Part 37 (1/2)

In the case of chain grate stokers, the desired operating conditions should bea test and for a like period before its close, the height of the throat plate and the speed of the grate being the sa of the data should be entered in notebooks or on blank sheets suitably prepared in advance This should be done in such manner that the test may be divided into hourly periods, or if necessary, periods of less duration, and the leading data obtained for any one or ree of unifors of the instruments are usually sufficient If there are sudden and wide fluctuations, the readings in such cases should be taken every 15 minutes, and in sohed and delivered to the firemen in portions sufficient for one hour's run, thereby ascertaining the degree of unifor An ample supply of coal should be maintained at all times, but the quantity on the floor at the end of each hour should be as small as practicable, so that the saht

The records should be such as to ascertain also the consuree of uniformity of evaporation

9 QUALITY OF STEAM[67]

If the boiler does not produce superheated steae of moisture in the stea or separating calori surface, the temperature of the steam should be determined by the use of a thermometer inserted in a ther pipe or nozzle made of one-half inch iron pipe and insert it in the steam main at a point where the entrained hly mixed The inner end of the pipe, which should extend nearly across to the opposite side of the main, should be closed and interior portion perforated with not less than twenty one-eighth inch holes equally distributed froular or spiral roith the first hole not less than half an inch fro pipe should not be placed near a point where water may pocket or where such water may effect the amount of moisture contained in the sample Where non-return valves are used, or there are horizontal connections leading from the boiler to a vertical outlet, water may collect at the lower end of the uptake pipe and be bloard in a spray which will not be carried away by the stea to a lack of velocity A sareater aoose-neck connections a small amount of water may collect on the bottom of the pipe near the upper end where the inclination is such that the tendency to flow backward is ordinarily counterbalanced by the flow of steam forward over its surface; but when the velocity momentarily decreases the water flows back to the lower end of the goose-neck and increases theit an undesirable location for sa In any case it must be borne in mind that with low velocities the tendency is for drops of entrained water to settle to the bottom of the pipe, and to be temporarily broken up into spray whenever an abrupt bend or other disturbance isnozzle at a point near the end of a long horizontal run, a drip pipe should be provided a short distance in front of the nozzle, preferably at a pocket for the bottohed, and added to the moisture shown by the calorimeter; or, better, a steam separator should be installed at the point noted

In testing a stationary boiler the sa pipe should be located as near as practicable to the boiler, and the saards the therine or turbine test these locations should be as near as practicable to throttle valve

In the test of a plant where it is desired to get complete infor, sa nozzles or thermometer wells should be provided at both points, so as to obtain data at either point as may be required

10 SAMPLING AND DRYING COAL

During the progress of test the coal should be regularly sampled for the purpose of analysis and determination of moisture

Select a representative shovelful from each barrow-load as it is drawn from the coal pile or other source of supply, and store the samples in a cool place in a covered metal receptacle When all the coal has thus been sahly mix the whole quantity, and finally reduce it by the process of repeated quartering and crushi+ng to a sa about the size of a pea Frolass fruit jars, or other air-tight vessels, are to be promptly filled and preserved for subsequent determinations of moisture, calorific value, and chemical composition These operations should be conducted where the air is cool and free from drafts

[Illustration: 3460 Horse-power Installation of Babcock & Wilcox Boilers at the Chicago, Ill, Shops of the Chicago and Northwestern Ry Co]

When the sa to, say, 100 pounds, a portion weighing, say, 15 to 20 pounds should be withdrawn for the purpose of immediate moisture determination This is placed in a shallow iron pan and dried on the hot iron boiler flue for at least 12 hours, being weighed before and after drying on scales reading to quarter ounces

The moisture thus determined is approximately reliable for anthracite and se much inherent moisture For such coals, and for all absolutely reliable determinations the method to be pursued is as follows:

Take one of the salass jars, and subject it to a thorough air drying, by spreading it in a thin layer and exposing it for several hours to the at it before and after, thereby deter the quantity of surface moisture it contains[68] Then crush the whole of it by running it through an ordinary coffee mill or other suitable crusher adjusted so as to produce sohly mix the crushed sarah it in a balance which will easily show a variation as small as 1 part in 1000, and dry it for one hour in an air or sand bath at a teh it and record the loss, then heat and weigh again until the ht has been reached The difference between the original and the ht is the moisture in the air-dried coal The sum of the moisture thus found and that of the surface moisture is the total moisture

11 ASHES AND REFUSE

The ashes and refuse withdrawn froress of the test and at its close should be weighed so far as possible in a dry state If wet the amount oftaken and dried for this purpose This sample may serve also for analysis and the deter te coala sample of the ashes and refuse