The present invention relates to a method for deodorising organic fluids or inorganic fluids, a plug flow tray, a tray column, a deodorisation column, a plant, and use thereof.

Background of the invention

Processes for purifying oils and fats comprise columns, which operate more or less in batch wise processes. This might risk to impose differences in the process time for the individual oil molecule resulting in lower quality the treated oil or fat, since the oil or fat are treated in trays operating by the overflow drainage principle. In chapter 6, volume 4 of Edible Oil and Fat Products; Process Technology, edited by Y.H. Hui, pages 339 to 390, Copyright © 1996 by John Wiley & Sons, Inc. are different principal processes described for deodorising of oils and fats.

One aim for the present invention is to provide a continuous or a semi continuous method for purifying oils and fats having an equal retention time for majority of all molecules in each tray of the column.

Another aim is to provide tools for accomplish the method.

The invention Accordingly the present invention provides a new method for purifying fluids, such as for example all edible oils and fats and mineral oils. The new method can operate continuously, semi continuously or both. The concept of the method is to create a uniform retention time for all molecules or droplets, i.e. all molecules or droplets may flow as a steady flow through the whole tray or the whole column from inlet to outlet, by the principle first in first out. Thus the present invention relates to a

method for deodorising high-boiling organic or inorganic fluids, which method comprises creating a continuous flow or semi continuous flow of fluids through a column having one or more trays, creating a plug flow of the fluids through a labyrinth of passages on each tray by regulating the flow through the passages by use of a regulating valve at an exit in the tray, introducing sparging gas on the bottom level of each tray, contacting the fluids with the sparging gas in the plug flow, removing volatiles from the fluids, and transferring the sparging gas and the volatiles in a duct inside the column or outside the column.

The method may also comprise transferring the flow of fluids through the regulating valve to another plug flow tray, or to an economiser heat exchanger. The flow of fluids may be transferred through the regulating valve to the centre of another plug flow tray, to the periphery of another plug flow tray, or through a collecting pipe having the regulating valve at the exit.

The method may also comprise introducing of sparging gas at a bottom level of the trays. According to one alternative embodiment of the method may the sparging gas be introduced at a velocity within a range of from about 20 m/sec to about 40 m/sec. According to a further alternative embodiment of the method may the sparging gas be introduce at a velocity less than about 30 m/sec. The method also comprises that the sparging gas can be selected from water vapour, low molecular fluids, or combinations thereof.

The plug flow of the present method may have a total retention time of less than 60 minutes through the column. According to one alternative embodiment of the method the total retention time may be less than 45 minutes, and according to yet another alternative embodiment of the

method the total retention time may be less than 30 minutes. According to a further alternative embodiment of the method the total retention time may be within the range of from about 2 to 30 minutes.

The temperature at which the column can be operating can be less than 28O ⁰ C. According to one alternative embodiment of the method may the column be operating at a temperature within the range of from about 25O ⁰ C to about 27O ⁰ C.

The pressure at which the column can be operating can be less than 20 mbar. According to one alternative embodiment of the method may the column operate at a pressure can be less than 15 mbar. According to one alternative embodiment of the method may the column operate at a pressure within a range of from about 0.5 to about 10 mbar. According to yet another alternative embodiment of the method may the column operate at a pressure within a range of from about 1.5 to about 5 mbar.

According to the method may the fluids be selected from the group consisting of all edible oils, vegetable oils or fats, animal oils or fats, fish oils, but also mineral oils.

The present invention relates also to a plug flow tray for tray columns, which tray comprises a passage labyrinth of an assembly of baffles connected to the tray bottom and one regulating valve in the tray bottom.

The passage labyrinth may be arranged so that baffle plates are arranged across the flow, and channel plates are arranged along the flow.

The baffles may be connected to the bottom by welding, by brazing, part- welding, part-brazing or combinations thereof, or by any other suitable way of connecting.

The tray layout may comprise an arrangement of baffles mounted in concentric shapes, of spiral shapes, or both, to a tray bottom. Each baffle element may be shaped in such a way that a simple geometry for both baffle and tray can be ascertained, particularly for joining to the assembly of baffles to the bottom. The entire arrangement of baffles may be such, that a continuous passage may be developed in the tray section with the aim of producing as long a passage as can be practically possible.

The tray bottom may be horizontal, sloping towards, or away from the centre, and according to one alternative embodiment may the bottom of the tray be flat, be prismed conical or be circular conical. According to one alternative embodiment may the bottom of the tray be sloping downwards or upward in an angle less than 10°. According to yet another alternative embodiment may the angle be at least 0.5°. According to a further alternative embodiment may the angle be within the range of from about 0.5° to about 5°.

The plug flow tray may also comprise sparging pipes, which are mounted at the bottom level of the tray. According to one alternative embodiment may the sparging pipes have holes, or passages for sparging gas with a diameter within a range of from about 0.5 mm to about 2 mm.

The passage may be continuously directing the fluids towards an exit point at the end, which could be fitted with a flow control device, which may be a regulating valve. The exit point may be in the centre of the tray,

at an exit point in the periphery of the tray, or at an exit point at the end of a collecting pipe.

Additionally, one sector in the baffle arrangement could be a void in order to use as a duct for distributing vacuum, or to let out volatile gasses from successive trays mounted below, or both. Accordingly the tray may also comprise at least one duct for vacuum and sparging gas.

The present invention relates also to a tray column, which comprises one or more plug flow trays having a passage labyrinth of an assembly of baffles connected to the tray bottom and one regulating valve at the tray bottom. According to one alternative embodiment can the tray column have less than 10 plug flow trays. According to another alternative embodiment may the tray column have at least one plug flow tray, and according to yet another alternative embodiment may the column have up to six plug flow trays

The present invention relates also to a deodorisation column, which comprises at least one tray column, and at least one distilling column or at least one stripper having structured packing material. The distilling column or the stripper may have fluid collectors mounted at the bottom of the distilling column or stripper above the tray column.

According to one alternative embodiment of the invention can the columns be mounted as one vessel containing both the tray column and the distilling column, or can be mounted as two vessels, the tray column and the distilling column connected with a connection pipe. The sparging gas, the vacuum or both can be transported via ducts in the trays, via ducts outside the column, or combinations thereof.

The present invention relates further to a plant comprising the deodorising column, at least one heat exchanger or economiser, and at least one scrubber, the invention relates also to use of the deodorisation plant for purifying all edible oils, vegetable oils or fats, animal oils or fats, fish oils, or mineral oils. Further embodiments of the invention are defined by the claims.

In the following the present invention will be explained in more detail by means of the attached drawings.

Brief description of the drawings Figure 1 is showing a cross section of one alternative baffle arrangement according to the invention.

Figure 2 is showing a cross section of another alternative baffle arrangement according to the invention.

Figure 3 is showing a cross section of a further alternative baffle arrangement according to the invention. Figure 4 is showing a cross section of a further alternative baffle arrangement according to the invention. Figure 5 is showing a cross section of side view of a collecting device having a regulating valve at the exit, according to one alternative embodiment of the invention. Figure 6 is showing a cross section of a tray having sparging pipes according to one alternative embodiment. Figure 7 is showing a cross section of a side view of a tray column according to one alternative embodiment of the invention. Figure 8 is showing a cross section of a side view of a tray column according to another alternative embodiment of the invention.

Figure 9 is showing a cross section of a side view of a tray column showing gas and vacuum ducts inside the column according to one alternative embodiment.

Figure 10 is showing a cross section of a side view of a tray column showing gas and vacuum ducts outside the column according to another alternative embodiment.

Detailed description of the drawings A spiral arrangement of baffles 1 is shown in Figure 1 , forming a spiral labyrinth of passages, in which the fluids flow from an inlet point 2 to an exit point 3. In Figure 2, 3 and 4 are other arrangements of a spiral labyrinth of passages disclosed. The fluids are directed through passages to flow for as long time as possible before leaving the tray at exit point 3. A duct 4 for sparging gas and vacuum are shown in the figures. Depending on if the tray bottoms are turned upwards or downwards inlet point 2 and exit point 3 may change place according to alternative embodiments of the invention. In all Figures 1 to 4 a regulating valve is mounted at or close to the exit point 3, the regulating valve is not shown in the figures.

The fluids are leaving the trays at an exit point 3 in the tray and are transferred to a collecting device 5 according to one alternative embodiment. The collecting device is sloping sideways in the direction towards the periphery of a tray below and over an inlet point not shown in the figure. At the end point 6 of the collecting device is a regulating valve 7 mounted, which regulates the fluid flow in the passages of the tray above. Sparging pipes 8 are mounted at the bottom of the tray.

Each tray is equipped with several sparging pipes 8 which can be seen in Figure 6. Figure 6 shows also under lying collecting device 5 having

regulating valve 7. The bottoms of the plug flow trays in the tray column can be horizontal, turned upwards or downwards. In figure 7 are the trays both turned upwards and downwards according to one alternative embodiment. Tray 9 is turned downwards having an angle θ, which can be less than 10°. At the lowest point is an exit point 3 to which a regulating valve 7 is mounted. The flow of fluids will be transferred from the regulating valve mounted in the centre of tray to an inlet point 2 on tray 10. Tray 10 is turned upwards. The flow of fluids will pass the labyrinth of passages from the inlet point in the centre of the tray out to an exit point 3 at the periphery. Mounted to exit point 3 is a regulating valve 7. Also Tray 10 is having an angle θ, which is less than 10°.

Figure 8 shows a tray column having only trays sloping downwards. According to this alternative embodiment are the trays equipped with collecting devices 5 and regulating valves 7, which are mounted at the periphery of the column. Ducts 4 for vacuum, volatiles and sparging gas according to one alternative embodiment are mounted inside the tray column, which can be seen in Figure 9. Figure 10 is showing another alternative embodiment wherein the ducts 4 are mounted outside the tray column.