A new type of heat supply power plant thermal peak shaving system with complementary optical and coal energy

Abstract

The present invention relates to the field of electric power, and specifically to a thermal peak-shaving system for a new type of thermal power plant complementary to light and coal. The oil pipeline between the oil outlet and the oil inlet of the trough-type heat collecting device is sequentially provided with a hot oil heat storage tank, a high-temperature oil-water heat exchanger, a low-temperature oil-water heat exchanger, a cold oil heat storage tank and an oil transfer pump along the flow direction of the internal heating oil. The condensate main pipe at the bottom of the condenser is provided with a condensate pump. The condensate main pipe at the outlet of the condensate pump is connected to the water side inlet of the high-temperature oil-water heat exchanger through the water inlet pipe of the high-temperature oil-water heat exchanger. The heat is supplemented for the heating extraction steam through an external heat source, breaking the heat user's demand for the heating extraction steam parameters, limiting the problem of variable load operation of the cogeneration unit, thereby enhancing the peak-shaving flexibility of the unit. This system can also adopt different operation modes one and two according to the actual peak-shaving demand of the power grid, thereby realizing a flexible operation mode integrating heating, power generation and peak-shaving.

Description

Technical Field

[0001] The present invention relates to the field of electric power, and in particular to a new type of thermal peak-shaving system for a heating power plant that complements light and coal. Background Art

[0002] Cogeneration (CHP) has been widely adopted and rapidly developed as a means of improving energy efficiency. It enables thermal power plants to simultaneously meet the needs of both heating and power generation, effectively increasing their operational efficiency. In actual operation, a heating plant primarily meets the heating needs of heat users, followed by increased power generation. Conventional CHP plants employ a "heat-to-electricity" or "power-to-heat" model to achieve these goals. With economic development, not only is residential heating demand increasing, but industrial heat use is also increasing, accounting for one-fifth of global energy consumption. Traditional thermal power generation operates at only around 30%, wasting significant resources and heat. This means that nearly half of the heat energy generated during thermal power plant operation is lost. Utilizing this energy could meet the heating needs of residents near the power plant. CHP technology can achieve this goal, increasing energy utilization to 80% and significantly improving the utilization of raw material heat. CHP reduces residential heating electricity demand, making it more environmentally friendly and energy-efficient than individual coal-fired heating. Heating from power plants can reduce the environmental requirements of surrounding industries and is of great significance in terms of economic benefits and convenience for residents' lives.

[0003] The peak-shaving capacity of cogeneration units often struggles to meet the grid's peak-shaving needs while maintaining sufficient heating capacity. This problem is exacerbated by the inverse peak-shaving characteristics of renewable energy sources such as wind, hydro, and photovoltaic power. However, combining cogeneration with solar thermal power generation systems can effectively improve the units' peak-shaving capacity and ensure flexible peak-shaving capabilities. Solar thermal-assisted cogeneration can be used to provide heating and power generation, increasing the units' generating load while also allowing for more generation capacity to be allocated to wind, solar, and hydropower plants.

[0004] Traditional cogeneration units operate based on a "heat-to-power" model, limiting their peak-shaving capabilities while meeting user heating needs. For example, in northern China, where thermal power generation is plentiful, peak-shaving capacity during the severe cold season reaches 13.40 GW. Cogeneration units contribute a small portion of this peak-shaving capacity, accounting for approximately half of the 78% of installed thermal power capacity. However, their deep peak-shaving capacity accounts for only 10% to 20%, leaving significant room for peak-shaving capacity in heating units.

[0005] To improve the peak-shaving capacity of traditional cogeneration units, researchers both domestically and internationally have explored using solar thermal collectors, heat storage devices, and electric boilers as external heat sources. These technologies, while effective in achieving peak-shaving performance, are often limited by safety concerns related to boilers and turbines, making deep peak-shaving difficult. Combining existing research and shortcomings, this design system modifies the operating mode of a solar-coal-based hybrid heating and power generation system by installing a throttling valve. By blocking the pipeline from the third-stage high-pressure heater's steam extraction, the integrated system reduces the power increase required by the cogeneration unit, thereby only supplementing the heat extraction steam for the cogeneration unit. By supplementing the heat extraction steam with an external heat source, the system overcomes the heat user's demand for heat extraction steam parameters and limits the variable load operation of the cogeneration unit, thereby enhancing the unit's peak-shaving flexibility and achieving a flexible operating mode that integrates heating, power generation, and peak-shaving. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the defects of the above-mentioned technologies and provide a new type of thermal peak-shaving system for a heating power plant that complements light and coal.

[0007] To solve the above technical problems, the technical solution provided by the present invention is a new type of thermal peak-shaving system for a solar-coal-combined heating power plant, comprising a boiler, a high-pressure cylinder, an intermediate-pressure cylinder, a low-pressure cylinder, a condenser, a trough-type heat collection device, and a heat network heater. The system is characterized in that: a hot oil heat storage tank, a high-temperature oil-water heat exchanger, a low-temperature oil-water heat exchanger, a cold oil heat storage tank, and an oil transfer pump are sequentially arranged in the oil pipeline between the oil outlet and the oil inlet of the trough-type heat collection device along the flow direction of the internal heating oil;

[0008] The condensate jellyfish pipe at the bottom of the condenser is provided with a condensate pump, the condensate jellyfish pipe at the outlet of the condensate pump is connected to the water side inlet of the high-temperature oil-water heat exchanger through the water inlet pipe of the high-temperature oil-water heat exchanger, and the water side outlet of the high-temperature oil-water heat exchanger is connected to the steam inlet pipe of the No. 3 high-pressure heater through the steam outlet pipe of the high-temperature oil-water heat exchanger;

[0009] The intermediate pressure cylinder exhaust manifold is connected to the low-temperature oil-water heat exchanger steam inlet pipe, the steam outlet of the low-temperature oil-water heat exchanger steam inlet pipe is connected to the steam side inlet of the low-temperature oil-water heat exchanger, the steam side outlet of the low-temperature oil-water heat exchanger is connected to the steam side inlet of the heat network heater through the low-temperature oil-water heat exchanger steam outlet pipe, and the steam side outlet of the heat network heater is connected to the condensate outlet pipe of the No. 5 low-pressure heater through a drain pipe;

[0010] The water side of the heating network heater is connected to the user through a pipeline.

[0011] As an improvement, the heating oil inside the trough type thermal collector is heated by a solar device.

[0012] As an improvement, the water inlet pipe body of the high-temperature oil-water heat exchanger is provided with a booster pump and a dynamic throttle valve in sequence along the flow direction of the internal fluid.

[0013] The advantages of the present invention compared with the prior art are:

[0014] The solar thermal steam is used to replace the third-stage high-pressure heater extraction steam as a transformation plan. In the solar-coal complementary heating and power generation system, a dynamic throttle valve is installed on the pumping pipe at the condenser outlet section for providing the working medium heated by the solar thermal field and the steam connection pipe for the solar thermal field to replace the third-stage high-pressure heater. This is shown in the thermal peak-shaving system of the solar-coal complementary new heating and power plant.

[0015] By changing the operating mode of the solar-coal complementary heating and power generation integrated system through a dynamic throttling valve, and according to actual conditions, blocking the extraction steam pipeline of the third-stage high-pressure heater, which is replaced by steam from the solar collector field, the integrated system reduces the need to increase the power generation of the cogeneration unit, thereby only supplementing the heat of the heating extraction steam for the cogeneration unit. By supplementing the heating extraction steam with heat from an external heat source, the heat user's demand for heating extraction steam parameters is eliminated, limiting the variable load operation of the cogeneration unit and thus enhancing the unit's peak-shaving flexibility. This system can also adopt different operating modes one and two according to the actual peak-shaving needs of the power grid, thus achieving a flexible operating mode that integrates heating, power generation, and peak-shaving. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the peak shaving system;

[0017] Figure 2 This is a schematic diagram of a trough solar collector system.

[0018] Figure 1-Figure 2 Shown: 1. Boiler, 2. High-pressure cylinder, 3. Medium-pressure cylinder, 4. Low-pressure cylinder, 5. Generator, 6. Deaerator, 7. Trough-type thermal collector, 701. Cold oil heat storage tank, 702. Hot oil heat storage tank, 703. Oil transfer pump, 8. High-temperature oil-water heat exchanger, 801. High-temperature oil-water heat exchanger water inlet pipe, 802. High-temperature oil-water heat exchanger steam outlet pipe, 9. Low-temperature oil-water heat exchanger, 901. Low-temperature oil-water heat exchanger steam inlet pipe, 902. Low-temperature oil-water heat exchanger steam outlet pipe, 10. Heat network heater, 11. Dynamic throttle valve, 12. Condenser, 13. No. 3 high-pressure heater, 14. No. 5 low-pressure heater, 15. Condensate pump, 16. User, 17. Feed water pump, 18. Booster pump, 19. Solar device, 20. Drain pipe. DETAILED DESCRIPTION

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of 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. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0020] In the description of the embodiments of the present invention, it should be noted that if the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or the orientation or position relationship in which the product of the invention is usually placed when in use. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, it should not be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description and should not be understood as indicating or implying relative importance.

[0021] Furthermore, the use of terms such as "horizontal," "vertical," and "overhanging" does not necessarily imply that the component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," not that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0022] In the description of the embodiments of the present invention, "a plurality of" means at least two.

[0023] In the description of the embodiments of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0024] The following is a further detailed description of the thermal peak-shaving system of a new type of thermal power plant complementary to light and coal according to the present invention with reference to the accompanying drawings.

[0025] Combined with attachment Figure 1-Figure 2A new type of thermal peak-shaving system for a solar-coal-based complementary heating power plant includes a boiler 1, a high-pressure cylinder 2, an intermediate-pressure cylinder 3, a low-pressure cylinder 4, a condenser 12, a trough-type heat collector 7, and a heat network heater 10. The system is characterized in that a hot oil storage tank 702, a high-temperature oil-water heat exchanger 8, a low-temperature oil-water heat exchanger 9, a cold oil storage tank 701, and an oil transfer pump 703 are sequentially provided along the internal heating oil flow direction in the oil pipeline between the oil outlet and the oil inlet of the trough-type heat collector 7.

[0026] The condensate jelly pipe at the bottom of the condenser 12 is provided with a condensate pump 15. The condensate jelly pipe at the outlet of the condensate pump 15 is connected to the water side inlet of the high-temperature oil-water heat exchanger 8 through the high-temperature oil-water heat exchanger water inlet pipe 801. The water side outlet of the high-temperature oil-water heat exchanger 8 is connected to the steam inlet pipe of the No. 3 high-pressure heater 13 through the high-temperature oil-water heat exchanger steam outlet pipe 802.

[0027] The exhaust manifold of the intermediate pressure cylinder 3 is connected to the low-temperature oil-water heat exchanger steam inlet pipe 901, the steam outlet of the low-temperature oil-water heat exchanger steam inlet pipe 901 is connected to the steam side inlet of the low-temperature oil-water heat exchanger 9, the steam side outlet of the low-temperature oil-water heat exchanger 9 is connected to the steam side inlet of the heat network heater 10 through the low-temperature oil-water heat exchanger steam outlet pipe 902, and the steam side outlet of the heat network heater 10 is connected to the condensate outlet pipe of the No. 5 low-pressure heater 14 through the drain pipe 20;

[0028] The water side of the heating network heater 10 is connected to the user 16 through a pipeline.

[0029] As a preferred implementation scheme of this embodiment, the heating oil inside the trough type thermal collector device 7 is heated by a solar device 19 .

[0030] As a preferred implementation scheme of this embodiment, the water inlet pipe 801 of the high-temperature oil-water heat exchanger is provided with a booster pump 18 and a dynamic throttle valve 11 in sequence along the flow direction of the internal fluid.

[0031] When the present invention is implemented, it includes two parts: a trough heat collecting device and a cogeneration part. Among them, the oil pipeline between the oil outlet and the oil inlet of the trough heat collecting device 7 is sequentially provided with a hot oil heat storage tank 702, a high-temperature oil-water heat exchanger 8, a low-temperature oil-water heat exchanger 9, a cold oil heat storage tank 701 and an oil transfer pump 703 along the internal heating oil flow direction. The operation process is: the solar energy device 19 converts solar energy into heat to heat the trough heat collecting device 7, the hot oil at the outlet of the hot trough heat collecting device 7 is stored in the hot oil heat storage tank 702 through a pipeline, the hot oil at the outlet of the hot oil heat storage tank 702 flows through the oil side of the high-temperature oil-water heat exchanger 8 and the oil side of the low-temperature oil-water heat exchanger 9 in sequence, and then enters the cold oil heat storage tank 701. The heated oil at the outlet of the cold oil heat storage tank 701 is connected to the oil inlet of the trough heat collecting device 7 through the oil transfer pump 703;

[0032] The other part is the cogeneration part, which mainly consists of four parts, namely the high-pressure cylinder 2, the intermediate-pressure cylinder 3, the low-pressure cylinder 4, the turbine circulation part, the condenser 12, the No. 3 high-pressure heater 13, the No. 5 low-pressure heater 14 and the boiler 1. The intermediate-pressure cylinder 3 extraction pipe is connected to the steam side of the No. 3 high-pressure heater 13, and the intermediate-pressure cylinder 3 exhaust main pipe is connected to the steam side inlet of the low-temperature oil-water heat exchanger 9 through the low-temperature oil-water heat exchanger steam inlet pipe 901. The operation process is: Boiler 1 consumes fossil energy to transport steam to the turbine high-pressure cylinder 2 to perform work. The exhaust steam from the high-pressure cylinder 2 enters the reheater of the boiler 1 for heating, and the steam from the reheater outlet enters the intermediate-pressure cylinder 3 of the steam turbine to perform work. The exhaust steam from the intermediate-pressure cylinder 3 of the steam turbine continues to enter the low-pressure cylinder 4 of the steam turbine to perform work. The exhaust steam from the low-pressure cylinder enters the condenser 12 to condense into condensate. The condensate is pressurized by the condensate pump 15 and flows through the shaft seal heater and the low-pressure heater in turn and then enters the deaerator 6. The feed water from the deaerator 6 is pressurized by the feed water pump 17 and flows through the high-pressure heater in turn and then enters the boiler. After the above process is completed, the steam returns to the boiler for the next cycle.

[0033] Under variable heating load conditions, the solution of completely replacing the third-stage HV heater with solar high-temperature steam offers significant advantages in reducing the construction area of the solar collector field and lowering investment costs. It also offers significant advantages in thermal efficiency and exergy efficiency compared to the original unit. The design of a condenser outlet pumping integrated system, which replaces the third-stage HV heater with solar high-temperature steam, achieves the highest thermal power generation rate at heating loads above 96.89MW, has a wide range of applicability, and offers high unit efficiency, making it the most suitable for widespread application. Under high heating loads (i.e., above 230.31MW), the solution of replacing the third-stage HV heater with solar high-temperature steam with the deaerator outlet pumping integrated system maintains the highest thermal power generation rate. It also requires the least amount of collector field area compared to the other two integrated systems, making it suitable for retrofitting CHP units in cold and high-altitude areas with low investment.

[0034] Based on the above, the thermal peak-shaving system of the new cogeneration power plant that complements light and coal can flexibly change the operating mode by setting a dynamic throttling valve to improve the peak-shaving capacity of the unit.

[0035] Mode 1: The extraction valve of the No. 3 high-pressure heater 13 is closed, and the high-temperature oil-water heat exchanger 8 of the trough-type heat collection device 7 is used to replace the heat recovery extraction of the No. 3 high-pressure heater 13. The steam extracted by the No. 5 low-pressure heater 14 is heated by the low-temperature oil-water heat exchanger to provide heating for users, while meeting the operating mode of light-coal mixed heating and power generation.

[0036] Mode 2: Based on Mode 1, the dynamic throttle valve 11 of the high-temperature oil-water heat exchanger inlet pipe 801 is closed, so that the trough type heat collection device 7 only serves as the supplementary heat supply steam extraction heat source to meet the heating needs of heat users.

[0037] Based on meeting the rated heating demand of heat users and under variable main steam flow conditions, operating modes 1 and 2 achieve optimal thermal economic performance when the main steam flow ranges are approximately 825 t / h and 770.00 t / h, respectively. Mode 1 achieves optimal peak-shaving performance when the main steam flow ranges are 811.75 t / h, with a daily peak-shaving capacity of approximately 28.44 MW. Mode 2 achieves optimal peak-shaving performance when the main steam flow ranges are 806.57 t / h, with a daily peak-shaving capacity of approximately 36.47 MW. Different operating modes can be adopted based on the actual peak-shaving demand of the power grid, achieving a flexible operating mode that integrates heating, power generation, and peak-shaving.

[0038] The present invention and its embodiments are described above. This description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if a person skilled in the art is inspired by this and, without departing from the purpose of the present invention, designs structures and embodiments similar to this technical solution without inventiveness, they shall fall within the scope of protection of the present invention.

Claims

1. A new type of thermal peak-shaving system for a solar-coal-combined heating power plant, comprising a boiler (1), a high-pressure cylinder (2), a medium-pressure cylinder (3), a low-pressure cylinder (4), a condenser (12), a trough-type heat collection device (7), and a heating network heater (10), characterized in that: The oil pipeline between the oil outlet and the oil inlet of the trough-type heat collecting device (7) is provided with a hot oil heat storage tank (702), a high-temperature oil-water heat exchanger (8), a low-temperature oil-water heat exchanger (9), a cold oil heat storage tank (701) and an oil transfer pump (703) in sequence along the flow direction of the internal heating oil; The condensate jelly pipe at the bottom of the condenser (12) is provided with a condensate pump (15), the condensate jelly pipe at the outlet of the condensate pump (15) is connected to the water side inlet of the high-temperature oil-water heat exchanger (8) through the high-temperature oil-water heat exchanger water inlet pipe (801), and the water side outlet of the high-temperature oil-water heat exchanger (8) is connected to the steam inlet pipe of the No. 3 high-pressure heater (13) through the high-temperature oil-water heat exchanger steam outlet pipe (802); The exhaust main pipe body of the medium-pressure cylinder (3) is connected to the low-temperature oil-water heat exchanger steam inlet pipe (901), the steam outlet of the low-temperature oil-water heat exchanger steam inlet pipe (901) is connected to the steam side inlet of the low-temperature oil-water heat exchanger (9), the steam side outlet of the low-temperature oil-water heat exchanger (9) is connected to the steam side inlet of the heat network heater (10) through the low-temperature oil-water heat exchanger steam outlet pipe (902), and the steam side outlet of the heat network heater (10) is connected to the condensate outlet pipe of the No. 5 low-pressure heater (14) through the drain pipe (20); The water side of the heating network heater (10) is connected to the user (16) through a pipeline.

2. The thermal peak-shaving system of a new type of cogeneration power plant with complementary solar and coal power according to claim 1, characterized in that: The heating oil inside the trough heat collecting device (7) is heated by a solar device (19).

3. The thermal peak-shaving system of a new type of thermal power plant with complementary solar and coal power according to claim 1 is characterized by: The water inlet pipe (801) of the high-temperature oil-water heat exchanger is provided with a booster pump (18) and a dynamic throttle valve (11) in sequence along the flow direction of the internal fluid.

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