DE2828247A1 - Continuously operating timber drying oven - uses blowers and heat exchanger for circulating drying gas - Google Patents

Abstract

The continuously operated drying oven is used for timber drying. The gaseous drying fluid is circulated by blowers ensuring mass exchange and removal of the moisture drawn from the timber. The drying system has high efficiency and compact design with relatively low energy consumption of the blowers. Transverse flow blowers are used for circulating the gaseous drying fluid. The axes of the transverse flow blowers are vertical and the timber moves horizontally through the drier. The length of the blower rotor (4), blower housing (5) and heat exchanger (6) corresponds to the useful stacking height of the material to be dried.

Description

j submittedJ

Remshalden, June 24, 1978 P 5321

Applicant
Rolf Pfisterer
Max-Eyth-Str. 9
7064 Remshalden 1

909881/0394

Continuous drying oven for wood

The invention relates to a continuous drying oven for wood and similar materials, in particular for thick peeled veneer or thinly cut wooden strips or boards _{or the like}

Known for drying wood veneers are the so-called nozzle dryers, in which the hot air circulated in the dryer is blown in an impact jet from above and below against the continuous veneer webs. With this process, the profitability drops sharply with increasing veneer thickness. This is due to the fact that in order to achieve a reasonably useful throughput time, the drying temperature must be increased sharply with increasing powder thickness, which requires correspondingly high transmission losses of the dryer and expensive high-pressure steam for heating. The high drying temperature required for this also has an unfavorable effect on the quality of the wood in many cases. In general it can be said that the principle of the nozzle dryer at Purnierdicken about 3 mm from the economic point is no longer competitive _o

Furthermore, it has already been proposed that specially thick veneer be fixed in appropriately designed raking trolleys or rack trolleys placed at a distance from each other in a drying oven, where it is also dried in a continuous process. To the The dryer hot air is also used to transport the moisture removed from the wood Fans circulated. It is true that there are the necessary To keep temperatures relatively low, due to the proposed use of axial or radial fans are the

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fluidic conditions extremely unfavorable, whereby uneven drying effect, voluminous construction and result in relatively high fan drive powers.

The aim of the present invention is to address the disadvantages outlined, particularly in terms of flow technology avoid and thereby at the same time an inexpensive, space-saving construction with a comparatively low fan to achieve performance

This is achieved through the use of cross-flow fans, their arrangement edge housing training preferably the intended use adjusted accordingly isto

the transport of the IHirnierblätter or the correspondingly thinly cut sawn timber trolleys are expediently used per se, which are carried out cyclically or continuously through the dryer, with the goods to be dried being arranged horizontally in the trolley _{or the like} .

Depending on the prevailing operating conditions, it can be be useful, the tray trolleys in a straight pass on the one side into the dryer »-, and on the opposite Side out of the dryer} or on the side opposite the dryer inlet to one to implement parallel track and lead back to the dryer inlet dene fan assemblies proposed, the following with reference to embodiments shown in three drawings are explained in more detail · Figures 1 and 2 show schematically two advantageous arrangements in which the tray trolleys in pure pass through the dryer, on the other hand

- 5 S09831 / O394

FIG. 3 shows the forward and reverse flow of the rack trolleys within the dryer ».

The trolleys 1 are before entering the dryer, either by hand, or partially or fully automatically with the Goods to be dried are charged and then fed into the dryer, which essentially consists of the dryer housing 2 consists * The transport device for the tray trolley 1, for example consisting of transport rails and drag chain, is, because insignificant, in Figures 1 “o. 3 not shown. In the same way, the herd wagons that have passed through the dryer are optionally unloaded by hand or partially or fully automatic.

The passage of the rack trolleys 1 through the drying oven housing can take place cyclically from ventilation station 3 to ventilation station 5, or else continuously. A complete fan unit is referred to as the ventilation station 3, consisting of the actual impeller 4 and the fan housing 5. Each ventilation station 3 on the fan suction side is advantageously assigned a heat exchanger 6 for heating the circulated air. be heated with steam, hot water or thermal oil.

Depending on the intended drying capacity, arrangements according to FIG. 1 and FIG. 3, in which there is only one ventilation station 3 per rack trolley 1, or arrangements according to FIG. 2, in which 2 ventilation stations 3 are available for every 2 rack trolleys 1, may be appropriate.

The fan arrangement is preferably selected in such a way that d & ß the direction of the flowing through the trolley 1

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Hot air from one to the other ventilation station 3 respectively is reversed. The arrows shown indicate the flow direction the air.

According to the invention, it is also expedient to use the axis the impellers 4 to be arranged vertically and the impellers 4, the length of the fan housing 5 and the heat exchanger 6 corresponds to the useful height of the tray trolley 1. As a result of these measures, the greatest possible degree of uniformity in drying for the material to be dried is achieved.

The doors of the dryer can, in a known manner, by hand, semi- or fully automatically according to the transport of the Trolley 1 can be operated »

A further advantageous embodiment variant of the invention consists in using a feeder that is known per se on control feeder doors Provide air lock 7, in the preferably cross-flow fan 8 in associated housings 9, the sealing of the hot ■ take over the dryer interior 10 against the outside atmosphere ·

An arrangement according to Figure 3 is particularly space and personnel-saving, because with intermittent loading and unloading of the Hardenwagen. 1 the same operators one after the other can carry out both the loading and the emptying of the trolley 1. This results in the same throughput with half the operating staff «,

Of course, this mode of operation requires an accurate one Coordination of the cycle times with regard to the loading and emptying the rack trolleys required working time. The dryer must be equipped with

909881/0394

for example separating sheets 11, are provided, whereby the flow course of the individual, ventilation stations 3 clearly from each other / is separated o This makes it possible to use each ventilation station 3 with a different one. Drying temperature EU drive, whereby an optimal adaptation to the drying— Course curve: Yes, the respective items to be dried are given »Of course, if you do not use different types of drying temperatures in opposite ventilation stations. 3, at particularly inexpensive. Trackner versions of these separating plates 11 can also be omitted, which siah a common flow of 2 opposite each other in the flow and return Trolley 1 through the associated ventilation stations results in «»

Of course, a dryer kit is also conceivable which is only the length of a rack trolley. In this case * not more of one can be used in cyclic operation. Continuous dryer are spoken of, there are then the characteristics of a chamber dryer Tor

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Claims (7)

Claims 1) Continuous drying oven for wood and similar materials, in which the gaseous drying medium is circulated by means of fans for the exchange of substances and for the removal of the moisture removed from the dry material, characterized by the use of cross-flow fans for circulating the gaseous drying medium _β 2) Continuous drying oven according to claim 1, characterized in that that the axes of the cross-flow fan are arranged vertically and the passage of the dry material horizontally he follows, 3) Continuous drying oven according to claim 2, characterized in that the air-flowed length of the fan impeller (4), fan housing (5) and heat exchanger (6) corresponds to the Uutzhöhe of the material to be dried _o 4) Continuous drying oven according to claim 1 to 3, characterized in that only one ventilation station (3) is provided for each rack trolley (l) and the drying medium is in one half of the rack trolley (1), c [uer to its transport direction - and flows back in the other half. 5) continuous drying oven according to claim 1 to 3, characterized in that that for every 2 trolleys (l) 2 ventilation stations (3) are available and the drying medium in one Trolley (l), transversely to its transport direction, flows forward and back in the other trolley (l). 6) Continuous drying oven according to claim 1 to 5, characterized by the arrangement of the ventilation stations (3) in relation on the respective position of the trolley (l) so that the direction of flow of the trolley (l) flowing through Drying medium in the following rack trolley position reverses in relation to the previous position. SQ9381 / D394 ORIGINAL INSPECTED 7) Continuous drying oven according to claim 1 to 6, characterized characterized that in order to seal the hot interior of the dryer against the outside atmosphere at the dryer -Exit airlocks are present that are in at. consist, as is known, of cross-flow fans. - "5 - 30988 1/0394