Application of process integration methods to retrofit design for Polish sugar factories

The total annual consumption of primary energy in the Polish sugar industry is of the order of 800,000 tonnes of coal equivalent (29,300 kJ/kg). The a verage specific energy consumption is about 330 kWh/t beet processed and th e level of atmospheric emissions accompanying energy generation is higher t han that substantiated by the state of development of sugar technology. A 26% reduction in specific energy consumption was achieved in the period 1 990-1997, and the trend towards energy saving is now being continued. The d esign of technical improvements aimed at energy reduction should therefore be preceded by the determination of realistic targets that correspond to a trade-off between the value of attainable energy saving and the cost of nec essary investment. The setting of targets can be augmented by process integ ration methods and in particular by "Pinch" analysis. The needs of the Poli sh sugar industry were addressed by a project carried out under the PHARE M ulti-country Energy Program. Selected staff of the BUTiH engineering compan y and cooperating university staff were trained on the use of process integ ration methods. By combining UMIST expertise and the experience of Polish s taff in engineering work for the sugar industry, it was possible to develop a retrofit design methodology that proved to be effective in solving probl ems characteristic of sugar factories. This has been demonstrated by two in dustrial cases analyzed in the framework of the PHARE project. A technical design was developed for the retrofit of the thermal system inc luding evaporation station and heat exchanger network, in a factory process ing 4300 t/d and consuming 4.3 kg coal equivalent per 100 kg beet. The retr ofit was aimed at increasing the processing capacity to 6000 t/d. Another case involved analyzing an extensive factory reconstruction in the framework of a feasibility report. In both cases, recommendations were made on heat recovery improvements by installing additional plate heat exchange rs. The optimal value of the minimum temperatures difference was determined at 2 K.