A system and method for non-nuclear steam start-up of a sodium-cooled fast reactor turbine

Abstract

The invention discloses a system and method for non-nuclear steam start-up of a sodium-cooled fast reactor steam turbine, comprising an auxiliary steam header, a deaerator, a high-pressure heater, a steam generator, a superheater, a reactor primary / secondary circuit, a steam turbine and a steam turbine shaft seal system; the outlet of the auxiliary steam header is connected to the steam inlet of the deaerator and the steam inlet of the high-pressure heater, the water outlet of the deaerator is connected to the water inlet of the high-pressure heater, the water outlet of the high-pressure heater is connected to the heat absorption side inlet of the steam generator, the heat absorption side outlet of the steam generator is connected to the heat absorption side inlet of the superheater, and the heat absorption side outlet of the superheater is connected to the steam inlet of the steam turbine; the outlet of the reactor primary / secondary circuit is connected to the inlet of the reactor primary / secondary circuit after passing through the heat release side of the steam generator and the heat release side of the superheater in sequence. The system can effectively solve the problem that the sodium-cooled fast reactor steam turbine cannot be started up with non-nuclear steam, and reduce the number of thermal shocks of the reactor primary / secondary circuit.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear power plant commissioning and relates to a system and method for non-nuclear steam start-up of a sodium-cooled fast reactor turbine. Background Art

[0002] Currently, there are generally two technical solutions for using non-nuclear steam to start the steam turbine in nuclear power units: using the heat generated by the friction between the rotation of the primary circuit main pump and the coolant and the heat generated by the primary circuit stabilizer electric heater to increase the temperature of the primary circuit coolant and reactor components for heat storage, so that the steam generator produces steam, or using the steam generated by the auxiliary boiler to increase the speed of the steam turbine and run it at a constant speed, and verifying the performance of the steam turbine and its auxiliary equipment during this period.

[0003] For sodium-cooled fast reactors, the above method has many disadvantages: First, using reactor heat storage to start the turbine requires repeated heat storage, which takes a long time, and the repeated heating and cooling will cause certain thermal shocks to the first and second reactors. Second, the heat generated by the main pumps and electric heaters in the first and second reactor circuits and the system heat storage are limited. Because the deaerator, turbine shaft seal, and high-pressure or low-pressure heaters consume a large amount of steam and are limited by the cooling rate of the first and second circuit equipment, the amount of steam available for the turbine is small, even if the steam pressure and temperature are met, and it cannot meet the turbine start-up requirements. Third, the temperature and pressure of the auxiliary steam are both lower than the required values ​​for the turbine start-up. According to calculations, the auxiliary steam can only start the turbine to 2000 rpm, which cannot meet the requirements of starting the turbine to 3000 rpm and rotating at a constant speed. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a system and method for non-nuclear steam start-up of a sodium-cooled fast reactor turbine. The system and method can effectively solve the problem that the sodium-cooled fast reactor turbine cannot be started up with non-nuclear steam, and reduce the number of thermal shocks in the first and second circuits of the reactor.

[0005] To achieve the above-mentioned object, the non-nuclear steam start-up system of the sodium-cooled fast reactor steam turbine of the present invention comprises an auxiliary steam header, a deaerator, a high-pressure heater, a steam generator, a superheater, a reactor primary / secondary circuit, a steam turbine and a steam turbine shaft seal system;

[0006] The outlet of the auxiliary steam header is connected to the steam inlet of the deaerator and the steam inlet of the high-pressure heater, the water outlet of the deaerator is connected to the water inlet of the high-pressure heater, the water outlet of the high-pressure heater is connected to the heat absorption side inlet of the steam generator, the heat absorption side outlet of the steam generator is connected to the heat absorption side inlet of the superheater, and the heat absorption side outlet of the superheater is connected to the steam inlet of the steam turbine; the outlet of the reactor primary / secondary circuit is connected to the inlet of the reactor primary / secondary circuit after passing through the heat release side of the steam generator and the heat release side of the superheater in sequence.

[0007] It also includes an auxiliary boiler, and the steam outlet of the auxiliary boiler is connected to the inlet of the auxiliary steam header.

[0008] The water outlet of the deaerator is connected to the water inlet of the high-pressure heater through the main feed water pump.

[0009] The water outlet of the high-pressure heater is connected to the heat absorption side inlet of the steam generator through the water supply control valve group.

[0010] The auxiliary steam header is also connected to the turbine shaft seal system.

[0011] A method for non-nuclear steam start-up of a sodium-cooled fast reactor steam turbine comprises the following steps:

[0012] The superheated steam output from the auxiliary steam header is divided into three routes: one route enters the deaerator, one route enters the high-pressure heater, and the other route is supplied to the turbine shaft seal system. After being deoxidized and preheated by the deaerator, the feed water enters the heater for preheating. It then enters the heat absorption side of the steam generator and the heat absorption side of the superheater in sequence to absorb heat and form superheated steam. Finally, it enters the steam turbine to perform work.

[0013] The working fluid output from the reactor primary / secondary circuit enters the heat release side of the steam generator and the heat release side of the superheater in turn to release heat, and then enters the reactor primary / secondary circuit.

[0014] The present invention has the following beneficial effects:

[0015] The system and method for non-nuclear steam start-up of a sodium-cooled fast reactor turbine described in the present invention utilize the primary / secondary circuits of the reactor and the electric heater to store energy during specific operation, while utilizing the superheated steam provided by the auxiliary steam header to preheat the feed water and supply it to the turbine shaft seal system, thereby reducing the cooling rate of the primary / secondary circuits of the reactor, thereby ensuring that the turbine can maintain a stable rated speed for a long time during the non-nuclear start-up. At the same time, the primary / secondary circuits of the reactor do not need to store heat multiple times, and the cooling rate is far less than the design value, thereby improving the continuity and stability of the non-nuclear steam start-up process of the turbine, improving the efficiency of the non-nuclear start-up, and also reducing the number of thermal shocks of the primary / secondary circuits of the reactor, thereby ensuring the safety of the primary / secondary circuits of the reactor during the non-nuclear start-up. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the present invention.

[0017] Among them, 1 is the auxiliary boiler, 2 is the auxiliary steam header, 3 is the deaerator, 4 is the main feed water pump, 5 is the high-pressure heater, 6 is the feed water control valve group, 7 is the steam generator, 8 is the superheater, 9 is the reactor primary / secondary circuit, 10 is the steam turbine, and 11 is the turbine shaft seal system. DETAILED DESCRIPTION

[0018] The present invention is described in further detail below with reference to the accompanying drawings:

[0019] refer to Figure 1 The non-nuclear steam start-up system of a sodium-cooled fast reactor steam turbine of the present invention comprises an auxiliary steam header 2, a deaerator 3, a high-pressure heater 5, a steam generator 7, a superheater 8, a steam turbine 10 and a reactor primary / secondary circuit 9; the outlet of the auxiliary steam header 2 is connected to the steam inlet of the deaerator 3 and the steam inlet of the high-pressure heater 5, the water outlet of the deaerator 3 is connected to the water inlet of the high-pressure heater 5, the water outlet of the high-pressure heater 5 is connected to the heat absorption side inlet of the steam generator 7, the heat absorption side outlet of the steam generator 7 is connected to the heat absorption side inlet of the superheater 8, and the heat absorption side outlet of the superheater 8 is connected to the steam inlet of the steam turbine 10; the outlet of the reactor primary / secondary circuit 9 is connected to the inlet of the reactor primary / secondary circuit 9 after passing through the heat release side of the steam generator 7 and the heat release side of the superheater 8 in sequence.

[0020] The present invention further comprises an auxiliary boiler 1 , the steam outlet of the auxiliary boiler 1 being connected to the inlet of the auxiliary steam header 2 .

[0021] The water outlet of the deaerator 3 is connected to the water inlet of the high-pressure heater 5 via the main feedwater pump 4. The water outlet of the high-pressure heater 5 is connected to the heat absorption side inlet of the steam generator 7 via the feedwater control valve group 6. The auxiliary steam header 2 is also connected to the turbine shaft seal system 11.

[0022] The method for non-nuclear steam start-up of a sodium-cooled fast reactor steam turbine according to the present invention comprises the following steps:

[0023] The superheated steam output from the auxiliary steam header 2 is divided into three paths: one path enters the deaerator 3, one path enters the high-pressure heater 5, and the other path is supplied to the turbine shaft seal system 11. After being deoxygenated and preheated in the deaerator 3, the feedwater enters the heater for preheating. It then enters the heat-absorbing side of the steam generator 7 and the heat-absorbing side of the superheater 8, where it absorbs heat to form superheated steam. Finally, it enters the steam turbine 10 to perform work.

[0024] The working fluid output from the reactor primary / secondary loop 9 enters the heat release side of the steam generator 7 and the heat release side of the superheater 8 in sequence to release heat, and then enters the reactor primary / secondary loop 9.

[0025] Example 1

[0026] The specific working process of this embodiment is as follows:

[0027] The auxiliary boiler 1 generates superheated steam at 2.1MPa, 280℃, and a maximum flow rate of 115t / h, which enters the auxiliary steam header 2. The steam is stabilized to 1.8MPa and 270-274℃ in the auxiliary steam header 2. The steam output from the auxiliary steam header 2 enters the deaerator 3, heating the feed water in the deaerator 3 to 210℃. At the same time, the steam output from the auxiliary steam header 2 is also supplied to the turbine shaft seal system. The feed water pressure of the main feed water pump 4 is adjusted by controlling the speed of the main feed water pump 4, and the feed water flow rate is controlled by the feed water control valve group 6, so that the inlet pressure on the water side of the steam generator 7 is 3.55MPa and the flow rate is 73.56t / h. The steam output from the auxiliary steam header 2 enters the high-pressure heater 5, heating the feed water temperature in the high-pressure heater 5 from 210℃ to 240℃.

[0028] The maximum temperature of the working fluid output from the reactor's primary / secondary loop 9 is 358°C. The feed water absorbs heat in the steam generator 7 and the superheater 8, vaporizing the 240°C feed water into 300°C superheated steam. The required heat absorption is 39.702MW, of which the main pump and electric heater of the reactor's primary / secondary loop 9 provide 17.3MW, and the reactor's primary / secondary loop 9 provides 22.402MW of heat through cooling.

[0029] Calculations show that when using the heat storage and cooling of the reactor's primary / secondary circuit 9 to provide 22.402 MW of heat, the temperature drop rate of the reactor's primary / secondary circuit 9 is 17.43°C / h, far less than the design safety limit of 30°C / h. The reactor's primary / secondary circuit 9 can use a cooling range of 50°C to continuously provide steam for 172 minutes. It takes 95 minutes for the turbine 10 to rush to 3000 rpm. Theoretically, the turbine 10 can operate continuously at the rated speed of 3000 rpm for 77 minutes.

Claims

1. A system for non-nuclear steam start-up of a sodium-cooled fast reactor steam turbine, characterized in that: It includes an auxiliary steam header (2), a deaerator (3), a high-pressure heater (5), a steam generator (7), a superheater (8), a reactor primary / secondary circuit (9), a steam turbine (10) and a steam turbine shaft seal system (11); The outlet of the auxiliary steam header (2) is connected to the steam inlet of the deaerator (3) and the steam inlet of the high-pressure heater (5), the water outlet of the deaerator (3) is connected to the water inlet of the high-pressure heater (5), the water outlet of the high-pressure heater (5) is connected to the heat absorption side inlet of the steam generator (7), the heat absorption side outlet of the steam generator (7) is connected to the heat absorption side inlet of the superheater (8), and the heat absorption side outlet of the superheater (8) is connected to the steam inlet of the steam turbine (10); the outlet of the reactor primary / secondary circuit (9) is connected to the inlet of the reactor primary / secondary circuit (9) after passing through the heat release side of the steam generator (7) and the heat release side of the superheater (8) in sequence; It also includes an auxiliary boiler (1), the steam outlet of the auxiliary boiler (1) is connected to the inlet of the auxiliary steam header (2); The water outlet of the deaerator (3) is connected to the water inlet of the high-pressure heater (5) via the main feed water pump (4).

2. The non-nuclear steam start-up system for a sodium-cooled fast reactor steam turbine according to claim 1, characterized in that: The water outlet of the high-pressure heater (5) is connected to the heat absorption side inlet of the steam generator (7) via the water supply control valve group (6).

3. The non-nuclear steam impulsion system for a sodium-cooled fast reactor steam turbine according to claim 1, characterized in that: The auxiliary steam header (2) is also connected to a steam turbine shaft seal system (11).

4. A method for non-nuclear steam start-up of a sodium-cooled fast reactor steam turbine, characterized in that: The following steps are involved: The superheated steam outputted from the auxiliary steam header (2) is divided into three paths, one of which enters the deaerator (3), one enters the high-pressure heater (5), and the other is supplied to the turbine shaft seal system. The feed water is deoxygenated and preheated in the deaerator (3) and then enters the heater for preheating. The feed water then enters the heat absorbing side of the steam generator (7) and the heat absorbing side of the superheater (8) in sequence to absorb heat and form superheated steam. The steam then enters the steam turbine (10) to perform work. The working fluid output from the reactor primary / secondary loop (9) sequentially enters the heat release side of the steam generator (7) and the heat release side of the superheater (8) to release heat, and then enters the reactor primary / secondary loop (9).

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