Xiaoxu Song

Biofuel Manufacturing from Woody Biomass: Effects of Sieve Size Used in Biomass Size Reduction

Size reduction is the first step for manufacturing biofuels from woody biomass. It is usually performed using milling machines and the particle size is controlled by the size of the sieve installed on a milling machine. There are reported studies about the effects of sieve size on energy consumption in milling of woody biomass. These studies show that energy consumption increased dramatically as sieve size became smaller. However, in these studies, the sugar yield (proportional to biofuel yield) in hydrolysis of the milled woody biomass was not measured. The lack of comprehensive studies about the effects of sieve size on energy consumption in biomass milling and sugar yield in hydrolysis process makes it difficult to decide which sieve size should be selected in order to minimize the energy consumption in size reduction and maximize the sugar yield in hydrolysis. The purpose of this paper is to fill this gap in the literature. In this paper, knife milling of poplar wood was conducted using sieves of three sizes (1, 2, and 4 mm). Results show that, as sieve size increased, energy consumption in knife milling decreased and sugar yield in hydrolysis increased in the tested range of particle sizes.

Ultrasonic vibration-assisted pelleting of wheat straw: a predictive model for energy consumption using response surface methodology.

Cellulosic biomass can be used as a feedstock for biofuel manufacturing. Pelleting of cellulosic biomass can increase its bulk density and thus improve its storability and reduce the feedstock transportation costs. Ultrasonic vibration-assisted (UV-A) pelleting can produce biomass pellets whose density is comparable to that processed by traditional pelleting methods (e.g. extruding, briquetting, and rolling). This study applied response surface methodology to the development of a predictive model for the energy consumption in UV-A pelleting of wheat straw. Effects of pelleting pressure, ultrasonic power, sieve size, and pellet weight were investigated. This study also optimized the process parameters to minimize the energy consumption in UV-A pelleting using response surface methodology. Optimal conditions to minimize the energy consumption were the following: ultrasonic power at 20%, sieve size at 4 mm, and pellet weight at 1g, and the minimum energy consumption was 2.54 Wh.

Ultrasonic-Vibration-Assisted Pelleting of Cellulosic Biomass: Effects of Moisture Content

Cellulosic biomass is an important source for making biofuels. However, there are several barriers to cost-effective manufacturing of biofuels using cellulosic biomass. One such barrier is related to the high transportation cost due to the low density of cellulosic biomass. Pelleting of cellulosic biomass is one way to increase its density. This paper reports an experimental study on ultrasonic vibration-assisted pelleting of cellulosic biomass. The study was focused on the effects of moisture content (MC) on pellet density of three kinds of cellulosic biomass (wheat straw, switchgrass, and sorghum). The experimental results show that sorghum has the highest density with three levels of MC among these biomass materials. The highest density was found with sorghum of 20% MC.Copyright

Ultrasonic-vibration-assisted pelleting of wheat straw: an experimental investigation

Energy security, economy, environment sustainability are all driving the USA to develop alternative liquid transportation fuels that are domestically produced and environmental friendly. Bioethanol produced from cellulosic biomass can significantly reduce the use of fossil fuels in the transportation section. However, significant hurdles must be overcome for cost-effective manufacturing of cellulosic bioethanol. Cellulosic feedstocks have a low bulk density, causing high costs in transportation and storage. To address this problem, this paper reports an experimental investigation on ultrasonic-vibration-assisted (UV-A) pelleting of wheat straw. Results show that pellet density and durability were greatly improved with the assistance of ultrasonic vibration.

Effects of Screen Size on Biochemical Conversion of Big Bluestem Biomass for Biofuel Production

Biomass size reduction is the first step for biofuel production from cellulosic biomass through biochemical pathway, and it is usually performed on a mill with screen installed to control the size of the produced particles. The absence of in-depth knowledge about the effects of screen size throughout the biochemical conversion of cellulosic biomass makes it difficult to choose the screen size to conduct biomass size reduction to minimize the energy consumption on mills, maximize the cellulose recovery rate after pretreatment, and maximize the enzymatic hydrolysis efficiency. The objective of this work is to address this issue by generating new knowledge on the effects of screen size in these three processes: size reduction, pretreatment, and enzymatic hydrolysis in conversion of big bluestem biomass for biofuel production. Four screen sizes used in this study were 1, 2, 4, and 8 mm. It was found that using a larger screen size saved energy in biomass size reduction on a knife mill. Moreover, particles produced with larger screen sizes achieved higher cellulose recovery rate after pretreatment, higher enzymatic hydrolysis efficiency, and higher total sugar yield.

Energy consumption study in ultrasonic vibration-assisted pelleting of wheat straw for cellulosic biofuel manufacturing

Cellulosic biofuels are an alternative to petroleum-based transportation fuels. Ultrasonic vibration-assisted (UV-A) pelleting can increase density of cellulosic feedstocks, reduce transportation and storage costs, and increase sugar yield. However, energy consumption in UV-A pelleting has not been fully investigated. This paper presents an experimental study on energy consumption in UV-A pelleting of wheat straw. Effects of pelleting input variables (sieve size used in size reduction, pelleting pressure, ultrasonic power, and pellet weight) and size reduction machine type (knife milling versus hammer milling) are investigated. Results show that energy consumption in UV-A pelleting increased as sieve size, ultrasonic power, and pellet weight increased, and as pelleting pressure decreased. Energy consumption in UV-A pelleting of wheat straw particles processed by knife milling was higher than that in UV-A pelleting of those processed by hammer milling.

A physics-based temperature model for ultrasonic vibration-assisted pelleting of cellulosic biomass

Temperature in ultrasonic vibration-assisted (UV-A) pelleting of cellulosic biomass has a significant impact on pellet quality. However, there are no reports on temperature models for UV-A pelleting of cellulosic biomass. The development of a physics-based temperature model can help to explain experimentally determined relations between UV-A pelleting process variables and temperature, and provide guidelines to optimize these process variables in order to produce pellets of good quality. This paper presents such a model for UV-A pelleting of cellulosic biomass. Development of the model is described first. Then temperature distribution is investigated using the model, and temperature difference between the top and the bottom surfaces of a pellet is explained. Based on this model, relations between process variables (ultrasonic power and pelleting duration) and temperature are predicted. Experiments were conducted for model verification, and the results agreed well with model predictions.

Preliminary study on pretreatment of poplar wood for biofuel production

Background: The literature does not contain any systematic study on the effects of operating variables in dilute acid pretreatment of poplar wood. Results & discussion: This article reports experimental-determined effects of operating variables on energy consumption, water usage, sugar yield and pretreatment energy efficiency (PEE) in dilute acid pretreatment of poplar wood. As pretreatment time increased, energy consumption, water usage and sugar yield increased; PEE first increased and then decreased. As pretreatment temperature increased, energy consumption and water usage increased; sugar yield and PPE first increased and then became constant or decreased. As acid concentration increased, energy consumption and water usage did not change noticeably; sugar yield and PEE first increased and then decreased. Conclusion: Pretreatment conditions resulting in higher sugar yield in hydrolysis normally consumed more electric power in pretreatment.

Ultrasonic vibration-assisted (UV-A) pelleting of wheat straw: a constitutive model for pellet density.

Ultrasonic vibration-assisted (UV-A) pelleting can increase cellulosic biomass density and reduce biomass handling and transportation costs in cellulosic biofuel manufacturing. Effects of input variables on pellet density in UV-A pelleting have been studied experimentally. However, there are no reports on modeling of pellet density in UV-A pelleting. Furthermore, in the literature, most reported density models in other pelleting methods of biomass are empirical. This paper presents a constitutive model to predict pellet density in UV-A pelleting. With the predictive model, relations between input variables (ultrasonic power and pelleting pressure) and pellet density are predicted. The predicted relations are compared with those determined experimentally in the literature. Model predictions agree well with reported experimental results.

Ultrasonic Vibration-Assisted Pelleting of Cellulosic Biomass for Biofuel Production

Cellulosic biofuels have the potential to partially replace petroleum-based liquid transportation fuels. Several technical barriers hinder large-scale and cost-effective production of cellulosic biofuels, such as the low density of cellulosic biomass feedstocks (causing high transportation and storage cost), and the lack of efficient pretreatment technologies for cellulosic biomass. Ultrasonic vibration-assisted (UV-A) pelleting is a novel biomass feedstock preprocessing technology. UV-A pelleting is characterized by a combination of pelletizing and ultrasonic treatment into one process. This chapter reports experimental and theoretical investigations on UV-A pelleting of cellulosic biomass for biofuel production. It covers studies on pellet quality, pellet sugar yield, pelleting energy consumption, and pelleting temperature.