Direct mechanical energy measures of hammer mill comminution of switchgrass, wheat straw, and corn stover and analysis of their particle size distributions

Bitra, Venkata S.P.; Womac, A. R.; Chevanan, Nehru; Miu, Petre I.; Igathinathane, C.; Sokhansanj, Shahab; Smith, David R.

doi:10.1016/j.powtec.2009.02.010

Cited by 175 publications

(123 citation statements)

References 17 publications

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“…The milling of switchgrass, wheat straw and corn stover in a hammermill equipped with a 3.2 mm mesh screen has been studied by Bitra et al [23]. Two hammer types and five rotation speeds of the rotor are compared on an electrical consumption basis, considering total specific energy and effective specific energy (total energy from which the empty consumption of the hammermill has been taken away).…”

Section: Biomass Grindingmentioning

confidence: 99%

Von Rittinger theory adapted to wood chip and pellet milling, in a laboratory scale hammermill

Temmerman

Jensen

Hebert

2013

Biomass and Bioenergy

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This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. b s t r a c tThe study draws upon the milling theories developed for the ore processing industry (Von Rittinger, Kick and Bond theories) in order to define a method for characterising wood chip and pellet energy consumption during milling.Energy consumption during wood milling depends on three main factors: the material moisture content, the particle size difference between the feed and the milled product, and the material itself. The latter may be characterised by a single parameter based on an adaptation of Von Rittinger's constant.A relation characterising wood pellet energy consumption as a function of the particle size distribution of the pellet ingredients and the milled pellets is proposed. This is characteristic of each type of pellet for each moisture content value considered. ª 2013 Elsevier Ltd. All rights reserved. IntroductionThe international drive to cut greenhouse gas emissions, carbon dioxide in particular, has prompted many electricity producers to convert some of their pulverized coal or gas plants to biomass co-combustion plants. There is even an example of a plant being converted to run on wood pellets exclusively [1]. Adding biomass to fossil fuels has a number of advantages. From an environmental point of view using biomass reduces fossil CO 2 , SO x and NO x emissions rapidly. Moreover, from a technical point of view boiler efficiency increases and lower fuel cost makes the plants more costeffective [2e4]. Some power plants use biomass (generally wood-derived) in pulverized form, which requires milling before use to produce wood particles that have the requisite aerodynamic and combustion properties to be used in the process. In such systems the characteristics of the biomass particles are vitally important as they impact upon feeding, combustion kinetics, the combustion residue volume and the hearth temperature [5e8].For most such co-combustion units the specification requires all of the particles to pass through a 6.34 mm mesh and the majority to pass through a 3 mm mesh [4]. However, some consumers sometimes apply stricter specifications [1,9].Grinding chips and pellets can pose problems, however. There is a lack of data for dimensioning the mill when designing power plant supply circuits. Conversely, in existing circuits, acceptance of new materials requires true scale pilot projects. More generally, little research appears to have been done overall into fine milling of biomass. Available online at www.sciencedirect.com ht tp://www.elsevier.com/locate/biombioe b i o m a s s a n d b i o e n e r g y 5 6 ( 2 0 1 3 ) 7 0 e8 1 0961-9534/$ e see front matter ª

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Section: Biomass Grindingmentioning

confidence: 99%

Von Rittinger theory adapted to wood chip and pellet milling, in a laboratory scale hammermill

Temmerman

Jensen

Hebert

2013

Biomass and Bioenergy

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“…Higher specific energy consumption was recorded for groundnut shell at the same screen aperture. However, in grinding of biomaterials, factors such as difference in moisture content, and fibrous nature of groundnut shell might have contributed to this (Himmel et al, 1985;Schnatz et al, 2000;Mani et al, 2004;Djantou et al, 2007;Bitra et al, 2009;Hess et al, 2009;and Miaoa et al, 2011).…”

Section: Energy Requirement For Grindingmentioning

confidence: 99%

Measurement of energy requirements for size reduction of palm kernel and groundnut shells for downstream bioenergy generation

Nnaemeka¹,

MacManus²

2016

J. Eng. Technol. Res.

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The study estimated the amount of energy required for grinding palm kernel shell and groundnut shell using laboratory hammer mill and also characterize their ground physical properties. The material type and hammer mill screen aperture significantly influenced the energy requirement for grinding the two materials. For a given screen aperture size, groundnut shell consumed more energy than palm kernel shell. The energy relationship with hammer mill screen exhibited a second order polynomial form. Within the same hammer mill screen aperture range, the energy requirements for palm kernel and groundnut shell were considerably lower than most grass based biomass or straw. The bulk and particle density of groundnut shell decreased with increased geometric mean diameter while that of palm kernel shell increased with geometric mean. The two materials ground exhibited a lognormal particle size distribution at hammer mill screen of 5 and 3 mm, while 0.8 mm screen aperture exhibited a normal size distribution. The total particle and surface area estimate in a charge was sensitive to the screen sizes. Energy equations: Ratzinger's, Kicks and Bond's were used to investigate the results of the biomass comminution with Ratzinger's equations showing a higher R 2 value for palm kernel shell while Kick's equation showed a higher R 2 value for groundnut shell.

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“…Leaving the substrate in bale form would decrease the energy input used in preparing the substrate for conversion. Size reduction is an energy intensive process and could consume up to one-third of the energy input in the entire biofuel conversion process (Bitra et al 2009). Bitra et al (2009) tested the total specific energy input calculations to grind switchgrass as a function of screen size, mass feed rate, and rotor speed.…”

Section: A B C Dmentioning

confidence: 99%

“…Size reduction is an energy intensive process and could consume up to one-third of the energy input in the entire biofuel conversion process (Bitra et al 2009). Bitra et al (2009) tested the total specific energy input calculations to grind switchgrass as a function of screen size, mass feed rate, and rotor speed. Increasing grinding speed from 250 to 500 rpm increased energy inputs 33% for all screen sizes tested.…”

Section: A B C Dmentioning

confidence: 99%

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The Confounding Effects of Particle Size and Substrate Bulk Density on Phanerochaete chrysosporium Pretreatment of Panicum virgatum

Hickman¹,

Nokes²,

Sympson³

et al. 2016

BioResources

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Phanerochaete chrysosporium treatment is less effective as a biological pretreatment on feedstock with larger particle sizes. We hypothesized that the improved effectiveness of the pretreatment when smaller particle sizes are used may be due to the inherently higher bulk density with smaller particle sizes. The effects of substrate bulk density and particle size on the efficacy of P. chrysosporium pretreatment of switchgrass (Panicum virgatum) was tested experimentally. Phanerochaete chrysosporium was grown on senesced switchgrass (2 different particle sizes) with various bulk densities. In all treatments, the fungal-pretreated samples released more glucose during enzymatic saccharification than the control sample. Substrate bulk density was a statistically significant factor in explaining the variation in the amount of glucose released per gram of substrate used. However, the particle size was not found to be a significant factor. On-farm switchgrass pretreatment may not require particle size reduction if the switchgrass is supplied in high-density bales.

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Direct mechanical energy measures of hammer mill comminution of switchgrass, wheat straw, and corn stover and analysis of their particle size distributions

Cited by 175 publications

References 17 publications

Von Rittinger theory adapted to wood chip and pellet milling, in a laboratory scale hammermill

Von Rittinger theory adapted to wood chip and pellet milling, in a laboratory scale hammermill

Measurement of energy requirements for size reduction of palm kernel and groundnut shells for downstream bioenergy generation

The Confounding Effects of Particle Size and Substrate Bulk Density on Phanerochaete chrysosporium Pretreatment of Panicum virgatum

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