AU5598699A - Soliquid - Google Patents

Description

Soliquid Field of invention The present invention relates to a Soliquid assembly, and more particularly to a solids liquid mixing device which removes air at the same time from the product. This can be used for mixing two liquids too.

Background Many processes in the food, pharmaceuticals and chemical industry call for mixing of solids into liquids to prepare a solution or suspension of a precise composition.

Quite often this is done discontinuously, in many steps. First a tank is filled with a known quantity of liquid. Next the required amount of solids are dumped in the tank. Thirdly the tank is vigorously mixed to achieve uniform distribution and homogenious solution. Sometimes a pump is used to circulate the product and achieve mixing. Now the product is ready for use.

The above method has a lot of disadvantages some of which are listed below 25 It is a batch process which normally has to integrate with continuous process thus necessitating two independent mixing S"units.

Vigorous mixing can lead to aeration of the product which may not be desirable.

Sometimes an additional solvent may be required to prepare a solution eg. Addition of lactose in milk is traditionally achieved by making a lactose solution in water which needs to be evaporated ultimately costing energy.

There are some proprietary equipment available in the market for industrial application which rely on dosing the solids in the eye of the vertically mounted impeller and accurately controlling the feed in and feed out of liquid. These equipments are fairly complex and rely on extensive instrumentation and controls. This leads to aeration of the product.

Other available equipments rely on vigorous agitation to achieve mixing. These introduce air into the product and have a very high energy consumption. These can damage the shear sensitive products.

The mixer in patent no AU-B-30482/95 had used the same principle but does not provide for air removal and in line use. This was a batch process equipment.

It is the object of the present invention to provide a mean of mixing solids into liquids as a continuous process with very low energy cost and removing air at the same time.

Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects S and the advantages of the invention may be realised and obtained by means of the instrumentation and combinations particularly pointed out in the description and their equivalents.

Summary of the invention 25 To achieve the forgoing objects, and in accordance with the purposes of the invention as embodied and broadly described herein, there is provided an apparatus and process called Soliquid to achieve an in line mixing of solids and liquids. The apparatus consists of a solids (or liquid) dosing equipment and an appropriate method of generating a centrifugal force in liquid. The centrifugal force thus generated is limited in magnitude so as to avoid the air core in the eye of vortex from reaching the liquid outlet port. The solids (or liquids) are dropped on the surface of the liquid. The solids that have a density higher than the liquid are subjected to a centrifugal force according to Stokes law and move towards the wall of the vessel. The gases or air which are generally lighter than the liquid tend to move towards the centre again due to the centrifugal forces and the Stokes Principle. The rotating liquid creates an interface with the solids surface and that facilitates suspension or solution of the solid. This mixer has the following advantages: It is an in line continuous process thus does not need holding tanks and vessels.

The mixing action is very gentle and the centrifugal force used for mixing also removes the air,ths it does not vigorously mix.

It does not aerate the product .hic ma n b al It does not need an additional solvent like the batch processes do.

Other objects and advantages are a) The energy consumption is extremely low for this process.

b) The equipment is washed in line and does not need separate washing.

c) The equipment has a small footprint and needs very little space 15 compared to batch mixing which needs tanks and pumps.

d) The control system to integrate this concept in the automatic plant are very simple.

Brief description of the drawing The accompanying drawings, which are incorporated in and constitute a part of the specifications, illustrate a preferred embodiment of the invention and together with the general description given above and the 25 detailed description of the preferred embodiment and the description of the actual tried unit given below, serve to explain the principles of the invention.

Fig.1. is a schematic diagram of a Soliquid the solids and liquids mixing apparatus and process.

Description of the Preferred Embodiment Reference will now be made in detail to the present preferred embodiments of the invention as illustrated in the accompanying drawings.

73 A preferred embodiment of the Soliquid solids and liquids mixing apparatus and process according to the teachings of the present invention is shown in fig.l. This is a schematic drawing of my invention.

According to the present invention, the components used in the preferred embodiment are Auger Feeder 28 Bag filter 27 A mixing vessel 24 A control valve 22 for the liquid line to maintain level in the mixing vessel 24 A level transmitter 23 A mixing pump A product outlet line 26.

15 21 is a liquid incoming line.

30 is a tangential entry to a mixing vessel 24 29 is a outlet port of mixing vessel 24 31 shows a typical shape of the vortex formed due to liquid S. entering the mixing vessel 24 through tangential entry The Soliquid comprises of 21 a liquid incoming line which has a control valve 22. A tangential entry 30 connects a control valve 22 to a mixing vessel 24. 31 is a typical shape of the vortex formed in to a mixing vessel 24. A Auger Feeder 28 is connected to a mixing vessel 24. A Bag filter 27 25 is connected to the top of the mixing vessel 24. A level transmitter 23 is mounted on a mixing vessel 24 and connected to a control valve 22. A mixing vessel 24 has a outlet port 29 which is connected to a mixing pump 25 which in turn is connected to a product outlet line 26. The Auger Feeder 28 is typically a commercially available unit. The mixing pump 25 is a commercially available pump of required flow rate and head. The mixing vessel 24 is typically a 150 mm diameter and 1000 mm long cylindrical vessel with a conical base.

From the description above, a number of advantages of my Soliquid mixer become evident: a) It is an in line continuous process thus does not need holding tanks and vessels.

b) The mixing action is very gentle and the centrifugal force used for mixing also removes the air thus it does not vigorously mix. It does not aerate the product which may not be desirable.

c) It does not need an additional solvent like the batch processes do.

d) The energy consumption is extremely low for this process.

e) The equipment can be washed in line and does not need separate washing.

f) The control system to integrate this concept in the automatic plant are very simple.

The operation of Soliquid as an in line equipment is identical to any in line equipment for liquid processing. It continuously receives a stream of liquid, processes the incoming liquid in real time and discharged the liquid continuously after processing.

21 is a liquid incoming line which supplies liquid through the control S valve 22. Control valve 22 controls the level in mixing vessel 24. Liquid 2 enters mixing vessel 24 via a tangential entry 30. The tangential entry velocity thus developed is used to create a rotating motion and create a centrifugal force. This centrifugal force is such controlled that a vortex is formed. 31 shows a typical shape of the vortex. The vortex is limited in depth such that it does not reach outlet port 29 of mixing vessel.. The Scontrol valve 22 maintains the level in mixing vessel 24 by using the "I 25 signal from the level transmitter 23.

The solids are dosed at a controlled rate by Auger Feeder 28. The dust thus generated is trapped in by the bag filter 27 while the excess air is allowed to escape. Solids make a contact with the rotating liquid in mixing vessel 24. The centrifugal force spins the particulate solids towards the inner wall of mixing vessel 24. All particulate solids have interstitial air. This air which is lighter moves towards the middle of mixing vessel 24 and discharges in the vortex cone 31 as shown in fig.1.

The solids mix with liquid move to 29 which is a outlet port of mixing vessel 24 and are drawn to the pump 25. The pump 25 acts as a mixer, size reduction equipment and a pressure generator.

The mix coming out at product outlet line 26 is a homogenous mix of the solids in the liquid.

The size of the mixing vessel 24 and the flow rate of liquid through Soliquid is determined by the characteristic of the liquid and solid.

While I believe that the physics involved can be explained by a) Stoke's Law of Centrifugal Forces b) Principle of Vortex formation in rotating liquids c) Principle of Cyclone operation I do not wish to be bound by these.

The configuration of the Soliquid as per the present invention is not limited to the preferred embodiments disclosed.

Details of the Actual Trial Unit 15 The trial unit was built as per the fig.1 schematic diagram.

This was used to add lactose powder in the milk for protein standardisation. The milk flow rate was 6,000 litres per hour and the lactose powder to be added was 300 kg per hour.

Pump 30 was rated at 6,000 litres p/h feeding to the evaporator. Line 21 (size 40 mm) feeds to the mixing vessel 24.

Therefore 300kg of lactose was added to 6,000 litres of milk per hour.

25 Pump 24 was a centrifugal pump with 1.0 KW motor running at 1350rpm.

The alternate technology required two 30,000 litres tank with necessary mixing, pasteurising equipment and with provision for cleaning using hot detergents. The product was still prone to bacterial contamination.

Since the solution was made using water, this water had to be evaporated which increased energy usage as well.

In another trial the unit was used for mixing of starch into water. This was equally successful.

In another trial it was used for mixing Skim Milk Powder into the water.

This is a very difficult application and always tends to generate foam. In the trial with Soliquid, no foam was formed at all.

In another trial it was used for mixing lactose in the skim milk concentrate( Viscosity equal to 5Ocps) and the soliquid perform as per expectation.

Thus the reader will see that Soliquid provides a) in line continuous process thus does not need holding tanks and vessels.

b) A gentle mixing action and removal of air. It does not aerate the product which would have played havoc with the vacuum control of Multi effect Evaporator.

c) It does not need an additional solvent like the batch processes do.

d) The equipment is washed in line and does not need separate washing.

e) The equipment has a small footprint and needs very little space 15 compared to batch mixing which needs tanks and pumps.

f) The control system to integrate this concept in the automatic plant are very simple.

g) It can be used with a large variety of products.

While my above description contains many specifities, these should not be construed as limitations on the scope of the invention, but rather as an exemplification of one preferred embodiment thereof. Many other variations are possible. For example, if the flow rate required is lower than what is required to form a proper vortex, a part of the mixed liquid be recirculated through the liquid inlet line.

In another example if the flow rate in the line is too large, only a part of the liquid stream can be passed through Soliquid.

Alternative means of level control can be used too. As an example, if it is connected to an existing balance tank, the height of Soliquid can be such designed that the level control is not required at all.

Alternative means to tangential entry can be used for generating a rotating liquid. This could be a mechanical means like a rotating mechanical device which induces a rotation in the liquid.

The Soliquid can be used for mixing liquids as well. In place of dropping solids particulate matter, it could be a different liquid.

Additional advantages and modifications will readily occur to those skilled in the art. The invention in its broader aspects is, therefore, not limited to the specific details, representative apparatus and illustrative examples shown and described. Accordingly, departures from the spirit or scope of the invention can be made.

*9 9

Claims (1)

1. An apparatus for mixing liquids and particulate solids comprising a vessel with inlet and outlet for said liquid, said liquid said inlet for introducing said liquid into the said vessel, a means to create a rotating said liquid in a manner that the air core in the middle of the said rotating said liquid does not reach the said outlet of the said vessel, said particulate solids inlet means for introducing a stream of said particulate solids into the said rotating liquid, and removing the mixed said liquid and said particulate solids from the said outlet of the said vessel. 20 RAKESH KUMAR AGGARWAL 20 OCTOBER 1999 Name of Applicant Signature Date S S