Energy from poultry waste: An Aspen Plus-based approach to the thermo-chemical processes

A particular approach to the task of energy conversion by a residual waste material was largely experienced during the implementation of the national funded Enerpoll project. The project is a case study applied to a poultry farm located in the peripheral context of Umbria (Italy); such a farm was chosen as representative of many similar smallsized breeding realties in the Italian regional context. The disposal of a waste material (i.e. poultry manure) and the contextual energy recovery was the purpose of the case study; this aim is in agreement with the major energy objectives enhanced by the vision of the European Commission. To this aim, an innovative gasification plant (300 kW) was chosen for the experimentation: the approach novelty deals with the possibility to achieve the thermal energy production burning the derived syngas and not directly the solid residues, minimizing the nitrogen released by the exhaust flue gases and directing it into solid residues (i.e. ashes). A complete Aspen Plus v.8.0 model was also elaborated for the prediction of the quality of the produced synthesis gas as a function of both the gasification temperature and the equivalence ratio (ER); the monitored average hourly produced thermal power equal to 200 kW allowed the model estimation of the syngas energy content (i.e. LHV), resulting in the range of 3 - 5 MJ/m3 and resulting from an ER value equal to 0,2.

A particular approach to the task of energy conversion of a residual waste material was properly experienced during the implementation of the national funded Enerpoll project. This project is a case study developed in the estate of a poultry farm that is located in a rural area of central Italy (Umbria Region); such a farm was chosen for the research project since it is almost representative of many similar small-sized breeding realties of the Italian regional context. The purpose of the case study was the disposal of a waste material (i.e. poultry manure) and its energy recovery; this task is in agreement with the main objectives of the new Energy Union policy. Considering this background, an innovative gasification plant (300. KW thermal power) was chosen and installed for the experimentation. The novelty of the investigated technology is the possibility to achieve the production of thermal energy burning just the produced syngas and not directly the solid residues. This aspect allows to reduce the quantity of nitrogen released in the atmosphere by the exhaust flue gases and conveying it into the solid residues (ashes). A critical aspect of the research program was the optimization of the pretreatment (reduction of the water content) and the dimensional homogenization of the poultry waste before its energy recovery. This physical pretreatment allowed the reduction of the complexity of the matrix to be energy enhanced.Further to the real scale plant monitoring, a complete Aspen Plus v.8.0 model was also elaborated for the prediction of the quality of the produced synthesis gas as a function of both the gasification temperature and the equivalence ratio (ER).The model is an ideal flowchart using as input material just the homogenized and dried material.On the basis of the real monitored thermal power (equal to about 200kW average value in an hour) the model was used for the estimation of the syngas energy content (i.e. LHV) that resulted in the range of 3-5MJ/m3 for an equivalence ratio (ER) equal to 0.2.