A two-stage deaerating regenerative system for 300MW and above grade steam turbine generator unit

Abstract

The utility model discloses a two -stage deoxygenization regenerative system of 300MW above grade steam turbine generator unit, including the high -pressure heater group, deaerator and low -pressure heater group that connect in order from high to low according to pressure, and low -pressure heater group includes at least one mixed type low -pressure heater, and mixed type low -pressure heater is communicated with condenser through shaft seal heater. The system of the utility model has the advantages of simple system, high efficiency, low heat rate, energy -conserving and emission -reducing, high safety, adapt to fast variable load, low failure rate, effectively reduce operation maintenance, long -term stable operation in life period, long -term operation overall economy is high, the price of equipment and supporting instrument valve is low, saves space, saves civil engineering cost etc. to solve the problem that the regenerative system of the prior art using surface heater can not solve the problem of depth peak shaving, fast variable load and wide load high -efficient operation well, and can solve the problems of large cold source loss of surface heater, low thermal efficiency and the like.

Description

Technical Field

[0001] This utility model relates to the field of steam turbine power generation technology, and more specifically, to a two-stage deaeration and regeneration system for steam turbine generator sets of 300MW or above. Background Technology

[0002] Currently, the turbine regenerative systems used in 300MW~1000MW generator units both domestically and internationally mainly consist of high-pressure heaters. Figure 1 The first high-pressure heater 1, the second high-pressure heater 2, the third high-pressure heater 3, and the fourth high-pressure heater 4), and the deaerator ( Figure 1 (Section 5) and low-pressure heater ( Figure 1 For details on typical 1000MW-class generator unit regenerative system engineering diagrams, please refer to the regenerative equipment (items 6-11). Figure 1 .

[0003] In modern power plant turbine regenerative systems, typically only the deaerator is a mixing heater, while the high-pressure and low-pressure heaters are surface heaters. Figure 1 As shown.

[0004] For regenerative systems using surface heaters, especially surface low-pressure heater systems, the main disadvantages are as follows: (1) There is a difference in the end points, which cannot make the maximum use of the energy potential of the heating steam, and the thermal economy is worse than that of the mixing heater.

[0005] In surface heaters, heating steam heats feedwater through a metal wall. Due to economic considerations, the heat transfer surface area cannot be large enough, and thermal resistance exists, meaning the feedwater generally cannot be heated to its saturation temperature at the heating steam pressure. The difference between the saturation temperature corresponding to the heating steam pressure and the feedwater outlet temperature is typically called the heat transfer differential of the surface heater. Because of this heat transfer differential, the work capacity of the heating steam is reduced, thus surface heaters are less thermally efficient than mixing heaters.

[0006] (2) The system that adopts hydrophobic stepwise gravity flow has large cold source loss and poor thermal economy.

[0007] Surface heaters contain condensate, which is typically discharged by gravity through the pressure differences between each heater stage. The condensate flows sequentially into the steam-side space of the lower-pressure heaters, with the condensate from the last low-pressure heater flowing into the condenser. In this system, the higher-pressure, higher-enthalpy condensate releases heat as it flows into the steam-side space of the lower-pressure heaters, displacing some of the lower-pressure regenerative extraction steam. To maintain a constant turbine output power, this inevitably leads to reduced extraction steam work and increased condensation steam work, resulting in greater cooling losses. In particular, when the condensate flows into the condenser, it directly increases cooling losses.

[0008] (3) The combined system of hydrophobic step-by-step gravity flow and hydrophobic cooler improves thermal economy, but increases system equipment and complicates system operation and control.

[0009] Currently, a combined system of condensate coolers and gravity-flow condensate is commonly used. Before flowing into the next stage heater, the condensate passes through a condensate cooler, where it is appropriately cooled by the main condensate before flowing into the next stage heater. This condensate system reduces the temperature and enthalpy of the condensate exiting the cooler, decreasing the steam extraction and exhaust of the heater receiving the condensate, thus reducing power loss in this area. While this system improves the unit's thermal economy compared to a pure gravity-flow condensate system, the overall thermal economy remains relatively low. Furthermore, the increased number of system components complicates system operation and control.

[0010] (4) The system adopts a combination of partial condensate stage gravity flow and condensate cooler, and additionally uses a condensate pump to send condensate into the main condensate pipe at the outlet of the heater. The thermal economy is greatly improved, but the system equipment increases, the system operation and control become more complicated, the investment increases, and the reliability decreases.

[0011] Using additional condensate pumps to deliver condensate to the main condensate piping system at the outlet of the heater stage is an effective measure to overcome the reduced thermal efficiency of surface heaters due to the gravity flow of condensate at each stage. For connection systems with added condensate pumps, their thermal efficiency is second only to mixed heater systems. However, in such systems, two condensate pumps must be installed for each heater (one as a backup), increasing equipment investment and maintenance costs, raising plant power consumption, and making the system more complex and reducing operational reliability.

[0012] (5) The condensate bypass of the low-pressure heater is often composed of a combination of large and small bypasses. Such an arrangement leads to a complex system with many valves, high cost, high failure rate, complicated operation and maintenance, and low economic efficiency.

[0013] To avoid overloading the deaerator, the downstream equipment of the low-pressure heaters, and deteriorating the deaeration effect, the second and third stages of low-pressure heaters adjacent to the deaerator cannot be disconnected simultaneously. Therefore, the condensate bypass of these low-pressure heaters needs to adopt a small bypass system. In engineering practice, the last stage or the last two stages of low-pressure heaters also require a small bypass system due to the structural influence of the turbine's low-pressure section.

[0014] (6) Surface-type low-pressure heaters have a relatively short service life.

[0015] Because the condensate from the condenser is of poor quality (generally with a pH value not lower than 9.5 and high levels of dissolved oxygen and various impurities), copper or stainless steel tubes are used for the surface-type low-pressure heater heat exchange tubes. However, due to the water quality, steel tubes, especially copper tubes, are prone to corrosion and leakage. When heat exchange tubes are damaged, temporary protective plugging is usually used. This reduces the effective heat exchange area, increases water resistance, and increases the feedwater temperature difference, affecting heater performance and reducing unit thermal efficiency. When the plugging rate is too high, the equipment can no longer meet the heat exchange requirements, and therefore needs to be replaced.

[0016] (7) Surface-type low-pressure heater equipment is prone to scaling on the heat exchange tube walls due to the poor quality of the condensate from the condenser. As the operating time increases, the thermal resistance gradually increases and the heat exchange effect gradually decreases. This will affect the steam extraction rate and the performance of this equipment, and will also affect adjacent equipment, affecting the overall efficiency of the unit and reducing its economic efficiency.

[0017] (8) Due to the poor water quality of the low-pressure heater, copper tubes or stainless steel tubes are usually selected as heat exchange tube materials. At present, stainless steel tubes are usually selected, which are expensive, have low thermal conductivity, and require 20% to 30% more heat transfer area than carbon steel tubes for the same heat exchange, resulting in poor economic efficiency.

[0018] (9) The failure rate of surface-type low-pressure heaters is relatively high, mainly due to insufficient net positive suction head (NPSH) of the condensate pump, unstable operating conditions, accidents such as heat exchange tube rupture, and manufacturing defects. These issues can lead to fault disconnection or shutdown, affecting the normal operation of subsequent deaerator equipment and impacting the unit's normal operation and economic efficiency.

[0019] (10) During the flow of the medium in the shell and tube side of the surface heater, pressure loss occurs due to friction and structural reasons. If the heat exchange tube leaks and is blocked, the pressure loss will increase further. Excessive pressure loss will increase the power consumption of the feedwater pump or condensate pump, resulting in insufficient energy saving and affecting the economic efficiency of the unit.

[0020] (11) Surface heaters, especially vertical structures, have a small condensate volume; for horizontal structures, the water level should not be too high because a high water level will submerge part of the heat exchange tubes and reduce heat exchange efficiency. Therefore, in general, the condensate volume is small, making water level control difficult and prone to excessively high or low water levels, which can lead to a chain reaction and affect the stable and safe operation of the system and other adjacent equipment.

[0021] (12) Surface heaters require shell or core removal, resulting in a large installation space requirement. Moreover, this operation is mostly performed when the heat exchange tube is ruptured, causing excessive blockage and the heat exchange performance does not meet the requirements. This operation will inevitably shut down the equipment, and the remanufacturing of the tube system and other parts and the replacement cycle are long, resulting in increased time and basic investment costs. In addition, the shutdown during this period will affect the normal operation of adjacent equipment, a series of subsequent equipment, and the normal operation and economy of the entire unit.

[0022] (13) Surface heaters, especially those with tube sheet structures, have strict requirements for temperature rise and fall and cannot adapt to the rapid load change of the unit.

[0023] (14) Surface heaters, when deep peak shaving, the pressure difference between adjacent heaters is too small under low load, which will lead to poor drainage and is not conducive to the safe and stable operation of the unit.

[0024] Therefore, it is necessary to propose a turbine regenerative system for steam turbine generator units of 300MW and above, which can not only improve the energy efficiency of the unit and reduce coal consumption per kilowatt-hour for a clean and low-carbon transformation of coal-fired power, but also enable deep peak shaving, rapid load change and wide-load high-efficiency transformation of coal-fired power, which is of great significance to the transformation, upgrading and innovative development of coal-fired power in my country. Utility Model Content

[0025] This invention provides a two-stage deoxygenation and regenerative system for steam turbine generator sets of 300MW and above. The regenerative system adopted in this invention has a two-stage deoxygenation function, which can reduce dissolved oxygen in the system, avoid oxidation and corrosion of the regenerative system, boiler, steam turbine, etc., and provide double protection for deoxygenation.

[0026] The regenerative system adopted in this utility model has the advantages of system simplicity, high efficiency, low heat consumption rate, energy saving and emission reduction, high safety, adaptability to rapid load changes, low failure rate, effective reduction of operation and maintenance, long-term stable operation during its service life, high overall economic efficiency in long-term operation, reduced price of equipment and supporting instruments and valves, space saving, and saving civil engineering costs. It solves the problems of existing regenerative systems using surface heaters that cannot effectively solve the problems of deep peak shaving, rapid load changes and high efficiency under wide loads, and can also solve the problems of large cold source loss and low thermal efficiency of surface heaters.

[0027] According to one aspect of the present invention, a two-stage deaeration and regenerative system for a steam turbine generator set of 300MW or above is provided, comprising a high-pressure heater group, a deaerator, and a low-pressure heater group connected in order of pressure from high to low, wherein the low-pressure heater group includes at least one mixing low-pressure heater, and the mixing low-pressure heater is connected to the condenser through a shaft seal heater.

[0028] Based on the above scheme, preferably, the high-pressure heater group includes multiple surface high-pressure heaters and at least one hybrid high-pressure heater, the hybrid high-pressure heater is connected in series with the surface high-pressure heater, and the deaerator is connected to the hybrid high-pressure heater through a water pump.

[0029] Based on the above scheme, preferably, the high-pressure heater group includes multiple surface high-pressure heaters connected in series, and the surface high-pressure heaters are externally connected to a steam cooler.

[0030] Based on the above scheme, preferably, the low-pressure heater group includes multiple surface low-pressure heaters connected in series, and the surface low-pressure heaters are connected to the hybrid low-pressure heater.

[0031] Based on the above scheme, preferably, the low-pressure heater group includes three hybrid low-pressure heaters connected in series. The three hybrid low-pressure heaters are arranged by gravity, and the hybrid low-pressure heater with the lower pressure is located above the vertical height of the deaerator.

[0032] Based on the above scheme, preferably, the mixed low-pressure heater is arranged by gravity, and the mixed low-pressure heater with lower pressure is located above the vertical height of the deaerator.

[0033] Based on the above scheme, a preferred embodiment is provided at the condensate outlet of the condenser, wherein the head of the condensate pump is higher than the sum of the equipment pressure, liquid column static pressure and system pressure loss of a nearby mixed low-pressure heater equipped with an outlet pump.

[0034] In a preferred embodiment based on the above scheme, an exhaust cooler is also included, wherein the top exhaust ports of the deaerator and the mixing low-pressure heater are both connected to the exhaust cooler.

[0035] Based on the above scheme, a preferred embodiment is provided whereby a feedwater pump is installed between the deaerator and the boiler or steam generator.

[0036] Based on the above scheme, the preferred option is that the hybrid low-pressure heater equipment serves as the primary deoxygenation equipment, and the deoxygenator equipment serves as the secondary deoxygenation equipment.

[0037] This utility model discloses a two-stage deaeration and regenerative system for steam turbine generator sets of 300MW or above. Compared with the prior art, this utility model has the following advantages: 1. The regenerative system has high thermal efficiency. The hybrid heater has no end difference and can heat water to the saturated water temperature corresponding to the steam pressure of the heater stage. It makes full use of the energy potential of the heating steam. Since there is no end difference, its thermal economy can be improved by at least 0.3% to 0.5% compared with the surface heater, and its heat consumption rate and steam consumption rate can be reduced by at least 0.3% to 0.5%. It has high long-term operating economy.

[0038] 2. The mixing heater equipment has a simple structure and reliable operation. Because steam and water come into direct contact in a hybrid heater, there is no metal heat transfer surface. Therefore, there are no heat exchange tubes and tube sheets of a surface heat exchanger. As a result, the hybrid heater has a simple structure, high reliability, can improve the stability of unit operation, reduce the failure rate of the unit, and reduce the unit operation and maintenance costs.

[0039] 3. Hybrid heater equipment has a lower cost and higher economic efficiency. The main pressure-bearing components of the hybrid heater can be made of carbon steel or low alloy steel, which are currently the most widely used materials in my country. Therefore, the hybrid heater has lower material requirements. Since the specifications and dimensions of these two types of heaters are roughly the same and there are no heat exchange tubes or tube sheets in the structure, the metal consumption of the hybrid heater equipment is less, the equipment cost is lower, and the economy is higher.

[0040] 4. The hybrid heater equipment has strong adaptability. Surface heaters require a compact structure to reduce heat transfer dead zones, while mixing heaters do not have this drawback. The internal space can be designed according to actual needs, making it easy to collect various media such as steam and water with different parameters, such as condensate, makeup water, expansion steam, and shaft sealing steam, thus having strong adaptability.

[0041] 5. The mixing heater equipment can achieve deoxygenation function and is a multi-functional device.

[0042] Unlike surface heaters, hybrid heaters, when equipped with atomizing nozzles, exhaust devices, and uniform heating devices, can effectively remove dissolved oxygen and other non-condensable gases from condensate. Therefore, they can also be used as deoxygenation equipment. This system upgrades deoxygenation from a single stage to a two-stage process, further improving the system's deoxygenation effect and effectively preventing metal-oxygen corrosion of subsequent pipelines and equipment, thus extending the service life of downstream equipment.

[0043] 6. The system has fewer regeneration stages, and the hybrid heater does not require a bypass system, reducing the number of instruments and valves, and simplifying the control system.

[0044] 7. Hybrid heaters do not require space for core extraction or shell extraction, thus occupying less space and saving building space.

[0045] 8. The hybrid heater system has a rapid temperature rise, which shortens the start-up time of the unit.

[0046] 9. The hybrid heater equipment has a low failure rate, does not require replacement during the unit's lifespan, has low overall costs, and is highly economical.

[0047] 10. Systems using hybrid heaters can improve unit energy efficiency, reduce coal consumption per kilowatt-hour, and promote the clean and low-carbon transformation of coal-fired power.

[0048] 11. Systems employing hybrid heaters are adaptable to deep peak shaving, rapid load changes, and high efficiency across wide load ranges, promoting the transformation of coal-fired power plants towards flexible and efficient upgrading. Attached Figure Description

[0049] To more clearly illustrate the technical solutions of the embodiments of this utility model, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 This diagram shows the layout flow of the regenerative system for a conventional 1000MW single-cycle reheat steam turbine generator unit. Figure 2 This invention presents a flow chart illustrating the arrangement of a regenerative system that replaces six conventional surface-type low-pressure heaters with three hybrid low-pressure heaters. Figure 3 This invention presents a flow chart illustrating the arrangement of a regenerative system that replaces two surface low-pressure heaters with one hybrid low-pressure heater. Figure 4 This invention presents a flow chart illustrating the arrangement of a regenerative system that replaces three surface low-pressure heaters with one hybrid low-pressure heater. Figure 5 This invention presents a flow chart of a gravity-arranged regenerative system in which three hybrid low-pressure heaters replace six surface low-pressure heaters. Figure 6 This invention presents a flow chart of a gravity-arranged regenerative system in which one hybrid low-pressure heater replaces two surface low-pressure heaters. Figure 7 This invention presents a flow chart illustrating the layout of a regenerative system that replaces six conventional surface-type low-pressure heaters with three hybrid low-pressure heaters, including exhaust steam recovery. Figure 8 The diagram shows a gravity-arranged regenerative system of the present invention, in which one hybrid heater replaces one surface high-pressure heater and one hybrid low-pressure heater replaces two conventional surface low-pressure heaters, including exhaust steam recovery. Explanation of icon numbers: 1. First high-pressure heater; 2. Second high-pressure heater; 3. Third high-pressure heater; 4. Fourth high-pressure heater; 5. Deaerator; 6. Sixth low-pressure heater; 7. Seventh low-pressure heater; 8. Eighth low-pressure heater; 9. Ninth low-pressure heater; 10. Tenth low-pressure heater; 11. Eleventh low-pressure heater; 12. Steam cooler; 13. Drain cooler; 14. Shaft seal cooler; 15. Feed water pump; 16. Condensate pump; 17. Drain pump; 18. Condenser; 19. First mixing low-pressure heater; 20. First outlet pump; 21. Second mixing low-pressure heater; 22. Second outlet pump; 23. Third mixing low-pressure heater; 24. Third outlet pump; 25. Exhaust cooler; 26. First mixing high-pressure heater; 27. Fourth outlet pump.

[0050] 100. High-pressure heater assembly; 200. Low-pressure heater assembly. Detailed Implementation

[0051] The specific embodiments of this utility model will be further described in detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this utility model, but are not intended to limit the scope of this utility model.

[0052] It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of a descriptive feature, integral, step, operation, element, and / or component, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or sets.

[0053] To keep the drawings concise, only the parts relevant to this invention are shown schematically in each figure, and they do not represent the actual structure of the product. Furthermore, for ease of understanding, in some figures, only one of the components with the same structure or function is schematically depicted, or only one is labeled. In this document, "one" not only means "only one," but can also mean "more than one."

[0054] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0055] In the embodiments shown in the accompanying drawings, the directional indications (such as up, down, left, right, front, and back) used to explain the structure and movement of the various components of this invention are relative rather than absolute. These descriptions are appropriate when these components are in the positions shown in the drawings. If the descriptions of the positions of these components change, these directional indications also change accordingly.

[0056] Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0057] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the specific implementation methods of this utility model will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of this utility model. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0058] Currently, the configuration scheme of heat exchanger equipment for the turbine regenerative system in conventional power plants is as follows. The following quantities are for a single unit: 300MW-class generator sets: The number of regeneration stages is generally 7 to 9, mainly consisting of 3 to 4 high-pressure heaters, such as the first high-pressure heater 1, the second high-pressure heater 2, the third high-pressure heater 3 and / or the fourth high-pressure heater 4, a deaerator 5, 3 to 4 low-pressure heaters such as the sixth low-pressure heater 6, the seventh low-pressure heater 7 and the eighth low-pressure heater 8 and / or the ninth low-pressure heater 9.

[0059] 600MW-class generator sets: The number of regenerative stages is generally 8 to 10, mainly including 3 to 4 high-pressure heaters such as the first high-pressure heater 1, the second high-pressure heater 2, the third high-pressure heater 3 and / or the fourth high-pressure heater 4, the deaerator 5, and 4 to 5 low-pressure heaters such as the sixth low-pressure heater 6, the seventh low-pressure heater 7, the eighth low-pressure heater 8, the ninth low-pressure heater 9 and / or the tenth low-pressure heater 10.

[0060] 1000MW-class generator sets: The number of regenerative stages is generally 10 to 11, mainly consisting of 4 high-pressure heaters (first high-pressure heater 1, second high-pressure heater 2, third high-pressure heater 3 and fourth high-pressure heater 4), deaerator 5, and 5 to 6 low-pressure heaters such as sixth low-pressure heater 6, seventh low-pressure heater 7, eighth low-pressure heater 8, ninth low-pressure heater 9, tenth low-pressure heater 10 and / or eleventh low-pressure heater 11.

[0061] like Figure 1As shown in the diagram, the regenerative system of a conventional 1000MW single-stage reheat turbine generator unit is used as an example. It consists of 11 stages of regenerative equipment, including 4 stages of surface high-pressure heaters (such as the first high-pressure heater 1, the second high-pressure heater 2, the third high-pressure heater 3, and the fourth high-pressure heater 4), 1 stage of mixing deaerator 5, and 6 stages of surface low-pressure heaters (such as the sixth low-pressure heater 6, the seventh low-pressure heater 7, the eighth low-pressure heater 8, the ninth low-pressure heater 9, the tenth low-pressure heater 10, and the eleventh low-pressure heater 11). It is equipped with an external high-pressure heater steam cooler 12, an external low-pressure heater condensate cooler 13, a shaft seal cooler 14, a feedwater pump 15, a condensate pump 16, a condensate pump 17, and a condenser 18, which together form the regenerative system.

[0062] like Figure 2 As shown, the present invention discloses a two-stage deaeration and regenerative system for a steam turbine generator set of 300MW or above, comprising a high-pressure heater group 100, a deaerator 5, a low-pressure heater group 200, a shaft seal cooler 14, and a condenser 18 connected in sequence.

[0063] Figure 2 In the middle, the low-pressure heater group 200 includes 3 mixed low-pressure heaters (first mixed low-pressure heater 19, second mixed low-pressure heater 21, and third mixed low-pressure heater 23) and 3 outlet water pumps (first outlet water pump 20, second outlet water pump 22, and third outlet water pump 24). Any one of the 3 mixed low-pressure heaters can be used as a low-pressure heating deaerator, with the third mixed low-pressure heater 23 being the most preferred.

[0064] In this embodiment, the high-pressure heater group 100 includes four surface high-pressure heaters connected in series (first surface high-pressure heater 1, second surface high-pressure heater 2, third surface high-pressure heater 3 and fourth surface high-pressure heater 4), and the surface high-pressure heaters are externally connected to a steam cooler 12.

[0065] like Figure 2 As shown, in the regenerative system, the feedwater is connected in series sequentially from the condenser 18 to the low-pressure heater group 200, to the deaerator 5, to the high-pressure heater group 100. It is then pressurized and transported sequentially by the condensate pump 16, three outlet pumps (first outlet pump 20, second outlet pump 22, and third outlet pump 24), and feedwater pump 15, and finally delivered to the boiler or steam generator.

[0066] It should be noted that any of the surface-type high-pressure heaters (first high-pressure heater 1, second high-pressure heater 2, third high-pressure heater 3 and fourth high-pressure heater 4) of this utility model can also be replaced by the first mixing high-pressure heater 26. The equipment has no condensate drain and no condensate drain system. The system does not need to be equipped with an external steam cooler 12. High-temperature, high-enthalpy steam can directly enter the water-side space of the mixing heat exchanger. In addition to turbine steam and condensate drain from the upper-level equipment, it can also accept other steam, exhaust gas, subcooled water, hot water and other media.

[0067] Of course, when the high-pressure heater group 100 is a surface high-pressure heater, the first high-pressure heater 1, the second high-pressure heater 2, the third high-pressure heater 3 and the fourth high-pressure heater 4 are connected in series, and the condensate is discharged by gravity in stages. The condensate from the last stage fourth high-pressure heater 4 flows into the deaerator 5 by gravity.

[0068] Of course, the high-pressure heater group 100 can also use any combination of hybrid heat exchangers and surface heat exchangers. In this system, the condensate from the surface high-pressure heater is discharged by gravity in stages to the next stage surface high-pressure heater, hybrid high-pressure heater, or deaerator 5; the hybrid high-pressure heater equipment has no condensate and no condensate system.

[0069] It should be noted that when the low-pressure heater of this utility model is a hybrid heat exchanger, the system does not need to be equipped with a condensate cooler 13.

[0070] This utility model discloses a hybrid low-pressure heater, a multi-functional device that serves as a deaerator, heat exchanger, and water tank. As a primary deaerator, it meets the requirements of the unit under load variations of 10% to 110% of rated operating conditions, with the dissolved oxygen content of the effluent ≤7μg / L. As a water tank, its effective volume meets the boiler's feedwater consumption requirements for 5 to 10 minutes during maximum continuous evaporation operation.

[0071] The deaerator 5 of this invention, serving as a secondary and advanced deaeration device, meets the requirements of the unit under load variations of 10% to 110% of its rated operating conditions throughout the entire process, ensuring a minimum dissolved oxygen content of ≤5 μg / L in the effluent, and more preferably, a dissolved oxygen content of ≤3 μg / L in the effluent. Furthermore, the deaerator 5 does not need to function as a water tank, thus reducing the equipment volume, dimensions, metal consumption, weight, and foundation load, thereby improving economic efficiency.

[0072] In this Figure 2 In this embodiment, three hybrid low-pressure heaters were selected to replace the existing six surface heaters, wherein... Please continue reading. Figure 3 As shown, with Figure 2Unlike the previous embodiment, in this embodiment, a hybrid low-pressure heater 19 with deoxygenation function is selected to replace the existing two surface low-pressure heaters (sixth low-pressure heater 6 and seventh low-pressure heater 7). That is, in the low-pressure heater group 200, the hybrid low-pressure heater 19 and four surface low-pressure heaters are connected in series (eighth low-pressure heater 8, ninth low-pressure heater 9, tenth low-pressure heater 10 and eleventh low-pressure heater 11).

[0073] like Figure 3 The condensate from the eighth low-pressure heater 8 flows by gravity to the ninth low-pressure heater 9; the condensate from the ninth low-pressure heater 9 is pumped back to the condensate system by the condensate pump 17; the condensate from the tenth low-pressure heater 10 and the eleventh low-pressure heater 11 flows by gravity to the external condensate cooler 13 and finally flows by gravity into the condenser 18.

[0074] As another preferred embodiment of this utility model, please continue reading. Figure 4 As shown, in this embodiment, a hybrid low-pressure heater 19 with deoxygenation function is selected to replace the existing three surface low-pressure heaters (sixth low-pressure heater 6, seventh low-pressure heater 7, and eighth low-pressure heater 8). That is, in the low-pressure heater group 200, the hybrid low-pressure heater 19 and the three surface low-pressure heaters are connected in series. The three surface low-pressure heaters are the ninth low-pressure heater 9, the tenth low-pressure heater 10, and the eleventh low-pressure heater 11.

[0075] As another preferred embodiment of this utility model, please continue reading. Figure 5 As shown, in this embodiment, the low-pressure heater group 200 is composed of three mixed low-pressure heaters (first mixed low-pressure heater 19, second mixed low-pressure heater 21, and third mixed low-pressure heater 23) and a second outlet water pump 22. Any one of the three mixed low-pressure heaters can be used as a low-pressure heating deaerator, with the third mixed low-pressure heater 23 being the most preferred.

[0076] like Figure 5 The medium-low pressure heater group 200, including the first mixing low-pressure heater 19 and the third mixing low-pressure heater 23, is arranged by gravity. They are positioned at a certain height above the deaerator 5 and the second mixing low-pressure heater 21, respectively, so that the effluent flows into the equipment below by gravity. Compared to traditional solutions, this scheme only requires the addition of a second effluent pump 22 to meet the forced circulation requirements of the circulating water.

[0077] As another preferred embodiment of this utility model, please continue reading. Figure 6As shown, in this embodiment, a hybrid low-pressure heater 19 with deoxygenation function is selected to replace the existing two surface low-pressure heaters (sixth low-pressure heater 6 and seventh low-pressure heater 7). The hybrid low-pressure heater 19 is arranged by gravity at a certain height above the deaerator 5, so that the effluent can flow into the deaerator 5 by gravity without the need to set up an effluent pump.

[0078] For another preferred embodiment of this utility model, please refer to [the following text]. Figure 7 As shown, in this embodiment, an exhaust cooler 25 device and system are selected for exhaust heat and working fluid recovery.

[0079] As another preferred embodiment of this utility model, please continue reading. Figure 8 As shown, in this embodiment, a first hybrid high-pressure heater 26 is selected to replace the surface-type fourth high-pressure heater 4. The outlet of the first hybrid high-pressure heater 26 is connected to the inlet of the feed water pump 15, and is arranged in a certain height space according to the net positive suction head (NPSH) requirement of the feed water pump 15. Accordingly, the deaerator 5 does not need to be arranged in a high position, and the feed water outlet of the deaerator 5 is connected to the inlet of the fourth outlet pump 27.

[0080] In the above scheme, the condensate pumps 16 are all arranged between the condenser 18 and the low-pressure heater group 200, such as Figure 1 According to the plan, the head of the condensate pump 16 needs to be higher than the sum of the equipment pressure of the deaerator 5, the static pressure of the liquid column, and the system pressure loss. like Figures 2-8 The scheme allows for different selections based on different schemes. The pressure head of the condensate pump 16 is changed from the conventional one adapted to the pressure of the deaerator 5 to the one adapted to the lower pressure of the first to third mixed low-pressure heater equipment (first mixed low-pressure heater 19, second mixed low-pressure heater 21, and third mixed low-pressure heater 23). The system pressure loss is reduced, so the pressure head of the condensate pump 16 can be reduced, the power consumption is reduced, and it is more energy-efficient.

[0081] Finally, the method described in this application is merely a preferred embodiment and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A two-stage deaeration and regenerative system for a steam turbine generator set of 300MW or higher, characterized in that, It includes a high-pressure heater group, a deaerator, and a low-pressure heater group connected in order of pressure from high to low. The low-pressure heater group includes at least one mixing low-pressure heater, which is connected to the condenser via a shaft seal heater.

2. The two-stage deaeration and regenerative system for a 300MW or higher-class steam turbine generator set as described in claim 1, characterized in that, The high-pressure heater group includes multiple surface high-pressure heaters and at least one hybrid high-pressure heater. The hybrid high-pressure heater is connected in series with the surface high-pressure heaters, and the deaerator is connected to the hybrid high-pressure heater via a water pump.

3. The two-stage deaeration and regenerative system for a 300MW or higher-class steam turbine generator set as described in claim 1, characterized in that, The high-pressure heater group includes multiple surface high-pressure heaters connected in series, and each surface high-pressure heater is externally connected to a steam cooler.

4. A two-stage deaeration and regenerative system for a 300MW or higher-class steam turbine generator set as described in claim 2 or 3, characterized in that, The low-pressure heater group includes multiple surface low-pressure heaters connected in series, and the surface low-pressure heaters are in communication with the hybrid low-pressure heater.

5. The two-stage deaeration and regenerative system for a 300MW or higher-class steam turbine generator set as described in claim 4, characterized in that, The low-pressure heater group includes three hybrid low-pressure heaters connected in series. The three hybrid low-pressure heaters are arranged by gravity, and the hybrid low-pressure heater with the lower pressure is located above the vertical height of the deaerator.

6. The two-stage deaeration and regenerative system for a 300MW or higher-class steam turbine generator set as described in claim 4, characterized in that, The hybrid low-pressure heater is arranged by gravity, and the lower pressure hybrid low-pressure heater is located above the vertical height of the deaerator.

7. A two-stage deaeration and regenerative system for a steam turbine generator set of 300MW or above as described in claim 5, characterized in that, A condensate pump is installed at the condensate outlet of the condenser. The head of the condensate pump is higher than the sum of the equipment pressure, liquid column static pressure, and system pressure loss of a nearby mixed low-pressure heater equipped with an outlet pump.

8. A two-stage deaeration and regenerative system for a steam turbine generator set of 300MW or above as described in claim 5, characterized in that, It also includes an exhaust cooler, and the top exhaust ports of the deaerator and the mixing low-pressure heater are both connected to the exhaust cooler.

9. A two-stage deaeration and regenerative system for a steam turbine generator set of 300MW or above as described in claim 5, characterized in that, A feedwater pump is installed between the deaerator and the boiler or steam generator.

10. A two-stage deaeration and regenerative system for a 300MW or higher-class steam turbine generator set as described in claim 1, characterized in that, The hybrid low-pressure heater equipment serves as a primary deoxygenation device, while the deoxygenator equipment serves as a secondary deoxygenation device.

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