Thermal power peak regulation and frequency regulation system with heat storage, thermal power unit and control method thereof

Abstract

The invention relates to a thermal power peak-shaving and frequency-regulating system with heat storage, a thermal power unit and a control method thereof, comprising: a steam storage tank; a low-temperature and high-temperature molten salt tank; a first and a second molten salt heat exchanger and valves; an inlet of the steam storage tank is connected to a hot side outlet of the second molten salt heat exchanger and is externally connected to a steam extraction pipeline of a medium and low pressure cylinder; a hot side inlet of the second molten salt heat exchanger is externally connected to a new steam pipeline of a high pressure cylinder inlet and a reheated steam pipeline of a medium and low pressure cylinder inlet; a cold side inlet and an outlet of the second molten salt heat exchanger are respectively connected to a low-temperature molten salt tank outlet and a high-temperature molten salt tank inlet; an outlet of the steam storage tank is connected to a cold side inlet of a first molten salt heat exchanger; a cold side outlet of the first molten salt heat exchanger is externally connected to a medium and low pressure cylinder; a hot side inlet and an outlet of the first molten salt heat exchanger are respectively connected to a high-temperature molten salt tank outlet and a low-temperature molten salt tank inlet; and by controlling the valves, the first and second molten salt heat exchangers are controlled to operate separately in the heat release and heat storage process to achieve the purpose of peak-shaving and frequency regulation.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal power generation, and in particular to a thermal power peak-shaving and frequency-regulating system with heat storage and an operating method thereof. Background Art

[0002] my country's energy structure is accelerating its transformation towards a clean and low-carbon direction, and the scale of renewable energy power generation continues to expand. However, due to my country's energy endowment of "rich in coal, poor in oil and little gas", coal still occupies a basic energy position in my country's primary energy structure, and thermal power generation will continue to play an important role in ensuring energy security and promoting the consumption of new energy. In particular, new energy sources such as wind energy and solar energy have strong time-varying characteristics and do not have their own regulation characteristics, which makes it difficult to consume renewable energy power generation. In many areas, there are serious problems of wind and solar abandonment, which makes the regulation of the power grid rely heavily on traditional thermal power generation systems.

[0003] However, due to the characteristics of thermal power units themselves, such as the large and complex combustion system of power station boilers, the minimum stable combustion load of boilers, the minimum condensing volume of turbines, etc., their operating flexibility is limited, making it difficult to meet the frequent and large-scale frequency and peak regulation needs of the power grid.

[0004] Therefore, how to further improve the flexibility of thermal power units to meet the grid regulation needs is a technical problem that needs to be urgently solved in my country's energy industry. Summary of the invention

[0005] In order to solve at least one of the above technical problems, the present invention provides a thermal power peak-shaving and frequency-regulating system with heat storage, comprising: a steam storage tank, a low-temperature molten salt tank, a high-temperature molten salt tank, a first molten salt heat exchanger, a second molten salt heat exchanger, and a first valve, a second valve, a third valve and a fourth valve;

[0006] The inlet of the steam storage tank is connected to the hot side outlet of the second molten salt heat exchanger and is externally connected to the steam extraction pipelines of the medium and low pressure cylinders;

[0007] The hot side inlet of the second molten salt heat exchanger is externally connected to the fresh steam pipeline of the high pressure cylinder inlet and the reheat steam pipeline of the medium and low pressure cylinder inlet;

[0008] The cold side inlet and outlet of the second molten salt heat exchanger are connected to the outlet of the low-temperature molten salt tank and the inlet of the high-temperature molten salt tank respectively;

[0009] The outlet of the steam storage tank is connected to the cold side inlet of the first molten salt heat exchanger;

[0010] The cold side outlet of the first molten salt heat exchanger is externally connected to the medium and low pressure cylinders;

[0011] The hot side inlet and outlet of the first molten salt heat exchanger are connected to the high-temperature molten salt tank outlet and the low-temperature molten salt tank inlet respectively;

[0012] A first valve is arranged on a connecting pipeline between the second molten salt heat exchanger and the fresh steam at the inlet of the external high-pressure cylinder;

[0013] The second valve is arranged on the connecting pipeline between the steam storage tank inlet and the external medium and low pressure cylinder steam extraction;

[0014] A third valve is arranged on the connecting pipeline between the steam storage tank outlet and the first molten salt heat exchanger;

[0015] The fourth valve is arranged on the connecting pipeline between the second molten salt heat exchanger and the reheat steam of the external medium and low pressure cylinder inlet.

[0016] Furthermore, the molten salt operating temperature range of the low-temperature molten salt tank and the high-temperature molten salt tank is: 350-550°C.

[0017] Furthermore, the low-temperature molten salt tank and the high-temperature molten salt tank adopt molten salt Solar salt, HITEC, and HITEC XL.

[0018] Furthermore, the operating pressure of the steam storage tank is: 1.0-3.0MPa.

[0019] On the other hand, the present invention also provides a thermal power unit, comprising: a boiler, a high-pressure cylinder, a medium- and low-pressure cylinder, a regenerator, a condenser, and any of the above-mentioned thermal power peak-shaving and frequency-regulating systems;

[0020] The new steam pipeline at the boiler outlet is connected to the high-pressure cylinder inlet, and the high-pressure cylinder outlet is connected to the boiler reheat; the reheat steam pipeline at the boiler outlet is connected to the medium and low-pressure cylinder inlet; the medium and low-pressure cylinder outlets are connected to the condenser, regenerator and boiler in sequence;

[0021] The high-pressure cylinder and the medium- and low-pressure cylinders also have steam extraction pipelines connected to the regenerator.

[0022] On the other hand, the present invention also provides a thermal power peak-shaving and frequency-regulating control method, which is used in any of the above-mentioned thermal power peak-shaving and frequency-regulating systems or thermal power generating units; comprising:

[0023] When the thermal power unit works normally and there is no peak-shaving demand, the first valve, the second valve, the third valve and the fourth valve are all closed, the steam storage tank stores a certain amount of saturated steam, the low-temperature molten salt tank and the high-temperature molten salt tank store a certain volume of low-temperature molten salt and high-temperature molten salt respectively, the first molten salt heat exchanger and the second lava heat exchanger are both shut down and do not participate in frequency and peak-shaving.

[0024] Furthermore, when the load of the thermal power unit increases and there is a demand for frequency regulation and peak regulation, the third valve is opened, the first molten salt heat exchanger is operated, and the steam stored in the steam storage tank and the molten salt in the high-temperature molten salt tank are released. After the steam is regulated in pressure by the third valve, it enters the first molten salt heat exchanger and is heated to a superheated state by the countercurrent high-temperature molten salt. The heated steam enters the medium and low pressure cylinders to rapidly increase the work flow rate, thereby achieving rapid load increase. The molten salt after heat release flows into the low-temperature molten salt tank, completing the heat release process.

[0025] Furthermore, when the load of thermal power units is reduced and there is a demand for frequency and peak regulation:

[0026] The fourth valve is opened to divert part of the reheated steam from the inlet of the medium and low pressure cylinders. The second molten salt heat exchanger is in operation and releases the molten salt in the low temperature molten salt tank. The diverted reheated steam enters the second molten salt heat exchanger after the pressure is adjusted by the fourth valve, and is cooled by the countercurrent low temperature molten salt and then stored in the steam storage tank. The heated molten salt flows into the high temperature molten salt tank to complete the heat storage process. After the steam is extracted, the flow of the medium and low pressure cylinder 3 is reduced, and the load is reduced.

[0027] Or / and, the first valve is opened to divert part of the new steam from the inlet of the high-pressure cylinder, the second molten salt heat exchanger is operated, and the molten salt in the low-temperature molten salt tank is released, the diverted new steam enters the second molten salt heat exchanger after the pressure is adjusted by the first valve, and is cooled by the countercurrent low-temperature molten salt, and then stored in the steam storage tank, and the heated molten salt flows into the high-temperature molten salt tank, completing the heat storage process; after the steam is extracted, the flow of the high-pressure cylinder and the medium and low-pressure cylinders is reduced, and the load is reduced;

[0028] Or / and the second valve is opened, part of the steam in the medium and low pressure cylinders is extracted, and after the pressure is adjusted by the second valve, it enters the steam storage tank for storage, which quickly reduces the work flow of the medium and low pressure cylinders and reduces the load.

[0029] The heat storage thermal power peak-shaving and frequency-regulating system and its thermal power unit and control method provided by the present invention can control the first molten salt heat exchanger and the second molten salt heat exchanger to operate separately in the heat release and heat storage processes respectively by controlling each valve. The unit load can be reduced by extracting steam, and the unit load can be increased by injecting steam into the medium and low pressure cylinders. The operating load range of the thermal power unit is widened to increase the load variable rate of the thermal power unit to which it is applied, and the flexibility is improved to achieve the purpose of rapid and stable regulation of the thermal power unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The schematic diagram of the structure of an embodiment of the thermal power peak-shaving and frequency-regulating system with heat storage and its thermal power unit of the present invention.

[0031] In the figure: 1 is a boiler, 2 is a high-pressure cylinder, 3 is a medium- and low-pressure cylinder, 4 is a regenerator, 5 is a condenser, 6 is a steam storage tank, 7 is a low-temperature molten salt tank, 8 is a high-temperature molten salt tank, 9 is a first molten salt heat exchanger, 10 is a second molten salt heat exchanger, 111 is a first valve, 112 is a second valve, 113 is a third valve, and 114 is a fourth valve. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] It should be noted that if the embodiments of the present invention involve directional indications, such as up, down, left, right, front, back, etc., then the directional indication is only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly. In addition, if the embodiments of the present invention involve descriptions of "first, second", "S1, S2", "step one, step two", etc., then such descriptions are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of indicated technical features or indicating the execution order of the method, etc. Those skilled in the art can understand that anything that does not violate the gist of the invention under the technical concept of the invention should be included in the protection scope of the present invention.

[0034] In order to improve the load change rate of thermal power units and improve their flexibility and adaptability, the present invention provides a thermal power peak load regulation and frequency regulation system with heat storage, which can be optionally combined with but not limited to Figure 1 The invention is explained in the example of a thermal power plant, but is not limited to this.

[0035] For example, the thermal power unit may optionally but not limited to mainly include a boiler 1, a high-pressure cylinder 2 (such as a high-pressure cylinder of a steam turbine), a medium- and low-pressure cylinder 3, a regenerator 4, and a condenser 5; the new steam pipeline at the outlet of the boiler 1 is connected to the inlet of the high-pressure cylinder 2, and the outlet of the high-pressure cylinder 2 is connected to the reheating of the boiler 1; the reheat steam pipeline at the outlet of the boiler 1 is connected to the inlet of the medium- and low-pressure cylinder 3, and the outlet of the medium- and low-pressure cylinder 3 is connected to the condenser 5, the regenerator 4, and the boiler 1 in sequence;

[0036] In addition, there are steam extraction pipelines between the high-pressure cylinder 2 and the medium- and low-pressure cylinders 3 , which are connected to the regenerator 4 .

[0037] It is worth noting that the thermal power unit is only an application example of the thermal power peak load regulation and frequency modulation system with heat storage of the present invention, but is not limited thereto. For example, the thermal power unit may optionally but not limited to not include the regenerator 4 and the condenser 5, or may also optionally but not limited to include other structural elements.

[0038] More specifically, the present invention proposes a thermal power peak-shaving and frequency-regulating system with heat storage, which mainly includes a steam storage tank 6, a low-temperature molten salt tank 7, a high-temperature molten salt tank 8, a first molten salt heat exchanger 9, a second molten salt heat exchanger 10, and a first valve 111, a second valve 112, a third valve 113 and a fourth valve 114;

[0039] The inlet of the steam storage tank 6 is connected to the hot side outlet of the second molten salt heat exchanger 10 and is externally connected to the steam extraction pipeline of the medium and low pressure cylinder 3;

[0040] The hot side inlet of the second molten salt heat exchanger 10 is externally connected to the fresh steam pipeline of the high pressure cylinder 2 inlet and the reheat steam pipeline of the medium and low pressure cylinder 3 inlet;

[0041] The cold side inlet and outlet of the second molten salt heat exchanger 10 are connected to the outlet of the low-temperature molten salt tank 7 and the inlet of the high-temperature molten salt tank 8 respectively;

[0042] The outlet of the steam storage tank 6 is connected to the cold side inlet of the first molten salt heat exchanger 9;

[0043] The cold side outlet of the first molten salt heat exchanger 9 is externally connected to the medium and low pressure cylinder 3;

[0044] The hot side inlet and outlet of the first molten salt heat exchanger 9 are connected to the outlet of the high-temperature molten salt tank 8 and the inlet of the low-temperature molten salt tank 7 respectively;

[0045] The first valve 111 is arranged on the connecting pipeline between the second molten salt heat exchanger 10 and the fresh steam inlet of the external high-pressure cylinder 2;

[0046] The second valve 112 is arranged on the connection pipeline between the inlet of the steam storage tank 6 and the steam extraction of the external medium and low pressure cylinder 3;

[0047] The third valve 113 is arranged on the connecting pipeline between the outlet of the steam storage tank 6 and the first molten salt heat exchanger 9;

[0048] The fourth valve 114 is arranged on the connecting pipeline between the second molten salt heat exchanger 10 and the reheated steam at the inlet of the external medium and low pressure cylinder 3 .

[0049] Preferably, the molten salt operating temperature range of the low-temperature molten salt tank 7 and the high-temperature molten salt tank 8 may be, but is not limited to, 350-550°C; more preferably, the low-temperature molten salt tank 7 and the high-temperature molten salt tank 8 may be, but is not limited to, molten salt Solar salt, HITEC, HITEC XL; more preferably, the operating pressure of the steam storage tank 6 may be, but is not limited to, 1.0-3.0MPa.

[0050] In this embodiment, a thermal power peak-shaving and frequency-regulating system with heat storage of the present invention is provided, which can control the first molten salt heat exchanger 9 and the second molten salt heat exchanger 10 to operate separately in the heat release and heat storage processes by controlling each valve, so as to improve the load change rate of the thermal power unit to which it is applied, enhance flexibility, and achieve the purpose of rapid and stable regulation of the thermal power unit.

[0051] Specifically, the present invention further provides an operation method of a thermal power peak-shaving and frequency-regulating system with heat storage, which is used to operate the thermal power peak-shaving and frequency-regulating system, and comprises the following steps:

[0052] When the thermal power unit operates normally and there is no peak load demand, the first valve 111, the second valve 112, the third valve 113 and the fourth valve 114 are all closed, the steam storage tank 6 stores a certain amount of saturated steam, the low-temperature molten salt tank 7 and the high-temperature molten salt tank 8 store a certain volume of low-temperature molten salt and high-temperature molten salt respectively, and the first molten salt heat exchanger 9 and the second lava heat exchanger 10 are both stopped and do not participate in frequency regulation and peak load regulation;

[0053] When the load of the thermal power unit increases and there is a demand for frequency regulation and peak regulation, the third valve 113 is opened, the first molten salt heat exchanger 9 is operated, and the steam stored in the steam storage tank 6 and the molten salt in the high-temperature molten salt tank 8 are released. After the steam is regulated in pressure by the third valve 113, it enters the first molten salt heat exchanger 9 and is heated to a superheated state by the countercurrent high-temperature molten salt. The heated steam enters the medium and low pressure cylinder 3 to rapidly increase the work flow rate, thereby realizing a rapid load increase. The molten salt after heat release flows into the low-temperature molten salt tank 7, completing the heat release process.

[0054] When the load of thermal power units is reduced and there is a need for frequency regulation and peak regulation, one or more of the following three operating methods may be selected but is not limited to:

[0055] Solution 1: Open the fourth valve 114 to divert part of the reheated steam at the inlet of the medium and low pressure cylinder 3, operate the second molten salt heat exchanger 10, and release the molten salt in the low temperature molten salt tank 7. The diverted reheated steam enters the second molten salt heat exchanger 10 after the pressure is adjusted by the fourth valve 114, and is cooled by the counter-flowing low temperature molten salt, and then stored in the steam storage tank 6. The heated molten salt flows into the high temperature molten salt tank 8, completing the heat storage process. After the steam is extracted, the flow rate of the medium and low pressure cylinder 3 is reduced, and the load is reduced.

[0056] Solution 2: Open the first valve 111 to divert part of the new steam at the inlet of the high-pressure cylinder 2, operate the second molten salt heat exchanger 10, and release the molten salt in the low-temperature molten salt tank 7. The diverted new steam enters the second molten salt heat exchanger 10 after the pressure is adjusted by the first valve 111, and is cooled by the countercurrent low-temperature molten salt, and then stored in the steam storage tank 6. The heated molten salt flows into the high-temperature molten salt tank 8 to complete the heat storage process; after the steam is extracted, the flow of the high-pressure cylinder 2 and the medium and low-pressure cylinders 3 is reduced, and the load is reduced; compared with Solution 1, Solution 2 can meet the deep peak regulation needs;

[0057] Solution three: Open the second valve 112, extract part of the steam in the medium and low pressure cylinder 3, and after the pressure is adjusted by the second valve 112, enter the steam storage tank 6 for storage, so as to quickly reduce the work flow of the medium and low pressure cylinder 3 and reduce the load.

[0058] For load reduction situations, the above three solutions can be used alone or in combination to quickly reduce the load.

[0059] Advantages of the present invention:

[0060] The present invention can reduce the unit load by extracting steam, and can also increase the unit load by injecting steam into the medium and low pressure cylinders, thereby widening the operating load range of the thermal power unit;

[0061] The present invention uses a combination of molten salt and steam storage tanks to store steam extraction energy, including heat energy and steam itself. When releasing heat, steam can be directly released and heated to a superheated state, which greatly improves the load change rate and meets the needs of rapid response regulation. Boilers with large inertia can also be slowly adjusted to adapt to load changes.

[0062] The present invention utilizes a combination of molten salt and a steam storage tank to ensure that the steam is in an overheated state during steam injection, thereby protecting the steam turbine.

[0063] The above-mentioned thermal power unit and control method are created based on the above-mentioned heat storage thermal power peak-shaving and frequency-regulating system. Its technical functions and beneficial effects are no longer repeated here. The various technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the various technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0064] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A thermal power peak-shaving and frequency-modulating system with heat storage, characterized in that: include: A steam storage tank, a low-temperature molten salt tank, a high-temperature molten salt tank, a first molten salt heat exchanger, a second molten salt heat exchanger, and a first valve, a second valve, a third valve, and a fourth valve; The inlet of the steam storage tank is connected to the hot side outlet of the second molten salt heat exchanger and is externally connected to the steam extraction pipelines of the medium and low pressure cylinders; The hot side inlet of the second molten salt heat exchanger is externally connected to the fresh steam pipeline of the high pressure cylinder inlet and the reheat steam pipeline of the medium and low pressure cylinder inlet; The cold side inlet and outlet of the second molten salt heat exchanger are connected to the outlet of the low-temperature molten salt tank and the inlet of the high-temperature molten salt tank respectively; The outlet of the steam storage tank is connected to the cold side inlet of the first molten salt heat exchanger; The cold side outlet of the first molten salt heat exchanger is externally connected to the medium and low pressure cylinders; The hot side inlet and outlet of the first molten salt heat exchanger are connected to the high-temperature molten salt tank outlet and the low-temperature molten salt tank inlet respectively; A first valve is arranged on a connecting pipeline between the second molten salt heat exchanger and the fresh steam at the inlet of the external high-pressure cylinder; The second valve is arranged on the connecting pipeline between the steam storage tank inlet and the external medium and low pressure cylinder steam extraction; A third valve is arranged on the connecting pipeline between the steam storage tank outlet and the first molten salt heat exchanger; The fourth valve is arranged on the connecting pipeline between the second molten salt heat exchanger and the reheat steam of the external medium and low pressure cylinder inlet.

2. The thermal power peak load regulation and frequency modulation system with heat storage according to claim 1 is characterized in that: The molten salt operating temperature range of the low-temperature molten salt tank and the high-temperature molten salt tank is: 350-550℃.

3. The thermal power peak load regulation and frequency modulation system with heat storage according to claim 1 is characterized in that: Low temperature molten salt tank and high temperature molten salt tank adopt molten salt Solar salt, HITEC and HITEC XL.

4. The thermal power peak load regulation and frequency modulation system with heat storage according to claim 1 is characterized in that: The operating pressure of the steam storage tank is: 1.0-3.0 MPa.

5. A thermal power unit, characterized in that: include: A boiler, a high-pressure cylinder, a medium- and low-pressure cylinder, a regenerator, a condenser, and a thermal power peak-shaving and frequency-regulating system as claimed in any one of claims 1 to 4; The new steam pipeline at the boiler outlet is connected to the high-pressure cylinder inlet, and the high-pressure cylinder outlet is connected to the boiler reheat; the reheat steam pipeline at the boiler outlet is connected to the medium and low-pressure cylinder inlet; the medium and low-pressure cylinder outlets are connected to the condenser, regenerator and boiler in sequence; The high-pressure cylinder and the medium- and low-pressure cylinders also have steam extraction pipelines connected to the regenerator.

6. A thermal power peak load and frequency modulation control method, characterized in that: Used in the thermal power peak load regulation and frequency regulation system according to any one of claims 1 to 4, or the thermal power unit according to claim 5; comprising: When the thermal power unit is working normally and there is no peak shaving demand, the first valve, the second valve, the third valve and the fourth valve are all closed, the steam storage tank stores a certain amount of saturated steam, the low-temperature molten salt tank and the high-temperature molten salt tank store a certain volume of low-temperature molten salt and high-temperature molten salt respectively, the first molten salt heat exchanger and the second molten salt heat exchanger are both shut down and do not participate in frequency regulation and peak shaving.

7. The thermal power peak load and frequency regulation control method according to claim 6, characterized in that: When the load of the thermal power unit increases and there is a demand for frequency and peak regulation, the third valve opens and the first molten salt heat exchanger starts to operate, releasing the steam stored in the steam storage tank and the molten salt in the high-temperature molten salt tank. After the steam pressure is adjusted by the third valve, it enters the first molten salt heat exchanger and is heated to an overheated state by the countercurrent high-temperature molten salt. The heated steam enters the medium and low pressure cylinders to rapidly increase the work flow rate, thereby achieving rapid load increase. The molten salt after heat release flows into the low-temperature molten salt tank, completing the heat release process.

8. The thermal power peak load and frequency regulation control method according to any one of claims 6 to 7, characterized in that: When the load of thermal power units is reduced and there is a demand for frequency and peak regulation: The fourth valve is opened to divert part of the reheated steam from the inlet of the medium and low pressure cylinders. The second molten salt heat exchanger is in operation and releases the molten salt in the low temperature molten salt tank. The diverted reheated steam enters the second molten salt heat exchanger after the pressure is adjusted by the fourth valve, and is cooled by the counter-flowing low temperature molten salt and then stored in the steam storage tank. The heated molten salt flows into the high temperature molten salt tank to complete the heat storage process. After the steam is extracted, the flow of the medium and low pressure cylinders is reduced, and the load is reduced. Or / and, the first valve is opened to divert part of the new steam from the inlet of the high-pressure cylinder, the second molten salt heat exchanger is operated, and the molten salt in the low-temperature molten salt tank is released, the diverted new steam enters the second molten salt heat exchanger after the pressure is adjusted by the first valve, and is cooled by the countercurrent low-temperature molten salt, and then stored in the steam storage tank, and the heated molten salt flows into the high-temperature molten salt tank, completing the heat storage process; after the steam is extracted, the flow of the high-pressure cylinder and the medium and low-pressure cylinders is reduced, and the load is reduced; Or / and the second valve is opened, part of the steam in the medium and low pressure cylinders is extracted, and after the pressure is adjusted by the second valve, it enters the steam storage tank for storage, which quickly reduces the work flow of the medium and low pressure cylinders and reduces the load.

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