Calculation method of container gas purging effect

Abstract

The invention discloses a method for calculating the gas purging effect of a container, the container contains first gas, and the method comprises the following steps: exhausting the gas purging space of the container to a first preset pressure value, and converting the gas purging space under the first preset pressure value into a first gas standard volume under the standard atmospheric pressure of the first preset pressure value; calculating the standard volume of the first gas in the purging gas space under the standard atmospheric pressure according to the percentage content of the first gas in the container and the standard volume of the first gas; filling second gas into the purging gas space to a second preset pressure intensity value, wherein the second preset pressure intensity value is smaller than or equal to the preset value of the upstream pressure reducing valve; converting the purging gas space under the second preset pressure value into a second gas standard volume under the standard atmospheric pressure; calculating the percentage content of the first gas in the container according to the first gas standard volume and the second gas standard volume; and repeating the steps until the percentage content of the first gas in the container is within a preset range. The gas purging time is saved, and manpower waste is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of gas purging, and in particular to a method for calculating the effect of gas purging of a container. Background Art

[0002] The overhaul of a nuclear power plant is a relatively large-scale maintenance activity carried out in a centralized manner according to the aging characteristics of the equipment and the requirements of the technical specifications in order to ensure the subsequent safe operation of the nuclear power plant. Among them, the nuclear power unit needs to replace the nuclear fuel every 12 or 18 months, shut down the unit for maintenance, and deal with some defects that cannot be handled daily.

[0003] At present, the gas purging of containers is controlled through experience. The personnel who stay on site wait for the pressure to reach 0.29Mpa and then stop pressurizing in time. The waiting time for the personnel who stay on site to stop pressurizing after the pressure reaches the specified value is long, which wastes manpower. The personnel who do not stay on site may not be able to stop pressurizing in time when the container pressure is high, resulting in the risk of accidental discharge of radioactive gas after the container safety valve is actuated. Summary of the invention

[0004] The technical problem to be solved by the present invention is that, in view of at least one defect of the related technology mentioned in the above background technology: when the container is gas purged, personnel who stay on site need to wait for the pressure to reach the specified value before stopping the pressurization, which results in a long waiting time and wastes manpower. A method for calculating the effect of container gas purging is provided.

[0005] The technical solution adopted by the present invention to solve the technical problem is: construct a method for calculating the gas purging effect of a container, wherein the container has a first gas, and the method comprises the following steps:

[0006] S1: exhausting the purge gas space of the container to a first preset pressure value, and converting the purge gas space at the first preset pressure value into a first gas standard volume at the standard atmospheric pressure of the first preset pressure value;

[0007] S2: Calculating the standard volume of the first gas in the purge gas space under standard atmospheric pressure according to the percentage content of the first gas in the container and the standard volume of the first gas;

[0008] S3: Filling the purge gas space with a second gas to a second preset pressure value, wherein the second preset pressure value is less than or equal to a preset set value of the upstream pressure reducing valve;

[0009] S4: converting the purge gas space at the second preset pressure value into the standard volume of the second gas at the standard atmospheric pressure;

[0010] S5: Calculating the percentage content of the first gas in the container according to the standard volume of the first gas and the standard volume of the second gas;

[0011] S6: Repeat steps S1 to S5 until the calculated percentage content of the first gas in the container is within a preset range.

[0012] In some embodiments, before step S1, the method further includes:

[0013] A purge gas space for purge is defined in the container space.

[0014] In some embodiments, a purge gas space for purge is defined in the container space, including:

[0015] A liquid that does not react with the first gas in the purge gas space is added into the container space to define a purge gas space for purge.

[0016] In some embodiments, the second preset pressure value is less than a preset set value of the upstream pressure reducing valve.

[0017] In some embodiments, when the second preset pressure value is equal to a preset set value of the upstream pressure reducing valve, the pressure reducing valve is closed, and the pressure reducing valve is closed as the second preset pressure value increases.

[0018] In some embodiments, the container is a pre-storage tank for storing liquid raw materials, liquid intermediate products, or liquid semi-finished products.

[0019] In some embodiments, the first gas is a flammable gas.

[0020] In some embodiments, the first preset pressure value is a pressure value inside the container that is higher than a preset Pa value of the atmospheric pressure outside the container.

[0021] In some embodiments, the second gas is an inert gas.

[0022] In some embodiments, in step S4, before converting the purge gas space at the second preset pressure value into the second gas standard volume at the standard atmospheric pressure, the method further includes:

[0023] Waiting for a preset time until the first gas and the second gas in the purge gas space are fully mixed to form a mixed gas.

[0024] By implementing the present invention, the following beneficial effects are achieved:

[0025] The present invention exhausts the purge gas space of the container to a first preset pressure value, and converts the purge gas space at the first preset pressure value into the standard volume of the first gas under the standard atmospheric pressure of the first preset pressure value; calculates the standard volume of the first gas in the purge gas space under the standard atmospheric pressure according to the percentage content of the first gas in the container and the standard volume of the first gas; fills the second gas into the purge gas space to a second preset pressure value, wherein the second preset pressure value is less than or equal to the preset constant of the upstream pressure reducing valve; converts the purge gas space at the second preset pressure value into the standard volume of the second gas under the standard atmospheric pressure; calculates the percentage content of the first gas in the container according to the standard volume of the first gas and the standard volume of the second gas; and repeats the above steps until the calculated percentage content of the first gas in the container is within the preset range, thereby saving gas purge time and preventing manpower waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0027] Figure 1 A flow chart showing an embodiment of a method for calculating the gas purge effect of a container according to the present invention;

[0028] Figure 2 A pressure diagram of a purging process in an embodiment of a method for calculating the effect of gas purging of a container according to the present invention is shown;

[0029] Figure 3 The single-charge exhaust pressure trend of an embodiment of the method for calculating the gas purge effect of a container according to the present invention is shown. DETAILED DESCRIPTION

[0030] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0031] It should be noted that the flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor do they have to be executed in the order described. For example, some operations / steps can be decomposed, while some operations / steps can be combined or partially combined, so the actual execution order may change according to actual conditions.

[0032] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities may be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0033] Since the operation of nuclear power units, the gas purge during the overhaul of the units has been carried out according to the historical experience of the external base. It needs to be carried out 6 times, which takes about 3 days. During the container pressurization process, in order to ensure that the pressure is accurately controlled to 0.29Mpa.a and the pressurization is stopped manually in time, the on-site personnel need to stay on standby for a long time, which not only consumes a lot of manpower, but also causes the remaining personnel to be highly tired. In addition, there is a risk that the pressurization cannot be stopped in time when the pressure exceeds the limit without personnel on duty, resulting in the risk of accidental radioactive discharge caused by the actuation of the container safety valve.

[0034] like Figure 1 As shown, some embodiments of the present invention disclose a method for calculating a gas purge effect of a container, wherein the container has a first gas, and the method comprises the following steps:

[0035] S1: exhausting the purge gas space of the container to a first preset pressure value, and converting the purge gas space at the first preset pressure value into a first gas standard volume at the standard atmospheric pressure of the first preset pressure value;

[0036] S2: Calculate the standard volume of the first gas in the purge gas space at standard atmospheric pressure according to the percentage content of the first gas in the container and the standard volume of the first gas; wherein the standard volume of the purge gas space at standard atmospheric pressure of the first gas is used to calculate the percentage content of the first gas in the container after inflation and exhaust;

[0037] S3: Filling the purge gas space with a second gas to a second preset pressure value, wherein the second preset pressure value is less than or equal to a preset fixed value of the upstream pressure reducing valve, and preferably the second preset pressure value is less than the preset fixed value of the upstream pressure reducing valve;

[0038] S4: converting the purge gas space at the second preset pressure value into the standard volume of the second gas at the standard atmospheric pressure;

[0039] S5: Calculating the percentage content of the first gas in the container according to the standard volume of the first gas and the standard volume of the second gas;

[0040] S6: Repeat steps S1 to S5 until the calculated percentage content of the first gas in the container is within a preset range.

[0041] In some embodiments, before step S1 , the method further includes: defining a purge gas space for purge in the container space.

[0042] Wherein, a purge gas space for purge is defined in the container space, including:

[0043] A liquid that does not react with the first gas in the purge gas space is added to the container space to define a purge gas space for purging. The purpose of filling the liquid is to reduce the air in the tank, reduce the purge gas consumption, and reduce the emission of radioactive waste gas.

[0044] For example, the container is a front tank for storing liquid raw materials, liquid intermediate products or liquid semi-finished products. Regarding the parameters of the front tank, its total volume (i.e., container space) is 81m 3 .

[0045] Fill the container space with water to 70m 3 , defining the purge gas space for purge as 81m 3 -70m 3 =11m 3 . The front tank, water, 81m 3 and 70m 3 This is just an example and is not intended to limit the present application. Other examples are possible.

[0046] In some embodiments, the second preset pressure value is less than a preset set value of the upstream pressure reducing valve.

[0047] In some embodiments, when the second preset pressure value is equal to the preset fixed value of the upstream pressure reducing valve, the pressure reducing valve is closed, and the pressure reducing valve is closed as the second preset pressure value increases. According to the preset fixed value of the upstream pressure reducing valve, 0.32 MPa is taken as an example here, when the second preset pressure value in the container rises but does not exceed the preset value of the upstream pressure reducing valve of 0.32 MPa, the pressure reducing valve is closed, and the second preset pressure value in the container will still rise slowly, but the rise of the second preset pressure value is slowed down by the pressure reducing valve; when the second preset pressure value in the container rises to reach the preset value of the upstream pressure reducing valve, the pressure reducing valve is closed and the second preset pressure value in the container stops rising.

[0048] In some embodiments, the first gas is a flammable gas. It is understood that there is a certain percentage of flammable gas in the container, and there are other gases in the container besides the flammable gas. For example, the flammable gas can be hydrogen, and the hydrogen here is only an example, and it can also be other flammable, inflammable and explosive gases.

[0049] In some embodiments, the first preset pressure value is a pressure value inside the container that is higher than a preset Pa value of the atmospheric pressure outside the container.

[0050] In some embodiments, the second gas is an inert gas, such as nitrogen, which is only an example and is not intended to limit the present application. The second gas may also be other gases that do not chemically react with the first gas and air.

[0051] In some embodiments, in step S4, before converting the purge gas space at the second preset pressure value into the second gas standard volume at the standard atmospheric pressure, the method further includes:

[0052] Wait for a preset time until the first gas and the second gas in the purge gas space are fully mixed to form a mixed gas. For example, the time for the first gas and the second gas to be fully mixed is 10 minutes, and the 10 minutes here is only an example and is not intended to limit the present application, and may be other.

[0053] Specifically, by comparing the calculation with the actual situation, during a major overhaul, the hydrogen content of the container before purging was 40.9%, and the container was filled with water to 70m 3 , defining the purge gas space for purge as 81m 3 -70m 3 =11m 3 , and exhaust to the first preset pressure value. The first preset pressure value is the pressure value inside the container higher than the preset Pa value of the atmospheric pressure outside the container, that is, a slightly positive pressure. Here, 0.125 MPa is taken as an example. According to PV=PV, it is converted into standard atmospheric pressure to obtain the standard volume of the first gas of 13.75m 3 According to the hydrogen percentage before purge of 40.9%, the volume of hydrogen in the purge gas space under standard atmospheric pressure is about 5.63m 3 Fill the purge gas space with nitrogen until the pressure is less than 0.32 MPa of the upstream pressure reducing valve. Here, 0.29 MPa is taken as an example. According to PV = PV, it is converted into standard atmospheric pressure to obtain the standard volume of the second gas, which is 31.9m 3 , based on the volume of hydrogen in the purge gas space at standard atmospheric pressure, 5.36m 3 The second gas standard volume is 39.1m 3 The percentage of hydrogen in the container is calculated to be 17.65%. Repeat the above steps. The results of each purge are shown in Table 1. The volume of waste gas generated by each purge is 18.15m 3 , take the purge time of each time as 205 minutes as an example.

[0054] Table 1 Data sheet of the container filled with nitrogen to 0.29 MPa

[0055]

[0056] It can be seen from Table 1 that the calculated hydrogen percentage content after 6 purges is 0.26%, which is close to the sampling result of 0.3%.

[0057] like Figure 2 As shown in the figure, the container is inflated and exhausted each time, and it can be seen that the time of each inflation and exhaust is basically the same, such as Figure 3 As shown, taking the first inflation and exhaust as an analysis, the pressure in the front section of the container is low, and the pressure value rises rapidly after inflation. As the pressure inside the container rises, the inflation pressure value rises slowly, and the dividing point is about 0.22 MPa.

[0058] The container filling time is shown in Table 2.

[0059] Table 2 Inflation schedule

[0060] operate time pressure time consuming Start charging 19:06 0.126Mpa.a 19:13 0.2Mpa.a 7min Charging is finished 20:31 0.29Mpa.a 85min

[0061] The container exhaust time is shown in Table 3.

[0062] Table 3 Exhaust schedule

[0063] operate time pressure time consuming Start exhaust 20:43 0.29Mpa.a 21:20 0.2Mpa.a 37min Exhaust end 22:33 0.125Mpa.a 110min

[0064] It can be seen from Tables 2 and 3 that when the air is inflated to 0.29 MPa, the entire inflation and exhaust process is 85 minutes for inflation, 10 minutes for waiting for mixing, and 110 minutes for exhaust. A complete inflation and exhaust process takes 205 minutes.

[0065] When performing this work on duty, there may be a shortage of manpower. When performing some of the filling and exhaust operations, there will be personnel on site. After the container pressure reaches 0.29 MPa, the pressurizing will be stopped in time to avoid the operation of the container safety valve. When performing some of the operations, after starting the inflation, the personnel will not stay to do other work. They will come back to stop the pressurizing operation after the container pressure approaches 0.29 MPa.

[0066] When purging the container with nitrogen, there is a risk that the safety valve will be activated due to high pressure in the container. After the safety valve is activated, hydrogen-containing radioactive gas may be directly discharged into the atmosphere, causing an alarm, which may lead to accidental discharge of radioactive gas and endanger personal safety.

[0067] When the container is pressurized, the personnel who stay on site wait for the pressure to reach 0.29 MPa and then stop the pressurization in time, which wastes manpower. The personnel who do not stay on site may not be able to stop the pressurization in time when the container pressure is high, resulting in the risk of accidental radioactive discharge due to the activation of the container safety valve.

[0068] When inflated to 0.2 MPa, the entire inflation and exhaust process takes 7 minutes to inflate, 10 minutes to wait for mixing, and 73 minutes to exhaust. A complete inflation and exhaust process takes 90 minutes.

[0069] According to the above method of filling the container with nitrogen to 0.29 MPa, the container is filled with nitrogen to 0.2 MPa for calculation, and the results of each purge are listed in Table 4.

[0070] Table 4 Data sheet of the container filled with nitrogen to 0.2 MPa

[0071]

[0072] Comparing Table 1 and Table 4, the number of purges increased from 6 to 11. However, due to the reduction in the purge time, the total purge time for the entire operation was reduced from 1230 minutes to 990 minutes, and the total work time was reduced by 240 minutes. The total exhaust gas emissions increased from 108.9m 3 Reduced to 90.75m 3 , exhaust gas reduction 18.15m 3 .

[0073] After optimization, the container inflation time is 7 minutes, the inflation volume is reduced by half, and the waiting time can also be reduced to 5 minutes. In this way, the on-site personnel need to stay for 12 minutes when the container is inflated, which solves the problem of on-site personnel staying for a long time when the container is inflated, which consumes manpower, and solves the problem of not being able to stop the container in time when the pressure is high without on-site personnel when the container is inflated, and the risk of accidental radioactive discharge from the container due to the activation of the overpressure safety valve.

[0074] This optimization not only greatly reduced the waiting time of on-site personnel, reduced the number of shift changes, and lowered the risk of human error, but also achieved a reduction in radioactive waste gas through refined control, reducing nitrogen consumption and waste gas emissions compared to previous overhauls.

[0075] By changing the first preset pressure value and the second preset pressure value, the method is used to calculate and obtain the minimum number of inflation times and the minimum exhaust volume, so that the percentage content of the first gas in the container is within a preset range. The present invention saves gas purging time and purging gas usage, reduces waste gas emissions, avoids waste of manpower and material resources, and reduces environmental pollution.

[0076] By implementing the present invention, the following beneficial effects are achieved:

[0077] The present invention exhausts the purge gas space of the container to a first preset pressure value, and converts the purge gas space at the first preset pressure value into the standard volume of the first gas under the standard atmospheric pressure of the first preset pressure value; calculates the standard volume of the first gas in the purge gas space under the standard atmospheric pressure according to the percentage content of the first gas in the container and the standard volume of the first gas; fills the second gas into the purge gas space to a second preset pressure value, wherein the second preset pressure value is less than or equal to the preset constant of the upstream pressure reducing valve; converts the purge gas space at the second preset pressure value into the standard volume of the second gas under the standard atmospheric pressure; calculates the percentage content of the first gas in the container according to the standard volume of the first gas and the standard volume of the second gas; and repeats the above steps until the percentage content of the first gas in the container is within a preset range, thereby saving gas purge time and preventing waste of manpower.

[0078] It is understandable that the above embodiments only express some implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present invention, the above embodiments or technical features can be freely combined, and several deformations and improvements can be made, which all belong to the protection scope of the present invention, that is, the embodiments described in "some embodiments" can be freely combined with any of the above and below embodiments. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should belong to the scope of the claims of the present invention.

Claims

1. A method for calculating the gas purge effect of a container, wherein the container has a first gas, characterized in that: The method comprises the following steps: S1: exhausting the purge gas space of the container to a first preset pressure value, and converting the purge gas space at the first preset pressure value into a first gas standard volume at the standard atmospheric pressure of the first preset pressure value; S2: Calculating the standard volume of the first gas in the purge gas space under standard atmospheric pressure according to the percentage content of the first gas in the container and the standard volume of the first gas; S3: Filling the purge gas space with a second gas to a second preset pressure value, wherein the second preset pressure value is less than or equal to a preset set value of the upstream pressure reducing valve; S4: converting the purge gas space at the second preset pressure value into the standard volume of the second gas at the standard atmospheric pressure; S5: Calculating the percentage content of the first gas in the container according to the standard volume of the first gas and the standard volume of the second gas; S6: Repeat steps S1 to S5 until the calculated percentage content of the first gas in the container is within a preset range.

2. The method for calculating the gas purge effect of a container according to claim 1, characterized in that: Before step S1, the method further includes: A purge gas space for purge is defined in the container space.

3. The method for calculating the effect of gas purge of a container according to claim 2, characterized in that: A purge gas space for purging is defined in the container space, including: A liquid that does not react with the first gas in the purge gas space is added into the container space to define a purge gas space for purge.

4. The method for calculating the gas purge effect of a container according to claim 1, characterized in that: The second preset pressure value is less than the preset set value of the upstream pressure reducing valve.

5. The method for calculating the effect of gas purge of a container according to claim 1, characterized in that: When the second preset pressure value is equal to the preset fixed value of the upstream pressure reducing valve, the pressure reducing valve is closed, and the pressure reducing valve is closed as the second preset pressure value increases.

6. The method for calculating the gas purge effect of a container according to claim 1, characterized in that: The container is a pre-storage tank for storing liquid raw materials, liquid intermediate products or liquid semi-finished products.

7. The method for calculating the gas purge effect of a container according to claim 1, characterized in that: The first gas is a flammable gas.

8. The method for calculating the gas purge effect of a container according to claim 1, characterized in that: The first preset pressure value is a pressure value inside the container that is higher than a preset Pa value of the atmospheric pressure outside the container.

9. The method for calculating the gas purge effect of a container according to claim 1, characterized in that: The second gas is an inert gas.

10. The method for calculating the gas purge effect of a container according to claim 1, characterized in that: In step S4, before converting the purge gas space at the second preset pressure value into the second gas standard volume at the standard atmospheric pressure, the method further includes: Waiting for a preset time until the first gas and the second gas in the purge gas space are fully mixed to form a mixed gas.

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