A step toward saving energy using thermal modification of crude oil preheat network: A case study

• The preheat system of the crude distillation unit at an oil refinery is investigated.
• A simulation software is applied to propose an improved heat exchanger network.
• The proposed design is compared with existing design and investigated economically.
• 4.6 MW energy saving and 17 °C rise in exiting temperature are achieved.
• The period of return on investment for the proposed design is about 9 months.

This paper presents a thermal and economic investigation of a heat exchanger network of a crude distillation unit in its existing configuration, with the aim of increasing the temperature of crude exiting the network and enhances its performance thermally. In the existing system, the crude enters to the preheat network at the temperature of 30 °C and leaves at 188 °C, being heated passing through a combination of nine shell and tube heat exchangers. However, achieving higher temperature is essential due to the extraordinary industrial importance in energy saving. For this purpose, the possibility of higher preheat temperature is investigated, using a computer software analysis, and a new configuration is proposed according to the simulation results. The proposed configuration is also compared with the existing configuration from an economic point of view. Simulation results prove that implementing certain modifications on the existing design reduces the consumption of utilities and upgrades the performance of the whole process in such a way that a 17 °C rise in temperature of the outgoing crude is achieved. Moreover, a heat recovery boost equal to 4.6 MW is obtained from hot streams using the proposed design. Eventually, the proposed configuration can lead to an improvement of overall process economics. The period of return on investment for the proposed design is about 9 months, proving to be cost effective.