https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=2232&context=usdaarsfacpub

Qualitative and quantitative analysis of lignocellulosic biomass using infrared techniques: A mini-review

Developing uniformly formatted, densified feedstock from lignocellulosic biomass is of interest to achieve consistent physical properties such as size and shape, bulk and unit density, and durability, which significantly influence storage, transportation and handling characteristics, and, by extension, feedstock cost and quality. A variety of densification systems are considered for producing a uniform format feedstock commodity for bioenergy applications, including (i) pellet mill, (ii) cuber, (iii) screw extruder, (iv) briquette press, (v) roller press, (vi) tablet press, and (vii) agglomerator. Each of these systems has varying impacts on feedstock chemical and physical properties, and energy consumption. This review discusses the suitability of these densification systems for biomass feedstocks and the impact these systems have on specific energy consumption and end-product quality. For example, a briquette press is more flexible in terms of feedstock variables where higher moisture content and larger particles are acceptable for making good quality briquettes; or among different densification systems, a screw press consumes the most energy because it not only compresses but also shears and mixes the material. Pre-treatment options like pre-heating, grinding, steam explosion, torrefaction, and ammonia fiber explosion (AFEX) can also help to reduce specific energy consumption during densification and improve binding characteristics. Binding behavior can also be improved by adding natural binders, such as proteins, or commercial binders, such as lignosulfonates. The quality of the densified biomass for both domestic and international markets is evaluated using PFI (United States standard) or CEN (European standard). Published in 2011 by John Wiley & Sons, Ltd

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https://onlinelibrary.wiley.com/doi/pdf/10.1002/bbb.324

A review of biomass densification systems to develop uniform feedstock commodities for bioenergy application.

Thermal analysis and devolatilization kinetics of cotton stalk, sugar cane bagasse and shea meal under nitrogen and air atmospheres.

This review article introduces recent technical and scientific reports in terms of near infrared (NIR) spectroscopy in the wood and paper science and industry, where interest has increased during the last couple decades. Many researchers reported the NIR technique was useful to detect multi information in both chemical and physical properties of wood materials, although it was widely used in a state where characteristic cellular structure was retained. In the case of application of NIR spectroscopy to pulp and paper, many publications have pointed out its high probability as online measurement techniques during paper‐making process control. Arguments referred to the importance of NIR spectroscopy as fundamental and applied research of wood and paper.

A Review of Recent Near Infrared Research for Wood and Paper

Production and utilization of fuel pellets from biomass: A review

Effects of raw material moisture content, densification pressure and temperature on some properties of Norway spruce pellets

Char yield, char combustion time and char combustion rate of pellets made from different tree parts of Norway spruce and industrially made stem wood pellets of Norway spruce and Scots pine were studied. The pellets were incinerated in a laboratory scale oven at various temperatures, gas flows and oxygen concentrations. It was found that the combustion time for a single pellet mostly depended on the raw material composition and to a minor extent on the density. Pellets made of bark had up to a 50% longer char combustion time compared to that of stem wood pellets, due to differences in char yield. Industrially made stem wood pellets of pine and spruce sawdust were found to have small differences in combustion characteristics. The variations in combustion characteristics of pellets are discussed in relation to composition of raw material.

Effect of raw material composition in woody biomass pellets on combustion characteristics.

The multitude of biofuels in use and their widely different characteristics stress the need for improved characterisation of their chemical and physical properties. Industrial use of biofuels further demands rapid characterisation methods suitable for on-line measurements. The single most important property in biofuels is the calorific value. This is influenced by moisture and ash content as well as the chemical composition of the dry biomass. Near infrared (NIR) spectroscopy and bi-orthogonal partial least squares (BPLS) regression were used to model moisture and ash content as well as gross calorific value in ground samples of stem and branches wood. Samples from 16 individual trees of Norway spruce were artificially moistened into five classes (10, 20, 30, 40 and 50%). Three different models for decomposition of the spectral variation into structure and noise were applied. In total 16 BPLS models were used, all of which showed high accuracy in prediction for a test set and they explained 95.4–99.8% of the reference variable variation. The models for moisture content were spanned by the O–H and C–H overtones, i.e. between water and organic matter. The models for ash content appeared to be based on interactions in carbon chains. For calorific value the models was spanned by C–H stretching, by O–H stretching and bending and by combinations of O–H and C–O stretching. Also –CC– bonds contributed in the prediction of calorific value. This study illustrates the possibility of using the NIR technique in combination with multivariate calibration to predict economically important properties of biofuels and to interpret models. This concept may also be applied for on-line prediction in processes to standardize biofuels or in biofuelled plants for process monitoring.

Multivariate NIR spectroscopy models for moisture, ash and calorific content in biofuels using bi-orthogonal partial least squares regression

Fertilization is used to increase the total yield of biomass on a site, as well as sustaining or improving the health, vigour and vitality of trees. How fertilization affects the chemical composition and the fuel characteristics is poorly known. Extractives, lignin, holocellulose, ash content and calorific heat value were measured in the stem wood at the root (0 m), 2 m and 4 m levels, in the branches, and in the bark of young Norway spruce [Picea abies (L.) Karst.] trees. Ten control trees and six fertilized trees were evaluated. Fertilization with a balanced nutrient mixture had only a minor effect on the detected chemical and fuel parameters. The main differences in chemical composition within the tree were found between stem, branches and bark. Thus, fertilization can be recommended as a silvicultural treatment to increase the net biomass production on a site intended for fuel production.

Christofer Rhén

Papers

Effects of raw material moisture content, densification pressure and temperature on some properties of Norway spruce pellets

Effect of raw material composition in woody biomass pellets on combustion characteristics.

Multivariate NIR spectroscopy models for moisture, ash and calorific content in biofuels using bi-orthogonal partial least squares regression

Chemical composition and gross calorific value of the above-ground biomass components of young Picea abies