Chemical cleaning method for two-loop valve cage
阅读说明：本技术 用于二回路阀笼的化学清洗方法 (Chemical cleaning method for two-loop valve cage ) 是由 王安宁 张铭刻 王今芳 翁云峰 王成林 胡跃华 费志松 孙勤 沈君 庄佳翔 蒋开 于 2019-10-28 设计创作，主要内容包括：本发明属于核电维修技术领域,具体涉及一种用于二回路阀笼的化学清洗方法。方法包括：使用碱性溶液浸泡清洗二回路阀笼；使用水清洗碱性溶液浸泡清洗过的二回路阀笼；在将二回路阀笼上的碱性残留溶液清除时,使用酸性溶液浸泡清洗二回路阀笼；使用水清洗酸性溶液浸泡清洗过的二回路阀笼；在将二回路阀笼上的酸性残留溶液清除时,使用钝化剂对二回路阀笼进行钝化处理；使用水清洗钝化处理后的二回路阀笼,直至将二回路阀笼上的钝化液残留清除；在将二回路阀笼上的残留的钝化液清除时,对二回路阀笼进行干燥处理。本公开实施例可以对二回路阀笼进行较为快速、彻底的清洁,较少对二回路阀笼产生机械损伤。(The invention belongs to the technical field of nuclear power maintenance, and particularly relates to a chemical cleaning method for a two-circuit valve cage. The method comprises the following steps: soaking and cleaning a two-loop valve cage by using an alkaline solution; soaking the cleaned two-circuit valve cage in an aqueous cleaning alkaline solution; when alkaline residual solution on the two-loop valve cage is removed, soaking and cleaning the two-loop valve cage by using acid solution; soaking the cleaned two-circuit valve cage in an aqueous cleaning acidic solution; when acid residual solution on the two-circuit valve cage is removed, passivating the two-circuit valve cage by using a passivating agent; cleaning the passivated two-loop valve cage by using water until the passivation solution residue on the two-loop valve cage is removed; and when the residual passivating liquid on the two-loop valve cage is removed, drying the two-loop valve cage. The two-circuit valve cage cleaning device can clean the two-circuit valve cage quickly and thoroughly, and mechanical damage to the two-circuit valve cage is reduced.)
1. A method of chemical cleaning for a two-circuit cage, the method comprising:
soaking and cleaning a two-loop valve cage by using an alkaline solution;
washing the alkaline solution with water to soak the washed two-circuit valve cage;
under the condition of removing alkaline residual solution on the two-loop valve cage, soaking and cleaning the two-loop valve cage by using an acidic solution;
washing the acid solution with water to soak the washed two-circuit valve cage;
passivating the two-loop valve cage by using a passivating agent under the condition of removing an acidic residual solution on the two-loop valve cage;
cleaning the passivated two-loop valve cage by using water until the passivation solution residue on the two-loop valve cage is removed;
and under the condition of removing residual passivating liquid on the two-loop valve cage, drying the two-loop valve cage.
2. The method of claim 1, wherein dip cleaning the two-circuit cage with a basic solution comprises:
the two-circuit cage is soaked and cleaned with an alkaline solution having a first temperature for a first period of time.
3. The method of claim 2, wherein the first period of time is between 1.5 hours and 2.5 hours.
4. The method of claim 2, wherein the first temperature is between 70 degrees celsius and 90 degrees celsius.
5. The method according to claim 1 or 2, characterized in that the alkaline solution is circulated.
6. The method of claim 1, wherein soaking and cleaning the two-circuit cage with an acidic solution comprises:
soaking and cleaning the two-circuit valve cage by using an acid solution with a second temperature in a second time period.
7. The method of claim 6, wherein the second period of time is between 8 hours and 12 hours.
8. The method of claim 6, wherein the second temperature is between 70 degrees Celsius and 90 degrees Celsius.
9. The method according to claim 1 or 6, wherein the acidic solution is circulated.
10. The method of claim 1, wherein passivating the two-circuit cage with a passivating agent comprises:
and passivating the two-circuit valve cage by using a passivating agent in a third time period.
11. The method of claim 10, wherein the third period of time is between 20 hours and 28 hours.
12. The method of claim 1, wherein the alkaline solution has a hydrogen ion concentration index PH of 10 to 11 and the acidic solution has a PH of 4 to 5.
Technical Field
The invention belongs to the technical field of nuclear power maintenance, and particularly relates to a chemical cleaning method for a two-circuit valve cage.
Background
Since the 3 rd fuel circulation operation of the square-family mountain 2# unit, the opening degree of three main water supply regulating valves (2 ARE031VL/032VL/033VL respectively) of a main water supply ARE (main water supply flow control system) has an abnormal increasing trend, and the opening degree gradually increases from 52% to the maximum approximate 70%. The main water supply regulating valve is an important device of a secondary loop system of the nuclear power station, the valve opening limit value is required to be 70% during the normal operation of the system, and if the valve opening is continuously increased, the safe operation of a unit is seriously influenced.
The maintenance personnel disassemble and overhaul the main water supply regulating valve 2ARE032VL with the largest opening degree, and replace the valve cage of the regulating valve, and the unit finds that the opening degree of the main water supply regulating valve 2ARE032VL is reduced by 16% -18% after the unit operates again. Further observations were then made on the cage of the replacement regulator valve: the inner walls of most of the small circulation holes on the valve cage are attached with sediments or scale deposits, and the scale deposit is compact and firm, so that the through-flow sectional area of the aperture is reduced, and the opening degree of the valve is slowly increased for keeping the main water supply flow unchanged.
Because the main water supply regulating valve is the core equipment of a power plant and the valve cage is limited in spare parts at present, the old valve cage with accumulated scale on the surface of the through-flow small hole of the valve cage needs to be effectively cleaned and descaled so as to be reused. The diameter of the opening of the small circulation hole of the valve cage of the main water supply regulating valve is only about 6mm (millimeter), so that the valve cage cannot be descaled by a common mechanical cleaning method, and the valve cage is cleaned by a conventional high-pressure water gun and an ultrasonic method, so that the accumulated scale is still deposited in the hole even though the accumulated scale is loosened a little, the effect is very little, and the accumulated scale cannot be removed.
Disclosure of Invention
To overcome the problems of the related art, a chemical cleaning method for a two-circuit valve cage is provided.
According to an aspect of an embodiment of the present disclosure, there is provided a chemical cleaning method for a two-circuit cage, the method comprising:
soaking and cleaning a two-loop valve cage by using an alkaline solution;
washing the alkaline solution with water to soak the washed two-circuit valve cage;
under the condition of removing alkaline residual solution on the two-loop valve cage, soaking and cleaning the two-loop valve cage by using an acidic solution;
washing the acid solution with water to soak the washed two-circuit valve cage;
passivating the two-loop valve cage by using a passivating agent under the condition of removing an acidic residual solution on the two-loop valve cage;
cleaning the passivated two-loop valve cage by using water until the passivation solution residue on the two-loop valve cage is removed;
and under the condition of removing residual passivating liquid on the two-loop valve cage, drying the two-loop valve cage.
In one possible implementation, a two-circuit cage is cleaned using alkaline solution soak, comprising:
the two-circuit cage is soaked and cleaned with an alkaline solution having a first temperature for a first period of time.
In one possible implementation, the first period of time is between 1.5 hours and 2.5 hours.
In one possible implementation, the first temperature is between 70 degrees celsius and 90 degrees celsius.
In one possible implementation, the alkaline solution is circulated.
In one possible implementation, a two-circuit cage is cleaned using an acidic solution soak, comprising:
soaking and cleaning the two-circuit valve cage by using an acid solution with a second temperature in a second time period.
In one possible implementation, the second period of time is between 8 hours and 12 hours.
In one possible implementation, the second temperature is between 70 degrees celsius and 90 degrees celsius.
In one possible implementation, the acidic solution is circulated.
In one possible implementation, passivating the two-circuit cage with a passivating agent includes:
and passivating the two-circuit valve cage by using a passivating agent in a third time period.
In one possible implementation, the third period of time is between 20 hours and 28 hours.
In one possible implementation, the hydrogen ion concentration index PH of the alkaline solution is between 10 and 11, and the PH of the acidic solution is between 4 and 5.
The invention has the beneficial effects that: this disclosed embodiment is through using alkaline solution to carry out the preliminary treatment to two return circuit valve cages, can effectively get rid of scaling such as two return circuit valve cage surface oil dirt, loose dirt layer and alkali solubles to use acid solution to carry out further cleaning process to two return circuit valve cages after the preliminary treatment, can effectively break down remaining scaling on two return circuit valve cages, can carry out comparatively quick, thorough cleanness to two return circuit valve cages from this, produce mechanical damage to two return circuit valve cages less. In addition, the two-loop valve cage is passivated, so that a protective film is formed on the surface of the cleaned two-loop valve cage, and the two-loop valve cage is effectively protected.
Drawings
FIG. 1 is a flow diagram illustrating a method of chemical cleaning for a two-circuit cage in accordance with an exemplary embodiment.
FIG. 2a is a partial photograph of a two-circuit cage to be cleaned illustrating one application.
FIG. 2b is a partial photograph of a two-circuit cage after being cleaned using the cleaning method of an embodiment of the present disclosure, as shown in an application example.
Detailed Description
The invention is described in further detail below with reference to the figures and the embodiments.
FIG. 1 is a flow diagram illustrating a method of chemical cleaning for a two-circuit cage in accordance with an exemplary embodiment. As shown in fig. 1, the method may include:
102, soaking and cleaning the two-loop valve cage by using an acid solution under the condition of removing the alkaline residual solution on the two-loop valve cage;
103, washing the two-loop valve cage soaked and washed by the acidic solution by using water;
104, passivating the two-loop valve cage by using a passivating agent under the condition of removing the acidic residual solution on the two-loop valve cage;
and 106, drying the two-loop valve cage under the condition of removing the residual passivating liquid on the two-loop valve cage.
In the embodiment of the present disclosure, the alkaline solution may be a sodium hydroxide solution or a potassium hydroxide solution or a mixed solution of multiple alkaline substances, and the composition of the alkaline solution is not limited in the embodiment of the present disclosure, and in a possible implementation manner, the PH of the alkaline solution may be between 8 and 11.
The acidic solution may include a mixed solution of solvents such as phosphoric acid, a surfactant, an inhibitor, an oxygen scavenger, a corrosion inhibitor, etc., and the composition of the acidic solution is not limited in the embodiments of the present disclosure, and in a possible implementation manner, the PH of the acidic solution may be between 4 and 5.
As an example of this embodiment, the two-circuit valve cage to be cleaned may be subjected to water jet cleaning with a high-pressure water gun to remove floating dust on the surface, and may be placed in a cleaning vessel, and an alkaline solution may be injected into the cleaning vessel. The cleaning vessel may, for example, have a heating device therein, which may, for example, heat and maintain the temperature of the alkaline solution at a first temperature, which may be between 70 ℃ (celsius) and 90 ℃, for example, the first temperature may be 80 ℃. The cleaning vessel may further include a liquid circulation device (e.g., a liquid circulation pump) that may circulate the alkaline solution in the cleaning vessel (e.g., the flow rate of the alkaline solution may be 0.7m/s) such that the alkaline solution is in sufficient contact with the two-circuit cage surface to increase the efficiency of the alkaline solution in disrupting scale. The circulating flow of the alkaline solution may be continuously controlled for a first period of time (the first period of time may be between 1.5 hours and 2.5 hours, for example, the first period of time may be 2 hours). Thus, the scale deposits such as oil dirt, loose dirt layers, alkali-soluble substances and the like on the surface of the two-circuit valve cage can be fully dissolved by the alkaline solution. In addition, a filtering device can be arranged, so that impurities dissolved in the alkaline solution can be filtered by using the filtering device when the circulation flow of the alkaline solution is controlled, and the cleaning capacity of the alkaline solution can be well maintained.
After the first time period, the alkaline solution can be discharged from the cleaning container, the two-circuit valve cage is flushed by using water (the water can be domestic water or pure water, and the pH value of the water can be between 6 and 8), for example, a high-pressure water gun can be used for flushing the two-circuit valve cage, so that the alkaline residual solution on the two-circuit valve cage and the collapsed scale are favorably cleared. A PH detection device (e.g., PH paper) may be used to detect the PH of the residual water that has been used to clean the two-circuit cage, which may indicate that the alkaline residual solution is substantially removed if the PH approaches about 7.
In the case of purging the two-circuit cage of alkaline residual solution, the acidic solution may be injected into the purge vessel, the heating device may be used to heat and maintain the temperature of the alkaline solution at a second temperature, which may be between 70 ℃ (celsius) and 90 ℃ (for example, the second temperature may be 80 ℃), and then the liquid circulation device may be used to control the circulating flow of the acidic solution for a second period of time (for example, the flow rate of the acidic solution may be 0.7m/s) to soak and purge the two-circuit cage, which may be between 8 hours and 12 hours. Thus, the acid solution is favorable for fully dissolving the scale remained on the surface of the two-circuit valve cage. In addition, when the circulation flow of the acid solution is controlled, impurities dissolved in the acid solution can be filtered by using the filtering device, and the cleaning capacity of the acid solution can be well maintained.
After a second period of time, the acidic solution may be drained from the wash tank, and the two-circuit valve cage flushed with water. A PH detection device (e.g., PH paper) may be used to detect the PH of the water that has been used to clean the two-circuit cage, which may indicate that the acidic residual solution has been substantially removed if the PH approaches about 7.
In the case of a purge of acidic residual solution on the two-circuit cage, the passivating agent is injected into the purge vessel and the circulation flow may be controlled for a third period of time (which may be between 20 hours and 28 hours, e.g., the third period of time may be 24 hours) to passivate the two-circuit cage.
After a third period of time, the passivating agent may be exhausted from the cleaning tank and the second-circuit cage flushed with water.
The two-circuit cage may be dried (e.g., may be purged for drying using a clean schedule) while the two-circuit cage is purged of residual passivating fluid.
In one example of use, FIG. 2a is a partial photograph of a two-circuit cage to be cleaned as shown in one example of use. FIG. 2b is a partial photograph of a two-circuit cage after being cleaned using the cleaning method of an embodiment of the present disclosure, as shown in an application example. As can be seen by comparing FIG. 2a and FIG. 2b, the cleaned surface of the two-circuit valve cage has no corrosion residues, no secondary corrosion and a complete and compact passivation film. The two-loop valve cage cleaned by the method is replaced into the main water supply regulating valve 2ARE031VL, the opening degree of the 2ARE031VL is reduced from about 67% to about 47% after the unit is restarted, the opening degree is reduced by about 20%, the normal opening degree level of the main water supply regulating valve is restored, and the safe and stable operation of the unit is effectively guaranteed.
In a possible implementation manner, the corrosion rate monitoring can be performed in the chemical cleaning process, and the corrosion rate monitoring can be determined by adopting a metal test piece weight loss method, wherein the material of the metal test piece can be the same as that of the two-loop valve cage to be cleanedOr close to that, the uniform corrosion rate of the metal test piece is 0.0062g/m2H, less than 2g/m2H, meeting the technical requirements of chemical cleaning of industrial equipment (HG/T2387-2007 quality standard of chemical cleaning of industrial equipment).
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. It is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
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