DE3727132A1 - Method for destabilizing and destroying foams by thermal energy - Google Patents

Abstract

To destabilize and destroy foams, as are formed, in particular, in chemical and biological processes, thermal energy is introduced into the foam volume and as a result the mechanical strength of the foam is decreased. The thermal energy can be transmitted by steam or by a hot gas. The foam bubbles burst either during the heat transfer or they can easily and effectively be destroyed mechanically.

Description

The invention relates to a method for destabilizing and Destruction of foams with thermal energy.

The problem of foam formation occurs in many chemicals and biological processes. The foaming rates (i.e. the foam volume formed per unit of time) can in many cases len be so high that the process control without foam destruction measures is made very difficult.

Especially during fermentation processes, it can happen during the micro organism growth lead to a strong foaming. The Foaming is caused by the necessary in aerobic processes Aeration and stirring of the substrate, for anaerobic fermentation processes by generated gas, as well as by proteins, which as Metabolic products of the microorganisms arise conditionally. Proteins belong to the group of amphoteric surfactants. You own both hydrophobic and hydrophilic groups within their Chain frame. As a result, proteins act like washing-active sub punch, which reduces the surface tension of the culture broth zen and thus promote foam formation.

Foam can be chemical, mechanical and thermal Fight Wise.

Chemical anti-foaming agents can only be added when the product produced by the anti-foaming agent is not damaged and if it is easy to separate from the product leaves. Chemical anti-foaming agents can also be negative on the viscosity and the oxygen transport in the reactor Act.

Mechanical foam destroyers deliver with high foam formation advise unsatisfactory results due to insufficient lei endurance.

The invention has for its object to effectively foam destroy without adversely affecting the production process ses.

This object is achieved according to the invention in that steam or a hot gas either directly into the foam layer or is blown in above the foam layer. By doing it The heat transferred will be the one in the individual gas bubbles closed gas volumia heated and there is a Ver enlargement of the foam bubbles. This is associated with a decrease the thickness of the inner lamellar liquid layer between the individual foam bubbles. It also causes the temperature increase a decrease in the viscosity of this layer of the inner layer mellar fluid. Because of these physical processes the stability of the foam is reduced so much that the foam bubbles either during the heat transfer from itself burst, or by introducing mechanical energy can be easily and effectively destroyed. The mechanical Energy can be obtained through a compressed gas, ultrasound or by a mechanical foam cutter.

Whether the foam is just by introducing thermal energy gie destroyed, or whether the foam is only destabili and is broken down by the introduction of mechanical energy must be disturbed depends on the consistency of the he produced foam.

According to the invention, the foam height above the liquid can be regulated in two ways:
1. by supplying thermal energy in cycles
2. by continuously supplying thermal energy.

When the thermal energy is supplied in cycles, it becomes one brought as soon as the foam over the liquid a be agreed height has reached. The entire foam vo lumen destroyed.

With continuous supply of thermal energy, pro Unit of time destroyed as much foam as on the rivers liquid surface is formed. So the foam height can be kept at a constant level.

The critical height of the foam level is according to the invention Using a level meter (e.g. optically using a differential photodiode) detected. Steam or hot gas are fiction according to by flat slot or round hole nozzles, which over the Ver volume and / or the lid of the corresponding container parts are blown in evenly.  

Principle of operation of the process

The height of the foam crown above the fermentation broth is measured with a suitable foam measuring probe 1 . Optical as well as working on the conductivity principle can be used as measuring methods. If a predetermined foam height is exceeded, this is registered by the foam probe 1 and a corresponding signal is sent to the control unit 2 . Via the control unit 2 on the steam generator (or gas heater) control valves are opened and steam (or hot gas) is injected via nozzles 4 into the head space of the bioreactor. This destroys the foam above the fermentation broth and the foam height drops below the specified critical value. The control unit 2 then closes the control valves on the steam generator 3 .

Claims (10)

1. A method for destabilizing and destroying foams, characterized in that the mechanical strength of the foam is greatly reduced by the introduction of thermal energy. 2. The method according to claim 1, characterized in that the Thermal energy is introduced by steam. 3. The method according to claim 1, characterized in that the Introduction of thermal energy through a heated Gas occurs. 4. The method according to claims 1-3, characterized in that after the foam has been destabilized by thermal energy of the foam through a mechanical Foam destroyer is destroyed. 5. The method according to claims 1-3, characterized in that after the foam has been destabilized by thermal energy of the foam by blowing one Gas is destroyed. 6. The method according to claims 1-3, characterized net that after destabilization of the foam by supplying thermal energy the foam through Ultra sound is destroyed. 7. The method according to claims 1-6, characterized net that the introduction of thermal energy continu is done.   8. The method according to claims 1-6, characterized net that the introduction of thermal energy tactaktwei se is done. 9. The method according to claims 1-8, characterized net that the critical foam height at which destruction is to be detected using level measuring devices. 10. The method according to claims 1-9, characterized net that steam or heated gas over flat slot or Round hole nozzles, which over the circumference or cover of the ent speaking container are distributed evenly will.