Targeting and design of heating utility system for offshore platform

Heating utility system is commonly used in offshore platform to provide heating requirement for heavy crude oil of high viscosity from the reservoir. Heating the oil reduces its viscosity and improves oil/water separation which eventually leads to reduced size and cost of the separator. In conventional design, heating medium is distributed to the heat exchangers in parallel configuration to provide the required heating. This design however contributes to the overdesign of heating utility system. In this paper, Process Integration approaches based on Pinch Analysis are extended to the heating utility system of offshore platform, which may be considered as a special case of the established Heat Exchange Network (HEN) synthesis problem. A revised graphical targeting technique is proposed, which allows the identification of optimum heating medium requirement that fulfils both minimum flowrate and total cost solutions. The latter includes capital and operating costs trade-off between HEN and the waste heat recovery unit (WHRU). The configuration of the heating utility system is designed using a revised Nearest Neighbour Algorithm (NNA) proposed in this work. Literature example and an industrial case study are used to elucidate the proposed approaches.