Fluidized bed granulation is a process by which granules or coated particles are produced in a single piece of equipment by spraying a hinder as solution, suspension, or melt on the fluidized powder bed. Heat and mass...Fluidized bed granulation is a process by which granules or coated particles are produced in a single piece of equipment by spraying a hinder as solution, suspension, or melt on the fluidized powder bed. Heat and mass transfer correlation useful for designing a granulator has been derived based on the equivalence of evaporation rate of the liquid to the heat transferred from hot gas to particles： （m/A）Dp^2λ/Lmf（1-εmf）（Tg-Tl）Kg=hDp/Kg.This equation is applied to data on granulation experiments by different workers to calculate Reynolds number and Nusselt number to obtain a relation between heat and mass transfer from gas to particles during granulation on a logarithmic scale from which the following empirical relation is obtained： Nu=0.0205Re^1.3876 which is comparable to Kothari＇s correlation Nu=0.03Re^1.3.By using the heat and mass transfer correlation obtained, the entry length, that is the length of granulator up to which effective heat transfer from gas to bed particles takes place, is estimated, which is also validated with experimental study. The correct estimation of entry length is useful in optimal design of a granulator.展开更多
Considering the strong dependence of agglomerate characteristics on various operating parameters,this study employs the control variable methodology(CVM)and response surface methodology(RSM)to investigate the influenc...Considering the strong dependence of agglomerate characteristics on various operating parameters,this study employs the control variable methodology(CVM)and response surface methodology(RSM)to investigate the influence of multi-factor interactions on particle growth during top-spray fluidized bed agglomeration.First,CVM is conducted to assess the effects of individual operating parameters on the agglomerate properties,such as mean particle size,relative width,and sphericity.Then,the interactive relationship between these input variables and the quality attributes of the process is investigated using RSM.The results show that the mean particle size increases with the increase of binder viscosity and spray rate,while it decreases with the increase of fluidization gas velocity and inlet gas temperature.The relative width of the particle size distribution increases with the spray rate,binder viscosity,and fluidization gas velocity,and hardly changes with the inlet gas temperature.The mean particle size is more sensitive to the binder spray rate at a lower level of fluidization gas velocity or a higher level of inlet gas temperature.The fluidization gas velocity corresponding to the maximum D_(50) changes when the binder viscosity and binder spray rate are at different levels.展开更多
Near infrared(NIR)spectroscopy is now widely used influidized bed granulation.However,there are still some demerits that should be overcome in practice.Valid spectra selection during modeling process is now a hard nut...Near infrared(NIR)spectroscopy is now widely used influidized bed granulation.However,there are still some demerits that should be overcome in practice.Valid spectra selection during modeling process is now a hard nut to crack.In this study,a novel NIR sensor and a cosine distance method were introduced to solve this problem in order to make thefluidized process into"visualization".A NIR sensor wasfixed on the side of the expansion chamber to acquire the NIR spectra.Then valid spectra were selected based on a cosine distance method to reduce the influence of dynamic disturbances.Finally,spectral pretreatment and wavelength selection methods were investigated to establish partial least squares(PLS)models to monitor the mois-ture content.The results showed that the root mean square error of prediction(RMSEP)was 0.124%for moisture content model,which was much lower than that without valid spectra selection treatment.All results demonstrated that with the help of valid spectra selection treatment,NIR sensor could be used for real-time determination of critical quality attributes(CQAs)more accurately.It makes the manufacturing easier to understand than the process parameter control.展开更多
文摘Fluidized bed granulation is a process by which granules or coated particles are produced in a single piece of equipment by spraying a hinder as solution, suspension, or melt on the fluidized powder bed. Heat and mass transfer correlation useful for designing a granulator has been derived based on the equivalence of evaporation rate of the liquid to the heat transferred from hot gas to particles： （m/A）Dp^2λ/Lmf（1-εmf）（Tg-Tl）Kg=hDp/Kg.This equation is applied to data on granulation experiments by different workers to calculate Reynolds number and Nusselt number to obtain a relation between heat and mass transfer from gas to particles during granulation on a logarithmic scale from which the following empirical relation is obtained： Nu=0.0205Re^1.3876 which is comparable to Kothari＇s correlation Nu=0.03Re^1.3.By using the heat and mass transfer correlation obtained, the entry length, that is the length of granulator up to which effective heat transfer from gas to bed particles takes place, is estimated, which is also validated with experimental study. The correct estimation of entry length is useful in optimal design of a granulator.
基金supported by the National Natural Science Foundation of China(grant No.52276149).
文摘Considering the strong dependence of agglomerate characteristics on various operating parameters,this study employs the control variable methodology(CVM)and response surface methodology(RSM)to investigate the influence of multi-factor interactions on particle growth during top-spray fluidized bed agglomeration.First,CVM is conducted to assess the effects of individual operating parameters on the agglomerate properties,such as mean particle size,relative width,and sphericity.Then,the interactive relationship between these input variables and the quality attributes of the process is investigated using RSM.The results show that the mean particle size increases with the increase of binder viscosity and spray rate,while it decreases with the increase of fluidization gas velocity and inlet gas temperature.The relative width of the particle size distribution increases with the spray rate,binder viscosity,and fluidization gas velocity,and hardly changes with the inlet gas temperature.The mean particle size is more sensitive to the binder spray rate at a lower level of fluidization gas velocity or a higher level of inlet gas temperature.The fluidization gas velocity corresponding to the maximum D_(50) changes when the binder viscosity and binder spray rate are at different levels.
基金the financial support of the Natural Science Foundation of Shandong Province of China(No.ZR2017MB012)Major In-novation Project of Shandong Province of China(2018CXGC1405)
文摘Near infrared(NIR)spectroscopy is now widely used influidized bed granulation.However,there are still some demerits that should be overcome in practice.Valid spectra selection during modeling process is now a hard nut to crack.In this study,a novel NIR sensor and a cosine distance method were introduced to solve this problem in order to make thefluidized process into"visualization".A NIR sensor wasfixed on the side of the expansion chamber to acquire the NIR spectra.Then valid spectra were selected based on a cosine distance method to reduce the influence of dynamic disturbances.Finally,spectral pretreatment and wavelength selection methods were investigated to establish partial least squares(PLS)models to monitor the mois-ture content.The results showed that the root mean square error of prediction(RMSEP)was 0.124%for moisture content model,which was much lower than that without valid spectra selection treatment.All results demonstrated that with the help of valid spectra selection treatment,NIR sensor could be used for real-time determination of critical quality attributes(CQAs)more accurately.It makes the manufacturing easier to understand than the process parameter control.
