PINCH-INTEGRATIONAL OPTIMIZATION OF HEAT EXCHANGE NETWORK OF THE HYDROLYTIC SULFURIC ACID CONCENTRATION PROCESS

The paper considers the question of the possibility of thermal energy saving at an industrial enterprise. As a means of optimizing energy consumption, one of the methods for integrating chemical-technological processes, pinch analysis, was used. It has been established that the problems of significant energy consumption are relevant for researchers and industrialists around the world, and scientists see their solution primarily in the development of alternative energy sources and modern methods of energy saving with well-predictable results. It is indicated that the target functions in this case can be combined: financial-energy and energy-environmental, since exactly these kinds of results are provided by the very essence of energy-and-resources saving applied to the industrial process. At the initial stage of the study, an analysis of thermal energy consumption structure provided by apparatuses in hydrolytic sulfuric acid concentration process was made. Based on its results, it was found that the existing minimum temperature difference in the system is far from the optimal and technically achievable value. Taking into account the confirmed energy-saving potential, its value was estimated. For this, the value of the present heat recovery in the system is established through calculation, and the volume of energy coming from external heat carriers and refrigerants is determined. Based on the calculation results, a Grid diagram and Composite curves of the specified technological process were constructed. At the second stage, optimization measures, which began with the choice of a new, lower value of the minimum temperature difference for the entire heat exchange network of this industrial plant, were carried out. For this value, shifted composite curves were constructed and an updated grid diagram was developed. In the integrated heat exchange network, there is three additional recuperative heat exchanger and were revised the operating modes of devices that it was decided to save. Based on the optimization results, a technological scheme of the hydrolytic sulfuric acid concentration process was designed while maintaining the key elements of the production technology. The result of the work is an optimized heat exchange network of the industrial enterprise section, which makes it possible to increase the thermal energy recuperation by 32,7 %, while reducing the consumption of external heat carriers by 30,3 %, as well as external refrigerants – by 50,1 %. The results obtained indicate a very high economic efficiency and a prospects of implementation the project into production.