Decrease energy consumption d during timber drying i ti b d i B.BEDELEAN, D. Ş OVA Transilvania University of Brasov, Romania COST ACTION E53 EDG SEMINAR 23 April, 2009, BLED, SLOVENIA
Introduction In a drying kiln without baffles, about 50% of the flow rate produced by fans passes the material stacks, the rest flows through the four types of passive channels. In order to be sure that the optimal velocity of air is reached in the material stacks, the kiln constructors oversize the air flow rate that is necessary for the drying process.
The additions accomplished by the constructors are situated between 30 – 50 %.
For an addition of 50% it results that on the entire drying process: � only half of the fans absorbs electric energy for produce air which is necessary to drying the material � the rest of produced air volume is used only for covering the losses through the passive channels. p From the Only half of the total Due to the 100% total air total air 50% air volume passes air volume passes passive passive 50% 50% volume the stacks channels Losses Through stacks
What is the effect of the air additions upon the electric energy consumption? What is the effect of the air additions upon the electric energy consumption? Based on the fans laws it can be observed that an addition of 10 % leads to Based on the fans laws it can be observed that an addition of 10 % leads to an increase of the absorbed power with 33%. 21.0 870.0 tric ă , kWh/mc Puterea total ă instalat ă , kW 19.0 770.0 Consumul de energie at ă , kW 17.0 electrc ă , kWh /mc 670.0 15.0 terea total ă instala mul de energie elect 570.0 13.0 470.0 11.0 9.0 370.0 7.0 270.0 Put Consum 5.0 170.0 3.0 70.0 1.0 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 Coeficientul de supradimensionare, c Coeficientul de supradimensionare, c Once increasing the absorbed power, the electric energy consumption that is necessary for the drying of one cubic meter of material increases proportionally.
In aim to reduce the disadvantage of oversize the air flow upon the electrical g p energy consumption the paper proposes the following solution: Using a program for adjusting the Using a kit of baffles for all + electric motors power according to g passive channels passive channels the optimal air velocity
Without baffles With top and lateral baffles Baffles for all passive channels Air velocity Air velocity 4.50 3.4 The obstruction of all 4.00 3.50 m/s passive p channels was Without baffles 3 00 3.00 2 54 2.54 Air velocity, necessary in order to 2.50 1.8 With top and lateral maximize the air velocity 2.00 baffles 1.50 with baffles for all above the optimal p value 1.00 passive channels passive channels recommended by the 0.50 0.00 literature. Without With top and with baffles baffles lateral baffles for all passive channels h l The analysed variants
Material and methods The research was performed on softwood timber (spruce), in a drying kiln with the capacity of 4 mc. The adjusting program of the electric motors power was developed on the basis of the developed on the basis of the criterion that the air velocity has to be framed in the optimal limits of 2 5 – 3 m/s optimal limits of 2.5 3 m/s, according to the literature recommendations. Current program Proposed program
The obstruction of all passive channels has been accomplished by means of the four types of baffles which are: types of baffles, which are: Top baffles Vertical Lateral b ffl baffles baffles H Horizontal i t l baffles
The measurement of the air velocity was performed at the air exit from the material stacks, by means of a probe and a data logger, made by Ahlborn company. Almemo data logger 2590 – 4s Ahlborn ‐ type probe for the measurement of p the air velocity The data acquisition has been accomplished by use of a computer. co pu e
In order to determine the influence of the proposed solution upon the electric energy In order to determine the influence of the proposed solution upon the electric energy consumption, the next two variants have been submitted to the drying process: The first variant – without baffles + current program Averge motors power: 85 % g p + + Averge velocity: 1.8 m/s Without baffles Current program Heating Stage I Stage II Stage III Stage IV Conditioning Cooling Average The power of the electric motor, % 100 95 85 75 70 85 95 85 2 2 1 89 1.89 1.76 1 76 1.64 1 64 1.53 1 53 1.76 1 76 1 89 1.89 1 78 1.78 Air velocity, m/s Ai l it /
The second variant – baffles for all passive channels + proposed program Averge power: 65% + Averge velocity: 3 m/s With baffles for all Proposed program passive channels Heating Stage I Stage II Stage III Stage IV Conditioning Cooling Average The power of the electric motor, % 70 70 70 55 50 70 70 65 Ai Air velocity, m/s l it / 3.2 3 2 3 2 3.2 3 2 3.2 2 66 2.66 2 46 2.46 3.2 3 2 3.2 3 2 3 3
The running of the process was accomplished according to the drying schedule supplied by the kiln constructor. pp y The stage of the Wood moisture Temperature, Equilibrium moisture 0 C process content, % content, % Heating - 50 18 Stage I 40 50 12 Stage II 28 60 10 Stage III 16 65 4,8 Stage IV 10 72 2,9 Co d Conditioning o g - 74 7 7 7 Cooling - 30 - The parameters monitoring was performed by means of Skype application and the values registration, by means of a webcam, a clock and a computer. Parameters monitoring Values registration The reading of the registered values
The measurement of the electric energy consumption was performed by determining The measurement of the electric energy consumption was performed by determining the value of the electric current intensity for each drying stage and the power factor. = = • • • • ϕ ϕ • • cos cos 3 3 P P I I U U kW kW = • E P t kWh The display of the frequency Heme Analyst 2050 y converter
Results Results 176 174 ours 174 172 172 rying time, ho The drying time decreased only with 170 168 5% if the proposed solution was applied 165 166 as compared to the present situation. p p 164 Dr 162 160 Var. I + actual program Var. II + proposed program The analysed variants 228 250 , ul de energie, 188 200 But, the electric energy 150 Wh/mc consumption decreased with 18 % 100 kW with respect to the current situation with respect to the current situation. Consum 50 0 Var. I + actual program Var. II + proposed program The analysed variants
From economically point of view, the proposed solution leads to the decrease of the drying cost of one cubic meter of wooden material with 18 %. f bi f d i l i h 18 % The name of variants First variant Second variant Species spruce Thickness, mm , 50 Annually production, m 3 176 Basis Electric energy cost, € / m 3 (kWh) 0.076 Electric energy consumption Electric energy consumption, 228 228 188 188 kWh / m 3 Total cost of electric energy, € / m 3 17.32 14.28 Saving € / m 3 g / ‐ 3 Annually saving, € / year ‐ 528 Results Cost of the baffles kit, € ‐ 234 Amortization (electric energy) ( gy) ‐ 0.44 years y (~ 5 months) It can be observed that the investment that is necessary for the production of the kit of baffles will be reclaimed in five months.
Thank you for your attention! Also, thanks to for the financial support bedelean@yahoo.com
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