Abstract
The oil refining industry accounts for 6 to 8% of global industrial energy consumption, and reducing this share remains one of the priority tasks for the sector. The present work is devoted to investigating the enhancement of the energy efficiency of the heat exchanger network of a delayed coking unit (DCU) with a throughput of 1 million tonnes per year. The pinch analysis method was applied to examine the existing scheme and to develop technical solutions. Process simulation was performed in Aspen HYSYS v12.1 using actual laboratory data from an operating refinery. The analysis identified the key issue, namely a temperature cross on the heat exchangers, whereby effective heat transfer between the hot and cold streams is virtually absent. On the basis of the pinch analysis results, a new piping configuration was developed for the second pump-around circuit, with the heat exchangers connected in series. Implementation of the proposed reconfiguration delivers a 40% increase in the thermal duty of the feed preheating section. No additional heat exchange equipment is required. In addition to the energy gain, the solution improves the operating conditions of the main fractionating column and contributes to a reduction in CO2 emissions.