Study On Producing High Purity Methanol From Industrial Methanol By Purification

This paper summarized the evolution of applying and producing high purity methanol at home and abroad, discussed the matters in methanol and high-purity- reagent industry and pointed out the necessity of international-standard-high- purity-methanol research in china. And then the techniques and feasibility of producing high purity methanol from industrial methanol were studied.An economical and practical method of evaluating the impurity of methanol was put forward. It was valuing ultraviolet transmission and moisture content of sample at the same time instead of testing the total quality index frequently. Ion exchange resin, molecular sieve, normal batch distillation, reaction distillation and batch extractive distillation were estimated and compared successively. The results indicate that batch extractive distillation is best suit to purify coal-made methanol and yet normal batch distillation suit natural-gas-made methanol perfectly.The influence of extractive solvent, operation principle and condition parameter on batch extractive distillation was measured. The optimum operation condition is that 2000mL industrial methanol is extracted with dimethylsulfoxide (DMSO), the average flow of DMSO is 597.6mL/h, the reflux ratio of the slop cut withdrawal is 8, the proportion (V/V) of the slop cut output without solvent and with solvent respectively is 5% and 15%, the reflux ratio of product phase is 5 and the yield of product phase is 60% (V/V). The quasi-steady-state model of the batch extractive distillation process was set up. On the basis of simulation, the optimum condition is that the number of theoretical plates is 35, DMSO as extraction solvent is added at the 10th theoretical plates, solvent ratio is 0.3, the reflux ratio of product phase and slop cut withdrawal respectively is 5 and 8. Accordingly, the single recovery fraction of high purity methanol is 60%.This text set up constant-molar-holdup model of the normal batch distillation process and solved it by two-point-implicate method with component balance calibration. The experiment results fit the simulation nicely. On the basis of experiment and simulation, the best technological condition is that the number of theoretical plates is 50, the proportion (V/V) of the slop cut output is 15%, the reflux ratio of product phase and slop cut withdrawal respectively is 5 and 10. Accordingly, the single recovery fraction of high purity methanol is 65%. This article drew up the project for two kinds of typical material methanol and economic feasibility of them was briefly estimated. The results show that it is an excellent project with a shorter payback period and a higher inside income rate.