Potential use of wood pyrolysis coproducts: A review

Abstract

The wood carbonization is made at an enclosed environment with controlled addition of atmospheric air producing, besides charcoal, other coproducts such as condensable and non-condensable gases. These gases, which represent 70% of the dry wood mass, are released into the atmosphere, decreasing air quality and producing environmental and social impacts. In this context, it is necessary to develop technologies capable to convert these gases into usable products or transform them into heat and power. The incineration of gases from charcoal kilns opens new opportunities of business because the energy provided by burners can be utilized for drying the wood to be introduced into the kilns and for generation of electricity. On the other hand, condensable gases can also be used on a route to recover and purify the pyroligneous acid. Pyroligneous acid finds application in diverse areas, as antiseptic, antioxidant, antimicrobial, anti-inflammatory, herbicide, pesticide, plant growth enhancer, antitermitic activities; is a source for valuable chemicals; and provides smoked flavor and aroma for food. The main objective of this review is to explore the potential use of wood pyrolysis coproducts, aiming to subsidize and to encourage the technological development of equipment for use of these coproducts. This paper highlights the potential benefits arising from pyroligneous acid application and discusses the charcoal cogeneration technologies.

Evaluation of Four Types of Kilns Used to Produce Charcoal from Several Tree Species in Mexico

“…According to Canal et al [5], the moisture content of the firewood does not influence the quality of the charcoal, as was observed with the Guamúchil firewood, but it influences the yield and the emissions released into the environment, since high moisture on the firewood will require a greater consumption of firewood to achieve carbonization. In addition, it is mentioned that masonry kilns have a yield of around 30% in their best scenarios, which is like Bailis et al [48], Pereira [34], and Pyshyev et al [40], who state that traditional kilns with low technology result in low yield and low charcoal quality. This is to be "considered" because most of the world's charcoal production is done with low technology.…”

“…Phase four goes from 280 • C to the kiln's maximum heating point (>400 • C), during which cellulose is degraded and lignin breaks down; CO 2 and CH 4 emissions also occur, and condensable and non-condensable volatile material is produced, while firewood is transformed into charcoal. Finally, phase five is characterized by the cooling of the kiln [15,20,[28][29][30][31][32][33][34].…”

“…On the other hand, phase 3, where cellulose and hemicellulose remnants react, was the shortest, regardless of the type of kiln used. For their part, Pyshyev et al [40] considered that the most important phase during the charcoal production process is phase 4, since it represents a change in the energy process, changing from an endothermic phase (<280 • C) to an exothermic one (>280 • C), a phase in which the remnants of hemicellulose and cellulose are minimal, as established by Chen et al [41] and Pereira et al [34]. Therefore, the component that carbonizes in this phase is lignin as a result of its elemental structure and is composed of a high percentage of carbon and low oxygen content.…”

Effect of Firewood Moisture Content on Quality, Yield, and Economic Gain during Charcoal Production in a Modified Half-Orange Kiln

“…For its part, charcoal production is an economically and environmentally important activity since it generates a livelihood for more than 40 million people worldwide. When its production comes from forests with forest management, it represents a sustainable biofuel, generates neutral carbon dioxide emissions, and, compared to fossil fuels, has a low sulfur and nitrogen content [2][3][4][5][6].…”

Mini-Kilns for Charcoal-Making: An Eco-Friendly Solution for Small-Scale Production of Charcoal and Wood Vinegar

“…In Brazil, 40% of steel, 70% of pig iron, 100% of iron alloys, and 100% of metallic silicon are produced with charcoal as a carbon source [3], while in every other country, they are manufactured using coke. Even though metallic commodities are made using cutting-edge technologies, the charcoal that feeds the industries in this sector is produced mainly in rudimentary and low-tech masonry kilns [4]. In those kilns, the losses of bone-dry firewood in mass and energy correspond to 65 and 50%, respectively.…”