Research On Optimization Of Energy Utilization In The Cold Silicon Tetrachloride Hydrogenation Process

There will produce large amounts of by-products silicon tetrachloride in the process of polysilicon making by improved Siemens.How to deal with the by-products silicon tetrachloride is the key problems of the polysilicon enterprises energy consumption,cost,green manufacture,also is the key of the improved Siemens method achieve really closed production.Hot hydrogenation and cold hydrogenation are the two methods of silicon tetrachloride hydrogenation technology which currently used for large-scale commercial production.Compare with the hot hydrogenation,the cold hydrogenation has lower consumption power,and has the obvious advantages in reduce cost,energy conservation and emissions reduction,so most polysilicon companies use this process.Based on the theory of pinch point design method,the process integration technology has obvious effect in saving energy and reducing consumption in the chemical production.It is based on thermodynamics and combined with systems engineering,and can raise the utilization ratio of global energy by analyzing the flow of energy in the chemical production system to find the main bottleneck of system energy utilization link,and to point out the way to take off the bottleneck.In this paper,we simulate the flow path of silicon tetrachloride cold hydrogenation process using Aspen Plus,and check with the actual production data.Based on the simulation process,we extract the logistics information of the silicon tetrachloride cold hydrogenation process,then using the pinch technology,we can analyze and find out the original process system with problems is the logistics have been no reasonable matching near the pinch point.After optimized by using pinch technology,we can find out energy saving potential of the system.Based on the pinch design criteria,we rematch the problems logistics.Considering the total cost,we simulate the heat exchange network.According the transformation ideas,we build a new model,and calculate the heat exchanger using EDR.We increase three heat exchangers of product purification unit,then the unit can save 78.1% hot utility consumption,and 83.6% cold utility consumption,and can save 5.528 million of running cost each year.We increase two heat exchangers of product purification unit,then the unit can save 22.6% hot utility consumption,and 19.1% cold utility consumption,and can save 8.852 million of running cost each year.According to the optimized scheme of this paper,this enterprise has transformed the existing device,and has received the desired effect,because the consumption of the utilities is resemblance with the solution after stable operation.