Preparation schemes of crushed coal for combustion in fluidized bed boilers using a gravity separator

The low concentration of nitrogen oxide during coal combustion in fluidized bed furnaces is due to the limited proportion of primary air in the combustion zone. The schemes applied for the preparation of crushed coal are mostly for the use of coal breakage screens with a fixed maximum particle size in the mixture. The primary air flow is limited to the conditions of the fluidization of the bed and can be reduced only by reducing the size of the particles fed into the furnace. With a constant particle size and lower boiler loads, the proportion of primary air and thus the concentration of nitrogen oxides in the flue gas increase. The use of separators to change the particle size has never been considered, since it is a priori assumed that the separators cannot provide the required disperse composition of crushed coal. To assess the possibility of using separators in the schemes of preparing crushed coal for combustion in a fluidized bed and to determine the necessary separation boundaries, variants calculations were carried out in respect to the coal preparation scheme for boiler No. 9 of the Novocherkasskaya hydro-power plant. It is shown that the disperse composition of the fine separation product in the gravity separator with overturning shelves along the 5 mm boundary is identical to the disperse composition of crushed coal obtained in the scheme with a screen and crusher. The dependence of the maximum particle size of crushed coal on the separation boundary of the separator is given. It is shown that in the scheme of preparation of crushed coal for combustion in a fluidized bed, replacement of screens with gravity separators will not lead to violation of the requirements for the dispersed composition of crushed coal. At the same time, the proposed replacement allows you to quickly change the maximum particle size of crushed coal during operational activity and thereby to maintain the optimal fraction of primary air when the boiler load changes.

Influence of Seed Quality Upgrading by Processing Machines in Soybean var. DSb-21

Background: Soybean is the “Miracle crop” of the 21st century due to its nutritional value and multiple uses. Maintenance of soybean seed quality is a major issue as it is more vulnerable to mechanical damage from harvesting to next sowing. Seed processing.by use of individual or combination of machineries will help in getting physically pure, uniform, healthy sound seeds with enhanced planting value. With the advent of new improved varieties, it is advisable to find out the individual or combination of seed processing machines like air screen cleaner, specific gravity and spiral separator to find out the effective and economical seed processing to get maximum recovery with up-graded quality of seeds.Methods: The seeds of soybean var. DSb-21 were used for seed size grading using different sieve sizes and the good seeds obtained from different size grading were processed through specific gravity separator and the good seeds obtained from specific gravity separator were further processed through spiral separator and the processed seeds obtained from these machine combinations were used to assess the seed quality. The seed processing was carried out at Seed Processing Unit and seed quality studies were carried out in the Seed Quality and Research Laboratory, Seed Unit, University of Agricultural Sciences, Dharwad during 2017-18. The experiment was laid in completely randomized design.Result: The influence of sequential processing through seed size grader followed by specific gravity separator and spiral separator on seed quality revealed that, the good seeds obtained from spiral separator after seed grading with recommended sieve size 3.75 mm recorded higher recovery (76.95%), seed germination (89.00%), seedling vigour index (3567) and lower seed mechanical damage (11.67%) followed by 4.00 mm (74.80%, 87.33%, 3418 and 12.33%, respectively) and 4.80 mm (65.64%, 85.00%, 3209 and 13.67%, respectively).

Optimization of Grading Efficiency of a Specific Gravity Separator to Upgrade the Quality of (Moringa oleifera Lam.) Seeds

The quality of Moringa oleifera seeds need to be ensured before sowing or using the seeds for other commercial purposes like oil extraction. In this study, an attempt was made to increase the efficiency of a specific gravity separator machine to upgrade the quality of moringa seed by suitably changing the machine settings viz., horizontal height (cm), vertical height (cm), and oscillation speed (rpm) of the deck and air blow rate (m3/hr). The optimization of moringa seed quality upgrading specific gravity machine has a horizontal height (cm), vertical height (cm), and air blow rate (m3/hr) adjustments of 0, 1.5, and 4.0 respectively at 450 rpm of deck oscillation. Under the above-optimized conditions, seed lot graded into five categories viz., A, B, C, D and E. Germination percentage of three grade viz., C, D, and E have 93.0%, 97.0%, and 96.0% respectively, which was higher than the germination percentage of ungraded bulk moringa seed lot (91.0%) used in this experiment. Seed with undesirable size and low in weight got separated as ‘A’ grade material. The optimization of moringa seed upgarding process showed the optimal processing conditions for grading the moringa seed based on physical property of the seed. The optimization of the moringa seed-grading machine would provide necessary information on combination of seed, operation and design parameters for enhancing seed quality.