Wood Drying Kiln Research Articles

On-line evaluation of moisture transfer properties for a feed-forward control of a wood drying kiln with a mechanistic model

Kiln operators are forced to rely on their own experience and expertise when adapting standard drying schedules to tackle changing situations or to better suit their needs. The online tuning of a mechanistic model and its use as forward control is therefore proposed to address the current lack of tools. An inverse analysis of the drying kinetics of wooden boards dried in an industrial kiln is carried out to determine the moisture transfer properties of the boards. The values obtained by the inverse method are found to be relatively close to those obtained by direct measurement. The mechanistic model is then used with these input values to simulate the drying of a stack of boards to find the best drying strategy to meet the objectives. This work focuses on achieving a compromise between quality and time. Several difficulties were encountered in developing this approach for a semi-industrial dryer, and some recommendations are made for developing this innovative strategy further.

Multiple-criteria location selection for wood kiln operations using AHP/TOPSIS

This study attempted to determine a suitable combination of multiple-criteria selection techniques for the best location for wood drying kiln operations in Iran. Utilising field studies across the wood-drying industry, limitations of existing selection-method criteria were identified, and a hierarchy of decision-making factors and weights was designed utilising AHP to overcome those limitations. The alternatives were then prioritised using fuzzy TOPSIS. Results indicate that a location in the province of Mazandaran is the best solution. In validation, the results from fuzzy TOPSIS were compared with the results from interview questionnaires in relation to priority alternatives. This validation demonstrates that the results of the fuzzy TOPSIS were confirmed in the resultant order with an acceptable rate of error. Moreover, the Spearman rank correlation coefficient of the results of alternative priorities with two methods of fuzzy TOPSIS and the interview questionnaires (99.23%) indicated that there was a strong positive correlation between the results.

Essential oil recovery from exhaust steam of wood-drying kiln

木材を製材として利用する際は，乾燥に伴う割れや変形を抑制するために，予め，乾燥する事が現在の主流となっている。この際，乾燥機内で熱をかけて短期間で乾燥させる人工乾燥法が広く用いられている。木材を乾燥させる際に，木材の水分は木材の匂い成分，即ち精油成分と共に大気中に放出される。本研究はこの大気中に放出されている精油を低コストで回収する装置を開発することを目的として行った。 フィンプレートを用いた空冷の冷却装置2機を試作し，製材所の中温（60℃）及び高温（120℃）乾燥機にそれぞれ取り付け，3年間精油回収量の調査を行った。検討の結果，高温乾燥機に取り付けた装置では3年間の平均で木材1立方米あたり106.6 ml の精油を，中温乾燥機に取り付けた装置では16.4 ml/m3の精油を回収できた。排蒸気温度の測定結果から高温乾燥機では冷却能が不足しており冷却能の改善が必要であることが示唆された。一方で，中温乾燥機では排蒸気は十分に冷却されており，中温乾燥では精油揮発量が少なく本装置での精油回収には向いていないことが示された。回収した精油のガスクロマトグラフ質量分析の結果，高温乾燥・中温乾燥共にdelta-cadinene が約40％を占めており，その他の成分についても似たようなプロファイルを持つことが示された。試作した精油回収装置は3年の試験期間の内に木酢液による腐食を受けており，長期運用が難しいことが明らかとなった。本研究で試作した装置の実用化には，冷却効率の改善と耐腐食化が必要であり，現在これらを改善するための取り組みを進めている。

КОНТРОЛЬ ПРОЦЕССА СУШКИ ПИЛОМАТЕРИАЛОВ В СВЧ-ЛЕСОСУШИЛЬНОЙ КАМЕРЕ РЕЗОНАТОРНОГО ТИПА

КОНТРОЛЬ ПРОЦЕССА СУШКИ ПИЛОМАТЕРИАЛОВ В СВЧ-ЛЕСОСУШИЛЬНОЙ КАМЕРЕ РЕЗОНАТОРНОГО ТИПА

The Application of CFD in Wood Drying Kiln System Identification

As wood drying kiln system has the nonlinear characteristics of a large lag, multivariable, large inertia and strong coupling. It is difficult to establish an accurate mathematical model of the wood drying kiln system by using traditional mathematical Modeling method. The data of wood drying kiln is drawn by CFD-Fluent, and the translate function of the control system is obtained by Matlab system identification. The simulation results show that the method has good accuracy, and can meet the control requirements of the system.

Extended Contract Nets Application in Wood Drying Kiln

The article aims at the problems such as the traditional contract nets model’s communication traffic is too heavy in the consultation process; task’s partition is fixed; evaluation index is not comprehensive, proposes a contract nets improvement method based on the bidding threshold and evaluation function by combining the response threshold model of the ant colony algorithm. This method introduce fuzzy synthetic computation, finding the potential cooperation relations between node agents, bottom-up decomposing the complex task, effectively reduce the negotiation time and communication flows, improve the efficiency of the system. The thesis combines wood drying application feature, and puts forward the improved model’s experimental simulation in wood drying kiln. The result shows that the improved method can effectively improve the performance of the Contract Net Protocol in large-scale multi-agent system. It provides technical basis for the realization of wood drying cluster control.

The Distributed Control of Multi-Kiln Wood Drying Environment Based on Multi Agent System

This paper introduces the basic performances of the multi-agent system. And according to the wood drying kiln distributed characteristics and the actual requirements of the wood drying factory, apply Multi-Agent System to the control of the wood drying; establish a multi-agent control system with the hierarchical control method. The system efficiently achieves the distributed control environment of the wood drying. And discuss about the real-time agent’s hardware structure in detail. Meanwhile apply the fuzzy theory to real-time intelligent agent’s software algorithm. And use it on the simulation experiment. Experimental results show that this method can improve the overall efficiency of the system. Application with this method in wood drying control is advanced.

A Novel Intelligent Modeling Method for Wood Drying Process

This paper investigates the development and intelligent modeling problem for a wood drying kiln process via optimized support vector machine (SVM). Based on parameters optimization and model selection idea, the swarm intelligence algorithms of Particle Swarm Optimization (PSO)-SVM and Genetic Algorithm (GA)-SVM were proposed for wood drying process with strong coupling and nonlinear characteristics. The simulation results showed that both of these two kinds of swarm intelligence optimization algorithm could get the appropriate parameters of SVM effectively, and by contrast, PSO showed a better learning ability and generalization in wood drying process modeling, and could establish predictive model with better accessibility.

Researching of airflow circulation system in wood drying kiln based on array fans

This paper investigates the airflow circulation system based on array fans for wood drying kiln process incorporating the simulation of airflow patterns, velocity and pressure distributions. A description of the array-based airflow circulation system is presented, furthermore, by setting the mesh size, grid unit and boundary conditions appropriately with fluid tools and using the renormalisation group (RNG) k-e turbulence model theory, simulation experiments are established. The results are evaluated to demonstrate that the designed system can improve working efficiency and wood drying rate; in addition, it can also avoid the defects and energy wasting. The system developed in this study may be applied in industrial wood-drying kilns, with a clear potential for improved quality and increased speed of drying.

Türkiye Ahşap Kurutma Endüstrisinin Mevcut Durumu, Temel Sorunları ve Gelecek Yönelimleri

In Turkey, investments in production and use of wood drying kilns have developed as the export rates and quality expectations increased in recent years. In this study, data obtained via semi-structured interviews from wood drying kiln producers and users were used. The results reveal that there are 16 kiln producers and importers in Turkey, and 60 firms use 205 kilns that have 20401,5 m3 drying capacity. Wood drying kiln producers and users were also benchmarked in terms of crisis management and technology policies. Statistical analyses demonstrated that technology management policies of producers and users are different from each other, and they both prefer cost control strategy to get out of economic crises in turbulent times.

A singular pencil model and neural network cascade fault diagnosis strategy for the lumber-drying process

This paper presents some results that were obtained in fault diagnosis for a wood-drying process. It is difficult to detect and diagnose faults or failure in the drying process due to complex dynamic nonlinearity, coupling effects among key variables, and process disturbances caused by the variation of lumber sizes, species and environmental factors. In this paper, a real-time fault diagnosis algorithm is developed based on a singular pencil model and neural network classifier. Inputs of the network are the process I/O data, such as moisture and temperature, and estimated parameters and states, while outputs of the network are process fault situations. A wood-drying kiln is studied as a test case, which is with two actuators and 23 sensors, six estimated parameters and states, and 11 fault situations. The simulation results show that the strategy appears to be better suited to diagnose faults of such industrial processes.

Experimental modelling and intelligent control of a wood‐drying kiln

AbstractProper control of the wood‐drying kiln is crucial in ensuring satisfactory quality of dried wood and in minimizing drying time. This paper presents the development, implementation, and evaluation of a control system for a lumber drying kiln process incorporating sensory feedback from in‐wood moisture content sensors and intelligent control such that the moisture content of lumber will reach and stabilize at the desired set point without operator interference. The drying process is difficult to model and control due to complex dynamic nonlinearities, coupling effects among key variables, and process disturbances caused by the variation of lumber sizes, species, and environmental factors. Through system identification scheme using experimental data and recursive least‐squares algorithm for parameter estimation, appropriate models are developed for simulation purpose and controller design. Two different control methodologies are employed and compared: a conventional proportional‐integral‐derivative (PID) controller and a direct fuzzy logic controller (FLC), and system performance is evaluated through simulations. The developed control system is then implemented in a downscaled industrial kiln located at the Innovation Centre of National Research Council (NRC) of Canada. This experimental set‐up is equipped with a variety of sensors, including thermocouples for temperature feedback, an air velocity transmitter for measuring airflow speed in the plenum, relative humidity sensors for measuring the relative humidity inside the kiln, and in‐wood moisture content sensors for measuring the moisture content of the wood pieces. For comparison, extensive experimental studies are carried out on‐line using the two controllers, and the results are evaluated to tune the controller parameters to achieve good performance in the wood‐drying kiln. The combination of conventional control with the intelligent control promises improved performance. The control system developed in this study may be applied in industrial wood‐drying kilns, with a clear potential for improved quality and increased speed of drying. Copyright © 2001 John Wiley & Sons, Ltd.

Strategy for optimal operation of a biomass-fired cogeneration power plant

Biomass-fired cogeneration not only is an environmentally friendly energy production, but also possesses high energy conversion efficiency. Generally, the wood product industry requires both heat and electricity. Combined heat and power generation cogeneration) using wood residue has a three-fold benefit: waste minimization, reduction of an energy-related production cost and additional income from selling the excess electricity to the utility. In reality, the process heat demand fluctuates according to the production activities in the factory. The fluctuation of process heat demand affects the cogeneration efficiency and the electricity output and, consequently, the financial return, since the prices of heat and electricity are different. A study by computer simulation to establish a guideline for optimum operation of a process heat fluctuating cogeneration power plant is presented. The power plant was designed for a sawmill and an adjacent plywood factory using wood wastes from these two processes. The maximum boiler thermal load is 81.9 MW while the electricity output is in the range 19-24 MW and the process heat 10-30 MW. Two modes of operation were studies, namely the full (boiler) load and the partial (boiler) load. In the full load operation, the power plant is operated at a maximum boiler thermal load, while the extracted steam is varied to meet the steam demand of the wood-drying kilns and the plywood production. The partial load operation was designed for the partially fuelled boiler to provide sufficient steam for the process and to generate electricity at a desired capacity ranging from the firmed contract of 19 MW to the turbine maximum capacity of 24 MW. It was found that the steam for process heat has an allowable extracting range, which is limited by the low pressure feed water heater. The optimum operation for both full and partial load occurs at the lower limit of the extracting steam. A guideline for optimum operation at various combinations of electricity output and steam demand is presented. The maximum achievable overall efficiency is 64.6 per cent when the power plant is operated at partial (boiler) load condition for 19 MW electricity and 30 MW process heat. The full load operation, although having lower overall efficiency, is preferable financially because of the higher unit price of electricity in comparison with heat.

Simulations and Experiments on Intelligent Control of a Wood-Drying Kiln

The paper first outlines the experimental kiln. Next, the control system that has been developed, which contains a fuzzy control module, is presented. Simulation results as obtained from an experimental model are given. Results from on-line experimentation of the physical kiln are given as well. The paper ends with a discussion of the results and conclusions.

Dynamic Modelling of the Wood Stack in a Wood Drying Kiln

For the design of energy efficient dryers employing heat pump systems, the dynamic response of the product to the kiln conditions must be taken into account. In this paper, the formulation of a dynamic, kiln-wide drying model is described. The model solves the unsteady-state mass, momentum and energy balance equations for both the air flow and the wood boards in drying three types of stack: normal stack, aligned stack and staggered stack. In order to represent the dynamical response of the system, the model equations provide more complete energy and mass balances than those presented in recent publications. The transient profiles of the air humidity, temperature, pressure, and velocity, and the wood temperature and moisture content along the air flow direction within the stack are obtained using this model. To illustrate the use of the model, the drying processes of sapwood boards of Pinus radiata under typical dehumidifier kiln conditions have been calculated, and the modelled results have been discussed in detail. In addition, the model has been tested by using the performance data for a commercial scale kiln. The agreement between the modelled and measured performance results shows that the model is suitable for the design and analysis of dehumidifier wood dryers.

Design of Solar–Dehumidification Wood Drying Kiln Characterized by High Capacity and Temperature

ABSTRACT Solar–;dehumidification wood drying kilns attract more and more interest due to their energy saving characteristics. However. such dryers are only available for small effective drying volume capacities. less than 30 m3, and for low drying temperature under 65 °C, for Chinese domestic products. In fact, wood drying kilns over 60 m3and high drying temperatures upto 95 °C or even higher are commonly desired from economic and process technology points o f view. For instance, if the drying temperature is below 60 °C. a long drying period will result in high operational costs and may also cause mould as well colour changes on the lumber surface. It is also known that the anti- decay ability of the seasoned lumber is lhus reduced. As such. the design of the solar–dehumidification wood drying kiln with an effective drying volume capacity of 60 m3 and a drying temperature upto 95 0C was made. Two compression processes for dehumidification and heat pump systems were adopted. The refrigerant of R1(2). which...