Efficiency of Using Heat Pumps in the Extractive Rectification of an Allyl Alcohol–Allyl Acetate Mixture Depending on the Composition of the Feed. Part 2. Application of Heat Pumps in Column Complexes with Partially Coupled Heat and Material Flows

Abstract

The efficiency of using heat pumps in extractive rectification schemes with partially coupled heat and material flows is studied on the example of separating an allylic alcohol–allyl acetate mixture of various initial compositions with n-butylpropionate as a separating agent. A comparison of schemes with heat pumps and schemes with a traditional two-column scheme of extractive rectification is carried out according to the criteria of reduced energy costs and total annual costs. It is established that with increasing concentration of allylic alcohol in the feed, the energy and economic efficiency of the scheme with a heat pump on the main column of the complex with partially coupled heat and material flows increases. The energy efficiency of the side-section heat-pump circuit decreases with increasing allylic alcohol content in the feed, and the economic efficiency of this circuit increases slightly. The energy efficiency of the scheme in which heat pumps are simultaneously used on the main column and on the side section depends little on the composition of the feed, while the economic efficiency of this scheme increases with increasing concentration of allylic alcohol. For all considered power compositions, the maximum savings in energy costs (by 45.9–49.1%) compared to the traditional two-column scheme is provided by the schemes in which heat pumps are simultaneously used on the main column and on the side section, and the maximum reduction in total annual costs (by 11.7–27.9% with a service life of 20 years) is achieved with the scheme with a heat pump on the main column of the complex with partially coupled heat and material flows.