System for increasing boiler feed water temperature

Abstract

The utility model relates to the technical field of energy conservation of coal-fired boilers, in particular to a system for increasing the feed water temperature of a boiler, which adopts a modular design, ensures the effective increase of the feed water temperature, and further enhances the operation efficiency and the overall performance of the boiler. According to the utility model, the temperature of feed water is increased, so that the boiler can operate more efficiently, the SCR full-load denitration is facilitated, and the potential and advantages in the aspects of improving the energy efficiency and protecting the environment are shown. The temperature of feed water entering the boiler is increased, then the temperature of flue gas at an SCR inlet is increased, and full-load denitration and deep peak regulation of a unit are facilitated.

Description

Technical Field

[0001] The utility model relates to the technical field of energy-saving of coal-fired boilers, in particular to a system for increasing the feed water temperature of a boiler. Background Art

[0002] With the rapid development of economy, the demand for energy continues to grow. As an important cornerstone to support economic development, the thermal power industry has seen its installed capacity and power generation increase year by year. The power industry has become the world's number one in terms of total installed capacity. At the same time, my country is also constantly optimizing its energy structure. Although the proportion of thermal power installed capacity has declined, thermal power generation still occupies a dominant position. However, this development has also brought about environmental problems, especially the large amount of carbon dioxide emissions caused by coal burning, making carbon emission reduction an important issue facing the thermal power industry.

[0003] In response to the challenge of carbon emission reduction, the power industry has promoted the technological upgrading of the thermal power industry, including strict control of emissions from coal-fired units. According to relevant policy requirements, coal-fired units must ensure that emission standards are met stably at full load and all time. In actual operation, in order to meet emission standards, most large coal-fired units have upgraded their denitrification technology, among which selective catalytic reduction (SCR) is widely used. This method requires the inlet flue gas temperature to reach above 300°C to ensure the normal operation of the SCR catalyst.

[0004] Although SCR technology has reduced nitrogen oxide emissions to a certain extent, it also faces some technical difficulties. When the SCR inlet flue gas temperature is lower than 300°C, the SCR system cannot operate normally, which will lead to ultra-low NOx emission concentration, catalyst deactivation, increased ammonia slip and other problems. To solve this problem, wide-load denitrification technology must be adopted. However, the existing wide-load denitrification technologies, such as economizer water side bypass and flue gas bypass, although the technical means are diverse, generally have pain points such as limited layout space, limited temperature increase effect, high investment cost and complex system. These limitations make coal-fired units face challenges in achieving flexibility transformation and meeting environmental emission requirements, and new technical reserves are urgently needed to break through these limitations. Utility Model Content

[0005] The utility model provides a system for increasing the boiler feed water temperature to solve the problems of the existing wide-load denitrification technologies, such as economizer water side bypass, flue gas bypass, etc., although the technical means are diverse, there are generally problems such as limited layout space, limited temperature increase effect, high investment cost and complex system.

[0006] The utility model provides a system for increasing the temperature of boiler feed water, comprising:

[0007] Steam extraction module: The steam extraction module extracts superheated steam from the outlet of the medium-temperature superheater in the boiler and sends it to the pressure reduction and temperature reduction module as bypass superheated steam.

[0008] Pressure reducing and temperature reducing module: The pressure reducing regulating valve in the pressure reducing and temperature reducing module reduces the pressure of the bypass superheated steam to obtain the reduced pressure bypass superheated steam, and the desuperheater uses the temperature reducing water to reduce the temperature of the reduced pressure bypass superheated steam to obtain the reduced temperature and pressure reduced superheated steam;

[0009] Steam isolation module: The steam isolation module controls the isolation of a first stage of extraction steam through a first stage extraction steam isolation valve. When the system is running, the first stage of extraction steam is no longer extracted from the high-pressure cylinder of the steam turbine;

[0010] Feedwater heating module: The No. 1 high-pressure heater in the feedwater heating module uses the superheated steam after temperature and pressure reduction to heat the low-temperature feedwater, turning the low-temperature feedwater into high-temperature feedwater;

[0011] Feed water delivery module: The feed water delivery module delivers the heated high-temperature feed water to the economizer in the boiler.

[0012] Furthermore, the boiler is set as the end point of the feed water delivery module, and the boiler is also set as the starting point of the feed water heating module. The high-temperature feed water is finally sent to the economizer in the boiler, and the boiler is used to generate main steam;

[0013] The No. 1 high-pressure heater uses bypass superheated steam or desuperheated and reduced-pressure superheated steam to heat low-temperature feed water, turning it into high-temperature feed water;

[0014] The economizer is set as the end point of the water delivery module, and the high-temperature feed water is sent to the economizer for heating.

[0015] Furthermore, a low-temperature superheater, a medium-temperature superheater and a high-temperature superheater are installed inside the boiler, and the low-temperature superheater, the medium-temperature superheater and the high-temperature superheater are used for heating inside the boiler.

[0016] Furthermore, the pressure reducing and cooling module includes a desuperheater, a bypass superheated steam isolation valve, a pressure reducing regulating valve and a desuperheating water isolation valve. The bypass superheated steam isolation valve, the pressure reducing regulating valve and the desuperheating water isolation valve are used to control and adjust the pressure and temperature of the superheated steam. The desuperheater is used to cool the superheated steam.

[0017] The beneficial effects produced by the utility model are as follows:

[0018] Increase feed water temperature: By utilizing superheated steam in the boiler to increase the feed water temperature, this helps the boiler to operate more efficiently and also helps SCR denitrification at full load, especially under low load conditions.

[0019] System simplification: Compared with the traditional wide-load denitrification technology, the system of the utility model is simpler and does not require complex layout space, thereby reducing the difficulty of installation and maintenance.

[0020] Cost reduction: Due to the simplification of the system, not only the initial investment cost is reduced, but also the operation and maintenance costs are reduced.

[0021] Flexibility and adaptability: The system can adapt to different operating conditions, especially when the unit is performing deep peak regulation or full-load denitrification, showing its superiority and flexibility.

[0022] Protect the environment: By increasing the flue gas temperature at the SCR inlet, it helps to reduce nitrogen oxide emissions more effectively, resulting in less impact on the environment.

[0023] Improved energy efficiency: By recovering and reusing the heat from superheated steam, the overall system energy efficiency is improved.

[0024] Technological innovation: This utility model provides an innovative solution, overcomes the limitations of existing technologies, and provides new ideas for promoting the development of related industries.

[0025] In summary, the utility model not only improves the boiler feed water temperature, but also contributes to environmental protection, improves energy efficiency, and reduces investment and operating costs, and has significant economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 A schematic diagram of a system for increasing boiler feed water temperature provided by the utility model.

[0028] 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. Bypass superheated steam; 10. Bypass superheated steam after pressure reduction; 11. Bypass superheated steam isolation valve; 12. Pressure reducing regulating valve; 13. Desuperheating water isolation valve; 14. Desuperheating water regulating valve; 15. Desuperheater; 16. Desuperheated and reduced-pressure superheated steam; 17. Desuperheating water; 18. Economizer; 19. Low-temperature superheater; 20. Medium-temperature superheater; 21. High-temperature superheater. DETAILED DESCRIPTION

[0029] See also Figure 1 The present invention provides a system for increasing boiler feed water temperature, comprising:

[0030] Steam extraction module: The steam extraction module extracts superheated steam from the outlet of the medium-temperature superheater 20 in the boiler 1 and sends it to the pressure reduction and temperature reduction module as bypass superheated steam 9

[0031] Decompression and temperature reduction module: the decompression regulating valve 12 in the decompression and temperature reduction module decompresses the bypass superheated steam 9 to obtain decompressed bypass superheated steam 10, and the desuperheater 15 uses decompression water 17 to decompress the decompressed bypass superheated steam 10 to obtain decompressed and reduced-pressure superheated steam 16;

[0032] Steam isolation module: The steam isolation module controls the isolation of a first stage of extraction steam 8 through a first stage extraction steam isolation valve 4. When the system is running, a first stage of extraction steam 8 is no longer extracted from the high-pressure cylinder 2 of the steam turbine;

[0033] Feedwater heating module: The No. 1 high-pressure heater 3 in the feedwater heating module uses the superheated steam 16 after temperature reduction and pressure reduction to heat the low-temperature feedwater 5, so that the low-temperature feedwater 5 becomes high-temperature feedwater 6;

[0034] Feed water delivery module: The feed water delivery module delivers the heated high-temperature feed water 6 to the economizer 18 in the boiler 1 .

[0035] Specifically, boiler 1 is set as the end point of the feed water delivery module. Boiler 1 is also set as the starting point of the feed water heating module. The high-temperature feed water is finally sent to the economizer in boiler 1. Boiler 1 is used to generate main steam.

[0036] The No. 1 high-pressure heater 3 utilizes the bypass superheated steam 9 or the desuperheated and reduced-pressure superheated steam 16 to heat the low-temperature feed water to make it high-temperature feed water 6;

[0037] The economizer 18 is set as the end point of the water delivery module, and the high-temperature feed water 6 is sent to the economizer 18 for heating.

[0038] Specifically, a low-temperature superheater 19 , a medium-temperature superheater 20 , and a high-temperature superheater 21 are installed inside the boiler 1 , and the low-temperature superheater 19 , the medium-temperature superheater 20 , and the high-temperature superheater 21 are used for heating inside the boiler.

[0039] Specifically, the pressure reducing and cooling module includes a cooler 15, a bypass superheated steam isolation valve 11, a pressure reducing regulating valve 12 and a cooling water isolation valve 14. The bypass superheated steam isolation valve 11, the pressure reducing regulating valve 12 and the cooling water isolation valve 14 are used to control and adjust the pressure and temperature of the superheated steam. The cooler 15 is used to cool the superheated steam.

[0040] The utility model solves the existing wide load denitrification technology, such as economizer water side bypass, flue gas bypass, etc. Although the technical means are diverse, there are generally problems such as limited layout space, limited temperature increase effect, high investment cost and complex system. The specific technical solution is as follows:

[0041] The utility model provides a system for increasing the boiler feed water temperature, which solves the technical pain points in the existing wide-load denitration technology by combining various devices in the system for increasing the boiler feed water temperature into a modular design.

[0042] Steam extraction module: This module extracts superheated steam from the outlet of the medium-temperature superheater 20 in the boiler 1. This method makes full use of the existing heat energy inside the boiler, not only saving space but also improving energy efficiency. The extracted superheated steam is sent to the next module as bypass superheated steam.

[0043] Decompression and temperature reduction module: This module includes a decompression regulating valve 12 and a desuperheater 15. The decompression regulating valve 12 decompresses the bypass superheated steam to obtain decompressed bypass superheated steam. Then, the desuperheater 15 uses decompression water 17 to decompress the decompressed steam to obtain decompressed and decompressed superheated steam. This process ensures that the temperature and pressure of the steam can meet the needs of the next module, while ensuring the safety and stability of the system.

[0044] Steam isolation module: This module controls the isolation of a first stage of extraction steam 8 through a first stage extraction steam isolation valve 4. When the system of the utility model is in operation, a first stage of extraction steam 8 is no longer extracted from the high-pressure cylinder 2 of the steam turbine, thereby simplifying the structure of the system, reducing investment costs and operational complexity.

[0045] Feedwater heating module: The No. 1 high-pressure heater 3 in this module uses the superheated steam after temperature reduction and pressure reduction to heat the low-temperature feedwater 5 to turn it into high-temperature feedwater 6. This method not only increases the feedwater temperature, but also facilitates the subsequent denitrification treatment.

[0046] Feed water delivery module: This module delivers the heated high-temperature feed water 6 to the economizer 18 in the boiler 1. By increasing the feed water temperature, the utility model helps to improve the boiler efficiency and denitration effect.

[0047] In summary, the utility model solves the problems existing in the existing wide-load denitrification technology through modular design, including limited layout space, limited temperature increase effect, high investment cost and complex system, etc. The utility model not only improves energy utilization efficiency, but also reduces investment and operation costs, and has significant economic and social benefits.

[0048] The above description is only the preferred embodiment of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A system for increasing boiler feed water temperature, characterized in that: include: Steam extraction module: The steam extraction module extracts superheated steam from the outlet of the medium-temperature superheater (20) in the boiler (1) and sends it to the pressure reduction and temperature reduction module as bypass superheated steam (9); Decompression and temperature reduction module: the decompression regulating valve (12) in the decompression and temperature reduction module performs a decompression treatment on the bypass superheated steam (9) to obtain decompressed bypass superheated steam (10), and the desuperheater (15) uses decompression water (17) to perform a temperature reduction treatment on the decompressed bypass superheated steam (10) to obtain decompressed and decompressed superheated steam (16); Steam isolation module: The steam isolation module controls the isolation of a first stage of extraction steam (8) through a first stage of extraction steam isolation valve (4), and when the system is running, a first stage of extraction steam (8) is no longer extracted from the high-pressure cylinder (2) of the steam turbine; Feedwater heating module: The No. 1 high-pressure heater (3) in the feedwater heating module uses the superheated steam (16) after temperature reduction and pressure reduction to heat the low-temperature feedwater (5), so that the low-temperature feedwater (5) is converted into high-temperature feedwater (6); Feed water delivery module: The feed water delivery module delivers the heated high-temperature feed water (6) to the economizer (18) in the boiler (1).

2. The system for increasing boiler feed water temperature according to claim 1, characterized in that: The boiler (1) is configured as the end point of the feed water delivery module. The boiler (1) is also configured as the start point of the feed water heating module. The high-temperature feed water is finally delivered to the economizer in the boiler (1). The boiler (1) is used to generate main steam. The first high-pressure heater (3) utilizes the bypass superheated steam (9) or the desuperheated and reduced-pressure superheated steam (16) to heat the low-temperature feed water to make it high-temperature feed water (6); The economizer (18) is arranged as the end point of the water delivery module, and the high-temperature feed water (6) is delivered to the economizer (18) for heating.

3. The system for increasing boiler feed water temperature according to claim 1, characterized in that: A low-temperature superheater (19), a medium-temperature superheater (20) and a high-temperature superheater (21) are installed inside the boiler (1). The low-temperature superheater (19), the medium-temperature superheater (20) and the high-temperature superheater (21) are used for heating the inside of the boiler.

4. The system for increasing boiler feed water temperature according to claim 1, characterized in that: The pressure reducing and temperature reducing module comprises a desuperheater (15), a bypass superheated steam isolation valve (11), a pressure reducing regulating valve (12) and a desuperheating water isolation valve (14). The bypass superheated steam isolation valve (11), the pressure reducing regulating valve (12) and the desuperheating water isolation valve (14) are used to control and adjust the pressure and temperature of the superheated steam. The desuperheater (15) is used to reduce the temperature of the superheated steam.

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