Feasibility exploration of strain-based indicator diagram reconstruction for reciprocating compressor fault diagnosis

Abstract

Reciprocating compressor is an indispensable and important production equipment in petrochemical industry. However, due to the large number of vulnerable components, thermal performance failures occur frequently. Indicator diagram has significant advantages in the diagnosis of those thermal performance failures and is therefore regarded as a reliable fault diagnosis technique for reciprocating compressor. Nevertheless, the indicator diagram needs to extract the pressure and piston position information in the cylinder, which has greatly hindered its practical application. The traditional way of extracting the pressure information may damage the cylinder wall, and the obtaining of the piston position requires key-phase sensor, both of which pose potential safety hazards. In this paper, a novel idea of obtaining cylinder pressure and piston position at the same time through cylinder strain is developed, and the feasibility of the proposed idea is verified by numerical simulation. During the simulation, this work employs ANSYS tool to extract the strain from the outer wall of the cylinder as a way of revealing the relationship between pressure and strain, and piston position and strain. Subsequently, the strain-based indicator diagram is reconstructed through the change of the strain at a certain point on the outer wall of the cylinder in a working cycle. The simulation results show that the cylinder strain can reflect cylinder internal pressure and piston position obviously, and it is feasible to construct an indicator diagram based on cylinder strain.