A Quick Dryer System

for Wet Moulded clay Bricks and a Kiln

Incorporating The Same

This Invention relates to a quick dryer system for wet moulded (i.e. with high water content) clay bricks utilizing effluent heat from brick kilns. It also relates to a kiln incorporating such waste heat recovery and quick dryer system for drying and baking green (Raw) moulded wet bricks.

An essential feature and necessity in making bricks of soft and porous quality is the four to five days of yard drying time taken for green (wet) bricks to be ready for stacking and storing.

For several reasons bricks have to be "laid" (moulded) in single layers with 15-20% of moisture: and not on the ground as is present practice. This high moisture level is dictated by considerations of mouldability of the wet clay, and porosity needs of the burnt brick: Other relevant factors are durability for various purposes, light weight, low thermal conductivity, easy handling, bonding between bricks, and "breathing" of moisture in diverse weathers. The softness of such clay when moulded in machine makes it imperative to lay bricks in single layer on the palette: this palette is again a necessity for speed drying and for handling. Open air drying, as of necessity to be in the shade, takes up to 4-5 days and involves large numbers of palettes-several times the actual minimum requirement - vitiating such factors as handling, stocking and cost. Hence quick drying is indicated as a necessity rather than as an option: This in turn indicates a need for green bricks to be exposed on all faces to hot ambient air: which again implies turning the bricks over across the drying sequence.

We therefore propose to devise a system of drying which meets these requirements and particularly will make do with only 2.5% (1/40) of the number of palettes needed for the nearly primitive open air dryer system in a shelter shed.

This invention therefore provides a quick dryer system for wet moulded clay bricks that reduces drying time from the moulding stage to kiln entry stage to just around 3 hours... a remarkable reduction indeed... with much less handling and without allowing cracking, warping, breaking or distortions of the finished products.

This quick dryer is conceived and adapted to be preferably incorporated atop a linear tunnel kiln and is an efficient, hassle free system for not only fast drying but also for efficient utilization of large amounts of generated heat (energy) which would otherwise dissipate into the atmosphere aggravating the much detested global warming. Being enclosed- and virtually wrapped up-integrally with a tunnel kiln, it greatly enhances the efficacy of the dryer; it is, besides compact, easily fabricated, is efficient in operation, and needs minimal manpower.

Without restricting its applications, thus, we may state that it is eminently adaptable and suited for a tunnel kiln which, typically, has a length of about 50m (160ft) of rectangular or squarish cross section, say 1.0m high and up to 1.5m wide on the inside. Such a kiln generally comprises three segments: a pre- combustion chamber, a central burner portion, and post burning heat exchange chamber where the hot burnt bricks give up much of their heat to the inflow air for combustion.

Correspondingly, then, the novel dryer device of the invention is of rectangular construction, generally matching the tunnel kiln of its application, and has atleast two, typically five, roller conveyors in tandem, in zigzag fashion, one below the other such
that moulded wet bricks which may be laid at one end are transported by the conveyor to the start of the next, at which junction an inverting device of invention inverts and thus reveals a fresh surface to the passing hot air and transfars each palette to the next conveyor beneath, for its next run.

It is preferred that the palettes with bricks, follow the run of the conveyers from the top, progressively to its bottom as they encounter a cross current of hot air from the perforated hot air wall adjacent.

The conveyor set is located in a closed rectangular elongate housing into which raw wet bricks on palettes may be fed from the top from a brick moulding machine. The conveyor housing has a hot air - chamber attached to it on the side such that heat is transferred to the bricks by ingress by a blower F of hot are across the partitioning wall having numerous specifically scattered perforations. As a preferred alternative - and this a better embodiment - the hot air chamber bifurcates the conveyor chamber into two so that these flank it on both sides, each having its own conveyor set.

Preferably also in an embodiment the hot air chamber tapers towards the top, wild the conveyor chamber is uniform, with a consequential parallelogram profile. This enables faster exit of used air to the outside.

As already indicated the conveyor set is located in a closed elongate housing into which raw wet bricks, stacked on palettes with their longest dimension preferably transverse to the direction of motion, may be fed from the top from a brick laying machine. The conveyor housing gets hot air, induced by a blower from the adjacent hot air chamber via the partition wall which has numerous perforations expressly for the purpose. The preferred embodiment, as already stated, has a central hot air chamber sharing its two walls with two conveyor belt system on both sides, each system supplied from its own brick moulding machine. The entire conveyor chamber is further enveloped on its outer walls by a fuel gas jacket that further helps wet bricks in its stages of drying.
This invention will now be described in further detail of method and performance by help of the figures of the accompanying drawings, wherein:

Figure la depicts a novel dryer device of the invention, juxtaposed on a typical application namely a tunnel kiln,
Figures lb and lc depict, respectively, a double conveyor chamber dryer and a single conveyor chamber dryer, of figure la,

Figures 2a and 2b show respectively side and front elevations of the novel inverter device for palettes used in the invention, and,

Figure 2c indicates its relative location of the inverter device at the confluence of two successive conveyors.

The wet brick dryer of the invention is depicted (Figure la, lb, lc) by reference numeral 1.

Numerals 2,3,4,5 and 6 show the five conveyors carrying palettes P with bricks 9 on them.

Inverter devices 10 comprised of short, side - open cylinders with screw threaded shafts S1, S2 which pass via screw sockets (not shown) and protrude into the cylinder space from diametrically opposite directions, each carrying palettes P1,P2 (loaded or empty).

The screw wheels (not shown) are operable by limit switches (not shown) and motors Ml, M2 fixed on the cylinder wall to move the two shafts towards or away from each other to grip or release brick palettes between them..

Moulding machines (not shown) at the top of the dryer units, one for each, feed the top most conveyors with batches of say five bricks on each palette P, P: these are carried down the conveyors on rollers which are preferably run by worms and screw shafts at one of their two ends, down and along the drying chamber with regular inversions at each end of the conveyor. The bricks encounter cross current of hot air from the kiln via the hot - air vent, at an optimum draw temperature of 100°c which rise from the bottom, travel upward from the hot air vent, i.e. about 2m high and diffuse through the dryer wall into the conveyor housing. The wet bricks, after several inversions and progressive drying, emerge from the exit of the last conveyor to be sent off for burning, storage or standby. It is to be reiterated here that perforations on the walls of le, (The hot gas vent leading out of the kiln below) are graded, spaced and sized to enable optimum cross current of hot gas over the palattes of bricks, and pass out and beyond from the far walls, also similarly perforated, thus leaving no possibility of moisture condensations.
The inverter device is explained simply enough: as a palette loaded with bricks approaches down to the end of its conveyor, the inverter is ready to receive it on its lower C rail pair R2 R2 - which operation is enabled by pusher elements, not shown, or by sheer gravity. This is followed by the upper (empty) palette - which was rendered empty before the inversion and eviction of the then lower palette into the conveyor - being pushed by Motor Ml acting on its shaft, to repose gently, controlled by limit switches or

such, not shown, on top of the brick batch B on the lower palette. Now the set of bricks between this two - top and bottom - palettes are ready for inversion, which action is accomplished by the device borne say by supports RSl-Rs4 being given a half revolution on its axis by known means, not shown, such as a gear and motor around its rim(not shown). The next step sees the now top palette being lifted off the bricks, leaving uncovered the surface which hither to - down the previous conveyor - was covered by virtue of resting in it; and the thus inverted brick batch is ready to slide down the lower conveyor with a fresh surface exposed and on top.
Another possible embodiment of the inverter has a side- open channel, or C shaped housing bearing the inverter elements.
An exemplary operational step needs a typical time of 43 seconds for a 5 brick
palette, on a basis of ten thousand bricks for a day or 3 shifts.— that is, 8.64
v 10,000
seconds, or 43 seconds per palette (=8.64X5) which means 14,400 bricks in a two sided
dryer chamber, needing 5 runs.
The large number of perforations on the conveyor chamber wall facing the hot air chamber enables the hot gases to diffuse and transgress over the brick palettes, and ensure gradual yet progressive drying of the bricks. Palettes with bricks may be pushed gently into the inverter in and out by mechanical pushers or by sheer gravity: no further explanation is deemed necessary on this point: one good idea is to give a small incline to the conveyor at its run end: this tips it easily into the inverter.
The dryer unit of this invention may be deemed as a separate entity by itself, without even the brick laying machines, or as incorporated with a tunnel kiln or such matchable unit.

In a preferred embodiment, the walls of the conveyor housing on both sides, namely to that on the hot air vent and on the outer wall, have an upwardly inward taper as illustrated (lb, lc) the purpose of this being to enable more uniform distribution of hot air in the inner vent surface, and to diffuse the spent hot gases more evenly out of the conveyor chamber.
Another preferred option of the dryer, seen in figure lb, has the dryer system of the invention with a width 10% to 20% larger than the kiln it surmounts, its overhang on both sides beyond the kiln width beneath being occupied by a jacket of hot air which is led up to the overhang above and upwards into the outlet. This feature is shown by dotted lines: fig lb and has the advantage of using the kiln-side heat to further push up the exhaust from the dryer.
The incorporation of this dryer unit into a brick kiln will give maximum production, output quality, with minimum space, high economy and environment friendly performance.

This description, read with reference to the drawings accompanying it is deemed to be sufficiently adequate for an understanding of the salient novel futures of the invention, whose scope is however to be perceived from the broad features of the claims appended hereinafter and not from the specific embodiment borne out in the illustrative examples of the description.

The claims

I Claim:

1. A quick dryer system for wet moulded clay bricks, with high moisture content,
said dryer comprising,

a pair of elongate chambers flanking a passage for hot dry air with blower means for forcing said air into said passage,

each chamber housing at least two conveyor means for carrying palettes loaded with single layers of wet bricks,

said conveyor means arranged in zigzag fashion one beneath the next,
inverting means to receive and invert at least one palette with bricks at a time and convey it to the next lower conveyor exposing a fresh surface to hot dry air,

said conveyors each having an inlet at topmost end to receive bricks-on-palettes from an automatic wet brick moulding machine, with an outlet at the far bottom end to deliver dried bricks for storage or baking,

and said each chamber having perforation means for transgress of hot dry air from said passage (for hot air) into said chambers of the conveyor means.

2. A quick dryer system as claimed in claim 1 wherein the whole system is covered with an outer jacket with space for exit of hot effluent gases from the kiln, said jacket space being fed with hot effluent gas from the kiln.

3. A quick dryer system as claimed in claim l, wherein said passage for hot dryer has graded perforations for ingress of hot air into and across the conveyors for drying the bricks.

4. A quick dryer system as claimed in claim 1, wherein the number of conveyors is five.

5. A quick dryer system as claimed in claim 1, wherein a single chamber, on only one of the said passage, is provided.

6. A quick dryer system as claimed in claim 1, where is said inverting means comprises,

a housing mounted to be rotatable about an axis perpendicular to the conveyor directions, and located at the converging place of each two successive conveyors,

said housing having an opening to receive a palette of bricks on to a receptacle adjustably located therein,

another empty palette, also located therein, adjustable to or away from the received palette to clamp and hold or relax the bricks with the bottom palette,

means to rotate the housing about its axis, half a revolution at a time, to expose the now top surface by lifting the now top palette,

and means to receive, at time of entry, and to expel, after inversion, the palette of bricks from one conveyor on to the next, below.

7. A quick dryer system as claimed in claim 1, wherein each palette carries on it five bricks, all their lengths transverse to the conveyor motion and at least 2cm gap between the bricks on the palette.

8. A quick dryer system as claimed in claim 1, wherein said adjustable location of the palettes of the inverting means are adjustable by motor means, springs and limit switches.

9. A quick dryer system as claimed in claim 1, wherein said palette locations are adjustable by screw shafts mounting the palettes and operable by rotation by motor means mounted on the housing.

10. A quick dryer system as claimed in claim 1, wherein said dryer is located straddling a tunnel kiln, along the top length thereof, wherein, hot air from the hot bricks side of the kiln is directed by blower means up into the hot air passage between the conveyors down which the wet brick palettes are descended from top to bottom.

11. A quick dryer system as claimed in claim 1, wherein said conveyors are of the roller type, said rollers being driven by gear or chain drive.

12. A brick making kiln for turning bricks, with a quick drying unit as claimed in any of claims 1 to 11, said drying located on the top length of the kiln, a passage for hot air being provided from near the exiting burnt bricks exit passage, into the chamber between or beside the conveyors said hot air being drawn at a temperature range of 100°C-120°C.

13. The tunnel kiln as in claim 12, wherein, the quick- dryer system is 20% wider than the kiln below.

14.A quick dryer system for wet moulded clay bricks for automation of a brick kiln, substantially, as hereinbefore illustrated and described.

15. A quick dryer system for wet moulded clay bricks, and a kiln in incorporating the same, substantially as hereinbefore described with reference to the accompanying drawings.