No.0 high-pressure heater system suitable for low-load heat supply of unit

Abstract

The invention discloses a No.0 high-pressure heater system suitable for low-load heat supply of a unit, which comprises a No.0 high-pressure heating steam trap and a No.0 high-pressure heater external steam cooler, and the No.0 high-pressure heater external steam cooler is configured to receive high-temperature steam of a high-pressure cylinder of a steam turbine. The high-temperature steam is used for heating feed water passing through the 0 # high-pressure heater external steam cooler, so that the high-temperature steam is cooled into low-temperature steam, the 0 # high-pressure heating steam trap is configured to receive the low-temperature steam from the 0 # high-pressure heater external steam cooler, and the low-temperature steam is used for heating the feed water passing through the 0 # high-pressure heater external steam cooler; the low-temperature steam is cooled into condensed water; and when the ultra-supercritical unit operates at low load, the No.0 high-pressure heating steam trap is stopped, and low-temperature steam in the No.0 high-pressure heating external steam cooler is guided to the outside, so that external heat supply is realized. According to the system, full-load switching of a steam source of the 0 # high-pressure heater is achieved, the requirement for external heat supply with lower loads can be met, and good economic benefits are achieved.

Description

Technical Field

[0001] The present application relates to a high-pressure heater system, and in particular to a No. 0 high-pressure heater system adapted to low-load heating of a unit. Background Art

[0002] The existing supercritical units have reduced steam extraction capacity and reduced steam extraction pressure when operating at low load, which cannot meet the external heat supply demand when the units are at low load.

[0003] In an ultra-supercritical unit using a specific steam turbine type, a No. 0 high-pressure heater is added to the original heat recovery system, and the steam in the steam turbine is extracted using the unique steam supplement valve interface of the unit's steam turbine for the feed water in the No. 0 high-pressure heater, thereby achieving the purpose of increasing the feed water temperature. However, the existing ultra-supercritical units have a reduced steam extraction capacity and a reduced steam extraction pressure when running at low load, which cannot meet the external heat supply demand of the unit at low load.

[0004] Figure 1 The No. 0 high-pressure heating system of the prior art is shown. However, the No. 0 high-pressure heating system of the prior art has the following problems: (1) The prior art is only suitable for heating feed water and cannot be used in conjunction with heat supply; (2) The No. 0 high-pressure heater of the prior art has only one steam source interface and cannot implement steam source switching at full load of the unit.

[0005] Therefore, there is an urgent need in this field to develop a No. 0 high-pressure heater system that is suitable for low-load heating of the unit. While ensuring the safe operation of the unit, it can increase the feed water temperature of the unit, thereby improving the heat recovery efficiency of the entire power plant. At the same time, it can be well coupled with the heating demand to achieve full-load switching of the No. 0 high-pressure heater steam source, and can achieve lower load external heating needs, with good economic benefits. Summary of the invention

[0006] The purpose of the present application is to provide a No. 0 high-pressure heater system suitable for low-load heating of the unit, which increases the feed water temperature of the unit while ensuring the safe operation of the unit, thereby improving the heat recovery efficiency of the entire power plant, and at the same time can be well coupled with the heating demand, realize the full-load switching of the steam source of the No. 0 high-pressure heater, can achieve lower load external heating needs, and has good economic benefits.

[0007] The present application provides a No. 0 high-pressure heater system adapted to low-load heating of a unit, wherein the No. 0 high-pressure heater system is applied to an ultra-supercritical unit, wherein the ultra-supercritical unit comprises: an ultra-supercritical boiler, a boiler economizer, a steam turbine high-pressure cylinder, and a feed water pump, wherein a main steam pipeline for conveying main steam to the steam turbine high-pressure cylinder is arranged between the ultra-supercritical boiler and the steam turbine high-pressure cylinder, and a feed water pipeline for conveying feed water to the boiler economizer is arranged between the feed water pump and the boiler economizer.

[0008] The steam turbine high-pressure cylinder includes a No. 0 steam extraction interface, the No. 0 high-pressure heater system includes a No. 0 high-pressure heating steam trap and a No. 0 high-pressure heater external steam cooler, and one end of the No. 0 high-pressure heater external steam cooler is connected to the boiler economizer through a first water supply pipeline section;

[0009] The No. 0 high pressure heater external steam cooler is configured to receive high temperature steam from the high pressure cylinder of the steam turbine, the high temperature steam is used to heat the feed water passing through the No. 0 high pressure heater external steam cooler, so that the high temperature steam is cooled into low temperature steam, and the No. 0 high pressure heating steam trap is configured to receive low temperature steam from the No. 0 high pressure heater external steam cooler, the low temperature steam is used to heat the feed water passing through the No. 0 high pressure heating steam trap, and the low temperature steam is cooled into condensate;

[0010] When the ultra-supercritical unit is running at low load, the No. 0 high-pressure heating steam trap is deactivated, and the low-temperature steam in the No. 0 high-pressure external steam cooler is guided to the outside to realize external heat supply.

[0011] In another preferred example, the low load operation refers to the ultra-supercritical unit operating below a load in the range of 40% load to 50% load.

[0012] In another preferred example, when the ultra-supercritical unit is running at high load, the No. 0 high-pressure heating steam trap is activated, and at this time the No. 0 high-pressure heating steam trap receives low-temperature steam from the No. 0 high-pressure external steam cooler.

[0013] In another preferred embodiment, the temperature of the high-temperature steam is between 500 degrees Celsius and 550 degrees Celsius.

[0014] In another preferred embodiment, the temperature of the low-temperature steam is between 300 degrees Celsius and 350 degrees Celsius.

[0015] In another preferred example, when the ultra-supercritical unit is operating at a load of more than 50%, the feed water provided by the feed water pump is heated in turn by the No. 0 high-pressure heating steam trap and the No. 0 high-pressure external steam cooler.

[0016] In another preferred example, the No. 0 high-pressure heating steam trap and the No. 0 high-pressure external steam cooler are located downstream of the water feed pump and are arranged on the water feed pipeline.

[0017] In another preferred example, the No. 0 high-pressure heater system is also provided with a water supply bypass pipe and a bypass shut-off valve arranged on the water supply bypass pipe. When the bypass shut-off valve is open, the No. 0 high-pressure heating steam trap is disabled, and when the bypass shut-off valve is closed, the No. 0 high-pressure heating steam trap is enabled.

[0018] In another preferred example, a first shut-off valve is provided between the No. 0 high-pressure heating steam trap and the inlet end of the water supply bypass pipe, and when the ultra-supercritical unit is operated at a load of more than 50%, the first shut-off valve is in an open state.

[0019] In another preferred example, the inlet end of the water supply bypass pipe is connected to the water supply pipe section between the high-pressure heater and the No. 0 high-pressure heating steam trap, and the outlet end of the water supply bypass pipe is connected to the water supply pipe section between the No. 0 high-pressure heating steam trap and the No. 0 high-pressure heater external steam cooler.

[0020] In another preferred example, the system also includes a steam supply channel, on which a steam shut-off valve is arranged, one end of the steam supply channel is connected to the outlet of the No. 0 high-pressure heating external steam cooler, and the other end of the steam supply channel is connected to the No. 0 high-pressure heating steam trap.

[0021] In another preferred example, the system further comprises an external heating steam channel, an inlet end of the external heating steam channel is connected to the steam supply channel and is located upstream of the steam shut-off valve, and an outlet end of the external heating steam channel is connected to an external device.

[0022] In another preferred example, when the ultra-supercritical unit is operating at low load, the steam shut-off valve is in a closed state, and the low-temperature steam at the outlet of the No. 0 high-pressure external steam cooler is transported to the external equipment through the external heating steam channel.

[0023] In another preferred example, when the ultra-supercritical unit is operating below 40% load, the bypass shut-off valve is in an open state, the first shut-off valve is in a closed state, and the feed water provided by the feed water pump passes through the one or more high-pressure heaters, the feed water bypass pipeline and the No. 0 high-pressure heater external steam cooler in sequence.

[0024] In another preferred embodiment, when the ultra-supercritical unit operates at a load of more than 50%, the steam shut-off valve is in an open state.

[0025] In another preferred example, a supplementary steam valve interface is provided on the high-pressure cylinder of the steam turbine, and the system further comprises a first supplementary steam channel, one end of which is connected to the main steam pipeline, and the other end of which is connected to the supplementary steam valve interface.

[0026] In another preferred example, the system further includes a spare steam supply channel, one end of which is connected to the first steam supply channel, and the other end of which is connected to the steam extraction channel between the No. 0 steam extraction interface of the high-pressure cylinder of the steam turbine and the No. 0 high-pressure heater external steam cooler.

[0027] In another preferred example, when the ultra-supercritical unit is operating at 20% load-30% load, when the pressure of the 0 steam extraction interface cannot meet the external heating demand, the standby steam supplementary channel is activated. At this time, the steam inlet source of the No. 0 high-pressure heater external steam cooler comes from the 0 steam extraction interface and the first steam supplementary channel.

[0028] In another preferred example, a second shut-off valve is provided on the standby supplementary steam passage.

[0029] It should be understood that within the scope of the present invention, the above-mentioned technical features of the present invention and the technical features specifically described below (such as embodiments) can be combined with each other to form a new or preferred technical solution. Due to space limitations, they will not be described one by one here. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. It should be understood that the drawings described below are only some implementation examples of the present invention, and ordinary technicians in this field can also obtain other implementation examples based on these drawings without paying creative work.

[0031] Figure 1 It is a structural schematic diagram of a No. 0 high-pressure heating system in the prior art;

[0032] Figure 2 It is a structural schematic diagram of a No. 0 high-pressure heater system adapted for low-load heating of a unit according to the present application.

[0033] In the accompanying drawings, the following are marked:

[0034] 10-Ultra-supercritical boiler

[0035] 11-Boiler economizer

[0036] 12-Steam turbine high pressure cylinder

[0037] 121-0 Steam extraction interface

[0038] 122-Steam supply valve interface

[0039] 13-Water supply pump

[0040] 14- Main steam pipeline

[0041] 15-Deaerator

[0042] 20-High voltage heater

[0043] No. 21-0 High Pressure Heating Steam Trap

[0044] 22-0 High Pressure Heater External Steam Cooler

[0045] 30-External heating steam channel

[0046] 31-Steam supply channel

[0047] 32-Steam shut-off valve

[0048] 41-First steam supply channel

[0049] 42-Standby steam supply channel

[0050] 43-Second shut-off valve

[0051] 44-Supplemental steam valve

[0052] 50-Water supply bypass pipeline

[0053] 51-Bypass shut-off valve

[0054] 60-First water supply pipeline section DETAILED DESCRIPTION

[0055] Through extensive and in-depth research, the inventors have developed for the first time a No. 0 high-pressure heater system suitable for low-load heating of the unit. The conventional No. 0 high-pressure heater of the system is divided into a No. 0 high-pressure heater external steam cooler and a No. 0 high-pressure heating steam trap. When the load of the unit is above 50%, the No. 0 high-pressure heater external steam cooler and the No. 0 high-pressure heating steam trap normally heat the feed water. When the load of the unit is below 40%, the No. 0 high-pressure heating steam trap is bypassed by the feed water bypass, and only the No. 0 high-pressure heater external steam cooler is retained to heat the feed water. The low-temperature steam at the outlet of the No. 0 high-pressure heater external steam cooler is used for external heating; at a lower load of 20%-30%, when the pressure of the No. 0 extraction steam interface cannot meet the external heating demand, the steam inlet source of the No. 0 high-pressure heater external steam cooler can be switched to the steam supplement valve interface, which can further increase the outlet steam pressure of the No. 0 high-pressure heater external steam cooler, so as to meet the external heating demand at full load. The system of the present application has the characteristics of economy, safety, reliability and environmental protection, and has a good promotion prospect for the heating transformation of supercritical (ultracritical) operating units and the external heating of newly built units.

[0056] In the following description, many technical details are provided to help readers better understand the present application. However, those skilled in the art can understand that the technical solution claimed in the present application can be implemented even without these technical details and various changes and modifications based on the following embodiments.

[0057] the term

[0058] As used herein, "ultra-supercritical unit" and "unit" are used interchangeably;

[0059] High-pressure heater: It is a device that uses part of the steam turbine's exhaust air to heat the feed water. The device consists of two major parts: a shell and a pipe system. A steam cooling section is set at the upper part of the shell cavity, a drainage cooling section is set at the lower part, and a feed water inlet and a feed water outlet are set at the top of the inlet and outlet pipes. When superheated steam enters the shell from the inlet, it can heat the feed water in the upper heat exchange tube. After the steam condenses into water (or water vapor), the condensed hot water (or steam) can heat the feed water in the lower drainage cooling section. The condensed water after use flows out of the body through the drainage outlet.

[0060] It should be noted that in the application documents of this patent, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "including one" do not exclude the existence of other identical elements in the process, method, article or device including the elements. In the application documents of this patent, if it is mentioned that an action is performed according to an element, it means that the action is performed at least according to the element, which includes two situations: performing the action only according to the element, and performing the action according to the element and other elements. Expressions such as multiple, multiple, and multiple include 2, 2 times, 2 kinds, and more than 2, more than 2 times, and more than 2 kinds.

[0061] In the present invention, all directional indications (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0062] This application has at least one of the following advantages

[0063] (a) The system of the present application divides the No. 0 high-pressure heater into the No. 0 high-pressure heater external steam cooler and the No. 0 high-pressure heating steam trap. When the unit load is above 50%, the No. 0 high-pressure heater external steam cooler and the No. 0 high-pressure heating steam trap normally heat the feed water. When the unit load is below 40%, the No. 0 high-pressure heating steam trap is bypassed by the feed water bypass, and only the No. 0 high-pressure heater external steam cooler is retained to heat the feed water. The outlet steam of the No. 0 high-pressure heater external steam cooler is used for external heat supply, which can solve the problem of insufficient heating capacity at low load faced by the current unit;

[0064] (b) The system of the present application avoids the de-temperature and de-pressure reduction of high-pressure steam under low load of the unit through the external steam cooler of No. 0 high-pressure heater and the No. 0 high-pressure heating steam trap, realizes the utilization of energy gradient and reduces the heat consumption of the unit;

[0065] (c) The system of the present application uses the No. 0 extraction steam interface and the steam supply valve extraction steam port as the extraction steam source of the No. 0 high-pressure heater system, which can realize the full-load switching of the No. 0 high-pressure heater extraction steam source; the pressure of the No. 0 extraction steam is well guaranteed to further ensure the temperature of the heating feed water;

[0066] (d) For ultra-supercritical units with supplementary steam valves, the system of the present application can retain the original supplementary steam valves while adding a zero extraction steam interface, thereby avoiding the negative impact on the operation of the unit caused by the removal of the supplementary steam valves;

[0067] (e) The system of the present application has wide applicability and is applicable to various types of steam turbines.

[0068] A No. 0 high-pressure heater system suitable for low-load heating of units

[0069] The No. 0 high-pressure heater system adapted to low-load heating of the unit of the present application divides the conventional No. 0 high-pressure heater into a No. 0 high-pressure heater external steam cooler 22 and a No. 0 high-pressure steam trap 21. The No. 0 high-pressure heater external steam cooler 22 is configured to receive high-temperature steam from the high-pressure cylinder 12 of the steam turbine, and the high-temperature steam is used to heat the feed water passing through the No. 0 high-pressure heater external steam cooler 22, so that the high-temperature steam is cooled into low-temperature steam. The No. 0 high-pressure heating steam trap 21 is configured to receive low-temperature steam from the No. 0 high-pressure heater external steam cooler 22, and the low-temperature steam is used to heat the feed water passing through the No. 0 high-pressure heating steam trap 21, and the low-temperature steam is cooled into condensed water, and the condensed water flows out through the water outlet of the No. 0 high-pressure heating steam trap 21;

[0070] When the unit load is above 50%, the No. 0 high-pressure steam cooler and the No. 0 high-pressure steam trap heat the feed water normally. When the unit load is below 40%, the No. 0 high-pressure steam trap is bypassed by the feed water bypass, and only the No. 0 high-pressure steam cooler is retained to heat the feed water. The outlet steam of the No. 0 high-pressure steam cooler is used for external heat supply. At a lower load of 20%-30%, when the pressure of the No. 0 steam extraction interface cannot meet the external heat supply demand, the steam source of the No. 0 high-pressure steam cooler can come from the steam supplement valve interface and the No. 0 steam extraction interface at the same time, which can further increase the outlet steam pressure of the No. 0 high-pressure steam cooler and meet the external heat supply demand at full load.

[0071] The system of the present application is a new technology for the No. 0 high-pressure heater system that is suitable for low-load heating of the unit. While ensuring the safe operation of the unit, it increases the feed water temperature of the unit, thereby improving the heat recovery efficiency of the entire power plant. At the same time, it can be well coupled with the heating demand to achieve full-load switching of the steam source of the No. 0 high-pressure heater, and can achieve lower load external heating needs, with good economic benefits.

[0072] In the supercritical unit reheat system, the extraction steam source of the No. 0 high-pressure heater system comes from both the No. 0 extraction steam interface and the supplementary steam valve interface of the steam turbine, so that the full-load switching of the No. 0 high-pressure heater steam source is achieved to ensure the extraction steam pressure of the No. 0 high-pressure heater system;

[0073] Compared with the No. 0 high-pressure heater feed water in the prior art, the present application is applicable to a wider range of steam turbine types and has higher safety and reliability. It can be generally applicable to supercritical (ultracritical) operating units that currently have heating modification needs or supercritical (ultracritical) newly built units that have heating needs.

[0074] To make the purpose, technical solution and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings. It should be understood that these are only some examples that the present invention may take for the reader, but are not intended to limit the scope of the present invention.

[0075] Example

[0076] See also Figure 2 The present application provides a No. 0 high-pressure heater system suitable for low-load heating of the unit, which is a part of the thermal cycle system of the steam turbine power generation. The system mainly includes a boiler, a boiler economizer 11, a No. 0 high-pressure heating steam trap 21 and a No. 0 high-pressure external steam cooler 22, a deaerator 15, a feed water pump 13, other high-pressure heaters 20 in the heat recovery system, a feed water pipe system, a steam pipe system and related valves, a steam supplement valve system, and a heating system;

[0077] Specifically, this embodiment provides a No. 0 high-pressure heater system adapted to low-load heating of the unit, and the No. 0 high-pressure heater system is applied to an ultra-supercritical unit, which includes: an ultra-supercritical boiler 10, a boiler economizer 11, a steam turbine high-pressure cylinder 12, and a feed water pump 13. A main steam pipeline 14 for conveying main steam to the steam turbine high-pressure cylinder 12 is provided between the ultra-supercritical boiler 10 and the steam turbine high-pressure cylinder 12, and a feed water pipeline for conveying feed water to the boiler economizer 11 is provided between the feed water pump 13 and the boiler economizer 11. A main steam valve is provided on the main steam pipeline.

[0078] The steam turbine high-pressure cylinder 12 includes a steam extraction interface 121, and the high-pressure heater system includes a high-pressure heating steam trap 21 and a high-pressure heater external steam cooler 22. The high-pressure heater external steam cooler 22 and the high-pressure heating steam trap 21 are located downstream of the feed water pump 13. The first end of the high-pressure heater external steam cooler 22 is connected to the boiler economizer 11 through the first feed water pipeline section 60, and the second end of the high-pressure heater external steam cooler 22 is connected to the steam extraction interface 121 through the steam extraction pipeline to receive steam from the steam extraction interface 121 to heat the feed water in the high-pressure heater external steam cooler 22. A regulating valve is provided on the steam extraction pipeline.

[0079] The No. 0 high-pressure external steam cooler 22 is configured to receive high-temperature steam from the high-pressure cylinder 12 of the steam turbine, and the high-temperature steam is used to heat the feed water passing through the No. 0 high-pressure external steam cooler 22, so that the high-temperature steam is cooled into low-temperature steam. The No. 0 high-pressure heating steam trap 21 is configured to receive low-temperature steam from the No. 0 high-pressure external steam cooler 22, and the low-temperature steam is used to heat the feed water passing through the No. 0 high-pressure heating steam trap 21, and the low-temperature steam is cooled into condensate.

[0080] When the ultra-supercritical unit is operating at low load, the No. 0 high-pressure heating steam trap 21 is disabled, and the low-temperature steam in the No. 0 high-pressure external steam cooler 22 is guided to the outside to achieve external heat supply. Preferably, low-load operation refers to the ultra-supercritical unit operating below the load in the range of 40% load-50% load, for example, the unit operates at 40% load. When the ultra-supercritical unit is operating at high load, the No. 0 high-pressure heating steam trap 21 is enabled, and the No. 0 high-pressure heating steam trap 21 receives the low-temperature steam from the No. 0 high-pressure external steam cooler 22. Preferably, the temperature of the high-temperature steam is 500 degrees Celsius-550 degrees Celsius. The temperature of the low-temperature steam is 300 degrees Celsius-350 degrees Celsius.

[0081] The No. 0 high-pressure heater system is also provided with a water supply bypass pipe 50 and a bypass shut-off valve 51 arranged on the water supply bypass pipe. When the bypass shut-off valve 51 is open, the No. 0 high-pressure heating steam trap 21 is disabled, and when the bypass shut-off valve 51 is closed, the No. 0 high-pressure heating steam trap 21 is enabled.

[0082] The inlet end of the feedwater bypass pipe 50 is connected to the feedwater pipe section between one or more other high-pressure heaters 20 and the No. 0 high-pressure heating steam trap 21, and the outlet end of the feedwater bypass pipe 50 is connected to the feedwater pipe section between the No. 0 high-pressure heating steam trap 21 and the No. 0 high-pressure external steam cooler 22. A first shut-off valve is provided between the No. 0 high-pressure heating steam trap 21 and the inlet end of the feedwater bypass pipe 50. When the ultra-supercritical unit is operated at a load of more than 50%, the first shut-off valve is in an open state, that is, the No. 0 high-pressure heating steam trap 21 is enabled.

[0083] The system also includes a steam supply channel 31 and an external heating steam channel 30. A steam shut-off valve 32 is provided on the steam supply channel 31. One end of the steam supply channel 31 is connected to the outlet of the No. 0 high-pressure external steam cooler 22, and the other end of the steam supply channel 31 is connected to the No. 0 high-pressure heating steam trap 21. The inlet end of the external heating steam channel 30 is connected to the steam supply channel 31 and is located upstream of the steam shut-off valve 32, and the outlet end of the external heating steam channel 30 is connected to an external device.

[0084] A steam supplement valve interface 122 is provided on the high-pressure cylinder 12 of the steam turbine. The system also includes a first steam supplement channel 41 and a standby steam supplement channel 42. One end of the first steam supplement channel 41 is connected to the main steam pipeline 13, and the other end of the first steam supplement channel 41 is connected to the steam supplement valve interface 122. One end of the standby steam supplement channel 42 is connected to the first steam supplement channel 41, and the other end of the standby steam supplement channel 42 is connected to the steam extraction channel between the steam extraction interface 121 of the high-pressure cylinder of the steam turbine and the external steam cooler 22 of the No. 0 high-pressure heater. The standby steam supplement channel 42 connected to the first steam supplement channel 41 and the steam extraction channel (from the steam extraction interface 121) are standby steam sources for each other. A second shut-off valve 43 is provided on the standby steam supplement channel 42, and a steam supplement valve 44 is provided on the first steam supplement channel 41.

[0085] When the ultra-supercritical unit is operating at 20% load-30% load, when the pressure of the No. 0 steam extraction interface 121 cannot meet the external heating demand, the standby steam supply channel 42 is activated. At this time, the steam supply source of the No. 0 high-pressure heater external steam cooler 22 comes from the No. 0 steam extraction interface 121 and the first steam supply channel 41.

[0086] When the ultra-supercritical unit is operated at a low load, for example, below 40% load, the bypass shut-off valve 51 is in an open state, the first shut-off valve is in a closed state, the No. 0 high-pressure heating steam trap 21 is deactivated, and the feed water provided by the feed water pump 13 passes through one or more other high-pressure heaters 20, the feed water bypass pipeline 50, and the No. 0 high-pressure external steam cooler 22 in sequence. At this time, the steam shut-off valve 32 is in a closed state, and steam is no longer delivered to the No. 0 high-pressure heating steam trap 21. The low-temperature steam at the outlet of the No. 0 high-pressure external steam cooler 22 is delivered to the external equipment through the external heating steam channel 30.

[0087] When the ultra-supercritical unit is operated at a load of more than 50%, the feed water provided by the feed water pump 13 is heated in sequence through one or more other high-pressure heaters 20, No. 0 high-pressure heating steam trap 21 and No. 0 high-pressure external steam cooler 22. Among them, the first shut-off valve is in an open state, and the bypass shut-off valve 51 is in a closed state. At this time, the No. 0 high-pressure heating steam trap is in an enabled state, and the steam shut-off valve 32 is in an open state. The steam from the No. 0 high-pressure external steam cooler can not only supply heat to external equipment through the external heat supply channel 30, but also supply steam to the No. 0 high-pressure heating steam trap 21 to heat the feed water in the No. 0 high-pressure heating steam trap 21.

[0088] A large number of technical features are recorded in the specification of this application, which are distributed in various technical solutions. If all possible combinations of technical features of this application (i.e., technical solutions) are to be listed, the specification will be too long. In order to avoid this problem, the various technical features disclosed in the above-mentioned invention content of this application, the various technical features disclosed in the various embodiments and examples below, and the various technical features disclosed in the accompanying drawings can be freely combined with each other to form various new technical solutions (these technical solutions are all deemed to have been recorded in this specification), unless the combination of such technical features is technically infeasible. For example, in one example, feature A+B+C is disclosed, and in another example, feature A+B+D+E is disclosed, and features C and D are equivalent technical means that play the same role. Technically, only one can be used, and it is impossible to use them at the same time. Feature E can be combined with feature C technically. Then, the solution of A+B+C+D should not be deemed to have been recorded because it is technically infeasible, and the solution of A+B+C+E should be deemed to have been recorded.

[0089] All documents mentioned in this application are considered to be included in the disclosure of this application as a whole, so that they can be used as the basis for modification when necessary. In addition, it should be understood that after reading the above disclosure of this application, those skilled in the art can make various changes or modifications to this application, and these equivalent forms also fall within the scope of protection claimed in this application.

Claims

1. A No. 0 high-pressure heater system adapted to low-load heating of a unit, wherein the No. 0 high-pressure heater system is applied to an ultra-supercritical unit, and the ultra-supercritical unit comprises: An ultra-supercritical boiler (10), a boiler economizer (11), a steam turbine high-pressure cylinder (12), and a feed water pump (13), wherein a main steam pipeline (14) for conveying main steam to the steam turbine high-pressure cylinder (12) is provided between the ultra-supercritical boiler (10) and the steam turbine high-pressure cylinder (12), and a feed water pipeline for conveying feed water to the boiler economizer (11) is provided between the feed water pump (13) and the boiler economizer (11), wherein: The steam turbine high-pressure cylinder (12) comprises a No. 0 steam extraction interface (121), the No. 0 high-pressure heater system comprises a No. 0 high-pressure heating steam trap (21) and a No. 0 high-pressure heater external steam cooler (22), and one end of the No. 0 high-pressure heater external steam cooler (22) is connected to the boiler economizer (11) through a first water supply pipeline section; The No. 0 high-pressure heater external steam cooler (22) is configured to receive high-temperature steam from the high-pressure cylinder (12) of the steam turbine, and the high-temperature steam is used to heat feed water passing through the No. 0 high-pressure heater external steam cooler (22), so that the high-temperature steam is cooled into low-temperature steam, and the No. 0 high-pressure heating steam trap (21) is configured to receive low-temperature steam from the No. 0 high-pressure heater external steam cooler (22), and the low-temperature steam is used to heat feed water passing through the No. 0 high-pressure heating steam trap (21), and the low-temperature steam is cooled into condensate; When the ultra-supercritical unit is operating at a low load, the No. 0 high-pressure heating steam trap (21) is deactivated, and the low-temperature steam in the No. 0 high-pressure external steam cooler (22) is guided to the outside to achieve external heat supply.

2. The system according to claim 1, characterized in that The low load operation refers to the ultra-supercritical unit operating below a load in the range of 40% load to 50% load.

3. The system according to claim 1, characterized in that When the ultra-supercritical unit is running at high load, the No. 0 high-pressure heating steam trap (21) is activated, and at this time, the No. 0 high-pressure heating steam trap (21) receives low-temperature steam from the No. 0 high-pressure external steam cooler (22).

4. The system according to claim 1, characterized in that The No. 0 high-pressure heater system is also provided with a water supply bypass pipeline (50) and a bypass shut-off valve (51) arranged on the water supply bypass pipeline. When the bypass shut-off valve (51) is opened, the No. 0 high-pressure heating steam trap (21) is disabled, and when the bypass shut-off valve (51) is closed, the No. 0 high-pressure heating steam trap (21) is enabled.

5. The system according to claim 4, characterized in that The system further comprises a steam supply channel (31), on which a steam shut-off valve (32) is arranged, one end of the steam supply channel (31) is connected to the outlet of the No. 0 high pressure heater external steam cooler (22), and the other end of the steam supply channel (31) is connected to the No. 0 high pressure heating steam trap (21).

6. The system according to claim 5, characterized in that The system further comprises an external heating steam channel (30), the inlet end of the external heating steam channel (30) being connected to the steam supply channel (31) and being located upstream of the steam shut-off valve (32), and the outlet end of the external heating steam channel (30) being connected to an external device.

7. The system according to claim 6, characterized in that When the ultra-supercritical unit is operating at a low load, the steam shut-off valve (32) is in a closed state, and the low-temperature steam at the outlet of the No. 0 high-pressure heater external steam cooler (22) is transported to the external equipment through the external heat supply steam channel (30).

8. The system of claim 1, wherein: The steam turbine high-pressure cylinder (12) is provided with a supplementary steam valve interface (122). The system further comprises a first supplementary steam passage (41), one end of the first supplementary steam passage (41) is connected to the main steam pipeline (13), and the other end of the first supplementary steam passage (41) is connected to the supplementary steam valve interface (122).

9. The system according to claim 8, characterized in that The system further comprises a spare supplementary steam passage (42), one end of which is connected to the first supplementary steam passage (41), and the other end of which is connected to a steam extraction passage between a No. 0 steam extraction interface (121) of the high-pressure cylinder of the steam turbine and an external steam cooler (22) of the No. 0 high-pressure heater.

10. The system according to claim 9, characterized in that When the ultra-supercritical unit is operating at a load of 20% to 30%, when the pressure of the No. 0 steam extraction interface (121) cannot meet the external heat supply demand, the standby steam supplement channel (42) is activated. At this time, the steam inlet source of the No. 0 high-pressure heater external steam cooler (22) comes from the No. 0 steam extraction interface (121) and the first steam supplement channel (41).

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