Drying of timber in progressive kilns: Simulation, quality, energy consumption and drying cost considerations

Salin, Jarl-Gunnar; Wamming, Thomas

doi:10.1080/17480270802561003

Cited by 16 publications

(10 citation statements)

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“…The prices of the Nafion membrane and Nafion solution came from DuPont, and the prices of the other reagents came from Aladdin. As drying ovens used for the preparation are usually inexpensive and durable, the use and energy consumption of dry ovens only played a small part in the total initial cost of manufacturing . As shown in Table , the material costs of N212–SiO 2 and Nafion–SiO 2 were only 1.1 and 0.8% higher, respectively, than that of Nafion 212.…”

Section: Resultsmentioning

confidence: 99%

Performance improvement of electrolytic air dehumidification systems with high‐water‐uptake polymer electrolyte membranes

Zhang

2019

J of Applied Polymer Sci

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Electrolytic dehumidification with polymer electrolyte membranes (PEMs) is innovative as it enables portable, accurate, and efficient air dehumidification. However, during operation, the dehydration of the PEM results in a severe decrease in its dehumidification performance. In this study, for the purposes of improving the water retention, we developed two types of composite PEMs, Nafion Membrane 212 (N212)-SiO 2 and Nafion-SiO 2 . The hydration parameters (λ; H 2 O-SO 3 H) of N212-SiO 2 and Nafion-SiO 2 were increased by 20-61 and 40-92%, respectively, compared to that of Nafion 212. System experimental results show that in air with a 45% relative humidity, the dehumidification rates of N212-SiO 2 and Nafion-SiO 2 elements improved by 17 and 8%, respectively, and the respective increases in energy efficiency were 22 and 16%. In addition, the effect of the PEM water content on the dehumidification performance was more pronounced than those of other influencing factors such as the proton conduction resistance. The use of high-water-uptake PEMs positively helped optimize the electrolytic dehumidification, especially under low air humidities.

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Section: Resultsmentioning

confidence: 99%

Performance improvement of electrolytic air dehumidification systems with high‐water‐uptake polymer electrolyte membranes

Zhang

2019

J of Applied Polymer Sci

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“…[9,10] Finally, by increasing the temperature level during drying, one can gain on two energy components: thermal losses due to a reduced drying time and air renewal due to an increased absolute humidity in the air of the kiln. [6,11,12] Energy Saving by Alternative Technologies…”

Section: Energy Savings In Conventional Kilnsmentioning

confidence: 99%

“…This is one of the explanations for the lower consumptions reported in the very large continuous kilns operating in Scandinavia compared with batch kilns. [6] Even though the fan consumption is eventually converted into heat and reduces the need for heating energy, the cost of electricity is generally much higher than the cost of heat. It is therefore beneficial to reduce this consumption.…”

Section: Energy Savings In Conventional Kilnsmentioning

confidence: 99%

Energy Consumption in the Convective Drying of Timber Analyzed by a Multiscale Computational Model

et al. 2012

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Energy consumption during timber drying has become an increasingly important issue, alongside conventional concerns such as quality, cost, and drying time. This paper proposes a detailed analysis of the energy consumption evolution in conventional kiln drying using a sophisticated modelling approach. The formulation of energy consumption proposed by Perré et al. [1] was embedded in a multiscale computational model to consider kiln drying of a stack of boards. The drying of each board in the stack is simulated using a full version of a heat and mass transfer code (the 1-D version of TransPore), which allows all boards to be different and facilitates consideration of wood variability, in addition to the effect of position within the stack.For simple configurations, the energy consumption predicted by this complex computational tool is in agreement with the global approach. [1] Moreover, this sophisticated model is able to account for the standard deviation of the final moisture content (MC), which allows a compromise to be struck between quality, drying time, and energy consumption. In addition, this model can also be applied to test innovative, energy-saving drying strategies with an equivalent drying quality, i.e. sorting boards of similar properties before drying, or sorting boards at the end of drying to re-dry those boards that have a final MC that is still too high.

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“…Conventional steam kilns vary between those that are a batch process or progressive or continual process. While there has been an increase in the use of progressive kilns in the softwood industry, little research has been published over the last decade on the use of progressive kilns, other than the determination that for drying Scots pine with similar quality, a two-zone progressive kiln had lower energy consumption and drying costs than single-zone batch kilns [3]. Most hardwoods and many softwood species are dried using maximum temperatures below 100°C, whereas some softwood species such as southern yellow pine are currently dried using temperatures higher than 100°C.…”

Section: Conventional Kilnsmentioning

confidence: 99%

“…Poor control of the drying process leads to defects that can adversely affect the value and quality of the product and higher drying costs. For example, improper moisture content in dried pine lumber can lead to losses between $1.2 and $2.8/ m 3 and poor warp control losses between 50 and 150 dollars per thousand board feet (MBF). Several methods or combination of methods exist for the drying of solid wood products, and there are a variety of ways to control the drying process.…”

Section: Introductionmentioning

confidence: 99%

A Decade of Improved Lumber Drying Technology

Bond

Espinoza

2016

Curr Forestry Rep

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In this paper, we comprehensively review the relevant literature published from 2005 to 2016, focused on lumber drying and provide a summary of where we feel future research will focus. Drying is a critical part of most wood products manufacturing process, and the methods used and proper control are key to achieving the appropriate production level, quality, and costs. While a combination of drying methods may be used, most lumber is dried in a kiln at some point in the process. The most common commercial kilns can be classified as conventional, high temperature, and vacuum; however, there continues to be some interest in solar and compression drying. While no new drying technologies have been proposed, work has continued on improving the existing methods. Control of the drying process varies with the type of kiln used, the species being dried and the temperatures used in the process; however, it usually involves some type of measurement of the moisture content of the wood being dried. The development of new methods for controlling the drying process focuses on new ways to measure moisture content or moisture content variation, temperature drop across the load, and drying stresses. While wood quality can be defined differently by its various users, for example, industrial or end users, certain aspects of quality remain constant across these groups, such as minimizing warp, checks, and splits, and discoloration, and maintaining or enhancing mechanical properties. New schedules have been proposed to increase drying rate and improve drying quality. Methods to reduce drying defects and improve its quality have focused mainly on mechanical restraint to prevent warp, better understanding of defect formation, and pre-treatments to speed up the drying process or reduce final moisture content variation. Finally, concerns regarding the environmental impacts of wood drying, most importantly the high energy demands and emissions, have increased in importance as concerns about sustainability and health issues become more mainstream.

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Drying of timber in progressive kilns: Simulation, quality, energy consumption and drying cost considerations

Cited by 16 publications

References 0 publications

Performance improvement of electrolytic air dehumidification systems with high‐water‐uptake polymer electrolyte membranes

Performance improvement of electrolytic air dehumidification systems with high‐water‐uptake polymer electrolyte membranes

Energy Consumption in the Convective Drying of Timber Analyzed by a Multiscale Computational Model

A Decade of Improved Lumber Drying Technology

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