Modelling of VK column reactors for manufacturing nylon-6

摘要

A stagewise model based on tanks in series approach has been proposed to elucidate the effects of backmixing in the two-phase zone of VK (Vereinfacht Kontinuerlich) column reactors. A recycle stream between tanks has been used to represent backmixing due to the vapour stream rising -coun-tercurrently to the liquid stream. The model has been used to calculate the monomer conversion, number average degree of polymerization and the polydispersity index at the end of the reactor. It has been found that increased backmixing increases the water holding capacity of the stream and, therefore, increases the conversion at the end of the two-phase zone. As water also lowers the degree of polymerization, it has been found that at the end of the reactor where equilibrium is reached, the degree of polymerization decreases with increased backmixing in the top portion of the reactor. The polydispersity index remains relatively unaffected as equilibrium is attained at the end of the reactor. If too high temperatures are used at the beginning of the reactor, the streams would contain less water and this would lead to higher degrees of polymerization but to lower rates.