The Advantages and Disadvantages of High Frequency Welded Finned Tubes

Do you know the advantages and disadvantages of high frequency welded finned tubes? We share something with you.

1. Due to process limitations, the fin spacing is large, the minimum spacing 4mm, fin outer diameter of up to 55mm, the general air cooler aluminum fin is 2.3mm fin spacing, 57mm fin outer diameter, so the finning ratio is low, the maximum is only about 13, the normal rolling or expansion of the piece is about 23, that is, the same base tube area, the fin area is small only about 55% of the aluminum fins, the heat transfer effect is limited.

2. Fins for steel or stainless steel, thicker piece, the thinnest 0.8mm, while the aluminum is 0.3 ~ 0.45mm or so, the thermal efficiency of the fins is poor, if the stainless steel fins, because the stainless steel heat transfer efficiency is worse (heat transfer efficiency of only 65% of aluminum), so the heat transfer efficiency is low.

3. High frequency welding fins, although the contact heat resistance is small, but the fin area is limited, the fins thick heat transfer is poor, so the overall thermal efficiency of the finned tube is not high. In addition to some special processes, the general situation is less used. Based on the above, high frequency welded fin tubes are not suitable for use in air coolers, except in cases where the temperature is higher than 500°C. However, based on its anti-corrosion, such as stainless steel fins - stainless steel base tube, in the application of methanol synthesis evaporative cooling, can be used, but its heat transfer efficiency is greatly reduced, only about 45% of aluminum (area of only 60% of aluminum, heat transfer efficiency of only 70% of aluminum, the total effect of 0.6 × 0.7 = 0.45), so its water-saving effect is poor.

The advantage of high frequency welded finned tubes is that the unit mass is light and the total manufacturing cost is low.

Integral finned tube has the following six advantages

1. Integral finned tube can expand the heat exchange effect (area and heat transfer coefficient). In the case of the same base tube: (for example, the base tube is φ32X3, the fin height is 10, and the fin distance is 8.5) 1 meter is equivalent to 4 meters of light tube or 2.6 meters of membrane structure (spacing 62X3, flat steel 30X3) or 1.5 meters of flat steel welded fin tube (flat steel 12X3).

2. Integral finned tube wear-resistant. Because the integral fin tube fins and base tube is one piece of molding, the crystal structure is consistent, stable performance, and the fins are dune shape, and in the heat of the temperature gradient shape, in the heat of the fins outside the surface temperature consistent, uniform thermal stress, will not produce concentration, and will not produce strength weak points, (and the main reason for wear because of high temperature points, should be σ low), in addition, the fins have the role of the flow of the flue gas In addition, the fins have the function of deflecting the flue gas, and at the same time, the indicators of the flue gas (temperature, flow rate, ash, etc.) are more uniform, so that the flue gas will not be deflected, and the flue gas will not be concentrated in a certain area or a certain part. Therefore, it is more wear-resistant.

3. The overall finned tube stiffness is greatly enhanced. The size of the stiffness depends on the size of the moment of inertia, and the moment of inertia of the integral finned tube is 4.76 times that of the corresponding light tube. (φ32X3 moment of inertia 35168mm2, while the finned tube moment of inertia 167613mm2,) bracket spacing light tube is 2.71m (3.55m old tube gauge), finned tube 5.28m (6.91m old tube gauge), if the calculated wall temperature reaches near 460 °, the bracket spacing will be reduced, so there are several rows of tubes on the coal saver in the middle of the two bracket fracture phenomenon. This phenomenon occurs when the fracture is flush. And the material is not found to be a problem.

4. The overall type finned tube does not accumulate ash. The reason for ash accumulation is caused by the Kamen vortex: when the flue gas flow through the tube, the back of the tube will form a negative pressure area, in this area, the flue gas flow rate is zero or even reflux, the flue gas will accumulate here, the ash is attached to the surface of the tube. The thermal resistance of the ash is relatively large, the thicker the ash accumulates, the greater the thermal resistance, the less heat transfer, the exhaust temperature increases, and the boiler efficiency decreases. The finned tube to the flue gas inflow to overcome the Carmen vortex, but also comb the distribution of ash, so that it is evenly distributed in the flue gas.

5. Stable heat transfer performance. One piece structure as a heating surface, in many years (no soot blowing) operation, the boiler exhaust temperature fluctuations do not change significantly, no coal boiler exhaust temperature fluctuations do not change significantly, no coal boiler tube burst phenomenon.

6. Long service life. Under the same operating conditions (coal quality, temperature, location of the heating surface), the finned tube is guaranteed to last 2 times longer than the light tube. In general, the life of the light tube is 3~4 years, while the life of the whole finned tube is at least 7~8 years.

The disadvantage of the overall finned tube is the heavy unit mass and high overall manufacturing cost.

Heat transfer division as a branch company of Group Hunan Jetvision Industrial Co., Ltd. We have grown to be a professional supplier in key customized components of Shell-tube HE.Offer one-stop service to our client,main products including tube-shell HE----like U tube, tube sheet,shell flange,baffle plate, vessel tank heads, etc.

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