The Research Of Dry Gas Seal On The Balance Drum Of Compressor

The work efficiency, operational life of the thrust bearing and the operational reliability of the whole compressor system are directly affected by sealing performance of the seal on balance drum of the compressor. By reducing the leakage rate of the seal on the balance drum, the power cost and axial direction load could be decreased; the operational life of the thrust bearing and the work efficiency of the compressor could be notably increased. Comparing with the traditional labyrinth seal, the dry gas seal has lower leakage rate, better wearing performance, longer operational life and bigger radial direction allowed move whose leakage rate is 1/50-1/100 of the one of labyrinth seal. Accordingly there will be important engineering significance to increase the efficiency and the reliability of compressor by researching the possibility of application of dry gas seal on the balance drum and exploring the improving scheme for the seal on the balance drum.The main researching work in this paper as follows:1. By establishing the finite element model of film between sealing faces and using the finite element method, the numerical analysis of static characteristic of dry gas seal on the compressor's balance drum is done.2. The finite element numerical analysis program is written by Matlab software to solve for static film pressure differential equation between sealing faces and to calculate the static characteristic parameters of the dry gas seal.3. The effect of waves, taper and static deflection of the sealing faces has been analyzed.4. According to the advantage of wave and taper on the sealing faces, six kinds of improving schemes for the sealing face structure of common dry gas seal are presented hoping to find more suitable sealing face structures for dry gas seal on the compressor's balance drum. By analyzing the six kinds of improving schemes, four of them are feasible as follows:"wave-spiral groove dry gas seal", "static ring with positive taper spiral groove dry gas seal", "wave-taper complex spiral groove dry gas seal", and "dynamic-static complex dry gas seal".5. The sealing characteristics of dry gas seal on the compressor's balance drum during the starting program are analyzed. The criteria evaluations for comparing the starting performances of sealing face are established, such as "just-lift-off critical whirling speed". The change of the sealing performance parameters during the starting and stopping process, such as gas film thickness, opening force, leakage rate, friction work and frictional torsional moment, with the rotate speed are analyzed. The influences of operational pressure and structural parameters, such as taper, breadth rate of dam zone, depth of dynamic pressure groove, number of dynamic pressure groove and spiral angle, on the starting and stopping performance of dry gas seal are studied.