Puidu kuivatuse simulatsiooniprogrammi ,,TORKSIM´´ sobitamine reaalse tööstusliku kuivatuskõveraga, eesmärgiga tõsta pinge arvutuste ja elektriliste niiskusandurite usaldusväärsust
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Kuupäev
2015
Kättesaadavus
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Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
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Abstrakt
Selles töös uuriti Secal tüüpi kamberkuivati sobivust TORKSIM ver 3.1 simulatsiooniprogrammiga, kui sisestati simulatsiooniprogrammi Secal kuivati etteande reziim 50mm paksuse männi saematerjali kuivatamiseks. Võrdlusmomendiks oli olemas ka samast materjalist lõigatud prooviklotsi, milled niiskussisaldus määrati kuivkaalumeetodiga.
Ära on toodud ka puidu erinevad kuivatamise viisid ja lühi-iseloomustused TORKSIM ver 3.1 simulatsiooniprogrammile, kui ka Secal Plus 3000 kuivatist.
Erinevatelt graafikutelt on näha,et tööstuslik kuivatusreziim jookseb suht hästi kokku simulatsiooni omaga just kuivatusperioodi teises pooles. Kuivatamise esimesel nädalal oli, aga simulatsiooni niiskuskõver lähedasem kuivkaalu meetodil saadud prooviklotside tulemustega. Siin mängib kindlasti rolli andurite mitte usaldusväärne signaal kuivatuse algfaasis, kui puit on veel liiga märg. Mida kuivemaks puit saab, seda täpsemat signaali peaks elektrilised niiskusandurid edastama.
Simulatsiooni programmi järgi võib järeldada, et selles Secal kuivatis vähemalt 50 mm paksuse puidu kuivatamisel kasutatakse suhteliselt pehmet kuivatusreziimi, kuna pinge maksimum jäi piisavalt suure varuga alla 0,33. See on iseenesest, aga väga turvaline viis puitu kuivatada, eriti kui puit läheb mööblitööstuses kasutusse, kus kindlasti ongi vaja ülimalt kvaliteetset materjali ja ei saa riskida puidu pindmiste lõhenemiste ja muude vigastustega.
Elektriliste niiskusandurite puhul tuleks kindlasti jälgida nende kulumisastet ja kindlasti välja vahetada, kui andur hakkab ebanormaalselt kõrge niiskussisaldusega signaali andma. Alati ei pruugigi asi olla selles, et andur sai paigaldatud liiga märja ja kehva puidu sisse, vaid hoopis tekib kuskil mingi lühis või loksumine ja saadaksegi vale tulemus. Mõistlik oleks ka kasutada isoleeritud elektroode, kuna ka see annaks täpsemad tulemused ja puidu niiskussisaldus saadakse kohe kuivatuse algusest puidu seest teada, kuna isoleeritud elektroodid saadavad signaali puidu sees olevate elektroodide otstest. Üldiselt võib pidada Secal kamberkuivatis kasutuses olevaid elektrilisi niiskusandureid piisavalt usaldusväärseteks.
Regressiooni meetodil sai kuivatuskõveraid kuivkaalu järgi sujuvamaks muuta, mis on matemaatiliste valemite järgi korektne. TORKSIM simulatsiooniprogrammi järgi selgus ka uurimuses, et mida suurema algniiskusega puit, seda hiljem tekivad kuivamise protsessis maksimum pinged. Mida madalam niiskussisaldus puidus oli, seda väiksem paistis olevat ka
pingete maksimum. Sellest saaks järeldada, et mida kuivem puit, seda vähem tõmbe- ja survepingeid seal tegutseb.
Simulatsioonile lisatud +0,5 m/s tuulekiirus ei andnud samuti erilist suurt kasu, kuivamise algfaasis see tõesti kiirendab, kuivamisele kahju tekitada aga simulatsiooni tulemuse järgi jäi tulemus lõpus väga minimaalseks. Pealegi tööstuslikes kuivatites 2 m/s tuulekiirust peetakse suhteliselt ideaalseks, seega tundub selle tuulekiiruse suuremaks ajamine mõttetu. Võib pigem puidu kuivamisele kahju tekitada.
Töös tehtud kahvliproov, mis oli tehtud suhteliste pingete visualiseerimiseks täitis oma eesmärgi. TORKSIM simulatsiooniprogrammiga saab küll välja arvutada ja graafiliselt näha pingete maksimumi loetud sekunditega, aga kahvliproovi tehes näeb reaalselt kuidas puit käitub kui seda kuivamisel lahti lõigata.
This thesis researched the compatibility of Secal drying kiln with TORKSIM vers. 3.1 simulation program by entering Secal drying kiln feed mode for pine lumber with the thickness of 50mm in a simulation program. As a point of comparison, sample tiles cut of the same material were used, they're humidity content was determined by dry weight method. Thesis also lists various wood drying methods and short testimonials on Torksim simulation program vers. 3.1 as well as Secal Plus 3000 drying kiln. As various graphs show, industrial drying mode is more compatible with simulation on the second half of the drying period. On the first week of drying, however, the moisture curve of the simulation was closer to the sample tile results obtained by dry weight method. This is certainly influenced by the unreliable signals of sensors at the initial stages of drying, when the lumber is still too wet. The drier the wood becomes, the more accurate is the signal transmitted by electronic humidity sensors. Based on simulation program, it can be concluded that this Secal drying kiln uses a relatively mild drying mode for wood of at least 50 mm thickness, as the maximum voltage remained with a rather large margin below 0.33. This, however, is a very safe way to dry the timber, especially for the use in the furniture industry, which requires extremely high-quality materials and cannot risk superficial splits or other damage. Use of electronic humidity sensors, should definitely take into consideration their wear-and-tear and should be replaced, when a sensor starts showing abnormally high moisture content. This may not always be the case that the sensor was installed on too wet and low-quality wood, but instead due to a short-circuit or too much shaking, ending in faulty results. It would be also wise to use insulated electrodes, as those would also provide more accurate results and provide the moisture levels of the wood immediately in the beginning, as insulated electrodes send signals from the ends of electrodes inside the timber. In general, the electronic humidity sensors used by Secal drying kiln can be considered sufficiently reliable. Regression method allowed streamlining drying curves, using dry weight, which is correct according to mathematical formulas. TORKSIM simulation program also revealed that the higher the initial moisture, the more likely is the occurrence of peak tensions later in the drying process. The lower the initial moisture content, the lower the maximum peak tension. This would conclude that the dryer the wood, the less tensile and compressive stresses it has. Simulation also included +0.5 m/s wind speed, which did not yield any remarkable results, as it did indeed speed up the process in its initial stages, without causing harm to drying process, but according to the overall result of the simulation, this had minimal effect. Moreover, the 2 m/s wind speed used in industrial kilns, is considered relatively ideal, thus an increase in wind speed seems relatively pointless, and may rather harm the wood drying process than anything. "Fork test" performed in the scope of this work to visualize relative tensions, fulfilled its purpose. Although TORKSIM simulation program allows calculating and graphing the peak tension within seconds, a fork test shows how the wood actually behaves when it's cut open during drying process.
This thesis researched the compatibility of Secal drying kiln with TORKSIM vers. 3.1 simulation program by entering Secal drying kiln feed mode for pine lumber with the thickness of 50mm in a simulation program. As a point of comparison, sample tiles cut of the same material were used, they're humidity content was determined by dry weight method. Thesis also lists various wood drying methods and short testimonials on Torksim simulation program vers. 3.1 as well as Secal Plus 3000 drying kiln. As various graphs show, industrial drying mode is more compatible with simulation on the second half of the drying period. On the first week of drying, however, the moisture curve of the simulation was closer to the sample tile results obtained by dry weight method. This is certainly influenced by the unreliable signals of sensors at the initial stages of drying, when the lumber is still too wet. The drier the wood becomes, the more accurate is the signal transmitted by electronic humidity sensors. Based on simulation program, it can be concluded that this Secal drying kiln uses a relatively mild drying mode for wood of at least 50 mm thickness, as the maximum voltage remained with a rather large margin below 0.33. This, however, is a very safe way to dry the timber, especially for the use in the furniture industry, which requires extremely high-quality materials and cannot risk superficial splits or other damage. Use of electronic humidity sensors, should definitely take into consideration their wear-and-tear and should be replaced, when a sensor starts showing abnormally high moisture content. This may not always be the case that the sensor was installed on too wet and low-quality wood, but instead due to a short-circuit or too much shaking, ending in faulty results. It would be also wise to use insulated electrodes, as those would also provide more accurate results and provide the moisture levels of the wood immediately in the beginning, as insulated electrodes send signals from the ends of electrodes inside the timber. In general, the electronic humidity sensors used by Secal drying kiln can be considered sufficiently reliable. Regression method allowed streamlining drying curves, using dry weight, which is correct according to mathematical formulas. TORKSIM simulation program also revealed that the higher the initial moisture, the more likely is the occurrence of peak tensions later in the drying process. The lower the initial moisture content, the lower the maximum peak tension. This would conclude that the dryer the wood, the less tensile and compressive stresses it has. Simulation also included +0.5 m/s wind speed, which did not yield any remarkable results, as it did indeed speed up the process in its initial stages, without causing harm to drying process, but according to the overall result of the simulation, this had minimal effect. Moreover, the 2 m/s wind speed used in industrial kilns, is considered relatively ideal, thus an increase in wind speed seems relatively pointless, and may rather harm the wood drying process than anything. "Fork test" performed in the scope of this work to visualize relative tensions, fulfilled its purpose. Although TORKSIM simulation program allows calculating and graphing the peak tension within seconds, a fork test shows how the wood actually behaves when it's cut open during drying process.
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