Effect of Compaction Pressure and Moisture Content on Post-Agglomeration Elastic Springback of Pellets

Abstract

Renewable energy sources (RES) represent an increasing share of global energy production. Biomass has the highest potential of all RES. Biomass is used to produce solid biofuels, liquid biofuels, and gaseous biofuels. One of the main directions of research on solid biofuels is to optimize the agglomeration process. The main factors determining the characteristics of the final product in the production of pellets are process and material parameters. Process parameters include compaction pressure, temperature, and geometry of the matrix channel. The parameters of the material are the type of biomass, moisture content, degree of fragmentation, and method of preparation of the material (e.g., drying). The process of pressure compaction is always associated with the negative phenomenon of elastic springback. The aim of this work was to check the influence of compaction pressure and material moisture content on the springback value. The research was conducted on three materials (giant miscanthus, cup plant and Virginia mallow), using four different pressures (131, 196, 262, and 327 MPa) and three different moisture levels (8, 11, and 14%). For all material springback values, the range was 9–16%. Statistical analysis showed that for all plants tested, the effects of compaction pressure and moisture content significantly affected the elastic springback value. Areas of high value springback in the pattern of process parameters were determined.

The Effect of Pressure on Compaction Process Parameters of Milk Thistle Straw With Binder

“…The studies of the compaction of milk thistle straw, compared to investigations carried out on other plant materials [16][17][18] confirmed the tendencies to change the density (Fig. 2) and mechanical strength of the briquette depending on the compaction pressure (Fig.…”

“…Milk thistle straw, on the other hand, is a by-product that can be used to produce solid biofuels. In the coming years, in connection with the new EU CAP for 2023-2027, In the context of the course of the process and the quality of the obtained product, the value of the applied compaction pressure is of exceptional importance [12][13][14][15][16], apart from the moisture content of the material [17][18][19][20]. The use of an inappropriate value of this parameter may, on the one hand, lead to excess energy consumption, and on the other hand, result in obtaining a briquette with inadequate strength properties.…”

Briquettes Made of Branches Wood of Three Mangrove Species Bonded by Starch Adhesive

“…The condition where the elasticity of a material decreases and its plasticity increases can be caused by temperature. The application of hot temperature during wood briquette production can reduce the springback phenomenon but not eliminate it [63]. The low density of wood briquettes is also associated with a decrease in density due to the loss of moisture and wood particles during pressing and drying, reducing the mass per unit volume of briquettes [64].…”

Influence of the Die Height on the Density of the Briquette Produced from Shredded Logging Residues

“…However, these authors created briquettes and pellets from materials characterized by homogeneity and much smaller particle sizes. The increase in the value of the relaxation coefficient along with the increase in temperature had a negative effect, which may be linked with a strong, excessive liquefaction of the resins contained in the biomass and the resulting loss of the possibility of binding (sticking) the biomass immediately after leaving the compacting die [54]. Moreover, during compaction, an intense evaporation of water and other substances contained in the biomass occurred.…”