Torrefaction kinetics of almond and walnut shells

Chiou, Bor‐Sen; Cao, Trung; Valenzuela-Medina, Diana; Bilbao‐Sainz, Cristina; Avena‐Bustillos, Roberto J.; Milczarek, Rebecca R.; Du, Wenjie; Glenn, Greg; Orts, William J.

doi:10.1007/s10973-017-6721-6

Cited by 23 publications

(8 citation statements)

References 37 publications

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“…The values obtained were in line with the values presented in previous studies, namely those by Demirbaş (2002) for almond husks [88], by Torreiro et al (2020) for kiwifruit pruning [89], by San José et al (2013) for vine pruning [90], by Nunes et al (2020) for olive pomace [91], for the pine chip [92], and Sá et al (2020) [93] For the same materials, after being subjected to the heat treatment process by torrefaction, there was an expected increase in the fixed carbon content, as described in several previous works for biomass materials-namely, the works of Faizal et al (2018), Lau et al (2018), and Conag et al (2017) [94][95][96]-with the smallest percentage increase corresponded to the increase seen in vine pruning, which stood at 63.57%, while the remaining materials had an average of 70.51 ± 3.96%. These values were also in line with the values obtained in previous studies, namely those developed by Chiou et al (2018) for almond shells [97], by Margaritis et al (2020) for vine pruning [98], by Volpe et al (2015) for olive pomace [99], Phanphanich and Mani (2011) for pine chip [35], and Sá et al (2020) [93] In the case of kiwifruit pruning, the only works found in the bibliographic research referred to its characterization as a fuel after drying, without any other type of thermal processing such as torrefaction (see, e.g., the works developed by Dyjakon and García-Galindo (2019) or Boumancher et al (2019) [100,101]). With reference to works carried out on the application of thermochemical conversion technologies (in this case, pyrolysis), we found a work developed by Rene et al (2020), which was carried out with the aim of studying the production of biochar from kiwifruit pruning employed as an amendment aiming to evaluate its remediation potential in smelter-and mining-contaminated soils [102]; therefore, the data from this study was not used for comparison, as the methodological assumptions related to sample preparation ...…”

Section: Discussionsupporting

confidence: 93%

Torrefied Biomass as an Alternative in Coal-Fueled Power Plants: A Case Study on Grindability of Agroforestry Waste Forms

Nunes

2020

Clean Technol.

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The use of biomass as a renewable energy source is currently a reality, mainly due to the role it can play in replacing fossil energy sources. Within this possibility, coal substitution in the production of electric energy presents itself as a strong alternative with high potential, mostly due to the possibility of contributing to the decarbonization of energy production while, at the same time, contributing to the circularization of energy generation processes. This can be achieved through the use of biomass waste forms, which have undergone a process of improving their properties, such as torrefaction. However, for this to be viable, it is necessary that the biomass has a set of characteristics similar to those of coal, such that its use may occur in previously installed systems. In particular, with respect to grindability, which is associated with one of the core equipment technologies of coal-fired power plants—the coal mill. The objective of the present study is to determine the potential of certain residues with agroforestry origins as a replacement for coal in power generation by using empirical methods. Selected materials—namely, almond shells, kiwifruit pruning, vine pruning, olive pomace, pine woodchips, and eucalyptus woodchips—are characterized in this regard. The materials were characterized in the laboratory and submitted to a torrefaction process at 300 °C. Then, the Statistical Grindability Index and the Hardgrove Grindability Index were determined, using empirical methods derived from coal analysis. The results obtained indicate the good potential of the studied biomasses for use in large-scale torrefaction processes and as replacements for coal in the generation of electrical energy. However, further tests are still needed, particularly relating to the definition of the ideal parameters of the torrefaction process, in order to optimize the grindability of the materials.

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Section: Discussionsupporting

confidence: 93%

Torrefied Biomass as an Alternative in Coal-Fueled Power Plants: A Case Study on Grindability of Agroforestry Waste Forms

Nunes

2020

Clean Technol.

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“…The results indicated that torrefaction improved several fuel characteristics, making the sugarcane bagasse suitable for both domestic and industrial applications. Other possibilities of torrefaction have been applied and studied, such as for microalgae [86], Black Lilac (Sambucus nigra L.) [87], Prosopis juliflora [88], corncob [89], almond and walnut shells [90], bamboo sawdust [91], rice husk [92], and cotton stalk [93], among many others [94].…”

Section: Future Perspectives and Research Developmentsmentioning

confidence: 99%

Future Perspectives of Biomass Torrefaction: Review of the Current State-Of-The-Art and Research Development

et al. 2018

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Abstract:The growing search for alternative energy sources is not only due to the present shortage of non-renewable energy sources, but also due to their negative environmental impacts. Therefore, a lot of attention is drawn to the use of biomass as a renewable energy source. However, using biomass in its natural state has not proven to be an efficient technique, giving rise to a wide range of processing treatments that enhance the properties of biomass as an energy source. Torrefaction is a thermal process that enhances the properties of biomass through its thermal decomposition at temperatures between 200 and 300 • C. The torrefaction process is defined by several parameters, which also have impacts on the final quality of the torrefied biomass. The final quality is measured by considering parameters, such as humidity, heating value (HV), and grindability. Studies have focused on maximizing the torrefied biomass' quality using the best possible combination for the different parameters. The main objective of this article is to present new information regarding the conventional torrefaction process, as well as study the innovative techniques that have been in development for the improvement of the torrefied biomass qualities. With this study, conclusions were made regarding the importance of torrefaction in the energy field, after considering the economic status of this renewable resource. The importance of the torrefaction parameters on the final properties of torrefied biomass was also highly considered, as well as the importance of the reactor scales for the definition of ideal protocols.

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“…The whole torrefaction process has been divided into three sections: feedstock transportation and handling, torrefaction and milling torrefied biomass. The torrefaction parameters assumed for process simulation are based on literature reports [17,20,21]. The energy of the byproduct (torgas) has been recovered and considered in the calculation of utility costs by the software.…”

Section: Process Design and Modeling Descriptionsmentioning

confidence: 99%

“…The condensate yields and gross calorific values increased with torrefaction severity. They also examined the effect of inorganic species on the torrefaction kinetics of almond shells using thermogravimetric analysis, and demonstrated that the kinetic model with two consecutive parallel reactions exhibited the best fit to experimental data [21]. Lin and Zheng [22] reported that GHG emissions were reduced by 58.5%-82.5% with the combustion of the biochar obtained from the torrefaction process compared with the combustion of coal.…”

Section: Introductionmentioning

confidence: 99%

Torrefaction of almond shell as a renewable reinforcing agent for plastics: techno-economic analyses and comparison to bioethanol process

Liu

Baral

Liu

et al. 2023

Environ. Res.: Infrastruct. Sustain.

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The U.S. state of California alone produced nearly 3.5 billion kilograms of almonds accounting for approximately 84% of the world’s almond production. This generates about 2.58 million metric tons of almond residues. The almond shells are currently either burned to generate power or disposed of in the landfill. Valorizing almond shells and hulls provides an opportunity to replace petroleum-derived products and divert organic material from landfills. Here we demonstrate a detailed techno-economic analysis of an almond shell torrefaction process capable of utilizing the 520,000 metric tons of almond shells produced annually in California. Our process also includes preprocessing the torrefied biomass to exploit it as a reinforcing agent for plastics. We further compared the revenue generated from the torrefied biomass and bioethanol derived from the same amount of almond shells. We considered three different torrefaction facility scales to evaluate trade-offs between economies of scale at the facility and trucking costs to deliver almond shells. A facility that takes in 200,000 metric tons (MT)/year of almond shells results in lower per-unit-output basis capital and operating cost relative to other smaller scales of torrefaction facility, including 10,000 MT/year and 50,000 MT/year, considered for analysis in this study. The large-sale facility results in the minimum selling price of the torrefied biomass of $311.4/MT. An analogous techno-economic analysis on converting almond residues into bioethanol is also investigated. The minimum selling price of almond shells derived ethanol ($1.71/kg) is higher than corn ($0.48/kg) or cellulosic biomass ($0.88/kg) derived ethanol. Compared to the bioethanol route, the torrefied almond shells result in 3 times more revenue if it is utilized as a reinforcing agent for plastics.

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Torrefaction kinetics of almond and walnut shells

Cited by 23 publications

References 37 publications

Torrefied Biomass as an Alternative in Coal-Fueled Power Plants: A Case Study on Grindability of Agroforestry Waste Forms

Torrefied Biomass as an Alternative in Coal-Fueled Power Plants: A Case Study on Grindability of Agroforestry Waste Forms

Future Perspectives of Biomass Torrefaction: Review of the Current State-Of-The-Art and Research Development

Torrefaction of almond shell as a renewable reinforcing agent for plastics: techno-economic analyses and comparison to bioethanol process

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