US2575298A

US2575298A - Steam generation and compositions for inhibiting foaming

Info

Publication number: US2575298A
Application number: US4458A
Authority: US
Inventors: John W Ryznar
Original assignee: National Aluminate Corp
Current assignee: ChampionX LLC
Priority date: 1948-01-26
Filing date: 1948-01-26
Publication date: 1951-11-13
Anticipated expiration: 1968-11-13

Description

Patented Nov. 13, 195E STEAM GENERATION AND COMPOSITIONS FOR INHIBITING FOAIVIIN G John W. Ryznar, La Grange Park, Ill., assignor to National Aluminate Corporation, Chicago, 111., a. corporation of Delaware No Drawing. Application January 26, 1948, Serial No. 4,458

18 Claims. (01. 252321) The present invention relates to improved antifoaming compositions which are added to water that is subjected to boiling, as in the boilers of locomotives, stationary steam generators, evaporators, and in other instances where the boiling of water occurs, especially under superatmospheric temperature and pressure conditions, whereby the tendency of the water therein to foam is prevented or reduced and the boiling characteristics of the water so improved that priming of the steam generator and carryover of boiler water with the steam therefrom is prevented.

It is well known that in the operation of steam boilers, such as in railroad locomotives, in electric power plants and the like, or in other boiling operations where steam is formed, as for example in evaporators, that the water therein, even though initially it shows little tendency to foam, will, when the amount of total dissolved solids approaches a relatively high concentration due to the production of steam, develop a very decided tendency to foam. This foaming of the water in a. boiler producing steam is characterized not only by an accumulation'of relatively stable froth or foam on the surface of the boiler water but also by the formation at the heat transfer surfaces in the boiler of extremely small steam bubbles. These minute bubbles show almost no tendency to coalesce and the result is that the entire volume of water in the steam generattor is lifted in the form of so-called light water, which is actually an intimate mixture of boiler water and tiny steam bubbles. When this occurs, considerable quantities of boiler water are physically carried out of the boilers or evaporators with the steam,

thereby introducing solid matter into the steam lines and into the eventual condensate. Such carryover has many disadvantages because it tends to contaminate and restrict the steam lines, to plug or corrode the valves, to deposit on turbine blades, to plug and cause burning out of superheater tubes, and under serious conditions may even impair the cylinders and piston rods of steam engines or otherwise render the steam unfit for use. The carryover is frequently due in part, at

least, to priming, or what may be described as surging or boiling over of the water.

Attempts have been made in the past to control foaming and priming by controlling the dissolved solids content of the water as by excessive blow-down of the boilers, that is, the removal, either continuously or periodically, of a portion of the boiler water containing the undesired ex cess solids. Also, it has been common to add materials for the purpose of abating the foam as by the injection of such materials as castor oil. tallow, and the like. While these fatty materials, notably castor oil, have some small degree of efiiciency, they are, on the other hand, quite deficient in that they introduce new difliculties which, in some instances, are worse than the conditions they are intended to cure. In the first place, these fatty materials or glycerides are very unstable under severe hydrolytic conditions encountered in steam generation, particularly under the conditions of superatmospheric pressure, the corresponding high temperatures and the alkalinity of the boiler water. The resultant decomposition products which remain in the boiler tend to increase the foaming tendencies of the boiler water and to accumulate in such a way as to give a compound dirty boiler, necessitating frequent washing. Furthermore, in many instances certain of the decomposition products thus produced, or sometimes even the materials themselves, have a definite volatility with steam and will, therefore, steam-distil out of the steam generators, thus appearing in the steam and in the eventual condensate. This, of course, is also undesirable. Additionally, such types of antifoaming agents usually are of'such a low order of efficiency that they have to be employed in relatively large quantities, adding not only to the expense but also to the inconvenience of operating the steam generators; and since they are so unstable their effectiveness is of short duration, necessitating the continual charging into the boilers or other steam generators of relatively large amounts of these older antifoaming agents.

The most noteworthy advance over the use of the fatty glycerides described above was the discovery and development of certain high molecular weight substituted polyamides, which antifoaming compounds overcame many of the disadvantages of the former, especially in that they were highly eflicient at lower dosage levels and much more resistant to decomposition, so that their effective life was relatively greater.

One of the objects of this invention is to provide a new and improved process for preventing the foaming and priming of steam generators, thus improving the quality of the steam produced thereby.

Another object is to provide new and improved compositions for adding to the water in a steam generator to prevent or reduceits tendency to foam.

Another object is to provide antifoaming coming temperatures. Still another object of the invention is to propositions which are eflective to prevent foaming when used in very low dosages.

A further object is to provide highTy effective antifoam compositions which are readily and easily dispersible when added to the feed water vide a process of generating steam and new and improved antifoam compositions therefor wherein the period of eflectiveness of the antifoam composition isgreatly prolonged as compared to the period of effectiveness of other antifoam compositions presently known in the art.

I Still another object of the invention is to provide a new and improved process of inhibiting foaming during steam generation which permits operations at higher dissolved solids contents than has heretofore been considered possible.

An additional object is to provide new and useful antifoaming compositions of an extremely high order of resistance to decompositionunder the conditions prevailing in steam generation. Other objects will appear hereinafter.

In accordance with this invention. it has now been discovered that there is a series of compounds, which may be broadly designated as high molecular weight monoethers of polyoxyalkylene glycols, that are very effective when used as antifoaming and antipriming agents in steam generators. These ether alcohols possess several important advantages over formerly known antifoam compositions. They are all much more effective than any of the fatty glycerides, and many are more effective than any hitherto known materials. Furthermore. they are much more stable to decomposition under conditions of use than any of the glycerides or polyamides, thus giving them a greatly prolonged period of effectiveness in preventing foaming. In general, they are more readily dispersed in the water being fed to the steam generator than are older materials, and a further advantage offered by many of these ether alcohols is that they are liquids or very low-melting waxy materials which are readily soluble at ordinary temperatures.

The preferred ether alcohols employed in the practice of this invention may be represented by the structural formula wherein R is an alkyl radical, n is 2 or 3 or may have both values, and :c is an integer of approximately 8 or larger. Such compounds are thus seen to include onoethers of polyoxyalkylene glycols includin polyoxyethylene glycols, polyoxypropylene glycols and polyoxyalkylene glycols in which the alkylene groups include both ethylene and propylene in any proportion and in a random or irregular sequence, with respect to each other, in the polyoxyalkylene chain.

In order that these monoethers of polyoxyalkylene glycols possess the property of efliciently preventing the foaming and priming of steam generators, they should be of relatively high molecular weight and, while the lower limiting value of molecular weight will vary both with the size of the terminal ether group and with the ratio of ethylene to propylene groups in thepolyoxyalkylene chain, it will, in general, be in the neighborhood of approximately 1500 when the terminal ether group 6 is a methoxy or an ethoxy group, and approximately 500 when the terminal ether group contains 12 to 18 carbon atoms or more. When the number of carbon atoms in the terminal ethergroup is intermediate between 2 and lzcarbon atoms, the lower limiting value of the molecular weight, in order to obtainemcient antifoam inhibition, will be intermediate between 500 and 1500.

Generally stated, therefore, it may be said that the ether alcohols employed for the purpose of this invention may be characterized as having a total molecular weight of at least 500 and containing a polyoxyalkylene group having different terminal groups connected to diiferent terminal 20 carbon atoms one of said terminal groups being a hydroxy group and the other being an ether group. The foam inhibiting compounds employed for the purpose of the invention may also be described as being non-ionic in that they do 5 not contain ionizable groups such as carboxy or sulfonic groups.

Although, as will be described more fully'hereinafter, the ether alcohols employed in accordance with this invention may be prepared by a variety of syntheticroutes, and from a variety of reactants, the group attached to the terminal ether oxygen may be considered as derived from a monohydroxy alcohol or a monobasic phenol. Suitable alcohols and phenols are the simple alkanol suchas methanol, ethanol, propanol, isopropanol, the butanols up to higher members such as cetyl alcohol, octadecanol; alicyclic alcohols, e. g., cyclohexanol; phenols, e. g., phenol, cresol; and aralkyl alcohols, e. g., benzyl alcohol.

Other suitable alcohols and phenols are the cor-- responding monohydroxy alcohols and monobasic phenols substituted in the hydrocarbon chain or the aromatic ring by groups not possessing acidic hydrogen, common examples of such substituents being halogeno (e. g., chlorine, bromine, iodine and fluorine), nitro, cyano, alkyl (e. g., methyl, ethyl and higher homologues), and alkoxy (e. g., methoxy, ethoxy and higher homologues) but not hydroxy, carboxy, or sulfonic groups.

Specific examples of ethers of polyoxyalkylene glycols suitable for the practice of this invention include (1) the mono-cetyl ether of a polyoxyethylene glycol of average molecular weight 400 (molecular weight of the cetyl ether=640) (2) 5 "UCON lubricant 50-I-1B-3520" which is substantially the mono-butyl ether of a mixed ethylenepropylene polyoxyalkylene glycol in which the weight ratio of ethylene oxide to 1,2-propylene oxide is 1:1 and inwhich the total molecular weight of the butyl derivative is about 3500 or greater as determined by calculation from data obtained by the method of Menzies and Wright (Journal American Chemical Society, volume 43,

pp. 2309 to 2314) and by acetyl determination and for which the viscosity at 100 degrees F. is 3520 Saybolt seconds (S. U. S.) and (3) UCON lubricant LB-1145 which is substantially the monobutyl ether of a polyoxypropylene glycol of such size that the average molecular weight is approximately 1700 by the method of Menzies (Journal American Chemical Society, volume 32,.

pp. 1615-1624) and the viscosity at 100 degrees F. is 1145 S. U. S. (Saybolt Universal seconds).

The compounds employed in accordance with this invention may be prepared in several ways.

I Thus, the desired alkylene oxide (ethylene oxide hol, R is Hor CH3, and y is a whole number. This is a well known type of reaction and has been described in U. S. Patent 1,633,927. For the case where a mixture of ethylene oxide and propylene is used, the reaction may be represented by the equation wherein ROH is an aliphatic monohydroxy alcohol; y and 2 represent the moles of ethylene oxide and 1,2-propylene oxide respectively; n is both 2 and 3 in a single molecule, the total number of times n has a value of 2 being equal to y and the total number of times n has a value of 3 being equal to z; and a: is the total number of such oxyalkylene groups, being equal to y+2. Methods of effecting this reaction with the mixed oxides and the resultant compositions have been described in U. S. Patent 2,425,755. Certain modifications of this general reaction may be employed'to produce compositions for the practice of the present invention, e. g., in place of the aliphatic monohydroxy alcohol (ROH) the alkylene oxide or mixed oxides may be reacted with a polyoxyalkylene monohydroxy alcohol prepared by this or some other route, to result in a product of the same chemical nature but of increased molecular weight because of the increased length of the polyoxyalkylene chain.

Another way in which the same class of products may be prepared is to efiect the reaction of an alkyl or aryl halide with an alkali metal alcoholate. Much work on this general preparative scheme has been done by Hibbert and his co-workers (see e. g., Journal American Chemical Society, volume 61, p. 1905). The two equations given below illustrate the reaction involved.

In these equations, R represents alkyl, aralkyl, aryl or cycloalkyl, a: is a whole number, and X is halogen, e. g., chlorine or bromine. For convenience, polyoxyethylene glycols and polyoxyproplene glycols have been used for illustration, but it will be understood that polyoxyalkylene glycols containing both ethylene oxide and propylene oxide will undergo the same type of reaction.

Since, as indicated above, it is possible to prepare the ether alcohols of this invention by various routes, the invention should not be limited by the following examples, which are merely intended to illustrate some satisfactory procedures for preparing a few of the materials suitable for employment within the scope of the present invention.

Example I n A solution of sodium methylate in methanol was prepared by dissolving 4.6 grams (0.20 atom) of sodium in 50 milliliters of absolute methanol. To this was added 87 grams (0.21 mole) of a poly oxyethylene glycol of approximate average molecular weight 414 (substantially nonaoxyethylene glycol) and the methanol removed by distillation under reduced pressure. To the resulting monosodium salt of the glycol was added, at to degrees C. with stirring, 61 grams (0.20 mole) of cetyl bromide and the reaction mixture stirred at this temperature for about 16 hours when a test for alkali to'phenolphthalein was negative. The product was filtered hot to free it of sodium bromide. When cool, the product, which was substantially the monocetyl ether of the glycol, was a grease of butter-like consistency which was fairly easy to disperse in water.

Example II Using the procedure of Example I and 1.5 grams of sodium, 15 milliliters of methanol, 26.1 grams of a polyoxyethylene glycol of average molecular weight 400 (substantially nonaoxyethylene glycol) and 13.9 grams of dodecyl chloride, a clear liquid product consisting mainly of the monolauryl ether of the glycol was obtained. This product was soluble in cold water and dispersible in hot water.

Example III Using the procedure of Example I and 0.46 gram of sodium, 25 ml. of methanol, 25.3 grams of a polyoxypropylene glycol of average molecular weight 1200, and 6.7 grams of cetyl bromide, the monocetyl ether of the glycol was prepared and found to be a clear, viscous liquid, substantially insoluble in water.

Example IV Example V Using the procedure of Example I and 0.46 gram 0 of sodium, 25 ml. of methanol, 25.3 grams of the Example VI Using the procedure of Example I and 0.86 gram of sodium, 25 ml. of methanol, 15.0 grams of a polyoxypropylene glycol of average molecular weight 400, and 12 grams of cetyl bromide, the monocetyl ether of the glycol was obtained as a water insoluble liquid.

Example VII Example VIII Using the procedure of Example I and 0.575 g. of sodium, 25 ml. of methanol, 30 g. of a polyoxypropylene glycol of average molecular weight 1200, and 3.26 g. of cyelohexyl chloride, the monocyclohexyl ether of the glycol was obtained as a water insoluble liquid.

Example IX Using the procedure of Example I and 0.575 g.

75 of sodium, 25 ml. of methanol, 30 g. of a polyoxyliquids or low-melting wax-like solids; and may be entirely soluble in cold water or only partially soluble. In the latter case, they are relatively easily dispersed in the feedwater by means of additional dispersing agents, as described below.

boiler by evaporation at the rate of six gallons per hour at 250 pounds persquare inch (p. s. 1.) gauge pressure. A continual recording wasmade of the relative conductivity of the condensate from the boiler, and continual observations were made of the character of the boiling andthe All of the products exhibitsubstantial insolubility in hot water, the phenomenon of decreasing solubility in water with increasing temperature being characteristic. of compounds of this class which contain multiple ether linkages and in which theratio of ether linkages to carbon is suiilciently greatto permit the weak hydrogen bonding eifect of the ether oxygen to confer water solubility.

The amounts of an antifoam agent employed in inhibiting the foaming of water in a steam generator will depend upon several factors, among them the per cent of solids in the foaming liquid, the nature of the solids, the alkalinity, temperature, and pressure, the type and degree of circulation in the steam generator, the rate of steam production, and the amount of foam suppression desired. It is, therefore, impossible to state any rigid rules for estimating the amount of an antifoam which needs to be used. The amounts of the ether alcohols of this invention which are required are, however, extremely small. For many purposes, amounts of the order of 0.01 grain per gallon to 0.02 grain per gallon in the feedwater are suflicient, and under certain conditions quantities as low as 0.001 grain per gallon in the feedwater have proved effective. In general, it can be said that quantities greater than 0.1 grain per gallon in the feedwater would seldom be required.

By way of illustrating the remarkable effectiveness of the ether alcohols of this invention, the method of testing their antifoam efliciency in the laboratory will be described and exemplary data given and this will be followed by the results of' an actual test made on a full-scale stationary boiler. e

In the laboratory, the experimental boiler used was of the type described in the publication Solid Matter in Boiler 'Water Foaming, by

Foulk and Brill, which appeared in the periodi-- position, expressed in parts per million, by weight:

Calcium hardness (as CaCOa) 154.0 Magnesium hardness (as CaCOs) 154.0

Alkalinity (methyl orange) (as CaCO3) 726.0 Sodium chloride (as NaCl) 85.5 Sodium sulfate (as NazSO-r) 718.0 Tannin extract, dry 34.2

To this feedwater was added the antifoam composition of the character and in the quantity specified in the specific experiment, and this water was then gradually concentrated in the test amount of foaming as seen through the sight glasses. When the antifoam thus introduced continuously with the feedwater was no longer able to overcome the foaming tendencies brought about by the concentration of dissolved solids in the boiler water, the foam height became great enough to cause boiler water to be carried out of the boiler with the steam, and this endpoint of the test was determined both by observation through the sight glasses, and particularly, by the abrupt increase in the'conductivity of the steam, as shown in the continuous recorder. At this end-point, a sample of the boiler water was withdrawn from the boiler and analyzed, and the eflectiveness of the antifoam expressed in terms of theltotal dissolved solids concentration which it permitted the boiler to carry. A high value of total dissolved solids (TDS) indicates an effective antifoam. With no antifoam, this feedwater gives a carryover at a total dissolved solids value of approximately 1'75 grains per gallon.

Test I This material was completely soluble in the-feed-' water at room temperature, and was dissolved in the feedwater at a dosage'of 0.043 part per million, by weight. Carryover did not occur until the total dissolved solids in the boiler wate had reached 4000 grains per gallon.

. Test II v The product of Example I as intimately mixed,

by grinding, with a dry, pulverized lignin derivative commonly used in boiler water treatment, and made by desulfonation and partial depolymerization of sodium lignin sulfonate by treatment with aqueous alkali at high temperatures. This material exhibits an excellent dispersing effect on the polyether alcohols but exerts no antifoam effect per se. The resulting dry-appearing pulverized composition, containing three parts by weight of the product of Example I and 97 parts of the lignin derivative, was added to the feedwater at a dosageof 2.86 P. P. M., resulting in a concentration of the polyether alcohol of 0.0855 P. P. M. in the feed water. This permitted a total dissolved solids concentration in the boiler of 887 grains per gallon before carryover occurred.

Test III The antifoam used in this experiment was "UCON lubricant 50-HB-3520, which is the monobutyl ether of a polyoxyalkylene glycol containing ethylene oxide and propylene oxide in a weight ratio of 1:1, and having a total average molecular weight of approximately 3500. This product was completely soluble in the feedwater at room temperature and was dissolved at a dos- 9. age of 0.043 P. P. M. in the feedwater. This permitted a total dissolved solids concentration in the boiler water of 1955 grains per gallon before carryover occurred.

Test IV The antifoam used in this test was UCON lubricant LIB-1145 which is the monobutyl ether of a polyoxypropylene' glycol of average molecular weight of approximately 1700, as determined by the method of Menzies. It was dispersed in the feedwater at a dosage of 0.17 P. P. M. by

' adding it in the form of an ethanolsolution of such concentration that'approximately 1 milliliter of the ethanol solution was required per gallon of feedwater. Ethanol added alone in this quantity has no eflect upon the test. The ether alcohol thus employed permitted a dissolved solids concentration of 1046 grains per gallon in the boiler water before carryover occurred.

As an example of the practice of this invention on a large scale, a carefully controlled test was carried out at a large industrial plant. The

boiler on which the test was run was a Foster 'Wheeler Type A boiler, fired by gas, operated .at 225 pounds per square inch gauge, and having a capacity of 70,000 pounds of steam per hour. The feedwater used was drawn from a large sanitary canal after which it was softened in a conventional hot-process lime soda softener, followed by a phosphate softener and filtration. The feedwater showed the following analy- The quality of thesteam produced 'by'lth e boil;

er during all the. runs -co m pri f H continuously recorded by a. Leed s an I. Qr'th Micromax strip condu ivity ree der,l-5O

cromho range. The first run was n e eabove feed water with no antifoam added to it. The blowdown valves were closed and the solids in the boiler water allowed to concentrate until carryover occurred. At carryover, a sample of the boiler water showed the total dissolved solids to. be 125 grains per gallon.

Another run was made in the same manner per gallon no carryover had occurred. The load on the: boiler .was then swung sharply up and ownn aneffort to cause carryover, but the sis:

.Total dissolved solids grains/gallon 23.5 Total hardness (as CaCOa) do 0.0 Phenolphthalein alkalinity (as CaCOa) do 3.3 Total alkalinity (methyl orange) e e (as CaCOz) "seq.-- 6.0 Free carbon dioxide (as CaCO d0 0.0 Chloride (as NaCl) do 6.1 Sulfate (as Na2SO4) do 6.8 Iron (as Fe in P. P. M.) ..P P..M 0.2 pH 10.15

While many of the ether alcohols employed in accordance with this invention are readily soluble in cold water, others are not completely soluble and must be rendered readily dispersible for use. Liquids, waxes, and preformed emulsions are inconvenient to apply to the feedwaters used by locomotives and other power plants. It is thus a further object of this invention to provide the ether alcohols compounded with other water treating chemicals in a powdered or briquetted form which can readily and conveniently be added to water, and which will disperse in the water quickly without excessive agitation or mixing.

The ether alcohols employed in the practice of this invention can all be incorporated into dry powdered materials such as powdered tannin, sodium lignin sulfonate, the desulfonated lignin described in Test II hereinabove, soda ash, various orthophosphates and polyphosphates. Depending somewhat upon the powdered absorbent selected, amounts of the ether alcohols of the order of 5 to 10% of the total composition may be readily incorporated to give a dry-appearing pulverized product. By the use of suitable binders and other well-known techniques, such compositions may also be briquetted.

The resulting dry-appearing products just described are readily and completely dispersible in water when the polyether alcohols themselves are soluble or dispersible. When polyether alcohols are employed which are substantially insoluble in water, such as, for example, the products described in Examples IV and V, these, too, give dry-appearing compositions by the method de-- scribed if a dispersing agent is used in conjunction with them. In fact, many of .the common water treating chemicals of a tannin or lignin nature behave as sufiiciently powerful dispersants' be employed with good results, and the amount of soap or sulfonate thus required is insufiicient .to interfere with the powerful antifoam effect of the ether alcohols or to render the boiler compound dirty.

In general, then, the ether alcohols of this invention maybe prepared in the form of dry-apquality remained excellent. 1 The test was 1 then stomiedi without having determined how' muchfarther'thesolids might have been in- "creased.

.0negofthe-:difliculties of using. mostantifoam materials is that of conveniently ii'ntroducing them into the water in small, controlledfamounts.1'

so that their maximum efiectivenes's isfutilizedf pearing pulverized or briquetted compositions which are readily and completely dispersible in water with a minimum of agitation by incorporating them, with or without a dispersant such as soap or sulfonated oil, with various tannins, lignins, or other pulverized chemicals, either alone or in combination.

' A few examples will serve to illustrate the preparation of suitable dry-appearing, dispersible compositions.

Example A Per cent Ether alcohol described in Test I 3 Desulfonated lignin derivatives described in Test II 9'7 The liquid ether alcohol was incorporated with the dry, pulverized lignin derivative by adding the alcohol to the latter in a putty-chaser type mixer. The resultant composition was dry and free flowing and was readily dispersible in water in concentrations of 3 to 5 or greater.

The mixing was done as described in Example A, by adding the liquid to the mixed dry'solids. The resultant pulverized product was readily and completely soluble in cold water.

This composition was mixed as in Example A and, even though the ether alcohol used is substantantially water-insoluble, the dry composition obtained herein was readily and completely dispersible in water in a concentration of 3 to 5%, and the aqueous dispersion thus obtained was stable and showed no tendency for the alcohol to separate.

Example D Per cent Ether alcohol of Test IV 3 Refined tall nil 2 Desulfonated lignin derivative described in Test I I 95 The lignin derivative used herein was that obtained directly from the sulflte pulp manufacturing process after removal of the bulk of the wood sugars, converting the calcium sulfonate to the corresponding sodium salts, and drying. composition described was readily dispersible in water.

The practice of the invention is applicable to the inhibition of foaming in steam generation over a relatively wide pressure and temperature range. In lomomotive boilers, steam is generally generated at pressures around 250 pounds per square inch and the corresponding temperatures. Excellent results have been obtained with the practice of the invention at pressures within the range of 100 to 300 pounds per square inch and the corresponding temperatures. The invention pan also be used, however, in connection with the generation of steam at much higher pressures and the corresponding temperatures, as, for example, in stationary boilers operating at pressures'as high as 1000 to 1500 pounds per square inch. The compositions employed in accordance with the invention are effective not only in inhibiting foaming but also in conditioning and improving the quality of the steam. For this purpose, they may be used in even smaller amounts than the amounts required for the complete inhibition of foaming and priming.

Example B Per cent Ether alcohol described in Test I 8 Soda a 72 Sodium septaphosphate 20 form of magnesium hydroxide, it is desirable that suflicient of hydroxylated organic material such as tannins, tannic acid, gallic acid, pyrogallol, catechol, phloroglucinol, etc. be added along with the ether alcohols. These hydroxylated organic compounds have the ability of nullifying the bad eflects of the magnesium hydroxide. Magnesium The The ether alcohols employed in the practice of a hydroxide appears to partially selectively adsorb the antifoam material and so take it out of the boiler water so that the full antifoam action cannot be exerted by the antifoam compositions when in this adsorbed state. However, when an organic materialsuch as a tannin is added, magnesium hydroxide appears to lose its ability to interfere with the antifoam action. Inasmuch as most boiler feedwaters encountered will have varying amounts'of magnesium salts present, it is desirable that such hydroxylated organic compounds be mixed with the polyether alcohols prior to addition to the boiler feedwater.

Thus another advantage is evident in preparing and using the pulverized or briquetted compositions hereinabove described containing both the polyether alcohol antifoam and the polyhydroxylated organic material of the tannin or lignin-derivative type.

As will be apparent from the foregoing description, the compounds employed in accordance with the invention do not all give the same results and from that standpoint are not necessarily equivalents. Some of these ether alcohol compositions, especially those of the type referred to in Test 1, are truly remarkable in their foam inhibiting properties even when compared with the best of the antifoam compositions which have been previously used commercially.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

l. A process of minimizing the production of foam in and the priming of steam generators operating under superatmospheric pressure conditions which comprises incorporating with a water therein containing an amount of total solids tending to produce foaming and priming a quantity of a monoalkyl ether of a polyoxyalkylene glycol wherein the alkylene radicals are selected from erating under superatmospheric pressure conditions which comprises incorporating with a water therein containing an amount of total solids tending to produce foaming and priming a quantity of a monoalkyl ether of a polyoxyalkylene glycol wherein the alkylene radicals are selected from the group consisting of ethylene, propylene, and

mixtures thereof, the terminal alkyl radical of said monoalkyl ether containing at least 12 carbon atoms and the average molecular weight being at least about 500, saidmonoalkyl ether being substantially insoluble in said water under said steam generating conditions, and'said quantity being suflicient to substantially inhibit foaming and priming. v

3. A process of minimizing the production of foam in and the priming of steam generators operating under superatmospheric pressure con,- ditions which comprises incorporating with a water therein containing an amount of total solids tending to produce foaming and priming a quantity of a monobutyl ether of a polyoxyalkylene therein containing an amount of total solids tending to produce foaming and priming a quantity of a monobutyl ether of a polyoxyalkylene glycol in which ethylene oxide and 1,2-propylene oxide in a weight ratio of approximately 1:1 are combined as oxyethylene and oxypropylene groups, the average molecular weight of said monobutyl ether being approximately 5000, and said quantity being sufiicient to substantially inhibit foaming and priming.

5. A process of minimizing the production of foam in and priming of steam generators operating under superatmospheric pressure conditions which comprises incorporating with a water therein containing an amount of total solids tending to produce foaming and priming a quantity of a monocetyl ether of a polyoxypropylene glycol having a molecular weight of approximately 1200, said quantity being suflicient to substantially inhibit foaming and priming.

6. A process of minimizing the production of foam in and the priming of steam generators operating under superatmospheric pressure conditions which comprises incorporating with a water therein containing an amount of total solids tending to produce foaming and priming a quantity of a monobutyl ether of a polyoxypropylene glycol having a molecular weight of approximately 1700, said quantity being sufiicient to substantially inhibit foaming and priming.

7. A process of minimizing the production of foam in and the priming of steam generators operating under superatmospheric pressure conditions which comprises incorporating with a water therein containing an amount of total solids tending to produce foaming and priming, a quantity of a non-ionic monoalkyl ether of a polyoxyalkylene glycol, wherein the alkylene radicals are selected from the group consisting of ethylene, propylene and" mixtures thereof, the average molecular weight of said monoether being at least 1 500, and said quantity being within the range of 0.001 grain to 0.1 grain per gallon of water.

'8. A process of minimizing the production of foam in and the priming of steam generators operating under superatmospheric pressure conditions which comprises incorporating with a water therein containing an amount of total solids tending to produce foaming and priming, a quantity of a non-ionic monoalkyl ether of a polyoxyalkylene glycol, wherein the alkylene radicals are selected from the group consisting of ethylene, propylene and mixtures thereof, the average molecular weight of said monoether being at least 1500, said quantity being sufficient to substantially inhibit foaming and priming, and said superatmospheric pressure conditions being within the range of 100 to 1500 pounds per square inch and the corresponding temperatures.

9. A process of minimizing the production of foam in and the priming of steam generators operating under superatmospheric pressure conditions which comprises incorporating with a water therein containing an amount of total solids tending to produce foaming and priming, a quantity of a non-ionic monoalkyl ether of a polyoxyalkylene glycol, wherein the alkylene radicals are selected from the group consisting of ethylene, propylene and mixtures thereof, the average molecular weight of said monoether being at least 1500, said quantity being suflicient to substantially inhibit foaming and priming, and said superatmospheric pressure conditions being within the range of 100 to 300 pounds per square inch and the corresponding temperatures.

10. The method of generating steam from a boiler water having a tendency to foam on boiling and which contains magnesium compounds which comprises dispersing in said water a quantity of a monoalkyl ether of a polyoxyalkylene glycol wherein the alkylene radicals are selected from the group consisting of ethylene, propylene and mixtures thereof, the average molecular weight of said monoalkyl ether being at least about 1500 and said monoalkyl ether being substantially insoluble in said boiler water under the steam generating conditions, and a quantity of a hydroxylated organic compound from the group consisting of tannins, sodium lignin sulfonate and 'desulfonated lignins effective to nullify the action of the magnesium compounds on said monoalkyl ether of the polyoxyalkylene glycol, the quantity of the monoalkyl ether of the polyoxyalklene glycol being effective to inhibit the tendency of said water to foam on boiling, and heating the resultant aqueous dispersion to the boiling point.

11. The method of generating steam from a boiler water having a tendency to foam on boiling and which contains magnesium compounds which comprises dispersing in said water a quantity of a monoalkyl ether of a polyoxyalkylene glycol wherein the alkylene radicals are selected from the group consisting of ethylene, propylene and mixtures thereof, the terminal alkyl radical of said monoalkyl ether containing at least 12 carbon atoms and the average molecular weight being at least about 500, said monoalkyl ether being substantially insoluble in said boiler water under steam generating conditions, and a quantity of a hydroxylated organic compound from the group consisting of tannins, sodium lignin sulfonate and desulfonated lignins effective to nullify the action of the magnesium compounds on said monoalkyl ether of the polyoxyalkylene glycol, the quantity of the monoalkyl ether of the polyoxyalkylene glycol being effective to inhibit the tendency of said water to foam on boiling, and heating the resultant aqueous dispersion to the boiling point.

12. The methodof generating steam from a boiler water having a tendency to foam on boiling and which contains magnesium compounds which comprises dispersing in said water a quantity of a monoalkyl ether of a polyoxyalkylene glycol in which ethylene oxide and 1,2-propylene oxide are combined as oxyethylene and oxypropylene groups and the average molecular weight of said monoalkyl ether is at least 3500, and a quantity of a hydroxylated organic compound from the group consisting of tannins, sodium lignin sulfonate and desulfonated lignins effective to nullify the action of the magnesium compounds on said monoalkyl ether of the polyoxyalkylene glycol, and heating the resultant aqueous dispersion to the boiling point, said monoalkyl ether of said polyoxyalkylene glycol being dispersed intosaid water in-an amount sufficient substantially to inhibit the tendency of said water to foam on boiling, said amount being within the range of 0.001 grain to 0.1 grain per gallon of water. 1

13. A liquid for the generation of steam comprising water containing magnesium compounds, an amount of total dissolved solids tending to produce foaming and priming when heated to the boiling point, a quantity of a monoalkyl ether of a polyoxyalkylene glycol wherein the alkylene radicals are selected from the group consisting of ethylene, propylene and mixtures thereof, said monoalkyl ether is substantially insoluble in water under the conditions of steam generation, and the average molecular weight is at least 1500, the aforesaid quantity being effective to inhibit the tendency of said water to foam on boiling, and a .quantity of a hydroxylated organic compound from the group consisting of tannins, sodium lignin sulfonate and desulfonated lignins effective to nullify the action of the magnesium compounds on said monoalkyl ether.

14. A liquid for the generation of steam comprising water containing magnesium compounds, an amount of total dissolved solids tending to produce foaming and priming when heated to the boiling point, a quantity of a monoalkyl ether of a polyoxyalkylene glycol wherein the alkylene radicals are selected from the group consisting of ethylene, propylene and mixtures thereof. the terminal alkyl radical contains at least 12 carbon atoms, said monoalkyl ether is substantially insoluble in water under the conditions of steam generation, and the average molecular weight is at least about 500, the aforesaid quantity being effective to inhibit the tendency of said water to foam on boiling, and a quantity of a hydroxylated organic compound from the groupconsisting of tannins, sodium lignin sulfonate and desulfonated lignins effective to nullify the action of the magnesium compounds on said monoalkyl ether.

15. An antifoam composition for minimizing the production of foam in the generation of steam from water containing magnesium compounds which comprises essentially a quantity of a monoalkyl ether of a polyoxyalkylene glycol wherein the alkylene radicals are selected from the group consisting of ethylene, propylene and mixtures thereof, said monoalkyl ether is substantially insoluble in water under the conditions of steam generation, and the average molecular weight is at least about 1500, the aforesaid quantity being effective to inhibit the tendency of said water to foam-g on boiling, and a quantity of a hydroxylated organic compound from the group consisting of tannins, sodium lignin sulfonate and desulfonated lignins effective to nullify the action of said magnesium compounds on said monoalkyl ether when said composition is dispersed in water containing magnesium compounds.

16. An antifoam composition for minimizing the production of foam in the generation of steam from water containing magnesium compounds which comprises essentially a quantity of a monoalkyl ether of a polyoxyalkylene glycol wherein the alkylene radicals are selected from the group consisting of ethylene, propylene and mixtures thereof, the terminal alkyl radical contains at least 12 carbon atoms, said monoalkyl ether is substantially insoluble in water under the conditions of steam generation, and the average molecular weight is at least about 500, the aforesaid quantity being effective to inhibit the tendency of said water to foam on boiling, and a quantity of a hydroxylated organic compound from the group consisting of tannins, sodium lignin sulfonate and desulfonated lignins effective to nullify the action of said magnesium compounds on said monoalkyl ether when, said composition is dispersed in water containing magnesium compounds.

17. An antifoam composition for minimizin the production of foam in the generation of steam from water containing magnesium compounds which comprises essentially a quantity of a monoalkyl ether of a polyoxyalkylene glycol in which ethylene oxide and 1,2-propylene oxide are combined as oxyethylene and oxypropylene groups and the average molecular weight is at least 3500, the aforesaid quantity being effective to inhibit the tendency of said water to foam on -boiling, and a quantity of a hydroxylated organic compound from the group consisting of tannins, sodium lignin sulfonate and desulfonated lignins effective to nullify the action of said magnesium compounds on said ether when said composition is dispersed in water containing magnesium compounds.

18. The process of minimizing the production of foam in steam boilers during steam generation which comprises incorporating in a water therein containing an amount of total solids tending to produce foaming, a quantity of a monoalkyl ether of a polyoxyalkylene glycol, in which ethylene oxide and 1,2-propylene oxide in a weight ratio of approximateh' 1:1 are combined as oxyethylene and oxypropylene groups, the average molecular weight of said monoalkyl ether being at least about 500, said quantity being suilicient to substantially inhibit said foaming.

JOHN W. RYZNAR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,213,477 Steindorfl et a1. Sept. 3, 1940 2,307,058 Moeller Jan. 5, 1943 2,428,776 Bird et al Oct. 14, 1947 FOREIGN PATENTS Number Country Date 429,423 Great Britain May 23, 1935 469,334 Great Britain July 23, 1937 Certificate of Correction Patent No. 2,575,298

November 13, 1951 JOHN W. RYZNAR It is hereby certified t hat error appeare in the printed Specification of the above numbered patent requiring correction as follows:

Column 1, line 30 for generattor read generator; column 5, line 14, after propylene insert amide; column 11, line 18, for stantantially read stantz'all%;

go1mSn 16, line 59, list of references cited, under UNITED ST T insert- ATES PA 2,442,768 Gunderson June a, 1948 and that the said Letters Paten e same may conform to the record of the case in the Patent Ofli Signed and sealed this 12th day THOMAS F. MURPHY,

Am'etant Oommim'oner of PM.

Claims

1. A PROCESS OF MINIMIZING THE PRODUCTION OF FOAM IN AND THE PRIMING OF STREAM GENERATORS OPERATING UNDER SUPERATMOSPHERIC PRESSURE CONDITIONS WHICH COMPRISES INCORPORATING WITH A WATER THEREIN CONTAINING AN AMOUNT OF TOTAL SOLIDS TENDING TO PRODUCE FOAMING AND PRIMING A QUANTITY OF A MONOALKYL ETHER OF A POLYOXYALKYLENE GLYCOL WHEREIN THE ALKYLENE RADICALS ARE SELECTED FROM THE GROUP CONSISTING OF ETHYLENE, PROPYLENE, AND MIXTURES THEREOF, THE AVERAGE MOLECULAR WEIGHT OF SAID MONOALKYL ETHER BEING AT LEAST ABOUT 1500 AND SAID MONOALKYL ETHER BEING SUBSTANTIALLY INSOLUBLE IN SAID WATER UNDER STEAM GENERATING CONDITIONS, AND SAID QUANTITY BEING SUFFICIENT TO SUBSTANTIALLY INHIBIT FOAMING AND PRIMING.