Impact of process conditions on the density and durability of wheat, oat, canola, and barley straw briquettes

J. S. Tumuluru,L. G. Tabil,K. L. Iroba,V. Meda,Y. Song

doi:10.1007/s12155-014-9527-4

Abstract

The present study is to understand the impact of process conditions on the quality attributes of wheat oat, barley, and canola straw briquettes. Analysis of variance indicated that briquette moisture content and initial density immediately after compaction and final density after 2 weeks of storage are strong functions of feedstock moisture content and compression pressure, whereas durability rating is influenced by die temperature and feedstock moisture content. Briquettes produced at a low feedstock moisture content of 9 % (w.b.) yielded maximum densities >700 kg/m3 for wheat, oat, canola, and barley straws. Lower feedstock moisture content of 110 °C and compression pressure >10 MPa minimized the briquette moisture content and maximized densities and durability rating based on surface plots observations. Optimal process conditions indicated that a low feedstock moisture content of about 9 % (w.b.), high die temperature of 120–130 °C, medium-to-large hammer mill screen sizes of about 24 to 31.75 mm, and low to high compression pressures of 7.5 to 12.5 MPa minimized briquette moisture content to 700 kg/m3. Durability rating >90 % is achievable at higher die temperatures of >123 °C, lower to medium feedstock moisture contents of 9 to 12 % (w.b.), low to high compression pressures of 7.5 to 12.5 MPa, and large hammer mill screen size of 31.75 mm, except for canola where a lower compression pressure of 7.5 to 8.5 MPa and a smaller hammer mill screen size of 19 mm for oat maximized the durability rating values.

Highlights

Lignocellulosic biomass includes agricultural residues, hardwood, and softwood, as well as dedicated biomass crops
The present results indicated that canola straw briquetted better at low feedstock moisture content and high die temperature to produce briquettes with high initial and final densities when compared to wheat, barley, and oat straws
Analysis of variance (ANOVA) indicated that die temperature was positively correlated with durability rating (DR) and did not significantly affect the unit density, while compression pressure was positively correlated with the briquette unit density

Summary

Introduction

Lignocellulosic biomass includes agricultural residues, hardwood, and softwood, as well as dedicated biomass crops. According to Kim and Dale [1], the estimated residue from crops such as corn, wheat, oats, rice, sorghum, and sugarcane throughout the world is approximately 1.5 billion metric tonnes. These residues constitute one of the most important biomass feedstocks in Canada due to its vast agricultural base. The Saskatchewan Ministry of Agriculture reported that the province of Saskatchewan alone produced 12.44 Mt of wheat, 5.63 Mt of canola, 4.59 Mt of barley, and 2.3 Mt of oats straws This abundant, inexpensive, and readily available biomass source indicates that Canada can play a significant role in the development of an environmentally benign bioenergy sector

Objectives

Methods

Results

Discussion

Conclusion