压缩机外文文献

Chemical and Petroleum Engineering,Vol. 40,Nos. 9–10,2004

MODELING METHODS FOR PERFECTING

SEALING UNITS OF PISTON COMPRESSORS

AT THE DESIGN STAGE

I. K. Prilutskii,1D. N. Ivanov,1

E. I. Zamolotskaya,1A. N. Bessonnyi,2

and A. I. Prilutskii2

Efficiency,reliability,and operating life of piston compressors depend on the perfection of designs of their con-stituent units,distinctive amongst which are seals of pistons and glands operating with high and time-variable pressure dif-ferentials.

Sealing units must meet two basic requirements:

leak-tightness,which is defined by the permissible (safe) degree of gas leakage through the sealing unit under thecompressor stage operating conditions set at the design stage; and

operating life,which is characterized by the continuation of operation of the sealing unit with no change in thetechnical parameters of the compressor stage (efficiency,power consumed,temperature,etc.) at the level asdemanded by the operating conditions.

The leak-tightness of the seal with conventional split or ganged piston rings at a known maximum pressure differen-tial pon the sealing unit depends on a host of design parameters:number of rings zrand their cross-sectional area brhr,inter-ring spaces that depend on the dimensions of the pieces connecting the rings or on the ring spacing tr,radial clearance in thepiston–cylinderpair δp-c,running clearance in the ring lock l,presence or absence of lubricant,etc. To a first approximation,the required number of rings in the sealing unit of the piston can be determined by the proposed empirical relationship

√ 5 p≤(zr– 1) ≤√ 10 p.(1)

The operating life of the sealing unit depends on the materials of the piston–cylinderfriction pair,speed of motionof the piston,roughness of the contact surfaces of the friction elements,cooling conditions,overall pressure differential pin the seal as well as on the pressure distribution across the elements of the sealing unit. In medium- and high-pressure stages,the last of the referred factors determine to a large measure the rate of wear of the piston rings and the scheduled time fortheir replacement.

In special-purpose compressors with one-way acting (unidirectional) pistons,the overall pressure differential in thesealing unit of high-pressure stages attains 20–40 MPa,which,in accord with Eq. (1),increases the number of sealing ringsto be installed on the piston to 11 ≤zr≤21 and,consequently,increases the axial dimensions of the cylinders.

Experience of designing,computational analysis,experimental studies [1–3],and industrial use of sealing units ofdomestic piston compressors shows that excessive increase in the number of sealing rings does not reduce external leakingmuch and does not facilitate uniform distribution of pressure across the rings of the sealing unit.

Translated from Khimicheskoe i Neftegazovoe Mashinostroenie,No. 9,pp. 27–30,September,2004.

0009-2355/04/0910-0545©2004 Springer Science+Business Media,Inc.

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