Part 58

The data and results should be reported in accordance with either the short form or the complete form, adding lines for data not provided for, or omitting those not required, as may conform to the object in view.

17. CHART

In trials having for an object the determination and exposition of the complete boiler performance, the entire log of readings and data should be plotted on a chart and represented graphically.

18. TESTS WITH OIL AND GAS FUELS

Tests of boilers using oil or gas for fuel should accord with the rules here given, excepting as they are varied to conform to the particular characteristics of the fuel. The duration in such cases may be reduced, and the "flying" method of starting and stopping employed.

The table of data and results should contain items stating character of furnace and burner, quality and composition of oil or gas, temperature of oil, pressure of steam used for vaporizing and quantity of steam used for both vaporizing and for heating.

TABLE DATA AND RESULTS OF EVAPORATIVE TEST SHORT FORM, CODE OF 1912

1 Test of.................boiler located at................................ to determine...............conducted by.............................. 2 Kind of furnace.......................................................... 3 Grate surface.................................................square feet 4 Water-heating surface.........................................square feet 5 Superheating surface..........................................square feet 6 Date..................................................................... 7 Duration............................................................hours 8 Kind and size of coal....................................................

AVERAGE PRESSURES, TEMPERATURES, ETC.

9 Steam pressure by gauge............................................pounds 10 Temperature of feed water entering boiler.........................degrees 11 Temperature of escaping gases leaving boiler......................degrees 12 Force of draft between damper and boiler...........................inches 13 Percentage of moisture in steam, or number degrees of superheating..................per cent or degrees

TOTAL QUANTITIES

14 Weight of coal as fired........................................pounds 15 Percentage of moisture in coal...................................per cent 16 Total weight of dry coal consumed..................................pounds 17 Total ash and refuse...............................................pounds 18 Percentage of ash and refuse in dry coal.........................per cent 19 Total weight of water fed to the boiler........................pounds 20 Total water evaporated, corrected for moisture in steam............pounds 21 Total equivalent evaporation from and at 212 degrees...............pounds

HOURLY QUANTITIES AND RATES

22 Dry coal consumed per hour.........................................pounds 23 Dry coal per square feet of grate surface per hour.................pounds 24 Water evaporated per hour corrected for quality of steam...........pounds 25 Equivalent evaporation per hour from and at 212 degrees............pounds 26 Equivalent evaporation per hour from and at 212 degrees per square foot of water-heating surface........................pounds

CAPACITY

27 Evaporation per hour from and at 212 degrees (same as Line 25).....pounds 28 Boiler horse power developed (Item 27÷34½).............boiler horse power 29 Rated capacity, in evaporation from and at 212 degrees per hour....pounds 30 Rated boiler horse power...............................boiler horse power 31 Percentage of rated capacity developed...........................per cent

ECONOMY RESULTS

32 Water fed per pound of coal fired (Item 19÷Item 14)................pounds 33 Water evaporated per pound of dry coal (Item 20÷Item 16)...........pounds 34 Equivalent evaporation from and at 212 degrees per pound of dry coal (Item 21÷Item 16)...................................pounds 35 Equivalent evaporation from and at 212 degrees per pound of combustible [Item 21÷(Item 16-Item 17)]......................pounds

EFFICIENCY

36 Calorific value of one pound of dry coal.........................B. t. u. 37 Calorific value of one pound of combustible......................B. t. u.

( Item 34×970.4) 38 Efficiency of boiler, furnace and grate (100 × -------------)....per cent ( Item 36 )

( Item 35×970.4) 39 Efficiency of boiler and furnace (100 × -------------)...........per cent ( Item 37 )

COST OF EVAPORATION

40 Cost of coal per ton of......pounds delivered in boiler room......dollars 41 Cost of coal required for evaporating 1000 pounds of water from and at 212 degrees........................................dollars

THE SELECTION OF BOILERS WITH A CONSIDERATION OF THE FACTORS DETERMINING SUCH SELECTION

The selection of steam boilers is a matter to which the most careful thought and attention may be well given. Within the last twenty years, radical changes have taken place in the methods and appliances for the generation and distribution of power. These changes have been made largely in the prime movers, both as to type and size, and are best illustrated by the changes in central station power-plant practice. It is hardly within the scope of this work to treat of power-plant design and the discussion will be limited to a consideration of the boiler end of the power plant.

As stated, the changes have been largely in prime movers, the steam generating equipment having been considered more or less of a standard piece of apparatus whose sole function is the transfer of the heat liberated from the fuel by combustion to the steam stored or circulated in such apparatus. When the fact is considered that the cost of steam generation is roughly from 65 to 80 per cent of the total cost of power production, it may be readily understood that the most fruitful field for improvement exists in the boiler end of the power plant. The efficiency of the plant as a whole will vary with the load it carries and it is in the boiler room where such variation is largest and most subject to control.

The improvements to be secured in the boiler room results are not simply a matter of dictation of operating methods. The securing of perfect combustion, with the accompanying efficiency of heat transfer, while comparatively simple in theory, is difficult to obtain in practical operation. This fact is perhaps best exemplified by the difference between test results and those obtained in daily operation even under the most careful supervision. This difference makes it necessary to establish a standard by which operating results may be judged, a standard not necessarily that which might be possible under test conditions but one which experiment shows can be secured under the very best operating conditions.