1818. J 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



179 



APPARATUS FOR SUPPLYING BOILERS WITH WATER. 



Report (by Order of the Amerk-an Government Jon an Ap])nratus for 

 Supplying the Boilers of Marine St earn- Engines with a Continuous 

 Supply of Fresh Water. Invented by Captain John Ericsson. — ■ 

 [From the Franklin Journal.'} 



In acceptance of j'our invitation of the ITtli ultimo, we, the 

 undersifined, had the lionour to meet together in the city of New 

 York, with the view of testinij and reporting upon an apparatus 

 invented by Captain John Ericsson, for the purpose of supplying 

 the boilers of marine steam-engines ivith a continuous supply of 

 fresh water, and applied l)y him under your direction in the United 

 States Revenue Steamer heg<ir!\ 



We have now respectfully to report, that on the 23rd ultimo we 

 embarked in the Leijare at 12 M., proceeded to sea, and remained 

 on board till the following morning. During this time the boiler 

 was in operation 15 hours, and we had am|de opportunity of ex- 

 amining the means employed for supplying it with water and the 

 results produced. 



By tlie ordinary method of condensing steam in marine naviga- 

 tion, boilers are supplied with the vHiter of condensation., composed 

 of the steam that is withdrawn from the boiler and the necessary 

 quantity of salt water required for its condensation. Hence, a 

 boiler in operation is constantly parting with steam (fresh water) 

 and receiving salt water in e.xchange. The effect of this operation, 

 uninfluenced by a correction, would be, that in a few hours a de- 

 gree of saturation of the water in the boiler would be reached, that 

 would precipitate ujion the plates of the furnaces and flues, a scale 

 of sufficient thickness to arrest the passage of the heat to the sur- 

 rounding water and cause the destruction of the plates, by expos- 

 ing them to a temperature destructive of their tenacity. The cor- 

 rection in use is the remo\al of tlie water as it approaches satura- 

 tion, and is effected by blowing, or pumping-nff. 



In the operation of either of these metliods, it is apparent that 

 there is a loss of the heat that has been imparted to the ^vater 

 blown or pumped oft', that neglect to open or shut the blow-off 

 cock, or in tlie admission of the required supply of water, involves 

 the duration of the boiler and may, as it frequently does, involve 

 the lives of the passengers and the crew, and the safety of the 

 vessel. Even when all practicable attention is given to blowing- 

 off, salt scale will be deposited in long voyages, particularly in the 

 middle latitudes, and accumulate to an extent that renders its re- 

 moval iniperati\ely necessary. This is at all times a difficult, and 

 even under the most favourable circumstances, an imperfect opera- 

 tion, and when tliis deposit coats the surfaces of the flues, the con- 

 sumption of fuel is increased to an extent unsuited to the economy 

 of mercantile enterprise and to the duration of operation requisite 

 for naval purposes. 



This evil may be avoided by furnishing the boilers with a full 

 supply of fresh water, and as the weight could not be accommodated, 

 nor the space spared in a vessel for an instrument and its fuel for 

 the sole purpose of distilling the quantity required, it is obvious 

 that the steam furnished by a boiler must be returned to it, after 

 being condensed by the radiation of its heat to cold surfaces, and 

 not by the admixture of water. This method was proposed by 

 James W^att, so early as the year 17.76, and has been effected to 

 some extent by an instrument invented by Mr. Samuel Hall, of 

 England, and applied to the engines of many steam-vessels, in 

 some of which, notwithstanding its imperfections, it is yet used. It 

 has failed, however, to answer the full purposes desired and anti- 

 cipated. 



In the arrangement of Mr. Hall a great number of thin metal 

 tubes, from one-half to three-fourths of an inch in diameter, were 

 placed vertically in a condenser and exposed to a current of cold 

 water from the sea and into which the steam from the cylinder was 

 admitted, for the abstraction of its heat by the radiation of it to the 

 water without the tubes. Now it is evident, that, by this arrange- 

 ment, the condensed steam would run down the inner surface of 

 the tubes, in its passage presenting a non-conducting lining to 

 them, and in its collection at their bottom an obstacle to the cur- 

 rent of the steam and a dimiimtion of the effective radiating sur- 

 face. 



With this method of condensation, it will be perceived that this 

 instrument provides alone for returning to the boiler, the water 

 that has passed through the engine as steam. It follows, then, 

 that all esca|)es of steam from the boiler or engine, or water-leaks 

 from the boiler, pipes, &c., must be replaced by distillation, at an 

 expense of fuel, directly as the evaporation. Further continued 

 use of this instrument exhibited an oleaginous deposit upon the 

 inner surface of the tubes from the use of oil and tallow iu the 



steam cylinder and on the valve faces, which, acting as a non-con- 

 ductor, materially obstructed the condensation of the steam. 



The apjyaratus of Captain Ericsson was designed to obviate the 

 difficulties and deficiencies developed in that of Mr. Hall, and is 

 composed of two distinct instruments, a Condenser and an Evapo- 

 rator ; the first for tlie purpose of condensation, and the latter for 

 a supply of fresh water to provide for any losses of steam or water 

 from the boiler liy escapes, leaks, gauge vents, &c. 



The Condenser is a cylindrical vessel set at a slight inclination 

 from a horizontal line, containing the requisite extent of radiating 

 surface in metal tubes of tm inches bore, with an open space at 

 each end. By this arrangement there is free space for the current 

 of steam to pass and for the condensed steam to run down the 

 lower side of the tubes, without presenting a lining of water to in- 

 tercept radiation or an obstruction to the course of the steam. 

 Connected with this is a pump, by which water from the sea is 

 drawn in and forced through the spaces between the tubes and the 

 inner surface of the shell of the condenser. Thus, the latent heat 

 of the steam is absorbed by contact with the tubes, and condensa- 

 tion is effected for the double purpose of affording a vacuum for the 

 engine and of restoring fresh water to the boiler, for continuous 

 evaporation and condensation, to meet the requirements of the 

 engine. 



The Ex'aporator, as constructed, is a parallelopipedon with a 

 semi-cylindrical top and bottom, the lower portion of which is oc- 

 cupied by a numl)er of tubes similar to those in the condenser, 

 which communicate with a valve at each end of the steam cylinder, 

 worked by the engine : around these tubes, and for some distance 

 above them, water from the sea is admitted for the purpose of 

 being evaporated, and the space above this water is open to the 

 condenser and consequently in vacuo. This instrument being de- 

 signed to furnish fresh water to replace that which way be lost, its 

 operation is resorted to only as occasion may require, and is effected 

 in the following manner : when the piston is near tlie termination 

 of its stroke the valve referred to o])ens (above or below, as 

 the case may be), and closes when the piston begins its return 

 stroke ; by this arrangement, steam is withdrawn from the engine 

 that has very nearly performed its full expansive effect, and pass- 

 ing into the tubes of the evaporator its heat is absorbed by the 

 water surrounding them, and as this water is in vacuo it readilv 

 boils at a low temperature, and its vapour being led to the tubes 

 in the condenser, it is condensed with the steam from the cylinder 

 and is sujiplied to the boiler. 



Upon the exjierimental trial to which you were pleased to re- 

 quest our attention, all practicable arrangements for correct ob- 

 servations were entered into ; and with a view to acquire full and 

 progressive notes of the operations of the apparatus, the observa- 

 tions of the various points were confided to special committees, 

 which upon the conclusion of the trial, reported full notes for fur- 

 nishing tlie following, viz. : 



The boiler was filled with fresh water from above the opening 

 of the blow-off cock ; below this, salt water had been left, from an 

 impression of its effect being too inconsiderable to authorise its 

 removal. 



At the commencement of tlie operation of the engine, the water in the 

 holier as indicated by a sahne hydrometer, when at a temperature of 150" 

 Fahrenheit, was •^.* 



The highest temperature of the feed ivaler observed was 158° Fahrenheit. 



The lowest 132°, and the average 150°. 



The higliest vacuum observed was from 16 to 18 inches. 



Tlie lowest from 11 to 15, and the average was from 12 to 15 inches. 



The highest steam pressure was 54 lb. mercurial gauge. 



The lowest was 20 lb., and the average was 48'6 lb. 



The highest number of revolutions was 47 per minute. 



The lowest number was 30, and the average 42'3 



The piiint of cutting off was at three-eighths of the stroke. 



The temperature of the sea water was 57. 



Duration of operation of the engine and boiler 14 hours and 20 minutes. 



Time during which steam was raised, 20 hours. 



Dimensions of Engine, &c. 



Cylinder. — 36 inches in diameter, with a stroke of piston of 32 inches. 



Boiler. — 1,400 square feet of heating surface. 



Condenser. — 637 square feet of radiating surface. 



Evaporator. — 100 square feet of heating surface. 



Upon coming-to, the freshness of the water was again tested, 

 and when at a temperature of 150° by a different thermometer than 

 that used at the first operation (it having been broken in the in- 

 terim), the hydrometer indicated -fj ; whether this difference in 

 the indications is to be attributed to a change in the density of the 

 water or to a difference in the thermometers, they being of different 



* 12-32 being tba point of saturation of water when at s temperature of 200°, 



24- 



