Wear Mechanism Analysis of a New Rotary Shear Biomass Comminution System

Lee, Kyungjun; Lanning, David N; Lin, Lianshan; Cakmak, Ercan; Keiser, James R.; Qu, Jun

doi:10.1021/acssuschemeng.1c02542

Cited by 8 publications

(13 citation statements)

References 35 publications

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“…Its application to biomass encounters well-known difficulty of pulverization. 14) A most reasonable way to solve this problem is heat treatment that allows mild pyrolysis, i.e., torrefaction. Yu et al 15) and Wang et al 16) showed great improvement in pulverizability of biomass in terms of time or energy consumption by torrefaction at temperatures of 220-325°C.…”

Section: Introductionmentioning

confidence: 99%

Preparation of Formed Coke from Biomass by Sequence of Torrefaction, Binderless Hot Briquetting and Carbonization

et al. 2022

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This paper proposes a method of preparing high-strength formed coke from woody biomass without binder. Chipped and pre-dried Japanese cedar was heat-treated in an inert atmosphere (i.e., torrefied) at 225-325°C (T t ), pulverized to sizes in three different ranges, molded into briquettes (in the form of thick disk with diameter/thickness ≈ 2.5) at temperature up to 200°C by applying mechanical pressure of 128 MPa. The torrefied/briquetted cedar (TBC) was then converted into coke by heating to 1 000°C in an inert atmosphere at normal pressure. This process sequence enabled to prepare coke having indirect tensile strength (S t ) of 8-32 MPa, which was much higher than that without torrefaction, below 5 MPa. The torrefaction greatly improved pulverizability of the cedar, which was further promoted by increasing T t . S t of TBC and that of coke both increased as the particle sizes of TBC decreased, but this explained only a minor part of significant effect of T t on S t of the coke. S t was maximized at T t = 275°C regardless of the degree of pulverization. The T t effects on physicochemical properties of TBC and coke were investigated in detail. The difference in S t of coke by T t was mainly due to that in the increment of S t along the carbonization at 500-1 000°C. Fracture surfaces of the coke had particular morphologies that had been inherited from the original honeycomb structure of the cedar.

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Section: Introductionmentioning

confidence: 99%

Preparation of Formed Coke from Biomass by Sequence of Torrefaction, Binderless Hot Briquetting and Carbonization

et al. 2022

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“…Still, this finite element analysis made it possible to compare the contact pressures for different wood species and/or woodchip shapes, thereafter to provide useful information for the cutter blade design. For example, such an analysis suggested that the current square cutter tooth (DZ design) can break woodchips more efficiently than the previous sharp curvy tooth design in our earlier report (Lee et al, 2021). The improved performance of the DZ design has been validated on actual rotary shear systems at Utilizing this finite element simulation method, initial effort has been carried out for optimizing the DZ tooth design.…”

Section: Discussionmentioning

confidence: 95%

“…High contact pressure at these contact locations brings up continuum damage to the cutters and gradually downgrades their functionality. The wear mechanisms could include several types, such as abrasive wear, surface fatigue, erosive wear, and corrosion wear, as detailed in Lee et al, (2021). However, a high contact pressure on the cutter surface is expected to result in high tangential friction on the cutter surface and accumulate more heat under continuous working conditions.…”

Section: Discussionmentioning

confidence: 99%

“…However, the rotary shear unit experiences significant abrasive wear, especially when processing hard and dirty biomass, such as dirty logging residue and recycled railroad ties. Figure 2 shows an example of worn cutters, and more detailed worn component characterization can be found in our earlier report (Lee et al, 2021). The desired cutter life is in excess of 1,200 operating hours.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of Cutter–Woodchip Contact Pressure in a New Biomass Comminution System

et al. 2022

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A Crumbler® rotary shear system was recently developed to process fuel-grade woodchips into feedstocks having more uniform particle sizes for improved flowability and higher thermochemical output yield than a traditional hammer mill. It represents a significant innovation in the state of the art of biomass comminution equipment. However, the milling unit has experienced significant abrasive wear of the feeding teeth and cutters when processing hard and dusty feedstocks, such as logging residue and corn stover. Here, we present initial simulation results from a finite-element stress analysis of the rotary shear, which is used to investigate the dynamics of interaction between the cutters and woodchips. This is the first step for optimizing the cutter design to improve the system lifetime and processing efficiency, thus reducing downtime and improving overall productivity.

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“…Wibawa et al applied the above-mentioned sequence to coke production from softwood alone while inserting torrefaction before pulverization in consideration of the effectiveness of fine pulverization for increasing the coke strength, − difficulty of pulverization of biomass, and improvement of pulverizability of biomass by torrefaction. , Then, Wibawa et al prepared cokes with tensile strengths of 10–32 MPa without any additives. The strength of coke from pulverized softwood (<100 μm) with hot briquetting but without torrefaction was smaller than 5 MPa.…”

Section: Introductionmentioning

confidence: 99%

High-Strength Formed Coke from Torrefied Biomass and Its Blend with Noncaking Coal

et al. 2022

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In continuation of our previous study on production of high-strength metallurgical coke from torrefied softwood (cedar), we studied coke production from a mixture of torrefied cedar (TC) and noncaking coal by pulverization to sizes <100 μm, mixing, binderless hot briquetting, and carbonization. These sequential processes produced coke with a tensile strength of 5–17 MPa, which was equivalent to or greater than that of conventional coke (5–6 MPa), from TC-coal mixtures over the entire ranges of TC mass fraction in briquette of 0–100%, torrefaction temperature of 250–300 °C, and choice of coal (sub-bituminous or medium-volatile bituminous coal). The mixing of TC and coal hindered densification of coke due to hindrance of shrinkage of more-shrinkable TC-derived particles during the carbonization under many of the conditions. Nevertheless, positive synergy occurred in the coke strength at TC mass fractions of over 50%, where coal-derived particles were dispersed in the matrix of TC-derived particles, bonded to them during the carbonization, and behaved as a reinforcement of the matrix. The bonding between TC-derived and coal-derived primary particles was revealed by scanning electron microscopy. Copulverization of mixed TC and coal to sizes <40 μm before the briquetting gave cokes having strengths as high as 23–28 MPa. The fine pulverization increased the frequencies of mutual bonding of TC-derived particles and coal-derived particles and bonding between TC-derived and coal-derived particles per coke volume. The strength of coke from the TC-coal mixture generally followed volume-based additivity of strengths of cokes from TC and coal. This was realized by mixing primary particles of TC and coal within ≈10 μm scale or even smaller.

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Wear Mechanism Analysis of a New Rotary Shear Biomass Comminution System

Cited by 8 publications

References 35 publications

Preparation of Formed Coke from Biomass by Sequence of Torrefaction, Binderless Hot Briquetting and Carbonization

Preparation of Formed Coke from Biomass by Sequence of Torrefaction, Binderless Hot Briquetting and Carbonization

Investigation of Cutter–Woodchip Contact Pressure in a New Biomass Comminution System

High-Strength Formed Coke from Torrefied Biomass and Its Blend with Noncaking Coal

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