CN205135735U - Thermal power system with heat supply of fused salt energy storage power - Google Patents

Abstract

The utility model discloses a thermal power system with heat supply of fused salt energy storage power, through setting up the bypass steam pipework, high pressure condenser and molten salt heater, load of power grid can save through the fused salt because of changing the steam heat that of having a favourable balance, pass through fused salt energy storage power generation subsystem at electric wire netting peak hours and participate in the peak regulation for mains supply, the low scheduling problem of electric wire netting peak regulation and power equipment utilization ratio has not only been solved from this, and guaranteed that power generation system has and has the generating efficiency that coal -fired power unit is suitable now, have and not only realize the power supply of energy storage varying duty but also guarantee high -efficient outstanding advantage of generating electricity.

Description

A thermal power generation system with molten salt energy storage for power supply and heating

technical field

The utility model belongs to thermal power generation technology, in particular to a thermal power generation system with molten salt energy storage for power supply and heat supply.

Background technique

With the improvement of people's living standards and the rapid growth of power load, the peak-to-valley difference in power grid load is increasing. The power supply and power transmission and distribution equipment in the power system are planned and constructed according to the peak load of the power grid, but the duration of the peak load of the power grid is short, resulting in a low utilization rate of power equipment assets planned and constructed to meet the peak load demand. In addition, my country's power supply structure is dominated by thermal power, and coal-fired power generation accounts for about 75% of the total power generation. A large number of thermal power units are in shutdown or low-load operation during off-peak power consumption, which not only makes the utilization rate of power equipment low, but also makes power generation more difficult. The operating reliability of the unit deteriorates and the power generation efficiency decreases. Therefore, solving the problem of power grid peak regulation, improving the utilization rate of power equipment assets and the operation reliability and efficiency of thermal power units are important issues facing the current power industry. The use of energy storage technology can greatly improve the total load factor and actual operating efficiency of thermal power generating units, and enhance the power transmission capacity of the grid. Therefore, the research and development of thermal power generation technology with energy storage system is an urgent need to improve the efficiency of conventional energy generation and transmission, and improve the security and economy of power supply.

Among the various existing energy storage technologies, the molten salt sensible heat storage technology has the advantages of mature technology and low heat storage cost, and has the ability of large-scale commercial application, and is currently widely used in solar thermal power generation systems.

At present, there is an independent molten salt thermal storage power station: it uses mixed molten salt as the thermal storage medium, uses wind power, photovoltaic power, etc. to heat the molten salt to store heat, and then uses molten salt heat storage to heat water to generate water vapor when needed. The steam then drives steam turbines and generators to realize molten salt heat storage and power generation. Although this technical idea has achieved the effect of “shaving peaks and filling valleys” to a certain extent by storing surplus electric energy, but because the current thermal-to-electrical energy conversion efficiency based on the steam Rankine cycle is 33-43%, its “electricity →Thermal→electricity” energy storage power generation technology route has certain shortcomings, that is, a large amount of high-quality electric energy is wasted in the conversion process from heat → electricity. When the system is coupled with a thermal power unit, since the system has experienced a second heat→electricity process (heat release from fuel→electricity→melted salt heat storage→electricity), the thermal efficiency of the steam Rankine cycle with supercritical parameters is 40%. The total power generation efficiency is only 16%, and the shortcoming of low power generation efficiency of the system is more prominent at this time. Considering the fact that my country's power supply structure is dominated by thermal power, a more efficient and reasonable energy storage thermal power generation system is urgently needed to effectively solve the problems of power grid peak-valley differences.

Utility model content

The technical problem to be solved by the utility model is to provide a thermal power generation system with molten salt energy storage for power supply and heat supply, which can not only solve the problem of power grid peak regulation and low utilization rate of power equipment assets, but also realize reliable and efficient power generation .

In order to solve the above technical problems, the utility model adopts the following technical solutions:

On the one hand, a thermal power generation system with molten salt energy storage for power supply and heating, including:

The thermal power generation sub-system includes a thermal power generation unit and a high-pressure condenser. The thermal power generation unit includes a boiler, a first generator and a first steam turbine unit. The boiler is connected to the first steam turbine unit through a main steam pipeline and outputs steam to the first steam turbine unit. , the first steam turbine unit is connected to the high-pressure condenser through a bypass steam pipeline, and part of the steam is transported to the high-pressure condenser, where it is condensed into water through the heat exchange of the high-pressure condenser, and the high-pressure condenser is connected to the boiler through a bypass water supply pipeline. Condensate is fed into the boiler;

The molten salt energy storage power generation subsystem includes the second generator, the second steam turbine unit, steam generator, molten salt heater and cold and hot molten salt tanks. One end of the molten salt heater is connected to the high-pressure condenser through a circulation pipeline. And heat exchange is carried out through the intermediate circulating working medium. The other end of the molten salt heater is connected with the hot molten salt tank, steam generator, and cold molten salt tank to form a molten salt circulation loop. The molten salt in the furnace is heated to form hot molten salt and stored in the hot molten salt tank. The hot molten salt releases heat in the steam generator to form cold molten salt and then returns to the cold molten salt tank. The steam generator is connected to the second steam turbine unit , to deliver the steam generated by the steam generator to the second steam turbine unit for power generation.

The molten salt energy storage power generation sub-system also includes a heating network heater, the steam generator is connected to the heating network heater, and directly supplies heat to the urban heating network through condensation and heat release of steam in the heating network heater.

The intermediate circulating working medium is water or heat transfer oil.

The thermal power generating set is a coal-fired generating set or a thermal generating set burning liquid or gaseous fuel.

The bypass feedwater pipeline is connected in parallel with the main feedwater pipeline of the first steam turbine unit and then connected to the boiler.

The thermal power generation system with molten salt energy storage for power supply and heat supply of the utility model has the following advantages:

1. It is possible to store the heat released by the boiler in the molten salt tank when the power grid is at a low load, so the boiler can run for a long time under the high load state with high power supply efficiency of the unit, and the surplus steam heat energy due to the load change of the power grid can be stored. During the peak load of the grid, the molten salt energy storage and power generation subsystem supplies power to the grid to participate in peak load regulation.

2. The thermal energy stored in the molten salt tank can be heated to form high-temperature and high-pressure steam to drive the molten salt energy storage power generation system to generate electricity, or it can be directly used to heat the circulating water of the urban heating network for heat supply, or power generation and Combined heating operation.

3. Using a high-pressure condenser (the pressure of which is not lower than 2.5MPa) can not only simplify the system flow and reduce the process equipment, but also meet the requirements of safe and reliable working temperature range of molten salt.

4. It avoids the huge energy loss caused by the conversion of "heat→electricity→heat" in the past energy storage system, which not only solves the problems of power grid peak regulation and low utilization rate of power equipment, but also ensures that the power generation system has the same characteristics as the current one. It has the equivalent power generation efficiency of thermal power units, and has the outstanding advantages of realizing energy storage variable load power supply and ensuring efficient power generation.

5. The technological process is simple and the engineering feasibility is very good. Large-scale engineering applications can be realized without the need to develop new power generation equipment host boilers and steam turbines.

6. Because the boiler unit can operate under the high-load state with the best thermal performance for a long time, it not only improves the power generation efficiency of the thermal power unit to obtain economic benefits of power generation and environmental protection benefits of emission reduction, but also achieves the purpose of improving the utilization rate of power equipment assets. It has the effect of reducing the failure risk and maintenance cost of the boiler unit.

Description of drawings

Fig. 1 is a schematic diagram of a thermal power generation system with molten salt energy storage for power supply and heating of the present invention (coal-fired embodiment).

detailed description

The thermal power generation system with molten salt energy storage for power supply and heating of the present utility model is shown in Figure 1, which mainly includes a thermal power generation sub-system (see the dotted line box on the left side of Figure 1) and a molten salt energy storage power generation sub-system (see Figure 1 The dotted line box on the right), and the heat is transferred between the two subsystems by the intermediate circulating working medium (the working medium can be water, or fluid such as heat transfer oil).

Specifically, the thermal power generation sub-system includes a thermal power generating set, which can be a coal-fired generating set widely used in my country as shown in Fig. 1, and of course other liquid or gas fuel-fired Thermal power generation unit. Taking a coal-fired power generation unit as an example, it mainly includes a boiler, a first generator 1, a first steam turbine unit 2, a pulverizing system, a burner 7, a blower, a dust removal system, a desulfurization system, and a chimney. The working principle is the same as that of the conventional thermal power generation system. It mainly generates steam through the boiler, connects with the first steam turbine unit 2 through the main steam pipeline, and outputs steam to the first steam turbine unit 2 for thermal power generation, and then condenses the steam to form water Return to the boiler through the main feedwater pipeline 4 and the first feedwater pump 3a as boiler feedwater. The difference is that the thermal power generation subsystem also includes a high-pressure condenser 5, and a bypass steam pipeline 6 connected to the high-pressure condenser 5 is also set on the first steam turbine unit 2, and part of the steam is transferred through the bypass steam pipeline 6. It is sent to the high-pressure condenser 5, condensed into water through the heat exchange of the high-pressure condenser 5, and then the high-pressure condenser 5 communicates with the main feedwater pipeline 4 of the first steam turbine unit 2 through the bypass feedwater pipeline and the second feedwater pump 3b. And then sent to the boiler for feed water.

The working principle of the molten salt energy storage and power generation sub-system is similar to the working principle of the molten salt heat storage power generation in the existing solar thermal power generation system, and the difference is that the heat source of the utility model comes from the steam heat energy output by the boiler. Specifically, the molten salt energy storage power generation subsystem includes a second generator 9, a second steam turbine unit 10, a steam generator 11, a molten salt heater 12, and cold and hot molten salt tanks, etc., and one end of the molten salt heater 12 is The high-pressure condenser 5 is connected through the circulation pipeline 13, and heat exchange is carried out through the circulation pump 8 and the intermediate circulation working medium. The other end of the molten salt heater 12 is connected with the hot molten salt tank, the hot salt pump 14b, the steam generator 11, The cold molten salt tank and the cold salt pump 14a are connected to form a molten salt circulation loop. When the power grid is low load, the molten salt stored in the cold molten salt tank is heated by the molten salt heater 12 to form hot molten salt and stored in the hot molten salt In the tank, when the power grid is under high load, the hot molten salt in the hot molten salt tank is transported to the steam generator 11, and heat is released in the steam generator 11, which supplies heat for the steam generator to generate steam to form cold molten salt and then returns To the cold molten salt tank, the steam generator 11 is connected with the second steam turbine unit 10, and the steam generated by the steam generator is sent to the second steam turbine unit 10 for driving the generator to generate electricity.

As an example, the molten salt energy storage power generation sub-system also includes a heat network heater 15, the steam generator 11 is connected with the heat network heater 15, and the city heat is generated through the heat release of the steam in the heat network heater 15. Net direct heating. Of course, the heat release of molten salt can also be carried out simultaneously by power generation and heat supply.

The intermediate circulating working medium can be water or heat transfer oil.

The power generation method of the thermal power generation system with molten salt energy storage for power supply and heating mainly includes the following steps:

a. The steam generated by the combustion of the boiler enters the first steam turbine unit 2 through the main steam pipeline for thermal power generation;

b. Through the first steam turbine unit 2, part of the steam is transported to the high-pressure condenser 5 through the bypass steam pipeline 6, and the steam is cooled and condensed into water by the intermediate circulating working fluid in the high-pressure condenser 5, and then passed through the bypass water supply pipeline and After the boiler feedwater in the main water supply pipeline 4 from the first steam turbine unit 2 is mixed, they jointly feed the boiler;

c. store the thermal energy after heat exchange in the hot molten salt tank through the molten salt heater 12;

d. The thermal energy stored in the hot molten salt tank is used in the steam generator 11 to generate steam for the second steam turbine unit 10 to generate electricity, and to provide power for the grid to participate in peak regulation during the peak load of the grid, and the steam generated by the steam generator 11 can also be passed through The heat network heater 15 directly supplies heat to the urban heat network.

In order to ensure that the molten salt does not solidify, the temperature of the cold end of the intermediate circulating working fluid needs to be slightly higher than the lower limit of the temperature range of the molten salt. In this system, the water temperature at the outlet of the feed water pump can be selected to be the same or similar to the feed water temperature of the first steam turbine unit 2, so that the system flow is greatly simplified and the engineering feasibility is better. Therefore, the temperature of the cold end of the intermediate circulating working fluid is the sum of the temperature of the boiler feed water and the difference between the heat transfer end of the cold end of the high-pressure condenser. According to the feed water temperature of common large-scale thermal power units and selecting a reasonable heat transfer difference at the cold end of the high-pressure condenser, it can be known that the temperature of the cold end of the intermediate cycle working medium is in the range of 280-350 ° C, which is in the current common range of mixed molten salt lower temperature range. Therefore, the use of high-pressure condensers can simplify the entire system flow, reduce process equipment, and also meet the requirements of safe and reliable working temperature range of molten salt. Therefore, the technical solution shown in Figure 1 is completely feasible in engineering applications.

When the power generation system described in the utility model is in operation, the boiler unit can run for a long time under a high-load state with high power supply efficiency of the unit, and the surplus steam heat energy due to the load change of the power grid can be stored by the molten salt energy storage power generation sub-system. During the peak load of the grid, the molten salt energy storage and power generation subsystem supplies power to the grid to participate in peak load regulation. The thermal energy stored in the hot molten salt tank can be used to heat water to form high-temperature and high-pressure steam, and then drive the second steam turbine unit 10 and the second generator 9 to generate electricity, or it can be directly used to heat the circulating water of the urban heating network for heating , or combined operation of power generation and heat supply.

The outstanding advantages of the utility model are: due to the joint work of the high-pressure condenser, the molten salt heater 12 and the intermediate circulating working fluid, the sensible heat and latent heat of the steam output by the boiler are recovered and stored in the hot molten salt tank, which is equivalent to The effective use heat of the original boiler is all stored by the molten salt. Therefore, the power generation system described in the utility model avoids the huge energy loss caused by the conversion of "heat→electricity→heat" in the previous energy storage system, thereby not only solving the problems of power grid peak regulation and low utilization rate of power equipment, but also It ensures that the power generation system has the same power generation efficiency as the existing thermal power units, and has the outstanding advantages of realizing energy storage variable load power supply and ensuring efficient power generation.

In addition, the high-pressure condenser is used to heat the intermediate circulating working fluid for heat storage, which avoids the problems of complex heating surface system of the boiler and difficult adjustment and control of boiler operation caused by the direct heating of the intermediate circulating working medium by the boiler flue gas. Therefore, the realization of the system described in the utility model has no special requirements on the existing boiler and steam turbine devices, so the technical solution proposed in the utility model has the advantages of simple process flow and good engineering feasibility, and there is no need to develop a new main engine of power generation equipment Boilers and steam turbines can realize large-scale engineering applications.

Moreover, because the boiler unit operates under the high-load state with the best thermal performance for a long time, it not only improves the power generation efficiency of the thermal power unit to obtain energy-saving economic benefits, emission reduction and environmental protection benefits, but also achieves the purpose of improving the utilization rate of power equipment assets. The effect of reducing the risk of boiler unit failure and maintenance costs.

Although the utility model has an additional set of molten salt energy storage and power generation sub-systems, correspondingly increasing a part of the power plant investment, but at the same time realizes that the power supply capacity of the power plant is greatly improved without adding new units, thereby saving energy. It saves the cost of building and maintaining peak-shaving units, and also saves a large amount of grid construction costs for sending power from the external grid to ensure grid security. Generally speaking, the system described in the utility model still has remarkable investment economy.

However, those of ordinary skill in the art should recognize that the above embodiments are only used to illustrate the utility model, rather than as a limitation to the utility model, as long as within the scope of the essential spirit of the utility model, the above The changes and modifications of the embodiments will fall within the scope of the claims of the present utility model.

Claims (5)

1. A thermal power generation system with molten salt energy storage for power supply and heating, characterized in that it comprises: The thermal power generation sub-system includes a thermal power generation unit and a high-pressure condenser. The thermal power generation unit includes a boiler, a first generator and a first steam turbine unit. The boiler is connected to the first steam turbine unit through a main steam pipeline and outputs steam to the first steam turbine unit. , the first steam turbine unit is connected to the high-pressure condenser through a bypass steam pipeline, and part of the steam is transported to the high-pressure condenser, where it is condensed into water through the heat exchange of the high-pressure condenser, and the high-pressure condenser is connected to the boiler through a bypass water supply pipeline. Condensate is fed into the boiler; The molten salt energy storage power generation subsystem includes the second generator, the second steam turbine unit, steam generator, molten salt heater and cold and hot molten salt tanks. One end of the molten salt heater is connected to the high-pressure condenser through a circulation pipeline. And heat exchange is carried out through the intermediate circulating working medium. The other end of the molten salt heater is connected with the hot molten salt tank, steam generator, and cold molten salt tank to form a molten salt circulation loop. The molten salt in the furnace is heated to form hot molten salt and stored in the hot molten salt tank. The hot molten salt releases heat in the steam generator to form cold molten salt and then returns to the cold molten salt tank. The steam generator is connected to the second steam turbine unit , to deliver the steam generated by the steam generator to the second steam turbine unit for power generation. 2. The thermal power generation system with molten salt energy storage for power supply and heating according to claim 1, characterized in that: the molten salt energy storage power generation sub-system also includes a heating network heater, a steam generator and a heating network heating It is connected with the heater, and directly supplies heat to the urban heating network through the heat release of steam in the heating network heater. 3. The thermal power generation system with molten salt energy storage for power supply and heat supply according to claim 1, characterized in that: the intermediate circulation working medium is water or heat transfer oil. 4. The thermal power generation system with molten salt energy storage for power supply and heat supply according to claim 1, characterized in that: the thermal power generating set is a coal-fired generating set or a thermal generating set using liquid or gaseous fuel. 5. The thermal power generation system with molten salt energy storage for power supply and heat supply according to claim 1, characterized in that: the bypass water supply pipeline is connected in parallel with the main water supply pipeline of the first steam turbine unit to the boiler.