Basic Analysis of Rectification Energy

Abstract

(1) In the schematic arrangement of the reversible rectifying column, it is desirable that it resembles the actual column as nearly as possible and yet be clearly reversible.(2) The deviation in the relationship between temperature and heat input or output of an irreversible column compared with that of a reversible column was examined. In the irreversible column m (<1) and K (positive integer) were induced as parameters of the shape of the relationship between temperature and heat input or output.(3) Fig.8 illustrates graphically how the required work is increased from a reversible column to a vaporrecompression column. This suggests that the work of compression in a vapor-recompression column can be reduced by the following mean:1) Reduction of the reflux ratio, 2) Use of a rectifying column equipped with a secondary still or a secondary condenser, or the use of successive rectifying columns, 3) Modification of the tower construction for larger heat transfer area, higher heat transfer coefficient and lower pressure drop through the column, 4) Recovery of mechanical energy from the excess vapor of the plant, 5) Improvement of the compressor efficiency.(4) Table 2 shows numerically the difference in work balance between the steam heating process and the vapor recompressin process. According to Table 2, the reflux condenser loss is recovered by the use of the vapor-recompression method. Next, in the case of the vapor-recompression process of the adiabatic column, the tower loss becomes the largest loss, and the adoption of a column equipped with a secondary still is a method which will further reduce the required work by reducing the tower loss. In the case of the vaporrecompression column epuipped with a secondary still, the still loss becomes the largest loss. Consequently, Table 2 poses questions concerning the most effective type of tower construction which reduces the still loss and hence, reduces the required work.