Combined heat and power generation peak regulation system of fused salt heat storage coupling rear-mounted back pressure machine

Abstract

The utility model provides a combined heat and power generation peak regulation system of a fused salt heat storage coupling rear-mounted back pressure machine, which comprises a combined heat and power generation unit, a rear-mounted back pressure unit, a fused salt heat storage device and a steam generation device. The combined heat and power generation unit can give consideration to the electricity utilization requirement and the steam utilization requirement through heat absorption and heat release of the fused salt heat storage device. The heat absorption process and the heat release process of the fused salt heat storage system are mutually independent, the operation flexibility is high, continuous external steam supply of the unit under any working condition can be achieved, and the contradiction between the power grid peak regulation requirement of the heat supply unit and industrial heat supply is solved.

Description

Technical Field

[0001] The utility model belongs to the technical field of cogeneration, and in particular relates to a cogeneration peak-shaving system of a molten salt heat storage coupled with a rear-mounted back pressure machine. Background Art

[0002] With the development of my country's power industry, the capacity of various power grids has continued to expand, and the composition of these grids has also changed. The annual growth rate of municipal electricity consumption has now exceeded that of industrial electricity consumption, and the proportion of industrial electricity consumption has gradually declined. At the same time, the rapid development of renewable energy (photovoltaic, wind power, and other sources) has made grid coordination more complex between traditional thermal power generation (including nuclear power) and renewable energy generation. Currently, it is imperative to increase the grid coverage of renewable energy generation, and peak load regulation of thermal power generation units has become a top priority. Therefore, effective grid peak load regulation is a crucial measure to ensure grid security, stable electricity consumption, and national energy security, and is of great significance.

[0003] The production method in which a power plant uses a steam turbine to produce electricity and uses the steam generated by the steam turbine to provide heat to users is called cogeneration. The unit operating in cogeneration mode is called a cogeneration unit. Compared with units that produce electricity and heat energy separately, cogeneration units can effectively save energy and reduce production costs.

[0004] Due to the operational constraints of "heat-based electricity generation," cogeneration units, when participating in power peak regulation, cannot flexibly adjust their electrical load to meet the grid's power peak regulation requirements in order to ensure external heating demand. Excessive electricity demand leads to a decrease in the cogeneration unit's steam supply capacity and quality, making it difficult to provide stable industrial steam even when the unit is performing low-load peak regulation. Excessive steam demand also leads to a decrease in the cogeneration unit's power supply capacity. Energy storage devices are used in cogeneration units to increase the unit's ability to flexibly adjust its electrical load. This is primarily aimed at cogeneration units used to provide heating for residents in northern China. Energy storage devices can only produce high-temperature hot water or low-parameter steam and are not suitable for cogeneration units with industrial steam supply needs. Utility Model Content

[0005] The purpose of the utility model is to provide a cogeneration peak-shaving system and method of molten salt heat storage coupled with a rear back pressure machine to meet the needs of cogeneration units to adapt to new power systems and improve flexibility. The system can achieve "thermal and electric decoupling" without being restricted by peak-shaving loads and provide stable high-temperature industrial steam.

[0006] To achieve the above-mentioned purpose of the utility model, the utility model provides a combined heat and power peak-shaving system with a molten salt heat storage coupled to a rear back pressure machine, comprising a combined heat and power unit, a rear back pressure unit, a molten salt heat storage device and a steam generating device, wherein:

[0007] The cogeneration unit includes a steam turbine generator set and a steam cylinder;

[0008] The rear-mounted back pressure unit includes a rear-mounted back pressure machine and a generator;

[0009] The molten salt heat storage device includes a high-temperature molten salt tank, a low-temperature molten salt tank and an electric heater;

[0010] The low-temperature molten salt tank is used to store low-temperature molten salt;

[0011] The electric heater is connected to the low-temperature molten salt tank, and the electric heater is connected to the factory power supply;

[0012] The high-temperature molten salt tank is connected to the electric heater;

[0013] The steam generating device is connected to the high-temperature molten salt tank and the low-temperature molten salt tank respectively. The high-temperature molten salt in the high-temperature molten salt tank enters the steam generating device and heats the low-temperature feed water into high-pressure steam. The high-temperature molten salt is converted into low-temperature molten salt and enters the low-temperature molten salt tank.

[0014] One end of the steam generating device is connected to the low-temperature water supply pipeline, and the other end is connected to the rear back pressure machine and the generator in sequence;

[0015] The steam cylinder has a first end connected to the rear back pressure machine for receiving the low-pressure steam discharged by the back pressure machine, a second end connected to the steam generating device for receiving the high-pressure steam after cooling and pressure reduction, a third end connected to the steam turbine generator set for receiving the steam extraction from the steam turbine generator set, and a fourth end connected to the heat user to supply heat to the user.

[0016] Furthermore, the steam generating device includes a preheater, an evaporator, and a superheater connected in sequence.

[0017] Furthermore, a low-temperature molten salt pump is provided between the low-temperature molten salt tank and the electric heater.

[0018] Furthermore, a high-temperature molten salt pump is provided between the high-temperature molten salt tank and the steam generating device.

[0019] Furthermore, a temperature and pressure reducer is provided between the steam cylinder and the steam generating device.

[0020] Furthermore, a water supply pump is connected between the low-pressure water supply pipeline and the steam generating device.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] This effectively addresses the issue of combined heat and power (CHP) units' heating capacity being limited by their power generation output. When the grid requires deep peak-shaving and upward peaking, CHP units can balance electricity and steam demand through the absorption and release of heat from their molten salt thermal storage devices. The independent absorption and release processes of the molten salt thermal storage system provide high operational flexibility, enabling continuous steam supply under all operating conditions. This resolves the conflict between the grid's peak-shaving needs for heating units and industrial heating, facilitating the widespread application of CHP units. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the system structure of the utility model

[0024] Among them: 1- low-temperature molten salt tank; 2- high-temperature molten salt tank; 3- electric heater; 4- steam turbine generator set; 5- sub-cylinder; 6- rear back pressure machine; 7- generator; 8- preheater; 9- evaporator; 10- superheater; 11- low-temperature molten salt pump; 12- high-temperature molten salt pump; 13- water supply pump; 14- desuperheater and pressure reducer. DETAILED DESCRIPTION

[0025] In order to better understand the purpose, structure and function of the present invention, the following is a further detailed description of a heat and power cogeneration peak-shaving system of the present invention with a molten salt heat storage coupled with a rear back pressure machine in conjunction with the accompanying drawings.

[0026] Reference Figure 1, a heat and power combined generation peak-shaving system of molten salt heat storage coupled with a rear back pressure machine, characterized in that: it includes a heat and power combined generation unit, a rear back pressure unit, a molten salt heat storage device and a steam generating device, wherein: the heat and power combined generation unit includes a steam turbine generator set 4 and a sub-cylinder 5; the rear back pressure unit includes a rear back pressure machine 6 and a generator 7; the molten salt heat storage device includes a low-temperature molten salt tank 1, a high-temperature molten salt tank 2 and an electric heater 3; the low-temperature molten salt tank 1 is used to store low-temperature molten salt; the electric heater 3 is connected to the low-temperature molten salt tank 1, and uses the plant electricity to heat the low-temperature molten salt input into the low-temperature molten salt tank 1 to obtain high-temperature molten salt; the high-temperature molten salt tank 2 is connected to the electric heater 3, and is used to store high-temperature molten salt; the steam generating device is connected to the high-temperature molten salt tank 2 and the low-temperature molten salt tank 1, respectively, for The low-temperature feed water is heated into high-pressure steam, and the high-temperature molten salt stored in the high-temperature molten salt tank 2 is cooled to obtain the cooled low-temperature molten salt; the cooled low-temperature molten salt is input into the low-temperature molten salt tank 1; the rear back pressure machine 6 is connected to the steam generating device, and is used to convert thermal energy into mechanical energy through high-pressure steam and discharge low-pressure steam; the generator 7 is coaxially connected to the rear back pressure machine 6, and is used to convert mechanical energy into electrical energy to supply power to the power grid; the steam cylinder 5, the first end of which is connected to the rear back pressure machine 6 for receiving the low-pressure steam discharged by the rear back pressure machine 6, the second end is connected to the steam generating device for receiving the high-pressure steam after cooling and pressure reduction, the third end is connected to the steam turbine generator set 4 for receiving the steam extraction of the steam turbine generator set 4, and the fourth end is connected to the heat user to supply heat to the user.

[0027] The steam generating device includes a preheater 8 , an evaporator 9 , and a superheater 10 .

[0028] A low-temperature molten salt pump 11 is provided between the low-temperature molten salt tank 1 and the electric heater 3 .

[0029] A high-temperature molten salt pump 12 is provided between the high-temperature molten salt tank 2 and the steam generating device.

[0030] A desuperheater and pressure reducer 14 is provided between the steam sub-cylinder 5 and the steam generating device, wherein the desuperheater and pressure reducer 14 is used to reduce the pressure of the high-pressure steam output by the steam generating device by using desuperheating water to obtain low-pressure steam; correspondingly, the steam sub-cylinder 5 is also used to transport the low-pressure steam obtained by the desuperheater and pressure reducer 14 to provide heat to users.

[0031] A water supply pump 13 is connected between the low-pressure water supply and the steam generating device.

[0032] In order to better understand the present invention, the present invention also proposes a combined heat and power peak regulation method of molten salt heat storage coupled with a rear back pressure machine.

[0033] The combined heat and power peak-shaving method of the molten salt heat storage coupled with the rear back pressure machine includes: when the thermal power plant does not participate in power peak-shaving, the steam turbine generator set 4 supplies power and heat to the outside to maintain high-efficiency operation. At this time, the molten salt heat storage device is disconnected from the system and does not absorb or release heat;

[0034] When the thermal power plant participates in power peak regulation and needs to reduce the grid load, the steam turbine generator set 4 reduces the load while ensuring the steam production parameters, and the electric heater 3 is started. The low-temperature molten salt in the low-temperature molten salt tank 1 is transported to the electric heater 3 through the low-temperature molten salt pump 11 for heating and raising the temperature. The obtained high-temperature molten salt enters the high-temperature molten salt tank 2. The molten salt heat storage device absorbs heat, and the electric heater 3 consumes plant electricity to reduce the grid load.

[0035] When the thermal power plant participates in power peak regulation and needs to further reduce the grid load, the load of the steam turbine generator set 4 is further reduced, and the steam production parameters cannot be guaranteed. At this time, the molten salt heat storage device absorbs and releases heat. While performing the above-mentioned heat absorption process, the high-temperature molten salt is transported to the steam generating device through the high-temperature molten salt pump 12 to heat the low-temperature feed water to generate high-pressure steam, which is adjusted to the required parameters by the desuperheater and pressure reducer 14 to supply heat users;

[0036] When the thermal power plant participates in power peak regulation and needs to increase the on-grid power load, the steam turbine generator set 4 maintains high-load operation, and the high-temperature molten salt is transported to the steam generating device through the high-temperature molten salt pump 12 to heat the low-temperature feed water to generate high-pressure steam, and the high-pressure steam is transported to the rear back pressure machine 6 to convert thermal energy into mechanical energy and discharge low-pressure steam; the mechanical energy is converted into electrical energy through the generator 7 to supply power to the power grid, and the first low-pressure steam is transported through the steam cylinder 5 to supply heat to users. At this time, the molten salt heat storage device releases heat, and the rear back pressure machine 6 generates electricity to increase the on-grid power load.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A heat and power cogeneration peak-shaving system with molten salt heat storage coupled with a rear back pressure machine, characterized in that: It includes a combined heat and power unit, a rear back pressure unit, a molten salt heat storage device and a steam generation device, among which: The cogeneration unit comprises a steam turbine generator set (4) and a steam cylinder (5); The rear back pressure unit comprises a rear back pressure machine (6) and a generator (7); The molten salt heat storage device comprises a high-temperature molten salt tank (2), a low-temperature molten salt tank (1) and an electric heater (3); The low-temperature molten salt tank (1) is used to store low-temperature molten salt; The electric heater (3) is connected to the low-temperature molten salt tank (1), and the electric heater (3) is connected to the factory electricity; The high-temperature molten salt tank (2) is connected to the electric heater (3); The steam generating device is connected to the high-temperature molten salt tank (2) and the low-temperature molten salt tank (1) respectively. After the high-temperature molten salt in the high-temperature molten salt tank (2) enters the steam generating device, the low-temperature feed water is heated into high-pressure steam, and the high-temperature molten salt is converted into low-temperature molten salt and enters the low-temperature molten salt tank (1); One end of the steam generating device is connected to a low-temperature water supply pipeline, and the other end is connected to a rear back pressure machine (6) and a generator (7) in sequence; The steam cylinder (5) has a first end connected to the rear back pressure machine (6) for receiving low-pressure steam discharged from the back pressure machine (6), a second end connected to the steam generating device for receiving high-pressure steam after temperature and pressure reduction, a third end connected to the steam turbine generator set (4) for receiving steam extraction from the steam turbine generator set (4), and a fourth end connected to a heat user for supplying heat to the user.

2. According to claim 1, a molten salt heat storage coupled with a rear back pressure machine combined heat and power peak shaving system is characterized by: The steam generating device comprises a preheater (8), an evaporator (9), and a superheater (10) which are connected in sequence.

3. According to claim 1, a molten salt heat storage coupled with a rear back pressure machine combined heat and power peak shaving system is characterized by: A low-temperature molten salt pump (11) is provided between the low-temperature molten salt tank (1) and the electric heater (3).

4. According to claim 1, a molten salt heat storage coupled with a rear back pressure machine combined heat and power peak shaving system is characterized in that: A high-temperature molten salt pump (12) is provided between the high-temperature molten salt tank (2) and the steam generating device.

5. The combined heat and power peak-shaving system of molten salt heat storage coupled with a rear back pressure machine according to claim 1 is characterized in that: A temperature and pressure reducer (14) is provided between the steam sub-cylinder (5) and the steam generating device.

Images