EP0946340B1 - Method for stocking and preserving green round wood and sawn timber - Google Patents

Abstract

The invention relates to a method for stocking and preserving green round wood and sawn timber, which is stored in an airtight and lighttight sealing cover. The oxygen inside the cover is decomposed by the respiratory process of fungi, bacteria and wood cells that are still alive, thereby forming CO2 and H2O. Fermentation processes also lead to the decomposition of hemicelluloses and saccharides which are converted to organic acids and CO2. The oxygen content in the cover is less than 0.1 vol. % after an adjustment time of 3 to 10 days of total stocking, while said CO2 content rises to more than 21 and up to 40 vol. %. This method enables green round wood a swan timber to be stocked over long periods without wastage or environmental damage.

Description

The invention relates to a method for preserving Storage of fresh logs and fresh sawn timber, such as Softwood and hardwood, for storage over long periods without loss of quality.

Common general preservation procedures used so far preferably foods that are either airless and Heating can be sterilized (boil down) or dry Be gassed with carbon dioxide (grain protection against Grain beetle infestation) or with protective gases of a special composition treated (fruit storage and ripening under nitrogen-carbon dioxide atmosphere) or under pure nitrogen from Free insects (restoration of wooden objects, whose color pigments would be attacked by carbon dioxide).

So far, especially in the preservation of fresh logs procedures used are based on water storage or Sprinkling with water. The aim is to have a high wood moisture content maintain over 100% to prevent fungal growth. Disadvantages are the high water consumption and the Groundwater contamination with wood constituents, associated with different humidity inside the pile, with the possible Result of fungal attack (Hallimasch).

Furthermore, with the help of insecticides and fungicides round and Lumber can be preserved temporarily. Pesticide use is associated with the endangerment of nature and humans.

A safe preservation option is the rapid processing and drying of the wood. This forces large cutting and drying reserves to be able to quickly process a large mass of logs (calamities, windthrow).
Attempts to preserve fresh logs in dry pile are also known. However, the procedure is associated with a high risk of fungal and insect attack.

Processes with the help of fungal cultures on the Wood properties act, are from DE-A-28 57 355 and known from DE-A-34 34 551.

According to DE-A-28 57 355, a method for the microbiological modification of hardwood by the action of microorganisms is known. The microorganisms bring about a selective change in the hardwood, the temperature, the moisture content of the wood, the O ₂ content and the CO ₂ content being regulated with regard to the microorganisms.
In DE-A-34 34 551, a specific color change is caused on logs by treatment with wood-destroying fungi. The color change occurs at the point where the mushroom culture was applied. The application of several wood cultures is also described, which is associated with an advantageous boundary layer formation.

At US-A-2 617 202 fresh lumber of the wood type Black Oak stacked for 3-5 days and the whole stack or just the top of the lumber stack covered with a film of what can cause fermentation processes by heating the wood. Then, in a second stage of the process, each board laid on the ground and rotated at regular intervals, which allow gentle drying and thus undesirable Should avoid cracking.

In the publication Mahler, G .: Preservation of wood by protective gas. AFZ 47 (1992), 19, pp. 1024-1025 reports on attempts to preserve wood with protective gas. During the tests, wood in standardized dimensions was packed in silage film. The pile was gassed with nitrogen as well as with carbon dioxide; the gas volume required about three times the volume of the wood. This reduced the oxygen content to 4 to 5% and maintained it over a longer period (more than 6 months). After opening the pile, a fungal coating was found on the wood, which is said to have an antagonistic effect and is pointed out that by promoting antagonistic fungi, an attack by wood-destroying fungi could be prevented.
The described fumigation expenditure and the relatively high residual oxygen content appear to be disadvantageous.

The invention is based on the object of a method develop with fresh logs with reasonable effort or fresh sawn timber of all tree types for a longer one Period without compromising quality and Strength properties can be stored without first sterilized, moistened, dried or with special Shielding gases must be treated.

The task is with those mentioned in claim 1 Process features resolved. There are advantageous variants from the subclaims.

First of all, there is some surprise in it there is that the damp, bark-free wood under one low-exchange atmosphere does not falter and rot. Essential the invention, however, is that by breathing processes even more alive Wooden cells and possibly through metabolic processes of fungi, Bacteria in the fresh round or sawn timber Envelope to be stored, an almost oxygen-free and carbon dioxide-enriched atmosphere is generated.

On the one hand, the airtight envelope does not guarantee this Oxygen can enter from the outside and no other generated carbon dioxide can escape from the envelope.

Contrary to that in Mahler, G .: Conservation of wood by Shielding gas. AFZ 47 (1992), 19, pp. 1024-1025 Is not the effect of the fungal antagonists of crucial, wood-destroying fungi on growth to prevent. Rather, the very low oxygen content of below 0.1 vol .-% essential for a permanent Storage.

This low oxygen content is achieved in that a further cycle begins after the breathing processes customary in fruit storage, in which CO ₂ and H ₂ O are released and which have ended with the consumption of O ₂ . Fermentation processes take place in which additional CO _{2 is} released so that the proportion of CO ₂ can increase further.

The start of fermentation processes is in the invention (in Contrary to the storage of fruit) of essential advantage. On Cellulose and lignin breakdown is not associated, as it is only slight soluble sugars are broken down. Thus, the strength of the Get round or sawn timber.

The biotechnological process started after the air is closed can be accelerated by minimizing the air volume involved in the casing.
A housing, advantageously a film with high diffusion resistance, is used to produce the air seal. The film can be doubled to reduce the risk of leakage. The advantage of a flexible cover is that the air volume can be reduced to a minimum (suction until the film tightly encloses the pile or lumber stack surface).

The air seal can also be achieved in specially prepared warehouses, containers, ship holds, lined pits, silos or mine tunnels.
After a short opening of the airtight casing for the removal of wood, the almost oxygen-free atmosphere is restored after a few days. Regardless of the time of year, the microorganisms are able to bring them back into their favorable condition. In addition, CO ₂ , which is stored in the wood as a porous body and dissolved in the water bound in the wood, can be released again to produce a new gas equilibrium.

In the case of foil storage, the air is sealed off from the layer or Long wood piles, in the case of valuable (veneer) logs too Individual protection, efficient with a double weld on the enveloping film or achieved by gluing or by Clamp the film sheets lying on top of each other with Last, around which the film is then wrapped tightly and with Is secured against rewinding.

The main advantage of the method according to the invention is in that the preservative storage without an additional Fumigation comes out.

Fig. 1

eine Anordnung mit mehreren Rundhölzern verschweißter bzw. verklebter doppelter Folienumhüllung

Fig. 2

eine Anordnung mit einem Rundholz mit verschweißter bzw. verklebter doppelter Folienumhüllung

Fig. 3

eine Klemmverbindung an den Folienrändern

Fig. 4

ein Diagramm mit Darstellung der Gasentwicklung bei Lagerung unter Luftabschluß

Fig. 5

ein Diagramm mit Darstellung der Biegefestigkeit im Lagerverlauf nach Lagerung unter Sauerstoffentzug mit Nullprobe und DIN-Wert

The invention is explained in more detail below using several exemplary embodiments. The drawings show:

Fig. 1

an arrangement with several round timbers welded or glued double foil wrapping

Fig. 2

an arrangement with a round timber with welded or glued double foil wrapping

Fig. 3

a clamp connection on the film edges

Fig. 4

a diagram showing the gas development when stored under the exclusion of air

Fig. 5

a diagram showing the bending strength in the course of the bearing after storage with oxygen removal with zero sample and DIN value

example 1

Duplicate dual films 2 were spread out on a flat surface and covered with 30 cbm of non-bared profiled wood, spruce 1, diameter groups 15-25 cm. Two measuring hoses 5 were laid without pressure in the pile and fastened to the film 2 with bulkhead screw connections 4 . According to FIG. 1, the protruding film 2 was then pulled over the pile and the two films 2 - separately from one another - were welded with a double seam. In summer, after approx. 3 days, in winter after approx. 10 days, the oxygen content drops below 0.1%. The carbon dioxide content levels out at around 40% (cf. FIG. 4). After 24 months of storage, there is no evidence of blueness, red streaking or Halli-mash infestation. The flexural strengths measured according to DIN 52186 after storage are not lower than those of fresh comparative samples (cf. FIG. 5).

Example 2

1 m ^{3 of} plywood pine 1 was wrapped in double dual film as in FIG. 3. Both ends of the film were clamped smoothly between two strips 6 and wound tightly in these strips 6 . The resulting bond was secured against unscrewing by means of clips 7 . This means that the prerequisites for setting the gas atmosphere can be created without a weld using means available on site.

Example 3

According to FIG. 2, a maple veneer trunk with a center diameter of 35 cm and a length of 3 m is rolled into double dual film 2 . A bulkhead screw connection is attached near the end faces of trunk 1 . The foils 2 are then double-welded 3 . After 2 weeks there is an atmosphere that contains less than 0.1% oxygen and whose carbon dioxide content is up to 30%.

Example 4

To harmless overseas transport of fresh logs allow, the wood is sealed in airtight Holds, filling the hold volume if possible, layered. Since the holds are already watertight thanks to bulkheads can only be closed, the air seal must be on top through airtight or sealed hatches. Around Shortening the setting time is called initial fumigation Combustion gases from the ship's diesel are fed into the hold.

Claims (14)

1. Method of preservative storage of fresh logs and sawn timber, wherein the wood is stored under a cover consisting of a sheet of plastic material, which may result in respiratory and fermentation processes by fungi, bacteria as well as respiratory processes of wood cells that are still alive, wherein:

   the fresh logs and sawn timber (1) are stored under an air-tight and light-tight covering (2),

   the oxygen in the enclosure, by metabolic reactions converts into CO₂, H₂O and organic acids, whereby essentially hemicelluloses and sugars are metabolized,

   and thus, after an adjustment period of 3-10 days, the oxygen content in the space enclosed by the covering is less than 0.1 Vol.% over the entire storage period, and the CO₂ content increases to more than 21 to 40 Vol.%, greatly preventing the growth of wood-destroying fungi.
2. Method according to Claim 1, wherein, in order to reduce the adjustment time, the CO₂ content is set to a level in excess of 21 Vol.% by an additional fumigation with CO₂ immediately after beginning of the storage.
3. Method according to Claim 1 or 2, wherein, prior the respiratory and fermentation processes, the volume of the enclosed air is minimized.
4. Method according to Claims 1 to 3, wherein a rigid or flexible enclosure is used as a cover, with the enclosed space being air- and light-tight.
5. Method according to Claims 1 to 4, wherein a single or double, UV-resistant sheet of plastic material (2) with a high diffusion resistance is used as covering material.
6. Method according to Claim 5, wherein a double-layer sheeting (2) is used as a film whose black internal surface prevents the light from penetrating and thereby algae from growing, and whose white external surface reflects the sunlight.
7. Method according to Claim 5 or 6, wherein the two layers of the sheeting (2) are welded either consecutively or simultaneously by double welds (3).
8. Method according to Claim 5 or 6, wherein the two layers of the sheeting (2) are bonded with each other.
9. Method according to Claim 5 or 6, wherein the two-layers of the sheeting (2) lie one upon the other, clamped between two strips (6), tightly wrapped around said strips, and secured by means of a clamping device (7).
10. Method according to Claims 5 to 9, wherein bulkhead fittings (4) for gas measuring flexible tubes (6), which penetrate said sheeting (2), are attached to the sheeting.
11. Method according to Claim 4 or 10, wherein the bulkhead fittings are provided with extension hoses inside the enclosure, and the hose ends pointing to opposite directions in the enclosure.
12. Method according to Claim 11, wherein measuring instruments are connected to the gas measuring flexible tubes through quick-connect couplings, thus enabling to supervise the course of the storage, on the basis of the gas composition.
13. Method according to Claim 4, wherein containers or loading bays are used as rigid enclosure.
14. Method according to Claim 13, wherein the containers or loading bays are supplied with exhaust gases from the combustion processes of the transport vehicles, or stationary plants, respectively.

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