Experimental Study And Process Simulation Of Drying Of Hydrogen Chloride By Adsorption

In recent years, new energy industries are developing quickly, in which solarenergy has received broad attention. Polysilicon is the core component of solar energycell. Trichlorosilane is main raw material of this process, while production oftrichlorosilane needs large amount of hydrogen chloride. Hydrogen chloride isgenerally produced by hydrogen and chlorine burning in hydrogen chloride furnace.Water in hydrogen chloride not only has an effect on the yield of trichlorosilane, alsoinfluences serviceable life of synthetic furnace of trichlorosilane and other relatedinstallations. Reducing water in hydrogen chloride effectively will have a good effecton energy saving in the production of trichlorosilane.The feasibility of using zeolite for the deep dehydration of hydrogen chloride onthe basis of refrigeration was studied，and the process simulation was made. Threetypes of zeolite (NKF-4A, NKF-5(50), NKF-5(300)) were chosen for the performancetest of removing water from hydrogen chloride, including dynamic adsorptioncapacity, wear rate and regeneration rate. The experimental results showed that:(1)All three types of zeolite could remove water in hydrogen chloride to less than50ppm (wt).(2) When considering dynamic adsorption capacity, NKF-4A＞NKF-5(50)＞NKF-5(300).(3) The wear rate of NKF-4A is0.93%and that of the two others iszero in the detection limit. And also color change of NKF-4A is obvious after use andthat can not recover, while the two others are not.(4) NKF-5(50) zeolite has a fasterregeneration rate than the two others.Taking all these aspects into consideration,NKF-5(50) zeolite is the best one for removing water from hydrogen chloride.Aspen Adsorption is used for the simulation of breakthrough curve ofdehydration of hydrogen chloride. The effects on breakthrough curve of single factorincluding pressure, mass transfer coefficient and bed porosity change was studied.The rationality of isothermal assumption and simplification for a single diluteadsorbate (water) in a carrier fluid (hydrogen chloride) is explained by engineeringdesign way. In order to save time of design and investment, Aspen Adsorption can beapplied to assisting the design of adsorption process.