A heating steam system based on feed water supplementary heating

Abstract

The application discloses a heat supply steam system based on feed water supplementary heating, which comprises a deaerator, a pre-pump, a feed water pump, a high-pressure heater, an additional high-pressure heater, a boiler heating surface, a heat supply working medium source, a pressure boosting heating device, a desuperheater and a heat supply user which are connected in sequence, wherein the boiler heating surface comprises an economizer device and a water cooling wall; the economizer device comprises a feed water heating surface and a heat supply steam heating surface which are independent of each other or integrated into one body, the two are completely isolated or can be operated to be completely isolated, the feed water heating surface is provided with a water side bypass or a flue gas bypass, the additional high-pressure heater is connected to the water cooling wall through the feed water heating surface, the heat supply working medium source is connected to the inlet of the pressure boosting heating device, the outlet of the pressure boosting heating device is connected to the inlet of the heat supply steam heating surface, the outlet of the heat supply steam heating surface is connected to the steam inlet of the desuperheater, the steam outlet of the desuperheater is connected to the heat supply user, and the pressure boosting heating device is further connected to the desuperheating water inlet of the desuperheater.

Description

Technical Field

[0001] This invention relates to the field of generator set external heating steam system technology, and in particular to a heating steam system based on feedwater supplementary heating. Background Technology

[0002] When generating units supply heat to external users, the steam source often needs to undergo pressure reduction and desuperheating to obtain heating steam that meets certain pressure and temperature parameters before being supplied to users. For heating steam demands with high pressure and large flow (such as 5MPa, 400℃, 250t / h, etc.), under the premise that the unit has to operate within a wide load range in response to the grid's deep peak shaving and the high-pressure cylinder has not undergone large-scale modifications such as adding new steam extraction ports or expanding the capacity of existing steam extraction ports, the main steam is often selected as the heating steam source. After pressure reduction through the regulating valve, the feedwater from the high-pressure heater outlet is selected as the desuperheating water for desuperheating. In this way, the main steam obtains heating steam with certain parameters after pressure reduction and desuperheating, resulting in poor heating economy.

[0003] Existing technologies for heating steam systems using main steam 1 as the steam source include... Figure 1 As shown, the low-pressure condensate from the outlet of deaerator 2 is pressurized by the pre-pump 3 and feedwater pump 4 and then enters the high-pressure heater for heating. The heated feedwater 6 enters the boiler 7 and is heated by the economizer 8, water-cooled wall 9 and other heating surfaces in sequence, and finally the main steam 1 enters the high-pressure cylinder 10 to do work.

[0004] Specifically: after a portion of the main steam 1 is depressurized by regulating valve 11, the feedwater 6 from the outlet of the final stage high-pressure heater 5 is selected as desuperheating water 12 and enters the desuperheater 13 for desuperheating. In this way, the main steam 1 is depressurized and desuperheated to obtain heating steam with certain parameters and is sent to the heating user 14.

[0005] Using main steam as the heating source: When the heating steam volume is large, the heat absorption of the reheat steam will increase significantly for primary or secondary reheat units. Due to the limited means of reheat temperature regulation and the excessive use of reheat desuperheating water, the operating economy of the unit will be significantly reduced. The heating surfaces inside the boiler, including the reheater, will have to undergo large-scale adaptive modifications, and the modification costs will be considerable. Furthermore, under extreme conditions where the heating steam volume is temporarily reduced or even stopped, the heating surfaces inside the boiler, including the reheater, will face the dilemma of severe heat absorption mismatch.

[0006] Therefore, those skilled in the art are dedicated to developing a heating steam system based on feedwater supplemental heating to overcome the problems existing in the prior art. Summary of the Invention

[0007] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is how to meet the demand for stable high-pressure and high-flow heating steam under wide load range operating conditions, and improve the safety and economy of the unit's heating operation. This has become an urgent problem to be solved.

[0008] To achieve the above objectives, the present invention provides a heating steam system based on feedwater supplemental heating, comprising a deaerator, a pre-pump, a feedwater pump, a high-pressure heater, an auxiliary high-pressure heater, a boiler heating surface, a heating medium source, a pressure boosting heating device, a desuperheater, and a heating user. The deaerator, pre-pump, feedwater pump, high-pressure heater, and auxiliary high-pressure heater are sequentially connected by pipelines. The boiler heating surface includes an economizer device and a water-cooled wall. The economizer device includes a feedwater heating surface and a heating steam heating surface that are independent or integrated. The feedwater heating surface and the heating steam heating surface are completely integrated. The system is isolated or can be operated to be completely isolated. The feedwater heating surface is provided with a water-side bypass or a flue gas bypass. The additional high-pressure heater is connected to the water-cooled wall via the feedwater heating surface pipe. The heating medium source pipe is connected to the inlet of the pressure-boosting heating device. The outlet pipe of the pressure-boosting heating device is connected to the inlet of the heating steam heating surface. The outlet pipe of the heating steam heating surface is connected to the steam inlet of the desuperheater. The steam outlet pipe of the desuperheater is connected to the heating user. The pressure-boosting heating device is also connected to the desuperheating water inlet of the desuperheater.

[0009] Furthermore, the heating medium is sourced from the low-pressure condensate between the deaerator and the pre-pump. The pressurization heating device includes at least one cascaded pressurization heating unit, which includes a booster pump, a mixing heater, and a regenerative extraction steam. The low-pressure condensate is connected to the inlet of the heating steam receiving surface via the booster pump and the mixing heater. The regenerative extraction steam is connected to the steam inlet of the mixing heater. The outlet of the booster pump is also connected to the desuperheating water inlet of the desuperheater.

[0010] Furthermore, it also includes a heat exchanger, a regenerative heater, and another regenerative extraction steam. The cold end pipe of the heat exchanger is connected between the outlet of the pressurized heating device and the inlet of the heating steam heating surface, and the hot end pipe of the heat exchanger is connected to the regenerative heater and the other regenerative extraction steam respectively.

[0011] Furthermore, it also includes a heat exchanger, a regenerative heater, and another regenerative extraction steam. The cold end pipe of the heat exchanger is connected between the outlet of the heating steam receiving surface and the steam inlet of the desuperheater, and the hot end pipe of the heat exchanger is connected to the regenerative heater and the other regenerative extraction steam respectively.

[0012] Furthermore, the heating medium source is the medium-pressure feedwater between the pre-pump and the feedwater pump. The pressurization heating device includes a pressurization heating unit, which includes a booster pump, a mixing heater, and a regenerative steam extraction unit. The medium-pressure feedwater is connected to the inlet of the heating steam receiving surface via the booster pump and the mixing heater pipeline. The regenerative steam extraction pipeline is connected to the steam inlet of the mixing heater. The outlet of the booster pump is also connected to the desuperheating water inlet of the desuperheater.

[0013] Furthermore, the heating medium source is the medium-pressure feedwater between the pre-pump and the feedwater pump. The pre-pump is an independent electric pre-pump. The pressure-boosting heating device includes a pressure-boosting heating unit, which includes a regulating valve, a mixing heater, and a regenerative steam extraction unit. The medium-pressure feedwater is connected to the inlet of the heating steam receiving surface via the regulating valve and the mixing heater pipeline. The regenerative steam extraction pipeline is connected to the steam inlet of the mixing heater. The outlet of the regulating valve is also connected to the desuperheating water inlet of the desuperheater.

[0014] Furthermore, the heating medium source is the normal condensate drain of the high-pressure regenerative heater. The pressure boosting heating device includes a pressure boosting heating unit, which includes a booster pump, a mixing heater, and regenerative steam extraction. The normal condensate drain of the high-pressure regenerative heater is connected to the inlet of the heating steam receiving surface via the booster pump and the mixing heater pipeline. The regenerative steam extraction pipeline is connected to the steam inlet of the mixing heater. The outlet of the booster pump is also connected to the desuperheating water inlet of the desuperheater.

[0015] Furthermore, the heating medium is sourced from the emergency drain of the high-pressure regenerative heater. The pressurization heating device includes a pressurization heating unit, which comprises a booster pump, a mixing heater, and regenerative steam extraction. The normal drain of the high-pressure regenerative heater is connected to the inlet of the heating steam receiving surface via the booster pump and the mixing heater pipeline. The regenerative steam extraction pipeline is connected to the steam inlet of the mixing heater. The outlet of the booster pump is also connected to the desuperheating water inlet of the desuperheater.

[0016] Furthermore, the heating medium is sourced from the low-pressure condensate between the deaerator and the pre-pump. The pressurization heating device includes a pressurization heating unit, which includes a booster pump but does not include a mixing heater or regenerative steam extraction. The low-pressure condensate is connected to the inlet of the heating steam heating surface via the booster pump pipeline, and the outlet of the booster pump is also connected to the desuperheating water inlet of the desuperheater.

[0017] Furthermore, the additional high-pressure heater includes an additional high-pressure heater body and an external steam cooler, which are arranged in series or in parallel along the feedwater flow pipeline.

[0018] The beneficial effects of this invention are as follows:

[0019] (1) The present invention uses low-pressure condensate and the like as the working fluid source, and obtains heating steam that meets the requirements through processes such as pressurization and heating for external heating.

[0020] (2) Increase the target value of feedwater supplement heating to above the full load feedwater temperature, thereby increasing the feedwater temperature at the economizer inlet, reducing the heat released by the flue gas in the boiler to the economizer, and transferring the reduced heat released to the heating medium that needs to be heated through the heating economizer, while keeping the boiler flue gas temperature stable and not increasing the flue gas heat loss.

[0021] (3) The present invention replaces the existing heating scheme with main steam as the steam source, improves the supplementary heating effect of feedwater, keeps the boiler flue gas temperature stable, does not increase flue gas heat loss, avoids large-scale modification of boiler and turbine, better adapts to the wide load range operation of the unit in response to the deep peak shaving of the power grid, and improves the economic efficiency of the unit's heating operation.

[0022] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a heating steam system using main steam as the steam source in the existing technology;

[0024] Figure 2 This is a schematic diagram of a heating steam system according to a preferred embodiment of the present invention.

[0025] Figure 3 This is a schematic diagram of a heating steam system according to a second example of a preferred embodiment of the present invention;

[0026] Figure 4 This is a schematic diagram of a heating steam system according to a third example of a preferred embodiment of the present invention;

[0027] Figure 5 This is a schematic diagram of a heating steam system according to a fourth example of a preferred embodiment of the present invention;

[0028] Figure 6 This is a schematic diagram of a heating steam system according to a fifth example of a preferred embodiment of the present invention;

[0029] Figure 7This is a schematic diagram of a heating steam system according to a sixth example of a preferred embodiment of the present invention;

[0030] Figure 8 This is a schematic diagram of a heating steam system according to a seventh example of a preferred embodiment of the present invention;

[0031] Figure 9 This is a schematic diagram of a heating steam system according to the eighth example of a preferred embodiment of the present invention;

[0032] Figure 10 This is a schematic diagram of a heating steam system according to a ninth example of a preferred embodiment of the present invention;

[0033] Figure 11 This is a schematic diagram of a heating steam system according to a first example of another preferred embodiment of the present invention;

[0034] Figure 12 This is a schematic diagram of a heating steam system according to a second example of another preferred embodiment of the present invention;

[0035] Figure 13 This is a schematic diagram of a heating steam system according to a third example of another preferred embodiment of the present invention;

[0036] Figure 14 This is a schematic diagram of a heating steam system according to a fourth example of another preferred embodiment of the present invention;

[0037] Figure 15 This is a schematic diagram of a heating steam system according to another preferred embodiment, the fifth example, of the present invention;

[0038] Figure 16 This is a schematic diagram of a heating steam system according to a sixth example of another preferred embodiment of the present invention;

[0039] Figure 17 This is a schematic diagram of a heating steam system according to a seventh example of another preferred embodiment of the present invention;

[0040] Figure 18 This is a schematic diagram of a heating steam system according to another preferred embodiment, the eighth example, of the present invention;

[0041] Figure 19 This is a schematic diagram of a heating steam system according to another preferred embodiment, the ninth example, of the present invention.

[0042] Among them, 1-Main steam, 2-Deaerator, 3-Pre-pump, 4-Feed water pump, 5-Final stage high-pressure heater, 6-Feed water, 7-Boiler, 8-Economizer, 9-Water-cooled wall, 10-High-pressure cylinder, 11-Regulating valve, 12-Desuperheating water, 13-Desuperheater, 14-Heating user, 15-Low-pressure condensate, 16-New final stage high-pressure heater, 17-Steam source for extraction from the new final stage high-pressure heater, 18-Heating economizer, 19-A-Addition 20-Pressure pump, 20-A Mixing heater, 21-A Regenerative extraction steam, 22-B Booster pump, 23-B Mixing heater, 24-B Regenerative extraction steam, 25-Regenerative heater, 26-Heat exchanger, 27-Medium-pressure feedwater, 28-High-pressure regenerative heater, 29-Normal condensate drain, 30-Lower stage regenerative heater, 31-Emergency condensate drain, 32-Condenser, 33-Feedwater heating surface, 34-Heating steam surface, 35-Isolation valve. Detailed Implementation

[0043] The following description, with reference to the accompanying drawings, illustrates several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0044] In the accompanying drawings, components with the same structure are indicated by the same numerical designation, and components with similar structures or functions are indicated by similar numerical designations. The dimensions and thicknesses of each component shown in the drawings are arbitrary, and the present invention does not limit the dimensions and thicknesses of each component. To make the illustrations clearer, the thickness of some components has been appropriately exaggerated in the drawings.

[0045] Example 1

[0046] The heating steam system in the first example of this embodiment is as follows: Figure 2 As shown, the low-pressure condensate 15 from the outlet of deaerator 2 is pressurized by the pre-pump 3 and feedwater pump 4 and then enters the high-pressure heater for heating. The heated feedwater 6 enters the boiler 7 and is heated by the economizer 8, water-cooled wall 9 and other heating surfaces in sequence, and finally the main steam 1 enters the high-pressure cylinder 10 to do work.

[0047] at the same time:

[0048] A new final-stage high-pressure heater 16, a new final-stage high-pressure heater extraction steam source 17, and its regulating valve 11 are installed at the outlet of the final-stage high-pressure heater 5 to supplement the heating of the feedwater 6.

[0049] A feedwater bypass and its regulating valve 11 are installed at the inlet and outlet of the economizer 8 of boiler 7. Part of the feedwater 6, after being supplemented and heated by the newly added final stage high-pressure heater 16, enters the economizer 8, and the remaining part enters the bypass of the economizer 8. In this way, the heating of the economizer 8 by the flue gas can be "squeezed out" and the heat absorption of the economizer 8 can be reduced.

[0050] A heating economizer 18 is installed upstream or downstream of the economizer 8 of boiler 7 along the flue gas flow direction to absorb the heat absorbed by the economizer 8, so as to keep the flue gas temperature at the outlet of the economizer 8 stable and not increase the heat loss of the flue gas.

[0051] The low-pressure condensate 15 between the deaerator 2 and the pre-pump 3 is used as the heating medium. After being pressurized by the A booster pump 19, it is fully mixed and heated with the A regenerative steam 21 in the A mixing heater 20. After further heating in the heating economizer 18, a portion of the condensate pressurized by the A booster pump 19 is selected as desuperheating water 12 and enters the desuperheater 13 for desuperheating.

[0052] In this way, the low-pressure condensate 15 undergoes processes such as pressurization and heating to obtain heating steam with certain parameters, which is then delivered to the heating user 14.

[0053] in:

[0054] The effect of the newly added final stage high-pressure heater 16 in supplementing the heating of feedwater 6 should be such that the final feedwater temperature entering boiler 7 is raised to a suitable value above the full-load feedwater temperature.

[0055] Based on the above-mentioned supplementary heating effect of water supply 6:

[0056] If there is an external steam cooler in the feedwater regeneration system to heat the feedwater 6, the external steam cooler and the newly added final stage high-pressure heater 16 can be arranged in series or in parallel along the feedwater 6 flow direction pipeline.

[0057] The newly added final stage high-pressure heater 16 can also be equipped with a feedwater bypass to reduce the rated capacity of the newly added final stage high-pressure heater 16.

[0058] The newly added final stage high-pressure heater extraction steam source 17 can be the steam turbine extraction port (such as the high-pressure cylinder make-up steam valve interface of a 1000MW unit), or the steam after the main steam 1 has been de-temperatured and depressurized, or the steam after the main steam 1 and the extraction steam have passed through the steam matching device, etc.

[0059] A booster pump 19 can be operated in a variable frequency mode to ensure that the pressure of the heating medium after pressurization is kept stable when the unit's operating load changes.

[0060] The newly added heating economizer 18 outlet of boiler 7 retains the desuperheater 13 device, which is an auxiliary means to regulate the steam temperature at the outlet of the heating economizer 18.

[0061] The heating steam system in the second example of this embodiment is as follows: Figure 3As shown, based on the first example of this embodiment, a booster pump 22 (B), a mixing heater 23 (B), and a regenerative steam extraction 24 (B) are added, which increases the regenerative heating of the heating medium and further improves the heating economy.

[0062] The heating steam system in the third example of this embodiment is as follows: Figure 4 As shown, based on the first example of this embodiment, a B regenerative extraction steam 24, a regenerative heater 25, and a heat exchanger 26 are added. The superheat of the B regenerative extraction steam 24 is used to further heat the heating medium, thereby further improving the heating economy.

[0063] The heating steam system in the fourth example of this embodiment is as follows: Figure 5 As shown, based on the first example of this embodiment, a B regenerative extraction steam 24, a regenerative heater 25, and a heat exchanger 26 are added. The superheat of the B regenerative extraction steam 24 is used to further heat the heating medium, thereby further improving the heating economy.

[0064] The heating steam system in the fifth example of this embodiment is as follows: Figure 6 As shown, based on the first example of this embodiment, the source of the heating medium is optimized from the low-pressure condensate 15 between the deaerator 2 and the pre-pump 3 to the medium-pressure feedwater 27 between the pre-pump 3 and the feedwater pump 4.

[0065] Compared to the low-pressure condensate 15, the medium-pressure water supply 27 has already been pressurized by the more efficient pre-pump 3, and then by the A booster pump 19, which can save some pumping power and improve the heating economy.

[0066] The heating steam system in the sixth example of this embodiment is as follows: Figure 7 As shown, based on the fifth example of this embodiment, the pre-pump 3 of this scheme is independently electric, and the rated outlet pressure is higher than the heating extraction steam pressure requirement. Therefore, the booster pump can be eliminated, and the regulating valve 11 can be added, which can simplify the system, reduce investment, and improve the heating economy.

[0067] The heating steam system in the seventh example of this embodiment is as follows: Figure 8 As shown, based on the first example of this embodiment, the source of the heating medium is optimized from the low-pressure condensate 15 between the deaerator 2 and the pre-pump 3 to the normal condensate 29 of the high-pressure regenerative heater 28.

[0068] Compared to the low-pressure condensate 15, the normal drain 29 of the high-pressure regenerative heater 28 has a higher pressure, which is further increased by the booster pump 19, saving some pumping power and improving heating economy. At the same time, the effective utilization of the high-pressure heater drain can reduce its "displacement" of the extracted steam used by the downstream regenerative heater 30, increase the extraction steam of the downstream regenerative heater 30, and further improve heating economy.

[0069] The heating steam system in the eighth example of this embodiment is as follows: Figure 9 As shown, based on the seventh example of this embodiment, the emergency drain 31 of the high-pressure regenerative heater 28 discharged to the condenser 32 is selected instead of the normal drain 29 as the working fluid source, so as to reduce the amount of modification required to the normal drain 29 system.

[0070] The heating steam system in the ninth example of this embodiment is as follows: Figure 10 As shown, based on the first example of this embodiment, the regenerative heating device for the working fluid is eliminated, that is, the mixing heater and its regenerative steam extraction are eliminated, which greatly simplifies the heating system.

[0071] The purpose of setting a water-side bypass in the economizer is to "displace" some of the heat released by the flue gas on the economizer. In other examples, this can also be achieved by setting a flue gas bypass.

[0072] In some cases, the demand for heating steam at low pressure and high temperature can be met by using low-temperature and low-pressure regenerative steam as the working fluid. After being heated by the economizer in this embodiment, the external heating steam that meets the parameter requirements can be obtained.

[0073] Example 2

[0074] The heating steam system in the first example of this embodiment is as follows: Figure 11 As shown, the low-pressure condensate 15 from the outlet of deaerator 2 is pressurized by the pre-pump 3 and feedwater pump 4 and then enters the high-pressure heater for heating. The heated feedwater 6 enters the boiler 7 and is heated by the economizer 8, water-cooled wall 9 and other heating surfaces in sequence, and finally the main steam 1 enters the high-pressure cylinder 10 to do work.

[0075] in:

[0076] A new final-stage high-pressure heater 16, a new final-stage high-pressure heater extraction steam source 17, and its regulating valve 11 are installed at the outlet of the final-stage high-pressure heater 5 to supplement the heating of the feedwater 6.

[0077] The economizer 8 of boiler 7 is divided into a feedwater heating heating surface 33 and a heating steam heating surface 34. Isolation valves 35 are installed on the inlet and outlet pipes of the heating steam heating surface. Within the isolation range of the isolation valve 35, a switching pipe and its isolation valve 35 are configured between the feedwater heating heating surface 33 and the heating steam heating surface 34 to enable the heating steam heating surface 34 to be put into use or the heating steam heating surface 34 to be switched to the feedwater heating surface 33 online when the heating is turned on or off.

[0078] A feedwater bypass and its regulating valve 11 are installed at the inlet and outlet of the economizer 8 of boiler 7. Part of the feedwater 6, after being supplemented and heated by the newly added final stage high-pressure heater 16, enters the feedwater heating surface 33 of the economizer 8, and the remaining part will enter the bypass of the economizer 8. In this way, the heating of the feedwater heating surface 33 of the economizer 8 by the flue gas can be "squeezed out", reducing the heat absorption of the feedwater heating surface 33 of the economizer 8, and the reduced heat absorption is used for the heat absorption of the heating steam heating surface 34, so that the flue gas temperature at the outlet of the economizer 8 remains stable and the exhaust heat loss is not increased.

[0079] The low-pressure condensate 15 between the deaerator 2 and the pre-pump 3 is used as the heating medium. After being pressurized by the A booster pump 19, it is fully mixed and heated with the A regenerative extraction steam 21 in the A mixing heater 20. After further heating in the heating steam heating surface 34 of the economizer 8, a portion of the condensate pressurized by the A booster pump 19 is selected as desuperheating water 12 and enters the desuperheater 13 for desuperheating.

[0080] In this way, the low-pressure condensate 15 undergoes processes such as pressurization and heating to obtain heating steam with certain parameters, which is then delivered to the heating user 14.

[0081] in:

[0082] The effect of the newly added final stage high-pressure heater 16 in supplementing the heating of feedwater 6 should be such that the final feedwater temperature entering boiler 7 is raised to a suitable value above the full-load feedwater temperature.

[0083] Based on the above-mentioned supplementary heating effect of water supply 6:

[0084] If there is an external steam cooler in the feedwater regeneration system to heat the feedwater 6, the external steam cooler and the newly added final stage high-pressure heater 16 can be arranged in series or in parallel along the feedwater flow pipeline.

[0085] The newly added final stage high-pressure heater 16 can also be equipped with a feedwater bypass to reduce the rated capacity of the newly added final stage high-pressure heater 16.

[0086] The newly added final stage high-pressure heater extraction steam source 17 can be the steam turbine extraction port (such as the high-pressure cylinder make-up steam valve interface of a 1000MW unit), or the steam after the main steam 1 has been de-temperatured and depressurized, or the steam after the main steam 1 and the extraction steam have passed through the steam matching device, etc.

[0087] A booster pump 19 can be operated in a variable frequency mode to ensure that the pressure of the heating medium after pressurization is kept stable when the unit's operating load changes.

[0088] The desuperheater 13 device is retained at the outlet of the heating steam surface 34 of the economizer 8, which is an auxiliary means to regulate the steam temperature at the outlet of the heating steam surface 34 of the economizer 8.

[0089] The heating steam system in the second example of this embodiment is as follows: Figure 12 As shown, based on the first example of this embodiment, a booster pump 22 (B), a mixing heater 23 (B), and a regenerative steam extraction 24 (B) are added, which increases the regenerative heating of the heating medium and further improves the heating economy.

[0090] The heating steam system in the third example of this embodiment is as follows: Figure 13 As shown, based on the first example of this embodiment, a B regenerative extraction steam 24, a regenerative heater 25, and a heat exchanger 26 are added. The superheat of the B regenerative extraction steam 24 is used to further heat the heating medium, thereby further improving the heating economy.

[0091] The heating steam system in the fourth example of this embodiment is as follows: Figure 14 As shown, based on the first example of this embodiment, a B regenerative extraction steam 24, a regenerative heater 25, and a heat exchanger 26 are added. The superheat of the B regenerative extraction steam 24 is used to further heat the heating medium, thereby further improving the heating economy.

[0092] The heating steam system in the fifth example of this embodiment is as follows: Figure 15 As shown, based on the first example of this embodiment, the source of the heating medium is optimized from the low-pressure condensate 15 between the deaerator 2 and the pre-pump 3 to the medium-pressure feedwater 27 between the pre-pump 3 and the feedwater pump 4.

[0093] Compared to the low-pressure condensate 15, the medium-pressure water supply 27 has already been pressurized by the more efficient pre-pump 3, and then by the A booster pump 19, which can save some pumping power and improve the heating economy.

[0094] The heating steam system in the sixth example of this embodiment is as follows: Figure 16 As shown, based on the fifth example of this embodiment, the pre-pump 3 of this scheme is independently electric, and the rated outlet pressure is higher than the heating extraction steam pressure requirement. Therefore, the booster pump can be eliminated, and the regulating valve 11 can be added, which can simplify the system, reduce investment, and improve the heating economy.

[0095] The heating steam system in the seventh example of this embodiment is as follows: Figure 17 As shown, based on the first example of this embodiment, the source of the heating medium is optimized from the low-pressure condensate 15 between the deaerator 2 and the pre-pump 3 to the normal condensate 29 of the high-pressure regenerative heater 28.

[0096] Compared to the low-pressure condensate 15, the normal drain 29 of the high-pressure regenerative heater 28 has a higher pressure, which is further increased by the booster pump 19, saving some pumping power and improving heating economy. At the same time, the effective utilization of the high-pressure heater drain can reduce its "displacement" of the extracted steam used by the downstream regenerative heater 30, increase the extraction steam of the downstream regenerative heater 30, and further improve heating economy.

[0097] The heating steam system in the eighth example of this embodiment is as follows: Figure 18 As shown, based on the seventh example of this embodiment, the emergency drain 31 of the high-pressure regenerative heater 28 discharged to the condenser 32 is selected instead of the normal drain 29 as the working fluid source, so as to reduce the amount of modification required to the normal drain 29 system.

[0098] The heating steam system in the ninth example of this embodiment is as follows: Figure 19 As shown, based on the first example of this embodiment, the regenerative heating device for the working fluid is eliminated, that is, the mixing heater and its regenerative steam extraction are eliminated, which greatly simplifies the heating system.

[0099] Taking a 1000MW unit in THA mode for external heating as an example, the required heating steam parameters are: pressure 5MPa, temperature 400℃, and flow rate 250t / h.

[0100] Existing unit parameters: main steam pressure 25.9MPa, temperature 600℃, flow rate 217t / h, feedwater pressure 32.2MPa, temperature 294.1℃, flow rate 33t / h.

[0101] The technical solution of the first example of Embodiment 1 is adopted:

[0102] The steam source for the newly added final stage high-pressure heater is located at the interface of the high-pressure cylinder make-up steam valve, with a pressure of 15.7 MPa and a temperature of 510.6℃.

[0103] The original final stage high-pressure heater outlet feedwater temperature was 293.7℃, while the newly added final stage high-pressure heater outlet feedwater temperature is 325.1℃.

[0104] The low-pressure condensate has a pressure of 1.06 MPa, a temperature of 182.2℃, and a flow rate of 209.2 t / h; the A regenerative extraction steam has a pressure of 5.7 MPa, a temperature of 360.1℃, and a flow rate of 40.8 t / h.

[0105] The heat absorbed by the supplementary heating of the feedwater temperature, which in turn "displaces" the economizer, is basically consistent with the heat absorbed by the heating medium in the heating economizer.

[0106] Compared with the prior art, the technical solution of the first example of Embodiment 1 achieves a heat consumption benefit of ~32.5 kJ / (kW·h).

[0107] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A steam heating system based on feedwater supplemental heating, characterized in that, The system includes a deaerator, a pre-pump, a feedwater pump, a high-pressure heater, an auxiliary high-pressure heater, boiler heating surfaces, a heating medium source, a pressure-boosting heating device, a desuperheater, and heating users. The deaerator, pre-pump, feedwater pump, high-pressure heater, and auxiliary high-pressure heater are sequentially connected by pipelines. The boiler heating surfaces include an economizer device and water-cooled walls. The economizer device includes an independent or integrated feedwater heating surface and a steam heating surface. The feedwater heating surface and the steam heating surface are completely isolated or can be operated to be completely isolated. The feedwater heating surface is equipped with a water-side bypass or a flue gas bypass. The additional high-pressure heater is connected to the water-cooled wall via the feedwater heating surface piping. The heating medium source piping is connected to the inlet of the pressure-boosting heating device. The outlet piping of the pressure-boosting heating device is connected to the inlet of the heating steam heating surface. The outlet piping of the heating steam heating surface is connected to the steam inlet of the desuperheater. The steam outlet piping of the desuperheater is connected to the heating user. The pressure-boosting heating device is also connected to the desuperheating water inlet of the desuperheater. The pressure-boosting heating device includes a pressure-boosting heating unit, and the pressure-boosting heating unit includes a booster pump. The pre-pump is an independent electric pre-pump.

2. The steam heating system based on feedwater supplementary heating as described in claim 1, characterized in that, The heating medium is sourced from the low-pressure condensate between the deaerator and the pre-pump. The pressurization heating device includes at least one cascaded pressurization heating unit, which includes a booster pump, a mixing heater, and a regenerative extraction steam. The low-pressure condensate is connected to the inlet of the heating steam receiving surface via the booster pump and the mixing heater. The regenerative extraction steam is connected to the steam inlet of the mixing heater. The outlet of the booster pump is also connected to the desuperheating water inlet of the desuperheater.

3. The steam heating system based on feedwater supplementary heating as described in claim 2, characterized in that, It also includes a heat exchanger, a regenerative heater, and another regenerative extraction steam. The cold end pipe of the heat exchanger is connected between the outlet of the pressurized heating device and the inlet of the heating steam heating surface. The hot end pipe of the heat exchanger is connected to the regenerative heater and the other regenerative extraction steam respectively.

4. The steam heating system based on feedwater supplementary heating as described in claim 2, characterized in that, It also includes a heat exchanger, a regenerative heater, and another regenerative extraction steam. The cold end pipe of the heat exchanger is connected between the outlet of the heating steam receiving surface and the steam inlet of the desuperheater. The hot end pipe of the heat exchanger is connected to the regenerative heater and the other regenerative extraction steam respectively.

5. The steam heating system based on feedwater supplementary heating as described in claim 1, characterized in that, The heating medium source is the medium-pressure feedwater between the pre-pump and the feedwater pump. The pressure-boosting heating device includes a pressure-boosting heating unit, which includes a booster pump, a mixing heater, and a regenerative steam extraction unit. The medium-pressure feedwater is connected to the inlet of the heating steam receiving surface via the booster pump and the mixing heater. The regenerative steam extraction unit is connected to the steam inlet of the mixing heater. The outlet of the booster pump is also connected to the desuperheating water inlet of the desuperheater.

6. The steam heating system based on feedwater supplementary heating as described in claim 1, characterized in that, The heating medium source is the medium-pressure feedwater between the pre-pump and the feedwater pump. The pre-pump is an independent electric pre-pump. The pressure-boosting heating device includes a pressure-boosting heating unit, which includes a regulating valve, a mixing heater, and a regenerative steam extraction unit. The medium-pressure feedwater is connected to the inlet of the heating steam receiving surface via the regulating valve and the mixing heater. The regenerative steam extraction unit is connected to the steam inlet of the mixing heater. The outlet of the regulating valve is also connected to the desuperheating water inlet of the desuperheater.

7. The steam heating system based on feedwater supplementary heating as described in claim 1, characterized in that, The heating medium is sourced from the normal condensate drain of the high-pressure regenerative heater. The pressure boosting heating device includes a pressure boosting heating unit, which comprises a booster pump, a mixing heater, and regenerative steam extraction. The normal condensate drain of the high-pressure regenerative heater is connected to the inlet of the heating steam receiving surface via the booster pump and the mixing heater pipeline. The regenerative steam extraction pipeline is connected to the steam inlet of the mixing heater. The outlet of the booster pump is also connected to the desuperheating water inlet of the desuperheater.

8. The steam heating system based on feedwater supplementary heating as described in claim 1, characterized in that, The heating medium is sourced from the emergency drain of the high-pressure regenerative heater. The pressurization heating device includes a pressurization heating unit, which comprises a booster pump, a mixing heater, and regenerative steam extraction. The normal drain of the high-pressure regenerative heater is connected to the inlet of the heating steam receiving surface via the booster pump and the mixing heater pipeline. The regenerative steam extraction pipeline is connected to the steam inlet of the mixing heater. The outlet of the booster pump is also connected to the desuperheating water inlet of the desuperheater.

9. The steam heating system based on feedwater supplementary heating as described in claim 1, characterized in that, The heating medium is sourced from the low-pressure condensate between the deaerator and the pre-pump. The pressurization heating device includes a pressurization heating unit, which includes a booster pump but does not include a mixing heater or regenerative steam extraction. The low-pressure condensate is connected to the inlet of the heating steam heating surface via the booster pump pipeline, and the outlet of the booster pump is also connected to the desuperheating water inlet of the desuperheater.

10. The steam heating system based on feedwater supplementary heating as described in claim 1, characterized in that, The additional high-pressure heater includes an additional high-pressure heater body and an external steam cooler, which are arranged in series or in parallel along the feedwater flow pipeline.

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