Secondary loop steam-water system of steam generator

Abstract

The utility model discloses a secondary loop steam-water system of a steam generator, which belongs to the technical field of nuclear power operation and comprises a reactor, the steam generator, a steam-water separator, a steam turbine, a condenser, a condensate pump, a deaerator, an auxiliary boiler and a pressure equalizing steam supplementing box. The defect that the auxiliary boiler is in a long-term hot standby state is avoided, and meanwhile cascade recycling of energy is achieved; in addition, when the water supply flow fluctuates, the auxiliary water supply loop can be rapidly switched, and the system reliability is high; and the reactor core can be quickly cooled after emergency shutdown, so that the safety of a unit is ensured.

Description

Technical Field

[0001] The utility model belongs to the technical field of nuclear power operation and relates to a secondary circuit steam-water system of a steam generator. Background Art

[0002] The secondary steam-water system of the steam generator includes the steam generator, steam-water separator, steam turbine, generator, condenser, deaerator and its pumps, valves and connecting pipes. The common design scheme of the secondary steam-water system of the direct current steam generator is: the condensate in the condenser is transported to the deaerator through the condensate pump, and after being heated in the deaerator, it is transported to the steam generator through the feed water pump to generate superheated steam, which drives the steam turbine to work and the generator to generate electricity. During the start-up and shutdown process of the unit, the heating steam source of the deaerator comes from external steam, which is supplied by the auxiliary boiler; when the unit is operating normally with load, the heating steam source of the deaerator comes from the steam extraction of each stage of the steam turbine.

[0003] The above design scheme has at least the following deficiencies:

[0004] 1) During the start-up and shutdown phases of the unit, the steam extraction of each stage of the steam turbine cannot be put into use, and the deaerator can only be supplied with steam from the outside to heat the feed water temperature at the secondary inlet of the steam generator. The auxiliary boiler needs to run for a long time, which has the problems of high cost, poor heating effect and instability;

[0005] 2) During the start-up and shutdown and low-load operation of the unit, a large amount of main steam is discharged to the condenser through the bypass system. The high-temperature and high-pressure main steam is directly condensed after being discharged into the condenser, which has a large thermal shock on the condenser. At the same time, the high-temperature main steam discharged into the condenser increases the temperature of the condensate, reduces the efficiency of the steam turbine, and also increases the power consumption of the circulating cooling water pump. Its energy has not been recycled in stages.

[0006] 3) When the unit is operating normally, the auxiliary boiler needs to be in hot standby state for a long time, so that it can provide the deaerator with heating steam source during the normal shutdown process of the unit. The long-term hot standby state is not conducive to the safe and stable operation of the auxiliary boiler, and also increases the energy consumption of the auxiliary boiler;

[0007] 4) When the turbine is shut down without stopping the reactor, all steam extraction at all levels will be lost when the turbine is shut down urgently. Since it takes a period of time for the auxiliary boiler to be ready for external steam supply, the deaerator heating steam source will be lost instantly, and the evaporator inlet feed water temperature will drop sharply, which can easily cause overcooling of the primary circuit and cause a reactor non-shutdown accident;

[0008] 5) When the feedwater flow rate suddenly drops, the feedwater pump has limited ability to automatically adjust the feedwater flow rate. Large fluctuations in the feedwater flow rate can easily trigger the reactor shutdown protection action. In addition, the original design of the feedwater system has no auxiliary feedwater loop, and a failure of the feedwater pump will cause an emergency shutdown;

[0009] 6) After the emergency shutdown of Reactor 1, the cooling of the reactor core relied on natural cooling, which took a long time and resulted in poor economic efficiency of the unit. Utility Model Content

[0010] The purpose of the utility model is to overcome the shortcomings of the above-mentioned prior art and provide a secondary steam-water system for a steam generator, which recovers main steam to the equalizing steam tank during the start-up and shutdown and low-load operation stages of the unit, avoiding the disadvantages of the auxiliary boiler in a long-term hot standby state and realizing the cascade recovery and utilization of energy; in addition, it can quickly switch to the auxiliary feed water circuit when the feed water flow fluctuates, and the system reliability is relatively high; after an emergency shutdown, the core can be quickly cooled to ensure the safety of the unit.

[0011] To achieve the above object, the utility model discloses a secondary steam-water system of a steam generator, comprising a steam generator, a steam-water separator, a steam turbine, a condenser, a deaerator, an auxiliary boiler and a pressure equalizing steam tank;

[0012] The secondary side outlet of the steam generator is divided into four routes, among which the first route is connected with the inlet of the third valve group, the second route is connected with the inlet of the steam turbine, the third route is connected with the inlet of the equalizing pressure steam box, the fourth route is connected with the inlet of the steam-water separator, the water outlet of the steam-water separator is connected with the secondary side inlet of the steam generator, and the steam outlet of the steam-water separator is connected with the inlet of the equalizing pressure steam box; the second-stage steam extraction port of the steam turbine is connected with the inlet of the equalizing pressure steam box; the outlet of the third valve group is divided into two routes, one of which is connected with the inlet of the equalizing pressure steam box, and the other is connected with the inlet of the condenser, and the outlet of the equalizing pressure steam box is connected with the inlet of the deaerator; the outlet of the auxiliary boiler is connected with the equalizing pressure steam box.

[0013] The reactor is connected to the primary side of the steam generator.

[0014] The exhaust port of the steam turbine is connected to the inlet of the condenser, the outlet of the condenser is connected to the inlet of the deaerator through the condensate pump, the outlet of the deaerator is connected to the secondary side inlet of the steam generator, and a first extraction port of the steam turbine is connected to the inlet of the deaerator;

[0015] The secondary side outlet of the steam generator is divided into four routes, among which the first route is connected to the inlet of the third valve group, the second route is connected to the inlet of the turbine through the second valve group, the third route is connected to the inlet of the equalizing steam tank through the seventh valve group, and the fourth route is connected to the inlet of the steam-water separator through the first valve group.

[0016] The outlet of the auxiliary boiler is connected to the pressure equalizing steam tank through the fifth valve group.

[0017] The steam outlet of the steam-water separator is connected to the inlet of the pressure-equalizing steam tank through the eighth valve group.

[0018] The water outlet of the steam-water separator is connected with the secondary side inlet of the steam generator via the water supply tank, the water supply pump and the tenth valve group in sequence.

[0019] The outlet of the deaerator is connected to the secondary side inlet of the steam generator through the feed water pump and the eleventh valve group.

[0020] The first stage steam extraction port of the steam turbine is connected to the inlet of the deaerator through the twelfth valve group, and the second stage steam extraction port of the steam turbine is connected to the inlet of the equalizing pressure steam tank through the sixth valve group.

[0021] The outlet of the third valve group is divided into two routes, one of which is connected to the inlet of the equalizing steam box through the fourth valve group, and the other is connected to the inlet of the condenser through the thirteenth valve group. The outlet of the equalizing steam box is connected to the inlet of the deaerator through the ninth valve group.

[0022] The utility model has the following beneficial effects:

[0023] During the specific operation of the secondary steam-water system of the steam generator described in the utility model, during the startup of the unit, the heat stored in the pressure-equalizing steam box is used to supply the heating steam source to the deaerator, and the feed water temperature on the secondary side inlet of the steam generator is heated, so that the main steam parameters can meet the operating requirements of the steam turbine and the generator as soon as possible, and the startup time of the unit is shortened; during the low-load operation of the unit, the main steam bypass steam is discharged into the pressure-equalizing steam box to supplement the heating steam source of the deaerator, and the auxiliary boiler can be shut down as soon as possible, thereby solving the problem that the auxiliary boiler needs to run for a long time. At the same time, during the normal operation of the unit, the pressure-equalizing steam box is used as a backup steam source, and the auxiliary boiler can be shut down from the hot standby state, which has a good energy-saving effect. In addition, during the unit startup and low-load operation, the main steam bypass steam is discharged into the equalizing steam box for recovery, and does not need to be discharged into the condenser in large quantities, avoiding the problem of large thermal shock to the condenser. At the same time, when the unit is stopped and the reactor is shut down without stopping the machine, the equalizing steam box can timely supply the deaerator with heating steam source, thereby heating the secondary side feed water of the steam generator, avoiding the drastic fluctuation of the feed water temperature at the steam generator inlet, and ensuring the safe and stable operation of the steam generator. In addition, when the feed water flow rate drops suddenly, the feed water system can switch to the auxiliary feed water loop without disturbance, which can quickly stabilize the feed water flow rate of the steam generator; after the emergency shutdown of the reactor, the auxiliary feed water loop is used to quickly remove the heat from the reactor core, which improves the safety of the unit operation and shortens the time for the unit to start again. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of the utility model.

[0025] Among them, 1 is the reactor, 2 is the steam generator, 3 is the steam-water separator, 4 is the steam turbine, 5 is the generator, 6 is the condenser, 7 is the condensate pump, 8 is the deaerator, 9 is the feed water pump, 10 is the auxiliary boiler, 11 is the equalizing steam box, 12 is the make-up water tank, 13 is the make-up water pump, 14 is the first valve group, 15 is the second valve group, 16 is the third valve group, 17 is the fourth valve group, 18 is the fifth valve group, 19 is the sixth valve group, 20 is the seventh valve group, 21 is the eighth valve group, 22 is the ninth valve group, 23 is the tenth valve group, 24 is the eleventh valve group, 25 is the twelfth valve group, and 26 is the thirteenth valve group. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the solution of the utility model, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is only an embodiment of a part of the utility model, not all embodiments, and is not intended to limit the scope of the disclosure of the utility model. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concepts disclosed in the utility model. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the utility model.

[0027] The accompanying drawings show schematic diagrams of structures according to the disclosed embodiments of the utility model. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0028] Embodiment 1

[0029] refer to Figure 1 The secondary steam-water system of the steam generator of the utility model comprises a reactor 1, a steam generator 2, a steam-water separator 3, a steam turbine 4, a generator 5, a condenser 6, a condensate pump 7, a deaerator 8, a feed water pump 9, an auxiliary boiler 10, a pressure equalizing steam tank 11, a water tank 12, a water pump 13, a first valve group 14, a second valve group 15, a third valve group 16, a fourth valve group 17, a fifth valve group 18, a sixth valve group 19, a seventh valve group 20, an eighth valve group 21, a ninth valve group 22, a tenth valve group 23, an eleventh valve group 24, a twelfth valve group 25 and a thirteenth valve group 26;

[0030] The reactor 1 is connected to the primary side of the steam generator 2, and the secondary side outlet of the steam generator 2 is divided into four routes, wherein the first route is connected to the inlet of the third valve group 16, the second route is connected to the inlet of the steam turbine 4 via the second valve group 15, the third route is connected to the inlet of the equalizing pressure steam tank 11 via the seventh valve group 20, and the fourth route is connected to the inlet of the steam-water separator 3 via the first valve group 14. The water outlet of the steam-water separator 3 is connected to the secondary side inlet of the steam generator 2 via the water tank 12, the water pump 13 and the tenth valve group 23 in sequence. The steam outlet of the steam-water separator 3 is connected to the inlet of the equalizing pressure steam tank 11 through the eighth valve group 21; the exhaust port of the steam turbine 4 is connected to the inlet of the condenser 6, the outlet of the condenser 6 is connected to the inlet of the deaerator 8 through the condensate pump 7, the outlet of the deaerator 8 is connected to the secondary side inlet of the steam generator 2 through the feed water pump 9 and the eleventh valve group 24, the first stage steam extraction port of the steam turbine 4 is connected to the inlet of the deaerator 8 through the twelfth valve group 25, and the second stage steam extraction port of the steam turbine 4 is connected to the inlet of the equalizing pressure steam tank 11 through the sixth valve group 19.

[0031] The outlet of the third valve group 16 is divided into two paths, one of which is connected to the inlet of the pressure equalizing steam tank 11 through the fourth valve group 17, and the other is connected to the inlet of the condenser 6 through the thirteenth valve group 26. The outlet of the pressure equalizing steam tank 11 is connected to the inlet of the deaerator 8 through the ninth valve group 22.

[0032] The outlet of the auxiliary boiler 10 is connected to the pressure equalizing steam supply tank 11 via the fifth valve group 18 .

[0033] Embodiment 2

[0034] The working process of this embodiment is:

[0035] 1. Unit startup process

[0036] System initial state: reactor 1, steam generator 2, steam turbine 4, generator 5, condensate pump 7, feed water pump 9 and make-up water pump 13 are not running, the first valve group 14, the third valve group 16, the fourth valve group 17, the fifth valve group 18, the eighth valve group 21, the ninth valve group 22 and the eleventh valve group 24 are open, and the second valve group 15, the sixth valve group 19, the seventh valve group 20, the tenth valve group 23, the twelfth valve group 25 and the thirteenth valve group 26 are closed.

[0037] 1) Reactor 1 starts to start, and condensate pump 7 is started to transport condensate in condenser 6 to deaerator 8. The heating steam source of deaerator 8 comes from pressure-equalizing steam supply tank 11. Pressure-equalizing steam supply tank 11 is supplied with steam by auxiliary boiler 10. After feed water is heated to the target feed water temperature at the inlet of secondary side of steam generator 2 in deaerator 8, it is transported to the secondary side of steam generator 2 through feed water pump 9. After absorbing the heat from reactor 1 entering the primary side of steam generator 2, it becomes steam-water mixture, and then enters steam-water separator 3. Steam separated in steam-water separator 3 is discharged into pressure-equalizing steam supply tank 11, and water separated in steam-water separator 3 is discharged into water supply tank 12, thus completing steam-water recovery in the initial stage of unit startup.

[0038] 2) Reactor 1 starts to increase power, and the working medium at the outlet of the secondary side of steam generator 2 undergoes a phase change, from a steam-water mixture to saturated steam. After all the steam becomes superheated steam, the first valve group 14 is closed, and the second valve group 15 is opened at the same time. The steam enters the steam turbine 4 to perform work and drives the generator 5 to generate electricity. The exhaust steam of the steam turbine 4 enters the condenser 6. After the exhaust steam is condensed in the condenser 6, it is transported to the deaerator 8 through the condensate pump 7. After being heated in the deaerator 8, it is transported to the secondary side of the steam generator 2 by the feed water pump 9. The feed water absorbs the steam. The heat on the primary side of the steam generator 2 becomes steam, and then enters the steam turbine 4 to do work; as the power of the reactor 1 increases, when the steam extraction of the steam turbine 4 meets the heating steam source demand of the deaerator 8, the sixth valve group 19 and the twelfth valve group 25 are opened, and the fifth valve group 18 and the ninth valve group 22 are closed, and the first steam extraction of the steam turbine 4 is used as the heating steam source of the deaerator 8, and the second steam extraction of the steam turbine 4 is used as the steam source of the equalizing steam box 11, so as to form a steam-water self-circulating loop of the unit, until the power of the reactor 1 is increased to full power, and the unit startup is completed.

[0039] 2. Normal shutdown process of the unit

[0040] System initial state: reactor 1, steam generator 2, steam turbine 4, generator 5, condensate pump 7 and feed water pump 9 are running, make-up water pump 13 is stopped, first valve group 14, third valve group 16, fourth valve group 17, fifth valve group 18, seventh valve group 20, ninth valve group 22, tenth valve group 23 and thirteenth valve group 26 are closed, second valve group 15, eighth valve group 21, sixth valve group 19, eleventh valve group 24 and twelfth valve group 25 are opened.

[0041] 1) The reactor 1 starts to reduce power. When the steam extraction of the steam turbine 4 cannot meet the heating steam source demand of the deaerator 8, the ninth valve group 22 is opened, and the sixth valve group 19 and the twelfth valve group 25 are closed at the same time. The pressure equalizing steam tank 11 is used as the heating steam source of the deaerator 8 to ensure that the feed water temperature at the secondary side inlet of the steam generator 2 meets the unit load demand.

[0042] 2) The reactor 1 continues to reduce its power. When the working medium at the outlet of the secondary side of the steam generator 2 undergoes a phase change, from superheated steam to saturated steam, until it becomes a steam-water mixture, the first valve group 14 is opened, the second valve group 15 is closed, the steam turbine 4 and the generator 5 are shut down, the steam-water mixture output from the secondary side of the steam generator 2 is discharged into the steam-water separator 3, the drain water separated in the steam-water separator 3 is discharged into the water supply tank 12, and the steam separated in the steam-water separator 3 is discharged into the pressure equalizing steam supply tank 11, until the power of the reactor 1 drops to zero, and the unit shutdown is completed.

[0043] 3. The process of unit shutdown without stopping the reactor

[0044] System initial state: reactor 1, steam generator 2, steam turbine 4, generator 5, condensate pump 7 and feed water pump 9 are running, make-up water pump 13 is stopped, first valve group 14, third valve group 16, fourth valve group 17, fifth valve group 18, sixth valve group 19, seventh valve group 20, ninth valve group 22, tenth valve group 23 and thirteenth valve group 26 are closed, second valve group 15, eighth valve group 21, eleventh valve group 24 and twelfth valve group 25 are opened.

[0045] After the steam turbine 4 is stopped in an emergency, the generator 5 is shut down, the reactor 1 starts to reduce power, the second valve group 15 is closed, the third valve group 16, the fourth valve group 17, the seventh valve group 20 and the ninth valve group 22 are opened, and the sixth valve group 19 and the twelfth valve group 25 are closed at the same time. The equalizing steam tank 11 is used as the heating steam source for the deaerator 8 to ensure that the feed water temperature at the inlet of the steam generator 2 meets the operation requirements of the steam generator 2. A part of the steam output from the secondary side of the steam generator 2 is discharged into the equalizing steam tank 11 through the third valve group 16 and the fourth valve group 17, and another part of the steam output from the secondary side of the steam generator 2 is discharged into the equalizing steam tank 11 through the seventh valve group 20. The third valve group 16 is put into automatic operation to adjust the steam pressure at the outlet of the secondary side of the steam generator 2 to be constant until the power of the reactor 1 drops to a low-load operation condition to maintain low-power stable operation.

[0046] 4. Operation process of sudden drop in water flow

[0047] System initial state: reactor 1, steam generator 2, steam turbine 4, generator 5, condensate pump 7 and feed water pump 9 are running, make-up water pump 13 is stopped, first valve group 14, third valve group 16, fourth valve group 17, fifth valve group 18, seventh valve group 20, ninth valve group 22, tenth valve group 23 and thirteenth valve group 26 are closed, second valve group 15, eighth valve group 21, sixth valve group 19, eleventh valve group 24 and twelfth valve group 25 are opened.

[0048] When the load fluctuation of the unit causes the feed water flow at the secondary side inlet of the steam generator 2 to decrease, the make-up water pump 13 is started, and the tenth valve group 23 is opened and automatically put into operation to transport the feed water in the make-up water tank 12 to the secondary side of the steam generator 2, and automatically adjust and increase the feed water flow at the secondary side inlet of the steam generator 2 to the normal operating value of the unit, so as to ensure the normal operation of the reactor 1, the steam turbine 4 and the generator 5.

[0049] When the failure of the feed water pump 9 causes the loss of feed water flow at the secondary side inlet of the steam generator 2, the tenth valve group 23 is opened, the eleventh valve group 24 is closed, the make-up water pump 13 is started, and the feed water in the make-up water tank 12 is transported to the secondary side of the steam generator 2 to restore the feed water flow at the secondary side inlet of the steam generator 2; then the tenth valve group 23 is automatically put into operation to adjust the feed water flow at the secondary side inlet of the steam generator 2 to the normal operating value of the unit, so as to ensure the normal operation of the reactor 1, the steam turbine 4 and the generator 5.

[0050] 5. Reactor 1 emergency shutdown and core cooling process

[0051] System initial state: reactor 1, steam generator 2, steam turbine 4, generator 5, condensate pump 7 and feed water pump 9 are running, make-up water pump 13 is stopped, first valve group 14, third valve group 16, fourth valve group 17, fifth valve group 18, seventh valve group 20, ninth valve group 22, tenth valve group 23 and thirteenth valve group 26 are closed, second valve group 15, eighth valve group 21, sixth valve group 19, eleventh valve group 24 and twelfth valve group 25 are opened.

[0052] When the reactor 1 triggers an emergency shutdown, the steam turbine 4 and the generator 5 are shut down, the second valve group 15 is closed, the third valve group 16, the fourth valve group 1, the seventh valve group 20, the ninth valve group 22 and the thirteenth valve group 26 are opened, and the sixth valve group 19 and the twelfth valve group 25 are closed at the same time, and the pressure equalizing steam tank 11 is used as the heating steam source for the deaerator 8 to ensure that the feed water temperature at the inlet of the steam generator 2 meets the operation requirements of the steam generator 2. The first part of the steam output from the secondary side of the steam generator 2 is discharged into the pressure equalizing steam tank 11 through the third valve group 16 and the fourth valve group 17, and the second part of the steam output from the secondary side of the steam generator 2 is discharged into the pressure equalizing steam tank 11 through the seventh valve group 20, and the remaining steam output from the secondary side of the steam generator 2 is discharged into the condenser 6 through the thirteenth valve group 26 to avoid overpressure in the main steam pipeline.

[0053] When the pressure in the main steam pipeline drops to normal pressure, the first valve group 14 is opened, the third valve group 16, the fourth valve group 17, the seventh valve group 20 and the thirteenth valve group 26 are closed, the steam-water mixture output from the secondary side of the steam generator 2 is discharged into the steam-water separator 3, the drain separated in the steam-water separator 3 is discharged into the water supply tank 12, and the steam separated in the steam-water separator 3 is discharged into the pressure equalizing steam supply tank 11.

[0054] After the feed water is heated in the deaerator 8 to the target feed water temperature at the inlet of the secondary side of the steam generator 2, it is transported to the secondary side of the steam generator 2 through the feed water pump 9 to absorb the residual heat of the core of the reactor 1, and then enters the steam-water separator 3 for steam-water separation. At the same time, the make-up water pump 13 is started, and the tenth valve group 23 is opened to transport the drain water in the make-up water tank 12 to the secondary side of the steam generator 2 for replenishing the core cooling feed water until the core temperature of the reactor 1 drops below the cold shutdown threshold, completing the emergency shutdown of the reactor 1 and core cooling.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model is described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the utility model can still be modified or replaced by equivalents, and any modification or equivalent replacement that does not depart from the spirit and scope of the utility model should be included in the scope of protection of the claims of the utility model.

Claims

1. A secondary steam-water system of a steam generator, characterized in that: It comprises a steam generator (2), a steam-water separator (3), a steam turbine (4), a condenser (6), a deaerator (8), an auxiliary boiler (10) and a pressure equalizing steam tank (11); The secondary side outlet of the steam generator (2) is divided into four routes, wherein the first route is connected to the inlet of the third valve group (16), the second route is connected to the inlet of the steam turbine (4), the third route is connected to the inlet of the equalizing steam supply tank (11), and the fourth route is connected to the inlet of the steam-water separator (3). The water outlet of the steam-water separator (3) is connected to the secondary side inlet of the steam generator (2), and the steam outlet of the steam-water separator (3) is connected to the inlet of the equalizing steam supply tank (11); the second-stage steam extraction port of the steam turbine (4) is connected to the inlet of the equalizing steam supply tank (11); the outlet of the third valve group (16) is divided into two routes, one of which is connected to the inlet of the equalizing steam supply tank (11), and the other is connected to the inlet of the condenser (6). The outlet of the equalizing steam supply tank (11) is connected to the inlet of the deaerator (8); the outlet of the auxiliary boiler (10) is connected to the equalizing steam supply tank (11).

2. The secondary steam-water system of the steam generator according to claim 1, characterized in that: The reactor (1) is connected to the primary side of the steam generator (2).

3. The secondary steam-water system of the steam generator according to claim 1, characterized in that: The exhaust port of the steam turbine (4) is connected to the inlet of the condenser (6), the outlet of the condenser (6) is connected to the inlet of the deaerator (8) via the condensate pump (7), the outlet of the deaerator (8) is connected to the secondary side inlet of the steam generator (2), and a first extraction port of the steam turbine (4) is connected to the inlet of the deaerator (8); The secondary side outlet of the steam generator (2) is divided into four paths, wherein the first path is connected to the inlet of the third valve group (16), the second path is connected to the inlet of the steam turbine (4) via the second valve group (15), the third path is connected to the inlet of the pressure equalizing steam tank (11) via the seventh valve group (20), and the fourth path is connected to the inlet of the steam-water separator (3) via the first valve group (14); The outlet of the auxiliary boiler (10) is connected to the pressure equalizing steam supply tank (11) via the fifth valve group (18).

4. The secondary steam-water system of the steam generator according to claim 3, characterized in that: The second-stage steam extraction port of the steam turbine (4) is connected to the inlet of the pressure equalizing steam tank (11) via the sixth valve group (19).

5. The secondary steam-water system of the steam generator according to claim 3, characterized in that: The steam outlet of the steam-water separator (3) is connected to the inlet of the pressure equalizing steam tank (11) via the eighth valve group (21).

6. The secondary steam-water system of the steam generator according to claim 3, characterized in that: The outlet of the pressure equalizing steam supply tank (11) is connected to the inlet of the deaerator (8) via the ninth valve group (22).

7. The secondary steam-water system of the steam generator according to claim 3, characterized in that: The water outlet of the steam-water separator (3) is connected to the secondary side inlet of the steam generator (2) via the water supply tank (12), the water supply pump (13) and the tenth valve group (23) in sequence.

8. The secondary steam-water system of the steam generator according to claim 3, characterized in that: The outlet of the deaerator (8) is connected to the secondary side inlet of the steam generator (2) via the feed water pump (9) and the eleventh valve group (24).

9. The secondary steam-water system of the steam generator according to claim 3, characterized in that: A steam extraction port of the steam turbine (4) is connected to the inlet of the deaerator (8) via a twelfth valve group (25).

10. The secondary steam-water system of the steam generator according to claim 3, characterized in that: The outlet of the third valve group (16) is divided into two paths, one of which is connected to the inlet of the pressure equalizing steam tank (11) through the fourth valve group (17), and the other is connected to the inlet of the condenser (6) through the thirteenth valve group (26).

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