into converter 715 716 is the exhaust stream from converter 715 containing tcs and hcl along with unreacted h 2 and stc fed to stc converter 715 in stream 714 condensation train 717 condenses substantially all of the chlorosilanes from the h 2 in stream 716 into stream 719 which then flows to distillation column 721 vapor stream 718 leaves condenser 717 and flows back to the fbr 701 h 2 stream 712 can be preheated in an interchanger with stream 716 not shown and fed to stc vaporizer 728 to reduce heat load on the vaporizer 728 and condensation train 717 tcs 722 leaves distillation column 721 to go through purification train 723 prior to being fed to cvd operations via stream 724 standard engineering techniques using chemical engineering simulation software widely used in industry chemcad version 6 provided by chemstations 3100 wilcrest drive suite 300 houston tex usa and aspenplus version 8 provided by aspentech 20 crosby drive bedford mass usa were used to model and compare the energy consumption per unit tcs produced in a traditional tcs plant associated with polysilicon production the processes of fig5 fig2 and fig3 are compared in these comparisons the energy for separation of stc from tcs by distillation in equipments 244 and 323 are not included physical properties thermodynamic models and equations of state known by those skilled in the art to be sufficiently accurate for industrial applications were used the industrial range stated below is based on the inventor 39 s industry experience of designs and.