CN113654851B - Device and method for sampling aerosol in containment under severe accident condition - Google Patents

Abstract

The purpose of the present invention is to provide an aerosol sampling device and measurement method suitable for use in containment vessels under severe accident conditions. The container is connected to an optical particle counter probe through a sampling pipe. A serial pressure reducing device is provided on the sampling pipe. A hot water exchange tank and a storage tank are provided. The pool is connected through two pipes with different heights. A heat exchange pipe is installed in the hot water exchange tank. One end of the heat exchange pipe is connected to the sampling pipe through an optical particle counter probe, and the other end of the heat exchange pipe extends from the bottom of the hot water exchange tank. The invention solves the current problem of insufficient sampling in high-temperature and high-humidity environments, and can operate stably and efficiently for a long time. The use of tandem decompression devices can achieve thermal depressurization of aerosols under minimal or even non-destructive conditions. The use of dual-point parameter measurement technology makes the aerosol sampling flow control more precise. The use of fiber filters can achieve aerosol removal under high temperature and high pressure conditions, which simplifies the difficulty of removing aerosol deposits in experimental equipment and tube walls.

Description

An aerosol sampling device and measurement suitable for use in containment vessels under severe accident conditions method

Technical field

The present invention relates to an aerosol sampling device and a measurement method, specifically to an aerosol sampling device and a measurement method under severe accident conditions in a nuclear power plant.

Background technique

When a serious accident occurs in a reactor, such as a large-scale failure of the core's fuel element cladding, fission products will be released from damaged or molten elements, and subsequently, there will be migration, settling and re-suspension processes in the reactor coolant system. After the pressure boundary of the reactor coolant system is damaged, the coolant with high temperature and high pressure and containing radioactive fission products will be released into the containment in the event of a breach accident. Aerosol is one of the main states of fission products. As a serious accident proceeds, it will migrate and settle within the containment. Once the integrity of the containment is damaged, these radioactive aerosols will be released into the environment, even if the integrity of the containment is damaged. If it is not destroyed, radioactive aerosols may leak into the environment through the gaps in the containment, causing harm to surrounding people and the environment. Therefore, monitoring the transport and deposition patterns of radioactive aerosols within the containment has important reference value for the formulation of accident emergency measures.

In addition, with the development of serious accidents, the thermal environment of aerosols in the containment will be greatly different. This environmental difference will change the migration mechanism and removal rate of aerosols. For example, aerosols will be exposed to high temperature, high pressure and low humidity conditions. When the aerosol concentration is very high and the particle size is large, gravity sedimentation and Brownian aggregation mechanisms dominate at this time; when the aerosol is in a high-temperature, high-pressure, high-humidity environment, even if the aerosol concentration is very high, the particle size is large, and the diffusion The removal rate is much greater than the amount of aerosol removed by gravity sedimentation and Brownian aggregation. Therefore, diffusion electrophoresis is the main removal mechanism of aerosols under this condition. Through the comparison of the above two thermal conditions, it can be found that the corresponding removal mechanisms of aerosols are also different depending on the thermal environment. Therefore, there is a lack of calculation models for aerosol behavior in this complex environment, and existing The model also lacks experimental verification, which brings great uncertainty to source term analysis and emergency planning zone division after serious accidents. Therefore, it is necessary to conduct experimental research on the aerosol removal mechanism under high temperature, pressure, and humidity conditions to obtain experimental data and refined prediction models of aerosol behavior in the containment under severe accident conditions.

Whether it is real-time monitoring of aerosol characteristics within the containment or experimental research on the behavior of aerosols in a simulated containment environment, high-precision sampling and analysis of aerosols in high-temperature and high-humidity environments is required. At present, aerosol sampling and analysis methods can be roughly summarized into the following three types: charged impact sampling method, mechanical filter sampling method, and optical sampling analysis method. Charged impact sampling is accomplished using a charged impactor. The particles entering the sampler are charged with a certain amount of charge by the charger, and then collected in a series of low-voltage impactors according to aerodynamic particle size classification. The induced electrical signal on the collection sensor is proportional to the mass concentration of the collected particles, so that the aerosol mass concentration in different particle size ranges can be analyzed. The conditions for use of the host are that the sample gas temperature is less than 60°C and the humidity range is 0-90% (water vapor cannot condense). It can work with an aerosol diluter to measure aerosol aerodynamic particle size quality under high-pressure and high-humidity conditions. Analysis of concentration, but in the aerosol dilution process, there are several branches for gas supply and pressure reduction, which makes the loop length larger and easily causes excessive loss of aerosol, so that the concentration of the aerosol sample gas after going through several branches to reduce pressure is measured. The deviation is large. The mechanical filter sampling method uses a metal filter holder and a filter membrane to achieve single sampling. After sampling, the filter membrane in the metal filter holder needs to be taken out, and the aerosol particle size and quantity should be analyzed by scanning electron microscopy or weighing method. This method cannot achieve continuous sampling, and because the filter membrane is relatively fragile, it is necessary to control the sampling pressure difference between the inlet and outlet of the metal filter membrane. However, this method can be used for aerosol sampling under high-pressure and high-humidity conditions. The last and most widely applicable real-time sampling method is optical sampling analysis. The optical sampling analysis method can achieve high-precision continuous sampling analysis. This method is not only used in the field of nuclear science, but also has high application in the field of medical protective product production. For example, it can analyze the aerosol removal efficiency of medical masks. The main equipment of the optical sampling analysis method is an optical particle counter. This equipment can irradiate particles with laser, measure the energy distribution of scattered light, and analyze the relationship between scattered light intensity and particle size to obtain the particle size distribution characteristics of the particles. When the optical particle counter measures particle size, it must ensure that the sampling gas flowing through the probe is stable at 5L/min. Under normal temperature and pressure conditions, the host computer of the optical particle counter and the probe work together to accurately control the flow, and then at high pressure Under certain conditions, especially in environments where high-pressure gas contains water vapor, high temperatures may cause damage to the host, while low temperatures will cause condensation of water vapor. Therefore, the host cannot control the sampling flow at the probe, and the optical particle counter cannot operate in a high-temperature, high-pressure, high-humidity environment. Real-time measurement of aerosols is achieved.

Based on the above aerosol sampling and measurement equipment, it can be found that although the charged impact sampler can perform aerosol sampling under high-pressure and high-humidity conditions, on the one hand, due to the existence of the decompression branch, the aerosol is sampled in the pipeline and decompression On the other hand, the sample aerosol needs to carry a charge, which causes some of the sample aerosol to be resuspended without charge after contacting the sampling pipe. The aerosol cannot be used for sampling, resulting in the loss of the sample. Therefore, it cannot meet the analysis of aerosol concentration in the containment under accident conditions. For the mechanical membrane sampling method, although it will not cause the loss of sampled samples, the analysis process is more cumbersome and continuous sampling cannot be carried out. This will add extra workload to the analysis of accident source items and cannot be monitored at all times. Concentration changes of accident aerosols.

Therefore, in order to solve the shortcomings of the optical particle counter in sampling and analysis under high temperature, high pressure and high humidity conditions, the present invention will provide a sampling and measurement solution that can enable the optical particle counter to be applied under high temperature, high pressure and high humidity conditions. The basic principle is: the sample aerosol with high temperature, pressure and humidity is cooled and decompressed through the series pressure reducing device and then enters the probe for measurement. The water vapor processing unit and fiber filter unit are used to make the gas composition and purity meet the control requirements, and pass The dual-point pressure sensor and temperature sensor cooperate with the logic control component to achieve precise control of the sampling flow rate at the probe.

Contents of the invention

The purpose of the present invention is to provide an aerosol sampling device and measurement method suitable for use in containment vessels under severe accident conditions that can solve the sampling and analysis deficiencies of optical particle counters under high temperature, high pressure and high humidity conditions.

The purpose of the present invention is achieved as follows:

The invention is an aerosol sampling device suitable for use in containment vessels under severe accident conditions. It is characterized by: including a container, a sampling pipe, a series pressure reducing device, an optical particle counter probe, a water reservoir, and a hot water exchange tank. The container is used for sampling The pipeline is connected to the optical particle counter probe. A serial pressure reducing device is installed on the sampling pipeline. The hot water exchange tank and the reservoir are connected through two pipes with different heights. A heat exchange tube is installed in the hot water exchange tank. One end of the heat exchange tube is optically The particle counter probe is connected to the sampling pipe, and the other end of the heat exchange pipe extends from the bottom of the hot water exchange tank, and a steam-water separator, fine filter, and flow controller are installed on the extended part.

An aerosol sampling device in a containment vessel of the present invention suitable for severe accident conditions may also include:

1. A check valve and fiber filter are installed on the heat exchange tube below the optical particle counter probe.

2. It also includes a first-third stop valve. A first path is set between the check valve and the fiber filter. The first stop valve is set on the first branch. A third stop valve is set on the heat exchange tube below the fiber filter. A second branch path is provided between the stop valve, the third stop valve and the fiber filter, and the second stop valve is provided on the second branch path.

3. A temperature sensor and a pressure sensor in the container are installed in the container. A sampling valve is installed in the sampling pipe between the container and the serial pressure reducing device. An optical sensor is installed in the sampling pipe between the series pressure reducing device and the optical particle counter probe. Measuring pressure sensors, optical measuring temperature sensors.

4. The series pressure reducing device includes a shell, in which a nozzle, a first buffer section, a buffer chamber, and a second buffer section are arranged in sequence. An automatic exhaust pipe is also arranged in the shell, and the automatic exhaust pipe extends to Outside the shell, an automatic exhaust valve is installed on the automatic exhaust pipe, and a pressure sensor is installed in the buffer chamber.

The present invention is a method for sampling and measuring aerosol in a containment vessel under severe accident conditions. It is characterized by heating the sampling pipe so that the steam does not condense in the sampling pipe, and heating the probe of the optical particle counter so that the probe can work properly. The temperature is greater than the temperature of the sample gas to prevent steam condensation; turn on the pressure sensor in the container, the optical measurement pressure sensor, the temperature sensor in the container, the optical measurement temperature sensor, the flow controller, and open the sampling valve. The sample gas passes through the series pressure reducing device to cool down. The pressure is reduced and flows through the optical measurement pressure sensor and the optical measurement temperature sensor in turn. When the sample gas flows through the optical particle counter probe, the aerosol quantity and mass concentration in the sample gas are obtained by measuring the scattering intensity of the light; after the measurement is completed, After the sample gas passes through the fiber filter and heat exchange tube, clean, dry, non-condensable gas remains, and finally flows through the flow controller and is discharged into the atmosphere.

An aerosol sampling and measurement method in a containment vessel suitable for severe accident conditions according to the present invention may also include:

1. During the aerosol sampling and measurement process, the mixed gas flow rate passing through the optical particle counter probe reaches a predetermined value by controlling the opening of the flow controller, that is, through the parameters of the temperature sensor in the container and the pressure sensor in the container close to the sampling pipe. Calculate the steam share of the sample gas, and then determine the density value of the mixed gas at this time through the thermal parameters measured by the optical pressure sensor and the optical temperature sensor. Combined with the non-condensable gas flow measured by the downstream flow controller, the flow rate is obtained. Through the mixed gas flow of the probe, the flow controller adjusts and controls the non-condensable gas flow in real time to ensure that the flow at the optical probe meets the measurement requirements.

The advantages of the present invention are:

1. It solves the current shortcomings of sampling in high temperature and high humidity environments, and can operate stably and efficiently for a long time to meet the sampling and analysis work of aerosols in containment under accident conditions.

2. The use of serial pressure reducing devices can achieve thermal aerosol pressure reduction under minimal or even non-destructive conditions.

3. The use of dual-point parameter measurement technology makes the aerosol sampling flow control more accurate.

4. The use of fiber filters can achieve aerosol removal under high temperature and high pressure conditions, and due to the design of the purge circuit, the difficulty of removing aerosol deposits in the experimental equipment and tube walls is simplified.

Description of drawings

Figure 1 is a schematic structural diagram of the present invention;

Figure 2 is a schematic diagram of the series pressure reducing device.

Detailed ways

The present invention will be described in more detail below with reference to the accompanying drawings and examples:

With reference to Figures 1-2, the present invention provides an aerosol sampling method and high-precision measurement technology under the condition that the container is at high temperature and high pressure and contains a large amount of water vapor. The sampling and measurement circuit consists of the temperature sensor in the container 1, the pressure sensor in the container 2, the serial pressure reducing device 4, the optical measurement pressure sensor 5, the optical measurement temperature sensor 6, the temperature controller 20, the probe 7 of the optical particle counter and the host 8 , fiber filter unit 9, 10, 11, 12, 13, water vapor treatment unit 14, 15, 16, 17, flow controller 18, logic control component 19 and container 21, and are connected through pipelines. Install sampling valve 3 at the relevant position of the pipeline. Through the series connection of the above units, the high-temperature and high-pressure sample gas in the container can be decompressed without loss through the series pressure reduction device and then enter the probe for analysis of aerosol concentration. Since the working environment of the flow controller is normal temperature and pressure, and the flow rate of air-water vapor mixed gas cannot be measured, the sample gas needs to be cooled down first after flowing through the probe. In order to meet the cooling needs, the corresponding water vapor is designed Processing unit, which can cool down the high-temperature sample gas. In order to prevent the aerosol deposited during steam cooling from hindering the continued inflow of the sample gas and affecting the performance of the steam cooling unit and the reliable operation of the flow controller, the aerosol must be removed before the sample gas flows through the water vapor treatment unit. removal work, but because the aerosol at this time is in a hot environment containing a large amount of water vapor, ordinary glass fiber filters cannot meet the working parameter requirements, so fluffy metal fiber filters are used, and according to the characteristics of the metal fiber filters, in order to ensure For long-term reliable operation of the filter, a purge circuit is designed at the inlet and outlet of the fiber filter.

The basic principle of the aerosol sampling and measurement loop is as follows: the high-temperature and high-pressure sampling gas in the container passes through the series pressure reducing device and becomes a high-temperature and low-pressure sample gas, which can meet the measurement needs of the optical measurement probe, and the aerosol particles are measured through the optical probe. Measurement of diameter distribution and concentration. The measured sample gas removes aerosols through a fiber filter and then enters the water vapor processing unit. The main function of the water vapor processing unit is to cool and separate the water vapor in the mixed sample gas to meet the back-end requirements. Flow controller usage requirements. The remaining non-condensable gas after passing through the water vapor treatment unit enters the flow controller, and is measured and fed back by the flow controller to control the sampling flow rate. In order to ensure that the flow rate at the optical probe meets the measurement requirements, dual-point thermal parameter measurement is used, that is, high-precision pressure sensors and temperature sensors are installed at the entrance of the optical probe and in the container, and the collected pressure signals and temperature signals are transmitted to the logic control component, and through the corresponding relationship between the temperature and pressure of the steam in the mixed gas in the container, the molar share of the steam in the mixed gas is determined. The molar share and the acquisition of the thermal parameters at the optical probe can be used to obtain the mixing density of the mixed gas, and then Combined with the non-condensable gas flow measured by the downstream flow controller, the mixed gas flow rate flowing through the probe can be obtained. The mixed gas flow rate can be set during the programming process of the logic control component, so that the flow controller can measure the non-condensable gas flow in real time. The gas flow is adjusted and controlled to ensure that the flow at the optical probe meets the measurement requirements.

According to the analysis results of serious accidents, it can be seen that the pressure inside the containment vessel after a serious accident is high, and under some working conditions it will exceed the operating conditions of optical measuring instruments, making monitoring impossible. Moreover, in order to meet the needs of passive operation and reduce aerosol loss, it is impossible to perform pressure reduction and flow control by setting a valve at the front end of the optical measuring instrument. Therefore, the present invention designs a series pressure reduction device to realize the sample in the container. Gas sampling, pressure reduction and flow regulation. In Figure 2, the series pressure reducing device 4 consists of a nozzle 24, buffer sections 26 and 27, a buffer chamber 26, a pressure sensor 23, an automatic exhaust valve 22 and a logic control component 19, which can achieve low loss of aerosol in the sample gas or even Cooling and decompression under non-destructive conditions. The sample gas is cooled and decompressed through the nozzle 24, and then enters the buffer chamber 26 through the buffer section 25, and is connected to the sampling pipeline through the buffer section 27. The buffer chamber 26 is provided with a pressure sensor 23 and an automatic exhaust valve 22. The pressure value of the sample gas in the buffer chamber can be controlled by controlling the opening of the automatic exhaust valve 22. After the sample gas passes through the tapering nozzle, the flow rate reaches a critical state. In order to achieve the decompression effect, a gradually expanding nozzle needs to be configured. In order to reduce the fluid oscillation problem of the sample gas after passing through the nozzle, a gas storage chamber is designed, and then the structure and Through process optimization, the gradually expanding nozzle and the gas storage chamber are combined to form the buffer chamber 26 in Figure 2. In order to ensure that the loss of aerosol is minimized when the sample gas flows through the series pressure reducing device, the geometry of the gas storage chamber is designed to be the same as the airflow field ejected from the gradually expanding nozzle. In order to facilitate the installation of components and reduce the cost of the equipment, Processing technology, buffer sections 25 and 27 are designed. According to the analysis of critical theory, when the upstream pressure changes, the flow value coming out of the nozzle will also change, causing the pressure in the buffer chamber 26 to increase. In order to solve the problem of the mismatch between the nozzle flow rate and the sampling flow rate of the flow controller, in the buffer chamber A pressure sensor 23 and an automatic exhaust valve 22 are installed in the design, and are connected to the logic control component 19, so that when the upstream pressure changes, the opening of the automatic exhaust valve can be adjusted through the pressure value set in the logic control component 19 degree to control the pressure value of the sample gas in the buffer chamber.

During the actual use of the sampling loop, the flow controller 18 is an extremely important part. According to its working conditions, the controller needs to work under normal temperature and pressure dry air conditions, and the gas passing through the controller cannot contain aerosols. Tiny particles such as these will cause irreversible damage to the flow controller 18 regardless of any usage conditions. In view of the usage conditions of the flow controller 18 and the parameter differences in the sample gas, fiber filter units 9, 10, 11, 12, 13 that remove aerosols and other tiny particles are designed and used to meet the requirements of the flow controller 18 drying at normal temperature and pressure. Water vapor treatment units 14, 15, 16, 17 used under air conditions.

The fiber filter units 9, 10, 11, 12, and 13 in Figure 1 are composed of a check valve 9, a fiber filter 11, and stop valves 10, 12, and 13. Since the sample aerosol in the loop is in a high-temperature and high-pressure state, a fiber filter is designed to remove it efficiently, that is, the removal of aerosol under high-temperature and high-pressure conditions is achieved through the combination of flange and fiber felt. However, due to the fact that some aerosols tend to accumulate on the surface of the fiber mat during actual use, these aerosols will hinder the flow rate of the sample gas. In order to solve this problem, a purge circuit is installed in the fiber filter unit, and the circuit valve 13 is closed, the automatic exhaust valves 10 and 12 are opened, and a purge air flow is added to make it enter the automatic exhaust valve 12 to reversely purge the fiber. filter so that the purge gas can carry the aerosol out of the loop from the automatic exhaust valve 10.

The water vapor treatment units 14, 15, 16, and 17 in Figure 1 are composed of a hot water exchange tank 14, a water reservoir 15, a steam-water separator 16, and a precision filter 17. By setting the sampling flow rate and the maximum thermal parameter of the sample gas, the required pipe length of the heat exchange tube is calculated, and the heat exchange tube is placed inside the hot water exchange tank 14 so that the cooling water inside the hot water exchange tank 14 completely submerges the heat exchange tube. . The hot water exchange tank 14 and the reservoir 15 are connected through two round pipes with different heights. When the sampling loop is working, the temperature of the sample gas is transferred to the cooling water in the hot water exchange tank 14, so that the cooling water temperature in the hot water exchange tank 14 It rises and forms a temperature difference with the water in the water storage tank 15. Under the action of the density difference, the water inside the two water tanks can flow naturally. After the sample gas passes through the hot water exchange tank 14, the water vapor will condense into water droplets, and then through the dual functions of the steam-water separator 16 and the precision filter 17, the water droplets in the sample gas will be removed, leaving only non-condensable gas.

The control unit in Figure 1 consists of two parts: a temperature controller 20 and a logic control component 19. The temperature controller 20 is used to control the temperature of the sampling pipeline before the sample gas passes through the probe. The logic control component 19 adopts a dual-point data acquisition method, and The opening degree of the flow controller 18 is controlled through an internal control program. The scheme and principle of flow control are as follows: First, in order to prevent the mixed sample gas from carrying small droplets at the probe of the optical particle counter, contaminating the probe lens and affecting the sampling accuracy, it is necessary to ensure that the sample gas passing through the probe is in a superheated state. The temperature parameters of the pipeline can be set by the temperature controller 20. Since the sample gas cannot be calculated through the optical measurement pressure sensor 5 and the optical measurement temperature sensor 6 after it is in a superheated state, the dual-point control idea is proposed, that is, through the temperature sensor in the container close to the sampling pipe. 1 and the pressure sensor 2 in the container to calculate the vapor share of the sample gas, and then determine the mixed gas density value at this time through the thermal parameters measured by the optical pressure sensor 5 and the optical temperature sensor 6, and then use the non-condensable gas The opening value of the flow controller 18 is calculated based on mass conservation to ensure that the sampling flow rate at the probe is satisfied.

As shown in Figure 1, the loop consists of an in-container temperature sensor 1, an in-container pressure sensor 2, a series pressure reducing device 4, an optical measurement pressure sensor 5, an optical measurement temperature sensor 6, a temperature controller 20, and a probe of an optical particle counter. 7 is composed of the host computer 8, high temperature and high pressure aerosol removal units 9, 10, 11, 12, 13, water vapor processing units 14, 15, 16, 17, flow controller 18, logic control component 19 and container 21, and through pipelines connect. Install sampling valves at relevant locations in the pipeline. Sensors 1, 2, 5, 6 and flow controller 18 are connected to the logic control component 19, and the collection and control signals can be connected to the logic control component 19, so that the sampling loop is connected as a whole.

According to the flow chart of aerosol sampling and measurement technology in containment suitable for severe accident conditions shown in Figure 1, the overall working process is as follows. Turn on the temperature controller 20 and heat the sampling pipe so that the steam does not condense in the sampling pipe. The host 8 of the optical particle counter heats up the probe 7 of the optical particle counter so that the working temperature of the probe is greater than the temperature of the sample gas to prevent steam. condensation. Turn on the pressure sensors 2 and 5, the temperature sensors 1 and 6, the flow controller 18 and the logic control component 19, and prepare to control the sampling and mixing flow. Open the sampling valve 3 and the sample gas passes through the serial pressure reducing device 4 to be cooled and decompressed, and flows through the optical measurement pressure sensor 5 and the optical measurement temperature sensor 6 in sequence. When the sample gas flows through the probe of the optical particle counter, the number and mass concentration of aerosols in the sample gas can be obtained by measuring the scattering intensity of light. After the measurement is completed, the sample gas passes through the fiber filter units 9, 10, 11, 12, 13 and the water vapor treatment unit 14, 15, 16, 17. Only clean, dry non-condensable gas remains, and finally flows through the flow controller 18 and is discharged. into the atmosphere. In aerosol sampling and measurement technology, it is necessary to control the opening of the flow controller 18 so that the mixed gas flow rate passing through the optical particle counter probe 7 reaches a predetermined value, that is, through the temperature sensor 1 in the container and the pressure sensor 2 in the container close to the sampling pipe. The parameter transfer allows the logic control component 19 to calculate the vapor share of the sample gas, and then determine the mixed gas density value at this time through the thermal parameters measured by the optical measurement pressure sensor 5 and the optical measurement temperature sensor 6, and then combine it with the downstream flow controller The measured non-condensable gas flow rate can be used to obtain the mixed gas flow rate flowing through the probe. The logic control component can set the mixed gas flow rate during the programming process, so that the flow controller can adjust and adjust the non-condensable gas flow rate in real time. Control to ensure that the flow rate at the optical probe meets the measurement requirements.

As shown in Figure 2, the series pressure reducing device 4 consists of a nozzle 24, buffer sections 26 and 27, a buffer chamber 26, a pressure sensor 23, an automatic exhaust valve 22 and a logic control component 19. The nozzle 24, the buffer sections 26 and 27 and the buffer chamber 26 are integrated processing equipment, and two branches are reserved at the side end of the buffer chamber 26, one of which is fixed with a threaded connection to the pressure sensor 23, and the other branch is connected through a straight-through and automatic Exhaust valve 22 is connected. The sample gas is cooled and decompressed through the nozzle 24, and then enters the buffer chamber 26 through the buffer section 25, and is connected to the sampling pipeline through the buffer section 2. The buffer chamber 26 is provided with a pressure sensor 23 and an automatic exhaust valve 22. The opening of the automatic exhaust valve 22 can be controlled through the set value in the logic control component 19 to control the pressure value of the sample gas in the buffer chamber. The serial pressure reducing device 4 can achieve temperature reduction and pressure reduction under low loss conditions of aerosol in the sample gas.

As shown in Figure 1, the fiber filter unit 9, 10, 11, 12, 13 is composed of a check valve 9, a fiber filter 11 and a stop valve 10, 12, 13, and each component is connected to the pipeline through flanges. Since the sample aerosol in the loop is in a high-temperature and high-pressure state, a fiber filter is designed to remove it efficiently, that is, the removal of aerosol under high-temperature and high-pressure conditions is achieved through the combination of flange and fiber felt. However, due to the fact that some aerosols tend to accumulate on the surface of the fiber mat during actual use, these aerosols will hinder the flow rate of the sample gas. In order to solve this problem, a purge circuit is installed in the fiber filter unit, and the circuit valve 13 is closed, the automatic exhaust valves 10 and 12 are opened, and a purge air flow is added to make it enter the automatic exhaust valve 12 to reversely purge the fiber. filter so that the purge gas can carry the aerosol out of the loop from the automatic exhaust valve 10.

As shown in Figure 1, the water vapor treatment units 14, 15, 16, and 17 are composed of a hot water exchange tank 14, a water reservoir 15, a steam-water separator 16, and a precision filter 17. The hot water exchange tank 14 and the reservoir 15 are connected through pipes and flanges. The heat exchange pipes in the hot water exchange tank 14 are connected to the wall of the hot water exchange tank 14 through the through-plate clamps. The heat exchange pipes are connected to the steam-water separator 16 and The precision filters 17 are directly connected to each other through ferrules and external threads. During use, the water vapor processing units 14, 15, 16, and 17 calculate the required length of the heat exchange tube by setting the sampling flow rate and the maximum thermal parameter of the sample gas, and install the heat exchange tube inside the hot water exchange tank 14 So that all the cooling water inside the hot water exchange tank 14 submerges the heat exchange tubes. The hot water exchange tank 14 and the reservoir 15 are connected through two round pipes with different heights. When the sampling loop is working, the temperature of the sample gas is transferred to the cooling water in the hot water exchange tank 14, so that the cooling water temperature in the hot water exchange tank 14 It rises and forms a temperature difference with the water in the water storage tank 15. Under the action of the density difference, the water inside the two water tanks can flow naturally. After the sample gas passes through the hot water exchange tank 14, the water vapor will condense into water droplets, and then through the dual functions of the steam-water separator 16 and the precision filter 17, the water droplets in the sample gas will be removed, leaving only non-condensable gas.

The control unit in Figure 1 consists of two parts: a temperature controller 20 and a logic control component 19. The temperature controller 20 is used to control the temperature of the sampling pipeline before the sample gas passes through the probe. The logic control component 19 adopts a dual-point data acquisition method, and The control program independently developed in-house controls the opening degree of the flow controller 18. The temperature controller 20 is composed of a PID temperature controller, a heating tape, a pipe outer surface contact thermocouple and a pipe insulation layer. The temperature value can be set during use, and the heating power of the heating belt outside the sampling pipe is controlled through feedback from the thermocouple in contact with the outer surface of the sampling pipe, so that the temperature on the outer surface of the pipe is consistent with the set temperature. The logic control component 19 is composed of a temperature acquisition card, a current acquisition card, a current control card and an integrated controller, and each part is connected through a signal line. The scheme and principle of flow control implemented by the logic control component 19 are as follows: First, in order to prevent the mixed sample gas from carrying small droplets at the probe of the optical particle counter, contaminating the probe lens and affecting the sampling accuracy, it is necessary to ensure that the sample gas passing through the probe is in an overheated state. . The temperature parameters of the pipeline can be set by the temperature controller 20. Since the sample gas cannot be calculated through the optical measurement pressure sensor 5 and the optical measurement temperature sensor 6 after it is in a superheated state, the dual-point control idea is proposed, that is, through the temperature sensor in the container close to the sampling pipe. 1 and the pressure sensor 2 in the container to calculate the vapor share of the sample gas, and then determine the mixed gas density value at this time through the thermal parameters measured by the optical pressure sensor 5 and the optical temperature sensor 6, and then use the non-condensable gas The opening value of the flow controller 18 is calculated based on mass conservation to ensure that the sampling flow rate at the probe is satisfied.

Claims (5)

1. An aerosol sampling device in containment suitable for under severe accident condition, characterized by: the device comprises a container, a sampling pipeline, a serial pressure reducing device, an optical particle counter probe, a reservoir and a heat exchange water tank, wherein the container is connected with the optical particle counter probe through the sampling pipeline;

the serial pressure reducing device comprises a shell, wherein a nozzle, a first buffer section, a buffer chamber and a second buffer section are sequentially arranged in the shell, an automatic exhaust pipeline is further arranged in the shell, the automatic exhaust pipeline extends out of the shell, an automatic exhaust valve is arranged on the automatic exhaust pipeline, and a pressure sensor is arranged in the buffer chamber;

a check valve and a fiber filter are arranged on the heat exchange tube below the optical particle counter probe;

an optical measurement pressure sensor and an optical measurement temperature sensor are arranged on a sampling pipeline between the serial pressure reducing device and the optical particle counter probe;

the control unit is provided with a temperature controller and a logic control component;

the steam share of the sample gas is calculated by the logic control component through the parameter transmission of the temperature sensor in the container and the pressure sensor in the container, then the density value of the mixed gas is determined through the optical measurement pressure sensor and the thermal parameter measured by the optical measurement temperature sensor, and the mixed gas flow flowing through the probe is obtained by combining the non-condensable gas flow measured by the downstream flow controller.

2. An aerosol sampling device in a containment vessel adapted for use in severe accident conditions according to claim 1, wherein: the device also comprises a first stop valve, a third stop valve and a second branch between the third stop valve and the fiber filter, wherein the first branch is arranged between the check valve and the fiber filter, the first stop valve is arranged on the first branch, the third stop valve is arranged on the heat exchange tube below the fiber filter, and the second stop valve is arranged on the second branch.

3. An aerosol sampling device in a containment vessel adapted for use in severe accident conditions according to claim 1 or 2, wherein: the container is internally provided with a temperature sensor in the container and a pressure sensor in the container, and a sampling valve is arranged on a sampling pipeline between the container and the serial pressure reducing device.

4. The aerosol sampling and measuring method suitable for the containment under the severe accident condition is characterized by comprising the following steps of: heating the sampling pipe by adopting the aerosol sampling device in the containment suitable for severe accident conditions, so that steam is not condensed in the sampling pipe, and heating the probe of the optical particle counter to ensure that the working temperature of the probe is higher than the temperature of sample gas and prevent the steam from condensing; opening a pressure sensor, an optical measurement pressure sensor, a temperature sensor, an optical measurement temperature sensor and a flow controller in the container, opening a sampling valve, enabling sample gas to pass through a serial pressure reducing device, reducing temperature and pressure, enabling the sample gas to sequentially flow through the optical measurement pressure sensor and the optical measurement temperature sensor, and obtaining the quantity and the mass concentration of aerosol in the sample gas through the scattering intensity of measurement light when the sample gas flows through an optical particle counter probe; the measured sample gas is filtered by a fiber filter and a heat exchange tube, clean and dry non-condensable gas is left, and finally the sample gas flows through a flow controller and is discharged into the atmosphere.

5. The method for sampling and measuring aerosol in a containment vessel suitable for use in severe accident conditions according to claim 4, wherein: in the aerosol sampling and measuring process, the opening of the flow controller is controlled to enable the flow of the mixed gas passing through the probe of the optical particle counter to reach a preset value, namely, the steam share of the sample gas is calculated through parameters of a temperature sensor in a container close to a sampling pipeline and a pressure sensor in the container, then the density value of the mixed gas at the moment is determined through the optical measurement pressure sensor and the thermal parameter measured by the optical measurement temperature sensor, and then the flow of the mixed gas flowing through the probe is obtained by combining the flow of the non-condensable gas measured by the downstream flow controller, and the flow controller regulates and controls the flow of the non-condensable gas in real time, so that the flow of the optical probe is ensured to meet the measurement requirement.