US2428775A - Product and process for the prevention of foaming in steam boilers - Google Patents

Description

Patented Oct. 14, 1947 PRODUCT AND PROCESS FOR THE PREVEN- TION OF FOAMING IN STEAM BOILERS Paul G. Bird, Western Springs, Ill., assignor to National Aluminate Corporation, Chicago, 111., a corporation of Delaware 7 e No Drawing. Application March 27, 1942,

Serial No. 436,488

8 Claims. (Cl. 252-321) 1 The present invention relates to antifoaming 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 of steam in steam generators, comprising water containing dissolved therein a very small quantity of a particular kind of a high molecular weight acyla-mino-N-alkylated amide, whereby, when such water is heated to the boiling point in a steam boiler or other generator, being thereb 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, 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 blow-down 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 efiiclency, 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 foam and priming dimculties. 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 quit-e rapidly, and hence their effectiveness 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 difficult to use because the amounts in which they are efl'icacious are very critical, and any overdosage usually aggravates the difficulty instead of curing it.

Applicant has now discovered, however, that there is a series of compounds which may be broadly designated as acylamino-N-allqrlated amides, which are condensation products derived from aminoacids, organic acids and organic amines, and which are very efficacious in overcoming the priming and foaming of boilers, etc., containing dissolved solids.

The products which are employed in the prevention of foaming and priming may be considered as complex derivatives or reaction products of an aminoacid which has reacted with an organic acid or acid derivative and with an aliphatic primary or secondary amine, in any desired order, whereby the amino group of the aminoacid becomes acylated and the acid group of the aminoacid is converted into an N-alkylated amide group. Such compounds can broadly be designated as acylamino-N-alkylated amides, an example of which would be a material such as palmitylamino-N-hexadecylcaproamide.

The probable general structural formula for the materials of this invention may be written:

OCANHZ RI wherein R and R are the alkyl groups from an aliphatic amine, and either R or R, but not both, may be hydrogen; Z is the acyl radical of an organic monobasic acid; and A is the alkylene or arylene residue of an aminocarboxylic acid. It is to be understood that the formulas recited in the claims are "probable" in that the formulas I use of these.

given are believed to be possessed by the compounds disclosed, or whose method of preparation is disclosed, in this specification.

Some specific examples of materials of the above description, which have been shown to be of value, are (1) the product resulting from the reaction of palmityl chloride on epsilon-aminon-caproic acid, followed by treatment with noctadecylamine; (2) the product resulting from the reaction of palmityl chlorideand alphaamino-n-valeric acid, followed by treatment with n-hexadecylamine; (3) the product resulting from the reaction of palmityl chloride and alpha-amino-n-butyric acid, followed by treatment with n-hexadecylamine; and (4) the product resulting from the reaction of palmityl chloride and p-aminophenylacetic acid, followed by treatment with n-hexadec-ylamine; all as more fully described in the examples given hereinbelow.

Investigation has shown that an,important factor iii/determining whether the materials of this invention are valuable as anti-foaming agents is the number of carbon atoms in the derivative. Thus it appears that, to be of value, the derivative should contain at least about 36 carbon atoms. It will be apparent that this can be readily realized through theuse of relatively high molecular weight fatty acids and fatty amines, although the invention is not restricted to the the amino group of the aminoacid by an aromatic or arylsulfonic acid or derivative thereof.

The following examples are given to show how some valuable materials of this invention may be made, but the examples are not intended to limit the scope of the invention beyond the claims themselves.

Actually, it is possible to acylate Example 1.To 19.5 grams of palmityl chloride at 130 C., 5 grams of epsilon-amino-ncaproic acid was addedwith stirring. The mixture-was stirred at 150-160 C..for an hour, after which 10.2 grams of n-octadecylamine was added and stirring and heating continued 2 hours longer. When cool, the product was a brown wax and can be termed as a palmitylamino-Ne octadecylcaproamide.

E:1:ample a-TO 11 grams of palmityl chloride st'antially devoid of foaming and priming which may be termed palmitylamino-N-hexadecylbutyramide.

Example 4.'11 grams of palmityl chloride and 6.1 grams of p-aminophenylacetic acid" were caused to react by mixing and heating together for 30 minutes at 250 C. Then 9.6 grams of n-hexadecylamine was'added and the mixture stirred one hour at 200 C. The resulting product was a very hard, brown wax-like material, and can be considered as being palmitylamino-N- hexadecylp-aminophenylacetamide.

These 'acylamino-N-alkylated amides may be suitably dispersed in water or emulsified therewith, so that eflfective amounts thereof may be introduced and be present in the water within a the steam generator under operating conditions.

The emulsifying or dispersing agent used must, however, be of a kind that does not cause foaming, either by itself or by its decomposition products. The compounds may be used conjointly with each other as well as with other known antifoaming agents, such as, for example, castor oil.

The amounts required of these acylamino-N- alkylated amides of the present invention are extremely small, and in general one grain per gallon is ample. For many purposes, however, amounts of as little as 1/100 grain per gallon in the feed water will still give valuable results, and the amounts maybe even further reduced. Depending of course upon the degree of concentration of solids, 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 1/ grain per gallon and even less can be used. The process is particularly efiective at pressures of about 250 pounds per square inch.

The introduction of the antifoaming compounds of the present invention into the boiler maybe accomplished in a number of ways. Thus, the antifoaming compositions may be dispersed or physically mixed with, say, sodium carbonate of the anti-foaming compounds into the feedwater may be used, so that the introduction will be more or less in proportion to the steam consumption to which the steam generator is subjected. Another manner of introducing the antifoaming compounds is to form an emulsion thereof in water and then feed said emulsion 'either directly into the boiler or the feed water lines leading to it. The invention therefore is not to be limited by the manner of introductionv of the antiioaming composition but rather is to be construed in'the terms of the hereunto appended claims.

I claim:

1. A liquid for the generation of steam, subtendencies when heated to the boiling point, comprising water containing an amount of total solids tending to produce foaming and priming and having dispersed therein a quantity of an acylamino-N-alkylated amide sumcient to substantially inhibit priming and foaming, said amide having at least 36 carbon atoms and having the general formula from the group consisting of alkylene and arylene.

2. A liquid for the generation of steam, substantially devoid of foaming and priming tendencies when heated to the boiling point, comprising water containing an amount of total solids tending to produce foaming and priming and having dispersed therein a quantity of paimitylamino-N-octadecylcaproamide suflicient to substantially inhibit priming and foaming.

3. A. liquid for the generation of steam, substantially devoid of foaming and priming tendencies when heated to the boiling point, comprising Water containing an amount of total solids tending to produce foaming and priming and having dispersed therein a quantity of palmitylamino-N-hexatiecyivaieramide sumcient to sub stantiaily inhibit priming and foaming.

4. A liquid for the generation of steam, su stantiaiiy devoid of foaming and priming tendencies "when heated to the boiling point, comprising tvater containing an amount of total solids tending to produce foaming and priming and having dispersed. therein a quantity of palmitylamino-N-herradecyihutyramide sumcient to substantially inhibit priming and foaming.

5. Process oi minimizing the production of foam in and the priming of steam generators operating at superatmospheric pressures which comprises incorporating with a water therein containing an amount of total solids tending to produce foaming and priming a quantity of an acyiamino-N-alkyiated amide suficient to substantially inhibit priming and foaming, said amide having at least 36 carbon atoms and having the general formula in which R and R are the alkyl groups from an aliphatic amine, and either R or R, but not both;

may be hydrogen; Z is an acyl radical of a monocontaining an amount of total solids tending to produce foaming and priming a quantity of palmitylamino-N-octadecylcaproamide sumcient to suppress priming and foaming.

7. 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 containing an amount of total solids tending to produce foaming and priming a quantity of palmitylamino-N-hexadecylvalerarnide sumcient to suppress priming and roaming.

8. 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 containing an amount of total solids tending to produce foaming and priming a quantity of palmitylamino-N-hexadecylbutyramide eufiicient to suppress priming and foaming.

PAUL G. BIRD.

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

UNITED STATES PATENTS Number Name Date 1,892,857 Spellmeyer Jan. 3, 1933 2,304,805 Denman Dec. 15, 1942 Gunderson Sept. '7, 1943