Method for feeding water to steam generator of high temperature gas cooled reactor nuclear power unit

Abstract

The embodiment of the present disclosure provides a water feeding method for a steam generator of a high-temperature gas cooled reactor nuclear power unit, which comprises the following steps: by controlling the rotation speed of a main feed water pump and the opening degree of a main feed water bypass valve, so that the main feed water pressure is at a preset pressure value, and the valve front pressure of a main feed water isolation valve is greater than the valve rear pressure; opening the main feed water isolation valve; controlling the main steam isolation valve to be opened at a preset opening degree, and fully opening the main steam isolation valve after the steam generator outlet pressure is stabilized; controlling the inlet valve of a steam-water separator to be opened at a preset opening degree, and establishing a two-loop small-flow circulation through steam-water separator exhaust water; when the two-loop small-flow circulation reaches a preset condition, fully opening the main feed water isolation valve, and gradually closing the main feed water bypass valve; using the hydraulic coupler and the inlet valve of the electric feed water pump to make the two-loop circulation flow and pressure meet a target working condition, so that the high-temperature gas cooled reactor steam generator is safely fed with water.

Description

Technical Field

[0001] The embodiments disclosed herein belong to the field of high-temperature gas-cooled reactor technology, specifically relating to a water filling method for a steam generator in a high-temperature gas-cooled reactor nuclear power unit. Background Technology

[0002] The steam generator in a high-temperature gas-cooled reactor (HTGR) nuclear power plant transfers heat from the primary loop to the secondary loop water, generating qualified steam to drive the turbine. In an HTGR unit, the shell side of the heat transfer tubes of the steam generator receives helium from the primary loop, while the tube side receives feedwater from the secondary loop.

[0003] Given the structural characteristics of the steam generator in a high-temperature gas-cooled reactor (HTGR) and the inherent operating characteristics of the HTGR itself, the water supply to the steam generator and the establishment of a secondary loop circulation are particularly important. Improper handling can lead to significant thermal shocks to the steam generator tubesheet, excessive negative helium pressure change rate in the primary loop, and a rapid drop in primary loop temperature that could introduce positive reactivity into the reactor, causing damage to the equipment and potentially resulting in a nuclear safety incident. Summary of the Invention

[0004] The embodiments disclosed herein aim to at least solve one of the technical problems existing in the prior art, and provide a method for water filling the steam generator of a high-temperature gas-cooled reactor nuclear power unit.

[0005] The embodiments of this disclosure provide a method for filling a steam generator in a high-temperature gas-cooled reactor nuclear power unit with water, the method comprising:

[0006] Main feedwater isolation valve from water supply to steam generator: By controlling the speed of the main feedwater pump and the opening of the main feedwater bypass regulating valve, the main feedwater pressure is kept at the preset pressure value and the pressure before the main feedwater isolation valve is greater than the pressure after the valve.

[0007] Steam generator water inlet: Open the main feedwater isolation valve; control the main steam isolation valve to open to a preset opening degree, and fully open the main steam isolation valve after the steam generator outlet pressure stabilizes;

[0008] Establish a two-loop low-flow circulation: control the inlet regulating valve of the steam-water separator to open at a preset opening degree, and establish a two-loop low-flow circulation by exhausting steam and introducing water through the steam-water separator;

[0009] The main water supply system valves are switched to adjust the secondary loop circulation flow and pressure: when the secondary loop small flow circulation reaches the preset conditions, the main water supply isolation valve is fully opened and the main water supply bypass regulating valve is gradually closed; the electric water supply pump hydraulic coupling and the inlet regulating valve are used to make the secondary loop circulation flow and pressure meet the target operating conditions.

[0010] Optionally, the preset pressure value range is 1MPa to 4MPa, and the pressure before the main water supply isolation valve is more than 1MPa greater than the pressure after the valve.

[0011] Optionally, during the process of opening the main water supply isolation valve, the method further includes:

[0012] Obtain the negative rate of change of helium pressure and / or the temperature change of hot and cold helium in the primary loop;

[0013] If the negative change rate of helium pressure and / or the change value of hot and cold helium temperature in the primary circuit exceeds a preset threshold, the opening of the main water supply bypass valve is reduced.

[0014] Optionally, during the process of fully opening the main steam isolation valve, the method further includes:

[0015] Obtain the negative rate of change of helium pressure and / or the temperature change of hot and cold helium in the primary loop;

[0016] If the negative rate of change of helium pressure and / or the change in temperature of hot and cold helium in the primary loop exceeds a preset threshold, the opening speed of the main steam isolation valve will be slowed down.

[0017] Optionally, the inlet regulating valve is controlled to open at a preset opening degree, establishing a two-loop low-flow circulation through the steam-water separator for steam discharge and water intake, including:

[0018] When the steam-water separator reaches the water level, the main feedwater flow rate is increased by opening the main feedwater bypass regulating valve and increasing the speed of the main feedwater pump. The pressure of the secondary circuit of the steam generator is controlled to be greater than the helium pressure of the primary circuit by the inlet regulating valve.

[0019] When the water level in the steam-water separator reaches the predetermined water level, the steam-water separator drain valve is automatically controlled.

[0020] If the water quality in the steam-water separator meets the preset water quality requirements, it is discharged to the condenser through the steam-water separator drain valve; otherwise, it is discharged to the secondary circuit inspection water tank through the steam-water separator drain valve.

[0021] Optionally, the predetermined water level range is 1500mm to 2500mm.

[0022] Optionally, the preset water quality requirements are: colorless and transparent appearance, and iron content less than 200 mg / L.

[0023] μm / L, sodium content less than 80 μm / L, and silica content less than 200 μm / L.

[0024] Optionally, during the process of fully opening the main feedwater isolation valve and gradually closing the main feedwater bypass regulating valve, the method further includes:

[0025] Real-time acquisition of main water supply flow rate and / or pressure;

[0026] Based on the obtained main water supply flow rate and / or pressure, adjust the speed of the main water supply pump to stabilize the main water supply flow rate and / or pressure.

[0027] Optionally, before the water supply reaches the main feedwater isolation valve of the steam generator, the method further includes preparatory work before water supply to the steam generator, specifically including:

[0028] The pH value and hydrazine concentration of the main water supply are controlled to be within the corresponding preset range values;

[0029] The temperature of the main feedwater is controlled to match the tube sheet temperature of the steam generator;

[0030] Drain the water accumulated in front of the main water supply isolation valve and close the inlet regulating valve.

[0031] Optionally, controlling the temperature of the main feedwater to match the tube sheet temperature of the steam generator includes:

[0032] If the required temperature of the main feedwater is low, the main feedwater is heated by the main feedwater pump so that the temperature of the main feedwater is slightly higher than the tube sheet temperature of the steam generator.

[0033] If the main feedwater temperature requirement is high, the main feedwater is heated by a heater so that the temperature of the main feedwater is slightly higher than the tube sheet temperature of the steam generator.

[0034] The water filling method for the steam generator of a high-temperature gas-cooled reactor nuclear power unit disclosed herein can effectively control all parameters of the entire water filling process of the high-temperature gas-cooled reactor steam generator during the process of filling water into the steam generator and establishing a secondary loop. This ensures safe water filling of the high-temperature gas-cooled reactor steam generator and avoids problems such as large temperature shocks in the steam generator tube sheet, excessive negative change rate of helium pressure in the reactor primary loop, and abnormal introduction of positive reactions into the reactor, thereby avoiding equipment damage or nuclear safety incidents. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the loop system of the steam generator in a high-temperature gas-cooled reactor nuclear power unit.

[0036] Figure 2 This is a schematic flowchart illustrating a water filling method for a steam generator in a high-temperature gas-cooled reactor nuclear power unit, according to an embodiment of this disclosure. Detailed Implementation

[0037] To enable those skilled in the art to better understand the technical solutions of this disclosure, the disclosure will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] The embodiments of this disclosure provide a method for filling the steam generator of a high-temperature gas-cooled reactor nuclear power unit with water. This method can be applied to, for example... Figure 1 The loop system 100 of the steam generator of the high-temperature gas-cooled reactor nuclear power unit is shown.

[0039] like Figure 1 As shown, the loop system 100 of the steam generator in a high-temperature gas-cooled reactor nuclear power unit includes: a main feedwater pipeline 110, a first bypass pipeline 120 connected in series with a heater 121, a second bypass pipeline 130 connected in series with a main feedwater bypass regulating valve 131, and a main steam pipeline (not labeled in the figure) connected in series with a main steam isolation valve 141. The outlet of the main feedwater pipeline 110 is connected to the inlet of the steam generator 200. The main feedwater pipeline 110 is sequentially connected to the main feedwater pump 111, the first bypass pipeline 120, the second bypass pipeline 130, and the main feedwater isolation valve 140 in the direction of outlet. The inlets and outlets of the first bypass pipeline 120 and the second bypass pipeline 130 are both connected to the main feedwater pipeline 110.

[0040] The inlet of the main steam pipeline is connected to the outlet of the steam generator 200, and its outlet is connected to the main steam system and the reactor start-up / shutdown system pipelines respectively. The reactor start-up / shutdown system includes an inlet regulating valve 310, a steam-water separator 320, and a steam-water separator drain valve 330 connected in series in the pipeline. The inlet and outlet of the steam-water separator 320 are connected to the outlet of the inlet regulating valve 310 and the inlet of the steam-water separator drain valve 330 respectively. The outlet of the steam-water separator drain valve 330 is connected to the condenser and the secondary loop inspection water pool respectively.

[0041] Specifically, such as Figure 1 As shown, at the initial startup of a high-temperature gas-cooled reactor nuclear power unit, it is necessary to establish the secondary loop flow and discharge or recover any substandard working fluid through the start-up and shutdown system. The main feedwater in the deaerator is supplied to the steam generator 200 via the main feedwater pipeline 110. The main feedwater pump 111 pressurizes the main feedwater in the deaerator, the heater 121 heats the main feedwater, and the main feedwater bypass valve 131 controls the main feedwater flow rate.

[0042] During the start-up and shutdown of a high-temperature gas-cooled reactor nuclear power unit, lower-temperature water or steam from the steam generator 200 flows through the start-up / shutdown system to the turbine to perform work or is discharged to the condenser. During this time, the main steam system is in an isolated state. During normal operation of the high-temperature gas-cooled reactor nuclear power unit, steam from the steam generator 200 drives the turbine to perform work through the main steam system, and the start-up / shutdown system is in an isolated standby state.

[0043] Currently, there is no relevant method for filling the 100 steam generator with water and establishing a secondary loop circulation in this loop system. During the operation of this loop system, problems such as large temperature shocks to the steam generator tube sheet, excessive negative helium pressure change rate protection in the reactor primary loop, and rapid temperature drop in the primary loop leading to positive reactivity in the reactor are prone to occur, which can damage the equipment and lead to nuclear safety incidents.

[0044] Based on this, to avoid the aforementioned problems, this disclosure presents a water filling method for the steam generator of a high-temperature gas-cooled reactor nuclear power unit, the water filling method comprising:

[0045] S1. Preparations before filling the steam generator with water.

[0046] Specifically, the preparatory work before filling the steam generator with water in this step includes: controlling the pH value and hydrazine concentration value of the main feed water to be within the corresponding preset range, controlling the temperature of the main feed water to match the tube sheet temperature of the steam generator, draining the water accumulated in front of the main feed water isolation valve, and keeping the inlet regulating valve in the closed state, etc.

[0047] As an example of controlling the pH value and hydrazine concentration of the main water supply within corresponding preset ranges, combined with Figure 1 Before filling with water, the loop system 100 is first flushed, and then the dosing system is activated to control the pH value and hydrazine concentration of the main feedwater within their respective preset ranges. As an example, the pH value of the main feedwater can be controlled to be 9.3–9.6, the hydrazine concentration to be 500 ml–1000 ml, and the iron content to be no more than 50 μm / L.

[0048] As an example of controlling the temperature of the main feedwater to match the tube sheet temperature of the steam generator, combined with Figure 1 The main feedwater temperature is matched with the steam generator tube sheet temperature. For example, the main feedwater temperature is controlled to be slightly higher than the steam generator tube sheet temperature. If the required main feedwater temperature is lower, the main feedwater is heated by the main feedwater pump 111. If the required main feedwater temperature is higher and auxiliary steam is available, the main feedwater is heated by the auxiliary steam and heater 121. As a specific example, matching the main feedwater temperature with the steam generator tube sheet temperature can be achieved by controlling the main feedwater temperature to be 5°C to 15°C higher than the steam generator tube sheet temperature. Preferably, the main feedwater temperature can be controlled to be 2°C to 10°C higher than the steam generator tube sheet temperature.

[0049] As an example of draining the water accumulated before the main water supply isolation valve and closing the inlet regulating valve, combined with Figure 1Drain the water in front of the main feedwater isolation valve 140 and set the inlet regulating valve 310 to the closed state. Of course, after the above work is completed, the main feedwater bypass regulating valve 131, the main feedwater isolation valve 140 and the main steam isolation valve 141 should also be set to the closed state.

[0050] The water filling method for the steam generator of the high-temperature gas-cooled reactor nuclear power unit in this embodiment, through the preparatory work before water filling, can better ensure the safe water filling of the high-temperature gas-cooled reactor steam generator, avoid large temperature shocks to the steam generator tube sheet, and effectively control various parameters during the water filling process.

[0051] S2, Main feedwater isolation valve from water supply to steam generator: By controlling the speed of the main feedwater pump and the opening of the main feedwater bypass regulating valve, the main feedwater pressure is kept at the preset pressure value and the pressure before the main feedwater isolation valve is greater than the pressure after the valve.

[0052] As a concrete example, let's combine them together. Figure 1 The main feedwater pressure is controlled by adjusting the speed of the main feedwater pump 111 to maintain a preset pressure range of 1MPa to 4MPa, preferably 2MPa to 3MPa. The main feedwater bypass valve 131 is slightly opened to establish the pressure before the main feedwater isolation valve 140 of the steam generator 200, ensuring that the pressure before the main feedwater isolation valve 140 is greater than the pressure after the valve, specifically by more than 1MPa. It should be noted that the side of the main feedwater isolation valve away from the steam generator is considered the front end, and the side closer to the steam generator is considered the back end. Of course, this embodiment does not limit the specific number of main feedwater isolation valves in the loop system.

[0053] S3. Steam generator inlet: Open the main feedwater isolation valve. Control the main steam isolation valve to open to a preset opening degree, and fully open the main steam isolation valve after the steam generator outlet pressure stabilizes.

[0054] Specifically, in combination Figure 1 Open the main water supply isolation valve 140. During the opening of the main water supply isolation valve 140, obtain the negative change rate of helium pressure and / or the change value of hot and cold helium temperature in the primary loop. If the negative change rate of helium pressure and the change value of hot and cold helium temperature in the primary loop exceed the preset threshold, reduce the opening of the main water supply bypass regulating valve 131 to prevent the above parameters from fluctuating too much.

[0055] The main steam isolation valve 141 is opened to a preset opening degree. It can be slightly opened, and fully opened once the outlet pressure of the steam generator 200 stabilizes. During the full opening of the main steam isolation valve 141, the negative helium pressure change rate and the hot and cold helium temperature change values ​​of the primary loop are acquired. If these values ​​exceed preset thresholds, the opening speed of the main steam isolation valve 141 is slowed down to prevent sudden changes in these parameters. It should be noted that this embodiment does not limit the specific number of main steam isolation valves in the loop system.

[0056] As a specific example, the preset threshold for the negative helium pressure change rate can be set to 300 Pa / s, the preset threshold for the cold helium temperature change value to 25 °C / h, and the preset threshold for the hot helium temperature change value to 2 °C / min. Of course, the preset thresholds for the negative helium pressure change rate and the cold and hot helium temperature change values ​​can also be set to other values, and this embodiment does not impose specific limitations on them.

[0057] S4. Establish a two-loop low-flow circulation: Control the inlet regulating valve of the steam-water separator to open at a preset opening degree, and establish a two-loop low-flow circulation through the steam-water separator exhaust and water intake.

[0058] Specifically, in combination Figure 1 The inlet regulating valve 310 of the steam-water separator 320 is opened to a preset opening degree, establishing a small-flow secondary loop through the steam discharge and water intake of the steam-water separator 320. The inlet regulating valve 310 can be slightly opened. When the steam-water separator 320 reaches the water level, the main feedwater bypass regulating valve 131 is opened wider and the speed of the main feedwater pump 111 is increased to increase the main feedwater flow rate. The pressure in the secondary loop of the steam generator is controlled to be greater than the helium pressure in the primary loop through the inlet regulating valve 310.

[0059] When the water level in the steam-water separator 320 reaches the preset level, the steam-water separator drain valve 330 is automatically activated, and the water quality of the condensate is monitored simultaneously. If the water quality meets the preset requirements, it is discharged to the condenser through the steam-water separator drain valve 330; otherwise, it is discharged to the secondary circuit inspection water tank through the steam-water separator drain valve 330. As a specific example, the preset water level range can be set to 1500mm to 2500mm, preferably 1900mm. The preset water quality requirements can be: colorless and transparent appearance, iron content less than 200μm / L, sodium content less than 80μm / L, and silica content less than 200μm / L.

[0060] S5. Switching the main feedwater system valves and adjusting the secondary loop circulation flow and pressure: When the secondary loop low-flow circulation reaches the preset conditions, fully open the main feedwater isolation valve and gradually close the main feedwater bypass regulating valve. Utilizing the electric feedwater pump hydraulic coupling and the inlet regulating valve, the secondary loop circulation flow and pressure are made to meet the target operating conditions.

[0061] Specifically, in combination Figure 1 After the secondary loop low-flow circulation reaches the preset conditions, the main feedwater isolation valve 140 is fully opened, and the main feedwater bypass regulating valve 131 is gradually closed to switch the main feedwater system valves. Specifically, it can be set so that when the helium temperature of the primary loop and the main feedwater temperature of the secondary loop are balanced, the main feedwater isolation valve 140 is fully opened and the main feedwater bypass regulating valve 131 is gradually closed. During the process of fully opening the main feedwater isolation valve 140 and gradually closing the main feedwater bypass regulating valve 131, the main feedwater flow rate and pressure are acquired in real time. Based on the acquired main feedwater flow rate and pressure, the speed of the main feedwater pump 111 is adjusted to keep the main feedwater flow rate and pressure stable. The electric feedwater pump hydraulic coupling and the inlet regulating valve 310 work together to make the secondary loop circulation flow rate and pressure reach the target operating conditions.

[0062] The water filling method for the steam generator of the high-temperature gas-cooled reactor nuclear power unit in this embodiment can effectively control all parameters of the entire water filling process of the high-temperature gas-cooled reactor steam generator during the process of filling water to the steam generator and establishing the secondary loop circulation. This ensures safe water filling of the high-temperature gas-cooled reactor steam generator and avoids problems such as large temperature shocks in the steam generator tube sheet, excessive negative change rate of helium pressure in the reactor primary loop, and introduction of positive reactions into the reactor abnormality, thus avoiding equipment damage or nuclear safety incidents.

[0063] It should be noted that in the water filling method of the steam generator of the high-temperature gas-cooled reactor nuclear power unit in this embodiment, the preparatory work before filling the steam generator with water is not necessary, and whether or not to carry out such preparatory work is optional.

[0064] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this disclosure.

Claims

1. A method for filling a steam generator in a high-temperature gas-cooled reactor nuclear power unit with water, characterized in that, The method includes: Main feedwater isolation valve from water supply to steam generator: By controlling the speed of the main feedwater pump and the opening of the main feedwater bypass regulating valve, the main feedwater pressure is kept at the preset pressure value and the pressure before the main feedwater isolation valve is greater than the pressure after the valve. Steam generator water inlet: Open the main feedwater isolation valve; control the main steam isolation valve to open to a preset opening degree, and fully open the main steam isolation valve after the steam generator outlet pressure stabilizes; Establish a two-loop low-flow circulation: control the inlet regulating valve of the steam-water separator to open at a preset opening degree, and establish a two-loop low-flow circulation by exhausting steam and introducing water through the steam-water separator; The main water supply system valves are switched to adjust the secondary loop circulation flow and pressure: when the secondary loop small flow circulation reaches the preset conditions, the main water supply isolation valve is fully opened and the main water supply bypass regulating valve is gradually closed; the electric water supply pump hydraulic coupling and the inlet regulating valve are used to make the secondary loop circulation flow and pressure meet the target operating conditions. During the process of opening the main water supply isolation valve, the method further includes: obtaining the negative change rate of helium pressure and / or the change value of hot and cold helium temperature in the first loop; if the negative change rate of helium pressure and / or the change value of hot and cold helium temperature in the first loop exceeds a preset threshold, then the opening degree of the main water supply bypass regulating valve is reduced. The system controls the inlet regulating valve to open at a preset opening degree, establishing a small-flow secondary loop circulation through the steam-water separator's exhaust and water intake. This includes: when the steam-water separator reaches a certain water level, increasing the main feedwater flow rate by widening the main feedwater bypass regulating valve and increasing the main feedwater pump speed; controlling the secondary loop pressure of the steam generator to be greater than the primary loop helium pressure via the inlet regulating valve; when the water level in the steam-water separator reaches a predetermined level, automatically controlling the steam-water separator drain valve; if the water quality in the steam-water separator meets the preset water quality requirements, it is discharged to the condenser through the steam-water separator drain valve; otherwise, it is discharged to the secondary loop inspection water tank through the steam-water separator drain valve. During the process of fully opening the main feedwater isolation valve and gradually closing the main feedwater bypass regulating valve, the method further includes: acquiring the main feedwater flow rate and / or pressure in real time; and adjusting the main feedwater pump speed according to the acquired main feedwater flow rate and / or pressure to stabilize the main feedwater flow rate and / or pressure. Before the main feedwater isolation valve of the steam generator is filled with water, the method also includes preparatory work before filling the steam generator with water, specifically including: controlling the pH value and hydrazine concentration value of the main feedwater to be within the corresponding preset range values; controlling the temperature of the main feedwater to match the tube sheet temperature of the steam generator; draining the water accumulated in front of the main feedwater isolation valve; and keeping the inlet regulating valve in the closed state. The method of controlling the temperature of the main feedwater to match the tube sheet temperature of the steam generator includes: if the temperature requirement of the main feedwater is low, heating the main feedwater by the main feedwater pump to make the temperature of the main feedwater slightly higher than the tube sheet temperature of the steam generator; if the temperature requirement of the main feedwater is high, heating the main feedwater by the heater to make the temperature of the main feedwater slightly higher than the tube sheet temperature of the steam generator.

2. The method according to claim 1, characterized in that, The preset pressure range is 1MPa to 4MPa, and the pressure before the main water supply isolation valve is more than 1MPa greater than the pressure after the valve.

3. The method according to claim 1, characterized in that, During the process of fully opening the main steam isolation valve, the method further includes: Obtain the negative rate of change of helium pressure and / or the temperature change of hot and cold helium in the primary loop; If the negative rate of change of helium pressure and / or the change in temperature of hot and cold helium in the primary loop exceeds a preset threshold, the opening speed of the main steam isolation valve will be slowed down.

4. The method according to claim 1, characterized in that, The predetermined water level range is 1500mm~2500mm.

5. The method according to claim 1, characterized in that, The preset water quality requirements are: colorless and transparent appearance, iron content less than 200 μg / L, sodium content less than 80 μg / L, and silica content less than 200 μg / L.

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