In accordance to European Regulation (91/676/CEE), which limits the amount of nitrogen available for distribution on agricultural lands that fall in nitrate vulnerable zones (NVZ), livestock farms have to find alternative solution for manure management. In order to avoid water pollution several technologies have been developed and one of these is solid-liquid separation allowing to obtain a solid fraction and a clarified liquid. As a consequence of low bulk density, the solid fraction is very difficult to handle, transport and store. One possible solution to these problems is densification of biomass materials into pellets, briquettes or cubes. Two techniques are used for size enlargement of particulate materials: tumble agglomeration and pressure agglomeration. This paper reports the results of a first investigation on physical behavior of swine solid fraction during pressure agglomeration in a cylindrical die. The investigation was carried out using a hydraulic press prototype equipped with measuring sensors to record the variables influencing the densification process. Two different types of materials have been used: swine solid fraction derived from mechanical separation and compost obtained by mixing the first material with wood chips. The initial bulk density values (?0) were 250 kg.m-3 and 450 kg.m-3 for the first and the second material respectively. Seven levels of compaction pressure between 20 MPa and 80 MPa and two application times for each pressure level (10 and 40 s) were considered. During the pressure agglomeration the density increase was distinctly nonlinear and different in the two materials. At the upper limit of this pressure range the density was about 1337 kg.m-3 and 1129 kg.m-3 for swine solid fraction and compost respectively. The tests carried out showed that, although there were significant differences between the final density values obtained at different pressure levels, the densification process efficiency decreased with increasing applied pressure.
Density-pressure relatinship in densification of swine solid fraction
Pampuro N;Facello A;Cavallo E
2012
Abstract
In accordance to European Regulation (91/676/CEE), which limits the amount of nitrogen available for distribution on agricultural lands that fall in nitrate vulnerable zones (NVZ), livestock farms have to find alternative solution for manure management. In order to avoid water pollution several technologies have been developed and one of these is solid-liquid separation allowing to obtain a solid fraction and a clarified liquid. As a consequence of low bulk density, the solid fraction is very difficult to handle, transport and store. One possible solution to these problems is densification of biomass materials into pellets, briquettes or cubes. Two techniques are used for size enlargement of particulate materials: tumble agglomeration and pressure agglomeration. This paper reports the results of a first investigation on physical behavior of swine solid fraction during pressure agglomeration in a cylindrical die. The investigation was carried out using a hydraulic press prototype equipped with measuring sensors to record the variables influencing the densification process. Two different types of materials have been used: swine solid fraction derived from mechanical separation and compost obtained by mixing the first material with wood chips. The initial bulk density values (?0) were 250 kg.m-3 and 450 kg.m-3 for the first and the second material respectively. Seven levels of compaction pressure between 20 MPa and 80 MPa and two application times for each pressure level (10 and 40 s) were considered. During the pressure agglomeration the density increase was distinctly nonlinear and different in the two materials. At the upper limit of this pressure range the density was about 1337 kg.m-3 and 1129 kg.m-3 for swine solid fraction and compost respectively. The tests carried out showed that, although there were significant differences between the final density values obtained at different pressure levels, the densification process efficiency decreased with increasing applied pressure.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
