Note: Descriptions are shown in the official language in which they were submitted.
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AIR FLOOR GRATING
FIELD OF INVENTION
This invention is based on Provisional Application
0
entitled "Air Floor Grating" filed December 12, 1995 and
~ claims the priority filing date of that application. The
invention relates to the curing phase of the composting
process. More specifically, the invention is directed to a
unique air-floor design and method of construction which
permits modular installation over existing non-aeration floors
and for use by a complete new spectrum of end users from home
owners to commercial plant operators.
BACKGROUND OF THE INVENTION
Prior art systems for curing compost commonly utilize a
concrete floor containing rectangular trenches in which is
laid perforated pipe the ends of which are supplied air from a
common plenum. The pipes are overlaid with gravel to form a
distribution system to permit front end loaders to traverse
the floor and turn the compost periodically. A major problem
of such systems is non-uniform air distribution resulting in
unreliable curing of the compost. Another problem normally
encountered in the use of such systems is clogging of the
floor air vents necessitating shut down of the system until
the vents have been cleared. A concomitant problem that
' results as the vents become clogged is that pressure required
to maintain desired air flow increases. Consequently, blowers
of increased capacity are needed to insure optimum curing
conditions to offset the effects of variable back pressure
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caused by clogging of the air vents. The above problems
result in unproductive down time with attendant increase in
the cost of operation. A still further problem of existing
air distribution systems for compost curing is their
complexity and cost. The present invention provides a
solution to these problems. It is also to be noted that full
use of the subject air floor grating system reduces
maintenance requirements and improves effectiveness of the
curing process. The air channels are more easily accessed and
cleaned and the overall cost of the curing system is
substantially reduced. Another aspect of the invention is the
unique method of assembly of the systems elements and their
adaptability to existing non-aeration floors and other diverse
uses as explained below.
The structural element comprising this invention is
designed both to support a 2-3 meter depth of compost and
allow air to pass freely through the structural element.
Further, the element has the feature that the air passages
will not plug even under traffic by rubber tired vehicles
which normally would tend to compress and mat the compost on
top of the element or in the orifices and consequently cause
the compost to block the air passages.
A BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a plan view of an air floor grating element '
embodying one aspect of the invention;
E'ig. 2 is a side view of the grating shown in Fig. 1;
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Fig. 3 is a cross-sectional view of one of the grating taken
along the cutting plane 3-3 shown in Fig. 1;
Fig. 4 is a partial sectional view of the air floor element
a
taken along the cutting plane 4-4 shown in Fig. 1;
~ 5 Fig. 5a and 5b depict dimensional details of one preferred
form of structural element;
Fig. 6 - 8 depict examples of the diverse uses to which the
grating element can be put;
Fig. 9 shows an interlocking feature and one method of
l0 installation, and
Fig. 10 illustrates an alternative form of grating support
structure.
DETAINED DESCRIPTION OF THE INVENTION
Referring to Fig. 1 of the drawing, there is shown a
15 structural element 10. By way of illustration the dimensions
of preferred forms of air passages 12 are shown in Fig. 4 and
Figs. 5a and 5b. One example of a preferred structural
element having the requisite strength and resistance to
corrosion is made of polypropylene. The unit shown in Fig. 1
20 contains 29 air slots whose narrowest openings 14 (Fig. 4) at
its compost-contacting surface is approximately 1/16 of an
inch. Each slot is 4 1/2 inches in lateral dimension. As
seen in Fig. 4 the slot is tapered and at its base 16 is 1/2
' inch wide. An alternative form of air slot designed to achieve
25 the save objectives as the air slot shown in Fig. 1 is
detailed in Figs. 5A and 5B. The air slot as show in those
figures has an air slot which is 50 mils wide at the top
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tapering in three steps to 3/4 of an inch at its base. A
preferred form of grate is 2 feet in overall length, 6 3/4
inches wide and 3/4 inch thick. Each grate is provided with
a
interlocking tab portions 18. The design of the air slots
insure that compost entering the slot does not plug the
opening but falls through the grate openings into the trench
below providing a self cleaning unit. The unit, in the
application described, has a load bearing capacity of up to
400 lbs./sq.ft.; is capable of passing no less than 5 cubic
i0 ft. per minute of air per linear foot or grate; is self
cleaning and non-plugging; will not break or crack when run
over by a rubber tired vehicle; and is relatively inexpensive
and capable of withstanding the organic acids to which it is
exposed in the curing process. The grating elements are of a
size and weight permitting installation of an air floor by
individual home owners as well as installation by commercial
users over existing floors or other surfaces. The air grating
elements can be interconnected as seen in Fig. 9 to service
any given design area. The grating can supported on pressure
treated 4x4 wooden members 20 as seen in Fig. 9 or other forms
of support means made of concrete, plastic, or other suitable
material meetina the reauisite strPnrrth a"~ .-~,-,-~~; "n
resistance requirements. One such alternative form of support
structure is illustrated in Fig_ 10. As seen in that Figure,
the support Z1 is precast from concrete or other suitable
material configured for retention of grates 10. This unique
grating design permits air floors to be installed
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expeditiously and economically to meet any variety of
operating conditions. To prevent sidewise movement of the
grates containment strips 22 are employed. To prevent
lengthwise movement of the grates they can be blocked at both
ends by means not shown. The grate is designed to be
supported on its edge portions 24. The support means 20 are
spaced to limit the bending moment to which the grate itself
may be subjected. The short span allows the bending moment
placed on the element to be within the structured limits of
io the plastic used while allowing the bulk of the load from a
rubber tired vehicle to rest on the sides of the trench formed
by the support means 20 across which the grating system spans.
The trench 26 formed under the grates provides a plenum
through which air is delivered to the grates and is designed
to accommodate the gradual build up of compost passing through
the grates without inhibiting air flow through the grates.
Periodic clean up of material which has passed through the
grates is easily done by removal of the grates or by providing
access under the grates for mechanized or manual cleaning. By
way of example Figs 6, 7 and 8 illustrate a number of the
diverse uses to. which the grating can be put. Fig. 6 depicts
its use in the floor of a bioconversion bay of the type shown
in United States Patent Number 5,583,045
filed January 30, 1995 assigned to the assignee of the subject
invention.
Fig. 7 depicts its use as a backyard composter and
Fig. 8 shows its use in connection with an outdoor Windrow of
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the type depicted in PCT publication WO 97/01519 which
was filed on 24 June 1996 and assigned to the assignee of
the subject invention.
The light weight and structural
form of. the grating elements make it readily adaptable to
compost curing processes of variable size and complexity.
As noted above, the grate consists of a short structural
span fabricated from tough plastic polymers or co-polymers
provided with a series of narrow slit or air passages of
to unique configuration. The air passages have a narrow slit at
the top of the opening, the width of which gets progressively
wider as its depth increases down through the grate. This
progressive widening prevents material that is pressed into
the slit from compacting and plugging the openings and permits
the material to fall into the trench below resulting in~self
cleaning of the unit.
The lengths of the grates have to be short enough that
they can be fabricated in conventional injection molding
equipment. A nominal two foot length meets this requirement.
2o The elements are interlocking so that they cannot easily be
displaced from the trench by passing of a front end loader
although in some applications it may be possible to eliminate
the use of the interlocking tabs.
Also to facilitate rapid cooling in the fabrication of
the unit in a mold and therefore hold fabrication costs down,
it is desirable that the thicknesses of each part of the grate
not exceed 3/8 inches and preferable be less than 1l4 inch.
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It will be understood that structural and dimensional
modifications differing from those described and illustrated
will be required to meet varying circumstances and that the
present invention may be embodied in other specific forms
without departing from the spirit or essential attributes
thereof and, accordingly, reference should be made to the
appended claims rather than to the foregoing specification as
indicating the scope of the invention.
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