A multi-rib protective pipe sleeve

Abstract

The present invention discloses a multi-rib protective pipe sleeve, comprising a base pipe, a sleeve and a plurality of fins, wherein the sleeve is a semicircular pipe, wherein the sleeve is buckled on the outer wall of the base pipe, and each fin is arranged on the outer wall of the sleeve. The sleeve can alleviate the current situation of heat exchange tube being worn, greatly improve the wear resistance of the heat exchange tube, and has simple equipment, short construction period and low investment cost.

Description

Technical Field

[0001] The invention belongs to the technical field of heat exchange tube protection and relates to a multi-rib protective tube sleeve. Background Art

[0002] The boiler is a device composed of heat exchange tubes. Therefore, the safety of the heat exchange tubes has a great impact on the overall safety and economy of the boiler. Heat exchange tubes in different parts have different failure modes. The main reason for the failure of the tail heat exchange tube is wear due to low flue gas temperature, uneven flow field, large ash content, and strong wear capacity of ash. Wear can easily lead to leakage of heat exchange tubes, and leakage leads to sticky ash accumulation, which disrupts the flue gas flow field, aggravates wear, and creates a vicious cycle. According to different causes of wear, targeted methods can be taken to solve the wear well. In many cases, wear is caused by uneven flue gas flow field. The hardest hit areas of wear are concentrated in the first two rows of the heat exchanger, and the subsequent tube rows have a lower risk of wear. Therefore, improving the wear resistance of the first two rows of heat exchange tubes is crucial to improving the overall life of the heat exchanger.

[0003] The main methods to improve the wear resistance of heat exchange tubes are to increase the wall thickness of the heat exchange tubes and add protective sleeves. For heat exchangers that have been put into operation, the cost of increasing the wall thickness of the heat exchange tubes is high. Adding anti-wear sleeves to the heat exchange tubes in the wear-prone area is a better choice. The current mainstream anti-wear sleeves are semi-circular sleeves, which are used to increase the wall thickness of the heat exchange tubes on the windward side. Although the investment is not large, it does not change the wear condition of the heat exchanger, but only delays the time of wear and leakage. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a multi-rib protective pipe sleeve, which can alleviate the wear of the heat exchange tube and greatly improve the wear resistance of the heat exchange tube. The equipment is simple, the construction period is short, and the investment cost is low.

[0005] To achieve the above-mentioned purpose, the multi-rib protective pipe sleeve described in the present invention includes a base pipe, a sleeve and a plurality of ribs, wherein the sleeve is a semicircular tube, wherein the sleeve is buckled on the outer wall of the base pipe, and each rib is arranged on the outer wall of the sleeve.

[0006] The fins are evenly distributed on the outer wall of the sleeve.

[0007] The wall thickness of the casing is 60% of the base pipe wall thickness.

[0008] When the thickness n+1mm of the base tube is greater than or equal to 6mm, the thickness of the fin is n+1mm; when the thickness n+1mm of the base tube is less than 6mm, the thickness of the fin is 6mm.

[0009] The axis of each fin passes through the axis of the base tube. Assume that the angle between the axes of two adjacent fins is α, the length of the fin is L, and the number of the fins is W.

[0010] The determination process of α, L and W is:

[0011] Perform vertical simulation on the flow field of the heat exchanger to determine the flue gas scouring angle of the first row of heat exchange tubes at the heat exchanger inlet, that is, the angle between the flue gas flow direction and the center line of the flue;

[0012] When the RMS velocity σ of the flue gas flow in the cross-sectional direction of the first row of heat exchange tubes at the heat exchanger inlet is ≤5%, the number of fins W is 3, the direction of the middle fin is parallel to the flue gas flow direction, α = 45°, L = r + δ = r * arcsin α - r, where r is the radius of the base tube, δ is the thickness of the casing, and α = 45°;

[0013] When the RMS velocity σ of the flue gas flow in the cross-sectional direction of the first row of heat exchange tubes at the heat exchanger inlet satisfies 5%≤σ≤10%, the number of fins W is 5, the direction of the middle fin is parallel to the flue gas flow direction, α=30°, L==r+δ=r*arcsin2α-r, where α=30°;

[0014] When the root mean square velocity σ of the flue gas flow in the cross-sectional direction of the first row of heat exchange tubes at the heat exchanger inlet is ≥10%, the flow field of the heat exchanger is re-simulated vertically.

[0015] The present invention has the following beneficial effects:

[0016] During the specific operation of the multi-ribbed protective sleeve described in the present invention, the flue gas will cause wear when scouring the base pipe. According to operating experience, the impact range of wear is within 60°, the most serious wear is around 45°, and the wear is most likely to occur in the first two rows. When the flue gas flow field is uneven, the flue gas flow angle changes. Therefore, the protection of the heat exchange tube must first determine the flue gas flow angle. After determining the flue gas flow angle by numerical simulation, the protective sleeve can be arranged accordingly. In the present invention, the sleeve is buckled on the outer wall of the base pipe, and each rib is arranged on the outer wall of the sleeve. The number of ribs can be adjusted according to the root mean square velocity of the flue gas to alleviate the current situation of wear of the heat exchange tube, greatly improving the wear resistance of the heat exchange tube. The equipment is simple, the construction period is short, and the investment cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic structural diagram of the present invention when the number of fins 1 is 3;

[0018] Figure 2 It is a schematic structural diagram of the present invention when the number of fins 1 is 5.

[0019] Among them, 1 is a fin, 2 is a casing, and 3 is a base pipe. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0021] refer to Figure 1 and Figure 2 The multi-rib protective pipe sleeve described in the present invention includes a base pipe 3, a sleeve 2 and a plurality of ribs 1, wherein the sleeve 2 is a semicircular tube, wherein the sleeve 2 is buckled on the outer wall of the base pipe 3, and each rib 1 is arranged on the outer wall of the sleeve 2.

[0022] The fins 1 are evenly distributed on the outer wall of the sleeve 2; the wall thickness of the sleeve 2 is 60% of the wall thickness of the base tube 3; when the thickness n+1mm of the base tube 3 is greater than or equal to 6mm, the thickness of the fin 1 is n+1mm, and when the thickness n+1mm of the base tube 3 is less than 6mm, the thickness of the fin 1 is 6mm.

[0023] The axis of each fin 1 passes through the axis of the base tube 3. Assuming that the angle between the axes of two adjacent fins 1 is α, the length of the fin 1 is L, and the number of the fins 1 is W, the determination process of α, L and W is:

[0024] Perform vertical simulation on the flow field of the heat exchanger to determine the flue gas scouring angle of the first row of heat exchange tubes at the heat exchanger inlet, that is, the angle between the flue gas flow direction and the center line of the flue;

[0025] When the RMS velocity σ of the flue gas flow in the cross-sectional direction of the first row of heat exchange tubes at the heat exchanger inlet is ≤5%, the number of fins 1 W is 3, the direction of the middle fin 1 is parallel to the flue gas flow direction, α = 45°, L = r + δ = r * arcsin α - r, where r is the radius of the base tube 3, δ is the thickness of the casing 2, and α = 45°;

[0026] When the RMS velocity σ of the flue gas flow in the cross-sectional direction of the first row of heat exchange tubes at the heat exchanger inlet satisfies 5%≤σ≤10%, the number of fins 1 W is 5, the direction of the middle fin 1 is parallel to the flue gas flow direction, α=30°, L==r+δ=r*arcsin2α-r, where α=30°;

[0027] When the root mean square velocity σ of the flue gas flow in the cross-sectional direction of the first row of heat exchange tubes at the heat exchanger inlet is ≥10%, the flow field of the heat exchanger is re-simulated vertically.

[0028] The specific working process of the present invention is:

[0029] When flue gas scours the base pipe 3, it will cause wear. According to operating experience, the impact range of wear is within 60°, the most serious wear is around 45°, and wear is most likely to occur in the first two rows. When the flue gas flow field is uneven, the flue gas flow angle changes. Therefore, the protection of the heat exchange tube must first determine the flue gas flow angle. After the flue gas flow angle is determined by numerical simulation, the protective sleeve 2 can be arranged accordingly. When the flue gas velocity root mean square σ≤5%, it means that the flue gas flow field is uniform. At this time, the number of fins 1 of the designed protective sleeve 2 is 3, the direction of the middle fin 1 is parallel to the flue gas flow direction, and the angle α between the two adjacent fins 1 is 45°. When the flue gas flows toward the heat exchange tube, due to the presence of the fins 1, the fly ash in the flue gas is diverted to both sides when it hits the sleeve 2, which minimizes the wear of the fly ash on the sleeve 2. When the root mean square velocity of the incoming flue gas is 5%≤σ≤10%, it means that the uniformity of the flue gas flow field is general. At this time, it is necessary to increase the protective performance of the protective sleeve 2, increase the number of fins 1 to 5, and increase the protection angle of the fin 1 to 60°. When the root mean square velocity of the incoming flue gas is σ≥10%, it means that the uniformity of the flue gas flow field is poor. In this case, the guide plate should be redesigned so that σ≤10%.

Claims

1. A multi-rib protective sleeve, characterized in that: It comprises a base tube (3), a sleeve (2) and a plurality of fins (1), wherein the sleeve (2) is a semicircular tube, wherein the sleeve (2) is buckled on the outer wall of the base tube (3), and each fin (1) is arranged on the outer wall of the sleeve (2); The axis of each fin (1) passes through the axis of the base tube (3), the angle between the axes of two adjacent fins (1) is α, the length of the fin (1) is L, and the number of the fins (1) is W; The determination process of α, L and W is: Perform vertical simulation on the flow field of the heat exchanger to determine the flue gas scouring angle of the first row of heat exchange tubes at the heat exchanger inlet, that is, the angle between the flue gas flow direction and the center line of the flue; When the root mean square velocity σ of the flue gas flow in the cross-sectional direction of the first row of heat exchange tubes at the heat exchanger inlet is ≤5%, the number W of the fins (1) is 3, the direction of the middle fins (1) is parallel to the flue gas flow direction, α=45°, L=r+δ=r*arcsinα-r, wherein r is the radius of the base tube (3), δ is the thickness of the casing (2), and α=45°; When the root mean square velocity σ of the flue gas flow in the direction of the cross section of the first row of heat exchange tubes at the heat exchanger inlet satisfies 5%≤σ≤10%, the number W of the fins (1) is 5, the direction of the middle fins (1) is parallel to the flue gas flow direction, α=30°, L==r+δ=r*arcsin2α-r, where α=30°; When the root mean square velocity σ of the flue gas flow in the cross-sectional direction of the first row of heat exchange tubes at the heat exchanger inlet is ≥10%, the flow field of the heat exchanger is re-simulated vertically.

2. The multi-rib protective sleeve according to claim 1, characterized in that: The fins (1) are evenly distributed on the outer wall of the sleeve (2).

3. The multi-rib protective sleeve according to claim 1, characterized in that: The wall thickness of the casing (2) is 60% of the wall thickness of the base pipe (3).

4. The multi-rib protective sleeve according to claim 1, characterized in that: When the thickness n+1mm of the base tube (3) is greater than or equal to 6mm, the thickness of the fin (1) is n+1mm; when the thickness n+1mm of the base tube (3) is less than 6mm, the thickness of the fin (1) is 6mm.

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