A flue gas temperature regulating system for a natural gas boiler

Abstract

The utility model relates to a kind of smoke temperature regulating system suitable for natural gas boiler, belong to industrial boiler field, including low-temperature economizer (7), high-temperature economizer (6), feedwater line (10) and regulating valve, the feedwater line (10) including the feedwater main line and feedwater bypass being uniformly provided with regulating valve, feedwater main line connects the inlet header (12) of low-temperature economizer, feedwater bypass connects the inlet header (14) of high-temperature economizer, the low-temperature economizer (7) is connected high-temperature economizer (6), the outlet header (13) of low-temperature economizer connects the inlet header (14) of high-temperature economizer.The utility model has set up the feedwater shunt system in low-temperature economizer inlet header and high-temperature economizer inlet header, by adjusting low-temperature economizer inlet water quantity, to adjust exhaust gas temperature, effectively avoid low load under tail end stage heating surface low-temperature corrosion, flue gas recirculation pipeline condensate water leads to pipeline corrosion and other problems.

Description

Technical Field

[0001] This utility model relates to the field of industrial boilers, and in particular to a flue gas temperature regulation system suitable for natural gas boilers. Background Technology

[0002] A flue gas temperature control system for natural gas boilers is primarily applied in the natural gas boiler sector. Driven by energy structure transformation and the "dual carbon" goal, natural gas, as a relatively clean fossil fuel, is increasingly widely used in industrial heating, district heating, and process steam applications. As a core heat energy conversion device, the operating efficiency and environmental performance of natural gas boilers directly affect energy consumption costs and environmental emissions levels. However, the flue gas temperature at the boiler's tail end, a key parameter for measuring boiler thermal efficiency and operating status, faces multiple challenges in its rational control, necessitating a more intelligent and precise flue gas temperature control system.

[0003] In actual boiler operation, parameters such as load demand, inlet water temperature, fuel characteristics (pressure), and ambient temperature all change dynamically. Traditional control methods based on a fixed excess air coefficient or simple proportional adjustment are difficult to maintain the optimal flue gas temperature in real time and accurately under varying operating conditions—that is, the temperature point that maximizes thermal efficiency (minimizes flue gas losses) while ensuring safety (avoiding low-temperature corrosion of the final stage air preheater and economizer) and meeting environmental protection requirements. Utility Model Content

[0004] To address the aforementioned technical problems, this utility model provides a flue gas temperature regulation system suitable for natural gas boilers.

[0005] A flue gas temperature regulation system suitable for natural gas boilers includes a low-temperature economizer, a high-temperature economizer, a feedwater pipeline, and regulating valves. The feedwater pipeline includes a main feedwater line and a feedwater bypass line, both equipped with regulating valves. The main feedwater line is connected to the inlet header of the low-temperature economizer, and the feedwater bypass line is connected to the inlet header of the high-temperature economizer. The low-temperature economizer is connected to the high-temperature economizer, and the outlet header of the low-temperature economizer is connected to the inlet header of the high-temperature economizer.

[0006] Furthermore, the electric regulating valve includes a main line electric regulating valve and a bypass electric regulating valve, wherein the main line electric regulating valve is installed on the main water supply line and the bypass electric regulating valve is installed on the water supply bypass.

[0007] Furthermore, the branch outlet of the water supply bypass is located before the main water supply line passes through the regulating valve.

[0008] Furthermore, the outlet header of the high-temperature economizer is connected to the steam drum via a steam drum feedwater pipeline.

[0009] Furthermore, the low-temperature economizer is connected to the outlet flue and the high-temperature economizer, and the high-temperature economizer is connected to the evaporator.

[0010] The beneficial effects of this utility model are as follows: This utility model sets up a feedwater diversion system in the inlet header of the low-temperature economizer and the inlet header of the high-temperature economizer. By adjusting the inlet water flow of the low-temperature economizer, the flue gas temperature can be adjusted. This system can flexibly adjust the flue gas temperature according to load changes, so that the flue gas temperature is kept within the most economical and safe range. It can effectively avoid low-temperature corrosion of the tail-end heating surface under low load and the problem of condensation in the flue gas recirculation pipeline leading to pipeline corrosion. Attached Figure Description

[0011] Figure 1 This is a structural diagram of the present invention.

[0012] Figure 2 This is a structural connection diagram of the application of this utility model to a natural gas boiler.

[0013] Figure descriptions: 1. Burner; 2. Natural gas boiler; 3. Furnace; 4. Superheater; 5. Evaporator; 6. High-temperature economizer; 7. Low-temperature economizer; 8. Steam drum; 9. Bypass electric regulating valve; 10. Feedwater pipeline; 11. Main electric regulating valve; 12. Inlet header of low-temperature economizer; 13. Outlet header of low-temperature economizer; 14. Inlet header of high-temperature economizer; 15. Outlet header of high-temperature economizer; 16. Steam drum feedwater pipeline; 17. Outlet flue. Detailed Implementation

[0014] The technical solutions of the present utility model will be clearly and completely described below with reference to the figures in the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0015] In this embodiment, as Figure 1 As shown, a flue gas temperature control system suitable for a natural gas boiler includes: a low-temperature economizer 7, a high-temperature economizer 6, a feedwater pipeline 10, and regulating valves. The feedwater pipeline 10 includes a main feedwater line and a feedwater bypass, both equipped with regulating valves. The main feedwater line connects to the inlet header 12 of the low-temperature economizer, and the feedwater bypass connects to the inlet header 14 of the high-temperature economizer. The low-temperature economizer 7 is connected to the high-temperature economizer 6, and the outlet header 13 of the low-temperature economizer connects to the inlet header 14 of the high-temperature economizer. The electric regulating valves include a main line electric regulating valve 11 and a bypass electric regulating valve 9. The main line electric regulating valve 11 is located on the main feedwater line, and the bypass electric regulating valve 9 is located on the feedwater bypass. The branch outlet of the feedwater bypass is located before the regulating valves of the main feedwater line. The outlet header 15 of the high-temperature economizer is connected to the steam drum 8 via a steam drum feedwater pipeline 16.

[0016] In this embodiment, the structure applied to the natural gas boiler 2 is as follows: Figure 2 As shown, starting from burner 1, the natural gas boiler 2, superheater 4, evaporator 5, high-temperature economizer 6, low-temperature economizer 7, and outlet flue 17 are connected in sequence; the connections of high-temperature economizer 6, low-temperature economizer 7, and steam drum 8 are as described above and will not be repeated.

[0017] In this embodiment, the flue gas temperature is adjusted by regulating the feedwater flow rate of the low-temperature economizer 7. A feedwater bypass is installed at the inlet of the low-temperature economizer 7 and connected to the inlet pipe of the high-temperature economizer 6. Electric regulating valves are installed on the main line and the bypass line. By adjusting the opening of the regulating valves (during operation, it should be noted that the main line regulating valve should not be fully closed, but should be kept as fully open as possible, and the flow rate is adjusted through the bypass regulating valve), the feedwater flow rate of the low-temperature economizer 7 is adjusted, thereby achieving the effect of regulating the flue gas temperature.

[0018] Low-load operation: When the boiler operates below 50% load, the flue gas temperature will decrease significantly (from approximately 135℃ at full load to below approximately 110℃). Operating at excessively low flue gas temperatures will cause low-temperature corrosion on the final stage heating surfaces. Furthermore, the temperature of the air mixed in the flue gas recirculation pipeline will also decrease, causing the mixed air temperature to fall below the dew point temperature, resulting in condensation and further corrosion of the pipelines, thus compromising the safe and stable operation of the boiler. This system can maintain the flue gas temperature within a safe and economical range under various loads by adjusting the feedwater flow of the low-temperature economizer 7. It can also directly disconnect the low-temperature economizer 7 under extremely low loads to ensure the flue gas temperature.

[0019] This solution achieves the following: 1) Effectively prevents low-temperature corrosion and ensures equipment safety: By adjusting the feedwater flow of the low-temperature economizer 7 (mainly by adjusting the bypass valve to reduce the flow of the low-temperature economizer 7), this system can actively and accurately increase the flue gas temperature, ensuring that it is always higher than the acid dew point temperature under various loads (especially at low loads), completely avoiding low-temperature corrosion of the tail heating surface, and significantly extending the service life of key boiler equipment.

[0020] 2) Eliminate the risk of condensation corrosion in the FGR system: Maintaining a sufficiently high exhaust gas temperature fundamentally ensures the temperature of the recirculated flue gas, so that the temperature after mixing with air is higher than the water dew point, effectively preventing the generation of condensate in the FGR pipeline and the resulting corrosion problems, and ensuring the safe and reliable operation of the FGR system.

[0021] 3) Stable control of flue gas temperature over a wide load range: This system breaks through the limitation of traditional boilers in controlling flue gas temperature under low load. It can dynamically adjust the heat absorption of the low-temperature economizer 7 within a wide operating range from high load to ultra-low load, and stably maintain the flue gas temperature within the preset safe and economical range (e.g., 135-140℃), taking into account both efficiency and safety.

[0022] 4) Extreme protection measures under ultra-low load: Under extreme ultra-low load conditions, if flow regulation alone is insufficient to maintain safe flue gas temperature, this system can "cut off" the low-temperature economizer 7 by completely closing the main regulating valve (at which time the bypass valve is fully open), so that most or all of the feedwater directly enters the high-temperature economizer 6, thereby maximizing the increase of flue gas temperature and providing the last guarantee for the safe and stable operation of the boiler under extreme conditions.

[0023] In the description of the embodiments of this utility model, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0024] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A flue gas temperature control system suitable for natural gas boilers, characterized in that, It includes a low-temperature economizer (7), a high-temperature economizer (6), a water supply pipeline (10), and regulating valves. The water supply pipeline (10) includes a main water supply line and a water supply bypass line, both equipped with regulating valves. The main water supply line is connected to the inlet header (12) of the low-temperature economizer, and the water supply bypass line is connected to the inlet header (14) of the high-temperature economizer. The low-temperature economizer (7) is connected to the high-temperature economizer (6), and the outlet header (13) of the low-temperature economizer is connected to the inlet header (14) of the high-temperature economizer.

2. The flue gas temperature control system for natural gas boilers according to claim 1, characterized in that, The regulating valve includes a main line electric regulating valve (11) and a bypass electric regulating valve (9). The main line electric regulating valve (11) is installed on the main water supply line, and the bypass electric regulating valve (9) is installed on the water supply bypass.

3. The flue gas temperature control system for natural gas boilers according to claim 1, characterized in that, The water supply bypass is located at the branch entrance before the main water supply line passes through the regulating valve.

4. The flue gas temperature control system for natural gas boilers according to claim 1, characterized in that, The outlet header (15) of the high-temperature economizer is connected to the steam drum (8) through the steam drum water supply pipeline (16).

5. A flue gas temperature control system for natural gas boilers according to claim 1, characterized in that, The low-temperature economizer (7) is connected to the outlet flue (17) and the high-temperature economizer (6), and the high-temperature economizer (6) is connected to the evaporator (5).

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