Air preheater cold section anti-ash-blocking device and using method thereof

Abstract

The invention provides an air preheater cold section anti-ash-blocking device and a using method thereof, and belongs to the technical field of coal-fired units. The problem of ash blockage caused by the fact that fly ash is adhered to the cold section of the tubular air preheater of the coal-fired unit in a liquid ammonium bisulfate state is solved. The anti-ash-blocking device comprises a cold-section air preheater, a connecting flue and a flue gas distribution header, the cold-section air preheater is partitioned in the width direction of a flue gas channel, a plurality of independent flue gas partitions are formed in the cold-section air preheater, one end of the connecting flue is connected with an outlet flue of the economizer, and the other end of the connecting flue is connected with an outlet flue of the economizer. The other end of the connecting flue is connected with a flue gas distribution header, and the flue gas distribution header is respectively connected with each independent flue gas subarea. The device is mainly used for coal-fired units.

Description

Technical Field

[0001] This invention belongs to the technical field of coal-fired power units, and in particular relates to an anti-ash blockage device for the cold section of an air preheater and its usage method. Background Technology

[0002] Currently, coal-fired boilers (pulverized coal boilers) employ Selective Catalytic Reduction (SCR) technology for denitrification. During the SCR system's denitrification process, the conversion of SO2 to SO3 is further enhanced as the flue gas passes through the SCR catalyst, resulting in the formation of more SO3. During denitrification, the escape of NH3 is inevitable; it reacts with SO3 after the SCR unit to form ammonium bisulfate. Ammonium bisulfate exists in gaseous, liquid, and particulate states at different temperatures. For coal-fired units, the fly ash content in the flue gas is high. Ammonium bisulfate is liquid within the temperature range of 146℃–207℃, gaseous above 207℃, and particulate below 146℃. Gaseous or particulate ammonium bisulfate flows through the preheater with the flue gas and does not affect it. Conversely, liquid ammonium bisulfate has a strong ability to capture fly ash and combines with fly ash particles in the flue gas, adhering to the heat transfer elements of the preheater to form molten salt-like ash deposits, causing corrosion and blockage of the preheater, thus affecting the heat exchange of the preheater and the normal operation of the unit.

[0003] Small and medium-sized pulverized coal boilers often use tubular air preheaters. In the lower section of the cold section of the air preheater, the flue gas temperature is between 146℃ and 207℃, which can easily cause ash blockage in the cold section of the air preheater due to the presence of ammonium bisulfate. Summary of the Invention

[0004] In view of this, the present invention aims to provide an anti-ash blockage device for the cold section of an air preheater and its usage method, so as to solve the problem of ash blockage caused by the liquid adhesion of fly ash in the cold section of a tubular air preheater in a coal-fired unit.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: an anti-ash blockage device for the cold section of an air preheater, comprising a cold section air preheater, a connecting flue, and a flue gas distribution manifold. The cold section air preheater is divided into sections in the width direction of the flue gas passage, forming several individual flue gas sections within the cold section air preheater. One end of the connecting flue is connected to the economizer outlet flue, and the other end of the connecting flue is connected to the flue gas distribution manifold. The flue gas distribution manifold is connected to each individual flue gas section.

[0006] Furthermore, a control damper is provided between the flue gas distribution manifold and each individual flue gas zone.

[0007] Furthermore, the cold section air preheater is connected to the hot section air preheater.

[0008] Furthermore, the hot section air preheater is connected to the denitrification mechanism.

[0009] Furthermore, the denitrification mechanism is connected to the economizer outlet flue.

[0010] Furthermore, the temperature of the flue gas inside the connecting flue is higher than 207°C.

[0011] Furthermore, the aforementioned cold-section air preheater and hot-section air preheater are tubular air preheaters.

[0012] Furthermore, a catalyst layer is provided inside the denitrification mechanism.

[0013] Furthermore, the air preheater cold section anti-ash blockage device is used in coal-fired boilers.

[0014] The present invention also provides a method for using an anti-ash blockage device for the cold section of an air preheater, specifically: the flue gas from the outlet flue of the economizer (or SCR device) is extracted and then enters a separate flue gas zone of the cold section air preheater after passing through the connecting flue and the flue gas distribution box, so that the flue gas temperature is higher than 207°C. At this temperature, ammonium bisulfate is in a gaseous state, which prevents ash blockage in the cold section air preheater.

[0015] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention effectively solves the ash blockage problem caused by the liquid adhesion of ammonium bisulfate by dividing the cold section of the tubular air preheater into zones and heating it with flue gas. By extracting high-temperature flue gas from the economizer (or SCR device) and injecting it into the cold section air preheater through connecting flue ducts and flue gas distribution boxes, the flue gas temperature can be raised to above 207°C, causing ammonium bisulfate to change from a liquid to a gaseous state, fundamentally eliminating its characteristic of adhering to fly ash. This zoned heating method ensures the complete vaporization of ammonium bisulfate and avoids the impact of raising the overall exhaust gas temperature on boiler efficiency. After implementation, it significantly reduces ash accumulation in the cold section preheater, extends the equipment maintenance cycle, maintains the normal heat exchange performance of the preheater, and ensures the safe and stable operation of the unit. Attached Figure Description

[0016] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the overall structure of an anti-ash blockage device for the cold section of an air preheater according to the present invention; Figure 2 This is a top view schematic diagram of an anti-ash blockage device for the cold section of an air preheater according to the present invention.

[0017] In the picture: 1-Economizer outlet flue, 2-Denitrification mechanism, 3-Hot section air preheater, 4-Cold section air preheater, 5-Connecting flue, 6-Flue gas distribution manifold, 7-Control damper. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other, and the described embodiments are only some embodiments of the present invention, not all embodiments.

[0019] See Figure 1-2 This embodiment describes an anti-clogging device for the cold section of an air preheater, comprising a cold section air preheater 4, a connecting flue duct 5, and a flue gas distribution manifold 6. The cold section air preheater 4 is divided into sections along the width of the flue gas passage, forming several individual flue gas sections within the cold section air preheater 4. One end of the connecting flue duct 5 is connected to the economizer outlet flue duct 1, and the other end of the connecting flue duct 5 is connected to the flue gas distribution manifold 6. The flue gas distribution manifold 6 is connected to each individual flue gas section.

[0020] In this embodiment, a control damper 7 is provided between the flue gas distribution manifold 6 and each individual flue gas zone. The cold section air preheater 4 is connected to the hot section air preheater 3. The hot section air preheater 3 is connected to the denitrification mechanism 2. The denitrification mechanism 2 is connected to the economizer outlet flue 1. The flue gas temperature in the connecting flue 5 is higher than 207°C. The cold section air preheater 4 and the hot section air preheater 3 are tubular air preheaters. A catalyst layer is provided inside the denitrification mechanism 2. The cold section anti-ash blockage device of the air preheater is used for coal-fired boilers.

[0021] This embodiment describes the use of an anti-ash blockage device for the cold section of an air preheater. Specifically, the flue gas from the economizer outlet flue 1 is extracted and then enters a separate flue gas zone of the cold section air preheater 4 after passing through the connecting flue 5 and the flue gas distribution box 6, so that the flue gas temperature is higher than 207°C. At this temperature, ammonium bisulfate is in a gaseous state, which prevents ash blockage in the cold section air preheater 4.

[0022] The specific explanation is as follows: An anti-ash-clogging device for the cold section of an air preheater mainly includes an economizer outlet flue 1, a denitrification mechanism 2, a hot section air preheater 3, a cold section air preheater 4, a connecting flue 5, a flue gas distribution manifold 6, and control dampers 7. The cold section air preheater 4 is partitioned along the width of the flue gas passage, forming several individual flue gas zones. One end of the connecting flue 5 is connected to the economizer outlet flue 1, and the other end is connected to the flue gas distribution manifold 6. The flue gas distribution manifold 6 is connected to each individual flue gas zone via control dampers 7. The hot section air preheater 3 is connected to the cold section air preheater 4, the denitrification mechanism 2 is connected to the hot section air preheater 3, and the economizer outlet flue 1 is connected to the denitrification mechanism 2.

[0023] During operation, the high-temperature flue gas first flows through the economizer outlet flue 1 and enters the denitrification unit 2 for denitrification treatment. Subsequently, the flue gas passes sequentially through the hot-section air preheater 3 and the cold-section air preheater 4. Simultaneously, the high-temperature flue gas drawn from the economizer outlet flue 1 enters the flue gas distribution manifold 6 through the connecting flue 5, where its temperature is maintained above 207°C. By adjusting the control dampers 7, the high-temperature flue gas is separately sent to each individual flue gas zone of the cold-section air preheater 4.

[0024] The working principle of this device is as follows: when high-temperature flue gas enters a separate section of the cold-section air preheater 4, the flue gas temperature in that section can be raised to above 207℃. Under this temperature condition, ammonium bisulfate, which was originally in a liquid state, will be converted into a gaseous state and lose its ability to adhere to fly ash. The gaseous ammonium bisulfate flows away with the flue gas and will not form ash accumulation on the heat transfer elements of the preheater. By using zoned heating, complete vaporization of ammonium bisulfate is ensured while avoiding any impact on the overall flue gas temperature of the boiler.

[0025] The function of the control damper 7 is to regulate the flue gas flow in each zone, ensuring that each zone receives sufficient high-temperature flue gas. The flue gas distribution manifold 6 enables the individual distribution of high-temperature flue gas. During operation, the preheater tube boxes in different zones can be flexibly heated according to actual operating conditions to achieve the best anti-clogging effect.

[0026] This invention effectively solves the ash blockage problem caused by the liquid adhesion of ammonium bisulfate by dividing the cold section of the tubular air preheater into zones and heating it with flue gas. By extracting high-temperature flue gas from the economizer and injecting it into the cold section air preheater through connecting ducts and a flue gas distribution manifold, the flue gas temperature can be raised to above 207°C, causing the ammonium bisulfate to transform from a liquid to a gaseous state, fundamentally eliminating its characteristic of adhering to fly ash. This zoned heating method ensures complete vaporization of ammonium bisulfate while avoiding the impact of raising the overall exhaust gas temperature on boiler efficiency. After implementation, it significantly reduces ash accumulation in the cold section preheater, extends equipment maintenance cycles, maintains the normal heat exchange performance of the preheater, and ensures the safe and stable operation of the unit.

[0027] The specific embodiments of the present invention disclosed above are merely illustrative of the invention. These embodiments do not exhaustively describe all details, nor do they limit the invention to the specific embodiments described. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A device for preventing ash blockage in the cold section of an air preheater, characterized in that: It includes a cold section air preheater (4), a connecting flue (5), and a flue gas distribution manifold (6). The cold section air preheater (4) is divided into sections in the width direction of the flue gas passage, so that several separate flue gas sections are formed in the cold section air preheater (4). One end of the connecting flue (5) is connected to the economizer outlet flue (1), and the other end of the connecting flue (5) is connected to the flue gas distribution manifold (6). The flue gas distribution manifold (6) is connected to each separate flue gas section.

2. The anti-clogging device for the cold section of an air preheater according to claim 1, characterized in that: Each flue gas distribution manifold (6) is equipped with a control damper (7) between itself and each individual flue gas zone.

3. The anti-clogging device for the cold section of an air preheater according to claim 1, characterized in that: The cold section air preheater (4) is connected to the hot section air preheater (3).

4. The anti-clogging device for the cold section of an air preheater according to claim 3, characterized in that: The hot section air preheater (3) is connected to the denitrification mechanism (2).

5. The anti-clogging device for the cold section of an air preheater according to claim 4, characterized in that: The denitrification mechanism (2) is connected to the economizer outlet flue (1).

6. The anti-clogging device for the cold section of an air preheater according to claim 1, characterized in that: The flue gas temperature in the connecting flue (5) is higher than 207°C.

7. The anti-clogging device for the cold section of an air preheater according to claim 3, characterized in that: The above-mentioned cold section air preheater (4) and hot section air preheater (3) are tubular air preheaters.

8. The anti-clogging device for the cold section of an air preheater according to claim 4, characterized in that: The denitrification mechanism (2) is equipped with a catalyst layer.

9. The anti-clogging device for the cold section of an air preheater according to claim 1, characterized in that: The air preheater cold section ash-blocking device is used in coal-fired boilers.

10. A method of using the anti-ash blockage device for the cold section of an air preheater as described in claim 1, characterized in that: The flue gas from the economizer outlet flue (1) is drawn and then enters the separate flue gas zone of the cold section air preheater (4) after passing through the connecting flue (5) and the flue gas distribution box (6), so that the flue gas temperature is higher than 207°C. At this temperature, ammonium hydrogen sulfate is in a gaseous state, which prevents the cold section air preheater (4) from being blocked with ash.

Images