Cooling-solidification of sprayed droplets is one of major methods for prilling of melt.Traditionally, this is carried out in an empty tower,and the equipment requirement for producing larger particles is very high,re...Cooling-solidification of sprayed droplets is one of major methods for prilling of melt.Traditionally, this is carried out in an empty tower,and the equipment requirement for producing larger particles is very high,resulting in not only significant cost increasing but also difficulties in transporting melt etc.Based on analysis and simulation,a new prilling process is developed for the melt prilling,which combines a tower with a fluidized bed so that the height of equipment is greatly decreased,and it exhibits satisfactory performance in industrial application. Mathematical model for tower prilling,its simulated results,the structure of the equipment for the innovated prilling process and its application are addressed.展开更多
Water and nitrogen are two key elements required for successful rice cultivation. We examined the responses of nitrogen and water management on methane emission of Boro rice in the field laboratory of Bangladesh Agric...Water and nitrogen are two key elements required for successful rice cultivation. We examined the responses of nitrogen and water management on methane emission of Boro rice in the field laboratory of Bangladesh Agricultural University research farm, Mymensingh. Three treatments were studied in the field experiment viz, T1: Control plot (no nitrogen fertilizer), T2: Urea super granule (78 kg N/ha), T3: Prilled urea (104 kg N/ha) with three replications under two water management of Continuous Standing Water (CSW) and Alternate Wetting and Drying (AWD). Air samples were collected by the closed-chamber method and methane gas was determined by gas chromatography. The highest CH4 emission was found from CSW plots and the lowest from AWD plots. Under CSW condition, the effects of urea treatments on CH4 emission were not significant. In case of urea treatments, the highest CH4 emission was observed from treatment T3 under CSW condition and T2 under AWD condition and the lowest emission was from the control treatment. The overall results suggest that prilled urea and urea super granule should be applied under AWD and CSW condition, respectively to keep less CH4 emission from irrigated rice agriculture.展开更多
A prilled urea applicator was designed and developed to increase fertilizer use efficiency. The developed applicator’s aims to place Urea continuously at the subsurface of soil between two rows of plants. A line-to-l...A prilled urea applicator was designed and developed to increase fertilizer use efficiency. The developed applicator’s aims to place Urea continuously at the subsurface of soil between two rows of plants. A line-to-line distance of 20 cm, depth of prilled urea placement of 5 - 7 cm, and field operating condition at 1 - 1.5 cm standing water (for softening the field) was the designed hypothesis. At the laboratory and farm level, test the developed applicator. The applicator consists of a rectangular frame, two skids and furrow opener, two cylindrical hoppers, and a drive wheel connected with a metering device. The designed applicator was fabricated using PVC, except the push handled (mild steel). The metering device consists of twelve spikes and is made of a metallic plate to apply the Urea uniformly. The applicator has a furrow opener and closer options. The effective field capacity was 0.13 ha/h with a speed of 1.22 km/h and field efficiency of 98%. Due to the continuous falling mechanism, there is no missing option but found the over-falling urea for both hoppers was found 5.35%. The average depth of urea placement was 6.38 cm. The machine was user-friendly to push, and the mean pushing force was 63.89 N. The weight of the applicator was 9 kg. So, it is natural to carry from one field to another field. The applicator is also convenient to handle, operate and manage.展开更多
文摘Cooling-solidification of sprayed droplets is one of major methods for prilling of melt.Traditionally, this is carried out in an empty tower,and the equipment requirement for producing larger particles is very high,resulting in not only significant cost increasing but also difficulties in transporting melt etc.Based on analysis and simulation,a new prilling process is developed for the melt prilling,which combines a tower with a fluidized bed so that the height of equipment is greatly decreased,and it exhibits satisfactory performance in industrial application. Mathematical model for tower prilling,its simulated results,the structure of the equipment for the innovated prilling process and its application are addressed.
文摘Water and nitrogen are two key elements required for successful rice cultivation. We examined the responses of nitrogen and water management on methane emission of Boro rice in the field laboratory of Bangladesh Agricultural University research farm, Mymensingh. Three treatments were studied in the field experiment viz, T1: Control plot (no nitrogen fertilizer), T2: Urea super granule (78 kg N/ha), T3: Prilled urea (104 kg N/ha) with three replications under two water management of Continuous Standing Water (CSW) and Alternate Wetting and Drying (AWD). Air samples were collected by the closed-chamber method and methane gas was determined by gas chromatography. The highest CH4 emission was found from CSW plots and the lowest from AWD plots. Under CSW condition, the effects of urea treatments on CH4 emission were not significant. In case of urea treatments, the highest CH4 emission was observed from treatment T3 under CSW condition and T2 under AWD condition and the lowest emission was from the control treatment. The overall results suggest that prilled urea and urea super granule should be applied under AWD and CSW condition, respectively to keep less CH4 emission from irrigated rice agriculture.
文摘A prilled urea applicator was designed and developed to increase fertilizer use efficiency. The developed applicator’s aims to place Urea continuously at the subsurface of soil between two rows of plants. A line-to-line distance of 20 cm, depth of prilled urea placement of 5 - 7 cm, and field operating condition at 1 - 1.5 cm standing water (for softening the field) was the designed hypothesis. At the laboratory and farm level, test the developed applicator. The applicator consists of a rectangular frame, two skids and furrow opener, two cylindrical hoppers, and a drive wheel connected with a metering device. The designed applicator was fabricated using PVC, except the push handled (mild steel). The metering device consists of twelve spikes and is made of a metallic plate to apply the Urea uniformly. The applicator has a furrow opener and closer options. The effective field capacity was 0.13 ha/h with a speed of 1.22 km/h and field efficiency of 98%. Due to the continuous falling mechanism, there is no missing option but found the over-falling urea for both hoppers was found 5.35%. The average depth of urea placement was 6.38 cm. The machine was user-friendly to push, and the mean pushing force was 63.89 N. The weight of the applicator was 9 kg. So, it is natural to carry from one field to another field. The applicator is also convenient to handle, operate and manage.
