A heat supply system and operation method for realizing deep decoupling of boiler and furnace

Abstract

The application discloses a kind of heat supply system and operating method for realizing boiler depth decoupling, the system includes boiler system and heat supply component, boiler system includes steam pocket, heat supply component includes dual-phase evaporator, superheater and low-temperature heat exchanger, feed water is heated into high-temperature steam by dual-phase evaporator and superheater, steam in steam pocket provides heat source for dual-phase evaporator, low return steam provides heat source for heat exchanger, and low-temperature heat exchanger is used to recover the drain heat of high-temperature steam outlet end of dual-phase evaporator.The application extracts part of high-temperature steam in boiler, which is used to heat feed water to generate steam for external heat supply, reduces the steam entering steam turbine for work, ensures the stability of industrial steam supply of unit, greatly improves the deep peak shaving performance of unit, and realizes the deep decoupling of boiler load and steam turbine load.

Description

Technical Field

[0001] This invention relates to the field of coal-fired power generation technology, and in particular to a heating system and operation method that achieves deep decoupling between the boiler and the generator. Background Technology

[0002] Combined heat and power (CHP) units have inherent advantages in the cascade utilization of energy, significantly improving the thermal efficiency of coal-fired power units and reducing total pollutant emissions. They are one of the most stable, reliable, and efficient heat sources for winter heating and an ideal alternative to small coal-fired industrial boilers near power plants. However, CHP units also exhibit strong thermoelectric coupling characteristics. During periods of low grid load, they often cannot further reduce the electrical load due to the need to ensure heating, while during periods of high grid load, they cannot operate at full load (electrical load) due to the demand for heating.

[0003] Based on the type of retrofit technology, the technologies currently applicable to thermoelectric decoupling can be divided into two categories: one is external technologies such as electric boilers and thermal storage devices, and the other is turbine-side heating retrofit technologies such as high back pressure, zero output, and high / low bypass. External thermal storage technology has a high initial investment cost and occupies a large area; turbine-side heating retrofit technologies such as high back pressure, zero output, and high / low bypass often cause safety problems such as reheater overheating, excessive humidity in the final stage, and axial thrust imbalance during deep peak shaving. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in the related art.

[0005] Therefore, embodiments of the present invention propose a heating system and operation method that achieves deep decoupling between the boiler and the boiler.

[0006] On the one hand, this invention proposes a heating system that achieves deep decoupling between the boiler and the turbine, comprising:

[0007] Boiler system, the boiler system including a steam drum;

[0008] The heating assembly includes a dual-phase evaporator, a superheater, and a low-temperature heat exchanger. Feedwater is heated into high-temperature steam by the dual-phase evaporator and the superheater. Steam in the steam drum provides a heat source for the dual-phase evaporator, and low-temperature steam provides a heat source for the heat exchanger. The low-temperature heat exchanger is used to recover the waste heat from the condensate drain at the hot side outlet of the dual-phase evaporator.

[0009] In some embodiments, a portion of the steam in the steam drum is heated by boiler flue gas to become main steam, and the other portion enters the two-phase evaporator and the low-temperature heat exchanger in sequence for heat exchange before entering the condenser.

[0010] In some embodiments, the hot-side inlet of the duplex evaporator is connected to the steam outlet of the steam drum, and the hot-side outlet of the duplex evaporator is connected to the hot-side inlet of the low-temperature heat exchanger.

[0011] In some embodiments, the cold-side inlet of the dual-phase evaporator is connected to the outlet of the feedwater pump, the cold-side outlet of the dual-phase evaporator is connected to the cold-side inlet of the superheater, and the cold-side outlet of the superheater is connected to the steam demand assembly.

[0012] In some embodiments, the hot-side outlet of the low-temperature heat exchanger is connected to the inlet of the condenser, the cold-side inlet of the low-temperature heat exchanger is connected to the outlet pipeline of the condensate pump, and the cold-side outlet of the low-temperature heat exchanger is connected to the inlet of the deaerator.

[0013] In some embodiments, a steam regulating valve is provided on the pipeline between the hot-side inlet of the two-phase evaporator and the steam outlet of the steam drum.

[0014] In some embodiments, a pressure reducing valve is installed on the pipeline between the condenser and the hot-side outlet of the low-temperature heat exchanger, and a feedwater regulating valve is installed on the pipeline between the cold-side inlet of the dual-phase evaporator and the feedwater pump.

[0015] In some embodiments, the boiler system further includes a high-temperature reheater, the hot-side outlet of the superheater being connected to the cold-side inlet of the high-temperature reheater, and low-temperature reheat steam sequentially entering the superheater and the high-temperature reheater to exchange heat and become hot reheat steam.

[0016] In some embodiments, the boiler system further includes a water-cooled wall, through which liquid water in the steam drum absorbs heat and evaporates into steam before returning to the steam drum.

[0017] On the other hand, this invention proposes an operation method for a heating system that achieves deep decoupling between the boiler and the turbine, comprising the following steps:

[0018] When the unit requires deep peak shaving, the boiler maintains stable combustion load operation, and the opening of the pressure reducing valve, steam regulating valve and feedwater regulating valve are adjusted so that some of the steam in the steam drum enters the two-phase evaporator to heat the feedwater to generate steam. At the same time, the condensate absorbs the residual heat of the hydrophobic water in the two-phase evaporator.

[0019] Steam from the cold side outlet of the dual-phase evaporator enters the superheater, is reheated by low-temperature reheat steam, and then goes to the steam-receiving components.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] This invention extracts some high-temperature steam from inside the boiler to heat feedwater and generate steam for external heating, thereby reducing the amount of steam entering the turbine to do work. This ensures stable industrial steam supply to the unit while significantly improving the unit's deep peak-shaving performance and achieving deep decoupling between boiler load and turbine load. Attached Figure Description

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0023] Figure 1 This is a schematic diagram of the heating system that achieves deep decoupling between the boiler and the machine according to the present invention;

[0024] Explanation of reference numerals in the attached figures:

[0025] 1. Water-cooled wall; 2. Steam drum; 3. Low-temperature superheater; 4. Screen-type superheater; 5. High-temperature reheater; 6. Low-temperature heat exchanger; 7. Two-phase evaporator; 8. Superheater; 9. Pressure reducing valve; 10. Feedwater regulating valve; 11. Steam regulating valve; 12. Downcomer; 13. Detailed Implementation

[0026] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0027] The following description, with reference to the accompanying drawings, describes a heating system and its operation method that achieves deep decoupling between the boiler and the turbine according to an embodiment of the present invention.

[0028] like Figure 1 As shown, the heating system of the present invention, which achieves deep decoupling of boiler and boiler, includes a boiler system and heating components.

[0029] The boiler system includes a steam drum 2, a water-cooled wall 1, a low-temperature superheater 3, a screen-type superheater 4, a high-temperature superheater 5, and a high-temperature reheater 6. Following the conventional flue gas flow, the water-cooled wall 1, the screen-type superheater 4, the high-temperature superheater 5, the high-temperature reheater 6, and the low-temperature superheater 3 are arranged in sequence. The water-cooled wall 1 is arranged around the furnace, the screen-type superheater 4 is arranged in the upper part of the furnace, and the high-temperature superheater 5 and the high-temperature reheater 6 are arranged behind the screen-type superheater 4 on the horizontal flue. The low-temperature superheater 3 is arranged on the tail flue.

[0030] The liquid water inside steam drum 2 evaporates into steam through the water-cooled wall 1 and then returns to steam drum 2. Specifically, as follows: Figure 1As shown, the liquid water outlet in the steam drum 2 is connected to the upper end of the downcomer 13, the lower end outlet of the downcomer 13 is connected to the lower end inlet of the water-cooled wall 1, and the upper end outlet of the water-cooled wall 1 is connected to the steam inlet of the steam drum 2. The liquid water in the steam drum 2 enters the water-cooled wall 1 through the downcomer 13, absorbs the heat of the flue gas, and becomes steam, which then enters the steam drum 2 from the steam inlet.

[0031] The heating components include a duplex evaporator 8, a superheater 9, and a low-temperature heat exchanger 7. Feedwater is heated into high-temperature steam by the duplex evaporator 8 and the superheater 9. The steam in the steam drum 2 provides a heat source for the duplex evaporator 8, and the low-temperature reheat steam provides a heat source for the superheater 9. The low-temperature heat exchanger 7 is used to recover the waste heat from the condensate drain at the hot side outlet of the duplex evaporator 8. The low-temperature reheat steam is the steam at the outlet of the low-temperature reheater, which is a conventionally used device in the boiler system.

[0032] In steam drum 2, a portion of the steam is heated by boiler flue gas to become main steam, while the other portion sequentially enters the two-phase evaporator 8 and the low-temperature heat exchanger 7 for heat exchange before entering the condenser. Specifically, a portion of the steam in steam drum 2 sequentially enters the low-temperature superheater 3, the screen-type superheater 4, and the high-temperature superheater 5 to be heated by the flue gas in the boiler to become main steam, while the other portion of the steam in steam drum 2 sequentially enters the two-phase evaporator 8 and the low-temperature heat exchanger 7 to release heat before entering the condenser.

[0033] The hot-side inlet of the duplex evaporator 8 is connected to the steam outlet of the steam drum 2, and the hot-side outlet of the duplex evaporator 8 is connected to the hot-side inlet of the cryogenic heat exchanger 7. The cold-side inlet of the duplex evaporator 8 is connected to the feedwater pump outlet, and the cold-side outlet of the duplex evaporator 8 is connected to the cold-side inlet of the superheater 9. The cold-side outlet of the superheater 9 is connected to the steam demand assembly. The hot-side outlet of the cryogenic heat exchanger 7 is connected to the condenser inlet, and the cold-side inlet of the cryogenic heat exchanger 7 is connected to the condensate pump outlet pipeline. The cold-side outlet of the cryogenic heat exchanger 7 is connected to the deaerator inlet.

[0034] Specifically, a steam regulating valve 12 is installed on the pipeline between the hot side inlet end of the duplex evaporator 8 and the steam outlet end of the steam drum 2 to regulate the amount of steam entering the duplex evaporator 8. A pressure reducing valve 10 is installed on the pipeline between the condenser and the hot side outlet end of the low-temperature heat exchanger 7 to regulate the fluid pressure entering the condenser. A feedwater regulating valve 11 is installed on the pipeline between the cold side inlet end of the duplex evaporator 8 and the feedwater pump to regulate the feedwater flow rate entering the duplex evaporator 8. The hot-side inlet of the duplex evaporator 8 is connected to the steam outlet of the steam drum 2 via a steam regulating valve 12. The hot-side outlet of the duplex evaporator 8 is connected to the hot-side inlet of the low-temperature heat exchanger 7. The cold-side inlet of the duplex evaporator 8 is connected to the outlet of the feedwater pump via a feedwater regulating valve 11. The cold-side outlet of the duplex evaporator 8 is connected to the cold-side inlet of the superheater 9. Steam in the steam drum 2 enters the hot side of the duplex evaporator 8 via the steam regulating valve 12. Water from the feedwater pump outlet enters the cold side of the duplex evaporator 8 via the feedwater regulating valve 11. In the duplex evaporator 8, the steam on the hot side exchanges heat with the feedwater on the cold side. The steam after heat exchange becomes condensate and enters the hot side of the low-temperature heat exchanger 7. The feedwater after heat exchange becomes steam and enters the cold side of the superheater 9.

[0035] The hot-side inlet of the low-temperature heat exchanger 7 is connected to the hot-side outlet of the duplex evaporator 8. The hot-side outlet of the low-temperature heat exchanger 7 is connected to the condenser inlet via a pressure reducing valve 10. The cold-side inlet of the low-temperature heat exchanger 7 is connected to the condensate pump outlet, and the cold-side outlet of the low-temperature heat exchanger 7 is connected to the deaerator inlet. The condensate flowing out of the hot-side outlet of the duplex evaporator 8 enters the hot side of the low-temperature heat exchanger 7, and the condensate from the condensate pump enters the cold side. In the low-temperature heat exchanger 7, the condensate on the hot side exchanges heat with the condensate on the cold side, and the waste heat of the condensate is recovered by the condensate, thus avoiding heat waste. The condensate after heat exchange enters the condenser via the pressure reducing valve 10, and the condensate after heat exchange is heated and then enters the deaerator. The condenser, deaerator, condensate pump, and feedwater pump are all commonly used equipment in power generation systems and will not be described in detail here.

[0036] The cold-side inlet of superheater 9 is connected to the cold-side outlet of the duplex evaporator 8, which is also connected to the steam demand assembly. The hot-side inlet of superheater 9 is connected to the outlet of the low-temperature reheater, and the hot-side outlet of superheater 9 is connected to the cold-side inlet of the high-temperature reheater 6. Steam from the cold-side outlet of the duplex evaporator 8 enters the cold side of superheater 9, while low-temperature reheat steam from the outlet of the low-temperature reheater enters the hot side of superheater 9. In superheater 9, the low-temperature reheat steam on the hot side exchanges heat with the steam on the cold side, and the steam after heat exchange is further heated to high-temperature steam, increasing the superheat of the steam at the outlet of the duplex evaporator 8. The heated steam goes to the steam demand assembly, for example, to supply industrial steam. The low-temperature reheat steam after heat exchange enters the high-temperature reheater 6, where it is heated by boiler flue gas to become hot reheat steam.

[0037] A method for operating a heating system that achieves deep decoupling of the boiler and turbine, comprising the following steps:

[0038] When the unit needs deep peak shaving, the boiler maintains stable combustion load operation, and adjusts the opening of pressure reducing valve 10, steam regulating valve 12 and feedwater regulating valve 11 so that some of the steam in the steam drum 2 enters the two-phase evaporator 8 to heat the feedwater and generate steam. At the same time, the condensate absorbs the residual heat of the hydrophobic water in the two-phase evaporator 8.

[0039] Steam from the cold side outlet of the dual-phase evaporator 8 enters the superheater 9, is reheated by low-temperature reheat steam, and then goes to the steam-receiving components.

[0040] Specifically, when the unit requires deep peak shaving, the boiler maintains stable combustion load operation, and adjusts the opening of pressure reducing valve 10, steam regulating valve 12, and feedwater regulating valve 11 so that some of the steam inside the steam drum 2 enters the two-phase evaporator 8 to heat the feedwater pump water to generate steam. After heat exchange, the condensate absorbs the residual heat of the condensate in the two-phase evaporator 8. The steam from the outlet of the low-temperature reheater enters the superheater 9 to heat the steam from the outlet of the two-phase evaporator 8, increasing the superheat of the steam from the outlet of the two-phase evaporator 8. The steam from the hot side outlet of the superheater 9 enters the high-temperature reheater 6 and is heated by the flue gas to generate hot reheat steam. The steam from the cold side outlet of the superheater 9 is used to supply industrial steam.

[0041] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms may refer to different embodiments or examples. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0042] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0043] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A heating system that achieves deep decoupling between the boiler and the turbine, characterized in that, include: Boiler system, the boiler system including a steam drum; The heating assembly includes a dual-phase evaporator, a superheater, and a low-temperature heat exchanger. Feedwater is heated into high-temperature steam by the dual-phase evaporator and the superheater. The steam in the steam drum provides a heat source for the dual-phase evaporator. The steam at the outlet of the low-temperature reheater provides a heat source for the low-temperature heat exchanger. The low-temperature heat exchanger is used to recover the waste heat from the condensate drain at the hot side outlet of the dual-phase evaporator. Part of the steam in the steam drum is heated by boiler flue gas to become main steam, and the other part enters the two-phase evaporator and the low-temperature heat exchanger in sequence for heat exchange before entering the condenser. The hot-side inlet of the duplex evaporator is connected to the steam outlet of the steam drum, and the hot-side outlet of the duplex evaporator is connected to the hot-side inlet of the low-temperature heat exchanger. The cold-side inlet of the dual-phase evaporator is connected to the outlet of the feedwater pump, the cold-side outlet of the dual-phase evaporator is connected to the cold-side inlet of the superheater, and the cold-side outlet of the superheater is connected to the steam demand assembly. The hot-side outlet of the low-temperature heat exchanger is connected to the inlet of the condenser, the cold-side inlet of the low-temperature heat exchanger is connected to the outlet pipeline of the condensate pump, and the cold-side outlet of the low-temperature heat exchanger is connected to the inlet of the deaerator. The boiler system also includes a high-temperature reheater, the hot-side outlet of which is connected to the cold-side inlet of the high-temperature reheater. Steam from the outlet of the low-temperature reheater sequentially enters the superheater and the high-temperature reheater for heat exchange, becoming... Hot reheat steam .

2. The system as described in claim 1, characterized in that, A steam regulating valve is installed on the pipeline between the hot-side inlet of the dual-phase evaporator and the steam outlet of the steam drum.

3. The system as described in claim 2, characterized in that, A pressure reducing valve is installed on the pipeline between the condenser and the hot-side outlet of the low-temperature heat exchanger, and a feedwater regulating valve is installed on the pipeline between the cold-side inlet of the dual-phase evaporator and the feedwater pump.

4. The system as described in claim 1, characterized in that, The boiler system also includes a water-cooled wall, through which liquid water in the steam drum absorbs heat and evaporates into steam before returning to the steam drum.

5. A method for operating a heating system that achieves deep decoupling between the boiler and the turbine, characterized in that, The system applicable to claim 3 includes the following steps: When the unit requires deep peak shaving, the boiler maintains stable combustion load operation, and the opening of the pressure reducing valve, steam regulating valve and feedwater regulating valve are adjusted so that some of the steam in the steam drum enters the two-phase evaporator to heat the feedwater to generate steam. At the same time, the condensate absorbs the residual heat of the hydrophobic water in the two-phase evaporator. Steam from the cold side outlet of the two-phase evaporator enters the superheater, is reheated by the steam from the outlet of the low-temperature reheater, and then goes to the steam-requiring components.

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