Study On Silica Gel Drying Characteristics And System Simulation Of Of Direct Combustion Flue Gas

Silicon dioxide aerogel(silica gel),as a highly active porous material,has many advantages,such as stable chemical properties,high adsorption performance,good thermal stability,high mechanical strength,etc.However,its preparation and drying process is a highly energy-consuming operation.As a highly energy-consuming product,silica gel needs a stable and simple drying process in the large-scale production process to meet the production needs.In order to achieve a benign cycle of energy-saving development of enterprises and in response to the national requirements for energy saving and carbon reduction,the existing silica gel drying system which produces steam from coal burning needs to be renovated.In this paper,a direct-fired flue gas silica gel drying scheme is proposed based on the experimental study on the hot air drying characteristics of silica gel.The drying process in the mesh is simulated by COMSOL,and the rationality of the transformation scheme is analyzed.(1)Based on the dynamic theory and heat and mass transfer theory of the drying process of silicone,the drying characteristics of silicone gel in the hot air drying process were studied.The drying characteristics of silicone gel entered the first decelerating drying stage when the water content reached 66%,and the second decelerating drying stage when the water content reached 18%.In the initial drying stage,the higher the temperature,the slower the initial drying rate,but the faster the growth,the slower the decay;In the second deceleration stage,the drying rate is faster at a lower temperature.The thicker the paving,the longer the drying time is needed,but the drying time increases by less and less with the thickness.Jena Das’ s model can accurately describe the drying characteristics of silicone gel during hot air drying,and fit the mathematical model under experimental conditions.The temperature change rule of silicone during hot air drying was studied experimentally.It was found that the temperature gradient inside the silicone gel was large when the paving thickness was high,the temperature at the center of the silicone gel measured point rose to 60 ～80 C after entering the hot airfield,and the temperature at the periphery measured point had a linear relationship with time.(2)Based on the hot air drying characteristics and the law of temperature change of silicone gel,a direct-fired flue gas silicone drying system is proposed,and the complete operating conditions and basic equipment parameters are designed and calculated to provide technical parameters for practical application.(3)The effects of different factors on the drying system were simulated by using COMSOL simulation technology,and the drying process under specific conditions in the design was simulated.The simulation results show that the external circulation has a better airflow effect and a faster increase in airspeed.The faster the wind speed,the faster the water evaporates from the material surface.The temperature change of the material in the hot airfield is similar to the experimental result.The unit drying chamber drying simulation under the designed smoke state parameters shows that the predicted drying effect can be achieved by good simulation results.(4)After experimental determination of the actual system,the drying effect of the direct combustion flue gas silica gel drying system is good,with a significant energysaving effect and great social benefit.This system provides a protocol option for the modification of drying systems with coal-fired steam as the source of heat.