JPH0476675B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to foam control compositions consisting essentially of polydimethylsiloxane, a silica compound, a polyoxypropylene polymer, certain nonionic surfactants as hereinafter indicated, and certain dispersants as hereinafter indicated. More particularly, the composition is used to control foaming in processes for obtaining alcohol from sugar cane. Obtaining alcohol from sugar cane has become increasingly important due to the global oil crisis.
The alcohol can be a fuel source used on its own or as an additive that can be substituted at least in part for conventional fuels such as gasoline. Accordingly, the production of alcohol by fermentation of molasses and direct fermentation of sugar cane has become desirable. In direct fermentation, alcohol is brewed directly from sugar cane juice, while in molasses fermentation, the brewer produces sugar and obtains molasses as a byproduct of the sugar. This molasses is then fermented and distilled to obtain alcohol. Carbon dioxide gas is generated during the main fermentation step and its increasing amount causes intense foaming, which is inherent in the nature of the raw material being processed and the yeast used. In some cases defoamer must be used as foam will overflow from the fermentation tank. Foaming is one of the major problems in sugarcane fermentation. At its most benign, foaming causes only a minor handling inconvenience; at its worst, it can contaminate the entire operation and cause product loss. This kind of foaming is a familiar problem for most fermentation engineers, but
Countermeasures vary depending on the fermentation method. These range from purely empirical attempts to add the most readily available antifoam to extensive investigations into potential causes and complete systematic studies of effective control methods. There is. So often that empirical trials are employed and the problem of foaming is viewed as peripheral to the overall process. Problems caused by foaming can be broadly divided into two types.
One problem is caused by the presence of foam inside the fermenter, and the other problem is caused by the foam leaking out if uncontrolled. In the former case, the most obvious disadvantage is probably the space taken up by the foam, which reduces the volume of mash allowed and leads to a reduction in yield. In the case of very difficult to process and rapidly forming foams, a further disadvantage is that restrictions are also placed on the maximum permissible speeds of aeration and agitation, thus limiting the oxygen transfer rate (hereinafter referred to as oxygen transfer rate).
(OTR) will be restricted. Further obstruction of ventilation causes stagnation and recirculation of air bubbles. Short-term stagnation increases OTR, but
Prolonged stagnation causes oxygen depletion and reduces OTR. The most direct consequence of foam leakage is a wetting effect on the outlet air filter and pipes, exposing other areas to the risk of subsequent contamination. Further significant adverse effects occur due to froth flotation and foam separation. The above two phenomena are superficially very similar, and it is not necessarily understood that they are fundamentally different. Foam separation refers to the selective adsorption of solutes at gas-liquid interfaces and can occur in pure solutions free of suspended particles. Foam flotation is the tendency of fine solids to rise out of the bulk solution and into the foam layer during the aeration operation. Both of these phenomena can occur simultaneously, so that the fermentation foam leads to an enrichment of solids and surfactant concentrations. Both foam flotation and foam separation are particularly problematic in continuous fermentation processes, where steady state conditions are achieved by the removal of foam enriched with cells and nutrients.
This is because the conditions) are disturbed. Pumping the foam medium between stages in a multi-stage continuous process is also difficult. The large number of cell membranes in contact with the pipe walls create extremely high resistance forces, which must be operated at pressures several times higher than those required to pump liquids. In molasses fermentation, the foam is soft, light and intense. This type of foam can be easily extinguished and suppressed with conventional antifoam agents. On the other hand, the foam produced in the direct fermentation method is heavy, compact, and bulky. In the method described above, foam is generated during charging into the fermenter. So far, not a single product has been certified as passing. The reasons for this are the large quantities of foam control compositions that must be used, the high costs, and the technical difficulties associated with the application of foam control compositions. Because of these problems, many sugar millers have used water and steam or steam to prevent foam overflow, but these do not prevent foam formation. In view of the many problems caused by foaming during continuous or bulk fermentation, many methods have been attempted in the past to control foaming. None of these attempts to ferment molasses, particularly direct fermentation of sugar cane, were completely successful. Relatively good results have been achieved by using antifoam or antifoam agents. Generally, antifoam agents are considered to be antifoam agents, while antifoam agents are foam reducing agents. However, since the volume and amount of foam depend to a large extent on the properties of the sugar cane used for fermentation, although the amount of antifoaming agent to be added to the foaming culture solution during fermentation can be determined in advance, it is difficult to determine it accurately. I can't. These antifoaming agents are effective when the fermentation period is short, and if the antifoaming agent is
Foam formation can be completely suppressed with just one addition. However, in operations where long-term fermentation is required due to the quality of the sugarcane, or where an excessive amount of foam is generated, antifoaming agents may be added multiple times or an undesirable large amount of antifoaming may occur. agent must be added. The use of such antifoaming agents is therefore associated with many technical difficulties. Foam inhibitors applied before foaming generally yields better results and are relatively easy to handle. However, the efficiency of controlling foaming varies greatly depending on the nature of the sugarcane in general and, in specific cases, on the residual inhibitory effect of the agents used to avoid foaming. Difficulties arise because of them. In addition to these, the general physico-chemical conditions of antifoam agents include limited solubility in the foaming liquid, low surface and interfacial tension, low cohesion within the surface layer,
and rapid and efficient dispersion into the liquid with minimal agitation, which allows intimate contact of the antifoam agent to the bubble surface. Antifoam agents used in the fermentation industry must also be non-toxic to microorganisms, non-metabolic, have no effect on oxygen transfer, and be tasteless and odorless.
It should be characterized by high activity even at low concentrations, long duration of action and good cost/efficacy. If chemical foam control methods are employed, the range of effective products ranges considerably from silicones to traditional formulations based on raw or partially oxidized animal and vegetable oils and other natural products. An obstacle in selecting a suitable one among them is the lack of reference data. Due to our inadequate knowledge of anti-foam properties, some of the above products were developed for other purposes and later discovered to have anti-foam properties. There are some things. Therefore, even manufacturers are unable to provide much data other than toxicity, effective concentration under given conditions, and typical physico-chemical properties. Organic antifoaming agents exhibit good foam suppression properties, but their activity gradually decreases with the passage of processing time. One known good anti-foam agent is Nalco 61-
There is a product sold under the name "G-10". This antifoam agent exhibits good foam suppression properties, but in addition to a gradual decrease in activity over processing time, the odor and greasy appearance of the mineral oil component are undesirable, and the use of this product may cause problems in tanks, pumps, etc. The drawback is that it is difficult to keep the parts of the device clean. To date, no products are known which can achieve completely satisfactory results in treating the heavy, tight, bulky foam produced by direct fermentation of sugar cane. Substantial improvements have been obtained by using silicone foam control agents with desirable physico-chemical properties. Although these desirable properties can be obtained by combining hydrophobic and hydrophilic moieties, the above-mentioned difficulties are not completely overcome. The object of the present invention is to provide a composition for foam control,
The aim is thereby to overcome the problems and difficulties mentioned above. Another object of the present invention is to provide a foam control composition for controlling foaming in alcohol brewing processes from sugar cane, namely direct fermentation processes and molasses fermentation processes. The present invention relates to foam control compositions consisting essentially of polydimethylsiloxane, a silica compound, a polyoxypropylene polymer, certain nonionic surfactants as shown below, and certain dispersants as shown below. More particularly, this composition is used for the purpose of controlling foaming in alcohol brewing processes from sugar cane. The present invention comprises: (A) a liquid polydimethylsiloxane having a viscosity of at least 20 mm ² /S at 25°C; (B) a silica compound; (C) a polyoxypropylene polymer having an average molecular weight within the range of about 1000 to 6000. D) A non-containing material selected from the group consisting of (a) polyoxyethylene octylphenol containing 10 polyoxyethylene units, (b) an alkyl ether of a polyoxyethylene polymer, and (c) an alkylaryl ether of a polyoxyethylene polymer. an ionic surfactant, and (E) (i) a small proportion of a siloxane resin consisting of (i) SiO ₂ units and (CH ₃ ) ₃ SiO _1/2 units; and (ii) ethylene oxide and propylene. reaction product with a large proportion of propylene oxide/ethylene oxide copolymer containing approximately equal parts of oxide and having an average molecular weight of 6000 to 6500; and (b)(i)
a dispersant selected from the group consisting of a reaction product of a minor amount of a siloxane resin composed of SiO ₂ units and (CH ₃ ) ₃ SiO _1/2 units and (ii) a major amount of propylene glycol; A composition for foam control consisting essentially of: Optionally, the compositions defined above and the foam control compositions include (F)SiO ₂ units and (CH ₃ ) ₃ SiO _1/2
A siloxane resin composed of units and units can also be included. Component (A) has a viscosity at 25°C of at least 20
mm ² /S liquid polydimethylsiloxane. Although this lower limit appears to be critical, the upper value can range quite widely, up to 1,000,000 mm ² /S or more. However, for best results, the viscosity at 25°C should be between 20 and 2000 mm ² /S.
It is desirable that it be within the range of . Although the polydimethylsiloxane end block is not a critical element, it is preferred that the end groups be selected from the group consisting of trimethyloxy and hydroxy groups. Furthermore, it is desirable that the foam control composition contains from 0.4042 to 10.105% by weight of composition (A). These liquid polydimethylsiloxanes are well known commercial products available from numerous manufacturers. These siloxanes can be produced by various methods, such as hydrolyzing dimethyldihalosilane and then condensing it, or cracking dimethylcyclosilane and then condensing it. Component (B) is a silica compound. Preferably, component (B) is selected from the group consisting of precipitated silica, silica aerosol, silica xerogel, fumed silica, and treated silica having organosilyl groups on the surface. Preferably, component (B) is a precipitated silica. Furthermore, it is desirable that the foam control composition contains 0.0215 to 0.5375% by weight of component (B). Silica aerosol is also a type of silica suitable for use in foam control compositions. In summary, this type of material uses a low-boiling organic liquid, such as ethyl alcohol, to drive water out of a silica hydrogel.
produced by heating the treated gel in an autoclave to near the critical temperature of the organic liquid and then releasing the vapor of the organic liquid from the autoclave, thereby avoiding excessive shrinkage and crushing of the silica. . Details of this technique are described in the literature and silica aerosols are commercially available. Other silica sols, including silica aerosols, that may be used are well known and will be apparent to those skilled in the art. Component (C) is a polyoxypropylene polymer having an average molecular weight within the range of about 1000-6000. In addition, component (C) is an average of a polyoxypropylene polymer having an average molecular weight of about 2000, a polyoxypropylene polymer having an average molecular weight of about 2000 or less, and a polyoxypropylene polymer having an average molecular weight of about 4000 or more. More preferably, it is selected from the group consisting of a mixture of molecular weights ranging from 1500 to 4500. A portion of the polyoxypropylene polymer can be replaced by a polyoxypropylene/polyoxyethylene copolymer. More preferably, component (C) is a xylene solution of a polyoxypropylene polymer. 86.46~ for foam control compositions
More preferably, it contains 99.4584% by weight of component (C). These polyoxypropylene polymers are commercially available from many manufacturers and are [CH ₂ CH
(CH ₃ )O] units. The terminal termination groups of these polymers may be methyl, ethyl or propyl groups. The terminal group is not critical for the purposes of the invention. However, the commercially available products are hydroxyl-terminated and are known to those skilled in the art by the erroneous name "propylene glycol", whether monool, diol, triol or polyol. I would like to point out that. Component (D) is a specific nonionic surfactant. The nonionic surfactant is selected from the group consisting of polyoxyethylene octylphenol containing 10 polyoxyethylene units, alkyl ethers of polyoxyethylene polymers, and alkylaryl ethers of polyoxypropylene polymers. Preferably, component (D) is polyoxyethylene octylphenol having 10 polyoxyethylene units. It is also desirable that the foam control composition contains 0.035 to 0.875% by weight of component (D). Component (E) is a specific dispersant. The purpose of the dispersant is to provide compatibility between the components contained within the foam control system. Component (E) consists of (1) a small proportion, preferably about 25% by weight, of a siloxane resin consisting of SiO ₂ units and (CH ₃ ) ₃ SiO _1/2 units, and approximately equivalent amounts of ethylene oxide and propylene oxide. a large proportion, preferably about 75% by weight, of a reaction product with a propylene oxide/ethylene oxide based copolymer having an average molecular weight of about 6000-6500, and (2) SiO ₂ units and (CH ₃ ) ₃ a minor amount, preferably about 36% by weight, of a siloxane resin, and a major amount, preferably about 64% by weight, of SiO _1/2 units;
reaction products with propylene glycol. In addition, SiO ₂ units (CH ₃ ) ₃ SiO _1/2 of the siloxane resin used in component (E)
It is desirable that the unit ratio is within the range of 1:0.6 to 1:1.2. In addition, component (E) is 25 to 33.33% by weight.
Preferably, it consists essentially of reaction product (1) and 66.67 to 75% by weight of reaction product (2). Optimally, the foam control composition contains from 0.0746 to 1.865% by weight of component (E). If desired, component (F), which is a siloxane resin composed of SiO ₂ units and (CH ₃ ) ₃ SiO _1/2 units, may be included in the foam control composition. The ratio of SiO ₂ units to (CH ₃ ) ₃ SiO _1/2 units in the siloxane resin is preferably in the range of 1:0.6 to 1:1.2. Optimally, the foam control composition contains from 0.0063 to 0.1575% by weight of component (F). This siloxane resin is a standard commercial product available from many manufacturers. This can be obtained by co-hydrolyzing and condensing (CH ₃ ) ₃ SiCl and SiCl ₄ or by co-hydrolyzing and condensing (CH ₃ ) ₃ SiCl
and acidic silica sol. The manufacturing method for this product has been described in detail in various documents, so I will not repeat it here. If desired, the foam control composition may also include xylene. However, the antifoam or antifoam activity of the overall composition is not thereby improved. As far as we know at this time, the order in which the components are mixed is not critical, as long as the correct proportions are maintained. In addition, this foam control composition has a content of 75 to 99% by weight.
of polyoxypropylene polymer and 1 to 25% by weight of components A, B, C, D, E and F [with the exception that component (A) is about 35 to 45% by weight and component (B) is about 0.5 to 5% by weight. %, component (C) is approximately 40-50% by weight, component (D) is approximately 1-5%
% by weight, component (E) in an amount of about 2-6% by weight, and component (F) in an amount of about 0-0.5% by weight, respectively. The effective amount of the compositions of this invention will depend on the particular system in which foam is to be controlled and the degree of control desired. Although the compositions of the present invention can be used for foam control in a variety of systems where foam is a problem, they are designed to be particularly useful in processes for obtaining alcohol from sugar cane. The compositions of the present invention can be utilized as any kind of foam control agent, ie as defoamers and/or antifoam agents. Antifoaming agents are generally thought of as foam reducing agents.
On the other hand, antifoaming agents are generally thought of as antifoaming agents. As described above, the composition of the present invention is useful as either of these, and also has the capabilities of both. The foam control compositions of the present invention have low surface and interfacial tension, low cohesion to surface layers, and other physico-chemical properties desirable for antifoam and antifoam agents. These materials disperse rapidly and efficiently and come into intimate contact with the surface bubble layer with minimal agitation. Furthermore, the compositions of the invention are harmless to microorganisms, mass metabolism and oxygen transfer and are therefore particularly suitable for use in the fermentation of sugar cane or molasses.
Besides this, these compositions are free of unpleasant odors and tastes and maintain a high degree of activity for a long time at low concentrations, so that a satisfactory anti-foaming effect is achieved. In addition, considering that the high activity remains for a long time, a defoaming effect is also achieved at the same time. That is, the presence of the above substance not only suppresses foaming during the fermentation process, but also suppresses all foam generated. It is believed that the hydrophobic component, siloxane, provides low surface tension and non-dissolving properties, while the silica and polyoxypropylene polymer provide good dispersibility, ie, hydrophilicity. EXAMPLES Hereinafter, examples will be described in order to explain the embodiments of the present invention more clearly to those skilled in the art, but these examples are for the purpose of explanation and are not intended to limit the present invention. Unless otherwise specified, parts and percentages in the examples are by weight;
In addition, all viscosities are measured values at 25°C. The foam control compositions tested in the following examples were as follows: The composition contained 8.084% by weight Component (A), 0.43% by weight Component (B), and 89.168% by weight Component (C). , 0.70% by weight component (D), 0.766% by weight component (E), 0.0645% by weight component (F), 0.7875% by weight xylene, and the composition consists essentially of 2.021% by weight component ( A), 0.1075% by weight ingredient (B), 97.292% by weight ingredient (C), 0.175% by weight ingredient (D), 0.16625% by weight ingredient (E), 0.016125% by weight ingredient (F), 0.196875% by weight % of xylene, and the above middle component (A) is
It has a viscosity of 1000 mm ² /S at 25°C, component (B) is a precipitated silica, component (C) has a molecular weight of 2000 and component (D) is a polyester containing 10 polyoxyethylene units. oxyethylene octylphenol and component (E) is 34.73% by weight of the reaction product (1)
and 65.27% by weight of reaction product (2). In the examples below, the amount of antifoam used relative to the tank volume is shown along with the Brix and temperature measurements. The Brix reading is the weight concentration of sugar measured using a Brix meter. A Brix meter is a floating scale type hydrometer used for sugar solutions, and has a scale so that it can be read in degrees. The degree of Brix at a specified temperature represents the weight percentage of sugar contained in the solution. In the following examples, compositions and compositions that are clean, non-toxic, non-flammable, non-slag-free, provide minimal carbon dioxide emissions, and therefore minimize alcohol loss, are used in conventional anti-foam formulations. agents such as Drew L-900 and Degani antifoam agents.
Antifoam) 4011 was added to molasses fermentation liquor and sugar cane direct fermentation liquor with good results. To date, none of the prior art anti-foam agents has been able to suppress the foam produced by direct fermentation of sugar cane, as the foam is heavy, tight, and bulky. Example 1 We have 10 tanks with a capacity of 200,000 each, and
A mixture of molasses and sugar cane was used to test the composition as an anti-foaming agent in an alcohol manufacturing plant producing 110,000 ml of alcohol.

[Table] Commercial products Dorieux L-900 and Deganey antifoaming agent
Although good results are not obtained with 4011, good results are obtained with compositions and. Example 2 In an alcohol factory producing 141,000 units of alcohol per day in 10 tanks each with a capacity of 200,000 units, the composition was tested using decanted sugarcane juice and a gentle foam formed.

EXAMPLE 3 A composition was tested for its efficiency as a foam preventer using a direct fermentation method producing 120,000 ml/day of alcohol in an apparatus consisting of 11 tanks of 225,000 ml each.

[Table] When using other known antifoaming agents in this device, good results have never been obtained. Example 4 In an apparatus consisting of 9 tanks of 150,000 capacity each, which produce 100,000 units of alcohol per day using molasses fermentation, experiments were conducted using the compositions and, and the results were as follows.

[Table] Example 5 Consisting of 11 tanks of 100,000 each and 10 tanks of 150,000 each, Nissan
In a device that produces 150,000 alcohol,
The following results were obtained using the following compositions.

[Table] In this device, sulfonated coconut oil and pressurized steam were used instead of an antifoaming agent. The composition and consistently demonstrated good efficacy. Example 6 Consists of 11 tanks with a capacity of 150,000 each, using a mixture of 90% sugar cane juice and 10% molasses as raw material.
In an apparatus producing 100,000/day of alcohol, the following results were obtained using the composition and as an antifoaming agent.

[Table] No dregs remained with the composition, but dregs remained with Dorieux L-900. Example 7 Consisting of 8 tanks with a capacity of 150,000 yen each, using a mixture of sugarcane juice and molasses as raw material, 90,000 yen
The results of operating the composition and in an apparatus for producing alcohol for 1 day were as follows.

[Table] Drieux L-900 requires 1.5 parts of product per tank to control foaming, whereas compositions and formulations can control foaming with less than 500 ml. Example 8 In a device consisting of 11 tanks each with a capacity of 200,000 ml, which produces 120,000 ml of alcohol per day using sterilized sugar cane juice as raw material, the following results were obtained by using the composition and as an anti-foaming agent. .

[Table] Example 9 In a device consisting of 16 tanks each with a capacity of 200,000 and producing 200,000/day of alcohol by the direct fermentation method of sugar cane, the following results were obtained by using the composition and as an anti-foaming agent. I got it.

[Table] For proven good results, Drieux L-900
These include the fact that the composition and composition are cleaner, emit less _CO2 , and are more effective. Example 10 In a plant consisting of 11 tanks each with a capacity of 200,000 liters and producing 100,000 liters of alcohol per day by direct fermentation of sugarcane juice, the following results were obtained using the composition and.

[Table] No antifoam agents were used in this equipment, as until the use of compositions and, no satisfactory results had been achieved with the products tested.

Claims (1)

[Claims] 1 (A) Viscosity at 25°C is at least 20 mm ² /S
(B) a silica compound; (C) a polyoxypropylene polymer having an average molecular weight within the range of 1000 to 6000; (D) (a) a polyoxyethylene containing 10 polyoxyethylene units; a nonionic surfactant selected from the group consisting of octylphenol, (b) alkyl ether of polyoxyethylene polymer, and (c) alkylaryl ether of polyoxyethylene polymer, and (E) (b) (i) A small proportion of siloxane resin composed of SiO ₂ units and (CH ₃ ) ₃ SiO _1/2 units, and (ii) ethylene oxide and propylene oxide are contained in approximately equal parts, and the average molecular weight is 6000 to 6500. Reaction products with a large proportion of propylene oxide/ethylene oxide copolymers and (b)(i)
a dispersant selected from the group consisting of a reaction product of a minor amount of a siloxane resin composed of SiO ₂ units and (CH ₃ ) ₃ SiO _1/2 units and (ii) a major amount of propylene glycol; A foam control composition consisting essentially of: