Pelletization of Sunflower Seed Husks: Evaluating and Optimizing Energy Consumption and Physical Properties by Response Surface Methodology (RSM)

Abstract

Pelletization is a significant approach for the efficient utilization of biomass energy. Sunflower seed husk is a common solid waste in the process of oil production. The novelty of this study was to determine the parameters during production of a novel pellet made from sunflower seed husk. The energy consumption (W) and physical properties (bulk density (BD) and mechanical durability (DU)) of the novel pellet were evaluated and optimized at the laboratory by using a pelletizer and response surface methodology (RSM) under a controlled moisture content (4%–14%), compression pressure (100–200 MPa), and die temperature (70–170 °C). The results show that the variables of temperature, pressure, and moisture content of raw material are positively correlated with BD and DU. Increasing the temperature and moisture content of raw materials can effectively reduce W, while increasing the pressure has an adverse effect on W. The optimum conditions of temperature (150 °C), pressure (180 MPa), and moisture content (12%) led to a BD of 1117.44 kg/m3, DU of 98.8%, and W of 25.3 kJ/kg in the lab. Overall, although the nitrogen content was slightly high, the novel manufactured pellets had excellent performance based on ISO 17225 (International Organization for Standardization of 17225, Geneva, Switzerland, 2016). Thus, sunflower seed husk could be considered as a potential feedstock for biomass pelletization.

Optimization of Microwave Coupled Hot Air Drying for Chinese Yam Using Response Surface Methodology

“…The following second-order polynomial of Equation 3was applied to fit the experimental data [34,35]:…”

Optimization of Cold Pressing Process Parameters of Chopped Corn Straws for Fuel

“…With the same method, Cui and Lu determined the straw compression process parameters and verified the accuracy of the regression model under the optimal compression conditions. Moreover, the prediction errors of the indices (mechanical durability, bulk density, energy consumption and tensile strength) were less than 5% [26,44]. In our study, the prediction errors of the indices are less than 2%, which are smaller compared with the above two studies.…”

“…The Box-Behnken design, which can study the influence degrees of the factors, interactions and quadratic items on indicators by variance analysis, was adopted to optimize process parameters [43]. The Box-Behnken design is often used to optimize straw compression process parameters [26,27,44,45]. Based on the Box-Behnken Design, twenty-four groups of combined tests involving different factors, and three groups of central tests were designed.…”

“…The optimal water content determined in our study fell within this range. With tensile strength, pellet density and specific energy consumption as the indices, Lu et al [26] optimized wood residue, bentonite, glycerol and compression load when the pressure maintenance time was 60 s. With the density immediately after pressing, the density at two weeks after pressing, and durability as the indices, Tumuluru et al [27] optimized die temperature, feedstock moisture content, compression pressure and hammer mill screen size when the stress maintenance time was 30 ± 2 s. Cui et al [44] optimized temperature, pressure and moisture content by using mechanical durability, bulk density, and energy consumption as the testing indices but did not give details about the stabilization method or time. In conclusion, when optimizing the straw compression process parameters, researchers often use a fixed time alone to maintain pressure or shape to prevent rebound among the existing studies.…”

Special Issue on “Bioenergy Systems, Material Management, and Sustainability”

“…This Special Issue, "Bioenergy Systems, Material Management, and Sustainability", encompasses a combination of contributed articles by a diverse set of worldwide experts in the Americas, Europe, and Asia, focusing on a multitude of concepts and topics. The following topics, along with the manuscript contributions, are addressed in this issue: Bio-based materials and processes [1,2], bioenergy systems optimization, advanced control for sustainability and state estimation [3][4][5][6][7], sustainability, life cycle assessment, and life cycle inventory analyses associated with biosystems and biofuels [8][9][10], sustainable management and valorization of organic/biomass waste, including energy production [11,12], and techno-economic analysis of novel routes for the sustainable utilization and reuse of biomass and waste [13]. Such topics are of great interest and critical relevance to the sustainable development of local, regional, national, and international communities.…”