[0001] The invention relates to conditioning apparatus, and particularly apparatus which
conditions a space by cooling it, usually by the introduction of cooling air.
[0002] The space is often a processing space separated from the surroundings by
inter alia the cooling air so that there is a barrier of cooled air between a product in the
space, and the surrounding air.
[0003] Air in particular industries often has particular requirements such as temperature.
Thus in the food industry, a product often has to be handled at a temperature below
10°C to provide hygienic conditions, for example the reduction of bacteria, and for
general preservation during processing. This is so when conveyor systems are used,
say during packaging of a food product. However, to cool the product the required
amount, high cooling power is required, if there is to be consistent cooling. Even
with high cooling power, uneven cooling can occur, both in a conveyor system and in
a room or cabinet, owing to the incursion of uncooled ambient air.
[0004] It is an object of the invention to seek to mitigate these disadvantages.
[0005] According to a first aspect of the invention there is provided apparatus for providing
conditioning medium in a space having at least opposed boundary walls and a base,
and inlet means positioned to direct conditioning medium into the space, the inlet
means comprising a plurality of elongate inlets which are spaced apart vertically
and extend over a desired length of a boundary wall.
[0006] There may be three rows of inlets. This provides a particularly simple, yet effective
construction.
[0007] The middle row of inlets may be closer to the upper row of inlets than to the lower
row of inlets. This provides for a particularly efficient conditioning of the space,
particularly when cooling.
[0008] The upper row of inlets may be narrower, in a vertical sense, than the other two
rows of inlets. This may provide a faster velocity jet at an upper level, so containing
the conditioning medium in the space, particularly when the middle row of inlets may
be wider as considered vertically than the lower row of inlets.
[0009] Each row of inlets may comprise a plurality of discrete slots.
[0010] At least two rows of inlets each may comprise a plurality of elongate blocks each
of which may have a plurality of inlet nozzles.
[0011] Adjacent blocks may have a gap therebetween in the longitudinal direction, or, alternatively
the lower two rows of inlets may comprise contiguous blocks.
[0012] The upper rows of inlets may be directed downwardly into the space at an angle of
inclination of less than 90 °. This contains the jets from the lower inlets in the
space, particularly when the angle of inclination may be about 45°.
[0013] The space may comprise a conveyor trough, and the base may include a conveyor belt
of the trough and the boundary walls may define a path of the conveyor belt.
[0014] Thus the apparatus may comprise a conveyor system.
[0015] There may be a plurality of elongate inlets in each boundary wall, each of which
walls may comprise a duct for supply of conditioning medium to the inlets.
[0016] There may be a source of cooled air as the conditioning medium. This provides for
a cooling environment, say in food processing, and the source may comprise air at
a temperature whereby to provide a temperature in the range 1.5°C to 3.75°C across
the trough.
[0017] The source may provide about 20 litres per second per metre of inlet per trough boundary
wall.
[0018] The inlets may be covered by a filter device, suitably a fabric covering.
[0019] According to a second aspect of the invention, there is provided a method of conditioning
a space, comprising a space having at least opposed boundary walls, a base, and inlet
means positioned to direct conditioning medium into the space, providing that the
inlet means comprises a plurality of elongate inlets which are spaced apart vertically
and extend over a desired length of boundary wall, and by passing a conditioning medium
into the space across the base from one boundary wall towards the other whereby to
condition the space between the boundary walls as desired.
[0020] The method may comprise the step of passing cooled air into the space to cool the
space to a desired temperature range.
[0021] An apparatus and method embodying the invention are hereinafter described, by way
of example, with reference to the accompanying drawings.
Fig. 1 is a perspective schematic view of a conveyor trough system according to the
invention;
Fig. 2 is a perspective view of part of a boundary wall of the system of Fig. 1, to
an enlarged scale, and showing part of a series of inlets;
Fig. 3 shows a similar view to that of Fig. 2, showing more of the inlets in elevation;
Figs. 4 and 5 show respectively in elevation two further embodiments of inlets;
Fig. 6 is a graph showing temperature along a three metre length of conveyor at the
centre line thereof, using the apparatus of Fig. 1; and
Fig. 7 shows air jet speeds along a three metre length of the apparatus of Fig. 1.
[0022] Referring to the drawings there is shown apparatus 1 for providing conditioning medium
in a space 2 having at least opposed boundary walls 3 and a base 4, and inlet means
5 positioned to direct conditioning medium into the space 2, the inlet means 5 comprising
a plurality of elongate inlets 6, 7, 8 which are spaced apart vertically and extend
over a desired length of boundary wall 3.
[0023] In the embodiment shown, the space 2 is a space defined between opposed boundary
walls 3 of a conveyor system, the base 4 including a conveyor device in the form of
a belt on which product such as a food product to be conditioned as by being cooled
is conveyed.
[0024] There are two opposed boundary walls with the conveyor belt, which forms a base of
the space therebetween for conveying a product through the space. A trough conveyor
is thus provided. In the embodiment there are inlet means 5 in the form of three vertically
arranged rows of elongate inlets 6, 7, 8, each row being fed with conditioning medium
in the form of cold air from a duct 9 which is part of, or contiguous with, a boundary
wall 3 on the side of that wall remote from the conveyor 4. The duct 9 is fed with
conditioning medium in the form of cooled air from a source (not shown) of that air.
Each inlet 6, 7, 8 is a row of discrete slots in Figs. 1 - 3, the upper row 6 as viewed
being of a depth or narrower, (i.e. as considered vertically) which is of less depth
than the respective slots 7, 8, the middle row of slots 7 being closer vertically
to the uppermost row of slots 6 than it is to the lowest row 8.
[0025] The middle row of slots 7 is wider (as considered vertically) than the lowest row
8 and thus is the widest (vertically) of the three rows.
[0026] There may be inlets in only one boundary wall 3, or in both boundary walls, in which
latter case the inlets are directed towards each other into the space between the
boundary walls, and above the conveyor 4.
[0027] In either case, when there is a flow of cooled air of 20 litres per second per meter
of inlets per side, the temperature at the centre line of the conveyor ranges from
about 1.5°C (at a position about 1.3m along the 3m length) to 3.6°C at or adjacent
the start of that length (Fig. 6). Thus using the invention, the space is conditioned
by being cooled well below ambient temperature throughout the length of the conveyor
4, thereby enhancing the processing of product such as food conveyed through the space
2 on the conveyor.
[0028] Using the invention, microbial tests show that using three slots vertically arranged
in rows of inlets fed from ducts, fewer than 10 counts of microbes per test plate
were found on plates in the trough.
[0029] In a modification using a filter device such as a fabric over the inlets, microbial
counts were between 5 and 24. This is in contrast to a count of between 400 and 600
outside the trough formed by the boundary walls and the conveyor. The speed of air
jets along a 3 metre length of duct shows a variation of between 2.6 m/s and 0.3 m/s,
depending on the position along the three metre length.
[0030] In a modification, the inlets may comprise blocks 10 having inlet nozzles 10'. Thus
in Fig .4, the blocks 10 in a row of inlets 7, 8 are contiguous; in Fig. 5 they are
spaced apart longitudinally by spaces 11.
[0031] In all embodiments, the upper, vertically narrowest, row of inlets may be angled
into the space, in the embodiment at an angle of 45° to the vertical. This provides
a relatively fast flow of cold air downwardly into the space, which impinges on the
generally horizontal flows from the middle and lowermost inlets, whereby to protect
that flow from the (lower) inlets from contamination by entrained ambient air, and
thus to maintain a desired cold environment in the trough.
[0032] In a modification, not shown, the inlets may be covered with a filter device such
as a fabric.
[0033] It will be understood that other modifications are possible, for example the space
may be a cabinet or chamber rather than a conveyor trough kind of apparatus as shown.
[0034] Using the invention, the air temperature and integrity of the space is maintained
at a desired, cooled, level, with respect to ambient conditions outside the space.
1. Apparatus for providing conditioning medium in a space having at least opposed boundary
walls and a base, characterised by inlet means (5) positioned to direct conditioning
medium into the space (2), and by the inlet means (5) comprising a plurality of elongate
inlets (6, 7, 8) which are spaced apart vertically and extend over a desired length
of a boundary wall (3).
2. Apparatus according to Claim 1, characterised by three rows of inlets (6, 7, 8).
3. Apparatus according to Claim 2, characterised by the middle row of inlets (7) being
closer to the upper row of inlets (6) than to the lower row of inlets (8).
4. Apparatus according to Claim 2 or 3, characterised by the upper row of inlets (6)
being narrower, in a vertical sense, than the other two rows of inlets (7, 8).
5. Apparatus according to Claim 4, characterised by the middle row of inlets (7) being
wider than the lower row of inlets (6, 8).
6. Apparatus according to any preceding claim, characterised by each row of inlets (6,
7, 8) comprising a plurality of discrete slots.
7. Apparatus according to Claims 6, characterised by at least two rows of inlets (7,
8) each comprising a plurality of elongate blocks (10) each of which has a plurality
of inlet nozzles.
8. Apparatus according to Claim 7, characterised by adjacent blocks (10) having a gap
(11) therebetween.
9. Apparatus according to Claim 7, characterised by the lower two rows of inlets (7,
8) comprising contiguous blocks (10).
10. Apparatus according to any of Claims 2 to 9, characterised by the upper row of inlets
(6) being directed downwardly into the space (2) at an angle of inclination of less
than 90°.
11. Apparatus according to Claim 10, characterised by the angle of inclination being
about 45°.
12. Apparatus according to any preceding claim, characterised by the space (2) comprising
a conveyor trough, and by the base including a conveyor belt (4) of the trough and
the boundary walls (3) defining a path of the conveyor belt (4).
13. Apparatus according to Claim 12, characterised by there being a plurality of elongate
inlets (6, 7, 8) in each boundary wall (3).
14. Apparatus according to Claim 13, characterised by each boundary wall (3) comprising
a duct (9) for supply of conditioning medium to the inlets.
15. Apparatus according to Claim 14, characterised by comprising a source of cooled air
as the conditioning medium.
16. Apparatus according to Claim 15, characterised by the source comprising air at a
temperature whereby to provide a temperature in the range 1.5°C to 3.75°C across the
trough.
17. Apparatus according to Claim 16, characterised by the source providing about 20 litres
per second per metre of inlet per trough boundary wall.
18. Apparatus according to Claim 16 or Claim 17, characterised by the inlets (6, 7, 8)
being covered by a filter device.
19. Apparatus according to Claim 18, characterised by the filter device comprising a
fabric covering.
20. A method of conditioning a space, characterised by providing a space (2) having at
least opposed boundary walls (3), a base (4), and inlet means (5) positioned to direct
conditioning medium into the space (2), by providing that the inlet means (5) comprises
a plurality of elongate inlets (6, 7, 8) which are spaced apart vertically and extend
over a desired length of boundary wall (3), and by passing a conditioning medium into
the space (2) across the base (4) from one boundary wall (3) towards the other whereby
to condition the space between the boundary walls as desired.
21. A method according to Claim 20, characterised by comprising the step of passing cooled
air into the space (2) to cool that space to a desired temperature range.
23. A method according to Claim 21, substantially as hereinbefore defined.