A rotary air preheater for a pulverizing system boiler using waste gas feeding and intermediate storage

Abstract

This invention specifically relates to a rotary air preheater for a pulverized coal boiler with a waste gas feeding and storage system. It includes an air preheater shell, hot-section heat storage plates, and cold-section heat storage plates, as well as at least one air intake and a supporting frame. The hot-section and cold-section heat storage plates are placed inside the air preheater shell, with the hot-section heat storage plates positioned above the cold-section heat storage plates. The air intake is located on the side of the air preheater shell, and the supporting frame is placed between the hot-section and cold-section heat storage plates. This invention achieves the purpose of opening the rotary air preheater shell to extract warm air by cutting the outer ring of the cold-section heat storage plates, thus completely solving the problem of a significant increase in flue gas temperature after the pulverized coal feeding system is stopped when a traditional waste gas feeding pulverized coal boiler is converted from a tubular air preheater to a rotary air preheater.

Description

Technical Field

[0001] This invention belongs to the field of thermal power generation technology, specifically relating to a rotary air preheater for a pulverizing system boiler with exhaust gas feeding and storage. Background Technology

[0002] The pulverizing system is the most important system in a thermal power plant, responsible for preparing pulverized coal for the boiler. Pulverizing systems are divided into two categories: intermediate storage pulverizing systems and direct-fired pulverizing systems. Intermediate storage pulverizing systems are further divided into two types: exhaust gas feeding and hot air feeding. Exhaust gas feeding intermediate storage pulverizing systems are generally equipped with tubular air preheaters, which provide both hot air for pulverizing and warm air for coal feeding. When the pulverizing system is running, the hot air from the tubular air preheater is used for drying the raw coal, particle carrying, and pulverized coal separation. The exhaust gas separated by the fine powder separator is used to feed the pulverized coal into the furnace for combustion. Figure 1 As shown in line 1; when the pulverizing system stops, the pulverized coal is fed into the furnace by the warm air supplied by the tubular air preheater, and the cold air damper at the inlet of the pulverizer is kept closed, as shown in line 1. Figure 1 As shown in line 2 above, under both air source configurations, regardless of whether the pulverizing system is running or stopped, a sufficient amount of air is maintained passing through the tubular air preheater, effectively reducing the boiler exhaust temperature.

[0003] In recent years, some boilers originally designed as medium-storage, pulverized coal-fired boilers have been replaced with rotary air preheaters, such as... Figure 2 As shown, however, the modification resulted in a significant increase in flue gas temperature after the pulverizing system was shut down. The main reason is that when a boiler with a medium-storage, exhaust gas-feeding pulverizing system is converted from a tubular air preheater to a rotary air preheater, the rotary air preheater's structure lacks a dedicated warm air extraction point. Therefore, there is no dedicated warm air for conveying pulverized coal. Instead, it requires mixing hot air (approximately 340-350℃) with ambient cold air (approximately 20℃) to obtain warm air at 90-120℃ for pulverized coal conveying. Figure 3 The mixing ratio is achieved by adjusting the hot and cold air dampers for powder feeding in the equipment. However, this adjustment method introduces too much cold air, causing the exhaust gas temperature to rise by about 12-20°C after the pulverizing system is stopped. Summary of the Invention

[0004] To address the aforementioned problems, this invention designs a novel air preheater heat storage plate structure, enabling the extraction of warm air through openings in the shell of a rotary air preheater. The air intake temperature can be controlled by adjusting the height of the heat storage plate structure in the local cold section to meet the needs of different applications.

[0005] The present invention provides a rotary air preheater for a pulverized coal boiler with exhaust gas feeding and intermediate storage, comprising an air preheater shell 1, hot section heat storage plates 2 and cold section heat storage plates 3, and at least one air intake 4 and a support frame 5; the hot section heat storage plates 2 and the cold section heat storage plates 3 are placed inside the air preheater shell 1, with the hot section heat storage plates 2 positioned above the cold section heat storage plates 3, the air intake 4 being located on the side of the air preheater shell 1, and the support frame 5 being placed between the hot section heat storage plates 2 and the cold section heat storage plates 3.

[0006] Furthermore, the cross-section of the cold section heat storage plate 3 is a "convex" shaped structure, divided into upper and lower cylinders, with the upper part being concave, creating a space volume filled with air in the upper and lower parts.

[0007] Furthermore, the air intake 4 is located on the air preheater housing 1 corresponding to the recessed position of the cold section heat storage plate 3. The air intake 4 is square, and one or more can be opened as needed.

[0008] Furthermore, the support frame 5 is located in the concave position of the cold section heat storage plate 3 to support the hot section heat storage plate 2 in the concave position and prevent the hot section heat storage plate 2 from collapsing.

[0009] Furthermore, the hot section heat storage plate 2 generates hot air at 340-350℃; in the "convex" shaped structure of the cold section heat storage plate 3, the heat storage plate corresponding to the high position generates warm air at 120-180℃, and the heat storage plate corresponding to the low position generates warm air at 90-120℃.

[0010] Furthermore, after the heat storage plate corresponding to the high position of the cold section heat storage plate 3 generates warm air at 120-180°C, the warm air enters the hot section heat storage plate 2 and continues to be heated to 340-350°C. After the heat storage plate corresponding to the low position of the cold section heat storage plate 3 generates warm air at 90-120°C, it is extracted from the air intake port 4.

[0011] Furthermore, by controlling the height of the low-position heat storage plate in the "convex" shaped structure of the cold section heat storage plate 3, the temperature of the air extracted from the air intake 4 is controlled.

[0012] The beneficial effects of this invention are as follows:

[0013] 1. This invention creates an air volume space by cutting the outer ring of the cold section heat storage plates, thus achieving the purpose of opening the shell of the rotary air preheater to extract warm air. This can completely solve the problem of a significant increase in flue gas temperature after the pulverizing system is stopped when the traditional medium-storage type pulverized coal boiler is converted from a tubular air preheater to a rotary air preheater.

[0014] 2. The temperature of the extracted warm air is precisely controlled by adjusting the cutting height of the outer ring of the cold section heat storage fins. This meets the air temperature requirements for different purposes.

[0015] 3. This invention can be used to convert a tubular air preheater into a rotary air preheater, and it can also be used to solve the problem of flue gas temperature after the pulverizing system is stopped when the pulverizing system is connected to a rotary air preheater with exhaust gas from a storage tank.

[0016] 4. This invention is particularly applicable to the modular combination structure of heat storage plates in air preheaters. Attached Figure Description

[0017] Figure 1 Diagram showing the relationship between the operation mode of the exhaust gas pulverizing system and the air source of the tubular air preheater;

[0018] Figure 2 This is a structural diagram of a traditional rotary air preheater.

[0019] Figure 3 Diagram showing the relationship between the operation mode of the exhaust gas pulverizing system and the air source of a traditional rotary air preheater;

[0020] Figure 4 The figures show a comparison between a conventionally designed cold-section heat storage plate and a cold-section heat storage plate according to an embodiment of the present invention, wherein (a) represents a conventionally designed cold-section heat storage plate and (b) represents a cold-section heat storage plate according to an embodiment of the present invention.

[0021] Figure 5 This is a structural diagram of a rotary air preheater according to an embodiment of the present invention;

[0022] Figure 6 This diagram illustrates the relationship between the operation mode of the exhaust gas pulverizing system and the air source of the rotary air preheater in this embodiment of the invention. Detailed Implementation

[0023] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0024] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0025] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0026] This technology utilizes a novel air preheater heat storage fin structure to extract warm air through openings in the shell of a rotary air preheater. The air intake temperature can be controlled by adjusting the height of the heat storage fin structure in the local cold section to meet the needs of various applications.

[0027] like Figure 5 The diagram shows a rotary air preheater for a pulverized coal boiler with a waste gas-feeding and storage system, provided by an embodiment of the present invention. It includes an air preheater shell 1, hot section heat storage plates 2, and cold section heat storage plates 3, and also includes at least one air intake 4 and a support frame 5. The hot section heat storage plates 2 and the cold section heat storage plates 3 are placed inside the air preheater shell 1, with the hot section heat storage plates 2 positioned above the cold section heat storage plates 3. The air intake 4 is located on the side of the air preheater shell 1, and the support frame 5 is placed between the hot section heat storage plates 2 and the cold section heat storage plates 3.

[0028] like Figure 4 The diagram shows a comparison between a conventionally designed cold-section heat storage plate and a cold-section heat storage plate according to an embodiment of the present invention, where (a) represents a conventionally designed cold-section heat storage plate and (b) represents a cold-section heat storage plate according to an embodiment of the present invention.

[0029] After the conventional cold section heat storage plate heats the air to 180-200℃, the air enters the hot section heat storage plate and is further heated to 340-350℃. Since the conventional cold section heat storage plate heats the air to 180-200℃, which exceeds the temperature of 90-120℃ required for powder feeding, and since it does not have an air intake 4, the air from the cold section heat storage plate cannot be extracted.

[0030] In this embodiment, the cross-section of the cold section heat storage plate 3 is a "convex" shaped structure. The heat storage plate corresponding to the high position generates warm air at 120-180℃, and the heat storage plate corresponding to the low position generates warm air at 90-120℃.

[0031] After the heat storage plate at the high position of the cold section heat storage plate 3 generates warm air at 120-180°C, the warm air enters the hot section heat storage plate 2 and continues to be heated to 340-350°C; after the heat storage plate at the low position of the cold section heat storage plate 3 generates warm air at 90-120°C, it is drawn out from the air intake 4 and sent into the powder delivery warm air damper through the air duct.

[0032] The heating temperature of the heat storage plate is linearly related to the height of the heat storage plate. Therefore, by controlling the height of the heat storage plate at the lower position in the "convex" shaped structure of the cold section heat storage plate 3, the temperature of the air extracted from the air intake 4 can be controlled.

[0033] The air intake 4 is located on the air preheater housing 1 corresponding to the recessed position of the cold section heat storage plate 3. The air intake 4 is square and one or more can be opened as needed.

[0034] The support frame 5 is located in the concave position of the cold section heat storage plate 3, supporting the hot section heat storage plate 2 in the concave position and preventing the hot section heat storage plate 2 from collapsing.

[0035] When the pulverizing system stops, the warm air for pulverizing is drawn out through air intake 4, connected to the warm air damper for pulverizing through the air duct, and then conveyed by the pulverizer. When line 2 is operating normally, the cold air damper for pulverizing is completely closed. See details. Figure 6 A hot air and warm air connecting gate is added between the hot air duct of line 1 and the warm air duct of line 2. When a higher powder delivery temperature is required, the hot air and warm air connecting gate is opened, and the hot air generated by the heat storage plate 2 in the hot section is added to increase the inlet temperature of the powder discharger.

[0036] This invention creates an air volume space by cutting the outer ring of the cold-section heat storage plates, thus achieving the purpose of opening the shell of the rotary air preheater to extract warm air. This completely solves the problem of a significant increase in exhaust gas temperature after the pulverizing system is stopped when converting a traditional medium-storage type pulverized gas boiler from a tubular air preheater to a rotary air preheater. The temperature of the extracted warm air is precisely controlled by adjusting the cutting height of the outer ring of the cold-section heat storage plates, meeting the air temperature requirements for different purposes. This technology can be used to convert tubular air preheaters to rotary air preheaters, and also to solve the problem of exhaust gas temperature after the pulverizing system is stopped when using a medium-storage type pulverized gas boiler with a rotary air preheater. This invention is particularly suitable for the modular assembly structure of the air preheater heat storage plates.

Claims

1. A rotary air preheater for a boiler of a storage pulverizing system in a pulverized coal-fired boiler, comprising an air preheater housing (1), a hot section regenerator (2), and a cold section regenerator (3), characterized in that, It also includes at least one air intake (4) and a support skeleton (5); the hot section heat storage sheet (2) and the cold section heat storage sheet (3) are placed in the air preheater shell (1), and the hot section heat storage sheet (2) is placed above the cold section heat storage sheet (3), the air intake (4) is arranged on the side of the air preheater shell (1), and the support skeleton (5) is placed between the hot section heat storage sheet (2) and the cold section heat storage sheet (3); The cross section of the cold section heat storage sheet (3) is a "convex" structure, which is divided into two cylindrical upper and lower parts, the upper part is concave, and an air-filled space volume is created between the upper and lower parts; The air intake (4) is arranged on the air preheater shell (1) corresponding to the concave position of the cold section heat storage sheet (3).

2. The rotary air preheater according to claim 1, characterized in that The air intake (4) is square, and one or more are opened according to needs.

3. The rotary air preheater according to claim 2, characterized in that The support skeleton (5) is arranged at the concave position of the cold section heat storage sheet (3) to support the hot section heat storage sheet (2) at the concave position and prevent the hot section heat storage sheet (2) from collapsing.

4. The rotary air preheater according to claim 3, characterized in that The hot section heat storage sheet (2) generates hot air of 340-350℃; in the "convex" structure of the cold section heat storage sheet (3), the heat storage sheet corresponding to the high position generates warm air of 120-180℃, and the heat storage sheet corresponding to the low position generates warm air of 90-120℃.

5. The rotary air preheater according to claim 4, characterized in that After the heat storage sheet corresponding to the high position of the cold section heat storage sheet (3) generates warm air of 120-180℃, the warm air enters the hot section heat storage sheet (2) upward and continues to be heated to 340-350℃, and after the heat storage sheet corresponding to the low position of the cold section heat storage sheet (3) generates warm air of 90-120℃, the warm air is extracted through the air intake (4).

6. The rotary air preheater according to claim 5, characterized in that By controlling the height of the heat storage sheet corresponding to the low position in the "convex" structure of the cold section heat storage sheet (3), the temperature of the air extracted through the air intake (4) is controlled.

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