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MARINE REVIEW AND MARINE RECORD. | Noy. 20. f water. in inches o » | | | 7 12 z 19 -- ' » | | - eof es es us ae Se o" i 4 v | -- 6B. em a! S=$--~. < : | " Be = eres mn NE Le) \ QA See. Se 3 =~ 8 = Fon Bes ~"g Combustion 6 so --Fur--*:= = Abscissas are roughly proportional to measurements along the path of gases. © | y | a | | | | 7 | ie | i | mie - | | ee ee > ee e Above "-----*? tubes Se ee ee a. ee a ee SS or:= eat aes at S>== > » = ------ \ i Fig. 3. Curves showing Variation of Air Pressure within the Boiler during certain Coal Burning Trials. Spots indicate points where measurements were made. diameter and a discharge duct 20 ins. by 42 ins., which led to the fire room and terminated in a box placed so as to direct the air current toward the ceiling. The pipe connections were such that steam for the auxiliaries could be taken either from the small upright boiler or from the main boiler. 'The bottom blow valve was blanked, but in plain sight, so that leakage from that source would be particularly observed. ARRANGEMENTS FOR THE EXPERIMENTS. The feed water was weighed in two tanks, each of 1,000 lbs. capacity, and resting on 1,500-lb. Howe scales. 'These scales had been tested by the city's sealer of weights and measures. 'The scales and weighing tanks were on a platform above the feed tank. The weight of each tank was taken when filled, and the water was then allowed to flow into the feed tank as needed. As scon as the weighing tank was emptied the weight was again _taken and the time noted. The feed tank was provided with a graduated water-level gauge. The height of water by this gauge was noted at the moment of beginning the test, and at the end of each hour it was again brought to the same level. 'The feed tank had a steam coil for heating the water, wide variations in the temperature of which were easily avoided by keeping the water level fairly constant. In most cf the forced-draft trials the weighing tanks had to be filled, weighed, and emptied with such rapidity, owing to their insufficient size, that the above method of catching their weight at the end of each hour could not be used. The weighing tanks were according each fitted with a water-level gauge graduated to 5 lbs., by the aid of which the weight within 5 Ibs. could be caught at any moment without in- _ verfering with the rapid manipulation of the tanks. The tempera- ture of the feed water was taken at an elbow of the feed pipe be- tween the pump and the boiler. The several air pressure gauges and two steam gauges were placed near each other on the wall of the steel structure, dn the opposite or fire room side of which the necessary pipe connections were made. The steam gauges were 3 ft. lower than the water level in the- boiler. A deduction of 1% lbs, from the observed steam pressures was therefore made in working up the results. The steam was blown off into the atmosphere, the pressure being controlled by a hand-operated stop valve. The coal was weighed in sheet-metal cans or bags, the method being to adjust each can or bag to a uniform weight of 220 lbs., _ or 130 Ibs. while on the scales, and then keep tally of the number passed into the fire room. Beginning 'with the seventh test, the coal account was balanced at the end of each hour by estimating and deducting the weight of coal lying at the moment on the fire room floor. The ashes and refuse were weighed in sheet-metal cans as they accumulated, and the weight of sweepings from tubes and baffles was ascertained for each test on the day following the _ test. A sample of coal for analysis and for the determination of moisture by weighing and drying was taken from a box which had been gradually filled during the test by specimens taken from: each can or bag as weighed. The following table gives the re- sults of analysis of samples of each lot of coal. The analyses were made by the chemist at the New York navy yard. Analyses of Fuel. Pocahon- New tas coal, Pocahontas coal, River hand run of mine. coa!,run} picked of mine. and screened. Fuel burned in boiler test No.-- F283: 4, 5,6. 7,8,9. | 10to17 Per cent. | Per cent. | ter cent. | Per cent Proximate Analysis. Bixed Carbon a)... 0 ak 73.30 75.78 72.99 76.81 Volatile. Matter cn oo so. e , 17.61 19.58 21.79 19.62 MOUStIte: 6 49 19 AQ £73 AIS aS re ee eas 8.60 3.90 4.73 2.84 100 100 100 100 Sulphur, separately determined..... : 48 TL 46 82 Ultimate Analysis. Carbone i yar ek 82.26 84.96 83.60 85.94 Eydtogcen® Guna ae 3.89 4.07 4 85 4.45 Oxysen (Gey Ae: ae: 4,12 5.46 4.87 4.50 Nitrogen. e50 (eee : ae 64 90 1.41 1.14 OT Oe ee .49 UL 46 82 MSNA eS ee ee 8.60 3.90 4.81 3.15 100 100 100 100 Calorific value (B. T. U.'s per lb), Ot ee er 14,067 14,534 14,841 14,992 Combustible. oe ee 15,391) 15,124) 15,684 15,475 The quality of the steam was determined by means of a Barrus throttling calorimeter, which drew steam from the main steam pipe at a point 8 ins. from the boiler. 'The sampling nozzle consisted of a 14-in. pipe reaching nearly across the steam pipe on a horizontal diameter and having four rows of perforations (top, bottom and sides) extending the length of the diameter of the inside of the steam pipe, save for one-half inch at each end An extra calorimeter was fitted and readings were taken from beth calorimeters throughout the series of trials, except when, as once occurred, the extra calorimeter got out of order by the lodg- ment of black scale in its throttle orifice. The temperatures at the base of the stack and the samples of tlue gas were taken above the roof at a point about 5 ft. from the nearest heating surface of the boiler, measured along the path of flow of the gases. In the nat- ural draft trials the temperatures were taken with a mercury-nitro gen pyrometer, and attempts were made to do the same in the forced-draft trials. Momentary flaming in the stack, however, caused so many breakages of glass bulbs that reliance had finally to be placed on a Brown quick-reading pyrometer, the readings of