An apparatus for cold start of silver loaded zeolite and method of use thereof

Abstract

The application provides a device for cold start of silver-loaded zeolite and a use method thereof, and belongs to the technical field of research on the filtering characteristics of silver-loaded zeolite on gaseous methyl iodine. The device solves the problem that the existing cold start scheme is not suitable for silver-loaded zeolite and cannot study the adsorption characteristics of silver-loaded zeolite on methyl iodine in the cold start stage. The device comprises a carrier gas system, a methyl iodine gas distribution system, a silver-loaded zeolite column assembly, a pipeline carrier gas flow path and a sampling and measuring system. The carrier gas system comprises a nitrogen source and a steam generator. The output end of the nitrogen source is connected with the input end of the steam generator. The methyl iodine gas distribution system comprises a gas cylinder. The silver-loaded zeolite column assembly comprises a silver-loaded zeolite bed. The mixed gas output by the steam generator and the methyl iodine gas output by the gas cylinder are mixed and transported to the silver-loaded zeolite column assembly through the main flow path of the pipeline carrier gas flow path. The silver-loaded zeolite column assembly is connected with the sampling and measuring system. The device is mainly used for testing the adsorption characteristics of silver-loaded zeolite.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of research on the filtering characteristics of gaseous methyl iodine based on silver-loaded zeolite in nuclear power plants, and particularly relates to a device for cold-state starting of silver-loaded zeolite and a use method thereof. BACKGROUND

[0002] When a severe accident occurs in a nuclear power plant reactor, a large amount of coolant will be injected into the containment to cool the reactor core temperature. These coolants will absorb a large amount of reactor heat in a very short time and form steam in the containment with low pressure. At the same time, after the reactor core is melted, the molten core will break the pressure vessel and fall into the pit and react with the concrete bottom plate to produce a large amount of non-condensable gas. The generation of these steam and non-condensable gas in the containment will cause the temperature and pressure in the containment to rise, and eventually may cause the containment to be damaged due to the internal pressure exceeding its pressure limit, causing radioactive substances to leak into the environment and causing serious radioactive pollution, endangering public safety. To protect the integrity of the containment, active discharge and pressure relief of the containment are needed at the first time of the accident. However, due to the presence of a large amount of radioactive substances in the containment, the discharged gas needs to be filtered to reduce the radioactive pollution discharged into the environment.

[0003] Currently, silver-loaded zeolite has been considered as a new material for filtering the main methyl iodine gas in radioactive substances. The adsorption performance of silver-loaded zeolite on methyl iodine gas is related to multiple parameters. In order to explore its adsorption performance, relevant methods and devices need to be designed.

[0004] The existing Chinese invention patent with publication number CN101238275B proposes a heating system for a liquid delivery system, which structure includes at least one first heating device for thawing liquid, and at least one filter heating device for heating the filter for filtering liquid, connecting wires, etc. This invention patent can more quickly heat the exhaust gas purification catalyst of an internal combustion engine to a working preparation state when the temperature is below the freezing point. The system disclosed in this invention patent can well complete the heating function of the liquid delivery system. However, compared with the present invention, although both belong to heating a certain device or part, the present invention can heat and insulate the heated part at the same time, keeping the temperature constant at a certain temperature. The invention patents with publication numbers CN113847621A and CN111042882A provide cold-state starting methods or systems in some fields, but few patents are related to the cold-state starting of silver zeolite beds. Due to the unique structure of silver zeolite, these cold-state starting methods and systems are not applicable.

[0005] In summary, the existing cold start scheme and heating system are not helpful for studying the adsorption characteristics of silver-loaded zeolite on methyl iodide in the cold start stage. SUMMARY

[0006] Therefore, the present application aims to provide a device for cold start of silver-loaded zeolite and a method for using the same to solve the problem that the existing cold start scheme is not suitable for silver-loaded zeolite and cannot study the adsorption characteristics of silver-loaded zeolite on methyl iodide in the cold start stage.

[0007] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0008] A device for cold start of silver-loaded zeolite, comprising a carrier gas system, a methyl iodide gas distribution system, a silver-loaded zeolite column assembly, a pipeline carrier gas flow path, and a sampling and measuring system, wherein the carrier gas system comprises a nitrogen source and a steam generator, the output end of the nitrogen source is connected to the input end of the steam generator, the methyl iodide gas distribution system comprises a gas cylinder, the silver-loaded zeolite column assembly comprises a silver-loaded zeolite bed, the mixed gas output by the steam generator is mixed with the methyl iodide gas output by the gas cylinder and transported to the silver-loaded zeolite column assembly through the main flow path of the pipeline carrier gas flow path, and the silver-loaded zeolite column assembly is connected to the sampling and measuring system.

[0009] Furthermore, the silver-loaded zeolite column assembly further comprises an insulation layer and an incubator, the silver-loaded zeolite bed is arranged in the insulation layer, and the insulation layer is arranged in the incubator.

[0010] Furthermore, the gas inlet of the silver-loaded zeolite bed is connected to the first three-way valve through the main flow path, and the gas outlet of the silver-loaded zeolite bed is connected to the third three-way valve through the main flow path.

[0011] Furthermore, a plurality of thermocouples are arranged at the side end of the silver-loaded zeolite bed.

[0012] Furthermore, a pressure relief valve, a flow meter, and an adjusting valve are arranged in the main flow path between the output end of the nitrogen source and the output end of the steam generator along the gas conveying direction, and a pressure gauge is arranged on the steam generator.

[0013] Furthermore, an electric heating device is arranged in the steam generator.

[0014] Furthermore, the sampling and measuring system comprises a condenser and a gas chromatograph connected to each other, a second three-way valve is arranged on the main flow path between the first three-way valve and the third three-way valve, and the second three-way valve is connected to the condenser.

[0015] Furthermore, a first shut-off valve is arranged at the bypass flow path connection port of the first three-way valve and the pipeline carrier gas flow path, and a second shut-off valve is arranged at the connection port of the bypass flow path and the third three-way valve.

[0016] Further, the output ends of the first and second stop valves are both provided with condensate measuring instruments.

[0017] A method for using a device for cold start of silver-loaded zeolite, comprising the following steps:

[0018] Step 1: turn on the steam generator and the thermostat, and set the liquid phase temperature in the steam generator and the temperature in the thermostat to predetermined values;

[0019] Step 2: start the nitrogen source, pass nitrogen into the steam generator, and discharge through the bypass flow path;

[0020] Step 3: after the temperature of the steam generator reaches the set value, increase the flow rate of the nitrogen source to the set value, and connect the condensate measuring instruments after the first and second stop valves;

[0021] Step 4: after confirming that the working conditions are correct, open the bypass flow path through the first and third three-way valves, open the flow path to the third three-way valve through the second three-way valve, close the first stop valve, form a flow path from the steam generator, the first three-way valve, the second three-way valve, the third three-way valve and the second stop valve, open the gas cylinder, and measure the methyl iodide concentration at the inlet of the silver-loaded zeolite bed through the bypass flow path;

[0022] Step 5: switch the carrier gas to the silver-loaded zeolite bed through the first three-way valve, record the temperature change of the silver-loaded zeolite bed, and measure the methyl iodide gas concentration at the outlet of the silver-loaded zeolite bed;

[0023] Step 6: gradually increase the temperature of the thermostat from the cold state, and repeat the above steps;

[0024] Step 7: after the test is completed, switch the carrier gas to the bypass flow path, then sequentially close the gas cylinder, the steam generator and the nitrogen source, and finally turn off the power of the thermostat.

[0025] Compared with the prior art, the present application has the following advantages:

[0026] 1. The present application can well study the adsorption characteristics of methyl iodide in the cold start stage of silver-loaded zeolite, and clearly reflect the change law of the bed temperature and the methyl iodide adsorption efficiency with time after the carrier gas is switched to the silver-loaded zeolite bed, so as to well determine the adsorption efficiency of the silver-loaded zeolite at different temperatures.

[0027] 2. The present application can provide good data support for studying the adsorption relationship between silver-loaded zeolite and other parameters, and ensure that the ventilation process does not produce steam condensation phenomenon in the process of other characteristic research. BRIEF DESCRIPTION OF DRAWINGS

[0028] The accompanying drawings, which form a part of the specification, are included to provide a further understanding of the application and are incorporated herein for explanation by illustrating a preferred embodiment of the present application. The present application is best described, by way of example, with reference to the accompanying drawings, in which:

[0029] Figure 1 Structure diagram of a device for cold start of silver-loaded zeolite according to the present application;

[0030] Figure 2 Structure diagram of a steam generator according to the present application;

[0031] Figure 3 Structure diagram of a silver-loaded zeolite column;

[0032] Figure 4 Distribution diagram of a pipeline carrier gas flow path.

[0033] 1-nitrogen source, 2-pressure relief valve, 3-flow meter, 4-pressure gauge, 5-gas cylinder, 6-heat preservation layer, 7-first three-way valve, 8-first stop valve, 9-condenser, 10-gas chromatograph, 11-second three-way valve, 12-second stop valve, 13-third three-way valve, 14-constant temperature box, 15-silver-loaded zeolite bed, 16-steam generator, 17-electric heating device, 18-regulating valve, 21-gas inlet, 22-thermocouple, 23-gas outlet, 24-main flow path, 25-bypass flow path. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict, and the described embodiments are only part of the embodiments of the present application, but not all the embodiments.

[0035] Specific implementation one: see Figures 1-4The embodiment is characterized in that: the device comprises a carrier gas system, a methyl iodide gas distribution system, a silver-loaded zeolite column assembly, a pipeline carrier gas flow path, and a sampling and measuring system; the carrier gas system comprises a nitrogen source 1 and a steam generator 16, the output end of the nitrogen source 1 is connected to the input end of the steam generator 16, the methyl iodide gas distribution system comprises a gas cylinder 5, the silver-loaded zeolite column assembly comprises a silver-loaded zeolite bed 15, the mixed gas output by the steam generator 16 is mixed with the methyl iodide gas output by the gas cylinder 5 and then transported to the silver-loaded zeolite column assembly through a main flow path 24 of the pipeline carrier gas flow path, the silver-loaded zeolite column assembly is connected to the sampling and measuring system, the gas inlet 21 of the silver-loaded zeolite bed 15 is connected to the first three-way valve 7 through the main flow path 24, the gas outlet 23 of the silver-loaded zeolite bed 15 is connected to the third three-way valve 13 through the main flow path 24, a first stop valve 8 is arranged at the connection port of the first three-way valve 7 and the bypass flow path 25 of the pipeline carrier gas flow path, and a second stop valve 12 is arranged at the connection port of the third three-way valve 13 and the bypass flow path 25.

[0036] Before use, the steam generator 16 and the constant-temperature box 14 are turned on, the liquid phase temperature in the steam generator 16 and the temperature in the constant-temperature box 14 are set to predetermined values, then the nitrogen source 1 is started, nitrogen is introduced into the steam generator 16 and discharged through the bypass flow path 25, when the temperature of the steam generator 16 reaches the set value, the flow rate of the nitrogen source 1 is also increased to a set value, after the working condition is confirmed to be correct, the first three-way valve 7 and the third three-way valve 13 are connected to the bypass flow path 25, the second three-way valve 11 is connected to the passage leading to the third three-way valve 13, the first stop valve 8 is closed, the passage formed by the steam generator 16, the first three-way valve 7, the second three-way valve 11, the third three-way valve 13 and the second stop valve 12 is formed, the gas cylinder 5 is opened, and the methyl iodide concentration at the inlet of the silver-loaded zeolite bed 15 is measured through the bypass flow path 25, the carrier gas is switched to the silver-loaded zeolite bed 15 through the first three-way valve 7, the temperature change of the silver-loaded zeolite bed 15 is recorded, and the methyl iodide gas concentration at the gas outlet 23 of the silver-loaded zeolite bed 15 is measured, the temperature of the constant-temperature box 14 is gradually increased from the cold state, the above steps are repeated, after the test is completed, the carrier gas is switched to the bypass flow path 25, then the gas cylinder 5, the steam generator 16 and the nitrogen source 1 are sequentially closed, and finally the power supply of the constant-temperature box 14 is turned off. The device can clearly reflect the change law of the bed temperature and the methyl iodide adsorption efficiency with time after the carrier gas is switched to the silver-loaded zeolite bed, thereby the adsorption efficiency of the silver-loaded zeolite at different temperatures can be well determined.

[0037] Specific implementation method two: refer to Figures 1-4The main flow path 24 between the output end of the nitrogen source 1 and the output end of the vapor generator 16 is sequentially provided with a pressure relief valve 2, a flow meter 3 and an adjusting valve 18 along the gas conveying direction, the vapor generator 16 is provided with a pressure gauge 4, the sampling and measuring system comprises a condenser 9 and a gas chromatograph 10 connected with each other, the second three-way valve 11 is arranged on the main flow path 24 between the first three-way valve 7 and the third three-way valve 13, the second three-way valve 11 is connected with the condenser 9, and the pipelines are connected between the systems. In the normal working state of the device, high-purity nitrogen gas from the high-purity nitrogen source 1 passes through the pipeline, flows through the pressure relief valve 2, the flow meter 3 and then the adjusting valve 18 to enter the inside of the vapor generator 16, and the high-purity nitrogen gas enters from the bottom of the generator and leaves from the upper liquid surface. The mixed gas leaving the vapor generator 16 is mixed with methyl iodine gas from the high-pressure cylinder 5 through the pipeline and continues to pass backward. When the stop valve 8 and the stop valve 12 are in the closed state, the three-way valve 13 connects the main flow path 24, the sampling gas passes through the silver zeolite column 15, enters the condenser 9 through the three-way valve 11, is condensed, enters the gas chromatograph 10 and is finally tested.

[0038] Specific embodiment three: see Figures 1-4 In this embodiment, the vapor generator 16 is provided with an electric heating device 17 and has a temperature control function, and the pressure of the internal space of the vapor can be monitored through the pressure gauge 4. The vapor generator 16 is filled with deionized water, and high-purity nitrogen gas enters from the bottom of the generator and passes through the liquid phase in the form of bubbles. In this process, because the initial vapor partial pressure in the bubbles is low, the vapor will transfer from the gas-liquid interface to the inside of the bubbles and reach a mass transfer equilibrium state before leaving the liquid surface. Based on this principle, the vapor mass fraction in the carrier gas can be realized by adjusting the nitrogen flow and the heating power of the evaporator.

[0039] The pressure relief valve 2 can control the gas flow pressure flowing into the pipeline carrier gas flow path, ensure the safe operation of the device, the adjusting valve 18 can adjust the gas flow flowing into the pipeline carrier gas flow path, the flow meter 3 can measure the gas flow flowing into the pipeline carrier gas flow path, thereby providing a reference for the gas flow control flowing into the pipeline carrier gas flow path, and the methyl iodine gas is supplied by the high-pressure cylinder 5. The high-pressure cylinder 5 is filled with 3000ppm high-concentration standard methyl iodine gas.

[0040] Specific embodiment four: see Figures 1-4The embodiment is described, the silver-loaded zeolite column assembly further comprises a heat preservation layer 6 and an incubator 14, the silver-loaded zeolite bed 15 is arranged in the heat preservation layer 6, the heat preservation layer 6 is arranged in the incubator 14, the silver-loaded zeolite column 15 is a cylindrical structure with an inner diameter of 25 mm, the top is a gas inlet 21, the bottom is a gas outlet 23, and the inside allows the packing height range to be 0-12 mm. Three armored thermocouples 22 with a diameter of 1 mm are arranged along the height direction of the column body for measuring the temperature changes of the upper gas space and the zeolite bed layer, the silver-loaded zeolite column 15 is integrally installed in the incubator 14, the temperature can be controlled, adjusted and monitored through the incubator 14, the inlet and outlet methyl iodine gas concentrations of the silver-loaded zeolite column 15 are measured and analyzed through a GC-2010 type gas chromatograph 10, when the carrier gas contains water vapor, the sampling gas is first passed through a condenser 9 to remove the water vapor in the carrier gas before entering the chromatograph, at the same time, the steam fraction in the carrier gas can be checked by measuring the condensate rate, and the test is carried out under the condition that the absolute pressure of the silver-loaded zeolite column 15 is 0.5 MPa, the gas temperature at the inlet of the silver-loaded zeolite column 15 is 145 DEG C, and the superheat is 10 DEG C, and the initial condition of the silver-loaded zeolite column 15 is close to normal temperature and pressure.

[0041] Specific implementation method five: see Figures 1-4 The embodiment is described, the output ends of the first stop valve 8 and the second stop valve 12 are both provided with condensate measuring instruments for measuring the condensate amount.

[0042] Specific implementation method six: see Figures 1-4 The embodiment is described, a method for using a device for cold start of a silver-loaded zeolite, which comprises the following steps:

[0043] Step 1: turn on the steam generator 16 and the incubator 14, and set the liquid phase temperature in the steam generator 16 and the temperature in the incubator 14 to a predetermined value;

[0044] Step 2: start the nitrogen source 1, pass the nitrogen into the steam generator 16, and discharge it through the bypass flow path 25;

[0045] Step 3: after the temperature of the steam generator 16 reaches the set value, also increase the flow rate of the nitrogen source 1 to a set value, and connect the condensate measuring instruments after the first stop valve 8 and the second stop valve 12;

[0046] Step 4: after confirming that the working conditions are correct, connect the first three-way valve 7 and the third three-way valve 13 to the bypass flow path 25, connect the second three-way valve 11 to the path leading to the third three-way valve 13, close the first stop valve 8, form a path from the steam generator 16, the first three-way valve 7, the second three-way valve 11, the third three-way valve 13 and the second stop valve 12, open the gas cylinder 5, and measure the methyl iodine concentration at the inlet of the silver-loaded zeolite bed 15 through the bypass flow path 25;

[0047] Step 5: Switch the carrier gas to the silver-loaded zeolite bed 15 through the first three-way valve 7, record the temperature change of the silver-loaded zeolite bed 15, and measure the methyl iodide gas concentration at the outlet 23 of the silver-loaded zeolite bed 15 at the same time;

[0048] Step 6: Gradually increase the temperature of the thermostat 14 from the cold state, and repeat the above steps;

[0049] Step 7: After the test is completed, switch the carrier gas to the bypass flow path 25, then sequentially close the gas cylinder 5, the steam generator 16, and the nitrogen source 1, and finally turn off the power supply of the thermostat 14.

[0050] The above disclosed embodiments of the present application are only used to help explain the present application. The embodiments do not describe all the details, nor limit the present application to the specific embodiments described. Many modifications and variations can be made in light of the content of the present specification. The present specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present application, so that those skilled in the art can well understand and utilize the present application.

Claims

1. A device for cold starting of silver-loaded zeolite, characterized in that: The invention comprises a carrier gas system, a methyl iodide gas distribution system, a silver-loaded zeolite column assembly, a pipeline carrier gas flow path and a sampling and measuring system. The carrier gas system comprises a nitrogen source (1) and a steam generator (16). The output end of the nitrogen source (1) is connected to the input end of the steam generator (16). The methyl iodide gas distribution system comprises a gas cylinder (5). The silver-loaded zeolite column assembly comprises a silver-loaded zeolite bed (15). The mixed gas output by the steam generator (16) and the methyl iodide gas output by the gas cylinder (5) are mixed and transported to the silver-loaded zeolite column assembly through a main flow path (24) of the pipeline carrier gas flow path. The silver-loaded zeolite column assembly is connected to the sampling and measuring system.

2. The device for cold starting of silver-loaded zeolite according to claim 1, characterized in that: The silver-loaded zeolite column assembly further comprises a heat-insulating layer (6) and a thermostatic box (14); the silver-loaded zeolite bed (15) is arranged in the heat-insulating layer (6), and the heat-insulating layer (6) is arranged in the thermostatic box (14).

3. The device for cold starting of silver-loaded zeolite according to claim 2, characterized in that: The air inlet (21) of the silver-loaded zeolite bed (15) is connected to the first three-way valve (7) via a main flow path (24), and the air outlet (23) of the silver-loaded zeolite bed (15) is connected to the third three-way valve (13) via a main flow path (24).

4. The device for cold starting of silver-loaded zeolite according to claim 2, characterized in that: A plurality of thermocouples (22) are provided at the side ends of the silver-loaded zeolite bed (15).

5. The device for cold starting of silver-loaded zeolite according to claim 1, characterized in that: A main flow path (24) between the output end of the nitrogen source (1) and the output end of the steam generator (16) is provided with a pressure relief valve (2), a flow meter (3) and a regulating valve (18) in sequence along the gas delivery direction, and a pressure gauge (4) is provided on the steam generator (16).

6. The device for cold starting of silver-loaded zeolite according to claim 5, characterized in that: An electric heating device (17) is provided in the steam generator (16).

7. The device for cold starting of silver-loaded zeolite according to claim 3, characterized in that: The sampling and measuring system comprises a condenser (9) and a gas chromatograph (10) connected to each other, a second three-way valve (11) is provided on the main flow path (24) between the first three-way valve (7) and the third three-way valve (13), and the second three-way valve (11) is connected to the condenser (9).

8. The device for cold starting of silver-loaded zeolite according to claim 3, characterized in that: A first stop valve (8) is provided at the connection port between the first three-way valve (7) and the bypass flow path (25) of the pipeline carrier gas flow path, and a second stop valve (12) is provided at the connection port between the third three-way valve (13) and the bypass flow path (25).

9. The device for cold starting of silver-loaded zeolite according to claim 8, characterized in that: The output ends of the first stop valve (8) and the second stop valve (12) are both equipped with condensate measuring instruments.

10. A method for using the device for cold starting of silver-loaded zeolite according to claim 1, characterized in that: It includes the following steps: Step 1: Turn on the steam generator (16) and the thermostat (14), and set the liquid phase temperature in the steam generator (16) and the temperature in the thermostat (14) to predetermined values; Step 2: Start the nitrogen source (1), pass nitrogen into the steam generator (16), and discharge it through the bypass flow path (25); Step 3: When the temperature of the steam generator (16) reaches the set value, the flow rate of the nitrogen source (1) is also increased to the set value, and at the same time, a condensate measuring instrument is connected after the first stop valve (8) and the second stop valve (12); Step 4: After the working conditions are confirmed to be correct, the first three-way valve (7) and the third three-way valve (13) are connected to the bypass flow path (25), the second three-way valve (11) is connected to the path flowing to the third three-way valve (13), the first stop valve (8) is closed, and a path is formed by the steam generator (16), the first three-way valve (7), the second three-way valve (11), the third three-way valve (13) and the second stop valve (12), the gas cylinder (5) is opened, and the methyl iodide concentration at the inlet of the silver-loaded zeolite bed (15) is measured through the bypass flow path (25); Step 5: switching the carrier gas to the silver-loaded zeolite bed (15) through the first three-way valve (7), recording the temperature change of the silver-loaded zeolite bed (15), and simultaneously measuring the methyl iodide gas concentration at the gas outlet (23) of the silver-loaded zeolite bed (15); Step 6: gradually increase the temperature of the thermostat (14) from the cold state and repeat the above steps; Step 7: After the test is completed, the carrier gas is switched to the bypass flow path (25), and then the gas cylinder (5), steam generator (16) and nitrogen source (1) are turned off in sequence, and finally the power supply of the thermostat (14) is turned off.

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