STATE OF ILLINOIS ADLAI E. STEVENSON, Governor DEPARTMENT OF REGISTRATION AND EDUCATION NOBLE J. PUFFER, Director DIVISION OF THE STATE GEOLOGICAL SURVEY M. M. LEIGHTON. Chief URBANA REPORT OF INVESTIGATIONS— NO. 151 CORRELATION OF DOMESTIC STOKER COMBUSTION WITH LABORATORY TESTS AND TYPES OF FUELS IV. COMBUSTION TESTS OF ILLINOIS AND OTHER COALS Roy J. Helfinstine PRINTED BY AUTHORITY OF THE STATE OF ILLINOIS URBANA, ILLINOIS 1951 ILLINOIS GEOLOGICAL I '.Err.ARY FEB 6 1952 ORGANIZATION STATE OF ILLINOIS HON. ADLAI E. STEVENSON, Governor DEPARTMENT OF REGISTRATION AND EDUCATION HON. NOBLE J. PUFFER, Director BOARD OF NATURAL RESOURCES AND CONSERVATION HON. NOBLE J. PUFFER, M.A., LL.D., Chairman W. H. NEWHOUSE, Ph.D., Geology ROGER ADAMS, Ph.D., D.Sc, Chemistry LOUIS R. HOWSON, C.E., Engineering A. E. EMERSON, Ph.D., Biology LEWIS H. TIFFANY, Ph.D., Pd.D., Forestry GEORGE D. STODDARD, Ph.D., Litt.D., LL.D., L.H.D. President of the University of Illinois GEOLOGICAL SURVEY DIVISION M. M. LEIGHTON, Ph.D., Chief '[■LINO'S STATE GEOLOGICAL SURVEY 3 3051 00005 7939 (27262— 2M— 3-51) STATE GEOLOGICAL SURVEY DIVISION Natural Resources Building, Urbana M. M. LEIGHTON, Ph.D., Chief Enid Townley, M.S., Geologist and Assistant to the Chief Velda A. Millard, Junior Assistant to the Chief Helen E. McMorris, Secretary to the Chief RESEARCH GEOLOGICAL RESOURCES Arthur Bevan, Ph.D., D.Sc, Principal Geologist Frances H. Alsterlund, A.B., Research Assistant Coal G. H. Cady, Ph.D., Senior Geologist and Head Ernest P. Du Bois, Ph.D., Geologist R. J. Helfinstine, M.S, Mechanical Engineer George M. Wilson, M.S., Geologist Robert M. Kosanke, M.A., Geologist Raymond Siever, Ph.D., Associate Geologist John A. Harrison, M.S., Assistant Geologist Jack A. Simon, M.S., Assistant Geologist Mary Barnes Rolley, M.S., Assistant Geologist Margaret A. Parker, B.S., Assistant Geologist Frederick E. Williams, B.A., Assistant Geologist Kenneth E. Clegg, B.S., Research Assistant Adabell Karstrom, M.S., Research Assistant Walter E. Cooper, Technical Assistant Oil and Gas A. H. Bell, Ph.D., Geologist and Head David H. Swann, Ph.D., Geologist Virginia Kline, Ph.D., Associate Geologist Wayne F. Meents, Assistant Geologist Lester W. Clutter, B.S., Research Assistant Kathryn C. Irving, Technical Assistant Robert L. Brownfield, A.B., B.S., Research Assistant Petroleum Engineering Paul A. Witherspoon, B.S., Petroleum Engineer and Head Frederick Squires, A.B., B.S., Petroleum Engineer, Emeritus Paul J. Shanor, B.S., Associate Petroleum Engineer Industrial Minerals J. E. Lamar, B.S., Geologist and Head Robert M. Grogan, Ph.D., Geologist Donald L. Graf, Ph.D., Associate Geologist James C. Bradbury, A.M., Assistant Geologist Raymond S. Shrode, M.S., Assistant Geologist Clay Resources and Clay Mineral Technology Ralph E. Grim, Ph.D., Consulting Clay Mineralogist W. Arthur White, M.S., Associate Geologist Herbert D. Glass, M.A., Associate Geologist William Johns, B.A., Special Research Assistant Groundwater Geology and Geophysical Exploration Arthur Bevan, Ph.D., D.Sc, Acting Head M. Wm. Pullen, Ph.D., Geologist Merlyn B. Buhle, M.S., Associate Geologist John F. Mann, Jr., M.S., Assistant Geologist Richard F. Fisher, M.S., Assistant Geologist Margaret J. Castle, Assistant Geologic Draftsman (on leave) Robert D. Knodle, M.S., Assistant Geologist John W. Foster, M.S., Assistant Geologist M. Verne Strantz, M.S., Research Assistant (on leave) Bennie Ellis, Automotive Mechanic's Helper Engineering Geology and Topographic Mapping George E. Ekblaw, Ph.D., Geologist and Head Areal Geology and Paleontology H. B. Willman, Ph.D., Geologist and Head J. S. Templeton, Ph.D., Geologist T. C. Buschbach, B.S., Research Assistant (half-time) Subsurface Geology L. E. Workman, M.S., Geologist and Head Elwood Atherton, Ph.D., Associate Geologist Donald B. Saxby, M.S., Assistant Geologist Robert C. McDonald, B.S., Research Assistant W. W. Hallstein, B.S., Research Assistant T. C. Buschbach, B.S., Research Assistant (half- time) Charles C. Engel, Technical Assistant Joseph F. Howard, Laborer Frank H Grace C. GEOCHEMISTRY Reed, Ph.D., Chief Chemist Johnson, B.S., Research Assistant Coal Chemistry G. R. Yohe, Ph.D., Chemist and Head Joseph E. Dunbar, B.S., Research Assistant Physical Chemistry J. S. Machin, Ph.D., Chemist and Head Tin Boo Yee, M.S., M.A., Assistant Chemist Frances H. Staplin, M.A., Research Assistant Fluorine Chemistry G. C. Finger, Ph.D., Chemist and Head Robert E. Oesterling, B.A., Research Assistant Chemical Engineering H. W. Jackman, M.S.E., Chemical Engineer and Head P. W. Henline, M.S., Chemical Engineer B. J. Greenwood, B.S., Mechanical Engineer James C. McCullough, Research Associate Earl C. Noble, Technical Assistant (on leave) Raymond H. Pellum, Technical Assistant Ronald J. Hays, Technical Assistant X-Ray W. F. Bradley, Ph.D., Chemist and Head Spectrochemistry Kenneth B. Thomson, Ph.D., Physicist and Head R. J. Piersol, Ph.D., Physicist Emeritus Juanita Witters, M.S., Assistant Physicist Analytical Chemistry O. W. Rees, Ph.D., Chemist and Head L. D. McVicker, B.S., Chemist Howard S. Clark, A.B., Chemist Emile D. Pierron, M.S., Assistant Chemist Francis A. Coolican, B.S., Research Assistant Charles T. Allbright, B.S., Research Assistant Richard H. Organist, B.S., Research Assistant Francis Scheidt, B.S., Research Assistant Jo Anne Armstrong, B.S., Research Assistant Eugene Lange, Technical Assistant George R. James, Technical Assistant MINERAL ECONOMICS W. H. Voskuil, Ph.D., Mineral Economist W. L. Busch, Assistant Mineral Economist Ethel M. King, Research Assistant EDUCATIONAL EXTENSION Gilbert O. Raasch, Ph.D., Geologist in Charge Margaret Hayes, B.S., Research Assistant Louis Unfer, Jr., B.S., Research Assistant Consultants: Geology, George W. White, Ph.D., Uni- versity of Illinois Ralph E. Grim, Ph.D., Univer sity of Illinois Ceramics, Ralph K. Hursh, B.S., Uni- versity of Illinois Mechanical Engineering, Seichi Konzo, M.S., University of Illinois Topographic Mapping in Cooperation with the United States Geological Survey. This report is a contribution of the Coal Division. GENERAL ADMINISTRATION Library Anne E. Kovanda, B.S., B.L.S., Librarian Ruby D. Frison, Technical Assistant Mineral Resource Records Vivian Gordon, Head Dorothy Gore, B.S., Research Assistant Ruth Warden, B.S., Research Assistant Beverly Solliday, B.S., Research Assistant Wanda L. Sparr, Technical Assistant Sarah Haraldsen, Technical Assistant Ina C, Johnson, A.B., Technical Assistant Marjorie Martin, B.A., Technical Assistant Publications Jane V. Olson, B.A., Associate Technical Editor Dorothy E. Rose, B.S., Consulting Technical Editor Barbara A. Zeiders, B.S., Assistant Editor Meredith M. Calkins, Geologic Draftsman Margaret Wilson, B.A., Assistant Geologic Draftsman Technical Records Berenice Reed, Supervisory Technical Assistant Marilyn Swartswalter, Technical Assistant General Scientific Information Donna M. Builte, Research Assistant Jane Teller, B.A., Technical Assistant Other Technical Services Leslie D. Vaughan, Research Associate, Photography Beulah M. Unfer, Technical Assistant A. W. Gotstein, Research Associate, Equipment Design Glenn G. Poor, Research Associate, Equipment Design Gilbert L. Tinberg, Technical Assistant Wayne W. Nofftz, In Charge Techii^al Supplie Robert M. Fairfield, Technical Assistant Financial Records Velda A. Millard, In Charge Leona B. Kenward, Clerk-Typist III Deoris Castle, Clerk-Typist I Lorraine Galbraith, Clerk-Typist I Clerical Services Mary Cecil, Clerk-Stenographer III Mary M. Sullivan, Clerk-Stenographer III Ethel M. Henwood, Clerk-Stenographer II Lyla Nofftz, Clerk-Stenographer II Eleanor M. White, Clerk-Stenographer II Reta Watson, Clerk-Stenographer I Hazel V. Orr, Clerk-Stenographer I Shirley W. Rice, Clerk-Stenographer I Mary J. de Hann, Messenger-Clerk I Automotive Service Glenn G. Poor, In Charge Robert O. Ellis, Automotive Mechanic Everette Edwards, Sr., Automotive Mechanic March 15, 1951 CONTENTS Page Introduction 7 Acknowledgments 7 Objective 7 Equipment 7 Procedure 8 Combustion testing schedule 9 Air setting 10 Combustion rating criteria 10 Results 12 Method of describing degree of correlation 12 Correlation of combustion criteria with standard chemical analyses 12 Heat obtained 12 Uniformity of combustion rate 12 Responsiveness of fire to heat demands 21 Pickup 21 Overrun 21 Clinkering characteristics 21 Out-of-state coals compared with Illinois coals 27 Relative qualities of coals tested 27 Conclusions 31 Appendix 33 TABLES Table Page 1. Source and identification of coals 34 2. Variation of rate of heat release 35 3. Heat obtained per pound of coal 36 4. Heat obtained per pound of ash formed 37 5. Responsiveness of fire to heat demand 38 6. Pickup ratios 39 7. Size analyses of coals 40 8. Proximate analyses of coals 41 9. Ultimate analyses of coals 42 10. Heating values and sulfur varieties 43 11. Ash fusion temperatures, Gieseler plasticity, free-swelling index, and ash analyses 44 12. Combustion data 45 13. Clinker and fly- ash data and coal-burning rates 46 ILLUSTRATIONS Figure Page 1. Heat obtained vs. heating value 13 2. Direct proportionality relationship of heat obtained and heating value 13 3. Heat obtained vs. carbon 14 4. Heat obtained vs. ash 14 5. Heat obtained vs. ash for 6 to 17 percent oxygen coals 15 Figure Page 6. Heat obtained vs. ash plus oxygen plus nitrogen 15 7. Uniformity vs. ash 17 8. Uniformity vs. softening temperature of ash 17 9. Uniformity vs. initial deformation temperature of ash 18 10. Uniformity vs. fluid temperature of ash 18 11. Uniformity vs. difference between the fluid and the initial deformation temperatures 19 12. Uniformity vs. free-swelling index 19 13. Uniformity vs. Gieseler maximum fluidity 20 14. Uniformity vs. volatile matter, as-fired basis 20 15. Uniformity vs. volatile matter, moisture and ash-free basis 22 16. Responsiveness vs. heating value 22 17. Responsiveness vs. free-swelling index 23 18. Responsiveness vs. volatile matter 23 19. Pickup vs. free-swelling index 24 20. Pickup vs. softening temperature of ash 24 21. Pickup vs. ash 25 22. Pickup vs. volatile matter 25 23. Overrun vs. free-swelling index 26 24. Overrun vs. Gieseler softening temperature 26 25. Clinker- ash ratio vs. softening temperature of ash 28 26. Apparent specific gravity of clinker vs. clinker-ash ratio 28 27. Clinker-shatter index vs. softening temperature of ash 29 28. Clinker-shatter index vs. clinker-ash ratio 29 29. Clinker-shatter index vs. apparent specific gravity of clinker 30 30. Heat obtained vs. fixed carbon 30 CORRELATION OF DOMESTIC STOKER COMBUSTION WITH LABORATORY TESTS AND TYPES OF FUELS IV. COMBUSTION TESTS OF ILLINOIS AND OTHER COALS Roy J. Helfinstine Various small-scale tests are used as indexes of the character of coal. These tests include the proximate analysis, ultimate analysis, heating value, ash-fusion temperatures, free-swelling index, Gieseler plasticity, and petrographic analysis. In 1937 the Illinois Geological Survey began a series of tests to determine the value of these analyses (chiefly petrographic analy- sis) as indexes to the performance char- acteristics of coals in a domestic stoker. The results of these tests were published in 1942, as Part I 1 of this series of studies. Part II, published in 1946, 2 is a compre- hensive study of Illinois coals that received special preparation in the Survey labora- tory. As the size range of coal used was kept constant, further investigation of the effect of coal size upon performance char- acteristics in a domestic stoker was required. The results of this study were published in 1948 as Part III. 3 With the exception of the two coals used in the preliminary studies, Illinois coals were used for all the tests in this series thus far published. In order to extend the range of coal characteristics included in the study, samples of coals from Arkansas, Indiana, Iowa, Kentucky, Missouri, West Virginia, and Wyoming were tested. It also seemed desirable to make tests with "commercial" coals, that is, those available on the open market. The results of these tests consti- tute the new data in this report. In order to provide a complete picture, data from the previously published reports are incor- porated in some of the graphs. 1 McCabe, L. C, Konzo, S., and Rees, O. W., Correlation of domestic stoker combustion with laboratory tests and types of fuels. I Preliminary studies: Illinois Geol. Survey Rept. Inv. 78, 20 pp., 1942. - Helfinstine, Roy J., and Boley, Charles C, Correlation of domestic stoker combustion with laboratory tests and types of fuels. II. Combustion tests and preparation studies of representative Illinois coals: Illinois Geol. Survey Rept. Inv. 120, 62 pp., 1946. 3 Helfinstine, Roy J., Correlation of domestic stoker com- bustion with laboratory tests and types of fuels. III. Effect of coal size upon combustion characteristics: Illi- nois Geol. Survey Rept. Inv. 133, 47 pp., 1948. Acknowledgments Grateful acknowledgment is made of as- sistance given by numerous members of the staff, particularly by W. E. Cooper, Tech- nical Assistant in the Coal Division. S. Konzo served as consultant, and his helpful advice is gratefully acknowledged. The investigation was carried out under the general direction of G. H. Cady, Head of the Coal Division of the Geological Re- sources Section of the Survey. The chem- ical analyses were made by the Analytical Division of the Geochemistry Section under the direction of O. W. Rees. Most of the coal samples used for the tests w T ere contributed by coal companies, whose cooperation is sincerely appreciated. Objective The primary objective of the tests de- scribed in this report was to determine the relationship between coal composition (as determined by standard analytical tests) and the performance characteristics of coals that exhibit a wide range in combustion be- havior when burned in a domestic stoker. EQUIPMENT The stoker and boiler used for all the reported tests are standard commercial units which were installed according to the manufacturers' instructions. The auxil- iary equipment and instruments did not affect the performance of the unit. The boiler is rated at 570 sq. ft. of equivalent direct radiation (136,800 B.t.u. per hr.). A maximum coal-feeding rate of 28 lb. per hr. is also given by the boiler manufacturer. The unit was operated as a forced-circulation hot-water boiler, with the water being recirculated at a constant rate during all tests. The quantity of water flowing through the boiler was indicated by a hot-water meter. The meter was occa- [7] 8 DOMESTIC STOKER COMBUSTION sionally checked by weighing the water passing through it, but no appreciable error was found. The temperature of the inlet boiler-water was maintained at approxi- mately 160°F. by an automatic valve that regulated the quantity of cooling water supplied to an indirect heat exchanger. The entire stoker-boiler unit, including the heat exchanger, was mounted on a plat- form scale with dial graduations of one- half pound. All connections to equipment not on the scales were flexible. A two-pen, mercury-actuated, recording thermometer provided a continuous record of the temperature of the inlet and outlet boiler-water. The temperatures of the air entering the stoker and of the stack gas were recorded by means of a multipoint potentiometer and thermocouples. A photo- electric cell and the recording potentiom- eter were used to provide a record of the opacity of the stack gas. A chemical-type meter recorded the percentage of C0 2 in the stack gas. The static pressure in the stoker air duct was recorded by a pressure gage. Indicating instruments measured the power required by the stoker and the drafts in the stack and combustion chamber. A 16-mm. motion picture camera with a special timer was used for taking pictures of the fuel bed at the rate of one frame every 21/ seconds. When the film was viewed at the rate of 16 frames per second the action appeared 40 times faster than the actual rate. When the camera was not being used for taking pictures of the fuel bed, it was used to take single frame pictures of the scale dial and a clock at appropriate intervals (usually one-half hour), thereby furnishing a record of the loss in weight of the stoker- boiler unit without continuous attention. The weight at the indicated time could be determined rapidly and conveniently by viewing the film through a low-power microscope. The coal-washing unit used for a few of the coals described in this report was a laboratory-size concentrating table, equipped with a diagonal, linoleum-covered deck with wooden riffles. The dimensions of the deck were 8 ft. 8 in. by 4 ft. 7 in. A complete description of this table and its action has been published. 4 5 A shatter-test machine, similar to that described in A.S.T.M. Standard D 141-48, was used to determine the resistance of the been published. 4, 5 PROCEDURE The tests described in this report are divided into two phases. For the first phase, coals from four Arkansas mines were tested as received and also after passing over the concentrating table with a "normal" reject. One Illinois coal from Douglas County was tested in the "washed" condition only. The second phase consisted of tests on com- mercially prepared stoker coals obtained from several Illinois mines and from a num- ber of mines in other states. Table 1 gives additional information about the source of the coals tested. The coal samples from Illinois, Indiana, Iowa, and Missouri were obtained directly from the mines by truck. The samples from Arkansas were obtained from the mines by B. C. Parks, Bureau of Research, Uni- versity of Arkansas, and shipped in an open car to Urbana. The Wyoming coal was obtained at the mine by C. C. Boley, Nat- ural Resources Research Institute, Univer- sity of Wyoming, and shipped to Urbana in sealed barrels. Three samples from Ken- tucky (Ky. 1, Ky. 3, and Ky. 4) were obtained from railroad cars upon receipt at local coal dealers. The remaining sam- ples were obtained from bins at nearby re- tail yards. Although there is a possibility of error in identification of the coals not obtained directly from the mine, only the source of the Ohio coal sample seems doubtful to the author. The samples are not considered repre- sentative of the seams, or even the mines. It was obviously impractical, and of no particular importance, to obtain represent- ative samples for this study. Coals from a large number of sources were used in 4 Helfinstine, Roy J., and Boley, Charles C, op. cit. 3 Boley, Charles C, Analysis of coal cleaning on a concen- trating table: Illinois Geol. Survey Rept. Inv. 136, 63 pp., 1949. PROCEDURE order to compare widely varying character- istics. Considerable care was taken to obtain representative samples of the coals as burned which were used for size and chemical analyses. Standard or proposed methods of the American Society for Testing Materials were used wherever they were applicable. The size composition of the coals was determined with mechanically vibrated test sieves with square openings. All mesh sieves were of the "Tyler" series. As shown in table 7 (appendix) the size composition of the coal varied widely. Maintenance of a constant size composition might have been desirable but it was not feasible for the present studies. Previous tests made on Illinois coals indi- cated that the size composition of coal burned did not greatly influence its com- bustion characteristics in a domestic stoker. 6 Of course, a difference in composition of various size fractions of a coal will prob- ably result in a corresponding change in combustion characteristics. However, such changes should not be attributed to change in size but to change in composition. Combustion Testing Schedule The combustion testing schedule included tests with the stoker operating 60, 45, 30, and 15 minutes out of each hour. Approxi- mately 300 pounds of coal were burned during each of these four tests. The inter- mittent test with the stoker operating 15 minutes out of each hour was followed by a hold-fire test of two days with the stoker operating about three minutes out of each one and three-fourths hours. The hold-fire test was followed by a two-hour test with continuous stoker operation. The test with the stoker operating con- tinuously was started on a clean hearth. Only the clinker was removed before all tests with intermittent stoker operation. All coal, clinker, and ash were removed at the end of the series of tests with a given coal. About 50 pounds of coal were burned before starting the actual test after changing the stoker operation rate and removing the clinker. Motion pictures of the combustion 8 Helfinstine, Roy J., op. cit. chamber were taken for approximately one- half hour at a definite time during each test with a given operation rate. The chronological test schedule follows: Tuesday 7:00 a.m. Start fire on clean hearth. Cause stoker to operate continuously. 10:00 a.m. Beginning of test period for contin- uous stoker operation. 3 :45 p.m. Start taking motion pictures of fuel bed. 4:25 p.m. Stop taking motion pictures of fuel bed. 8:00 p.m. End of test period with continuous stoker operation. Remove clinker, fill hopper, and change stoker oper- ating rate to 45 minutes on and 15 minutes off. 10:15 p.m. Beginning of test period with stoker operating 45 minutes out of each hour. Wednesday 10:15 a.m. Start taking motion pictures of fuel bed. 11:05 a.m. Stop taking motion pictures of fuel bed. 11:13 a.m. Start taking motion pictures of fuel bed. 11:40 a.m. Stop taking motion pictures of fuel bed. 1:15 p.m. End of test period with stoker oper- ating 45 minutes out of each hour. Remove clinker, fill hopper, and change stoker operating rate to 30 minutes on and 30 minutes off. 4:30 p.m. Beginning of test period with stoker operating 30 minutes out of each hour. Thursday 10:45 a.m. Start taking motion pictures of fuel bed. 11:05 a.m. Stop taking motion pictures of fuel bed. 11:28 a.m. Start taking motion pictures of fuel bed. 11:45 a.m. Stop taking motion pictures of fuel bed. 2:30 p.m. End of test period with stoker oper- ating 30 minutes out of each hour. Remove clinker, fill hopper, and change stoker operating rate to 15 minutes on and 45 minutes off. 6:30 p.m. Beginning of test period with stoker operating 15 minutes out of each hour. Friday 8:43 a.m. Start taking motion pictures of fuel bed. 9:05 a.m. Stop taking motion pictures of fuel bed. 9:43 a.m. Start taking motion pictures of fuel bed. 9:55 a.m. Stop taking motion pictures of fuel bed. Saturday 10:30 a.m. End of test period with stoker oper- ating 15 minutes out of each hour. Remove clinker and change stoker operating rate to hold-fire (3 min- utes out of each 1^ hours). 10 DOMESTIC STOKER COMBUSTION Monday 11:45 a.m. Start stoker operating continuousl). 1 :45 p.m. Stop stoker. Quench fire, remove clinker and ash from hearth and fly ash from boiler passages. Remove coal from hopper, worm, and retort. Records were made of the weights of all coal placed in the hopper, and of the coal, clinker, fly ash, and refuse removed. A representative sample of refuse was analyzed for percentage of ash. This information permitted the calculation of the average re- lationship between the loss in weight of the stoker-boiler unit and the coal burned. 7 The heat output from the boiler was determined for each 20-minute interval of the test with continuous stoker operation, and for each hour with the three tests with intermittent stoker operation. Average val- ues for each operation rate were determined for pressure in the stoker windbox, tempera- ture of the room, temperature of the stack gases during stoker operation, percentage of COo in the stack gases during stoker oper- ation, boiler output, rate of coal feed, and coal burning rate. Air Setting Before starting a fire with any coal, the air control was adjusted to what seemed most reasonable. During the first two and one-half hours of operation, minor adjust- ments of the air control were made if neces- sary to provide what was considered the optimum setting for the coal being burned. All adjustments were completed before the beginning of the test period. Combustion Rating Criteria The many factors that govern the suit- ability of coals for domestic stokers include : ( 1 ) amount of heat obtamed per dollar ; (2) attention required by heating plant; (3) ability to maintain the desired tempera- ture in the house; (4) smoke emitted; (5) ability to maintain fire at low rates of oper- ation ; (6) cleanliness; (7) appearance of the fuel bed and fire; (8) odors given off by clinkers during their removal ; (9) quiet- ' Ratio: :oal fed — (clinker removed -f- ash in refuse -\- fly ash in boiler passages) coal fed into combustion chamber ness of operation; and (10) appearance of the coal. These factors vary in relative im- portance, depending upon the heating system and also upon personal preference of the operator. Objective measurement of each of these factors would have been desirable, but no such measures for all have been devised, and probably are not possible. Certain objective measurements were made that should reveal the relative merits of the various stoker coals tested. Most of these are discussed in some detail in Part II of this series of reports, and are described only briefly in this report. A few criteria have been added and a few modified for these tests. The heat absorbed by the boiler per pound of coal burned is a fairly reliable index of the cost of heat if the hold-fire characteristics of the coals being compared are similar. Illinois coals usually require less stoker operation to hold fire than do many of the eastern coals, hence the "heat obtained" is not always a fair basis for cost comparison between coals from these two areas. Although the cost of heat may not be of primary importance in the selection of stoker coal, it is an important consideration for many people. This does not mean that other factors such as convenience, cleanliness, re- liability, and ability to maintain the desired comfortable conditions are disregarded. As cost probably has far more influence than most people will admit, test results that give information about cost are included. The percentage of ash, which can be determined by proximate analysis, is a good index to attention required by the heating plant. The pounds of ash per million B.t.u. is probably a fairer measure. Other criteria which were used for the present tests (but not in those reported in R.I. 120 or R.I. 133) are the density and friability of the clinker. Density of the clinker was determined by a slight modifi- cation of the A.S.T.M. procedure for de- termining the density of coke. The fria- bility of clinkers was determined by drop- ping the clinker twice from a height of 6 feet, and determining the percentage of clinker by weight that broke into pieces PROCEDURE 11 weighing less than }4 lb. Although the percentage of ash removed in the form of clinker has been determined for all tests in this series, this information is published for the first time in this report. The subjective clinker rating given in previous reports is also included in this report, although its value is quite limited. The ability of a stoker-fired heating system to maintain the desired temperature in a dwelling depends largely upon the phys- ical characteristics of the heating system and the construction of the house. A tightly constructed, well-insulated dwelling with a good heating system will be easier to heat than a poorly constructed house with an obsolete heating system. However, certain performance characteristics of the coal are thought to exert influence on "comfort con- ditions" irrespective of where it is burned. These are : ( 1 ) uniformity of rate of burn- ing, (2) responsiveness of the fire after a prolonged hold-fire period, (3) responsive- ness of the fire after a short "off" period (called pickup in this report), and (4) the tendency for over-heating (called overrun in this report). Uniformity of rate of burning is regarded as one of the most influential of these fac- tors. It seems reasonable, at least, to believe that a uniform temperature can be more readily maintained if the furnace or boiler releases heat at a uniform rate during stoker operation. There are several ways to indicate the degree of variability of rate of heat release. One of the simplest was used for the tests described in this report. Although knowl- edge about the method of calculating uni- formity, or any of the other indexes used in this report, is not essential for a full use of the information presented, a description of the procedure follows. For the test with continuous stoker oper- ation, the rate of heat output was deter- mined for each 20-minute interval. The percentage difference between the rate of heat output for each 20-minute interval and the average rate of heat output during the entire test with continuous stoker operation was calculated. These differences were added, irrespective of algebraic sign, and then divided by the number of cycles (30) to give the average percent variation in rate of heat output for the test with continuous stoker operation. The same general proce- dure was used for the tests with 45, 30, and 15 minutes of stoker operation per hour, except that the cycle period was considered as one hour instead of 20 minutes. The per- centage variations for the four operation rates were averaged, and these average values are used for all graphs and tables in this report. Another measure of uniformity of rate of heat release which is included is the ratio of the minimum rate of heat release during any cycle of stoker operation to the average rate of heat release per cycle. Responsiveness (after a prolonged hold- fire period) is the heat output in B.t.u. dur- ing the 30 minutes of continuous stoker operation immediately following the hold- fire period. The responsiveness ratio is the ratio of heat output during the first 30- minute period and the average output for 30 minutes during the test with continuous stoker operation. As results are based on only one cycle of operation for each coal, variations of 0.03 or less in the ratio are not considered significant. Pickup is the rate of heat release during the first five minutes of stoker operation following a 45-minute period without stoker operation. The average pickup for 40 cycles is given in this report. The pickup ratio is the ratio of the rate of heat release during this five-minute period to the rate of heat release during the test with continuous stoker operation. Overrun is the rate of heat output during the first five minutes of the off period following a 15-minute period of stoker operation. The numerical value is largely dependent upon the equipment used. An overrun ratio was also calculated ; this is the ratio of overrun to the rate of heat release during the test with continuous stoker operation. Overrun will not be im- portant unless the heating system causes the temperature to rise above the desired level because of excessive heat release after the stoker shuts off. 12 DOMESTIC STOKER COMBUSTION RESULTS Method of Describing Degree of Correlation The degree of correlation of two vari- ables may be expressed as a correlation coef- ficient, such as the Pearson product-moment coefficient. Although a numerical value is thus obtained, it is difficult to evaluate its significance. Probably most people would prefer to base their judgment of signifi- cance of a given relationship upon the scatter of points in a graph. The data are presented in full so that anyone who desires may do the time-consuming labor required to determine the coefficients. Correlation of Combustion Criteria with Standard Chemical Analyses heat obtained The heat obtained from the test coals correlated very well with the heating value of the coal, on the as-fired basis, as shown in figure 1. The solid line in this graph appears to be the best straight line to repre- sent the points shown. All points between the dashed lines are within 5 percent of the value indicated by the solid line. The solid line of figure 1 does not rep- resent a direct proportionality. An exten- sion of the line intersects the axis at 2200 B.t.u instead of as required of a direct proportionality (fig. 2). The line that best represents the test data and also passes through the origin is shown in figure 2 as the "best direct proportionality" line. Within the range of heating values included in this investigation, the "direct proportion- ality" line does not vary from the "best straight line" more than 5 percent. This means that the heating value may be used for determining the relative cost of heat in many cases without making any correction for the increase in efficiency which usually accompanies an increase in heating value. Of course figure 1 should be used as a basis of comparison if available. Part IP in this series includes a table and chart to enable rapid calculation of relative cost of heat. The tests disclosed that the heat obtained correlates very well with the percentage of 8 Helfinstine, Roy J., and Boley, Charles C, op. cit. carbon, on the as-fired basis (fig. 3). Fewer plotted points are outside the ± 5 percent lines than in the case of heating value. Although the correlation of heat obtained and percentage of carbon is good, the rela- tionship will not be as useful as the one between heat obtained and heating value, because the percentage of carbon is more difficult to determine than the heating value. The percentage of ash also has a fair correlation with the heat obtained, as shown in figure 4. If the coals are divided into groups with similar percentages of oxygen the correlation is good enough to be of considerable value. Figure 5 shows the re- lationship when all coals with less than 6 percent oxygen, on the moisture and ash- free basis, are eliminated. The subbitumi- nous coal from Wyoming, which has nearly 18 percent oxygen, is likewise excluded from the graph. All the Illinois, Indiana, and western Kentucky coals tested are included except those from Gallatin County, 111. Although the correlation between heat ob- tained and ash is poorer than with heating value, ash is readily determined, hence the relationship is of considerable value. Numerous other items and combinations of items have been found to give fairly good correlation with heat obtained, such as the sum of the percentages of ash, oxygen, and nitrogen (fig. 6), fixed carbon, fixed carbon X heating value, and carbon H- (oxygen + ash). UNIFORMITY OF COMBUSTION RATE The uniformity of the rate of heat re- lease during stoker operation is considered to be a good index of stoker coal perform- ance. This characteristic is expressed as "percent variation," which is explained in detail on page 11. A low figure means the coal burns relatively uniformly (with less variation) and is therefore an indication that the coal is superior in this respect. The degree of uniformity of combustion in domestic stokers burning Midwestern coals appears to be largely dependent upon the behavior of the ash. Frequently with some coals the fire will be nearly smothered by a large clinker forming in the combus- RESULTS 13 12.0 1 1.0 CD -I or 10.0 UJ CL 9.0 CD S o" 8.0 LU 2 2 7.0 CD O 1— < 6.0 LU 5.0 4.0 ^>^r^ -Vj<<^'^- 9,000 10,000 11,000 12,000 13,000 14,000 15,000 HEATING VALUE, aiU. PER LB. AS FIRED Fig. 1. — Relationship of heat obtained per pound of coal to the heating value, on the as-fired basis. Data from R.I. 120 included. 12.0 CD 11.0 _J or 10.0 UJ Q. 9.0 3 ^ 8.0 CD 7.0 2 o" 6.0 UJ 2 5.0 < CD 4.0 O h- 3.0 < UJ X 2.0 1.0 x- /, / • BEST STRA IGHT I INE F EL ATI 0NSH1 3 "^^ ^ ■ V* ^W- tf 's «" BEST DIREC T PR )P0R1 I0NAL ^y y^A "X +- RANGI : inci .UDEC yy — w TC5Tt r=* ' 3,000 6,000 9,000 12.000 15,000 HEATING VALUE, B.T.U. PER LB. AS FIRED Fig. 2. — Best direct proportionality relationship of heat obtained per pound of coal to the heating value, on the as-fired basis. 14 DOMESTIC STOKER COMBUSTION CD 12.0 1 1.0 10.0 rr UJ Q_ z> 9.0 K m -8.0 UJ £ 7.0 CD O CD _l rr UJ Q. GO Q Ld 2 00 o 6.0 5.0 4.0 > S" o /„ J ^ •.£-"• rr^_ ^« -** * ^ ** ** -•- • 50 55 60 65 70 75 80 85 90 CARBON, AS" FIRED BASIS, PERCENT Fig. 3. — Relationship of heat obtained per pound of coal to the percentage of carbon, on the as-fired basis. Data from R.I. 120 included. 12.0 1 1.0 10.0 9.0 ; 8.o & 7.0 ao 5i0 4.0 ^ • • ••• • ^^m — ^ i -^^<- 2 • 8 10 12 14 16 18 20 22 ASH, AS- FIRED BASIS, PERCENT Fig. 4. — Relationship of heat obtained per pound of coal to the percentage of ash, on the as-fired basis. Data from R.I. 120 included. RESULTS 15 CO CO O 12.0 II. 10.0 or LU Q. P 9.0 00 2 8.0 % 7.0 6.0 5.0 4.0 • 9 • ** . 1 a* -. ^1 • ► 1 < . V • • 1 • • •H •• 8 10 12 14 16 18 20 22 ASH, AS-FIRED BASIS, PERCENT Fig. 5. — Relationship of heat obtained per pound of coal (in the 6 to 17 percent 2 range) to the percentage of ash, on the as-fired basis. Data from R.I. 120 included. 12.0 r I i.o CD 10.0 ^ 9.0 00 8.0 CD O UJ 5.0 4.0 L- 10 *• • • • • •*• • • • • • • • J^ . jr: >• %• • 8 10 12 14 16 18 20 22 < UJ O cr < UJ X ASH, AS-FIRED BASIS, PERCENT Fig. 7. — Relationship of uniformity of rate of heat release to the percentage of ash, on the as-fired basis. Data from R.I. 120 included. 25 20 15 10 O 5 • • 1 < > •• » 1 ► • 1 . • • • » • i • • • • • • ••• • - "• • •• • • • ••: • • • • 1 • • I * * ••• • $ • < ►*- • • • 1 u • • 1 • 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 SOFTENING TEMPERATURE OF ASH, °F Fig. 8. — Relationship of uniformity of rate of heat release to the softening temperature of a?h. Data from R.I. 120 included. DOMESTIC STOKER COMBUSTION 2 at 2£ 2 25 20 15 10 • f • •• • • • •• • • 4» • 1 • • ■*••• •./ •• ••V ,♦• 1 • • • •• + \ • n • • • <►*. 1 • • * • • UJ I- H < 2 * g UJ U §£ < 2 2 si U- |- < 2 UJ O I - O < > 1800 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 INITIAL DEFORMATION TEMPERATURE OF ASH, °F Fig. 9. — Relationship of uniformity of rate of heat release to the initial deformation temperature of the ash. Data from R.I. 120 included. 25 20 15 10 • • • • • • • • • • • • • • $ » • • • 1 w >• • > •• • •• - • • • 1 i • *- • < • 1 9 • • • *+■ 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 FLUID TEMPERATURE OF ASH, # F Fig. 10. — Relationship of the uniformity of rate of heat release to the fluid temperature of the ash. Data from R.I. 120 included. RESULTS 19 25 UJ o ... tr 15 < °- a: Ul UJ < < 5 -J o uj 10 a: en U. J- I < 1° • • 50 100 150 200 250 300 350 400 450 500 FLUID MINUS INITIAL DEFORMATION TEMPERATURE OF ASH Fig. 11. — Relationship of the uniformity of rate of heat release to the difference between the fluid temperature and the initial deformation temperature of the ash. 25 20 15 < rr UJ > < UJ* 15 ^ uj |0 2 i- H < 5u. 5 • < • • ► • • < 1 ( ( > 1 1 i • i ( i 1 i ► 1 < 1 1 > < < • • 1 • t « 1 • • * • < i i 1 1 1 i t : > < • • i i * 8 10 FREE-SWELLING INDEX Fig. 12. — Relationship of the uniformity of rate of heat release to the free-swelling index. Data from R.I. 120 included. 20 DOMESTIC STOKER COMBUSTION UJ < -z. Ul o UJ rr o hi < n cr hi •» > 25 20 15 10 1 ► • ^ -^' • • *** • • i • • ^ • <• • • ^•" ^ *" • • • 1.0 5.0 10 50 100 500 1,000 10,000 100,000 GIESELER MAXIMUM -FLUIDITY, DIAL DIVISIONS PER MINUTE Fig. 13. — Relationship of the uniformity of rate of heat release to Gieseler maximum fluidity. Data from R.I. 120 included. UJ o uj or o uj < Q- or - UJ UJ > £ < < UJ 2 -J o w or or 2 < O UJ P X < u. or o 25 20 15 10 • < • • » • • < • • • 4 • • • » •• « • v.- • • • • • 1 • « • * 10 15 20 25 30 35 40 45 50 VOLATILE MATTER, AS-FIRED BASIS, PERCENT Fig. 14. — Relationship of the uniformity of rate of heat release to the percentage of volatile matter, on the as-fired basis. Data from R.I. 120 included. RESULTS 21 are numerous other coals that are exceptions to the general trend. The major excep- tion is an unprepared coal from St. Clair County, 111. (coordinates of 10.0 and 20.5). Little or no correlation was evident be- tween the percentage of volatile matter in the coal and the uniformity with which it burned. Figures 14 and 15 show these relationships with volatile matter expressed on two different bases. While it is evident that all the coals that had less than 20 per- cent volatile matter on the as-fired basis did burn fairly uniformly, there were numerous high-volatile coals that performed equally well in this respect. In fact, the subbituminous coal from Wyoming, which had the highest percentage of volatile mat- ter of the coals tested (on the ash- and moisture-free basis), burned more uni- formly than any of the low-volatile coals. RESPONSIVENESS OF FIRE TO HEAT DEMANDS None of the items obtained from standard analytical tests gave very useful correlations with the responsiveness of the fire after a prolonged hold-fire period. The relation- ships with heating value, free-swelling index, and volatile matter are shown in figures 16, 17, and 18. Inasmuch as the responsiveness is based upon only one 30- minute test, a considerable part of the scatter of points may be attributed to the fact that the values for responsiveness may not be typical for each coal. PICKUP The pickup (responsiveness of the fire to a heat demand after the stoker has been off for 45 minutes) does not correlate very well with any of the items from the avail- able standard analytical tests. Although the coking and clinkering characteristics of a coal might be expected to exert considerable influence on the pickup, the correlations with the free-swelling index and ash-soften- ing temperature were found to be poor (figs. 19 and 20). This poor correlation does not mean that the coking and clinker- ing characteristics do not exert an influence on the pickup. The most logical explana- tion is that the free-swelling index and ash- softening temperature are not suitable measures of coking and clinkering charac- teristics. Evidence of this probability is presented in another section of this report. The correlation between pickup and per- centage of ash is shown to be poor in figure 21. The same is true in regard to percent- age of volatHe matter, as indicated in fig- ure 22. OVERRUN No useful correlation could be found between the tendency for the coal to cause overheating, which is called overrun in this report, and any of the items from small- scale analytical tests. The relationship be- tween overrun and the free-swelling index is shown in figure 23, and the relationship between overrun and the Gieseler soften- ing temperature is given in figure 24. Numerous other plots, not shown in this report, exhibited the same scatter of points. CLINKERING CHARACTERISTICS The clinkering characteristics of a coal are quite important when the coal is burned in the type of stoker used for these tests. As all the ash should be removed in the form of clinker, the ratio of ash released to clinker removed should become unity after a normal fuel bed is established. The rela- tively short test period (one week) used in this investigation precludes a value of unity and probably fails to determine the ability of an individual coal to form the desired amount of clinkers. However, the tests were considered adequate to reveal any general relationship between the ability of a coal to clinker and its ash-softening temperature. Figure 25 shows that the correlation is very poor. The Paris seam coal from Arkansas had the lowest clinker- ash ratio (0.22) although its softening tem- perature was only 2021° F. The Indiana IV seam coal behaved in a reverse fashion. Its softening temperature was 2552° F., which is above the range usually considered satisfactory for clinkering-type domestic stokers, yet 62 percent of the ash released during the test was removed in the form of clinker. Anomalies of this magnitude certainly cannot be credited to test vagaries. The only reasonable conclusion is that the ash-softening temperature is of little or no 22 DOMESTIC STOKER COMBUSTION < 2 or - UJ UJ > co < < O uj cr rr Z < o ui p x < u. 25 20 15 10 • • • 4 :• • • • •• i • • • 9 • • • •1 . •*• • • • • t •••-;• • • • « >• + i* •«t • • • >1 • • •< • • 10 15 20 25 30 35 40 45 50 55 60 VOLATILE MATTER, MOISTURE- AND ASH-FREE BASIS , PERCENT Fig. 15. — Relationship of the uniformity of rate of heat release to the percentage of volatile matter, on the moisture and ash-free basis. Data from R.I. 120 included. .50 .45 .40 .35 < or .30 CO CO UJ .25 z UJ > CO .20 z o 0- .lb co 05 • • • • *• • • • • • 1 • .< • 1 • • • • • • • • .' » s • ••• 1 • • • • • • •• • • 4 • • • 1 • . • • • • 1 4 • 9,000 10,000 1,000 12,000 13,000 14,000 15,000 HEATING VALUE, B.T.U. PER LB. AS FIRED Fig. 16. — Relationship of the responsiveness ratio to the heating value, on the as-fired basis. Data from R.I. 120 included. RESULTS 23 > z o UJ .50 .45 .40 .35 .30 .25 .20 .15 .10 .05 i 1 • 1 > 1 ► • ► < 1 , 1 > 4 ® 1 < > • • i i < i < 1 i t > 5 < • • > > • i < ► • < ► 1 ► • < t < ► i > < ► i • > • < • ► i ► 8 10 FREE- SWELLING INDEX Fig. 17. — Relationship of the responsiveness ratio to the free-swelling index. Data from R.I. 120 included. O H < if) (f) -z. o Q- U) UJ cr .50 .45 .40 .35 .30 .25 .20 .15 .10 .05 # « • • • • . • • • • i •• • • f < • i :\ v • o • 4 ©• • • • > • ► • o 10 Fig. 18 20 25 30 35 40 45 50 VOLATILE MATTER, AS-FIRED BASIS, PERCENT — Relationship of the responsiveness ratio to the volatile matter, on the as-fired basis. Data from R.I. 120 included. 24 DOMESTIC STOKER COMBUSTION .40 .36 .32 .28 Q_ * .24 o a. .20 .16 .12 o o • (I (I > ,, « (I II O • • II O II (I • II II • II • • • it ii • o • n • ii ,, • 8 10 .40 36 32 .28 Q. g .24 .20 .16 FREE-SWELLING INDEX Fig. 19. — Relationship of the pickup ratio to the free-swelling index. Data from R.I. 120 included. .12 • • • • • • • • i • i i m • • •• • m »• i < ►+ • < » i • • • • • • • ••• • • m • • 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 SOFTENING TEMPERATURE OF ASH, °F Fig. 20. — Relationship of the pickup ratio to the softening temperature of the ash. Data from R.I. 120 included. RESULTS 25 .40 36 .32 < .28 o a. .20 .16 12 1 • • • • < » •• • > • •• i • > • • i • • • • • 4» • • • • • • m • •• i • • • • m m • • • 4 • • 8 10 12 14 16 18 20 22 ASH, AS-FIRED BASIS , PERCENT Fig. 21. — Relationship of the pickup ratio to the percentage of ash, on the as-fired basis. Data from R.I. 120 included. 40 .36 32 < .28 0- 3 24 o .20 16 .12 • • • • 4 • • « • •• < • • • m • • • — • • 10 15 20 25 30 35 40 45 50 55 60 VOLATILE MATTER, MOISTURE- AND ASH- FREE BASIS, PERCENT Fig. 22. — Relationship of the pickup ratio to the percentage of volatile matter, on the moisture- and ash-free basis. Data from R.I. 120 included. 26 DOMESTIC STOKER COMBUSTION .60 .55 50 z 3 cr £ .45 .40 .35 n • • II o < • • • i • (> <£ j _ _ # • I 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 SOFTENING TEMPERATURE OF ASH, °F Fig. 25. — Relationship of the clinker-ash ratio to the softening temperature of the ash. Unpublished data included. 3.5 U 3.0 >- > < o LU CL cn < Q- < 2.5 2.0 1.5 1.0 < •_• * !! ! • •• ! ! !__.^, • ¥ "» .15 .20 .25 .30 .35 .40 .45 .50 .55 .60 .65 .70 .75 .80 CLINKER-ASH RATIO Fig. 26. — Relationship of the apparent specific gravity of the clinker to the clinker-ash ratio. RESULTS 29 100 90 x UJ Q 80 on £ 70 < X if) i or UJ ? 50 o 40 60 • • II • — w—m - • " 30 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 SOFTENING TEMPERATURE 0FASH,°F Fig. 27. — Relationship of the clinker-shatter index to the softening temperature of the ash. 100 90 2 80 a: 70 < I en 60 rr UJ Y 2 50 _l O 40 30 • • • • • i > • • / • •• m • • • • < > • • 1 1 ^s • ^ • 15 .20 .25 .30 .35 .40 .45 .50 .55 .60 .65 .70 .75 .80 CLINKER -ASH RATIO Fig. 28. — Relationship of the clinker-shatter index to the clinker-ash ratio. 30 DOMESTIC STOKER COMBUSTION 100 90 x LU 9 80 H 70 < ? 60 or hi o 40 30 • » 1 • • • • • • • • t 1 • •• • • • .5 I.O 2.0 2.5 3.0 3.5 I2.0 I I.O CD _l or I0.0 Id DL => 9.0 GO 2 8.0 o" LU | 7.0 CD O H 60 < LU X 5.0 4.0 APPARENT SPECIFIC GRAVITY OF CLINKER Fig. 29. — Relationship of the clinker-shatter index to the apparent specific gravity of the clinker. rr— ^-^^ »■ T^ J**^ * >^ IP • 30 35 40 45 50 55 60 65 70 75 80 FIXED CARBON, AS-FIRED BASIS, PERCENT Fig. 30. — Relationship of heat obtained per pound of coal to the percentage of fixed carbon, on the as-fired basis. CONCLUSIONS 31 this investigation, some of the test results are listed in order of superiority as an aid to those who wish to compare them. It should be remembered that the coals tested are not necessarily typical of those being sold from the indicated source. In fact, a few coals are known to differ considerably from the coal usually marketed from the locality. The Arkansas and Douglas County, 111., coals received special prepara- tion in the Survey laboratories and are therefore excluded from the tables that follow. Table 2 lists the stoker coals in order of their uniformity of burning. Inasmuch as the percent variation in tests repeated with the same coal may differ by as much as one percentage figure with the more uniformly burning coals and by five percentage figures with coals of extremely variable perform- ance, the relative positions of the coals tested should be considered only approxi- mate. In other words, the Sheridan County, Wyo., and the Grundy County, 111., coals should be considered equal in respect to their uniformity of combustion. The relative amount of heat obtained per pound of coal burned is shown in table 3. Table 4 shows the restive position of the coals with respect to the amount of heat that would be obtained per pound of ash formed. This table gives an approxi- mation of the relative amount of ash that must be removed, presumably in the form of clinker, for the same amount of heat. A difference in heat obtained per pound of coal of less than 0.2 M B.t.u. should not be considered significant. Although the Eastern coals tested gen- erally supplied more heat per pound of coal, or per pound of ash, their greater cost per ton delivered to Illinois usually more than offsets their higher heating value. As far as nearby coals are concerned, Illinois coals likewise enjoy an excellent competitive posi- tion in regard to heat obtained per dollar. Table 5 gives the relative position of the coals in regard to responsiveness to demand for heat after a prolonged hold-fire period. Inasmuch as the values were obtained from onlv one cycle of operation, differences of 0.03 or less in the ratio should not be con- sidered significant. Table 6 gives the rela- tive position of the coals in regard to pickup (responsiveness after the stoker had been off for 45 minutes). As the figures are based on 40 cycles of operation, a dif- ference in pickup ratio of 0.02 or more is considered significant. Tables 5 and 6 show that several Illinois coals are very good in respect to their responsiveness to heat demand. CONCLUSIONS The useful heat obtained from the coals exhibited a good correlation with the heat- ing value on the as-fired basis. Although a slight increase in efficiency accompanied an increase in heating value, the increase was small, hence the cost of heat will closely approximate the relative cost per B.t.u. as determined by standard analytical methods. The heat obtained also correlated very well with the percentage of carbon. The correlation with percentage of ash was fair when the comparison was limited to Mid- western coals. The uniformity of rate of heat release during stoker operation is thought to be a good index of stoker coal performance. The tests indicated that the best correlation with this characteristic was probably the percent- age of ash. However, there were numerous exceptions to the general trend of more uniform combustion accompanying a de- crease in percentage of ash. The periodic formation of clinkers certainly influenced the rate of combustion. However, the cor- relation of the uniformity of heat release with the initial deformation, softening, or fluid temperatures of the ash was very poor. Observation also indicated that the peri- odic formation and combustion of coke trees had some influence on the uniformity of combustion, although the correlation of free-swelling index with the uniformity of heat release proved to be very poor. The fluid properties of the coals, as indi- cated by the Gieseler plastometer, appear to have some correlation with the uniform- ity of rate of heat release. However, there 32 DOMESTIC STOKER COMBUSTION were many exceptions to the general trend of improved uniformity accompanying a decrease in fluidity. Little or no correlation was evident between the percentage of volatile matter in coal and the uniformity with which it burned. None of the items obtained by standard analytical tests gave useful correlations with the responsiveness of the fire after a pro- longed hold-fire period. The responsiveness of the fire to a heat demand after the stoker had been off for a relatively short period (pickup) did not correlate very well with any of the items obtained from standard analytical tests. The correlations with the tendency for the coal to cause overheating (overrun) were likewise poor. There was little or no correlation be- tween the percentage of ash fused into clinker and the ash-fusion temperatures. Two, and perhaps three, coals with ash- softening temperatures higher than 2600° F. formed a satisfactory proportion of clinker while some in the 2000° F. range did not. No useful correlation was found between any of the items obtained from standard analytical tests and the shatterability of the clinker. In general, the coals which clinkered most readily were most resistant to break- age. The tests disclosed that actual combus- tion tests are the only satisfactory way to determine the suitability of a coal for use in a domestic stoker. The standard analyti- cal tests are of very limited value in pro- viding indexes to most performance char- acteristics. The correlations of standard analytical test results and combustion characteristics of coals in a domestic stoker were essen- tially the same for out-of-state coals and for Illinois coals. The tests indicate that many Illinois coals rate high as domestic-stoker coals. APPENDIX 34 DOMESTIC STOKER COMBUSTION Table 1. — Source and Identification of Coals iple No. County State Seam 1 2 3 4 5 6 7 8 9 10 11 12 13 Ark. 1 Ark. 2 Ark. 3 Ark. 4 Ind. 1 Ind. 2 Ind. 3 Ind. 4 Ind. 5 Ind. 6 Ind. 7 la. 1 Ky. Ky. Ky. Ky. Ky. Mo. 1 2 3 4 5 1 Mo. 2 Ohio 1 W. Va. 1 W. Va. 2 W. Va. 3 W. Va. 4 W yo. 1 Douglas. . Grundy . . Franklin. Fulton . . . Knox. . . . Grundy . . Christian. Saline. . . . Saline. . . . Randolph . Jackson. . Bureau. . . St. Clair.. Sebastian. Johnson. . Sebastian. Logan Vigo Vigo Gibson. . . Fountain. Clay Greene. . . Greene. . . Dallas. . . Harlan. . . Perry .... Hopkins. . Hopkins. . Letcher. . Randolph . Macon . . . Athens' 1 . . Marion. . . Wyoming. McDowell Webster. . Sheridan . Illinois Illinois Illinois Illinois Illinois Illinois Illinois Illinois Illinois Illinois Illinois Illinois Illinois Arkansas. . . . Arkansas. . . . Arkansas. . . . Arkansas .... Indiana Indiana Indiana Indiana Indiana Indiana Indiana Iowa Kentucky . . . Kentucky. . . Kentucky . . . Kentucky . . . Kentucky . . Missouri .... Missouri .... Ohio. . West Virginia West Virginia West Virginia West Virginia Wyoming. . . . No. No. No. No. No. No. No. No. No. No. No. No. No. Hartshorne Hartshorne (Spadra) Hartshorne Paris IV III V Minshall Brazil VI VII Third seam No. 5 Hazard No. 4 No. 11 No. 6 Elkhorn Bevier Mulky Middle Kittaning a Pittsburgh Beckley Pocahontas No. 4 Sewell Monarch 8 There is some doubt about the true source of this coal. APPENDIX 35 Table 2.- —Variation in Rate of Heat Release STATE COUNTY SEAM PERCENT VARIATION 5 10 15 20 Wyo Sheridan Monarch III. Grundy No. 2 Ind. Vigo IV III. Knox No.6 W.Va. M c Dowcll Poca.4 WVa. Wyoming Beckley Ind. Clay Brazil Ind. Greene VII IN. Franklin No.6 Ky Hopkins No.6 Ky. Perry Hazard 4 Iowa Dallas Third W.Va. Webster Sewell Ky. Harlan No. 5 Ky. Letcher Elkhorn III. Bureau No.6 in. Saline No.5 Mo. Macon Mulky Ind. Fountain Minshall III. Grundy No.7 Ind. Vigo Ml III. Christian No.6 III. Jackson No.6 Ky. Hopkins No.ll Ill Randolph No 6 Ind. Gibson V III. Saline No.6 Mo. Randolph Bevier Ind. Greene VI III. St.Clair No 6 III. Fulton No.5 W.Va Marion Pittsburgh 36 DOMESTIC STOKER COMBUSTION Table 3. — Heat Obtained per Pound of Coal STATE COUNTY SEAM HEAT OBTAINED, M. B.T.U. PER LB. 8 10 W.Va. M c Dowell Poca. 4 W.Va Webster Sewell W.Va. Wyoming Beckley Ky. Harlan No. 5 Ky. Perry Hazard No4 Ky. Letcher Elkhorn W.Va. Marion Pittsburgh Ky. Hopkins No. 6 III. Saline No. 6 m. Saline No. 5 in. Franklin No. 6 Ky. Hopkins Noll III. Jackson No 6 in. Grundy No. 2 III. Knox No.6 Ind. Greene VII Mo. Macon Mulky III. Randolph No.6 III. St. Clair No.6 Ind. Vigo III Ind. Clay Brazil Mo Randolph Bevier Ind. Greene VI III. Grundy No. 7 Ind. Vigo IV III. Bureau No- 6 III. Christian No-6 III. Fulton No- 5 Wyo. Sheridan Monarch Ind. Gibson V Ind. Fountain Minshall Iowa Dallas Third APPENDIX 37 Table 4. — Heat Obtained per Pound of Ash Formed STATE COUNTY SEAM HEAT OBTAINED M BTU PER LB. OF ASH 50 100 150 200 250 Ky. Hopkins No.6 Ky. Perry Hazard 4 Ky. Harlan No. 5 W.Va. Webster Sewell Ky- Hopkins Noil Hi Grundy No. 2 W.Vo. M c Dowel 1 Poca. 4 Wyo. Sheridan Monarch Mo. Macon Mulky Ky. Letcher Elkhorn Ind. Vigo IV W.Va. Marion Pittsburgh Ill Franklin No.6 III. Knox No-6 W.Vo Wyoming Beckley Ind. Greene VII HI. Saline No.5 Mo. Randolph Bevier 111. Saline No.6 III. Jockson No 6 Ind. Vigo III III. St.Clair No.6 III. Grundy No. 7 III. Randolph No.6 III. Bureau No 6 III. Fulton No.5 Ind. Clay Brazil III. Christian No.6 Ind Fountain Minsnall Ind. Greene VI Ind. Gibson V lowo Dallas Third 38 DOMESTIC STOKER COMBUSTION Table 5. — Responsiveness of Fire to Heat Demand STATE COUNTY SEAM RESPONSIVENESS RATIO 0.10 020 030 0.40 III Grundy No. 2 Wyo. Sheridan Monarch Ind. Greene VII Ind. Greene VI Ill Bureau No-6 Iowa Dallas Third III Fulton No5 Ind. Vigo IV W.Va. M c Dowell Poca.4 III. Grundy No. 7 Ind. Cloy Brazil Mo. Randolph Bevier III. Randolph No6 III. St. Clair No. 6 Mo. Macon Mulky III. Franklin No.6 III. Christian No. 6 III. Saline No. 5 Ill Knox No.6 Ky. Perry Hazard 4 W.Va. Wyoming Beckley Ky- Hopkins No6 Ky. Harlan No. 5 Ky. Hopkins No. II III. Jackson No-6 Ind. Vigo III Ind. Fountain Minshall Ky. Letcher Elkhorn Ind. Gibson V W.Va. Webster Sewell III. Soline No-6 W.Va. Marion Pittsburgh APPENDIX 39 Table 6.- —Pickup Ratios COUNTY SEAM PICKUP RATIO STATE 0.15 020 0.25 0.30 Wyo. Sheridan Monarch III. Grundy No. 2 III. St.Clair No. 6 III. Bureau No.6 Ind. Greene VII Ky. Perry Hazard 4 Ky. Hopkins No. II Mo. Randolph Bevier Ind. Gibson V Ind. Greene VI Iowa Dallas Third W.Va. Webster Sewell W.Va. Wyoming Beckley WVa. Marion Pittsburgh Ill Christian No. 6 III. Jackson No. 6 III. Randolph No. 6 III. Saline No.6 Ind Vigo IV Ind. Vigo III Ind. Clay Brazil W.Va. M c Dowell Poca.4 III. Franklin No.6 HI. Saline No. 5 III. Knox No.6 III. Grundy No. 7 III. Fulton No. 5 Ky. Hopkins No.6 Mo. Macon Mulky Ind. Fountain Minshall Ky. Letcher Elkhorn Ky. Harlan No. 5 40 DOMESTIC STOKER COMBUSTION Table 7. — Size Analyses of Coals Sample No. 111. 1 . . 111. 2.. 111. 3.. 111. 4. . 111. 5.. 111. 6.. 111. 7.. 111. 8.. 111. 9.. 111. 10.. 111. 11.. 111. 12. . 111. 13.. Ark. 1R. Ark. 1W. Ark. 2R . Ark. 2W. Ark. 3R . Ark. 3W. Ark. 4R . Ark. 4VV Ind. 1 . . Ind. 2. . Ind. 3.. Ind. 4.. Ind. 5.. Ind. 6.. Ind. 7.. Iowa 1 . . Ky. 1 . . Ky. 2.. Kv. 3.. Ky. 4. . Ky. 5.. Mo. 1 . . Mo. 2. . Ohio 1 . . W. Va. 1.. W. Va. 2. . W. Va. 3.. W. Va. 4.. Wyo. 1 . . ■H' 3.8 9.9 9.9 4.0 5.8 12.2 1XK* KXH a Y2Xh* K a X3 b 3X4 b 4X6 b 6X8 b 8X10 b 10XH b 14X20 b 14 9 15.5 21 14.7 10.8 9.1 7.4 3.9 1.2 4.1 29.1 19.9 24.5 13.4 4.6 1.7 0.8 0.5 0.2 3.9 23.4 15.5 17.8 11.1 8.1 8.3 5.6 2.8 1.8 27.5 33.1 27.6 5.3 1.8 1.0 0.7 0.5 0.4 6.3 51.2 26.9 8.3 1.9 1.0 0.7 0.6 0.4 0.3 4.1 33.0 17.9 21.3 14.2 4.4 1.7 0.9 0.5 0.3 2.3 12.0 19.4 14.7 11.9 11.8 10.3 7.1 4.3 7.0 44.6 13.6 10.8 6.4 4.7 3.9 3.2 1.9 1.2 23.2 26.8 23.8 11.1 5.0 3.3 2.4 1.5 0.9 25.8 24.8 30.3 11.8 2.7 1.4 0.9 0.5 0.3 20.9 33.3 25.7 10.5 3.5 2.1 1.7 1.5 0.7 5.6 15.3 11.4 15.3 11.0 9.1 9.4 7.6 4.3 2.6 25.5 26.9 29.4 10.5 2.5 1.3 0.9 0.6 0.4 5.1 10.6 11.9 13.7 14.6 15.7 13.6 5.3 2.4 28.9 9.1 11.6 11.6 14.1 10.8 4.4 11.3 10.3 12.4 15.5 11.8 12.2 12.1 8.0 2.0 5.4 8.4 9.1 12.9 13.2 14.1 14.6 11.5 4.3 10.4 14.6 16.3 13.8 13.8 13.8 9.5 2.2 111 14.7 15.3 13.0 12.3 11.3 7.9 3.9 12.6 10.9 9.9 10.8 13.9 11.4 13.8 10.0 2.4 17.5 11.8 14.8 13.2 13.6 10.8 9.0 5.0 1.4 23.5 44.5 14.6 8.5 1.7 0.8 0.5 0.4 0.2 0.2 27.8 28.4 27.9 7.4 3.1 1.6 1.0 0.6 0.4 15.2 24.0 13.7 20.7 14.8 6.0 1.8 0.9 0.5 0.3 17.0 32.9 13.3 16.0 5.4 1.8 0.9 0.6 0.4 0.3 14.0 33.9 15.9 16.4 6.9 3.8 2.3 1.6 1.1 0.6 8.6 18.2 23.9 15.0 9.7 8.4 6.9 4.4 2.2 10.7 20.4 24.5 13.9 10.0 8.4 6.8 3.5 0.9 16.7 26.6 12.1 13.2 7.8 4.4 2.1 1.4 0.9 0.7 11.7 25.4 12.6 18.5 13.5 10.0 5.5 1.4 0.5 0.2 4.1 26.1 19.9 25.2 15.7 5.7 1.6 0.6 0.3 0.1 20.8 37.5 16.1 16.0 6.2 1.3 0.8 0.4 0.3 0.2 30.5 21.7 23.4 12.2 5.5 4.5 2.0 0.2 0.0 2.0 20.9 15.0 22.0 12.8 5.6 4.4 3.6 2.5 2.0 6.6 32.7 16.5 16.5 111 7.2 4.5 2.1 0.9 0.5 41.2 40.7 8.9 4.1 1.0 0.6 0.5 0.4 0.3 0.3 20.0 34.8 13.7 11.7 4.1 2.3 1.9 1.5 1.1 0.9 33.2 42.7 7.3 3.0 1.3 0.8 0.7 0.7 0.5 0.5 9.3 18.0 29.5 18.8 9.2 3.6 2.5 1.6 1.2 13.0 29.4 33.1 13.8 3.7 14 1.2 0.8 0.6 19.6 24.7 31.4 12.1 3.1 1.9 1.6 1.1 0.8 50.0 23.1 4.8 3.6 1.6 0.8 0.6 0.5 0.4 0.3 ■ Square openings in inches. b Tyler mesh series. APPENDIX 41 Table 8. — Proximate Analyses of Coals pie 3. PROXIMATE ANALYSIS Sam As Fired Moisture Free Moisture and Ash Free Dry Mineral Matter Free Moist Mineral Matter Free N< Mois- Vola- Fixed Vola- Fixed Vola- Fixed Vola- Fixed Mois- Vola- Fixed Ash, tile Car- Ash, tile Car- tile Car- tile Car- tile Car- ture, % % Matter, bon, % Matter, bon, Matter, bon, Matter, bon, ture, % Matter, bon, % % % % % % % % % % 111. 1 11.5 6.6 37.8 44.1 7.5 42.7 49.8 46.2 53.8 45.5 54.5 12.5 39.8 47.7 111. 2 9.9 5.4 38.0 46.7 6.0 42.2 51.8 44.9 55.1 44.3 55.7 10.6 39.5 49.9 111. 3 9.2 7.6 32.7 50.5 8.4 36.0 55.6 39.3 60.7 38.7 61.3 10.1 34.8 55.1 111. 4 16.0 9.4 34.8 39.8 11.2 41.4 47.4 46.7 53.3 45.6 54.4 18 1 37.4 44.5 111. 5 12.7 7.0 36.9 43.4 8.0 42.3 49.7 46.0 54.0 45.2 54.8 13.9 38.9 47.2 111. 6 10.6 9.0 39.6 40.8 10.0 44.3 45.7 49.2 50.8 48.3 51.7 12.0 42.5 45.5 111. 7 9.8 12.3 33.3 44.6 13.6 37.0 49.4 42.8 57.2 41.3 58.7 11.6 36.4 52.0 111. 8 5.3 9.6 36.7 48.4 10.1 38.8 51.1 43.2 56.8 42.1 57.9 6.0 39.5 54.5 111. 9 5.6 9.4 33.4 51.6 9.9 35.4 54.7 39.3 60.7 38.3 61.7 6.3 35.9 57.8 111. 10 9.3 9.6 36.6 44.5 10.5 40.4 49.1 45.2 54.8 44.0 56.0 10.6 39.3 50.1 111. 11 7.8 9.4 36.7 46.1 10.2 39.8 50.0 44.3 55.7 43.3 56.7 8.8 39.5 51.7 111. 12 12.0 9.2 36.2 42.6 10.4 41.1 48.5 45.9 54.1 44.8 55.2 13.6 38.8 47.6 III. 13 10.2 9.1 39.0 41.7 10.2 43.4 46.4 48.3 51.7 47.3 52.7 11.5 41.9 46.6 Ark. 1R Ark. 1W 1.5 7.0 17.3 74.2 7.1 17.6 75.3 19.0 81.0 18.12 81.88 1.63 17.79 80.58 Ark. 2R 2.5 13.9 12.0 71.6 14.2 12.3 73.5 14.4 85.6 11.9 88.1 3.0 11.6 85.4 Ark. 2W 2.1 6.6 6.8 Ark. 3R 1.8 8.7 8.8 Ark. 3W 1.7 6.8 19.7 71.8 7.0 20.1 72.9 21.6 78.4 20.88 79.12 1.84 20.42 77.74 Ark. 4R 1.2 18.1 18.3 Ark. 4W 1.3 10.5 17.6 70.6 10.7 17.8 71.5 20.0 80.0 18.34 81.66 1.49 18.10 80.41 Ind. 1 13.6 6.2 29.8 50.4 7.2 34.5 58.3 37.2 62.8 36 . 6 63.4 14.6 31.2 54.2 Ind. 2 7.5 8.6 41.1 42.8 9.3 44.4 46.3 49.0 51.0 47.9 52.1 8.5 43.9 47.6 Ind. 3 10.1 13.7 33.7 42.5 15.2 37.4 47.4 44.2 55.8 42.9 57.1 12.0 37.8 50.2 Ind. 4 11.2 11.0 39.9 37.9 12.4 44.9 42.7 51.3 48.7 50.1 49.9 13.0 43.6 43.4 Ind. 5 13.2 11.7 33.0 42.1 13.5 38.1 48.4 44.0 56.0 43.2 56.8 15.2 36.5 48.3 Ind. 6 7.7 13.2 35.9 43.2 14.2 38.9 46.9 45.4 54.6 44.0 56.0 9.2 40.0 50.8 Ind. 7 9.6 8.0 36.3 46.1 8.9 40.1 51.0 44.0 56.0 43.4 56.6 10.6 38.8 50.6 Iowa 1 14.0 16.4 34.1 35.5 19.0 39.7 41.3 49.0 51.0 47.2 52.8 17.5 38.9 43.6 Ky. 1 2.5 4.6 37.7 55.2 4.8 38.6 56.6 40.6 59.4 40.2 59.8 2.6 39.1 58.3 Ky. 2 3.5 4.1 38.1 54.3 4.3 39.5 56.2 41.2 58.8 40.9 59.1 3.7 39.3 57.0 Ky. 3 7.5 5.4 40.6 46.5 5.8 43.9 50.3 46.6 53.4 45.9 54.1 8.1 42.1 49.8 Ky. 4 9.9 3.6 38.7 47.8 4.0 43.0 53.0 44.8 55.2 44.3 55.7 10.4 39.7 49.9 Kv. 5 3.0 7.3 35.1 54.6 7.5 36.2 56.3 39.1 60.9 38.6 61.4 3.3 37.3 59.4 Mo. 1 13.0 8.2 38.3 40.5 9.4 44.0 46.6 48.6 51.4 47.4 52.6 14.6 40.5 44.9 Mo. 2 9.6 5.8 42.0 42.6 6.4 46.4 47.2 49.6 50.4 48.6 51.4 10.5 43.6 45.9 Ohio 1 7.0 10.9 36.8 45.3 11.7 39.6 48.7 44.8 55.2 43.7 56 3 8.1 40.2 51.7 W. V i. 1 1.5 7.5 40.3 50.7 7.7 40.9 51.4 44.3 55.7 43.4 56.6 1.7 42.7 55.6 W. Va. 2 1.2 8.7 18.6 71.5 8.8 18.9 72.3 20.7 79.3 19.9 80.1 1.3 19.5 79.2 W. V i. 3 2.0 7.5 15.1 75.4 7.6 15.4 77.0 16.7 83.3 15.9 84.1 2.2 15.6 82.2 W. Va. 4 2.0 5.5 28.7 63.8 5.6 29.3 65.1 31.0 69.0 30.5 69.5 2 1 29.9 68.0 Wyo. 1 20.9 5.1 38.4 35.6 6.5 48.5 45.0 51.9 48.1 51.5 48.5 22.2 40.1 37.7 42 DOMESTIC STOKER COMBUSTION Table 9. — Ultimate Analyses of Coals ULTIMATE ANALYSIS As Fired Moisture Free Moisture and Ash Free ScHT**"*'* 3 N o. Hy- dro- gen, % Car- bon, % Ni- tro- gen, % Oxy- gen, % Sul- fur, % Ash, % Hy- dro- gen, % Car- bon, % Ni- tro- gen, % Oxy- gen, % Sul- fur, % Ash, % Hy- dro- gen, % Car- bon, % Ni- tro- gen, % Oxy- gen, % Sul- fur. % 111. 1 5.89 65 . 68 1.60 18.42 1.80 6.61 5.22 74.23 1.80 9.25 2.03 7.47 5.64 80.23 1.95 9.99 2.19 111. 2 5.77 68.04 1.30 17.58 1.86 5.45 5.18 75.51 1.45 9.74 2.07 6.05 5.51 80.37 1.54 10.38 2.20 III. 3 5.42 67.87 1.61 16.60 0.88 7.62 4.85 74.77 1.78 9.24 0.97 8.39 5.29 81.62 1.94 10.09 1.06 111. 4 5.88 59.93 1.17 21.16 2.49 9.37 4.90 71.28 1.39 8.33 2.96 11.14 5.52 80.22 1.57 9.36 3.33 111. 5 5 81 64.05 1.32 19.48 2.34 7.00 5.04 73.35 1.51 9.40 2.68 8.02 5.48 79.74 1.64 10.23 2.91 111. 6 5.75 63.83 1.33 17.24 2.89 8.96 5.12 71.42 1.49 8.72 3.23 10.02 5.69 79.37 1.65 9.70 3.59 111. 7 5.39 61.02 1.22 16.42 3.67 12.28 4.77 67.72 1.35 8.45 4.08 13.63 5.53 78.40 1.57 9.78 4.72 111. 8 5.32 69.03 1.59 11.69 2.82 9.55 4.99 72.90 1.67 7.37 2.98 10.09 5.55 81.08 1.86 8.19 3.32 111. 9 5.23 69.82 1.78 11.84 2.00 9.33 4.88 74.00 1.88 7.23 2.12 9.89 5.41 82.12 2.09 8.02 2.36 111. 10 5.45 63.97 1 32 16.60 3.07 9.59 4.87 70.54 1.46 9.17 3.39 10.57 5.44 78.88 1.63 10.26 3.79 111. 11 5.50 67.35 1.39 13.77 2.62 9.37 5.03 72.99 1.50 7.49 2.84 10.15 5.60 81.24 1.67 8.33 3.16 111. 12 5.75 61.03 1.04 20.16 2.87 9.15 5.02 69.37 1.18 10.77 3.26 10.40 5.60 77.42 1.32 12.02 3.64 111. 13 5.71 63.74 1.26 17.07 3.10 9.12 5.09 71.04 1.40 8.84 3.46 10.17 5.67 79.08 1.56 9.84 3.85 Ark. 1R Ark. 1W 4.51 82.35 2.11 2.98 0.99 7.06 4.41 83.62 2.14 1.66 1.01 7.16 4.75 90.07 2.31 1.79 1.08 Ark. 2R 3.73 74.77 1.48 3.09 3.05 13.88 3.54 76.68 1.51 0.90 3.13 14.24 4.13 89.40 1.76 1.06 3.65 Ark. 2W Ark. 3R Ark. 3W 4.43 83.12 1.89 2.92 0.82 6.82 4.31 84.55 1.93 1.42 0.84 6.95 4.64 90.87 2.07 1.52 0.90 Ark. 4R Ark. 4W 4.27 79.78 1.70 1.37 2.38 10.50 4.18 80.83 1.72 0.23 2.41 10.63 4.67 90.38 1.93 0.33 2.69 Ind. 1 6.01 66.18 1.57 19.45 0.65 6.14 5.20 76.57 1.81 8.56 0.75 7.11 5.60 82 . 43 1.95 9.22 0.80 Ind. 2 5.71 67.38 1.35 13.31 3.61 8.64 5.28 72.83 1.46 7.19 3.90 9.34 5.82 80.29 1.61 7.98 4.30 Ind 3 5.39 61.81 1.34 15.93 1.87 13.66 4.74 68 . 76 1.49 7.73 2.08 15.20 5.59 81.08 1.76 9.12 2.45 Ind. 4 5.82 61.52 1.28 16.81 3.57 11.00 5.15 69.28 1.44 7.72 4.02 12.39 5.88 79.08 1.65 8.80 4.59 Ind. 5 5.55 61.01 1.31 19.70 0.78 11.65 4.73 70.00 1.50 9.51 0.90 13.36 5.46 80.80 1.73 10.97 1.04 Ind. 6 5.34 63.53 1.32 13.76 2.89 13.16 4.86 68.80 1.42 7.54 3.13 14.25 5.67 80.24 1.66 8.78 3.65 Ind. 7 5.65 66.56 1.49 17.22 1.09 7.99 5.07 73.61 1.64 9.63 1.21 8.84 5.56 80.74 1.80 10.58 1.32 Iowa 1 5.48 54.36 1.14 18.46 4.21 16.35 4.56 63.18 1.33 7.04 4.89 19.00 5.63 78.00 1.64 8.69 6.04 Ky. 1 5.46 78.21 1 .63 9.32 0.70 4.68 5.32 80.24 1.67 7.25 0.72 4.80 5.58 84.28 1.76 7.62 0.76 Ky. 2 5.45 77.09 1.69 10.66 0.96 4.15 5.25 79.85 1.75 7.85 1.00 4.30 5.48 83.44 1.83 8.21 1.04 Ky. 3 5.72 70.00 1.47 14.66 2.84 5.31 5.29 75.62 1.59 8.70 3.07 5.73 5.61 80.21 1.69 9.23 3.26 Ky. 4 5.80 70.13 1.77 17.03 1.65 3.62 5.20 78 . 04 1.96 8.93 1.84 4.03 5.42 81.32 2.05 9.30 1.91 Ky. 5 5.18 75.78 1.63 9.39 0.76 7.26 5.00 78.07 1.68 6.99 0.78 7.48 5.40 84.39 1.82 7.55 0.84 Mo. 1 5.70 61.97 1.14 19.12 3.91 8.16 4.90 71 . 10 1.31 8.83 4.50 9.36 5.40 78.45 1.45 9.74 4.96 Mo. 2 5.84 66.14 1.18 16.66 4.39 5.79 5.29 73.12 1.30 9.04 4.85 6.40 5.65 78.12 1.39 9.66 5.18 Ohio 1 5.26 65.50 1.41 14.23 2.69 10.91 4.82 70.43 1.51 8.62 2.89 11.73 5.46 79.79 1.71 9.77 3.27 W. \ r a. 1 5.50 76.33 1.56 6.14 2.89 7.58 5.41 77.48 1.58 4.91 2.93 7.69 5.86 83.94 1.71 5.32 3.17 W. Va. 2 4.36 81.07 1.56 3.56 0.71 8.74 4.27 82.06 1.58 2.52 0.72 8.85 4.68 90.02 1.73 2.78 0.79 W. Va. 3 4.21 82.61 1.27 3.94 0.50 7.47 4.07 84.29 1.29 2.22 0.51 7.62 4.41 91.25 1.40 2.39 0.55 W. Va. 4 5.11 80.90 1.60 6.05 0.78 5.56 4.98 82.75 1.63 4.16 0.79 5.69 5.28 87.74 1.73 4.41 0.84 Wyo . 1 6.22 55.18 1.33 31.58 0.52 5.17 4.92 69.78 1.68 16.42 0.66 6.54 5.27 74.66 1.80 17.56 0.71 APPENDIX 43 Table 10.— Heati ng Values and Sulfur Varieties pie ). HEATING VALUE, B.T.U. PER LB. SULFUR VARIETIES Sam Nc As Moist Moist and Ash Free Unit Coal Unit Coal As Fired Moisture Free Moisture and Ash Free Fired Free Dry Moist Sul- fate Pyritic Or- ganic Sul- fate Pyritic Or- ganic Sul- fate Pyritic Or- ganic 111. 1 11901 13444 14530 14698 12855 .11 .82 .87 .12 .92 .99 .13 1.00 1.06 111. 2 12210 13546 14415 14551 13008 .05 1.05 .76 .05 1.16 .86 .06 1.24 .90 111. 3 11953 13162 14372 14506 13042 .02 .39 .47 .02 .43 .52 .02 .47 .57 111. 4 10760 12803 14415 14669 12020 .08 .85 1.56 .09 1.02 1.85 .10 1.14 2.10 111. 5 11561 13239 14395 14579 12555 .12 .74 1.48 .14 .85 1.69 .15 .92 1.84 111. 6 11515 12881 14315 14550 12820 .07 1.11 1.71 .07 1.24 1.92 .08 1.38 2.13 111. 7 11047 12253 14186 14505 12826 .05 1.70 1.92 .05 1.89 2.14 .06 2.19 2.47 111. 8 12599 13308 14806 15047 14144 .03 1.47 1.32 03 1.55 1.40 .03 1.73 1.56 III. 9 12420 13159 14611 14809 13882 .05 1.18 .77 .05 1.25 .82 .06 1.39 .91 111. 10 11547 12730 14230 14471 12956 .03 1.32 1.72 .03 1.46 1.90 .03 1.63 2.13 111. 11 12038 13050 14530 14765 13468 .03 1.08 1.51 .03 1.17 1.64 .03 1.31 1.82 111. 12 10971 12470 13924 14149 12237 .20 1.22 1.45 .23 1.39 1.64 .25 1.55 1.84 111. 13 11529 12845 14301 14552 12858 .02 1.17 19.91 .02 1.30 2.14 .02 1.45 2.38 Ark. Ark. 1R 1W 14149 14364 15469 15596 15343 .02 .29 .68 .02 .29 .69 .03 .31 .74 Ark. 2R 12718 13042 15206 15536 15081 .14 1.99 .92 .14 2.04 .95 .16 2.38 1.11 Ark. 2W Ark. 3R Ark. 3W 14123 14366 1544C 15573 15272 .02 .14 .66 .02 .14 .68 .02 .15 .73 Ark. 4R Ark. 4W 13688 13868 15525 15780 15534 .08 1.59 .71 .08 1.61 .72 .09 1.80 .80 Ind. 1 11785 13632 14683 14807 12645 .00 .07 .58 .00 .08 .67 .00 .09 .71 Ind. 2 12260 13252 14610 14270 13615 .05 1.72 1.84 .05 1.86 1.99 .06 2.05 2.19 Ind. 3 11057 12304 14510 14803 13025 .03 1.17 .67 .03 1.31 .74 .04 1.54 .87 Ind. 4 11238 12662 14449 14764 12836 .73 2.10 .74 .82 2.36 .84 .94 2.69 .96 Ind. 5 10936 12606 14567 14792 12535 .04 .43 .31 .04 .50 .36 .05 .58 .41 Ind. 6 11170 12096 14105 14395 13102 .27 1.52 1.10 .29 1.64 1.20 .34 1.91 1.40 Ind. 7 11839 13093 14365 14526 12984 .08 .55 .46 .09 .61 .51 .09 .67 .56 Iowa 1 9864 11467 14161 14615 12071 .21 3.29 .71 .24 3.83 .82 .30 4.72 1.02 Ky. 1 13998 14355 15073 15165 14754 .00 .14 .56 .00 .14 .58 .00 .15 .61 Ky. Kv. 2 13872 14370 15012 15104 . 14545 .01 .34 .61 .01 .36 .63 .01 .37 .66 3 12771 13801 14648 14826 13637 .06 1.03 1.75 .06 1.12 1.89 .07 1.18 2.01 KV. 4 12548 13925 14508 14612 13094 .10 .79 .76 .11 .88 .85 .12 .91 .88 Ky. 5 13465 13878 15004 15130 14642 .01 .17 .58 .01 .17 .60 .01 .19 .64 Mo. 1 11292 12986 14331 14606 12469 .24 2.21 1.46 .28 2.55 1.67 .31 2.81 1 84 Mo. 2 12187 1347S 14402 14639 13104 .32 1.70 2.37 .35 1.88 2.62 .38 2.01 2.79 Ohio 1 11739 12619 14292 14544 13377 .07 1.84 .78 .07 1.98 .84 .08 2.24 .95 W. V a. 1 13887 14098 15266 15490 15217 .01 1.11 1.77 .01 1.13 1.79 .01 1.22 1.94 W. V a. 2 14256 14425 15827 15974 15764 .00 .15 .56 .00 .15 .57 .00 .16 .63 W. V a. 3 14224 14514 15711 15833 15498 .00 .05 .45 .00 .05 .46 .00 .05 .50 W. V a. 4 14473 14768 15649 15749 15416 .00 .02 .76 .00 .02 .77 .00 .02 .82 Wyo. 1 9553 12076 12917 13003 10114 .01 .14 .37 .01 .18 .47 .01 .20 .50 44 DOMESTIC STOKER COMBUSTION Table 11, -Ash Fusion Temperatures, Gieseler Plasticity, Free-Swelling Index and Ash Analyses ASH FUSION TEMPERATURES GIESELER PLASTICITY o z i 3 Y- ASH ANALYSIS Sample No. bB c • o 1 1* k§ 6? &S &s &S fcS o 'oft. h Is ■IS? ££9 •pT3 '-3 o g III 6 CO O < 9 o M 3 d a O 6 111. 1 1942 2197 2357 362 414 429 460 11.9 4.0 111. 2 2026 2107 2149 NO PLA STIC ITY 3.0 32 73 18.28 28.47 .89 8.46 7.42 .35 111. 3 2182 2264 2311 400 416 455 1.5 3.0 49 '.4 22.75 8.91 1.04 8.17 5.94 .65 111. 4 2039 2105 2169 369 409 446 2.4 3.5 4S 38 15.62 12.89 .73 10.19 10.74 1.46 111. 5 1980 2105 2254 372 403 450 2.5 3.5 4X 20 25.33 17.92 1.23 1.74 1.12 .86 111. 6 2079 2156 2205 356 418 425 452 6.8 2.5 48 23 20.98 17.33 .58 4.55 4.44 -.02 111. 7 2032 2109 2140 NO PLA STIC ITY 3.5 44 25 19.04 19.01 .54 5.19 5.40 2.13 111. 8 2064 2265 2304 388 415 436 477 164 5.0 4S 14 24.12 21.01 .49 1.22 .87 1.16 111. 9 2055 2165 2304 405 445 468 3.8 5.0 111. 10 2070 2140 2181 379 423 447 3.2 4.0 111. 11 2090 2146 2195 380 408 434 466 145 5.0 111. 12 1993 2113 2195 NO PLA STIC ITY 1.0 111. 13 2009 2162 2220 333 401 420 457 54 3.0 Ark. 1R Ark. 1W 1938 2083 2245 454 485 515 3.9 8.5 Ark. 2R 2082 2284 2380 NO PLA STIC ITY 1 Ark. 2VV Ark. 3R Ark. 3W 1892 1971 1998 461 469 505 1.7 8.0 Ark. 4R Ark. 4W 1933 2021 2156 461 492 516 3.9 8.0 Ind. 1 2328 2552 2600+ NO PLA STIC ITY 4.5 48 76 33.84 5.40 .so 3.03 1.85 1 .68 Ind. 2 2016 2144 2256 321 389 426 463 2143 5.5 40 13 24.05 25.84 .44 3.03 3.07 1.20 Ind. 3 2060 2204 2380 383 415 430 461 9.0 5.0 51 19 23.32 13.66 .95 3.17 3.37 1.69 Ind. 4 1988 2062 2102 358 412 431 462 25.5 2.0 2X 43 16.56 35.86 .71 8.93 6.74 1.62 Ind. 5 2220 2456 2546 393 425 459 4.5 2.5 51 96 25.38 18.07 .96 .64 .31 .00 Ind. 6 2030 2126 2341 385 413 457 3.0 3.5 52 59 21.42 20 . 07 1.25 .52 .45 .76 Ind. 7 2102 2459 2532 380 413 458 3.7 3.5 56 IS 25.72 1 1 . 62 1.32 .55 .14 .14 Iowa 1 2001 2075 2105 388 412 449 2.1 1.0 Ky. 1 2103 2215 2351 397 421 444 472 620 3.5 43 34 26.25 12.63 2.01 4.80 5.47 3.47 Ky. 2 2228 2600+ 2600+ 433 456 462 494 22 4.5 Ky. 3 1996 2080 2158 360 401 427 462 155 3.5 41 05 22.41 26.69 .67 2.91 2.67 .82 Ky. 4 1952 2074 2248 390 427 457 2.3 5.0 35 97 21.68 35.85 91 1.78 .35 .72 Kv. 5 2375 2600+ 2600+ 403 425 447 475 74 5.5 Mo. 1 1949 2011 2072 365 405 454 3.2 2.0 38 34 16.78 40.11 .87 .75 .75 .81 Mo. 2 1965 2018 2064 366 422 428 456 6.2 2.5 31 .86 13.31 42.10 .88 5.14 5.19 -.14 Ohio 1 2039 2144 2238 406 422 455 0.8 2.0 W. Va. 1 2062 2197 2245 345 388 420 495 6000 6.5 39 .22 23.51 17.17 1.49 7.03 9.46 4.49 W. Va. 2 2600+ 2600+ 2600+ 447 468 490 519 23.0 8.0 W. Va. 3 2286 2338 2399 467 500 523 4.4 6.5 W. Va. 4 2388 2600+ 2600+ 394 416 444 499 1957 8 Wyo. 1 1981 2064 2103 NO PLA STIC ITY 31 .68 18.60 8.64 6.01 13.56 16.52 3.01 APPENDIX 45 Table 12. — Combustion Data HEAT OBTAINED UNI- FORMITY RESPONSIVENESS PICKUP OVERRUN Heat Ob- tained Wind- box Pres- Sample M B.T.U. per Lb. Min- M M B.T.U. First Hour C0 2 . No. M B.T.U. per Hour* Ave. Var. % imum Aver- age B.T.U. First 30 Min. Ratio M B.T.U. Ratio M B.T.U. Ratio % Ash sure In. of H 2 % 1 163 7.02 5.7 .86 14.9 .18 91.6 37.2 .23 72.8 .45 1.06 0.77 10.7 2 164 7.44 3.4 .92 28.4 .35 103.8 43.6 .27 84.1 .51 1.38 0.58 10.0 3 188 7.95 6.3 .81 19.5 .21 84.6 38.8 .21 82.5 .44 1.05 0.57 13.0 4 150 6.52 13.5 .68 17.6 .24 57.2 31.2 .21 71.3 .48 .69 0.56 9.2 5 165 7.37 4.9 .86 14.9 .18 70.8 34.7 .21 74.6 .45 1.05 0.50 10.3 6 154 6.90 8.9 .80 17.6 .23 83.4 33.0 .21 67.5 .44 .77 0.74 111 7 172 6.70 9.8 .77 18.2 .21 74.8 37.6 .22 74.9 .44 .54 0.98 12.7 8 186 8.00 11.9 .66 8.4 .09 31.4 40.1 .22 82.9 .45 .83 0.89 13.7 9 192 7.97 8.0 .80 19.8 .21 84.6 40.7 .21 89.2 .47 .85 0.86 13.4 10 179 7.16 11.8 .78 19.9 .22 83.6 38.8 .22 80.7 .45 .74 0.73 13.0 11 188 7.68 10.5 .77 13.2 .14 43.2 41.8 .22 80.3 .43 .82 0.77 13.8 12 166 6.83 7.3 .78 23.2 .28 109.5 41.6 .25 86.1 .52 .74 1.02 12.2 13 164 6.99 13.0 .63 17.6 _.22 -75.7 42.2 .26 77.0 .47 .77 0.92 11.5 Ark. 1R Fire could not b e main tained withou t man ual at tentio n Ark. 1W 251 9.57 4.6 .86 c c c 60.0 .24 120.5 .48 1.37 0.89 14.1 Ark. 2R Fire could not b e main tained withou t man ual at tentio n Ark. 2W Fire could not b e main tained withou t man ual at tentio n Ark. 3R 243 9.57 4.7 .88 47.6 .39 131.1 59.7 .25 113.2 .47 1.10 0.81 13.7 Ark. 3W 243 9.67 4.1 .90 32.5 .27 120.9 69.4 .29 116.4 .48 1.42 0.82 13.6 Ark. 4R 214 8.69 b 5.9 .83 27.1 .25 115.4 57.0 .26 111.6 .51 .48 1.07 12.3 Ark. 4W 236 9.41 5.3 .89 32.7 .28 112.9 54.8 .23 109.1 .46 .90 0.97 13.0 Ind. 1 150 6.87 4.6 .89 18.3 .24 78.3 32.9 .22 69.6 .46 1.11 0.60 9.8 lnd. 2 162 6.95 9.4 .76 11.3 .14 40.6 36.1 .22 62.4 .38 .81 0.81 10.1 Ind. 3 147 6.26 11.8 .72 9.3 .13 45.6 34.2 .23 62.8 .43 .46 1.00 9.6 Ind. 4 132 5.89 8.7 .83 9.3 .14 37.0 26.5 .20 52.5 .40 .54 0.74 Ind. 5 147 6.95 5.7 .84 16.9 .23 76.1 32.8 .22 72.8 .50 .59 0.93 10.5 Ind. 6 162 6.92 12.5 .69 26.2 .32 102.3 37.4 .23 84.7 .52 .52 1.00 Ind. 7 168 7.25 6.0 .86 28.2 .34 110.0 42.0 .25 91.0 .54 .91 0.81 9.7 Iowa 1 127 5.85 6.9 .85 16 .25 64.5 29.3 .23 61.7 .48 .36 0.76 9.9 Ky. 1 208 8.96 7.2 .79 15.2 .15 73.2 40.3 .19 89.5 .43 1.95 0.51 13.4 Ky. 2 206 8.92 6.7 .84 18.4 .18 96.7 49.7 .24 88.4 .43 2.18 0.70 11.5 Ky. 3 165 7.74 10.5 .71 12.1 .15 32.2 39.8 .24 63.2 .38 1.43 0.65 9.5 Ky. 4 174 8.07 6.3 .88 15.0 .17 85.0 37.2 .21 74.6 .43 2.24 0.50 11.0 Ky. 5 202 8.23 7.2 .80 13.8 .14 89.2 41.0 .20 92.9 .46 1.13 1.03 Mo. 1 154 6.95 12.1 .77 17.9 .23 50.8 37.0 .24 70.8 .46 .85 0.76 9.5 Mo. 2 147 7.25 8.0 .84 15.9 .22 57.6 31.0 .21 62.4 .42 1.25 0.65 8.6 Ohio 1 166 7.39 6.8 .79 14.2 .17 57.7 33.7 .20 72.3 .44 .68 0.72 13.2 W. V, i. 1 176 8.12 16.9 .54 c c c 40.1 .23 66.0 .37 1.08 1.06 10.7 W. V; i. 2 235 9.09 5.6 .84 21.6 .18 114.6 54.9 .23 112.8 .48 1.04 1.13 13.3 W. V; i. 3 238 9.50 5.2 .88 28.4 .24 115.7 52.0 .22 113.7 .48 1.27 0.74 13.2 W. V; i. 4 223 9.11 7.1 .83 13.9 .13 86.5 51.3 .23 98.5 .44 1.66 0.80 12.6 Wyo. 1 126 6.36 3.1 .93 22.1 .35 86.3 34.7 .28 61.7 .49 1.25 0.49 10.6 a With continuous stoker operation. b Only two rates of stoker operation. c Fire not maintained. 46 DOMESTIC STOKER COMBUSTION Ta 5LE 13. ■ — Clinker and Fly-Ash Data, and Coal -Burning Rates "linker Rating Specific Gr. of Clinker Po- rosity of Clink- er % Clink- er Shat- ter Index Clink- er Ash Ratio FLY ASH COAL BURNED, LB. PER HR. Sample No. Ap- parent True Lbs. % of Ash % of Coal 60 a 45 a 30 a 15 a 111. 1 3 3 3 3 4 3 2 2 3 3- 3 3 3- 3 2 3 2 3 4 3 3 3 3 2 3 2 4 + 4 2 3 2 2 4 3 3 2 4 3 3 1.33 1.91 1.25 2.13 1.25 1.29 1.52 1.37 1.20 1.32 1.23 1.41 1.24 2.09 1.63 2.07 0.92 1.56 1.25 1.82 1.32 1.21 .98 2.28 .98 1.36 1 61 2.03 1.05 1.84 2.94 1.62 2.06 1.18 1.63 1.16 1.85 2.79 3.16 2.72 2.78 2.78 2.78 2.88 2.83 2.79 2.83 2.80 2.88 2.68 2.62 2.93 2.70 3.37 2.79 2.78 2.66 3.34 2.78 2.87 2.83 3.14 2.65 3.23 3.49 3.03 2.99 2.68 2.83 2.74 3.04 52 40 54 23 55 53 47 52 57 53 56 51 54 65 47 54 46 53 57 63 32 65 53 43 35 60 43 16 47 31 56 42 58 39 50 69 49 47 50 56 51 68 55 52 52 49 48 65 69 49 58 45 54 44 70 88 72 95 93 58 66 70 58 47 76 70 80 70 0.53 0.57 0.65 0.73 0.61 0.61 0.65 0.35 0.64 0.66 0.69 0.68 0.65 0.60 0.47 0.38 0.22 0.62 0.59 0.63 0.53 0.55 0.68 0.66 0.59 0.44 0.32 39 0.36 0.52 0.44 0.33 0.53 26 0.51 0.47 0.42 0.52 1.5 1.0 1.0 1.5 1.5 1.5 1.5 2.0 2.0 1.5 2.0 2.5 2.0 4.0 2.5 5.0 5.5 1.0 2.5 2.0 2.5 2.0 2.5 2.5 3.0 1.5 2.5 1.5 1.5 3.0 2.5 2.5 2.0 2.5 2.5 3.5 2.0 1.0 1.9 1.6 1.2 1.4 1.8 1.5 1.0 1.7 1.8 1.2 1.8 2.0 1.8 4.6 2.5 7.3 5.1 1.5 2.4 1.3 2.1 1.5 1.5 2.5 1.8 3.3 5.0 2.4 3.9 3.4 2.6 4.3 1.6 2.9 2.1 4.0 2.8 2.1 .12 .08 .08 .12 .12 .13 .11 .15 .15 .11 .16 .19 .16 .29 .19 .38 .42 .09 .21 .16 .22 .17 .19 .20 .26 .12 .20 .13 .13 .23 .20 .23 .17 .22 .18 .15 .16 .09 22.4 22.1 23.3 22.6 22.3 21.6 24.7 22.8 23.5 24.9 23.6 23.6 22.9 26.5 25.2 24.8 25.1 24.9 21.4 22.4 23.0 20.3 21.2 23.6 23.6 21.7 22.7 23.1 20.4 20.9 23.7 21.9 19.6 21.7 21.1 25.8 24.6 23.8 19.9 17.7 16.6 17.1 17.0 16.9 16.5 18.6 16.4 17.8 18.2 17.5 18.0 18.1 19.2 18.6 18.4 18.4 16.4 16.6 17.4 15.7 16.3 18.0 17.8 16.8 17.0 17.0 15.9 15.6 18.0 17.2 14.8 16.5 16.7 19.4 18.1 17.9 15.1 11.5 11.0 11.3 11.5 11.3 11.2 12.3 12.2 12.1 12.3 11.4 12.2 12.3 12.8 12.7 12.4 12.4 11.0 11.3 11.7 10.6 10.7 12.1 12.0 10.9 11.3 11.5 10:5 10.5 11.5 11.6 10.0 11.0 11.0 13.0 11.7 11.9 10.2 5.6 111. 2 5.6 111. 3 111. 4 111. 5 111. 6 5.8 5.9 5.6 5.6 111. 7 6.5 111. 8 6.0 111. 9 6.0 111. 10 6.1 111. 11 5.8 111. 12 6.2 111. 13 6.1 Ark. 1R . Ark. 1W Ark. 2R 6.3 Ark. 2W Ark. 3R 6.3 Ark. 3W 6.2 Ark. 4R. . 6.4 Ark. 4\V Ind. 1 6.0 5.5 Ind. 2 5.5 Ind. 3 5.8 Ind. 4 5.2 Ind. 5 5.3 Ind. 6 6.1 Ind. 7 6.0 Iowa 1 5.5 Ky. 1 Ky. 2 Ky. 3 Ky. 4 Kv. 5 Mo. 1 Mo. 2 Ohio 1 W. Va. 1 W. Va. 2 W. Va. 3 W. Va. 4 Wyo. 1 5.6 5.7 5.2 5.1 6.0 5.7 4.9 5.5 5.3 6.4 6.1 5.9 5.1 a Minutes of stoker operation per hour. Illinois State Geological Survey Report of Investigations No. 151 1951