-2-
FIELD OF INVENTION
The present invention relates to a single jacketed scrapped surface multipurpose conical vessel to perform kneading, mixing, heating and cooling operations during processing of dairy and food products. More particularly, the invention relates to a single jacketed scrapped surface multipurpose device for processing of dairy and food products.
BACKGROUND OF THE INVENTION
Use of jacketed vessels is a common practice in food industries. Batch-wise kneading, heating, cooking, and concentration are some of the operations carried out in them.
Uniform mixing of high viscous products is one of the major constraints in food industry. In these products, mixing and kneading elements do not generate flow currents. Sometimes it becomes necessary to take special steps to eliminate any stagnant zones inside the mixer in order to avoid the material riding around on mixing blades without being reincorporated into the mixture.
Another problem that persists in food industry is the elaborate arrangement made to the vessel for discharging the mixed, cooked, or concentrated material out of the vessel. In all the existing designs, the whole vessel is tilted for pouring the material out of the vessel, but the paste like products cannot be completely emptied out, as some amount would remain sticking to the blades. The mixing blades, in these designs, cannot be easily removed out of the vessel for manual cleaning.
-3-
During manufacture of traditional Indian dairy products like rasogolla, sandesh, peda, and gulabjaman, kneading of chhana or khoa and subsequent mixing with sugar are the important unit operations. For example in preparation of sandesh, chhana, a heat and acid coagulated product of milk, is kneaded manually. Operations such as mixing of kneaded chhana with sugar and cooking of chhana sugar mixture is carried out in an open pan. During the operation, the mixture is continuously scraped manually by using a wooden ladle until the product attains the desired consistency. The process is labor intensive, unhygienic and lacks quality control in the finished product. During the process of cooking, the mixture gets deposited on the surface of the pan thereby lowering the thermal efficiency of the equipment.
Scaling on hot surface is a major problem during heating and concentration of non-foaming liquids and pastes in a jacketed vessel. In most cases, the vessel wall offers negligible thermal resistance to the heating or cooling medium, but a thin film of paste adhering the vessel wall offers a considerable amount of resistance. This reduces heat transfer from heating medium to the liquids or paste. In order to minimize the thermal resistance, it is required to fix a scraper blade very close to the vessel wall and the shape of the blade should be such that a flow current of the liquid or paste is established around the blade.
Uhl et al., (1967) reported the use of banbury and sigma mixers for mixing of highly viscous products. Sigma mixer has a good mixing action, but the mixer is tilted for discharge of the processed product. Due to the typical geometry, cleaning of the sigma mixer blades is not convenient when sticky materials are processed.
-4-
Mc Cabe et al., (1993) suggested use of planetary or pony mixer for mixing of viscous material in food processing. Most of the designs include provision to remove the mixing blades by lifting them out of the vessel.
Indian Patent 165440 described a vat, tapered downwardly with a cone angle of 60°. The vat has a steam jacket, partitioned into four segments to provide control over heat transfer surface area. There is a scraper assembly having three arms. The scraper blades are placed in a manner to facilitate scraping from entire heating surface. Discharge of the product is carried out through a propeller located at the bottom end of the vat.
US Patent Application 20010024400 describes a circular vessel, which narrows in a downward direction. The power transmission is inserted from the top. Mixing elements consist of a number of radial elements fixed on the mixing shaft and carry paddles at their distal ends, adjacent the sidewall of the vessel. Mixing takes place due to the. spiral movement of the material along the wall and top lid of the vessel. Due to the rotation of paddles and the conical shape of the vessel, the contents move spirally in upward direction. The layers of material closest the wall end get less spiral and more upward movement, so that the intermediate layer is subjected to strong shearing forces that promote mixing. Discharge takes place by gravity through a ball segment valve or a slide valve mounted at the lower end of the mixing vessel.
US Patent 4,123,174 relates a mixer with a downwardly tapered conical wall. The mixer doesn't bear any heating or cooling jacket for thermal treatment of product
-5-
the mixer uses a ring shaped screw or worm as the mixing element, wherein the mixing element rotates about its own axis and at the same time it rotates about a conical path along the inside wall of the vessel. Discharge of product in the said patent is carried out through a product outlet tube extending straight vertically downward. The discharge takes place due to the gravitational force on the products and the conveying action of the screw element.
US Patent 6,793,386 describes a twin-screw extruder as the kneading device. The kneading elements are similar to that of a twin-screw extruder, having one of the screws as that of sigma blade. Screw profiles of the kneading elements are very typical and difficult in fabrication.
US Patent 6,767,123 relates a twin-screw extruder having two similar kneading screws. The screws are attached with a number of mixing elements.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose a single jacketed scrapped surface multipurpose device which ensures uniform mixing of high viscous products.
Another object of the invention to propose a single jacketed scrapped surface multipurpose device which eliminates a complex arrangement for discharging the end-product out of the device.
Another object of the invention is to propose a single jacketed scrapped surface multipurpose device, for having total visibility of material during kneading.
A still another object of the invention to propose a single jacketed scrapped surface multipurpose device which produces hygienic products and less labor-intensive.
-6-
Yet another object of the invention to propose a single jacketed scrapped surface multipurpose device which eliminates the need of removal of the mixing blades for cleaning of the vessel.
A further object of the invention to propose a single jacketed scrapped surface multipurpose device which consumes less time, ensures high heat transfer, and absorbs less electrical energy.
SUMMARY OF THE INVENTION
The present invention discloses a circular vessel where the bottom of the vessel is tapered in an upward direction. Power transmission shaft to the rotating blade of the invention is inserted from the bottom of the vessel. Mixing elements of the vessel includes two symmetrically placed rotating blades, inclined at an angle with respect to the bottom and sidewall of the vessel. This allows viscous material to slip against the rotating blades. Thus the process avoids any material riding around on mixing blades without being reincorporating into the mixture. Kneading and mixing of the material inside the vessel takes place due to shearing and scrapping of the material by the two rotating blades. Out of two blades, placed symmetrically inside the vessel, one of the blades is fitted closely to wall of the vessel whereas the other maintains a certain amount of clearance from it. The later permits shearing and stretching of high viscous materials that is required to reduce the size of particles present in the mixture, as this is the desired characteristics during mixing and kneading of high viscous material. The top lid of the vessel is completely detachable and the vessel can be used for pressure or vacuum application. Discharge of products takes place through
-7-
the outlet located at the bottom wall of the vessel. The discharge is aided by the centrifugal force created on the material due to rotational speed of the scraper blades. Since the rotating blades are attached with Teflon plates, high viscous material doesn't stick to the surface of the blade. The Teflon plates can be adjusted to vary the clearance between inner surface of the wall and the edge of the rotating blade, if required.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig.l- Shows a single jacketed scrapped surface multipurpose device of the present invention in assembled condition.
Fig.2- Shows a detailed drawing of the conical vessel of the device of Fig. 1. Fig.3- Shows a 'kneading and mixing element' of the device of Fig.l Fig.4- Shows a discharge valve provided to the conical vessel of Fig.2
Fig.5- Shows the details of the power transmission means operating the device of Fig. 1.
DETAIL DESCRIPTION OF PREFERRED EMBODIMENT OF THE INVENTION
The present invention relates to a single jacketed scrapped surface conical vessel, which performs mixing, heating, concentration, evaporation and cooking (both at atmospheric and sub-atmospheric pressure) operations involved in manufacture of dairy and food products.
-8-
Bottom surface of the vessel is conical. Conical bottom facilitates the vessel to remain dry during its non-use. The angle between the bottom of the vessel and the horizontal is 15°. The vessel is jacketed and provision exists for the heating or cooling medium (1) to be introduced into the jacket (2). It has provision to connect steam trap (5) and vent off valve at its jacketed portion.
Two teflon coated kneading and mixing blades (3) are placed symmetrically inside the vessel. The blades are rotated by a centrally located vertical stainless steel shaft (23). The two blades (24 and 25) are placed at an angle with respect to the conical and vertical surface of the vessel to avoid riding of viscous materials around on the kneading and mixing blades without reincorporating into the mixture. Effective vertical (24) and horizontal (25) length of the scraper blades are 260 mm and 180 mm respectively. Of these two blades, one blade fits close to the inner walls of the vessel whereas the other maintains a certain amount of clearance from these walls. The blade that maintains certain clearance, allows the material to pass through the clearance while other blade scrapes the material that sticks to the wall surface. As the material passes through the clearance it gets stretched and sheared forming a thin layer on the inner wall of the vessel as that obtained in a thin film evaporator. Slots (26) are provided on the blades to adjust the desired clearance between the vessel surface and the edge of the scraper blades. Effective width of the scraper blades is 50 mm. Shaft (30) that transmits power to the kneading and mixing elements is introduced from the bottom of the vessel and is connected to a 1:20 speed reduction unit (8).
The vessel is closed with a top cover and is provided with a pressure or vacuum gauge (17), pressure release valve (18), vent off ball valve (19), sterile air or vacuum line inlet (15), and light and sight glasses (16 and 20). Provision is made for
-9-
inserting thermocouple and measuring the temperature of product when the vessel is operated under vacuum or pressure. The top cover is tightened to the vessel through food grade gasket (13). The rotor is coupled to the power transmission shaft (23) through gland packing (33).
An outlet (11) is provided at the bottom of the vessel. Discharge of product takes place due to the centrifugal action created on the product due to rotational speed of the kneading and mixing blades. The discharge valve is provided with two closers (28 and 29). One of the two closures is used for the discharge of liquid and the other for high viscosity dough and pastes.
Example 1:
Use of the vessel as chhana kneader for preparation of rasogolla
1. Adjusting the Teflon plates (4) so that one blade (24) fits closely to the inner
walls of the vessel (22) and another (25) maintains certain clearance from
these walls (30a).
2. Flushing the vessel (22) with cold water and then with hot water.
3. Closing the discharge valve (18).
4. Placing chhana into the vessel (22).
5. Switching on the scraper drive and run the drive unit (8,10).
6. Opening the discharge valve (18) and collecting the kneaded chhana after the
product gets the desired consistency.
7. Switching off the scraper drive (8,10)
8. Repeating the process with fresh batch.
-10-
Test results for kneading of chhana for preparation of rasogolla
Amount of chhana per batch : 6 kg
(Capacity= 13.33% of total hold up volume)
Moisture content of chhana : 0.60 kg water per kg of chhana
Rotational speed of scraper blades : 100 rpm
Blade clearance from the scraped surface : 4 mm
Amount of kneaded chhana : 5.95 kg
Total process time : 6 min
Capacity of the vessel : 45 kg per hour
Example 2:
Procedure for kneading, mixing and cooking of chhana-sugar mixture for preparation of sandesh
1. Adjusting the Teflon coatings (4) so that one of the two blades (24) fits
closely to the inner walls (30a) of the vessel (22) and another (25) maintains
certain clearance from these walls .
2. Flushing the vessel (22) with cold water and then with hot water.
3. Closing the discharge valve (18).
4. Placing chhana into the vessel (22).
5. Switching on the scraper drive and run the drive (8,10).
6. Adding appropriate amount of ground sugar after the kneaded chhana mass
attains the desired texture.
-11-
7. Switching on the steam valve (5) and allow the steam to enter the jacket (2)
of the vessel (22).
8. Controlling rotational speed of the scraper blades (24,25) during mixing and
subsequent cooking so that the mixture does not flash out of the vessel (22).
9. Switching off the steam valve (5) when the mixture tries to leave the scraped
surface.
10. Opening the discharge valve (18) and collecting cooked chhana-sugar
mixture in trays.
11. Switching off the scraper drive (8,10).
12. Cooling the vessel (22) by circulating cold water inside the jacket (2).
13. Repeating the process with a fresh batch.
Test results for kneading, mixing and cooking of chhana-sugar mixture for preparation of sandesh
Amount of chhana per batch : 6 kg
(Capacity= 13.33% of total hold up volume)
Moisture content of chhana : 0.60 kg water per kg of chhana
Amount of ground sugar per batch : 2.10 kg
Maximum rotational speed of scraper blades : 100 rpm
Total batch time : 18 min
Blade clearance from the scraped surface : 4 mm
Saturated steam pressure : 1 kg.cm"2 gauge
Amount of cooked chhana-sugar mixture :5.16 kg
Moisture content of cooked chhana-sugar " : 0.15 kg water per kg of
mixture cooked chhana-sugar mixture
Capacity of the vessel : 15 kg per hour
-12-
Example 3: Procedure for preparation of kheer under pressure
1. Washing rice in cold water in a container and drain out the wash water.
2. Soaking the rice in cold water.
3. Adjusting the Teflon coated blades (4) so that there will be no clearance
between the blade edge and the vessel wall.
4. Flushing the vessel (22) with cold water and then with hot water.
5. Closing the discharge valve (18).
6. Putting milk, sweetened condensed milk and the rice in appropriate ratio into
the vessel (22).
7. Covering the vessel (22) with the top cover (17,20,21) and tighten it
properly.
8. Switching on the steam valve (5) and allow the steam to enter the jacket (2).
9. Switching on the scraper drive (8,10) and run the drive at slow speed.
10. Opening the top cover (17,20,21) and adding appropriate amount of ground
sugar, chopped cashew nuts, raisins and crushed cardamom seeds in
appropriate amount after the mixture attains the desired texture and
consistency.
11. Switching off the steam valve (5) and opening the discharge valve (14) and
collecting the processed kheer in container.
12. Switching off the scraper drive (8,10).
13. Repeating the process with fresh batch. .
-13-
Test results for preparation of kheer under pressure
Weight of milk : 2.5 kg
(TS:14%, SNF:11.5%,Fat:3.5%)
Weight of broken basumati rice : 0.5 kg
Weight of sweetened condensed milk : 1.2 kg
Weight of chopped cashew nuts : 0.1 kg
Weight of raisins : 0.1 kg
Weight of cardamom : 0.01 kg
Weight of sugar : 0.5 kg
Weight of water added : 2.75 kg
Total weight of mix : 7.66 kg
Rotational speed of scraper blades : 7 rpm
Steam pressure inside the vessel : 1 kg.cm"2 gauge
Total batch time : 10 min
Amount of kheer produced : 7.43 kg
Total solid content of kheer : 37.6 kg dry matter per kg of
kheer
Production capacity of the vessel : 40 kg per hour
Example 4:
Procedure for concentration of tomato pulp under vacuum
1. Adjusting the Teflon coatings (4) so that one blade (24) fits close wall (30a)of
the vessel (22) and another (25) maintains certain clearance from the
wall.
-14-
2. Flush the vessel (22) with cold water and then with hot water.
3. Close the discharge valve (18).
4. Connecting a vacuum line at the inlet for sterile air (15) and replacing the
pressure gauge (17) by a vacuum gauge.
5. Placing tomato pulp into the vessel (22).
6. Closing the top cover of the vessel (22) and tighten it properly.
7. Switching on the scraper drive (17,20,21) and run the drive at slow speed.
8. Switching on the steam valve (5) and allow the steam to enter the jacket (8).
9. Controlling the steam pressure so that the temperature of the product remains at
70±2°C.
10. Closing the steam valve (5) when the product attains the consistency of tomato
sauce.
ll.Stoping the drive unit (8,10) and opening the discharge valve (14) and, collecting the concentrated pulp in a container.
Test results for concentration of tomato pulp under vacuum

Weight of tomato pulp 6.0 kg
TS of the pulp 4.6%
Clearance of one blade from the
vessel wall 5 mm
Rotational speed of scraper blades 58 rpm
Vacuum level 680 mm Hg
Temperature of the product 70+2°C
Total batch time 2hrs
Weight of concentrated pulp 3.5 kg
Total solid content of concentrated pulp 31.2%
Production capacity of the vessel 1 kg per hour
15-
KEY TO ACCOMPANYING DRAWINGS
1. Heating or cooling medium inlet
2. Hot water, cold water or steam
jacket
3. Kneading and mixing blade
4. Teflon plate
5. Steam trap
6. Condensed water outlet
7. Supporting frame
8. Speed reduction unit
9. Supporting base
10. AC motor
11. Outlet
12. Heating or cooling medium
outlet
13. Gasket
14. Handle
15. Sterile air or vacuum line inlet
16. Light glass
17. Pressure or vacuum gauge
18. Pressure release valve
19. Vent off ball valve
20. Sight glass
21. Pressure gauge
22. Main vessel
23. Kneading and mixing elements
mounting shaft

24. Vertical blade
25. Inclined blade
26. Slots
27. Gasket
28. Closure for discharge of liquid
product
29. Closure for discharge of high
viscous product
30. Coupling
31. Power transmission shaft
32. Coupling
33.Glandpacking
-16-
WE CLAIM:
1. A single jacketed scrapped surface multipurpose device for processing of
high viscous products, in particular dairy and food products, comprising:
- a jacket for heating or cooling an intended product via a medium,
the jacket having an inlet at an upper section and an outlet for
the heating or cooling medium;
- a conical vessel (2) disposed inside the jacket;
- atleast two scraper blades placed inside the vessel being rotatable
by a centrally located vertical snaft;
- a top cover for closing the vessel;
- a discharge valve provided at the bottom of the vessel having two
different closure members and
- a power transmission means supplying rotational power to the
vertical shaft for rotating the atleast two scraper blades , wherein
the atleast two scraper blades are arranged at an angle of about
45° to the side and the bottom surface of the vessel , and wherein
a first of the atleast two scraper blades is fitted close to the vessel
wall , the second blade being disposed maintaining a clearance
from the vessel wall.
2. The device as claimed in claim 1, wherein the scraper blades are coated
with Teflon plates and disposed inside the vessel.
3. .The device as claimed in claim 1 or 2, wherein a plurality of slots are
provided on the teflon plates to vary the clearance between the vessel wall and the edge of the blades.
-17-
4. The device as claimed in claim 1, wherein the top cover is provided with a
pressure or vacuum gauge , a pressure release valve , a ball valve , an
inlet, and one each of a light and sight glass .
5. The device as claimed in claim 1, wherein the power transmission means
comprises an induction motor , a speed reduction unit , and a power
transmission shaft.
6. The device as claimed in claim 1, wherein the effective vertical and
horizontal length of the scraper blades are respectively 60% and 40% of
the inside diameter of the vessel , and wherein the effective width of the
scraper blades is 12% of the inside diameter of the vessel.
7. The device as claimed in any of the preceding claims, wherein the inside
diameter and the height of the vessel bears a relationship of 3:2, and
wherein the spacing of the jacket is 2.5% of the inside diameter of the
vessel .
8. A single jacketed scrapped surface multipurpose device for processing of
high viscous products, in particular dairy and food products as
substantially described herein and illustrated with reference to the
accompanying drawings.

A single jacketed scrapped surface multipurpose device for processing of high viscous products, in particular dairy and food products, comprising of a jacket for heating or cooling an intended product via a medium, the jacket having an inlet at an upper section and an outlet for the heating or cooling medium; - a conical vessel (2) disposed inside the jacket; - atleast two scraper blades placed inside the vessel being rotatable by a centrally located vertical snaft; - a top cover for closing the vessel; - a discharge valve provided at the bottom of the vessel having two different closure members and - a power transmission means supplying rotational power to the vertical shaft for rotating the atleast two scraper blades , wherein the atleast two scraper blades are arranged at an angle of about 45° to the side and the bottom surface of the vessel , and wherein a first of the atleast two scraper blades is fitted close to the vessel wall , the second blade being disposed maintaining a clearance from the vessel wall.