Control method for use of fine processing system filter

Abstract

The invention belongs to the technical field of water treatment, and particularly relates to a control method for use of a fine treatment system filter. And slowly opening a valve of the standby filter, and connecting the cation bed filter and the mixed bed filter into a fine treatment system. And controlling the flow of the filter put into operation through the drop value of the flow of the filter in operation. When the flow values of the other four running filters are respectively reduced by 2 kg / s, namely the total flow is reduced by 8 kg / s, the valve adjusting operation of the filter is suspended, waiting is carried out for 1 h, then the adjusting valves are continuously opened until the flows of the five filters are equal, and then the failed filter is withdrawn. The slow feeding process eliminates the influence of the switching operation of the cation bed filter and the mixed bed filter of the condensate polishing system on the water quality of the secondary loop of the unit; and the slow casting operation parameters are accurately and reliably controlled.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and in particular relates to a control method for putting a filter of a fine treatment system into use. Background Art

[0002] The first phase of the Jiangsu Nuclear Power Co., Ltd. project is designed and equipped by Russia. It consists of two VVER-1000 units with a total rated power of 2×1060MW and a design life of 40 years. The two units are each equipped with a set of condensate polishing equipment, which is used to purify the condensate water quality, remove metal impurities such as metal corrosion products and ionic impurities, and meet the requirements of unit feed water and steam generator sewage. The condensate polishing system includes a mechanical filtration system (five cation bed filters), an ion exchange system (five mixed bed filters), an in vitro regeneration system, and a wastewater discharge system.

[0003] The cation bed filter and mixed bed filter of the condensate polishing system are cylindrical filters with a diameter of 3.4m. In normal operation, four rows are in operation and one row is in standby. Figure 1 . The condensate in condensers No. 1 to No. 4 flows through four rows of operating cationic beds and mixed beds for treatment, and then returns to the condensate system. The fine treatment cationic bed filter is filled with 14.6 cubic meters of resin. The water quality at the outlet of the cationic bed filter should meet the requirements that the conductivity is not greater than 1μS / cm, the sodium ion concentration is not greater than 2μg / L, and the operating pressure difference of the cationic bed filter is greater than 0.30Mpa. It is considered to be failed, and the spare fine treatment filter is put into operation, and then the failed fine treatment cationic bed filter is shut down for regeneration. The fine treatment cationic bed filter is regenerated in vitro, and the system is equipped with a cationic bed filter regeneration filter. The mixed bed filter of the fine treatment system is filled with 16.2 cubic meters of resin, including 9.8 cubic meters of anionic resin, 4.8 cubic meters of cationic resin, and 1.6 cubic meters of inert resin. When the operating conductivity of the mixed bed filter of the fine treatment system is greater than 0.15μS / cm, the silicon concentration is not greater than 20μg / L, and the operating pressure difference of the mixed bed filter is greater than 0.25Mpa, it is considered to be failed, and the spare mixed bed filter of fine treatment is put into operation, and then the failed mixed bed filter of fine treatment is taken out of operation for regeneration. The mixed bed filter of fine treatment is in vitro regenerated, and the system is equipped with a mixed bed filter regeneration filter. Regeneration, the exchanged exhausted ion exchange resin is exchanged with a suitable acid, alkali or salt solution to convert the resin into the required form. The chemical reagents used for the regeneration of the cationic bed filter and the mixed bed filter of the fine treatment system are hydrochloric acid and sodium hydroxide. Before the spare cationic bed filter and the mixed bed filter are put into operation, they need to be flushed with deionized water, and they can be put into operation only after the flushing reaches the index.

[0004] The requirements for the secondary circuit water quality of the unit include the secondary circuit control index and the secondary circuit diagnostic index. The secondary circuit control index is the quality index of the steam generator feed water and wastewater. Maintaining these indexes within the allowable range can ensure the safety and reliability of the steam generator and secondary circuit equipment, without reducing the economic efficiency, and guarantee the operation of the design life; the secondary circuit diagnostic index refers to providing the power station personnel with supplementary information on the correctness of the water chemical conditions of the steam generator feed water and wastewater, saturated steam, and auxiliary systems. Deviations from the index indicate that the process system that guarantees the water chemical conditions is not operating normally.

[0005] When one or more water quality control indicators of the secondary circuit steam generator feed water and steam generator wastewater deviate from the standard, and the indicators fail to return to normal within the time specified by the standard; or when the pH value, iron, and copper diagnostic indicators of the steam generator feed water deviate and fail to return to normal within 30 days from the discovery of the deviation, the unit needs to take corresponding state change operations, and this situation is called secondary circuit chemical condition damage. The unit has more requirements for water quality during startup, operation, maintenance and other different working conditions. Secondary circuit chemical condition damage will cause the unit power to be reduced or even shut down.

[0006] During the power operation of the units, the conductivity of the steam generator wastewater, chloride ions and the pressure of the secondary circuit of both units fluctuated to varying degrees. When the operators put the fine treatment cation bed filter into operation, the water quality and pressure of the secondary circuit fluctuated, which affected the stable operation of the units. The situation is as follows:

[0007] (1) The cation bed filter and mixed bed filter of the fine treatment system are in normal operation, but the water quality of the steam generator wastewater fluctuates and deviates:

[0008] During the full-power operation of the unit, the condensate polishing cationic bed filter runs to the end point, and the regenerated cationic bed filter needs to be put into use and the failed cationic bed filter needs to be withdrawn. During this operation, it was found that with the rapid increase in the flow through the newly put into the cationic bed filter, the conductivity of the sewage increased rapidly, and at the same time, the chloride ions were sampled and monitored, and the water quality deviated. In order to confirm the conclusion that the cationic bed filter of the condensate polishing system caused the water quality fluctuation of the steam sewage during the switching, the inventor stopped all other operations of the secondary circuit before the switching of the cationic bed filter to verify that the conclusion was correct. At the same time, it was also verified that similar water quality deviations occurred during the switching of the mixed bed filter.

[0009] During the startup of the unit, the secondary circuit is put into operation during the power increase period, and the water quality fluctuation increases. At this time, due to the switching operation of the cation bed filter and the mixed bed filter of the fine treatment system, there will be superimposed fluctuations in water quality, and water quality deviation has occurred.

[0010] The inventors have analyzed the system equipment, operating parameters, etc. The condensate polishing treatment cationic bed filter and mixed bed filter are column tanks with a diameter of 3.4m. The water distribution device for the water inlet is a cup-in-cup type. There are 840 holes with a diameter of 15mm on the inner cup and 1518 holes with a diameter of 20mm on the outer cup. The system is designed to have an operating flow rate of 250kg / s and a pressure of about 1.0-1.1Mpa. The flushing flow rate of the cationic bed filter before commissioning is 13.9kg / s, and the flushing flow rate of the mixed bed filter before commissioning is 27.3kg / s, and the pressure is less than 0.70-0.72Mpa. Since the pressure and flow of flushing water are much smaller than the pressure and flow of condensate water during operation, there will be uneven water distribution. After flushing, there will be very little regeneration agent remaining in the filter, and the flushing water is desalted water, which is slightly worse than the condensate water. Therefore, when the cation bed filter and mixed bed filter are flushed and put into operation, the water in the filter enters the secondary circuit system, causing the water quality of the steam generator to fluctuate and deviate into the danger zone.

[0011] At present, there are two water sources for flushing the fine treatment system before commissioning at home and abroad. One is desalted water, that is, the desalted water of the unit is used for flushing; the other is condensed water, that is, the condensed water is used for circulating flushing of the filter. No matter which water source is used, the quality of the water in the filter is lower than that of the condensed water when it is connected to the condensate water system. After the filter is connected, it will more or less interfere with the water quality of the secondary circuit, causing fluctuations or even deviations.

[0012] (2) The cation bed filter and mixed bed filter of the fine treatment system are in normal operation, and the secondary circuit pressure and water quality fluctuate:

[0013] When the condensate polishing cation bed filter and mixed bed filter are about to reach the end of their operation, the spare filter is ready to be connected to the condensate system. During the opening of the spare filter valve, the pressure of the condensate system fluctuates, endangering the safe operation of the condensate pump.

[0014] The inventors analyzed and checked the system equipment structure and on-site pipeline layout. It was found that during the operation of the fine treatment cation bed filter and mixed bed filter from failure to standby and commissioning, compressed air was used to pour resin and mix fat. These operations would cause air to enter the system. Although water filling and exhaust were involved in subsequent operations, a small amount of air entered the condensate water system, causing fluctuations in the secondary circuit pressure. Since there were gases such as carbon dioxide in the air, after the air entered the system, the water quality of the secondary circuit also fluctuated and entered the danger zone.

[0015] (3) The condensate polishing cation bed filter and mixed bed filter were put into operation after overhaul, causing the water quality of the unit to deviate:

[0016] The condensate polishing mixed bed filter has a regular maintenance project. Before the maintenance, the mixed bed filter is in standby state. For regular maintenance, the resin in the mixed bed filter is transported to the regeneration filter, and the resin is returned to the mixed bed after the maintenance. After the mixed bed is put into operation, the steam generator sewage conductivity and sulfate ion increase, while the cation is not high, reaching 2.25h. This deviation time reaches 24 hours, and it is required to reduce the power to the minimum monitorable power.

[0017] The inventor analyzed and investigated the on-site situation, and checked from aspects such as system operation mode, filter body, resin quality and regeneration, resin degradation and reproduction of water quality fluctuations, and instrumentation. It was finally confirmed that during the maintenance of the mixed bed filter, the person in charge of the work was also responsible for grease-related work. He brought grease (containing organic sulfate) into the filter, causing an increase in sulfate after the filter was put into use, resulting in water quality deviation.

[0018] (4) When the condensate polishing cation bed filter and mixed bed filter are put into operation for flushing, the pressure of the condensate system fluctuates and the standby pump is started by interlock.

[0019] The flushing operation of the condensate polishing cation bed filter and mixed bed filter is to operate the valve switch in the central control room. During a cation bed flushing operation, after the operator opens the filter drain valve, the condensate system pressure drops sharply and the standby pump starts.

[0020] The inventor investigated the cause and found that since the control of the relevant valves of the cation bed filter and the mixed bed filter are on the central control computer, the control screens of the five cation beds are the same, and the control screens of the five mixed beds are also the same. The operator went to the wrong interval during the flushing operation and opened the drain valve of the running cation bed filter, causing condensate to be discharged into the wastewater tank and pressure and flow loss in the condensate system. Summary of the invention

[0021] The purpose of the present invention is to provide a control method for the commissioning of filters in a fine treatment system to eliminate the influence of operations such as the commissioning of the fine treatment system on the water quality of the secondary circuit of the unit, specifically as follows: to solve the problem of fluctuation and deviation of wastewater discharged from the steam generator when the cationic bed filter and the mixed bed filter of the fine treatment system are put into normal operation; to solve the problem of fluctuation of pressure and water quality of the secondary circuit when the cationic bed filter and the mixed bed filter of the fine treatment system are put into normal operation; to solve the problem of deviation of water quality of the unit caused by the commissioning of the condensate polishing cationic bed filter and the mixed bed filter after maintenance; to solve the problem of pressure fluctuation of the condensate system and start-up of the standby pump when the condensate polishing cationic bed filter and the mixed bed filter are put into operation and flushed.

[0022] In order to achieve the above object, the technical solution adopted by the present invention is:

[0023] A control method for putting filters of a fine treatment system into use includes slowly opening the valve of a standby filter and connecting a cation bed filter and a mixed bed filter to the fine treatment system.

[0024] The flow rate of the operating filter is controlled by the drop value of the filter flow rate during operation.

[0025] Pulse open the inlet regulating valve of the standby filter. When the flow values ​​of the other four running filters drop by 2kg / s respectively, that is, the total flow drops by 8kg / s, suspend the valve adjustment operation of the filter in use, wait for 1 hour, and then continue to open the regulating valve until the flow rates of the five filters are equal, and then exit the failed filter.

[0026] During the overhaul of the unit, the cation bed that has reached 30% of the cumulative water production will be regenerated, and the mixed bed that has reached 30% of the cumulative water production and has resin output operation will be regenerated in preparation for startup.

[0027] If the filter is not put into operation after flushing, it needs to be flushed again when it is put into operation again.

[0028] The flushed cation bed filter and mixed bed filter are pressurized and the system is exhausted during the pressurization process.

[0029] For any overhauled filter, after the overhaul is completed, the filter needs to be flushed and sampled. The resin can only be transported back to the overhauled filter after the sampling is qualified.

[0030] The valves of the running filter are controlled. Except for the inlet and outlet valves of the filter which are in the operable state, all other valves are set to the prohibited operation state.

[0031] If the filter is not put into operation within 3 hours after flushing, it needs to be flushed again when it is put into operation again.

[0032] The unit's continuously running make-up water system is used to pressurize the flushed cation bed filter and mixed bed filter to 0.7Mpa, and the system is vented during the pressurization process.

[0033] The beneficial effects achieved by the present invention are:

[0034] The slow injection process of the present invention eliminates the influence of the switching operation of the cationic bed filter and the mixed bed filter of the condensate polishing system on the water quality of the secondary circuit of the unit; the slow injection operation parameter control is accurate and reliable; during the major and minor repairs of the unit, the states of the polishing cationic bed filter and the mixed bed filter are controlled to eliminate the influence of the switching of the polishing filter on the water quality of the secondary circuit; the time interval between flushing and commissioning of the condensate polishing cationic bed filter and the mixed bed filter is controlled to reduce the influence of water in the filter on the water quality of the secondary circuit; the pressure boost control before commissioning of the condensate polishing cationic bed filter and the mixed bed filter reduces the influence of the switching of the filter on the pressure of the unit; the commissioning control after the overhaul of the condensate polishing cationic bed filter and the mixed bed filter eliminates the influence of the overhaul work on the water quality of the secondary circuit of the unit; the control of the system valves after the commissioning and flushing of the condensate polishing cationic bed filter and the mixed bed filter eliminates human errors caused by going into the wrong interval. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is the flow chart of the condensate polishing system. DETAILED DESCRIPTION

[0036] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] (1) The cation bed filter and mixed bed filter of the fine treatment system adopt the slow injection method

[0038] A new method of putting into use a cation bed filter and a mixed bed filter in a fine treatment system, namely slow putting into use, is invented.

[0039] (2) Control method of using slow injection method for cation bed filter and mixed bed filter in fine treatment system

[0040] According to the structure of the system equipment, the specific parameters of slow release are determined through experimental verification.

[0041] (3) Control of the interval between flushing and commissioning of the cation bed filter and mixed bed filter in the fine treatment system

[0042] In order to reduce the impact of water stored in the filter during its operation on the water quality of the secondary circuit, the operation time is limited after the filter is flushed. If the time requirement is exceeded, the resin in the filter needs to be flushed again when it is put into operation again.

[0043] (4) Control of cation bed filters and mixed bed filters in the fine treatment system during unit overhaul

[0044] In order to avoid switching the cation bed filter and mixed bed filter of the fine treatment system during the unit startup process, the cation bed and mixed bed whose cumulative water production reaches a certain value are controlled during the unit overhaul.

[0045] (5) Pressure boost and exhaust control before commissioning of cation bed filter and mixed bed filter in fine treatment system

[0046] According to the system operating parameters, before the cation bed filter and mixed bed filter of the fine treatment system are put into operation, the original equipment of the system is used to increase the pressure boosting and exhaust operations of the filters in use.

[0047] (6) Inspection and control of condensate polishing cation bed filter and mixed bed filter after overhaul

[0048] After the condensate polishing treatment cation bed filter and mixed bed filter have been overhauled, water quality testing should be added and resin can be delivered only after the test is qualified.

[0049] (1) The cation bed filter and mixed bed filter of the fine treatment system adopt the slow injection method

[0050] The inventor analyzed that the cause of the water quality fluctuation in the secondary circuit system is the water access system in the cation bed filter and the mixed bed filter of the fine treatment system. If the valve of the spare filter is opened slowly and this part is slowly connected to the system, the fluctuation of water quality can be eliminated, that is, the spare filter is put into use in a "slow investment" manner.

[0051] The control method of the slow injection method for the cation filter and mixed bed filter of the fine treatment system is as follows: the normal operation of the system is that four columns are running and one column is spare, the maximum flow rate of each column is 250kg / s, and the dead zone value of the flow meter is 25-30kg / s, so when the flow rate is lower than 30kg / s, the flow meter display is inaccurate. The inventor verified this conclusion through experiments, so it is not possible to control the injection flow rate by the flow meter of the spare filter.

[0052] In order to accurately control the flow rate of slow injection, the inventor controls the flow rate of the filter in operation by the drop value of the flow rate of the running filter. Pulse open the inlet regulating valve of the standby filter. When the flow values ​​of the other four running filters drop by 2kg / s each, that is, the total flow rate drops by 8kg / s, suspend the valve adjustment operation of the filter in operation, wait for 1 hour, and then continue to open the regulating valve until the flow rates of the five filters are equal, and then exit the failed filter.

[0053] (2) Control of cation bed filters and mixed bed filters in the fine treatment system during the major and minor repairs of the unit

[0054] In order to avoid switching the cation bed filter and mixed bed filter of the fine treatment system during the startup of the unit, during the major and minor overhauls of the unit, the cation bed that has reached 30% of the cumulative water production will be regenerated, and the mixed bed that has reached 30% of the cumulative water production and has resin output operation will be regenerated in preparation for startup.

[0055] (3) Control method for flushing and commissioning time interval of cation bed filter and mixed bed filter in fine treatment system

[0056] In order to reduce the impact of water stored in the filter during its service life on the water quality of the secondary circuit, if the filter is not put into operation within 3 hours after being flushed, it needs to be flushed again when it is put into operation again.

[0057] (4) Pressure boost and exhaust control before commissioning of cation bed filter and mixed bed filter in fine treatment system

[0058] After flushing the cation bed filter and mixed bed filter of the fine treatment system, the continuously running make-up water system of the unit is used to increase the pressure of the flushed filter to 0.7Mpa. During the pressure increase process, the high-point exhaust valve of the system is opened to exhaust the system.

[0059] (5) Inspection and control of condensate polishing cation bed filter and mixed bed filter after overhaul

[0060] During the overhaul of the condensate polishing cation bed filter and mixed bed filter, multiple personnel will enter the filter. Because the overhaul personnel were also responsible for the grease-related work of a certain system, the personnel brought the grease into the filter, causing the sulfate radical to exceed the limit. To avoid similar situations, for any overhauled filter, after the overhaul, the filter needs to be flushed and sampled. Only after the sampling is qualified can the resin be transported back to the overhauled filter.

[0061] (6) Control of the operation of condensate polishing cation bed filter and mixed bed filter after overhaul

[0062] The control screens of the five cation bed filters in the fine treatment system are exactly the same, and the control screens of the five mixed bed filters are also exactly the same. In order to prevent operators from going to the wrong interval, the inventor controls the valves of the running filters. Except for the inlet and outlet valves of the filters which are in an operable state, the other ten or so valves are set to a prohibited operation state to prevent them from being opened by mistake due to going to the wrong interval, which would threaten the stable operation of the unit.

Claims

1. A control method for putting a filter into use in a fine treatment system, characterized in that: Slowly open the valve of the standby filter and connect the cation bed filter and mixed bed filter to the fine treatment system.

2. The control method for putting the filter of the fine treatment system into use according to claim 1 is characterized in that: The flow rate of the operating filter is controlled by the drop value of the filter flow rate during operation.

3. The control method for putting the filter of the fine treatment system into use according to claim 2 is characterized in that: Pulse open the inlet regulating valve of the standby filter. When the flow values ​​of the other four running filters drop by 2kg / s respectively, that is, the total flow drops by 8kg / s, suspend the valve adjustment operation of the filter in use, wait for 1 hour, and then continue to open the regulating valve until the flow rates of the five filters are equal, and then exit the failed filter.

4. The control method for putting the filter of the fine treatment system into use according to claim 1 is characterized in that: During the overhaul of the unit, the cation bed that has reached 30% of the cumulative water production will be regenerated, and the mixed bed that has reached 30% of the cumulative water production and has resin output operation will be regenerated in preparation for startup.

5. The control method for putting the filter of the fine treatment system into use according to claim 1 is characterized in that: If the filter is not put into operation after flushing, it needs to be flushed again when it is put into operation again.

6. The control method for putting the filter of the fine treatment system into use according to claim 1 is characterized in that: The flushed cation bed filter and mixed bed filter are pressurized and the system is exhausted during the pressurization process.

7. The control method for putting a filter of a fine treatment system into use according to claim 1, characterized in that: For any overhauled filter, after the overhaul is completed, the filter needs to be flushed and sampled. The resin can only be transported back to the overhauled filter after the sampling is qualified.

8. The control method for putting a filter of a fine treatment system into use according to claim 1, characterized in that: The valves of the running filter are controlled. Except for the inlet and outlet valves of the filter which are in the operable state, all other valves are set to the prohibited operation state.

9. The control method for putting the filter of the fine treatment system into use according to claim 5, characterized in that: If the filter is not put into operation within 3 hours after flushing, it needs to be flushed again when it is put into operation again.

10. The control method for putting the filter of the fine treatment system into use according to claim 6, characterized in that: The unit's continuously running make-up water system is used to pressurize the flushed cation bed filter and mixed bed filter to 0.7Mpa, and the system is vented during the pressurization process.

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