Influence of a Biodegradable Litter Amendment on the Pyrolysis of Poultry Litter

Abstract

The effects of adding a biodegradable litter amendment (AmmoSoak), developed from steam exploded corncobs, to poultry litter prior to pyrolysis on the product yields and qualities were investigated. Mixtures of litter and AmmoSoak were pyrolyzed in a bench-scale fluidized bed reactor. The objective of the second phase was to start-up a pilot-scale fluidized bed reactor unit.

The poultry litter had a lower higher heating value (HHV), higher moisture, ash, nitrogen, sulfur, and chlorine contents than AmmoSoak. Analysis of the poultry litter indicated a mixture of volatiles, hemicelluloses, cellulose, lignin, ash, and proteins. AmmoSoak had a simpler composition than the litter; mainly hemicelluloses, cellulose, and lignin. Bench-scale studies indicated that adding AmmoSoak affected the yields and characteristics of the products.

Addition of Ammosoak increased the bio-oil and syngas yields and decreased char yields. Adding AmmoSoak to the feed decreased the pH, water contents, initial viscosity, and the rate at which the viscosity increased with time, while densities and HHVs increased. The addition of Ammosoak to poultry litter also increased the carbon and oxygen contents of the boi-oils while nitrogen, hydrogen, sulfur, chlorine and ash contents decreased.

A pilot-scale fluidized bed reactor was designed, constructed, installed and investigated for the pyrolysis of poultry litter. Fluidization and thermal equilibrium of the reactor were successfully demonstrated. The reactor was heated by combustion of propane. To ensure complete combustion, the combustion water was collected and compared to the stoichiometric yield. Complete combustion was achieved. Bio-oil yields on the pilot scale were lower than those obtained on the bench-scale pyrolysis unit. The water soluble fractions of the bio-oils were rich in oxygen. Water insoluble fractions were rich in carbon and ash.