Thermodynamic system of coupling back pressure turbine for wide-load peak regulation

Abstract

The utility model relates to the technical field of steam turbines, and discloses a thermodynamic system of a coupling back pressure turbine for wide-load peak regulation, which is provided with a boiler, a back pressure turbine, a high-pressure cylinder, an intermediate-pressure cylinder, a low-pressure cylinder, a generator and a recovery mechanism, the boiler is respectively connected with the back pressure machine, the high-pressure cylinder and the intermediate-pressure cylinder; the back pressure machine is connected with the high-pressure cylinder; the medium-pressure cylinder is connected with the low-pressure cylinder; the low-pressure cylinder is connected with the generator; the recycling mechanism is connected with the low-pressure cylinder and the boiler and used for condensing steam discharged by the low-pressure cylinder and recycling and conveying the steam to the boiler. In a high-load operation state, the thermodynamic system, the back pressure turbine and the high-pressure cylinder operate in parallel, and the boiler conveys steam to the back pressure turbine and the high-pressure cylinder. In the thermodynamic system in a low-load operation state, the back pressure machine and the high-pressure cylinder are connected in series for operation, the boiler conveys steam to the back pressure machine, and the back pressure machine conveys steam to the high-pressure cylinder. According to the utility model, the pressure of steam entering the steam turbine during low-load operation can be improved, and the feed water temperature and the operation economy can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of steam turbines, in particular to a thermal system of a coupled back pressure machine for wide load peak regulation. Background Art

[0002] Under the new power system, the proportion of installed capacity of new energy sources continues to increase. In the construction of large-scale wind, solar, thermal and storage bases under the future new power system architecture, new energy will serve as the main power source, and coal-fired power will be configured as a regulating power source. However, there is great uncertainty in the power generation capacity of new energy, which is greatly affected by climate, geography and other factors. This requires coal-fired power units to frequently participate in peak-shaving operations to ensure the stability of power grid operation. Therefore, the wide-load and efficient operation of coal-fired power units becomes crucial.

[0003] When the thermal system of a conventional coal-fired power unit operates at low load, the steam flow and pressure generated by the boiler will decrease, causing the turbine's working capacity to decline and the feed water temperature to drop. In order to maintain power generation, the boiler's coal consumption increases significantly, thereby increasing costs. Utility Model Content

[0004] The technical purpose of the present utility model is to address the deficiencies of the above-mentioned existing technologies and provide a thermal system for wide load peak regulation with a coupled back pressure machine, which is beneficial to increasing the steam pressure entering the turbine during low load operation, increasing the feed water temperature and improving the low load operation economy of the thermal system.

[0005] The technical solutions adopted in this utility model are as follows:

[0006] A thermal system coupled with a back pressure machine for wide load peak regulation, the thermal system comprising a boiler, a back pressure machine, a high-pressure cylinder, a medium-pressure cylinder, a low-pressure cylinder, a generator and a recovery mechanism;

[0007] The boiler is connected to the back pressure machine, the high-pressure cylinder and the intermediate-pressure cylinder through pipelines; the back pressure machine is connected to the high-pressure cylinder through a pipeline; the intermediate-pressure cylinder is connected to the low-pressure cylinder through a pipeline; the low-pressure cylinder is connected to the generator; the recovery mechanism is connected to the low-pressure cylinder and the boiler through pipelines, and is used to condense the steam discharged from the low-pressure cylinder and recover it and transport it to the boiler;

[0008] In the thermal system under high-load operation, the back pressure machine and the high-pressure cylinder operate in parallel, and the boiler supplies steam to the back pressure machine and the high-pressure cylinder respectively;

[0009] In the thermal system under low-load operation, the back pressure machine and the high-pressure cylinder operate in series, the boiler delivers steam to the back pressure machine, and the back pressure machine delivers steam to the high-pressure cylinder.

[0010] The above technical measures are achieved by setting a back pressure machine between the boiler and the high-pressure cylinder. Under high-load operation conditions, the back pressure machine and the high-pressure cylinder operate in parallel, and the boiler supplies steam to the back pressure machine and the high-pressure cylinder respectively; under low-load operation conditions, the back pressure machine and the high-pressure cylinder operate in series, and the boiler only supplies steam to the back pressure machine, which in turn supplies steam to the high-pressure cylinder. The steam pressure is adjusted by the back pressure machine, thereby increasing the steam pressure entering the high-pressure cylinder, and then increasing the feed water temperature, reducing the heating burden of the boiler, and being conducive to reducing coal consumption and improving the economy of the thermal system when operating at low load.

[0011] Furthermore, a first regulating valve is provided on the pipeline connecting the boiler and the high-pressure cylinder, a second regulating valve is provided on the pipeline connecting the boiler and the back pressure machine, and a third regulating valve is provided on the pipeline connecting the back pressure machine and the high-pressure cylinder;

[0012] In the thermal system under high-load operation, the first regulating valve and the second regulating valve are both in an open state, the third regulating valve is in a closed state, and the back pressure machine and the high-pressure cylinder operate in parallel;

[0013] In the thermal system under low-load operation, the second regulating valve and the third regulating valve are both in the open state, the first regulating valve is in the closed state, and the back pressure machine and the high-pressure cylinder operate in series.

[0014] The above technical measures enable the thermal system to flexibly switch the operating state between the back pressure machine and the high-pressure cylinder under high-load operating conditions and low-load operating conditions by setting the first regulating valve, the second regulating valve, and the third regulating valve, while facilitating the control of steam flow.

[0015] Furthermore, the back pressure machine is also connected to an industrial steam user through a pipeline, and a fourth regulating valve is provided on the pipeline connecting the back pressure machine and the industrial steam user.

[0016] The above technical measures are connected to industrial steam users through a back pressure machine, and the steam flow is controlled by a fourth regulating valve to realize wide load operation of the back pressure machine. This is beneficial to avoid energy loss caused by the back pressure machine being in hot standby state when the thermal system is operating at high load, thereby achieving wide load and efficient operation.

[0017] Furthermore, the back pressure machine, the high-pressure cylinder, the medium-pressure cylinder, and the low-pressure cylinder are coaxially arranged.

[0018] The above technical measures arrange the back pressure machine, high-pressure cylinder, medium-pressure cylinder and low-pressure cylinder coaxially, making the structure compact and easy to install; at the same time, it is beneficial to improve the energy transmission efficiency.

[0019] Furthermore, the recovery mechanism comprises a condenser, a condensate pump, a shaft seal heater, a low-pressure heating component, a deaerator, a feed water pump, and a high-pressure heating component which are sequentially connected through pipelines;

[0020] The low-pressure cylinder is connected to the condenser through a pipeline; the high-pressure heating assembly is connected to the boiler through a pipeline;

[0021] The low-pressure heating component is used to heat the condensate delivered by the shaft seal heater; the high-pressure heating component is used to heat the feed water delivered by the feed water pump.

[0022] The above technical measures can achieve steam recovery and reduce resource waste through the coordinated work of the condenser, condensate pump, shaft seal heater, low-pressure heating component, deaerator, feed water pump, and high-pressure heating component connected in sequence through pipelines.

[0023] Furthermore, the low-pressure heating assembly comprises a drain cooler, a first low-pressure heater, a second low-pressure heater, a third low-pressure heater, a fourth low-pressure heater and a fifth low-pressure heater which are sequentially connected by pipelines;

[0024] The drain cooler is connected to the shaft seal heater through a pipeline; the fifth low-pressure heater is connected to the deaerator through a pipeline;

[0025] The first low-pressure heater, the second low-pressure heater, the third low-pressure heater, and the fourth low-pressure heater are respectively connected to the low-pressure cylinder through pipelines, and the low-pressure cylinder provides steam to the first low-pressure heater, the second low-pressure heater, the third low-pressure heater, and the fourth low-pressure heater respectively;

[0026] The fifth low-pressure heater is connected to the intermediate-pressure cylinder via a pipeline, and the intermediate-pressure cylinder provides steam for the fifth low-pressure heater;

[0027] The first low-pressure heater and the second low-pressure heater are both provided with a drain pipe, and the drain pipe of the first low-pressure heater and the drain pipe of the second low-pressure heater are respectively connected to the drain cooler.

[0028] In the above technical measures, the drain cooler uses the drain of the first low-pressure heater and the second low-pressure heater to heat the condensate, while achieving the effect of lowering the drain temperature; the condensate then passes through the first low-pressure heater, the second low-pressure heater, the third low-pressure heater, the fourth low-pressure heater and the fifth low-pressure heater in sequence to achieve step-by-step heating, which is beneficial to improving the heating efficiency.

[0029] Furthermore, the drain cooler, the third low-pressure heater, the fourth low-pressure heater and the fifth low-pressure heater are all provided with drain pipes;

[0030] The drain pipe of the drain cooler is connected to the condenser, the drain pipe of the fifth low-pressure heater is connected to the fourth low-pressure heater, and the drain pipe of the fourth low-pressure heater is connected to the third low-pressure heater;

[0031] The third low-pressure heater is provided with a drain pump, and the drain pump is used to transport the drain water in the third low-pressure heater to the pipeline between the third low-pressure heater and the fourth low-pressure heater.

[0032] The above technical measures achieve gravity flow of drain water by setting up a drain pipe and utilizing the effect of pressure difference, and use a drain pump to transport the drain water into the pipe, which is conducive to preventing poor drain water transportation under load operation and ensuring smooth flow of drain water. At the same time, the heat of drain water can be used to heat condensate water, thereby improving economic efficiency. The drain pipe of the drain cooler is connected to the condenser, so that the drain water in the drain cooler can be recovered.

[0033] Furthermore, the high-pressure heating assembly comprises a first high-pressure heater, a second high-pressure heater, a third high-pressure heater and a fourth high-pressure heater which are sequentially connected by pipelines;

[0034] The first high-pressure heater is connected to the feedwater pump through a pipeline, and the fourth high-pressure heater is connected to the boiler through a pipeline;

[0035] The first high-pressure heater is connected to the intermediate-pressure cylinder via a pipeline, and the intermediate-pressure cylinder provides steam for the first high-pressure heater;

[0036] The second high-pressure heater and the third high-pressure heater are respectively connected to the high-pressure cylinder through pipelines, and the high-pressure cylinder provides steam to the second high-pressure heater and the third high-pressure heater respectively;

[0037] The fourth high-pressure heater is connected to a back pressure machine through a pipeline, and the back pressure machine provides steam for the fourth high-pressure heater.

[0038] The above technical measures are beneficial to increase the feed water temperature, reduce boiler coal consumption and improve economy by setting up multiple high-pressure heaters, and each high-pressure heater draws steam from the back pressure machine, high-pressure cylinder and medium-pressure cylinder for heating.

[0039] Furthermore, a fifth regulating valve is provided on the pipeline connecting the fourth high-pressure heater and the back pressure machine;

[0040] In the thermal system under high-load operation, the fifth regulating valve is closed, and the pipeline connecting the fourth high-pressure heater and the back pressure machine is disconnected;

[0041] In the thermal system under low-load operation, the fifth regulating valve is in an open state, and the pipeline connecting the fourth high-pressure heater and the back pressure machine serves as a passage.

[0042] The above technical measures can flexibly control the on / off of the pipeline between the fourth high-pressure heater and the back pressure machine by using the fifth regulating valve, and can be adjusted in time according to different operating conditions, which is conducive to avoiding overheating of the feed water under high-load operating conditions.

[0043] Furthermore, the first high-pressure heater, the second high-pressure heater, the third high-pressure heater and the fourth high-pressure heater are all provided with a drain pipe;

[0044] The drain pipe of the first high-pressure heater is connected to the deaerator, the drain pipe of the second high-pressure heater is connected to the first high-pressure heater, the drain pipe of the third high-pressure heater is connected to the second high-pressure heater, and the drain pipe of the fourth high-pressure heater is connected to the third high-pressure heater.

[0045] In the above technical measures, the first high-pressure heater, the second high-pressure heater, the third high-pressure heater and the fourth high-pressure heater are all provided with drain pipes, and the pressure difference is used to realize the gravity flow of the drain; the drain finally flows into the deaerator, and after being deoxygenated in the deaerator, it is transported to the boiler in turn through the feed water pump and the high-pressure heating assembly to realize the recovery of the drain; at the same time, the heat of the drain is used to heat the feed water to increase the feed water temperature.

[0046] One or more technical solutions provided by this utility model have at least the following technical effects or advantages:

[0047] The utility model arranges a back pressure machine between the boiler and the high-pressure cylinder. When operating at high load, the back pressure machine and the high-pressure cylinder operate in parallel, and the boiler supplies steam to the back pressure machine and the high-pressure cylinder respectively. When operating at low load, the back pressure machine and the high-pressure cylinder operate in series, and the boiler only supplies steam to the back pressure machine, which in turn supplies steam to the high-pressure cylinder. The steam pressure is adjusted by the back pressure machine, thereby increasing the steam pressure entering the high-pressure cylinder, and further increasing the feed water temperature, reducing the heating burden of the boiler, and being beneficial to reducing coal consumption and improving the economy of the thermal system when operating at low load. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of the present invention, and do not constitute a limitation of the embodiments of the present invention;

[0049] Figure 1 It is a structural schematic diagram of the utility model;

[0050] Among them, 1- boiler; 2- back pressure machine; 3- high pressure cylinder; 4- medium pressure cylinder; 5- low pressure cylinder; 6- generator; 7- first regulating valve; 8- second regulating valve; 9- third regulating valve; 10- fourth regulating valve; 11- condenser; 12- condensate pump; 13- shaft seal heater; 14- low pressure heating assembly; 141- drain cooler; 142- first low pressure heater; 143- second low pressure heater; 144- third low pressure heater; 145- fourth low pressure heater; 146- fifth low pressure heater; 147- drain pump; 15- deaerator; 16- feed water pump; 17- high pressure heating assembly; 171- first high pressure heater; 172- second high pressure heater; 173- third high pressure heater; 174- fourth high pressure heater; 18- fifth regulating valve; 19- sixth regulating valve; 20- steam cooler; 21- feed water pump turbine. DETAILED DESCRIPTION

[0051] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present invention and the features therein can be combined with each other without conflict.

[0052] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0053] Reference Figure 1 This embodiment provides a thermal system coupled with a back pressure machine for wide load peak regulation, the thermal system comprising a boiler 1, a back pressure machine 2, a high-pressure cylinder 3, a medium-pressure cylinder 4, a low-pressure cylinder 5, a generator 6 and a recovery mechanism;

[0054] Among them, the back pressure machine 2, the high-pressure cylinder 3, the medium-pressure cylinder 4, and the low-pressure cylinder 5 are coaxially arranged.

[0055] The boiler 1 is connected to the back pressure machine 2, the high pressure cylinder 3, and the intermediate pressure cylinder 4 through pipelines; the back pressure machine 2 is connected to the high pressure cylinder 3 through pipelines; the intermediate pressure cylinder 4 is connected to the low pressure cylinder 5 through pipelines; the low pressure cylinder 5 is connected to the generator 6; the recovery mechanism is connected to the low pressure cylinder 5 and the boiler 1 through pipelines, and is used to condense the steam discharged from the low pressure cylinder 5 and recover it and transport it to the boiler 1;

[0056] In the thermal system under high-load operation, the back pressure machine 2 and the high-pressure cylinder 3 operate in parallel, and the boiler 1 supplies steam to the back pressure machine 2 and the high-pressure cylinder 3 respectively;

[0057] In the thermal system under low-load operation, the back pressure machine 2 and the high-pressure cylinder 3 operate in series, the boiler 1 delivers steam to the back pressure machine 2, and the back pressure machine 2 delivers steam to the high-pressure cylinder 3.

[0058] A first regulating valve 7 is provided on the pipeline connecting the boiler 1 and the high-pressure cylinder 3, a second regulating valve 8 is provided on the pipeline connecting the boiler 1 and the back pressure machine 2, and a third regulating valve 9 is provided on the pipeline connecting the back pressure machine 2 and the high-pressure cylinder 3;

[0059] In the thermal system under high-load operation, the first regulating valve 7 and the second regulating valve 8 are both open, the third regulating valve 9 is closed, and the back pressure machine 2 and the high-pressure cylinder 3 operate in parallel;

[0060] In the thermal system under low-load operation, the second regulating valve 8 and the third regulating valve 9 are both in the open state, the first regulating valve 7 is in the closed state, and the back pressure machine 2 and the high-pressure cylinder 3 operate in series.

[0061] The back pressure machine 2 is also connected to an industrial steam user through a pipeline. A fourth regulating valve 10 is provided on the pipeline connecting the back pressure machine 2 and the industrial steam user.

[0062] The recovery mechanism comprises a condenser 11, a condensate pump 12, a shaft seal heater 13, a low-pressure heating assembly 14, a deaerator 15, a feed water pump 16, and a high-pressure heating assembly 17, which are sequentially connected through pipelines;

[0063] The intermediate pressure cylinder 4 is also connected to the feed water pump turbine 21 through a pipeline. The feed water pump turbine 21 is connected to the feed water pump 16. The feed water pump turbine 21 is used to drive the feed water pump 16 to deliver water ( Figure 1 The connection between the feed water pump turbine 21 and the feed water pump 16 is not shown).

[0064] The deaerator 15 is connected to the medium-pressure cylinder 4 through a pipeline, and the medium-pressure cylinder 4 provides steam for the deaerator 15 .

[0065] The low-pressure cylinder 5 is connected to the condenser 11 through a pipeline; the high-pressure heating component 17 is connected to the boiler 1 through a pipeline;

[0066] The low-pressure heating assembly 14 is used to heat the condensate delivered by the shaft seal heater 13; the high-pressure heating assembly 17 is used to heat the feed water delivered by the feed water pump 16; the condenser 11 is used to condense the steam discharged from the low-pressure cylinder 5 into condensate, and the condensate pump 12 is used to deliver the condensate to the deaerator 15 through the shaft seal heater 13 and the low-pressure heating assembly 14. The shaft seal heater 13 is used to heat the condensate using steam leaked from the turbine; the deaerator 15 is used to deoxygenate the delivered condensate to form feed water; the feed water pump 16 is used to deliver the feed water to the boiler 1 through the high-pressure heating assembly 17;

[0067] The low-pressure heating assembly 14 comprises a drain cooler 141, a first low-pressure heater 142, a second low-pressure heater 143, a third low-pressure heater 144, a fourth low-pressure heater 145 and a fifth low-pressure heater 146 which are sequentially connected by pipelines;

[0068] The drain cooler 141 is connected to the shaft seal heater 13 through a pipeline; the fifth low-pressure heater 146 is connected to the deaerator 15 through a pipeline;

[0069] The first low-pressure heater 142, the second low-pressure heater 143, the third low-pressure heater 144 and the fourth low-pressure heater 145 are respectively connected to the low-pressure cylinder 5 through pipelines, and the low-pressure cylinder 5 provides steam to the first low-pressure heater 142, the second low-pressure heater 143, the third low-pressure heater 144 and the fourth low-pressure heater 145 respectively;

[0070] The fifth low-pressure heater 146 is connected to the intermediate-pressure cylinder 4 through a pipeline, and the intermediate-pressure cylinder 4 provides steam for the fifth low-pressure heater 146;

[0071] The first low-pressure heater 142 and the second low-pressure heater 143 are both provided with drain pipes. The drain pipes of the first low-pressure heater 142 and the drain pipes of the second low-pressure heater 143 are respectively connected to the drain cooler 141 .

[0072] The drain cooler 141, the third low-pressure heater 144, the fourth low-pressure heater 145 and the fifth low-pressure heater 146 are all provided with drain pipes;

[0073] The drain pipe of the drain cooler 141 is connected to the condenser 11 , the drain pipe of the fifth low-pressure heater 146 is connected to the fourth low-pressure heater 145 , and the drain pipe of the fourth low-pressure heater 145 is connected to the third low-pressure heater 144 ;

[0074] The third low-pressure heater 144 is provided with a drain pump 147 , which is used to transport drain water in the third low-pressure heater 144 to a pipeline between the third low-pressure heater 144 and the fourth low-pressure heater 145 .

[0075] The shaft seal heater 13 is provided with a drain pipe, and the drain pipe of the shaft seal heater 13 is connected to the condenser 11;

[0076] The high-pressure heating assembly 17 comprises a first high-pressure heater 171, a second high-pressure heater 172, a third high-pressure heater 173 and a fourth high-pressure heater 174 which are sequentially connected by pipelines;

[0077] The first high-pressure heater 171 is connected to the feed water pump 16 through a pipeline, and the fourth high-pressure heater 174 is connected to the boiler 1 through a pipeline;

[0078] The first high-pressure heater 171 is connected to the intermediate-pressure cylinder 4 through a pipeline, and the intermediate-pressure cylinder 4 provides steam for the first high-pressure heater 171. A steam cooler 20 is provided on the pipeline connecting the first high-pressure heater 171 and the intermediate-pressure cylinder 4. The steam cooler 20 is used to cool the steam provided by the intermediate-pressure cylinder 4 to the first high-pressure heater 171, which helps to reduce the exergy loss in the heat exchange process and improve the heat exchange efficiency.

[0079] The second high-pressure heater 172 and the third high-pressure heater 173 are connected to the high-pressure cylinder 3 through pipelines, and the high-pressure cylinder 3 provides steam to the second high-pressure heater 172 and the third high-pressure heater 173 respectively;

[0080] The fourth high-pressure heater 174 is connected to the back pressure machine 2 through a pipeline, and the back pressure machine 2 provides steam to the fourth high-pressure heater 174 .

[0081] A fifth regulating valve 18 is provided on the pipeline connecting the fourth high-pressure heater 174 and the back pressure machine 2;

[0082] In the thermal system under high-load operation, the fifth regulating valve 18 is closed, and the pipeline connecting the fourth high-pressure heater 174 and the back pressure machine 2 is disconnected;

[0083] In the thermal system under low-load operation, the fifth regulating valve 18 is in the open state, and the pipeline connecting the fourth high-pressure heater 174 and the back pressure machine 2 is a passage.

[0084] The first high-pressure heater 171, the second high-pressure heater 172, the third high-pressure heater 173 and the fourth high-pressure heater 174 are all provided with drainage pipes;

[0085] The drain pipe of the first high-pressure heater 171 is connected to the deaerator 15, the drain pipe of the second high-pressure heater 172 is connected to the first high-pressure heater 171, the drain pipe of the third high-pressure heater 173 is connected to the second high-pressure heater 172, and the drain pipe of the fourth high-pressure heater 174 is connected to the third high-pressure heater 173.

[0086] The back pressure machine 2 is also connected to the condenser 11 through a pipeline. A sixth regulating valve 19 is provided on the pipeline connecting the back pressure machine 2 and the condenser 11. The sixth regulating valve 19 is in an open state in accident conditions or heat rejection load conditions, etc., to facilitate emergency discharge of steam; it is in a closed state during normal operation to ensure efficient use of steam.

[0087] The first high-pressure heater 171, the second high-pressure heater 172, the third high-pressure heater 173, the fourth high-pressure heater 174, the first low-pressure heater 142, the second low-pressure heater 143, the third low-pressure heater 144, the fourth low-pressure heater 145 and the fifth low-pressure heater 146 are all provided with emergency drain pipes, which are respectively connected to the same drain expansion tank, and the drain expansion tank is respectively connected to the hot well and the throat of the condenser 11; the emergency drain pipes are usually used only when a fault condition occurs (heater failure, etc.).

[0088] Under normal operating conditions, the drain water of the first low-pressure heater 142 and the second low-pressure heater 143 flows into the drain cooler 141, and then flows into the condenser 11 through the drain pipe of the drain cooler 141; the third low-pressure heater 144, the fourth low-pressure heater 145 and the fifth low-pressure heater 146 realize gravity flow through each drain pipe under the action of the pressure difference, and the drain water of the fifth low-pressure heater 146 flows into the fourth low-pressure heater 145, and then flows into the third low-pressure heater 144 together with the drain water of the fourth low-pressure heater 145, and is transported to the condensate transport unit 11 through the drain pump 147. the first high-pressure heater 171, the second high-pressure heater 172, the third high-pressure heater 173, and the fourth high-pressure heater 174 realize gravity flow through each drain pipe under the action of the pressure difference. The drain of the fourth high-pressure heater 174 flows into the third high-pressure heater 173, and then flows into the second high-pressure heater 172 together with the drain of the third high-pressure heater 173, and then flows into the first high-pressure heater 171 together with the drain of the second high-pressure heater 172, and finally flows into the deaerator 15 together with the drain of the first high-pressure heater 171, and enters the pipeline for conveying water after deoxygenation.

[0089] When in high-load operation, the first regulating valve 7, the second regulating valve 8, and the fourth regulating valve 10 are opened, and the third regulating valve 9, the fifth regulating valve 18, and the sixth regulating valve 19 are closed; the back pressure machine 2 and the high-pressure cylinder 3 operate in parallel, and the steam generated by the boiler 1 is respectively transmitted to the back pressure machine 2 and the high-pressure cylinder 3, and the steam discharged from the high-pressure cylinder 3 is reheated by the boiler reheater of the boiler 1 and then transmitted to the intermediate-pressure cylinder 4. The steam discharged from the intermediate-pressure cylinder 4 is transmitted to the low-pressure cylinder 5 through a pipeline, thereby driving the generator 6 to generate electricity; the high-pressure cylinder 3 provides steam to the second high-pressure heater 172 and the third high-pressure heater 173 respectively, and the intermediate-pressure cylinder 4 provides steam to the first high-pressure heater 171, the deaerator 15, the fifth low-pressure heater 146, and the feedwater pump turbine 21 respectively, and the low-pressure cylinder 5 provides steam to the first low-pressure heater 142, the second low-pressure heater 143, the third low-pressure heater 144, and the fourth low-pressure heater 145 respectively; the steam discharged from the low-pressure cylinder 5 passes through the condenser 1 1 condenses into condensate and is transported to the shaft seal heater 13 through the condensate pump 12. The shaft seal heater 13 uses the steam leaked from the turbine to heat the condensate and transports the heated condensate to the drain cooler 141. The drain cooler 141 uses the drain from the first low-pressure heater 142 and the second low-pressure heater 143 to heat the condensate, cool the drain at the same time, and discharge it into the hot well of the condenser 11 through the drain pipe. The condensate passes through the first low-pressure heater 142, the second low-pressure heater 143, the third low-pressure heater 144, the fourth low-pressure heater 145, and the fifth low-pressure heater 146 in sequence for heating step by step, and then flows into the deaerator 15 for deoxygenation to form feed water. The feed water is transported to the first high-pressure heater 171 through the feed water pump 16, and passes through the first high-pressure heater 171, the second high-pressure heater 172, and the third high-pressure heater 173 in sequence for heating step by step. Finally, the feed water flows into the boiler 1 and is recovered.

[0090] When in low-load operation, the second regulating valve 8, the third regulating valve 9, the fourth regulating valve 10 and the fifth regulating valve 18 are opened, and the first regulating valve 7 and the sixth regulating valve 19 are closed; the back pressure machine 2 and the high-pressure cylinder 3 are operated in series, and the steam generated by the boiler 1 is only delivered to the back pressure machine 2. After the steam is pressurized by the back pressure machine 2, the pressurized steam is delivered to the high-pressure cylinder 3. The steam discharged from the high-pressure cylinder 3 is reheated by the boiler reheater of the boiler 1 and then delivered to the medium-pressure cylinder 4. The steam discharged from the medium-pressure cylinder 4 is delivered to the The low-pressure cylinder 5 drives the generator 6 to generate electricity; the back pressure machine 2 provides steam to the fourth high-pressure heater 174; the high-pressure cylinder 3 provides steam to the second high-pressure heater 172 and the third high-pressure heater 173 respectively; the intermediate-pressure cylinder 4 provides steam to the first high-pressure heater 171, the deaerator 15, the fifth low-pressure heater 146 and the feedwater pump turbine 21 respectively; the low-pressure cylinder 5 provides steam to the first low-pressure heater 142, the second low-pressure heater 143, the third low-pressure heater 144 and the fourth low-pressure heater 145 respectively Steam; The steam discharged from the low-pressure cylinder 5 is condensed into condensate through the condenser 11 and transported to the shaft seal heater 13 through the condensate pump 12. The shaft seal heater 13 uses the steam leaked from the turbine to heat the condensate and transports the heated condensate to the drain cooler 141. The drain cooler 141 uses the drain from the first low-pressure heater 142 and the second low-pressure heater 143 to heat the condensate, and at the same time cools the drain and discharges it into the condenser 11 hot well through the drain pipe. The condensate passes through the first The low-pressure heater 142, the second low-pressure heater 143, the third low-pressure heater 144, the fourth low-pressure heater 145 and the fifth low-pressure heater 146 are heated step by step, and then flow into the deaerator 15 for deoxygenation to form feed water. The feed water is transported to the first high-pressure heater 171 through the feed water pump 16, and is heated step by step through the first high-pressure heater 171, the second high-pressure heater 172, the third high-pressure heater 173 and the fourth high-pressure heater 174 in turn, and finally the feed water flows into the boiler 1 to complete the recovery.

[0091] During the load reduction process, when the load is reduced to a preset load value, the first regulating valve 7 is gradually closed, and the third regulating valve 9 and the fifth regulating valve 18 are gradually opened.

[0092] During the process of increasing the load, when the load reaches a preset value, the first regulating valve 7 is gradually opened, and the third regulating valve 9 and the fifth regulating valve 18 are gradually closed.

[0093] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0094] Obviously, those skilled in the art may make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if such modifications and variations fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include such modifications and variations.

Claims

1. A thermal system coupled with a back pressure machine for wide load peak regulation, characterized by: The thermal system comprises a boiler (1), a back pressure machine (2), a high-pressure cylinder (3), a medium-pressure cylinder (4), a low-pressure cylinder (5), a generator (6) and a recovery mechanism; The boiler (1) is connected to the back pressure machine (2), the high pressure cylinder (3) and the medium pressure cylinder (4) through pipelines; the back pressure machine (2) is connected to the high pressure cylinder (3) through a pipeline; the medium pressure cylinder (4) is connected to the low pressure cylinder (5) through a pipeline; the low pressure cylinder (5) is connected to the generator (6); the recovery mechanism is connected to the low pressure cylinder (5) and the boiler (1) through pipelines, and the recovery mechanism is used to condense the steam discharged from the low pressure cylinder (5) and recover and transport it to the boiler (1); In the thermal system under high-load operation, the back pressure machine (2) and the high-pressure cylinder (3) operate in parallel, and the boiler (1) delivers steam to the back pressure machine (2) and the high-pressure cylinder (3) respectively; In the thermal system under low-load operation, the back pressure machine (2) and the high-pressure cylinder (3) operate in series, the boiler (1) delivers steam to the back pressure machine (2), and the back pressure machine (2) delivers steam to the high-pressure cylinder (3).

2. The thermal system for wide load peak regulation coupled with a back pressure machine according to claim 1, characterized in that: A first regulating valve (7) is provided on the pipeline connecting the boiler (1) and the high-pressure cylinder (3), a second regulating valve (8) is provided on the pipeline connecting the boiler (1) and the back pressure machine (2), and a third regulating valve (9) is provided on the pipeline connecting the back pressure machine (2) and the high-pressure cylinder (3); In the thermal system under high-load operation, the first regulating valve (7) and the second regulating valve (8) are both in an open state, the third regulating valve (9) is in a closed state, and the back pressure machine (2) and the high-pressure cylinder (3) operate in parallel; In the thermal system under low-load operation, the second regulating valve (8) and the third regulating valve (9) are both in an open state, the first regulating valve (7) is in a closed state, and the back pressure machine (2) and the high-pressure cylinder (3) operate in series.

3. The thermal system for wide load peak regulation coupled with a back pressure machine according to claim 1, characterized in that: The back pressure machine (2) is also connected to an industrial steam user via a pipeline, and a fourth regulating valve (10) is provided on the pipeline connecting the back pressure machine (2) and the industrial steam user.

4. The thermal system for wide load peak regulation coupled with a back pressure machine according to claim 1, characterized in that: The back pressure machine (2), the high-pressure cylinder (3), the medium-pressure cylinder (4), and the low-pressure cylinder (5) are coaxially arranged.

5. The thermal system for coupling a back pressure machine for wide load peak regulation according to claim 1, characterized in that: The recovery mechanism comprises a condenser (11), a condensate pump (12), a shaft seal heater (13), a low-pressure heating component (14), a deaerator (15), a feed water pump (16), and a high-pressure heating component (17) which are sequentially connected through pipelines; The low-pressure cylinder (5) is connected to the condenser (11) via a pipeline; the high-pressure heating assembly (17) is connected to the boiler (1) via a pipeline; The low-pressure heating component (14) is used to heat the condensate delivered by the shaft seal heater (13); the high-pressure heating component (17) is used to heat the feed water delivered by the feed water pump (16).

6. The thermal system for wide load peak regulation coupled with a back pressure machine according to claim 5, characterized in that: The low-pressure heating assembly (14) comprises a drain cooler (141), a first low-pressure heater (142), a second low-pressure heater (143), a third low-pressure heater (144), a fourth low-pressure heater (145), and a fifth low-pressure heater (146) which are sequentially connected via pipelines; The drain cooler (141) is connected to the shaft seal heater (13) via a pipeline; the fifth low-pressure heater (146) is connected to the deaerator (15) via a pipeline; The first low-pressure heater (142), the second low-pressure heater (143), the third low-pressure heater (144), and the fourth low-pressure heater (145) are respectively connected to the low-pressure cylinder (5) through pipelines, and the low-pressure cylinder (5) provides steam to the first low-pressure heater (142), the second low-pressure heater (143), the third low-pressure heater (144), and the fourth low-pressure heater (145); The fifth low-pressure heater (146) is connected to the medium-pressure cylinder (4) through a pipeline, and the medium-pressure cylinder (4) provides steam for the fifth low-pressure heater (146); The first low-pressure heater (142) and the second low-pressure heater (143) are both provided with a drain pipe, and the drain pipe of the first low-pressure heater (142) and the drain pipe of the second low-pressure heater (143) are respectively connected to the drain cooler (141).

7. The thermal system for wide load peak regulation coupled with a back pressure machine according to claim 6, characterized in that: The drain cooler (141), the third low-pressure heater (144), the fourth low-pressure heater (145), and the fifth low-pressure heater (146) are all provided with drain pipes; The drain pipe of the drain cooler (141) is connected to the condenser (11), the drain pipe of the fifth low-pressure heater (146) is connected to the fourth low-pressure heater (145), and the drain pipe of the fourth low-pressure heater (145) is connected to the third low-pressure heater (144); The third low-pressure heater (144) is provided with a drain pump (147), and the drain pump (147) is used to transport the drain in the third low-pressure heater (144) to the pipeline between the third low-pressure heater (144) and the fourth low-pressure heater (145).

8. The thermal system for wide load peak regulation coupled with a back pressure machine according to claim 5, characterized in that: The high-pressure heating assembly (17) comprises a first high-pressure heater (171), a second high-pressure heater (172), a third high-pressure heater (173), and a fourth high-pressure heater (174) which are sequentially connected via pipelines; The first high-pressure heater (171) is connected to the feed water pump (16) via a pipeline, and the fourth high-pressure heater (174) is connected to the boiler (1) via a pipeline; The first high-pressure heater (171) is connected to the medium-pressure cylinder (4) via a pipeline, and the medium-pressure cylinder (4) provides steam for the first high-pressure heater (171); The second high-pressure heater (172) and the third high-pressure heater (173) are respectively connected to the high-pressure cylinder (3) through pipelines, and the high-pressure cylinder (3) provides steam to the second high-pressure heater (172) and the third high-pressure heater (173); The fourth high-pressure heater (174) is connected to the back pressure machine (2) through a pipeline, and the back pressure machine (2) provides steam for the fourth high-pressure heater (174).

9. The thermal system for wide load peak regulation coupled with a back pressure machine according to claim 8, characterized in that: A fifth regulating valve (18) is provided on the pipeline connecting the fourth high-pressure heater (174) and the back pressure machine (2); In the thermal system under high-load operation, the fifth regulating valve (18) is in a closed state, and the pipeline connecting the fourth high-pressure heater (174) and the back pressure machine (2) is disconnected; In the thermal system under low-load operation, the fifth regulating valve (18) is in an open state, and the pipeline connecting the fourth high-pressure heater (174) and the back pressure machine (2) is a passage.

10. The thermal system coupled with a back pressure machine for wide load peak regulation according to claim 8, characterized in that: The first high-pressure heater (171), the second high-pressure heater (172), the third high-pressure heater (173), and the fourth high-pressure heater (174) are all provided with a drain pipe; The drain pipe of the first high-pressure heater (171) is connected to the deaerator (15), the drain pipe of the second high-pressure heater (172) is connected to the first high-pressure heater (171), the drain pipe of the third high-pressure heater (173) is connected to the second high-pressure heater (172), and the drain pipe of the fourth high-pressure heater (174) is connected to the third high-pressure heater (173).

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