US2428776A - Prevention of foaming in steam boilers - Google Patents

Description

Patented Oct. 14,1941

rm-zvnu'non or FOAMING m swam nomms Paul G. Bird and Arthur L. Jacob! Western Springs, 11]., asslgnors to National Aluminate Corporation, Chicago, 111., a corporation oi Delaware No Drawing. Application March 21, 1942,

Serial No. 430.491

6 Claims. (01. 252-321) 1 The present invention relates .to antiioaming compositions which are used in steam boilers and similar steam generators, evaporators, etc., to overcome the tendency of the water therein to foam and hence to bring about the priming of the steam generator or the like.

One of the objects of the present invention relates to a liquid suitable for the generation oi steam in steam generators and comprising water containing dissolved therein a very small quantity of an acyl derivative of an aromatic polyamine having a high molecular weight, whereby, when such water is heated to the boiling point in a steam boiler or other generator, being thereby evaporated; the concentration of solids therein will not bring about excessive foaming and the resulting priming, these compounds being substantially nonvolatile with the steam and stable,

1 so that they will be retained by the water and neither they nor their decomposition products will appear in the steam and the resulting condensation thereof.

It is well known in the operation of steam boilers, such as in electric power plants, railroad locomotives and the like, or in evaporators, that the water therein, even though initially it shows very little tendency to foam, will, when the amount of total solids therein approaches a relatively high concentration, develop a very decided tendency to foam. When this occurs, considerable quantities of water are physically carried out of the boilers or evaporators with the steam, thus appearing in the steam lines and in the eventual condensate. Such priming has many disadvantages because it tends to contaminate the steam lines, to plug or corrode the valves, and under serious conditions may even impair the cylinders and piston rods of the steam engines, or the impeller blades of turbines in which the steam is used for the generation of power. Attempts have been made in the past to control this foaming, either by excessive blowdown of the boilers or by the injection thereinto of such materials as castor oil, tallow, and the like. While these fatty materials have some small degree of efllciency, 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 acids or glycerides are unstable under the conditions existing in the boilers, particularly as the pressure and temperature increase, the high temperatures leading to rapid decomposition of the glycerides, which, if anything, will tend to increase the foaming and priming difllculties.

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 boilers, thus appearing in the steam and in the condensate. This, of course, is also very undesirable. Furthermore, such types of antifoaming agents usually 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 those which have a tendency to decompose do so quite rapidly, and hence their efi'ectiveness is of short duration, which therefore necessitates the continual charging into the boilers or other steam generators of relatively large amounts of these older antifoaming agents. Moreover. such antifoaming agents are diiilcult to use because the amounts in which they are eflicacious are very critical, and any overdosage usually aggravates the difliculty instead of curing it.

Applicants have now discovered, however, that there is a series of compounds which may broadly be designated as acyl derivatives of aromatic polyamines, wherein the acyl groups are derived from high molecular weight aliphatic acids, and which are of a high order of efliciency when used as an antifoaming and antipriming agent in steam generators. These acyl derivatives must, however, meet certain requirements as to molecular weight and configuration, as will be fully discussed below.

The materials of the invention maybe represented by the probable general formula:

wherein Y and Z represent aliphatic hydrocarbon radicals which may contain one or more double bonds and may be substituted by hydroxy] groups;

that is, the groupings Y-CO- and -OCZ formulas given are believed-to be possessed by the compounds disclosed, or whose method of preparation is disclosed in this specification.

. derived from the same may acid, and in fact one may be relatively small. as for example,

- acetyl. when the other contains at least about 16 carbon atoms, but in ,the case where they are substantially equal in number ohcarbon atoms,

each must contain at least about 14;

Specific compounds which have been shown to be eillcient as antii'oaming and antipriming agents include the products from the condensation of oleic acid with m-phenylenediamine, stearic acid with m-phenylenediamine, palmityl chloride with 4,4 diaminobenzophenone, palstearic acid with N-methylphenylenediamine,

stearic acid with p-phenylenediamine, and palmityl chloride with benzidine. 7 Many of the products useful in connection with the presentinvention may be obtained in more 20 than one way. The examples given below are merely illustrative of methods of preparing a, few representative members of the group,

Example 1.-A mixture of 19.8 grams oi. oleic' acid and 3.2 grams of m-phenylenediamine was heated with stirring at 150-160 C. for 3.5 hours. When cool, the product was a dark brown, viscous oil.

Example 2.A mixture of 24.2 grams of commercial stearic acid and 4.3 grams or m-phenylenediamine was heated with stirring at 150-160 C. for 3 hours. When cool, the product was a hard, black wax.

Example 3.-'I'o a stirred and heated portion of palmityl chloride weighing 22 grams was added 85 slowly, with stirring, 8.5 grams of 4,4'-diaminobenzophenone, During the addition, the temperature of the mixture was gradually increased from about 100 C at the beginning to a maximum of 190 C. at the end. Much hydrogen chlo- 40 ride was evolved during the addition. When cool,

the product was a very high melting wax,

Example 4.-To 22 grams of palmityl chloride was added slowly, and with stirring, 8 grams of 4,4-diaminodiphenyl ether, The temperature of the mixture was gradually increased during the addition from about 100 C. at the start to about 190 C. at the end. Hydrogen chloride was freely evolved during the addition: and the product,

when cool, was a hard, crumbly, dark wax.

Example 5.-A mixture of 11.8 grams of commercial stearic acid and 2.5 grams of methyl p-phenylenediamine was heated with stirring at 150-160 C. for 3 hours. when cool, the product was a brown wax.

Example 6.-A mixture of 16.9 grams or commercial stearic acid and 5.4 grams or p-phenylenediamine was heated with stirring at 150-160 C. for 3 hours. When cool, the-product was a brown wax.

Example 7.--To 22 grams oi' palmityl chloride, 7.4 grams of benzidine was added slowly with stirring and heating. During the addition, the temperature was increased from about 100 C. at the start to about 250 C. at the end. Hydrogen chloc5- ride was-freely evolved during the addition; and

when the product was cool, it was an extremely hard wax, Example 8.'I'o 16.5 grams or palmityl chloride at 150-160 C. was added, with stirring, 6 grams of 2,-diaminodiphenylamine, over a lo -minute period. After addition was complete, the stirring and heating were continued an hour. When cool, the product was a brown, sticky wax.

4 and 30 grams or stearyl chloride were mixed at room temperature and heated with stirring at 150-l60 C. for an hour.- When cool, the prodnot was a brown wax.

The compounds mentioned herein, while not ordinarily considered as soluble in water to any great extent, may be suitably dispersed in water or position products. The compounds may be used mityi chloride with 4,4--diaminodiphenyl ether, 15

coniointly with each other as well as with other known antiioaming agents, such as, for example,

matic polyamines, of high molecular weight;

which are required are extremely small, and in general one grain per gallon is ample. For many purposes, however, amounts of as little as ,6 grain per gallon in the feed water will still give valuable results, and the amounts may be even further reduced. Depending of course upon'the degree of concentration oisolids. the dosage may be varied, but one grain per gallon is about as much as would ever have to be used even under serious conditions, and for many purposes A grain per gallon and even less can be used. The process is particularly eflective at pressures oi about 250 pounds per square inch.

The introduction of the antifoaming compounds of the present invention into the boiler may be accomplished in a number of ways. Thus. the antifoaming compositions may be dispersed or physically mixed with, say. sodium carbonate I or some other material used for treating the boiler water and pumped with the feed water into the boiler by means of either an injector or a feed water pump. The compounds may also be diswhich the steam generator is subjected. Another manner of introducing the antiioaming compounds is to form an emulsion thereof in water and then feed said emulsion either directly into 5 the boiler or the feed water lines leading to it.

The invention therefore is not to be limitedby the manner of introduction of the antifoaming composition but rather is to be construed in the terms of the hereunto appended claims.

We claim: I

1. Process 01' minimizing the production or foam in and the priming of steam generators operating at superatmospheric pressures which comprises incorporating with awater therein containing an amount of total solids tending to produce foaming and priming a quantity of a diacyl derivative oi an aromatic polyamine sufllcient to substan- I tially inhibit priming and foaming, said acyl group containing at least about 16 carbon atoms.

2. Process of minimizing the production oi. foam in and the priming of steam generators operating at superatmospheric pressures which coma prises incorporating with a. water therein a quantity of a diacyl derivative of a phenylenediamine Example 9.-5.4 grams oi'o-phenylenediamine in which each of the acyl groups contains at least 14 carbon atoms, said quantity being sufilcient to substantially inhibit priming and foaming.

3. Process of minimizing the production of foam in and the priming of steam generators operating at superatmospheric pressures which comprises incorporating witha water therein a quantity of a condensation product of metaphenylenediamine and stearic acid, sufiicient to substantially inhibit priming and foaming.

4. Process of minimizing the production of foam in and the priming of steam generators operating at superatmospheric pressures which comprises incorporating with a water therein a very small amount of a condensation product of palmityl chloride and 4,4-diaminobenzophenone, suflicient to substantially inhibit priming'and foaming.

5. Process of minimizing the production of foam in and the priming of steam generators operating at superatmospheric pressures which comprises incorporating with a Water therein a very small amount of a condensation product of palmityl chloride and benzicline, sufiicient to substantially inhibit priming and foaming.

6. The process of conditioning water for the generation of steam under superatmospheric presresidues contains at least about 16 carbon atoms,

said quantity of diacyl derivative of an aromatic polyamine being sufiicient to substantially inhibit priming and foaming.

PAUL G. BIRD. ARTHUR L. JACOBY.

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

UNITED STATES PATENTS Number Name Date 2,074,380 Flett Mar. 23, 1937 1,892,857 Spellmeyer Jan. 3, 1933 2,103,872 Schoeller et a1. Dec. 28, 1937 2,304,805 Denman Dec, 15, 1942 2,328,551 Gunderson Sept. 7, 1943