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Dissertation/Thesis Abstract

Optimization of Parameters for the Densification (Pelletization) of Cereal Crop Residues and Feasibility Study of Pellet Plant Development in the State of Arkansas from Economic Perspective
by Thapa, Shyam, Ph.D., Arkansas State University, 2017, 151; 10640883
Abstract (Summary)

Conventional cereal crop residues, namely, rice ( Oryza sativa L.), corn (Zea mays L.), and wheat (Triticum aestivum L.) is very abundant and readily available widely. It has been a nuisance to agronomic producers to manage these immense “so-called wastes”. The Energy Independence and Security Act (EISA) promulgated by the United States and The EU’s renewable energy directive mandated the substantial incorporation of renewable energy in their final energy consumption. These led to the increase in R&D’s on biomass and bioenergy products in the United States as well.

Hammer mill grinds of different cereal crop residues, rice, wheat, and corn, sieved through 5"/64 , 1"/8 , and 5"/32 hammer mill screen sizes (details in chapter 3) are mixed with different binders namely gelatin, wheat gluten, and dry milk at 1:10, 1:15, and 1:20 proportions (Chapter 4). Applying Taguchi-Grey relational analysis for four factors with three levels each, optimal operating level for the control factors based on multi-response characteristics was determined. The multi-responses used for the study are bulk density, durability, compressive strength, and gross heating values. Binder ratio was most influential in determining pellet quality. Binder type was next influential factor. The combination of factor levels A1B1C3D 1 was found to be optimal conditions for pelletization as final results were confirmed with tests.

The pelletization parameters for making better quality composite pellets were also investigated (in Chapter V). The same Taguchi –Grey relational analysis method was used for optimization. The process (material variables) parameters those are material type, particle size or grind size, binder type, and proportion of binder were closely studied using L9 Taguchi orthogonal array. Binder ratio (blending ratio) has most significant impact, and particle size (Hammer mill grind) has second greatest impact on pelleting composite wastes. Tests conducted employing optimal conditions (A3B3C2D1) has confirmed that better pellets were produced compared with the hypothesized conditions.

The cost analysis using Invest for excel was carried out in order to study the feasibility of solid biofuel project. The biomass assessment using Biopower Atlas and associated GIS tools from NREL demonstrated that the State of Arkansas has agricultural residues sufficient to support 50 kilotons and 66 kilotons biomass pellet plant. Economy of scale effect can be observed when comparing 50 kilotons and 66 kilotons pellet mill. Gelatin-wheat pellet mill at 50 kiloton and even 66 kilotons were predicted to be unprofitable at the current stage. However, analysis results showed pellet produced from pine shavings – wheat residue blends is profitable. Crop residues are promising resources due to its wide distribution and availability. It can be termed as a “Backstop resource” because it is renewable and will be economically viable option as the price of oil and gas become expensive.

Indexing (document details)
Advisor: Engelken, Robert D.
Commitee: Green, Steven, Guha, Gauri-Shankar, Humphrey, Bill, Humphrey, Kevin
School: Arkansas State University
Department: Environmental Science
School Location: United States -- Arkansas
Source: DAI-B 79/03(E), Dissertation Abstracts International
Subjects: Bioengineering, Environmental economics, Agricultural economics, Agricultural engineering, Environmental science
Keywords: Agricultural residue, Bio-composite, Feasibility study, Pelletization, Solid biofuel, Taguchi-Grey relational analysis
Publication Number: 10640883
ISBN: 978-0-355-50211-4
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