This paper presents a new mixed-integer linear model for the planning of heat-exchanger cleaning in chemical plants. The model maximizes the net present value based on the cost of cleaning and the cost of energy and takes into account changes in production rates and even changes in the properties and flows of the different streams throughout time. This is important for the case of petroleum distillation in refineries that process different types of crudes. The model is multiperiod and uses two different fouling models.