A flexible energy supply system of steam turbine based on cascade utilization and a method for operating the same

Abstract

The present application relates to a kind of flexible energy supply system of steam turbine based on cascade utilization and its operating method, wherein the system includes air-cooled atmospheric condenser, high back pressure condenser, primary peak heater, secondary peak heater, cascade utilization back pressure machine, molten salt heat storage system, steam compressor, steam turbine and drainage system;The air-cooled atmospheric condenser, high back pressure condenser, primary peak heater, secondary peak heater are sequentially connected to constitute four-stage heating energy supply system;The inlet of the air-cooled atmospheric condenser is connected with heating return water pipeline, and the outlet of the secondary peak heater is connected with heating steam supply pipeline.The present application clearly divides heating steam turbine unit into four cascade utilization energy supply systems, can dynamically adjust cascade heating mode according to the demand of heat user and the demand of unit deep peak regulation, relieve the problem of energy crisis caused by deep peak regulation, and improve the ability of unit livelihood heating and industrial steam supply guarantee.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of thermal-electric decoupling of thermal power units, and particularly relates to a steam turbine flexible energy supply system based on cascade utilization and a running method thereof. BACKGROUND

[0002] In recent years, China's energy adheres to the development direction of clean and low-carbon, safe and efficient, vigorously develops clean energy such as wind energy and solar energy, and the adjustment of energy structure is accelerating. However, wind energy and solar energy generation have the characteristics of randomness, intermittency and rapid change. With the increase of new energy generation, combined with the overcapacity of traditional coal-fired power generation, the difficulty of peak regulation of power grid is aggravated, and wind and light are abandoned in some areas. This puts forward new requirements for improving the flexibility and deep peak regulation capacity of active thermal power units.

[0003] At present, the state has proposed a new generation of coal-fired power construction plan, which requires thermal power units to have deeper peak regulation capacity. In order to meet the increasingly severe peak regulation environment of thermal power units, it is urgent to conduct more systematic and in-depth research on deep thermal-electric decoupling and energy cascade utilization means to help thermal power units better play the role of bottom support and power supply. SUMMARY

[0004] The purpose of the present application is to provide a steam turbine flexible energy supply system based on cascade utilization and a running method thereof. In the environment that the new generation of coal-fired power has increasingly strict requirements for the deep peak regulation of thermal power units, the steam turbine is divided into a four-stage heating energy supply system, including an air-cooled normal-pressure exhaust heating, a high-backpressure exhaust heating, a first-stage peak heating and a second-stage peak heating. The four-stage cascade utilization energy supply system is used to improve the external heating and steam supply capacity of the unit under deep peak regulation conditions. The cascade utilization backpressure generator can replace part of the auxiliary power, and can also drive the steam compressor to meet the steam pressure demand.

[0005] The present application provides a steam turbine flexible energy supply system based on cascade utilization, which comprises an air-cooled normal-pressure condenser, a high-backpressure condenser, a first-stage peak heater, a second-stage peak heater, a cascade utilization backpressure generator, a molten salt heat storage system, a steam compressor, a steam turbine and a drainage system.

[0006] The air-cooled normal-pressure condenser, the high-backpressure condenser, the first-stage peak heater and the second-stage peak heater are connected in sequence to form a four-stage heating energy supply system. The inlet of the air-cooled normal-pressure condenser is connected with a heating return water pipeline, and the outlet of the second-stage peak heater is connected with a heating and steam supply pipeline.

[0007] The steam turbine is connected with the air-cooled normal-pressure condenser through a normal-pressure exhaust pipeline, and the air-cooled normal-pressure condenser is connected with the drainage system.

[0008] The steam turbine is connected with the high-backpressure condenser through a high-backpressure exhaust pipeline, and the high-backpressure condenser is connected with the drainage system.

[0009] The steam turbine is connected with the cascade back pressure machine through a middle exhaust steam pipeline, the cascade back pressure machine is connected with the first peak heater, and the first peak heater is connected with the drain system;

[0010] The steam turbine is connected with the molten salt heat storage system through a heat re-exhaust pipeline, the molten salt heat storage system is connected with the second peak heater through a first valve, and the second peak heater is connected with the drain system;

[0011] The cascade back pressure machine is connected with the heat supply and steam supply pipeline through the steam compressor;

[0012] The molten salt heat storage system is connected with the first peak heater through a second valve.

[0013] The application further provides an operation method of the cascade utilization based steam turbine flexible energy supply system, and the operation method comprises the following steps:

[0014] The heat supply return water first enters the air cooling atmospheric condenser, absorbs the air cooling unit atmospheric exhaust heat, and then enters the high back pressure condenser, the first peak heater and the second peak heater in sequence; the heat source of the first peak heater is the steam after cascade power generation and the low-temperature steam discharged by the molten salt heat storage system, and the heat source of the second peak heater is the heat re-exhaust steam after heat release of the molten salt system.

[0015] Further, the operation method further comprises the following steps:

[0016] The steam compressor is used to improve the pressure of industrial steam supply, so as to provide qualified steam meeting the user demand.

[0017] Further, the operation method further comprises the following steps:

[0018] The cascade back pressure machine is used to generate power to replace part of the auxiliary power, and the steam compressor is driven at the same time, so as to meet the steam pressure demand of steam supply.

[0019] Further, the pressure of the high back pressure condenser, the proportion of the heat re-exhaust steam after heat storage of the molten salt heat storage system entering the first peak heater and the second peak heater are dynamically adjusted according to the power generation load and the heat supply load of the unit; the principle of the dynamic adjustment is to optimize the overall income of the unit.

[0020] Further, the molten salt heat storage system can accommodate high-temperature steam in the temperature range of 450-600 DEG C according to the thermal properties of molten salt; the high-temperature steam of the steam turbine continues to enter the primary peak heater and the secondary peak heater to release heat; when the deep regulation stage of the unit exceeds the self thermal-electric decoupling capacity, the molten salt heat storage system is used to supplement the generation of high-temperature steam to relieve the pressure of self thermal-electric decoupling of the unit.

[0021] By the above scheme, the heat supply steam turbine unit is divided into four cascade utilization energy supply systems, and the cascade heat supply mode can be dynamically adjusted according to the heat user demand and the deep regulation demand of the unit, so as to relieve the problem of sharp increase of energy caused by deep regulation, and improve the capacity of civil heating and industrial steam supply of the unit.

[0022] The above description is only a summary of the technical scheme of the present application, in order to more clearly understand the technical means of the present application, and the content of the specification can be implemented. The following will be described in detail with the preferred embodiments of the present application and the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a structure schematic diagram of a steam turbine flexible energy supply system based on cascade utilization according to the present application.

[0024] Marked in the figure:

[0025] 1-air cooling normal pressure condenser; 2-high back pressure condenser; 3-primary peak heater; 4-secondary peak heater; 5-cascade utilization back pressure machine; 6-molten salt heat storage system; 7-steam compressor; 8-steam turbine; 9-drainage system; 10-first valve; 11-second valve. DETAILED DESCRIPTION

[0026] The specific embodiments of the present application will be further described in detail below in combination with the drawings and examples. The following examples are used to illustrate the present application, but not to limit the scope of the present application.

[0027] Reference Figure 1As shown, the embodiment provides a flexible energy supply system of steam turbine based on cascade utilization, which comprises an air-cooled normal-pressure condenser 1, a high-backpressure condenser 2, a first-stage peak heater 3, a second-stage peak heater 4, a cascade utilization backpressure turbine 5, a molten salt heat storage system 6, a steam compressor 7, a steam turbine 8 and a drainage system 9; the air-cooled normal-pressure condenser 1, the high-backpressure condenser 2, the first-stage peak heater 3 and the second-stage peak heater 4 are sequentially connected to form a four-stage heating energy supply system; the inlet of the air-cooled normal-pressure condenser 1 is connected with a heat supply return water pipeline, and the outlet of the second-stage peak heater 4 is connected with a heat supply steam pipeline; the steam turbine is connected with the air-cooled normal-pressure condenser 1 through a normal-pressure exhaust steam pipeline, and the air-cooled normal-pressure condenser 1 is connected with the drainage system 9; the steam turbine is connected with the high-backpressure condenser 2 through a high-backpressure exhaust steam pipeline, and the high-backpressure condenser 2 is connected with the drainage system 9; the steam turbine is connected with the cascade utilization backpressure turbine 5 through a medium-pressure extraction steam pipeline, the cascade utilization backpressure turbine 5 is connected with the first-stage peak heater 3, and the first-stage peak heater 3 is connected with the drainage system 9; the steam turbine is connected with the molten salt heat storage system 6 through a hot re-extraction steam pipeline, the molten salt heat storage system 6 is connected with the second-stage peak heater 4 through a first valve, and the second-stage peak heater 4 is connected with the drainage system 9; the cascade utilization backpressure turbine 5 is connected with the heat supply steam pipeline through the steam compressor 7; and the molten salt heat storage system 6 is connected with the first-stage peak heater 3 through a second valve.

[0028] The operation method of the flexible energy supply system of steam turbine based on cascade utilization is as follows:

[0029] The process on the side of heat network circulating water is as follows: the heat supply return water first enters the air-cooled normal-pressure condenser 1 to absorb the heat of normal-pressure exhaust steam of the air-cooled unit, and then enters the high-backpressure condenser 2, the first-stage peak heater 3 and the second-stage peak heater 4 in sequence; the heat source of the first-stage peak heater 3 comes from the steam after medium-pressure extraction and cascade power generation and the low-temperature steam discharged by the molten salt heat storage system 6; and the heat source of the second-stage peak heater 4 comes from the hot re-extraction steam after heat release of the molten salt system 6. If necessary, the steam compressor 7 is used to improve the pressure of industrial steam supply to provide qualified steam meeting the user demand. The cascade utilization backpressure turbine 5 can be used to generate electricity to replace part of the plant power, and can also be used to drive the steam compressor 7 to meet the steam pressure demand of the industrial steam supply. The medium-pressure extraction steam enters the first-stage peak heater after being first introduced into the cascade utilization backpressure turbine to generate electricity, and the electricity can be used as plant power and can also be used to drive the steam compressor to provide guarantee for the industrial steam pressure. The hot re-direct extraction steam can further reduce the power generation load of the steam turbine main unit, and can improve the heat supply / steam supply capacity of the unit, and the molten salt heat storage system can realize the goal of matching the parameters of the heat supply enterprise and the heat user in stages.

[0030] In the embodiment, the pressure of the high back pressure condenser 2, the proportion of the heat stored in the molten salt heat storage system 6 to the re-extracted steam entering the primary peak heater 3 and the secondary peak heater 4 are dynamically adjusted according to the power generation load and the heat supply load of the unit group; the principle of dynamic adjustment is to optimize the overall revenue of the unit group.

[0031] In the embodiment, the molten salt heat storage system 6 can accommodate high-temperature steam in the temperature range of 450-600°C according to the thermal properties of the molten salt; the high-temperature steam of the steam turbine 8 can continue to be discharged in the molten salt heat storage system 6, and then enter the primary peak heater 3 and the secondary peak heater 4; when the unit enters the deep regulation stage exceeding the self thermal-electric decoupling capacity, the molten salt heat storage system 6 can supplement the generation of high-temperature steam to relieve the pressure of the self thermal-electric decoupling of the unit.

[0032] Through the steam turbine flexible energy supply system based on gradient utilization and the operation method thereof, the heat supply steam turbine unit is clearly divided into four gradient utilization energy supply systems, the gradient heat supply mode can be dynamically adjusted according to the heat user demand and the deep regulation demand of the unit, the problem of sharp increase of energy caused by deep regulation is relieved, and the support capacity of the unit for people's livelihood heat supply and industrial steam supply is improved.

[0033] The above only describes the preferred embodiments of the present application and is not used to limit the present application, and it should be noted that for ordinary skilled in the art, without departing from the technical principles of the present application, a number of improvements and modifications can be made, and these improvements and modifications should be considered as the protection scope of the present application.

Claims

1. A steam turbine flexible energy supply system based on cascade utilization, characterized in that: It includes an air-cooled atmospheric pressure condenser (1), a high back pressure condenser (2), a first-stage peak heater (3), a second-stage peak heater (4), a cascade back pressure machine (5), a molten salt heat storage system (6), a steam compressor (7), a steam turbine (8) and a drain system (9); The air-cooled atmospheric pressure condenser (1), the high back pressure condenser (2), the first-stage peak heater (3), and the second-stage peak heater (4) are sequentially connected to form a four-stage heating energy supply system; The inlet of the air-cooled atmospheric condenser (1) is connected to the heat return water pipeline, and the outlet of the secondary peak heater (4) is connected to the heat steam supply pipeline; The steam turbine is connected to the air-cooled atmospheric pressure condenser (1) via an atmospheric pressure exhaust pipeline, and the air-cooled atmospheric pressure condenser (1) is connected to the drain system (9); The steam turbine is connected to the high back pressure condenser (2) via a high back pressure exhaust pipeline, and the high back pressure condenser (2) is connected to the drain system (9); The steam turbine is connected to the step-utilizing back pressure machine (5) via a middle exhaust steam extraction pipeline, the step-utilizing back pressure machine (5) is connected to the first-stage peak heater (3), and the first-stage peak heater (3) is connected to the drain system (9); The steam turbine is connected to the molten salt heat storage system (6) via a hot re-extraction pipeline, the molten salt heat storage system (6) is connected to the secondary peak heater (4) via a first valve, and the secondary peak heater (4) is connected to the drain system (9); The steps are connected to the heat and steam supply pipeline via the steam compressor (7) using a back pressure machine (5); The molten salt heat storage system (6) is connected to the first-level peak heater (3) via a second valve.

2. An operating method of the steam turbine flexible energy supply system based on cascade utilization according to claim 1, characterized in that: include: The heating return water first enters the air-cooled atmospheric pressure condenser (1), absorbs the heat of the atmospheric pressure exhaust steam of the air-cooled unit, and then enters the high back pressure condenser (2), the first-stage peak heater (3), and the second-stage peak heater (4) in sequence; wherein the heat source of the first-stage peak heater (3) comes from the steam extracted from the middle exhaust and after cascade power generation and the low-temperature steam released by the molten salt thermal storage system (6); the heat source of the second-stage peak heater (4) comes from the hot re-extraction steam after the heat release of the molten salt thermal storage system (6).

3. The operating method according to claim 2, characterized in that: Also includes: The steam compressor (7) is used to increase the pressure of industrial steam supply to provide qualified steam that meets user needs.

4. The operating method according to claim 3, characterized in that: Also includes: The cascade back pressure machine (5) is used to generate electricity to replace part of the factory electricity, and at the same time drives the steam compressor (7) to meet the steam supply pressure requirement.

5. The operating method according to claim 2, characterized in that: The pressure of the high back pressure condenser (2) and the ratio of the hot re-extracted steam after heat storage in the molten salt heat storage system (6) entering the first-stage peak heater (3) and the second-stage peak heater (4) are dynamically adjusted according to the changes in the power generation load and heating load of the unit; the principle of the dynamic adjustment is to optimize the overall benefit of the unit.

6. The operating method according to claim 2, characterized in that: The molten salt thermal storage system (6) absorbs high-temperature steam in the temperature range of 450°C-600°C according to the thermal properties of the molten salt; after the high-temperature steam of the steam turbine (8) releases heat in the molten salt thermal storage system (6), it continues to enter the first-level peak heater (3) and the second-level peak heater (4) to release heat; when the deep adjustment stage entered by the unit exceeds its own thermoelectric decoupling capacity, the molten salt thermal storage system (6) is used to supplement the generation of high-temperature steam to relieve the unit's own thermoelectric decoupling pressure.

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