System for synchronously increasing low-load hot air temperature and feed water temperature of coal-fired boiler

Abstract

The utility model relates to the technical field of energy conservation of coal-fired boilers, in particular to a system for synchronously improving the low-load hot air temperature and the feed water temperature of a coal-fired boiler, which utilizes superheated steam to improve the hot air temperature and the feed water temperature of the boiler. Particularly, under the low-load working condition, the hot air temperature and the feed water temperature of the boiler are effectively increased through the steam extraction module, the pressure and temperature reduction module, the hot air heating module, the feed water heating module and the like. The system comprises a steam extraction module, a steam pressure reduction and temperature reduction module, a hot air heating module, a first high-pressure heater module, a system control module, an air preheater module, a boiler system module and other modules, all the modules work cooperatively, the combustion efficiency and the power generation performance of the boiler are remarkably improved, the environmental protection standard is met, and the overall economic benefits are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of energy-saving of coal-fired boilers, in particular to a system that utilizes superheated steam to synchronously increase the low-load hot air temperature and boiler feed water temperature of a coal-fired boiler. Background Art

[0002] Currently, large-scale coal-fired power plants in China generally use selective catalytic reduction (SCR) for denitrification, which is an effective means of reducing nitrogen oxide emissions. However, the use of SCR technology requires maintaining a certain flue gas temperature, usually above 300°C, to ensure catalyst activity and denitrification efficiency.

[0003] Although SCR technology has been widely adopted, practical operation still presents technical challenges. In particular, when units are operating at low load, the SCR inlet flue gas temperature may fall below 300°C, causing the SCR to malfunction, leading to problems such as excessive nitrogen oxide emissions, catalyst deactivation, and increased ammonia slip. To address this issue, wide-load denitrification technologies have emerged, such as economizer water-side bypass and flue gas bypass. However, practical application of these technologies is often limited by space requirements, temperature increase, investment costs, and system complexity. Furthermore, under low-load conditions, increasing air volume to ensure normal boiler combustion can increase the excess air coefficient at the furnace outlet and reduce boiler efficiency, thereby increasing unit coal consumption and affecting the overall economic viability of the power plant. Therefore, the thermal power industry urgently needs a new wide-load denitrification technology that meets environmental requirements while maintaining economic benefits. Utility Model Content

[0004] The present utility model provides a system for synchronously increasing the hot air temperature and feed water temperature of a coal-fired boiler under low load. In the utility model, under low load conditions, the temperature of the secondary air entering the boiler is increased by heating the hot air heat exchanger, thereby increasing the heat in the boiler and facilitating stable combustion in the boiler. At the same time, due to the increase in the temperature of the hot air entering the boiler, the flow rate of the hot air can be appropriately reduced, thereby improving the boiler efficiency of the unit under low load conditions.

[0005] The utility model provides a system for synchronously increasing the hot air temperature and feed water temperature of a coal-fired boiler under low load, comprising:

[0006] A steam extraction module is used to extract superheated steam from the outlet of the medium-temperature superheater of the boiler;

[0007] The steam decompression and temperature reduction module is used to decompress and reduce the temperature of the superheated steam extracted from the outlet of the medium-temperature superheater to obtain treated superheated steam;

[0008] The hot air heating module uses the treated superheated steam to heat the hot air at the outlet of the air preheater to increase its temperature. The treated superheated steam is heated by the hot air at the outlet of the air preheater to reduce the heat and obtain the superheated steam after cooling.

[0009] The No. 1 high-pressure heater module uses cooled superheated steam to heat low-temperature feed water to increase the feed water temperature;

[0010] System control module: used to control the operation of the system, including steam extraction, pressure reduction and temperature reduction, hot air heating, and feed water heating.

[0011] Air preheater module: preheats the cold air entering the boiler to increase the initial temperature of the hot air;

[0012] The boiler system module receives heated hot air and high-temperature feed water for combustion and power generation.

[0013] According to the system for simultaneously increasing the low-load hot air temperature and feed water temperature of a coal-fired boiler, the steam extraction module includes: a medium-temperature superheater and a bypass superheated steam isolation valve. The steam extraction module extracts superheated steam from the outlet of the medium-temperature superheater in the boiler system module.

[0014] Furthermore, the utility model provides a system for simultaneously increasing the low-load hot air temperature and feed water temperature of a coal-fired boiler, a steam pressure reducing and temperature reducing module, including: a pressure reducing regulating valve, a temperature reducing water isolation valve, a temperature reducing water regulating valve and a temperature reducer. The steam pressure reducing and temperature reducing module receives the superheated steam extracted by the steam extraction module, and performs pressure reducing and temperature reducing treatment on it.

[0015] Furthermore, the utility model provides a system for simultaneously improving the low-load hot air temperature and feed water temperature of a coal-fired boiler, and a hot air heating module, including: a hot air heat exchanger, and an air preheater outlet hot air duct and a heated hot air duct connected thereto. The hot air heating module uses the superheated steam processed by the steam pressure reduction and temperature reduction module to heat the hot air at the outlet of the air preheater module.

[0016] Furthermore, the utility model provides a system for simultaneously improving the low-load hot air temperature and feed water temperature of a coal-fired boiler, a No. 1 high-pressure heater module, including: a No. 1 high-pressure heater, a low-temperature feed water inlet pipe, a high-temperature feed water outlet pipe, and an access pipe for the superheated steam at the outlet of the hot air heat exchanger. The No. 1 high-pressure heater module receives the superheated steam that has been released after being processed by the steam pressure reducing and temperature reduction module, and uses this steam as a heat source to heat the low-temperature feed water.

[0017] Furthermore, the utility model provides a system for simultaneously improving the low-load hot air temperature and feed water temperature of a coal-fired boiler, and a system control module for controlling the working states of the steam extraction module, the steam pressure reduction and temperature reduction module, the hot air heating module and the No. 1 high-pressure heater module.

[0018] Furthermore, the utility model provides a system for simultaneously improving the low-load hot air temperature and feed water temperature of a coal-fired boiler, an air preheater module, including: an air preheater, a cold air inlet pipe and an air preheater outlet hot air pipe. The air preheater module is used to provide preheated air for the boiler system, and the hot air at its outlet is further heated by the hot air heating module.

[0019] Furthermore, the utility model provides a system for simultaneously improving the low-load hot air temperature and feed water temperature of a coal-fired boiler. The boiler system module includes a boiler body, an economizer, a low-temperature superheater, a medium-temperature superheater, a high-temperature superheater and a high-pressure cylinder of a steam turbine. The boiler system module is used to receive the hot air heated by the hot air heating module and the high-temperature feed water provided by the No. 1 high-pressure heater module for combustion and power generation.

[0020] The beneficial effects of this utility model are as follows: It increases the boiler's hot air and feedwater temperatures, facilitating stable combustion and improving thermal efficiency; optimizes operation under low-load conditions, resolving the issue of insufficient SCR inlet flue gas temperature, and avoiding excessive emissions and catalyst deactivation; achieves energy conservation and emission reduction, enhances system flexibility and reliability, and ensures stable and efficient operation; and simultaneously reduces power plant operating costs and improves economic benefits. Overall, this utility model offers significant technical advantages and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 This is a schematic diagram of a system for simultaneously increasing the low-load hot air temperature and feed water temperature of a coal-fired boiler provided by the utility model.

[0023] Illustration: 1. Boiler; 2. Steam turbine high-pressure cylinder; 3. No. 1 high-pressure heater; 4. First-stage extraction steam isolation valve; 5. Low-temperature feed water; 6. High-temperature feed water; 7. Main steam; 8. First-stage extraction steam; 9. Air preheater; 10. Cold air; 11. Hot air at the outlet of air preheater; 12. Pressure reducing regulating valve; 13. Attempering water isolation valve; 14. Attempering water regulating valve; 15. Desuperheater; 16. Superheated steam at the outlet of hot air heat exchanger; 17. Attempering water; 18. Bypass superheated steam; 19. Attempering and pressure reducing superheated steam; 20. Hot air; 21. Hot air heat exchanger; 22. Bypass superheated steam isolation valve; 23. Pressure reducing superheated steam; 24. Economizer; 25. Low-temperature superheater; 26. Medium-temperature superheater; 27. High-temperature superheater. DETAILED DESCRIPTION

[0024] See also Figure 1 The present invention provides a system for synchronously increasing the low-load hot air temperature and feed water temperature of a coal-fired boiler, comprising:

[0025] A steam extraction module, used to extract superheated steam from the outlet of the medium-temperature superheater 26 of the boiler 1;

[0026] The steam decompression and temperature reduction module is used to decompress and reduce the temperature of the superheated steam extracted from the outlet of the medium-temperature superheater 26 to obtain treated superheated steam;

[0027] The hot air heating module uses the treated superheated steam to heat the hot air at the outlet of the air preheater 9 to increase its temperature. The treated superheated steam is heated by the hot air at the outlet of the air preheater 9 to reduce the heat and obtain the superheated steam after cooling.

[0028] The No. 1 high-pressure heater module uses cooled superheated steam to heat low-temperature feed water to increase the feed water temperature;

[0029] System control module: used to control the operation of the system, including steam extraction, pressure reduction and temperature reduction, hot air heating, and feed water heating.

[0030] Air preheater module: preheats the cold air entering boiler 1 to increase the initial temperature of the hot air;

[0031] The boiler system module receives heated hot air and high-temperature feed water for combustion and power generation.

[0032] According to the system for simultaneously increasing the low-load hot air temperature and feed water temperature of a coal-fired boiler, the steam extraction module includes: a medium-temperature superheater 26 and a bypass superheated steam isolation valve 22. The steam extraction module extracts superheated steam from the outlet of the medium-temperature superheater 26 in the boiler system module.

[0033] Specifically, the utility model provides a system for simultaneously improving the low-load hot air temperature and feed water temperature of a coal-fired boiler, a steam pressure reducing and temperature reducing module, including: a pressure reducing regulating valve 12, a temperature reducing water isolation valve 13, a temperature reducing water regulating valve 14 and a temperature reducer 15. The steam pressure reducing and temperature reducing module receives the superheated steam extracted by the steam extraction module, and performs pressure reducing and temperature reducing treatment on it.

[0034] Specifically, the utility model provides a system for simultaneously improving the low-load hot air temperature and feed water temperature of a coal-fired boiler, and a hot air heating module, including: a hot air heat exchanger 21, and a hot air pipe 11 at the air preheater outlet and a heated hot air pipe 20 connected thereto. The hot air heating module uses the superheated steam treated by the steam pressure reducing and temperature reducing module to heat the hot air at the outlet of the air preheater module.

[0035] Specifically, the utility model provides a system for simultaneously improving the low-load hot air temperature and feed water temperature of a coal-fired boiler, a No. 1 high-pressure heater module, including: a No. 1 high-pressure heater 3, a low-temperature feed water 5 inlet pipe, a high-temperature feed water 6 outlet pipe, and an access pipe for the superheated steam 16 at the outlet of the hot air heat exchanger. The No. 1 high-pressure heater module receives the superheated steam that has been released after being processed by the steam pressure reducing and temperature reducing module, and uses this steam as a heat source to heat the low-temperature feed water 5.

[0036] Specifically, the utility model provides a system for simultaneously improving the low-load hot air temperature and feed water temperature of a coal-fired boiler, and a system control module for controlling the working status of a steam extraction module, a steam pressure reduction and temperature reduction module, a hot air heating module and a No. 1 high-pressure heater module.

[0037] Specifically, the utility model provides a system for simultaneously improving the low-load hot air temperature and feed water temperature of a coal-fired boiler, an air preheater module, including: an air preheater 9, a cold air inlet pipe 10 and an air preheater outlet hot air pipe 11. The air preheater module is used to provide preheated air for the boiler system, and the hot air at its outlet is further heated by the hot air heating module.

[0038] Specifically, the utility model provides a system for simultaneously improving the low-load hot air temperature and feed water temperature of a coal-fired boiler. The boiler system module includes a boiler 1 body, an economizer 24, a low-temperature superheater 25, a medium-temperature superheater 26, a high-temperature superheater 27 and a turbine high-pressure cylinder 2. The boiler system module is used to receive the hot air heated by the hot air heating module and the high-temperature feed water provided by the No. 1 high-pressure heater module for combustion and power generation.

[0039] The connection relationship and position relationship between the structures of the present invention are as follows:

[0040] Boiler 1 is the core of the entire system. After entering the boiler, high-temperature feed water is heated in sequence by economizer 24, low-temperature superheater 25, medium-temperature superheater 26, and high-temperature superheater 27, ultimately producing main steam 7. This main steam 7 is then fed into the high-pressure cylinder 2 of the steam turbine for energy conversion and drives the generator.

[0041] The steam turbine high-pressure cylinder 2 receives main steam 7 from the boiler 1. Under normal circumstances, a first stage of extraction steam 8 drawn from the steam turbine high-pressure cylinder 2 enters the No. 1 high-pressure heater 3. However, in the present invention, under low-load conditions, the first stage of extraction steam isolation valve 4 closes, isolating this section of extraction steam 8.

[0042] Under low load conditions, the inlet steam of the No. 1 high-pressure heater 3 is changed to the superheated steam 19 after being processed by the pressure reducing regulating valve 12 and the desuperheater 15, that is, the superheated steam 16 at the outlet of the hot air heat exchanger.

[0043] The air preheater 9 is located before the boiler 1 . The cold air 10 is heated by the air preheater and becomes hot air 11 at the air preheater outlet. The hot air then enters the hot air heat exchanger 21 for further heating and is finally sent to the boiler 1 .

[0044] The hot air heat exchanger 21 uses the desuperheated and decompressed superheated steam 19 to heat the hot air 11 at the air preheater outlet.

[0045] The pressure reducing regulating valve 12 works in conjunction with the desuperheater 15 to extract bypass superheated steam 18 from the outlet of the medium-temperature superheater 26, and after pressure reduction and temperature reduction treatment, the desuperheated and reduced-temperature superheated steam 19 is obtained and supplied to the hot air heat exchanger 21.

[0046] The attemperating water regulating valve 14 and the attemperating water isolation valve 13 control the flow of the attemperating water 17 to ensure accurate attemperating.

[0047] The working principle of the utility model in actual use is as follows:

[0048] Steam extraction module (including the medium-temperature superheater 26 and the bypass superheated steam isolation valve 22): This module extracts superheated steam from the outlet of the medium-temperature superheater 26 of the boiler 1 to provide the required steam source for subsequent steps.

[0049] Steam decompression and temperature reduction module (including decompression regulating valve 12, temperature reduction water isolation valve 13, temperature reduction water regulating valve 14 and temperature reducer 15): This module will reduce the pressure and temperature of the extracted superheated steam to obtain superheated steam suitable for the subsequent heating process.

[0050] Hot air heating module (main component is hot air heat exchanger 21): This module uses the treated superheated steam to heat the hot air from the outlet of the air preheater 9, increase the temperature of the hot air, and send it to the boiler 1 to assist combustion.

[0051] High-pressure heater module No. 1 (including high-pressure heater No. 1 3): Here, the superheated steam after heat release will be used to heat the low-temperature feed water 5, converting it into high-temperature feed water 6, and then entering the boiler system.

[0052] Air preheater module (including air preheater 9): This module is responsible for preheating the cold air 10 to generate hot air 11 at the air preheater outlet for subsequent heating.

[0053] Boiler system module (core is boiler 1): The boiler receives heated hot air and high-temperature feed water, performs combustion and energy conversion, and ultimately generates main steam 7 for use in the turbine high-pressure cylinder 2, thereby driving the generator to generate electricity.

[0054] System control module: This module is responsible for comprehensively monitoring and regulating the operation of the entire system to ensure that each link is efficient and stable.

[0055] Through such a design, the utility model can use superheated steam to synchronously increase the hot air temperature and feed water temperature of the boiler, aiming to improve the efficiency of the boiler and meet the requirements of environmental protection and energy saving.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A system for synchronously increasing the low-load hot air temperature and feed water temperature of a coal-fired boiler, characterized in that: include: A steam extraction module for extracting superheated steam from an outlet of a medium-temperature superheater (26) of a boiler (1); A steam decompression and temperature reduction module is used to decompress and reduce the temperature of the superheated steam extracted from the outlet of the medium-temperature superheater (26) to obtain treated superheated steam; The hot air heating module uses the processed superheated steam to heat the hot air at the outlet of the air preheater (9) to increase its temperature. The processed superheated steam is heated by the hot air at the outlet of the air preheater (9) to reduce the heat and obtain the superheated steam after cooling. The No. 1 high-pressure heater module uses cooled superheated steam to heat low-temperature feed water to increase the feed water temperature; System control module: used to control the operation of the system, including steam extraction, pressure reduction and temperature reduction, hot air heating, and feed water heating; Air preheater module: preheats the cold air entering the boiler (1) to increase the initial temperature of the hot air; The boiler system module receives heated hot air and high-temperature feed water for combustion and power generation.

2. The system for synchronously increasing the low-load hot air temperature and feed water temperature of a coal-fired boiler according to claim 1 is characterized in that: The steam extraction module comprises a medium-temperature superheater (26) and a bypass superheated steam isolation valve (22). The steam extraction module extracts superheated steam from the outlet of the medium-temperature superheater (26) in the boiler system module.

3. The system for synchronously increasing the low-load hot air temperature and feed water temperature of a coal-fired boiler according to claim 1 is characterized in that: The steam decompression and temperature reduction module comprises: a decompression regulating valve (12), a temperature reduction water isolation valve (13), a temperature reduction water regulating valve (14) and a temperature reducer (15). The steam decompression and temperature reduction module receives the superheated steam extracted by the steam extraction module and performs pressure reduction and temperature reduction processing on the superheated steam.

4. The system for synchronously increasing the low-load hot air temperature and feed water temperature of a coal-fired boiler according to claim 1, characterized in that: The hot air heating module comprises a hot air heat exchanger (21), and a hot air (11) pipe at the outlet of the air preheater and a heated hot air (20) pipe connected thereto. The hot air heating module uses the superheated steam processed by the steam decompression and temperature reduction module to heat the hot air at the outlet of the air preheater module.

5. The system for synchronously increasing the low-load hot air temperature and feed water temperature of a coal-fired boiler according to claim 1 is characterized in that: The No. 1 high-pressure heater module comprises: a No. 1 high-pressure heater (3), a low-temperature feed water (5) inlet pipe, a high-temperature feed water (6) outlet pipe, and an access pipe for superheated steam (16) at the outlet of the hot air heat exchanger. The No. 1 high-pressure heater module receives the superheated steam that has released heat after being processed by the steam pressure reducing and temperature reducing module, and uses this steam as a heat source to heat the low-temperature feed water (5).

6. The system for synchronously increasing the low-load hot air temperature and feed water temperature of a coal-fired boiler according to claim 1, characterized in that: The system control module is used to control the working status of the steam extraction module, steam pressure reduction and temperature reduction module, hot air heating module and No. 1 high-pressure heater module.

7. The system for synchronously increasing the low-load hot air temperature and feed water temperature of a coal-fired boiler according to claim 1, characterized in that: The air preheater module comprises an air preheater (9), a cold air (10) inlet pipe and an air preheater outlet hot air (11) pipe. The air preheater module is used to provide preheated air for the boiler system, and the hot air at its outlet is further heated by the hot air heating module.

8. The system for synchronously increasing the low-load hot air temperature and feed water temperature of a coal-fired boiler according to claim 1, characterized in that: The boiler system module includes a boiler (1) body, an economizer (24), a low-temperature superheater (25), a medium-temperature superheater (26), a high-temperature superheater (27) and a turbine high-pressure cylinder (2). The boiler system module is used to receive hot air heated by the hot air heating module and high-temperature feed water provided by the No. 1 high-pressure heater module for combustion and power generation.

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