,,united ,,states ,,fuel ,,administration ,,bureau ,,of ,,conservation ,engineering ,bulletin ,no4 #a ,,boiler ,,and ,,furnace ,,testing ,rufus ,t4 ,strohm ,associate ,editor1 ,power ,illustration3 ,maximum ,production ,minimum ,waste ,,washington ,,government ,,printing ,,office #aiah ---------------------------------------- ------------------------------ ,,maximum ,,production4 ,,minimum ,,waste4 ,the ,united ,states ,fuel ,administration is making every effort1 through the producers and transportation lines1 to obtain an adequate supply of fuel for the industries of the country4 ,twenty-five to fifty million tons of coal a year can be saved by the improved operation of steam-power plants without changing their present equipment and without abating their production the slightest4 ,it is absolutely necessary that this saving be realized1 if our overburdened railroads are to be relieved and our industries kept in full operation4 ,the extent to which it will be realized depends upon the cooperation of the owners1 engineers1 and firemen of every power plant of the country4 ,,your ,,firing ,,line ,,is ,,at ,,the ,,furnace ,,door4 ,,david ,,moffat ,,myers1 ,advisory ,engineer to ,united ,states ,fuel ,administration4 ---------------------------------------- ------------------------------ ,,boiler ,,and ,,furnace ,,testing4 ,by ,,rufus ,t4 ,,strohm4 ,,necessity ,,for ,,testing ,,boilers4 ,a boiler test is necessary in order to determine how well the boiler is doing the work expected of it2 that is to say1 we must find out whether we are wasting coal in making steam and how much this waste may be4 ,such a test may be made to discover the efficiency of the boiler1 or the quantity of water it is evaporating1 or the cost of evaporating #a1jjj pounds of water4 ,the ,united ,states ,fuel ,administration recommends that every boiler plant have some means of daily checking the efficiency of the boiler and furnace4 ,the simplest and best way of finding out how efficiently the boiler is working is to make an evaporation test1 as described in this bulletin4 ,all the necessary records can be made automatically with suitable instruments1 although in many small plants the coal must be weighed on ordinary scales4 ,the efficiency of the furnace can be found by making analyses of the flue gases4 7,see ,bulletin ,no4 #b of the ,united ,states ,fuel ,administration47 ,too many engineers and firemen have the idea that they are not fitted to make boiler tests4 ,this is altogether wrong4 ,any man who can weigh water and coal and read steam gages and thermometers is able to do the work required in making a boiler test for evaporation or efficiency4 ,such a test requires a knowledge of the following3 #a4 ,the total weight of coal used4 #b4 #a,the total weight of water fed to and evaporated by the boiler4 #c4 ,the average temperature of the feed water4 #d4 ,the average steam pressure in the boiler4 ,if these four items are known1 a series of simple calculations will show how much water is being evaporated per pound of coal1 and the efficiency of the boiler and furnace4 ,to make a test1 the following apparatus and instruments are necessary3 #a4 ,scales to weigh the coal4 #b4 ,apparatus to weigh or measure the feed water4 #c4 ,thermometers to take feed-water temperature4 #d4 ,gages to indicate steam pressure4 ,a boiler test to be of value should extend over a period of at least eight hours4 ,the longer the test the more accurate the results4 ,footnote #a3 ,for the sake of simplicity1 only the essential elements of boiler and furnace testing are treated in this bulletin4 ,for rules covering the refinements for an exhaustive test1 the reader is referred to the boiler test code of the ,american ,society of ,mechanical ,engineers4 ,copies of this code can be obtained from the secretary1 #bi ,west ,thirty-ninth ,street1 ,new ,york ,city4 ,,weighing ,,the ,,coal4 ,the weight of coal used during a test may easily be found by using an ordinary wheelbarrow and a platform scales1 arranged as in figure #a4 ,at each side of the scales build an incline with its top level with the top of the platform1 but take care not to have either one touch the platform4 ,set the empty wheelbarrow on the scales1 run the movable weight or poise out until it exactly balances the weight of the barrow and lock it in position with the thumbscrew4 ,next1 put weights on the scale pan ,a to correspond to a net weight of #bej or #cjj pounds of coal4 ,fill the barrow with coal1 run it on the scales1 and add coal or take off coal until the scales balance4 ,this is easily done by having a small pile of coal ,b beside the scales4 ,if the weights on the scale pan represent1 say1 #cjj pounds1 the net weight of coal in the barrow is exactly #cjj pounds4 ,this coal is wheeled in front of the boiler and dumped on the clean floor1 and the barrow is returned for another load4 ,illustration3 ,fig4 #a4 #a ,set to balance tare of wheelbarrow #b ,add to balance net weight of coal ,each time the barrow of coal is weighed on the scales and taken to the boiler being tested1 a tally mark should be made on a board nailed to the wall beside the scales4 ,each tally mark represents #cjj pounds of coal1 since the amount of coal in the barrow is adjusted at each weighing1 so that the scales just balance4 ,at the end of the test1 therefore1 the number of tally marks is multiplied by #cjj1 and the product is the weight of coal used1 provided it has all been fired2 but if any coal remains in front of the boiler at the close of the test1 it must be gathered up and weighed1 and its weight must be subtracted from the total weight indicated by the tally marks to get the number of pounds of coal actually fired4 ,you should1 of course1 start the test with no coal in front of the boiler4 ,care must be taken not to forget to make a tally mark each time a barrow of coal is run off the scales4 ,by setting the scales so as to show any net weight1 such as #bej or #cjj pounds1 and making each barrow load exactly this weight1 much time is saved1 as it is unnecessary to change any of the weights or the position of the rider on the scale beam4 ,if the coal used in the test is to be analyzed1 take a sample of from #d to #f pounds from each barrow and throw it into a box near the scales4 ,do this before the coal is weighed4 ,these small amounts from the various barrow loads will then give a fair average sample of the coal used during the test4 ,the condition of the furnace should be the same at the end of the test period as at the start4 ,therefore1 at the moment the test is begun1 observe the thickness of the fuel bed and the condition of the fire4 ,if the fire was cleaned1 say1 an hour before the test began1 see that it is cleaned an hour before the time when the test is scheduled to end4 ,if the coal was fired1 say1 eight minutes before the test started1 the last coal used during the test should be fired eight minutes before the end of the test4 ,the object of these precautions is to insure the same conditions at start and finish1 as nearly as possible2 otherwise1 the coal weighed will not be the same as the coal consumed4 ,,measuring ,,the ,,feed ,,water4 ,the quantity of water fed to the boiler during the test may be found by metering or by weighing4 ,a reliable water meter is recommended for this work4 ,there are a number of good makes1 of different types1 such as3 #a4 ,venturi meter4 #b4 ,weir or ,v-notch meters4 #c4 ,diaphragm meters4 #d4 ,displacement meters4 #e4 ,water weighers4 ,the best form of meter to use in any particular case depends on the local conditions in the plant2 but every plant should be provided with a permanently installed meter of some type4 ,the displacement form of meter should be used only with cold water1 however4 ,if there is no meter or water weigher in the plant1 the feed water used during the test can be measured by the three-barrel arrangement illustrated in figure #b4 ,obtain three water-tight barrels1 and set two of them close together on a platform directly over the third1 leaving about #ab inches above barrel #c in which to fit the valves ,v and the nipples in the bottoms of barrels #a and #b4 ,near the top of each of the barrels #a and #b screw a #a-;inch overflow pipe ,o4 ,run a pipe ,p from the city main or other source of supply above barrels #a and #b1 and put a valve ,a on the pipe leading to each barrel4 ,from barrel #c run a suction pipe to the feed pump that is to pump water to the boiler to be tested4 ,it is best to have a by-pass from the usual water supply direct to the feed pump1 or to another pump connected to the boiler1 so that in case of any trouble with the testing barrels1 the regular operation of the boiler may be resumed without shutting down4 ,the next step is to fill barrels #a and #b with water until they overflow at ,o4 ,this water should be of practically the same average temperature as that which is to be used during the test4 ,barrel #c should be high enough above the feed pump so that the pump will handle hot water4 ,put barrel #c on a scales1 before connecting it to the feed pump1 and weigh it4 ,then let the water from barrel #a run into barrel #c1 and weigh again4 ,the second weight minus the first weight is the net weight of water run in from barrel #a and is the weight of water contained in barrel #a when filled to the overflow4 ,the weight of water in barrel #b when it is filled to the overflow can be found in like manner4 ,mark these weights down4 ,illustration3 ,fig4 #b4 ,when the net weights are found and barrel #c is removed from the scales and connected to the feed pump1 the apparatus is ready to begin the test4 ,start with the level of the water about #a foot below the top of the barrel #c1 and drive a nail into the barrel to mark this level4 ,when the test is finished1 the level should be brought to the same point1 so that the water that has passed through barrels #a and #b will accurately represent the weight of water fed to the boiler during the test4 ,when the test is to begin1 stop the feed pump and tie a string around the gage glass on the boiler to mark the height of the water level in the boiler4 ,then start the pump connected to barrel #c4 ,fill barrels #a and #b up to the overflow before the test is started4 ,then open the valve ,v on barrel #a and let the water run into barrel #c as fast as the feed pump draws water from barrel #c4 ,when barrel #a is emptied close its valve ,v and open its valve ,a so as to refill it4 ,while barrel #a is filling empty barrel #b into barrel #c in the same way1 and continue to fill and empty barrels #a and #b alternately4 ,in this way barrel #c will be kept supplied with water that has been measured in barrels #a and #b1 the net weights of which were found before the test began4 ,keep a separate tally of the number of times each of the barrels #a and #b is emptied into barrel #c4 ,at the end of the test the number of tallies for each barrel multiplied by the weight of the water that barrel will hold will be the weight of water measured in that barrel4 ,the sum of these weights for barrels #a and #b will be the weight of water used in the test4 ,with a three-barrel arrangement like this1 water can be weighed rapidly enough to supply #cjj boiler horsepower4 ,before starting a test make sure that there is no chance for water to leak into or out of the boiler4 ,see that the blow-off is tight1 that there is no drip from gage cocks1 and that the feed-line connections are tight1 so that all the water fed to the boiler will represent accurately the amount evaporated during the test4 ,if a meter is used instead of the three-barrel method1 make absolutely sure that the meter is correct1 as the accuracy of the test depends on the accuracy with which the water measurements are made4 ,after a meter is installed1 test it to see that it operates correctly under the plant conditions4 ,the water level in the boiler should be the same at the end of the test as at the beginning4 ,as the time for stopping the test draws near1 therefore1 try to bring the conditions the same as at the start4 ,do not1 however1 run the feed pump rapidly in the last few minutes for the test in order to obtain the same water level4 ,if there is a slight difference in level1 calculate the weight of water it represents and make the necessary correction to the total weight of water fed4 ,,temperature ,,of ,,feed ,,water4 ,every plant should have a thermometer on the feed line1 so as to find the temperature of the feed water4 ,preferably1 this thermometer should be of the recording type4 ,if such a form of thermometer is used during the test1 it is unnecessary to take the feed temperature at stated intervals1 as the record will show the varying temperatures1 and so the average feed temperature during the test can easily be found4 ,if there is no thermometer in the feed line1 take the feed-water temperature by means of a thermometer hung in barrel #c 7figure #b7 by a hook over the edge of the barrel4 ,read this thermometer every half hour during the test if the feed-water temperature is fairly uniform2 but if it varies considerably1 read the thermometer every #ae minutes4 ,the object is to obtain the average feed-water temperature during the test period4 ,therefore1 mark down the temperatures as read at the stated intervals4 ,at the close of the test add the readings and divide their sum by the number of readings and you will have the average temperature of the feed water4 ,,steam ,,pressure4 ,every boiler is fitted with a steam gage by which the pressure is indicated4 ,it is important that the pressure gage be accurate4 ,what is wanted in a test is the average pressure of the steam in the boiler1 therefore1 observe the pressure at regular intervals1 just as with the feed-water temperature1 and mark down these gage readings4 ,the sum of the readings divided by the number of readings taken will be the average steam pressure during the test4 ,a recording steam gage is best and makes its own readings4 ,,working ,,up ,,the ,,test4 ,after the boiler test has been made1 so as to find the weight of coal burned1 weight of feed water used1 feed-water temperature and steam pressure1 the efficiency1 the horsepower1 and the economy must be obtained by calculation from the test results4 ,the process of figuring the desired results from the test data is called working up the test4 ,to illustrate the method used in finding the efficiency1 etc41 suppose that the data obtained from the test are as follows3 ,length of test hours #aj ,total weight of coal fired pounds #e1jjj ,total weight of water evaporated do4 #ce1jjj ,average temperature of feed water ,f #ahj ,average steam pressure1 gage pounds per square inch #ajj ,the efficiency of any process is always a comparison1 or ratio1 of the output to the input4 ,in the case of a steam boiler the efficiency is the percentage of the heat supplied in the coal that is usefully employed in making steam4 ,the output of the steam boiler is the heat represented by the quantity of water evaporated by a pound of coal1 taking into account the feed temperature and the steam pressure1 and input is the amount of heat contained in a pound of the coal used4 ,the efficiency of the boiler is the output divided by the input4 ,the heat contained in a pound of coal is called the calorific value or heating value of the coal4 ,it can be found by taking a fair average sample of the coal used during the test1 as explained in connection with weighing the coal1 and sending the sample to a chemist1 who will make a calorimeter test to determine its heating value4 ,at the end of the test the sample fuel should be spread out on a clean floor and all lumps broken up1 so that no pieces are larger than #b inches maximum diameter4 ,then the gross sample should be very thoroughly mixed by shoveling1 after which it should be spread out in the form of a square of uniform depth and quartered down until a final average sample is obtained for shipment to a competent chemist1 experienced in fuel analysis4 7,see ,bureau of ,mines ,technical ,paper ,no4 #acc47 ,about #b quarts of the chemist's sample should be put in air-tight tins or jars for the determination of moisture2 the balance of the sample 7the total weight of which should be from #aj to #ej pounds1 depending on the total weight of coal used in the test7 may be packed in a wooden box lined with paper to prevent splinters from mingling with the sample4 ,a duplicate coal sample should be kept at the plant to be used in case of loss of the sample sent to the chemist4 ,the ,bureau of ,mines has published a bulletin or pamphlet giving the analyses and heating values of the various kinds and grades of coal from all parts of the ,united ,states4 7,bureau of ,mines ,bulletin ,no4 #bb47 ,this bulletin can be used to learn the approximate heating value of the coal4 ,simply find out what district the coal used in the test came from1 and its grade1 and then refer to the bulletin to obtain the heating value of the coal4 ,if a chemist can be obtained to make a heat test1 however1 it is better to use the heating value he determines4 ,suppose that during the test the coal used was run-of-mine bituminous having a heating value of #ac1ejj ,b4 t4 u4 ,every pound of coal fired1 then1 carried into the furnace #ac1ejj heat units1 and this value therefore is the input to be used in calculating the boiler efficiency4 ,during the test #e1jjj pounds of coal was fired and #ce1jjj pounds of water was fed and evaporated4 ,this means that #ce1jjj #e1jjj #g pounds of water was evaporated per pound of coal burned4 ,this is the actual evaporation1 and the heat required to evaporate this #g pounds of water is the output to be used in calculating the efficiency4 ,every fireman knows that it takes more coal1 and therefore more heat1 to make steam with cold feed water than with hot feed water2 also1 that it is somewhat easier to make steam at a low pressure than at a high pressure4 ,so it is plain that the heat required to evaporate #g pounds of water into steam depends on two things1 namely1 7#a7 the temperature of the feed water and 7#b7 the pressure of the steam in the boiler4 ,from the data of the test1 both the average feed-water temperature and the average steam pressure are known1 and so it is a simple matter to find out the amount of heat needed to evaporate #g pounds of water from the average temperature to steam at the average pressure4 ,a pound of water at #bab ,f4 must have #igj4d ,b4 t4 u4 added to it to become a pound of steam at #bab ,f41 or zero gage pressure4 ,this value1 #igj4d ,b4 t4 u41 is called the latent heat of steam at atmospheric pressure1 or the heat from and at #bab ,f4 ,it is the heat required to change a pound of water from #bab ,f4 to steam at #bab ,f41 and is used by engineers as a standard by which to compare the evaporation of different boilers4 ,in a boiler test the temperature of the feed water is usually something less than #bab ,f41 and the steam pressure is commonly higher than zero1 gage4 ,in the test outlined previously1 the feed-water temperature was #ahj ,f4 and the pressure was #ajj pounds per square inch1 gage4 ,it must be clear1 then1 that the amount of heat required to change a pound of water at #ahj to steam at #ajj pounds gage pressure is not the same as to make a pound of steam from and at #bab ,f4 ,to make allowance for the differences in temperature and pressure1 the actual evaporation must be multiplied by a number called the factor of evaporation4 ,the factor of evaporation has a certain value corresponding to every feed-water temperature and boiler pressure1 and the values of this factor are given in the accompanying table4 ,along the top of the table are given the gage pressures of the steam4 ,in the columns at the sides of the table are given the feed-water temperatures4 ,to find the factor of evaporation for a given set of conditions1 locate the gage pressure at the top of the table and follow down that column to the horizontal line on which the feed-water temperature is located4 ,the value in this column and on the horizontal line thus found is the factor of evaporation required4 ,if the feed water has a temperature greater than #bab ,f41 obtain the proper factor of evaporation from the ,marks and ,davis steam tables4 ,take the data of the test1 for example4 ,the average steam pressure is #ajj pounds1 gage4 ,the average feed-water temperature is #ahj ,f4 ,so1 in the table locate the column headed #ajj and follow down this column to the line having #ahj at the ends1 and the value where the column and the line cross is #a4jgbg1 which is the factor of evaporation for a feed-water temperature of #ahj ,f4 and a steam pressure of #ajj pounds1 gage4 ,this factor1 #a4jgbg1 indicates that to change a pound of water at #ahj ,f4 to steam at #ajj pounds requires #a4jgbg times as much heat as to change a pound of water at #bab ,f4 to steam at atmospheric pressure4 ,in other words1 the heat used in producing an actual evaporation of #g pounds under the test conditions would have evaporated #g #a4jgbg #g4e pounds from and at #bab ,f4 ,hence1 #g4e pounds is called the equivalent evaporation from and at #bab ,f4 per pound of coal used4 ,as already stated1 it takes #igj4d ,b4 t4 u4 to make a pound of steam from and at #bab ,f4 ,then to make #g4e pounds there would be required #g4e #igj4d #g1bgh ,b4 t4 u4 ,this is the amount of heat required to change #g4e pounds of water at #bab ,f4 to steam at zero gage pressure1 but it is also the heat required to change #g pounds of water at #ahj ,f4 to steam at #ajj pounds gage pressure1 because #g4e pounds from and at #bab ,f4 is equivalent to #g pounds from #ahj ,f4 to steam at #ajj pounds4 ,therefore1 the #g1bgh ,b4 t4 u4 is the amount of heat usefully employed in making steam per pound of coal fired1 and so it is the output4 ,accordingly1 the efficiency of the boiler is-- ,output #g1bgh ,efficiency ------ ------ #j4ed1 nearly4 ,input #ac1ejj ,in other words1 the efficiency of the boiler is #j4ed1 or #ed per cent1 which means that only a little more than half of the heat in the coal is usefully employed in making steam4 ,the chart shown in figure #c is given to save the work of figuring the efficiency4 ,if the equivalent evaporation per pound of coal is calculated and the heating value of the coal is known1 the boiler efficiency may be found directly from the chart4 ,at the left-hand side locate the point corresponding to the equivalent evaporation and at the bottom locate the point corresponding to the heating value of the coal4 ,follow the horizontal and vertical lines from these two points until they cross1 and note the diagonal line that is nearest to the crossing point4 ,the figures marked on the diagonal line indicate the boiler efficiency4 ,take the case just worked out1 for example4 ,the equivalent evaporation is #g4e pounds and the heating value of the fuel is #ac1ejj ,b4 t4 u4 ,at the left of the chart locate the point #g4e midway between #g and #h and at the bottom locate the point #ac1ejj midway between #ac1jjj and #ad1jjj4 ,then follow the horizontal and vertical lines from these two points until they cross1 as indicated by the dotted lines4 ,the crossing point lies on the diagonal corresponding to #ed1 and so the efficiency is #ed per cent4 ,,boiler ,,horsepower ,,or ,,capacity4 ,the capacity of a boiler is usually stated in boiler horsepower4 ,a boiler horsepower means the evaporation of #cd4e pounds of water per hour from and at #bab ,f4 ,therefore1 to find the boiler horsepower developed during a test1 calculate the evaporation from and at #bab ,f4 per hour and divide it by #cd4e4 ,take the test previously mentioned1 for example4 ,the evaporation from and at #bab ,f4 or the equivalent evaporation1 was #g4e pounds of water per pound of coal4 ,the weight of coal burned per hour was #e1jjj #aj #ejj pounds4 ,then the equivalent evaporation was #g4e #ejj #c1gej pounds per hour4 ,according to the foregoing definition of a boiler horsepower1 then-- #c1gej ,boiler horsepower ----- #aji4 #cd4e ,the rated horsepower of a boiler1 or the builders' rating1 is the number of square feet of heating surface in the boiler divided by a number4 ,in the case of stationary boilers this number is #aj or #ab1 but #aj is very commonly taken as the amount of heating surface per horsepower4 ,assuming this value and assuming further that the boiler tested had #a1ejj square feet of heating surface1 its rated horsepower would be #a1ejj #aj #aej boiler horsepower4 ,it is often desirable to know what per cent of the rated capacity is developed in a test4 ,this is found by dividing the horsepower developed during the test by the builders' rating4 ,in the case of the boiler tested1 #aji horsepower was developed4 ,the percentage of rated capacity developed1 therefore1 was #aji #aej #j4gc1 or #gc per cent4 ,,heating ,,surface4 ,the heating surface of a boiler is the surface of metal exposed to the fire or hot gases on one side and to water on the other side4 ,thus1 the internal surface of the tubes of a fire-tube boiler is the heating surface of the tubes1 but the outside surface of the tubes of a water-tube boiler is the heating surface of those tubes4 ,in addition to the tubes1 all other surfaces which have hot gases on one side and water on the other must be taken into account4 ,for instance1 in a fire-tube boiler from one-half to two-thirds of the shell 7depending on how the boiler is set7 acts as heating surface4 ,in addition to this1 the surface presented by both heads1 below the water level1 has to be computed4 ,the heating surface of each head is equal to two-thirds its area minus the total area of the holes cut away to receive the tubes4 ,,cost ,,of ,,evaporation4 ,the cost of evaporation is usually stated as the cost of fuel required to evaporate #a1jjj pounds of water from and at #bab ,f4 ,to find it1 multiply the price of coal per ton by #a1jjj and divide the result by the product of the equivalent evaporation per pound of coal and the number of pounds in a ton4 ,suppose that the cost of the coal used in the foregoing test was #c4fj per ton of #b1jjj pounds4 ,the equivalent evaporation per pound of coal was #g4e pounds4 ,therefore the cost of evaporating #a1jjj pounds of water from #ahj ,f4 to steam at #ajj-pound gage1 is-- #c4fj #a1jjj ------------- #j4bd1 or #bd cents4 #g4e #b1jjj ,,table ,,of ,,test ,,results4 ,after the test has been made and properly worked up1 as heretofore described1 collect all the results of the test on one sheet1 so that they can be kept in convenient form for reference and for comparison with later tests4 ,a brief form of arranging the results is as follows3 #a4 ,date of test ,may #bj1 #aiah #b4 ,duration of test hours #aj #c4 ,weight of coal used pounds #e1jjj #d4 ,weight of water fed and evaporated do4 #ce1jjj #e4 ,average steam pressure1 gauge do4 #ajj #f4 ,average feed-water temperature ,f4 #ahj #g4 ,factor of evaporation #a4jgbg #h4 ,equivalent evaporation from and at #bab ,f4 pounds #cg1ede ,,efficiency4 #i4 ,efficiency of boiler and furnace per cent #ed ,,capacity4 #aj4 ,boiler horsepower developed #aji #aa4 ,builders' rated horsepower #aej #ab4 ,percentage of rated horsepower developed per cent #gc ,,economic ,,results4 #ac4 ,actual evaporation per pound of coal pounds #g #ad4 ,equivalent evaporation from and at #bab ,f4 per pound of coal as fired1 pounds #g4e #ae4 ,cost of coal per ton 7#b1jjj pounds7 #c4fj #af4 ,cost of coal to evaporate #a1jjj pounds from and at #bab ,f4 #j4bd ,,how ,,to ,,use ,,the ,,test ,,results4 ,the object of working up a test is to obtain a clear idea as to the efficiency of operation of the boiler or its operating cost4 ,consequently1 after the calculations have been made1 they should be used as a basis for study with the idea of improving the boiler performance4 ,take the matter of boiler efficiency1 for example1 as found from the test mentioned4 ,its value was #ed per cent4 ,this is altogether too low and indicates wasteful operation4 ,the efficiency of a hand-fired boiler ought not to be less than #fe per cent1 and it can be increased to #gj per cent by careful management under good conditions4 ,the chart in figure #c can be used to indicate the evaporation that should be obtained in order to reach a desired efficiency4 ,suppose1 for example1 that it is desired to know how much water per pound of coal must be evaporated to produce a boiler efficiency of #fe per cent with coal having a heating value of #ac1ejj ,b4 t4 u4 per pound4 ,locate #ac1ejj at the bottom of the chart1 follow the vertical line until it meets the diagonal marked #fe per cent1 and then from this point follow the horizontal line to the left-hand edge1 where the figure #i is found4 ,this means that the equivalent evaporation from and by #bab ,f4 per pound of coal must be #i pounds of water4 ,if the steam pressure is #ajj pounds gauge1 and the feed-water temperature is #ahj ,f4 the factor of evaporation is #a4jgbg1 then the actual evaporation must be #i #a4jgbg #h4cf pounds per pound of coal4 ,in other words1 to increase the efficiency from #ed per cent to #fe per cent under the same conditions of pressure and feed-water temperature1 it would be necessary to increase the actual evaporation from #g pounds to #h4cf pounds4 ,this would mean practically #bj per cent more steam from the same weight of coal used4 ,illustration3 ,heating ,value of ,coal1 in ,b4 t4 u4 ,per ,pound ,,fig4 #c4 ,how to do this will require some study and experimenting on the part of the fireman or engineer4 ,the three most common reasons for low-boiler efficiency are 7#a7 excess air1 7#b7 dirty heating surfaces1 and 7#c7 loss of coal through the grates4 ,the first of these items is the most important of the three4 ,in most cases the greatest preventable waste of coal in a boiler plant is directly due to excess air4 ,excess air simply means the amount of air which gets into the furnace and boiler which is not needed for completing the combustion of the coal4 ,very often twice as much air is admitted to the boiler setting as is required4 ,this extra or excess air is heated and carries heat out through the chimney instead of heating the water in the boiler to make steam4 ,there are two ways in which this excess air gets into the furnace and boiler setting4 ,first1 by a combination of bad regulation of drafts and firing4 ,the chances are your uptake damper is too wide open4 ,try closing it a little4 ,then1 there may be holes in the fire4 ,keep these covered4 ,the second way excess air occurs is by leakage through the boiler setting1 through cracks in the brickwork1 leaks around the frames and edges of cleaning doors1 and holes around the blow-off pipes4 ,there are also other places where such air can leak in4 ,take a torch or candle and go over the entire surface of your boiler setting--front1 back1 sides1 and top4 ,where the flame of the torch is drawn inward there is an air leak4 ,plaster up all air leaks and repair the brickwork around door frames where necessary4 ,you should go over your boiler for air leaks once a month4 ,in regard to best methods of firing soft coal1 see ,technical ,paper ,no4 #hj of the ,bureau of ,mines1 which may be obtained from your ,state ,fuel ,administrator4 ,dirty heating surfaces cause low efficiency because they prevent the heat in the hot gases from getting through into the water4 ,therefore1 keep the shell and tubes free of soot on one side and scale on the other4 ,soot may be removed by the daily use of blowers1 scrapers1 and cleaners4 ,the problem of scale and pure feed water is a big one and should be taken up with proper authorities on the subject4 ,there are many things that may be done to increase the efficiency of the boiler and to save coal4 ,for convenience a number of these points are grouped in the following list3 ,,what ,,to ,,do4 ,,why4 #a4 ,close up all leaks in the boiler ,to prevent waste of heat due to setting4 excess air admitted4 #b4 ,keep shell and tubes free from ,to allow the heat to pass easily soot and scale4 into the water4 #c4 ,use grates suited to the fuel ,to prevent loss of unburnt coal to be burned4 through air spaces4 #d4 ,fire often1 and little at a ,to obtain uniform conditions and time4 better combustion4 #e4 ,cover all thin spots and keep ,to prevent burning holes in bed fire bed level4 and admitting excess air4 #f4 ,do not allow clinkers to form ,because they reduce the effective on side or bridge walls4 area of the grate4 #g4 ,keep the ash pit free from ashes ,to prevent warping and burning out and hot clinkers4 of the grates4 #h4 ,do not stir the fire except when ,because stirring causes clinker necessary4 and is likely to waste coal4 #i4 ,use damper and not ash-pit doors ,because less excess air is to control draft4 admitted by so doing4 #aj4 ,see that steam pipes and valves ,because steam leaks waste heat are tight4 and therefore coal4 #aa4 ,keep blow-off valves tight4 ,because leaks of hot water waste coal4 #ab4 ,cover steam pipes and the tops ,to prevent radiation and loss of of boilers4 heat4 ,make a boiler test under the conditions of operation as they now exist in your plant4 ,then make all possible improvements as suggested in this bulletin1 make another test afterwards and note the increase in the equivalent evaporation per pound of coal used4 ,remember that the firing line in the boiler room can be just as patriotic and helpful as the firing line at the front4 ,table of factors of evaporation4 ,feed ,steam pressure in pounds per square inch1 gauge4 temperature1---------------------------- ----------------------------------- ,f4 #cj #ej #gj #hj #ij #ajj #aaj #abj ---------------------------------------- ---------------------------- #cb #a4bjgc #a4badd #a4baie #a4bbaf #a4bbcd #a4bbea #a4bbff #a4bbgi #ce #a4bjdb #a4baac #a4bafd #a4bahd #a4bbjc #a4bbai #a4bbce #a4bbdh #ch 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#a4jfce #a4jfdd #a4jfec #a4jffa #a4jffi #aih #a4jehb #a4jeid #a4jfje #a4jfad #a4jfbc #a4jfcb #a4jfda #a4jfdh #bjj #a4jefa #a4jegd #a4jehd #a4jeic #a4jfjb #a4jfab #a4jfbj #a4jfbg #bjb #a4jeda #a4jeec #a4jefc #a4jegb #a4jehb #a4jeia #a4jeii #a4jfjf #bjd #a4jebj #a4jecb #a4jedb #a4jeeb #a4jefa #a4jegj #a4jegi #a4jehf #bjf #a4jdii #a4jeaa #a4jebb #a4jeca #a4jedj #a4jeej #a4jeeh #a4jefe #bjh #a4jdgh #a4jdia #a4jeja #a4jeaj #a4jebj #a4jebi #a4jecg #a4jedd #baj #a4jdeh #a4jdgj #a4jdhj #a4jdij #a4jdii #a4jejh #a4jeaf #a4jebd #bab #a4jdcg #a4jddi #a4jdfj #a4jdfi #a4jdgh #a4jdhg #a4jdif #a4jejc ,,publications ,,on ,,the ,,utilization ,,of ,,coal ,,and ,,lignite4 ,a limited supply of the following publications of the ,bureau of ,mines has been printed and is available for free distribution until the edition is exhausted4 ,requests for all publications can not be granted1 and to insure equitable distribution applicants are requested to limit their selection to publications that may be of especial interest to them4 ,requests for publications should be addressed to the ,director1 ,bureau of ,mines4 ,the ,bureau of ,mines issues a list showing all its publications available for free distribution1 as well as those obtainable only from the ,superintendent of ,documents1 ,government ,printing ,office1 on payment of the price of printing4 ,interested persons should apply to the ,director1 ,bureau of ,mines1 for a copy of the latest list4 ,,publications ,,available ,,for ,,free ,,distribution4 ,,bulletin #eh4 ,fuel briquetting investigations1 ,july1 #aijd1 to ,july1 #aiab1 by ,c4 ,a4 ,wright4 #aiac4 #bgg pp41 #ba pls41 #c figs4 ,,bulletin #gf4 ,united ,states coals available for export trade1 by ,van4 ,h4 ,manning4 #aiad4 #ae pp41 #a pl4 ,,bulletin #he4 ,analyses of mine and car samples of coal collected in the fiscal years #aiaa to #aiac1 by ,a4 ,c4 ,fieldner1 ,h4 ,i4 ,smith1 ,a4 ,h4 ,fay1 and ,samuel ,sanford4 #aiad4 #ddd pp41 #b figs4 ,,bulletin #hi4 ,economic methods of utilizing western lignites1 by ,e4 ,j4 ,babcock4 #aiae4 #gd pp41 #e pls41 #e figs4 ,,bulletin #aai4 ,analyses of coals purchased by the ,government during the fiscal years #aijh-aiae1 by ,g4 ,s4 ,pope4 #aiaf4 #aah pp4 ,,bulletin #ace4 ,combustion of coal and design of furnaces1 by ,henry ,kreisinger1 ,c4 ,e4 ,augustine1 and ,f4 ,k4 ,ovitz4 #aiag4 #add pp41 #a pl41 #de figs4 ,,bulletin #acf4 ,deterioration in the heating value of coal during storage1 by ,h4 ,c4 ,porter and ,f4 ,k4 ,ovitz4 #aiag4 #ch pp41 #g pls4 ,,bulletin #ach4 ,coking of ,illinois coals1 by ,f4 ,k4 ,ovitz4 #aiag4 #ga pp41 #aa pls4 #a fig4 ,,technical ,,paper #cd4 ,experiments with furnaces for a hand-fired return tubular boiler1 by ,s4 ,b4 ,flagg1 ,g4 ,c4 ,cook1 and ,f4 ,e4 ,woodman4 #aiad4 #cb pp41 #a pl41 #d figs4 ,,technical ,,paper #ej4 ,metallurgical coke1 by ,a4 ,w4 ,belden4 #aiac4 #dh pp41 #a pl41 #bc figs4 ,,technical ,,paper #gf4 ,notes on the sampling and analysis of coal1 by ,a4 ,c4 ,fieldner4 #aiad4 #ei pp41 #f figs4 ,,technical ,,paper #hj4 ,hand-firing soft coal under power-plant boilers1 by ,henry ,kreisinger4 #aiae4 #hc pp41 #cb figs4 ,,technical ,,paper #ig4 ,saving fuel in heating a house1 by ,l4 ,p4 ,breckenridge and ,s4 ,b4 ,flagg4 #aiae4 #ce pp41 #c figs4 ,,technical ,,paper #ih4 ,effect of low-temperature oxidation on the hydrogen in coal and the change of weight of coal in drying1 by ,s4 ,h4 ,katz and ,h4 ,c4 ,porter4 #aiag4 #af pp41 #b figs4 ,,technical ,,paper #abc4 ,notes on the uses of low-grade fuel in ,europe1 by ,r4 ,h4 ,fernald4 #aiae4 #cg pp41 #d pls41 #d figs4 ,,technical ,,paper #acc4 ,directions for sampling coal for shipment or delivery1 by ,g4 ,s4 ,pope4 #aiag4 #ae pp41 #a pl4 ,,technical ,,paper #acg4 ,combustion in the fuel bed of hand-fired furnaces1 by ,henry ,kreisinger1 ,f4 ,k4 ,ovitz1 and ,c4 ,e4 ,augustine4 #aiaf4 #gf pp41 #b pls41 #ba figs4 #ae cents4 ,,technical ,,paper #adh4 ,the determination of moisture in coke1 by ,a4 ,c4 ,fieldner and ,w4 ,a4 ,selvig4 #aiag4 #ac pp4 ,,technical ,,paper #agj4 ,the diffusion of oxygen through stored coal1 by ,s4 ,h4 ,katz4 #aiag4 #di pp41 #a pl41 #bg figs4 ,,technical ,,paper #agb4 ,effects of moisture on the spontaneous heating of stored coal1 by ,s4 ,h4 ,katz and ,h4 ,c4 ,porter4 #aiag4 #be pp41 #a pl41 #h figs4 ,,publications ,,that ,,may ,,be ,,obtained ,,only ,,through ,,the ,,superintendent ,,of ,,documents4 ,,bulletin #h4 ,the flow of heat through furnace walls1 by ,w4 ,t4 ,ray and ,henry ,kreisinger4 #aiaa4 #cb pp41 #ai figs4 #e cents4 ,,bulletin #aa4 ,the purchase of coal by the ,government under specifications1 with analyses of coal delivered for the fiscal year #aijh-i1 by ,g4 ,s4 ,pope4 #aiaj4 #hj pp4 #aj cents4 ,,bulletin #ac4 ,rsum of producer-gas investigations1 ,october #a1 #aijd1 to ,june #cj1 #aiaj1 by ,r4 ,h4 ,fernald and ,c4 ,d4 ,smith4 #aiaa4 #cic pp41 #ab pls41 #bej figs4 #fe cents4 ,,bulletin #ad4 ,briquetting tests of lignite at ,pittsburgh1 ,pa41 #aijh-i1 with a chapter on sulphite-pitch binder1 by ,c4 ,l4 ,wright4 #aiaa4 #fd pp41 #aa pls41 #d figs4 #ae cents4 ,,bulletin #ah4 ,the transmission of heat into steam boilers1 by ,henry ,kreisinger and ,w4 ,t4 ,ray4 #aiab4 #ahj pp41 #gh figs4 #bj cents4 ,,bulletin #ba4 ,the significance of drafts in steam-boiler practice1 by ,w4 ,t4 ,ray and ,henry ,kreisinger4 #fd pp41 #bf figs4 #aj cents4 ,,bulletin #bb4 ,analyses of coals in the ,united ,states1 with descriptions of mine and field samples collected between ,july #a1 #aijd1 and ,june #cj1 #aiaj1 by ,n4 ,w4 ,lord1 with chapters by ,j4 ,a4 ,holmes1 ,f4 ,m4 ,stanton1 ,a4 ,c4 ,fieldner1 and ,samuel ,sanford4 #aiab4 ,part ,i1 ,analyses1 pp4 #a-cba2 ,part ,,ii1 ,descriptions of samples1 pp4 #cba-aabi4 #he cents4 ,,bulletin #bc4 ,steaming tests of coals and related investigations1 ,september #a1 #aijd1 to ,december #ca1 #aijh1 by ,l4 ,p4 ,breckenridge1 ,henry ,kreisinger1 and ,w4 ,t4 ,ray4 #aiab4 #chj pp41 #b pls41 #id figs4 #ej cents4 ,,bulletin #bg4 ,tests of coal and briquets as fuel for house-heating boilers1 by ,d4 ,t4 ,randall4 #dd pp41 #c pls41 #b figs4 #aj cents4 ,,bulletin #cg4 ,comparative tests of run-of-mine and briquetted coal on locomotives1 including torpedo-boat tests1 and some foreign specifications for briquetted fuel1 by ,w4 ,f4 ,m4 ,goss4 #aiaa4 #eh pp41 #d pls41 #ce figs4 #ae cents4 ,,bulletin #dj4 ,the smokeless combustion of coal in boiler furnaces1 with a chapter on central heating plants1 by ,d4 ,t4 ,randall and ,h4 ,w4 ,weeks4 #aiab4 #ahh pp41 #dj figs4 #bj cents4 ,,bulletin #da4 ,government coal purchases under specifications1 with analyses1 for the fiscal year #aiji-aj by ,g4 ,s4 ,pope1 with a chapter on the fuel-inspection laboratory of the ,bureau of ,mines1 by ,j4 ,d4 ,davis4 #aiab4 #ig pp41 #c pls41 #i figs4 #ae cents4 ,,bulletin #aji4 ,operating details of gas producers1 by ,r4 ,h4 ,fernald4 #aiaf4 #gd pp4 #aj cents4 ,,bulletin #aaf4 ,methods of sampling delivered coal1 and specifications for the purchase of coal for the ,government1 by ,g4 ,s4 ,pope4 #aiaf4 #fd pp41 #e pls41 #b figs4 #ae cents4 ,,technical ,,paper #bj4 ,the slagging type of gas producer1 with a brief report of preliminary tests1 by ,c4 ,d4 ,smith4 #aiab4 #ad pp41 #a pl4 #e cents4 ,,technical ,,paper #fc4 ,factors governing the combustion of coal in boiler furnaces2 a preliminary report1 by ,j4 ,k4 ,clement1 ,j4 ,c4 ,w4 ,frazer1 and ,c4 ,e4 ,augustine4 #aiad4 #df pp41 #bf figs4 #aj cents4 ,,technical ,,paper #fe4 ,a study of the oxidation of coal1 by ,h4 ,c4 ,porter4 #aiad4 #cj pp41 #ab figs4 #e cents4 ,,technical ,,paper #aad4 ,heat transmission through boiler tubes1 by ,henry ,kreisinger and ,f4 ,k4 ,ovitz4 #aiae4 #cf pp41 #bc figs4 #aj cents4 ,,transcriber',s ,,notes3 ,page #e3 ,added period to the sentence3 ,if the coal used in the test is to be analyzed1 take a sample of from #d to #f pounds from each barrow and throw it into a box near the scales44 ,page #aa3 ,changed typo calcuate to calculate4 ,page #ah3 ,changed typo #a4ahed to #a4jhed1 see intersecting columns #ahd ,f and #bjj psi4 ,page #ai3 ,changed typo ,samuel ,sandford to ,samuel ,sanford4