SE193812C1

SE193812C1 -

Info

Publication number: SE193812C1
Authority: SE
Publication date: 1964-01-01

Description

Uppfinnare: GE Stargren FOreliggande uppfinning hAnfor sig till ett forfaringssatt vid torkning av virke i en kanaltork, ddr virket passerar med i huvudsak konstant hastighet genom en torkkanal och darunder bestrykes av ett i en sluten bana cirkulerande torkmedel, sasom varmluft. Torkanordningar av ifragavarande typ besta av dels en kammare for upptagande av det material, som skall torkas, med insattningsportar for materialet vid kammarens ena dude, i det efterfoljande kallad »vdtande» pd grund av materialets fuktiga tillstand, och uttagsportar vid kammarens motsatta dude, i det efterfoljande kallad »torrande», dels en kanal for aterforing av den cirkulerande torkluften. Inventor: GE Stargren The present invention relates to a process for drying wood in a duct dryer, in which the wood passes at a substantially constant speed through a drying channel and is then coated by a desiccant circulating in a closed web, such as hot air. Drying devices of the type in question consist of a chamber for receiving the material to be dried, with insertion ports for the material at one dude of the chamber, hereinafter referred to as "wetting" due to the moist condition of the material, and outlet ports at the opposite dude of the chamber, in the subsequent so-called «drying edge», partly a channel for feeding back the circulating drying air.

Det far uppfinningen utmarkande dr, att for astadkommande av en i huvudsalc konstant fuktighetshalt hos det ur kanaltorken uttradande virket oberoende av fuktighetshalten hos det inkommande virket och utan andring av virkets genommatningshastighet regleras den med fuktighetshalten hos virket varierande varmetillforseln genom forandring av det cirkulerande torkmedlets cirkulationshastighet, dvs. volymmangd per tidsenhet, i beroende av temperaturskillnaden hos torkmedlet f re och efter dess passage genom virket, medan ventilationsluftmangden regleras i beroende av torkmedlets fuktighet efter dess passage genom virket, i dndamal att lidila denna fuktighetshalt konstant. The invention is characterized in that in order to achieve a substantially constant moisture content of the wood emerging from the channel dryer, independent of the moisture content of the incoming wood and without changing the throughput of the wood, the heat supply varying with the moisture content is regulated by changing the circulation dryness. i.e. volume volume per unit time, depending on the temperature difference of the desiccant before and after its passage through the wood, while the ventilation air volume is regulated depending on the humidity of the desiccant after its passage through the wood, in this case to keep this moisture content constant.

Vid anordning av likartad typ, exempelvis vid en i den schweiziska patentskriften 215 467 beskriven anordning, arbetar man ocksa med en temperaturskillnad for att reglera arbetsforloppet hos en tork, men det bor observeras att vid patentforemdlet i namnda patentskrift arbetar man med torktiden, dvs. dd en bestAm.d temperaturskillnad uppnas erhAlles en signal, som indikerar att torkningen Ar Dupl. kl. 82 a: 30/ slutford. Det dr praktiskt taget uteslutet att anvanda en dylik anordning for kontinuerlig drift. lridare är det besvarligt vid intermittent drift, dA tidsperioderna for torkens beskickning varier. ar. In a device of a similar type, for example in a device described in the Swiss patent specification 215 467, one also works with a temperature difference to regulate the work process of a dryer, but it should be noted that in the patent example in the said patent specification one works with the drying time, ie. If a certain temperature difference is obtained, a signal is obtained which indicates that the drying is Du Dupl. at 82 a: 30 / slutford. It is practically impossible to use such a device for continuous operation. In other words, it is responsible for intermittent operation, as the time periods for the dryer to be loaded vary. are.

Det dr ocksd kant, exempelvis enligt den svenska patentskriften 177 263, att bAlla kyl- grdnstemperaturen fOr torkmedlet i torkkana- len konstant genom en reglerad ventilation och att variera torkmedlets torra temperatur i be- roende av torkmedlets avvikelse fran en bestamd normaltemperatur vid en punkt i forkkanalen i narheten av torkgodsets inmatningsstalle. It is also possible, for example according to the Swedish patent specification 177 263, to keep the coolant temperature of the desiccant in the duct constant through a regulated ventilation and to vary the dry temperature of the desiccant depending on the deviation of the desiccant from a certain normal temperature at a point in the front channel near the dryer feed stall.

Vid anordningar av de ovan beskrivna slagen har det inneburit svarigheter att Astad- komma ett effektivt torkforlopp, speciellt under automatisk kontroll och vid kontinuerlig drift. In the case of devices of the types described above, it has entailed responsibilities to ensure an efficient drying process, especially during automatic control and during continuous operation.

Genom forfarandet enligt uppfinningen uppnas ddremot en snabb och korrekt automatisk reglering av torkluften till for torkningen ldmpliga varden. Detta forfarande ldmpar sig foretradesvis for motstromstorkar, men det kan i modifierad form aven tillampas vid andra typer av torkar, sasom tvarstrOmstorkar. By means of the method according to the invention, on the other hand, a fast and correct automatic regulation of the drying air to the values suitable for drying is achieved. This method is preferably suitable for countercurrent dryers, but it can in modified form also be applied to other types of dryers, such as cross-flow dryers.

Detta sker enligt uppfinningen genom variation av den i torken cirkulerande torkluft- mangden per tidsenhet. Fdrfarandet baserar sig pa den erforderliga torkluftmangden sasom funktion av den specifika avdunstningen och temperaturfallet hos torkluft, vid dess passage forbi det material, som skall torkas. Om torkluftmdngden betecknas med Q„ varmebehovet for torkningen Q, och temperaturfallet mellan torkens torr- och vatande td kan foljande ekvation uppstAllas: Q v kg/h 0,24. td 2— — Av denna framgar att vid ett pa materialegenskaperna baserat konstant temperaturfall ta, torkluftmangden Qe skall varieras i huvudsak proportionellt mot varmebehovet. This is done according to the invention by varying the amount of drying air circulating in the dryer per unit of time. The process is based on the required amount of drying air as a function of the specific evaporation and temperature drop of drying air, during its passage past the material to be dried. If the amount of drying air is denoted by Q, the heat demand for the drying Q, and the temperature drop between the dry and watering td of the dryer, the following equation can be set: Q v kg / h 0.24. td 2— - From this it appears that at a constant temperature drop based on the material properties, the amount of drying air Qe must be varied substantially in proportion to the heat demand.

Genom den angivna atgarden dr det saledes mojligt att enligt uppfinningen astadkomma ett riktigt torkningsresultat med storsta majliga utnyttjande av apparaten, da temperaturerna i resp. andar kunna bestammas till sina maximala \Orden med hansyn till materialets egenskaper, sasom porositet, fuktighetshalt, benagenhet for torkskador etc. Through the stated procedure it is thus possible according to the invention to achieve a correct drying result with the greatest possible utilization of the apparatus, as the temperatures in resp. spirits can be determined to their maximum \ words with regard to the properties of the material, such as porosity, moisture content, susceptibility to drought damage, etc.

Med kannedom om att torkluftens tillstandsforandring foljer en linje i Mollier-diagrammet for fuktig luft, som är i det narmaste parallell med linjerna for konstant vat temperatur är det pa basis av uppfinningen majligt att med ett ringa antal kontrollorgan astadkomma den erforderliga regleringen. Genom ovannamnda forhallande behover namligen luftkvaliteten endast kontrolleras vid torkens ena ande. Foretradesvis, ehuru ej nodvdndigt, sker detta vid torkens -vatande. Sale-des fordras for torkforloppets fullstandiga beharskande endast tre kontrollelement, näinligen ett par kontrollelement for temperaturfallet och ett kontrollelement for luftfuktigheten, sasom vat termometer eller hygrometer. With the knowledge that the change of condition of the drying air follows a line in the Mollier diagram for humid air, which is almost parallel to the lines for constant wet temperature, it is possible on the basis of the invention to achieve the required regulation with a small number of control means. Due to the above-mentioned conditions, the air quality only needs to be controlled at one end of the dryer. Preferably, although not necessarily, this is done during the drought. For the complete mastery of the drying process, only three control elements are required, namely a pair of temperature drop control elements and a humidity control element, such as a water thermometer or hygrometer.

I det efterfoljande askadliggores forfarandet genom en beskrivning av ett utforingsexempel enligt uppfinningen med hfinvisning till bifogade schematiska ritningsfigur. In the following, the method is illustrated by a description of an exemplary embodiment according to the invention with reference to the accompanying schematic drawing figure.

Pa ritningen Or eu langstrackt kammare 1 vid sina andar (vatande resp. torrande), farsedd med insattningsportar 2 resp. uttagsportar 3, eventuellt anordnade sasom slussar for det material, som skall torkas, exempelvis virke. In the drawing Or eu elongated chamber 1 by its breaths (watering or drying), fitted with insertion ports 2 resp. outlet ports 3, possibly arranged as locks for the material to be dried, for example wood.

Materialet transporteras i huvudsak kontinuerligt genom namnda kammare 1 i pilriktningen A sasom enskikla artiklar eller 1 satser 4, visade med streckprickade linjer. Storleken pa satserna kan vara godtycklig beroende pa de aktuella forhallandena. Vid torkning av virke kan detta matas antingen i sin langd- eller tvarriktning genom kammaren 1. Det sen.are, dvs. med virket frammatat i sin tvdrriktning, kan emellertid innebara vOsentliga fordelar saval betraffande torkningsforloppet som en mer kontinuerlig drift. The material is transported substantially continuously through said chamber 1 in the direction of the arrow A as single articles or 1 sets 4, shown in dashed lines. The size of the rates can be arbitrary depending on the current conditions. When drying wood, this can be fed either in its longitudinal or transverse direction through the chamber 1. The latter, ie. with the wood fed in its opposite direction, however, can entail significant advantages in terms of the drying process as a more continuous operation.

Ehuru uttrycket kontinuerlig anvants for att karakterisera behandlingssattet, sker givetvis in- och utmatningen av virke i viss man intermittent genom att insattning och uttagning av artiklarna eller satser av artiklar maste ske en gang med en stracka svarande mot artikelns eller satsens utstraekning i matningsriktningen, men detta bryter dock icke kontinuiteten i behandlingen. Although the term is continuously used to characterize the method of treatment, the input and output of timber takes place intermittently, of course, by inserting and removing the articles or batches of articles once with a distance corresponding to the extent of the article or batch in the feeding direction, but this however, does not break the continuity of treatment.

Materialet 4 kan transporteras pa vagnar eller band (joke visade) genom kammaren 1, och de enskilda artiklarna Oro anordnade med mellanrum pa kdnt salt sa att torkluften effektivt nar alla delar av virket. The material 4 can be transported on carts or belts (joke shown) through the chamber 1, and the individual articles Oro are arranged at intervals on cored salt so that the drying air effectively reaches all parts of the wood.

En kanal 5 for aterforing av cirkulationsluft i pilarnas B, C riktning (mot materialets transportriktning i kammaren 1) Or anordnad Over kammaren 1, och star i farbindelse med den senare enbart genom oppningar 6 och 7 vid kammarens insattnings- resp. uttagsande. Kanalen 5 innehaller dels en fla.kt 8 far luftens cirkulation, dels ett varmebatteri 9 och dels ett motormanovrerat spjall 10. A duct 5 for returning air of circulation in the direction of the arrows B, C (towards the direction of transport of the material in the chamber 1) is arranged above the chamber 1, and communicates with the latter only through openings 6 and 7 at the insertion resp. withdrawal. The duct 5 contains partly a flat 8 for the circulation of the air, partly a heating coil 9 and partly a motor-maneuvered damper 10.

Till kanalen 5 fore uppvarmningselementet 9 Oro separata avlopps- och inloppskanaler 11, 12 anordnade i forbindelse med fria luften. Kanalernas 11, 12 genomstromningsarea regleras medelst motorkontrollerade spjall 13, 14, vilka Oro hopkopplade direkt eller via ldmpliga overforingsorgan for astadkommande av eventuell onskad inbordes rorelse. En joke visad flakt Or Otminstone anordnad i utloppskanalen 11 for evakuering av fuktighetsmattad luft, men kan Oven vara anordnad i kanalen 12 for tillforsel av frisk- Kanalernas yttre oppningar bora givetvis vara inbordes sa. anordnade att den avgaende fuktiga luften joke tillates intrada i kanalen 12. To the duct 5 the heating element 9 is provided with separate drain and inlet ducts 11, 12 arranged in connection with the open air. The flow area of the channels 11, 12 is regulated by means of motor-controlled dampers 13, 14, which are connected directly or via flexible transfer means for effecting any desired inboard movement. A joke shown flat Or at least arranged in the outlet duct 11 for evacuation of moisture-saturated air, but can Oven be arranged in the duct 12 for supply of fresh- The outer openings of the ducts should of course be inboard so. arranged that the exiting humid air joke is allowed intrada in the duct 12.

I lufteirkulationskretsen Or vid vatanden 2 ett kanselorgan 15 anordnat, bestaende av exempelvis en elektriskt arbetande termostat for torr temperatur ansluten till en_ motor 18 till den motormanovrerade spjallanordningen 10 i kanalen 5. Termostaten 15 Or anordnad for att vid sjunkande temperatur oppna spjallen 10 for okad eirkulationsluftmangd. In the air circulation circuit Or at the watering 2 a pulpit means 15 is arranged, consisting of for instance an electrically operating thermostat for dry temperature connected to a motor 18 of the motor-operated throttle device 10 in the channel 5. The thermostat 15 Or is arranged to open the throttle 10 for increased circulation air at decreasing temperature. .

Vid torkens vatande 2 Or vidare ett kanselorgan 16 anordnat f6r kontroll av torkmedlets fuktighetshalt. Detta kanselorgan kan utgaras av en elektriskt arbetande termostat for vat temperatur eller en hygrostat, som Or kopplad till en motor 20 far den motormanovrerade spjallanordningen 13, 14 for luftbyte genom kanalerna 11, 12, sa att en konstant fuktighetshalt uppratthalles vid torkens vatande. When the dryer is being watered, a chisel means 16 is further provided for checking the moisture content of the desiccant. This pulpit means can be provided by an electrically operating thermostat for wet temperature or a hygrostat, which Or connected to a motor 20 passes the motor-operated throttle device 13, 14 for air exchange through the channels 11, 12, so that a constant moisture content is maintained during the drying of the dryer.

Slutligen Or vid torkens torrande 3 en kanselkropp 17 anordnad, bestaende exempelvis av en elektriskt arbetande termostat for torr temperatur. Denna termostat 17 Or kopplad till motorn till en motormanovrerad ventil 19 for reglering av varmetillforseln till varmebatteriet 9, for uppratthallande av konslant temperatur vid torkens torrande. ..9.tt marka Or emellertid att Mom forfarandets ram anordningen kan modifieras pa sadant satt att kanselkroppen 15 vid torkens vatd.nde kan reglera varmetillforseln, medan kanselkroppen 17 vid torkens torrande reglerar luftmangden, men den pa ritningen exemplifierade anordningen har visat sig ur praktisk synpunkt fordelaktigare. Likash kan luftens tillstand regleras vid torkens torrande 3 i stallet for vid vatanden 2, om sa skulle befinnas IOmpligt. Vidare Or att marka att luftmangdens reglering, sa val betraffande — —3 cirkulationsluft som luftutbytet, kan ske genom varvtalsreglering eller ornstallning av f15.ktar eller pa vilket annat lampligt salt som heist, och att overforing av de upptagna tillstanden vid matpunkterna kart ske joke en-hart pa elektrisk vag utan pa vilket annat lampligt satt som heist, s5.som hydrauliskt eller pneumatiskt. Finally, during the drying 3 of the dryer, a pulpit body 17 is arranged, consisting for example of an electrically operating thermostat for dry temperature. This thermostat 17 is connected to the motor of a motor-operated valve 19 for regulating the heat supply to the heating coil 9, for maintaining a constant temperature during the drying of the dryer. It should be noted, however, that the device frame of the procedure can be modified in such a way that the pulpit body 15 at the drying water can regulate the heat supply, while the pulpit body 17 at the drying stage regulates the air flow, but the device exemplified in the drawing has proved practical. point of view more advantageous. Likash, the state of the air can be regulated during the drying of the dryer 3 in the stable before at the water 2, if this should be found IOmpligt. Furthermore, it should be noted that the regulation of the amount of air, so the choice concerning - —3 circulating air as the air exchange, can take place by speed control or installation of f15.ktar or on any other suitable salt as heist, and that transfer of the occupied states at the food points -hard on electric scales but on any other suitable way as a lift, such as hydraulic or pneumatic.

Claims

Patent claim:

Procedure for drying wood in a duct dryer, where the wood passes at a substantially constant speed through a drying channel and is then coated with a desiccant circulating in a closed web, such as hot air, which can be characterized in that, in order to achieve a substantially constant moisture content of the wood exiting the duct dryer, independent of the moisture content of the incoming wood and without changing the feed rate of the wood, regulates the heat supply varying with the moisture content of the wood by changing the circulation speed of the circulating desiccant, i.e. volume per unit time, depending on the temperature difference of the desiccant before and after its passage through the wood, while the amount of ventilation air is regulated depending on the humidity of the desiccant after its passage through the wood, in order to keep the moisture content substantially constant.

2. A method according to claim 1, wherein the temperature of the desiccant before its passage through the wood is maintained substantially constant, characterized in that the circulation speed of the desiccant is controlled so that a constant temperature of the desiccant is maintained after its passage through the wood. Request publications: Patentskrifter frein Sverige 177 263; Switzerland 215 467, 295 174.