Liquid purification or separation – With means to add treating material – Chromatography
Patent
1987-03-19
1988-02-02
Therkorn, Ernest G.
Liquid purification or separation
With means to add treating material
Chromatography
55386, 422 70, 422211, 422310, B01D 1508
Patent
active
047227869
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to a head for uniformly dispersing a liquid over the input surface of a chromatographic or reactive bed in a preparative column having a predetermined back pressure per unit flow rate, comprising an inlet tube through which the liquid is supplied.
BACKGROUND ART
For a chromatographic separation it is common to utilize at least three diffrent liquids, namely a sample liquid, a wash liquid, and an elution liquid.
These liquids are transferred to the chromatographic column by means of a pump, and each liquid is selected in turn by a tap or rotary valve.
The liquids will be pumped through conveniently sized tubing to the chromatographic column which may be 10 or 100 times larger in diameter than the tubing.
It is necessary that the connecting tubing is relatively small in diameter so that the liquids are delivered in a plug-flow manner. Thereby, the liquids will not experience excessive drag at the wall of the tubing or diffusion with the liquids in front and behind, respectively.
In known columns the liquids enter the distribution region of the columns in a turbulent state with a linear velocity which is normally 300-1000 times higher than the linear flow velocity through the column.
This sudden change in velocity tends to induce mixing of the liquids, and makes the sample trail onto a column during the sample loading stage.
DISCLOSURE OF INVENTION
The object of the invention is to bring about a distribution head for a preparative column, which effectively reduces the input velocity of the pumped liquids, and creates a uniform laminar flow over the input surface of the bed in the column.
This is attained in that the head according to the invention has obtained the characterizing features defined in the claims.
BRIEF DESCRIPTION OF DRAWINGS
The invention will be described more in detail below with reference to the drawings on which FIG. 1 is a cross-sectional view of one embodiment of a head according to the invention, FIG. 2 is a sectional view along line A--A in FIG. 1, FIG. 3 is a sectional view of another embodiment of the head according to the invention, and FIG. 4 is a sectional view of a further embodiment of the head according to the invention.
DETAILED DESCRIPTION
FIGS. 1 and 2 show a first embodiment of a head according to the invention for uniformly dispersing a liquid over the input surface of a chromatographic or reactive bed in a preparative column (not shown). The head is denoted 1 and comprises an inlet tube 2 through which the liquid is supplied.
To uniformly disperse a liquid onto such a bed (not shown) it is necessary for the head 1 to induce laminar flow of the liquid. The head 1 should, therefore, effectively reduce the input velocity of the pumped liquids and create a uniform laminar flow over the input surface of the bed in the column (not shown), and this should be accomplished in the minimum volume to limit diffusion between contiguous quantities of liquid entering the head 1.
Thus, the liquid flow through the packed column bed should be equated to horizontal liquid flow in the head 1, which means that liquid for the outer bed region must be supplied by liquid flowing from the centre of the head 1.
According to the invention the head 1 has a central domed part 3 into which the inlet tube 2 enters. The central domed part blends into a profiled lower part 4, the profile of which is described by the equation ##EQU1## where R is the internal radius of the column (not shown), inside surface of the profiled part 4 at a distance x from the central vertical axis of the head 1, and column. x is smaller than or equal to R, and greater than or equal to R/15, preferably greater than or equal to R/4.
The object of the central domed part 3 which may be e.g. semi-spherical or of an arched vertical cross-sectional form, is to destroy the excess kinetic energy of the input liquid, and to form a laminar flow region prior to the liquid entering into the wider profiled part 4.
To enforce the loss of kinetic energy the inlet tube 2 is horizontal and enters
REFERENCES:
patent: 3298527 (1967-01-01), Wright
patent: 3511377 (1970-05-01), Hrdina
patent: 3780866 (1973-12-01), Ek
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