Economizer system of tower type boiler and boiler system

Abstract

The invention discloses an economizer system of a tower-type boiler and a boiler system, belongs to the field of industrial machinery, and particularly relates to an economizer technology in the boiler system. The economizer system comprises a second-stage economizer system and a first-stage economizer system, and the second-stage economizer system and the first-stage economizer system are connected in series. The secondary economizer system comprises a secondary economizer inlet header and a secondary economizer outlet header, the secondary economizer inlet header is a header, and the secondary economizer outlet header is a double-header. According to the economizer system, the secondary economizer outlet header is designed into a double-header form, so that the alternating stress at the root of the economizer outlet header tube seat at the deep peak regulation stage of the boiler is effectively reduced. The secondary economizer inlet header adopting the one-header form can avoid the problem of steam resistance caused by unbalanced pressure between headers in the traditional design. The economizer system is particularly suitable for a deep peak regulation boiler system, and is further suitable for the fields of electric power production, boiler manufacturing, energy management and the like.

Description

Technical Field

[0001] The present invention belongs to the field of industrial machinery, and specifically relates to the design of an economizer in a boiler system, and is particularly suitable for a boiler system with deep peak regulation. Background Art

[0002] With the rapid development of renewable energy power generation, the power system is facing unprecedented challenges. Especially in the context of the increasing proportion of renewable energy such as wind power and solar power, the peak-shaving capability of traditional thermal power generating units is particularly important. Deep peak-shaving means that when the load of the power grid fluctuates sharply, the thermal power generating units need to quickly adapt to the load changes to ensure the stable operation of the power grid. Due to the volatility and intermittency of renewable energy, the rapid peak-shaving capability of thermal power generating units directly affects the safety and stability of the power grid.

[0003] In coal-fired power generation units, economizers are important equipment for recovering flue gas waste heat and preheating boiler feed water. They are widely used to improve boiler efficiency and reduce energy consumption. However, traditional economizer systems have significant problems in deep peak regulation and rapid load regulation. First, due to the dramatic load fluctuations of the boiler during peak regulation, the flue gas flow and temperature will also change dramatically, resulting in large fluctuations in the temperature and pressure of the economizer outlet header. This drastic fluctuation causes the root of the boiler economizer outlet header pipe seat to bear a large amount of alternating stress. Long-term operation will cause fatigue or even leakage of the pipe seat, thus affecting the safety and stability of the boiler system. In addition, during the hot start-up of deep peak-shaving boilers after startup or emergency shutdown, the economizer system is prone to steam resistance problems. Steam resistance is the accumulation of local bubbles caused by changes in the temperature of the medium near the heating surface of the economizer. These bubbles will hinder the flow of feed water and even cause boiler startup failure. Especially during the rapid rise and fall of boiler load, the temperature fluctuation inside the economizer will cause bubbles to form in local areas. These bubbles accumulate over time and may eventually form steam resistance, affecting the normal operation of the boiler.

[0004] Although some existing technologies have adopted multi-stage economizers or optimized the heat exchange path of economizers to try to solve these problems, there are still many shortcomings. For example, the graded economizer design has improved the impact of temperature fluctuations on the economizer to a certain extent, but during the rapid peak regulation of the boiler, the economizer system still cannot avoid the occurrence of alternating stress problems, especially when the unit load changes rapidly, the root of the header is still prone to leakage. In addition, most of the existing steam resistance solutions rely on increasing the heat exchange area or improving the heat exchange method, but have not fundamentally solved the source of steam resistance, especially during hot startup, the steam resistance problem is still serious.

[0005] Therefore, based on the current technology, a new economizer design is still urgently needed to effectively solve the problems of alternating stress, steam resistance and temperature fluctuation faced by the boiler system during the deep peak regulation stage, so as to improve the operation safety and stability of the boiler, especially during load regulation and hot start-up. Summary of the invention

[0006] In order to reduce the alternating stress on the root of the economizer outlet header during the peak load regulation process of the boiler, and solve the steam resistance problem of the economizer system during the hot start-up process of the deep peak load regulation boiler after startup or emergency shutdown, the present invention provides the following solutions:

[0007] A coal economizer system for a tower boiler, the coal economizer system comprising a secondary coal economizer system and a primary coal economizer system, the secondary coal economizer system and the primary coal 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, the secondary economizer outlet header is a double header, the double header 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 with the center line of the secondary economizer inlet header.

[0009] Furthermore, the left outlet header and the right outlet header 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, and the primary economizer inlet header, the primary economizer heating surface and the primary economizer outlet header are connected in series.

[0012] Furthermore, the first-stage economizer outlet header and the second-stage economizer inlet header are connected by a pipeline.

[0013] A tower boiler comprises a denitration system and front and rear vertical shafts at the uppermost part of a boiler furnace. The tower boiler also comprises an economizer system as described in any one of the present invention, and the economizer system is located in the boiler furnace.

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

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

[0016] Furthermore, the heating surface of the first-stage economizer is arranged below the catalyst of the denitration system.

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

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

[0019] (2) The economizer system of a tower boiler proposed in the present invention can avoid the problem of steam resistance and ensure smooth hot start-up. The use of a two-stage economizer inlet header in the form of a header successfully avoids the steam resistance problem caused by pressure imbalance between headers in traditional designs. The single header design can simplify the fluid flow path and reduce the steam resistance phenomenon caused by pressure fluctuations or uneven flow resistance at the connection of multiple headers. During the hot start-up process after an emergency shutdown, this design ensures smooth fluid flow in the economizer system and avoids the generation of steam resistance, thereby ensuring that the boiler can be started smoothly and improving the emergency start-up capability of the unit.

[0020] (3) The tower boiler proposed in the present 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 adopts a countercurrent heat exchange method with the flue gas. The countercurrent heat exchange method can maximize the heat exchange temperature difference, reduce local overheating, and thus reduce the generation and accumulation of bubbles. It effectively reduces the bubble accumulation caused by temperature difference changes during the deep peak regulation stage of the boiler. Through this optimized design, the economizer system can operate stably during high load fluctuations and deep peak regulation, improve the heat exchange efficiency, and reduce the steam resistance problem caused by bubbles.

[0021] (4) The tower boiler proposed in the present invention can improve the flexibility of boiler regulation and meet the denitrification requirements. By rationally arranging the primary and secondary economizer systems and connecting them through pipelines, the medium flow rate flowing through the economizer system can be accurately adjusted, thereby optimizing the flue gas temperature of the boiler denitrification system and meeting the catalyst input requirements. Through flow regulation, the heat exchange amount of the economizer system can be controlled, and then the flue gas temperature can be adjusted to ensure that it is within the optimal operating temperature range of the denitrification catalyst. During the deep peak regulation stage of the unit, the system can adjust the flow rate as needed, effectively balance the hot start-up of the boiler and the denitrification requirements, and improve the flexibility of boiler regulation and environmental protection performance.

[0022] The present invention is widely applicable to many fields such as power production, boiler manufacturing, energy management and environmental protection technology, and has important application value in deep peak-shaving power systems in particular. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a tower boiler described in the implementation manner; the figure numerals: first-level economizer inlet header 1, first-level economizer heating surface 2, first-level economizer outlet header 3, second-level economizer inlet header 4, second-level economizer heating surface 5, second-level economizer outlet header 6, wherein the second-level economizer outlet header 6 includes a second-level economizer outlet left header 6L and a second-level economizer outlet right header 6R.

[0024] Figure 2 It is an economizer system of a tower boiler described in the implementation manner, and the figure numerals are: first-level economizer inlet pressure measuring point P1, second-level economizer outlet pressure measuring point P2, second-level economizer inlet pressure measuring point P3, first-level economizer inlet temperature measuring point T1, first-level economizer heating surface outlet wall temperature measuring point T2, second-level economizer outlet temperature measuring point T3, second-level economizer heating surface outlet wall temperature measuring point T4, second-level economizer inlet temperature measuring point T5. Implementation

[0026] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Implementation Method 1

[0028] Combined with Figure 2 The present embodiment is described as an economizer system for a tower boiler, wherein the economizer system comprises a secondary economizer system and a primary economizer system, wherein the secondary economizer system and the primary economizer system are connected in series.

[0029] This embodiment connects the secondary economizer system and the primary economizer system in series to achieve coordinated operation between the two-stage economizers, optimize heat exchange efficiency, and provide a basis for subsequent flow regulation and temperature control, thereby improving the overall performance and operational stability of the boiler system.

[0030] Implementation Method 2

[0031] This embodiment is a further explanation of the first embodiment:

[0032] 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 with respect to the center line of the secondary economizer inlet header 4.

[0033] This embodiment ensures uniform distribution of the fluid in the double headers by making the widths of the left and right outlet headers the same, avoiding uneven flow problems caused by differences in header widths, and further improving system stability and heat exchange efficiency.

[0034] Implementation Method 3

[0035] This embodiment is a further explanation of the second embodiment:

[0036] Furthermore, the left outlet header 6L and the right outlet header 6R have the same width.

[0037] This embodiment can enhance the heat exchange capacity of the secondary economizer and optimize the heat transfer efficiency between the flue gas and the working medium by setting a secondary economizer heating surface, thereby improving the overall thermal efficiency of the boiler.

[0038] Implementation Method 4

[0039] This embodiment is a further explanation of the second embodiment:

[0040] Furthermore, the secondary economizer system also includes a secondary economizer heating surface 5 .

[0041] This embodiment sets up a first-level economizer system, including a first-level economizer inlet header, a first-level economizer heating surface and a first-level economizer outlet header, so as to realize the independent operation and heat exchange function of the first-level economizer, provide pre-treated working fluid for the second-level economizer, and optimize the overall heat exchange effect.

[0042] Implementation Method 5

[0043] This embodiment is a further explanation of the first embodiment:

[0044] 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, and the primary economizer inlet header 1, the primary economizer heating surface 2 and the primary economizer outlet header 3 are connected in series.

[0045] This embodiment connects the first-stage economizer outlet header and the second-stage economizer inlet header with a pipeline, thereby achieving seamless connection between the two-stage economizers, ensuring the continuity and stability of the working fluid flow, and providing convenience for flow regulation and temperature control.

[0046] Implementation Method 6

[0047] This implementation is a further explanation of the fifth implementation:

[0048] Furthermore, the primary economizer outlet header 3 and the secondary economizer inlet header 4 are connected by a pipeline.

[0049] This embodiment connects the first-stage economizer outlet header and the second-stage economizer inlet header with a pipeline, thereby achieving seamless connection between the two-stage economizers, ensuring the continuity and stability of the working fluid flow, and providing convenience for flow regulation and temperature control.

[0050] Implementation Method 7

[0051] Combined with Figure 1 To describe this embodiment, 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 embodiments one to six, and the economizer system is located in the boiler furnace.

[0052] This embodiment integrates the economizer system into the tower boiler and locates it in the boiler furnace, so as to fully utilize the furnace space, optimize the heat exchange layout, meet the temperature requirements of the denitrification system, and improve the environmental performance and operating efficiency of the boiler.

[0053] Implementation Method 8

[0054] This embodiment is a further explanation of the seventh embodiment:

[0055] Furthermore, the widths of the left outlet header 6L and the right outlet header 6R of the secondary economizer are both half of the width of the boiler furnace.

[0056] This embodiment designs the width of the left outlet header and the right outlet header of the secondary economizer to be half the width of the boiler furnace, which can effectively reduce the stress concentration phenomenon of the header and the impact of alternating stress on the tube seat, thereby improving the stability and safety of the boiler in the deep peak regulation stage.

[0057] Implementation Method 9

[0058] This embodiment is a further explanation of the seventh embodiment:

[0059] Furthermore, the secondary economizer heating surface 5 is arranged in the front and rear vertical shafts at the uppermost part of the boiler furnace.

[0060] This embodiment arranges the secondary economizer heating surface in the front and rear vertical shafts at the top of the boiler furnace, which can fully utilize the high-temperature flue gas area, optimize the countercurrent heat exchange effect, reduce bubble accumulation, and improve heat exchange efficiency and system operation stability.

[0061] Implementation Method 10

[0062] This embodiment is a further explanation of the seventh embodiment:

[0063] Furthermore, the primary economizer heating surface 2 is arranged below the denitration system catalyst.

[0064] This embodiment arranges the heating surface of the first-stage economizer below the catalyst of the denitrification system, thereby being able to accurately adjust 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.

[0065] Implementation Method Eleven

[0066] This embodiment integrates the technical solutions described in the aforementioned multiple embodiments, combines the actual situation, and further verifies and explains the technical effects of the present invention through specific examples.

[0067] The secondary economizer system consists of a secondary economizer inlet header (single header), a secondary economizer heating surface, and a secondary economizer outlet header (double headers, divided into secondary economizer left / 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 countercurrent manner.

[0068] The feed water flows through the first economizer inlet header, the first economizer heating surface, the first economizer outlet header, the second economizer inlet header, the second economizer heating surface, and the second economizer left / right outlet headers in sequence and then converges to flow to the boiler water wall system. At the same time, the medium flow through the economizer system can be adjusted by adjusting the medium flow through the feed water bypass. In the deep peak regulation stage of the unit, the medium flow through the economizer system can be adjusted to make the boiler denitrification inlet flue gas temperature meet the catalyst input requirements.

[0069] During the deep peak regulation stage of the unit, monitor and ensure that the outlet wall temperature of the heating surface of the secondary economizer is more than 10°C lower than the saturation temperature to avoid the problem of steam resistance caused by bubbles generated in local areas of the economizer during the deep peak regulation stage of the unit.

[0070] During the hot start-up and water supply stage of the unit, monitor and control the pressure deviation on the left and right sides of the secondary economizer inlet to be no more than 0.05MPa to avoid steam resistance problems in the boiler economizer system.

[0071] The present invention overcomes many technical difficulties when solving the design problem of the deep peak-shaving tower boiler economizer system. After many tests and technical adjustments, it finally achieves effective solutions to a series of key problems such as temperature fluctuations, steam resistance problems and alternating stress during the deep peak-shaving process of the boiler.

[0072] In the early stage of research and development, faced with the problem of alternating stress in the economizer system during the deep peak regulation of the boiler, the R&D team tried a variety of header design solutions, including increasing the thickness of the header and adjusting the pipeline layout. However, these solutions failed to effectively alleviate the alternating stress, but instead increased the size and cost of the boiler. In particular, when adjusting the header design, despite the use of a reinforced structure, fatigue damage at the root of the tube seat was still not effectively avoided, resulting in leakage and unstable operation.

[0073] After repeated experiments and theoretical analysis, the inventors found that at the boiler economizer outlet header, the alternating stress is mainly caused by the temperature fluctuations caused by the header width and boiler load changes. Therefore, the invention team proposed a double header design (left outlet header and right outlet header), and made the width of each header half the width of the boiler furnace. This innovative design effectively disperses the stress at the economizer outlet header during the deep peak regulation of the boiler, greatly reducing the alternating stress. Through this improvement, the boiler system can operate stably under high-frequency peak regulation and load fluctuations without leakage problems, solving the technical bottleneck that has long plagued this field.

[0074] The inventors also experienced many failed attempts to solve the steam resistance problem. In the initial design, they tried to use multiple headers to optimize the startup process. As a result, due to pressure imbalance, hot startup was prone to steam resistance problems. Faced with this technical difficulty, the invention team conducted repeated research and calculations and finally determined to use a two-stage economizer inlet header in the form of a header. This design simplified the system structure, ensured smooth fluid flow in the boiler economizer system during hot startup, avoided the occurrence of steam resistance, and successfully ensured the rapid startup of the unit.

[0075] In addition, during the research process, it was found that when the secondary economizer heating surface is arranged in the vertical shaft at the top of the boiler furnace, it is easily affected by the flow pattern of the flue gas, which can easily lead to local bubble generation and cause steam resistance. By adopting the countercurrent heat exchange method, the invention team successfully avoided the accumulation of bubbles inside the heating surface. Although the initial countercurrent design failed to achieve the expected effect due to the flow fluctuation problem of the boiler system, through multiple optimizations and experiments on the boiler airflow path, a relatively ideal heat exchange effect was finally achieved, avoiding the bubble problem caused by excessive temperature difference during deep peak regulation.

[0076] These technological breakthroughs were achieved through continuous experimentation and optimization. Each failure accumulated valuable experience for the final success, and the invention team put in a lot of creative work. Through this innovative design, the present invention effectively improves the stability, reliability and efficiency of the boiler during deep peak regulation, solves the technical bottleneck in deep peak regulation that cannot be overcome by existing technologies, and greatly improves the regulation ability of the boiler system during deep peak regulation and rapid load changes.

[0077] In summary, the present invention not only overcomes a number of technical difficulties, but also successfully solves a series of problems such as alternating stress and steam resistance of the economizer system during deep peak regulation through innovative design and multiple experimental verifications, reflecting the tremendous creative work that the inventor has put into this patent.

[0078] The technical solution provided by the present invention is further described in detail through the above specific implementation modes in order to highlight the advantages and benefits of the technical solution provided by the present invention. However, the above specific implementation modes are not intended to limit the present invention. Any reasonable modification and improvement of the present invention, combination of implementation modes and equivalent substitution within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0079] Those skilled in the art will appreciate that the above are only preferred embodiments of the present invention, and the various embodiments of the present disclosure and / or the features described in the claims may be combined or combined in various ways, even if such combinations or combinations are not explicitly described in the present disclosure. It is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art may still modify the technical solutions described in the aforementioned embodiments, or perform equivalent substitutions on some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

[0080] Although preferred embodiments of the present invention have been described, additional changes and modifications may be made to these embodiments by those skilled in the art once the basic inventive concepts are known. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A tower boiler economizer system, characterized in that: The economizer system includes a secondary economizer system and a primary economizer system, and the secondary economizer system and the primary economizer system are connected in series.

2. The economizer system according to claim 1, characterized in that: The secondary economizer system comprises a secondary economizer inlet header (4) and a secondary economizer outlet header (6), wherein 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, wherein the double header comprises a left outlet header (6L) and a right outlet header (6R), and the left outlet header (6L) and the right outlet header (6R) are arranged in a mirror image with respect to the center line of the secondary economizer inlet header (4).

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

4. The economizer system according to claim 2, characterized in that: The secondary economizer system further comprises a secondary economizer heating surface (5).

5. The economizer system according to claim 1, characterized in that: The primary economizer system comprises a primary economizer inlet header (1), a primary economizer heating surface (2) and a primary economizer outlet header (3), wherein the primary economizer inlet header (1), the primary economizer heating surface (2) and the primary economizer outlet header (3) are connected in series.

6. The economizer system according to claim 5, characterized in that: The first-stage economizer outlet header (3) and the second-stage economizer inlet header (4) are connected by a pipeline.

7. A tower boiler, comprising a denitration system and front and rear shafts at the uppermost part of the boiler furnace, characterized in that: The tower boiler also includes an economizer system as described in any one of claims 1 to 6, and the economizer system is located in the boiler furnace.

8. The tower boiler according to claim 7, characterized in that: 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.

9. The tower boiler according to claim 7, characterized in that: The secondary economizer heating surface (5) is arranged in the front and rear vertical shafts at the uppermost part of the boiler furnace.

10. The tower boiler according to claim 7, characterized in that: The primary economizer heating surface (2) is arranged below the denitration system catalyst.

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