CN106124393A - Flowing accelerated corrosion assay device and using method thereof - Google Patents

Abstract

The invention provides a flow-accelerated corrosion test device and its use method, comprising: a loop; a stabilizing water tank, a heating water tank, a centrifugal circulating pump, a shut-off valve, a turbine flowmeter, a first test section, a second A test section, an observation window section, and a third test section; in the circuit, a pressure gauge and a temperature sensor are all arranged between the first test section and the second test section. The first test section is the elbow test section, the second test section is the variable diameter test section, and the third test section is the tee test section. The invention is carried out aiming at the corrosion problem of the pipe material of the conventional island of the reactor, and focuses on studying the rule of pipe thickness thinning caused by flow accelerated corrosion of the pipe of the secondary circuit system, laying a foundation for the life evaluation and safe operation of the pipe of the nuclear power plant.

Description

Flow Accelerated Corrosion Test Apparatus and Method of Use

technical field

The invention relates to the field of accelerated corrosion research, in particular to a flow accelerated corrosion test device and a method for using the same, and in particular to a research scheme for flow accelerated corrosion of a nuclear power plant secondary circuit pipeline.

Background technique

There are many pipes in the secondary circuit system of nuclear power plants, including condensate pipes and crisis drainage pipes. They are generally made of carbon steel or chromium-containing carbon steel. They are corroded by high-temperature and high-pressure water and flow-accelerated corrosion (FAC). The thinning of the thickness is a serious potential threat to the safe operation of the pipeline.

Contents of the invention

Aiming at the defects in the prior art, the object of the present invention is to provide a flow accelerated corrosion test device and its application method.

A flow accelerated corrosion test device provided according to the present invention includes: a circuit;

A heating water tank, a centrifugal circulating pump, a stop valve, a turbine flowmeter, a first test section, a second test section, an observation window section, and a third test section are arranged in sequence in the loop;

In the circuit, the pressure gauge and the temperature sensor are both arranged between the first test section and the second test section.

Preferably, the first test section is an elbow test section, the second test section is a variable diameter test section, and the third test section is a tee test section;

The first end of the three-way test section is connected to the observation window section;

The second end of the three-way test section is connected to the heating water tank through the first circuit branch;

The third end of the three-way test section is connected to the heating water tank through the second circuit branch;

On the branch of the second circuit, from upstream to downstream, there are shut-off valves, turbine flowmeters and pressure gauges.

Preferably, the heating water tank is equipped with a heater, a temperature sensor, and a water discharge valve, and the gas cylinder, the gas regulating valve, the pressure-stabilizing water tank, and the heating water tank are connected in sequence;

The chemical adjustment water tank is connected to the pressure-stabilizing water tank through the water inlet pump; a sampling valve is connected to the pipeline between the water inlet pump and the heating water tank.

Preferably, the heating water tank maintains the circuit at a constant pressure and temperature through a heater and a gas regulating valve; the working fluid in the reflux flows at a constant flow rate;

Preferably, the material of the first test section, the second test section and the third test section is secondary circuit pipe steel, and the material of other sections in the circuit is stainless steel pipe.

According to a method of using the above-mentioned flow accelerated corrosion test device provided by the present invention, the pressure information and temperature information are collected and monitored through the pressure sensor and the temperature sensor in the loop;

Take water samples through the sampling valve, and measure the pH value, oxygen content and conductivity;

Each time after the loop runs for a set time, use a thickness gauge to measure the thickness of the pipe wall in the first test section, the second test section, and the third test section, and obtain the thinning rate of the pipe wall during the experiment;

After the test is completed, the first test section, the second test section, and the third test section are taken out, and the surface morphology of the inner wall of the test section is detected by electron microscope scanning.

Preferably, the pH value and oxygen content of the working fluid in the loop are adjusted by adding hydrazine N ₂ H ₄ into the loop.

Preferably, the liquid level is obtained by setting measuring points in the pressurized water tank.

Preferably, each time the wall thickness of the first test section, the second test section, and the third test section is measured by the thickness gauge, the first test section, the second test section, and the third test section are in the same state.

Preferably, the same state includes that the temperature and pressure of the working fluid in the circuit are consistent, and the position of each measurement is consistent.

Compared with the prior art, the present invention has the following beneficial effects:

1. The present invention is developed for the corrosion problem of the pipe material of the conventional island of the reactor, focusing on the study of the thickness reduction law of the pipe in the secondary circuit system due to flow-accelerated corrosion, and laying the foundation for the life evaluation and safe operation of the pipe in the nuclear power plant.

2. Select the miniature thickness measuring probe, by marking the test position, keep the position of each measurement consistent, and accurately obtain the change of the pipe wall thickness with the corrosion time.

Description of drawings

Other characteristics, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

Fig. 1 is a schematic diagram of the test circuit of the flow accelerated corrosion test device provided by the present invention.

Fig. 2 is a top view of the test circuit of the flow accelerated corrosion test device provided by the present invention.

In the picture:

1-Heating water tank and heater 11-Chemical adjustment water tank

2-centrifugal circulation pump 12-water discharge valve

3-turbine flowmeter 13-sampling valve

4- Elbow test section 14- Shut-off valve

5-Reducing test section 15-Temperature sensor

6-Pressure gauge 16-Gas regulating valve

7- Observation window segment

8- Tee test section

9-stabilized water tank

10-Inlet pump

detailed description

The present invention will be described in detail below in conjunction with specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

A flow-accelerated corrosion test device provided according to the present invention includes: a circuit; a heating water tank, a centrifugal circulation pump, a shut-off valve, a turbine flowmeter, a first test section, a second test section, an observation window section, The third test section: the heating water tank is connected to the pressure-stabilizing water tank; in the circuit, the pressure gauge and the temperature sensor are both arranged between the first test section and the second test section. The first test section is the elbow test section, the second test section is the variable diameter test section, and the third test section is the three-way test section; the first end of the three-way test section is connected to the observation window section; the second end of the three-way test section One end is connected to the heating water tank through the first circuit branch; the third end of the three-way test section is connected to the heating water tank through the second circuit branch; on the second circuit branch, from upstream to downstream, a stop valve, a turbine flowmeter , Pressure gauge.

The heating water tank is equipped with a heater, temperature sensor, and water discharge valve; it is connected with the gas cylinder, gas regulating valve, and pressure-stabilizing water tank in sequence; the chemical adjustment water tank is connected to the pressure-stabilizing water tank through the water inlet pump; the pipeline between the water inlet pump and the heating water tank is connected with Sampling valve. The stabilized water tank is connected to the gas regulating valve to maintain the circuit at a constant pressure; the working medium in the return flow flows at a constant flow rate; the material of the first test section, the second test section, and the third test section is the secondary circuit pipe steel, and the circuit in the circuit The material of the other sections is stainless steel pipe.

According to a method for using the above-mentioned flow accelerated corrosion test device provided by the present invention, the pressure information and temperature information are collected and monitored through the pressure sensor and the temperature sensor in the loop; the water sample is obtained through the sampling valve, and the pH value, oxygen The measurement of content and conductivity; each time after the loop runs for a set time, the thickness of the first test section, the second test section, and the third test section are measured with a thickness gauge, and the reduction of the pipe wall during the experiment is obtained. Thinness rate: After the test is completed, the first test section, the second test section, and the third test section are taken out, and the surface morphology of the inner wall of the test section is detected by electron microscope scanning. By adding hydrazine N ₂ H ₄ into the loop, the pH value and oxygen content of the working fluid in the loop are adjusted. The liquid level is obtained by setting measuring points in the pressurized water tank. When the thickness gauge is used to measure the pipe wall thickness of the first test section, the second test section and the third test section, the first test section, the second test section and the third test section are in the same state. The same state includes that the temperature and pressure of the circuit working medium are consistent, and the position of each measurement is consistent.

The present invention will be described more specifically below.

The flow accelerated corrosion test device provided by the present invention can be used as an experimental system for simulating the working condition of the main water supply pipeline of the secondary circuit of the nuclear power plant. The flow-accelerated corrosion test device preferably simulates the main water supply pipeline system of the secondary circuit of the nuclear power plant.

The flow-accelerated corrosion test device includes three test sections and pipes connecting the three test sections, a main pump, a pressurized water tank, a heating water tank, a gas cylinder, a pressure sensor and a number of temperature sensors, as shown in FIG. 1 .

In the flow accelerated corrosion test device, the nitrogen cylinder is connected to the pressure-stabilized water tank through a gas regulating valve to maintain the circuit at a constant pressure; the circuit is maintained at a constant temperature by a heater.

The single-phase water in the circuit flows in the circuit at a constant flow rate driven by the centrifugal circulating pump; a number of pressure sensors and temperature sensors are arranged in the circuit, and the pressure sensors and temperature sensors transmit the pressure and temperature signals to the host computer respectively to realize real-time monitoring , and an appropriate amount of water samples can be obtained through the sampling valve to measure the pH value, oxygen content and conductivity.

After running for a certain period of time each time, the thickness of the pipe wall at a specific position in the experimental section is measured with a thickness gauge, and the thinning rate of the pipe wall during the experiment is obtained.

After the test is completed, the test section is taken out, and the surface morphology of the inner wall of the test section is detected by electron microscope scanning.

The invention can help to study the thinning rule of the pipeline in the secondary circuit system caused by flow accelerated corrosion.

(1) By designing and constructing a special FAC (Flow Accelerated Corrosion) test circuit, simulating the typical working condition test of the secondary circuit, setting the secondary circuit pipeline material test section in the circuit, and testing the corrosion of the material under the flow state of high temperature and high pressure fluid Mechanism and Thinning Law. The test uses deionized water. After the water chemical performance test, it is injected into the heating water tank before the test.

(2) By observing the change of the pipe wall thickness of the material in the test section with the flow velocity and time, understand the law of pipe wall thickness thinning, understand the influence of different flow velocity pipe wall thinning rates, and analyze the relationship between the pipeline FAC corrosion rate and environmental working condition parameters relation.

(3) Partially decompose the test section with severe FAC, and analyze the material of the test section by means of scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) to understand the morphology and appearance of FAC corrosion products of pipeline materials. Chemical composition, in-depth analysis of its corrosion mechanism.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. In the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims (10)

1. A flow accelerated corrosion test device, characterized in that, comprising: a loop; A heating water tank, a centrifugal circulating pump, a stop valve, a turbine flowmeter, a first test section, a second test section, an observation window section, and a third test section are arranged in sequence in the loop; In the circuit, the pressure gauge and the temperature sensor are both arranged between the first test section and the second test section. 2. The flow accelerated corrosion test device according to claim 1, wherein the first test section is an elbow test section, the second test section is a variable diameter test section, and the third test section is a tee test section; The first end of the three-way test section is connected to the observation window section; The second end of the three-way test section is connected to the heating water tank through the first circuit branch; The third end of the three-way test section is connected to the heating water tank through the second circuit branch; On the branch of the second circuit, from upstream to downstream, there are shut-off valves, turbine flowmeters and pressure gauges. 3. The flow accelerated corrosion test device according to claim 1, wherein the heating water tank is equipped with a heater, a temperature sensor, and a water discharge valve, and the gas cylinder, the gas regulating valve, the stabilizing water tank, and the heating water tank are connected in sequence; The chemical adjustment water tank is connected to the pressure-stabilizing water tank through the water inlet pump; a sampling valve is connected to the pipeline between the water inlet pump and the heating water tank. 4. The flow-accelerated corrosion test device according to claim 3, wherein the heated water tank maintains the circuit at a constant pressure and temperature through a heater and a gas regulating valve; the working medium in the reflux flows at a constant flow rate. 5. flow accelerated corrosion test device according to claim 1, is characterized in that, the material of the first test section, the second test section, the third test section is secondary circuit pipeline steel, and the material of other sections in the loop is stainless steel Tube. 6. A method for using the flow accelerated corrosion test device described in any one of claims 1 to 5, wherein pressure information and temperature information are collected by pressure sensors and temperature sensors in the circuit, and monitored; Take water samples through the sampling valve, and measure the pH value, oxygen content and conductivity; Each time after the loop runs for a set time, use a thickness gauge to measure the thickness of the pipe wall in the first test section, the second test section, and the third test section, and obtain the thinning rate of the pipe wall during the experiment; After the test is completed, the first test section, the second test section, and the third test section are taken out, and the surface morphology of the inner wall of the test section is detected by electron microscope scanning. 7 . The method for using the flow accelerated corrosion test device according to claim 6 , characterized in that the pH value and oxygen content of the working fluid in the loop are adjusted by adding hydrazine N ₂ H ₄ into the loop. 8. The method for using the flow accelerated corrosion test device according to claim 6, characterized in that the liquid level is obtained by setting measuring points in the pressurized water tank. 9. the using method of flow accelerated corrosion test device according to claim 6, is characterized in that, when measuring first test section, second test section, the 3rd test section pipe wall thickness with thickness gauge each time, first The test segment, the second test segment, and the third test segment are in the same state. 10 . The method for using the flow accelerated corrosion test device according to claim 9 , wherein the same state includes the same temperature and pressure of the working medium in the circuit, and the same position for each measurement. 11 .