US2206776A - Boiler composition - Google Patents

Description

Patented July 2, 1940 P N TED STATES BOILER COMPOSITION Otto Jalchke, Crowley, La.

No Drawing. Application October 18, 1937.

I Serial No. 169,749

3 Claims. (cl. 37-27) This invention relates to boiler compositions,

and more particularly to compositions adapted to be introduced into boiler feed water to soften the same and prevent the precipitation of hard scale,

5 as well as to aid in the removal of any hard scale already present.

The principal object of the invention is to provide a composition which when introduced into the boiler feed water, will not only soften the same, and prevent the depositing of hard scale, but will also penetrate and soften any scale already formed on the boiler walls so that itcan be removed readily.

Heretofore it has been customary to introduce 5 into the boiler water, either before or after a has entered the boiler, substances for the purpose of removing. temporary or .permanent hardness or both. For this purpose such compositions as soda ash, caustic soda and tri-sodium phosphate have been commonly used.

In order to prevent the formation of adherent scale in the boiler it has also been customary to add to these compositions a tannin bearing substance such as oak-bark, gambler, catechu or an equivalent material. Catechu is commonly added in admixture with the water softening, compositions in order to hold the precipitated scale-forming material in the form of a soft, non-scale-formingsludge which is easily removed. The tannic acid contained in such tannin bearing ingredients also attacks adherent scale and very gradually dissolves the same. p

It has been found that boiler treating compo- H sitions of the above type while useful for the purpose of preventing the formation of adherent scale deposits, act very slowly upon such scale already deposited, and are therefore of little use in boilers whose emciency is already impaired by heavy deposits of adherent scale. 49 By long experimentation I have discovered that the addition of a hydrocarbon chloro derivative of the class of chloro benzenes greatly im provesthe action of boiler compositions of the above type in preventing and removing adherent boiler scale. In this connection I preferably employ a composition of the class ofdichloro benzenes, such for instance as orthodichlorob'enzene or any of its homologues.

In preparing a boiler composition of this type I have found that the best results are obtained when the hydrocarbon chloro derivative is first mixed with an appropriate solvent. The solvents best suited to this purpose which I have employed are: 1

Carbon tetrachloride, C014 Tetrachlor-ethane, CHClaCHCli Tetrachlor-ethylene. 0012.001: Ethylene-di-chloride, CHrCLCHaCl Monochlorbenzene, 003501 I preferably prepare a solution of the hydrocarbon chloro derivative by mixing it with one of the above solvents in the proportion of about two parts of the chloro derivative to one part of the solvent.

.The composition with which I mix this solution of hydrocarbon chloro derivative is preferably a combination of soda ash, caustic soda, di-sodium phosphate, tri-sodium phosphate, or a mixture of any or all of them, together. with a tannin bearing substance. 0! the tannin bearing substances suitable for this purpose one of the following or its equivalent may be employed:

Oak-bark Sumac Gambler Mangrove outch Quebracho Catechu It is to be understood that although soda ash (sodium carbonate) and caustic soda are mentioned, other alkali metal salts such as potassium carbonate and caustic potash may be substituted.

Soda ashpmmd 3 Gambler. do 30 Caustic soda do 35" Ortho dichlorobenzene pints 10 'Carbon tetrachloride do 5 In making up the above composition the ortho dichlorobenzene is first mixed with the carbon tetrachloride as previously pointed out. The

soda ash, gambler and caustic soda all in water solutions are thoroughly mixed together to make up 53 gallons, and the ortho dichlorozenzene solution is then incorporated and uniformly distributed through the mixture. The whole mixture will then constitute a barrel of 55 gallons.

. In determining the amountof the composition which is to be added to a boiler, I have been guided more by practical experience than by theo-- retical calculation. As an example, I have found that a boiler of 300 horsepower, using approximately 12,000 gallons of water of a hardness of ten degrees in a ten hour shift, will require approximately 3 quarts of my composition. As the cleaning action of the composition progresses, a lesser quantity will be necessary, of which the engineer will be the best judge. The quantity of composition for a shift may for convenience be diluted with 5 to 10 gallons of water in a small tank, and fed into the feed water gradually during the ten hours.

In some cases, especially in bad water distriots where the onlywater available for boiler feed purposes contains large amounts of iron, I

have found it desirable to add oxalic acid or some other suitable reducing agent to my composition in order to reduce the ferric iron salts tothe ferrous form. The iron present in water is usually in the form of the ferric oxide FeaOa, which is diflicult to dissolve. When the iron is in the ferrous form FeO it may be put in solution more readily, and the oxalic acid is believed to have substantially the following action:

mod-0111.0 -v 2FeO+2COaT+H;O

The C: passes off as a gas while the FeO will react with tannic acid to produce a soft fluffy scale which can be washed out of the boiler.

This reducing agent I preferably add to the compositionin the'proportion of 5 to pounds of reducing agent to 100 pounds of the composition, but the proportions may be varied, depending upon the amount of iron present in the water.

While it is impossible to state exactly allthe reactions taking place upon the addition of, my boiler composition to the water, or the exact manner in which the ingredients cooperate in the prevention and removal of adherent boiler scale,

nesium chloride arevacted upon by the soda ash,.

likewise precipitating follows:

When di-sodium phosphate is present as an ingredient of my boiler composition,'it reacts with the scale-forming materials present in the boiler water to form phosphates which are exceedingly flufiy in nature. These phosphates form a mixture with the carbonate precipitates produced by the soda ash and caustic soda. The precipitating properties of the resulting mixture thus formed are superior to those of either the carbonates or the phosphates alone, since the latter are too fluffy and the former too gritty for rapid settling in the form of .a soft sludge. The di-sodium phosphate reacts with temporary hardness-forming constituents of the water according to the following equation 2Na1HP04+3Ca(HC0a): 1'

The insoluble carbonate precipitates, together with other insoluble precipitates, such as those insoluble carbonates as aaoep'le of iron which are formed therewith, are enveloped' by the particles of tannin to form a soft mass. part of which rises to the surface of thewater and can be blown oil, and part of which settles to the bottom and forms a soft sludge which can be removed easily.

Adherent scale already deposited or present in the boiler is attacked by the tannic acid content of the tannin bearing ingredient of the composition, and very slowly dissolved thereby. This scale is, however, much morerapidly attacked in the presence of the hydrocarbon chloro derivative present in the composition. This action is believed to be due to the penetration of the scale by the hydrocarbon chloro derivative by capillary aflinity, which enables it in cooperation with the tannic acid to rapidly disintegrate and envelop the particlesof scale. The combined action of the ingredients of the composition quickly and completely removes any adherent scale" from the boiler, and also effectively prevents any further formation of adherent scale therein. The tannin bearing material also forms a protective film over the exposed metal surfaces and thus acts to prevent scale adherence, while the hydrocarbon chloroderivative is harmless to metal.

It will thus be seen that my invention provides a means in the form of a cheap and easily made composition, for maintaining steam boilers in a clean and eflicient condition and results in a great reduction in the fuel costs.

It will, of course, be understood that ingredients other than those specifically mentioned herein can be substituted for any of those named, provided they are the full equivalent thereof.

- What is claimed is: V I

1. A boiler water treating composition comprising a water softening ingredient selected from the group consisting of soda ash, disodium phosphate, tri-sodium phosphate, caustic soda and the corresponding salts of potassium, a tannin bearing material, and a penetrating agent comprising ortho dichlorobenzene to substantially accelerate the solvent action of said tannin bearing material on adherent boiler scale.

2. A boiler water treating composition comprisinga water softening ingredient selected from the group consisting of soda ash, caustic soda, di-sodium phosphate, tri-sodium phosphate, and the corresponding salts of potassium, a tannin bearing material, and a chlorinated hydrocarbon solution of ortho dichlorobenzene serving as a penetrating agent for accelerating the solvent action of said tannin bearing mate rial on adherent boiler scale.

3. A composition for treating boiler water consisting of approximately pounds of soda ash, pounds of gambler, pounds of caustic soda, 10 pints of orthodichlorobenzene, and 5 pintsof carbon tetrachloride.

, o'rro JASCHKE.