Middle collector and method for descaling inner wall of U-shaped heat transfer tube of steam generator

Abstract

The invention belongs to the technical field of steam generator inspection and maintenance, and aims to solve the problems of low shot blasting channel correctness detection, low mixture recovery efficiency, cleaning effect detection and the like in the prior art. The invention discloses an intermediate collector and method for descaling the inner wall of a U-shaped heat transfer pipe of a steam generator, and the intermediate collector comprises a first pipeline, a second pipeline and a third pipeline which are connected in parallel, and is connected with the inlet end of a fourth pipeline; the outlet end of the fourth pipeline is connected with a fifth pipeline and a sixth pipeline which are connected in parallel, the fifth pipeline and the sixth pipeline are connected with a seventh pipeline, and the seventh pipeline is connected with an air blower; the method utilizes the device to realize high-efficiency recovery of the mixture. According to the invention, one-to-one channel detection can be conveniently realized, inconsistency of transmitting and receiving is avoided, and foreign matters are prevented from falling into the system.

Description

Technical Field

[0001] The present application belongs to the technical field of steam generator inspection and maintenance, and in particular relates to an intermediate collector and method for descaling the inner wall of a U-shaped heat transfer tube of a steam generator. Background Art

[0002] During the operation of heavy water reactors, the primary circuit of the reactor faces serious corrosion problems. This is mainly because the coolant in the primary circuit needs to withstand the harsh environment of high temperature and high pressure when circulating in the reactor. At the same time, it is also affected by the radiation generated by the reactor and the chemical medium. Corrosion products will be generated in the pipeline and deposited on the inner wall of the steam generator heat transfer tube, which not only affects the power generation efficiency, but also threatens the operation stability and safety of the nuclear power plant. Traditional heat transfer tube cleaning methods often have problems such as incomplete cleaning, low efficiency, and high energy consumption.

[0003] The existing shot peening cleaning technology uses high-speed shot to impact the inner wall of the heat transfer tube to remove dirt and sediment. However, during the shot peening cleaning process, how to effectively collect and process the shot, prevent foreign matter, and detect the cleaning effect have become urgent problems to be solved. Summary of the invention

[0004] The purpose of the present application is to provide an intermediate collector and method for descaling the inner wall of a U-shaped heat transfer tube of a steam generator, so as to solve the problems of correctness detection of shot peening channels, low mixture recovery efficiency and cleaning effect detection in the prior art.

[0005] In order to achieve the above objectives, this application provides the following technical solutions:

[0006] In a first aspect, the present application provides an intermediate collector for descaling the inner wall of a U-shaped heat transfer tube of a steam generator, comprising a first pipeline, a second pipeline and a third pipeline connected in parallel, and connected to an inlet end of a fourth pipeline; an outlet end of the fourth pipeline is connected to a fifth pipeline and a sixth pipeline connected in parallel, the fifth pipeline and the sixth pipeline are connected to a seventh pipeline, and the seventh pipeline is connected to a blower;

[0007] The first pipeline is provided with a first control valve, the second pipeline is provided with a second control valve, and the third pipeline is provided with a third control valve; the fifth pipeline is provided with a fourth control valve, a pressure sensor, a flow sensor, and a fifth control valve in sequence; the sixth pipeline is provided with a sixth control valve; and the seventh pipeline is provided with a seventh control valve.

[0008] In some embodiments, the first pipe is connected to an orifice of one of the U-shaped pipes.

[0009] In some embodiments, the second pipe is connected to an orifice of another U-shaped pipe.

[0010] In a second aspect, the present application provides a method for descaling the inner wall of a U-shaped heat transfer tube of a steam generator, using the above-mentioned intermediate collector for descaling the inner wall of a U-shaped heat transfer tube of a steam generator, comprising the following steps:

[0011] Step 1: Channel inspection before shot peening;

[0012] Step 2: Implement shot peening, and close the pressure and flow detection circuits during shot peening;

[0013] Step 3: Open the air supply circuit and recover all the pellets through the blower;

[0014] Step 4: After shot peening, close the corresponding pipeline to detect the flow rate, and confirm the descaling effect by the flow difference before and after shot peening.

[0015] In some embodiments, channel detection includes pressure detection and flow detection.

[0016] In some embodiments, the pressure and flow rate on the branch line are detected by compressed air, and the shot is fired after confirming that the channel is correct.

[0017] In some embodiments, step 1 comprises:

[0018] Step 1.1: close the second control valve, the third control valve, the fifth control valve, the sixth control valve, and the seventh control valve, open the first control valve and the fourth control valve, detect the air pressure through the pressure sensor, confirm that the channel is correct, open the fifth control valve and the seventh control valve to continue blowing, record the value of the flow sensor, and stop blowing;

[0019] Step 1.2: After completing step 1.1, close the first control valve, the fifth control valve, and the seventh control valve, open the second control valve and the fourth control valve, detect the air pressure through the pressure sensor, and after confirming that the channel is correct, open the fifth control valve and the seventh control valve to continue blowing, record the value of the flow sensor, and stop blowing.

[0020] In some embodiments, during shot peening, the first control valve, the second control valve, the sixth control valve, and the seventh control valve are opened, and the fourth control valve and the fifth control valve are closed.

[0021] In some embodiments, after shot blasting is completed, when the blower puts the intermediate collector pipeline in a negative pressure state, the third control valve is opened to replenish air and recover the mixture.

[0022] In some embodiments, after the mixture is recovered, the third control valve and the sixth control valve are closed, the fourth control valve and the fifth control valve are opened, and then the first control valve and the second control valve are closed in sequence. The air flow rates of the two channels are respectively detected by the flow controller, and the flow rates are compared with the flow rates before shot peening to detect the effectiveness of descaling.

[0023] Compared with the prior art, the intermediate collector and method for descaling the inner wall of a U-shaped heat transfer tube of a steam generator provided in the present application have the following beneficial effects:

[0024] This application can conveniently implement one-to-one channel detection, avoid inconsistencies in transmission and reception, and prevent foreign objects from falling in.

[0025] The present application adds an air replenishing function to the negative pressure system recovery system, thereby improving the mixture recovery efficiency and avoiding the blockage of the pipeline after long-term operation.

[0026] This application can evaluate the descaling effect by comparing the changes in air flow before and after shot peening, and provide data support for the evaluation of descaling effectiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for the technical description.

[0028] Figure 1 A schematic diagram of the structure of the intermediate collector for descaling the inner wall of a U-shaped heat transfer tube of a steam generator provided in this application;

[0029] Figure 2 A flow chart of a method for descaling the inner wall of a U-shaped heat transfer tube of a steam generator provided in the present application. DETAILED DESCRIPTION

[0030] The following is further explained in detail through specific implementation methods.

[0031] In the present application, when descaling and cleaning the primary side of the heat transfer tube, a robot in the cold side water chamber carries a spray gun and aims at a certain U-shaped tube hole to fire shot. A hot end robot carries a collecting nozzle to collect the shot at the hot side tube mouth of the U-shaped tube. In order to avoid the shot from accidentally falling into the water chamber due to the inconsistency between the tube mouth of the launching end and the tube mouth of the collecting end, it is considered to blow compressed air through the launching end before the shot is launched, hold the pressure in the loop connected to the rear of the receiving end, and identify the pressure through the pressure sensor to ensure that the tube mouths connected to the launching end and the collecting end are consistent.

[0032] In order to improve the descaling efficiency, the present application has two interfaces at the transmitting end (cold end) and the collecting end (hot end), which can realize the descaling work of the two U-shaped tubes.

[0033] After the channel is detected correctly, during normal shot blasting, in order to prevent the sensor from being impacted by the shot, the present application designs a separate branch (the sixth pipeline) to be connected to the blower recovery end.

[0034] After double-channel shot peening, when the mixture is recovered, the U-tube pipeline is very long (nearly 20m), the air replenishment is not timely, and the other pipelines are all closed. Therefore, this application designs an air replenishment port at the front end of the mixture concentration point to achieve efficient recovery of the mixture.

[0035] By adding a flow sensor to the pressure detection circuit, the cleaning effect can be quantitatively evaluated by comparing the air flow in the pipeline before and after shot peening.

[0036] like Figure 1 As shown, the present application provides an intermediate collector for descaling the inner wall of a U-shaped heat transfer tube of a steam generator, including a first control valve FV1, a second control valve FV2, a third control valve FV3, a fourth control valve FV4, a fifth control valve FV5, a sixth control valve FV6, a seventh control valve FV7, a pressure sensor PT1, a flow sensor FL1, and a blower 1.

[0037] The first control valve FV1, the second control valve FV2 and the third control valve FV3 are arranged in parallel, the first control valve FV1 is set on the first pipeline, the second control valve FV2 is set on the second pipeline, and the third control valve FV3 is set on the third pipeline. The first pipeline, the second pipeline and the third pipeline are arranged in parallel and the outlet ends of the three pipelines are connected to the fourth pipeline. The first pipeline and the second pipeline are connected to the pipe mouths of two U-shaped pipes respectively; the third pipeline is connected to the air supply branch (the third pipeline). For the convenience of description, the pipeline connected to the pipe mouth of the first control valve FV1 and the U-shaped pipe is channel one, and the pipeline connected to the pipe mouth of the second control valve FV2 and another U-shaped pipe is channel two.

[0038] The fifth pipeline and the sixth pipeline are connected in parallel, and the inlet ends of the fifth pipeline and the sixth pipeline are connected to the outlet end of the fourth pipeline, the outlet ends of the fifth pipeline and the sixth pipeline are connected to the seventh pipeline, and the seventh pipeline is connected to the blower 1. The function of the blower 1 is to form a negative pressure at its inlet to facilitate the recovery of the mixture.

[0039] The fifth pipeline is provided with a fourth control valve FV4, a pressure sensor PT1, a flow sensor FL1, and a fifth control valve FV5 in sequence. The sixth pipeline is provided with a sixth control valve FV6. The seventh pipeline is provided with a seventh control valve FV7.

[0040] like Figure 2 As shown, based on the above-mentioned intermediate collector for descaling the inner wall of a U-shaped heat transfer tube of a steam generator, the present application also provides a method for descaling the inner wall of a U-shaped heat transfer tube of a steam generator, comprising the following steps:

[0041] Step 1: Before shot peening, test each channel (channel 1 and channel 2), including pressure and flow rate testing.

[0042] The pressure and flow rate on the branch line (fifth pipeline) are tested by compressed air, and the shot can be fired only after the channel is confirmed to be correct. Specifically, it includes:

[0043] Step 1.1: Channel 1 detection. Close the second control valve FV2, the third control valve FV3, the fifth control valve FV5, the sixth control valve FV6, and the seventh control valve FV7, open the first control valve FV1 and the fourth control valve FV4, and blow compressed air at the cold side inlet (cold end) of the heat transfer tube corresponding to channel 1, and exhaust air at its hot side outlet (hot end). At this time, the air pressure is detected by the pressure sensor PT1. After confirming that channel 1 is correct, open the fifth control valve FV5 and the seventh control valve FV7 and continue blowing for a period of time (for example, 10-30 seconds). At this time, the flow sensor FL1 should display the flow, and stop blowing after recording.

[0044] Step 1.2: Channel 2 detection. After the channel 1 detection is completed, close the first control valve FV1, the fifth control valve FV5, and the seventh control valve FV7, open the second control valve FV2 and the fourth control valve FV4, and blow compressed air at the cold side inlet of channel 2, and exhaust the hot side outlet circuit (channel 1 and channel 2). At this time, the air pressure is detected by the pressure sensor PT1. After confirming that channel 2 is correct, open the fifth control valve FV5 and the seventh control valve FV7 and continue blowing for a period of time (for example, 10-30 seconds). At this time, the flow sensor FL1 should have a flow display, and stop blowing after recording.

[0045] Step 2: Shot peening.

[0046] During shot peening, close the pressure and flow detection circuits to prevent the sensors from being damaged by the shot materials, that is, close the fourth control valve FV4 and the fifth control valve FV5 to close the fifth pipeline to protect the pressure sensor PT1 and the flow sensor FL1. Open the first control valve FV1, the second control valve FV2, the sixth control valve FV6, and the seventh control valve FV7, close the fourth control valve FV4 and the fifth control valve FV5, and start shot peening according to the time required by the process.

[0047] Step 3: Efficient recovery of the mixture.

[0048] After the shot peening is finished, the air supply branch (the third pipeline) is opened, and all the shot materials are recovered through the blower 1. After the shot peening is finished, when the blower 1 makes the intermediate collector pipeline (the sixth pipeline) in a negative pressure state, at this time, based on step 2, the third control valve FV3 is opened, and air is added to pipeline 3, and the mixture is completely recovered through the negative pressure system. It should be noted that the fifth pipeline is used to detect pressure and flow, and is usually not opened; during shot peening and recovery, the sixth control valve FV6 is opened, and the sixth pipeline is opened.

[0049] Step 4: Comparison of descaling effects of a single U-shaped heat transfer tube.

[0050] After shot peening is completed, close the corresponding pipeline (the sixth pipeline) to detect the flow rate, and then confirm the descaling effect through the flow difference before and after shot peening. Close the sixth control valve FV6 to close the sixth pipeline, open the fourth control valve FV4 and the fifth control valve FV5 to open the fifth pipeline, and detect the efficiency through the difference in flow rate. After the mixture is recovered, close the third control valve FV3 and the sixth control valve FV6, open the fourth control valve FV4 and the fifth control valve FV5, and then close the first control valve FV1 and the second control valve FV2 in turn, and use the flow controller FL1 to detect the air flow of the two channels (channel one and channel two) respectively, and compare the flow rate with the flow rate before shot peening to detect the descaling effectiveness of the heat transfer tube (U-type heat transfer tube one or heat transfer tube two) in the channel.

[0051] The above description is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed in the present application should be covered within the protection scope of the present application.

Claims

1. An intermediate collector for descaling the inner wall of a U-shaped heat transfer tube of a steam generator, characterized in that: The first pipeline, the second pipeline and the third pipeline are connected in parallel and connected to the inlet end of the fourth pipeline; the outlet end of the fourth pipeline is connected to the fifth pipeline and the sixth pipeline in parallel, the fifth pipeline and the sixth pipeline are connected to the seventh pipeline, and the seventh pipeline is connected to the blower; The first pipeline is provided with a first control valve, the second pipeline is provided with a second control valve, and the third pipeline is provided with a third control valve; the fifth pipeline is provided with a fourth control valve, a pressure sensor, a flow sensor, and a fifth control valve in sequence; the sixth pipeline is provided with a sixth control valve; and the seventh pipeline is provided with a seventh control valve.

2. The intermediate collector for descaling the inner wall of a U-shaped heat transfer tube of a steam generator according to claim 1, characterized in that: The first pipeline is connected to the pipe opening of one of the U-shaped pipes.

3. The intermediate collector for descaling the inner wall of a U-shaped heat transfer tube of a steam generator according to claim 1, characterized in that: The second pipeline is connected to the pipe mouth of another U-shaped pipe.

4. A method for descaling the inner wall of a U-shaped heat transfer tube of a steam generator, characterized in that: Using the intermediate collector for descaling the inner wall of a U-shaped heat transfer tube of a steam generator as claimed in any one of claims 1 to 3 comprises the following steps: Step 1: Perform channel detection; Step 2: Implement shot peening, and close the pressure and flow detection circuits during shot peening; Step 3: Open the air supply branch and recover all the pellets through the blower; Step 4: After shot peening, close the corresponding pipeline to detect the flow rate, and confirm the descaling effect by the flow difference before and after shot peening.

5. The method for descaling the inner wall of a U-shaped heat transfer tube of a steam generator according to claim 4, characterized in that: Channel detection includes pressure detection and flow detection.

6. The method for descaling the inner wall of a U-shaped heat transfer tube of a steam generator according to claim 4 or 5, characterized in that: The pressure and flow rate on the branch line are tested by compressed air, and the shot is fired after the channel is confirmed to be correct.

7. The method for descaling the inner wall of a U-shaped heat transfer tube of a steam generator according to claim 4, characterized in that: Step 1 includes: Step 1.1: close the second control valve, the third control valve, the fifth control valve, the sixth control valve, and the seventh control valve, open the first control valve and the fourth control valve, detect the air pressure through the pressure sensor, confirm that the channel is correct, open the fifth control valve and the seventh control valve to continue blowing, record the value of the flow sensor, and stop blowing; Step 1.2: After completing step 1.1, close the first control valve, the fifth control valve, and the seventh control valve, open the second control valve and the fourth control valve, detect the air pressure through the pressure sensor, and after confirming that the channel is correct, open the fifth control valve and the seventh control valve to continue blowing, record the value of the flow sensor, and stop blowing.

8. The method for descaling the inner wall of a U-shaped heat transfer tube of a steam generator according to claim 4, characterized in that: During shot peening, the first control valve, the second control valve, the sixth control valve, and the seventh control valve are opened, and the fourth control valve and the fifth control valve are closed.

9. The method for descaling the inner wall of a U-shaped heat transfer tube of a steam generator according to claim 4, characterized in that: After the shot blasting is completed, when the blower makes the intermediate collector pipeline in a negative pressure state, the third control valve is opened at this time, air is replenished, and the mixture is recovered.

10. The method for descaling the inner wall of a U-shaped heat transfer tube of a steam generator according to claim 4, characterized in that: After the mixture is recovered, the third control valve and the sixth control valve are closed, the fourth control valve and the fifth control valve are opened, and then the first control valve and the second control valve are closed in sequence. The air flow rates of the two channels are respectively detected by the flow controller, and the flow rates are compared with the flow rates before shot peening to detect the effectiveness of descaling.

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