A multi-stage heat supply system for increasing the waste heat of the exhaust steam of an air-cooled unit without increasing the back pressure

Abstract

The present application discloses a multi-stage heat supply system for the waste heat of the exhaust steam of an air-cooled unit without increasing the back pressure of the steam turbine, belonging to the field of thermal power generation. A multi-stage heat supply system for the waste heat of the exhaust steam of an air-cooled unit without increasing the back pressure of the steam turbine includes a steam turbine unit, which includes a high-pressure cylinder of the steam turbine, an intermediate-pressure cylinder of the steam turbine, and a low-pressure cylinder of the steam turbine connected in sequence; a generator, the shaft of which is connected to the low-pressure rotor of the low-pressure cylinder of the steam turbine; a steam booster, the inlets of which are all connected to the exhaust port of the low-pressure cylinder of the steam turbine and the motive steam of the steam booster, and the outlet of which is connected to the condenser of the steam booster, and the condensate condensed by the condenser of the steam booster enters the condensate water pipe in the air-cooled unit; a heat network circulating water system, which includes a heat network circulating water pump, and the heat network circulating water flows out from the condenser of the steam booster and is pressurized by the heat network circulating water pump. The multi-stage heat supply system for the waste heat of the exhaust steam of an air-cooled unit without increasing the back pressure of the steam turbine in the present application can avoid increasing the back pressure of the air-cooled unit and the power loss of the low-pressure cylinder of the steam turbine caused by high back pressure operation.

Description

Technical Field

[0001] The present application relates to the field of thermal power generation, and in particular to a multi-stage heating system for the waste heat of the exhaust steam of an air-cooled unit without increasing the back pressure and adding a steam turbine. Background Art

[0002] With the improvement of China's urbanization rate, the demand for urban central heating has been increasing year by year. Under the background of the "dual carbon" goal and the construction of a new power system, under the current technical conditions and power generation installed capacity structure, cogeneration is an economically feasible, safe and reliable energy utilization method to fill the demand for central heating.

[0003] Chinese Patent Invention No. 202111635275.9 discloses a flexible high-back-pressure heating system and its heating method. The high-back-pressure heating of this invention requires increasing the operating back pressure of the unit in the non-heating season so that the exhaust steam temperature is higher than the temperature of the heat network circulating water to utilize the high-back-pressure exhaust steam for heating. It can only be applied to direct air-cooled units, and the high back pressure has a certain demand for the circulating water volume of the heat network. A large circulating water volume of the heat network is required. Otherwise, only part of the exhaust steam is used for heating after increasing the back pressure, and the rest of the high-back-pressure exhaust steam is cooled by the air-cooled island above, resulting in waste of high-quality energy and poor heating economy.

[0004] Chinese Patent Invention No. 201610242548.6 discloses a heating system and regulation method for a high-back-pressure heating supporting heat press unit of a large air-cooled generator set. The unit in this invention still needs to increase the back pressure of the unit, and the problem of the high-back-pressure exhaust steam that cannot be utilized by the corresponding exhaust steam condenser and the heat press condenser after increasing the back pressure has not been solved. If the proportion of the high-back-pressure exhaust steam going to the air-cooled island is large, its heating economy will be poor.

[0005] The inventor found that the above heating systems all have different defects during the research process, specifically as follows:

[0006] 1. High-back-pressure heating system: When heating, it is necessary to increase the operating back pressure of the unit, and the exhaust steam of the low-pressure cylinder of the steam turbine is cooled by the circulating water of the heat network. When a higher heating temperature is required, the heat network heater at the heat network first station uses high-quality medium-extraction steam to continue heating the circulating water of the heat network. However, it has high requirements for the electric load and heating heat load of the unit, and it is necessary to increase the operating back pressure of the unit in the heating season.

[0007] 2. Steam ejector heating system. The steam ejector (also known as "hot press" or "steam booster") uses high-pressure steam to eject exhausted steam, enabling the exhausted steam to heat the heat network circulating water. Generally, the unit needs to increase its operating back pressure and use the high-back-pressure exhausted steam to preliminarily heat the heat network circulating water, and then use the steam ejector to reuse part of the high-back-pressure exhausted steam. Although the requirements for the heat network circulating water and the return water temperature are reduced compared with the high-back-pressure technology, there are still restrictions on the heat network circulating water volume and the return water temperature for units with small heat load demands. Specifically, assume that the heating area of two 300,000-kilowatt units is 10 million square meters, and the heating load is approximately 500 megawatts, which is a relatively large heat load for the unit. However, if the heating area of two 300,000-kilowatt units is 5 million square meters, the corresponding heating load is approximately 250 megawatts, which is a relatively small heat load for the unit. At this time, the heat network circulating water volume is correspondingly relatively small. If in an extreme situation, the heat network circulating water volume is very small and the return water temperature is high, using the steam ejector heating system will result in high heating energy consumption and thus unnecessary waste.

[0008] Therefore, there is an urgent need for a technical solution that does not require increasing the back pressure of the air-cooled unit and can solve the problem of high heating energy consumption of high-quality steam. Summary of the Invention

[0009] In order to avoid the increase in the back pressure of the air-cooled unit and the resulting high heating energy consumption of high-quality steam, the present application provides a multi-stage heating system for the waste heat of the exhausted steam of an air-cooled unit without increasing the back pressure of the steam booster.

[0010] A multi-stage heating system for the waste heat of the exhausted steam of an air-cooled unit without increasing the back pressure of the steam booster provided by the present application adopts the following technical solutions:

[0011] A multi-stage heating system for the waste heat of the exhausted steam of an air-cooled unit without increasing the back pressure of the steam booster includes:

[0012] A steam turbine unit, which includes a high-pressure cylinder of the steam turbine, an intermediate-pressure cylinder of the steam turbine, and a low-pressure cylinder of the steam turbine connected in sequence;

[0013] A generator, the shaft of which is connected to the low-pressure rotor of the low-pressure cylinder of the steam turbine;

[0014] A steam booster, the inlets of which are all connected to the exhaust port of the low-pressure cylinder of the steam turbine and the motive steam of the steam booster, and the outlet of which is connected to the condenser of the steam booster. The condensed water condensed by the condenser of the steam booster enters the condensate water pipe in the air-cooled unit;

[0015] A heat network circulating water system, which includes a heat network circulating water pump, and the heat network circulating water flows out from the condenser of the steam booster and is pressurized by the heat network circulating water pump.

[0016] By adopting the above technical solution, during the heating period operation, by using a small amount of high-quality steam as the power steam of the steam booster, part of the exhausted steam is sucked into the steam booster and pressurized and upgraded in quality. The exhaust steam of the steam booster conducts primary heating on the heat network circulating water, and then the double-cooling-source low-pressure heater is used for heating, so that the heat network circulating water can be heated and supplied to the heat users. The setting of the present application not only does not require increasing the exhaust back pressure of the steam turbine, reduces the coal consumption, improves the efficiency of the low-pressure cylinder of the steam turbine, but also avoids the heat in part of the exhausted steam being discharged into the air, resulting in waste of energy.

[0017] Optionally, it further includes an air-cooled island, which is connected to the exhaust port of the low-pressure cylinder of the steam turbine, and the condensed water condensed by the air-cooled island enters the condensed water water pipe in the air-cooled unit;

[0018] A condensate system, which includes a condensate pump, and the inlet of the condensate pump is connected to the condensed water water pipe in the air-cooled unit; the outlet of the heat network circulating water pump and the outlet of the condensate pump are jointly connected to a double-cooling-source No. 7 low-pressure heater, and the inlet of the double-cooling-source No. 7 low-pressure heater is connected to the extraction port of the low-pressure cylinder of the steam turbine. The medium entering the double-cooling-source No. 7 low-pressure heater from the heat network circulating water pump and the medium entering the double-cooling-source No. 7 low-pressure heater from the condensate pump are isolated from each other.

[0019] By adopting the above technical solution, part of the exhausted steam is condensed into condensed water through the air-cooled island and enters the double-cooling-source No. 7 low-pressure heater. After part of the exhausted steam is combined with the power steam of the steam booster to conduct primary heating on the heat network circulating water, it becomes condensed water after passing through the condenser of the steam booster and enters the double-cooling-source No. 7 low-pressure heater. The heat network circulating water after primary heating also enters the double-cooling-source No. 7 low-pressure heater, but the condensed water medium and the heat network circulating water medium do not mix. The steam coming out of the extraction port of the low-pressure cylinder of the steam turbine is input into the double-cooling-source No. 7 low-pressure heater to heat the condensed water medium and the heat network circulating water medium. For the heat supply transformation, there is no need to set up an additional heat network heater, and the heat network circulating water can be heated to the heat users by using the lower-quality steam of the steam turbine to complete the heat supply.

[0020] Optionally, the extraction ports include a seventh-stage extraction port, a sixth-stage extraction port both arranged on the low-pressure cylinder of the steam turbine, and a fifth-stage extraction port arranged on the middle-pressure cylinder of the steam turbine;

[0021] The double-cooling-source No. 7 low-pressure heater is connected to the seventh-stage extraction port, the sixth-stage extraction port is connected to a double-cooling-source No. 6 low-pressure heater, and the fifth-stage extraction port is connected to a double-cooling-source No. 5 low-pressure heater; the double-cooling-source No. 7 low-pressure heater, the double-cooling-source No. 6 low-pressure heater and the double-cooling-source No. 5 low-pressure heater have the same structure;

[0022] The hot water network circulating water and condensate both pass through the Double-Cooling-Source No. 7 Low-Pressure Heater, the Double-Cooling-Source No. 6 Low-Pressure Heater, and the Double-Cooling-Source No. 5 Low-Pressure Heater in sequence. The condensate medium entering the Double-Cooling-Source No. 6 Low-Pressure Heater and the Double-Cooling-Source No. 5 Low-Pressure Heater from the Double-Cooling-Source No. 7 Low-Pressure Heater and the hot water network circulating water medium entering the Double-Cooling-Source No. 6 Low-Pressure Heater and the Double-Cooling-Source No. 5 Low-Pressure Heater from the Double-Cooling-Source No. 7 Low-Pressure Heater are isolated from each other.

[0023] By adopting the above technical solution, using the original fifth, sixth, and seventh stage extraction and regeneration of the steam turbine to form a multi-stage heating and heat supply regeneration system, it can meet the demand adjustment of the hot water network circulating water temperature at different heating periods. For example, in the middle and late stages of heating, when the hot user's demand for the supply water temperature of the hot water network circulating water is less than the outlet temperature of the Double-Cooling-Source No. 5 Low-Pressure Heater and / or the Double-Cooling-Source No. 6 Low-Pressure Heater, the Double-Cooling-Source No. 5 Low-Pressure Heater and / or the Double-Cooling-Source No. 6 Low-Pressure Heater can be closed to make them not work, and the temperature of the hot water network circulating water can be adjusted orderly.

[0024] Optionally, a condensate and hot water network circulating water switching inlet valve is arranged on the inlet side of the Double-Cooling-Source No. 7 Low-Pressure Heater, and a condensate and hot water network circulating water switching outlet valve is arranged on the outlet side of the Double-Cooling-Source No. 5 Low-Pressure Heater.

[0025] By adopting the above technical solution, opening the condensate and hot water network circulating water switching inlet valve and the condensate and hot water network circulating water switching outlet valve can allow the condensate to enter and exit the condensate system, allow the hot water network circulating water to enter and exit the hot water network circulating water system, and enable both media to be heated by the Double-Cooling-Source Low-Pressure Heater without mixing the two media.

[0026] Optionally, a No. 5 Low-Pressure Heater circulating water bypass is arranged on one side of the Double-Cooling-Source No. 5 Low-Pressure Heater, a No. 5 Low-Pressure Heater circulating water bypass valve is arranged on the No. 5 Low-Pressure Heater circulating water bypass, and a No. 5 Low-Pressure Heater circulating water inlet stop valve is arranged on the inlet side of the Double-Cooling-Source No. 5 Low-Pressure Heater;

[0027] A No. 6 Low-Pressure Heater circulating water bypass is arranged on one side of the Double-Cooling-Source No. 6 Low-Pressure Heater, a No. 6 Low-Pressure Heater circulating water bypass valve is arranged on the No. 6 Low-Pressure Heater circulating water bypass, and a No. 6 Low-Pressure Heater circulating water inlet stop valve is arranged on the inlet side of the Double-Cooling-Source No. 6 Low-Pressure Heater.

[0028] By adopting the above technical solution, the No. 5 Low-Pressure Heater circulating water inlet stop valve can be closed, and the No. 5 Low-Pressure Heater circulating water bypass valve can be opened to allow the hot water network circulating water to pass through this bypass; the No. 6 Low-Pressure Heater circulating water inlet stop valve can be closed, and the No. 6 Low-Pressure Heater circulating water bypass valve can be opened to allow the hot water network circulating water to pass through this bypass. Furthermore, while closing several low-pressure heaters to adjust the temperature of the hot water network circulating water, the hot water network circulating water can flow forward.

[0029] Optionally, each dual-cooling-source low-pressure heater includes a housing, in which a condensate side tube group and a heat network circulating water side tube group are arranged. A steam inlet is arranged on the upper side of the housing, and a drain device is arranged on the lower side;

[0030] The condensate side tube group includes a condensate water inflow heat exchange tube bundle and a condensate water outflow heat exchange tube bundle connected at the ends. A condensate water to dual-cooling-source heat exchanger inlet communicated with the condensate water inflow heat exchange tube bundle and a condensate water to dual-cooling-source heat exchanger outlet communicated with the condensate water outflow heat exchange tube bundle are arranged on the housing;

[0031] The heat network circulating water side tube group includes a heat network circulating water inflow heat exchange tube bundle and a heat network circulating water outflow heat exchange tube bundle connected at the ends. A heat network circulating water to dual-cooling-source heat exchanger inlet communicated with the heat network circulating water inflow heat exchange tube bundle and a heat network circulating water to dual-cooling-source heat exchanger outlet communicated with the heat network circulating water outflow heat exchange tube bundle are arranged on the housing;

[0032] The steam inlet is close to the condensate water outflow heat exchange tube bundle and the heat network circulating water outflow heat exchange tube bundle, and the drain device is close to the condensate water inflow heat exchange tube bundle and the heat network circulating water inflow heat exchange tube bundle.

[0033] By adopting the above technical solution, the steam can heat the condensate water and the heat network circulating water simultaneously, and the three media will not be mixed. The temperature of the condensate water or the heat network circulating water is very low, forming a vacuum state. After the steam enters from the upper side, it condenses and releases heat, and the relatively low-temperature condensate water and heat network circulating water are heated on the outlet side. The condensed steam is discharged through the drain device.

[0034] Optionally, a seven-stage extraction steam regulating valve is arranged on the pipeline connecting the dual-cooling-source No. 7 low-pressure heater to the seven-stage extraction steam port;

[0035] A six-stage extraction steam regulating valve is arranged on the pipeline connecting the dual-cooling-source No. 6 low-pressure heater to the six-stage extraction steam port;

[0036] A five-stage extraction steam regulating valve is arranged on the pipeline connecting the dual-cooling-source No. 5 low-pressure heater to the five-stage extraction steam port;

[0037] A steam supply butterfly valve for the intermediate and low-pressure connection pipe of the steam turbine is arranged on the pipeline connecting the intermediate-pressure cylinder and the low-pressure cylinder of the steam turbine;

[0038] A low-pressure cylinder exhaust to air-cooled island isolation valve is arranged on the pipeline connecting the air-cooled island to the exhaust port.

[0039] By adopting the above technical solution, setting the extraction steam regulating valve can adjust the amount of extraction steam, setting the steam supply butterfly valve can realize the connection between the intermediate-pressure cylinder and the low-pressure cylinder of the steam turbine, and setting the isolation valve can condense the exhaust steam.

[0040] Optionally, the main steam of the steam turbine is introduced into the high-pressure cylinder of the steam turbine, and the reheated steam of the steam turbine is introduced into the intermediate-pressure cylinder of the steam turbine.

[0041] By adopting the above technical solution, the main steam of the steam turbine is used to realize the work of the high-pressure cylinder of the steam turbine, and the reheated steam is used to realize the work of the intermediate-pressure cylinder of the steam turbine.

[0042] Optionally, the condensate water flowing into the heat exchange tube bundle and the condensate water flowing out of the heat exchange tube bundle are symmetrically arranged with respect to the central longitudinal section of the shell, and the connection between the two forms an arc; the heat network circulating water flowing into the heat exchange tube bundle and the heat network circulating water flowing out of the heat exchange tube bundle are symmetrically arranged with respect to the central longitudinal section of the shell, and the connection between the two forms an arc.

[0043] By adopting the above technical solution, the isolation setting of the heat exchange tube bundle inlet and outlet can be achieved.

[0044] In summary, the present application includes at least one of the following beneficial technical effects:

[0045] 1. Utilize the original fifth, sixth, and seventh stage extraction steam of the steam turbine for regenerative heating of the heat network circulating water.

[0046] 2. Adopt a three-stage regenerative system to significantly reduce the problem of high heating energy consumption, and can significantly reduce the quality of the heat source steam compared with the traditional heating method.

[0047] 3. During the heating period operation, the steam booster uses part of the exhaust steam from the low-pressure cylinder to conduct primary heating of the heat network, but there is no need to increase the back pressure of the low-pressure cylinder of the steam turbine. At the same time, part of the waste heat of the exhaust steam from the low-pressure cylinder is reduced from being discharged into the air, resulting in energy waste. Utilize the dual-cooling source low-pressure heater, both the condensate water and the heat network circulating water are put into operation, and the heat network circulating water can be heated to the heat user by using the regenerative system of the steam turbine.

[0048] 4. Utilize the sequential switching of the No. 5 and No. 6 dual-cooling source low-pressure heaters to meet the demand adjustment of the temperature of the heat network circulating water at different heating periods.

[0049] 5. No additional heat network heater needs to be set for the heating transformation. During the non-heating period operation, the condensate water can be introduced into the heat network circulating water side of the dual-cooling source low-pressure heater to increase the heat exchange area and reduce the terminal difference of the low-pressure heater.

[0050] 6. Provide a dual-cooling low-pressure heater that can heat both the condensate water and the heat network circulating water at the same time, and the two cooling source media do not mix. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a schematic diagram of the overall structure of an air-cooled unit non-backpressure increasing steam turbine waste heat multi-stage heating system reflecting the present application;

[0052] Figure 2It is a schematic structural diagram of a dual-cooling-source low-pressure heater of a multi-stage heat supply system for waste heat of the exhaust steam of an air-cooled unit without increasing the back pressure, which embodies the present application;

[0053] Figure 3 Along Figure 2 Side view along line A-A in the middle.

[0054] Explanation of reference numerals:

[0055] 1. Steam turbine unit; 11. High-pressure cylinder of steam turbine; 111. Main steam of steam turbine; 12. Intermediate-pressure cylinder of steam turbine; 121. Reheat steam of steam turbine; 122. Heat supply butterfly valve for intermediate-low pressure connecting pipe of steam turbine; 13. Low-pressure cylinder of steam turbine; 131. Isolation valve for exhaust steam from low-pressure cylinder to air-cooled island;

[0056] 2. Generator;

[0057] 3. Air-cooled island;

[0058] 4. Condensate system; 41. Condensate pump; 411. Switching inlet valve for condensate and heat network circulating water; 412. Switching outlet valve for condensate and heat network circulating water; 42. Dual-cooling-source No. 7 low-pressure heater; 421. Regulating valve for extraction steam of the seventh stage; 43. Dual-cooling-source No. 6 low-pressure heater; 431. Regulating valve for extraction steam of the sixth stage; 432. Shut-off valve for inlet of circulating water of No. 6 low-pressure heater; 433. Bypass valve for circulating water of No. 6 low-pressure heater; 44. Dual-cooling-source No. 5 low-pressure heater; 441. Regulating valve for extraction steam of the fifth stage; 442. Shut-off valve for inlet of circulating water of No. 5 low-pressure heater; 443. Bypass valve for circulating water of No. 5 low-pressure heater;

[0059] 5. Heat network circulating water system; 51. Condenser of steam augmenter; 52. Heat network circulating water pump;

[0060] 6. Steam augmenter; 61. Power steam of steam augmenter; 62. Cut-off valve for exhaust steam from low-pressure cylinder of steam turbine to steam augmenter;

[0061] 7. Steam inlet; 71. Drainage device;

[0062] 81. Condensate flowing into heat exchange tube bundle; 82. Condensate flowing out of heat exchange tube bundle; 83. Inlet of condensate to dual-cooling-source heat exchanger; 84. Outlet of condensate to dual-cooling-source heat exchanger; 91. Heat network circulating water flowing into heat exchange tube bundle; 92. Heat network circulating water flowing out of heat exchange tube bundle; 93. Inlet of heat network circulating water to dual-cooling-source heat exchanger; 94. Outlet of heat network circulating water to dual-cooling-source heat exchanger. Specific implementation mode

[0063] The following will further elaborate on the present application in conjunction with the attached Figures 1-3 drawings.

[0064] An embodiment of the present application discloses a multi-stage heating system for the waste heat of the exhaust steam of an air-cooled unit without increasing the back pressure of the steam turbine.

[0065] At present, during the heating season, the back pressure of a direct air-cooled unit during operation is about 10 kPa, and the corresponding low-pressure exhaust steam temperature is about 45 °C. However, the return water temperature of the circulating water in the urban heating network is generally about 50 - 60 °C. If the exhaust steam back pressure of the steam turbine is not artificially increased, the waste heat of the exhaust steam cannot be directly utilized for heating.

[0066] Directly condensing the exhaust steam into condensate through the air-cooled island will discharge the heat in the exhaust steam into the air, resulting in waste of heat. However, artificially increasing the back pressure will increase the overall exhaust steam of the low-pressure cylinder of the steam turbine, resulting in more coal consumption required for the same power generation, and reducing the efficiency of the low-pressure cylinder of the steam turbine.

[0067] In this application, a small amount of high-quality steam is used as the power steam of the steam booster. Part of the exhaust steam is inhaled into the steam booster and pressurized and upgraded. The exhaust steam of the steam booster is used for primary heating of the circulating water in the heating network. The heat of the exhaust steam is fully utilized, and the consumption of high-quality steam is greatly reduced, thus achieving the effect of energy saving.

[0068] Refer to Figure 1 , a multi-stage heating system for the waste heat of the exhaust steam of an air-cooled unit without increasing the back pressure of the steam turbine includes a steam turbine unit 1, a generator 2, a condensate system 4, and a steam booster 6. The steam turbine unit 1 includes a steam turbine high-pressure cylinder 11, a steam turbine intermediate-pressure cylinder 12, and a steam turbine low-pressure cylinder 13 connected in sequence. The connecting shaft of the steam turbine low-pressure cylinder 13 drives the generator 2 to generate electricity.

[0069] The main steam 111 of the steam turbine enters the steam turbine high-pressure cylinder 11. After the steam turbine high-pressure cylinder 11 completes work, the steam is continuously heated by the reheater. The reheated steam 121 of the steam turbine enters the steam turbine intermediate-pressure cylinder 12. One path of the steam in the steam turbine intermediate-pressure cylinder 12 enters the steam turbine low-pressure cylinder 13 through the heat supply butterfly valve 122 of the steam turbine intermediate-low pressure connecting pipe to continue working.

[0070] The exhaust port of the steam turbine low-pressure cylinder 13 is used for discharging the exhaust steam. The exhaust port of the steam turbine low-pressure cylinder 13 and the power steam 61 of the steam booster are both connected to the inlet of the steam booster 6, where the power steam 61 of the steam booster is high-quality steam from each cylinder. A stop valve 62 from the exhaust steam of the steam turbine low-pressure cylinder to the steam booster is provided on the branch where the steam booster 6 is located to control the on-off of the branch.

[0071] The exhaust port of the steam turbine low-pressure cylinder 13 is also connected to an air-cooled island 3 for condensing part of the exhaust steam into condensate.

[0072] Part of the exhaust steam discharged from the steam turbine low-pressure cylinder 13 enters the air-cooled island 3 to be condensed into condensate, and the other part enters the steam booster 6 and preheats the circulating water in the heating network together with the power steam 61 of the steam booster. The outlet of the steam booster 6 is connected to the condenser 51 of the steam booster.

[0073] The condensate system 4 includes pipelines, a condensate pump 41 located on the pipelines, and a plurality of double-cooling-source low-pressure heaters with the same structure.

[0074] The condensate condensed by the steam extraction condenser 51 of the steam addition turbine enters the condensate water pipe in the air-cooled unit, and the condensate condensed by the air-cooled island 3 also enters the condensate water pipe in the air-cooled unit. The two-way condensate water enters the condensate pump 41 and is pressurized.

[0075] The double-cooling-source low-pressure heaters include a double-cooling-source No. 7 low-pressure heater 42, a double-cooling-source No. 6 low-pressure heater 43, and a double-cooling-source No. 5 low-pressure heater 44, which are sequentially arranged on the pipeline starting from the outlet of the condensate pump 41.

[0076] The multi-stage heat supply system for the waste heat of the exhaust steam of the steam addition turbine without increasing the back pressure of the air-cooled unit further includes a heat network circulating water system 5. The heat network circulating water system 5 includes pipelines and a heat network circulating water pump 52 located on the pipelines.

[0077] The outlet of the heat network circulating water pump 52 and the outlet of the condensate pump 41 of the condensate system are jointly and sequentially connected to the double-cooling-source No. 7 low-pressure heater 42, the double-cooling-source No. 6 low-pressure heater 43, and the double-cooling-source No. 5 low-pressure heater 44. That is, each double-cooling-source low-pressure heater can heat the heat network circulating water and the condensate at the same time, so additional heat network heaters do not need to be set up for the heat supply transformation.

[0078] The medium entering each double-cooling-source low-pressure heater from the heat network circulating water pump 52 and the medium entering the double-cooling-source low-pressure heater from the condensate pump 41 are isolated from each other, that is, the two do not mix.

[0079] Among them, the steam quality at the five-stage extraction steam port is higher than that at the six-stage extraction steam port, and the steam quality at the six-stage extraction steam port is higher than that at the seven-stage steam port.

[0080] Among them, the medium entering from the pipeline of the condensate system 4 is condensate water, and the medium entering from the pipeline of the heat network circulating water system 5 is heat network circulating water.

[0081] The structures of each double-cooling-source low-pressure heater are introduced in detail below.

[0082] Referring to Figure 2 and Figure 3 , Figure 3 shows the placement state when the double-cooling-source low-pressure heater is working. Each double-cooling-source low-pressure heater includes a hollow shell. The shell can be any hollow structure such as a cylindrical shape or a column shape. In this embodiment, a cylinder is taken as an example. A condensate water side pipe group and a heat network circulating water side pipe group are arranged in the shell. A steam inlet 7 is arranged on the upper side of the shell, and a drain device 71 for discharging the water condensed from the steam is arranged on the lower side of the shell.

[0083] The condensate side tube group includes a condensate inlet heat exchange tube bundle 81 located on the lower side of the shell and a condensate outlet heat exchange tube bundle 82 located on the upper side of the shell. A condensate to dual-cooling source heat exchanger inlet 83 communicating with the condensate inlet heat exchange tube bundle 81 is provided on the lower side of the shell, and a condensate to dual-cooling source heat exchanger outlet 84 communicating with the condensate outlet heat exchange tube bundle 82 is provided on the upper side.

[0084] Among them, one condensate inlet heat exchange tube bundle 81 and one condensate outlet heat exchange tube bundle 82 form a connected U-shaped tube. The condensate side tube group includes multiple U-shaped tubes, and the cross-section formed by the multiple U-shaped tubes is semi-circular. The condensate side tube group occupies half of the cavity of the shell.

[0085] The heat network circulating water side tube group includes a heat network circulating water inlet heat exchange tube bundle 91 located on the lower side of the shell and a heat network circulating water outlet heat exchange tube bundle 92 located on the upper side of the shell. A heat network circulating water to dual-cooling source heat exchanger inlet 93 communicating with the heat network circulating water inlet heat exchange tube bundle 91 is provided on the lower side of the shell, and a heat network circulating water to dual-cooling source heat exchanger outlet 94 communicating with the heat network circulating water outlet heat exchange tube bundle 92 is provided on the upper side.

[0086] The steam inlet 7 is close to the outlet of the condensate outlet heat exchange tube bundle 82, and the drain device 71 is close to the inlet of the condensate inlet heat exchange tube bundle 81. The steam inlet 7 is also close to the outlet of the heat network circulating water outlet heat exchange tube bundle 92, and the drain device 71 is also close to the inlet of the heat network circulating water inlet heat exchange tube bundle 91. Setting the steam inlet 7 on the upper side can prevent the water condensed from the steam from mixing with the steam under the action of gravity to form vibration. The temperature of the condensate or the heat network circulating water is very low, forming a vacuum state. When the steam enters, it condenses and releases heat, which can heat the condensate and the heat network circulating water.

[0087] Among them, one heat network circulating water inlet heat exchange tube bundle 91 and one heat network circulating water outlet heat exchange tube bundle 92 form a connected U-shaped tube. The heat network circulating water side tube group includes multiple U-shaped tubes, and the cross-section formed by the multiple U-shaped tubes is semi-circular. The heat network circulating water side tube group occupies the other half of the cavity of the shell.

[0088] Refer to Figure 1 and Figure 2 , a condensate and heat network circulating water switching inlet valve 411 is provided on the inlet side of the dual-cooling source No. 7 low-pressure heater 42, and a condensate and heat network circulating water switching outlet valve 412 is provided on the outlet side of the dual-cooling source No. 5 low-pressure heater 44.

[0089] In the non-heating season, the heat network circulating water system stops operating, and the condensate can operate in the condensate system 4. After being pressurized by the condensate pump 41, the condensate enters the dual-cooling source No. 7 low-pressure heater 42, the dual-cooling source No. 6 low-pressure heater 43, and the dual-cooling source No. 5 low-pressure heater 44 in sequence, and then enters the remaining regenerative system to be heated continuously after being heated.

[0090] In order to make full use of the heat transfer area of each dual-cooling-source low-pressure heater and reduce the heat transfer end difference of the low-pressure heater, when the heat network circulating water system is out of operation, the condensate can also be connected to the heat network circulating water system 5. The condensate and heat network circulating water switching inlet valve 411 and the condensate and heat network circulating water switching outlet valve 412 are both opened. The condensate enters simultaneously from the condensate side system and the heat network circulating water side system of the dual-cooling-source low-pressure heater, and is heated successively by the dual-cooling-source No. 7 low-pressure heater 42, the dual-cooling-source No. 6 low-pressure heater 43, and the dual-cooling-source No. 5 low-pressure heater 44, and then enters the remaining regenerative system to be heated continuously. Since the condensate enters both systems simultaneously, the heat transfer area is increased, so the heat transfer end difference of the dual-cooling-source low-pressure heater can be greatly reduced, and the energy consumption of the regenerative system can be reduced.

[0091] The dual-cooling-source No. 7 low-pressure heater 42 is connected to the seventh extraction steam port through the seventh extraction steam regulating valve 421 to achieve on-off; the dual-cooling-source No. 6 low-pressure heater 43 is connected to the sixth extraction steam port through the sixth extraction steam regulating valve 431 to achieve on-off; the dual-cooling-source No. 5 low-pressure heater 44 is connected to the fifth extraction steam port through the fifth extraction steam regulating valve 441 to achieve on-off.

[0092] The exhaust port and the air-cooled island 3 are connected through the low-pressure cylinder exhaust to air-cooled island isolation valve 131 to achieve on-off.

[0093] A No. 5 low-pressure heater circulating water bypass is provided on one side of the dual-cooling-source No. 5 low-pressure heater 44. A No. 5 low-pressure heater circulating water bypass valve 443 is provided on this bypass. A No. 5 low-pressure heater circulating water inlet stop valve 442 is provided between the connection of the inlet side of the dual-cooling-source No. 5 low-pressure heater 44 and the inlet side of this bypass and the dual-cooling-source No. 6 low-pressure heater 43.

[0094] A No. 6 low-pressure heater circulating water bypass is provided on one side of the dual-cooling-source No. 6 low-pressure heater 43. A No. 6 low-pressure heater circulating water bypass valve 433 is provided on this bypass. A No. 6 low-pressure heater circulating water inlet stop valve 432 is provided between the connection of the inlet side of the dual-cooling-source No. 6 low-pressure heater 43 and the inlet side of this bypass and the dual-cooling-source No. 6 low-pressure heater 43.

[0095] During the heating season, both the condensate and the heat network circulating water are put into operation. Among them, the condensate is pressurized by the condensate pump 41 and then enters the dual-cooling-source No. 7 low-pressure heater 42, the dual-cooling-source No. 6 low-pressure heater 43, and the dual-cooling-source No. 5 low-pressure heater 44 successively to be heated and then enters the remaining regenerative system to be heated continuously. The heat network circulating water is pressurized by the heat network circulating water pump 52 and then also enters the dual-cooling-source No. 7 low-pressure heater 42, the dual-cooling-source No. 6 low-pressure heater 43, and the dual-cooling-source No. 5 low-pressure heater 44 successively to be heated and then is supplied to users for heating. The condensate and the heat network circulating water entering both sides of each dual-cooling-source low-pressure heater do not mix, operate independently, and do not require an additional heat network heater.

[0096] Part of the exhaust steam of the low-pressure cylinder 13 of the steam turbine under normal back pressure enters the steam booster 6. The exhausted steam after being upgraded in quality and pressurized by the motive steam 61 of the steam booster enters the condenser 51 of the steam booster. The heat network circulating water enters the condenser 51 of the steam booster for primary heating, and then the heat network circulating water enters the heat network circulating water pump 52, is pressurized, and then enters the double-cooling-source No. 7 low-pressure heater 42, the double-cooling-source No. 6 low-pressure heater 43, and the double-cooling-source No. 5 low-pressure heater 44 in sequence to be heated and supplied to heat users. The condensate water and the heat network circulating water entering both sides of each double-cooling-source low-pressure heater do not mix, operate independently, and there is no need to additionally set a heat network heater.

[0097] At the end of the heating period, when the heat user's demand for the supply temperature of the heat network circulating water is lower than the outlet temperature of the double-cooling-source No. 5 low-pressure heater 44, the inlet stop valve 442 of the circulating water of the No. 5 low-pressure heater can be closed, and the bypass valve 443 of the circulating water of the No. 5 low-pressure heater can be opened to make the double-cooling-source No. 5 low-pressure heater 44 not heat the heat network circulating water, so as to reduce the supply temperature of the heat network circulating water. When the heat user's demand for the supply temperature of the heat network circulating water is still lower than the outlet temperature of the double-cooling-source No. 6 low-pressure heater 43, the inlet stop valve 432 of the circulating water of the No. 6 low-pressure heater can be closed, and the bypass valve 433 of the circulating water of the No. 6 low-pressure heater can be opened to make the double-cooling-source No. 6 low-pressure heater 43 not heat the heat network circulating water, and orderly adjust the temperature of the heat network circulating water.

[0098] The above are all the preferred embodiments of this application. The protection scope of this application is not limited by this. Therefore, all equivalent changes made according to the structure, shape, and principle of this application should be covered within the protection scope of this application.

Claims

1. An air-cooled unit non-backpressure-increasing steam turbine exhaust waste heat multi-stage heating system, characterized in that: It includes: A steam turbine unit (1), which includes a steam turbine high-pressure cylinder (11), a steam turbine intermediate-pressure cylinder (12) and a steam turbine low-pressure cylinder (13) connected in sequence; A generator (2), whose shaft is connected to the low-pressure rotor of the steam turbine low-pressure cylinder (13); An augmenting steam turbine (6), whose inlet is connected to the exhaust port of the steam turbine low-pressure cylinder (13) and the augmenting steam turbine motive steam (61), and whose outlet is connected to the augmenting steam turbine condenser (51), and the condensate condensed by the augmenting steam turbine condenser (51) enters the condensate water pipe in the air-cooled unit; A heat network circulating water system (5), which includes a heat network circulating water pump (52), and the heat network circulating water flows out from the augmenting steam turbine condenser (51) and is pressurized by the heat network circulating water pump (52); It also includes an air-cooled island (3), which is connected to the exhaust port of the steam turbine low-pressure cylinder (13), and the condensate condensed by the air-cooled island (3) enters the condensate water pipe in the air-cooled unit; A condensate water system (4), which includes a condensate water pump (41), and the inlet of the condensate water pump (41) is connected to the condensate water pipe in the air-cooled unit; the outlet of the heat network circulating water pump (52) and the outlet of the condensate water pump (41) are jointly connected to a dual-cooling-source No. 7 low-pressure heater (42), and the inlet of the dual-cooling-source No. 7 low-pressure heater (42) is connected to the extraction port of the steam turbine low-pressure cylinder (13), and the medium entering the dual-cooling-source No. 7 low-pressure heater (42) from the heat network circulating water pump (52) and the medium entering the dual-cooling-source No. 7 low-pressure heater (42) from the condensate water pump (41) are isolated from each other; The extraction ports of the steam turbine low-pressure cylinder (13) include a seventh-stage extraction port and a sixth-stage extraction port provided on the steam turbine low-pressure cylinder (13), and a fifth-stage extraction port is also provided on the steam turbine intermediate-pressure cylinder (12); The dual-cooling-source No. 7 low-pressure heater (42) is connected to the seventh-stage extraction port, the sixth-stage extraction port is connected to a dual-cooling-source No. 6 low-pressure heater (43), and the fifth-stage extraction port is connected to a dual-cooling-source No. 5 low-pressure heater (44); the dual-cooling-source No. 7 low-pressure heater (42), the dual-cooling-source No. 6 low-pressure heater (43) and the dual-cooling-source No. 5 low-pressure heater (44) have the same structure; Both the heat network circulating water and the condensate water sequentially pass through the dual-cooling-source No. 7 low-pressure heater (42), the dual-cooling-source No. 6 low-pressure heater (43) and the dual-cooling-source No. 5 low-pressure heater (44), and the condensate water medium entering the dual-cooling-source No. 6 low-pressure heater (43) and the dual-cooling-source No. 5 low-pressure heater (44) from the dual-cooling-source No. 7 low-pressure heater (42) and the heat network circulating water medium entering the dual-cooling-source No. 6 low-pressure heater (43) and the dual-cooling-source No. 5 low-pressure heater (44) from the dual-cooling-source No. 7 low-pressure heater (42) are isolated from each other; A condensate water and heat network circulating water switching inlet valve (411) is provided on the inlet side of the dual-cooling-source No. 7 low-pressure heater (42), and a condensate water and heat network circulating water switching outlet valve (412) is provided on the outlet side of the dual-cooling-source No. 5 low-pressure heater (44).

2. A multi - stage heat supply system for the waste heat of the exhaust steam of an air - cooled unit without increasing the back pressure, according to claim 1, characterized in that: On one side of the double - cold - source No. 5 low - pressure heater (44), there is a bypass for the circulating water of the No. 5 low - pressure heater. A bypass valve (443) for the circulating water of the No. 5 low - pressure heater is provided on the bypass for the circulating water of the No. 5 low - pressure heater. An inlet stop valve (442) for the circulating water of the No. 5 low - pressure heater is provided on the inlet side of the double - cold - source No. 5 low - pressure heater (44); On one side of the double - cold - source No. 6 low - pressure heater (43), there is a bypass for the circulating water of the No. 6 low - pressure heater. A bypass valve (433) for the circulating water of the No. 6 low - pressure heater is provided on the bypass for the circulating water of the No. 6 low - pressure heater. An inlet stop valve (432) for the circulating water of the No. 6 low - pressure heater is provided on the inlet side of the double - cold - source No. 6 low - pressure heater (43).

3. A multi - stage heat supply system for the waste heat of the exhaust steam of an air - cooled unit without increasing the back pressure, according to claim 1 or 2, characterized in that: Each double - cold - source low - pressure heater includes a shell. A condensate side tube group and a heat network circulating water side tube group are arranged in the shell. A steam inlet (7) is provided on the upper side of the shell, and a drain device (71) is provided on the lower side; The condensate side tube group includes a condensate water inflow heat exchange tube bundle (81) and a condensate water outflow heat exchange tube bundle (82) connected at the ends. A condensate water to double - cold - source heat exchanger inlet (83) communicated with the condensate water inflow heat exchange tube bundle (81) and a condensate water to double - cold - source heat exchanger outlet (84) communicated with the condensate water outflow heat exchange tube bundle (82) are provided on the shell; The heat network circulating water side tube group includes a heat network circulating water inflow heat exchange tube bundle (91) and a heat network circulating water outflow heat exchange tube bundle (92) connected at the ends. A heat network circulating water to double - cold - source heat exchanger inlet (93) communicated with the heat network circulating water inflow heat exchange tube bundle (91) and a heat network circulating water to double - cold - source heat exchanger outlet (94) communicated with the heat network circulating water outflow heat exchange tube bundle (92) are provided on the shell; The steam inlet (7) is close to the condensate water outflow heat exchange tube bundle (82) and the heat network circulating water outflow heat exchange tube bundle (92), and the drain device (71) is close to the condensate water inflow heat exchange tube bundle (81) and the heat network circulating water inflow heat exchange tube bundle (91).

4. A multi - stage heat supply system for the waste heat of the exhaust steam of an air - cooled unit without increasing the back pressure, according to claim 1 or 2, characterized in that: A seven - stage extraction steam regulating valve (421) is provided on the pipeline connecting the double - cold - source No. 7 low - pressure heater (42) to the seven - stage extraction steam port; A six - stage extraction steam regulating valve (431) is provided on the pipeline connecting the double - cold - source No. 6 low - pressure heater (43) to the six - stage extraction steam port; A five - stage extraction steam regulating valve (441) is provided on the pipeline connecting the double - cold - source No. 5 low - pressure heater (44) to the five - stage extraction steam port; A heat supply butterfly valve (122) for the intermediate - low - pressure connection pipe of the steam turbine is provided on the pipeline connecting the intermediate - pressure cylinder (12) and the low - pressure cylinder (13) of the steam turbine; An isolation valve (131) for the exhaust steam from the low - pressure cylinder to the air - cooled island is provided on the pipeline connecting the air - cooled island (3) to the exhaust steam port.

5. A multi - stage heat supply system for the waste heat of the exhaust steam of an air - cooled unit's non - rising back - pressure steam augmenter according to claim 1, characterized in that: The main steam of the steam turbine (111) is introduced into the high - pressure cylinder (11) of the steam turbine, and the reheated steam of the steam turbine (121) is introduced into the intermediate - pressure cylinder (12) of the steam turbine.

6. A multi - stage heat supply system for the waste heat of the exhaust steam of an air - cooled unit's non - rising back - pressure steam augmenter according to claim 3, characterized in that: The condensate water flowing into the heat exchange tube bundle (81) and the condensate water flowing out of the heat exchange tube bundle (82) are symmetrically arranged with respect to the central longitudinal section of the housing, and the connection between the two forms an arc; the heat network circulating water flowing into the heat exchange tube bundle (91) and the heat network circulating water flowing out of the heat exchange tube bundle (92) are symmetrically arranged with respect to the central longitudinal section of the housing, and the connection between the two forms an arc.

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