Optimizing hammer mill performance through screen selection and hammer design

Yancey, Neal; Wright, Christopher T.; Westover, Tyler L.

doi:10.4155/bfs.12.77

Cited by 47 publications

(26 citation statements)

References 24 publications

(13 reference statements)

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“…The SER and SFU for grinding bales were greater than for baling of chopping. The SFU reported here is in the same range as that reported for SWG and CS bales when throughputs were similar to those found here [40]. When LRBe throughputs varied from 10 to 45 Mg·h −1 , SFU of tub grinding with screen sizes similar of those used here were 5.9 to 9.7 L·Mg −1 for CS and 2.6 to 3.4 L·Mg −1 for NTG [41].…”

Section: Bale Grinding and Shreddingsupporting

confidence: 85%

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Energy Requirements for Biomass Harvest and Densification

Shinners

Friede

2018

Energies

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This research quantified the unit and bulk density of several biomass crops across a variety of harvest and processing methods, as well as the energy and fuel requirements for these operations. A load density of approximately 240 kg·m −3 is needed to reach the legal weight limit of most transporters. Of the three types of balers studied, only the high density (HD) large square baler achieved this target density. However, the specific energy and fuel requirements increased exponentially with bale density, and at the maximum densities for corn stover and switchgrass, the dry basis energy and fuel requirements ranged from 4.0 to 5.0 kW·h·Mg −1 and 1.2 to 1.4 L·Mg −1 , respectively. Throughputs of tub grinders when grinding bales was less than any other harvesting or processing methods investigated, so specific energy and fuel requirements were high and ranged from 13 to 32 kW·h·Mg −1 and 5.0 to 11.3 L·Mg −1 , respectively. Gross size-reduction by pre-cutting at baling increased bale density by less than 6% and increased baling energy requirements by 11% to 22%, but pre-cut bales increased the tub grinder throughput by 25% to 45% and reduced specific fuel consumption for grinding by 20% to 53%. Given the improvement in tub grinder operation, pre-cutting bales should be considered as a means to increase grinder throughput. Additional research is needed to determine the energy required to grind high density pre-cut bales at high throughputs so that better estimates of total energy required for a high density bale system can be made. An alternative bulk feedstock system was investigated that involved chopping moist biomass crops with a precision-cut forage harvester, compacting the bulk material in a silo bag, and then segmenting the densified material into modules optimized for efficient transport. The specific fuel use for chopping and then compacting biomass crops in the silo bag ranged from 1.6 to 3.0 L·Mg −1 and 0.5 to 1.3 L·Mg −1 , respectively. At the proposed moistures, the compacted density in the silo bags was sufficient to achieve weight-limited transport although there would be less dry matter (DM) shipped than with the high density dry bale system. Additional development work is needed to create transportable modules from the compacted silo bag. The overall results of this research will allow more accurate estimates of biomass logistics costs based on product density and energy expenditures.

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Section: Bale Grinding and Shreddingsupporting

confidence: 85%

“…Previous research on tub grinding biomass has been done with LRBes or CD LSBes and the reported throughputs and SFU varied considerably across these studies [39][40][41][42]. Based on the results here and those of previous research, only estimates of SFU to grind HD LSBes can be made.…”

Section: Discussionmentioning

confidence: 84%

Energy Requirements for Biomass Harvest and Densification

Shinners

Friede

2018

Energies

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“…However, crushing degree of the olive paste depends on the energy transferred to the olives during the crushing operation, which is mainly affected by the retention time inside the hammer mill . We propose that open area (i.e., the percentage of the area of holes over the total area of the screen) should be also considered in screen characterization, since it has proven to have an effect on the retention time and crushing degree during the processing of other matrixes . Herein, we built upon our earlier work to study the impact of sieve design (screen size and open area) and rotor speed on extraction efficiency, quality and minor components composition of olive oil at a laboratory scale.…”

Section: Introductionmentioning

confidence: 99%

Hammer Mill Sieve Design Impacts Olive Oil Minor Component Composition

Polari

Wang

2019

Euro J Lipid Sci & Tech

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Crushing of the olive fruit is the first operation for olive oil extraction. The hammer mill is one of the most popular devices used in modern facilities due to its easy maintenance and high product output. The effect of hammer mill rotor speed and sieve design, including screen size and screen open area on extraction yield, overall quality and minor component composition, is evaluated at the laboratory scale. Quality parameters such as free fatty acids (FFA), peroxide value (PV), and UV absorbances (K232, K270, and ΔK) are unaltered by crushing parameters. Extraction efficiency, chlorophylls content, total phenol content, 3,4‐DHPEA‐EDA, and p‐HPEA‐EDA increase with faster hammer mill rotor speed and smaller screen size. Volatiles (E)‐2‐hexenal, hexanal, 1,5‐hexadiene‐(3,4)‐diethyl, 3‐ethyl‐1,5‐octadiene, and (E)‐2‐hexenol are only affected by screen size. Screen open area is found to be a relevant factor regarding extraction efficiency, chlorophylls, total, and individual phenols as well as the volatile compounds 1,5‐hexadiene (3,4)‐diethyl, 3‐ethyl‐1,5‐octadiene, hexanal, and (E)‐2‐hexenal. Practical Application: It is found that screen open area is a relevant factor regarding extraction efficiency, chlorophylls, total and individual phenols and volatile compounds, in addition to the screen size and rotor speed. This is useful information for millers who are interested in optimizing extraction efficiency as well as the minor compounds of extra virgin olive oil. Hammer mill sieve design impacts extraction efficiency, chlorophylls, total and individual phenols, and the volatile compounds during laboratory‐scale extraction of olive oil.

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“…There, it was processed using the pilot-scale feedstockhandling unit operated by INL as described by Yancey et al [16] and hammer milled to pass through a 1.9 cm (0.75 in.) round rejection screen.…”

Section: Feedstockmentioning

confidence: 99%

Development and characterization of a high-solids deacetylation process

Shekiro

Chen

Smith

et al. 2016

Sustain Chem Process

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Background: Dilute-acid pretreatment has proven to be a robust means of converting herbaceous feedstock to fermentable sugars. However, it also releases acetic acid, a known fermentation inhibitor, from acetyl groups present in the biomass. A mild, dilute alkaline extraction stage was implemented prior to acid pretreatment to separate acetic acid from the hydrolysate sugar stream. This step, termed deacetylation, improved the glucose and xylose yields from enzymatic hydrolysis and ethanol yields from fermentation of the sugars relative to the control experiments using dilute-acid pretreatment of native corn stover without deacetylation. While promising, deacetylation as it was historically practiced is conducted at low solids loadings, and at fixed conditions. Thus, many questions have been left unanswered, including the relationship between sodium hydroxide and solids loading, and acetate and xylan solubilization, as well as the impact of temperature and residence time on the process efficacy.Results: A central composite experiment was designed to evaluate the impact of solids loading, sodium hydroxide loading, reaction time and temperature during deacetylation on the acetate and xylan solubilization of corn stover. Using the ANOVA test, it became apparent that neither of the responses was significantly impacted by the solids loading, while the reaction time was a minor factor-the responses were largely driven by reaction temperature and the sodium hydroxide loading. Based on the results, we successfully demonstrated the ability to transition the low-solids (10 % w/w) deacetylation process to a higher-solids process (30 % w/w) with minimal impact on the ability to extract acetate from biomass. Conditions were selected to minimize xylose loss during deacetylation, while also removing 70 % of acetyl groups. The impact of selected conditions on the enzymatic hydrolysis and fermentation was further investigated. Conclusions:Evaluation of the whole-process impact demonstrated that despite the upfront reduction in carbohydrate loss during deacetylation, the overall process sugar yields were depressed by the high-solids, low alkali process relative to the historical control. Consequently, ethanol titers were reduced, though strong fermentation performance was still observed, indicating that 70 % acetate removal is sufficient to depress acetic acid concentrations to a level that does not substantially inhibit ethanol fermentation by rZymomonas.

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Optimizing hammer mill performance through screen selection and hammer design

Cited by 47 publications

References 24 publications

Energy Requirements for Biomass Harvest and Densification

Energy Requirements for Biomass Harvest and Densification

Hammer Mill Sieve Design Impacts Olive Oil Minor Component Composition

Development and characterization of a high-solids deacetylation process

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