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20 MARINE REVIEW. [May 22 REPLY TO THE BRITISH ADMIRALTY. LETTER OF DELAUNAY BELLEVILLE & CO., OWNERS OF THE BELLEVILLE WATER-TUBE BOILER PATENTS, TO ENGLISH NAVAL OFFICIALS ON THE SUBJECT OF THE BOILER COMMITTEE REPORT, A letter from Delaunay Belleville & 'Co., owners of the Belleville water-tube boiler patents,-to the British admiralty on the subject of the trials of the cruisers Hyacinth and Minerva, the former fitted with Belle- ville water-tube boilers and the latter with Scotch boilers, adds another interesting chapter to the extended discussion of the boiler question in the British navy. The letter is as follows: We have the honor to submit to your notice the following observa- tions which have occurred to us in reading the recent report by the com- mittee on water tube boilers on the trials of the cruisers Hyacinth and Minerva. We will be obliged to you if you will kindly place these ob- servations before the lords commissioners of the admiralty: Efficiency of the boilers--It appears to us of the greatest importance, in view of the controversies which have raged in print on the subject of the efficiency of Belleville boilers, to, in the first place, point out the fact that the committee recognize that these boilers show greater economy than the boilers under comparison with them. The figures in lines 46, 47 and 49 of table 25, annexed to the report, leave no doubt on this point. We give them below:. TABLE 25, LINE 46. Thermal efficiency of the boilers-- Minerva. Hyacinth. Ateabout 2.000! HP ee ence dieses vemw. sees 69.7 77.2 A about 9,000 Ee Ro a ee. neues ecideecsn « 68.0 71.8 00 ik oo neve viele ces bee ce 61.4 13.0 LINE 47. Actual evaporation per pound of coal under the conditions of the trial-- Pe 2000 TS ie ic Beas cea s 8.56 9.65 Pe ee 000 HA Peo. bes ee bees es. 8.84 9.33 Pe S000 TI oc Fie cis oss 7.93 9.39 LINE 49. Equivalent evaporation (per pound of coal) at a steam and water tem- perature of 212° F.-- ee 2 TA ee ee cee es 10.26 11.46 ee es ke ee 10.33 11.0 een O00) nett es ee 9.27 11.03 The report summarizes these observations in the following words (page 8, line 35): 'The thermal efficiency of the Hyacinth's boilers was in each case greater than that of the Minerva's at the same power and the evaporation per pound of coal from and at 212° varied, of course, in the same way. The difference is considerable at 2,000 H.P., small at 5,000 H.P., and very great at 8,000 H.P." With the object of lessening this inequality in results, and in order to better regulate the quantity of air passed through the fires in the Minerva, the committee had spirals of thin sheet iron (called retarders) inserted in the boiler tubes. The result, it is true, was somewhat better, but it was not equal to that obtained on the Hyacinth, as stated in the report. The results on the Minerva, with re- tarders, are still notably inferior to those obtained on the Hyacinth, as the following figures extracted from table 25 show: TABLE XXV. Minerva, With retarders. Hyacinth. Line 46--Thermal efficiency of boiler.... 68.4 per cent. 73.3 per cent. Line 47--Actual evaporation per pound of ee 8.84 Ibs. 9.39 Ibs. Line 49--Equivalent evaporation from and Biogle Fite... is. Pees Cepseee ~ 10.34 Ibs. 11.03 Ibs. It may here be remarked that these retarders are probably not un- connected with the choking of the ferrules with which the back ends of the Minerva's tubes are fitted, and of which mention will be made further on. As a matter of fact, the committee does not state whether similar ob- structions have been experienced during voyages of the Minerva prior to the use of these retarders. While these retarders increased the efficiency of the Minerva's boilers, without, however, making it equal to the effi- _ciency of the Hyacinth's, this relative improvement seems to have been gained only at the expense of an inconvenience elsewhere. Calorimetric tests (dryness of steam)--Before leaving this question of efficiency it will be well to say a few words about calorimetric measure- ments, made on the two cruisers during the trials, in order to ascertain the wetness of the steam. The report shows that from measurements made by a Carpenter calorimeter on the Hyacinth at less than 8,000 ra... the wetness was so small that its average value was negligible (page 10, line 60), but that when the horse power was between 8,000 and 10,000 the proportion of water indicated by the apparatus as contained in the steam was 4.7 per cent. and 6.4 per cent. respectively (ib. line 63). On the Minerva, on the contrary, the steam at these different horse powers was found to be practically dry. As a general rule calorimetric observa- tions are of an extremely delicate nature, but one may be certain that the readings of the instrument give results here which cannot be correct. Tn the first place, different positions were chosen in the Minerva and Hya- cinth for making the connections between the calorimeter and the steam to be tested. In the Minerva the calorimeter (page 6, line 14) was con- nected to the steam pipe betweén the regulating valve and the high-pres- sure valve chest of the port main engines; in the Hyacinth it was con- nected to the steam pipe in No. 5 stokehold on the boiler side of the separator. To render the results comparable it would have been necessary in the Hyacinth to make the connection near the high-pressure valve chest, as was done in the Minerva, for it is there only that the steam, purified in the separator, and wire drawn in the reducing valve, is in the condition in which it is used in the engines. The calorimeter test of the steam in the Hyacinth was therefore made under decidedly unfavorable conditions. . es iy aay eee Moreover, there is a contradiction between the statement. that, the steam in the Hyacinth showed more wetness at powers between 8,000 and _ 10,000 H.P., and the fact that these very horse powers are the only ones at which the Hyacinth's engines showed greater efficienc I ya S c y than those of the Minerva. This fact would be inexplicable if the amount of water car- ried over from the Hyacinth's boilers during the trials did in fact attain the proportions indicated by the calorimeter, for it is well known that on the contrary the efficiency of the engines very sensibly diminishes in proportion as the steam is wetter. In short, table 25 proves more clearly still, if it is possible, that the quality of the steam of the Hyacinth's Belle- ville boilers at horse powers of from 8,000 to 10,000 is not inferior to that of the Minerva's boilers. This table allows of the comparison, as regards the two vessels, of the temperature corresponding to the pressure in the valve chest of the high-pressure cylinder, and the temperature actually observed in this chest. These are the figures given in lines 9, 10 and 13, of table 25--first for the Minerva: Line 9--Mean pressure by gauge on the high-pressure valve chest 136 Ibs. Line 10--Corresponding temperature of saturated steam........ 308.5° F, Line 13--Mean observed temperature in high-pressure valve chest 345° F, Fall Of temperature: foc. oe osc: «oot ee oe eae ee 13.5° Fo Following are the figures for the Hyacinth; 8,0U0 we ue 10,000 H. P. Line 9--Mean pressure by gauge in high- Closed. Open. Open. pressure: valve chests... is 0.2 eas 194 lbs. 192 Ibs. 220 Ibs. Line 10--Corresponding temperature of saturated: Steam reas ete eles oF 385.1° 384.3° 395.4° Line 13--Mean observed temperature in high-pressure valve 'chest:.2. 004 2..0; 391.6° 389.1° 394.1° Excess of temperatures. 76602 foi. soi 2. as 6.5° ABP Aa Balls of temperature <72i5 . 253026 oes : 1.3° Therefore, in the Minerva with 8,000 H.P., the thermometer indi- cates a fall of temperature of 13.5°, as compared with the temperature corresponding to the gauge pressure, while in the Hyacinth, at 10,000 H.P., this difference is only 1.8°, and at 8,000 H.P. there is, on the con- trary, a gain of 4.8° and 6.5°, The figures for the Hyacinth given in this table undoubtedly show the steam to be perfectly dry, which is entirely in agreement with the greater efficiency of the engines at that horse power. Losses of Water--The report (page 11, line 4, etc.) contains the fol- lowing remarks on the question of loss of water: "The loss of steam through leaks in boilers, steam pipes, engine stuffing boxes, etc., is given in table 25, line 42. It is, of course, impossible to apportion the losses to their various causes, but the results of the Gibraltar runs lead us to look upon leaks at the boilers as being responsible for any abnormal increase in these losses. On the three progressive trials of the Minerva, the total losses were represented by 2.1, 3.0 and 3.7 tons of water per 1,000 H.P. per 24 hours respectively. In the Saxonia the figure was 2.76 tons. In the Hyacinth they were 5.5, 2.9 and 5.5 tons respectively, and 4.8 tons at 10,000 H.P. The irregularities here no doubt depend mainly on the actual tightness of the boiler joints during the runs. At 5,000 H.P. the Hya- cinth's losses came out very well, and slightly less than those of the Min- erva at the same power; at the other powers, both lower and higher, they were very much greater, and it was found later on, during the Gibraltar runs, that on trials of greater duration they became most serious." Thus during the trial at 5,000 H.P. the losses of water are a little less in the Hyacinth than in the Minerva; during the trials at 2,000 and 8,000 H.P., the losses are greater; on the runs to Gibraltar the losses are much more serious. Attempt was made at Gibraltar and again at Ports- mouth to discover the nature of the leaks which occasioned these losses; it does not, however, appear to have been clearly recognized at first. On the voyage out to Gibraltar a sudden slackening of speed, due to fog, had resulted in greater losses, and it was supposed that the cause might be the increase of pressure. On a special run over a free route, made during the stay at Gibraltar, the same conditions of sudden slowing down were voluntarily reproduced, with the result that the safety valves blew freely, but the tests made did not show any appreciable difference be- tween the amount of water lost before and after the slowing down (page 18, line 50). The importance of the losses, therefore, had no visible con- nection either with the speed of the engines or with the pressure in the boilers, and the question seemed involved in a certain mystery, which has been exploited to the detriment of Belleville boilers in the polemics to which the Hyacinth and Minerva trials gave rise. The question is now clearly elucidated by the experiments made with two of the Hyacinth's boilers at Devonport in December, 1901. The losses of water were measured with these boilers at first in the same state in which they were at the time of the return of this cruiser from sea service. These measurements were made during six consecutive periods of 24 hours each. The examination of the boilers showed that the losses were due exclu- sively to leaks in the joints of the handhole doors of the junction boxes, the faces of which did not bear truly against each other, while the asbestos rings were of irregular thickness and defective composition. The joints were re-made under more normal conditions, and, in a new trial, covering, like the former, a period of six times 24 hours, it was found that the loss had been reduced to less than one-tenth of its former amount. The question was thus reduced to its true proportions and placed on its proper footing. We now know which were the leaky joints, and what steps are necessary to avoid such leakage. It is at present purely a question of practice, the solution of which will daily become more certain and more easy in pro- portion as the staff, whose attention is now awakened in the right direc- tion, acquire more experience, and the materials prepared for the joints are better fitted for their purpose. This elucidation, the result of the Devonport experiments, makes it easy to understand why the question of losses of water with Belleville boilers has arisen in no other navy. although every day ships of all sorts fitted with Belleville boilers accomplish on every sea voyages which are much longer than the run from Portsmouth to Gibraltar, thereby proving that,,contrary to the opinion of the committee (page 23, line 39), water leakage is not inherent in the very design of these boilers. It is equally well known that it has not been judged necessary in any navy in which Belleville boilers are used to take any special precautions on their account, either as regards the supply or the production of fresh water. In France, for example, the apparatus fitted for producing fresh water is calculated on the same, base (4 tons of water per 24.hours per 1,000 H.P.), whether the boilers jin question are, Belleville, water tube of other types, or cylindrical. These plain facts and results of multiple and' prolonged ex- periments over so many fields of 'action ought in justice to be taken into consideration. They admit of the conclusion that the losses of water experienced during the voyage to Gibraltar are due to causes practically