IL87301A - Apparatus and method for storing grain - Google Patents

Description

APPARATUS AND METHOD FOR STORING GRAIN .□'HAT oTCPN noien ipnn STATE OF ISRAEL -MINISTRY OF AGRICULTURE and AMERICAN JEWISH WORLD SERVICE Inventors: Dr. Shlomo Navarro Dr. Ezra Donahaye Ben-Ami Zi 1 berstei n C:06913 FIELD OF THE INVENTION The present invention relates generally to storage containers and storage methods and, particularly, to containers and methods for storing grain.

BACKGROUND OF THE INVENTION In the field of grain storage, various ways, including the use of conventional-type warehouse and silos are known and widely used.

The way in which grain is stored may be critical, particularly when considering emergency grain storage in famine-stricken regions, which occur particularly in Third World countries. Among factors to be considered when storing grain are the following: a. the cost of building the storage apparatus and transporting it, b. the availability of skilled local manpower, c. the ground preparation necessary and the level of mechanization required for building the storage apparatus, d. the climate in which the grain is to be stored and e. the level of insect infestation to be tolerated within the stored mass of grain.

Among storage structures known for the emergency storage of grain is a relatively large scale structure for the bulk storage of grain, as described in an article entitled 'Airtight Storage of Wheat in a Temporary Structure formed by PVC and Polyethylene Liners' written by S. Navarro and E. Donahaye 06913 29.3.95 1 87301/2 (among the present inventors), Y. Kashanchi, V. Pisarev and 0. Bulbul and published in ISRAEL AGRESEARCH, 1:11, 1987, pp. 101 -114.

The article describes bulk storage of approximately 15,565 tons of wheat in a shallow earth bunker in which a selected plastic underliner is used and, once filled with the grain, over which a PVC overliner is placed. Around the entire periphery of the bunker, the edges of the underliner and the overliner meet and are buried in earth so as to provide a hermetic seal.

An additional storage structure known is the Haogenplast Mobile Grain Silo, manufactured by HAOGENPLAST LTD., Plastic Industries, Kibbutz Haogen, 42880, Israel. The Mobile Silo is intended for bulk storage of grain and is available in different sizes corresponding to grain storage capacities varying between 250 and 1000 tons.

The Mobile Silo may be erected on a site that has been levelled and cleared of sharp objects and it comprises a circular wire mesh fence, a plastic liner covering the ground surface surrounded by the fence and covering the fence and a plastic cover which, once the grain to be stored has been placed within the Mobile Silo, is joined to the plastic liner so as to provide a hermetic seal. There is also provided an aeration system which permits constant control of temperature and humidity within the body of the silo.

Great emphasis is placed upon the hermetic sealing of the above-described storage structures. It has been found that a major problem encountered in wheat storage in that of insect infestation and that hermetic sealing of the structure can reduce this problem considerably. Once a storage structure has been sealed, initial insect activity consumes the available oxygen and the level of carbon dioxide rises. Once the level of oxygen drops 06913 29.3.95 2 87301/2 below a certain minimum level required to maintain insect activity, the insects are eliminated. Thus, when providing a hermetically sealed storage structure, insect infestation can be controlled without the use of chemical pesticides.

It will be appreciated, however, that the above-described storage structures are more suitable bulk storage of grain which requires grain handling to be mechanized. In particular, the storage structure to Navarro et al is intended for storage of 1000 tonnes of grain and over.

In addition, machinery and skilled manpower are required for construction of the structures whether this be for excavating the earth bunker in the structure to Navarro et al or for construction of the mobile silo. 06913 29.3.95 3 87301/2 SUMMARY OF THE INVENTION It is an aim of the present invention to provide an inexpensive, easy-to-handle container for the storage of grain which does not require machinery for handling the grain.

It is a further aim of the present invention to provide a container for . the storage of grain that requires substantially no field preparation prior to its erection.

It is yet a further aim of the present invention to provide a container for the storage of grain that obviates the need for chemical residual pesticides.

There is provided, therefore, in accordance with an embodiment of the invention, a reusable, portable, foldable and frameless storage container for storing sacks of dry grain, wherein the container defines a grain storage volume and is formed of a flexible material which is resistant to ultraviolet radiation and which is substantially impermeable to gas.

Additionally in accordance with an embodiment of the invention, the container comprises a base having upwardly extending edge portions, a cover having downwardly extending edge portions, means for providing a substantially gas impermeable seal between the base and the cover, and means for maintaining the edge portions of the base and the cover in a substantially taught configuration, thereby preventing tooth-holds for rodents.

Further in accordance with an embodiment of the invention, the container also includes apparatus for supplying gas to the storage volume so as to modify the atmosphere therewithin and thereby to further prevent insect infestation of the grain. The container may also include means for releasing excess gas pressure from the storage volume. 06913 29.3.95 87301/2 In accordance with an embodiment of the invention, the gas comprises one or a mixture of carbon dioxide nitrogen and a fumigant .

Further, in accordance with an embodiment of the invention, the flexible material is a compound based on polyvinyl chloride, and remains resilient at sub-zero temperatures.

In accordance with an alternative embodiment of the invention, there is provided a method of storing sacks of dry without need for ground preparation or machinery for transportation and erection, the method comprising the steps of laying out on a grain storage site, without the use of machinery, a frameless, foldable container formed of a flexible material which is resistant to ultraviolet radiation and which is substantially impermeable to gas; filling the container with sacks of dry grain; and closing the container with an air-tight seal, to prevent insect infestation and rodent penetration.

Additionally according to the method of the invention, the container comprises a base having upwardly extending edges and a cover having downwardly extending edges; and the step of laying out the container comprises the step of laying out the base on the storage site, the step of filling the container comprises loading layers of sacks of dry grain onto the base and the step of closing comprises the steps of spreading the cover over the loaded grain sacks, sealing together the edges of the base and the cover and stretching tautly the edges of the base and cover by means of straps fixedly attached thereto. 06913 29.3.95 5 87301/2 BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be understood and appreciated from the following detailed description, taken in conjunction with the drawings, in which: Fig. 1 is a schematic illustration of a partially loaded grain storage container base, constructed according to a preferred embodiment of the present invention; Fig. 2 is a schematic illustration showing the grain storage container base of Fig. 1 when fully laden and a preferred stacking arrangement of grain sacks therein; Fig. 3 shows the fully laden grain storage container base of Fig. 2 after a cover therefor has been placed thereover and prior to securing of the cover to the base; Fig. 4 shows the grain storage container shown in Fig. 3 after securing of the cover to the base and sealing together thereof ; Fig. 5 shows the base and cover of the storage container shown in Figs. 3 and 4, but wherein the base and cover have been collapsed prior to packing for reuse; and Fig. 6 shows a carrier for the collapsed grain storage container as shown in Fig. 5; Fig. 7A is a graph showing a variation of gas concentration in the container of the present invention over a selected period of time; and Fig. 7B is a graph showing temperature variation and distribution in the container of the present invention over a period of time including the time period represented in the graph of Fig. 7A. 06913 29.3.95 6 87301/2 DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Reference is made to Figs. 1 to 6, in which there is shown, in various stages of use, a grain storage container, referenced generally 10, constructed in accordance with a preferred embodiment of the present invention.

Container 10 is intended for use particularly in drought-stricken regions and it is characterized, therefore, by being inexpensive to manufacture, easy to transport and requiring no machinery for its on-site erection and loading. It furthermore requires substantially no ground preparation on site and provides ample protection against the weather while preventing any substantial insect infestation.

As shown, therefore, container 10 comprises a base 12 and a cover 14 made of a flexible, substantially gas impermeable and ultraviolet radiation resistant material. A typical material is food grade PVC (polyvinyl chloride) which has physical properties as listed in the non-limiting example set forth below: Typical properties of the material used for manufacture of the container 10 of the present invention.

Permitted water vapor permeation of about 8 grams per square meter per twenty four hours at 38 degrees celsius and relative humidity of 90%.

Permitted oxygen gas permeation of about 407 milliliters per square meter per twenty four hours.

Permitted carbon dioxide gas permeation of about 2355 milliliters per square meter per twenty four hours. 06913 29.3.95 7 87301/2 Minimum tensile strength according to ASTM (American Standard Test Methods) D-882, lengthwise 200 Kilograms per square centimeter, crosswise 185 Kilograms per square centimeter.

Elongation at break according to ASTM D-882, length 290%, transverse 305%.

Tear propagation according to ASTM D-1004, angle tear test, length: 75 kg/cm, transverse: 71.6 kg/cm.

Shrinkage at zero degrees celsius compared to 35 degrees celsius is 0.9%.

Dimensional changes at 100 degrees celsius according to ASTM D-1204 in fifteen minutes, length -1.19%, transverse +0.50%.

Coefficient of linear expansion between 0.007 and 0.025% per degree celsius.

Weight per unit area according to ASTM D-374, 1140 grams per square meter.

Impact cold crack according to BS 3424 is at -25 degrees celsius.

Cold bend temperature test according to BS 2782 Method 104A, passed at -50 degrees celsius.

Volatile loss at 100 degrees celsius according to ASTM D-1023, Method A 1.93%, Method B 1.56%.

Base 12 and cover 14 are configured so as to be sealable along respective adjacent edges 16 and 18. According to a preferred embodiment of the invention there is provided a zipper (not shown) along the entire length of the common edge which provides a substantially hermetic seal therealong. 06913 29.3.95 8 87301/2 As described in the Background of the Invention, sealing of the volume defined by container 10 when closed is instrumental in eliminating insect infestation of partially affected grain. As shown in Fig. 7A, after a relatively short period of time, due to insect activity, the oxygen level within the sealed volume drops to a critical level thereby preventing further insect activity within the container. In the shown example, the critical oxygen level has been reached after approximately nine days.

With particular reference to Fig. 3, there are also provided straps 20, each of which is fastened at a first end 22, as by hot melting or gluing, to cover 14 and at a second end 24, typically by means of a buckle. The use of straps 20 is intended to ensure that the side walls of base 12 are taut and; therefore, flat, in order to reduce the chance of penetration into container 10 by, for example, rodents by eliminating possible tooth-holds.

With reference to Figs. 1 to 6, a method of storing grain using container 10 of the present invention will now be described. As an initial step, (Fig. 1), base 12 is laid out over a selected storage site which does not require any substantial surface preparation, although it should be generally flat and cleared of sharp objects. According to the present embodiment of the invention, a typical range of container capacity is 5 to 50 tons of grain sacks and covering a ground area typically ranging from approximately 5 to 39.5 square meters. According to the present embodiment, the grain is stored in sacks 26.

As shown, sacks 26 are laid out on base 12 preferably in layers, each layer being laid transverse to the layer below. It will be appreciated that container 10, which is designed for the storage of sacks of grain on a relatively small scale eliminates the need for any grain loading machinery as used with loose grain storage silos. Furthermore, the respective capacities 06913 29.3.95 9 of differently sized containers are generally such that a single truck load of grain sacks, typically five tons or a multiple thereof, completely fills a single container.

As shown in Fig. 2, it is preferred that a single row 28 of sacks 26 is laid out along the longitudinal axis of the stack. This ensures that when cover 14 is positioned (Figs. 3 and 4), it receives a pitched configuration and thus prevents water collection thereon.

Once cover 14 has been placed in position, edges 16 and 18 of base 12 and cover 14 are sealed by means of a zipper (not shown) and straps 20 are secured. Container 10 is shown completely secured and sealed in Fig. 4.

According to an alternative embodiment of the invention, there is also provided a gas inlet port 30 for the optional supply of gas under pressure to the internal volume of container 10, once sealed. Accordingly, there is also provided an excess pressure outlet port 31 (Figs. 3 and 4). Although, as stated above, the rate at which oxygen is consumed by any insects already living within the grain is sufficiently high to reduce the oxygen level to the critical level, this process is time dependent .

Therefore, in order to prevent even partial infestation, the atmosphere within container 10 may be modified by supplying, via inlet port 30, carbon dioxide gas, nitrogen gas, a mixture of carbon dioxide and nitrogen gas or a fumigant gas so as to immediately kill any insects present in the grain.

With particular reference to Figs. 5 and 6, once container 10 has been emptied of all the stored sacks of grain, both base 12 and cover 14 may be folded down, rolled up (Fig. 5) and loaded into a carrier 32 (Fig. 6) for transportation to and reuse at another location. 06913 29.3.95 10 It will be appreciated by persons skilled in the art that the present invention is not limited by what has been shown and described hereinabove, The scope of the invention is limited, rather, solely by the claims, which follow: 06913 29.3.95 11

Claims (17)

1. A reusable, portable container for storing sacks of dry grain comprising a frameless, foldable container which defines a grain storage volume wherein the container is formed of a flexible material which is resistant to ultraviolet radiation and which is substantially impermeable to gas.

2. A container according to claim 1, and wherein the container comprises: a base having upwardly extending edge portions; a cover having downwardly extending edge portions; means for providing a substantially gas impermeable seal between the base and the cover; and means for maintaining the edge portions of the base and the cover in a substantially taut configuration, thereby preventing tooth-holds for rodents.

3. A container according to either claim 1 or claim 2, and also including means for supplying gas under pressure to the storage volume.

4. A container according to claim 3, and also including means for releasing excess gas pressure in the storage volume.

5. A container according to claim 3 or 4, and wherein the gas comprises one or a mixture of carbon dioxide, nitrogen, and a fumigant.

6. A container according to any of the previous claims, and wherein the flexible material is a compound based on polyvinyl chloride.

7. A container according to claim 6 wherein the flexible material remains resilient at sub-zero temperatures. 06913 29.3.95 12

8. A method of storing sacks of dry grain without need for ground preparation or machinery for transportation and erection, comprising the following steps: laying out on a grain storage site, without the use of machinery, a frameless, foldable container formed of a flexible material which is resistant to ultraviolet radiation and which is substantially impermeable to gas; filling the container with sacks of dry grain; and closing the container with an air-tight seal, to prevent insect infestation and rodent penetration.

9. A method according to claim 8, and wherein the container comprises: a base having upwardly extending edges; and a cover having downwardly extending edges; and wherein the step of laying out the container comprises the step of laying out the base on the storage site, the step of filling the container comprises loading layers of sacks of dry grain onto the base and the step of closing comprises the steps of spreading the cover over the loaded grain sacks, sealing together the edges of the base and the cover and stretching tautly the edges of the base and cover by means of straps fixedly attached thereto.

10. A method according to claim 9, and also including the additional step, subsequent to the step of closing, of supplying gas under pressure to the storage volume.

11. A method according to claim 10, and wherein the gas comprises one or a mixture of carbon dioxide, nitrogen, and a fumigant .

12. A method according to any of claims 8-11, and wherein the flexible material is a compound based on polyvinyl chloride. 06913 29.3.95 13 87301/3

13. A method according to claim 12 wherein the flexible material remains resilient at sub-zero temperatures.

14. A container according to any of claims 1-7 substantially as described hereinabove.

15. A container according to any of claims 1-7 substantially as shown in any of the drawings.

16. A method according to any of claims 8-12 substantially as described hereinabove.

17. A method according to any of claims 8-12 substantially as shown in any of the drawings. For the Applicant, Sart or T. Colb C.06913 06913 29.3.95 14