AU600362B2

AU600362B2 - Apparatus for drying a stream of fibrous material

Info

Publication number: AU600362B2
Application number: AU16929/88A
Authority: AU
Inventors: Ross Shepherd
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-05-28
Filing date: 1988-05-27
Publication date: 1990-08-09
Anticipated expiration: 2008-05-27
Also published as: AU1692988A

Description

j AUSTRALIA 3 6 2 PatentIs Act t COMPLETE SPECIFICATION

(ORIGINAL)

Class Int, Class Application Number; Lodged: Thi document con tains thel annendmn-ts Mde tinder Section 49 and is correct for printin Complete Specification Lodged: Pr~ority Related Art: Accepted; Name(s) of Applicant(s): Address(es) of Applicant's): Actual Inventor(s)', Address for Service is APPLICANT'S REF.

ROSS SHEPHERD 33 Martin Place Glen WaverJtay 3149 Victoria Australia Ross Shepherd C.A.P. of PI 2192 PHJ LUL 3 ORMONDE AND FITZPATRICKC Patent and Trade Mark Attorneys 367 Collins Street Melbourne, Australia, 3000 Complete Specifiction for the invention entitled: e%~ ~r WW *Y*r *-Wk O'Hnb statenment Is a full description of this invention, including the best method of performing it known to P1944 ombkft rrxslur~nrrraur~ nrrmrr~ This invention relates generally to the drying of fibrous materials and in particular to an apparatus for drying a scream of fibrous material. It will be hereinafter convenient to describe the invention with particular reference to wool, although the invention has wider application.

Before raw wool can be further processed, it is necessary to clean and degrease that wool via a "scouring" process. After the scouring has been completed, it is necessary to dry the wool before final baling. Apparatus known as "drum dryers" are generally used for this purpose.

Drum' dryers of the foregoing kind generally include an enclosure having an inlet and outlet through which a stream of wool may be passed into and out of respe> .ively and a plurality of drying drums rotatably supported within the enclosure although dryers may consist of a single drum only.

The drying drums are supported about their longitudinal axes, which are arranged in a spaced apart, at least substantially parallel, relationship and lie in a common plane. The drums each have an outer drying surface over which the stream of wool passes in succession. A plurality of apertures extend through the outer surface to the interior of each drum. Means are provided to circulate air within the enclosure and to deaw air from the interior of each drum. This produces a negative pressure differential from the outer surfaces to the interior 11 of ea h drum. Wool may be drawn against the outer surfaces of the drying drums by the resulting suction effect during passage thereover.

Means are also provided to heat the air circulated S: within the enclosure which acts as the drying medium.

The wool to be dried is fed into the inlet of the enclosure and entrained by the fiist drum encountered. The drums are rotated slowly on their axes, adjacent drums rotating in the opposite direction to each other. Because tne drums are closely spaced, the wool held on one drum is transferred to the next successive drum at or near the area where the drums are at their closest approach. The wooi is sequentially transferred along successive drums to the outlet of the enclosure.

In the drum driers described above, only a maximum of about half the outer surface area of each drum is used at any one time to hold the wool for drying.

It would be advantageous if a greater portion of the drum could be used because the wool could then be held longer on each drum thereby increasing the residence time of the wool to optimise the drying and/oi reducing the numbers of drums required.

It is therefore an object of the present invention to provide an improved apparatus for drying a stream of fibrous material, With this obje in mind, the present invention provides an apparatus f drying a stream of fibrous material, including: an enclosure having an inlet and an outlet through which a jtream of fibrous material is passed into and out of the enclosure, respectively, a plurality of drying drums rotatably supported about their longitudinal axes within the enclosure in a consecutive arangement between the inlet and outlet, the drums each having an outer drying surface over which the fibrous material stream passes in succession, the outer surfaces each having a plurality of apertures extending therethrough to the interior of the drum, air circulation means to circulate air within the enclosure and to draw air from the interior of each drum so as to produce a negative S pressure differential from the outer surfaces to the interior of the drum and thereby draw the fibrous material stream against the outer surfaces during passage thereover, and heating means to heat at least a pcrtion of the circulating air so as to dry the fibrous material, the longitudinal axes S of the drums being arranged in a spaced apart, at least substantially parallel, relationship and being staggered in a zig-zag configuration with adjacent drums being closely spaced whereby the fibrous material stream extends asubtatial of the outer sur a of each drying drum in succession.

r, u e r 1 a po a no. Fibro mtri t a .on mhf of M- a h- 1- Fof-a I Aryli -rf.co The air circulation means preferably includes at least one fan and directing means to direct air from the interior of the drum to the at least one fan. The directing means preferably L includes at least one primary duct provided between an open -3- /o c 0 I end of each drum to the at least one fan to direct air from the interior of each of the drums to the at least one fan, The directing means may also further include at least one branch duct directing air from outside the enclosure to the at least one primary duct. The heating means is preferably located adjacent or within the at least one branch duct to heat the air passing through the at least one branch duct into 4 the at least one primary duct.

In a preferred form the apparatus pretdrably includes a plurality of fans adjacent respective drums, the fan nearest the inlet of the enclosure directing a portion of the circulating air out of the enclosure. The heating means may alternatively or alsobe preferably located within the enclosure to heat the circulating air or be located in the interior of each of the drums.

The following description refers in more detail to the various features of the apparatus of the present invention. To facilitate an understanding of the invention, reference is made in the description to the accompanying drawings where the apparatus is illustrated in a preferred embodiment, It is to be understood that the apparatus of the present invention is not limited to the preferred embodiment as illustrated in the drawings.

Figure 1 is a schematic longitudinal crosssectional view of a prior art apparatus for drying a stream of fibrous material.

Figure 2 is a schematic longitudinal crosssectional view of the apparatus of the present invention, Figure 3 is a schematic transverse cross-sectional view of the apparatus of the present invention.

Figure 1 illustrates the drum arrangement of a prior art drying apparatus which includes an enclosure 1 having aa inlet 2 and an outlet 3 and a plurality of drums 4 having longitudinal axes 5, each drum 4 being rotatabl> supported within the enclosure 1. The axes 5 are arranged in a spaced apart, at least su~stantially parallel relationship and lie in a common plane. The drums 4 are closely spaced to allow a stream of fibrous material 7 to pass in succession over the outer surfaces 6 of each successive drum 4.

Figure 2 illustrates the drum arrangement of the I _J I drying apparatus of the present invention. The same reference numerals are used for components corresponding to those of the prior art apparatus. Unlike the prior art apparatus, the longitudinal axes 5 of the drums 4 are arranged in a spaced apart, at least substantially parallel relationship and are staggered in a zig-zag configuration.

With the drums arranged in this staggered arrangement, the fibrous material 7 carried by a drum 4 must travel a greater distance on the outer surface 6 of that drum 4 before being transferred to the next adjacent drum 4. This allows the stream of fibrous material 7 to extend about a substantial portion of the outer surface 6 of each drying drum 4 in succession. Therefore, during operation of the drying appartcus greater than half of the drum outer surface 6 of each drum 4 may be used at any time to support the fibrous material 7 being dried. The advantage of this arrangement is that it increases the residence time of the fibrous material stream 7 on each drum 4 optimising the drying of the fibrous material stream 7 and/or reducing the number of drums 4 required relative to the prior art apparatus for the same amount of drying.

Figure 3 illustrates in further detail the mounting of each of the drums 4 and the air circulation means provided in the apparatus, r Preferably, one end of each drum 4 is blanked off with an end wall 8 while the other end has an opening 19, Preferably each drum 4 is rotatably supported at the one end by a rotatable bearing arrangement, such as a shaft 9 extending from the centre of the end wall 8 of the drum 4 and supported in a bearing 10 mounted on a side wall of the enclosure I.

Preferably the other end of each drum is supported upon a roller arirangement 11 that may engage the cuter surface 6 of the drum 4 surrounding the open end 19, The outer surface 6 of each drum 4 is preferably made from perforated metal having apertures 12 to permit the pas.age of air through the outer surface 6.

Preferably the air circulation means includes at least one fan 13 such as a multivare volute fan. Preferably,

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It 1 a plurality of fans 13 are provided, each being mounted adjacent a respective open end 19 of each drum 4. Each fan 13 acts to draw air out from the interior of the drum 4 into the surrounding enclosure. The air is then preferably directed both vertically upwards and downwards so as to impact against the roof and the floor of the enclosure 1 respectively.

Circulating air is then drawn back to the drums 4 by the sue effect produced by the fans 13 thereby completing the circulating motion 14 of the air within the enclosure 1.

Preferably a primary duct 15 is in the form of inlet cone is provided between the open end 19 of each of the drums 4 and the suction opening \of each of the volute fans 13 for directing air to those fans, Moreover a branch duct 17 preferably extends frcm each primary duct 15 to the exterior of the enclosure 1. This branch duct 17 allows incoming air to enter the primary duct 15 from outside the enclosure and be subsequently mixed with the already circulating air. The branch duct 17 may include a series of ducts each extending from a respective branch duct 15. The primary and branch ducts are preferably fixed within the enclosure 1 relative to the rotatable drums 4. Air heating means 18 may be located in any suitable location that enables heating of the air circulating within the enclosure 1. In that regard, the air may be heated before it enters the enclosure 1 and/or whilst circulating within that enclosure 4 44 4: 44 To that end the heating means 18 may be mounted adjacent or within the primary or branch ducts. The heating means 18 may be located adjacent the inlets to the branch ducts 17. That creates a pressure difference between the surrounding atmosphere and the inlets causing surrounding air to be drawn towards the heating means 18 and subsequently into the branch ducts 17. This arrangement, known as an "induced draft passage", allows heated air to be drawn into the enclosure 1 without the need for auxiliary fans.

In another arrangement the heating means 18 may be located within or otherwise communicate directly with the enclosure 1 for heating air circulating therein. That heating means 18 may be positioned in an enclosure wall, such as an end wall, Alternatively the heating means may be located i-6- Lpil-'~

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s t, G~ El"Psr within the drums 4.

One or more gas heaters may b.e preferably used as the heating means 18.

The volute fan 13 mounted on the drum 4 closest to the inlet 2 of the enclosure 1 preferably directs a portion of the air passing through that fan 13 out of the enclosure 1. This produces sub-atmospheric pressure within the enclosure 1 which minimises the loss of heated air from the enclosure 1. Because the above fan 13 is mounted near the inlet 2 of the enclosure 1, a secondary pressure gradient is also produced within the enclosure 1. This pressure gradient effects a general movement of the air within the enclosure 1 from the outlet 3 to the inlet 2 of the enclosure.

Preferably, the greatest proportion of the drying occurs on the drums 4 nearest the inlet 2 when the fibrous material is at its wettest state. The air is heated as it passses through the enclosure 1, so that the warmest air can be provided near the inlet 2 of the enclosure 1.

It will be appreciated that various modificacions and/or alterations may be made without departing from the scope of the present invention as defined in the claims appended hereto.

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Claims

1. Apparatus for drying a stream of fibrous material, including: an enclosure having an inlet and an outlet through which a stream of fibrous material is passed into and out of the enclosure, respectively, a plurality of drying drums rotatably supported about their longitudinal axes within the enclosure in a consecutive arrangement between the inlet and outlet, the drums each having an outer drying surface over which the fibrous material stream passes in succession, the outer surfaces each having a plurality of apertures extending therethrough to the interior of the drum, air circulation means to circulate air within the enclosure and to draw air from the interior of each drum so as to produce a negative pressure differential from the outer surfaces to the interior of the drum and thereby draw the fibrous material stream against the outer surfaces during passage thereover, and heating means to heat at least a portion of the circulating air so as to dry the fibrous material, the longitudinal axes of the drums being arranged in a spaced apart, at least substantially parallel, relationship and being staggered in a zig-zag configuration with adjacent drums being closely spaced whereby the fibrous material stream extends over more than half of the outer drying surface of each drying drum in succession.

2. Apparatus as claimed in claim 1, wherein the air circulation means includes at least one fan and directing means to direct air from the interior of the drum to the at least one fan.

3. Apparatus as claimed in clai.n 2, wherein the dicecting means includes at least one primary duct provided between an open end of each drum to the at least one fan to direct air from the interior of each of the drums to the at least one fan.

4. Apparatus as claimed in claim 3, wherein the directing means further includes at least one branch duct directing air from outside the enclosure to the at least one primary duct.

Apparatus as Claimed in claim 4, wherein the -I heating means is located adjacent or within the at least one branch duct to heat the air passing through the at least one branch duct into the at least one primary duct.

6. Apparatus as claimed in any one of claims 2 to wherein a plurality of fans are provided adjacent respective drums, the fan nearest the inlet of the enclosure directing a portion of the circulating air out of the enclosure.

7. Apparatus as claimed in any preceding claim, wherein the heating means is located within the enclosure to heat the circulating air.

8. Apparatus as claimed in any preceding claim, wherein the heating means is located in the interior of each of the drums.

9. Apparatus for drying a stream of fibrous material, substantially as herein particularly described with respect to what is shown in Figs. 2 and 3 of the accompanying drawingi. DATED: 23 May 1990 PHILLIPS ORMONDE FITZPATRICK Attorneys for: ROSS SHEPHERD T t 4 0 4 z -9- V1F %4 mc