Drive-through chamber type timber drying kiln.

The present invention concerns a drive-through chamber type timber drying kiln, where the timber loads to be dried are conveyed on a roller track or equivalent through a front door into the drying kiln, and from which drying kiln, subsequent to drying, the timber loads are removed on the opposite side of the drying kiln through a back door.

So-called drive-through chamber type drying kilns are known in prior art. Their structure is such that drying kiln loads assembled of drying kiln packages are carried into the drying chamber on a roller track in front of them, whence the loads are pushed into the drying chamber. The dried loads are taken out through the opposite door of the drying chamber. It is an advantage of these chamber-type drying kilns known in the art that in them the load changing time is comparatively short. However, a disadvantage is the expensive realization of such drying kilns, because they require two opposite doors, and roller tracks on both sides of the drying chamber. The object of the present invention is to provide a simple design by which the drawbacks mentioned can be substantially reduced, and to provide a chamber-type drying kiln in which the advantageous characteristics of the chamber-type drying kiln, mentioned above, are preserved.

For attaining these aims and those to be disclosed below, the invention is mainly characterized in that in the drying kiln two or more drying chambers are connected in series and that of these chambers connected in series each chamber operates independently in the way that when the timber loads are transferred from a first. chamber to a next chamber, in this latter chamber the drying is carried on substantially from that point of the drying schedule which had been reached in the drying process in the first chamber.

In the following, the invention is described in detail reference being made to an embodiment example of the invention presented in the figures of the drawing attached, to the details of which the invention is not confined.

<ul id="ul0001" list-style="none"><li>Fig. 1 presents in elevational view a chamber-type drying kiln of the invention. Fig. 1 is at the same time the vertical section along the line I-I indicated in Fig. 3.</li><li>Fig. 2 shows the vertical cross section II-II in Fig. 3.</li><li>Fig. 3 shows the horizontal section III-III in Fig. 2.</li></ul>

As shown in the figures, the chamber-type drying kiln comprises four drying chambers K₁, K₂, K₃ and K₄. The chambers K₁ and K₂ among themselves and the chambers K₃ and K₄ among themselves are connected in series. Thus, the chambers K₁ and K₂ in ombination and the chambers K₃ and K₄ in combination constitute two chamber groups, both of them having only one front door 11 and one back door 13. Through the chamber groups K₁, K₂ and K₃, K₄ pass the roller tracks 10. The initial parts 10a of these roller tracks are located outside the doors 11, and similarly the ultimate ends lOb of the roller tracks 10 are located outside the rear doors 13. The timber loads P₁ to be dried are brought to the initial ends 10a of the roller tracks, and the finished dried loads P₄ are taken off the ultimate ends 10b of the roller tracks 10.

The chamber-type drying kiln comprising two drying kiln groups is composed of outer walls 14 and partitions 16, of a roof 15, and of the front doors 11 and rear doors 13 mentioned. Between the first chambers K₁ and K₃ and the second chambers K₂ and K₄ are provided light-weight partitions 12, for instance made of flexible fabric-type material, because these partitions 12 need not be thermally lagging. The partitions 12 are advantageously of such kind that it is possible to push the drying kiln loads P₂ through them from the first chamber K₁, K₃ to the second chamber K₂, K₄.

Each drying chamber K₁-K₄ is provided with means by which circulation F_k of drying air through the timber loads P_a and P₃ composed of packages provided with spacers is achieved. Said means comprise one or more blowers 20 and a heating radiator 21 placed in a duct 22. On the intake side of the blowers 20 in the duct 22 is introduced through ventilation ducts 26 an inlet air flow F_in from outdoors, and similarly, on the pressure side of the blowers 20, an outlet air flow F_out is taken off through ventilation ducts 25. In connection with the ventilation ducts 25 and 26 are provided control dampers 23 and 24, by the aid of which, combined with regulation of the radiators 21, the drying capacity of the circulating air F_k is influencable. Said means are separated from the load space by a partition 17, which is open on both sides (apertures 18 and 19). Through one aperture 19 the circulating air can pass to one side of the load, and through the other aperture 18 it is enabled to return to the blowers, having in the meantime passed through the loads. The direction in which the air circulates is reversed at regular intervals, usually automatically.

The drive-through chamber type drying kiln described in the foregoing operates as follows. The first chambers K₁ and K₃ and the second chambers K_a and K₄ of the chamber groups operate independently. When loads P₂ are transferred from the first chambers K₁, K₃ into the second chambers K₂, K₄, drying is carried on subsequent to this transfer as if no transfer had taken place, in other words, after the transfer, one begins to follow the drying schedule in the second chambers Kz,K₄ starting at that point in the drying process which had been reached in the drying in the first chambers K₁, K₃. It is advantageous, to this end, if the circulating air flows F_k in the first chambers K₁, K₃ and in the second chambers K₂, K₄ have opposite direction.

As has been set forth, each group of chambers contains two drying chambers K₁, K₂; K₃, K₄, In certain applications there may be even more such chambers in series, for instance three or four.

It is thus understood that in accordance with the invention a drive-through chamber type drying kiln has been obtained in which for each chamber group K₁, K₂ and K₃, K₄ there are still only two doors 11 and 13 and only one roller track 10 or equivalent track system passing through the chambers.

In the following are stated the claims, various details of the invention being allowed to vary within the scope of the inventive idea thereby defined and to deviate from those presented in the foregoing.