FR2680230A1 - Solar dryer oven allowing the seasoning (drying) of wood - Google Patents

Abstract

The design of the drying oven is based on assimilating the building itself to a solar collector. A washing and sap removal device is also provided. A handling assembly makes it possible to transfer the stacks of wood from washing to oven drying. The unit comprises: - washing and sap removal equipment (A) made up of spray booms (1) and an immersion pool (2), - oven drying equipment (B) making it possible to lower the moisture content from 90 to 30%, made up of a metallic structure (7) supporting solar collectors (5) and two air extractors (8), - handling equipment (6) making it possible to transfer the product into the unit. It is composed of two pallets (9) receiving planks of wood, of a monorail-supporting gantry (portal frame) (11) the monorails being equipped with trolleys (12) and pulleys for lifting and transferring the pallets (9). The method is solely intended for the seasoning of wood and more particularly tropical wood which are highly laden with moisture and sometimes not very accessible.

Description

 The present invention relates to a solar oven allowing progressive drying intended for joinery and cabinetmaking, in particular for working with tropical precious woods.

 Traditional wood drying is done in large capacity ovens using fossil fuels such as fuel.

 The capacities of these ovens, much greater than several tens of m3 of wood per day, are too large in relation to the needs of cabinetmakers on the one hand, and the size of the markets of tropical countries on the other.

 The advantage of the invention of the present solar oven is to better correspond to the requirements of cabinetmakers in terms of capacity of dried wood (8 ms per week), while using solar energy for drying, in the absence of all fossil fuel.

 The design of the oven for drying the wood is based on the assimilation of the building itself to a solar collector, the orientation and the area of the glazing being calculated according to the path of the sun.

 The natural convention of hot air, thus induced by the greenhouse effect, is accelerated using an exhaust fan.

 The location, the flow rate, the on-off sequences of this fan were the subject of detailed calculations.

 The hot air charged with humidity coming from the wood is blown by this fan on an exchanger thus making it possible to recover the water by condensation.

 The water thus recovered passes through a circuit fitted with sprinklers and placed above the stack of wood to be dried, during the drying phase of one week in the oven, there is permanently a supply of calculated amount of water preventing any cracking of the wood by removal.

 The invention also includes a chain for the preliminary treatment of wood before entering the oven. Desiccation to rid the wood of all sap, by immersion of the pile in a basin and forced bubbling by sprinklers.

 Rate: 8 to 10 cubic meters of wood per week.

 Dimensions: boards about 3 meters long.

 Performance: lower the humidity rate from 90 to 30%.

The proposed unit includes three separate pieces of equipment shown in elevation in the overview FIG. 1
- equipment for washing and drying <À)
- steaming equipment (B)
- handling equipment (C)
THE LIFTING EQUIPMENT (A): its purpose is to wash and then immerse the wooden planks so as to evacuate the sap and other possible resins.

 Installed inside a handling circuit, it consists of a set of water spraying booms (1) and an immersion tank (2).

 The spraying assembly (1) is a network of galvanized steel booms on which sprinklers are installed at regular intervals intended to spray pressurized water onto the product to be treated.

 These ramps are installed on each side and on top of the product as shown in the view following F of our plan.

 These same ramps are fed in parallel by a vertical multicellular centrifugal pump (3) whose pressure can rise up to 16 bars and the flow rate is around 17 m3 / hour.

 The pump is supplied from a hydraulic network outside the unit. It is also possible to install on the pump supply circuit, a 3-way valve which allows the water from the immersion tank to be used as soon as it reaches a level compatible with the characteristics of the pump. .

 The immersion tank (2) consists of an envelope of galvanized sheet metal and mounted on a mechanically welded tubular structure.

 In the lower part of the basin (2), a settling tank (4) with emptying is provided in order to possibly recover gasoline and other recyclable resins.

 Finally, in the upper part of the basin and on each side, there are fixed protective plates (13) making it possible to avoid any projection of water outside the unit and so that it drips in. inside of it.

 THE OVENING EQUIPMENT (B): its purpose, from energy, is to reduce the humidity of the product from 90 to 30% in approximately one week.

 Located at the end of the handling circuit, it consists of two insulated facades (14) and a set of solar collector panels (5) placed laterally and in the upper part.

 Each of the facades (6) is made up of insulating sandwich panels (lacquered steel / polyurethane foam) mounted in a metallic structure (7). The end facade is full. The interior facade has two sliding doors (15) also insulated.

 The solar collector panels (5) are assembled metal frames in which is mounted a tinted and waterproof double glazing.

 In addition, on each side of the oven and in the lower part, two humid air extractors (8) are placed with intermittent operation.

In return, flap ventilation openings (only one direction of air circulation) are provided to avoid depressurization of the oven during extractor operation.

 Condensate can be collected to regulate the lowering of the humidity level.

 HANDLING EQUIPMENT (C): its purpose is to transfer the product inside the unit.

 For this purpose, the wood is stored inside two specific pallets (9) with a useful loading volume of approximately 4 m3 each.

 These pallets (9) are of mechanically welded and galvanized tubular structure. Breeding rings are provided for handling the product by hoist, as well as forklift sockets when handling the product outside the wood treatment unit.

 The pallets are transferred from one area of the unit to the other via a gantry (10) designed in mechanically welded steel profiles.

 This gantry (10) supports two monorails (11) on each of which circulate two trolleys (12) equipped with hoist with manual control of 3000 kg payload.

Claims (3)

 1) Process for drying and drying stacks of wood for a modular capacity of 8 to 10 m3 per week approximately, characterized by the fact that the energy used is solar.  2) Method according to claim 1 characterized by the addition of a desiccation system for decanting and recovering the sap.  3) A method according to claim 1 or claim 2 characterized in that the dessevage and drying units can be prefabricated with small dimensions and located in inaccessible areas.