GB1569269A - Treatment of emulsions - Google Patents

Description

(54) TREATMENT OF EMULSIONS (71) We, I.W.S. NOMINEE COM PANY LIMITED, a British Company of Wool House, Carlton Gardens, London, S.W.1., do hereby declare the invention, for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a method and apparatus for the thermal cracking of emul sions of immiscible liquids, more particularly emulsions of water and wool grease.

In the scouring of raw wool to remove contaminants, which may be present in amounts of up to 40% by weight of the total, it is usual to subject the wool to the action of hot solutions of soaps or detergents. The effluent from such scouring contains a great many substances, such as excess detergent, woo grease, dirt and vegetable matter.

Before the effluent can be discharged it must be treated to remove contaminants and to recover wool grease from which valuable lanolin can be extracted.

A standard form of treatment has the following steps. The effluent is heated to 7O-8OC and passed to a primary centrifuge where three phases are separated: heavy solids and grit, an aqueous phase, and an emulsion or 'cream' of wool grease and water. The cream is fed to a second centrifuge which cracks the emulsion into wool grease and an aqueous phase. The second centrifuge, in particular, is an expensive piece of equipment and its operation is labour-intensive in that it must be cleaned frequently of deposits of grease and light solids.

The invention seeks to provide a simple and economic method and means of extracting soluble wool grease from scouring effluent.

According to the present invention, there is provided a method of thermally cracking an emulsion of immiscible liquids differing in density which comprises passing the emulsion into a heated zone maintained substantially free of turbulence and drawing off the separated components from different regions of the zone, the zone being maintained free of turbulence by heating it in such a manner that a thermal gradient exists wherein the top is hotter than the bottom.

Such heating ensures that convection currents are reduced or eliminated.

The invention also provides a thermal emulsion-cracking apparatus which comprises a vessel having an inlet for the emulsion, respective outlets for the emulsion components at different levels, and heating means capable of maintaining a thermal gradient in the vessel such that the top of the vessel is hotter than the bottom.

The heating means may conveniently comprise two or more steam pipes each controlled by thermocouples. Preferably the outlets are at the top and bottom of the vessel, and the inlet at or near the middle.

Thus, in the operation of the invention in the separating of wool grease, the cream from the primary centrifuge is fed to the apparatus of the invention and enters at the middle of the vessel. Ideally the cream is preheated to the temperature of the contents of the vessel at or about the inlet pipe.

The action of the heat (preferably in the range 75" to llO"C) cracks the emulsion and an aqueous phase separates downwards while the wool grease moves to the top, at both of which places there are outlets to remove the respective components. Thus the apparatus of the invention can be operated continuously to separate wool grease from the primary centrifuge cream, and so replace the second centrifuge.

While the invention is particularly useful for the separation of wool grease/water emulsions, it may be used to separate other emulsion systems susceptible to thermal cracking, where the density of the two components differs.

The invention will be described in greater detail, by way of example, with reference to the drawing accompanying the Provisional Specification the sole figure of which is a diagrammatic cross sectional view of one form of apparatus for separating an emulsion, e.g. of wool grease, according to the invention.

The emulsion cracking apparatus shown in the drawing comprises a vessel 10 having an emulsion inlet pipe 12 extending into the interior of the vessel at a level about half the height of the vessel and provided with a series of perforations 14. An outlet 16 for the aqueous phase is located at the lower end of the vessel 10 and is connected by pipes 18 to valves 20 and 22. A wool grease outlet 24 is located near the top of the vessel. Upper and lower steam pipes 26, 28 extend into the vessel and are each controlled by associated thermocouples 30, 32 which can be set to any desired temperature.

The aqueous phase from the outlet 16 can be directly drained away through the valve 20 or may be fed through a pipe 34 to an overflow chamber 36 adjustably positioned at a height close to the level of wool grease in the vessel.

A conductance probe 33 is provided to monitor the resistivity of the aqueous phase and should this rise, indicating that wool grease or emulsion layer is descending toward the aqueous phase outlet 16, the probe output may operate the valves 20 or 22 to shut off the flow.

In the use of this apparatus, wool grease emulsion ('cream') from a primary centrifuge is preheated to 85 to 100"C, which is the temperature of the central region of the vessel. The vessel is of such a size in comparison to the flow-rate that the residence time of the emulsion is several hours, which is ample to ensure cracking.

The cracked-out wool grease moves up to the top level, which is maintained at 90 to 110 C, and is continuously drawn off through the outlet 24. The aqueous phase moves down towards the lower outlet 18 through the lower region maintained at 75 to 85"C.

The aqueous effluent may be drawn off continuously from the chamber 36, or in batches through the valve 20 controlled by the probe 33. The aqueous phase may be discharged to waste, or recycled if it still contains significant quantities of grease.

Wool grease separated by the process of the invention is of good enough quality for direct sale to manufacturers for the extraction of lanolin or the preparation of other cosmetic and pharmaceutical products from it.

The temperatures employed in the cracking process should not be so high as to cause boiling of any component. If it should be necessary for other reasons to employ temperatures which ordinarily would cause a component to boil, then steps should be taken, e.g. by raising the pressure, to prevent boiling.

WHAT WE CLAIM IS: 1. A method of thermally cracking an emulsion of immiscible liquids differing in density which comprises passing the emulsion into zone heated in such a manner that a thermal gradient exists wherein the top is hotter than the bottom of the zone whereby the zone is maintained substantially free of turbulence, and drawing off the separated components from different regions of the zone.

2. A method according to claim 1 in which the emulsion is continuously introduced at an intermediate level in the heated zone and the lighter component being withdrawn continuously or intermittently from the upper region of the zone and the heavier component from the lower region of the zone.

3. A method according to claim 2 in which the heavier component is withdrawn intermittently in response to detection of a predetermined level of such component in the lower region of the zone.

4. A method according to any of claims 1 to 3 in which the emulsion is an aqueous emulsion of wool grease.

5. Apparatus for thermal cracking of emulsions which comprises a vessel having an inlet for the emulsion, respective outlets for the emulsion components at different levels, and heating means capable of maintaining a thermal gradient in the vessel such that in use the top of the vessel is hotter than the bottom.

6. Apparatus according to claim 5 in which the heating means comprises a first heater in an upper region of the vessel, a second heater in a lower region of the vessel, and temperature detectors in the said upper and lower regions connected to control the operation of the heaters to maintain the said temperature gradient, the inlet being disposed between the heaters, and the outlets being disposed respectively near the top and bottom of the vessel.

7. Apparatus according to claim 6 in which the first and second heaters are respective steam pipes.

8. Apparatus according to claim 5, 6 or 7 in which the lower region of the vessel is provided with an electrical conductivity probe and a discharge valve controlling the lower outlet is operable in response to signals from the probe to discharge the heavier component from the bottom of the vessel when its level within the vessel reaches the probe.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (10)

**WARNING** start of CLMS field may overlap end of DESC **. components differs. The invention will be described in greater detail, by way of example, with reference to the drawing accompanying the Provisional Specification the sole figure of which is a diagrammatic cross sectional view of one form of apparatus for separating an emulsion, e.g. of wool grease, according to the invention. The emulsion cracking apparatus shown in the drawing comprises a vessel 10 having an emulsion inlet pipe 12 extending into the interior of the vessel at a level about half the height of the vessel and provided with a series of perforations 14. An outlet 16 for the aqueous phase is located at the lower end of the vessel 10 and is connected by pipes 18 to valves 20 and 22. A wool grease outlet 24 is located near the top of the vessel. Upper and lower steam pipes 26, 28 extend into the vessel and are each controlled by associated thermocouples 30, 32 which can be set to any desired temperature. The aqueous phase from the outlet 16 can be directly drained away through the valve 20 or may be fed through a pipe 34 to an overflow chamber 36 adjustably positioned at a height close to the level of wool grease in the vessel. A conductance probe 33 is provided to monitor the resistivity of the aqueous phase and should this rise, indicating that wool grease or emulsion layer is descending toward the aqueous phase outlet 16, the probe output may operate the valves 20 or 22 to shut off the flow. In the use of this apparatus, wool grease emulsion ('cream') from a primary centrifuge is preheated to 85 to 100"C, which is the temperature of the central region of the vessel. The vessel is of such a size in comparison to the flow-rate that the residence time of the emulsion is several hours, which is ample to ensure cracking. The cracked-out wool grease moves up to the top level, which is maintained at 90 to 110 C, and is continuously drawn off through the outlet 24. The aqueous phase moves down towards the lower outlet 18 through the lower region maintained at 75 to 85"C. The aqueous effluent may be drawn off continuously from the chamber 36, or in batches through the valve 20 controlled by the probe 33. The aqueous phase may be discharged to waste, or recycled if it still contains significant quantities of grease. Wool grease separated by the process of the invention is of good enough quality for direct sale to manufacturers for the extraction of lanolin or the preparation of other cosmetic and pharmaceutical products from it. The temperatures employed in the cracking process should not be so high as to cause boiling of any component. If it should be necessary for other reasons to employ temperatures which ordinarily would cause a component to boil, then steps should be taken, e.g. by raising the pressure, to prevent boiling. WHAT WE CLAIM IS:

1. A method of thermally cracking an emulsion of immiscible liquids differing in density which comprises passing the emulsion into zone heated in such a manner that a thermal gradient exists wherein the top is hotter than the bottom of the zone whereby the zone is maintained substantially free of turbulence, and drawing off the separated components from different regions of the zone.

2. A method according to claim 1 in which the emulsion is continuously introduced at an intermediate level in the heated zone and the lighter component being withdrawn continuously or intermittently from the upper region of the zone and the heavier component from the lower region of the zone.

3. A method according to claim 2 in which the heavier component is withdrawn intermittently in response to detection of a predetermined level of such component in the lower region of the zone.

4. A method according to any of claims 1 to 3 in which the emulsion is an aqueous emulsion of wool grease.

5. Apparatus for thermal cracking of emulsions which comprises a vessel having an inlet for the emulsion, respective outlets for the emulsion components at different levels, and heating means capable of maintaining a thermal gradient in the vessel such that in use the top of the vessel is hotter than the bottom.

6. Apparatus according to claim 5 in which the heating means comprises a first heater in an upper region of the vessel, a second heater in a lower region of the vessel, and temperature detectors in the said upper and lower regions connected to control the operation of the heaters to maintain the said temperature gradient, the inlet being disposed between the heaters, and the outlets being disposed respectively near the top and bottom of the vessel.

7. Apparatus according to claim 6 in which the first and second heaters are respective steam pipes.

8. Apparatus according to claim 5, 6 or 7 in which the lower region of the vessel is provided with an electrical conductivity probe and a discharge valve controlling the lower outlet is operable in response to signals from the probe to discharge the heavier component from the bottom of the vessel when its level within the vessel reaches the probe.

9. A method of separating emulsions

substantially as described herein with reference to the drawing accompanying the Provisional Specification.

10. Apparatus for separating emulsions substantially as described herein with reference to the drawing accompanying the Provisional Specification.