Energy efficiency improvement in an ethylene plant propylene refrigeration cycle (C3R)

Abstract

A typical refrigeration cycle in an ethylene plant utilizes propene as fluid. When C3R is still in the warm zone, there is some process heat exchangers that leave it sub-cooled. This creates the opportunity for operational improvement in these systems which will result in less parasite steam formation on cycle expansion zone. The objective is analyze this energy efficiency improvement opportunity, showing the financial and energy earnings. The methodology applied to achieve this improvement in the energy efficiency of this cycle is based on: mass and energy balance calculation, design data comparison, and analysis of differences between the actual values and the design reference. An action plan was developed with necessary implementation steps and earnings calculations. The annual amount realized was around one million dollars in 2015. In terms of natural resources, this work is bringing an average reduction of 1.07 kg/s of steam, representing an amount of approximately 2.12 MW. This gain is about 2% of the turbine consumption. This framework can be applied at any Ethylene plant that has the similar equipments.