COMPLEX THERMAL INTEGRATION OF THE RECTIFICATION PROCESS USING THERMAL COMPRESSION

Abstract

The rectification process is widespread in many industries and requires significant energy consumption. The search for technological schemes of the rectification process, which ensures the maximum reduction of energy consumption, is arelevant task.
 One of the modern approaches to the design of technological schemes aimed at ensuring resource and energy saving is pinch analysis. In this work, it was decided to apply the methods of pinch analysis and heat pump (thermocompression) for complex thermal integration of the methanol-water mixture rectification process.
 On the basis of the material and heat balance of the rectification column the characteristics of the main technological flows of the methanol-water mixture rectification process were calculated: their consumption, temperatures, specific heat capacity, flow heat capacity, and enthalpy change (heat load). A flow table has been created. Composite process curves for the minimum temperature difference DТmin were constructed, the pinch point and the minimum power values of hot and cold utilities were determined. Based on the calculated data, a grid diagram was constructed and heat exchangers were located in accordance with the pinch rules, which allows to achieve the maximum heat recovery that corresponds to the selected DТmin.
 For the use of a heat pump (thermocompression), the required degree of steam compression in the P2/P1 compressor was calculated. It was chosen taking into account the necessary steam temperature, which is sufficient for heating the cube of the column. Based on these calculations a technological diagram of the methanol-water rectification process with a heat pump (thermocompression) and thermal integration of the main technological flows was developed. Such a scheme provides a significant saving of hot and cold utilities in comparison with carrying out the process of rectification of the methanol-water mixture according to the principle technological scheme.