Full-working-condition composite dry-wet state conversion system of ultra-supercritical boiler

Abstract

The utility model provides an ultra-supercritical boiler full-working-condition composite dry and wet state conversion system, and belongs to the technical field of coal power unit flexibility reformation. The system comprises a boiler water recycling module used for recycling wet state water separated by a separator (34); the drainage expansion module is used for carrying out expansion vaporization after the temperature and pressure of the wet water are reduced, and secondary steam is obtained; and the heat exchange deoxidization module is used for carrying out heat exchange on saturated condensed water left after the wet water is expanded and vaporized and condensed water from the low-temperature heater to obtain supercooled water, and the supercooled water enters the heat exchange deoxidization module. According to the scheme, the working medium and heat of circulating water in the coal-fired boiler starting stage and the deep peak load regulation load can be recycled.

Description

Technical Field

[0001] This application relates to the field of coal-fired power unit flexibility retrofit technology, specifically to a composite dry-wet state conversion system for an ultra-supercritical boiler under all operating conditions. Background Art

[0002] Due to the rapid development of new energy sources, large coal-fired power units participating in deep peak shaving has become commonplace. During deep peak shaving, as the load decreases, supercritical boilers will undergo dry-wet state switching. Currently, there are two main types of boiler dry-wet state switching technologies: a supercritical boiler dry-wet state seamless switching system with coupled boiler water circulation pumps and a supercritical boiler dry-wet state switching system without boiler water circulation pumps.

[0003] Current technologies cannot recover the working fluid and heat of circulating water during the start-up phase and deep peak load shaving of coal-fired boilers. Therefore, how to recover the working fluid and heat of circulating water during the start-up phase and deep peak load shaving of coal-fired boilers remains an unsolved problem. Utility Model Content

[0004] The purpose of this application is to provide a composite dry-wet state conversion system for ultra-supercritical boilers under all operating conditions, which can solve the problem in the prior art of not being able to recover the working fluid and heat of circulating water during the start-up phase and deep peak load of coal-fired boilers.

[0005] In the first aspect, the embodiments of this application provide a composite dry-wet state conversion system for an ultra-supercritical boiler under all operating conditions, including: a water storage tank (35), an economizer (32), a water-cooled wall (33), and a separator (34). The system also includes: a boiler water recirculation module, a condensate expansion module, a heat exchange deoxygenation module, a low-temperature heater, and a high-temperature heater.

[0006] The input end of the water-cooled wall (33) is connected to the output end of the economizer (32), the output end of the water-cooled wall (33) is connected to the input end of the separator (34), and the output end of the separator (34) is connected to the input end of the water storage tank (35).

[0007] The first output end of the water storage tank (35) is connected to the input end of the boiler water recirculation module, the second output end of the water storage tank (35) is connected to the input end of the drainage expansion module, and the output end of the boiler water recirculation module is connected to the input end of the economizer (32).

[0008] The first output terminal of the hydrophobic expansion module is connected to the first input terminal of the heat exchange and deoxygenation module, the second output terminal of the hydrophobic expansion module is connected to the second input terminal of the heat exchange and deoxygenation module, the third output terminal of the hydrophobic expansion module is connected to the input terminal of the high-temperature heater, and the third input terminal of the heat exchange and deoxygenation module is connected to the output terminal of the low-temperature heater.

[0009] The boiler water recirculation module is used to recirculate the wet water separated by the separator (34);

[0010] The hydrophobic expansion module is used to expand and vaporize wet water after decooling and depressurizing it to obtain secondary steam.

[0011] The heat exchange and deoxygenation module is used to exchange heat with the saturated condensate remaining after the expansion and vaporization of wet water, and then obtain subcooled water, which enters the heat exchange and deoxygenation module.

[0012] In one possible implementation of the first aspect, the system further includes a high-pressure heater (36), and the boiler water recirculation module includes: a control unit, a low-flow recirculation unit, and a subcooling tube unit;

[0013] The first output end of the water storage tank (35) is connected to the input end of the control unit, and the second output end of the water storage tank (35) is connected to the input end of the hydrophobic expansion module. The water storage tank (35) is used to store the wet water separated by the separator (34).

[0014] The input terminal of the control unit is also connected to the first terminal of the small flow recirculation unit and the output terminal of the subcooling tube unit. The first output terminal of the control unit is connected to the input terminal of the economizer (32), and the second output terminal of the control unit is connected to the second terminal of the small flow recirculation unit.

[0015] The control unit is used to control the circulation of wet water in the water storage tank (35), and the small flow recirculation unit is used to recirculate the wet water at a preset flow rate;

[0016] The input end of the subcooling tube unit is connected to the output end of the high-pressure heater (36), and the output end of the high-pressure heater (36) is also connected to the input end of the economizer (32).

[0017] In one possible implementation of the first aspect, the control unit includes: an electric gate valve (23), a boiler water circulation pump (24), a flow measurement device (25), a check valve (26), an electric regulating valve (27), and a second electric gate valve (28).

[0018] An electric gate valve (23), a boiler water circulation pump (24), a flow measurement device (25), a check valve (26), an electric regulating valve (27), and a second electric gate valve (28) are connected in series between the first output end of the water storage tank (35) and the input end of the economizer (32).

[0019] A boiler water circulation pump (24) is used to circulate wet water in a water storage tank (35).

[0020] In one possible implementation of the first aspect, the low-flow recirculation unit includes: an electric gate valve (29) and a flow measurement device (30).

[0021] The first end of the electric gate valve (29) is connected to the output end of the boiler water circulation pump (24), the second end of the electric gate valve (29) is connected to the first end of the flow measuring device (30), and the second end of the flow measuring device (30) is connected to the first end of the electric gate valve (23).

[0022] In one possible implementation of the first aspect, the subcooling pipe unit includes: an electric gate valve (31) and a subcooling pipe disposed between the first output end of the water storage tank (35) and the output end of the high-pressure heater (36), wherein the electric gate valve (31) is disposed on the subcooling pipe.

[0023] In one possible implementation of the first aspect, the hydrophobic expansion module includes: a de-cooling and de-pressure unit, an expansion container (37), a first steam delivery unit, and a second steam delivery unit;

[0024] The input end of the de-temperature and pressure reducing unit is connected to the second output end of the boiler water recirculation module, and the output end of the de-temperature and pressure reducing unit is connected to the input end of the expansion tank (37). The de-temperature and pressure reducing unit is used to de-temperature and pressure reduce the wet water and then transport it to the expansion tank (37).

[0025] The first output end of the expansion container (37) is connected to the first input end of the heat exchange and deoxygenation module, the second output end of the expansion container (37) is connected to the input end of the first steam conveying unit, and the third output end of the expansion container (37) is connected to the input end of the second steam conveying unit. The expansion container (37) is used to expand and vaporize the de-cooled and depressurized wet water to obtain secondary steam.

[0026] The output of the first steam delivery unit is connected to the second input of the heat exchange and deoxygenation module, and the output of the second steam delivery unit is connected to the input of the high-temperature heater.

[0027] In one possible implementation of the first aspect, the de-cooling and pressure-reducing unit includes: an electric gate valve (1), an isolation valve (2), a flow measuring device (3), a small flow 361 valve (4), and a multi-stage flow limiting device (5); the electric gate valve (1), the isolation valve (2), the flow measuring device (3), the small flow 361 valve (4), and the multi-stage flow limiting device (5) are connected in series between the second output end of the boiler water recirculation module and the input end of the expansion tank (37).

[0028] In one possible implementation of the first aspect, the first steam delivery unit includes: an isolation valve (6), an electric regulating valve (7), an electric gate valve (8), and a check valve (9); the isolation valve (6), the electric regulating valve (7), the electric gate valve (8), and the check valve (9) are connected in series between the second output terminal of the condensate expansion module and the input terminal of the high-temperature heater.

[0029] In one possible implementation of the first aspect, the second steam delivery unit includes: an isolation valve (10), an electric regulating valve (11), an electric gate valve (12), and a check valve (13); the isolation valve (10), the electric regulating valve (11), the electric gate valve (12), and the check valve (13) are connected in series between the second output end of the hydrophobic expansion module and the second input end of the heat exchange deoxygenation module, and the first end of the isolation valve (10) is connected to the first end of the isolation valve (6).

[0030] In one possible implementation of the first aspect, the system further includes a wastewater discharge module, an atmospheric expansion tank (39), and a condenser (40).

[0031] The input end of the wastewater discharge module is connected to the first output end of the expansion vessel (37), and the output end of the wastewater discharge module is connected to the first end of the atmospheric expansion vessel (39). The wastewater discharge module is used to discharge the unqualified water obtained when rinsing the expansion vessel (37) to the atmospheric expansion vessel (39). The second end of the atmospheric expansion vessel (39) is connected to the first output end of the boiler water recirculation module and the input end of the condenser (40).

[0032] In one possible implementation of the first aspect, the wastewater discharge module includes: an isolation valve (21), an electric gate valve (22), and a condensate drain pipe disposed between the first output end of the condensate expansion module and the output end of the heat exchange deoxygenation module; the isolation valve (21) and the electric gate valve (22) are connected in series on the condensate drain pipe.

[0033] In one possible implementation of the first aspect, the heat exchange and deoxygenation module includes: a heat exchange unit and a deoxygenation unit;

[0034] The first input terminal of the heat exchange unit is connected to the first output terminal of the hydrophobic expansion module, the second input terminal of the heat exchange unit is connected to the output terminal of the low-temperature heater, the first output terminal of the heat exchange unit is connected to the output terminal of the deoxygenation unit, and the second output terminal of the heat exchange unit is connected to the first input terminal of the deoxygenation unit.

[0035] The second input terminal of the deaerator unit is connected to the second output terminal of the hydrophobic expansion module, and the output terminal of the deaerator unit is also connected to the first output terminal of the boiler water recirculation module.

[0036] The heat exchange unit is used to exchange heat with the saturated condensate remaining after the expansion and vaporization of wet water and the condensate from the low-temperature heater to obtain subcooled water, which then enters the deoxygenation unit; the deoxygenation unit is used to recover the subcooled water.

[0037] In one possible implementation of the first aspect, the heat exchange unit includes: an electric gate valve (14), an electric regulating valve (15), a water-to-water heat exchanger (16), an electric gate valve (18), an electric gate valve (19), and an electric regulating valve (20).

[0038] Electric gate valve (14), electric regulating valve (15) and water-to-water heat exchanger (16) are connected in series between the first output end of the hydrophobic expansion module and the output end of the deoxygenation unit. The first input end of the water-to-water heat exchanger (16) is connected to the first end of the electric gate valve (18), and the first output end of the water-to-water heat exchanger (16) is connected to the first end of the electric gate valve (19).

[0039] The second end of the electric gate valve (18) is connected to the first end of the electric regulating valve (20) and the input end of the low-temperature heater, and the second end of the electric gate valve (19) is connected to the second end of the electric regulating valve (20) and the first input end of the deoxygenation unit.

[0040] In one possible implementation of the first aspect, the deaeration unit includes: a deaerator (38), an energy dissipation device (17), and a drain pipe disposed between the output end of the deaerator (38) and the first output end of the boiler water recirculation module;

[0041] The energy dissipation device (17) is located at the output end of the deaerator (38) and inside the deaerator (38). The output end of the deaerator (38) is connected to the first output end of the heat exchange unit and the first output end of the boiler water recirculation module.

[0042] Secondly, embodiments of this application provide a method for combined dry and wet state conversion under all operating conditions of an ultra-supercritical boiler, implemented based on the ultra-supercritical boiler combined dry and wet state conversion system according to any one of the first aspects, the method comprising:

[0043] In the initial stage of coal-fired power unit startup, the coal-fired boiler is in wet operation. Based on the boiler water recirculation module, the wet water separated by the separator (34) is recirculated. Based on the hydrophobic expansion module, the wet water is de-heated and depressurized and then expanded and vaporized to obtain secondary steam, which enters the heat exchange and deoxygenation module. Based on the heat exchange and deoxygenation module, the remaining saturated condensate after the wet water is expanded and vaporized is exchanged with the condensate from the low temperature heater to obtain subcooled water, which then enters the heat exchange and deoxygenation module.

[0044] When the operating load of the coal-fired boiler is between the first preset load and the second preset load, the water level of the water storage tank (35) is controlled based on the boiler water recirculation module, and the pipes of the drainage expansion module are warmed up using wet water.

[0045] When the operating load of the coal-fired boiler is between the second and third preset loads, the boiler water recirculation module is shut down, and the condensate expansion module and heat exchange deaeration module are turned on to regulate the water level.

[0046] When the operating load of the coal-fired boiler exceeds the third preset load, the coal-fired boiler switches to dry operation and shuts down the condensate expansion module and the heat exchange deaeration module.

[0047] In one possible implementation of the second aspect, the system includes a water storage tank (35), an economizer (32), and a boiler water recirculation module including a control unit, which includes a boiler water circulation pump (24); the recirculation of saturated water in the boiler based on the boiler water recirculation module includes:

[0048] The wet water in the water storage tank (35) is circulated into the economizer (32) by the boiler water circulation pump (24).

[0049] In one possible implementation of the second aspect, the hydrophobic expansion module includes: a de-cooling and de-pressure unit and an expansion container (37); based on the hydrophobic expansion module, wet water is de-cooled and de-pressured, then expanded and vaporized to obtain secondary steam, which enters the heat exchange and deoxygenation module, including:

[0050] Based on the de-cooling and de-pressure unit, the wet water is de-cooled and de-pressured and then transported to the expansion container (37).

[0051] Based on the expansion container (37), the wet water after de-cooling and de-pressure is expanded and vaporized to obtain secondary steam, which enters the heat exchange and deoxygenation module.

[0052] In one possible implementation of the second aspect, the hydrophobic expansion module includes an expansion container (37), and the heat exchange deoxygenation module includes a heat exchange unit and a deoxygenation unit, the heat exchange unit including a water-to-water heat exchanger (16); based on the heat exchange deoxygenation module, the saturated condensate remaining after the expansion and vaporization of wet water is exchanged with condensate from the low-temperature heater to obtain subcooled water, and the subcooled water enters the heat exchange deoxygenation module, including:

[0053] Based on the water-to-water heat exchanger (16), the remaining saturated condensate after the expansion container (37) is vaporized is exchanged with the condensate from the low-temperature heater to obtain subcooled water, which then enters the deoxygenation unit.

[0054] The ultra-supercritical boiler full-condition composite dry-wet conversion system of this application recirculates the wet water separated by the separator (34) in the boiler water recirculation module, expands the capacity of the wet water after de-temperature and de-pressure reduction in the condensate expansion module to obtain secondary steam, and the heat exchange deoxygenation module exchanges the remaining saturated condensate after the expansion and vaporization of the wet water with the condensate from the low temperature heater to obtain subcooled water, so that the subcooled water enters the heat exchange deoxygenation module.

[0055] The proposed solution can recover the working fluid and heat of circulating water during the start-up phase and deep peak load of coal-fired boilers, and has strong ease of use and practicality.

[0056] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0057] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0058] Figure 1 This is a schematic block diagram of the ultra-supercritical boiler full-condition composite dry-wet state conversion system provided in the embodiments of this application;

[0059] Figure 2 This is a schematic block diagram of the ultra-supercritical boiler full-condition composite dry-wet state conversion system provided in the embodiments of this application. Detailed Implementation

[0060] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application can also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0061] It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0062] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0063] 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.

[0064] As used in this specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if [the described condition or event] is detected" may be interpreted, depending on the context, as "once determined," "in response to determination," "once [the described condition or event] is detected," or "in response to detection of [the described condition or event]."

[0065] Furthermore, in the description of this application, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0066] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in some other embodiments," "in other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0067] In this application specification, unless otherwise stated, directional terms such as "up," "down," "left," and "right" generally refer to the orientation or positional relationship based on the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use.

[0068] In this application specification, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0069] In recent years, with the large-scale development of new energy sources such as wind power and photovoltaics, the installed capacity and power generation of new energy sources have been increasing, and China's energy consumption and production structures are showing a trend towards clean energy. Due to the randomness, intermittency, and instability of new energy sources, their rapid development has brought increasing challenges to new energy consumption and grid peak shaving. Coal-fired power units are facing the need to shift from power generation-oriented to regulation-oriented power sources, but the existing coal-fired units lack flexibility and have limited peak-shaving capacity, preventing the effective release of wind and solar power capacity.

[0070] Due to the rapid development of new energy sources, large thermal power units participating in deep peak shaving has become commonplace. During deep peak shaving, as the load decreases (30% BMCR (Boiler Maximum Continuous Rating), supercritical boilers will experience a dry-wet transition. Since supercritical units are designed to only switch between dry and wet states during startup and shutdown, and continuous operation in a wet state is not considered during normal operation, there is a significant waste of working fluid and heat during the transition. Therefore, the dry-wet transition has become a bottleneck restricting supercritical units from participating in deep peak shaving.

[0071] The current focus is on implementing flexibility upgrades for coal-fired power units to further enhance their flexibility and regulation capabilities, and to promote the transformation of coal-fired power into a source of both basic security and system regulation. Whether from a policy perspective or from the perspective of power plants enhancing their competitiveness and profitability on the grid, conducting technical research on dry-wet switching systems for coal-fired units is an inevitable trend.

[0072] There are two conventional methods for boiler dry-wet state conversion. The first method is the start-up method without a boiler water circulation pump: saturated water produced by the steam-water separator enters the storage tank, and water with qualified water quality is introduced into the main body drainage expansion tank or directly discharged into the condenser; if the water quality is unqualified, it is directly discharged. This operating method results in a great waste of working fluid and heat.

[0073] The second operating mode is the start-up method with a boiler water circulation pump: In this mode, a boiler water circulation pump is installed below the water storage tank. During startup, if the water quality is up to standard, the circulation pump is activated, allowing saturated water from the storage tank to be pumped to the economizer inlet, thus recovering the working fluid and heat. However, since the circulation pump delivers saturated water, frequent start-ups and shutdowns and long-term operation can easily cause cavitation in the circulation pump, affecting the reliability of the unit operation.

[0074] To address the above issues, there are currently two main types of boiler dry-wet switching technologies: a supercritical boiler dry-wet switching system with coupled boiler water circulation pump and a supercritical boiler dry-wet switching system without boiler water circulation pump.

[0075] The supercritical boiler dry-wet state seamless switching system technology, which combines a boiler water pump circulation system and a water storage tank fine-tuning system, involves adjusting the water level when the unit frequently performs deep peak shaving in the 25% to 35% load range. The high-temperature saturated water from the water storage tank is then piped to the deaerator. When the unit's deep peak shaving reaches 20%, the boiler water circulation pump is activated to direct the high-temperature saturated water from the water storage tank to the economizer inlet.

[0076] The technology of a dry-wet switching system for supercritical boilers without boiler water circulation pumps: High-temperature saturated water from the storage tank enters the expansion tank after being subjected to multi-stage flow restriction and pressure reduction, flash steam enters the No. 2 high-pressure heater, and condensate enters the deaerator, thereby realizing the full recovery of working fluid and heat after switching to wet operation and continuous operation after deep peak shaving and switching to wet operation.

[0077] In existing technologies, the feedwater temperature is low during boiler startup, resulting in low steam production and small superheated and reheat steam flow rates. When the unit rapidly switches to high-load operation, the furnace heat load increases sharply, leading to a rapid rise in wall temperature, even exceeding the maximum temperature, in the intermediate superheater, high-temperature superheater, and high-temperature reheater. Therefore, increasing the superheated and reheat steam flow rates remains an unsolved problem.

[0078] To address the aforementioned deficiencies, this application provides a composite dry-wet conversion system for an ultra-supercritical boiler operating under all conditions. In this system, the boiler water recirculation module recirculates the wet water separated by the separator (34), the condensate expansion module de-heats and depressurizes the wet water and then expands and vaporizes it to obtain secondary steam, and the heat exchange and deoxygenation module exchanges the remaining saturated condensate after the wet water expansion and vaporization with the condensate from the low-temperature heater to obtain subcooled water, which then enters the heat exchange and deoxygenation module.

[0079] The proposed solution can recover the working fluid and heat of circulating water during the start-up phase and deep peak load of coal-fired boilers, and has strong ease of use and practicality.

[0080] The overall structure of the ultra-supercritical boiler full-condition composite dry-wet state conversion system provided in this application is described below through specific embodiments.

[0081] Please see Figure 1 , Figure 1 This is a schematic block diagram of the ultra-supercritical boiler full-condition composite dry-wet state conversion system 100 provided in the embodiments of this application. Figure 1 As shown, the system 100 includes: a water storage tank (35), an economizer (32), a water-cooled wall (33), a separator (34), a boiler water recirculation module 110, a drainage expansion module 12, a heat exchange deoxygenation module 130, a No. 5 low-temperature (low-pressure) heater, and a No. 2 high-temperature (high-pressure) heater.

[0082] In some embodiments, the input end of the water-cooled wall (33) is connected to the output end of the economizer (32), the output end of the water-cooled wall (33) is connected to the input end of the separator (34), and the output end of the separator (34) is connected to the input end of the water storage tank (35).

[0083] In some embodiments, the first output end of the water storage tank (35) is connected to the input end of the boiler water recirculation module, the second output end of the water storage tank (35) is connected to the input end of the drainage expansion module, and the output end of the boiler water recirculation module is connected to the input end of the economizer (32).

[0084] In some embodiments, the first output terminal of the hydrophobic expansion module is connected to the first input terminal of the heat exchange and deoxygenation module, the second output terminal of the hydrophobic expansion module is connected to the second input terminal of the heat exchange and deoxygenation module, the third output terminal of the hydrophobic expansion module is connected to the input terminal of the No. 5 high-temperature heater, and the third input terminal of the heat exchange and deoxygenation module is connected to the output terminal of the No. 2 low-temperature heater.

[0085] In some embodiments, the boiler water recirculation module 110 is used to recirculate the wet water separated by the boiler separator (34). The condensate expansion module 120 is used to expand and vaporize the wet water after de-cooling and depressurizing to obtain secondary steam.

[0086] In some embodiments, the heat exchange deoxygenation module 130 is used to exchange heat between the saturated condensate remaining after the expansion and vaporization of wet water and the condensate from the No. 5 low-temperature heater to obtain subcooled water, and then the subcooled water enters the heat exchange deoxygenation module 130.

[0087] Please see Figure 2 , Figure 2 This is a schematic block diagram of the ultra-supercritical boiler full-condition composite dry-wet state conversion system 100 provided in the embodiments of this application. Figure 2 As shown, the boiler water recirculation module 110 includes: a control unit 112, a small-flow recirculation unit 114, and a subcooling pipe unit 116. The first output terminal of the water storage tank (35) is connected to the input terminal of the control unit 112, and the second output terminal of the water storage tank (35) is connected to the input terminal of the hydrophobic expansion module 120. The water storage tank (35) is used to store the wet water separated by the separator (34).

[0088] In some embodiments, the input terminal of the control unit 112 is also connected to the first terminal of the small flow recirculation unit 114 and the output terminal of the subcooling tube unit 116, the first output terminal of the control unit 112 is connected to the input terminal of the economizer (32), and the second output terminal of the control unit 112 is connected to the second terminal of the small flow recirculation unit 114.

[0089] In some embodiments, the control unit 112 is used to control the circulation of wet water in the water storage tank (35). The small flow recirculation unit 114 is used to recirculate the wet water at a preset flow rate (small flow rate), thereby improving the regulation characteristics of the boiler water circulation pump (24) and preventing the boiler water circulation pump (24) from overheating.

[0090] In some embodiments, the input end of the subcooling tube unit 116 is connected to the output end of the high-pressure heater (36), and the output end of the high-pressure heater (36) is also connected to the input end of the economizer (32). The subcooling tube unit 116 is used to prevent flash evaporation of the circulating water at the inlet of the boiler water circulation pump (24) during rapid load reduction and entry into wet operation.

[0091] Please continue reading Figure 2 According to one embodiment of this application, the control unit 112 includes: an electric gate valve (23), a boiler water circulation pump (24), a flow measurement device (25), a check valve (26), an electric regulating valve (27), and a second electric gate valve (28).

[0092] In some embodiments, an electric gate valve (23), a boiler water circulation pump (24), a flow measurement device (25), a check valve (26), an electric regulating valve (27), and a second electric gate valve (28) are connected in series between the first output end of the water storage tank (35) and the input end of the economizer (32). The boiler water circulation pump (24) is used to circulate the wet water in the water storage tank (35).

[0093] Please continue reading Figure 2 According to one embodiment of this application, the small flow recirculation unit 114 includes an electric gate valve (29) and a flow measuring device (30). The first end of the electric gate valve (29) is connected to the output end of the boiler water circulation pump (24), the second end of the electric gate valve (29) is connected to the first end of the flow measuring device (30), and the second end of the flow measuring device (30) is connected to the first end of the electric gate valve (23).

[0094] Please continue reading Figure 2 According to one embodiment of this application, the subcooling pipe unit 116 includes: an electric gate valve (31) and a subcooling pipe disposed between the first output end of the water storage tank (35) and the output end of the high-pressure heater (36), wherein the electric gate valve (31) is disposed on the subcooling pipe.

[0095] Please continue reading Figure 2 According to one embodiment of this application, the hydrophobic expansion module 120 includes: a de-cooling and de-pressure unit 122, an expansion container 37, a first steam conveying unit 124, and a second steam conveying unit 126. The input terminal of the de-cooling and de-pressure unit 122 is connected to the second output terminal of the boiler water recirculation module 110, and the output terminal of the de-cooling and de-pressure unit 122 is connected to the input terminal of the expansion container 37. The de-cooling and de-pressure unit 122 is used to de-cool and de-pressure the wet water before conveying it to the expansion container 37.

[0096] In some embodiments, the first output end of the expansion container 37 is connected to the first input end of the heat exchange and deoxygenation module 130, and the second output end of the expansion container 37 is connected to the input end of the first steam conveying unit 124 and the input end of the second steam conveying unit 126. The expansion container 37 is used to expand and vaporize the de-cooled and depressurized wet water to obtain secondary steam.

[0097] Of these, after being depressurized in expansion vessel 37, a portion is flashed into secondary steam, and the remainder is low-pressure saturated condensate.

[0098] In some embodiments, the output end of the first steam delivery unit 124 is connected to the second input end of the heat exchange and deoxygenation module 130, and the output end of the second steam delivery unit 126 is connected to the input end of the No. 2 high-temperature heater.

[0099] In some embodiments, the secondary steam generated by the expansion and vaporization of wet water in the expansion tank (37) is split into two streams. One stream is led to the No. 2 high-temperature heater to replace part of the second-stage extraction steam for heating the feedwater. An isolation valve (6), an electric regulating valve (7), an electric gate valve (8), and a check valve (9) are installed on this pipeline. The other stream is led to the deaerator (38) to heat the condensate. An isolation valve (10), an electric regulating valve (11), an electric gate valve (12), and a check valve (13) are installed on this pipeline.

[0100] Please continue reading Figure 2 According to one embodiment of this application, the de-temperature and pressure reducing unit 122 includes: an electric gate valve (1), an isolation valve (2), a flow measuring device (3), a small flow 361 valve (4), and a multi-stage flow limiting device (5). The electric gate valve (1), the isolation valve (2), the flow measuring device (3), the small flow 361 valve (4), and the multi-stage flow limiting device (5) are connected in series between the second output terminal of the boiler water recirculation module 110 and the input terminal of the expansion vessel 37.

[0101] Please continue reading Figure 2 According to one embodiment of this application, the first steam delivery unit 124 includes: an isolation valve (6), an electric regulating valve (7), an electric gate valve (8), and a check valve (9). The isolation valve (6), the electric regulating valve (7), the electric gate valve (8), and the check valve (9) are connected in series between the first output terminal of the condensate expansion module 120 and the input terminal of the No. 2 high-temperature heater.

[0102] Please continue reading Figure 2According to one embodiment of this application, the second steam conveying unit 126 includes: an isolation valve (10), an electric regulating valve (11), an electric gate valve (12), and a check valve (13). The isolation valve (10), the electric regulating valve (11), the electric gate valve (12), and the check valve (13) are connected in series between the first output terminal of the hydrophobic expansion module 120 and the second input terminal of the heat exchange deoxygenation module 130, and the first end of the isolation valve (10) is connected to the first end of the isolation valve (6).

[0103] Please continue reading Figure 2 According to one embodiment of this application, the system 100 also includes a wastewater discharge module 140, an atmospheric expansion tank (39), and a condenser (40).

[0104] In some embodiments, the input end of the wastewater discharge module 140 is connected to the first output end of the expansion vessel 37, and the output end of the wastewater discharge module 140 is connected to the first end of the atmospheric expansion vessel (39). The wastewater discharge module 140 is used to discharge the unqualified water obtained when rinsing the expansion vessel 37 to the atmospheric expansion vessel (39). The second end of the atmospheric expansion vessel (39) is connected to the second output end of the boiler water recirculation module 110 and the input end of the condenser (40).

[0105] Please continue reading Figure 2 According to one embodiment of this application, the wastewater discharge module 140 includes: an isolation valve (21), an electric gate valve (22), and a drainage pipe disposed between the first output end of the drainage expansion module 120 and the output end of the heat exchange deoxygenation module 130, wherein the isolation valve (21) and the electric gate valve (22) are connected in series on the drainage pipe.

[0106] Please continue reading Figure 2 According to one embodiment of this application, the heat exchange deoxygenation module 130 includes a heat exchange unit 132 and a deoxygenation unit 134. The first input terminal of the heat exchange unit 132 is connected to the first output terminal of the hydrophobic expansion module 120, the second input terminal of the heat exchange unit 132 is connected to the output terminal of the No. 5 low-temperature heater, the first output terminal of the heat exchange unit 132 is connected to the output terminal of the deoxygenation unit 134, and the second output terminal of the heat exchange unit 132 is connected to the first input terminal of the deoxygenation unit 134.

[0107] In some embodiments, the second input terminal of the deaeration unit 134 is connected to the second output terminal of the hydrophobic expansion module 120, and the output terminal of the deaeration unit 134 is also connected to the first output terminal of the boiler water recirculation module 110; the heat exchange unit 132 is used to exchange heat with the saturated condensate remaining after the expansion and vaporization of wet water and the condensate from the No. 5 low-temperature heater to obtain subcooled water, which then enters the deaeration unit 134. The deaeration unit 134 is used to recover the subcooled water.

[0108] Please continue reading Figure 2 According to one embodiment of this application, the heat exchange unit 132 includes: an electric gate valve (14), an electric regulating valve (15), a water-to-water heat exchanger (16), an electric gate valve (18), an electric gate valve (19), and an electric regulating valve (20).

[0109] In some embodiments, the electric gate valve (14), the electric regulating valve (15), and the water-to-water heat exchanger (16) are connected in series between the first output end of the hydrophobic expansion module 120 and the output end of the deoxygenation unit 134. The first input end of the water-to-water heat exchanger (16) is connected to the first end of the electric gate valve (18), and the first output end of the water-to-water heat exchanger (16) is connected to the first end of the electric gate valve (19).

[0110] In some embodiments, the second end of the electric gate valve (18) is connected to the first end of the electric regulating valve (20) and the input end of the No. 5 cryogenic heater, and the second end of the electric gate valve (19) is connected to the second end of the electric regulating valve (20) and the first input end of the deoxygenation unit 134.

[0111] Please continue reading Figure 2 According to one embodiment of this application, the deaeration unit 134 includes: a deaerator (38), an energy dissipation device (17), and a drain pipe disposed between the output end of the deaerator (38) and the first output end of the boiler water recirculation module 110.

[0112] In some embodiments, the energy dissipation device (17) is disposed at the output end of the deaerator (38) and inside the deaerator (38), the output end of the deaerator (38) is connected to the first output end of the heat exchange unit 132 and the first output end of the boiler water recirculation module 110.

[0113] In some embodiments, after the wet water enters the expansion container (37) and vaporizes, the saturated water at the bottom enters the water-to-water heat exchanger (16) and is cooled into slightly subcooled water by the condensate from the No. 5 low-temperature heater and enters the deaerator (38). The pipeline is sequentially equipped with an electric gate valve (14), an electric regulating valve (15), a water-to-water heat exchanger (16), and an energy dissipation device (17).

[0114] In some embodiments, the condensate from the outlet of the No. 5 cryogenic heater is bypassed and enters the deaerator (38) after heat exchange through a water-to-water heat exchanger (16). A first electric gate valve (18) and a second electric gate valve (19) are sequentially installed on the bypass pipeline.

[0115] In some embodiments, a pipeline is led out from the outlet drain pipe of the expansion tank (37) to the deaerator (38) drain pipe. When the coal-fired power unit starts to flush the expansion tank (37), the unqualified water is discharged to the atmospheric expansion tank (39) through this pipeline. An isolation valve (21) and an electric gate valve (22) are installed on this pipeline.

[0116] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0117] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0118] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the above embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A combined dry-wet state conversion system for an ultra-supercritical boiler under all operating conditions, comprising: The system comprises a water storage tank (35), an economizer (32), a water-cooled wall (33), and a separator (34), characterized in that the system further includes: a boiler water recirculation module, a condensate expansion module, a heat exchange deoxygenation module, a low-temperature heater, and a high-temperature heater; The input end of the water-cooled wall (33) is connected to the output end of the economizer (32), the output end of the water-cooled wall (33) is connected to the input end of the separator (34), and the output end of the separator (34) is connected to the input end of the water storage tank (35). The first output end of the water storage tank (35) is connected to the input end of the boiler water recirculation module, the second output end of the water storage tank (35) is connected to the input end of the drainage expansion module, and the output end of the boiler water recirculation module is connected to the input end of the economizer (32). The first output terminal of the hydrophobic expansion module is connected to the first input terminal of the heat exchange and deoxygenation module, the second output terminal of the hydrophobic expansion module is connected to the second input terminal of the heat exchange and deoxygenation module, the third output terminal of the hydrophobic expansion module is connected to the input terminal of the high-temperature heater, and the third input terminal of the heat exchange and deoxygenation module is connected to the output terminal of the low-temperature heater. The boiler water recirculation module is used to recirculate the wet water separated by the separator (34); The hydrophobic expansion module is used to expand and vaporize wet water after de-cooling and de-pressurizing to obtain secondary steam. The heat exchange and deoxygenation module is used to exchange heat between the saturated condensate remaining after the expansion and vaporization of wet water and the condensate from the low-temperature heater to obtain subcooled water, which then enters the heat exchange and deoxygenation module.

2. The ultra-supercritical boiler full-condition composite dry-wet state conversion system according to claim 1, characterized in that, The system also includes a high-pressure heater (36), and the boiler water recirculation module includes: a control unit, a low-flow recirculation unit, and a subcooling tube unit; The first output end of the water storage tank (35) is connected to the input end of the control unit, and the second output end of the water storage tank (35) is connected to the input end of the hydrophobic expansion module. The water storage tank (35) is used to store the wet water separated by the separator (34). The input terminal of the control unit is also connected to the first terminal of the small flow recirculation unit and the output terminal of the subcooling tube unit. The first output terminal of the control unit is connected to the input terminal of the economizer (32), and the second output terminal of the control unit is connected to the second terminal of the small flow recirculation unit. The control unit is used to control the circulation of wet water in the water storage tank (35), and the small flow recirculation unit is used to recirculate the wet water at a preset flow rate. The input end of the subcooled tube unit is connected to the output end of the high-pressure heater (36), and the output end of the high-pressure heater (36) is also connected to the input end of the economizer (32).

3. The ultra-supercritical boiler full-condition composite dry-wet state conversion system according to claim 2, characterized in that, The control unit includes: an electric gate valve (23), a boiler water circulation pump (24), a flow measurement device (25), a check valve (26), an electric regulating valve (27), and a second electric gate valve (28). An electric gate valve (23), a boiler water circulation pump (24), a flow measurement device (25), a check valve (26), an electric regulating valve (27), and a second electric gate valve (28) are connected in series between the first output end of the water storage tank (35) and the input end of the economizer (32). The boiler water circulation pump (24) is used to circulate the wet water in the water storage tank (35).

4. The ultra-supercritical boiler full-condition composite dry-wet state conversion system according to claim 3, characterized in that, The low-flow recirculation unit includes: an electric gate valve (29) and a flow measurement device (30). The first end of the electric gate valve (29) is connected to the output end of the boiler water circulation pump (24), the second end of the electric gate valve (29) is connected to the first end of the flow measuring device (30), and the second end of the flow measuring device (30) is connected to the first end of the electric gate valve (23).

5. The ultra-supercritical boiler full-condition composite dry-wet state conversion system according to claim 2, characterized in that, The subcooling pipe unit includes: an electric gate valve (31) and a subcooling pipe disposed between the first output end of the water storage tank (35) and the output end of the high-pressure heater (36), wherein the electric gate valve (31) is disposed on the subcooling pipe.

6. The ultra-supercritical boiler full-condition composite dry-wet state conversion system according to claim 1, characterized in that, The hydrophobic expansion module includes: a de-temperature and de-pressure unit, an expansion container (37), a first steam delivery unit, and a second steam delivery unit; The input end of the de-temperature and pressure reducing unit is connected to the second output end of the boiler water recirculation module, and the output end of the de-temperature and pressure reducing unit is connected to the input end of the expansion container (37). The de-temperature and pressure reducing unit is used to de-temperature and pressure reduce the wet water and then transport it to the expansion container (37). The first output end of the expansion container (37) is connected to the first input end of the heat exchange and deoxygenation module, the second output end of the expansion container (37) is connected to the input end of the first steam conveying unit, and the third output end of the expansion container (37) is connected to the input end of the second steam conveying unit. The expansion container (37) is used to expand and vaporize the de-cooled and depressurized wet water to obtain secondary steam. The output end of the first steam delivery unit is connected to the second input end of the heat exchange and deoxygenation module, and the output end of the second steam delivery unit is connected to the input end of the high-temperature heater.

7. The ultra-supercritical boiler full-condition composite dry-wet state conversion system according to claim 6, characterized in that, The de-heating and pressure reducing unit includes: an electric gate valve (1), an isolation valve (2), a flow measuring device (3), a small flow 361 valve (4), and a multi-stage flow limiting device (5); An electric gate valve (1), an isolation valve (2), a flow measurement device (3), a small flow 361 valve (4), and a multi-stage flow limiting device (5) are connected in series between the second output end of the boiler water recirculation module and the input end of the expansion vessel (37).

8. The ultra-supercritical boiler full-condition composite dry-wet state conversion system according to claim 6, characterized in that, The first steam delivery unit includes: an isolation valve (6), an electric regulating valve (7), an electric gate valve (8), and a check valve (9); Isolation valve (6), electric regulating valve (7), electric gate valve (8) and check valve (9) are connected in series between the second output terminal of the hydrophobic expansion module and the input terminal of the high-temperature heater.

9. The ultra-supercritical boiler full-condition composite dry-wet state conversion system according to claim 8, characterized in that, The second steam delivery unit includes: an isolation valve (10), an electric regulating valve (11), an electric gate valve (12), and a check valve (13); Isolation valve (10), electric regulating valve (11), electric gate valve (12) and check valve (13) are connected in series between the second output end of the hydrophobic expansion module and the second input end of the heat exchange deoxygenation module. The first end of the isolation valve (10) is connected to the first end of the isolation valve (6).

10. The ultra-supercritical boiler full-condition composite dry-wet state conversion system according to claim 6, characterized in that, The system also includes a wastewater discharge module, an atmospheric expansion tank (39), and a condenser (40). The input end of the wastewater discharge module is connected to the first output end of the expansion container (37), and the output end of the wastewater discharge module is connected to the first end of the atmospheric expansion container (39). The wastewater discharge module is used to discharge the unqualified water obtained when rinsing the expansion container (37) to the atmospheric expansion container (39). The second end of the atmospheric expansion vessel (39) is connected to the first output end of the boiler water recirculation module and the input end of the condenser (40).

11. The ultra-supercritical boiler full-condition composite dry-wet state conversion system according to claim 10, characterized in that, The wastewater discharge module includes: an isolation valve (21), an electric gate valve (22), and a drainage pipe disposed between the first output end of the drainage expansion module and the output end of the heat exchange deoxygenation module; the isolation valve (21) and the electric gate valve (22) are connected in series on the drainage pipe.

12. The ultra-supercritical boiler full-condition composite dry-wet state conversion system according to claim 1, characterized in that, The heat exchange and deoxygenation module includes: a heat exchange unit and a deoxygenation unit; The first input terminal of the heat exchange unit is connected to the first output terminal of the hydrophobic expansion module, the second input terminal of the heat exchange unit is connected to the output terminal of the low-temperature heater, the first output terminal of the heat exchange unit is connected to the output terminal of the deoxygenation unit, and the second output terminal of the heat exchange unit is connected to the first input terminal of the deoxygenation unit. The second input terminal of the deoxygenation unit is connected to the second output terminal of the hydrophobic expansion module, and the output terminal of the deoxygenation unit is also connected to the first output terminal of the boiler water recirculation module. The heat exchange unit is used to exchange heat with the saturated condensate remaining after the expansion and vaporization of wet water and the condensate from the low-temperature heater to obtain subcooled water, which then enters the deoxygenation unit; the deoxygenation unit is used to recover the subcooled water.

13. The ultra-supercritical boiler full-condition composite dry-wet state conversion system according to claim 12, characterized in that, The heat exchange unit includes: an electric gate valve (14), an electric regulating valve (15), a water-to-water heat exchanger (16), an electric gate valve (18), an electric gate valve (19), and an electric regulating valve (20). An electric gate valve (14), an electric regulating valve (15), and a water-to-water heat exchanger (16) are connected in series between the first output end of the hydrophobic expansion module and the output end of the deoxygenation unit. The first input end of the water-to-water heat exchanger (16) is connected to the first end of the electric gate valve (18), and the first output end of the water-to-water heat exchanger (16) is connected to the first end of the electric gate valve (19). The second end of the electric gate valve (18) is connected to the first end of the electric regulating valve (20) and the input end of the low-temperature heater, and the second end of the electric gate valve (19) is connected to the second end of the electric regulating valve (20) and the first input end of the deoxygenation unit.

14. The ultra-supercritical boiler full-condition composite dry-wet state conversion system according to claim 12, characterized in that, The deaeration unit includes: a deaerator (38), an energy dissipation device (17), and a drain pipe disposed between the output end of the deaerator (38) and the first output end of the boiler water recirculation module. The energy dissipation device (17) is located at the output end of the deaerator (38) and inside the deaerator (38). The output end of the deaerator (38) is connected to the first output end of the heat exchange unit and the first output end of the boiler water recirculation module.

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