow-stabilized apparatus and method for generating standard gases of volatile organic compounds.

Abstract

This invention pertains to standard test gas generation devices, specifically relating to a stable gas flow standard gas generation device and method for multiple volatile organic compounds (VOCs). The device includes multiple parallel-flow evaporation tanks connected in parallel. Each parallel-flow evaporation tank has a continuous U-shaped trough structure, comprising an organic liquid tank and a continuous airflow channel. A water / oil bath heater is used to generate saturated vapor of VOCs. This invention controls the concentration of saturated vapor of VOCs by controlling the temperature through the water / oil bath, and ultimately forms a VOC gas to be diluted with controllable concentration, temperature, and flow rate through the continuous airflow channel. Synthetic air supplied by a synthetic air supply device, along with multiple VOC gases to be diluted, enters a gas manifold and is discharged through an outlet pipeline. During this process, a mass flow controller and temperature sensor are installed to control the dilution ratio, carrier gas flow rate, and airflow temperature of various VOCs.

Description

Technical Field

[0001] This invention pertains to standard test gas generation devices, and specifically relates to a device and method for generating standard gases of multi-volatile organic compounds with stable gas flow. Background Technology

[0002] The presence of volatile organic compounds (VOCs) and the need for their detection are undeniable in healthcare, public safety, industrial and agricultural production, and daily life. The widespread use of VOCs in production environments and daily life makes their flammability, explosiveness, and biotoxicity a significant concern. In the healthcare field, VOCs are often used as biomarkers for the early diagnosis of diseases such as diabetes and cancer. This underscores the high significance and value of developing gas sensors targeting VOCs.

[0003] In the development of gas sensors targeting volatile organic compounds (VOCs), standard test gases are crucial for sensor performance testing. Furthermore, to cope with complex sensor application environments, current development of novel gas sensors generally focuses on the detection of the composition and concentration of multi-component complex gases. This necessitates that the standard test gas supply device for the sensor testing system simultaneously meet the basic requirements of a rich selection of VOC gases and controllable and adjustable concentrations. However, in practical sensor testing, to observe sensor performance in the most detailed possible way and to observe the effects of gas flow rate and temperature on sensor performance, the standard test gas supply device must also be able to provide standard test gases for extended periods and maintain a controllable, temperature-controlled, and stable gas flow.

[0004] Clearly, current standard test gas supply devices that rely on offline preparation of standard gas cylinders are ill-suited to meet such complex requirements. The need to prepare corresponding standard gas cylinders in advance for each new gas necessitates flexibility. While standard test gas supply devices using a fixed-volume evaporation chamber can precisely control the composition and concentration of the standard test gas by controlling the type and quality of the volatile organic liquid evaporated within the chamber, thus meeting the requirement for flexible gas selection, the limited total gas volume within the chamber makes it difficult to supply standard test gas to the gas sensor testing device for extended periods. The invention patent with application number CN 119368098 A discloses a device employing a precision injection pump, a micro-injection needle, and a thermal evaporation tube. While this can address the issue of continuous standard test gas supply by using a larger injection needle, the higher cost of the precision components in the system leads to a faster increase in cost when expanding the entire system. Standard gas supply devices using gas washing bottles for standard test gas mixing, although offering low system expansion costs and flexible gas selection, still suffer from serious problems such as large fluctuations in the concentration of the generated standard test gas, high concentrations, and unstable airflow and temperature. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a device and method for generating standard gases with stable airflow, thereby achieving high scalability, concentration stability, airflow stability, and stable airflow temperature for standard gas generation.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A stable airflow standard gas generator for volatile organic compounds (VOCs) includes multiple parallel-flow evaporation tanks connected in parallel. Each parallel-flow evaporation tank is equipped with a water / oil bath heater, multiple temperature sensors (I), and an acceleration / tilt sensor. The water / oil bath heater is used to generate saturated vapor of VOCs from the VOCs. The temperature sensors (I) are used to measure the temperature of the parallel-flow evaporation tank, and the acceleration / tilt sensors are used to detect whether the parallel-flow evaporation tank tilts or vibrates. The evaporation tank body within the parallel-flow evaporation tank has a continuous U-shaped trough structure, including an organic liquid tank and a continuous airflow channel. The organic liquid tank contains the VOCs. The continuous airflow channel has an air inlet at one end and an air outlet at the other end. One end of the air inlet pipe is connected to the air inlet, and the other end is connected to the gas supply device. The gas supplied by the gas supply device enters the continuous airflow channel through the air inlet pipe to drive the movement of VOC gas saturated vapor. One end of the air outlet pipe is connected to the air outlet, and the other end is connected to the gas manifold. The gas supply device is also equipped with a synthesis air pipeline, which is connected to the gas manifold. The gas manifold is also connected to a discharge pipeline. The gas supply device inputs synthesis air into the gas manifold through the synthesis air pipeline to mix with VOC gas saturated vapor to form a mixed gas. The mixed gas is discharged through the discharge pipeline.

[0008] The horizontal flow evaporation tank includes an evaporation tank body and an outer shell body. An evaporation tank cover is sealed to the top of the evaporation tank body, which is fixed to the outer shell body. An outer shell cover is also sealed to the top of the outer shell body, and an acceleration tilt sensor is installed on the top of the outer shell cover. Multiple temperature sensors I are installed on the outer shell body. A water / oil bath heater is connected to the outer shell body. An inlet is located at the bottom of the organic liquid tank of the evaporation tank body. One end of a feed pipe passes through the outer shell body and connects to the inlet, while the other end of the feed pipe connects to a feed device. One end of an air inlet pipe passes through the outer shell body and connects to the air inlet of a continuous airflow channel. A [missing information - likely a device or component] is connected to the air inlet pipe. The system includes an inlet solenoid valve, an inlet temperature controller, and a mass flow controller I, which is connected to a gas supply device. One end of the outlet pipe passes through the outer casing and connects to the outlet of the continuous airflow channel. An outlet solenoid valve is installed on the outlet pipe, and the other end of the outlet pipe is connected to a gas manifold. A liquid level limiter is connected to the organic liquid tank and is located on the outside of the outer casing. The system also includes a water / oil bath heater, an inlet temperature controller, a mass flow controller I, an inlet solenoid valve, a feeding device, an outlet solenoid valve, a liquid level limiter, multiple temperature sensors I, and an acceleration and tilt sensor, all connected to a microcontroller. The microcontroller is connected to the main controller.

[0009] The synthetic air pipeline is connected to a mass flow controller II, which is connected to a gas supply device. The gas supply device is equipped with a temperature sensor II. An output temperature controller is installed on the discharge pipeline. The temperature sensor II, the mass flow controller II, and the output temperature controller are connected to the main controller, which is connected to a host computer.

[0010] The water / oil bath heater includes a liquid heating tank, a liquid pump, a heat pipe, and a semiconductor refrigeration chip. The liquid heating tank contains a heat pipe, and the semiconductor refrigeration chip is mounted on the liquid heating tank. The semiconductor refrigeration chip has heat exchange plates. The liquid pump is connected to the liquid heating tank. The outer shell has a water / oil bath inlet and a water / oil bath outlet. The liquid heating tank is connected to the water / oil bath outlet, and the liquid pump is connected to the water / oil bath inlet. The heat pipe, semiconductor refrigeration chip, and liquid pump are connected to a microcontroller. The liquid heating tank has a feed inlet.

[0011] The liquid level limiter includes a communicating vessel body and a communicating vessel solenoid valve. The communicating vessel body is provided with a communicating vessel interface, which passes through the outer shell body and connects to the communicating vessel connection hole on the evaporation tank body. The communicating vessel body is provided with an upper liquid level sensor and a lower liquid level sensor. The top of the communicating vessel body is provided with a communicating vessel solenoid valve. The communicating vessel solenoid valve, the upper liquid level sensor, and the lower liquid level sensor are connected to a microcontroller.

[0012] The feeding device includes a feeding bottle containing a feeding pipe. One end of the feeding pipe extends into the liquid in the feeding bottle, and the other end is connected to the liquid inlet of the evaporation tank body. A feeding outlet solenoid valve is installed on the feeding pipe. A pressure gas pipe is installed inside the feeding bottle, and the other end of the pressure gas pipe is connected to a tee. The other two through holes of the tee are respectively connected to a pressure gas supply device and a tail gas recovery device. A feeding inlet solenoid valve is installed on the pipeline connected to the pressure gas supply device, and a pressure relief valve is installed on the pipeline connected to the tail gas recovery device. The feeding inlet solenoid valve and the feeding outlet solenoid valve are connected to a microcontroller.

[0013] A method for generating a gaseous standard gas containing multiple volatile organic compounds with stable gas flow, comprising the following steps:

[0014] Step 1: The gas supply device inputs the target working flow rate of synthetic air into the gas sensor through the synthetic air pipeline and the discharge pipeline. The target working flow rate is the flow rate set value of the mass flow controller II.

[0015] The method for determining the target working flow rate of synthetic air is as follows:

[0016] Q0 = Q (T0 / T) (1);

[0017] In the formula, Q0 is the target working flow rate of the synthetic air; Q is the target flow rate set by the host computer; T is the target temperature set by the host computer, and the target temperature T is controlled by the output port temperature controller; T0 is the gas temperature provided by the gas supply device, and the gas temperature is obtained by temperature sensor II.

[0018] Step 2: The microcontrollers of multiple horizontal flow evaporation tanks control the temperature of the water / oil bath heaters to ensure that each volatile organic compound reaches the target working concentration of each VOC gas saturated vapor. The microcontrollers control the opening of the inlet solenoid valve, so that the gas supply device delivers the target working flow rate of gas to the continuous airflow channel of the evaporation tank body, and pushes the VOC gas saturated vapor to flow towards the outlet at the target working flow rate. The outlet solenoid valve is opened, and the VOC gas saturated vapor enters the gas manifold through the outlet pipe. During this process, the mass flow controller I and the inlet temperature controller control the flow rate and temperature of the gas supplied by the gas supply device, respectively.

[0019] The methods for determining the temperature of the water / oil bath heater and the target operating flow rate of VOC gas saturated steam are as follows:

[0020] S1: Obtain the comparison relationship between the target working flow rate and the target working concentration of saturated vapor for each VOC gas. The specific calculation method is as follows;

[0021] (2);

[0022] In the formula, The target working concentration of a certain VOC gas saturated vapor; The target operating flow rate of a certain VOC gas saturated vapor; The target concentration of a certain VOC gas is set for the host computer; This represents the number of VOC gas types.

[0023] S2: The optimal operating flow rate of mass flow controller I is the target operating flow rate of each VOC gas saturated steam. Based on the correlation between the target operating flow rate and the target operating concentration of VOC gas saturated steam, the target operating concentration of each VOC gas saturated steam is determined. Based on the correspondence table between the target operating concentration of VOC gas saturated steam and the target operating concentration of saturated steam, the corresponding temperature of each VOC gas saturated steam is determined. This determines the required temperature of the horizontal flow evaporator and, consequently, the temperature of the water / oil bath heater.

[0024] Step 3: The gas supply device inputs the required flow compensation amount of synthetic air into the gas manifold through the synthetic air pipeline;

[0025] The formula for calculating the required flow compensation amount of syngas is as follows:

[0026] Q'=Q0- (3);

[0027] In the formula, Q' is the flow compensation amount of the synthetic air;

[0028] Step 4: The synthetic air from Step 3 is mixed with the saturated vapors of multiple VOC gases from Step 2 at the gas manifold and enters the gas sensor through the discharge pipeline.

[0029] The beneficial effects of this invention are as follows:

[0030] 1. This invention uses a horizontal flow evaporation tank as the core component. It employs a horizontal flow evaporation method to generate saturated vapors of volatile organic compounds with stable airflow, concentration, and temperature. The concentration of the saturated vapors of volatile organic compounds is controlled by a water / oil bath. The vapors are then transported through a continuous airflow channel to ultimately form volatile organic compound gas to be diluted with controllable concentration, temperature, and flow rate. Multiple horizontal flow evaporation tanks are connected in parallel. Synthetic air supplied by a synthetic air supply device and multiple volatile organic compound gases to be diluted enter a gas manifold and are discharged through an outlet pipeline. During this process, an inlet temperature controller, a mass flow controller I, a temperature sensor I, and a mass flow controller II are installed to achieve control of the dilution ratio, carrier gas flow rate, and final airflow temperature of various volatile organic compound gases to be diluted.

[0031] 2. The design of the independent horizontal flow evaporation tank and the structural design of the horizontal flow evaporation tank in this application make this invention superior to existing standard test gas supply devices in terms of strong scalability, strong modifiability, low cost, low expansion cost, stable airflow, long operating time, convenient gas type replacement, online generation, wide range of gas concentration selection, and the ability to configure low concentration standard test gases. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the overall structure of the horizontal flow evaporation tank of the multi-volatile organic compound standard gas generation device of the present invention;

[0033] Figure 2 This is an exploded view of the horizontal flow evaporation tank of the multi-volatile organic compound standard gas generating device of the present invention;

[0034] Figure 3 This is a schematic diagram of the bottom of the horizontal flow evaporation tank of the multi-volatile organic compound standard gas generating device of the present invention;

[0035] Figure 4 This is a schematic diagram of the structure of the evaporation tank body of the multi-volatile organic compound standard gas generating device of the present invention. Figure 1 ;

[0036] Figure 5 This is a schematic diagram of the structure of the evaporation tank body of the multi-volatile organic compound standard gas generating device of the present invention. Figure 2 ;

[0037] Figure 6 This is a schematic diagram of the horizontal flow evaporation tank of the multi-volatile organic compound standard gas generating device of the present invention;

[0038] Figure 7 This is a schematic diagram showing the connection of multiple horizontal flow evaporation tanks in the multi-volatile organic compound standard gas generation device of the present invention;

[0039] Figure 8 This is a schematic diagram of the electrical connections of multiple horizontal flow evaporation tanks in the multi-volatile organic compound standard gas generating device of the present invention;

[0040] Figure 9 This is a schematic diagram of the liquid level controller of the multi-volatile organic compound standard gas generating device of the present invention;

[0041] Figure 10 This is a schematic diagram of the feeding device of the multi-volatile organic compound standard gas generating device of the present invention;

[0042] Figure 11 This is a schematic diagram of the water / oil bath heater of the multi-volatile organic compound standard gas generating device of the present invention;

[0043] In the diagram: 1. Outer shell cover; 2. Outer shell sealing gasket; 3. Outer shell body; 4. Evaporation tank cover; 5. Evaporation tank sealing gasket; 6. Evaporation tank body; 7. Isolation column; 8. Water / oil bath outlet; 9. Water / oil bath inlet; 10. Acceleration and tilt sensor; 11. Air inlet pipe connection port; 12. Air outlet pipe connection port; 13. Feed pipe connection port; 14. Temperature sensor I; 15. Liquid level limiter; 1501. Communicating vessel interface; 1502. Communicating vessel body; 1503. Upper liquid level sensor; 1504. Lower liquid level sensor; 1505. Communicating vessel electromagnetic... 16. Valve; 17. Air inlet; 18. Liquid inlet; 19. Communicator connection hole; 20. Organic liquid tank; 21. Continuous airflow channel; 22. Feeding device; 2201. Feeding bottle; 2202. Feeding inlet solenoid valve; 2203. T-junction; 2204. Pressure relief valve; 2205. Tail gas recovery device; 2206. Feeding outlet solenoid valve; 2207. Pressurized gas supply device; 23. Water / oil bath heater; 2301. Liquid heating tank; 2302. Liquid pump; 2303. Heat pipe; 2304. Semiconductor refrigeration chip. Detailed Implementation

[0044] The present invention will now be described in detail with reference to the accompanying drawings.

[0045] like Figures 1-11As shown, a multi-volatile organic compound (VOC) standard gas generating device with stable airflow includes multiple horizontal flow evaporation tanks connected in parallel. Each horizontal flow evaporation tank is equipped with a water / oil bath heater 23, multiple temperature sensors I14, and an acceleration tilt sensor 10. The water / oil bath heater 23 is used to generate VOC gas saturated vapor from the VOCs, and the concentration of the saturated vapor generated from the VOC liquid is adjusted by regulating the temperature of the horizontal flow evaporation tank. The temperature sensors I14 are used to measure the temperature of the horizontal flow evaporation tank, and the acceleration tilt sensor 10 is used to detect whether the horizontal flow evaporation tank tilts or vibrates. The evaporation tank body 6 of the horizontal flow evaporation tank has a continuous U-shaped trough structure, including an organic liquid tank 20 and a continuous airflow channel 21. The container holds volatile organic compounds. One end of the upper part of the continuous airflow channel 21 has an air inlet 16, and the other end has an air outlet 17. One end of the air inlet pipe is connected to the air inlet 16, and the other end is connected to a gas supply device. The gas supplied by the gas supply device enters the continuous airflow channel 21 of the horizontal flow evaporation tank through the air inlet pipe to drive the movement of VOC gas saturated vapor. One end of the air outlet pipe is connected to the air outlet 17, and the other end is connected to a gas manifold. The gas supply device is also equipped with a synthetic air pipeline, which is connected to the gas manifold. The gas manifold is also connected to a discharge pipeline, which is connected to a gas sensor. The gas supply device inputs synthetic air into the gas manifold through the synthetic air pipeline to mix with the VOC gas saturated vapor to form a mixed gas. The mixed gas enters the gas sensor through the discharge pipeline for detection.

[0046] In this embodiment, multiple horizontal flow evaporation tanks are set up and controlled independently. According to the needs of the host computer, multiple VOC gas saturated vapors can be supplied to the gas sensor, which is suitable for the detection of various VOC gases. For each horizontal flow evaporation tank, a water / oil bath heater heats / cools the organic liquid tank 20 of the horizontal flow evaporation tank. With the feedback of temperature sensor I14, the temperature in the horizontal flow evaporation tank is adjusted and VOC gas saturated vapors are generated. The gas supply device supplies gas to the evaporation tank body 6 of the horizontal flow evaporation tank through the air inlet pipe to drive the VOC gas saturated vapors to flow along the continuous airflow channel 21 and finally enter the gas collector through the air outlet 17. The setting of the continuous airflow channel 21 allows sufficient time for the gas mass to reach the vapor saturation level when it flows out, so that the concentration and flow rate of the saturated vapor are more stable. The saturated vapors entering the gas collector are mixed with the synthetic air supplied by the gas supply device through the synthetic air pipeline and discharged to the gas sensor for detection.

[0047] In this embodiment, one or more advection evaporation modules are used to generate one or more streams of saturated steam with a fixed flow rate and temperature, and a dilution stream with a fixed flow rate and temperature is provided through a gas supply device. After the two streams are mixed in the gas manifold, they are passed through the output temperature controller to form a multi-component standard test gas with a fixed concentration, flow rate and temperature, thereby realizing the online generation of standard test gas.

[0048] The horizontal flow evaporation tank includes an evaporation tank body 6 and an outer shell body 3. An evaporation tank cover 4 is sealed to the top of the evaporation tank body 6. The evaporation tank body 6 is fixed to the outer shell body 3. An outer shell cover 1 is sealed to the top of the outer shell body 3. An acceleration tilt sensor 10 is installed on the top of the outer shell cover 1. Multiple temperature sensors I14 are installed on the outer shell body 3. A water / oil bath heater 23 is connected to the outer shell body 3. The continuous airflow channel 21 of the evaporation tank body 6 is located above the organic liquid tank 20. The bottom of the organic liquid tank 20 has a liquid inlet 18. One end of the continuous airflow channel 21 has an air inlet 16, and the other end has an air outlet 17. An air inlet pipe connection 11, an air outlet pipe connection 12, and a feed pipe connection 13 are respectively provided at the air inlet 16, air outlet 17, and liquid inlet 18. One end of the air inlet pipe passes through the outer shell body 3 and connects to the air inlet pipe connection 11. The intake pipe is connected to an intake solenoid valve, an intake temperature controller, and a mass flow controller I. The mass flow controller I is connected to an air supply device, and a pressure reducing and stabilizing valve I is installed on its connecting pipe. One end of the exhaust pipe passes through the outer shell 3 and connects to the exhaust pipe connection port 12. An exhaust solenoid valve is installed on the exhaust pipe, and the other end of the exhaust pipe is connected to a manifold. One end of the feed pipe passes through the outer shell 3 and connects to the feed pipe connection port 13, and the other end of the feed pipe is connected to the feed device 22. A liquid level limiter 15 is connected to the organic liquid tank 20 and is located on the outside of the outer shell 3. The water / oil bath heater 23, the intake temperature controller, the mass flow controller I, the intake solenoid valve, the feed device 22, the exhaust solenoid valve, the liquid level limiter 15, multiple temperature sensors I 14, and the acceleration tilt sensor 10 are connected to a microcontroller, which is connected to the main controller.

[0049] In this embodiment, an evaporation tank sealing gasket 5 is provided between the evaporation tank body 6 and the evaporation tank cover 4, and an outer shell sealing gasket 2 is provided between the outer shell body 3 and the outer shell cover 1; an isolation column 7 is provided on the outer shell body 3 to support the evaporation tank body 6; three temperature sensors I 14 are provided on the outer shell body 3, one of which is located below the air inlet 16, and the other two are located at the bottom and side of the outer shell body 3. The temperature sensor I 14 located below the air inlet 16 serves as reference information, and the information of the other two temperature sensors I is compared with the temperature sensor I until it matches the reference information, indicating that the evaporation tank body 6 is heated evenly; the air inlet temperature controller is set to avoid temperature instability caused by the inconsistency between the airflow temperature and the temperature of the evaporation tank body 6; the pressure reducing and stabilizing valve I is used to regulate the fluid pressure delivered by the gas supply device to maintain a stable outlet pressure.

[0050] In this embodiment, the evaporation tank body 6 is a continuous U-shaped trough structure, i.e., a serpentine trough structure. The bottom of the continuous U-shaped trough structure is an organic liquid tank 20, and the top is a continuous airflow channel 21. The saturated vapors of the VOC gas evaporated in the organic liquid tank 20 flow in the continuous airflow channel 21. The two side walls of the continuous U-shaped trough restrict the diffusion of the vapors, so that the saturated vapors can only flow along the path of the continuous U-shaped trough and generate saturated vapors. At the same time, driven by the gas from the gas supply device, the vapors enter the gas collection channel through the gas outlet 17. The gas flow rate delivered by the gas supply device is the flow rate of the saturated vapors. During this process, the temperature controller and mass flow controller I connected to the inlet pipe are used to control the temperature and flow rate of the gas input from the gas supply device, respectively. The inlet solenoid valve is used to control whether the inlet pipe is open. The feeding device 22 replenishes the volatile organic liquids into the organic liquid tank 20 according to the indication of the liquid level limiter 15.

[0051] The organic liquid tank 20 and the continuous airflow channel 21 have the same length, denoted as L; the width of the continuous airflow channel 21 is denoted as l; the dimensions of the organic liquid tank 20 and the continuous airflow channel 21 satisfy L*l≥4.5cm. 2 .

[0052] In this embodiment, the cross-section of the continuous airflow channel 21 is a square structure with a width of l. The organic liquid tank 20 and the continuous airflow channel 21 are designed to have sufficient length so that the VOC gas from the evaporation tank body 6 can reach the saturated vapor concentration.

[0053] The synthetic air pipeline is connected to a mass flow controller II, which is connected to a gas supply device. A pressure reducing and stabilizing valve II is installed on the connecting pipeline to regulate the fluid pressure delivered by the gas supply device and maintain a stable outlet pressure. A temperature sensor II is installed on the gas supply device. An output temperature controller is installed on the discharge pipeline connected to the gas sensor and the gas manifold. The temperature sensor II, mass flow controller II, and output temperature controller are connected to the main controller, which is connected to the host computer. The host computer is connected to the gas sensor.

[0054] In this embodiment, the host computer sets the temperature, flow rate, and concentration of multiple VOC gases required by the gas sensor. The required temperature of the VOC gases is controlled by the output temperature controller. The mass flow controller II controls the flow rate of the synthetic air discharged by the gas supply device through the synthetic air pipeline. The temperature sensor II monitors the temperature of the gas delivered by the gas supply device. The sum of the flow rates of the multiple VOC saturated vapors and the flow rate of the synthetic air supplied by the gas supply device is the flow rate required by the gas sensor.

[0055] In this embodiment, pressure reducing and stabilizing valve I and pressure reducing and stabilizing valve II are used to reduce and stabilize the high-pressure gas source (usually 10 MPa) to the gas source pressure required by mass flow controller I and mass flow controller II (0.2 MPa).

[0056] The water / oil bath heater 23 includes a liquid heating tank 2301, a liquid pump 2302, a heat pipe 2303, and a semiconductor cooling chip 2304. The liquid heating tank 2301 is equipped with a heat pipe 2303, and the liquid heating tank 2301 is equipped with a semiconductor cooling chip 2304. The semiconductor cooling chip 2304 is equipped with heat exchange plates. The liquid pump 2302 is connected to the liquid heating tank 2301. The outer shell 3 is equipped with a water / oil bath inlet 9 and a water / oil bath outlet 8. The liquid heating tank 2301 is connected to the water / oil bath outlet 8, and the liquid pump 2302 is connected to the water / oil bath inlet 9. The heat pipe 2303, the semiconductor cooling chip 2304, and the liquid pump 2302 are connected to a microcontroller. The liquid heating tank 2301 is equipped with a feeding port.

[0057] The liquid level limiter 15 includes a communicating vessel body 1502 and a communicating vessel solenoid valve 1505. The communicating vessel body 1502 is provided with a communicating vessel interface 1501, which passes through the outer shell body 3 and connects to the communicating vessel connection hole 19 on the evaporation tank body 6. The communicating vessel body 1502 is provided with an upper liquid level sensor 1503 and a lower liquid level sensor 1504. The top of the communicating vessel body 1502 is provided with a communicating vessel solenoid valve 1505. The communicating vessel solenoid valve 1505, the upper liquid level sensor 1503, and the lower liquid level sensor 1504 are connected to a microcontroller.

[0058] In this embodiment, the upper liquid level sensor 1503 and the lower liquid level sensor 1504 are used to control the upper and lower limits of the volatile organic liquid in the organic liquid tank 20, respectively, and transmit the relevant information to the microcontroller, thereby controlling the liquid inlet device to replenish the volatile organic liquid in a timely manner; the communicating vessel solenoid valve 1505 is used to ensure that VOC gas does not leak out when the evaporation tank body is in a non-replenishing state.

[0059] The feeding device 22 includes a feeding bottle 2201, a feeding inlet solenoid valve 2202, a three-way valve 2203, a pressure relief valve 2204, a tail gas recovery device 2205, and a feeding outlet solenoid valve 2206. The feeding bottle 2201 is equipped with a feeding pipe, one end of which extends into the liquid in the feeding bottle 2201, and the other end is connected to the liquid inlet 18 of the evaporation tank body 6. The feeding outlet solenoid valve 2206 is provided on the feeding pipe. The feeding bottle 2201 is equipped with a pressure gas pipe, the other end of which is connected to the three-way valve 2203. The other two through holes of the three-way valve 2203 are respectively connected to the pressure gas supply device 2207 and the tail gas recovery device 2205. The feeding inlet solenoid valve 2202 is provided on the pipeline connected to the pressure gas supply device 2207, and the pressure relief valve 2204 is provided on the pipeline connected to the tail gas recovery device 2205. The feeding inlet solenoid valve 2202 and the feeding outlet solenoid valve 2206 are connected to a microcontroller.

[0060] In this embodiment, the pressurized gas supply device 2207 can provide air at 0.11~0.15 MPa. When replenishment is required, the pressurized gas supply device 2207 introduces pressurized gas through the pressurized gas pipe replenishment bottle 2201, allowing the volatile organic liquid to enter the evaporation tank body 6 from the replenishment pipe. When the required volume of liquid is reached, the pressure relief valve 2204 is manually adjusted to allow the gas to enter the tail gas recovery device 2205, preventing the replenishment bottle 2201 from being affected by long-term pressure.

[0061] A method for generating a gaseous standard gas containing multiple volatile organic compounds with stable gas flow, comprising the following steps:

[0062] Step 0: Before the entire device is put into operation, the operator should turn on the gas supply device and adjust the pressure of pressure reducing and stabilizing valve I and pressure reducing and stabilizing valve II to the gas source pressure required by mass flow controller I and mass flow controller II, respectively.

[0063] Step 1: The gas supply device inputs the target working flow rate of synthetic air into the gas sensor through the synthetic air pipeline and the discharge pipeline. The target working flow rate is the flow rate set value of the mass flow controller II corresponding to the target flow rate required by the gas sensor.

[0064] The method for determining the target working flow rate of synthetic air is as follows:

[0065] Q0 = Q (T0 / T) (4);

[0066] In the formula, Q0 is the target working flow rate of the synthetic air; Q is the target flow rate set by the host computer; T is the target temperature set by the host computer, and the target temperature T is controlled by the output port temperature controller; T0 is the gas temperature provided by the gas supply device, and the gas temperature is obtained by temperature sensor II.

[0067] Step 2: The microcontrollers of multiple horizontal flow evaporation tanks control the temperature of the water / oil bath heaters 23 respectively to make each volatile organic compound reach the target working concentration of each VOC gas saturated vapor. The microcontrollers control the inlet solenoid valve to open, so that the gas supply device delivers the target working flow rate of gas to the continuous airflow channel 21 of the evaporation tank body 6, and pushes the VOC gas saturated vapor to flow towards the outlet 17 at the target working flow rate. The outlet solenoid valve is opened, and the VOC gas saturated vapor enters the gas manifold through the outlet pipe. During this process, the mass flow controller I and the inlet temperature controller control the flow rate and temperature of the gas supplied by the gas supply device respectively.

[0068] The methods for determining the temperature of the water / oil bath heater and the target operating flow rate of VOC gas saturated steam are as follows:

[0069] S1: Obtain the comparison relationship between the target working flow rate and the target working concentration of saturated vapor for each VOC gas. The specific calculation method is as follows;

[0070] (5);

[0071] (6);

[0072] In the formula, The saturated vapor flow rate of a certain VOC gas in a horizontal flow evaporator; The target working concentration of a certain VOC gas saturated vapor; The target operating flow rate of a certain VOC gas saturated vapor; The target concentration of a certain VOC gas is set for the host computer; This represents the number of VOC gas types. The temperature corresponding to the saturated vapor of a certain VOC gas;

[0073] S2: The optimal operating flow rate of mass flow controller I is the target operating flow rate of each VOC gas saturated steam. Based on the correlation between the target operating flow rate and the target operating concentration of VOC gas saturated steam, the target operating concentration of each VOC gas saturated steam is determined. Based on the correspondence table between the target operating concentration of VOC gas saturated steam and the target operating concentration of saturated steam, the corresponding temperature of each VOC gas saturated steam is determined. This determines the required temperature of the horizontal flow evaporator and, consequently, the temperature of the water / oil bath heater.

[0074] In this embodiment, the table showing the correspondence between the target working concentration of VOC gas saturated steam and the corresponding temperature and the target working concentration of saturated steam is a parameter relationship that has already been obtained. After calculating the correspondence between the target working flow rate and the target working concentration of VOC gas saturated steam, a table showing the correspondence between the target working concentration of VOC gas saturated steam, the corresponding temperature, the target working concentration, and the target working flow rate can be obtained. Based on this table and combined with the optimal working flow rate of the mass flow controller I, the target working flow rate of each VOC gas saturated steam, the target working concentration of each VOC gas saturated steam, and the temperature required for the horizontal flow evaporator can be obtained.

[0075] The optimal operating flow rate of mass flow controller I is generally 50% of the design value of mass flow controller I. By combining the VOC gas saturated steam target operating concentration corresponding to temperature-target operating concentration-target operating flow rate comparison table, the optimal set of parameters is found, thereby determining the target operating flow rate of VOC gas saturated steam and the required temperature of the horizontal flow evaporator. Combined with temperature sensor I, the heating temperature of the water / oil bath heater is then determined.

[0076] Step 3: The gas supply device inputs the required flow compensation amount of synthetic air into the gas manifold through the synthetic air pipeline;

[0077] The formula for calculating the required flow compensation amount Q' of the syngas is as follows:

[0078] Q'=Q0- (7);

[0079] In the formula, Q' is the flow compensation amount of the synthetic air.

[0080] Step 4: The synthesized air in Step 3 and the saturated vapors of multiple VOC gases in Step 2 are mixed in the gas manifold to form a mixed gas. The mixed gas enters the gas sensor through the exhaust pipe. During this process, the output temperature controller is used to control the temperature of the mixed gas, which is the target temperature of the gas sensor set by the host computer.

Claims

1. A method for generating a standard gas of volatile organic compounds (VOCs) with stable airflow, based on a device for generating VOCs with stable airflow, the device comprising multiple parallel-flow evaporation tanks connected in parallel; each parallel-flow evaporation tank is equipped with a water / oil bath heater, multiple temperature sensors I, and an acceleration tilt sensor; the water / oil bath heater is used to generate saturated vapor of VOCs; the temperature sensors I are used to measure the temperature of the parallel-flow evaporation tank; and the acceleration tilt sensor is used to detect whether the parallel-flow evaporation tank tilts or vibrates; the evaporation tank body within the parallel-flow evaporation tank has a continuous U-shaped trough structure, including an organic liquid tank and a continuous airflow channel. Volatile organic compounds (VOCs) are placed in an organic liquid tank. An air inlet is located at one end of the upper part of a continuous airflow channel, and an air outlet is located at the other end. One end of an air inlet pipe is connected to the air inlet, and the other end is connected to a gas supply device. Gas supplied by the gas supply device enters the continuous airflow channel through the air inlet pipe to drive the movement of VOC saturated vapors. One end of the air outlet pipe is connected to the air outlet, and the other end is connected to a gas manifold. The gas supply device is also equipped with a synthetic air pipeline, which is connected to the gas manifold. The gas manifold is also connected to a discharge pipeline. The gas supply device inputs synthetic air into the gas manifold through the synthetic air pipeline to mix with the VOC saturated vapors to form a mixed gas. The mixed gas is discharged through the discharge pipeline. Its features are, Includes the following steps: Step 1: The gas supply device inputs the target working flow rate of synthetic air into the gas sensor through the synthetic air pipeline and the discharge pipeline. The target working flow rate is the flow rate set value of the mass flow controller II. Step 2: The microcontrollers of multiple horizontal flow evaporation tanks control the temperature of the water / oil bath heaters to ensure that each volatile organic compound reaches the target working concentration of each VOC gas saturated vapor. The microcontrollers control the opening of the inlet solenoid valve, so that the gas supply device delivers the target working flow rate of gas to the continuous airflow channel of the evaporation tank body, and pushes the VOC gas saturated vapor to flow towards the outlet at the target working flow rate. The outlet solenoid valve is opened, and the VOC gas saturated vapor enters the gas manifold through the outlet pipe. During this process, the mass flow controller I and the inlet temperature controller control the flow rate and temperature of the gas supplied by the gas supply device, respectively. The methods for determining the temperature of the water / oil bath heater and the target operating flow rate of VOC gas saturated steam are as follows: S1: Obtain the comparison relationship between the target working flow rate and the target working concentration of saturated vapor for each VOC gas. The specific calculation method is as follows; （2）； In the formula, The target working concentration of a certain VOC gas saturated vapor; The target operating flow rate of a certain VOC gas saturated vapor; The target concentration of a certain VOC gas is set for the host computer; Q0 represents the number of VOC gas types and the target working flow rate of the synthesis air. S2: The optimal operating flow rate of mass flow controller I is the target operating flow rate of each VOC gas saturated steam. Based on the correlation between the target operating flow rate and the target operating concentration of VOC gas saturated steam, the target operating concentration of each VOC gas saturated steam is determined. Based on the correspondence table between the target operating concentration of VOC gas saturated steam and the target operating concentration of saturated steam, the corresponding temperature of each VOC gas saturated steam is determined. This determines the required temperature of the horizontal flow evaporator and, consequently, the temperature of the water / oil bath heater. Step 3: The gas supply device inputs the required flow compensation amount of synthetic air into the gas manifold through the synthetic air pipeline; Step 4: The synthetic air from Step 3 is mixed with the saturated vapors of multiple VOC gases from Step 2 at the gas manifold and enters the gas sensor through the discharge pipeline.

2. The method for generating a gaseous, gas-stabilized standard gas for multi-volatile organic compounds according to claim 1, characterized in that, The horizontal flow evaporation tank includes an evaporation tank body and an outer shell body. An evaporation tank cover is sealed to the top of the evaporation tank body, which is fixed to the outer shell body. An outer shell cover is also sealed to the top of the outer shell body, and an acceleration tilt sensor is installed on the top of the outer shell cover. Multiple temperature sensors I are installed on the outer shell body. A water / oil bath heater is connected to the outer shell body. An inlet is located at the bottom of the organic liquid tank of the evaporation tank body. One end of a feed pipe passes through the outer shell body and connects to the inlet, while the other end of the feed pipe connects to a feed device. One end of an air inlet pipe passes through the outer shell body and connects to the air inlet of a continuous airflow channel. A [missing information - likely a device or component] is connected to the air inlet pipe. The system includes an inlet solenoid valve, an inlet temperature controller, and a mass flow controller I, which is connected to a gas supply device. One end of the outlet pipe passes through the outer casing and connects to the outlet of the continuous airflow channel. An outlet solenoid valve is installed on the outlet pipe, and the other end of the outlet pipe is connected to a gas manifold. A liquid level limiter is connected to the organic liquid tank and is located on the outside of the outer casing. The system also includes a water / oil bath heater, an inlet temperature controller, a mass flow controller I, an inlet solenoid valve, a feeding device, an outlet solenoid valve, a liquid level limiter, multiple temperature sensors I, and an acceleration and tilt sensor, all connected to a microcontroller. The microcontroller is connected to the main controller.

3. The method for generating a gaseous, gas-stabilized standard gas for multi-volatile organic compounds according to claim 1, characterized in that, The synthetic air pipeline is connected to a mass flow controller II, which is connected to a gas supply device. The gas supply device is equipped with a temperature sensor II. An output temperature controller is installed on the discharge pipeline. The temperature sensor II, the mass flow controller II, and the output temperature controller are connected to the main controller, which is connected to a host computer.

4. The method for generating a gaseous, gas-stabilized standard gas for multi-volatile organic compounds according to claim 1, characterized in that, The water / oil bath heater includes a liquid heating tank, a liquid pump, a heat pipe, and a semiconductor refrigeration chip. The liquid heating tank contains a heat pipe, and the semiconductor refrigeration chip is mounted on the liquid heating tank. The semiconductor refrigeration chip has heat exchange plates. The liquid pump is connected to the liquid heating tank. The outer shell has a water / oil bath inlet and a water / oil bath outlet. The liquid heating tank is connected to the water / oil bath outlet, and the liquid pump is connected to the water / oil bath inlet. The heat pipe, semiconductor refrigeration chip, and liquid pump are connected to a microcontroller. The liquid heating tank has a feed inlet.

5. The method for generating a gaseous, gas-stabilized standard gas for multi-volatile organic compounds according to claim 2, characterized in that, The liquid level limiter includes a communicating vessel body and a communicating vessel solenoid valve. The communicating vessel body is provided with a communicating vessel interface, which passes through the outer shell body and connects to the communicating vessel connection hole on the evaporation tank body. The communicating vessel body is provided with an upper liquid level sensor and a lower liquid level sensor. The top of the communicating vessel body is provided with a communicating vessel solenoid valve. The communicating vessel solenoid valve, the upper liquid level sensor, and the lower liquid level sensor are connected to a microcontroller.

6. The method for generating a gaseous, gas-stabilized standard gas for multiple volatile organic compounds according to claim 2, characterized in that, The feeding device includes a feeding bottle containing a feeding pipe. One end of the feeding pipe extends into the liquid in the feeding bottle, and the other end is connected to the liquid inlet of the evaporation tank body. A feeding outlet solenoid valve is installed on the feeding pipe. A pressure gas pipe is installed inside the feeding bottle, and the other end of the pressure gas pipe is connected to a tee. The other two through holes of the tee are respectively connected to a pressure gas supply device and a tail gas recovery device. A feeding inlet solenoid valve is installed on the pipeline connected to the pressure gas supply device, and a pressure relief valve is installed on the pipeline connected to the tail gas recovery device. The feeding inlet solenoid valve and the feeding outlet solenoid valve are connected to a microcontroller.

7. The method for generating a gaseous, gas-stabilized standard gas for multi-volatile organic compounds according to claim 5, characterized in that, In step 1, the method for determining the target working flow rate of the synthetic air is as follows: Q0 = Q*(T0 / T) (1); In the formula, Q0 is the target working flow rate of the synthetic air; Q is the target flow rate set by the host computer; T is the target temperature set by the host computer, and the target temperature T is controlled by the output port temperature controller; T0 is the gas temperature provided by the gas supply device, and this gas temperature is obtained by temperature sensor II.

8. The method for generating a gaseous, gas-stabilized standard gas for multi-volatile organic compounds according to claim 7, characterized in that, In step 3, the formula for calculating the required flow compensation amount of synthesis gas is as follows: （3）； In the formula, Q' is the flow compensation amount of the synthetic air.

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