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Title:
A METHOD AND AN ARRANGEMENT FOR STORING ORGANIC FIBROUS MATERIAL IN A STACK
Document Type and Number:
WIPO Patent Application WO/1980/002573
Kind Code:
A1
Abstract:
Method of storing organic fibrous material in a stack (1). To increase, in an energy-technical optimal way, the heat content of the material, air is blown into the stack (1) at a number of different levels depending on the height of the stack and at each level, at a number of points evenly distributed over the cross-section of the stack. At said levels and at a distance from the air blowing-in points air is sucked out of the stack. The temperature of the sucked-out air at mainly each suction point is made to control the blowing-in of air at the adjoining blowing-in points so that the temperature of the fibrous material is kept within a predetermined temperature range. The water and heat contained in the sucked-out air is collected and at least some of the air thus dried and cooled is used for blowing into the stack (1).

Inventors:
Larsson C.
Application Number:
PCT/SE1979/000107
Publication Date:
November 27, 1980
Filing Date:
May 15, 1979
Export Citation:
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Assignee:
Larsson C.
International Classes:
D21B1/38; F26B9/10; F26B21/04; F26B21/10; F26B25/22; (IPC1-7): D21C1/00; C10F5/00; F24J3/04; F26B9/10
Foreign References:
DE2646622A1
DE2754032A1
SE399247B1978-02-06
US0722118A
SE391544B
SE387310B
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Claims:
P a t e n t C l a i m s
1. A method of storing organic fibrous material in a stack (1), barn or the like, characterised in that air is blown.into the stack (1) at a number of different level depending on the height of the stack and at each level, at a number of points preferably evenly distributed over the crosssection of the stack, that at points located at the said levels and at a distance from the air blowingin points in the stack, air is sucked out of the stack, that the temperature of the air is measured approximately at each suction point and controls the blowingin of air at the adjoining blowingin points so that the temperature of the material in the stack is kept within a predetermined temperature range, that the water and heat contained in the suckedout air is collected, and that at least some of the air thus dried and cooled is used for blowing into the stack (1).
2. A method according to Patent Claim 1, characterised in that the generation of heat in the stack is accelerated and intensified by making up the stored fibrous material from a mixture of different types and size categories of organic fibrous material.
3. A method according to Patent Claim 2, characterised in that the different types of.fibrous material in the mixture consist of birch chips, ground bark and other fibrous waste, together with chips from pine trees and forest waste containing needles.
4. A method according to Claim 3, characterised in that the grainsize for the coarsely chopped birch chips should exceed 30 mm, for forest waste it should lie in the range 5 10 mm, and for bark and other fibrous waste it should be less than 5 mm. OMPI .
5. A method according to any one of the preceding Claims, characterised in that during storage the organic fibrous material is dried, new material being added from the top of the stack or the equivalent, and that the dried material is taken out from the bottom.
6. A method according to Patent Claim 1, characterised in that the storage is carried out in a chamber v/hich is divided off from the atmosphere and is insulated.
7. An arrangement for carrying out the method according to Patent Claim 1, comprising pipes (2) connected via valves (12) to the pressure side of a f n (13) and perforated over at least part of their length, for blow¬ ing air into the stack, a control unit (11.) which actuates the valves and is connected to the temperature indicators (10) for monitoring the temperature of the material in the stack, this unit being designed to control the blow¬ ingof air into the stack so that the temperature of the material lies within a predetermined temperature range, characterised in that the pipes (2) for blowing air in are arranged vertically and have perforations so that blowingin is. effected at the said levels, that the temp¬ erature indicators (10) are arranged in the pipes (6) which are perforated and are orientated in a corresponding way to the blowingin pipes (2) and are arranged at a distance from the latter, and which are connected to the suction side of the fan (13), and that in the connection between the suction pipes (6) and the fan (13) a heat exchanger and demoisturising unit (15) is provided.
8. An arrangement according to Patent Claim 3» character ised in that the pipes (2) for blowing air in are divided into a number of chambers (3, 4, 5) located one behind the other in the longitudinal direction, and that OMPI Λ, WIPO a line is connected to each of the chambers so that each chamber can be set under overpressure individually. OMPI WIPO '.
Description:
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The present invention relates to a method of storing organic fibrous material in a stack, barn or the like. The invention also relates to an arrangement for carrying . out this method, comprising a pipe which is perforated over at least part of its length and is connected via valves to the pressure side of a fan for blowing air into the stack, and a control unit which actuates the valves, connected to a temperature indicator for. onitoring the temperature of the material in the stack, this unit being designed to control the blowing in of air into the stack so that the temperature of the material lies within a pre¬ determined temperature range.

During recent years considerable progress has been made in the field of tree and timber handling. To ensure the best use is made of the raw fibrous material, methods and machines for tree-felling, transportation and handling of whole tree trunks, branches and.boughs, together with the excavation of the root systems, have been proposed. It has thus been possible to achieve a high level of ex- ploitation of the raw timber in sawmills and pulp factories. As for the question of exploiting the fibrous waste from tree-felling to produce energy, development has not advanced so far. Research has shown that only 8% of Swedish timber terrain is of such a nature that it is necessary to leave the timber waste behind. Since leaving behind timber waste such as stumps, branches and twigs results in an increased risk of damaging insects, it is important to remove waste timber. It can also be shown that the energy content of timber waste is so high that with rationalised transportation and storage methods profitable exploitation of the timber waste can be achieved.

The aim of the present invention is to provide a method and an arrangement for storing fibroua material in a stack, this storage being effected in such a way that

the heat content of the material is increased as the ther mal energy released during storage is used, and this is made possible due to the fact that the storage is carried out as revealed in the characteristics in the attached Patent Claims.

The invention will be explained further in the following with reference to the attached Drawing, in whic Figure 1 shows in the form of a block diagram an arrange¬ ment which operates in the way proposed by the invention. Figure 2 shows schematically a preferred embodiment of a barn for storing organic.fibrous material. Figure 3a shows in perspective how, according-to the invention, per forated pipes are arranged vertically for blowing air int the stack and for sucking out warmed up and moist air. Figure 3 is a detail from Figure 3-=-* and shows how the perforated pipes may be fixed in the floor of the barn. Figure is a cross-section through the barn shown in Figure 2. Figure 5 shows an alternative embodiment of an arrangement according to. the invention. In the Drawing, parts with the same or similar functions have been given the same reference numerals.

In Figure 1, 1 is a stack which contains organic fibrous material such as chips, bark and/or so-called organic industrial waste, for example. The stack is assumed to be lying in a well-insulated chamber of the kind which will be described in more detail in connection with Figures 2 - 4. According to the invention, air is blown into the stack at a number of levels depending on the height of the stack, and at each level, at a number of points preferably distributed evenly over the cross- section of the stack. This is accomplished by means of a plurality of pipes 2 which are disposed vertically and ar perforated over at least part of their length and are pre ferably divided up in the longitudinal direction into chambers 3 ? - ? 5 which are separated from each other.

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According to the invention, the-air is sucked out from the said levels by means of vertically arranged perforated pipes 6 of the same type as the pipes 2, arranged at a distance from the latter. The pipes 6 are also divided up into chambers 7, 8, 9. At each of the said levels the pipes 6 are equipped with a temperature indicator 10 which is connected to a control unit 11. The pipes 2 are connec¬ ted via a valve element 12 to the pressure side of a fan 13 ? and the pipes 6 are connected via a valve element 14 and a combined heat-exchanger and demoisturiser 15 to the suction side of the fan 3. The valve elements 12, 14 are connected to and controlled by the control unit 11. Via the control unit 11 which actuates the valve elements 12, 14, the temperature measured at each suction point by means of the temperature indicator 10 controls the blowing in of air so that the temperature of the material in the stack is kept within a predetermined temperature range. It will readily be appreciated that the biological processes which take place in a stack of organic fibrous material produce a considerable amount of heat energy which can even cause self-ignition. At the start, the fibrous material in the stack has a relatively high water-content which must be reduced so that the combustion level of the fibrous material will be sufficiently high with regard to fuel economy. Due to the heat produced, the water is vapourised and as a result is sucked out of the stack with the air. According to the invention the water and heat content of the sucked-out air is * collected., after which the air, thus dried and cooled, is used for blowing into the stack 1. The collected heat may be used for heating purposes of various kinds, such as, for example, for dry¬ ing timber or for heating areas of a sawmill. According to a special characteristic Of the invention, the genera¬ tion of heat in the stack can be accelerated and intensi- fied by making up the stored fibrous material from a

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mixture of different types and different. size categories of organic fibrous material, for example, birch chips, ground bark and other fibrous waste, together with chips of coniferous trees and forest waste containing needles. So that the fibrous material may be stored under the best conditions and so that the considerable amount of heat energy which is formed during storage may be made use of, according to the invention storage should be carried out indoors in a barn of the type which is shown schematically in Figures 2 - 4. As can be seen in Fig¬ ure 4, the barn is made.up of corrugated sheet which at the same time is a roof, the long side 16 being held in place by roof trusses 17 whic are supported on baseplates 18. The gable ends are in the shape of a triangle with a base of approximately 30 and a height of approximately 32 m. The barn is extended expediently in sections . according to requirements, but is preferably approximately 100 m.. The stack in the barn is fed in from above, for example, by a belt or screw conveyor 19 arranged under the ridge of the barn, in the longitudinal direction thereσf; see Figure 3. The fibrous material is delivered from the conveyor via inlet openings 20 along the conveyor 19. Thes may be opened and closed so that it is possible to control where along the longitudinal extent of the barn delivery will take place. Removal from the barn is effected by means of conveyors 21 which move from the longitudinal sides of the barn towards a conveyor 22 arranged in the centre of the barn in its floor, or above this, directly under the conveyor 1 . The blowing-in pipes 2 are fixed in the floor 23 of the barn between the conveyors 21 (see Figure 4) and are supplied via pressure lines 24 laid out in the floor. Plates 25 bent into an angle are provided as protection for the blowing-in pipes 2. The suction pipes 6 are con- nected to a suction line 26 and are suspended from the

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roof of the barn. Figure 4 also shows how the fan 13, driven by an electromotor 27, may be connected to suction lines 26 and to the pressure lines 24 via a heat-exchanger/ demoisturiser 15. The condensed water from the sucked-out air is conducted away via a line 28.

In the alternative embodiment of the invention shown schematically in Figure 5» the blowing-in and suction pipes 2, 6 are not made of perforated pipe divided .up into chambers, which are preferred, but not essential. The said pipes consist of a number of separate pipes of various lengths, perforated at different levels so that blowing- in and suction can be effected as described earlier. The blowing-in and suction is controlled as before, by the control unit 11 via motors 2 acting on the valve elements 12, 14; only one of these motors is shown in the Figure. The temperature indicator 10 is connected to the control unit 11 via a connection box 30. The control unit 11 is made up of a chart recorder 31 with relay outputs 32. The outputs have a memory -function so as to simplify the con- struction of the control unit.

Obviously, the invention may be varied in many ways within the scope of the concept of the invention.

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