Determining the optimum conditions for catalytic steam gasification of broiler litter

In the United SMes in 1996, approximately 7.6 billion head of broiler chickens were produced. This number has continuously risen over the last few years, with more than 75% of the production accounted in the southeastern United States. Because of the significant growth in the rate of production, the amount of litter produced is substantial. Unfortunately, much of the litter is not used for fertilizer and ends up polluting the rivers and surface waters. Because of the decreased availability of land and potential federal regulations, appropriate actions must be taken to find a better way to handle the poultry waste. Recently, catalytic steam gasification has been considered as an alternative to manage the broiler litter. The process requires and alkali metal or alkaline earth metal salt and steam to convert the feedstock to a fuel gas consisting primarily of carbon monoxide, carbon dioxide, hydrogen, and methane. The gas may be used as a possible energy source or chemical feedstock. The broiler litter is a good candidate for catalytic steam gasification because it contains potassium and several other alkali metal salts that can be used as a catalyst. Even if the inherent salts are not sufficient, additional sources, such as potassium carbonate and langbeinite, can be used with minimal additional cost. The broiler litter also produces low quantities of unwanted hydrogen sulfide. The residue left after gasification can also be used as fertilizer or in the concrete/cement manufacturing industries. A preliminary study was carried out to determine the concept's feasibility. In that study, a bench-scale high-pressure, fixed bed gasification system was designed and assembled to carry out experiments up to a temperature of 1400°F,and pressures up to 250 psig. Also, in that study, a limited number of experiments were conducted at different temperatures, pressures, and catalyst loadings to prove the technical and economic viability of handling broiler litter. Additional work has now been carried out to validate the optimum conditions for handling the broiler litter. In this work, a screening test matrix has been developed to assess the different process variables so as to determine the optimum conditions for treating the broiler litter. Comparative analyses are also carried out in this work to see if the process is economically viable for stationary as well as mobile applications.