The particle deposition behaviour of skim milk, water and maltodextrin in the conical section of a pilot-scale spray dryer was predicted using simple correlations for particle depositions in pipes. The predicted parti...The particle deposition behaviour of skim milk, water and maltodextrin in the conical section of a pilot-scale spray dryer was predicted using simple correlations for particle depositions in pipes. The predicted particle deposition fluxes of these materials were then compared with the measured deposition fluxes. The predicted particle deposition regimes of the spray dryer were expected to be in the diffusional and mixed (diffusional and inertial) regimes, but the experimental results suggested that the particle deposition was mainly in the inertial regime. Therefore, using the pipe correlations for predicting deposition in a pilot-scale spray dryer suggests that they do not sufficiently represent the actual deposition behaviour. This outcome indicates that a further study of particle flow patterns needs to be carried out using numerical simulations (computational fluid dynamics, CFD) in view of the additional geometrical complexity of the spray dryer.展开更多
Wall deposition occurs in spray dryers when dried or partially dried particles contact and adhere to the walls during operation, thus reducing the yield of product collected. Wall deposits also present a product conta...Wall deposition occurs in spray dryers when dried or partially dried particles contact and adhere to the walls during operation, thus reducing the yield of product collected. Wall deposits also present a product contamination risk and a fire or explosion risk when spray drying products that oxidize exothermically, such as milk powder. Re-entrainment is the resuspension of spray dryer wall deposits into the main gas stream for collection as product. Literature suggests that the process for re-entrainment of particles from spray dryer wall deposits is strongly dependent on particle size and gas velocity.展开更多
Based on the demand of sintering/pelleting flue gas ultra-low emission,a semi-dry method using a spray dryer absorber (SDA) combined with O3 oxidation was proposed for simultaneous removal of SO2 and NO.Effects of O3 ...Based on the demand of sintering/pelleting flue gas ultra-low emission,a semi-dry method using a spray dryer absorber (SDA) combined with O3 oxidation was proposed for simultaneous removal of SO2 and NO.Effects of O3 injection site,O3/NO molar ratio,and spray tower temperature on the removal efficiencies were investigated.It was revealed that both desulfurization and denitrification efficiencies could reach to 85%under the conditions of setting O3 injection site inside of tower,O3/NO molar ratio 1.8,spray tower temperature 85°C,Ca/(S+2N) molar ratio 2.5 and slurry flow rate 300 m L/hr.CaSO3/Ca(OH)2 mixture slurry was used as absorbent to simulate operating conditions in iron and steel industry.The result shows that the addition of CaSO3 weakens both removal efficiencies.In addition,the reaction mechanism of simultaneous removal of SO2 and NO using SDA combined with O3 oxidation was proposed.展开更多
Monodisperse droplet spray dryers have great advantages in particle formation through spray drying because of their ability to produce uniform sized particles. Experimental analyses of this system have shown that drop...Monodisperse droplet spray dryers have great advantages in particle formation through spray drying because of their ability to produce uniform sized particles. Experimental analyses of this system have shown that droplets atomized through the piezoceramic nozzle need to be sufficiently well dispersed before entering the drying chamber to achieve sufficiently dried particles. However, the dispersion dynamics cannot be readily observed because of experimental limitations, and key factors influencing the dispersion state currently remain unclear. This study carried out numerical simulations for droplet dispersions in the dispersion chamber, which allow this important process to be visualized. The system- atic and quantitative analyses on the dispersion states provide valuable data for improving the design of the dispersion chamber, and optimizing the spray drying operation.展开更多
Carbon dioxide(CO_(2))is an influential greenhouse gas that has a significant impact on global warming partly.Nowadays,many techniques are available to control and remove CO_(2) in different chemical processes.Since t...Carbon dioxide(CO_(2))is an influential greenhouse gas that has a significant impact on global warming partly.Nowadays,many techniques are available to control and remove CO_(2) in different chemical processes.Since the spray dryer has high removal efficiency rate,a laboratory-scale spray dryer is used to absorb carbon dioxide from air in aqueous solution of NaOH.In the present study,the impact of NaOH concentration,operating temperature and nozzle diameter on removal efficiency of CO_(2) is explored through experimental study.Moreover,the reaction kinetic of NaOH with CO_(2) is studied over the temperature range of 50-100℃ in a laboratory-scale spray dryer absorber.In the present contribution,a simple reaction rate equation is proposed that shows the lowest deviation from the experimental data with error less than 2%.展开更多
Palm C16 methyl ester sulphonate （C16MES）is an anionic surfactant that has the potential as active ingredient in the production of laundry detergent powders. Although C16MES has been successfully applied in the prod...Palm C16 methyl ester sulphonate （C16MES）is an anionic surfactant that has the potential as active ingredient in the production of laundry detergent powders. Although C16MES has been successfully applied in the production of high-density laundry detergent powders （HDDP）, it coulingd not be employed directly as it is in the spray drying process for the production of low-density laundry detergent powders （LDDP） without compromising the detergency and other significant properties. This research paper highlights the pilot-scale experimental study, which performed to produce phosphate-free laundry detergent （PFD） powders incorporated with binary anionic surfactants of C16MES and linear alkyl benzene sulphonic acid （LABSA）. Past laboratory experiments revealed that PFD powders resulted from C16MES/LABSA of 50：50 ratio and of pH 7-8 have good detergency stability upon one-week of continuous heating in an oven at 50~C with 85% relative humidity. Based on these laboratory results, subsequent experiments were carded in a 5 kg/hr capacity co-current pilot spray dryer using PFD formulations comprising six different ratios of C16MES/LABSA （0：100, 20：80, 40：60, 80：20 and 100：0） under the same pH condition. Three PFD formulations were selected for further evaluation based on their characteristics in the spray drying process. The cleaning properties and particle properties of the resulting spray dried detergent powders from these selected formulations were analyzed. Based on the overall evaluation, C16MES/LABSA in 40：60 ratio was selected as the ideal PFD formulation. Further tests confirmed that spray dried detergent powder （SDDP） from the ideal formulation has high level of biodegradability （60% in 13 d）, low eco-toxicity properties （LC50 of 11.3 mg/L） and moderate flowability charactedsUcs （Hausner ratio of 1.27 and Carr＇s index of 21.3）.展开更多
文摘The particle deposition behaviour of skim milk, water and maltodextrin in the conical section of a pilot-scale spray dryer was predicted using simple correlations for particle depositions in pipes. The predicted particle deposition fluxes of these materials were then compared with the measured deposition fluxes. The predicted particle deposition regimes of the spray dryer were expected to be in the diffusional and mixed (diffusional and inertial) regimes, but the experimental results suggested that the particle deposition was mainly in the inertial regime. Therefore, using the pipe correlations for predicting deposition in a pilot-scale spray dryer suggests that they do not sufficiently represent the actual deposition behaviour. This outcome indicates that a further study of particle flow patterns needs to be carried out using numerical simulations (computational fluid dynamics, CFD) in view of the additional geometrical complexity of the spray dryer.
文摘Wall deposition occurs in spray dryers when dried or partially dried particles contact and adhere to the walls during operation, thus reducing the yield of product collected. Wall deposits also present a product contamination risk and a fire or explosion risk when spray drying products that oxidize exothermically, such as milk powder. Re-entrainment is the resuspension of spray dryer wall deposits into the main gas stream for collection as product. Literature suggests that the process for re-entrainment of particles from spray dryer wall deposits is strongly dependent on particle size and gas velocity.
基金supported by the Nationals Key Research and Development Program of China (No.2017YFC0210600)the National Natural Science Foundation of China (No.51978644)。
文摘Based on the demand of sintering/pelleting flue gas ultra-low emission,a semi-dry method using a spray dryer absorber (SDA) combined with O3 oxidation was proposed for simultaneous removal of SO2 and NO.Effects of O3 injection site,O3/NO molar ratio,and spray tower temperature on the removal efficiencies were investigated.It was revealed that both desulfurization and denitrification efficiencies could reach to 85%under the conditions of setting O3 injection site inside of tower,O3/NO molar ratio 1.8,spray tower temperature 85°C,Ca/(S+2N) molar ratio 2.5 and slurry flow rate 300 m L/hr.CaSO3/Ca(OH)2 mixture slurry was used as absorbent to simulate operating conditions in iron and steel industry.The result shows that the addition of CaSO3 weakens both removal efficiencies.In addition,the reaction mechanism of simultaneous removal of SO2 and NO using SDA combined with O3 oxidation was proposed.
文摘Monodisperse droplet spray dryers have great advantages in particle formation through spray drying because of their ability to produce uniform sized particles. Experimental analyses of this system have shown that droplets atomized through the piezoceramic nozzle need to be sufficiently well dispersed before entering the drying chamber to achieve sufficiently dried particles. However, the dispersion dynamics cannot be readily observed because of experimental limitations, and key factors influencing the dispersion state currently remain unclear. This study carried out numerical simulations for droplet dispersions in the dispersion chamber, which allow this important process to be visualized. The system- atic and quantitative analyses on the dispersion states provide valuable data for improving the design of the dispersion chamber, and optimizing the spray drying operation.
文摘Carbon dioxide(CO_(2))is an influential greenhouse gas that has a significant impact on global warming partly.Nowadays,many techniques are available to control and remove CO_(2) in different chemical processes.Since the spray dryer has high removal efficiency rate,a laboratory-scale spray dryer is used to absorb carbon dioxide from air in aqueous solution of NaOH.In the present study,the impact of NaOH concentration,operating temperature and nozzle diameter on removal efficiency of CO_(2) is explored through experimental study.Moreover,the reaction kinetic of NaOH with CO_(2) is studied over the temperature range of 50-100℃ in a laboratory-scale spray dryer absorber.In the present contribution,a simple reaction rate equation is proposed that shows the lowest deviation from the experimental data with error less than 2%.
文摘Palm C16 methyl ester sulphonate （C16MES）is an anionic surfactant that has the potential as active ingredient in the production of laundry detergent powders. Although C16MES has been successfully applied in the production of high-density laundry detergent powders （HDDP）, it coulingd not be employed directly as it is in the spray drying process for the production of low-density laundry detergent powders （LDDP） without compromising the detergency and other significant properties. This research paper highlights the pilot-scale experimental study, which performed to produce phosphate-free laundry detergent （PFD） powders incorporated with binary anionic surfactants of C16MES and linear alkyl benzene sulphonic acid （LABSA）. Past laboratory experiments revealed that PFD powders resulted from C16MES/LABSA of 50：50 ratio and of pH 7-8 have good detergency stability upon one-week of continuous heating in an oven at 50~C with 85% relative humidity. Based on these laboratory results, subsequent experiments were carded in a 5 kg/hr capacity co-current pilot spray dryer using PFD formulations comprising six different ratios of C16MES/LABSA （0：100, 20：80, 40：60, 80：20 and 100：0） under the same pH condition. Three PFD formulations were selected for further evaluation based on their characteristics in the spray drying process. The cleaning properties and particle properties of the resulting spray dried detergent powders from these selected formulations were analyzed. Based on the overall evaluation, C16MES/LABSA in 40：60 ratio was selected as the ideal PFD formulation. Further tests confirmed that spray dried detergent powder （SDDP） from the ideal formulation has high level of biodegradability （60% in 13 d）, low eco-toxicity properties （LC50 of 11.3 mg/L） and moderate flowability charactedsUcs （Hausner ratio of 1.27 and Carr＇s index of 21.3）.
