The effect of ash composition on gasification of poultry wastes in a fluidized bed reactor.

The effect of ash composition on the fluidized bed gasification behaviour of poultry wastes was investigated by operating a pre-pilot scale reactor with two batches of manure obtained from an industrial chicken farm. The experimental runs were carried out by keeping the fluidized bed velocity fixed (at 0.4m s(-1)) and by varying the equivalence ratio between 0.27 and 0.40, so obtaining bed temperature values between 700 and 800 °C. The performance of the gasification process was assessed by means of mass balances as well as material and feedstock energy analyses, and reported in terms of cold gas efficiency (CGE), specific energy production, low heating value of obtained syngas and yield of undesired by-products. The experimental results indicate the crucial role of ash amount and composition of the two poultry wastes. In particular, higher ash content (25.1% instead of 17.2%) and higher fractions of calcium, phosphorous and potassium (with an increase of 24, 30 and 28%, respectively) induce a dramatic reduction of all the process performance parameters: CGE reduces from 0.63 to 0.33 and the specific energy from 2.1 to 1.1 kWh kg(fuel)(-1). At the same time, the formation of alkali compounds and their behaviour inside the fluidized bed reactor determine an increase of feedstock energy losses, which is related to occurrence of sintering and bridging between bed particles.

The O2-enriched air gasification of coal, plastics and wood in a fluidized bed reactor.

The effect of oxygen-enriched air during fluidized bed co-gasification of a mixture of coal, plastics and wood has been investigated. The main components of the obtained syngas were measured by means of on-line analyzers and a gas chromatograph while those of the condensate phase were off-line analysed by means of a gas chromatography-mass spectrometer (GC-MS). The characterization of condensate phase as well as that of the water used as scrubbing medium completed the performed diagnostics. The experimental results were further elaborated in order to provide material and substances flow analyses inside the plant boundaries. These analyses allowed to obtain the main substance distribution between solid, gaseous and condensate phases and to estimate the conversion efficiency of carbon and hydrogen but also to easily visualise the waste streams produced by the process. The process performance was then evaluated on the basis of parameters related to the conversion efficiency of fuels into valuable products (i.e. by considering tar and particulate as process losses) as well as those related to the energy recovery.