Simulation And Experimental Study Of Purification Of Low Concentration Formic Acid Aqueous Solution By Batch Azeotropic Distillation

Formic acid is widely used in the production of medicine and perfume, as well as the acid treatment of textiles and leathers. However, in these processes, a lot of low-concentration formic acid can be generated without any value. The low-concentration formic acid that is to be recycled and concentrated can not only reduce environmental pollution, but also create considerable economic value.At atmospheric pressure, formic acid and water form azeotrope, which can't be effectively separated by conventional distillation. As a result, the method of heterogeneous azeotropic distillation under different pressure is used to concentrate the low concentration formic acid aqueous solution.Firstly, suitable entrainers are preliminary screened by the triangular phase diagram, then the simulation in which CHEMCAD is applied to compare the yield of formic acid, concentration degree and energy consumption with different entrainers, toluene and 1,2-dichloroethane are determined to be the entrainers of the formic acid heterogeneous azeotropic distillation.According to the particularity of the formic acid concentration, 2 plans are determined, which are the formic acid is concentrated to the degree of approaching azeotropic mass ratio by azeotropic distillation with toluene and 1,2-dichloroethane as entrainer separately on the first step, then the conventional distillation is applied to do the secondary concentration until the product meet the requirements.CHEMCAD is used to simulate the process of concentration. By optimizing parameters and analyzing the influence of the reflux ratio, theoretical plate number and amount of entrainer on yield and concentration degree of formic acid, we get the concentration profile curves, the temperature profile curves and the vapor/liquid flow profile of the column.The batch heterogeneous azeotropic distillation is done to compare the different of the formic acid yield and concentration with toluene and 1,2-dichloroethane as entrainer respectively. Meanwhile, the experiment result is also compared with the simulation value, which is in substantial agreement.