High-back-pressure heat supply system

Abstract

The utility model provides a high-back-pressure heat supply system, and relates to the technical field of heat supply and energy conservation. The high-back-pressure heat supply system comprises a compression device used for compressing dead steam discharged by a low-pressure cylinder to generate first steam; the heat exchange device is used for heating the heat supply network return water through waste heat of the first steam, the first steam becomes drain water after heat loss and is fed into the cooling recovery device, and the heated heat supply network return water is used for supplying heat; dead steam discharged by the low-pressure cylinder enters the cooling recovery device to be cooled and then becomes condensed water to be stored, and drained water discharged by the heat exchange device is recovered through the cooling recovery device. According to the high-back-pressure heat supply system, the compression device is arranged to compress the dead steam so as to increase the pressure and temperature of the dead steam to become the first steam, then the first steam is used for heating the heat supply network return water to supply heat, and the problem that the dead steam utilization rate is low is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of heating and energy saving, and in particular to a high back pressure heating system. Background Art

[0002] Today's energy structure is rapidly transitioning toward a clean, low-carbon future. The clean and efficient use of coal resources is a key cornerstone of energy security. Thermal power unit heating retrofits are a crucial tool for achieving energy conservation and emission reduction, and a crucial direction for adjusting the thermal power energy structure under the new normal of "double reduction, double low" electricity consumption. They offer advantages such as energy conservation, emission reduction, and improved business environment. The development of cogeneration and centralized heating continues to receive significant attention.

[0003] Currently, the main cogeneration transformation technologies include: central perforated heating, bypass heating, and low-temperature waste heat utilization, including high back-pressure heating and heat pump heating. These technologies directly recover turbine exhaust steam to heat the heat network's circulating water, fully utilizing the exhaust steam heat and converting it into heat for heating. This significantly reduces the turbine's cooling losses, offering significant social and energy benefits. However, due to the safety characteristics of the low-pressure cylinder's final and sub-final stages, the maximum back pressure for heating in air-cooled units can only reach 30-33 kPa, resulting in low exhaust steam utilization. High back-pressure heating in wet-cooled units requires replacement of the low-pressure cylinder rotor to meet this requirement. This rotor replacement, which requires twice a year to achieve high back-pressure heating in wet-cooled units, results in high operating, maintenance, and overhaul costs. Furthermore, traditional high back-pressure heating systems have limited adaptability and impose high requirements on both heat and electricity loads. High back-pressure heating is only economical when the heating load reaches a certain level. At the same time, high-back-pressure heating units, due to their high operating back pressure, are limited by the minimum cooling flow rate of the low-pressure cylinder, which limits their peak-shaving capabilities and operational flexibility, making it difficult to meet the frequent and large-scale frequency and peak-shaving needs of the power grid. Therefore, a device or system that can address at least one of the above issues is urgently needed. Utility Model Content

[0004] The purpose of the embodiment of the utility model is to provide a high back pressure heating system for solving the problem of low exhaust steam utilization rate in the prior art.

[0005] In order to achieve the above-mentioned purpose, the utility model provides a high back pressure heating system, which is connected to the low pressure cylinder of the steam turbine and the heat network system. The high back pressure heating system includes:

[0006] a compression device, wherein a steam inlet of the compression device is connected to the exhaust port of the low-pressure cylinder and is used to compress the exhaust steam discharged from the low-pressure cylinder to generate first steam;

[0007] The heat exchange device has a heat exchange inlet, a heat exchange outlet, a heat exchange water inlet and a heat exchange water outlet. The heat exchange inlet of the heat exchange device is connected to the steam outlet of the compression device. The return water of the heat network system enters the heat exchange device through the heat exchange water inlet. The heat exchange device is used to heat the return water of the heat network by using the waste heat of the first steam. After the first steam loses heat, it becomes condensate, and the condensate flows out from the heat exchange outlet of the heat exchange device and is sent to the cooling recovery device. The heated return water of the heat network is discharged from the heat exchange water outlet of the heat exchange device for heating.

[0008] It has a cooling inlet and a cooling water return port. The cooling inlet of the cooling recovery device is connected to the exhaust port of the low-pressure cylinder. The cooling water return port of the cooling recovery device is connected to the heat exchange water outlet of the heat exchange device. The exhaust steam discharged from the low-pressure cylinder enters the cooling recovery device and is cooled to become condensate for storage. The condensate discharged from the heat exchange device is recovered through the cooling recovery device.

[0009] Specifically, the high back-pressure heating system further includes: a maintenance bypass, which is arranged between the exhaust port of the low-pressure cylinder and the steam outlet of the compression device, and the maintenance bypass is connected in parallel with the steam flow pipeline of the compression device.

[0010] Specifically, a first manual valve is arranged on the maintenance bypass.

[0011] Specifically, the high back-pressure heating system further includes: a heating device, which is connected to the heat exchange water outlet of the heat exchange device and is used for secondary heating of the return water of the heat network discharged from the heat exchange device.

[0012] Specifically, the high back-pressure heating system further includes: a preheating heat exchange device, which has a preheating inlet, a preheating outlet, a preheating water inlet and a preheating water outlet. The preheating inlet is connected to the exhaust port of the low-pressure cylinder. The preheating outlet is connected to the cooling water return port of the cooling recovery device. The preheating water outlet is connected to the heat exchange water inlet of the heat exchange device. The return water of the heat network enters the preheating heat exchange device from the preheating water inlet.

[0013] The preheating heat exchange device is used to preheat the return water of the heat network by using the exhaust steam. After the exhaust steam loses heat, it becomes condensate and is discharged from the preheating outlet of the preheating heat exchange device and then enters the cooling recovery device.

[0014] Specifically, the cooling recovery device includes: an air-cooled tower and a hot water well;

[0015] The water inlet of the hot water well serves as the cooling water return port of the cooling recovery device;

[0016] The air-cooled inlet of the air-cooled tower serves as the cooling inlet of the cooling recovery device. The air-cooled inlet is connected to the exhaust port of the low-pressure cylinder. The air-cooled outlet of the air-cooled tower is connected to the water inlet of the hot water well. The air-cooled tower is used to cool the exhaust steam discharged from the exhaust port of the low-pressure cylinder to generate condensate, and the condensate enters the hot water well for storage;

[0017] The hot well is used to recover the drain water discharged from the self-heat exchange device and the condensate water discharged from the preheating heat exchange device.

[0018] Specifically, the cooling and recovery device includes: a condenser, a hot well at the lower part of the condenser, and a cooling water supply assembly;

[0019] The cooling water supply assembly is used to convey circulating water to the condenser;

[0020] The condenser has a steam condensation inlet, a steam condensation outlet, a circulating water inlet, and a circulating water outlet. The steam condensation inlet of the condenser is connected to the exhaust port of the low-pressure cylinder, and the steam condensation outlet of the condenser is connected to the water inlet of the hot well at the lower part of the condenser. The condenser uses circulating water to cool the exhaust steam discharged from the low-pressure cylinder to generate condensate water;

[0021] The water inlet of the hot well at the lower part of the condenser is also connected to the heat exchange outlet of the heat exchange device, and is used to store the condensate water and recover the drain water discharged from the heat exchange device;

[0022] Specifically, the cooling water supply assembly includes: a cooling tower, and a cooling circulation loop formed between the cooling tower and the condenser;

[0023] The cooling tower conveys circulating water to the condenser through the cooling circulation loop. After the circulating water absorbs the heat of the exhaust steam, it is heated to become heated circulating water. The heated circulating water flows through the cooling circulation loop to the cooling tower, and the heated circulating water is cooled by the cooling tower to become circulating water.

[0024] Specifically, the cooling water supply assembly further includes: a circulating water pump, which is arranged on the cooling circulation loop between the circulating water outlet of the cooling tower and the circulating water inlet of the condenser. The circulating water pump is used to pump the circulating water in the cooling tower into the condenser.

[0025] Specifically, the cooling water supply assembly further includes: a peak shaving bypass and a variable frequency pump;

[0026] The peak shaving bypass is arranged between the circulating water outlet of the cooling tower and the circulating water inlet of the condenser;

[0027] The variable frequency pump is arranged on the peak shaving bypass, and the variable frequency pump is used to adjust the flow rate of the circulating water pumped into the condenser 43.

[0028] The high back-pressure heating system provided by the present utility model has the exhaust port of the low-pressure cylinder connected to the steam inlet of the compression device and the steam inlet of the heat exchange device. In this way, the exhaust steam discharged from the exhaust port of the low-pressure cylinder is divided into two paths. One path enters the compression device through the steam inlet of the compression device, and the exhaust steam is compressed by the compression device to increase the temperature and pressure of the exhaust steam. The exhaust steam after temperature increase and pressure boost becomes the first steam. Then, the first steam is used to heat the return water of the heat network, improving the quality and utilization rate of the exhaust steam. After the first steam loses heat, it becomes condensate and is sent to the cooling and recovery device. The other path of the exhaust steam enters the cooling and recovery device, and the exhaust steam is cooled by the cooling and recovery device to become condensate. The high back-pressure heating system provided by the present utility model solves the problem of low utilization rate of exhaust steam in the prior art by setting a compression device to increase the pressure and temperature of the exhaust steam, and then using the exhaust steam after temperature increase and pressure boost to heat the return water of the heat network to supply heat to users, improving the utilization rate of the exhaust steam. At the same time, the exhaust steam discharged from the exhaust port of the low-pressure cylinder is set in two paths, which is convenient for the unit to flexibly adjust the peak load.

[0029] Other features and advantages of the embodiments of the present utility model will be described in detail in the subsequent specific implementation part. Brief Description of the Drawings

[0030] The drawings are used to provide a further understanding of the embodiments of the present utility model, and constitute a part of the specification. Together with the following specific implementation, they are used to explain the embodiments of the present utility model, but do not constitute a limitation to the embodiments of the present utility model. In the drawings:

[0031] Figure 1 is a schematic structural diagram of the high back-pressure heating system provided by the embodiment of the present utility model;

[0032] Figure 2 is a schematic structural diagram of the high back-pressure heating system provided by another embodiment of the present utility model;

[0033] Figure 3 is a schematic structural diagram of the high back-pressure heating system provided by still another embodiment of the present utility model.

[0034] Description of the Reference Numerals in the Drawings

[0035] 1-Low-pressure cylinder; 2-Compression device; 3-Heat exchange device; 4-Cooling recovery device; 5-Maintenance bypass; 6-Heating device; 7-Preheating heat exchange device; 41-Air cooling tower; 42-Hot water well; 43-Condenser; 44-Condenser lower hot well; 45-Cooling water supply assembly; 46-Fourth electric butterfly valve; 451-Cooling tower; 452-Circulating water pump; 453-Peak-shaving bypass; 454-Variable frequency pump; 455-Fourth manual valve; 456-Third electric gate valve ;457-fifth manual valve;458 fourth electric gate valve;459-sixth manual valve;51-first manual valve;71-first electric regulating valve;72-third electric butterfly valve;73-third manual valve;74-second electric gate valve;75-preheating drain pump;81-reheating water pump;82-steam turbine unit heat recovery system;83-first electric butterfly valve;84-second manual valve;85-first electric gate valve;86-drain pump;87-second electric butterfly valve. DETAILED DESCRIPTION

[0036] The following describes the specific implementation of the embodiment of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the embodiment of the present invention and is not intended to limit the embodiment of the present invention.

[0037] Figure 1 It is a structural diagram of a high back pressure heating system; Figure 2 It is a structural diagram of another high back pressure heating system; Figure 3 This is a structural diagram of a high back pressure heating system. Figures 1 - 3 As shown, the utility model provides a high back pressure heating system, which is connected to the low pressure cylinder 1 of the steam turbine and the heat network system. The high back pressure heating system includes:

[0038] A compression device 2, wherein the steam inlet of the compression device 2 is connected to the exhaust port of the low-pressure cylinder 1, and is used to compress the exhaust steam discharged from the low-pressure cylinder 1 to generate the first steam;

[0039] The heat exchange device 3 has a heat exchange inlet, a heat exchange outlet, a heat exchange water inlet, and a heat exchange water outlet. The heat exchange inlet of the heat exchange device 3 is connected to the steam outlet of the compression device 2. The return water of the heat network system enters the heat exchange device 3 through the heat exchange water inlet. The heat exchange device 3 is used to heat the return water of the heat network using the waste heat of the first steam. After losing heat, the first steam becomes drain water. The drain water flows out of the heat exchange outlet of the heat exchange device 3 and is sent to the cooling recovery device 4. The heated return water of the heat network is discharged from the heat exchange outlet of the heat exchange device 3 for heat supply.

[0040] The cooling and recovery device 4 has a cooling inlet and a cooling water return port. The cooling inlet of the cooling and recovery device 4 is connected to the exhaust port of the low-pressure cylinder 1, and the cooling water return port of the cooling and recovery device 4 is connected to the heat exchange water outlet of the heat exchange device 3. The exhaust steam discharged from the low-pressure cylinder 1 enters the cooling and recovery device 4, is cooled and then stored as condensate, and the drain water discharged from the heat exchange device 3 is recovered through the cooling and recovery device 4.

[0041] In the high back-pressure heating system provided by the present utility model, the exhaust steam discharged from the exhaust port of the low-pressure cylinder 1 of the steam turbine flows in two paths. One path is discharged from the exhaust port of the low-pressure cylinder 1 and enters the compression device 2 through the steam inlet of the compression device 2. The exhaust steam is compressed by the compression device 2 to increase the pressure and temperature of the exhaust steam. The exhaust steam after temperature rise and pressure increase becomes the first steam. The maximum pressure of the first steam can reach 54-60 kPa. The first steam enters the heat exchange device 3 through the heat exchange inlet of the heat exchange device 3 and exchanges heat with the return water of the heat supply network entering the heat exchange device 3 through the heat exchange water inlet, so as to heat the return water of the heat supply network by the first steam. Compared with the exhaust steam, the temperature and pressure of the first steam are higher, and it can better heat the return water of the heat supply network, improving the utilization rate of the exhaust steam. After the first steam heats the return water of the heat supply network, it loses heat and becomes drain water, which is discharged from the heat exchange outlet of the heat exchange device 3 and sent into the cooling and recovery device 4, while the return water of the heat supply network that absorbs heat is discharged from the heat exchange water outlet of the heat exchange device 3 and then used for heating, as Figure 1 shown. The power supply is provided for the compression device 2 by an electric motor, and the compression device 2 is a compressor. The other path of exhaust steam can enter the cooling and recovery device 4 through the cooling inlet of the cooling device 4. The exhaust steam is cooled in the cooling and recovery device 4 and becomes condensate. The condensate and the drain water are mixed in the cooling and recovery device 4 to form mixed water. The mixed water in the cooling and recovery device 4 can be pumped to the regenerative system 82 of the steam turbine unit by the hot water return pump 81. In the high back-pressure heating system provided by the present utility model, by setting the compression device 2 to compress the exhaust steam to increase the pressure and temperature of the exhaust steam, and then using the exhaust steam after temperature rise and pressure increase to heat the return water of the heat supply network to supply heat to users, the problem of low utilization rate of exhaust steam in the prior art is solved, the utilization rate of the exhaust steam is improved, and at the same time, the exhaust steam discharged from the exhaust port of the low-pressure cylinder 1 is arranged in two paths, which is convenient for the unit to flexibly adjust the peak load.

[0042] In one example, as Figure 1As shown, the high back-pressure heating system further includes: a maintenance bypass 5, which is arranged between the exhaust port of the low-pressure cylinder 1 and the steam outlet of the compression device 2, and the maintenance bypass 5 is connected in parallel with the steam flow pipeline of the compression device 2. A first manual valve 51 is arranged on the maintenance bypass 5. The high back-pressure heating system further includes: a heating device 6, which is connected to the heat exchange water outlet of the heat exchange device 3 and is used for secondary heating of the heat network return water discharged from the heat exchange device 3. The cooling recovery device 4 includes: an air cooling tower 41 and a hot water well 42; the water inlet of the hot water well 42 serves as the cooling return water inlet of the cooling recovery device 4; the air cooling inlet of the air cooling tower 41 serves as the cooling inlet of the cooling recovery device 4, the air cooling inlet is connected to the exhaust port of the low-pressure cylinder 1, the air cooling outlet of the air cooling tower 41 is connected to the water inlet of the hot water well 42, and the air cooling tower 41 is used for cooling the exhaust steam discharged from the exhaust port of the low-pressure cylinder 1 to generate condensate, and the condensate enters the hot water well 42 for storage; the hot water well 42 is used for recovering the drain water discharged from the heat exchange device 3 and the condensate discharged from the preheating heat exchange device 7.

[0043] Taking a 330MW subcritical air-cooled unit as an example, the exhaust port of the low-pressure cylinder 1 is connected to the steam inlet of the compression device 2 through a first pipeline, and a first electric butterfly valve 83 is arranged on the first pipeline to control the flow state of the exhaust steam in the first pipeline; when the unit supplies heat in winter, the first electric butterfly valve 83 is opened, and the exhaust steam enters the compression device 2 through the first pipeline and the steam inlet of the compression device 2, and the exhaust steam entering is compressed by the compression device 2 to increase the pressure and temperature of the exhaust steam to become the first steam. The compression device 2 is a compressor, and the first steam is discharged from the steam outlet of the compression device 2 and then enters the heat exchange device 3. The heat exchange device 3 has a heat exchange inlet, a heat exchange outlet, a heat exchange water inlet and a heat exchange water outlet. The first steam enters from the heat exchange inlet of the heat exchange device 3 and exchanges heat with the heat network return water entering from the heat exchange water inlet of the heat exchange device 3. The heat exchange device 3 is a high back-pressure condenser. The heat network return water absorbs the heat of the first steam, and the first steam loses heat and becomes drain water and is discharged from the heat exchange outlet of the heat exchange device 3. The heat network return water is heated and then discharged from the heat exchange water outlet of the heat exchange device 3. In order to increase the temperature of the heat network return water, a heating device 6 is arranged at the heat exchange water outlet of the heat exchange device 3, and the heating device 6 is used to reheat the heated heat network return water discharged from the heat exchange water outlet of the heat exchange device 3. The heating device 6 is a peak heater. The heat exchange outlet of the heat exchange device 3 is connected to the water inlet of the hot water well 42 of the cooling recovery device 4 through a second pipeline, and the drain water can flow into the hot water well 42 through the second pipeline. A second manual valve 84, a first electric gate valve 85 and a drain water pump 86 are arranged on the second pipeline in the flowing direction of the drain water in sequence. The second manual valve 84 and the first electric gate valve 85 can control the flow state of the drain water in the second pipeline, and the drain water pump 86 arranged on the second pipeline can pump the drain water to the hot water well 42 faster.

[0044] To facilitate the maintenance of the compression device 2, a maintenance bypass 5 is provided in parallel with the steam flow pipeline of the compression device 2. The steam flow pipeline of the compression device 2 refers to the pipeline between the internal steam inlet and the steam outlet of the compression device 2. The exhaust steam enters the compression device 2 from the steam inlet, and after being compressed by the compression device 2, it becomes the first steam and is discharged from the steam outlet. When the compression device 2 needs to be maintained, the exhaust steam can flow through the maintenance bypass 5, thus isolating the compression device 2 for convenient maintenance. To control the flow state of the exhaust steam in the maintenance bypass 5, at least one first manual valve 51 is provided on the maintenance bypass 5 to control the flow state of the exhaust steam.

[0045] The exhaust port of the low-pressure cylinder 1 is connected to the air-cooling inlet of the air-cooling tower 41 through the third pipeline. Another part of the exhaust steam discharged from the exhaust port of the low-pressure cylinder 1 enters the air-cooling tower 41 through the third pipeline. A second electric butterfly valve 87 is provided on the third pipeline to control the flow state of the exhaust steam in the third pipeline. The exhaust steam enters the air-cooling tower 41 through the air-cooling inlet of the air-cooling tower 41, and after being cooled in the air-cooling tower 41, it becomes condensate, which is discharged from the air-cooling outlet of the air-cooling tower 41 and enters the hot well 42. The hot well 42 also recovers the drain water discharged from the heat exchange outlet of the heat exchange device 3. The mixed water formed by the drain water and the condensate is pumped to the regenerative system 82 of the steam turbine unit by the hot well water pump 81.

[0046] Assume that the return water flow of the heat supply network is 10,000 t / h and the return water temperature of the heat supply network is 45 °C. Taking the average heat load of 300 MW during the heating period as an example, the compression device 2 is a compressor, and the pressure ratio of the compression device 2 is set to 1.8. When the unit load is 204.14 MW, the unit back pressure is 19.15 kPa, and the pressure of the first steam formed after all the exhaust steam of the low-pressure cylinder 1 is upgraded by the compression device 2 is 34.46 kPa. The first steam enters the heat exchange device 3. Compared with the high back pressure operation of the original unit, the high back pressure operation of the original unit is 33 kPa, and the minimum operating load of the unit is 258.16 MW. It can be seen that after adding the steam compression device 2, the thermoelectric decoupling ability of the unit in high back pressure operation is significantly enhanced. The return water of the heat supply network is preliminarily heated to 70.84 °C in the heat exchange device 3 and then supplied for heat. When the unit load is lower than 204.14 MW, the first electric butterfly valve 83 on the third pipeline is closed, and the unit operates in pure high back pressure, resulting in insufficient heat supply of the return water of the heat supply network. At this time, the return water of the heat supply network flowing out of the heat exchange device 3 can be reheated by the heating device 6; when the unit load is higher than 204.14 MW, the first electric butterfly valve 83 on the third pipeline is opened, and the excess exhaust steam enters the air-cooling tower 41.

[0047] Taking the average heat load of 455 MW during the heating period as an example, assuming the pressure ratio of the compression device 2 is 1.8, when the unit load is 311.10 MW, the back pressure of the unit is 33 kPa, and the exhaust steam flow rate of the low-pressure cylinder 1 is 711.16 t / h. All the exhaust steam enters the compression device 2, and after quality improvement, the pressure of the first steam becomes 59.46 kPa. The first steam enters the heat exchange device 3. The return water of the heat network is preliminarily heated to 84.20 °C by the first steam in the heat exchange device 3 and then supplies heat to the outside. When the unit load is lower than 311.10 MW, the first electric butterfly valve 83 on the third pipeline closes, and the unit operates at a pure high back pressure, resulting in insufficient heat supply for the return water of the heat network. At this time, the return water of the heat network flowing out of the heat exchange device 3 can be reheated through the heating device 6; when the unit load is higher than 311.10 MW, the first electric butterfly valve 83 on the third pipeline opens, and the excess exhaust steam enters the air cooling tower 41. Taking the unit load of 311.10 MW as an example, when the original unit operates at a high back pressure, the operating back pressure of the unit is 33 kPa, the exhaust steam flow rate of the low-pressure cylinder 1 is 711.16 t / h, the heat exchange device 3 absorbs 459.65 t / h of exhaust steam, and the remaining 251.51 t / h of exhaust steam enters the air cooling tower 41. After adding the compression device 2, all the exhaust steam enters the heat exchange device 3 and absorbs heat from the return water of the heat network, greatly improving the utilization rate of the exhaust steam of the steam turbine, with remarkable social and economic benefits.

[0048] In another example, as Figure 2 shown, the high back pressure heat supply system further includes: a preheating heat exchange device 7, having a preheating inlet, a preheating outlet, a preheating water inlet, and a preheating water outlet. The preheating inlet is connected to the exhaust port of the low-pressure cylinder 1, the preheating outlet is connected to the cooling return water port of the cooling recovery device 4, the preheating water outlet is connected to the heat exchange water inlet of the heat exchange device 3, and the return water of the heat network enters the preheating heat exchange device 7 from the preheating water inlet;

[0049] The preheating heat exchange device 7 is used to preheat the return water of the heat network by using the exhaust steam. After the exhaust steam loses heat, it becomes condensed water and is discharged from the preheating outlet of the preheating heat exchange device 7 and then enters the cooling recovery device 4.

[0050] The cooling recovery device 4 includes: an air cooling tower 41 and a hot well 42; the water inlet of the hot well 42 serves as the cooling return water port of the cooling recovery device 4; the air cooling inlet of the air cooling tower 41 serves as the cooling inlet of the cooling recovery device 4. The air cooling inlet is connected to the exhaust port of the low-pressure cylinder 1, the air cooling outlet of the air cooling tower 41 is connected to the water inlet of the hot well 42, and the air cooling tower 41 is used to cool the exhaust steam discharged from the exhaust port of the low-pressure cylinder 1 to generate condensed water, and the condensed water enters the hot well 42 for storage; the hot well 42 is used to recover the drain water discharged from the heat exchange device 3 and the condensed water discharged from the preheating heat exchange device 7.

[0051] The preheating heat exchange device 7 is a high back-pressure condenser. The preheating heat exchange device 7 has a preheating inlet, a preheating outlet, a preheating water inlet, and a preheating water outlet. The preheating inlet of the preheating heat exchange device 7 is connected to the exhaust port of the low-pressure cylinder 1 through a fourth pipeline. The preheating outlet is connected to the water inlet of the hot well 42 through a fifth pipeline. The preheating water outlet is connected to the heat exchange water inlet of the heat exchange device 3 through a sixth pipeline. The exhaust steam discharged from the exhaust port of the low-pressure cylinder 1 can be divided into three paths. One path enters the compression device 2, another path enters the cooling and recovery device 4, and the other path enters the preheating heat exchange device 7. The exhaust steam enters from the preheating inlet of the preheating heat exchange device 7 and exchanges heat with the heat network return water that enters the preheating heat exchange device 7 through the preheating water inlet at the same time. The heat network return water absorbs the waste heat of the exhaust steam in the preheating heat exchange device 7 and then heats up. After losing heat, the exhaust steam becomes condensate and is discharged from the preheating outlet and enters the hot well 42 of the cooling and recovery device 4. The heat network return water is preheated by the exhaust steam. The preheated heat network return water is discharged from the preheating water outlet of the preheating heat exchange device 7 and then flows through the sixth pipeline into the heat exchange device 3. The exhaust steam that enters the compression device 2 is compressed and then heated up and pressurized to become the first steam and enters the heat exchange device 3. The preheated heat network return water enters the heat exchange device 3 and exchanges heat with the first steam. The preheated heat network return water is reheated by the first steam again. The reheated heat network return water enters the heating device 6. The heat network return water discharged from the water outlet of the heat exchange device 3 is heated by the heating device 6. The heat network return water heated by the heating device 6 is used for heating. Another path of exhaust steam enters the air cooling tower 41 of the cooling and recovery device 4 and is cooled in the cooling tower 41. After cooling, it becomes condensate and is sent into the hot well 42 for storage.

[0052] In order to control the flow state of the exhaust steam in the fourth pipeline, a first electric regulating valve 71 and a third electric butterfly valve 72 are sequentially arranged on the fourth pipeline along the flow direction of the exhaust steam. The flow state of the exhaust steam in the fourth pipeline is controlled by the third electric butterfly valve 72. The flow rate of the exhaust steam flowing through the fourth pipeline is adjusted by the first electric regulating valve 71. After the exhaust steam preheats the heat network return water in the preheating heat exchange device 7, it becomes condensate. The condensate flows out from the preheating outlet of the preheating heat exchange device 7 and then enters the hot well 42 through the fifth pipeline. In order to improve the speed of the condensate entering the hot well 42, a third manual valve 73, a second electric gate valve 74, and a preheating drain pump 75 are sequentially arranged on the fifth pipeline along the flow direction of the condensate. The third manual valve 73 and the second electric gate valve 74 can control the flow state of the condensate in the fifth pipeline. The preheating drain pump 75 can quickly pump the condensate in the preheating heat exchange device 7 into the hot well 42.

[0053] Taking a 330MW subcritical air-cooled unit as an example, when the unit supplies heat in winter, assuming the return water flow rate of the heat network is 10,000t / h and the return water temperature of the heat network is 45°C. Taking the average heat load of 300MW during the heating period as an example, assuming the pressure ratio of the compression device 2 is 1.8. When the unit load is 207.02MW, the valve core opening of the first electric control valve 71 is adjusted. When the unit back pressure is 19.17kPa, the exhaust steam enters the preheating heat exchange device 7 and the heat exchange device 3 respectively. The high back pressure heat supply just meets the demand of the average heat load of 300MW during the heating period. The second electric butterfly valve 87 on the third pipeline is closed. One-way exhaust steam enters the preheating heat exchange device 7 after passing through the first electric control valve 71 and the third electric butterfly valve 72, and the pressure of the preheating heat exchange device 7 is 19.17kPa; the other way of exhaust steam enters the compression device 2 through the first electric butterfly valve 83 and the first pipeline. After being compressed, pressurized and heated by the compression device 2, the exhaust steam enters the heat exchange device 3, and the pressure of the exhaust steam after compression is 34.51kPa. After the return water of the heat network is initially heated to 57.65°C by the exhaust steam in the preheating heat exchange device 7, it enters the heat exchange device 3 through the sixth pipeline and is further heated to 70.85°C by the first steam and then supplies heat to the outside. After the exhaust steam releases heat and becomes condensate in the preheating heat exchange device 7, it enters the hot well 42 through the third manual valve 73, the second electric gate valve 74 and the preheating drain pump 75. The first steam releases heat and becomes drain water in the heat exchange device 3, and the drain water flows through the second pipeline into the hot well 42. After the condensate and the drain water are mixed in the hot well 42, they are pumped to the regenerative system 82 of the steam turbine unit by the hot water pump 81. Compared with the high back pressure operation of the original unit, the high back pressure of the original unit is 33kPa, and the minimum operating load of the unit is 258.16MW. It can be seen from this that the thermoelectric decoupling ability of the unit in high back pressure operation is significantly enhanced after adding the compression device 2. Compared with the first embodiment, considering the efficiency of the compression device 2 is 80%, the power consumption of the compression device 2 in the second embodiment is 7352kW. Compared with the power consumption of 14406kW of the compression device 2 in the first embodiment, the power consumption is reduced by 7054kW. The second embodiment realizes cascade high back pressure heat supply, the compression device 2 has small power consumption, and the energy saving benefit is obvious. When the unit load is lower than 207.02MW, the second electric butterfly valve 87 is closed, and the unit operates in pure cascade high back pressure mode. The insufficient heat of the high back pressure heat supply is supplemented by the heating device 6. When the unit load is higher than 207.02MW, the second electric butterfly valve 87 on the third pipeline is opened, and the excess exhaust steam enters the air cooling tower 41.

[0054] Taking the average heat load of 455 MW during the heating period as an example, assuming the pressure ratio of the compression device 2 is 1.8, when the unit load is 316.80 MW, the back pressure of the unit is 33 kPa. Adjust the valve core opening of the first electric control valve 71. When the back pressure of the unit is 33 kPa, all the exhaust steam enters the preheating heat exchange device 7 and the heat exchange device 3. The high back pressure heat supply just meets the demand of the average heat load of 455 MW during the heating period. The second electric butterfly valve 87 on the third pipeline is closed. One part of the exhaust steam enters the high preheating heat exchange device 7, and the pressure of the preheating heat exchange device 7 is 33 kPa; one part of the exhaust steam first enters the compression device 2, is compressed, pressurized and heated by the compression device 2 and then enters the heat exchange device 3. After being compressed, the pressure of the exhaust steam is 59.46 kPa. The return water of the heat network is preliminarily heated to 69.80 °C in the preheating heat exchange device 7 and then enters the heat exchange device 3 to be continuously heated to 84.17 °C and then supply heat to the outside. When the unit load is lower than 316.80 MW, the second electric butterfly valve 87 on the third pipeline is closed, and the unit operates at a pure cascade high back pressure. The insufficient heat of the high back pressure heat supply is supplemented by the heating device 6. When the unit load is higher than 316.80 MW, the second electric butterfly valve 87 on the third pipeline is opened, and the excess exhaust steam enters the air cooling tower 41. Taking the unit load of 316.80 MW as an example, when the original unit operates at a high back pressure, the operating back pressure of the unit is 33 kPa, and the exhaust steam of the low-pressure cylinder 1 is 721.20 t / h. The preheating heat exchange device 7 and the heat exchange device 3 absorb 459.65 t / h of exhaust steam, and the remaining 261.51 t / h enters the air cooling tower 41. After adding the compression device 2 and adopting cascade high back pressure heat supply, all the exhaust steam is absorbed by the preheating heat exchange device 7 and the heat exchange device 3, greatly improving the utilization rate of the exhaust steam, and the social and economic benefits are remarkable. Compared with the first embodiment, considering the efficiency of the compression device 2 is 80%, the power consumption of the compressor in the second embodiment is 8347 kW, compared with the power consumption of 22785 kW of the compression device 2 in the first embodiment, the power consumption is reduced by 14438 kW. The second scheme realizes cascade high back pressure heat supply, the compressor power consumption is small, and the energy-saving benefit is obvious.

[0055] In yet another embodiment, as Figure 3 shown, a condenser 43 is provided to cool the exhaust steam discharged from the low-pressure cylinder 1. The cooling and recovery device 4 includes: a condenser 43, a hot well 44 at the lower part of the condenser, and a cooling water supply assembly 45;

[0056] The cooling water supply assembly 45 is used to supply circulating water to the condenser 43;

[0057] The condenser 43 has a steam condensation inlet, a steam condensation outlet, a circulating water inlet and a circulating water outlet. The steam condensation inlet of the condenser 43 is connected to the exhaust port of the low-pressure cylinder 1, and the steam condensation outlet of the condenser 43 is connected to the water inlet of the hot well 44 at the lower part of the condenser. The condenser 43 uses circulating water to cool the exhaust steam discharged from the low-pressure cylinder 1 to generate condensed water;

[0058] The water inlet of the hot well 44 at the lower part of the condenser is also connected to the heat exchange outlet of the heat exchange device 3, which is used to store the condensed water and recover the drain water discharged from the heat exchange device 3.

[0059] The cooling water supply assembly 45 includes: a cooling tower 451, and a cooling circulation loop formed between the cooling tower 451 and the condenser 43;

[0060] The cooling tower 451 conveys circulating water to the condenser 43 through the cooling circulation loop. After absorbing the heat of the exhaust steam, the circulating water is heated up to become heated circulating water, and the heated circulating water flows through the cooling circulation loop to the cooling tower 451, and the heated circulating water is cooled by the cooling tower 451 to become circulating water.

[0061] The cooling water supply assembly 45 further includes: a circulating water pump 452, which is arranged on the cooling circulation loop between the circulating water outlet of the cooling tower 451 and the circulating water inlet of the condenser 43. The circulating water pump 452 is used to pump the circulating water in the cooling tower 451 into the condenser 43.

[0062] The cooling water supply assembly 45 further includes: a peak shaving bypass 453 and a variable frequency pump 454;

[0063] The peak shaving bypass 453 is arranged between the circulating water outlet of the cooling tower 451 and the circulating water inlet of the condenser 43;

[0064] The variable frequency pump 454 is arranged on the peak shaving bypass 453, and the variable frequency pump 454 is used to adjust the flow rate of the circulating water pumped into the condenser 43.

[0065] The water inlet of the hot well 44 at the lower part of the condenser is connected to the heat exchange outlet of the heat exchange device 3 through a seventh pipeline. A second manual valve 84, a first electric gate valve 85 and a drain water pump 86 are sequentially arranged on the seventh pipeline along the flow direction of the drain water. The condenser 43 has a steam inlet, a steam outlet, a circulating water inlet and a circulating water outlet. The steam inlet of the condenser 43 is connected to the exhaust port of the low-pressure cylinder 1 through an eighth pipeline, and a fourth electric butterfly valve 46 is arranged on the eighth pipeline. The flow state of the exhaust steam in the eighth pipeline is controlled by the fourth electric butterfly valve 46. The exhaust steam discharged from the exhaust port of the low-pressure cylinder 1 enters the condenser 43 through the eighth pipeline and the steam inlet. The circulating water enters the condenser 43 through the circulating water inlet to exchange heat with the exhaust steam to cool the exhaust steam into condensed water. The condensed water is discharged from the steam outlet and enters the hot well 44 at the lower part of the condenser. After absorbing the heat of the exhaust steam, the circulating water is discharged from the circulating water outlet of the condenser 43.

[0066] In order to control the flow state of the circulating water in the peak shaving bypass 453, a fourth manual valve 455 and a third electric gate valve 456 are sequentially arranged on the peak shaving bypass 453 along the flow direction of the circulating water.

[0067] Taking a 330MW subcritical wet-cooled unit as an example, during winter heating, exhaust steam from the exhaust port of the low-pressure cylinder 1 can flow in two ways. One path of the exhaust steam flows through the first pipeline into compression device 2. After compression in compression device 2, the exhaust steam is compressed, raised in pressure and temperature to become first steam, which then enters heat exchanger 3. The maximum pressure of the compressed exhaust steam can reach 40-45 kPa. The return water from the heating network exchanges heat with the first steam in heat exchanger 3, raising its temperature. After this heat exchange, the return water enters heating device 6, where it is heated again before supplying heat to the outside. After releasing heat in heat exchanger 3, the first steam becomes drain water, which then flows through the second pipeline into the lower condenser hot well 44. The condensate and drain water mix in the lower condenser hot well 44 and are pumped by the heat recovery water pump 81 to the turbine unit heat recovery system 82.

[0068] Excess exhaust steam from another route enters condenser 43. Assuming a return flow rate of 10,000 t / h and a return water temperature of 45°C for the heating network circulating water, and taking the average heat load of 300 MW during the heating period as an example, and assuming a pressure ratio of 4 for compression device 2, when the unit load is 237.16 MW and the unit back pressure is 8.62 kPa, all the exhaust steam from low-pressure cylinder 1 enters compression device 2 for upgrading to primary steam at a pressure of 34.46 kPa. This primary steam then enters heat exchanger 3, and the fourth electric butterfly valve 46 is closed. The return water from the heating network is heated to 70.84°C in heat exchanger 3 before being supplied to the outside. When the unit load falls below 237.16 MW, the fourth electric butterfly valve 46 closes, and the unit operates purely at high back pressure. The peak heater compensates for any shortfall in high back pressure. When the unit load is higher than 237.16 MW, the fourth electric butterfly valve 46 opens, and the frequency conversion pump 454 adjusts the circulating water flow entering the condenser 43 to match the high back pressure heating. The circulating water pump 452 pumps the circulating water in the cooling tower 451 into the condenser 43. In order to control the flow state of the circulating water in the section between the circulating water outlet of the cooling tower 451 and the circulating water inlet of the condenser 43 in the cooling circulation loop, a fifth manual valve 457 and a fourth electric gate valve 458 are provided in the section between the circulating water outlet of the cooling tower 451 and the circulating water inlet of the condenser 43 in the cooling circulation loop. The circulating water pump 452 pumps the circulating water to the condenser 43. In order to adjust the flow rate of the circulating water sent to the condenser 43, a peak-shaving bypass 453 and a variable frequency pump 454 are provided. The variable frequency pump 454 pumps the circulating water from the cooling tower 451 through the peak-shaving bypass 453, the fourth manual valve 455 and the third electric gate valve 456 into the condenser 43, and adjusts the flow rate of the circulating water entering the condenser 43 by the variable frequency pump 454. The circulating water absorbs the heat released by the exhaust steam entering the condenser 43.

[0069] Taking the heat load of 368 MW during the heating period as an example, assuming the pressure ratio of the compression device 2 is 4. When the unit load is 298.89 MW, the back pressure of the unit is 11 kPa. All the exhaust steam from the low-pressure cylinder 1 enters the compression device 2. After being compressed and upgraded in quality, the pressure of the first steam becomes 44 kPa. The first steam enters the heat exchange device 3, and the fourth electric butterfly valve 46 is closed. The return water of the heat network is heated to 76.69 °C by the first steam in the heat exchange device 3 and then supplies heat to the outside. When the unit load is lower than 298.89 MW, the fourth electric butterfly valve 46 is closed, and the unit operates in a pure high back pressure mode. The insufficient heat for high back pressure heating is supplemented by the heating device 6. When the unit load is higher than 298.89 MW, the fourth electric butterfly valve 46 is opened. The circulating water pump 452 pumps the circulating water in the cooling tower 451 to the condenser 43, and the flow rate of the circulating water entering the condenser 43 is adjusted by the variable frequency pump 454 to match the high back pressure heating. The circulating water transported by the cooling tower 451 flows through the peak shaving bypass 453, the fourth manual valve 455, and the third electric gate valve 456 and enters the condenser 43. The circulating water absorbs the heat released by the exhaust steam entering the condenser 43.

[0070] For the convenience of overhauling the variable frequency pump 454, an auxiliary overhaul bypass is connected to the water inlet and outlet of the variable frequency pump 454, so that the auxiliary overhaul bypass and the variable frequency pump 454 form a parallel relationship. When overhauling the variable frequency pump 454, the circulating water can flow through the auxiliary overhaul bypass and then enter the condenser 43. In order to control the flow state of the circulating water in the auxiliary overhaul bypass, at least one sixth manual valve 459 is arranged on the auxiliary overhaul bypass.

[0071] In the high back pressure heating system provided by the present utility model, the exhaust port of the low-pressure cylinder is connected to the steam inlet of the compression device and the steam inlet of the heat exchange device. In this way, the exhaust steam discharged from the exhaust port of the low-pressure cylinder is divided into two paths. One path enters the compression device through the steam inlet of the compression device. The exhaust steam is compressed by the compression device to increase the temperature and pressure of the exhaust steam. After the temperature and pressure are increased, the exhaust steam becomes the first steam. Then, the first steam is used to heat the return water of the heat network, improving the quality and utilization rate of the exhaust steam. After the first steam loses heat, it becomes condensed water and is sent to the cooling and recovery device. The other path of the exhaust steam enters the cooling and recovery device, and the exhaust steam is cooled by the cooling and recovery device to become condensed water. The high back pressure heating system provided by the present utility model solves the problem of low utilization rate of exhaust steam in the prior art by setting a compression device to increase the pressure and temperature of the exhaust steam, and then using the exhaust steam with increased temperature and pressure to heat the return water of the heat network to supply heat to users, improving the utilization rate of the exhaust steam. At the same time, the exhaust steam discharged from the exhaust port of the low-pressure cylinder is divided into two paths, which is convenient for the unit to flexibly adjust the peak load.

[0072] The optional implementation manners of the embodiments of the present utility model have been described in detail above in conjunction with the accompanying drawings. However, the embodiments of the present utility model are not limited to the specific details in the above implementation manners. Within the scope of the technical concept of the embodiments of the present utility model, various simple modifications can be made to the technical solutions of the embodiments of the present utility model, and these simple modifications all fall within the protection scope of the embodiments of the present utility model.

[0073] In addition, it should be noted that, among the various specific technical features described in the above specific implementation manners, they can be combined in any appropriate manner without contradiction. To avoid unnecessary repetition, the embodiments of the present utility model will not separately describe various possible combination manners.

[0074] Furthermore, any combination can be made among various different implementation manners of the embodiments of the present utility model, as long as it does not violate the idea of the embodiments of the present utility model, and it should also be regarded as the content disclosed by the embodiments of the present utility model.

Claims

1. A high-backpressure heating system, which is connected to the low-pressure cylinder (1) of a steam turbine and a heat network system, is characterized in that, The high back-pressure heating system includes: A compression device (2), the steam inlet of the compression device (2) is connected to the exhaust port of the low-pressure cylinder (1), and is used to compress the exhausted steam discharged from the low-pressure cylinder (1) to generate first steam; A heat exchange device (3), having a heat exchange inlet, a heat exchange outlet, a heat exchange water inlet and a heat exchange water outlet. The heat exchange inlet of the heat exchange device (3) is connected to the steam outlet of the compression device (2). The return water of the heat supply network of the heat supply network system enters the heat exchange device (3) through the heat exchange water inlet. The heat exchange device (3) is used to utilize the waste heat of the first steam to heat the return water of the heat supply network. After the first steam loses heat, it becomes condensate water, and the condensate water flows out from the heat exchange outlet of the heat exchange device (3) and is sent to the cooling recovery device (4). The heated return water of the heat supply network is discharged from the heat exchange water outlet of the heat exchange device (3) for heat supply; The cooling recovery device (4) has a cooling inlet and a cooling return water port. The cooling inlet of the cooling recovery device (4) is connected to the exhaust port of the low-pressure cylinder (1), and the cooling return water port of the cooling recovery device (4) is connected to the heat exchange water outlet of the heat exchange device (3). The exhausted steam discharged from the low-pressure cylinder (1) enters the cooling recovery device (4) and is cooled to become condensate water for storage. The condensate water discharged from the heat exchange device (3) is recovered through the cooling recovery device (4).

2. The high back-pressure heating system according to claim 1, wherein The high back-pressure heating system further includes: a maintenance bypass (5), which is arranged between the exhaust port of the low-pressure cylinder (1) and the steam outlet of the compression device (2), and the maintenance bypass (5) is connected in parallel with the steam flow pipeline of the compression device (2).

3. The high-backpressure heating system according to claim 2, characterized in that, A first manual valve (51) is arranged on the maintenance bypass (5).

4. The high back-pressure heating system according to claim 1, characterized in that, The high back-pressure heating system further includes: a heating device (6), which is connected to the heat exchange water outlet of the heat exchange device (3) and is used to perform secondary heating on the return water of the heat supply network discharged from the heat exchange device (3).

5. The high back-pressure heat supply system according to claim 4, wherein The high back-pressure heating system further includes: a preheating heat exchange device (7), having a preheating inlet, a preheating outlet, a preheating water inlet and a preheating water outlet. The preheating inlet is connected to the exhaust port of the low-pressure cylinder (1), the preheating outlet is connected to the cooling return water port of the cooling recovery device (4), the preheating water outlet is connected to the heat exchange water inlet of the heat exchange device (3), and the return water of the heat supply network enters the preheating heat exchange device (7) from the preheating water inlet; The preheating heat exchange device (7) is used to preheat the return water of the heat supply network by using the exhausted steam. After the exhausted steam loses heat, it becomes condensate water and is discharged from the preheating outlet of the preheating heat exchange device (7) and then enters the cooling recovery device (4).

6. The high-back-pressure heat supply system according to claim 5, characterized in that, The cooling recovery device (4) includes: an air cooling tower (41) and a hot water well (42); The water inlet of the hot water well (42) serves as the cooling return water port of the cooling recovery device (4); The air cooling inlet of the air cooling tower (41) serves as the cooling inlet of the cooling recovery device (4). The air cooling inlet is connected to the exhaust port of the low-pressure cylinder (1). The air cooling outlet of the air cooling tower (41) is connected to the water inlet of the hot water well (42). The air cooling tower (41) is used to cool the exhausted steam discharged from the exhaust port of the low-pressure cylinder (1) to generate condensate water, and the condensate water enters the hot water well (42) for storage; The hot water well (42) is used to recover the condensate water discharged from the heat exchange device (3) and the condensate water discharged from the preheating heat exchange device (7).

7. The high-backpressure heating system according to claim 4, characterized in that, The cooling and recovery device (4) includes: a condenser (43), a hot well (44) at the lower part of the condenser, and a cooling water supply component (45); The cooling water supply component (45) is used to convey circulating water to the condenser (43); The condenser (43) has a steam condensation inlet, a steam condensation outlet, a circulating water inlet, and a circulating water outlet. The steam condensation inlet of the condenser (43) is connected to the exhaust port of the low-pressure cylinder (1), and the steam condensation outlet of the condenser (43) is connected to the water inlet of the hot well (44) at the lower part of the condenser. The condenser (43) uses circulating water to cool the exhausted steam discharged from the low-pressure cylinder (1) to generate condensed water; The water inlet of the hot well (44) at the lower part of the condenser is also connected to the heat exchange outlet of the heat exchange device (3), and is used to store condensed water and recover the drain water discharged from the heat exchange device (3).

8. The high back-pressure heating system according to claim 7, characterized in that, The cooling water supply component (45) includes: a cooling tower (451), and a cooling circulation loop formed between the cooling tower (451) and the condenser (43); The cooling tower (451) conveys circulating water to the condenser (43) through the cooling circulation loop. The circulating water absorbs the heat of the exhausted steam and then becomes heated circulating water. The heated circulating water flows through the cooling circulation loop to the cooling tower (451), and the heated circulating water is cooled by the cooling tower (451) to become circulating water.

9. The high back-pressure heating system according to claim 8, characterized in that, The cooling water supply component (45) further includes: a circulating water pump (452), which is arranged on the cooling circulation loop and is located between the circulating water outlet of the cooling tower (451) and the circulating water inlet of the condenser (43). The circulating water pump (452) is used to pump the circulating water in the cooling tower (451) into the condenser (43).

10. The high back-pressure heating system according to claim 9, wherein The cooling water supply component (45) further includes: a peak shaving bypass (453) and a variable frequency pump (454); The peak shaving bypass (453) is arranged between the circulating water outlet of the cooling tower (451) and the circulating water inlet of the condenser (43); The variable frequency pump (454) is arranged on the peak shaving bypass (453), and the variable frequency pump (454) is used to adjust the flow rate of the circulating water pumped into the condenser (43).

Images