A coal-fired power generation system thermally decoupled

Abstract

The utility model provides a kind of coal-fired power generation system of thermal-electric decoupling, including low-temperature molten salt tank, high-temperature molten salt tank, heat exchanger, steam generator, coal-fired boiler, steam turbine unit and condenser;The high-temperature high-pressure steam outlet of coal-fired boiler and steam generator is connected to steam turbine;The steam outlet of steam turbine is connected to the steam inlet of condenser, and the water quality outlet of condenser is connected to the water quality inlet of steam generator, and form molten salt heat storage steam circulation loop;The water quality inlet of condenser is connected to the water quality inlet of heat exchanger;The water quality inlet of heat exchanger is connected to the water quality inlet of coal-fired boiler, and form boiler steam circulation loop.The utility model adds molten salt heat storage system for coal-fired unit, decouples coal-fired boiler heat production and steam turbine power generation process, avoids coal-fired boiler load operation while improving coal-fired unit peak shaving capability.The system effectively improves the load regulation capability of small coal-fired power generation unit, and can be used for the transformation and upgrading of coal-fired unit.

Description

TECHNICAL FIELD

[0001] The utility model belongs to coal-fired power generation technical field, concretely relates to a coal-fired power generation system of heat and electricity decoupling. BACKGROUND

[0002] Coal plays an important role in energy structure, and coal-fired power units play a key role in energy security. Under the background of increasing proportion of new energy, coal-fired power units still have important role and significance: first, coal-fired power units can provide stable power supply: new energy power generation has intermittency and instability, and coal power can quickly fill the power gap when new energy output is insufficient, ensuring the safe and stable operation of the power grid. Second, coal-fired power units can be used as peak shaving power: by adjusting the output flexibly, it balances the supply and demand of the power system in cooperation with new energy power generation.

[0003] However, the current coal-fired power unit faces some technical problems in deep peak shaving: first, the stability of boiler combustion: when running at low load, the furnace temperature decreases, and the combustion is insufficient, which can easily lead to accidents such as fire extinguishing and deflagration, affecting the safe operation of the boiler. Second, the poor adaptability of the thermal control system: the traditional control system is difficult to accurately control under large load changes, resulting in unstable operation of the unit. Third, the poor economy of low-load operation: coal consumption increases, and power generation costs rise, and more auxiliary equipment may need to be invested to maintain operation, further increasing costs. For small coal-fired units, the above three problems are more pronounced when deep peak shaving, which brings challenges to coal-fired units participating in grid peak shaving. CONTENT OF THE UTILITY MODEL

[0004] In view of the defects existing in the prior art, the utility model provides a coal-fired power generation system of heat and electricity decoupling, which can effectively solve the above problems.

[0005] The technical scheme adopted by the utility model is as follows:

[0006] The utility model provides a coal-fired power generation system of heat and electricity decoupling, which comprises a low-temperature molten salt tank, a high-temperature molten salt tank, a heat exchanger, a steam generator, a coal-fired boiler, a steam turbine unit and a condenser.

[0007] The molten salt outlet of the low-temperature molten salt tank is connected to the molten salt inlet of the heat exchanger through a pipeline; the molten salt outlet of the heat exchanger is connected to the molten salt inlet of the high-temperature molten salt tank through a pipeline; the molten salt outlet of the high-temperature molten salt tank is connected to the molten salt inlet of the steam generator through a pipeline; and the molten salt outlet of the steam generator is connected to the molten salt inlet of the low-temperature molten salt tank through a pipeline, forming a molten salt circulation loop.

[0008] The high-temperature and high-pressure steam outlet of the coal-fired boiler and the high-temperature and high-pressure steam outlet of the steam generator are both connected to the steam turbine of the steam turbine unit through pipelines to drive the steam turbine to work; the steam outlet of the steam turbine is connected to the steam inlet of the condenser, and in the condenser, the temperature is lowered to condense into liquid water, and the water working medium outlet of the condenser is connected to the water working medium inlet of the steam generator through a first pipeline to form a molten salt heat storage steam circulation loop; the water working medium outlet of the condenser is connected to the water working medium inlet of the heat exchanger through a second pipeline; and the water working medium outlet of the heat exchanger is connected to the water working medium inlet of the coal-fired boiler through a pipeline to form a boiler steam circulation loop.

[0009] The high-temperature tail gas outlet of the coal-fired boiler is connected to the high-temperature tail gas inlet of the heat exchanger.

[0010] Preferably, a first water pump is installed in the first pipeline, and a second water pump is installed in the second pipeline.

[0011] Preferably, a heat exchange coil is arranged in communication between the water working medium inlet and the high-temperature and high-pressure steam outlet of the coal-fired boiler.

[0012] The coal-fired power generation system provided by the utility model has the following advantages:

[0013] The utility model provides a kind of coal-fired power generation system of thermal-electricity decoupling, by increasing a set of molten salt heat storage system for coal-fired unit, heat production of coal-fired boiler and steam turbine power generation process decoupling, avoid coal-fired boiler variable load operation while improving the peak shaving capability of coal-fired unit.Especially, by adjusting molten salt tank capacity, the load regulation capability of small coal-fired power generation unit can be effectively improved, and the utility model can be used for the modification and upgrading of coal-fired unit. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 The utility model provides a kind of coal-fired power generation system of thermal-electricity decoupling structure diagram;

[0015] Wherein:

[0016] 1-low temperature molten salt tank;2-high temperature molten salt tank;3-heat exchanger;4-steam generator;5-coal-fired boiler;6-steam turbine;7-generator;8-condenser;9-power grid;10-first water pump;11-second water pump. DETAILED DESCRIPTION

[0017] In order to make the technical problem, technical scheme and beneficial effect solved by the utility model more clearly understood, the utility model is further described in detail below in combination with drawings and examples.It should be understood that the specific examples described herein are only used to explain the utility model and not to limit the utility model.

[0018] The utility model provides a kind of coal-fired power generation system of thermal-electric decoupling, by increasing a set of molten salt heat storage system for coal-fired unit, decoupling coal-fired boiler heat production and steam turbine power generation process, avoid the load operation of coal-fired boiler changes while promoting the peak shaving capability of coal-fired unit.Especially, by adjusting molten salt tank capacity, the utility model can effectively improve the load regulation capability of small coal-fired generator set, and can be used for the reform upgrading of coal-fired unit.

[0019] Specifically, refer to Figure 1 The utility model provides a kind of coal-fired power generation system of thermal-electric decoupling, including low temperature molten salt tank, high temperature molten salt tank, heat exchanger, steam generator, coal-fired boiler, steam turbine unit and condenser;

[0020] The molten salt outlet of the low temperature molten salt tank is connected to the molten salt inlet of the heat exchanger by pipeline;The molten salt outlet of the heat exchanger is connected to the molten salt inlet of the high temperature molten salt tank by pipeline;The molten salt outlet of the high temperature molten salt tank is connected to the molten salt inlet of the steam generator by pipeline;The molten salt outlet of the steam generator is connected to the molten salt inlet of the low temperature molten salt tank by pipeline, forming molten salt circulation loop;

[0021] The high temperature and high pressure steam outlet of the coal-fired boiler and the high temperature and high pressure steam outlet of the steam generator are both connected to the steam turbine of the steam turbine unit by pipeline, to drive the steam turbine to work;The steam outlet of the steam turbine is connected to the steam inlet of the condenser, and in the condenser, it is condensed to liquid water by cooling, and the water working medium outlet of the condenser is connected to the water working medium inlet of the steam generator by first pipeline, forming molten salt heat storage steam circulation loop;The water working medium outlet of the condenser is connected to the water working medium inlet of the heat exchanger by second pipeline;The water working medium outlet of the heat exchanger is connected to the water working medium inlet of the coal-fired boiler by pipeline, and the water working medium inlet and high temperature and high pressure steam outlet of the coal-fired boiler are communicated with heat exchange coil, forming boiler steam circulation loop;Wherein, first water pump is installed in the first pipeline;Second water pump is installed in the second pipeline.

[0022] The high temperature tail gas outlet of the coal-fired boiler is connected to the high temperature tail gas inlet of the heat exchanger, as the heat source of heat exchanger.

[0023] The composition and principle of the coal-fired power generation system of thermal-electric decoupling provided by the present application are introduced in detail as follows Figure 1

[0024] In Figure 1 , 1-low temperature molten salt tank;2-high temperature molten salt tank;3-heat exchanger;4-steam generator;5-coal-fired boiler;6-steam turbine;7-generator;8-condenser;9-power grid;10-first water pump;11-second water pump.

[0025] According to​Figure 1 , the system from left to right in turn is:

[0026] (1) coal-fired boiler: common coal-fired boiler, no limit to the type, used for heating the liquid water preheated by the heat exchanger, generating high-temperature and high-pressure steam for steam turbine to do work, while generating high-temperature tail gas, providing high-temperature heat source for the heat exchanger;

[0027] (2) heat exchanger: the structure of the heat exchanger is not limited, which needs to be able to fully absorb the heat of the tail gas of the coal-fired boiler and transfer the heat to the low-temperature condensed water and the low-temperature molten salt;

[0028] (3) high-temperature molten salt tank: storing high-temperature molten salt heated by the heat exchanger, the molten salt is usually binary molten salt, and the temperature in the high-temperature molten salt tank is generally about 560 DEG C;

[0029] (4) low-temperature molten salt tank: storing low-temperature molten salt after heat release in the steam generator, and the temperature of the molten salt in the low-temperature molten salt tank is generally about 290 DEG C;

[0030] (5) steam generator: used for transferring the heat in the high-temperature molten salt to the normal-temperature liquid water, generating high-temperature and high-pressure steam for driving the steam turbine to do work;

[0031] (6) steam turbine and generator: the steam turbine utilizes the high-temperature and high-pressure steam from the coal-fired boiler and the steam generator to do work, and the generator connected with the steam turbine converts mechanical energy into electrical energy, thereby completing the power generation process; here, the condensing steam turbine is usually used for power generation;

[0032] (7) condenser: through heat exchange with air or other low-temperature medium, the steam discharged from the steam turbine is cooled and condensed into liquid water. On the one hand, an internal vacuum is formed to reduce the exhaust pressure of the steam turbine; on the other hand, the water working medium is recovered and sent into the coal-fired boiler and the steam generator by two pumps to be reheated;

[0033] (8) power grid: the power grid with a high proportion of new energy installed capacity, the wind and light power output is large during the day, and the power grid has sufficient power; the wind and light power output is small at night, and the power grid is insufficient;

[0034] The arrow lines in the figure are all pipeline connections except that the connection between the generator and the power grid is an electric wire connection.

[0035] The utility model provides a kind of coal-fired power generation system of thermal-electric decoupling, principle as follows:

[0036] (1) coal powder combustion releases heat in coal-fired boiler, on the one hand, heat is transferred to water working medium to generate steam; on the other hand, high-temperature tail gas is delivered to heat exchanger;

[0037] (2) In the molten salt circulation, the low-temperature molten salt from the low-temperature molten salt tank absorbs heat in the heat exchanger to become high-temperature molten salt and is stored in the high-temperature molten salt tank, and the high-temperature molten salt flows to the steam generator to release heat, and the low-temperature molten salt after heat release flows back to the low-temperature molten salt tank for storage, completing the whole circulation;

[0038] (3) In the boiler steam circulation, the water working medium is preheated by the heat exchanger and then enters the coal-fired boiler to absorb heat to become high-temperature and high-pressure steam, the high-temperature and high-pressure steam does work in the steam turbine and then enters the condenser to condense, and the condensed working medium water reenters the heat exchanger and the coal-fired boiler to absorb heat under the action of the pump;

[0039] (4) In the molten salt heat storage steam circulation, the water working medium absorbs heat of the molten salt in the steam generator to become high-temperature and high-pressure steam, the high-temperature and high-pressure steam does work in the steam turbine and then enters the condenser to condense, and the condensed working medium water reenters the steam generator to absorb heat under the action of the pump;

[0040] (5) For the whole power generation system, during the day period, the wind and light resources are sufficient, and the power grid power demand is not large, at this time, only the boiler steam circulation is started, the molten salt heat storage steam circulation is closed, and only the boiler steam is used to drive the steam turbine to generate electricity; the high-temperature tail gas continuously heats the molten salt in the low-temperature molten salt tank, and the molten salt is stored in the high-temperature molten salt tank;

[0041] (6) During the night period, the wind and light resources are insufficient, and the power grid power demand is large, at this time, the boiler steam circulation and the molten salt heat storage steam circulation are started at the same time, so that the steam turbine operates under greater load and generates more power to meet the power grid demand.

[0042] The utility model provides a kind of coal-fired power generation system of thermal-electricity decoupling, with following technical improvements:

[0043] (1) Technical improvement one: by molten salt heat storage, coal-fired boiler heating and steam turbine power generation are decoupled, without frequently starting and stopping boiler or changing boiler load to meet power generation load change demand, and make coal-fired boiler maintain in stable, efficient operating state;

[0044] (2) Technical improvement two: by molten salt heat storage, high-temperature tail gas waste heat is fully collected, and at peak electricity demand period, molten salt heat storage steam circulation and boiler steam circulation can supply steam to steam turbine together, to exert stronger peak regulation capacity;

[0045] (3) Technical improvement three: by increasing molten salt storage tank capacity, the degree of thermal-electricity decoupling of system can be changed, system peak power and peak power duration can be changed, to help existing small-capacity coal power unit to better play the role of regulating power source;

[0046] The above merely is preferred implementation manner of the present application, it should be pointed out, for ordinary skilled person in the technical field, on the premise of not departing from the principle of the present application, can also make several improvements and refinements, these improvements and refinements also should be regarded as the protection scope of the present application.

Claims

1. A thermoelectric decoupled coal-fired power generation system, characterized in that, This includes low-temperature molten salt tanks, high-temperature molten salt tanks, heat exchangers, steam generators, coal-fired boilers, steam turbine units, and condensers; The molten salt outlet of the low-temperature molten salt tank is connected to the molten salt inlet of the heat exchanger via a pipeline; the molten salt outlet of the heat exchanger is connected to the molten salt inlet of the high-temperature molten salt tank via a pipeline; the molten salt outlet of the high-temperature molten salt tank is connected to the molten salt inlet of the steam generator via a pipeline; the molten salt outlet of the steam generator is connected to the molten salt inlet of the low-temperature molten salt tank via a pipeline, forming a molten salt circulation loop; The high-temperature, high-pressure steam outlets of the coal-fired boiler and the steam generator are both connected to the turbine of the turbine unit via pipelines, driving the turbine to perform work. The steam outlet of the turbine is connected to the steam inlet of the condenser, where the steam is cooled and condensed into liquid water. The water outlet of the condenser is connected to the water inlet of the steam generator via a first pipeline, forming a molten salt thermal storage steam circulation loop. The water outlet of the condenser is connected to the water inlet of the heat exchanger via a second pipeline. The water outlet of the heat exchanger is connected to the water inlet of the coal-fired boiler via a pipeline, forming a boiler steam circulation loop. The high-temperature exhaust gas outlet of the coal-fired boiler is connected to the high-temperature exhaust gas inlet of the heat exchanger.

2. The thermoelectric decoupling coal-fired power generation system according to claim 1, characterized in that, A first water pump is installed in the first pipeline; a second water pump is installed in the second pipeline.

3. The thermoelectric decoupling coal-fired power generation system according to claim 1, characterized in that, A heat exchange coil is connected between the water inlet and the high-temperature, high-pressure steam outlet of the coal-fired boiler.

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