A faulty dynamical interaction between a machine and a foundation can lead to unexpected and dangerous failures, impacting human lives and the environment. Some machines, as reciprocating compressors, have a low rotation speed; this can lead to dangerous frequency for the foundation blocks. For this reason, a careful analysis shall be done during the design phase to avoid the range of the frequency of resonances and low vibration speeds. Designers can approach this problem by relying both on Analytical Theory and Finite Element Analysis. This article compares these methods by studying the dynamical response of different foundation geometries in a case study of a reciprocating compressor foundation. The applicability limits of Analytical theory are explored and an evaluation of the difference in the estimation of natural frequencies of the system using Analytical Theory and Finite Elements Analysis are made for different foundation geometries. The comparison shows similar results until the foundation geometry is rigid; reference geometries limits are provided so that designers can choose which of the methods better suits their type of analysis.

A good design of hyper compressors is heavily dependent by the good understanding of all critical aspects of the LDPE plant and on the implementation of appropriate technical solutions, during the design phase, to identify and resolve problems that may arise during the operation of the plant. The various aspects have to be investigated keeping in mind to reach an optimum performance in agreement with the customer’s requirements. The real effort is starting at the first design stages where all different departments are involved for dynamic loads acting on the foundation, the torsional analysis involving the motor supplier and the pulsation/vibration considerations interfacing the engineering company, the suppliers of high pressure equipment and the end users. All the stress levels, the pulsation and vibrations have to be minimized. Such results are influenced by the layout of the plant and the arrangement of the cranks of the compressor’s crank-shaft. This latter decision can improve the pulsation level, but affect the loads on the foundations. Here is the optimization of some technical aspects to be faced with the approval of all actors involved.