Device for optimizing electric heating load of low-pressure cylinder zero-output thermal power generating unit

Abstract

The utility model relates to a device for optimizing electric heating load of a low-pressure cylinder zero-output thermal power generating unit. According to the technical scheme, one sides of high-pressure cylinders of four sets of steam turbines are connected to a first unit heat supply network heater, a second unit heat supply network heater, a third unit heat supply network heater and a fourth unit heat supply network heater respectively; the outer network water return pipe is respectively connected with inlet ends of the first unit heat supply network heater, the second unit heat supply network heater, the third unit heat supply network heater and the fourth unit heat supply network heater; the outer net water supply pipe is connected to the outlet ends of the first unit heat supply network heater, the second unit heat supply network heater, the third unit heat supply network heater and the fourth unit heat supply network heater. The utility model has the beneficial effects that the steam admission quantity of the heaters of the heating network of the four units is increased by controlling and reducing the steam admission quantity entering the low-pressure cylinder of the steam turbine, so that the fuel consumption is reduced under the condition that the total power supply quantity and the heat supply quantity are not changed, the optimized distribution of electric heating load is achieved, and the maximum economic benefit is realized.

Description

Technical Field

[0001] This utility model relates to the field of electrothermal load optimization technology, and in particular to a device for optimizing the electrothermal load of a low-pressure cylinder zero-output thermal power unit. Background Technology

[0002] In oilfield production, self-contained power plants play a crucial role in ensuring power supply. These plants typically operate with multiple generator units to meet varying electricity, heating, and steam supply requirements. Each unit can adjust its load according to actual needs to satisfy the plant's total power generation and heating flow requirements. Therefore, optimizing the power generation and heating / steam supply of each unit to achieve maximum economic benefits is critical for the operation and management of thermal power plants. However, factors such as the output range, ramp-up rate, and performance differences of thermal power plant units make optimizing electricity and heat loads even more challenging.

[0003] Chinese patent document publication number CN115264565A, entitled "A Deep Recovery and Optimized Heating System for Waste Heat from Low-Pressure Cylinder Zero-Output Units," describes a system that divides the intermediate-pressure cylinder exhaust pipe into three branches, which respectively enter an absorption heat pump, an exhaust heat exchanger, and a peak heater. The return water from the heating network first enters the absorption heat pump for heating before entering the exhaust heat exchanger. When the hot water flowing from the exhaust heat exchanger meets the water temperature requirements, it can directly enter the heating network. When the hot water temperature does not meet the requirements, it is heated by the peak heater before entering the heating network. This invention addresses the rapidly developing low-pressure cylinder zero-output heating method by developing a system that enables efficient and flexible recovery of low-grade waste heat. Through optimization and improvement of the thermal process of the low-pressure cylinder zero-output heating unit, it achieves deep recovery and cascaded energy supply of low-pressure exhaust waste heat, significantly improving the overall heating economy of the unit and simultaneously enhancing its heating capacity.

[0004] Chinese patent document publication number CN116244548A, patent titled "A Method for Optimizing the Zero-Output Operation of a Low-Pressure Cylinder in a Condensing Unit," describes an invention comprising: constructing an electrothermal operating domain and a zero-output operating curve diagram of the condensing unit under condensing conditions; determining the energy consumption of the condensing unit under condensing conditions and the energy consumption of the low-pressure cylinder under zero-output conditions; identifying a "conjugate zone" where the two conditions can supply the same heat load; and comparing the operation of the condensing condition and the low-pressure cylinder under zero-output conditions within the "conjugate zone." The system calculates the benefit difference and peak-shaving compensation benefit between the extraction condensing operation and the low-pressure cylinder zero-output operation, and constructs a comparison chart of peak-shaving compensation and benefit difference for the extraction condensing unit under the low-pressure cylinder zero-output operation. Finally, it constructs a judgment rule for whether the extraction condensing unit changes from the extraction condensing operation to the low-pressure cylinder zero-output operation, and determines whether the extraction condensing unit has changed to the low-pressure cylinder zero-output operation. This has the advantages of simplifying the calculation process and intuitively judging the adjustment rules of the extraction condensing unit's low-pressure cylinder zero-output optimized operation method.

[0005] The Chinese patent document publication number is CN114091718A, and the patent title is "A Research Method for Optimizing the Operation of Combined Cycle Heating and Power Units." The steps of this invention are as follows: Based on local energy prices and actual policies such as power generation utilization hours, and combined with the thermodynamic characteristics of gas turbine combined cycle power units, the invention studies the relationship between energy price changes, unit thermoelectric load changes, and the production economic indicators of each unit through quantitative calculation and analysis; it studies the optimal annual production total plan under energy price changes, and the optimal allocation of the total plan between the two units; through the design of an overall optimization research method, this invention reduces the impact of multiple constraints on combined cycle power units from the power grid, heating network, and gas network, and also reduces the multiple influences of factors such as the energy price system, unit thermodynamic characteristics, and heat-to-power ratio, and achieves optimized resource allocation, thereby optimizing the unit's production and operation efficiency, improving its survivability, increasing power generation, and improving the overall production and operation economic benefits.

[0006] There are some problems in the optimization of existing thermal power plant units. The main difficulties include the following aspects: there may be performance differences between different units, such as power generation efficiency, thermal efficiency, and fuel consumption. This makes it necessary to consider the mutual influence between different units in the optimization process in order to maximize the overall benefits. The two modes of operation (on / off) of the low-pressure cylinder of the steam turbine make these problems more complicated. Utility Model Content

[0007] The purpose of this invention is to address the aforementioned deficiencies in the existing technology by providing a device for optimizing the electrical and thermal load of low-pressure cylinder zero-output thermal power units. By adjusting the steam intake into the turbine, the steam intake of the four unit heating network heaters is adjusted, thereby reducing fuel consumption and achieving optimized distribution of electrical and thermal loads while keeping the total power and heat supply constant.

[0008] The present invention relates to a device for optimizing the electrical and thermal load of a low-pressure cylinder zero-output thermal power unit. The technical solution includes: a first turbine (a), a second turbine (b), a third turbine (c), a fourth turbine (d), a first unit heat network heater (e), a second unit heat network heater (f), a third unit heat network heater (g), a fourth unit heat network heater (h), an external network return water pipe (k1), and an external network supply water pipe (k2). The high-pressure cylinder side of the first turbine (a) is connected to the first unit heat network heater (e) via a pipeline and a first heating valve (9). The high-pressure cylinder side of the second turbine (b) is connected to the second unit heat network heater (e) via a pipeline and a second heating valve (10). f), the high-pressure cylinder side of the third turbine (c) is connected to the third unit heat network heater (g) through a pipeline and the third heating valve (11), and the high-pressure cylinder side of the fourth turbine (d) is connected to the fourth unit heat network heater (h) through a pipeline and the fourth heating valve (12); the external network return water pipe (k1) is connected to the inlet end of the first unit heat network heater (e), the second unit heat network heater (f), the third unit heat network heater (g) and the fourth unit heat network heater (h) respectively, and the external network supply water pipe (k2) is connected to the outlet end of the first unit heat network heater (e), the second unit heat network heater (f), the third unit heat network heater (g) and the fourth unit heat network heater (h) respectively.

[0009] Preferably, the aforementioned external network return water pipe (k1) is connected to the inlet ends of the first unit's heating network heater (e), the second unit's heating network heater (f), the third unit's heating network heater (g), and the fourth unit's heating network heater (h) via a first return water regulating valve (i) and a second return water regulating valve (j) connected in parallel.

[0010] Preferably, the inlet end of the first heating valve (9) is connected to the medium and low pressure cylinder of the first steam turbine (a) via a parallel pipeline and the first heating disc valve (5).

[0011] Preferably, the inlet end of the second heating valve (10) is connected to the medium and low pressure cylinder of the second steam turbine (b) via a parallel pipeline and a second heating disc valve (6).

[0012] Preferably, the inlet end of the aforementioned third heating valve (11) is connected to the medium and low pressure cylinder of the third steam turbine (c) via a parallel pipeline and the third heating disc valve (7).

[0013] Preferably, the inlet end of the fourth heating valve (12) is connected to the medium and low pressure cylinder of the fourth steam turbine (d) via a parallel pipeline and the fourth heating disc valve (8).

[0014] Preferably, the outlet end of the first return water regulating valve (i) is connected to the inlet end of the first unit heat network heater (e) through a pipeline and the first return water valve (13), and is connected to the inlet end of the second unit heat network heater (f) through a second pipeline and the second return water valve (14).

[0015] Preferably, a first outlet valve (17) is installed on the pipeline at the outlet end of the first unit's heat network heater (e), and a second outlet valve (18) is installed on the pipeline at the outlet end of the second unit's heat network heater (f). The outer ends of the two sets of pipelines converge into the external network water supply pipe (k2).

[0016] Preferably, the outlet end of the second return water regulating valve (j) is connected to the inlet end of the third unit heat network heater (g) through a pipeline and the third return water valve (15), and is connected to the inlet end of the fourth unit heat network heater (h) through a second pipeline and the fourth return water valve (16).

[0017] Preferably, a third outlet valve (19) is installed on the pipeline at the outlet end of the third unit's heating network heater (g), and a fourth outlet valve (20) is installed on the pipeline at the outlet end of the fourth unit's heating network heater (h). The outer ends of the two sets of pipelines converge into the external network water supply pipe (k2).

[0018] The beneficial effects of this utility model are as follows: This utility model adjusts the steam intake of the four steam turbines through the first, second, third, and fourth control valves, and increases the steam intake of the four unit heating network heaters by reducing the steam intake into the low-pressure cylinder of the steam turbines through the first, second, third, and fourth heating disc valves. This achieves a reduction in the overall plant fuel consumption and optimizes the distribution of electrical and thermal loads while keeping the total power and heat supply constant. In short, this utility model achieves efficient distribution of electrical and thermal loads and optimizes the power generation, heat supply, and steam supply of each unit to achieve maximum economic benefits. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of Embodiment 1 of the present invention;

[0020] Figure 2 This is a schematic diagram of the structure of the first heating disc valve;

[0021] Figure 3 This is a schematic diagram of Embodiment 3 of this utility model;

[0022] Figure 4 This is a schematic diagram of Embodiment 4 of this utility model;

[0023] Figure 5 This is a schematic diagram of Embodiment 5 of the present invention;

[0024] In the diagram above: First turbine a, Second turbine b, Third turbine c, Fourth turbine d, First unit heat network heater e, Second unit heat network heater f, Third unit heat network heater g, Fourth unit heat network heater h, First return water regulating valve i, Second return water regulating valve j, External network return water pipe k1, External network supply water pipe k2, Newly added heat network heater m, Fifth heating disc valve d1, Sixth heating disc valve d2, Cooling steam valve c1.

[0025] First control valve 1, second control valve 2, third control valve 3, fourth control valve 4, first heating disc valve 5, second heating disc valve 6, third heating disc valve 7, fourth heating disc valve 8, first heating valve 9, second heating valve 10, third heating valve 11, fourth heating valve 12, first return water valve 13, second return water valve 14, third return water valve 15, fourth return water valve 16, first outlet valve 17, second outlet valve 18, third outlet valve 19, fourth outlet valve 20, valve body 5.1, valve core 5.2, valve core shaft 5.3, actuator 5.4, steam passage hole 5.5. Detailed Implementation

[0026] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0027] Example 1, referring to Figure 1 This utility model discloses a device for optimizing the electrical and thermal load of a low-pressure cylinder zero-output thermal power unit, comprising a first turbine a, a second turbine b, a third turbine c, a fourth turbine d, a first unit heat network heater e, a second unit heat network heater f, a third unit heat network heater g, a fourth unit heat network heater h, an external network return water pipe k1, and an external network supply water pipe k2. A first control valve 1, a second control valve 2, a third control valve 3, and a fourth control valve 4 are respectively installed at the air inlet end of the high-pressure cylinder of the first turbine a, second turbine b, third turbine c, and fourth turbine d. One side of the high-pressure cylinder of the first turbine a is connected to the first unit heat network heater e via a pipeline and a first heating valve 9. The second turbine... One side of the high-pressure cylinder of turbine b is connected to the second unit's heating network heater f via a pipeline and the second heating valve 10. One side of the high-pressure cylinder of turbine c is connected to the third unit's heating network heater g via a pipeline and the third heating valve 11. One side of the high-pressure cylinder of turbine d is connected to the fourth unit's heating network heater h via a pipeline and the fourth heating valve 12. The external network return water pipe k1 is connected to the inlet ends of the first unit's heating network heater e, the second unit's heating network heater f, the third unit's heating network heater g, and the fourth unit's heating network heater h, respectively. The external network supply water pipe k2 is connected to the outlet ends of the first unit's heating network heater e, the second unit's heating network heater f, the third unit's heating network heater g, and the fourth unit's heating network heater h, respectively.

[0028] Preferably, the aforementioned external network return water pipe k1 is connected to the inlet ends of the first unit's heating network heater e, the second unit's heating network heater f, the third unit's heating network heater g, and the fourth unit's heating network heater h via a first return water regulating valve i and a second return water regulating valve j connected in parallel.

[0029] Preferably, the inlet end of the first heating valve 9 is connected to the medium and low pressure cylinder of the first steam turbine a via a parallel pipeline and the first heating disc valve 5.

[0030] Preferably, the inlet end of the second heating valve 10 is connected to the low-pressure cylinder of the second steam turbine b via a parallel pipeline and the second heating disc valve 6.

[0031] Preferably, the inlet end of the third heating valve 11 is connected to the medium and low pressure cylinder of the third steam turbine c via a parallel pipeline and the third heating disc valve 7.

[0032] Preferably, the inlet end of the fourth heating valve 12 is connected to the low-pressure cylinder of the fourth steam turbine d via a parallel pipeline and the fourth heating disc valve 8.

[0033] Preferably, the outlet end of the first return water regulating valve i is connected to the inlet end of the first unit's heating network heater e via a pipeline and the first return water valve 13, and is connected to the inlet end of the second unit's heating network heater f via a second pipeline and the second return water valve 14.

[0034] Preferably, a first outlet valve 17 is installed on the pipeline at the outlet end of the first unit's heating network heater e, and a second outlet valve 18 is installed on the pipeline at the outlet end of the second unit's heating network heater f. The outer ends of the two sets of pipelines converge into the external network water supply pipe k2.

[0035] Preferably, the outlet end of the second return water regulating valve j is connected to the inlet end of the third unit's heating network heater g via a pipeline and the third return water valve 15, and is connected to the inlet end of the fourth unit's heating network heater h via a second pipeline and the fourth return water valve 16.

[0036] Preferably, a third outlet valve 19 is installed on the pipeline at the outlet end of the heating network heater g of the third unit, and a fourth outlet valve 20 is installed on the pipeline at the outlet end of the heating network heater h of the fourth unit. The outer ends of the two sets of pipelines converge into the external network water supply pipe k2.

[0037] When using this utility model, refer to Figure 1 , Figure 2The first turbine a generates 25% of the total electricity and supplies 20% of the total heat; the second turbine b generates 20% of the total electricity and supplies 20% of the total heat; the third turbine c generates 30% of the total electricity and supplies 30% of the total heat; and the fourth turbine d generates 25% of the total electricity and supplies 30% of the total heat. By controlling and adjusting the first control valve 1 to close less and the first heating disc valve 5 to open more, the electricity and heat supply of the first turbine a are reduced; by closing the second control valve 2 to close more and the second heating disc valve 6 to open more, the electricity and heat supply of the second turbine b are reduced; by opening the third control valve 3 to open more and adjusting the third heating disc valve 7, the electricity and heat supply of the third turbine c are increased; and by opening the fourth control valve 4 to open more and adjusting the fourth heating disc valve 8, the electricity supply of the fourth turbine d is increased, while keeping the total heat supply constant. This achieves a better optimization of the electrical and thermal load.

[0038] Example 2: The device for optimizing the electrical and thermal load of a low-pressure cylinder zero-output thermal power unit mentioned in this utility model includes a first turbine a, a second turbine b, a third turbine c, a fourth turbine d, a first unit heat network heater e, a second unit heat network heater f, a third unit heat network heater g, a fourth unit heat network heater h, an external network return water pipe k1, and an external network supply water pipe k2. A first control valve 1, a second control valve 2, a third control valve 3, and a fourth control valve 4 are respectively installed at the high-pressure cylinder inlet ends of the first turbine a, second turbine b, third turbine c, and fourth turbine d. One side of the high-pressure cylinder of the first turbine a is connected to the first unit heat network heater e via a pipeline and a first heating valve 9. One side of the high-pressure cylinder of turbine b is connected to the second unit's heating network heater f via a pipeline and the second heating valve 10. One side of the high-pressure cylinder of the third turbine c is connected to the third unit's heating network heater g via a pipeline and the third heating valve 11. One side of the high-pressure cylinder of the fourth turbine d is connected to the fourth unit's heating network heater h via a pipeline and the fourth heating valve 12. The external network return water pipe k1 is connected to the inlet ends of the first unit's heating network heater e, the second unit's heating network heater f, the third unit's heating network heater g, and the fourth unit's heating network heater h, respectively. The external network supply water pipe k2 is connected to the outlet ends of the first unit's heating network heater e, the second unit's heating network heater f, the third unit's heating network heater g, and the fourth unit's heating network heater h, respectively.

[0039] The difference from Example 1 is:

[0040] Reference Figure 2The first heating butterfly valve 5, the second heating butterfly valve 6, the third heating butterfly valve 7, and the fourth heating butterfly valve 8 are heating butterfly valves with steam flow holes. Specifically, they include a valve body 5.1, a valve core 5.2, a valve core shaft 5.3, and an actuator 5.4. The valve core 5.2 is installed inside the valve body 5.1, and the valve core 5.2 rotates along the valve core shaft 5.3. There is one or more steam flow holes 5.5 distributed on the valve core 5.2. After receiving the command to increase the heating capacity, the valve core 5.2 closes slightly. Even when it is fully closed, it will still maintain a certain flow of steam to ensure the cooling of the low-pressure cylinder and avoid the generation of air friction. The cooling steam flow rate is not adjustable. Under high load, the flow rate is large and cannot achieve the maximum heating economy.

[0041] Example 3: The device for optimizing the electrical and thermal load of a low-pressure cylinder zero-output thermal power unit mentioned in this utility model includes a first turbine a, a second turbine b, a third turbine c, a fourth turbine d, a first unit heat network heater e, a second unit heat network heater f, a third unit heat network heater g, a fourth unit heat network heater h, an external network return water pipe k1, and an external network supply water pipe k2. A first control valve 1, a second control valve 2, a third control valve 3, and a fourth control valve 4 are respectively installed at the high-pressure cylinder inlet ends of the first turbine a, second turbine b, third turbine c, and fourth turbine d. One side of the high-pressure cylinder of the first turbine a is connected to the first unit heat network heater e via a pipeline and a first heating valve 9. One side of the high-pressure cylinder of turbine b is connected to the second unit's heating network heater f via a pipeline and the second heating valve 10. One side of the high-pressure cylinder of the third turbine c is connected to the third unit's heating network heater g via a pipeline and the third heating valve 11. One side of the high-pressure cylinder of the fourth turbine d is connected to the fourth unit's heating network heater h via a pipeline and the fourth heating valve 12. The external network return water pipe k1 is connected to the inlet ends of the first unit's heating network heater e, the second unit's heating network heater f, the third unit's heating network heater g, and the fourth unit's heating network heater h, respectively. The external network supply water pipe k2 is connected to the outlet ends of the first unit's heating network heater e, the second unit's heating network heater f, the third unit's heating network heater g, and the fourth unit's heating network heater h, respectively.

[0042] The difference from Example 2 is:

[0043] Figure 3 As shown, the heat source of the newly added heating network heater m is taken from the third turbine c and the fourth turbine d. According to the unit load, the heat source can be switched by adding the fifth heating disc valve d1 and the sixth heating disc valve d2, which can maximize the heating of one of the units, the third turbine c and the fourth turbine d.

[0044] Example 4: The device for optimizing the electrical and thermal load of a low-pressure cylinder zero-output thermal power unit mentioned in this utility model includes a first turbine a, a second turbine b, a third turbine c, a fourth turbine d, a first unit heat network heater e, a second unit heat network heater f, a third unit heat network heater g, a fourth unit heat network heater h, an external network return water pipe k1, and an external network supply water pipe k2. A first control valve 1, a second control valve 2, a third control valve 3, and a fourth control valve 4 are respectively installed at the high-pressure cylinder inlet ends of the first turbine a, second turbine b, third turbine c, and fourth turbine d. One side of the high-pressure cylinder of the first turbine a is connected to the first unit heat network heater e via a pipeline and a first heating valve 9. One side of the high-pressure cylinder of turbine b is connected to the second unit's heating network heater f via a pipeline and the second heating valve 10. One side of the high-pressure cylinder of the third turbine c is connected to the third unit's heating network heater g via a pipeline and the third heating valve 11. One side of the high-pressure cylinder of the fourth turbine d is connected to the fourth unit's heating network heater h via a pipeline and the fourth heating valve 12. The external network return water pipe k1 is connected to the inlet ends of the first unit's heating network heater e, the second unit's heating network heater f, the third unit's heating network heater g, and the fourth unit's heating network heater h, respectively. The external network supply water pipe k2 is connected to the outlet ends of the first unit's heating network heater e, the second unit's heating network heater f, the third unit's heating network heater g, and the fourth unit's heating network heater h, respectively.

[0045] The difference from Example 2 is:

[0046] Reference Figure 4 The diagram shows the heating system of a device for optimizing the electrical and thermal load of a thermal power unit with zero output in the low-pressure cylinder. A cooling steam valve c1 has been added. With the third heating disc valve 7 fully closed, the cooling steam valve c1 controls and maintains the minimum amount of cooling steam in the low-pressure cylinder, ensuring that the low-pressure cylinder does not generate blow-through friction and maximizing the heating economy.

[0047] Example 5: A device for optimizing the electrical and thermal load of a low-pressure cylinder zero-output thermal power unit mentioned in this utility model includes a first turbine a, a second turbine b, a third turbine c, a fourth turbine d, a first unit heat network heater e, a second unit heat network heater f, a third unit heat network heater g, a fourth unit heat network heater h, an external network return water pipe k1, and an external network supply water pipe k2. A first control valve 1, a second control valve 2, a third control valve 3, and a fourth control valve 4 are respectively installed at the high-pressure cylinder inlet ends of the first turbine a, second turbine b, third turbine c, and fourth turbine d. One side of the high-pressure cylinder of the first turbine a is connected to the first unit heat network heater e via a pipeline and a first heating valve 9. One side of the high-pressure cylinder of turbine b is connected to the second unit's heating network heater f via a pipeline and the second heating valve 10. One side of the high-pressure cylinder of the third turbine c is connected to the third unit's heating network heater g via a pipeline and the third heating valve 11. One side of the high-pressure cylinder of the fourth turbine d is connected to the fourth unit's heating network heater h via a pipeline and the fourth heating valve 12. The external network return water pipe k1 is connected to the inlet ends of the first unit's heating network heater e, the second unit's heating network heater f, the third unit's heating network heater g, and the fourth unit's heating network heater h, respectively. The external network supply water pipe k2 is connected to the outlet ends of the first unit's heating network heater e, the second unit's heating network heater f, the third unit's heating network heater g, and the fourth unit's heating network heater h, respectively.

[0048] The difference from Example 4 is:

[0049] Reference Figure 5 In addition to the cooling steam valve C1, the third heating disc valve 7 adopts a heating disc valve without steam flow holes, allowing the low-pressure cylinder to enter a zero-output mode. With the third heating disc valve 7 fully closed, the minimum cooling steam output to the low-pressure cylinder is maintained by adjusting the cooling steam valve C1. At the same time, the addition of a heating network heater increases the heating capacity and maximizes heating economy.

[0050] The above description is merely a preferred embodiment of this utility model. Any person skilled in the art may modify this utility model or modify it into an equivalent technical solution using the technical solutions described above. Therefore, any simple modifications or equivalent transformations made based on the technical solutions of this utility model are within the scope of protection claimed by this utility model.

Claims

1. A device for optimizing the electrothermal load of a low-pressure cylinder zero-output thermal power unit, characterized in that: The turbine includes a first turbine (a), a second turbine (b), a third turbine (c), a fourth turbine (d), a first unit heat network heater (e), a second unit heat network heater (f), a third unit heat network heater (g), a fourth unit heat network heater (h), an external network return water pipe (k1), and an external network supply water pipe (k2). The high-pressure cylinder side of the first turbine (a) is connected to the first unit heat network heater (e) via a pipeline and a first heating valve (9). The high-pressure cylinder side of the second turbine (b) is connected to the second unit heat network heater (f) via a pipeline and a second heating valve (10). The high-pressure cylinder side of the third turbine (c) is connected to the first unit heat network heater (e) via a pipeline and a second heating valve (10). The pipeline and the third heating valve (11) are connected to the third unit's heating network heater (g), and the high-pressure cylinder side of the fourth turbine (d) is connected to the fourth unit's heating network heater (h) through the pipeline and the fourth heating valve (12); the external network return water pipe (k1) is connected to the inlet end of the first unit's heating network heater (e), the second unit's heating network heater (f), the third unit's heating network heater (g) and the fourth unit's heating network heater (h) respectively, and the external network supply water pipe (k2) is connected to the outlet end of the first unit's heating network heater (e), the second unit's heating network heater (f), the third unit's heating network heater (g) and the fourth unit's heating network heater (h) respectively.

2. The device for optimizing the electrothermal load of a low-pressure cylinder zero-output thermal power unit according to claim 1, characterized in that: The external network return water pipe (k1) is connected to the inlet ends of the first unit heat network heater (e), the second unit heat network heater (f), the third unit heat network heater (g), and the fourth unit heat network heater (h) through the first return water regulating valve (i) and the second return water regulating valve (j) connected in parallel.

3. The device for optimizing the electrothermal load of a low-pressure cylinder zero-output thermal power unit according to claim 1, characterized in that: The inlet end of the first heating valve (9) is connected to the medium and low pressure cylinder of the first steam turbine (a) through a parallel pipeline and the first heating disc valve (5).

4. The device for optimizing the electrothermal load of a low-pressure cylinder zero-output thermal power unit according to claim 3, characterized in that: The inlet end of the second heating valve (10) is connected to the medium and low pressure cylinder of the second steam turbine (b) via a parallel pipeline and the second heating disc valve (6).

5. The device for optimizing the electrothermal load of a low-pressure cylinder zero-output thermal power unit according to claim 4, characterized in that: The inlet end of the third heating valve (11) is connected to the medium and low pressure cylinder of the third steam turbine (c) via a parallel pipeline and the third heating disc valve (7).

6. The device for optimizing the electrothermal load of a low-pressure cylinder zero-output thermal power unit according to claim 5, characterized in that: The inlet end of the fourth heating valve (12) is connected to the low-pressure cylinder of the fourth steam turbine (d) via a parallel pipeline and the fourth heating disc valve (8).

7. The device for optimizing the electrothermal load of a low-pressure cylinder zero-output thermal power unit according to claim 2, characterized in that: The outlet end of the first return water regulating valve (i) is connected to the inlet end of the first unit heat network heater (e) through a pipeline and the first return water valve (13), and is connected to the inlet end of the second unit heat network heater (f) through a second pipeline and the second return water valve (14).

8. The device for optimizing the electrothermal load of a low-pressure cylinder zero-output thermal power unit according to claim 7, characterized in that: The first unit's heat network heater (e) has a first outlet valve (17) installed on the pipeline at the outlet end, and the second unit's heat network heater (f) has a second outlet valve (18) installed on the pipeline at the outlet end. The outer ends of the two sets of pipelines converge into the external network water supply pipe (k2).

9. The device for optimizing the electrothermal load of a low-pressure cylinder zero-output thermal power unit according to claim 2, characterized in that: The outlet end of the second return water regulating valve (j) is connected to the inlet end of the third unit heat network heater (g) through a pipeline and the third return water valve (15), and is connected to the inlet end of the fourth unit heat network heater (h) through a second pipeline and the fourth return water valve (16).

10. The device for optimizing the electrothermal load of a low-pressure cylinder zero-output thermal power unit according to claim 9, characterized in that: The pipeline at the outlet end of the third unit's heating network heater (g) is equipped with a third outlet valve (19), and the pipeline at the outlet end of the fourth unit's heating network heater (h) is equipped with a fourth outlet valve (20). The outer ends of the two sets of pipelines converge into the external network water supply pipe (k2).

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