DE3025671A1 - METHOD AND DEVICE FOR RECOVERING A FOAM MOLD FROM A LIQUID CONTAINING A FOAM MOLD - Google Patents

Description

ALFA-LAVAL AB, Fack, S-147 OO Tumba, Sweden

Method and device for the recovery of a foaming agent from a foaming agent containing liquid

The invention relates to a method for recovery a foaming agent from a liquid containing a foaming agent, which is obtained from a process, in which a gas flowing in a channel is brought into contact with a layer of foam, which is thus in the Liquid containing foaming agents is degraded.

The invention also relates to a device for recovering a foaming agent from such a device Foaming agent-containing liquid, wherein the

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Bremen / Bremen Office:
P.O. Box / PO Box 10 7] 27
Hollerallee 32, D-2800 Bremen 1
Telephone: (0421) - 34 90 71
Facsimile / Telecopier: Rank Xerox 400
Telegr. / Cables: diagram Bremen
Telex: 244 958 bopatd

030067/0680

Accounts Bremen:

Bremer Bank, Bremen

(Sort code 290 800 10) 300144

Deutsche Bank. Bremen

(Sort code 290 700 50) 1312002

PSchA Hamburg

(Sort code 200 100 20) 1260 83-202 Munich Office: Postfach / P.O.Box 34 0108 Schlotthauerslraße 3. D-8000 Munich 5 Telephone: (089) 65 23 21 Telecop./Teleeop .: (089) 2215 69 R. X. 400 Telegr. / Cables: Telepatent Munich Telex: 523937 jus d (code: forbo)

Liquid obtained by a process in which a
Gas flowing in a channel in contact with a
Foam layer is brought, which is broken down into the liquid containing the foaming agent.

As can be seen from SE-PS 6715724-8, 354194 and 7506461-8

is known, find such methods for a multitude of j

number of purposes use. Such procedures can I serve to separate particles from a gas,

such as cleaning gases (e.g. exhaust gases), J

thus of fine, solid particles distributed therein, i

or also for the recovery of one in a gas |

distributed substance, such as an oxide from the Ab-;

gas of a steelworks, the polluted gas;

or the gas-dust mixture can be passed through a foam bed, which is created by a foaming agent or
a foaming agent or a surfactant
is generated and in which the impurities are trapped
will.

In this way, the foam is broken down into a polluted liquid, which contains foaming agents and dirt particles
contains, and in the form of a concentrated digested sludge,
which is discharged at the channel-shaped bottom of the cleaner
will.

The foam layer is created by a gas (usually air)
and a liquid (preferably water) with addition
a foaming agent generated.

Such a method is also used for the reaction
to convey between a liquid and a gas,
wherein the liquid by means of a gas other than
the reaction gas is converted into foam, where appropriate a

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Foaming agent is added.

One example of such a process is desulfurization of crude oil using a carbon sulphide with added foaming agent which is mixed with Hydrogen gas creates foam that goes along with the hydrogen sulfide from a previous step of the method is brought into contact.

The method in question can also be a combination of the individual processes mentioned above Act. You can e.g. the gas of solid, liquid or gaseous substances or impurities be clean, while the gas as such acts as a reactant for a chemical reaction with the liquid phase in the foam layer is used.

An example of this is the cleaning of the exhaust gas that occurs during the production of MPK fertilizer, the MPK ~ Particles or ammonium containing, with nitric acid as a reactant to one containing a surfactant Foam layer is sprinkled against which the ammonium gas containing the particle is directed.

Another example is the cleaning of exhaust gases from oil burners or diesel engines in tankers in order to remove the from To use sulfur dioxide and solid soot particles as an inert gas in the free spaces of the oil tanks, the cleaning being carried out by means of sodium hydroxide based on a surfactant containing agent Foam bed is sprayed, which intercepts the soot particles.

In order to achieve the desired profitability in particular

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To achieve large plants, there is a need to be able to reuse the foaming agent. When the substances or impurities consist of solid particles, these can be removed relatively easily from the foam solution be deposited so that the foam solution can be reintroduced into the process. If but the substances or impurities are soluble in the liquid leaving the channel, as is the case with the Absorption of a gas in a dissolved absorption medium is the case, or in the separation of solid substances that are soluble in the liquid leaving the channel, this liquid or this effluent cannot be returned to the treatment channel because of the substances or impurities are resolved in it.

The object of the present invention is to provide an effective method and a device for recovery of foaming agents from a liquid containing a foaming agent, the liquid in particular originates from one of the processes or methods described above.

According to the invention, this object is achieved in terms of the method solved that in a separate step carried out outside the channel, a gas stream with the liquid in Contact is brought to produce a foam phase above a liquid phase, the foam phase at their creation is recovered.

The invention is based on the fact that a foaming,

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Surfactant enriched in the foam phase when a gas is introduced into the liquid to generate a foam. The foam produced can e.g. be broken down by means of mechanical foam reducers, creating a liquid phase enriched with foaming agent is to be obtained.

The liquid removed from the treatment channel of this process can thus be separated into two parts according to the invention, one part forming the main part of the liquid phase and the dissolved substances and a low concentration of the foaming agent, while the other part consists of a smaller proportion of the liquid and one has a significantly higher foaming agent concentration. The solution enriched with foaming agent can be put into the treatment channel the process concerned can be recycled either directly or indirectly, while the fewer foaming agents containing larger proportion is fed to the outlet or subjected to a further treatment in order to be therein recover material containing it.

The use of the method according to the invention for recovering the foaming agent allows the consumption of to significantly reduce fresh foaming agent. For example, it is possible to reduce consumption by at least 2/3. At the same time, the risk of becoming undesirable in the outflowing liquid in one of the subsequent process steps To obtain foam formation is reduced, since the proportion "depleted" of foaming agent is such a low concentration contains that no disturbances in this direction are to be expected in the subsequent process steps.

The invention is of course applicable in all cases in

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'where the recovery of foaming agents from one one Foaming agent-containing liquid is desirable, for example even in a case where the liquid has solid impurities that form a sludge. In general terms, the method according to the invention for the recovery of a foaming agent from such a liquid which contains foaming agents and which in addition to the foaming agent, at least one different compound or material and a carrier or a solvent for this compound or this material and the foaming agent can be used.

Further features and advantages of the invention emerge from the claims and from the following description, in which an exemplary embodiment is explained in detail with reference to the drawing.

The drawing shows a schematic flow diagram a foam cleaning system and a system according to the invention for separation or recovery.

The foam cleaning system has a foam scrubber 1, which is fed through an inlet 2 with foam from a foam generator 3 is supplied, the foam in the generator by supplying compressed air and foam solution by special Inlets 4 and 5 are created and the foam solution is provided from a container 6 by means of a pump 7 will. The foam solution consists of a suitable foaming agent which is mixed with a liquid, usually water, is mixed.

The foam scrubber 1 is in the form of a vertical treatment channel. Through a lower inlet 8, e.g.

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most impure gas introduced. Purified gas is through taken from an upper outlet 9. The channel contains a perforated partition wall 10 (or a "mesh"), which both the partition wall serves to distribute the gas flow and also to support the foam bed 11 at a predetermined height covers the entire cross section of the channel and is above the gas inlet 8 at a certain distance from the ground of the scrubber 1 arranged. The height and the composition of the foam bed can be determined by a special component, as described, for example, in U.S. Patent No. 4,003,724.

When the polluted gas - i.e. the gas that contains impurities - flows upwards through the foam bed 11, the impurities are caught by the foam, which is broken down in this way into a liquid that Contains impurities and foaming. The liquid containing foaming agents and impurities runs down into the lower part of the foam scrubber 1 and will removed through an outlet 13. It is then collected in a circulation tank 14 which has a lower outlet for the purpose of removing the concentrated, undissolved material-containing sludge, which is removed or re-introduced into the Process is introduced, has. By means of a circulation pump 16, liquid enriched with foaming agent is added returned through the pipe 17 into the foam scrubber 1.

The scrubber effluent is transferred from the tank 14 to an inventive one Separator transferred. The separator comprises a container 18 with an inlet 19 for the Skubber outflow and an inlet pipe 20, through the inlet 20 compressed air is supplied to a number of nozzles 21, the inside the container with a certain distance below

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of the liquid level 22 are arranged. These nozzles create a large number of air bubbles that rise upwards flow through the liquid. The foaming agent is naturally surface-active and therefore becomes active at the interface between air and liquid, e.g. on the bladder wall. So in this way the Foaming agent enriched in a foam phase 23 by means of the air flow through the scrubber outlet. A liquid one Phase 24, which contains a low concentration of foaming agent, is therefore created in the soil layer, with the liquid phase contains dissolved substances from the previous process in the foam scrubber 1. This is through a Outlet 25 branched off and either discharged into the sewage system or for the purpose of recovering the contained therein Materials further treated.

The separator also has a mechanical foam destroyer 26, which is arranged in the upper part of the tank 18 is, and the parts 27 of which are arranged in a space 29 which is delimited by the housing 28, with an opening 30 is provided in the wall between the housing and the tank 18, which has an inlet opening to the foam destroyer 26 forms so that the foam, as soon as it has risen to the level of the opening 30 after generation, the foam destroyer 26 is fed.

The foam destroyer 26 is designed mechanically and is based on the principle that the air bubbles burst as a result allow them to be subjected to a sudden drop in pressure. This can be achieved by making the foam is pressed through an opening which is initially tapered and then widened into an expansion nozzle (e.g. from the Type of venturi nozzle), whereby the air bubbles burst when

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they pass the narrowest point. The venturi nozzles will be formed by a unit that has a number of annular lamellae mounted on a vertical shaft are rotatable, and the foam is drawn up through the central space of the annular lamellas by suction and forced through the venturi nozzles by centrifugal forces. The suction and centrifugal forces can can be achieved in a known manner by specially arranged fan blades.

The liquid formed by the destruction of the air bubbles is collected within the housing 28 and through the lower Outlet 31 removed from the housing while released air and excess air through an upper outlet 32 are discharged. The liquid obtained in this way necessarily has a higher concentration of foaming agent and is fed to the circulation tank 14 for the purpose of being returned to the foam scrubber 1. The circulating fluid is sprayed from above onto the foam bed 11 in the scrubber 1 through one or more nozzles 33.

Another solution provides that the solution enriched with foaming agent from the tank 18 either partially or is fed directly to the foam scrubber 1.

Although the foam scrubber 1 has been described in connection with the removal of contaminants in gas, it can of course also be used for other processes, such as those described in the introduction, in which the gas is reactive and can contain impurities, and in which the outflowing liquid Contains dissolved substances or impurities.

In the following a laboratory test is described in which the foaming agent using one according to the invention

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Separator was recovered.

0.45 1 of a foam concentrate FOAMIX 3030 (anionic, surface-active medium) was in a tank 1200 1 Added water, giving a concentration of about 0.037%. 10 m of air per hour were introduced and in the tank through two centrifugal nozzles so that foam was formed. The foam produced was through a mechanical Foam destroyer destroyed. The liquid phase enriched with foaming agent was then passed through an outlet pipe in one side of the tank, which is connected to a collecting j

\ container or a housing around the foam destroyer *

is bound, discharged. \

The experiment was carried out for 50 minutes and j

after 0 and 50 minutes, samples of the liquid in the j

Tank and the liquid in the shredder. To ;

0 minutes the liquid flow from the annihilator was j

about 8 l / min, and after 50 minutes about 3 l / min. The ent-;

Samples taken were analyzed for the amount of anionic, surface-active material and the result was converted to give the following percentage of foam concentrate:

• t (min)

50

Concentration in the tank 0.025% 0.007%

Concentration in the foam destroyer 0.13% O, 13%

From these values it can be seen that after 0 minutes the concentration from the destroyer was about 5 times greater than the concentration in the tank. After 50 minutes it was

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Concentration from the annihilator about 20 times greater than
those in the tank. A comparison of the concentration in the tank after 0 minutes indicates that the solution in the tank during this
Experiment has missed about 70% of the foaming agent. This is also confirmed by the fact that the flow from the foam killer has decreased accordingly.

The features of the invention disclosed in the above description, the drawing and in the claims can both individually and in any combination for the implementation of the invention in its various embodiments be essential.

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0 30067/068 0

HOKHMKRT

File: A 1548

4 july 19

B SZ ¹ JGo Z sich KNL13 TS (LIST OF.RSFSRSKCE NUMERALS)

1 wet cleaner, scrubber 1 ρ inlet P. ^ Foam generator 4 inlet 4th 5 inlet 5 6 containers 6th 7 pump 7th 8 inlet 8th 9 outlet 9 10 partition 10 11 foam bed 11 12th 12th 15 outlet 15th 14 tank 14th 15 outlet 15th 16 pump 16 17 pipe 17th 18 containers 18th 19 inlet 19th ? 0 pipe 20th 21 nozzles 21st 22 liquid level 22nd ? 3 Schaunrohase 25th • -4 · liquid phase 24 25 outlet 25th ^ f) Foam destroyer 26th .57 pieces (of 26) 27 "" 8 housing 28 29 room 29 -30 opening 30th

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31 outlet 31 32 outlet 32 33 nozzle 33 34 34 35 35 36 36 37 37 38 38 39 39 40 40 41 41 42 42 43 43 44 44 45 45 46 46 47 47 48 48 49 49 50 50 51 51 52 52 53 53 54 54 55 · 55 56 56 57 57 58 58 59 59 60 60 61 61 62 62 63 63 64 64 65 65

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Claims (8)

A 1548 July 4, 1980 CLAIMS 1. Process for the recovery of a foaming agent a liquid containing a foaming agent obtained from a process in which one in one Channel flowing gas is brought into contact with a foam layer, which is so contained in the foaming agent Liquid is degraded, characterized in that carried out in a separate, outside of the channel (1) A gas stream is brought into contact with the liquid to form a foam phase (23) above a step to generate liquid phase, the foam phase (23) being recovered when it is formed. 2. The method according to claim 1, characterized in that the foam phase (23) is broken down in liquid. 3. The method according to claim 2, characterized in that the breakdown of the foam phase (23) takes place close to the location on which the foam phase (23) is generated. 4. The method according to claim 2, characterized in that that the decomposition of the foam phase (23) takes place away from the location at which the foam phase (23) is generated. 0 3 0 0 6 7/0680 5. The method according to any one of the preceding claims, characterized in that the gas stream consists of air. 6. Device for the recovery of a foaming agent from a liquid containing such a foaming agent, the liquid being obtained by a process in which a gas flowing in a channel is brought into contact with a layer of foam, which is so in the Liquid containing foaming agent is broken down, characterized by a tank (18) with an inlet (19) for the liquid; Means (20, 21) with which the gas flow is brought into contact with the liquid is to create a foam phase (23) above the liquid phase; Means (30) for removal the foam phase (23) above the liquid phase from the tank (18); and a bottom outlet (25) for removal the liquid (24) having a low foaming agent concentration from the tank (18). 7. Apparatus according to claim 6, characterized in that also means (26) for breaking down the foam phase produced (23) are provided, which is discharged into a solution with a high proportion of foaming agent. 8. Apparatus according to claim 7, characterized in that the means comprise a mechanical foam destroyer known per se (26), the parts (27) of which are arranged in a housing (28) which has an opening (30) is connected to the space section of the tank (18) provided for the foam phase (23). 030067/0880