Process synthesis of intensified extractive distillation for recycling organics material from wastewater

Acetonitrile and 1,4-dioxane are significant organic compounds, which are widely used in many chemical production processes. However, some pharmaceutical or chemical factories discharge large amounts of organic wastewater containing acetonitrile and 1,4-dioxane. For dealing with this special multi-azeotrope system, it is necessary to design a dehydration extractive distillation separation scheme. Thus, an extractive distillation process with dehydration column (BFED) and an innovative extractive distillation process with an integrated column (CTED) which can function as dehydration column and extractant recovery column were proposed. For the sake of reducing energy consumption, three improved processes with direct steam injection, heat integration and heat pump were exploited. The proposed processes are comprehensively evaluated by total energy consumption and economic demand, CO2 emissions and exergy analysis. As a result, the heat pump assisted CTED process can reduce 26.86% of the total annual cost, 40.61% of energy consumption, 40.71% of CO2 emission and 44.82% of exergy destruction, respectively, compared with the BFED process.