Retrofit of Refinery Utility System by Total Site Heat Recovery: Practical Arrangements

This paper presents an optimisation of heat recovery of refinery site, a setting of utility targets of heating and cooling and indirect heat transfer between industrial clusters. The methodology provides the minimisation of capital cost of utility system retrofit. The optimisation of cost parameters connected with the heat transfer area of steam boilers and heaters, intermediate utility levels and a number of units. A method for calculation of a heat transfer area of intermediate utility heat exchangers is proposed. Minimum temperature approach of Total Site heat recovery is analysed and the number of steam mains, indirect heating loops, heat transfer area of boilers and condensers is calculated. The utility consumption,numbers of required units and material of equipment are analysed to optimise the retrofit investments. The case study shows optimal heat recovery of the refinery site of 1.94 MW. It reduces the consumption of middle-pressure steam by 37.3%, the cooling heat capacity is lowered by 39.6%. The investments of a retrofit project are paid back in 11.96 months.