GB2165768A

GB2165768A - Method and apparatus for destroying froth

Info

Publication number: GB2165768A
Application number: GB08518561A
Authority: GB
Inventors: Gunter Lehnhausen
Original assignee: EKATO IND ANLAGEN VERWALT
Current assignee: EKATO IND ANLAGEN VERWALT
Priority date: 1984-10-22
Filing date: 1985-07-23
Publication date: 1986-04-23
Also published as: DE3438657A1; GB8518561D0; JPS61101213A

Abstract

The invention relates to a turbo- impeller (20) for destroying the froth forming in fermenter tanks for example. For this purpose, the turbo-impeller (20) is disposed immediately in front of the outlet orifice (18) for the spent air as a result of which the froth is at least substantially prevented from being entrained by the spent air through the outlet orifice (18). The turbo-impeller (20) may be installed with a horizontal or vertical plane of rotation but can also be used, in particular, in an inclined position. <IMAGE>

Description

SPECIFICATION Method and apparatus for destroying froth This invention relates to a method and apparatus for destroying froth in reactor tanks. It is particularly applicable to reactor tanks of the type in which there is an outlet orifice for gas, and a turbo-impeller to draw in froth axially and fling it off radially, compressing the froth to liquid droplets in the process.

Froth forms in many chemical and biochemical processes, for example in reactor tanks treated with gas, particularly in fermentation tanks, so-called fermenters.

In order that this froth may not be drawn off from the tanks, for example entrained with waste gas or spent air, it is destroyed by means of froth destroyers, that is to say turbo-impellers which draw the froth in axially and fling it off radially, the froth being compressed into liquid droplets. (When spent air is referred to hereinafter, it means not only air but also other gases).

These turbo-impellers are disposed above the level of the liquid in order to destroy the froth where it forms, as far as possible.

This is possible but it has been found that an optimum destruction of the froth cannot be achieved by this means and, in particular, it is impossible to prevent froth from being entrained with the spent air and carried out of the tank.

It is therefore the object of the invention to dispose the turbo-impeller for destroying the froth so that entrainment of the froth with the spent air and hence a discharge of the froth from the fermenter tank is at least substantially prevented.

According to an aspect of the invention, this is achieved in that the turbo-impeller is disposed immediately in front of the outlet orifice for the waste gas.

The spacing of the turbo-impeller from the outlet orifice is preferably substantially in the range from one-sixth to one-third of the diameter of the turboimpeller.

The diameter of the turbo-impeller may appropriately correspond to the diameter of the outlet orifice; it may also be larger but should not be substantially smaller than the diameter of the outlet orifice.

The invention further relates to a method of destroying the froth, forming in fermenter tanks for example, by means of a turbo-impeller of the abovementioned type, the method being distinguished by the fact that the froth is drawn off immediately in front of the outlet orifice for the spent air and compressed into liquid droplets.

One form of embodiment of the invention is explained by way of example below, with reference to the drawing in which:~ Fig. 1 shows diagrammatically a fermenter tank with a turbo-impeller for destroying the froth disposed according to the invention.

Fig. 2 shows a side view of the turbo-impeller and its arrangement in front of the outlet orifice for the spent air, on a larger scale.

Fig. 1 shows diagrammatically a tank or container 10, for example a fermenter tank, which is filled up to a given height with the liquid to be processed, the level of the liquid being designated by 12. Froth 14 has formed above the level 12 of the liquid and is to be destroyed in order to prevent the froth from being discharged from the tank 10 through an outlet duct 30, through which the spent air flows away.

In order to destroy the froth 14, a turbo-impeller 20, knownperse, is used which is mounted on a drive shaft 22 which is driven by a drive not illustrated in the drawing, for example an electric motor.

As illustrated in Fig. 1, the outlet duct 30 is disposed in the curved region 16 of the wall of the tank 10.

As the Fig. shows, the turbo-impeller 20 is disposed immediately in front of the outlet orifice 18 in the wall of the tank 10, in accordance with the invention.

If desired, the outlet orifice and hence the turboimpeller 20 may be disposed in the plane horizontal region 24, the tapered region 26 or the vertical cylindrical region 28 of the wall of the tank 10, the only important thing being that the turbo-impeller 20 is situated immediately in front of the outlet orifice 18.

Fig. 2 shows the turbo-impeller 20, which is disposed immediately in front of the outlet orifice 18 in the wall of the tank 10, on a larger scale than Fig.

1. As already mentioned, the turbo-impeller 20 is set in rotation via its shaft 22 by a drive not shown, for example an electric motor. It draws the froth in axially along the arrows P1 and flings it off radially in the direction of the arrows P3, the froth being compressed into liquid droplets during and by this centrifuging, as known per se.

Any froth entrained by the spent air is drawn out of the region between the turbo-impeller and the outlet orifice, as indicated diagrammatically by the arrows P2, and is likewise flung away in the direction of the arrows P3, with compression into liquid droplets.

As illustrated in Fig. 2, the outlet duct 30 is secured to the wall of the tank 10 by means of mounting flanges 36,34 and the actual spent-air outlet 32 is branched off from the outlet duct 30. The shaft 22 extends through the outlet duct 30 (not illustrated) to the drive, likewise not shown.

The median plane (that is to say the plane perpendicular to the centre axis of the shaft 22) may appropriately extend parallel to the plane of the outlet orifice 18.

The spacing A between the outlet orifice 18 and the turbo-impeller 20 is preferably in the range from one-sixth to one-third of the diameter D of the turboimpeller 20. The diameter D of the turbo-impeller 20 preferably corresponds substantially to the diameter dofthe outlet orifice 18; it may be larger than the latter but should preferably not be substantially smaller than the diameter d of the outlet orifice 18.

The turbo-impeller 20 can be adapted to all sizes of fermenter and to all sizes of the outiet orifice. it can be used in an inclined position, as illustrated, but may also be positioned in a horizontal or vertical position.

The invention has been described with reference to fermenters, which are understood to mean apparatus in which micro-organisms are cultivated in a liquid, the metabolites of which microorganisms generally represent valuable materials, for example, penicillin. In order to supply the organisms with 02, the fermentation liquid must be aerated.

Since many liquors tend to froth, the froth formed would leave the fermentation tank with the waste gas. This would lead to production losses and in addition the froth would have to be disposed of in some way.

In order to avoid this, the froth is destroyed inside the fermentation tank.

Claims

1. A method of destroying froth in reactor tanks having a gas outlet orifice, in which the froth is drawn into an axial-inflow radial-oufflow turboimpeller and compressed to form liquid droplets, characterised in that the froth is destroyed directly in front of the outlet orifice.

2. A reactor tank for performing the method claimed in claim 1, characterised in that the turboimpeller is disposed directly in front of the outlet orifice.

3. A reactor tank as claimed in claim 2 in which the distance of the turbo-impeller from the outlet orifice is in the range one-sixth to one-third of the turboimpeller diameter.

4. A reactor tank as claimed in claim 2 or claim 3 in which the diameter of the turbo-impeller is substantially equal to the diameter of the outlet orifice.

5. A turbo-impeller and outlet duct assembly for mounting to a container to produce a reactor tank as claimed in any of claims 2 to 4.

6. A method of destroying froth in reactor tanks as claimed in claim 1 and substantially as described.

7. A reactor tank substantially as described with reference to the Drawings.

8. Aturbo-impeller and outlet duct assembly substantially as described with reference to Fig. 2.