FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents(Amendment)Rules, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION Apparatus for making powder from slurry
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR
Milind Gajanan Narkhede of S4 Division, Crompton Greaves Ltd, A3 MIDC Ambad 422010 Nashik, Maharashtra, India, Indian Nationals
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed

FIELD OF THE INVENTION
The present invention relates to an apparatus for making powder from a slurry. More specifically, the present invention relates to drying and crushing of slurries to form powders.
BACKGROUND OF THE INVENTION
Conventionally, many types of dryers are available for drying slurries/solutions to obtain powdered materials. One such type of dryer is an oven, in which a slurry is dried through static drying and then convened to powdered form. However, in an oven, the drying is done in bulk format and has less evaporation rate due to which the heating of the slurry may not be uniform, leaving moisture content in the final product. Further, the process of drying in an oven is time consuming and is prone to contamination. Moreover, the product obtained from oven drying has greater density as compared to the desired product and has to be ground/crushed in order to obtain desired powdered material.
Another type of dryer is a cylinder dryer, in which the products to be dried are spread over a surface of a hollow cylinder which is rotatable around an axis and is heated through various means. The product to be dried is in direct contact with the heat. However, the rotation of the cylinder may cause temperature variation, which may result in improper mixing of the product and non-uniform drying.
Yet another type of dryer is a spray dryer, in which a liquid or slurry is dried rapidly with a hot gas to obtain dry powder. However, spray dryer requires many

accessories to operate and hence expensive and difficult to maintain. Further, the behavior of the spray dryer is different in different types of liquid.
Yet another type of dryer is a vacuum dryer, in which liquid material is dried under reduced air pressure and low temperature. However, vacuum may cause the loss of fine powders and all the liquids may not be treated in the vacuum. Further, the vacuum dryer is difficult to control and maintain and is quite expensive. Hence, there is a need for an apparatus which facilitates uniform drying of the slurry and does not leave moisture content in the powder. The apparatus should facilitate drying in lesser time and in closed environment. Moreover, the final product obtained after drying of the slurry should be a finely ground powder.
OBJECTS OF THE INVENTION
An object of the invention is to provide an apparatus which facilitates uniform drying of the slurry and does not leave moisture content in the final dried product.
Another object of the invention is to provide an apparatus which produces a finely ground powder from a slurry
Yet another object of the invention is to provide an apparatus which takes significantly less time in making powder from slurry
Yet another object of the invention is to provide an apparatus in which no contamination takes place while drying of the slurry

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION
Various embodiments of the invention provide an apparatus for making powder from slurry. The apparatus comprises a cylindrical chamber enclosed by a cylindrical wall and two parallel side walls, a thermally insulated jacket wrapped around an outer surface of said cylindrical wall, the jacket being filed with a thermic fluid and comprising a plurality of heaters disposed therein for heating the thermic fluid for transmitting heat to an inner surface of the cylindrical wall, an inlet valve attached to a side wall of the cylindrical drum for feeding slurry thereinto; and a rotatable shaft disposed coaxially with a cylinder axis and including a plurality of spaced apart bladed paddles attached to and extending radially therefrom, each of the bladed paddles including a scraper disposed at an end thereof, wherein on rotation of the shaft, the bladed paddles are adapted to crush the slurry and throw it towards the inner surface for drying the slurry by the heat transmitted from the jacket, and the scrappers are adapted to scrap the powder from the inner surfaces and throw towards an outlet valve.
Preferably, the outlet valve is attached to a bottom end of the side wall for collecting powder from the cylindrical chamber.
Preferably, the apparatus comprises a cyclone and a blower attached to a side wall for suction of vapors from the cylindrical chamber.
Preferably, the apparatus comprises an exhaust attached to a top end of the cylindrical wall for exhaustion of vapors and gases from the cylindrical chamber.
Preferably, each of the bladed paddles comprises a blade disposed along its

length.
These and other aspects, features and advantages of the invention will be better understood with reference to the following detailed description, accompanying drawings and appended claims, in which,
Fig. 1 is a schematic cross-sectional front view of an apparatus for making powder from slurry in accordance with an embodiment of the present invention;
Fig.2 is a schematic cross-sectional side view of an apparatus for making powder from slurry in accordance with an embodiment of the present invention; and
Fig.3 is a schematic isometric view of a bladed paddle of Fig. 1 in accordance with an embodiment of the present invention.
Referring to figures 1-2, the apparatus 100 comprises a cylindrical chamber 1, a thermally insulated jacket 2 wrapped around a cylindrical surface of the cylindrical chamber 1, an inlet valve 3, an outlet valve 4, a rotatable shaft 5 disposed coaxially with a cylinder axis, and a motor arrangement 6 for rotating the shaft.
The cylindrical chamber 1 is mounted on a stand 11 and is enclosed by a cylindrical wall 12 and two parallel side walls 13 and 14 orthogonally disposed against the cylindrical wall 12. The cylindrical wall 12 has an outer surface 121 and an inner surface 122. In an exemplary embodiment of the present invention, the cylindrical chamber 1 is a drum shaped container having open-able side walls 13 and 14 re-sealable with o-rings and nut bolt type locking arrangement. An exhaust 123 is attached to a top end of the cylindrical wall 12 for exhaustion of vapors and any gases thereof.

A cyclone 71 is attached to a top end of the side wall 13 and a blower 72 is connected to the cyclone 71 for suction of vapors. The vapors inside the cylindrical chamber 1 get exhausted through the cyclone 71 due to the pull draft of the blower 72.
The inlet valve 3 is attached to a top end of the side wall 14 for feeding slurry into the cylindrical chamber 1. The outlet valve 4 is attached to a bottom end of the side wall 14 for collecting powder from the cylindrical chamber 1.
The jacket 2 is filed with a thermic fluid 21 and comprises a plurality of heaters 22 disposed therein for heating the thermic fluid 21 for transmitting heat to the inner surface 122 of the cylindrical wall 12. In order to prevent heat loss from the jacket 2, a layer 23 of an insulating material is wrapped around the jacket 2. Example of insulating material includes, but is not limited to, rockwool. Further, example of thermic fluid includes, but is not limited to, hytherm 500.
The thermic fluid 21 may be added to the jacket 2 through a fluid inlet valve 24 disposed at a top end of the jacket 2. Further, the thermic fluid 21 may be extracted out from the jacket 2 through a fluid outlet valve 25 disposed at a bottom end of the jacket 2.
A temperature sensor 26 is attached to the thermic fluid 21 for measuring its temperature at various time instants. The temperature sensor 26 may be connected to a

control panel of the apparatus 100, which includes temperature control, rpm control. safety devices and indicators.
The rotatable shaft 5 is disposed coaxially with the cylinder axis and extends between two ends, where one end is attached to a center 15 of the side wall 14 through a support bush 53 and another end is coupled through a flange coupling 54 to a gear box 55 disposed outside the chamber 1. The gear box 55 comprises a motor 56 for rotating the shaft 5. A portion of the shaft 5 protruding outside the chamber 1 is disposed inside a bearing housing arrangement 57 and is fixed to a center 16 of the side wall 13 through a mechanical seal 58.
The shaft 5 includes a plurality of spaced apart bladed paddles 61-68 attached to and extending radially therefrom. The bladed paddles 61-68 are arranged on the shaft 5 in such a manner that the paddles cover all the area of the cylindrical chamber 1 during rotation of the shaft 5. On rotation of the shaft 5, the bladed paddles 61-68 are adapted to crush the slurry and throw it towards the inner surface 122 for drying by the heat transmitted from the jacket 2. The material contained inside the chamber 1 is thrown towards the inner surface 122 due to the centrifugal force created by the rotation of the shaft 5. For the sake of illustration and clarity, the number of paddles shown on the shaft is eight, however, their number may vary based on the shape and size of the cylindrical chamber 1.

Each of the bladed paddles 61-68 comprises a scraper attached at an end for scrapping the powder from the inner surface 122 and throw it towards the outlet valve 4. For example, the bladed paddle 62 comprises a scrapper 621 at its top end for scrapping the powder from the inner surface 122 during rotation of the shaft 5.
With reference to Fig. 3, an exploded view of the bladed paddle 62 is illustrated. The bladed paddle 62 extends between two ends 621 and 622, where one end 622 is attached to the shaft 5 through a locking arrangement and another end 621 is a scraper. A blade 623 is disposed along the entire length of the paddle 62. In an exemplary embodiment of the present invention, the scrapper 621 is a Teflon scraper.
Operationally, the slurry 27 is fed into the cylindrical chamber 1 through the inlet valve 3. During the feeding of slurry, the outlet valve 4 is kept closed. It may be noted that the maximum slurry that can be fed to the chamber 1 is 60% of the total volume of the chamber 1. Once the slurry is fed, the heaters 22 are turned on to heat the thermic fluid 21 inside the jacket 2. When the temperature of the thermic fluid 21 reaches a preset temperature, the motor 56 is turned on with a pre-defined rpm. The pre-set temperature may be a temperature at which the evaporation of the slurry starts taking place.
When the motor 56 is turned on, the shaft 5 starts rotating and due to the rotation of the shaft 5, the paddles 61-68 rotate and start throwing the slurry on the inner surface 122. The shaft 5 keeps the slurry rolling inside the chamber 1 and reduces the formation

of cakes. During rotation, the slurry is crushed by the blades of the paddles 61-68. As a result, a thin film of slurry is evenly formed on the inner surface 122. The moisture content of the thin film of slurry is quickly evaporated due to the heat transmitted from the thermic fluid 21 and a thin layer of powder is formed thereof. The scrappers at the end of the blades scrape the powder from the inner surface 122 and throw it towards the outlet valve 4. The powder is collected from the outlet valve 4 thereof.
Due to formation of the thin film of slurry on the internal surface of the cylinder, the drying time is significantly less. Further, due to the presence of blades, a finely ground powder is obtained from the slurry. The apparatus not only improves the quality of drying but also significantly reduces the cycle time for drying. The final product has almost negligible moisture content and is uncontaminated due to the closed environment of the chamber 1.
Although the invention has been described with reference to a specific embodiment, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiment, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore contemplated that such modifications can be made without departing from the scope of the invention as defined in the appended claims.

We claim: 1. An apparatus for making powder from a slurry comprising:
a cylindrical chamber enclosed by a cylindrical wall and two parallel side walls;
a thermally insulated jacket wrapped around an outer surface of said cylindrical wall, the jacket being filed with a thermic fluid and comprising a plurality of heaters disposed therein for heating the thermic fluid for transmitting heat to an inner surface of the cylindrical wall:
an inlet valve attached to a side wall of the cylindrical drum for feeding slurry thereinto; and
a rotatable shaft disposed coaxially with a cylinder axis and including a plurality of spaced apart bladed paddles attached to and extending radially therefrom, each of the bladed paddles including a scraper disposed at an end thereof, wherein on rotation of the shaft, the bladed paddles are adapted to crush the slurry and throw it towards the inner surface for drying by the heat transmitted from the jacket, and the scrappers are adapted to scrap the powder from the inner surfaces and throw towards an outlet valve.
2. The apparatus as claimed in claim 1, wherein the outlet valve is attached to a bottom end of the side wall for collecting powder from the cylindrical chamber.
3. The apparatus as claimed in claim 1, which comprises a cyclone and a blower attached to a side wall for suction of vapors from the cylindrical chamber.
4. The apparatus as claimed in claim 1, which comprises an exhaust attached to a top end of the cylindrical wall for exhaustion of vapors and gases from the cylindrical

chamber.
5. The apparatus as claimed in claim 1, wherein each of the bladed paddles comprises a blade disposed along its length.