Impeller Blower Performance in Conveying Broiler Litter

Broadcast application is the typical application method for poultry litter, which is a mixture of poultry manure and a bedding material. Applying poultry litter in subsurface bands reduces concentrations of nutrients from the litter in surface runoff water, reduce loss of ammonia to volatilization, and has been shown to increase cotton lint yield, relative to conventional broadcast application. An impeller blower was developed for conveying poultry litter a short distance horizontally and downward to the soil. When relatively dry pine shavings-based broiler litter with a moisture content of 27% w.b. was used, and the impeller speed was 930 r min-1 [14.9 m s-1 (48.9 ft s-1) circumferential speed], the blower performed well conveying litter at a rate of 1.2 kg s-1 (2.6 lb s-1) [0.88 kg dry matter s-1 (1.9 lb dry matter s-1)]. The blower performance was unsatisfactory, however, when relatively moist litter with a moisture content of 45% w.b. was used because the litter adhered to the interior of the blower outlet and clogged the outlet. The blower was mounted beneath a litter hopper, and safety of people in the vicinity of the blower is a concern if the litter contains rocks or other hard objects, and there is no shield to prevent these objects from being flung upward, out of the hopper, from the blower inlet. When the blower was run at 889 ± 14 r min-1 without any litter, so it was conveying only air, as the area of the circular blower inlet increased by a factor of 25 from 0.00051 to 0.0127 m2 (0.79 to 19.6 in.2), the mean outlet air velocity increased by a factor of 4.0 from 3.0 to 12.0 m s-1 (9.8 to 39.4 ft s-1). The blower conveyed dry litter successfully for a single-band implement [1.2 kg s-1 (2.6 lb s-1) mass flow rate at 930 r min-1 impeller speed], for subsurface band application of poultry litter. Mesh chain conveyors, however, perform better for litter moisture contents up to 40% w.b. The mass flow rate of litter, up to 40% w.b. moisture content, can be controlled quite well with mesh chain conveyors (litter mass flow rate coefficients of variation typically 5% or less), but is more difficult to control with this impeller blower. Keywords: Animal waste, Band application, Impeller blower, Manures, Manure application equipment, Pneumatic conveying, Poultry manure, Subsurface banding.