Thermodynamic system of coal power unit

Abstract

The utility model relates to a thermodynamic system of a coal power unit. The thermodynamic system comprises a boiler, a pressure adjusting device and a steam turbine pressure cylinder. The pressure adjusting device is used for increasing steam pressure; a first air outlet of the boiler is communicated with the steam turbine pressure cylinder through the pressure adjusting device, and a second air outlet of the boiler is communicated with the steam turbine pressure cylinder; main steam in the boiler flows into the pressure adjusting device through a first air outlet of the boiler, the main steam is pressurized in the pressure adjusting device to form pressurized steam, and the pressurized steam flows into the steam turbine pressure cylinder. And reheat steam in the boiler flows into the steam turbine pressure cylinder through a second air outlet of the boiler, the steam turbine pressure cylinder conducts thermoelectric conversion through the pressurized steam and the reheat steam, and the thermoelectric conversion efficiency of the steam turbine pressure cylinder in the coal power unit thermodynamic system can be improved.

Description

Technical Field

[0001] This application relates to the field of generator set technology, and in particular to a thermal system for a coal-fired power unit. Background Technology

[0002] Coal-fired power generation is a complex energy conversion process involving the interconversion of various energy forms. The steam turbine in the thermal system of a coal-fired power unit is a crucial link in this energy conversion, and its operating efficiency and performance directly affect the overall efficiency and performance of the unit. In the boiler, coal is fed into the combustion chamber for combustion, releasing a large amount of heat energy. Condensate in the boiler is heated and evaporated through heating surfaces, forming high-temperature, high-pressure steam. After entering the turbine's pressure cylinder, the steam expands on the blades at each stage, driving the blades to rotate and thus converting heat energy into mechanical energy. The mechanical energy output from the turbine's pressure cylinder is converted into electrical energy by a generator and transmitted to the outside world through power lines, thus realizing the thermoelectric conversion of the turbine's pressure cylinder.

[0003] Traditional power units are typically built with the goal of maximizing power generation. Therefore, the high-pressure cylinder of the steam turbine is usually designed based on the rated operating conditions. However, with the development of new energy sources and the construction of new power systems, coal-fired power is gradually transforming into a regulating and reliable power source. Large-capacity ultra-supercritical units generally operate at medium and low loads. When operating at medium and low loads, the pressure of the main steam is usually low, which can easily lead to a low thermoelectric conversion efficiency of the steam turbine pressure cylinder in the thermal system of coal-fired power units. Utility Model Content

[0004] Therefore, it is necessary to provide a thermal system for coal-fired power units that improves the thermoelectric conversion efficiency of the turbine pressure cylinder in the thermal system of the coal-fired power unit, in order to address the above problems.

[0005] A thermal system for a coal-fired power unit, the thermal system comprising:

[0006] Boiler, pressure regulating device and turbine pressure cylinder;

[0007] The pressure regulating device is used to increase the steam pressure; the first outlet of the boiler is connected to the turbine pressure cylinder through the pressure regulating device, and the second outlet of the boiler is connected to the turbine pressure cylinder.

[0008] The main steam in the boiler flows into the pressure regulating device through the first outlet of the boiler. The main steam is pressurized in the pressure regulating device to form pressurized steam. The pressurized steam flows into the turbine pressure cylinder. The reheat steam in the boiler flows into the turbine pressure cylinder through the second outlet of the boiler. The turbine pressure cylinder uses the pressurized steam and the reheat steam for thermoelectric conversion.

[0009] The aforementioned coal-fired power unit thermal system includes: a first valve, a second valve, and a third valve; the first valve is disposed between the first outlet of the boiler and the first inlet of the turbine pressure cylinder, and is used to control the opening and closing of the passage between the first outlet of the boiler and the first inlet of the turbine pressure cylinder; the second valve is disposed between the first exhaust port of the pressure regulating device and the first inlet of the turbine pressure cylinder, and is used to control the opening and closing of the passage between the first exhaust port of the pressure regulating device and the first inlet of the turbine pressure cylinder; the third valve is disposed between the first exhaust port of the pressure regulating device and the second inlet of the turbine pressure cylinder, and is used to control the opening and closing of the passage between the first exhaust port of the pressure regulating device and the second inlet of the turbine pressure cylinder.

[0010] In one embodiment, when the load demand of the coal-fired power unit's thermal system meets a preset low-load condition, the first and third valves are closed, and the second valve is open; all the main steam in the boiler flows into the pressure regulating device, where it is pressurized to form pressurized steam, which then flows into the turbine pressure cylinder through the second valve; when the load demand of the coal-fired power unit's thermal system does not meet the preset low-load condition, the first and third valves are open, and the second valve is closed; a portion of the main steam in the boiler flows into the pressure regulating device, where it is pressurized to form pressurized steam, which then flows into the turbine pressure cylinder through the third valve; another portion of the main steam in the boiler flows into the turbine pressure cylinder through the first valve, and the turbine pressure cylinder uses the main steam for thermoelectric conversion.

[0011] In one embodiment, the turbine pressure cylinder includes a high-pressure cylinder and multiple sets of medium and low-pressure cylinders connected in sequence. Each set of medium and low-pressure cylinders includes one medium-pressure cylinder and two low-pressure cylinders. The ratio between the multiple sets of medium and low-pressure cylinders corresponds to the historical load demand distribution of the environment in which the thermal system of the coal-fired power unit is located.

[0012] In one embodiment, the thermal system of the coal-fired power unit further includes: a plurality of fourth valves; the plurality of fourth valves are respectively disposed between the second gas outlet of the boiler and the intermediate pressure cylinder in the plurality of low-pressure cylinders, for adjusting the opening degree of the passage between the high pressure cylinder and the intermediate pressure cylinder.

[0013] In one embodiment, the number of fourth valves is the same as the number of groups of medium and low pressure cylinders, and each of the fourth valves is disposed between the medium pressure cylinder in each group of medium and low pressure cylinders and the second air outlet of the boiler.

[0014] In one embodiment, the thermal system of the coal-fired power unit further includes a fifth valve; the fifth valve is disposed between the first air outlet of the boiler and the air inlet of the pressure regulating device, and is used to control the opening degree of the passage between the first air outlet of the boiler and the air inlet of the pressure regulating device.

[0015] In one embodiment, the coal-fired power unit thermal system further includes a first generator, and the pressure regulating device is connected to the first generator. When the load demand corresponding to the coal-fired power unit thermal system does not meet the preset low load conditions, the first generator uses the heat loss between the pressure regulating device and the turbine pressure cylinder to perform thermoelectric conversion.

[0016] In one embodiment, the thermal system of the coal-fired power unit further includes a high-pressure heating device, which is connected to the second exhaust port of the pressure regulating device.

[0017] In one embodiment, the thermal system of the coal-fired power unit further includes a condenser connected to the third exhaust port of the pressure regulating device.

[0018] In the aforementioned coal-fired power unit thermal system, a pressure regulating device for boosting steam pressure is installed between the turbine pressure cylinder and the boiler. This device regulates the pressure of the main steam before it enters the turbine pressure cylinder. When the operating load of the coal-fired power unit thermal system is low, the main steam can be boosted through the pressure regulating device, thereby increasing the inlet steam pressure of the turbine pressure cylinder and improving the thermoelectric conversion efficiency of the turbine pressure cylinder in the coal-fired power unit thermal system. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the thermal system of a coal-fired power unit in one embodiment;

[0020] Figure 2 This is a schematic diagram of the structure of a coal-fired power unit thermal system that also includes a first valve, a second valve, and a third valve in another embodiment.

[0021] Figure 3 This is a schematic diagram of the structure when the low- and medium-pressure cylinders of the turbine pressure cylinder in the thermal system of a coal-fired power unit are set into two groups, as shown in another embodiment.

[0022] Figure 4 This is a schematic diagram of the structure when the thermal system of the coal-fired power unit also includes a fourth valve in another embodiment;

[0023] Figure 5 This is a schematic diagram of the structure when the thermal system of the coal-fired power unit further includes a fifth valve in another embodiment;

[0024] Figure 6 This is a schematic diagram of the thermal system of a coal-fired power unit in a detailed embodiment.

[0025] Explanation of icon numbers:

[0026] Boiler-11; Boiler's first exhaust port-111; Boiler's second exhaust port-112; Pressure regulating device-12; Pressure regulating device's first exhaust port-121; Pressure regulating device's second exhaust port-122; Pressure regulating device's third exhaust port-123; Steam turbine pressure cylinder-13; High-pressure cylinder's first inlet-131; High-pressure cylinder's second inlet-132; High-pressure cylinder-1301; First intermediate-pressure cylinder-1302; Second intermediate-pressure cylinder-1303; First low-pressure cylinder-1304; Second low-pressure cylinder-1305; Third low-pressure cylinder-1306; Fourth low-pressure cylinder-1307; First valve-14; Second valve-15; Third valve-16; Fourth valve-17; Fifth valve-18; High-pressure heating device-19; Condenser-20; Low-pressure heating device-21; First generator-22; Second generator-23. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0028] Steam turbine pressure cylinders can be divided into high-pressure cylinders, intermediate-pressure cylinders, and low-pressure cylinders according to different steam inlet parameters. The high-pressure cylinder is located at the front of the steam turbine and is the initial stage for the main steam to enter the turbine pressure cylinder. The exhaust steam from the high-pressure cylinder enters the boiler reheater for heating and then enters the intermediate-pressure cylinder to do work. The exhaust steam from the intermediate-pressure cylinder enters the low-pressure cylinder. The exhaust steam that has done work in the low-pressure cylinder enters the condenser (air-cooled island in air-cooled units) and condenses into water, which then enters the regenerative system and returns to the boiler.

[0029] Because traditional coal-fired power units are typically built with the goal of maximizing power generation, the turbine pressure cylinder is usually designed based on rated operating conditions. This means that the high-pressure cylinder in a traditional turbine can only maintain efficient energy conversion under rated conditions. However, with most units currently operating at medium to low loads, the main steam parameters and steam intake of the coal-fired power unit's thermal system differ, causing a mismatch between the steam intake of the turbine pressure cylinder and its design value. This results in lower thermoelectric conversion efficiency for the turbine pressure cylinder.

[0030] In order to improve the thermoelectric conversion efficiency of the turbine pressure cylinder, such as Figure 1As shown, this application provides a coal-fired power unit thermal system 10, which includes a boiler 11, a pressure regulating device 12, and a turbine pressure cylinder 13.

[0031] The pressure regulating device 12 is used to increase the steam pressure. The pressure regulating device 12 can be an actively regulating turbine or a front-mounted steam turbine; there is no limitation on this.

[0032] The first outlet 111 of the boiler 11 is connected to the turbine pressure cylinder 13 through the pressure regulating device 12, and the second outlet 112 of the boiler 11 is connected to the turbine pressure cylinder 13.

[0033] In this way, the exhaust steam in the boiler 11 can flow into the pressure regulating device 12 and the turbine pressure cylinder 13 through the first outlet 111; and the exhaust steam in the boiler 11 can flow into the turbine pressure cylinder 13 through the second outlet 112.

[0034] The main steam in boiler 11 flows into pressure regulating device 12 through the first outlet 111 of boiler 11. The main steam is pressurized in pressure regulating device 12 to form pressurized steam. The pressurized steam flows into turbine pressure cylinder 13. The reheat steam in boiler 11 flows into turbine pressure cylinder 13 through the second outlet 112 of boiler 11. Turbine pressure cylinder 13 uses pressurized steam and reheat steam for thermoelectric conversion.

[0035] In this way, the pressure of the main steam in the boiler 11 can be regulated by the pressure regulating device 12 before it enters the turbine pressure cylinder 13. When the operating load of the coal-fired power unit thermal system 10 is low, the main steam can be pressurized by the pressure regulating device 12, thereby increasing the steam inlet pressure of the turbine pressure cylinder 13 and improving the thermoelectric conversion efficiency of the turbine pressure cylinder 13 in the coal-fired power unit thermal system 10 to a certain extent.

[0036] It is understandable that the operating load of a coal-fired power unit's thermal system is matched with the heat and electricity demand of its suppliers (e.g., residential users, industrial users, etc.). However, this demand is not fixed; therefore, the thermal system may operate under low, medium, or high load conditions. When the load demand of the thermal system meets the preset low load conditions (i.e., the system is operating at low load), the steam intake of the turbine pressure cylinder may not match the design value, resulting in lower thermoelectric conversion efficiency. Conversely, when the load demand does not meet the preset low load conditions (i.e., the system is operating at high or medium load), the thermal system may be unable to meet the actual load demand, leading to a failure to supply sufficient heat and electricity.

[0037] In one embodiment, reference Figure 2 The thermal system 10 of the coal-fired power unit also includes: a first valve 14, a second valve 15 and a third valve 16.

[0038] The first valve 14 is located between the first outlet 111 of the boiler 11 and the first inlet 131 of the turbine pressure cylinder 13, and is used to control the opening and closing of the passage between the first outlet 111 of the boiler 11 and the first inlet 131 of the turbine pressure cylinder 13; the second valve 15 is located between the first exhaust port 121 of the pressure regulating device 12 and the first inlet 131 of the turbine pressure cylinder 13, and is used to control the opening and closing of the passage between the first exhaust port 121 of the pressure regulating device 12 and the first inlet 131 of the turbine pressure cylinder 13; the third valve 16 is located between the first exhaust port 121 of the pressure regulating device 12 and the second inlet 132 of the turbine pressure cylinder 13, and is used to control the opening and closing of the passage between the first exhaust port 121 of the pressure regulating device 12 and the second inlet 132 of the turbine pressure cylinder 13.

[0039] Among them, the first valve 14, the second valve 15 and the third valve 16 can be shut-off valves, specifically having only two states: open and closed. The first valve 14, the second valve 15 and the third valve 16 can also be flow valves, specifically having two states: open and closed, which can be achieved by adjusting the opening degree of the flow valve (for example, the flow valve is in the open state when the opening degree is the largest, and in the closed state when the opening degree of the flow valve is the smallest).

[0040] When the load demand of the thermal system 10 of the coal-fired power unit meets the preset low load conditions, the first valve 14 and the third valve 16 are closed, and the second valve 15 is open. When the load demand of the thermal system 10 of the coal-fired power unit does not meet the preset low load conditions, the first valve 14 and the third valve 16 are open, and the second valve 15 is closed.

[0041] The load demand status corresponding to the thermal system 10 of the coal-fired power unit is used to characterize the load level corresponding to the heat and electricity demand of the supplier of the thermal system 10 of the coal-fired power unit under real-time conditions. When the load level characterized by the load demand status corresponding to the thermal system 10 of the coal-fired power unit is less than the preset load level threshold, it is determined that the load demand status corresponding to the thermal system 10 of the coal-fired power unit meets the preset low load condition. The preset load level threshold can be set by the user as needed, or it can correspond to the rated load level corresponding to the turbine pressure cylinder 13. Specifically, the preset load level threshold is less than the rated load level corresponding to the turbine pressure cylinder 13. For example, the preset load level threshold can be 70%, or it can be other values, which are not restricted here.

[0042] When the load demand of the thermal system 10 of the coal-fired power unit meets the preset low load conditions, all the main steam in the boiler 11 flows into the pressure regulating device 12. After being pressurized in the pressure regulating device 12, the main steam forms pressurized steam. The pressurized steam flows into the first air inlet 131 of the turbine pressure cylinder 13 through the second valve 15.

[0043] In this way, when the thermal system 10 of the coal-fired power unit is under low load, the pressure of the main steam can be increased to form pressurized steam, thereby making the pressure of the steam entering the turbine pressure cylinder 13 as high as possible, which can improve the thermoelectric conversion efficiency of the turbine pressure cylinder 13 to a certain extent.

[0044] When the load demand of the thermal system 10 of the coal-fired power unit does not meet the preset low load conditions, a portion of the main steam in the boiler 11 flows into the pressure regulating device 12. The main steam is pressurized in the pressure regulating device 12 to form pressurized steam. The pressurized steam flows into the second air inlet 132 of the turbine pressure cylinder 13 through the third valve 16, while another portion of the main steam flows into the first air inlet 131 of the turbine pressure cylinder 13 through the first valve 14.

[0045] In this way, when the thermal system of the coal-fired power unit is under high load, the steam can be supplemented to the turbine pressure cylinder 13 through the pressure regulating device 12, ensuring the steam intake in the turbine pressure cylinder 13, thereby enabling the turbine pressure cylinder 13 to meet the thermal power supply requirements, and thus enabling the thermal system 10 of the coal-fired power unit to meet the thermal power supply needs.

[0046] In one embodiment, the turbine pressure cylinder 13 includes a high-pressure cylinder and multiple sets of medium and low-pressure cylinders connected in sequence. Each set of medium and low-pressure cylinders includes one medium-pressure cylinder and two low-pressure cylinders. The ratio between the multiple sets of medium and low-pressure cylinders corresponds to the historical load demand distribution information of the environment in which the thermal system of the coal-fired power unit is located.

[0047] Among them, historical load demand distribution information is used to characterize the distribution of load demand in the corresponding environment of the coal-fired power unit's thermal system at a historical moment. The ratio between multiple groups of medium and low-pressure cylinders is used to characterize the proportion of steam intake information among multiple groups of medium and low-pressure cylinders. The ratio between multiple groups of medium and low-pressure cylinders includes at least one of the following: the proportion of air intake among multiple groups of medium and low-pressure cylinders, the proportion of load among multiple groups of medium and low-pressure cylinders, and the proportion of flow area among multiple groups of medium and low-pressure cylinders. The sum of the proportions of all medium and low-pressure cylinders is 1.

[0048] Taking the setting of two sets of medium and low pressure cylinders as an example, refer to Figure 3 The turbine pressure cylinder 13 includes a high-pressure cylinder 1301, a first intermediate-pressure cylinder 1302, a second intermediate-pressure cylinder 1303, a first low-pressure cylinder 1304, a second low-pressure cylinder 1305, a third low-pressure cylinder 1306, and a fourth low-pressure cylinder 1307. The air inlet of the first intermediate-pressure cylinder 1302 is connected to the air inlet of the second intermediate-pressure cylinder 1303. The air inlet of the first intermediate-pressure cylinder 1302 is also connected to the air inlets of the first low-pressure cylinder 1304 and the second low-pressure cylinder 1305. The air inlet of the second intermediate-pressure cylinder 1303 is connected to the air inlets of the third low-pressure cylinder 1306 and the fourth low-pressure cylinder 1307. The air inlet of the fourth low-pressure cylinder 1307 is connected. The first valve 14 is located between the first air outlet of the boiler 11 and the first air inlet 131 of the high-pressure cylinder 1301. The second valve 15 is located between the first exhaust port 121 of the pressure regulating device 12 and the first air inlet 131 of the high-pressure cylinder 1301. The third valve 16 is located between the first exhaust port 121 of the pressure regulating device 12 and the second air inlet 132 of the high-pressure cylinder 1301. The second air inlet of the boiler 11 is connected to the air inlets of the first intermediate-pressure cylinder 1302 and the second intermediate-pressure cylinder 1303, respectively.

[0049] The ratio between the first intermediate pressure cylinder 1302 and the second intermediate pressure cylinder 1303, the ratio between the first low pressure cylinder 1304 and the third low pressure cylinder 1306, and the ratio between the second low pressure cylinder 1305 and the fourth low pressure cylinder 1307 are equal. For example, the ratio between the three sets of pressure cylinders can be 5:5, 4:6, or 7:3, etc., and there is no limitation here.

[0050] When the load demand of the thermal system 10 of the coal-fired power unit meets the preset low load conditions, all the main steam in the boiler 11 flows into the pressure regulating device 12. After being pressurized in the pressure regulating device 12, the main steam becomes pressurized steam. The pressurized steam flows into the first air inlet 131 of the high-pressure cylinder 1301 through the second valve 15. The high-pressure cylinder 1301 uses the pressurized steam for thermoelectric conversion. When the load demand of the thermal system 10 of the coal-fired power unit does not meet the preset low load conditions, a portion of the main steam in the boiler 11 flows into the pressure regulating device 12. After being pressurized in the pressure regulating device 12, the pressurized steam flows into the second air inlet 132 of the high-pressure cylinder 1301 through the third valve 16. Another portion of the main steam flows into the first air inlet 131 of the turbine pressure cylinder 13 through the first valve 14. The high-pressure cylinder 1301 uses the pressurized steam and a portion of the main steam for thermoelectric conversion.

[0051] The reheated steam in boiler 11 flows into the first intermediate pressure cylinder 1302, the second intermediate pressure cylinder 1303, the first low pressure cylinder 1304, the second low pressure cylinder 1305, the third low pressure cylinder 1306, and the fourth low pressure cylinder 1307 through the second outlet of boiler 11. The first intermediate pressure cylinder 1302, the second intermediate pressure cylinder 1303, the first low pressure cylinder 1304, the second low pressure cylinder 1305, the third low pressure cylinder 1306, and the fourth low pressure cylinder 1307 use the reheated steam for thermoelectric conversion.

[0052] Among them, the high-pressure cylinder 1301, the first intermediate-pressure cylinder 1302, the second intermediate-pressure cylinder 1303, the first low-pressure cylinder 1304, the second low-pressure cylinder 1305, the third low-pressure cylinder 1306 and the fourth low-pressure cylinder 1307 are axially connected in sequence.

[0053] Thus, the high-pressure cylinder 1301, the first intermediate-pressure cylinder 1302, the second intermediate-pressure cylinder 1303, the first low-pressure cylinder 1304, the second low-pressure cylinder 1305, the third low-pressure cylinder 1306, and the fourth low-pressure cylinder 1307 can be axially connected in sequence to achieve the conversion between thermal energy and mechanical energy, and then the conducted mechanical energy can be converted into electrical energy by a generator.

[0054] In one embodiment, the thermal system 10 of the coal-fired power unit also includes a plurality of fourth valves.

[0055] Multiple fourth valves are respectively installed between the second air outlet 112 of the boiler 11 and the intermediate pressure cylinder (such as the first intermediate pressure cylinder 1302 and the second intermediate pressure cylinder 1303 mentioned above) in multiple sets of medium and low pressure cylinders, and are used to adjust the opening degree of the passage between the second air outlet 112 of the boiler 11 and the intermediate pressure cylinder.

[0056] The larger the opening degree of the fourth valve, the larger the opening degree of the passage between the second air outlet 112 of the boiler 11 and the intermediate pressure cylinder.

[0057] In one embodiment, the number of fourth valves is the same as the number of groups of medium and low pressure cylinders, and each fourth valve is located between the medium pressure cylinder in each group of medium and low pressure cylinders and the second air outlet 112 of the boiler 11.

[0058] Taking the setting of two sets of medium and low pressure cylinders as an example, refer to Figure 4 A fourth valve 17 is disposed between the second air outlet 112 of the boiler 11 and the first intermediate pressure cylinder 1302, for adjusting the opening of the passage between the second air outlet 112 of the boiler 11 and the first intermediate pressure cylinder 1302. Another fourth valve 17 is disposed between the second air outlet 112 of the boiler 11 and the second intermediate pressure cylinder 1303, for adjusting the opening of the passage between the second air outlet 112 of the boiler 11 and the second intermediate pressure cylinder 1303.

[0059] Thus, the steam intake of the first intermediate pressure cylinder 1302 and the second intermediate pressure cylinder 1303 can be adjusted through the fourth valve 17, thereby adjusting the steam intake of the first low pressure cylinder 1304 and the second low pressure cylinder 1305 connected to the first intermediate pressure cylinder 1302, as well as adjusting the steam intake of the third low pressure cylinder 1306 and the fourth low pressure cylinder 1307 connected to the second intermediate pressure cylinder 1303.

[0060] In one embodiment, the ratio between the turbine pressure cylinder 13 and the pressure regulating device 12 corresponds to the load demand of the coal-fired power unit thermal system 10.

[0061] The ratio between the turbine pressure cylinder 13 and the pressure regulating device 12 includes at least one of the following: the air intake ratio between the turbine pressure cylinder 13 and the pressure regulating device 12; the load ratio between the turbine pressure cylinder 13 and the pressure regulating device 12; and the flow area ratio between the turbine pressure cylinder 13 and the pressure regulating device 12.

[0062] It is understandable that when the load demand of the thermal system 10 of the coal-fired power unit does not meet the preset low load conditions, there is a risk that the turbine pressure cylinder 13 may not be able to meet the heat and power supply requirements. At this time, the turbine pressure cylinder 13 can be operated at the rated operating condition (maximum operating condition). However, the pressure regulating device 12 has a portion of the main steam allocated and supplementary steam to the turbine pressure cylinder 13. Therefore, although the turbine pressure cylinder 13 can meet the heat and power supply requirements, the turbine pressure cylinder 13 may still have a low heat and power conversion efficiency.

[0063] In one embodiment, the steam intake of the high-pressure cylinder 1301 in the turbine pressure cylinder 13 is greater than the steam intake of the pressure regulating device 12.

[0064] In this way, the steam intake of the turbine pressure cylinder 13 can be increased to a certain extent. However, when the difference between the steam intake of the high-pressure cylinder 1301 and the steam intake of the pressure regulating device 12 is not significant, the thermoelectric conversion efficiency of the turbine pressure cylinder 13 is still relatively low.

[0065] In one embodiment, reference Figure 5 The thermal system 10 of the coal-fired power unit also includes a fifth valve 18; the fifth valve 18 is located between the first air outlet 111 of the boiler 11 and the air inlet of the pressure regulating device 12, and is used to control the opening degree of the passage between the first air outlet 111 of the boiler 11 and the air inlet of the pressure regulating device 12.

[0066] Where the load level represented by the load demand condition corresponding to the thermal system 10 of the coal-fired power unit is not lower than the load level corresponding to the rated operating condition of the turbine pressure cylinder 13, the turbine pressure cylinder 13 is in the rated operating condition, and the valve opening of the fifth valve 18 corresponds to the load level difference value. The load level difference value is the difference between the load level represented by the load demand condition corresponding to the thermal system 10 of the coal-fired power unit and the load level corresponding to the rated operating condition of the turbine pressure cylinder 13. The higher the load level difference value, the larger the valve opening of the fifth valve 18.

[0067] In this way, both the high thermoelectric conversion efficiency of the turbine pressure cylinder 13 and the requirement to meet the thermoelectric supply can be guaranteed.

[0068] In one embodiment, the coal-fired power unit thermal system 10 also includes a first generator. The pressure regulating device 12 is connected to the first generator. When the load demand corresponding to the coal-fired power unit thermal system 10 does not meet the preset low load conditions, the first generator uses the heat loss between the pressure regulating device 12 and the turbine pressure cylinder 13 to perform thermoelectric conversion.

[0069] In this way, the heat loss between the pressure regulating device 12 and the turbine pressure cylinder 13 can be utilized through the first generator and the heat can be converted into electrical energy, which can reduce the energy loss of the thermal system 10 of the coal-fired power unit to a certain extent.

[0070] In one embodiment, the thermal system 10 of the coal-fired power unit further includes a high-pressure heating device, which is connected to the second exhaust port 122 of the pressure regulating device 12.

[0071] In cases where the load demand of the thermal system 10 of the coal-fired power unit does not meet the preset low load conditions, the high-pressure heating device is in the on state.

[0072] Thus, when the load demand of the thermal system 10 of the coal-fired power unit does not meet the preset low load conditions, the exhaust temperature of the pressure regulating device 12 is low. As a result, the temperature of the mixed water formed by mixing the condensate with the exhaust of the pressure regulating device 12 is also low. Therefore, the mixed water is heated by the high-pressure heating device to ensure the return water temperature of the boiler 11.

[0073] In one embodiment, the thermal system 10 of the coal-fired power unit also includes a condenser, which is connected to the third exhaust port 123 of the pressure regulating device 12.

[0074] When the thermal system 10 of the coal-fired power unit is in an accident condition, the exhaust steam from the pressure regulating device 12 flows into the condenser through the third exhaust port 123. The accident condition is an abnormal operating condition.

[0075] In this way, the pressure regulating device 12 can be guaranteed to operate normally under accident conditions.

[0076] In one detailed embodiment, taking the setting of two sets of medium and low pressure cylinders as an example, refer to... Figure 6The air inlet of the first intermediate-pressure cylinder 1302 is connected to the air inlet of the second intermediate-pressure cylinder 1303. The air inlet of the first intermediate-pressure cylinder 1302 is connected to the air inlets of the first low-pressure cylinder 1304 and the second low-pressure cylinder 1305, respectively. The air inlet of the second intermediate-pressure cylinder 1303 is connected to the air inlets of the third low-pressure cylinder 1306 and the fourth low-pressure cylinder 1307, respectively. The first valve 14 is located between the first air outlet of the boiler 11 and the first air inlet 131 of the high-pressure cylinder 1301. The second valve 15 is located between the first exhaust port 121 of the pressure regulating device 12 and... Between the first air inlet 131 of the high-pressure cylinder 1301, a third valve 16 is located between the first exhaust port 121 of the pressure regulating device 12 and the second air inlet 132 of the high-pressure cylinder 1301. The second air inlet of the boiler 11 is connected to the air inlets of the first intermediate-pressure cylinder 1302 and the second intermediate-pressure cylinder 1303, respectively. The exhaust ports of the first low-pressure cylinder 1304, the second low-pressure cylinder 1305, the third low-pressure cylinder 1306, and the fourth low-pressure cylinder 1307 are respectively connected. A fourth valve 17 is located between the second air outlet 112 and the second air outlet 1307 of the boiler 11. Between one intermediate-pressure cylinder 1302, another fourth valve 17 is located between the high-pressure cylinder 1301 and the second intermediate-pressure cylinder 1303. A fifth valve 18 is located between the first steam outlet 111 of the boiler 11 and the steam inlet of the pressure regulating device 12. The high-pressure heating device 19 is connected to the second exhaust port 122 of the pressure regulating device 12, the high-pressure cylinder 1301, the first intermediate-pressure cylinder 1302, and the second intermediate-pressure cylinder 1303. The condenser 20 is connected to the first intermediate-pressure cylinder 1302 and the second intermediate-pressure cylinder 1303. The condenser 20 is connected to the third exhaust port of the pressure regulating device 12. The high-pressure heating device 21 is connected to the first low-pressure cylinder 1304, the second low-pressure cylinder 1305, the third low-pressure cylinder 1306, and the fourth low-pressure cylinder 1307 respectively. The low-pressure heating device 21 is located between the high-pressure heating device 19 and the condenser 20. The pressure regulating device 12 is connected to the first generator 22. The high-pressure cylinder 1301, the first intermediate-pressure cylinder 1302, the second intermediate-pressure cylinder 1303, the first low-pressure cylinder 1304, the second low-pressure cylinder 1305, the third low-pressure cylinder 1306, the fourth low-pressure cylinder 1307, and the second generator 23 are axially connected in sequence.

[0077] When the load demand of the coal-fired power unit's thermal system 10 meets the preset low-load conditions, all the main steam in the boiler 11 flows into the pressure regulating device 12. After being pressurized in the pressure regulating device 12, the main steam becomes pressurized steam. This pressurized steam flows through the second valve 15 into the first air inlet 131 of the high-pressure cylinder 1301. The high-pressure cylinder 1301 uses the pressurized steam to achieve thermoelectric conversion through the second generator 23. When the load demand of the coal-fired power unit's thermal system 10 does not meet the preset low-load conditions, a portion of the main steam in the boiler 11 flows into the pressure regulating device 12. This portion of the main steam is pressurized in the pressure regulating device 12 to become pressurized steam. This pressurized steam flows through the third valve 16 into the second air inlet 132 of the high-pressure cylinder 1301, while the remaining portion of the main steam... Steam flows into the first inlet 131 of the turbine pressure cylinder 13 through the first valve 14. The high-pressure cylinder 1301 uses pressurized steam and part of the main steam to achieve thermoelectric conversion through the second generator 23. The heat loss between the pressure regulating device 12 and the high-pressure cylinder 1301 is converted into thermoelectricity through the first generator 22. The reheated steam in the boiler 11 flows into the first intermediate-pressure cylinder 1302, the second intermediate-pressure cylinder 1303, the first low-pressure cylinder 1304, the second low-pressure cylinder 1305, the third low-pressure cylinder 1306, and the fourth low-pressure cylinder 1307 through the second outlet of the boiler 11. The first intermediate-pressure cylinder 1302, the second intermediate-pressure cylinder 1303, the first low-pressure cylinder 1304, the second low-pressure cylinder 1305, the third low-pressure cylinder 1306, and the fourth low-pressure cylinder 1307 use reheated steam to achieve thermoelectric conversion through the second generator 23.

[0078] In this process, the condensate in the condenser flows into the low-pressure heating device 21. The exhaust steam from the first low-pressure cylinder 1304, the second low-pressure cylinder 1305, the third low-pressure cylinder 1306, and the fourth low-pressure cylinder 1307 is discharged into the low-pressure heating device 21 and mixes with the condensate to form mixed-temperature water. The mixed-temperature water flows into the high-pressure heating device. The exhaust steam from the high-pressure cylinder 1301, the first intermediate-pressure cylinder 1302, and the second intermediate-pressure cylinder 1303 is discharged into the high-pressure heating device 19. The mixed-temperature water is heated in the high-pressure heating device 19 with the exhaust steam from the high-pressure cylinder 1301, the first intermediate-pressure cylinder 1302, and the second intermediate-pressure cylinder 1303 to form return water, which is then returned to the boiler 11.

[0079] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0080] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A thermal system for a coal-fired power unit, characterized in that, include: Boiler, pressure regulating device and turbine pressure cylinder; The pressure regulating device is used to increase the steam pressure; the first outlet of the boiler is connected to the turbine pressure cylinder through the pressure regulating device, and the second outlet of the boiler is connected to the turbine pressure cylinder. The main steam in the boiler flows into the pressure regulating device through the first outlet of the boiler. The main steam is pressurized in the pressure regulating device to form pressurized steam. The pressurized steam flows into the turbine pressure cylinder. The reheat steam in the boiler flows into the turbine pressure cylinder through the second outlet of the boiler. The turbine pressure cylinder uses the pressurized steam and the reheat steam for thermoelectric conversion.

2. The thermal system of a coal-fired power unit as described in claim 1, characterized in that, The thermal system of the coal-fired power unit also includes: a first valve, a second valve, and a third valve; The first valve is located between the first air outlet of the boiler and the first air inlet of the turbine pressure cylinder, and is used to control the opening and closing of the passage between the first air outlet of the boiler and the first air inlet of the turbine pressure cylinder; The second valve is disposed between the first exhaust port of the pressure regulating device and the first inlet port of the turbine pressure cylinder, and is used to control the opening and closing of the passage between the first exhaust port of the pressure regulating device and the first inlet port of the turbine pressure cylinder; The third valve is located between the first exhaust port of the pressure regulating device and the second inlet port of the turbine pressure cylinder, and is used to control the opening and closing of the passage between the first exhaust port of the pressure regulating device and the second inlet port of the turbine pressure cylinder.

3. The thermal system of a coal-fired power unit as described in claim 2, characterized in that, When the load demand of the thermal system of the coal-fired power unit meets the preset low load conditions, the first valve and the third valve are in the closed state, and the second valve is in the open state. All the main steam in the boiler flows into the pressure regulating device. The main steam is pressurized in the pressure regulating device to form pressurized steam. The pressurized steam flows into the turbine pressure cylinder through the second valve. When the load demand of the thermal system of the coal-fired power unit does not meet the preset low load conditions, the first valve and the third valve are in the open state, and the second valve is in the closed state. A portion of the main steam in the boiler flows into the pressure regulating device, where it is pressurized to form pressurized steam. This pressurized steam then flows into the turbine pressure cylinder through the third valve. Another portion of the main steam in the boiler flows into the turbine pressure cylinder through the first valve, where the turbine pressure cylinder utilizes the main steam for thermoelectric conversion.

4. The thermal system of a coal-fired power unit as described in claim 2, characterized in that, The turbine pressure cylinder includes a high-pressure cylinder and multiple sets of medium and low-pressure cylinders connected in sequence. Each set of medium and low-pressure cylinders includes a medium-pressure cylinder and two low-pressure cylinders. The ratio between the multiple groups of medium and low pressure cylinders corresponds to the historical load demand distribution of the environment in which the thermal system of the coal-fired power unit is located.

5. The thermal system of a coal-fired power unit as described in claim 4, characterized in that, The thermal system of the coal-fired power unit also includes: multiple fourth valves; The plurality of fourth valves are respectively installed between the second air outlet of the boiler and the intermediate pressure cylinder in the plurality of low-pressure cylinders, and are used to adjust the opening of the passage between the high pressure cylinder and the intermediate pressure cylinder.

6. The thermal system of a coal-fired power unit as described in claim 5, characterized in that, The number of the fourth valves is the same as the number of groups of medium and low pressure cylinders, and each of the fourth valves is located between the medium pressure cylinder in each group of medium and low pressure cylinders and the second gas outlet of the boiler.

7. The thermal system of a coal-fired power unit as described in claim 2, characterized in that, The thermal system of the coal-fired power unit also includes a fifth valve; The fifth valve is located between the first air outlet of the boiler and the air inlet of the pressure regulating device, and is used to control the opening degree of the passage between the first air outlet of the boiler and the air inlet of the pressure regulating device.

8. The thermal system of a coal-fired power unit as described in claim 2, characterized in that, The thermal system of the coal-fired power unit also includes a first generator. The pressure regulating device is connected to the first generator. When the load demand of the thermal system of the coal-fired power unit does not meet the preset low load conditions, the first generator uses the heat loss between the pressure regulating device and the turbine pressure cylinder to perform thermoelectric conversion.

9. The thermal system of a coal-fired power unit according to claim 1, characterized in that, The thermal system of the coal-fired power unit also includes a high-pressure heating device, which is connected to the second exhaust port of the pressure regulating device.

10. The thermal system of a coal-fired power unit according to any one of claims 1 to 9, characterized in that, The thermal system of the coal-fired power unit also includes a condenser, which is connected to the third exhaust port of the pressure regulating device.

Images