Developments in Dry Running Seals for Reciprocating Compressors

Reciprocating compressors of the crosshead design have sealing elements around the piston and piston rod. These seals can be of lubricated or nonlubricated design. This paper will give details about our R&D-work for dry running piston rod sealings or packings for high pressure applications. Starting with an overview of packing design some details are given about tribological tests. Measurements within packings give informations about the physics in this special dry running sealing element. Calculations of temperatures in the contact area between a dry running sealing ring and piston rod point to the main problem to be solved: The energy input due to friction. A new sealing ring design for packings is presented. Whith this new development we are able to seal a pressure difference of 100 bar across the packing and achieve a sufficiently long life. INTRODUCTION TO THE PACKING DESIGN Reciprocating compressors of the crosshead design must be sealed at piston and piston rod. These seals can be of lubricated or nonlubricated design. In the early 90's we started a R&D-project to develop dry running seals for high pressure applications. This paper will give details about our development work, especially for dry running piston rod sealings or packings. Various styles of packing rings are known (Fig. 1). A standard ring for low pressure differences is the six piece, tangentthree piece, radial cut :t1elili!wtl!l:l.J!IJI!iljitf;;( I three piece, penguin style six piece, tangential cut >;P4"fiUN'i!.ili®f!tl I four piece, unequal segments three piece, tangential-to the-rod a<;ilJ•·•;,gta.§w:wr.:>,:l:rlfE I one piece, radial cut with outer cover ring Fig. 1: Various styles of packing rings