Study On Hydration Of Ethylene Oxide For Preparing Ethylene Glycol And Process Simulation

Ethylene oxide (EO) is one kind of important basic organic industrial chemicalsand intermediate in the ethylene derivatives. Most of EO are used to product Ethyleneglycol(EG)with water. This paper proposes and develops study on new processintensification technology of preparing ethylene glycol from hydration of ethyleneoxide aiming at existing process, which has many shortcomings just like high molarratio of water and EO, lower selectivity of ethylene glycol, high energy consumptionfor separation and complex process. The purpose of the research is providingtheoretical foundation and model support for the design and development of theprocess.（1）The paper puts forward a new process intensification technique based onanalysis of conditions of existing processes for producing EG from hydration ofethylene oxide and characteristics. Heat pump distillation is used to intensifyhydration reaction and thermally coupled distillation technology is used to intensifyproducts separationThe reaction section and the stripping section are in a unit column in thetraditional reaction distillation of EO hydration, reaction under high temperature andpressure, which resulted in the operation temperature of separation section higher,leading to the operating consumption very high. Aiming at this problem, this paperproposes a heat pump distillation process. In the process, hydration reaction isoperated in a higher pressure in a reactive distillation column, and the separation ofunconverted reactant and product performs in a stripping column with a lowerpressure, the compressor and valve are linked between the columns; the liquidmixture at the bottom of the distillation column act as the liquid reflux of stripperafter cooling through the valve, the steam at the top of the stripper act as the vaporreflux of the reactive distillation column after compression through compressorsimultaneously; reaction with higher temperature and pressure and separation with lower temperature and pressure process at the same time, and operating consumptionis reduced effective. According to the characteristics of product separation thatcontent of intermediate component (EG) is high, light component (water) and heavycomponent (DEG) are low, and difference of the mixture boiling point is large, thispaper puts forward the thermally coupled distillation technology. Intermediatecomponent has been non-sharp or sloppy split in prefractionator, the final product ispurified in main column, new technology simplifies the process and reduces theenergy consumption of products.（2）The research analyzes the simulation of new technology by Aspen Plus andreveals the trade-off between parameters and the laws of process.Simulate the heat-pump distillation columns, the effects of the operatingparameters (such feed ratio, reaction pressure of distillation column, reboiler duty ofstripper, etc.) on selectivity of EG are investigated to obtain the optimal operatingconditions of columns, the profiles of temperature, the vapor and liquid composition,besides liquid and vapor molar flow rate. The results indicate that conversion of EOachieves100%, conversion of water is83.3%, selectivity of EG is91%in theconditions of the operating pressure of reactive distillation column is1Mpa, stagenumber is eight，feed ratio of water and EO is1.1to1; stripper column with seventrays is operated on0.1Mpa, and reflux ratio is10.A method of simple design is established to obtain initial parameters and strictcalculation is taken to simulate thermally coupled distillation column. Simulation canobtain the optimal device and operating parameters of columns, the profiles oftemperature、the vapor and liquid composition、liquid and vapor molar flow rate. Theresults indicate that in the conditions of operating pressure is0.1Mpa, prefractionatorhas8trays and main column has35trays, reflux ratio is14, the target product withpurity more than99%is obtained by side product.The technical and economic feasibility of new technology are evaluted. Theresult indicated that the new technology proposed in paper with heat pump reactivedistillation and thermally coupled distillation is much superior than existingtechnology. It reflects a very good application in the area of lower feed ratio of water and EO, the system can achieve lower energy consumption because reaction heatenergy can be utilized directly, and high conversion rate of material and selectivity oftarget product. The results of this paper will provide theoretical basis for the processdesign, experimental research, operation control and equipment scale-up.