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Boiler Water Treatment (Continued from Page 28) fact that flues and tubes in some sec- tions might be safely operated throughout a lifetime, while, in other sections, tubes and flues must be re- placed at intervals as short as six or eight months. In the accompanying table the samples of fresh water were taken as follows: 1, Mississippi river, (Pa- ducah, Oct. 1927); 2, Lake Michigan (Great Lakes, Ill, Aug. 1927); 3, Well (Chicago Heights, Ill, May, 1927); 4, Well (Edgemont, Nebr., June, 1927). Impurities in Grains Per Gallon in Four Fresh Waters 1 3 4 Organic & volatile .............. 5.02 a 8.09 12.63 Sodium chloride wc... 1.29 1.02 1.50 15.61 Sodium sulphate oc... CAD See itabece eu aakbaaan Calcium carbonate ............ 3. 16 4.77 8.98 4.52 Calcium sulphate .90 1.70 27.97 18.88 Magnesium carbonate .. .22 1.75 15.69 e Oe Magnesium chloride ..... Carbonic: BCIG ss. occssssccocscssesesses 1.87 5.76 13.99 : a The cities and stations on the Great Lakes are blessed with a_ splendid boiler water supply, inexhaustible and almost unchanging. Analysis number 2, taken at our naval training station, on Lake Michigan, in August, will dif- fer very slightly from one taken at the same place in December, this is because of the large basin storage. Compare this beautiful supply with analysis number 8, Chicago Heights is only a short distance inland from Lake Michigan yet this water supply, which is characteristic of all inland well waters of Illinois and Indiana is so hard as to make treatment costly while, without treatment, steam boil- ers cannot use it and render service. Even heating systems .in_ private houses are destroyed in their useful- ness in very short periods of time. Naturally large industries avoid these towns, and the tendency for extension of the city boundries of Chicago finds one of its reasons in the superiority of its water supply. Interest in sample number 4, lies in the fact that the water issues from an artesian well at a high tempera- ture. It is the supply of the Chi- cago, Burlington & Quincy railroad at Edgemont, S. Dak., in the re- gion of the Black Hills. In addition to the necessity for an expensive treatment the railroad is embarrassed with the problem of cooling it before it can be used with the standard lo- comotive injectors. An observer may in the summer time, actually see en- gine crews placing blocks of ice in the tender tanks of their locomotives, to bring the water down to a tempera- ture low enough to permit of the in- jectors picking it up. Despite the fact that in many cases the necessity for, or at least the ad- weeseces 70 visability of water treatment is ap- preciated, the-brain of the executive may well be puzzled in choosing be- tween the several and_ conflicting plans for the treatment of water supplies, argumentatively and ag- gressively advanced. It seems to the writer that frank discussion, without prejudice or ran- cor, of the comparative advantages and disadvantages of the several gen- eral methods of preventing the for- mation of scale, of minimizing cor- rosive tendencies and of overcoming foaming, in boilers, would be of the greatest value to the officer who must authorize the expenditures, incident to a water treatment program. There are three general methods of treating waters for evaporative pur- poses, as follows: Method A: The complete treating plant, involving mixing, stirring, set- tling and filtering apparatus located at each troublesome water supply sta- tion. Cost per 1000 gallons evap- orated: From 7 to 17 cents. Cost of apparatus: From $20,000 to $50,000 per installation. Method B: The mere application of chemicals or chemical compounds through a simple system of by-pass- ing into the supply tanks. Cost per 1000 gallons pumped: From 2 to 10 cents. Cost per 1000 gallons evap- orated: From 4 to 20 cents. Cost of apparatus: From $75 to $300 per installation. Method C: The application of the necessary chemicals or chemical com- pounds directly to the individual boil- ers. Cost per 1000 gallons evaporated (only) 1 to 4 cents. Cost of appa- ratus: Nothing. At first glance, method A, has the greatest appeal. This appeal becomes the greater in the eyes of the non- technical officer, when he hears the method spoken of as “purification.” The facts are that these treating plants do not purify the water. What they do is to take out, by reaction and settlement certain objectionable solids while allowing others to re- main, and while adding still others. The solids which are not taken out, such as sodium chloride or common salt, are sometimes the most ob- jectionable of all. The solids which are added are also frequently objec- tionable, as for instance, sodium sulphate (the result of one of the reactions) which is one of the causes of foaming. Despite its objections this treat- ment is by all means the one to be preferred where the solids in the raw water are present in very large pro- portion and where there is very large consumption of such a supply. This MARINE REVIEW—July, 1929 is because, if they are not removed from the water, the solids would build up sludge in the boilers so rap- idly as to cause serious difficulty. The first method is the only one which keeps these sludge forming solids from entering the boilers. The foam- ing tendencies of the waters custom- arily delivered by the treating plant are recognized as inevitable. This necessitates the use of method C as an auxiliary treatment and ties the two methods together. It will be noted that for method B, as for method A, two per thousand gallon costs are given. This is be- cause not all of the water treated is customarily evaporated in _ boilers. Where lime and soda ash are used for reagents or where straight soda ash fs used in by-passed solution, the losses due to the difference between the quantity of water treated and that evaporated are of small impor- tance. When precombined chemical compounds are used in this manner, however, these losses become very serious because of the cost of the compounds wasted. This wastage may easily run to fifty per cent or more depending upon water usage conditions. A few min- utes thought will result in an appre- ciation of these wastages. Water escapes by leakage, by use for sprinkling, boiler washing, station service, fire prevention and practice, as well as in other ways. Having in mind these objections, there are oc- casional conditions which, neverthe- less, make this method the best avail- able. It is apparent that there is usually marked loss in applying the chem- icals to the stores water supply, which is completely obviated by ar- ranging for application to the vessel or station supply tanks or directly to the boilers. In either case, the chemicals merely go into solution, awaiting their injection into the boiler for the necessary reaction. The use of method C calls for no apparatus or change of current and Standard practice. It merely in- volves the application of the necessary chemical compounds to the boiler through suitable direct feeding de- vices. This treatment is “boosted” by the application directly to the boiler, after each washout, of a charge of chemicals, compounded to obtain the best physical as well as chemical effect upon old scale forma- tions on the neating surfaces. It cannot be disputed that the most immediate and effective results in water treatment may be obtained by the application of the method de- scribed above as method C.