Water supply oxygenation process system and method for direct-current evaporator nuclear power unit

Abstract

The invention discloses a water supply and oxygenation process system and method for a direct-current evaporator nuclear power unit, and belongs to the field of direct-current evaporator nuclear power units. In the system, a condenser is connected with a water inlet of a precision treatment system through a condensate pump, and a low-pressure heater is connected with a water outlet of the precision treatment system and a deaerator; the deaerator is connected with a high-pressure heater through a water feeding pump, the high-pressure heater is connected with an inlet of the direct-current evaporator nuclear power unit, the demineralized water oxygen dissolving device is provided with an air inlet end and a water inlet end, the water inlet end is connected with a water outlet of a precision processing system, and compressed air after pressure reduction is input into the air inlet end. The demineralized water oxygen dissolving device is further provided with a condensation water oxygen adding end and a deaerator oxygen adding end, the condensation water oxygen adding end is connected to an inlet of the condensation water pump, and the deaerator oxygen adding end is connected to a descending pipe of the deaerator. The problem that a steam generator or a steam turbine is salted, corroded or scaled due to the fact that the nuclear power unit cannot add oxygen to water can be solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of once-through evaporator nuclear power unit, and particularly relates to a once-through evaporator nuclear power unit feed water oxygenation process system and method. BACKGROUND

[0002] High temperature gas cooled reactor, sodium cooled fast reactor and small reactor belong to once-through steam generator nuclear power unit. Compared with pressurized water reactor unit, the once-through steam generator nuclear power unit has higher steam parameters, special steam generator structure and strict feed water quality indexes. Improper water quality control will cause salt deposition, corrosion or fouling problems of the steam generator or steam turbine. Referring to the once-through boiler technology of thermal power, feed water oxygenation is an important method to improve the feed water quality. The principle of oxygenation is to form a double-layer protective film of Fe3O4 and Fe2O3 on the metal substrate surface in pure water at a certain concentration of oxygen, so as to reduce the occurrence of flow accelerated corrosion. The once-through unit of thermal power generally adopts gaseous oxygenation or liquid oxygenation technology, but the safety requirement of nuclear power unit is high, and the gaseous oxygenation or liquid oxygenation technology cannot meet the safety requirement. SUMMARY

[0003] The present application aims to provide a once-through evaporator nuclear power unit feed water oxygenation process system and method, so as to solve the problem that the nuclear power unit cannot oxygenate the feed water, thereby causing salt deposition, corrosion or fouling problems of the steam generator or steam turbine.

[0004] To achieve the above-mentioned purpose, the present application adopts the following technical scheme: In a first aspect, a once-through evaporator nuclear power unit feed water oxygenation process system comprises a desalted water oxygenation device, a condenser, a condensate pump, a polishing treatment system, a low-pressure heater, a deaerator, a feed water pump and a high-pressure heater. The condenser is connected to the water inlet of the polishing treatment system through the condensate pump, the low-pressure heater is connected to the water outlet of the polishing treatment system and the deaerator, the deaerator is connected to the high-pressure heater through the feed water pump, the high-pressure heater is connected to the inlet of the once-through evaporator nuclear power unit, the desalted water oxygenation device has an air inlet end and a water inlet end, the water inlet end is connected to the water outlet of the polishing treatment system, the air inlet end inputs compressed air after pressure reduction, the desalted water oxygenation device further has a condensate oxygenation end and a deaerator oxygenation end, the condensate oxygenation end is connected to the inlet of the condensate pump, and the deaerator oxygenation end is connected to the downcomer of the deaerator.

[0005] In some embodiments, the desalted water oxygenation device comprises a demister, a water inlet nozzle, an air inlet nozzle and an oxygenation booster pump. The demister is arranged at the top of the desalinated water dissolving oxygen device, the condensate water oxygenation end and the deaerator oxygenation end are arranged at the bottom of the desalinated water dissolving oxygen device, the oxygenation pressure increasing pump is arranged at the deaerator oxygenation end, and the water inlet end and the air inlet end are arranged between the top and the bottom of the desalinated water dissolving oxygen device, the water inlet nozzle is arranged at the water inlet end, and the air inlet nozzle is arranged at the air inlet end.

[0006] In some embodiments, the desalinated water dissolving oxygen device further comprises a water inlet adjusting valve, an air inlet check valve, an air inlet adjusting valve, a condensate water oxygenation adjusting valve and a feed water oxygenation adjusting valve. The water inlet adjusting valve is arranged between the water outlet of the polishing treatment system and the air inlet nozzle, the air inlet check valve and the air inlet adjusting valve are arranged at the air inlet end, the air inlet check valve is arranged between the air inlet nozzle and the air inlet adjusting valve, the reduced pressure compressed air passes through the air inlet adjusting valve and the air inlet check valve in sequence, enters the air inlet nozzle, the condensate water oxygenation adjusting valve is arranged at the condensate water oxygenation end, and the feed water oxygenation adjusting valve is arranged at the deaerator oxygenation end and at the outlet of the oxygenation pressure increasing pump.

[0007] In some embodiments, the desalinated water dissolving oxygen device further comprises a condensate water oxygenation flowmeter and a feed water oxygenation flowmeter. The condensate water oxygenation flowmeter is arranged between the inlet of the condensate water pump and the condensate water oxygenation adjusting valve, and the feed water oxygenation flowmeter is arranged between the feed water oxygenation adjusting valve and the deaerator.

[0008] In some embodiments, the first online dissolved oxygen meter is arranged at the inlet of the deaerator, and the second online dissolved oxygen meter is arranged at the outlet of the high-pressure heater.

[0009] In some embodiments, the head of the oxygenation pressure increasing pump is greater than 1.5 times of the rated pressure of the deaerator.

[0010] In the second aspect, a feed water oxygenation process method of a once-through evaporator nuclear power unit is provided, which is based on the feed water oxygenation process system and comprises the following steps. The desalinated water in the desalinated water dissolving oxygen device is sucked into the condensate water generated by the condenser through the negative pressure at the inlet of the condensate water pump, and the desalinated water flow at the condensate water oxygenation end is controlled by a feedforward control or a PID closed-loop regulation mode to control the oxygenation amount at the inlet of the condensate water pump. After the oxygenation pressure increasing pump increases the pressure, the desalinated water flow at the deaerator oxygenation end is controlled by the feed water oxygenation adjusting valve and a feedforward control or a PID closed-loop regulation mode to control the oxygenation amount of the feed water in the downcomer of the deaerator.

[0011] In some embodiments, the oxygenation concentration of the condensate water oxygenation end and the deaerator oxygenation end is 10 μg / L-30 μg / L.

[0012] In some embodiments, the step of controlling the flow of the desalted water at the condensate oxygenation end by the feedforward control or PID closed-loop regulation to control the oxygenation amount at the inlet of the condensate pump specifically comprises: When the flow of the condensate is greater than the preset threshold, the flow of the desalted water is calculated according to the flow of the condensate and the preset condensate oxygenation concentration based on the feedforward control, and the flow of the desalted water at the condensate oxygenation end is controlled by adjusting the condensate oxygenation regulating valve; When the flow of the condensate is less than the preset threshold, the flow of the desalted water at the condensate oxygenation end is regulated by the PID closed-loop according to the concentration difference between the preset condensate oxygenation concentration and the measured dissolved oxygen concentration of the first online dissolved oxygen meter.

[0013] In some embodiments, the step of controlling the flow of the desalted water at the deaerator oxygenation end by the feedforward control or PID closed-loop regulation to control the oxygenation amount at the downcomer of the deaerator specifically comprises: When the flow of the feedwater is greater than the preset threshold, the flow of the desalted water is calculated according to the flow of the feedwater and the preset feedwater oxygenation concentration based on the feedforward control, and the flow of the desalted water at the deaerator oxygenation end is controlled by adjusting the feedwater oxygenation regulating valve; When the flow of the feedwater is less than the preset threshold, the flow of the desalted water at the deaerator oxygenation end is regulated by the PID closed-loop according to the concentration difference between the preset feedwater oxygenation concentration and the measured dissolved oxygen concentration of the second online dissolved oxygen meter.

[0014] Compared with the prior art, the present application has the following beneficial effects: The condenser is connected to the water inlet of the polishing treatment system through the condensate pump, the low-pressure heater is connected to the water outlet of the polishing treatment system and the deaerator, the deaerator is connected to the high-pressure heater through the feedwater pump, the high-pressure heater is connected to the inlet of the once-through evaporator nuclear power unit, the desalted water oxygenation device has an air inlet end and a water inlet end, the water inlet end is connected to the water outlet of the polishing treatment system, the air inlet end inputs compressed air after pressure reduction, the desalted water oxygenation device also has a condensate oxygenation end and a deaerator oxygenation end, the condensate oxygenation end is connected to the inlet of the condensate pump, and the deaerator oxygenation end is connected to the downcomer of the deaerator. The conventional oxygenation process relies on external oxygen cylinders, which constitutes a potential safety risk, especially in a nuclear power environment, any additional hazard source needs to be strictly controlled. However, the present application uses the water outlet of the secondary circuit polishing treatment system, i.e. desalted water, as the oxygenation water source, which can directly obtain oxygen from the internal system without introducing external oxygen cylinders, thereby eliminating this risk and improving the safety of the overall operation.

[0015] Further, in the desalted water dissolving oxygen device, the demister is arranged at the top of the desalted water dissolving oxygen device, the condensed water oxygen adding end and the deaerator oxygen adding end are located at the bottom of the desalted water dissolving oxygen device, the oxygen adding booster pump is arranged at the deaerator oxygen adding end, the gas inlet end and the water inlet end are located between the top and the bottom of the desalted water dissolving oxygen device, the water inlet nozzle is arranged at the water inlet end, and the gas inlet nozzle is arranged at the gas inlet end, compared with the complex gaseous or liquid oxygen adding technology, the desalted water dissolving oxygen device is simpler, the demand for special oxygen adding equipment is reduced, and the construction and maintenance costs are reduced. Meanwhile, due to the incompressibility and purity of the desalted water, more accurate and stable control can be provided during the oxygen adding process, and even in extreme or accident conditions, excessive oxygen adding is not easy to occur.

[0016] The desalted water flow of the condensed water oxygen adding end is controlled by the feedforward control or PID closed loop regulation to control the oxygen adding amount at the inlet of the condensed water pump, and the desalted water flow of the deaerator oxygen adding end is controlled by the feedforward control or PID closed loop regulation to control the oxygen adding amount of the downcomer feedwater of the deaerator, so that automatic control is realized, the flow change can be adapted, and the accurate management of the oxygen adding concentration is ensured. This method not only improves the efficiency, but also greatly reduces the demand for manual intervention. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 A structure diagram of a direct-flow evaporator nuclear power unit feedwater oxygen adding process system is provided for the embodiment of the present application. Figure 2 A desalted water dissolving oxygen device structure diagram is provided for the embodiment of the present application.

[0018] In the figure, 1 is a demister, 2 is a water inlet nozzle, 3 is a water inlet regulating valve, 4 is a gas inlet nozzle, 5 is a gas inlet check valve, 6 is a gas inlet regulating valve, 7 is a condensed water oxygen adding regulating valve, 8 is a feedwater oxygen adding regulating valve, 9 is an oxygen adding booster pump, 10 is a desalted water dissolving oxygen device, 11 is a condenser, 12 is a condensate pump, 13 is a polishing treatment system, 14 is a low-pressure heater, 15 is a deaerator, 16 is a feedwater pump, 17 is a high-pressure heater, 18 is a condensed water oxygen adding flowmeter, and 19 is a feedwater oxygen adding flowmeter. DETAILED DESCRIPTION

[0019] In the following, only certain exemplary embodiments are simply described, and the described embodiments can be modified in various different ways without departing from the spirit or scope of the present application. Therefore, the drawings and the description are considered to be exemplary in nature rather than limiting.

[0020] In the description of the present application, it is to be understood that the orientations or positional relationships indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed or operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0021] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features referred to. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0022] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connected", "fixed" and the like should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integral; can be mechanical connection, can also be electrical connection, can also be communication; can be direct connection, can also be indirectly connected through intermediate medium, can be the communication or interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0023] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0024] Example 1 As Figure 1 And Figure 2As shown, the embodiment provides a direct-flow evaporator nuclear power unit water feeding and oxygen adding process system, wherein the demineralized water dissolving oxygen device 10, the condenser 11, the condensate pump 12, the fine treatment system 13, the low-pressure heater 14, the deaerator 15, the water feeding pump 16 and the high-pressure heater 17 constitute the core of the entire water feeding and oxygen adding process system. The demineralized water dissolving oxygen device 10 utilizes oxygen in the air to dissolve in the demineralized water out of the fine treatment system 13 to form demineralized water saturated with dissolved oxygen, thereby providing a safe and reliable water source for the oxygen adding process. By controlling the air intake and the demineralized water flow, the oxygen is fully dissolved in the water, the occurrence of flow-accelerated corrosion is reduced, the water quality of the water feeding can be effectively improved, the problems of salt accumulation, corrosion or fouling of the steam generator and the steam turbine are prevented, and the safe and stable operation of the nuclear power unit is ensured. In other embodiments, the design of the demineralized water dissolving oxygen device 10 can also be optimized, such as increasing the filler layer to improve the oxygen dissolution efficiency and solve the technical problem of insufficient oxygen dissolution under certain working conditions.

[0025] The demineralized water dissolving oxygen device 10 comprises a demister 1, a water inlet nozzle 2, an air inlet nozzle 4 and an oxygen adding booster pump 9. The demister 1 is arranged at the top of the demineralized water dissolving oxygen device 10, the condensate oxygen adding end and the deaerator oxygen adding end are located at the bottom of the demineralized water dissolving oxygen device 10, the oxygen adding booster pump 9 is arranged at the deaerator oxygen adding end, the air inlet end and the water inlet end are located between the top and the bottom of the demineralized water dissolving oxygen device 10, the water inlet nozzle 2 is arranged at the water inlet end, and the air inlet nozzle 4 is arranged at the air inlet end. The arrangement of the demister 1 can remove water droplets in the compressed air to avoid the water droplets entering the demineralized water dissolving oxygen device 10 and affecting the oxygen dissolution efficiency. The water inlet nozzle 2 and the air inlet nozzle 4 promote water-gas contact by spraying, increase the oxygen dissolution area, improve the dissolution rate, and utilize the incompressibility of the demineralized water to ensure the stability and controllability of the oxygen dissolution process. The embodiment can ensure the normal operation of the demineralized water dissolving oxygen device 10 and provide demineralized water saturated with dissolved oxygen. In other embodiments, the nozzle design can also be improved, such as adopting multi-stage spraying, to further improve the oxygen dissolution efficiency and solve the problem of insufficient oxygen dissolution under low flow conditions.

[0026] The settings of the water inlet regulating valve 3, the air inlet check valve 5, the air inlet regulating valve 6, the condensate water oxygenation regulating valve 7 and the feed water oxygenation regulating valve 8 in the desalted water oxygenation device 10 provide precise flow control and safe gas introduction for the oxygenation process. The water inlet regulating valve 3 is installed between the outlet of the polishing treatment system 13 and the air inlet nozzle 4, the air inlet check valve 5 and the air inlet regulating valve 6 are both arranged at the air inlet end, the air inlet check valve 5 is arranged between the air inlet nozzle 4 and the air inlet regulating valve 6, the compressed air after pressure reduction passes through the air inlet regulating valve 6 and the air inlet check valve 5 in sequence, enters the air inlet nozzle 4, the condensate water oxygenation regulating valve 7 is arranged at the condensate water oxygenation end, the feed water oxygenation regulating valve 8 is arranged at the deaerator oxygenation end and is located at the outlet of the oxygenation booster pump 9. The water inlet regulating valve 3 and the air inlet regulating valve 6 can accurately adjust the flow of the desalted water and the compressed air according to the actual demand, so as to ensure the stability of the oxygen concentration. The air inlet check valve 5 prevents backflow and protects the safety of the desalted water oxygenation device 10. Through the opening degree control of the above-mentioned regulating valves, the precise control of the oxygen dissolution amount is realized, the problem of excessive oxygenation is avoided, the stability and safety of the oxygenation process can be ensured, and the precise oxygenation of the feed water and the condensate water is realized.

[0027] The condensate water oxygenation flowmeter 18 is installed between the inlet of the condensate water pump 12 and the condensate water oxygenation regulating valve 7, and the feed water oxygenation flowmeter 19 is installed between the feed water oxygenation regulating valve 8 and the deaerator 15. The settings of the condensate water oxygenation flowmeter 18 and the feed water oxygenation flowmeter 19 provide real-time flow monitoring for the oxygenation process, so as to ensure the precise control of the oxygenation amount.

[0028] The first online dissolved oxygen meter is arranged at the inlet of the deaerator 15, and the second online dissolved oxygen meter is arranged at the outlet of the high-pressure heater 17. The settings of the first online dissolved oxygen meter and the second online dissolved oxygen meter provide real-time dissolved oxygen concentration monitoring for the oxygenation process, so as to ensure the precise control of the oxygenation amount.

[0029] The head of the oxygenation booster pump 9 is designed to be greater than 1.5 times the rated pressure of the deaerator 15. The rated pressure of the deaerator 15 and the performance of the oxygenation pump are considered, so as to ensure that the oxygenation pump can overcome the pressure of the deaerator 15 and successfully add the desalted water saturated with dissolved oxygen into the feed water system, which can ensure the smooth progress of the oxygenation process and avoid the problem of oxygenation failure caused by insufficient performance of the oxygenation pump.

[0030] The working process of the above water feeding and oxygen adding process system is as follows: under normal operation condition, the effluent of the fine treatment system 13 enters the desalted water dissolving oxygen device 10 through the water feeding adjusting valve 3, and the compressed air after pressure reduction enters the air inlet nozzle 4 through the air inlet adjusting valve 6 and the air inlet check valve 5, and mass transfer exchange occurs between the effluent of the fine treatment system 13 and the compressed air in the desalted water dissolving oxygen device 10, oxygen is dissolved in the desalted water to form desalted water saturated with dissolved oxygen. The condensate water oxygen adding adjusting valve 7 and the water feeding oxygen adding adjusting valve 8 control the desalted water flow rate at the condensate water oxygen adding end and the deaerator oxygen adding end according to the condensate water flow rate and the water flow rate and the preset oxygen adding concentration through feedforward control or PID closed loop regulation, so as to realize accurate oxygen adding of the condensate water and the water. The condensate water oxygen adding flow meter 18 and the water feeding oxygen adding flow meter 19 monitor the oxygen adding amount in real time to ensure accurate control of the oxygen adding amount. The first online dissolved oxygen meter and the second online dissolved oxygen meter monitor the dissolved oxygen concentration in real time to provide data support for the PID closed loop regulation and ensure accurate control of the dissolved oxygen concentration. The head of the oxygen adding booster pump 9 is designed to ensure smooth progress of the oxygen adding process and overcome the pressure of the deaerator 15 to smoothly add the desalted water saturated with dissolved oxygen into the water feeding system. The entire oxygen adding process system realizes accurate control of the oxygen adding amount through accurate flow rate control and real-time dissolved oxygen concentration monitoring, improves the water quality of the water feeding system, prevents salt deposition, corrosion or fouling of the steam generator and the steam turbine, and ensures safe and stable operation of the nuclear power unit.

[0031] Embodiment Two On the basis of Embodiment One, the embodiment provides a once-through evaporator nuclear power unit water feeding and oxygen adding process method, which specifically comprises the following steps: The once-through evaporator nuclear power unit is provided with two oxygen adding points: a water feeding oxygen adding point and a condensate water oxygen adding point. The oxygen adding concentration of the water and the condensate water is controlled at 10-30 μg / L, which can be set artificially. The water feeding oxygen adding point is designed at the inlet of the condensate water pump 12, and the desalted water in the desalted water dissolving oxygen device 10 is sucked into the condensate water through the negative pressure at the inlet of the condensate water pump 12. The control of the oxygen adding amount at the inlet of the condensate water pump 12 adopts feedforward control combined with PID closed loop regulation. When the condensate water flow rate fluctuates greatly, the feedforward control is adopted, the flow rate q1 of the desalted water added is calculated according to the condensate water flow rate and the preset condensate water oxygen adding concentration, and the flow rate of the desalted water added is controlled by adjusting the opening degree of the condensate water oxygen adding adjusting valve 7.

[0032] wherein, q1 is the flow rate of the desalted water added (t / h), q is the condensate water flow rate (t / h), C is the preset condensate water oxygen adding concentration (μg / L); For example, under the rated condition of a 600 MW unit, the condensate flow is 2400 t / h, and the condensate dissolved oxygen content is controlled at 20 μg / L. The condensate deaerated water flow q1 is 2400*20 / 8000 = 6 t / h. The opening of the condensate oxygen adding regulating valve 7 is adjusted to control the condensate deaerated water flow at 6 t / h.

[0033] When the flow fluctuation is not large, PID closed-loop regulation is adopted, and the PID closed-loop regulation is performed according to the difference between the set oxygen concentration c and the concentration of the on-line dissolved oxygen meter at the inlet of the deaerator (i.e., the first on-line dissolved oxygen meter), so as to ensure that the positive and negative deviations are less than 3 μg / L.

[0034] The feed water oxygen adding point is arranged at the downcomer of the deaerator, and the oxygen adding pressure boosting pump 9 in the deaerated water dissolved oxygen device 10 is used for pressure boosting. The head of the oxygen adding pressure boosting pump 9 should be greater than 1.5 times of the rated pressure of the deaerator 15. The feed water deaerated water flow is controlled by the feed water oxygen adding regulating valve 8.

[0035] The feed water oxygen adding amount control of the downcomer of the deaerator 15 adopts feedforward control combined with PID closed-loop regulation. When the flow fluctuation is large, the feedforward control is adopted, the deaerated water flow q2 is calculated according to the feed water flow and the set feed water oxygen adding concentration, and the opening of the feed water oxygen adding regulating valve 8 is adjusted to control the feed water deaerated water flow.

[0036] wherein, q2 is the feed water deaerated water flow (t / h), q is the feed water flow (t / h), c is the preset feed water oxygen adding concentration (μg / L).

[0037] When the flow fluctuation is not large, PID closed-loop regulation is adopted, and the PID closed-loop regulation is performed according to the difference between the set oxygen concentration c and the concentration of the on-line dissolved oxygen meter at the outlet of the high-pressure heater (i.e., the second on-line dissolved oxygen meter), so as to ensure that the positive and negative deviations are less than 3 μg / L.

[0038] The working process is described as follows: under normal operation condition, the effluent of the polishing treatment system 13 enters the desalted water dissolved oxygen device 10 through the water inlet adjusting valve 3, and the compressed air after pressure reduction enters the air inlet nozzle 4 through the air inlet adjusting valve 6 and the air inlet check valve 5, and mass transfer exchange occurs between the effluent of the polishing treatment system 13 and the compressed air in the desalted water dissolved oxygen device 10, oxygen is dissolved in the desalted water to form desalted water saturated with dissolved oxygen. The condensate water oxygen adding adjusting valve 7 and the feed water oxygen adding adjusting valve 8 control the desalted water flow rate of the condensate water oxygen adding end and the deaerator oxygen adding end according to the condensate water flow rate and the feed water flow rate and the preset oxygen adding concentration through feedforward control or PID closed loop regulation, so that the condensate water and the feed water are accurately oxygenated. The condensate water oxygen adding flowmeter 18 and the feed water oxygen adding flowmeter 19 monitor the oxygen adding amount in real time, so that the oxygen adding amount is accurately controlled. The first online dissolved oxygen meter and the second online dissolved oxygen meter monitor the dissolved oxygen concentration in real time, so that the dissolved oxygen concentration is accurately controlled. The head of the oxygen adding pressure pump 9 is designed to ensure the smooth progress of the oxygen adding process, overcome the pressure of the deaerator 15 and smoothly add the desalted water saturated with dissolved oxygen into the feed water system. The entire oxygen adding process system is accurately controlled through accurate flow control and real-time dissolved oxygen concentration monitoring, so that the oxygen adding amount is accurately controlled, the feed water quality is improved, the problems of salt accumulation, corrosion or fouling of the steam generator and the steam turbine are prevented, and the safe and stable operation of the nuclear power unit is ensured.

[0039] It is to be understood by those skilled in the art that the present application can be implemented by other embodiments without departing from the spirit or essential characteristics thereof. Therefore, the above disclosed embodiments are merely exemplary in all aspects and are not the only ones, and all changes within the scope of the present application or equivalent to the scope of the present application are intended to be included in the present application.

Claims

1. A feedwater oxygenation process system for a DC evaporator nuclear power unit, characterized in that, include: Demineralized water oxygenation unit (10), condenser (11), condensate pump (12), fine treatment system (13), low-pressure heater (14), deaerator (15), feed water pump (16) and high-pressure heater (17). The condenser (11) is connected to the inlet of the fine treatment system (13) via the condensate pump (12). The low-pressure heater (14) is connected to the outlet of the fine treatment system (13) and the deaerator (15). The deaerator (15) is connected to the high-pressure heater (17) via the feed water pump (16). The high-pressure heater (17) is connected to the inlet of the DC evaporator nuclear power unit. The demineralized water oxygenation device (10) has an air inlet and a water inlet. The water inlet is connected to the outlet of the fine treatment system (13). The air inlet is supplied with compressed air after pressure reduction. The demineralized water oxygenation device (10) also has a condensate oxygenation end and a deaerator oxygenation end. The condensate oxygenation end is connected to the inlet of the condensate pump (12). The deaerator oxygenation end is connected to the downcomer of the deaerator (15).

2. The feedwater oxygenation process system for a DC evaporator nuclear power unit according to claim 1, characterized in that, The demineralized water oxygenation device (10) includes: a demister (1), a water inlet nozzle (2), an air inlet nozzle (4), and an oxygenation booster pump (9). The demister (1) is located at the top of the demineralized water oxygenation device (10), the condensate oxygenation end and the deaerator oxygenation end are located at the bottom of the demineralized water oxygenation device (10), the oxygenation booster pump (9) is located at the deaerator oxygenation end, the air inlet end and the water inlet end are located between the top and bottom of the demineralized water oxygenation device (10), the water inlet nozzle (2) is located at the water inlet end, and the air inlet nozzle (4) is located at the air inlet end.

3. The feedwater oxygenation process system for a DC evaporator nuclear power unit according to claim 2, characterized in that, The demineralized water oxygenation device (10) also includes: an inlet water regulating valve (3), an inlet air check valve (5), an inlet air regulating valve (6), a condensate oxygenation regulating valve (7), and a feed water oxygenation regulating valve (8); The water inlet regulating valve (3) is installed between the outlet of the fine treatment system (13) and the air inlet nozzle (4). The air inlet check valve (5) and the air inlet regulating valve (6) are both located at the air inlet end. The air inlet check valve (5) is located between the air inlet nozzle (4) and the air inlet regulating valve (6). The compressed air after pressure reduction passes through the air inlet regulating valve (6) and the air inlet check valve (5) in sequence and enters the air inlet nozzle (4). The condensate oxygenation regulating valve (7) is located at the condensate oxygenation end. The feed water oxygenation regulating valve (8) is located at the deaerator oxygenation end and is located at the outlet of the oxygenation booster pump (9).

4. The feedwater oxygenation process system for a DC evaporator nuclear power unit according to claim 3, characterized in that, The demineralized water oxygenation device (10) also includes a condensate oxygenation flow meter (18) and a feedwater oxygenation flow meter (19). The condensate oxygenation flow meter (18) is installed between the inlet of the condensate pump (12) and the condensate oxygenation regulating valve (7), and the feedwater oxygenation flow meter (19) is installed between the feedwater oxygenation regulating valve (8) and the deaerator (15).

5. The feedwater oxygenation process system for a DC evaporator nuclear power unit according to claim 3, characterized in that, It also includes a first online dissolved oxygen meter and a second online dissolved oxygen meter, the first online dissolved oxygen meter being installed at the inlet of the deaerator (15) and the second online dissolved oxygen meter being installed at the outlet of the high-pressure heater (17).

6. The feedwater oxygenation process system for a DC evaporator nuclear power unit according to claim 2, characterized in that, The head of the oxygenation booster pump (9) is 1.5 times the rated pressure of the deaerator (15).

7. A method for oxygenating feedwater in a DC evaporator nuclear power unit, characterized in that, The water supply oxygenation process system according to any one of claims 3 includes the following steps: The demineralized water in the demineralized water oxygenation device (10) is drawn into the condensate generated by the condenser (11) by the negative pressure at the inlet of the condensate pump (12), and the flow rate of demineralized water at the oxygenation end of the condensate is controlled by feedforward control or PID closed-loop regulation to control the amount of oxygen added at the inlet of the condensate pump (12). After the oxygenation booster pump (9) pressurizes the water, the oxygenation regulating valve (8) is used to control the flow rate of demineralized water at the oxygenation end of the deaerator through feedforward control or PID closed-loop regulation to control the oxygenation amount of the downcomer water supply of the deaerator (15).

8. The method for oxygenation of feedwater in a DC evaporator nuclear power unit according to claim 7, characterized in that, The oxygen concentration at the condensate oxygenation end and the deaerator oxygenation end is 10 μg / L to 30 μg / L.

9. The method for oxygenation of feedwater in a DC evaporator nuclear power unit according to claim 7, characterized in that, The step of controlling the demineralized water flow rate at the condensate oxygenation end through feedforward control or PID closed-loop regulation to control the oxygenation amount at the inlet of the condensate pump (12) specifically includes: When the flow rate of the condensate is greater than the preset threshold, the flow rate of the demineralized water is calculated based on the feedforward control method and the flow rate of the condensate and the preset condensate oxygenation concentration. The flow rate of the demineralized water at the condensate oxygenation end is controlled by adjusting the condensate oxygenation regulating valve (7). When the flow rate of the condensate is lower than a preset threshold, the flow rate of the demineralized water at the oxygenation end of the condensate is adjusted by PID closed-loop control based on the concentration difference between the preset oxygenation concentration of the condensate and the dissolved oxygen concentration measured by the first online dissolved oxygen meter.

10. The method for oxygenating feedwater in a DC evaporator nuclear power unit according to claim 7, characterized in that, The step of controlling the demineralized water flow at the oxygen supply end of the deaerator through feedforward control or PID closed-loop regulation to control the oxygen supply at the downcomer of the deaerator (15) specifically includes: When the flow rate of the water supply is greater than the preset threshold, the flow rate of the demineralized water is calculated based on the feedforward control method and the flow rate of the water supply and the preset oxygenation concentration of the water supply. The flow rate of the demineralized water at the oxygenation end of the deaerator is controlled by adjusting the oxygenation regulating valve (8). When the flow rate of the feed water is lower than a preset threshold, and based on the concentration difference between the preset feed water oxygenation concentration and the dissolved oxygen concentration measured by the second online dissolved oxygen meter, the flow rate of the demineralized water at the oxygenation end of the deaerator is adjusted by PID closed-loop control.

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