AU616991B2

AU616991B2 - Dehydrator

Info

Publication number: AU616991B2
Application number: AU39574/89A
Authority: AU
Inventors: Jose Luis Ruiz-Avila
Original assignee: AKT Consultants Pty Ltd
Current assignee: AKT Consultants Pty Ltd
Priority date: 1984-10-02
Filing date: 1989-08-11
Publication date: 1991-11-14
Anticipated expiration: 2005-10-02
Also published as: AU3957489A

Description

AKT CONSULTANTS PTY LTD FORM 9 4 0 0 *0 0 0 000 0 0 4 o 04 0 04 4 #0 II O 4 O 0 COMMONWEALTH OF AUSTRALIA Patents Act 1952 1969 COMPLETE PATENT SPECIFICATION FOR THE INVENTION ENTITLED 04 0 040 000 0 0 aA0a a 0

"DHYRAOR

This invention is described in the following statement: 2 THIS INVENTION relates to apparatus for the dehydration of organic material, of the type in which raw material to be dehydrated is passed from an agitating chamber and through inlet and outlet paths of a dehydrating tower by means of a stream of heated air. Such apparatus is used in the production, for example, of fish meal, and the production of dehydrated meal from various organic raw materials such as meat products, waste materials from poultry and fish processing.

fri Apparatus of the type referred to is well known in the c.

art, and generally comprise means for the supply of raw O" material and heated air upstream of the agitating chamber in C' which the material is partially comminuted and dried until its density is such that it is carried upwardly into the dehydrating tower where final dehydration takes place, the fully treated material being recovered from the air stream downstream of the dehydrating tower by suitable means such fo as a cyclone.

Equipment of this type known in the prior art suffers from the disadvantage of being incapable of ready adaptation to different types of feed material, and to feed material of different quality. In addition, the adverse operation of the known dehydrators occurs where the raw material was high or variable liquid content such as might be found in some plant and animal matter. This is particularly the case where liquids such as various flats are rendered from the raw material under influence of heat. Dehydrators generally operate most efficiently where the raw materials are substantially solid and of relatively low moisture content ;i 2::AL- 3 o t *e o 0a 4 4 0 4 oo o 00 1 9 o 0 3 0 o 0a a Sooo *o 0 4 4 4 a and therefore it would be desirable to provide some pretreatment of the raw material.

In one aspect therefore, the invention resides broadly in a process for the dehydration of organic material utilising a dehydration apparatus of the type in which organic mate:rial to be dehydrated is passed from an agitating chamber and through inlet and outlet paths of a dehydrating tower by means of a stream of heated air or gas, the process including the steps of:a) pretreating raw material under the influence of heat and pressure in a tallow extruder to reduce the raw material into a solid fraction and a liquid fraction; b) separating the solid and liquid fractions; c) delivering the solid fraction to the agitator chamber of the dehydration apparatus where it is partially dried and comminuted; d) delivering the partially dried and comminuted solid fraction from the agitating chamber to the dehydrating tower where drying and comminution is completed; and e) recovering the dried comminuted solid fraction.

The process can include the further step of controlling the residence time of material in the dehydration apparatus by varying the path length travelled by the solid fraction in the dehydrating tower.

In another aspect, the invention resides in a dehydration apparatus of the type in which organic material to be dehydrated is passed from an agitating chamber and through inlet and outlet paths of a dehydrating tower by means of a stream of heated air characterised in that the 4 dehydration apparatus includes a fe&i and extruder assembly for extruding raw material therethrough prior to the extruded raw material being delivered to the agitator chamber.

Preferably the tower includes fine and course residence time controls so that the residence time of the material passing through the tower can be accurately controlled or varied. Furthermore the apparatus preferably includes means for extraction of tallow from the organic material prior to its passage to the agitating chamber.

r In order that the invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate a preferred embodiment of the invention and wherein: Fig. 1 is an elevational partly cut away view of the .o4, apparatus of the present invention; Fig. 2 is an elevational end view of the apparatus of .i Fig. 1; Fig. 3 is a plan view of the apparatus; Figs. 4 and 5 illustrate components of the extruder of 0 0 the tallow collection assembly; a e Fig. 6 illustrates details of the fine residence time control arrangement; and Fig. 7 illustrates an alternative form of extruder.

Referring to the drawings there is illustrated dehydration apparatus 10 according to the invention comprising a burner 11 which may be fed with oil or other suitable fuel to provide by means of a blower 12 a stream of hot air or gas through a ducting assembly 13 to an agitator i i i i rC *i 5 *000 88a 0 00 *0 0 4 S 8 a 0 A 0 0 ft O 0 14 and via a dehydration tower 15 to a cyclone 17 from which the dehydrated product is collected.

Associated with the tower 15 and cyclone 17 are respective classifiers 18 and 19 which are arranged to direct solids back into the tower 15 for further drying if required. A vacuum exhaust fan 20 is also linked to the tower 15 so that pneumatic flow through the dehydrator is determined both by the blower of the burner 11 and partial vacuum produced by the fan 20. Located within the ducting assembly 13 to extend longitudinally thereof is a feed and extruder assembly 21 which is adapted to extract tallow from the organic material prior to feeding of the material into the agitator 14.

As shown in Fig. 1, the feed and extruder assembly 21 preferably comprises an auger assembly 22 comprising an auger 23 supported within a cylindrical housing 24 and driven by a variable speed motor 25 and which is fed with the organic material in this instance from one end via a hopper. Located at the opposite end of the auger assembly 22 is an extruder 27 which is shown more clearly in Fig. 4 and 5 and includes an outer perforated frusto-conical casing 28 and an inner extruder screw 29 fixed for rotation with the auger 23. The perforated casing 28 is defined on its outer surface by a plurality of spaced members 30 which define therebetween slots or perforations 31 to permit the extraction of the tallow therethrough. The extruder screw 29 comprises a variable pitch auger which co-operates with the casing 28 in such a manner that the tallow is extruded through the casing perforations 31 and collected whilst the 0*0c 0 0 0 8 6 0 60 1 a a e +a i] 6 0 S 1 4 4 0 So 0 0 0 *08*0*8 6 organic material to be dehydrated passes out of the end of the casing 28 and is fed to the agitator 14 whence it passes into the tower 15 under the influence of hot air or gas.

It will be evident from the above disclosure that a variety of organic materials can be processed through the feed and extruder assembly in order to reduce the liquid content of the organic material prior to the liquid reduced material being delivered to the agitator for comminution and drying. The feed and extruder assembly illustrated is tt't It S located in the heated air stream of ducting assembly 13 so rt t that the extrusion process is enhanced by heating.

tril S Pneumatic flow through the dehydrator tower 15 is determined tt It both by the blower 12 of the burner 11 and the partial vacuum produced by the exhaust fan In this embodiment, the dehydration tower 15 is lot, divided into two tower sections, the first section 32 S including a fine residence time control arrangement for the o oil material and the second section 33 comprising a coarse residence time control arrangement. The first tower section 32 includes a pair of spaced upright baffles 34 and 35, the first baffle 34 defining with a side wall 36 of the tower an

I

inlet path 37 for organic material from the agitator. As shown more clearly in Fig. 6, the upper portion of the baffle 34 is provided with a plurality of transverse slots 38 and a closure assembly 39 is associated with the baffle 34 to selectively close off the slots as desired. The closure assembly 39 includes a closure plate 40 which is slidably engaged with the baffle 34 and preferably maintained in engagement therewith by guide means 41 7 provided on the rear of the plate 40 and slidably engaging the wall 36 of the tower. A similar arrangement is provided for the second baffle 35 except in this instance slots 42 are located in a lower portion thereof and a second closure plate 43 is associated with these slots. Both closure plates 40 and 43 are linked by a cable 44 which passes upwardly over a winch 45 or other driving means so that the respective plates 40 and 43 can be raised or lowered in t opposite directions to thereby vary the number of slots uncovered or covered in the respective baffles 34 and In use material passes upwardly in the tower along the inlet flit lqt i f path 37 over or through the slots in the baffle 34 and :stiff f downwardly between the baffles 34 and 35. It will be seen that when the slots are fully closed the material spends maximum time within the first tower section 32 as it travels 050 *a O approximately two full lengths of the tower passing upwardly on one side of the baffle 34 and downwardly on the other S side thereof to pass into the lower end of the first tower portion 46 of the second tower section.

To vary the residence time in the first tower section

S

32 the respective positions of the closure plates 40 and 43 0 are varied by actuation of the winch 45 so as to open a selected slot or a number of slots. Minimum time residence in the first tower section 32 occurs when the plate 40 is at its lowest position and plate 43 is at its highest position so that the material follows the path shown by the doubleheaded arrow in Fig. 1 to enter into the tower portion 46 half way up its length.

1 i I l~l~ -8- The tower portion 46 is separated from an adjacent portion 48 by an upright fixed baffle 49 so that the material passes upwardly along the tower portion 46 over the baffle 49 and downwardly along the tower portion 48 the latter being separated from a further tower portion 50 by a further upright fixed baffle 51. Thus the material in the air stream passes beneath the baffle 51 and up the tower portion 50 and passes to the cyclone for collection at the S air lock 52. Associated with the two tower portions 48 and r 50 is a course residence time control arrangement in this t instance comprising a flap 52, which in a first position t* I Iq permits the flow of material downwardly along the tower 4t it portion 48 and upwardly along the tower portion 50 whilst in a second position the flap 52 closes off the tower portion 48 at its upper end so that both tower portion 48 and 50 are o et S bypassed permitting flow of material directly to the cyclone from the tower portion 46.

In an alternative for feeding material into the apparatus and as shown in Fig. 7 the tallow collection assembly may be arranged so that the extruder portion is located at the lower end of the auger assembly 22 whilst the organic material is fed to the auger screw 23 via a hopper located at the upper end of the tower. In either instance, it will be seen that the efficient removal of tallow is achieved due to the fact that the tallow collection assembly 21 is disposed within the heated air stream carried by the ducting assembly 13.

If necessary, the fine residence time control arrangement may be shut off completely so that materials may I :111 I----rre 9 simply be directed into the tower portion 46 from the agitator so that the residence time of the material within the dehydration tower is reduced. Of course other arrangements may be used to provide the fine residence time control for example the transverse slots may be replaced by a plurality of apertures in the baffles.

Whilst the above has been given by way of illustrative example, many modifications and variations as would be apparent to persons skilled in the art may be made thereto rrzt i'V without departing from the broad scope and ambit of the V t invention as herein set forth and defined ii the following claims.

4 •o4 o 44 6 a o artr o e

Claims

1. A process for the dehydration of organic material utilising a dehydration apparatus of the type in which organic material to be dehydrated is passed from an agitating chamber and through inlet and outlet paths of a dehydrating tower by means of a stream of heated air or gas, the process including the steps of:- a) pretreating raw material under the influence of heat and pressure in a tallow extruder to reduce the raw material t into an extruded solid fraction and a liquid fraction; b) separating the solid and liquid fractions; c) delivering the solid fraction to the agitating chamber t t of the dehydration apparatus where it is partially dried and comminuted; d) delivering the partially dried and comminuted solid a f7 fraction from the agitating chamber to the dehydrating tower I t a where drying and comminution is completed; and 6 e) recovering the dried comminuted solid fraction.

2. The process according to claim 1 including the further step of controlling the residence time of the organic material in the dehydration apparatus by varying the path J length travelled by the solid fraction in the dehydrating tower.

3. A dehydration apparatus of the type in which organic material to be dehydrated is passed from an agitating chamber and through inlet and outlet paths of a dehydrating tower by means of a stream of heated air characterised in that the dehydration apparatus includes a feed and extruder assembly for extruding raw material therethrough prior to L I i I r;ri;-.ri i 11 the extruded raw material being delivered to the agitator chamber.

4. A dehydration apparatus according to claim 3 wherein cne feed and extruder assembly comprises an auger assembly including an auger within a housing, an inlet to the housing for raw material and an outlet from the housing for the extruded raw material.

A dehydration apparatus according to claim 3 or claim 4 wherein the stream of heated air is in heat exchange relationship with said feed and extruder assembly so as to 0 deliver heat thereto. -t 0

6. A dehydrator apparatus according to claim 4 or claim o a wherein said feed and Ixtruder assembly includes a perforated casing through which liquid rendered from said raw material can be separated from said raw material prior V" to said extruded raw material being delivered to said agitating chamber.

7. A dehydration apparatus according to any one of claims 3 to 6 further including means to vary the residence time of material in said dehydration apparatus.

8. A dehydration apparatus according to claim 7 wherein said means to vary the residence time irL-udes a dividing wall in said dehydrating tower to divide the tower into a plurality of ducts, said wall having a plurality of closable apertures which can be opened or closed to vary the path length of material travelling through the dehydration tower and thereby the residence time of material in the dehydration apparatus. 12

9. A dehydration apparatus according to claim 8 wherein said wall divides the dehydrating tower into Pn upwardly extending duct and a downwardly extending duct, and includes a closure assembly which can be operated to selectively open or close selected ones of said apertures in said wall.

A dehydration apparatus according to claim 8 wherein said dehydrating tower includes two said walls, said walls defining therebetween a duct, a first one of said walls having closable apertures at one end thereof, the other said aJ t wall having closable apertures at an end thereof remote from t the one end of the first said wall, each said wall having a S said closure member to respectively selectively close or open selected ones of said apertures.

11. A dehydration apparatus according to any one of the preceding claims including a di-j;rsion flap located before 0 the outlet path from the tower, the diversion flap being S4 6 operative to in its open position, permit material in the A at tower to travel through the outlee path, and when in its closed position to divert material from the tower.

12. A dehydration apparatus substantially as described 0,14 with refere.ce to the accompanying draftings. I DATED this tenth day of August, 1989. AKT CONSULTANTS PTY LTD By their Patent Attorneys PETER MAXWELL ASSOCIATES