An apparatus for preventing ash accumulation in the horizontal section at the inlet of the bypass flue of the economizer of a coal-fired boiler

Abstract

The present invention provides a device for preventing ash accumulation in the horizontal section at the inlet of the bypass flue of a coal-fired boiler economizer, which can effectively avoid ash accumulation in the horizontal section of the bypass flue and mechanical jamming of the baffle door, ensure the catalyst efficiency and meet the requirements for the operation of denitration; it includes a boiler furnace, the boiler furnace is sequentially connected to a low-temperature superheater, a boiler economizer, and an SCR denitration reactor after passing through the boiler furnace outlet flue, a boiler bypass flue is provided between the outlet of the boiler furnace outlet flue and the inlet of the SCR denitration reactor, a bypass flue baffle door is installed at the inlet of the boiler bypass flue, the bypass flue baffle door is arranged on the bypass flue inlet horizontal flue of the boiler bypass flue, and a connected bypass flue ash conveying channel is provided between the bypass flue inlet horizontal flue before the bypass flue baffle door and the boiler furnace outlet flue.

Description

Technical Field

[0001] The present invention relates to the technical field of economizer bypass flues, and specifically to a device for preventing ash accumulation in the horizontal section at the inlet of the economizer bypass flue of a coal-fired boiler. Background Art

[0002] Currently, it has become an inevitable trend for thermal power plants to participate in flexible peak shaving, and its primary goal is to reduce the minimum technical output of the unit. For the existing widely used flue gas denitrification technology (SCR technology), due to reasons such as catalyst activity, its operating temperature is generally between 310°C and 420°C. However, at low loads (generally below 50% of the rated load), the flue gas temperature cannot meet the requirements. In order to increase the inlet flue gas temperature of the flue gas denitrification system at low loads and achieve full-load operation of the SCR flue gas denitrification device, most coal-fired power plants adopt the economizer bypass transformation scheme, that is, a damper door is installed on the economizer bypass flue to adjust the amount of high-temperature flue gas at the inlet of the SCR device. Generally, under high-load conditions of the boiler, the economizer bypass damper door is closed; under low-load conditions of the boiler, when the flue gas temperature is lower than the minimum ammonia injection temperature of the catalyst, the damper door is opened. However, during actual operation, when the economizer bypass flue damper door is closed, a "dead zone" will be formed at the front end of the damper door, resulting in serious ash accumulation at the horizontal flue position at the inlet of the bypass flue. If the horizontal section of the economizer bypass flue accumulates ash for a long time, it is easy to cause mechanical jamming of the damper door, so that when the unit needs to completely close the damper door at high load, the damper door cannot be closed tightly, and high-temperature flue gas will enter the SCR denitrification reactor through the economizer bypass flue, causing local overheating of the flue gas and affecting the catalyst efficiency; and when the unit needs to open the damper door at low load, it cannot be fully opened, or due to serious ash accumulation, the resistance of the bypass flue increases, and an effective pressure difference cannot be formed, resulting in less high-temperature flue gas entering the SCR denitrification reactor, and the flue gas temperature cannot meet the requirements for denitrification operation. Summary of the Invention

[0003] In view of the above problems, the present invention provides a device for preventing ash accumulation in the horizontal section at the inlet of the economizer bypass flue of a coal-fired boiler, which can effectively avoid ash accumulation in the horizontal section of the bypass flue and mechanical jamming of the damper door, and ensure catalyst efficiency and meet the requirements for denitrification operation.

[0004] The technical solution is as follows: A device for preventing ash accumulation in the horizontal section of the inlet of the bypass flue of a coal-fired boiler economizer, which includes a boiler furnace. The boiler furnace is sequentially connected to a low-temperature superheater, a boiler economizer, and an SCR denitration reactor after passing through the boiler furnace outlet flue. A boiler bypass flue is provided between the outlet of the boiler furnace outlet flue and the inlet of the SCR denitration reactor. A bypass flue baffle door is installed at the inlet of the boiler bypass flue. It is characterized in that: The bypass flue baffle door is arranged on the horizontal flue of the inlet of the bypass flue of the boiler bypass flue, and a connected bypass flue ash conveying channel is provided between the horizontal flue of the inlet of the bypass flue before the bypass flue baffle door and the boiler furnace outlet flue.

[0005] Its further features are as follows:

[0006] The bypass flue ash conveying channel is divided into a vertical section and an arc section. The vertical section is connected to the horizontal flue of the inlet of the bypass flue, and the arc section is connected to the boiler furnace outlet flue;

[0007] The widths of the two end connection ports on the bypass flue ash conveying channel connected to the horizontal flue of the inlet of the bypass flue and the boiler furnace outlet flue are both 500mm - 800mm;

[0008] The distance between the bypass flue baffle door and the vertical section is not greater than 500mm;

[0009] The included angle between the outer wall of the arc section and the outer wall of the boiler furnace outlet flue is not greater than 45°;

[0010] A main baffle door is installed on the connecting flue between the boiler economizer and the SCR denitration reactor.

[0011] The beneficial effect of the present invention is that a connected bypass flue ash conveying channel is provided between the horizontal flue of the inlet of the bypass flue before the bypass flue baffle door and the boiler furnace outlet flue. Then, the ash-containing flue gas will flow back into the boiler furnace outlet flue through the bypass flue ash conveying channel, avoiding the problems of ash accumulation in the horizontal flue of the inlet of the bypass flue and mechanical jamming of the baffle door. Thus, it can effectively ensure the catalyst efficiency and meet the requirements of denitration operation, and has good economic use value. Brief Description of the Drawings

[0012] Figure 1 is a structural schematic diagram of the present invention;

[0013] Figure 2 is Figure 1 the enlarged structural schematic diagram at A in

[0014] Figure 3 is Figure 1Schematic diagram of the enlarged structure at point A in (the bypass flue damper door is in the closed state). Detailed implementation manners

[0015] As Figures 1 to 3 shown, a device for preventing ash accumulation in the horizontal section of the inlet of the bypass flue of a coal-fired boiler economizer according to the present invention includes a boiler furnace 1. The boiler furnace 1 is sequentially connected to a low-temperature superheater 3, a boiler economizer 4, and an SCR denitration reactor 6 after passing through a boiler furnace outlet flue 2. A boiler bypass flue 7 is provided between the outlet of the boiler furnace outlet flue 2 and the inlet of the SCR denitration reactor 6. A bypass flue damper door 9 is installed at the inlet of the boiler bypass flue 7. A main damper door 5 is installed on a connecting flue 11 between the boiler economizer 4 and the SCR denitration reactor 6. The bypass flue damper door 9 is arranged on a bypass flue inlet horizontal flue 8 of the boiler bypass flue 7. A connected bypass flue ash conveying channel 10 is provided between the bypass flue inlet horizontal flue 8 before the bypass flue damper door 9 and the boiler furnace outlet flue 2.

[0016] The bypass flue ash conveying channel 10 is divided into a vertical section 12 and an arc section 13, which is beneficial to the conveying of fly ash. The vertical section 12 is communicated with the bypass flue inlet horizontal flue 8, and the arc section 13 is communicated with the boiler furnace outlet flue 2.

[0017] The widths s of the two end connection ports on the bypass flue ash conveying channel 10 connected to the bypass flue inlet horizontal flue 8 and the boiler furnace outlet flue 2 are both 500 mm; the distance a between the outer wall of the vertical section 12 and the boiler furnace outlet flue 2 is the same as the width of the boiler bypass flue 7; the distance b between the bypass flue damper door 9 and the vertical section 12 is 500 mm; the included angle is 45°.

[0018] When the bypass flue ash conveying channel 10 is not installed on the bypass flue inlet horizontal flue 8, under the high-load condition of the unit, when the bypass flue damper door 9 is closed, a "dead zone" will be formed in the bypass flue inlet horizontal flue 8, resulting in serious ash accumulation in this area of the flue. In the present invention, the ash-containing flue gas will flow back into the boiler furnace outlet flue 2 through the bypass flue ash conveying channel 10, avoiding the problems of ash accumulation in the bypass flue inlet horizontal flue 8 and mechanical jamming of the damper door, and also avoiding the problems of local overheating of the flue gas under high load and the flue gas temperature not meeting the requirements for SCR operation under low load.

[0019] In the present invention, when the main baffle door 5 is opened and the flue gas leaves the boiler furnace 1, it successively passes through the boiler furnace outlet flue 2, the low-temperature superheater 3, the boiler economizer 4, and then enters the SCR denitration reactor 6. When the unit is operating at low load, the bypass flue baffle door 9 is opened, and the high-temperature boiler flue gas enters the boiler bypass flue 7 after passing through the bypass flue inlet horizontal flue 8, and after flowing out, it converges with the main flue gas at the outlet of the economizer in the SCR denitration reactor 6. When the unit is operating at high load, the bypass flue baffle door 9 is closed, and the boiler furnace outlet flue 2, the bypass flue inlet horizontal flue 8, and the bypass flue ash conveying channel 10 form a flow-through channel, avoiding ash accumulation in the bypass flue inlet horizontal flue 8.

[0020] Figure 3 In the figure, the arrow indicates the conveying direction of the ash-containing flue gas.

[0021] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed rights.

[0022] In addition, it should be understood that although this specification is described in terms of embodiments, not every embodiment contains only one independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An apparatus for preventing ash accumulation in the horizontal section at the inlet of the bypass flue of a coal-fired boiler economizer, which comprises a boiler furnace. The boiler furnace is sequentially connected to a low-temperature superheater, a boiler economizer, and an SCR denitration reactor after passing through a boiler furnace outlet flue. A boiler bypass flue is provided between the outlet of the boiler furnace outlet flue and the inlet of the SCR denitration reactor. A bypass flue damper door is installed at the inlet of the boiler bypass flue. It is characterized in that: The bypass flue gas damper door is arranged on the horizontal flue at the inlet of the bypass flue of the boiler. A connected bypass flue ash conveying channel is arranged between the horizontal flue at the inlet of the bypass flue before the bypass flue gas damper door and the flue at the outlet of the boiler furnace; the bypass flue ash conveying channel is divided into a vertical section and an arc section. The vertical section is connected to the horizontal flue at the inlet of the bypass flue, and the arc section is connected to the flue at the outlet of the boiler furnace; the widths of the two connection ports on the bypass flue ash conveying channel connected to the horizontal flue at the inlet of the bypass flue and the flue at the outlet of the boiler furnace are both 500 mm - 800 mm; the distance between the bypass flue gas damper door and the vertical section is not greater than 500 mm; the included angle between the outer wall of the arc section and the outer wall of the flue at the outlet of the boiler furnace is not greater than 45°.

2. An apparatus for preventing ash accumulation in the horizontal section at the inlet of the bypass flue of a coal economizer in a coal-fired boiler, characterized in that: A main damper door is installed on the connecting flue between the economizer and the SCR denitration reactor of the boiler.

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