FORM 2
THE PATENTS ACT 70
(ACT 39 OF 70)
COMPLETE SPECIFICATION
( See Section 10)
TITLE
A HERMETIC PRESSURE LEAF FILTER FOR DRY DEWAXING AND WINTERISATION WITHOUT FILTER AID
APPLICANT DESMET BALLESTRA INDIA PVT LTD
An Indian Company Apeejay Chambers 5, Wallace Street
Fort Area Mumbai-400 001
The following description particularly describes the nature of the invention and the manner in which it is to be performed

FIELD OF INVENTION:
The present invention relates to an improved design of a filter for oils and more particularly relates to a hermetic pressure leaf filter for dry dewaxing and winterization of vegetable oils without using any filter aid
BACKGROUND OF THE INVENTION:
Vegetable oils are essential commodities which are increasingly marketed as refined vegetable oils in small branded packs.
Oils like sunflower oil and rice bran oil contain high melting esters called waxes which impart turbid appearance to the refined oil especially in the winter. Oils like cottonseed oil and rice bran oil contain saturated tri-glycerides which also impart turbid appearance to the refined oil especially in the winter. Such appearance of turbidity is not desired especially in small packs as it has negative impact on aesthetic appeal of the oil. The dewaxing or winterization process is used to separate these waxes / saturated tri-g!ycerides from the oil so that this turbidity is eliminated / restricted.
The dewaxing or winterization process consists of crystallization of waxes / saturated tri-glycerides by controlled cooling of the oil over a given period of time. This is followed by separation of the crystallized waxes / saturated tri-glyce rides by filtration.
Various types of filtration equipment traditionally and currently in use such as Plate and frame filter press, Horizontal pressure leaf filters, Plate and frame type filters with heating / cooling arrangement have their considerable limitations in many aspects.
In the convention system, Plate and Frame Filter Press can be used on all oils which require removal of waxes or saturated tri-glycerides to improve its clarity in winter. Waxes can be free of filter aid and are in solid/semisolid form which is economical for subsequent oil recovery. After oil recovery the waxes are sold as valuable by products. Filtered oil quality can be monitored in special designs. The feed can be distributed from one or two corner or center channels to the filter plate pack. However, the clearance between individual filter plates is limited to the thickness of the wax layer desired. From these feed channels (or core) the feed is distributed through smaller ports to individual plates at corner/ or center. Thus uniform distribution is a serious limitation as the feed first contacts the part of filtration area nearest to the feed channel. This leads to early growth of layer of waxes near the feed ports and resists further the distribution of feed to the filtration area farther from the feed port. Also after formation of layer of waxes on the filtration area there is no flow path available for the blowing air. Moreover, filtration can be made automatic only in special design and wax discharge cannot be easily done automatic as the waxes are very sticky. Possible to filter at higher pressure but is of limited use because of limitations in the feed/blowing air distribution. Waxes are removed by scrapping in simpler designs. Advanced designs attempt to remove waxes by shaking but are not reliable due to stickiness of the waxes. The scrapping / shaking reduce the life of the filter fabric used in the filter plates.
In the Horizontal Pressure Leaf Filter system, though hermetic operation is possible, it can be used only on sunflower oil with waxes less than 1000 to 1500 ppm. The filter aid is

required as filter elements are metallic wire mesh type. The waxes are contaminated with filter aid are discharged in solid form and no oil recovery is easily possible due to contamination with filter aid. Moreover, waxes plus filter aid are disposed as a waste product. The system limits the use of the facility of washing of the filter elements after several filtration cycles at high temperature to improve filterability and facility to cool the layer of waxes / saturated tri-glycerides formed on filtration area to maintain its mechanical strength to prevent its crushing and ensuring better filterability.
The Plate and Frame Type Filters with Heating / Cooling arrangement can be used on all oils which require the separation of waxes or saturated tri-glycerides. However, hermetic operation is not possible and each filter element drains into an open trough. Though waxes are free of filter aid but are in molten form. This is not economical for subsequent oil recovery as the waxes need to be re-solidified. All filter operations are generally manual and filtered oil quality cannot be easily monitored. Furthermore, it limits the facility of filtration and blowing at higher pressures. Waxes are removed as liquid only by complete melting. This leads to overheating of the fabric which reduces its life.
As seen that each traditional type of filter used for separation of waxes / tri-glycerides allows a few advantages but always combined with serious limitations.
Therefore, no traditional design of filter for separation of waxes / tri-glycerides is truly versatile as each design has severaf limitations. Moreover, the modern edibleoff processing industry increasingly focuses on food safety, automation and reduction in costs on manpower, maintenance, utilities and consumables. There are no current designs which could satisfy these needs of the oil processing industry. The present invention fulfils these needs and provides further related advantages.
SUMMARY OF THE INVENTION
The present invention relates to an improved design of filter for vegetable oil dry dewaxing and winterization in order to avoid turbid appearance of the refined oil during winter or cold climate conditions.
In accordance with the embodiment of the present invention, a horizontal retractable shell hermetic pressure leaf filter is provided with plurality of filter elements and multiple filtrate outlet headers. Each filter element consists of an internal support element and an external fabric based element. Each filter element is independently connected to an internal heating / cooling fluid inlet header, heating /cooling fluid outlet header and multiple filtrate outlet header by means of a mechanical design.
In accordance with the embodiment of the present invention, the internal support element provides adequate support to the external fabric based element and fluid flow area and it allows for heating and cooling by passage of steam / chilled water by means of a mechanical design.
In accordance with the embodiment of the present invention, the external fabric based element is sealed and fixed at the base of the internal support element by means of a mechanical design. The external fabric based elements are of unique shape such that a single piece of fabric based element covers one filter element which minimizes the sealing

and fixation points and so it minimizes the possibility of feed oil bypassing to the filtrate header.
The mechanical design of the present invention is simple, reliable and provides flexibility with durability.
In accordance with the embodiment of the present invention, the filter elements can be heated and cooled with the external shell of the pressure leaf filter in retracted position to allow visual inspection of the filter elements.
The filter design of the present invention ensures a "unique combination" of advantages. The filter is versatile for all oils and has complete hermetic operation on oil side. It does not require any filter aid. Waxes are recovered in solid / semisolid form which is economical for subsequent oil recovery by simple hydraulic pressing. The design ensures a uniform distribution of feed, blowing air over the filtration area and optimum oil loss in waxes / saturated tri-glycerides. The design has the facility of filtration & air blowing at higher pressures and washing of the filter elements after several filtration cycles at high temperature. In addition, waxes are recovered in semisolid form with limited heating of the filter elements and the process avoids manual scrapping. This helps in improving the life of filter elements and reduces manpower. Due to flexibility in changing one filter element easily without disturbing other elements, it ensures complete access for inspection and maintenance of filter elements during each wax discharge. Furthermore the operation of filtration and wax discharge is fully automatic and savings in manpower cost.
These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
BRIEF DESCRIPTION OF THE DRAWINGS
The detailed description is set forth with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure fn which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items.
FIG. 1 illustrates a general assembly of filter elements supported inside the pressure leaf filter and connected to the internal heating/cooling fluid inlet, outlet headers and multiple filtrate headers in accordance with the embodiment of the present invention.
FIG. 2 illustrates two sectional views AA and BB of the general assembly in figure 1, which shows the filter element without and with the external fabric element respectively. These sectional views AA and BB also illustrate the filter element fixed on the internal support element in accordance with the embodiment of the present invention.
Figure 2 also include section CC, a transverse section of filter element in accordance with the embodiment of the present invention.

REFERENCE NUMBERS:
Body 1
Support Frame 2 Filter Frames 3
Product Inlet 5
Heating Fluid Inlet / Outlet 6
Heating Fluid Inlet 6a.
Heating Fluid Outlet 6b
Product Outlet 7
Drain 8
Internal Support Element 9
Internal Support Element without external fabric element 9a
Internal Support Element with external fabric element 9b
Hermetic pressure leaf filter 10
DETAILED DESCRIPTION OF THE INVENTION:
The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skil[ in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The general operation of pressure leaf filters especially horizontal retractable shell pressure leaf filters may be found in various chemical engineering text books and hand books and will not be discussed here.
Accordingly, the embodiments of the present invention disclose a horizontal retractable shell hermetic pressure leaf filter 10 provided with plurality of filter elements. Each filter element consists of an internal support element 9 and an external fabric based element. The internal support element 9 has a mechanical design which combines adequate support to the external fabric based element with adequate fluid flow area. Each filter element is independently connected to an internal heating / cooling fluid inlet header, and heating /cooling fluid outlet header. The pressure leaf filter 10 has multiple filtrate outlet headers, which permit independent monitoring of the filtrate quality. Each filter element is independently connected to one of the multiple filtrate outlet headers by means of a mechanical design which combines mechanical flexibility with durability. The internal support element of the filter Element allows for heating and cooling by passage of steam / chilled water by means of a mechanical design which is simple and reliable. Each filter element is supported independently inside the shell of the pressure leaf filter by a mechanically reliable and simple design. The filter elements can be heated and cooled with the external shell of the pressure leaf filter 10 in retracted position to allow visual inspection of the filter elements.

The design of the internal support element 9 and further design of internal support element 9 which allows passage of heating / cooling fluid and further the design of the connections of the internal support elements 9 with the heating / cooling fluid inlet and outlet headers and multiple filtrate headers and further the design of the support of internal support element 9 within the shell of the pressure leaf filter 10 and further the design allowing passage of heating / cooling fluid in retracted position, as revealed in the FIG. 1 above, individually and in combination allow: (a) Removal of the wax / saturated tri-glycerides by heating and melting of the layer only adjacent to the external fabric based element, which permits slipping of the entire mass of wax / saturated tri-glycerides in semi-solid form, (b) Hermetic flow of filtrate to filtrate header, (c) Uniform distribution of feed and blowing air over the filtration area. This leads to a uniform formation of the layer of waxes / saturated triglycerides. This gives higher filterability in terms of mass of oil filtered per unit filtration area. This also gives higher loading in terms of mass of wax / saturated tri-glycerides per unit filtration area. This also ensures uniform air blowing and thus ensures optimum oil loss in waxes / saturated tri-glycerides. (d) The layer of waxes / saturated tri-glycerides formed on filtration area can be cooled to maintain its mechanical strength to prevent its crushing and ensuring better filterability. (e) Facility of filtration and air blowing at higher pressures that provides better filterability and lesser oil in waxes, (f) Facility of washing of the filter elements after several filtration cycles at high temperature to improve filterability. (g) Recovery of waxes in semisolid form without manually scrapping and with limited heating of the filter elements. This improves the life of filter elements and savings in manpower (h) Complete access for inspection and maintenance of filler elements, during each wax discharge. Flexibility to easily change one filter element without disturbing other elements, (i) Easy monitoring of filtered oil quality at the outlet of individual filtrate headers.
The external fabric based elements of the present invention are of unique shape such that a single piece of fabric based element covers one filter element which minimizes the sealing and fixation points and so it minimizes the possibility of feed oil bypassing to the filtrate header. The fabric based element is sealed and fixed at the base of the internal support element by a design which combines mechanical reliability with simplicity which minimizes possibility of feed oil bypassing to the filtrate header.
The design of the external fabric based element of each filter element, further the design of the shape of the external fabric based element and further the design of the fixation of the external fabric based element on the internal support element 9, as revealed in the FIG. 2 above, individually and in combination allow: (a) Operation on all oils which require separation of waxes / saturated tri-glycerides, to improve its clarity in winter season (b) Non requirement of use of filter aid and eliminates cost of filter aid and environmental problems of spent wax plus filter aid disposal (c) Wax separation uncontaminated with filter aid
Furthermore advantageous features of the present invention are, but not limited to, (a) waxes / saturated tri-glycerides recovered are free of filter aid and can be sold as a by-product. Waxes are recovered in solid / semisolid form which is economical for subsequent oil recovery by simple hydraulic pressing, (b) Completely hermetic operation on oil side, which is essential for food safety.
In accordance with one embodiment of the present invention, the filtration area and shape of each filter element, the heat transfer area within each filter element, number of filter elements in one pressure leaf filter shell, the size of the heatjng/cooling fluid inlet and outlet headers, sizes and numbers of multiple filtrate headers, sizes of the connections from

individual filter element to the headers will be variable to suit individual application of the filter.
In one embodiment of the present invention, the operation of filtration and wax discharge is automatic thus ensures easy monitoring of filtered oil quantity and in turn saves the man power cost.
The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

WE CLAIM:
1. An improved horizontal retractable shell hermetic pressure leaf filter design is
provided without the use of any filter aid for the separation of waxes and triglycerides
comprises:
a) a plurality of filter elements and
b) multiple filtrate outlet headers

2. The leaf filter design according to claim 1, wherein said each filter element consists of an Internal support element and an external fabric based element
3. The leaf filter design according to claim 1, wherein said each filter element is independently connected to the internal heating/cooling fluid inlet header and heating/cooling fluid outlet header
4. The filter element according to claim 3, is independently supported by a unique mechanical design which is simple and reliable
5. The filter element according to claim 1, is independently connected to one of the said multiple filtrate outlet headers by means of a mechanical design which combines mechanical flexibility with durability
6. The filter element according to claim 1, is supported independently inside the shell of the said pressure leaf filter by a mechanical design which combines mechanical reliability with simplicity
7. The filter element according to claim 2, wherein the said internal support element has a mechanical design which combines adequate support to the said external fabric based element with adequate fluid flow area
8. The filter element according to claim 2, wherein the said internal support element allows for heating and coofing by passage of steam/chilled water by means of a mechanical design which is simple and reliable
9. The leaf filter design according to claim 2, wherein the said external fabric based element is sealed and fixed at the base of the internal support element by a mechanically reliable and simple design
10. The external fabric based element according to claim 9, minimizes the possibility of feed oil bypassing to the filtrate header