Nuclear power plant condensate treatment system and method

Abstract

The present disclosure relates to the technical field of nuclear power plant condensate water, and provides a nuclear power plant condensate water treatment system and method. The system comprises a control unit and an EDI treatment circuit connected in communication. The EDI treatment circuit comprises a pre-filter group, a flow distribution unit and a plurality of EDI treatment sub-units connected in sequence. The control unit is configured to automatically configure the number of EDI treatment sub-units to be put into use according to the flow of condensate water to be treated by using time sequence control and bubble sorting. The system can partially or completely replace the ion exchange process to treat the condensate water of the nuclear power plant, greatly simplifying the process and equipment of the condensate water polishing treatment system, without using regenerative chemical reagents, and widening the background alkali concentration and use temperature of the condensate water, improving the availability of the condensate water polishing treatment system, and reducing the possibility of the polishing treatment system being unavailable due to incomplete resin regeneration or other processes bringing impurities into the secondary loop cycle, the background alkali concentration of the condensate water, and the condensate water temperature exceeding the use limit of the purification system.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of nuclear power plant condensate water treatment, in particular, to a nuclear power plant condensate water treatment system and method. BACKGROUND

[0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute the prior art.

[0003] The nuclear power plant condensate polishing system removes ionic impurities and corrosion products through purification treatment process during unit startup, shutdown and condenser leakage caused by abnormal secondary circuit water quality, maintains the secondary circuit water quality, and is crucial to the reliability and availability of the secondary circuit system.

[0004] The conventional condensate polishing system uses ion exchange treatment process to purify condensate water, and the purification process is pre-positioned positive bed-resin trap-high speed mixed bed-resin trap-precision filter-condensate water booster pump. At the same time, the condensate polishing system is equipped with a regeneration unit and a regeneration auxiliary unit for resin regeneration of failed resin bed. Different types of alkali reagents are used in each power plant, and the regeneration process is also different. The entire condensate polishing system is equipped with ion exchange bed, regeneration metering device, acid and alkali storage tank, compressed air tank, water tank, pump, fan, wastewater treatment equipment and other devices. The treatment process has high requirements for resin loading ratio, regeneration process and control, resin delivery, etc. Once there is a deviation in a certain link, it will affect the condensate polishing effect, or resin leakage will occur, affecting the secondary circuit water quality, and a large amount of acid and alkali chemicals are used in the regeneration process, which has adverse effects on the environment.

[0005] The inventors found in the research that the condensate polishing system using ion exchange treatment currently has the following problems: In order to reduce the amount of secondary circuit corrosion products, nuclear power plants use high-concentration alkali reagents to control the pH value of the secondary circuit, which causes the condensate polishing resin to fail easily, and the bed body in the regeneration cannot be used. If the secondary circuit water quality is continuously poor, the resin failure rate will increase, and the regeneration speed cannot meet the system operation, so the condensate polishing system cannot be put into operation as needed. In addition, due to the increase in temperature in summer in recent years, the temperature of the plant water increases, and the temperature of the medium entering the condensate polishing system is close to the limit of the condensate treatment system, which greatly reduces the availability of the condensate polishing system. SUMMARY

[0006] The present disclosure proposes a nuclear power plant condensate water treatment system and method to solve the above problems, which can partially or completely replace ion exchange process to treat nuclear power plant condensate water, greatly simplify the process and equipment of condensate polishing system, and does not need to use regeneration chemical reagent, the background alkali concentration of condensate water and the use temperature can be widened, the availability of condensate polishing system is improved, and the possibility of polishing system being unavailable due to incomplete resin regeneration or other processes bringing impurities into the secondary loop cycle, background alkali concentration of condensate water, and condensate water temperature exceeding the use limit of purification system is reduced.

[0007] In order to achieve the above-mentioned purpose, the present disclosure adopts the following technical solutions:

[0008] One or more embodiments provide a nuclear power plant condensate water treatment system, comprising a control unit and an EDI treatment loop connected in communication, the EDI treatment loop comprising a pre-filter group, a flow distribution unit and a plurality of EDI treatment sub-units connected in sequence;

[0009] The control unit is configured to automatically configure the number of EDI treatment sub-units to be put into according to the flow of condensate water to be treated, using time sequence control and bubble sort.

[0010] One or more embodiments provide a control method of a nuclear power plant condensate water treatment system based on the above, comprising the following steps:

[0011] Obtain the cumulative running time of each EDI treatment sub-unit, sort the running time from small to large, and set the priority of each EDI treatment sub-unit from large to small according to the sorting;

[0012] Obtain the total flow of condensate water to be treated;

[0013] Determine the number N of EDI treatment sub-units to be turned on according to the total flow of condensate water and the treatment flow range of a single EDI treatment sub-unit;

[0014] Control the first N EDI treatment sub-units with high priority to be turned on.

[0015] Compared with the prior art, the present disclosure has the following beneficial effects:

[0016] In the present disclosure, the EDI treatment loop is provided, which can partially or completely replace ion exchange process to treat nuclear power plant condensate water, greatly simplify the process and equipment of condensate polishing system, and does not need to use regeneration chemical reagent, the background alkali concentration of condensate water and the use temperature can be widened, the availability of condensate polishing system is improved, and the possibility of polishing system being unavailable due to incomplete resin regeneration or other processes bringing impurities into the secondary loop cycle, background alkali concentration of condensate water, and condensate water temperature exceeding the use limit of purification system is reduced.

[0017] Advantages of the present disclosure and additional aspects will be more fully understood in view of the following detailed description. BRIEF DESCRIPTION OF DRAWINGS

[0018] The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the present disclosure, illustrate preferred embodiments of the present disclosure, and to explain the principles of the present disclosure.

[0019] Figure 1 is a condensate treatment system block diagram of the EDI treatment circuit based replacement of ion exchange treatment of embodiment 1 of the present disclosure;

[0020] Figure 2 is a structure schematic diagram of a single filter of the pre-filter group of embodiment 1 of the present disclosure;

[0021] Figure 3 is a structure schematic diagram of a flow distribution unit of embodiment 1 of the present disclosure;

[0022] Figure 4 is a condensate treatment system block diagram of the EDI treatment circuit based partial replacement of ion exchange treatment of embodiment 1 of the present disclosure;

[0023] Wherein: 1, cylinder, 2, filter cartridge, 3, filtrate inlet, 4, filtrate outlet, 5, first blow-off port, 6, second blow-off port, 7, flange type top cover. DETAILED DESCRIPTION

[0024] The present disclosure will be further described with reference to the drawings and embodiments.

[0025] It should be noted that the following detailed description is exemplary in nature and is intended to provide further description of the present disclosure. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this present disclosure belongs.

[0026] It is to be noted that the terms used herein are merely for the purpose of describing particular embodiments and are not intended to limit exemplary embodiments according to the present disclosure. As used herein, the singular forms are intended to include the plural forms, unless the context clearly indicates otherwise, and it will be further understood that the terms "comprise" and / or "include" when used herein specify the presence of stated features, steps, operations, devices, components and / or combinations thereof. It should be noted that the various embodiments in the present disclosure and the features in the embodiments can be combined with each other without conflict, and the embodiments will be described in detail below with reference to the accompanying drawings.

[0027] Embodiment 1

[0028] In one or more embodiments of the technical solutions disclosed, Figures 1 to 4As shown in the figure, a nuclear power plant condensate water treatment system includes a control unit and an EDI treatment circuit connected in communication, the EDI treatment circuit including a pre-filter group, a flow distribution unit and a plurality of EDI treatment sub-units connected in sequence.

[0029] The control unit is configured to automatically configure the number of EDI treatment sub-units to be put into use according to the flow of condensate water to be treated, using time sequence control and bubble sort.

[0030] In this embodiment, the EDI treatment circuit is provided to partially or completely replace the ion exchange process for treating condensate water in a nuclear power plant, greatly simplifying the process and equipment of the condensate water polishing treatment system, and without the need to use regenerating chemical reagents, the background alkali concentration and use temperature of the condensate water can be widened, improving the availability of the condensate water polishing treatment system, and reducing the possibility of the polishing treatment system being unavailable due to incomplete resin regeneration or other processes bringing impurities into the secondary circuit circulation, the background alkali concentration of the condensate water, and the condensate water temperature exceeding the use limit of the purification system.

[0031] Since the operating temperature of the condensate water is 45-47℃, which is higher than the use temperature of the ordinary electric desalting (40℃), in this embodiment, the EDI treatment sub-unit can optionally use an electric desalting EDI membrane stack that can withstand the set temperature, avoiding the increase of devices such as heat exchangers due to process replacement, and simplifying the system design. The packed negative resin, anion exchange membrane and sealing material of the EDI device are all temperature-resistant.

[0032] The EDI treatment circuit can completely or partially replace the ion exchange treatment.

[0033] As shown in the figure, the EDI treatment circuit includes a pre-filter group, a flow distribution unit and a plurality of EDI treatment sub-units. Figure 1 As shown in the figure, the EDI treatment circuit completely replaces the ion exchange process (i.e. a full-flow treatment system), the input interface of the EDI treatment circuit is connected to the outlet pipeline of the condensate water pump, after entering the EDI process treatment, it is delivered back to the secondary circuit through the condensate water booster pump to the main pipeline of the feedwater.

[0034] Optionally, the EDI treatment circuit includes a pre-filter group, a flow distribution unit and a plurality of EDI treatment sub-units.

[0035] Optionally, the control unit can use a PLC control cabinet.

[0036] In some embodiments, the pre-filter group is a one-to-one backup double-column setting, each column including a coarse filter and a fine filter connected in sequence.

[0037] Optionally, the coarse filter can use a 5μm coarse filter cartridge, and the fine filter can use a 0.1μm filter cartridge.

[0038] Further, the structures of the coarse filter and the fine filter provided can be the same, and the filters use an integrated filter basket structure, which can be as shown in the figure. Figure 2As shown, it includes a cylinder 1, a filter cartridge 2 disposed inside the cylinder 1, a filter element disposed inside the filter cartridge 2, a filtrate inlet 3 disposed on the side of the cylinder 1, the filtrate inlet 3 being connected to and communicating with the gap between the cylinder 1 and the filter cartridge 2; a filtrate outlet 4 and a first drain port 5 disposed at the bottom end of the filter cartridge 1, and a second drain port 6 disposed on the pipe of the filtrate outlet 4.

[0039] Specifically, the filtrate outlet 4 is connected to the process pipeline and is used to discharge the filtered condensate; a second drain port 6 is provided on the filtrate outlet 4 to drain the condensate in the outlet 4 pipeline when the filter element is replaced; the first drain port 5 is connected to the center of the filter element inside the filter cartridge 2 and is used to drain the condensate in the filter when the filter element is replaced.

[0040] Optionally, a flange-type top cover 7 can be detachably installed on the upper end of the filter cartridge 1;

[0041] When in use, if the filter element pressure difference exceeds the limit, the entire filter element can be replaced. During normal filtration, the filter cartridge and filter element are installed inside the cartridge, and the flange top cover 7 is kept tight. After the filter element pressure difference exceeds the limit, open the flange top cover 7, lift the filter cartridge and filter element 2 as a whole, and replace the filter element.

[0042] In some embodiments, the flow distribution unit includes a main pipe and EDI processing subunit pipes; a first flow monitoring device is installed on the main pipe, and a control valve and a second flow monitoring device are installed on each EDI processing subunit pipe; the first flow monitoring device, the control valve, and the second flow monitoring device are respectively communicatively connected to the control unit. The control unit acquires the data collected by the first flow monitoring device and the second flow monitoring device, and controls the valve to operate, thereby enabling the switching of the EDI processing subunits.

[0043] Optionally, the control valves on each EDI processing subunit pipeline include isolation valves and flow control valves; the first flow monitoring device and the second flow monitoring device are configured as flow meters.

[0044] like Figure 3 As shown, a flow meter F11, an isolation valve for EDI processing subunit 1, and a flow control valve for EDI processing subunit 1 are installed on the pipeline connected to EDI processing subunit 1; a flow meter F12, an isolation valve for EDI processing subunit 2, and a flow control valve for EDI processing subunit 2 are installed on the pipeline connected to EDI processing subunit 2; and a flow meter F13, an isolation valve for EDI processing subunit 3, and a flow control valve for EDI processing subunit 3 are installed on the pipeline connected to EDI processing subunit 3.

[0045] The main pipe is configured with two parallel branches, such as... Figure 3As shown, an isolation valve, a coarse filter MT01A and a fine filter MT02A and a differential pressure gauge PD01 are arranged on each branch, and the two ends of the coarse filter MT01A and the fine filter MT02A are respectively provided with a differential pressure gauge PD01.

[0046] The mother pipe of the flow distribution unit is provided with two parallel branches, and each branch is provided with a filter sequence. When differential pressure alarm of a column of filters occurs, the other column of filters is put into use to avoid system shutdown.

[0047] Optionally, each EDI processing subunit includes a plurality of EDI membrane stacks.

[0048] The flow distribution unit receives the distribution control signal of the control unit to control the number of EDI processing subunits to be put into use.

[0049] Specifically, to realize intelligent distribution of flow, the control unit is configured to perform the following processes:

[0050] According to the mother pipe flow, the number of EDI processing subunits to be put into use and the number of EDI membrane stacks in the EDI processing subunits to be put into use are automatically configured.

[0051] Further, the control unit can also be configured to automatically power off and protect the EDI processing subunits when the mother pipe flow is lower than the minimum running flow of the EDI processing subunits.

[0052] Further, the control unit can also be configured to determine the EDI membrane stack to be put into use in priority by accumulating the running time of each EDI membrane stack, balance the running time of the EDI membrane stacks, and prolong the service life of the EDI membrane stacks.

[0053] Specifically, the EDI membrane stack with short running time has high priority, so that each EDI membrane stack can have time to run, the running time is evenly distributed, and the single EDI membrane stack is avoided to be idle.

[0054] Further, the control unit can also be configured to adopt a mode of water circulation without power supply to continue to wet maintain the EDI membrane stacks when the condensate polishing system is not put into use for a long time.

[0055] The flow distribution unit measurement and control signal is provided with an interface with the local PLC cabinet and the power plant PLC system.

[0056] The number of EDI processing subunits can be configured according to the system processing flow.

[0057] In some embodiments, each EDI processing subunit comprises an EDI power supply, EDI membrane stack concentrated water inlet pipeline, concentrated water flow regulating valve, concentrated water pressure difference meter, and according to the flow distribution unit control signal, automatically put into the required number of subunits and the number of EDI membrane stacks. Specifically, the concentrated water flow regulating valve is controlled by the flow control signal to control the operation of the EDI, and each membrane stack hose is connected to the process pipeline.

[0058] The control unit adopts time sequence control and bubble sorting for the flow distribution of the EDI processing subunit, and the control method is as follows:

[0059] Step 1, obtain the cumulative running time of each EDI processing subunit, sort the running time from small to large, and set the priority of each EDI processing subunit from large to small according to the sorting;

[0060] Step 2, obtain the total flow of the condensate water to be processed;

[0061] Step 3, according to the total flow of the condensate water and the processing flow range of a single EDI processing subunit, determine the opening number N of the EDI processing subunit to be opened;

[0062] Step 4, according to the opening number, control the opening of the N EDI processing subunits with high priority.

[0063] Further, when it is detected that the total flow of the condensate water is reduced, after step 1 is performed, the EDI processing subunit in operation is sequentially closed according to the priority from small to large.

[0064] In this embodiment, three EDI processing subunits are taken as an example to illustrate the above process.

[0065] (1) Assuming that the processing flow of a single EDI processing subunit is A1, and the maximum flow is A2; after step 1 is performed, it is obtained that the running time of EDI processing subunit 1 < the running time of EDI processing subunit 2 < the running time of EDI processing subunit 3, i.e. the priority of EDI processing subunit 1 > the priority of EDI processing subunit 2 > the priority of EDI processing subunit 3.

[0066] (2) When the total flow of the condensate water to be processed by the EDI processing circuit is less than A1, the EDI processing subunit is not powered on;

[0067] (3) When the medium flow to be processed by the EDI processing circuit is ≥ A1 and does not exceed A2, EDI processing subunit 1 is put into operation, and A2 ≥ 2 × A1;

[0068] (4) When the medium flow rate required by the EDI processing loop is ≥ A2, the EDI processing subunit 2 is put into operation, at this time, the inlet flow control valve is controlled by the flow distribution unit to keep the flow rate entering each EDI processing subunit uniform;

[0069] (5) When the medium flow rate required by the EDI processing loop is ≥ 2xA2, the EDI processing subunit 3 is put into operation, at this time, the inlet flow control valve is controlled by the flow distribution unit to keep the flow rate entering each EDI processing subunit uniform;

[0070] (6) As the flow rate increases, other EDI processing subunits are put into operation. When the flow rate decreases, the reverse logic is exited.

[0071] At the same time, the cumulative running time of each EDI processing subunit is recorded by the flow distribution unit, when the EDI processing subunit needs to be put into operation, the subunit with less cumulative running time is put into operation first, thereby prolonging the service life of the equipment.

[0072] In some embodiments, the EDI processing loop is connected in parallel with an ion exchange processing loop, and a partial replacement ion exchange processing system is adopted, as shown in FIG. 2. Figure 4 The number of EDI processing subunits in the EDI processing loop is set according to requirements.

[0073] Optionally, the ion exchange processing loop comprises a prepositive anion bed, a first resin catcher, a high-speed mixed bed, a second resin catcher and a precision filter connected in sequence.

[0074] The EDI processing loop is connected in parallel with the ion exchange processing loop, and a condensate water treatment control method of a partial replacement ion exchange processing system is adopted, and the method further comprises the following steps:

[0075] Step 51, receiving signals of the resin catcher and the flow distribution unit of the EDI processing loop;

[0076] Step 52, determining whether to put the EDI processing subunit into operation according to the total flow rate of the condensate water to be treated and the resin regeneration condition of the prepositive anion bed;

[0077] The number of processing subunits of the EDI processing subunit put into operation is controlled by the flow distribution unit of the EDI processing loop, and the control method is the same as that of the full replacement scheme, and the execution steps 1 to 4 are implemented.

[0078] In the embodiment, the EDI treatment circuit can greatly simplify the condensate polishing system process and equipment, whether it is partially or completely replaced by ion exchange treatment; it can improve the availability of the condensate polishing system, and for the complete resin bed process scheme, the EDI does not need to be regenerated and can be continuously operated; for the partial replacement scheme, the EDI subunit can be put into operation at any time to meet the system processing requirements of a wide flow range; using EDI treatment can reduce the possibility of impurities being brought into the secondary circuit due to incomplete resin regeneration or other processes, and can improve the removal rate of impurity ions in the high-concentration alkaliizer background.

[0079] Embodiment 2

[0080] Based on embodiment 1, the embodiment provides a control method of a nuclear power plant condensate water treatment system based on the method described in embodiment 1, which can be implemented in a control unit and includes the following steps:

[0081] Obtain the cumulative running time of each EDI treatment subunit, sort them in order from small to large running time, and set the priority of each EDI treatment subunit in order from large to small;

[0082] Obtain the total flow of the condensate water to be treated;

[0083] Determine the number N of EDI treatment subunits to be opened according to the total flow of the condensate water and the treatment flow range of a single EDI treatment subunit;

[0084] Control the first N EDI treatment subunits with high priority to be opened;

[0085] Further, when the total flow of the condensate water is detected to decrease, the priority of the EDI treatment subunit is judged according to the running time, and the EDI treatment subunit in operation is closed in order from small to large priority.

[0086] The above only describes the preferred embodiments of the present disclosure and is not intended to limit the present disclosure. For those skilled in the art, the present disclosure can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present disclosure shall be included in the protection scope of the present disclosure.

[0087] The above describes the specific embodiments of the present disclosure in conjunction with the accompanying drawings, but is not a limitation on the protection scope of the present disclosure. Those skilled in the art should understand that various modifications or changes made on the basis of the technical solutions of the present disclosure without creative labor are still within the protection scope of the present disclosure.

Claims

1. A nuclear power plant condensate treatment system, characterized by, The control unit is in communication connection with the EDI processing loop including a pre-filter group, a flow distribution unit and a plurality of EDI processing sub-units connected in sequence; the flow distribution unit includes a mother pipe and EDI processing sub-unit pipelines; a first flow monitoring device is arranged on the input mother pipe, and a control valve and a second flow monitoring device are arranged on each EDI processing sub-unit pipeline; the first flow monitoring device, the control valve and the second flow monitoring device are respectively in communication connection with the control unit; The control unit is configured to automatically configure the number of EDI processing sub-units to be put into use according to the flow of the condensate water to be treated by using time sequence control and bubble sorting; The control method of the nuclear power plant condensate water treatment system includes the following steps: Obtain the cumulative running time of each EDI processing sub-unit, sort them in the order of running time from small to large, and set the priority of each EDI processing sub-unit in the order from large to small; Obtain the total flow of the condensate water to be treated; Determine the number N of EDI processing sub-units to be turned on according to the total flow of the condensate water and the processing flow range of a single EDI processing sub-unit; Control the first N EDI processing sub-units with high priority to be turned on.

2. A nuclear power plant condensate treatment system as claimed in claim 1, characterized in that: The control unit is configured to automatically configure the number of EDI processing sub-units to be put into use according to the flow of the condensate water to be treated by using time sequence control and bubble sorting; Obtain the cumulative running time of each EDI processing sub-unit, sort them in the order of running time from small to large, and set the priority of each EDI processing sub-unit in the order from large to small; Obtain the total flow of the condensate water to be treated; Determine the number N of EDI processing sub-units to be turned on according to the total flow of the condensate water and the processing flow range of a single EDI processing sub-unit; Control the first N EDI processing sub-units with high priority to be turned on.

3. A nuclear power plant condensate treatment system as claimed in claim 1, characterized in that: The EDI processing sub-unit uses an electric desalination EDI membrane stack that can withstand a set temperature.

4. A nuclear power plant condensate treatment system as claimed in claim 1, characterized in that: The EDI processing loop is all or partially replaced by an ion exchange treatment. Alternatively, the control unit uses a PLC control cabinet.

5. A nuclear power plant condensate treatment system as claimed in claim 1, characterized in that: The pre-filter group is a one-to-one standby double-column arrangement, and each column includes a coarse filter and a fine filter connected in series.

6. A nuclear power plant condensate treatment system as claimed in claim 5, characterised in that: The filter uses an integrated filter basket structure, including a cylinder, a filter cartridge arranged in the cylinder, a filter core arranged in the filter cartridge, a filtrate inlet arranged on the side of the cylinder, and the filtrate inlet connected to and communicating with the gap between the cylinder and the filter cartridge; a filtrate outlet and a first purge port are arranged at the bottom end of the filter cartridge, a second purge port is arranged on the pipeline of the filtrate outlet, and a flange type top cover is detachably arranged at the upper end of the filter cartridge.

7. A nuclear power plant condensate treatment system as claimed in claim 1, characterized in that: The flow distribution unit receives the distribution control signal of the control unit to control the number of EDI processing sub-units to be put into use.

8. A nuclear power plant condensate treatment system as claimed in claim 1, characterized in that: Each EDI processing sub-unit includes a plurality of EDI membrane stacks; The control unit is configured to perform the following process: According to the mother pipe flow, automatically configure the number of EDI processing sub-units to be put into use, and the number of EDI membrane stacks running in the EDI processing sub-units; Alternatively, the control unit can also be configured to determine the EDI membrane stack to be put into use by accumulating the running time of each EDI membrane stack, and balance the running time of the EDI membrane stacks; Or, when the condensate water fine treatment system is not operated for a long time, the water is passed without power to continue wet maintenance of the EDI membrane stack.

9. A nuclear power plant condensate treatment system as claimed in claim 1, characterized in that: When the total flow of the condensate water is detected to be reduced, the priority of the EDI processing subunit is judged according to the running time, and the EDI processing subunit in operation is sequentially closed according to the priority from small to large.

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