External Steam Regeneration System for Thermal Power Plants
By introducing plate heat exchangers and condensate booster pumps into the thermal power plant, the problem of mismatch between the pressure difference and steam volume between the back pressure turbine exhaust and the deaerator has been solved, achieving efficient utilization of thermal energy and flexible system operation, which is in line with energy conservation and emission reduction policies.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- CHINA UNITED ENG
- Filing Date
- 2025-06-27
- Publication Date
- 2026-07-31
AI Technical Summary
In the existing technology, the large pressure difference between the back pressure turbine exhaust and the deaerator working pressure leads to increased irreversible losses. Furthermore, the exhaust volume of the driven turbine does not match the demand of the intermediate heater, resulting in inflexible system operation and limited improvement in thermal efficiency.
The system employs a plate heat exchanger and a condensate booster pump. The steam produced by the exhaust pressure of the back pressure turbine is converted into low-pressure steam, which is then matched with a high-pressure deaerator via a plate heat exchanger. An auxiliary motor is installed to drive the feed water pump, enabling flexible matching of steam volume and tiered utilization of thermal energy.
This achieves a match between the exhaust steam volume of the driven steam turbine and the demand of the plate heat exchanger, reduces plant power consumption, improves thermal energy utilization efficiency, enhances system flexibility and thermal efficiency, and complies with energy conservation and emission reduction policies.
Smart Images
Figure CN224579377U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to a system for enhancing the efficiency of external steam supply in thermal power plants. Background Technology
[0002] Traditional back-pressure heating units have the following problems when supplying steam to external users:
[0003] 1. In addition to supplying heat to the outside, the exhaust steam from the back pressure turbine also deaerators the feedwater for heating, and currently, a single-stage deaeration scheme is basically adopted. There is often a large difference between the exhaust steam pressure and the deaerator operating pressure. The larger the difference, the greater the irreversible loss, which affects the economics of the regenerative system.
[0004] 2. To reduce the aforementioned irreversible losses, a makeup water heater is often installed before the deaerator. This makeup water heater uses a low-pressure steam source for heating and is connected to a turbine (whose inlet steam is the exhaust steam from the back-pressure unit, and the exhaust steam is low-pressure steam). A portion of the back-pressure unit's exhaust steam is converted into low-pressure steam by the turbine, and this low-pressure steam is then utilized effectively through the makeup water heater, improving thermal efficiency. Conventional makeup water heaters are surface heaters, which have a differential pressure, leaving room for further improvement in thermal efficiency.
[0005] To address the above two issues, the applicant applied for a Chinese patent with patent number 202420864274.4, entitled "Multi-stage Stepped Regenerative Efficiency Enhancement System for Thermal Power Plants," which can reduce coal consumption and improve overall energy efficiency. However, further research revealed the following problems with this patented technology:
[0006] The amount of low-pressure steam required by the intermediate heater is often mismatched with the exhaust flow rate of the driven turbine. If the exhaust flow rate of the driven turbine is less than the amount of low-pressure steam required by the intermediate heater, the intermediate heater can only operate at a reduced load, and the remaining required steam can be provided by the exhaust flow rate of the back compressor. If the exhaust flow rate of the driven turbine is greater than the amount of low-pressure steam required by the intermediate heater, the excess low-pressure steam cannot be utilized, and the system cannot solve this problem effectively. Utility Model Content
[0007] The purpose of this utility model is to overcome the above-mentioned shortcomings in the existing technology and provide a thermal power plant external steam regeneration efficiency enhancement system with reasonable structural design. The exhaust steam volume of the driving turbine can be fully matched with the heating steam volume required by the plate heat exchanger, and the insufficient power of the feedwater pump can be assisted by the motor, making the operation more flexible.
[0008] The technical solution adopted by this utility model to solve the above problems is: a power plant external steam regeneration efficiency enhancement system, including a boiler, a back-pressure steam turbine, a high-pressure heater, a high-pressure deaerator, a demineralized water station, a driven steam turbine, a steam-electric dual-drive feedwater pump, and an electric feedwater pump; the boiler's steam outlet is connected to the back-pressure steam turbine's steam inlet, and the back-pressure steam turbine's exhaust outlet is connected to the high-pressure deaerator's inlet, the driven small steam turbine's steam inlet, and the high-pressure heater's hot phase inlet, respectively; the high-pressure deaerator's outlet is connected to the steam-electric dual-drive feedwater pump and the electric feedwater pump; the steam-electric... The outlets of the dual-drive feedwater pump and the electric feedwater pump are connected to the cold phase inlet of the high-pressure heater, and the cold phase outlet of the high-pressure heater is connected to the inlet of the boiler; the hot phase outlet of the high-pressure heater is connected to the inlet of the high-pressure deaerator; the feature is that it also includes a plate heat exchanger, the exhaust port of the back-pressure steam turbine and the exhaust port of the driven small steam turbine are both connected to the hot phase inlet of the plate heat exchanger, and the hot phase outlet of the plate heat exchanger is connected to the inlet of the high-pressure deaerator; the demineralized water station is connected to the cold phase inlet of the plate heat exchanger, and the cold phase outlet of the plate heat exchanger is connected to the inlet of the high-pressure deaerator.
[0009] In this utility model plate heat exchanger, a heat exchanger pressure regulating valve is provided on the hot phase inlet connected to the exhaust port of the back-pressure steam turbine.
[0010] The hot phase outlet of the plate heat exchanger described in this utility model is connected to the inlet of the high-pressure deaerator through a condensate drain pipe, and a condensate booster pump is installed on the condensate drain pipe.
[0011] The hydrophobic booster pump described in this utility model consists of two units, one in operation and one on standby.
[0012] The cold phase outlet of the plate heat exchanger described in this utility model is connected to the inlet of the high-pressure deaerator through a demineralized water pipeline, and a water replenishment regulating valve is installed on the demineralized water pipeline.
[0013] This utility model also includes a generator, a back-pressure steam turbine, and a connection between the generator and the generator.
[0014] In this utility model of high-pressure deaerator, a deaerator pressure regulating valve is provided at the inlet connected to the exhaust port of the back-pressure steam turbine.
[0015] This utility model includes a motor on both the steam-electric dual-drive water pump and the electric water pump.
[0016] Compared with the prior art, this utility model has the following advantages and effects:
[0017] 1. Set up a turbine system to drive the feedwater pump. Make full use of the high exhaust pressure of the back pressure turbine to do work first, and after it is reduced to low-pressure steam, the residual heat can still be utilized, thus utilizing thermal energy in a stepped manner and reducing the consumption of plant power.
[0018] 2. The total capacity of the steam-electric dual-drive feedwater pump is designed to meet the maximum feedwater demand of one boiler. The exhaust steam output of the driven steam turbine matches the low-pressure steam required by the plate heat exchanger. The difference between the two, i.e., the portion of the driven steam turbine's power that is insufficient, can be assisted by the electric motor, making operation more flexible. This solves the systemic problem of the excess low-pressure steam being unusable when the exhaust steam output of a single driven steam turbine exceeds the plate heat exchanger's requirements.
[0019] 3. Plate heat exchangers are used to reduce heat exchange differences at the ends; a high-pressure heater and surface heater system are installed to further realize a stepped regeneration system.
[0020] 4. This utility model complies with the national industrial policy of improving the overall efficiency of thermal power and the energy conservation and emission reduction policy. It plays a positive role in local environmental protection and reducing air pollution, and has certain energy-saving, environmental and social benefits. Attached Figure Description
[0021] Figure 1 This is a structural schematic diagram of an embodiment of the present utility model. Detailed Implementation
[0022] The present invention will be further described in detail below with reference to the accompanying drawings and through embodiments. The following embodiments are explanations of the present invention, but the present invention is not limited to the following embodiments.
[0023] This utility model embodiment includes a boiler 1, a back-pressure steam turbine 2, a generator 3, a high-pressure heater 4, a high-pressure deaerator 5, a demineralized water station 6, a plate heat exchanger 7, a driven steam turbine 8, a motor 9, a steam-electric dual-drive feedwater pump 10, an electric feedwater pump 11, a condensate booster pump 12, a deaerator pressure regulating valve 13, a makeup water regulating valve 14, and a heat exchanger pressure regulating valve 15.
[0024] The steam outlet of boiler 1 is connected to the steam inlet of back-pressure steam turbine 2 via main steam pipeline 01, and the exhaust outlet of back-pressure steam turbine 2 is connected to the steam heat user via exhaust pipeline 02. The exhaust outlet of back-pressure steam turbine 2 is connected to the inlet of high-pressure deaerator 5 via steam pipeline 03. A deaerator pressure regulating valve 13 is installed on the inlet of high-pressure deaerator 5 to control the constant pressure operation of high-pressure deaerator 5. The exhaust outlet of back-pressure steam turbine 2 is connected to the steam inlet of the driven small steam turbine 8 via steam pipeline 04.
[0025] The steam-electric dual-drive feedwater pump 10 and the electric feedwater pump 11 are connected in parallel. Both the steam-electric dual-drive feedwater pump 10 and the electric feedwater pump 11 are equipped with motors 9. Under normal operating conditions, the steam-electric dual-drive feedwater pump 10 is in operation, and the electric feedwater pump 11 is on standby. The outlet of the high-pressure deaerator 5 is connected to the inlet of the steam-electric dual-drive feedwater pump 10 and the inlet of the electric feedwater pump 11 through a low-pressure feedwater pipeline 09. The outlets of the steam-electric dual-drive feedwater pump 10 and the electric feedwater pump 11 are connected to the cold phase inlet of the high-pressure heater 4 through a high-pressure feedwater pipeline 010. The cold phase outlet of the high-pressure heater 4 is connected to the inlet of the boiler 1 through a high-pressure feedwater pipeline 011. The exhaust port of the back-pressure turbine 2 is connected to the hot phase inlet of the high-pressure heater 4 through an extraction steam pipeline 012. The hot phase outlet of the high-pressure heater 4 is connected to the inlet of the high-pressure deaerator 5 through a drain pipeline 013.
[0026] The back-pressure steam turbine 2 and the generator 3 are connected.
[0027] The exhaust port of the back-pressure steam turbine 2 is connected to the hot phase inlet of the plate heat exchanger 7 via steam pipeline 03. A heat exchanger pressure regulating valve 15 is installed on the hot phase inlet to control the standby steam flow of the plate heat exchanger 7. The exhaust port of the drive turbine 8 is connected to the hot phase inlet of the plate heat exchanger 7 via exhaust pipeline 05. The hot phase outlet of the plate heat exchanger 7 is connected to the inlet of the high-pressure deaerator 5 via condensate pipeline 06. A condensate booster pump 12 is installed on condensate pipeline 06. There are two condensate booster pumps 12, one in operation and one on standby. The demineralized water station 6 is connected to the cold phase inlet of the plate heat exchanger 7 via demineralized water pipeline 07. The cold phase outlet of the plate heat exchanger 7 is connected to the inlet of the high-pressure deaerator 5 via demineralized water pipeline 08. A makeup water regulating valve 14 is installed on demineralized water pipeline 08 for makeup water flow control.
[0028] The operation mode of this utility model is as follows:
[0029] Boiler 1 supplies main steam to back-pressure turbine 2 through main steam pipeline 01. Back-pressure turbine 2 supplies heat to steam users through exhaust pipeline 02, and at the same time, back-pressure turbine 2 supplies heating steam to high-pressure deaerator 5 through steam pipeline 03, and maintains a certain working pressure of high-pressure deaerator 5 through regulating valve 13.
[0030] Back-pressure turbine 2 supplies steam to drive turbine 8 via steam pipeline 04. Driven turbine 8 performs work to drive dual-drive feedwater pump 10, and motor 9 can also drive dual-drive feedwater pump 10. Low-pressure exhaust steam from driven turbine 8 after its work is supplied to plate heat exchanger 7 via exhaust pipeline 05. Condensed condensate is pressurized via condensate booster pump 12 via condensate booster pipeline 06 and then enters high-pressure deaerator 5.
[0031] The demineralized water preparation station 6 delivers qualified demineralized water through demineralized water pipelines 07 and 08, preheats it via plate heat exchanger 7, and then supplies it to the high-pressure deaerator 5. A regulating valve is installed on this pipeline for flow control. The high-pressure deaerator 5 then pressurizes the feedwater via pipeline 09 to a dual-drive steam-electric feedwater pump 10 or an electric feedwater pump 11, before sequentially passing through high-pressure feedwater pipeline 010, high-pressure heater 4, and high-pressure feedwater pipeline 011 into boiler 1. A back-pressure turbine with a first-stage non-adjustable extraction steam source delivers the feedwater through pipeline 012 to the high-pressure heater 4 to heat the feedwater. After condensation, the condensate flows through pipeline 013 into the high-pressure deaerator 5.
[0032] The total output of the dual-drive steam-electric feedwater pump 10 meets the maximum feedwater demand of one boiler. The capacity of the steam-driven section is designed to match the exhaust steam of the driven steam turbine 8 with the low-pressure steam required by the plate heat exchanger 7. The remaining feedwater pump output is driven by an electric motor. When the exhaust steam of the driven steam turbine 8 does not match the low-pressure steam required by the plate heat exchanger 7, the load of the steam-driven section is adjusted to match the required low-pressure steam, and the load of the electric motor is also adjusted. When the maximum exhaust steam of the driven steam turbine 8 is still less than the required low-pressure steam of the plate heat exchanger 7, the deaerator pressure regulating valve 13 can be opened to use part of the exhaust steam from the back-pressure steam turbine 2 as supplementary heating steam for the plate heat exchanger 7.
[0033] When the steam-electric dual-drive feedwater pump 10 is under maintenance or malfunctioning, the heat exchanger pressure regulating valve 15 is opened, and the heating steam source for the plate heat exchanger 7 is the exhaust steam from the back-pressure steam turbine 2. The steam-electric dual-drive feedwater pump 10 is disconnected from the system, and the standby electric feedwater pump 11 is started.
[0034] Furthermore, it should be noted that the specific embodiments described in this specification may differ in the shape and name of their components. The above description is merely illustrative of the structure of this utility model. All equivalent or simple variations made based on the structure, features, and principles described in this utility model patent concept are included within the protection scope of this utility model patent. Those skilled in the art to which this utility model pertains may make various modifications or additions to the described specific embodiments or use similar methods to replace them, as long as they do not deviate from the structure of this utility model or exceed the scope defined in these claims, all of which should fall within the protection scope of this utility model.
Claims
1. A power plant external steam regeneration efficiency enhancement system, comprising a boiler, a back-pressure steam turbine, a high-pressure heater, a high-pressure deaerator, a demineralized water station, a driven steam turbine, a steam-electric dual-drive feedwater pump, and an electric feedwater pump; the boiler's steam outlet is connected to the back-pressure steam turbine's steam inlet, and the back-pressure steam turbine's exhaust outlet is connected to the high-pressure deaerator's inlet, the driven small steam turbine's steam inlet, and the high-pressure heater's hot-phase inlet, respectively; the high-pressure deaerator's outlet is connected to the steam-electric dual-drive feedwater pump and the electric feedwater pump's inlet; the steam-electric dual-drive feedwater pump and the electric feedwater pump's outlet are connected to the high-pressure heater's cold-phase inlet, and the high-pressure heater's cold-phase outlet is connected to the boiler's inlet; the high-pressure heater's hot-phase outlet is connected to the high-pressure deaerator's inlet; characterized in that: It also includes plate heat exchangers. The exhaust ports of the back-pressure steam turbine and the exhaust ports of the driven small steam turbine are connected to the hot phase inlet of the plate heat exchanger. The hot phase outlet of the plate heat exchanger is connected to the inlet of the high-pressure deaerator. The demineralized water station is connected to the cold phase inlet of the plate heat exchanger, and the cold phase outlet of the plate heat exchanger is connected to the inlet of the high-pressure deaerator.
2. The heat recovery steam generator regenerative system of claim 1, wherein: In plate heat exchangers, a heat exchanger pressure regulating valve is installed at the hot phase inlet connected to the exhaust port of the back-pressure steam turbine.
3. The thermal plant external steam feed heat recovery boosting system of claim 1, wherein: The hot phase outlet of the plate heat exchanger is connected to the inlet of the high-pressure deaerator via a condensate drain pipe, on which a condensate booster pump is installed.
4. The heat recovery steam generator regenerative system of claim 3, wherein: The aforementioned hydrophobic booster pump consists of two units, one in operation and one on standby.
5. The thermal plant external steam feed heat recovery boosting system of claim 1, wherein: The cold phase outlet of the plate heat exchanger is connected to the inlet of the high-pressure deaerator via a demineralized water pipeline, on which a water supply regulating valve is installed.
6. The thermal plant external steam feed heat recovery boosting system of claim 1, wherein: It also includes generators, back-pressure steam turbines, and generator connections.
7. The thermal plant external steam feed heat recovery boosting system of claim 1, wherein: In a high-pressure deaerator, a deaerator pressure regulating valve is installed at the inlet connected to the exhaust port of a back-pressure steam turbine.
8. The thermal plant external steam feed heat recovery boosting system of claim 1, wherein: Both the steam-electric dual-drive water pump and the electric water pump are equipped with motors.