THE PINCH TECHNOLOGY AND THE ENERGY REDUCTION IN THE BEET SUGAR PROCESS

The "Pinch Technology" is over twelve years old. It is a method of analysis of combined heat and power systems by an energy bottleneck or "Pinch" technique. In particular pinch technology has demonstrated that good process integration pays off through simplicity of plant design and good use of energy and capital. The principle is to predict what should be achieved (targeting) and to then set out to achieve it (design). This technique identifies the minimum process energy demand for a given value of DELTA-T, where DELTA-T is the minimum approach temperature in any heat exchanger. It is possible to determine the optimum value of DELTA-T for a given fuel cost and equipment cost. For the beet sugar process a low value was used, 5 K. Two cases of sugar factories, where the pinch technology and the process integration was applied are discussed. The 5 K difference leads to six evaporator stages using overall falling film evaporators. For a higher fuel cost, the choice of a 4 K difference leads to seven evaporator stages using again falling film evaporators. For plate heat exchangers a DELTA-T(min) of 2.5-3 K is already feasible. The use of small DELTA-T at heat exchangers or evaporators is advocated by the second law of thermodynamics.