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

Abstract

The utility model 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, in particular to a 0th high-pressure heater system suitable for low-load heat supply of a unit. BACKGROUND

[0002] The existing supercritical or ultra-supercritical unit has a decreased steam extraction capacity and a decreased steam extraction pressure during low-load operation, which cannot meet the external heat supply demand of the unit during low-load operation.

[0003] In a super-supercritical unit of a specific turbine type, a 0th high-pressure heater is added to the original regenerative system, and steam in the turbine is extracted through a specific steam valve interface to heat the feed water in the 0th high-pressure heater, so as to increase the feed water temperature. However, the existing supercritical or ultra-supercritical unit has a decreased steam extraction capacity and a decreased steam extraction pressure during low-load operation, which cannot meet the external heat supply demand of the unit during low-load operation.

[0004] Figure 1 The prior art 0th high-pressure heating system is shown, but the prior art 0th high-pressure heating system has the following problems: (1) the prior art is only suitable for heating feed water and cannot be coupled with heat supply; and (2) the 0th high-pressure heater in the prior art has only one steam source interface, and cannot implement steam source switching during full load of the unit.

[0005] Therefore, there is an urgent need in the art to develop a 0th high-pressure heater system suitable for low-load heat supply of a unit, which can increase the feed water temperature of the unit under the condition of ensuring safe operation of the unit, thereby improving the regenerative efficiency of the entire power plant, and can be well coupled with heat supply demand, implement full-load switching of the steam source of the 0th high-pressure heater, and meet the external heat supply demand at a lower load, thereby having good economic benefits. CONTENT OF THE INVENTION

[0006] The present application aims to provide a 0th high-pressure heater system suitable for low-load heat supply of a unit, which can increase the feed water temperature of the unit under the condition of ensuring safe operation of the unit, thereby improving the regenerative efficiency of the entire power plant, and can be well coupled with heat supply demand, implement full-load switching of the steam source of the 0th high-pressure heater, and meet the external heat supply demand at a lower load, thereby having good economic benefits.

[0007] The application provides a 0# high-pressure heater system suitable for low-load heating of a unit, which is applied to an ultra-supercritical unit, the ultra-supercritical unit comprising: an ultra-supercritical boiler, a boiler economizer, a high-pressure cylinder of a steam turbine, and a feed water pump, a main steam pipeline for delivering main steam to the high-pressure cylinder of the steam turbine is arranged between the ultra-supercritical boiler and the high-pressure cylinder of the steam turbine, a feed water pipeline for delivering feed water to the boiler economizer is arranged between the feed water pump and the boiler economizer,

[0008] The high-pressure cylinder of the steam turbine comprises a 0# extraction steam interface, the 0# high-pressure heater system comprises a 0# high-pressure heater trap and a 0# high-pressure heater external steam cooler, one end of the 0# high-pressure heater external steam cooler is connected with the boiler economizer through a first feed water pipeline section;

[0009] The 0# high-pressure heater external steam cooler is configured to receive high-temperature steam of the high-pressure cylinder of the steam turbine, the high-temperature steam is used to heat 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 heater trap is configured to receive low-temperature steam from the 0# high-pressure heater external steam cooler, the low-temperature steam is used to heat feed water passing through the 0# high-pressure heater trap, and the low-temperature steam is cooled into condensate water;

[0010] When the ultra-supercritical unit is in low-load operation, the 0# high-pressure heater trap is disabled, and the low-temperature steam in the 0# high-pressure heater external steam cooler is guided to the outside to realize external heating.

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

[0012] In another preferred example, when the ultra-supercritical unit is in high-load operation, the 0# high-pressure heater trap is enabled, at this time, the 0# high-pressure heater trap receives low-temperature steam from the 0# high-pressure heater external steam cooler.

[0013] In another preferred example, the temperature of the high-temperature steam is in a range of 500 degrees Celsius-550 degrees Celsius.

[0014] In another preferred example, the temperature of the low-temperature steam is in a range of 300 degrees Celsius-350 degrees Celsius.

[0015] In another preferred example, when the ultra-supercritical unit is operated above 50% load, the feed water provided by the feed water pump is heated in sequence by the 0# high-pressure heater trap and the 0# high-pressure heater external steam cooler.

[0016] In another preferred embodiment, the No. 0 high-pressure heater system further comprises a feedwater bypass pipe, a bypass shut-off valve arranged on the feedwater bypass pipe, when the bypass shut-off valve is open, the No. 0 high-pressure heater is disabled, and when the bypass shut-off valve is closed, the No. 0 high-pressure heater is enabled.

[0017] In another preferred embodiment, the No. 0 high-pressure heater system further comprises a feedwater bypass pipe, a bypass shut-off valve arranged on the feedwater bypass pipe, when the bypass shut-off valve is open, the No. 0 high-pressure heater is disabled, and when the bypass shut-off valve is closed, the No. 0 high-pressure heater is enabled.

[0018] In another preferred embodiment, a first shut-off valve is arranged between the No. 0 high-pressure heater and the inlet end of the feedwater bypass pipe, when the ultra-supercritical unit operates at a load of 50% or above, the first shut-off valve is open.

[0019] In another preferred embodiment, the inlet end of the feedwater bypass pipe is connected to a section of the feedwater pipe between the high-pressure heater and the No. 0 high-pressure heater, and the outlet end of the feedwater bypass pipe is connected to a section of the feedwater pipe between the No. 0 high-pressure heater and the No. 0 high-pressure heater external steam cooler.

[0020] In another preferred embodiment, the system further comprises a steam supply channel, a steam shut-off valve is arranged on the steam supply channel, one end of the steam supply channel is connected to the outlet of the No. 0 high-pressure heater external steam cooler, and the other end of the steam supply channel is connected to the No. 0 high-pressure heater.

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

[0022] In another preferred embodiment, when the ultra-supercritical unit operates at a low load, the steam shut-off valve is closed, and the low-temperature steam at the outlet of the No. 0 high-pressure heater external steam cooler is delivered to the external device through the external heat supply steam channel.

[0023] In another preferred embodiment, when the ultra-supercritical unit operates at a load of 40% or below, the bypass shut-off valve is open, and the first shut-off valve is closed, and the feedwater provided by the feedwater pump is sequentially passed through the one or more high-pressure heaters, the feedwater bypass pipe, and the No. 0 high-pressure heater external steam cooler.

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

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

[0026] In another preferred embodiment, the system further comprises a standby supplementary steam passage, one end of which is connected with the first supplementary steam passage, and the other end of which is connected with a steam extraction passage between the 0 extraction interface of the steam turbine high-pressure cylinder and the 0th high-pressure heater external steam cooler.

[0027] In another preferred embodiment, when the ultra-supercritical unit is running at 20%-30% load, and when the pressure of the 0 extraction interface cannot meet the external heat supply demand, the standby supplementary steam passage is enabled, and at this time, the steam source of the 0th high-pressure heater external steam cooler comes from the 0 extraction interface and the first supplementary steam passage.

[0028] In another preferred embodiment, a second shutoff valve is arranged on the standby supplementary steam passage.

[0029] It should be understood that, within the scope of the present application, the above technical features of the present application and the technical features described in detail below (such as the embodiments) can be combined with each other to form new or preferred technical solutions. Due to the limited length, they will not be listed one by one here. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. It should be understood that the drawings described below are only some of the embodiments of the present application, and those skilled in the art can obtain other embodiments from these drawings without creative labor.

[0031] Figure 1 is a structural schematic diagram of a 0th high-pressure heating system in the prior art;

[0032] Figure 2 is a structural schematic diagram of a 0th high-pressure heater system adapted to low-load heat supply of a unit according to the present application.

[0033] In each drawing, the following marks are used

[0034] 10 - ultra-supercritical boiler

[0035] 11 - boiler economizer

[0036] 12 - steam turbine high-pressure cylinder

[0037] 121 - 0 extraction interface

[0038] 122 - make-up valve interface

[0039] 13 - feed water pump

[0040] 14 - main steam pipe

[0041] 15 - deaerator

[0042] 20 - high pressure heater

[0043] 21 - 0# high pressure heater drain

[0044] 22 - 0# high pressure heater external steam cooler

[0045] 30 - external heat supply steam passage

[0046] 31 - steam supply passage

[0047] 32 - steam shut-off valve

[0048] 41 - first make-up passage

[0049] 42 - backup make-up passage

[0050] 43 - second shut-off valve

[0051] 44 - make-up valve

[0052] 50 - feed water bypass pipe

[0053] 51 - bypass shut-off valve

[0054] 60 - first feed water pipe section DETAILED DESCRIPTION

[0055] The inventor, through extensive and in-depth research, has for the first time developed a 0# high pressure heater system suitable for low load heat supply of a unit. The conventional 0# high pressure heater is divided into a 0# high pressure heater external steam cooler and a 0# high pressure heater drain. When the unit load is above 50%, the 0# high pressure heater external steam cooler and the 0# high pressure heater drain normally heat the feed water. When the unit load is below 40%, the 0# high pressure heater drain is bypassed by the feed water bypass, only the 0# high pressure heater external steam cooler is retained to heat the feed water, and the low temperature steam at the outlet of the 0# high pressure heater external steam cooler is used for external heat supply. When the 0# extraction interface pressure cannot meet the external heat supply demand at a lower load of 20%-30%, the steam source of the 0# high pressure heater external steam cooler can be switched to the make-up valve interface, which can further improve the steam pressure at the outlet of the 0# high pressure heater external steam cooler, and realize full load to meet the external heat supply demand. The system of the present application has the characteristics of economy, safety, reliability, environmental protection, etc. It has a good popularization prospect for heat supply transformation of (ultra) supercritical units in operation and external heat supply of newly built units.

[0056] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. It will be apparent, however, to one ordinarily skilled in the art that the application can be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order not to unnecessarily obscure the present application.

[0057] The term

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

[0059] High pressure heater: is the use of partial extraction of steam turbine to heat the feed water device, which is composed of shell and tube two parts, in the shell cavity upper part set up the cold section, the lower part set up the cold section, the inlet and outlet water pipe top set up the feed water inlet and the feed water outlet. When the superheated steam enters the shell through the inlet, the feed water in the upper heat exchange tube can be heated, and the condensed water (or steam) can heat the feed water in the lower cold section. The condensed water after being used flows out of the body through the drain outlet.

[0060] It should be noted that in the application file of the present patent, the relationship 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 the entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment. Without more limitation, the element defined by the statement "including one" does not exclude the presence of another identical element in the process, method, article or equipment including the element. In the application file of the present patent, if it is mentioned that a certain action is performed according to a certain element, it means that the action is performed at least according to the element, which includes two cases: the action is performed only according to the element, and the action is performed according to the element and other elements. The expressions of multiple, multiple times, multiple varieties, etc. include 2, 2 times, 2 kinds and 2 or more, 2 times or more, 2 or more.

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

[0062] The present 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 a No. 0 high-pressure heater external steam cooler and a No. 0 high-pressure heater trap, the No. 0 high-pressure heater external steam cooler and the No. 0 high-pressure heater trap normally heat the feed water when the unit load is above 50%, and when the unit load is below 40%, the No. 0 high-pressure heater trap is bypassed by the feed water bypass, only the No. 0 high-pressure heater external steam cooler remains to heat the feed water, the steam at the outlet of the No. 0 high-pressure heater external steam cooler is used to supply heat to the outside, which can solve the problem of insufficient heating capacity of the unit at low load;

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

[0065] (c) The system of the present application simultaneously uses the No. 0 extraction interface and the extraction port of the supplementary valve as the extraction steam source of the No. 0 high-pressure heater system, which can realize full-load switching of the extraction steam source of the No. 0 high-pressure heater, and further ensure the temperature of the heated feed water by ensuring the pressure of the No. 0 extraction;

[0066] (d) The system of the present application can retain the original supplementary valve while adding the No. 0 extraction interface for ultra-supercritical units with a supplementary valve, thereby avoiding the negative impact on unit operation caused by the removal of the supplementary valve;

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

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

[0069] The No. 0 high-pressure heater system suitable for low-load heating of a 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 heater trap 21, the No. 0 high-pressure heater external steam cooler 22 is configured to receive high-temperature steam of a high-pressure cylinder 12 of a steam turbine, 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 heater trap 21 is configured to receive the low-temperature steam from the No. 0 high-pressure heater external steam cooler 22, the low-temperature steam is used to heat the feed water passing through the No. 0 high-pressure heater trap 21, and the low-temperature steam is cooled into condensate water, the condensate water flows out through the water outlet of the No. 0 high-pressure heater trap 21;

[0070] When the unit load is above 50%, the No. 0 high pressure heater and the No. 0 high pressure trap normally heat the feed water, when the unit load is below 40%, the No. 0 high pressure trap is bypassed, only the No. 0 high pressure heater is used to heat the feed water, the steam at the outlet of the No. 0 high pressure heater is used to supply heat to the outside; when the unit load is lower than 20%-30%, when the pressure at the 0 extraction interface cannot meet the demand of supplying heat to the outside, the steam source at the inlet of the No. 0 high pressure heater can be from the extraction interface and the 0 extraction interface, the pressure of the steam at the outlet of the No. 0 high pressure heater can be further increased, and the demand of supplying heat to the outside can be met under full load.

[0071] The system of the present application is a new technology of the No. 0 high pressure heater system suitable for low load heat supply of a unit, under the condition of ensuring safe operation of the unit, the feed water temperature of the unit is increased, thereby the regenerative efficiency of the whole power plant is increased, meanwhile, the system can be well coupled with the heat supply demand, the steam source of the No. 0 high pressure heater can be switched under full load, the demand of supplying heat to the outside under lower load can be met, and good economic benefits can be obtained.

[0072] In the regenerative system of the (super) supercritical unit, the steam source of the No. 0 high pressure heater system is from the 0 extraction interface and the extraction interface of the steam turbine, the steam source of the No. 0 high pressure heater can be switched under full load, and the extraction pressure of the No. 0 high pressure heater system is ensured.

[0073] Compared with the feed water of the No. 0 high pressure heater in the prior art, the steam turbine type suitable for the present application is more extensive, the safety and reliability are higher, and the present application can be commonly suitable for the (super) supercritical unit in operation or the (super) supercritical unit newly built and having the demand of heat supply.

[0074] In order to make the purpose, technical scheme and advantages of the present application more clear, the embodiments of the present application will be further described in detail below with reference to the drawings. It should be understood that these are only some examples that the present application can take, but are not intended to limit the scope of the present application.

[0075] Embodiment

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

[0077] Specifically, the embodiment provides a 0# high-pressure heater system suitable for low-load heating of a unit, the 0# high-pressure heater system being applied to an ultra-supercritical unit, the ultra-supercritical unit comprising: an ultra-supercritical boiler 10, a boiler economizer 11, a high-pressure cylinder 12 of a steam turbine, and a feed water pump 13, a main steam pipeline 14 for delivering main steam to the high-pressure cylinder 12 of the steam turbine is arranged between the ultra-supercritical boiler 10 and the high-pressure cylinder 12 of the steam turbine, and a feed water pipeline for delivering feed water to the boiler economizer 11 is arranged between the feed water pump 13 and the boiler economizer 11. A main steam valve is arranged on the main steam pipeline.

[0078] The high-pressure cylinder 12 of the steam turbine comprises a 0# extraction steam interface 121, the 0# high-pressure heater system comprises a 0# high-pressure heater trap 21 and a 0# high-pressure heater external steam cooler 22, the 0# high-pressure heater trap 21 and the 0# high-pressure heater external steam cooler 22 are located downstream of the feed water pump 13. A first end of the 0# high-pressure heater external steam cooler 22 is connected to the boiler economizer 11 through a first feed water pipeline section 60, and a second end of the 0# high-pressure heater external steam cooler 22 is connected to the 0# extraction steam interface 121 through an extraction steam pipeline to receive steam from the 0# extraction steam interface 121 to heat feed water in the 0# high-pressure heater external steam cooler 22, and an adjusting valve is arranged on the extraction steam pipeline.

[0079] The 0# high-pressure heater external steam cooler 22 is configured to receive high-temperature steam of the high-pressure cylinder 12 of the steam turbine, the high-temperature steam is used to heat feed water passing through the 0# high-pressure heater external steam cooler 22, so that the high-temperature steam is cooled into low-temperature steam, the 0# high-pressure heater trap 21 is configured to receive the low-temperature steam from the 0# high-pressure heater external steam cooler 22, the low-temperature steam is used to heat feed water passing through the 0# high-pressure heater trap 21, and the low-temperature steam is cooled into condensate water.

[0080] When the ultra-supercritical unit is in low-load operation, the 0# high-pressure heater trap 21 is disabled, and the low-temperature steam in the 0# high-pressure heater external steam cooler 22 is guided to the outside to realize external heating. Preferably, the low-load operation refers to that the ultra-supercritical unit is operated below a load in a range of 40% load-50% load, for example, the unit is operated at 40% load. When the ultra-supercritical unit is in high-load operation, the 0# high-pressure heater trap 21 is enabled, at this time, the 0# high-pressure heater trap 21 receives the low-temperature steam from the 0# high-pressure heater external steam cooler 22. Preferably, the temperature of the high-temperature steam is in a range of 500 degrees Celsius-550 degrees Celsius. The temperature of the low-temperature steam is in a range of 300 degrees Celsius-350 degrees Celsius.

[0081] The 0# high-pressure heater system is further provided with a feed water bypass pipeline 50 and a bypass shut-off valve 51 arranged on the feed water bypass pipeline, when the bypass shut-off valve 51 is in an open state, the 0# high-pressure heater trap 21 is disabled, and when the bypass shut-off valve 51 is in a closed state, the 0# high-pressure heater trap 21 is enabled.

[0082] The inlet end of the feedwater bypass pipe 50 is connected to a section of the feedwater pipe between one or more other high-pressure heaters 20 and the 0# high-pressure heater drain 21, and the outlet end of the feedwater bypass pipe 50 is connected to a section of the feedwater pipe between the 0# high-pressure heater drain 21 and the 0# high-pressure heater external steam cooler 22. A first shutoff valve is provided between the 0# high-pressure heater drain 21 and the inlet end of the feedwater bypass pipe 50, and when the ultra-supercritical unit is operated at a load of 50% or more, the first shutoff valve is in an open state, i.e., the 0# high-pressure heater drain 21 is enabled.

[0083] The system also includes a steam supply channel 31 and an external heat supply steam channel 30, and a steam shutoff 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 0# high-pressure heater external steam cooler 22, and the other end of the steam supply channel 31 is connected to the 0# high-pressure heater drain 21. The inlet end of the external heat supply steam channel 30 is connected to the steam supply channel 31 and is located upstream of the steam shutoff valve 32, and the outlet end of the external heat supply steam channel 30 is connected to external equipment.

[0084] A steam supplement valve interface 122 is provided on the high-pressure cylinder 12 of the steam turbine, and the system also includes a first steam supplement channel 41 and a backup steam supplement channel 42. One end of the first steam supplement channel 41 is connected to the main steam pipe 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 backup steam supplement channel 42 is connected to the first steam supplement channel 41, and the other end of the backup steam supplement channel 42 is connected to a steam extraction channel between the 0# steam extraction interface 121 of the high-pressure cylinder of the steam turbine and the 0# high-pressure heater external steam cooler 22. The backup steam supplement channel 42 and the steam extraction channel (from the 0# steam extraction interface 121) connected to the first steam supplement channel 41 are mutually backup steam sources. A second shutoff valve 43 is provided on the backup 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 operated at a load of 20%-30%, and when the pressure of the 0# steam extraction interface 121 cannot meet the external heat supply demand, the backup steam supplement channel 42 is enabled, and at this time, the steam source for the 0# high-pressure heater external steam cooler 22 comes from the 0# steam extraction interface 121 and the first steam supplement channel 41.

[0086] When the ultra-supercritical unit is operated at a low load, such as a load of 40% or less, the bypass shutoff valve 51 is in an open state, the first shutoff valve is in a closed state, the 0# high-pressure heater drain 21 is disabled, and the feedwater provided by the feedwater pump 13 passes through one or more other high-pressure heaters 20, the feedwater bypass pipe 50, and the 0# high-pressure heater external steam cooler 22 in sequence. At this time, the steam shutoff valve 32 is in a closed state, and no steam is delivered to the 0# high-pressure heater drain 21, and the low-temperature steam at the outlet of the 0# high-pressure heater external steam cooler 22 is delivered to external equipment through the external heat supply steam channel 30.

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

[0088] A large number of technical features are described in the specification of the present application, which are distributed in various technical solutions. If all possible combinations of technical features (i.e. technical solutions) of the present application are listed, the specification will be too long. In order to avoid this problem, each technical feature disclosed in the above invention content of the present application, each technical feature disclosed in the following various embodiments and examples, and each technical feature disclosed in the drawings can be freely combined with each other to form various new technical solutions (these technical solutions are all considered to have been described in the specification), unless such combination of technical features is technically infeasible. For example, features A+B+C are disclosed in one example, features A+B+D+E are disclosed in another example, features C and D are equivalent technical means that play the same role, and only one of them can be used technically, and feature E can be combined with feature C technically. Therefore, the scheme of A+B+C+D should not be considered as having been described because it is technically infeasible, and the scheme of A+B+C+E should be considered as having been described.

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

Claims

1. A No. 0 high-pressure heater system adapted for low-load heating of a unit, the No. 0 high-pressure heater system being applied to an ultra-supercritical unit, the ultra-supercritical unit comprising: The system comprises an ultra-supercritical boiler (10), a boiler economizer (11), a steam turbine high-pressure cylinder (12), and a feedwater pump (13). A main steam pipe (14) for supplying 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). A feedwater pipe for supplying feedwater to the boiler economizer (11) is provided between the feedwater pump (13) and the boiler economizer (11). The system is characterized in that... The turbine high-pressure cylinder (12) includes a 0 extraction steam port (121), and the 0 high-pressure heater system includes a 0 high-pressure heater drain valve (21) and a 0 high-pressure heater external steam cooler (22). One end of the 0 high-pressure heater external steam cooler (22) is connected to the boiler economizer (11) through the first feedwater pipeline section. The No. 0 high-pressure heater external steam cooler (22) is configured to receive high-temperature steam from the turbine high-pressure cylinder (12), the high-temperature steam being used to heat the feedwater passing through the No. 0 high-pressure heater external steam cooler (22), thereby cooling the high-temperature steam into low-temperature steam. The No. 0 high-pressure heater steam trap (21) is configured to receive low-temperature steam from the No. 0 high-pressure heater external steam cooler (22), the low-temperature steam being used to heat the feedwater passing through the No. 0 high-pressure heater steam trap (21), and the low-temperature steam being cooled into condensate. When the ultra-supercritical unit is running at low load, the No. 0 high-pressure heater steam trap (21) is shut down, and the low-temperature steam in the No. 0 high-pressure heater external steam cooler (22) is guided to the outside to achieve external heating. The No. 0 high-pressure heater system is also equipped with a water supply bypass pipe (50) and a bypass shut-off valve (51) installed on the water supply bypass pipe. When the bypass shut-off valve (51) is open, the No. 0 high-pressure heater steam trap (21) is deactivated. When the bypass shut-off valve (51) is closed, the No. 0 high-pressure heater steam trap (21) is activated.

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

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

4. The system as described in claim 1, characterized in that, The temperature of the high-temperature steam is between 500 and 550 degrees Celsius, and / or the temperature of the low-temperature steam is between 300 and 350 degrees Celsius.

5. The system as described in claim 4, characterized in that, The system also includes a steam supply channel (31), on which a steam shut-off valve (32) is provided. 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).

6. The system as described in claim 5, characterized in that, The system also includes an external heating steam channel (30), the inlet end of which is connected to the steam supply channel (31) and located upstream of the steam shut-off valve (32), and the outlet end of which is connected to external equipment.

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

8. The system as described in claim 1, characterized in that, The high-pressure cylinder (12) of the steam turbine is provided with a steam replenishment valve interface (122). The system also includes a first steam replenishment channel (41), one end of which is connected to the main steam pipeline (14), and the other end of which is connected to the steam replenishment valve interface (122).

9. The system as described in claim 8, characterized in that, The system also includes a backup steam supply channel (42), one end of which is connected to the first steam supply channel (41), and the other end of which is connected to the extraction channel between the 0 extraction port (121) of the turbine high-pressure cylinder and the external steam cooler (22) of the No. 0 high-pressure heater.

10. The system as described in claim 9, characterized in that, When the ultra-supercritical unit is running at 20%-30% load, and the pressure of the 0 extraction steam interface (121) cannot meet the external heating demand, the backup steam supply channel (42) is activated. At this time, the steam source of the No. 0 high-pressure heater external steam cooler (22) comes from the 0 extraction steam interface (121) and the first steam supply channel (41).

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