Research On The Influences Between Flexible Sealing Structure Parameter And Fatigue Life For Air Preheater

Rotary air preheater is one of the important energy-saving equipment plant in power plant. It plays a vital role in keeping the unit safety and economical operating, but ti also has some problems. For example,the problem of excessive air leakage rate. Leakage rate is too large will produce a series of negative impact on the normal operation of the air preheater, although it can not be completely eliminated but must be curbed. Leakage problems generated depends on the seal gap, the rotor "mushroom-shaped" deformation,the gas pressure too large and other factors, So from the above perspective to reduce the air preheater leakage is effective. Contact flexible seal can effectively reduce the gap between the rotor and the air preheater sector plates, when the “mushroom-like” deformation due to its own bending characteristics closing the sector plate. Reaching zero gap sealing effect basically, is an effective way to reduce the amount of air leakage.Since the flexible seal in the actual work environment in which relatively poor, and changing the sealing sheet will force the unit to shutdown, influencing its normal operation. Therefore, improving the fatigue life of the flexible seal is helpful to efficiency of the actual operation in the power plant. This article uses finite element analysis software to stimulate studies for flexible contact fatigue life of different structural parameters(wave, wave number, thickness, wave depth, pitch, initial elongation and AOA) to compare and integrate the result of fatigue life results in different parameters, concluded a set of the longest fatigue life contact flexible seals parameter size. Found in the maximum stresses and node stimulation process, different structural parameters will certainly affect the size of maximum stress difference.However, the occurrence of stress concentration points are close to the first stage of the corrugated in the seal sheet roots, this position occurs the fatigue damage. Therefore, we can properly thicken the first stage thickness in the manufacture of the sealing sheet, or make the appropriate chansfering on the first stage ripple would play a role in mitigation about stress concentration problems.After calculation, flexible sealing sheet with the wave “U” shape, wave number of 5, thickness of3 mm, the pitch of 4mm, deep wave 8mm, the initial elongation of 8mm, the angle of attack of 60°has the longest fatigue. Contrast with simulation and experimental study of the sealing sheet thickness by predecessors can be found that the life of 2mm sealing sheet for eight years, the conclusion is same and accurate. But this article considers the probability of fatigue life and preventing damage, the fatigue life of the sealing sheet by 1 years, but also reduce the probability of accidental damage to the sealing sheet occurs in practice, such as large pieces of ash falling cuts the flexible seal. However, the actual production considers the production cost of the flexible sealing sheet, a rough estimate of the production of 2.5mm thickness sealing sheet costs about two-thirds of 3mm thickness, improving the life one year in case of accidental breakage does not occur, therefore, a reasonable choice of the size thickness of the flexible seal has practical significance.