Economizer system of tower boiler and boiler system

Abstract

An economizer system and boiler system for a tower boiler, belonging to the field of industrial machinery, specifically relates to economizer technology in boiler systems. The economizer system includes a secondary economizer system and a primary economizer system, which are connected in series. The secondary economizer system includes a secondary economizer inlet header and a secondary economizer outlet header; the secondary economizer inlet header is a single header, and the secondary economizer outlet header is a double header. This economizer system effectively reduces the alternating stress at the root of the economizer outlet header tube seat during the deep peak-shaving stage of the boiler by designing the secondary economizer outlet header as a double header. The use of a single header for the secondary economizer inlet header avoids the steam resistance problem caused by pressure imbalance between headers in traditional designs. This economizer system is particularly suitable for boiler systems with deep peak-shaving capabilities, and is also applicable to power generation, boiler manufacturing, energy management, and other fields.

Description

Technical Field

[0001] This invention belongs to the field of industrial machinery, specifically relating to the design of economizers in boiler systems, and is particularly suitable for boiler systems with deep peak shaving capabilities. Background Technology

[0002] With the rapid development of new energy power generation, the power system is facing unprecedented challenges. Especially with the increasing proportion of renewable energy sources such as wind and solar power, the peak-shaving capacity of traditional thermal power generating units is particularly important. Deep peak shaving refers to the need for thermal power generating units to quickly adapt to load changes when the grid experiences drastic load fluctuations, ensuring the stable operation of the grid. Due to the volatility and intermittency of renewable energy, the rapid peak-shaving capacity of thermal power generating units directly affects the security and stability of the power grid.

[0003] In coal-fired power generating units, economizers are crucial equipment for recovering waste heat from flue gas and preheating boiler feedwater, widely used to improve boiler efficiency and reduce energy consumption. However, traditional economizer systems present significant problems during deep peak shaving and rapid load regulation. First, due to drastic load fluctuations during peak shaving, flue gas flow and temperature also change dramatically, leading to large temperature and pressure fluctuations in the economizer outlet header. These drastic fluctuations subject the root of the economizer outlet header tube seat to significant alternating stress, which can cause tube seat fatigue or even leakage over long-term operation, affecting the safety and stability of the boiler system. Furthermore, during the hot start-up process after startup or emergency shutdown of a deep peak-shaving boiler, the economizer system is prone to steam resistance. Steam resistance is caused by localized bubble accumulation due to temperature changes in the medium near the economizer's heating surface. These bubbles can obstruct feedwater flow and even cause boiler startup failure. Especially during rapid increases and decreases in boiler load, temperature fluctuations inside the economizer can cause localized bubble formation. These bubbles accumulate over time and may eventually form steam resistance, affecting the normal operation of the boiler.

[0004] Although some existing technologies employ multi-stage economizers or optimize the heat exchange path of economizers in an attempt to address these issues, many shortcomings remain. For example, while staged economizer designs mitigate the impact of temperature fluctuations on the economizer to some extent, the economizer system still struggles to avoid alternating stress problems during rapid boiler peak shaving, especially under rapid load changes, where leakage at the header root remains a significant risk. Furthermore, most existing steam resistance solutions rely on increasing the heat exchange area or improving the heat exchange method, but they do not fundamentally address the source of steam resistance, which remains a serious problem, particularly during hot start-up.

[0005] Therefore, based on current technology, there is still an urgent need for a new economizer design that can effectively solve the problems of alternating stress, steam resistance, and temperature fluctuations faced by boiler systems during deep peak shaving, in order to improve the operational safety and stability of the boiler, especially during load regulation and hot start-up. Summary of the Invention

[0006] To reduce the alternating stress at the root of the economizer outlet header tube seat during peak shaving of the boiler, and to solve the steam resistance problem of the economizer system during hot start-up of a deep peak shaving boiler after startup or emergency shutdown, this invention provides the following solutions:

[0007] An economizer system for a tower boiler, the economizer system comprising a secondary economizer system and a primary economizer system, the secondary economizer system and the primary economizer system being connected in series.

[0008] Furthermore, the secondary economizer system includes a secondary economizer inlet header and a secondary economizer outlet header. The secondary economizer inlet header is located directly above the secondary economizer outlet header. The secondary economizer inlet header is a single header, and the secondary economizer outlet header is a double header, which includes a left outlet header and a right outlet header. The left outlet header and the right outlet header are arranged in a mirror image of the centerline of the secondary economizer inlet header.

[0009] Furthermore, the left and right exit headers have the same width.

[0010] Furthermore, the secondary economizer system also includes a secondary economizer heating surface.

[0011] Furthermore, the primary economizer system includes a primary economizer inlet header, a primary economizer heating surface, and a primary economizer outlet header, which are connected in series.

[0012] Furthermore, the primary economizer outlet header and the secondary economizer inlet header are connected by pipes.

[0013] A tower boiler includes a denitrification system and front and rear vertical shafts at the top of the boiler furnace. The tower boiler also includes an economizer system as described in any one of the present invention, the economizer system being located inside the boiler furnace.

[0014] Furthermore, the width of both the left and right outlet headers of the secondary economizer is half the width of the boiler furnace.

[0015] Furthermore, the heating surface of the secondary economizer is arranged in the front and rear vertical shafts at the top of the boiler furnace.

[0016] Furthermore, the heating surface of the primary economizer is arranged below the catalyst of the denitrification system.

[0017] The present invention has the following beneficial effects:

[0018] (1) The economizer system for a tower boiler proposed in this invention can reduce alternating stress and improve boiler stability. By designing the outlet header of the secondary economizer as a double header (left outlet header and right outlet header), with the width of each header being half the width of the boiler furnace, this design can disperse the fluid flow path, reduce single-point stress concentration, and thus reduce the amplitude of alternating stress. This invention effectively reduces the alternating stress at the root of the economizer outlet header tube seat during the deep peak shaving stage of the boiler. This design can significantly reduce leakage problems caused by alternating stress and improve the long-term stability and safety of the boiler system.

[0019] (2) The economizer system for a tower boiler proposed in this invention can avoid steam resistance problems and ensure smooth hot start-up. The use of a single-header inlet header for the secondary economizer successfully avoids the steam resistance problem caused by pressure imbalance between headers in traditional designs. The single-header design simplifies the fluid flow path and reduces steam resistance caused by pressure fluctuations or uneven flow resistance at the connection points of multiple headers. During the hot start-up process after an emergency shutdown, this design ensures smooth fluid flow within the economizer system, avoids steam resistance, and thus ensures smooth boiler startup, improving the unit's emergency start-up capability.

[0020] (3) The tower boiler proposed in this invention can reduce bubble accumulation. The heating surface of the secondary economizer is arranged in the vertical shaft at the top of the boiler furnace and exchanges heat with the flue gas in a counter-current manner. The counter-current heat exchange method can maximize the heat exchange temperature difference and reduce local overheating, thereby reducing the generation and accumulation of bubbles. It effectively reduces the bubble accumulation caused by temperature difference changes during the deep peak shaving stage of the boiler. Through this optimized design, the economizer system can operate stably during high load fluctuations and deep peak shaving, improve heat exchange efficiency, and reduce steam resistance problems caused by bubbles.

[0021] (4) The tower boiler proposed in this invention can improve the boiler's adjustment flexibility and meet denitrification requirements. By rationally arranging the primary and secondary economizer systems and connecting them through pipelines, the flow rate of the medium flowing through the economizer system can be precisely adjusted, thereby optimizing the flue gas temperature of the boiler's denitrification system and meeting the catalyst input requirements. Through flow rate adjustment, the heat exchange of the economizer system can be controlled, thereby adjusting the flue gas temperature and ensuring that it is within the optimal operating temperature range of the denitrification catalyst. During the deep peak shaving phase of the unit, the system can adjust the flow rate as needed, effectively balancing the boiler's hot start-up and denitrification requirements, improving the boiler's adjustment flexibility and environmental performance.

[0022] This invention is widely applicable to various fields such as power generation, boiler manufacturing, energy management, and environmental protection technology, and has significant application value, especially in deep peak-shaving power systems. Attached Figure Description

[0023] Figure 1 The embodiment describes a tower boiler; reference numerals: 1 for primary economizer inlet header, 2 for primary economizer heating surface, 3 for primary economizer outlet header, 4 for secondary economizer inlet header, 5 for secondary economizer heating surface, and 6 for secondary economizer outlet header, wherein the secondary economizer outlet header 6 includes a secondary economizer outlet left header 6L and a secondary economizer outlet right header 6R.

[0024] Figure 2 The economizer system of a tower boiler described in the embodiment is indicated by the following reference numerals: primary economizer inlet pressure measuring point P1, secondary economizer outlet pressure measuring point P2, secondary economizer inlet pressure measuring point P3, primary economizer inlet temperature measuring point T1, primary economizer heating surface outlet wall temperature measuring point T2, secondary economizer outlet temperature measuring point T3, secondary economizer heating surface outlet wall temperature measuring point T4, and secondary economizer inlet temperature measuring point T5. Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Implementation Method 1

[0027] Combined with appendix Figure 2 This embodiment describes an economizer system for a tower boiler, comprising a secondary economizer system and a primary economizer system, wherein the secondary economizer system and the primary economizer system are connected in series.

[0028] This embodiment connects the secondary economizer system and the primary economizer system in series, enabling the two economizers to work together, optimizing heat exchange efficiency, and providing a basis for subsequent flow regulation and temperature control, thereby improving the overall performance and operational stability of the boiler system.

[0029] Implementation Method 2

[0030] This embodiment is a further explanation of embodiment one:

[0031] Furthermore, the secondary economizer system includes a secondary economizer inlet header 4 and a secondary economizer outlet header 6. The secondary economizer inlet header 4 is located directly above the secondary economizer outlet header 6. The secondary economizer inlet header 4 is a single header, and the secondary economizer outlet header 6 is a double header. The double header includes a left outlet header 6L and a right outlet header 6R. The left outlet header 6L and the right outlet header 6R are arranged in a mirror image of the centerline of the secondary economizer inlet header 4.

[0032] This embodiment ensures uniform fluid distribution within the dual headers by making the left and right outlet headers the same width, avoiding uneven flow caused by differences in header width, and further improving system stability and heat exchange efficiency.

[0033] Implementation Method 3

[0034] This embodiment is a further explanation of embodiment two:

[0035] Furthermore, the left outlet header 6L and the right outlet header 6R have the same width.

[0036] This embodiment enhances the heat exchange capacity of the secondary economizer by setting up a secondary economizer heating surface, optimizes the heat transfer efficiency between flue gas and working fluid, and thus improves the overall thermal efficiency of the boiler.

[0037] Implementation Method 4

[0038] This embodiment is a further explanation of embodiment two:

[0039] Furthermore, the secondary economizer system also includes a secondary economizer heating surface 5.

[0040] This embodiment, by setting up a primary economizer system, including a primary economizer inlet header, a primary economizer heating surface, and a primary economizer outlet header, can realize the independent operation and heat exchange function of the primary economizer, provide pre-treatment working fluid for the secondary economizer, and optimize the overall heat exchange effect.

[0041] Implementation Method 5

[0042] This embodiment is a further explanation of embodiment one:

[0043] Furthermore, the primary economizer system includes a primary economizer inlet header 1, a primary economizer heating surface 2, and a primary economizer outlet header 3, which are connected in series.

[0044] This embodiment connects the primary economizer outlet header and the secondary economizer inlet header with a pipeline, enabling seamless connection between the two economizers, ensuring the continuity and stability of the working fluid flow, and providing convenience for flow regulation and temperature control.

[0045] Implementation Method Six

[0046] This embodiment is a further explanation of embodiment five:

[0047] Furthermore, the primary economizer outlet header 3 and the secondary economizer inlet header 4 are connected by pipes.

[0048] This embodiment connects the primary economizer outlet header and the secondary economizer inlet header with a pipeline, enabling seamless connection between the two economizers, ensuring the continuity and stability of the working fluid flow, and providing convenience for flow regulation and temperature control.

[0049] Implementation Method Seven

[0050] Combined with appendix Figure 1 This embodiment describes a tower boiler, which includes a denitrification system and front and rear vertical shafts at the top of the boiler furnace. The tower boiler also includes an economizer system as described in any one of embodiments one to six, and the economizer system is located inside the boiler furnace.

[0051] This embodiment integrates the economizer system into the tower boiler and places it inside the boiler furnace. This allows for full utilization of the furnace space, optimization of the heat exchange layout, and simultaneous satisfaction of the temperature requirements of the denitrification system, thereby improving the boiler's environmental performance and operating efficiency.

[0052] Implementation Method Eight

[0053] This embodiment is a further explanation of embodiment seven:

[0054] Furthermore, the widths of the left outlet header 6L and the right outlet header 6R of the secondary economizer are both half the width of the boiler furnace.

[0055] This embodiment designs the width of the left and right outlet headers of the secondary economizer to be half the width of the boiler furnace, which can effectively reduce stress concentration in the headers and reduce the impact of alternating stress on the tube seat, thereby improving the stability and safety of the boiler during the deep peak shaving stage.

[0056] Implementation Method Nine

[0057] This embodiment is a further explanation of embodiment seven:

[0058] Furthermore, the heating surface 5 of the secondary economizer is arranged in the front and rear vertical shafts at the top of the boiler furnace.

[0059] This embodiment arranges the heating surface of the secondary economizer in the front and rear vertical shafts at the top of the boiler furnace, which can make full use of the high-temperature flue gas area, optimize the countercurrent heat exchange effect, reduce bubble accumulation, and improve heat exchange efficiency and system operation stability.

[0060] Implementation Method Ten

[0061] This embodiment is a further explanation of embodiment seven:

[0062] Furthermore, the heating surface 2 of the primary economizer is arranged below the catalyst of the denitrification system.

[0063] This embodiment arranges the heating surface of the primary economizer below the catalyst in the denitrification system, which can precisely regulate the flue gas temperature and ensure that the catalyst operates within the optimal temperature range, thereby improving the denitrification efficiency and meeting environmental emission requirements.

[0064] Implementation Method Eleven

[0065] This embodiment combines the technical solutions described in the foregoing embodiments, and further verifies and explains the technical effects of the present invention through specific examples in light of actual conditions.

[0066] The secondary economizer system consists of the secondary economizer inlet header (first header), the secondary economizer heating surface, and the secondary economizer outlet header (double header, divided into left and right outlet headers). The secondary economizer heating surface is arranged in the front and rear vertical shafts at the top of the boiler furnace, and exchanges heat with the flue gas in a counter-current manner.

[0067] Feedwater flows sequentially through the primary economizer inlet header, primary economizer heating surface, primary economizer outlet header, secondary economizer inlet header, secondary economizer heating surface, and secondary economizer left / right outlet headers before converging and flowing into the boiler water-cooled wall system. Simultaneously, the flow rate of the medium flowing through the economizer system can be regulated by adjusting the flow rate of the medium flowing through the feedwater bypass. During deep peak shaving, the boiler denitrification inlet flue gas temperature can be adjusted to meet the catalyst charging requirements by regulating the flow rate of the medium flowing through the economizer system.

[0068] During the deep peak shaving phase of the unit, monitor and ensure that the outlet wall temperature of the secondary economizer heating surface is more than 10°C below the saturation temperature to prevent the bubbles generated in the local area of ​​the economizer from eventually deteriorating into steam resistance problems during the deep peak shaving phase of the unit.

[0069] During the hot start-up and water filling stage of the unit, monitor and control the pressure deviation on the left and right sides of the inlet of the secondary economizer to be no more than 0.05MPa to avoid steam resistance problems in the boiler economizer system.

[0070] In solving the design problems of the economizer system for deep peak-shaving tower boilers, this invention overcomes many technical difficulties. After multiple experiments and technical adjustments, it finally achieves effective solutions to a series of key problems such as temperature fluctuations, steam resistance, and alternating stress during the deep peak-shaving process of the boiler.

[0071] In the early stages of research and development, facing the alternating stress problem in the economizer system during deep peak shaving of the boiler, the R&D team tried various header design solutions, including increasing the header thickness and adjusting the pipeline layout. However, these solutions failed to effectively alleviate the alternating stress and instead increased the boiler's size and cost. In particular, when adjusting the header design, despite adopting a reinforced structure, fatigue damage at the tube root was still not effectively prevented, leading to leakage and operational instability.

[0072] Through repeated experiments and theoretical analysis, the inventors discovered that the alternating stress at the economizer outlet header of the boiler is mainly caused by temperature fluctuations due to header width and boiler load changes. Therefore, the invention team proposed a dual-header design (left and right outlet headers), with each header's width being half the width of the boiler furnace. This innovative design effectively disperses the stress at the economizer outlet header during deep peak shaving, significantly reducing alternating stress. Through this improvement, the boiler system can operate stably under high-frequency peak shaving and load fluctuations without leakage problems, solving a long-standing technical bottleneck in this field.

[0073] In solving the steam resistance problem, the inventors also experienced many failed attempts. In the initial design, they tried using multiple header configurations to optimize the startup process, but due to pressure imbalance, this actually made steam resistance more likely during hot startup. Faced with this technical challenge, the invention team conducted repeated research and calculations, and finally determined to use a single header configuration for the secondary economizer inlet header. This design simplified the system structure, ensured smooth fluid flow in the boiler economizer system during hot startup, avoided steam resistance, and successfully guaranteed the unit's rapid startup.

[0074] Furthermore, the research revealed that when the secondary economizer's heating surface is positioned within the vertical shaft at the top of the boiler furnace, the flue gas flow pattern can easily lead to localized bubble formation, resulting in steam resistance. By employing counter-current heat exchange, the research team successfully prevented bubble accumulation within the heating surface. Although the initial counter-current design failed to achieve the desired effect due to boiler system flow fluctuations, through multiple optimizations and experiments of the boiler airflow path, a more ideal heat exchange effect was ultimately achieved, avoiding the bubble problem caused by excessive temperature differences during deep peak shaving.

[0075] These technological breakthroughs were achieved through continuous experimentation and optimization. Each failure contributed valuable experience to the final success, and the invention team devoted a great deal of creative labor. Through this innovative design, the present invention effectively improves the stability, reliability, and efficiency of boiler deep peak shaving, solves the technical bottlenecks in deep peak shaving that existing technologies cannot overcome, and greatly enhances the boiler system's adjustment capabilities during deep peak shaving and rapid load changes.

[0076] In summary, this invention not only overcomes many technical challenges, but also, through innovative design and multiple experimental verifications, successfully solves a series of problems such as alternating stress and steam resistance in the economizer system during deep peak shaving, demonstrating the tremendous creative labor that the inventors have devoted to this patent.

[0077] The above detailed description of the technical solution provided by the present invention is intended to highlight the advantages and benefits of the technical solution provided by the present invention. However, the above detailed embodiments are not intended to limit the present invention. Any reasonable modifications and improvements to the present invention, combinations of embodiments, and equivalent substitutions based on the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0078] Those skilled in the art will understand that the above description is merely a preferred embodiment of the present invention, and the features described in the various embodiments and / or claims of this disclosure can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in this disclosure. This is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0079] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if these modifications and modifications of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include these modifications and modifications.

Claims

1. An economizer system for a tower boiler, characterized in that, The economizer system includes a secondary economizer system and a primary economizer system, which are connected in series. The secondary economizer system includes a secondary economizer inlet header (4) and a secondary economizer outlet header (6). The secondary economizer inlet header (4) is located directly above the secondary economizer outlet header (6). The secondary economizer inlet header (4) is a single header, and the secondary economizer outlet header (6) is a double header. The double header includes a left outlet header (6L) and a right outlet header (6R). The left outlet header (6L) and the right outlet header (6R) are arranged in a mirror image of the centerline of the secondary economizer inlet header (4).

2. The economizer system according to claim 1, characterized in that, The left exit header (6L) and the right exit header (6R) have the same width.

3. The economizer system according to claim 1, characterized in that, The secondary economizer system also includes a secondary economizer heating surface (5).

4. The economizer system according to claim 1, characterized in that, The primary economizer system includes a primary economizer inlet header (1), a primary economizer heating surface (2), and a primary economizer outlet header (3), which are connected in series.

5. The economizer system according to claim 4, characterized in that, The primary economizer outlet header (3) and the secondary economizer inlet header (4) are connected by a pipeline.

6. A tower boiler, comprising a denitrification system and front and rear vertical shafts at the uppermost part of the boiler furnace, characterized in that, The tower boiler also includes the economizer system according to any one of claims 1-5, wherein the economizer system is located inside the boiler furnace.

7. The tower boiler according to claim 6, characterized in that, The width of the left outlet header (6L) and right outlet header (6R) of the secondary economizer is half the width of the boiler furnace.

8. The tower boiler according to claim 6, characterized in that, The secondary economizer heating surface (5) is arranged in the front and rear vertical shafts at the top of the boiler furnace.

9. The tower boiler according to claim 6, characterized in that, The primary economizer heating surface (2) is arranged below the catalyst of the denitrification system.

Images