Multiperiod investment models for the gradual reconstruction of chemical processesNovak-Pintarič, Zorka (Avtor) Kravanja, Zdravko (Avtor) chemical processingprocess designprocess retrofitinvestmentmodelingprocessingtechno-economic criteriaA multiperiod mixed-integer nonlinear programming (MINLP) model is presented for planning an optimal investment policy for the gradual retrofit of chemical plants over a specified time frame. This approach can be applied when the available funds are insufficient to perform the optimal reconstruction at once. Through gradual improvements, the process progressively approaches its optimum with considerably lower requirements for new capital whilst still exhibiting an attractive increase in economic performance. In the proposed multiperiod problem for gradual retrofit, certain amounts of capital enter into the periods for the gradual increase of equipment, in order to improve the performance of the process, e.g. increase in conversion or energy recovery. This capital may arise from internal sources of the company or can be borrowed. The financial benefits resulting from the improvements at the end of the periods can be reinvested for additional reconstruction over the next periods. In this way, self-sustained capital generation for future reconstruction is achieved, and any additional funds required minimized. The objective function of the proposed problem is formulated as the net present worth of the gradually retrofitted system. This enables several techno-economic analyses to be performed. The proposed multiperiod investment strategies are illustrated by an investment planning example for the retrofit of a heat-exchanger network.20072012-05-31 11:38:45Neznano26003UDK: 54:330.142.211COBISS_ID: 11807766ISSN pri članku: 0930-7516NUK URN: URN:SI:UM:DK:GP5MDGCYsl