TS is S TNTRODTTCTTON. The author of this thesis has made a study of steam power plants and heating systems for several years with a view of determining the best use that oan be made of exhaust steam when the power plant and heating system can be obmbined. It is the writer 1 s conclusion based on the study of conditions in a number of localities, particular- ly in the mining districts of the West that the average steam plant is not operated under anything like economical conditions. The reasons for this condition may be attributed to the average operating engineer's lack of knowledge of his work, indifference on the part of the plant owner, poor advice from the consulting engineer, uncertainty as to the life of the plant, (particularly true in mining operations) and not infrequently to the conceit and stubbornness of the engineer in charge who is often averse to accepting new ideas and methods from an outside party. Little of value has been written on the subject of combined heating and power plants. This is probably due to the fact that there are so many variable factors which tend to make each problem a distinct and separate prop- osition as indeed every engineering problem should be. It is hoped that the following discussion will be of some value to those interested in this subject and that it may encourage further effort along the same line of work which will raise the standard of engineering practice. Because of the many factors which govern all heat distribution it was thought best to give a general dis- cussion of the subject preliminary to the main body of the thesis. However many phases of the subjeot have been omitted because of the desire to confine the disoussion to the principal topic. 2–~ 3. © : 6. 7. 8, 9. 10. ll. 12. l3. CONTENTS. . Introduction. References. . Buildings and Building Materials. Atmospherio Gonditions. Types of Plants. Types of Boilers and Prime Movers. Systems of Heat Distribution. Power Hoad and its Relation to Heat Load. The Walue of Exhaust Steam. The Essential Elements of a Wacuum Heating System. The Cost of Power in Isolated Plants. The Measurement of steam. Results of Tests made at the Colorado School of Mines Heating and Power Plant. 14. Conclusiong. To the Honorable Board of Regents and the Faculty of the Engineering Department of the University of Michigan, I respectfully submit the following thesis in compliance with the requirements for the Degree of Mechanical Engineer. A Treatise on Wacuum Heating with Exhaust Steam, with Considerations of Power Cost;3. References. l. Books on Heating and Wentilation. Elements of Heating and Ventilation, by A. M. Greene. Central Station Heating, by B.T. Gifford. Heating and Wentilating Buildings, by R. C. Carpenter. Handbook for Heating and Ventilating Engineers, by J. D. Hoffman. Mechanics of Heating and Ventilating, by Konrad Meier. Notes on Heating and Ventilation, by John R. Allen. Heating and Wentilating Plants, by C. L. Hubbard. Heating and ventilation, by Baldwin. 2. Articles on Central Station Heating with Exhaust Steam. Central Station Heating, by A. D. Spencer; Power, July 5, 1910. Electrical Supply and Exhaust Steam Heating, by F. H. Davies; Electrical Review, London; Sept. 8, 1911. Exhaust Steam Heating, by E. Darrow; Electrical World, April 6, 1911. Pipe Line Design for Central Station Heating, by B. T. Gifford; H. & W. Magazine, Feb. 1911. Central Heating and flower Plant of Mogill University, by Richard J. Durley; Inst. C. E. No. 3985. Combined Central Heating and Electrical Plants, by E. D. Dreyfus; Power, August 20, 1912. 7. Heating and Wentilating Large Buildings, by C. L. Hubbard; Practical Engineer, August 15, 1913. Cost of Exhaust Steam Heating, by I.N. Evans; Power, November 26, 1912. Central station Heating, by J. Grant DeRemer; Engineering Magazine, February and March, 1914. Customers Steam Heating, by H. R. Wetherell, H. & W. Mag. June , 1914. Buildings and Building Materials. The materials used in the construction of large buildings are principally brick, stone, concrete, and marble. Probably the majority of public buildings are constructed of brick. The thickness of wall depends upon the size, number of stories, and the type of structure. The foregoing applies to public buildings, factories, shops, department, stores, and office buildings which are large enough to warrant individual power and heating plants. Since the materials used have widely different factors of heat conduction and radiation it is at once apparent that this fact together with thickness of wall, number of stories, windows, eto..will to a great extent govern the size and operating costs of the plant. The chart on page 9 was plotted from tables taken from Hubbard's "Heating and Ventilating Plants", and is intended to show more clearly than otherwise the heat loss through different materials. Authorities differ considerably in the factors for the same materials. This is due no doubt to the fact that the conditions under which experiments are conducted by different individ- uals can never be exactly the same ; and exact values are determined with difficulty. To illustrate the use of the chart as applied to a problem in heating let us consider a room 16' x 20' x 10' ºsloue low 6uſ plung u 6 nouum egon ſoºſ … y ººzvezº， º /º/ º /ºo/zzzz ~~ ~~~~ ！， -º， -ae， ſae，.…….，|-•••ſº：•o ，ſºº 4ººº– 2，· ºmaeº w wieli »ad|| №= ~ ----ſae）. | ----·£， |-№---- |_）+-~~~~|_）==º2í， ），~T）№|- -· | laeſº，==№ſ：21// | ==№ſ：4，1：1，1：1）|- |_）~~|_）~/|- ſº|_）~|_！-^ ^ __--#####~T_1）-f（1），T__£>.<_^º /l._ |_）~/Laera.|_）~|-/|- _）~----|- |-77，ſaeſ））f_laſ|：_，_：12，|×//| =（[“ſºfºſſ–№ſſºſ，H—ſoºſ： |_！）·ſãºL_，ſººr| _ļa， ſººſ №ſſºſ！ºſºp_^_^11：12，-//-»ae 171ſººſſae51，4_^Lºr|×Zº ºſáſáſ,ſºſ2， ºſ_：：i！|×/ſv. -， ！---- 2^^×432：22， ſººDº，º S. ºcº，|（7 ±ſãº07^ Źź¿? №ſſºſſaeſ，_^_]'，|×1}，·N arº".| -7 A，3 ſº| 21// |· 0?^-110- ， ，{aºíſ_^！| /|ק Prae37ſ㺱|||- _：1！ 1|×·||-~ −2/242/• //?soaſ， 7 Þºſº'º|×1Z|×·n. ºvº soºr? ：o） …ayoºy vozzº zvog！ș62ºſéZ ！//_ （ ſíºſm！ № }466 • ſaeae§ á?’T№ _^11.^Affſãº47?Z z zvºz –， aºſ o aer ºg sae/ºsa）_^ſº4%|-%%|Áº- asº-~~~~ zvozzoa） szvo： ）， ooa^ _^oy|- i I z zvº2 -vºa^ oº º sae//ºsº），62.| ºszºº-vºz， zvºaei！?）， zvo? --//c2， …vœ/º|- -rºo /ſº ºdſzyn z，|-|× awa， wo ºvº „º saevae aero/o：/ …，-| ºrº， º ae → *， | _ |-- l(). exposed on two sides, the short side on the south and the longer side on the west. The short side has a single win- dow 50" x 52" and the long side has two windows of the same size. The walls are 8" brick of fair construction. Com- pute the heat loss per hour for a temperature of 70° in- side when the mercury stands at zero outside. - l. West side . From the chart the transmission factor for a temper- ature difference of 709through an 8" brick wall is 28 B.T. U; s per sq. ft. per hour. For a single windowſ the factor is 84 B.T. U's per sq. ft. per hour. The exposure factor for the west side is l . 2 . Heat loss for wall—-l'78x38xl. 2 –––– 5986 B. T. U : 3 per hr. He at loss for windows-22 x 84 x 1.2-2220 º * . Total loss --- 82OO h tº º The same method of calculation for the south side gives a loss of 5095 B. T. U is per hour. The total loss per hour will be 8200+5095 x 1.2 = 16350 B.T. U. 's per hour. ( The construction factor is l.2) Note :-The above calculations do not include the wind factor. This will be discussed later. ll. Atmospheric Conditions. Power load may consist of shaft driving, electric generators, distribution to eleotrio motors, air com— pressors, blowers, lighting, or combinations of these loads. Aside from the lighting load most of the others will average about the same from month to month in any given plant, and in many oases the lighting load will not vary to any great extent. This condition is likely to be true in a large department store. The requirements for heat however, vary to some extent from year to year in a given locality, and are widely different in different latitudes, longitudes and altitudes. For example, the average temper- ature for Denver, Colorado, for the year 1913 was 489, while for St. Paul, Minnesota, the average temperature was 44°. Yet the average temperatures for the same two cities during the heating season was 37.8°and 30.6° respectively. Temperature more than any other factor governs the re- lation between heat and power loads. Sunshine, humidity, and particularly wind velocity also enter into the problem of heating requirements. The average wind velocity for Denver during the year 1913 was 7.9 miles per hour and during the heating the heat- ing season was 8.1 miles per hour. Mr. W. H. "hittier gives the following: — "From 40 to 15 degrees plus, one mile of wind movement per hour is equal to one degree drop in temperature. From 15 degrees plus to 20 degrees minus 12. one mile of wind movement per hour is equal to l, 15 degrees drop in temperature. This applies to ordinary buildings without protected windows. " The curves on page 13 are plotted form data furnish- ed by the U. S. Weather Bureau Office from the cities noted. The idea is not original with the writer but is carried out here to show in graphic form the influence of climatie con ditions on heating requirements. Six cities were selected in different parts of the United States. Curves obtained in this manner are alone worthy of considerable study. The ordinates represent the average monthly temperature for a period of about 40 years. This is about the time which has elapsed since the bureaus were established. The absoissae represent months; and the mean temperature was plotted on the middle ordinate of the month. Some interesting features may be noted. For example it we consider an average temper- ature below 559to be the heating season then San Francisco has a heating season of nearly 5% months. For no month is the mean temperature lower than 48°. Kansas City has a heating season of less than six months but a low mean of 38° while St. Paul has a low mean of 130 and a heating season of about 7 months. The heating requirements are based on both the length of season and the range of temperature and on this basis the relative heating requirements of the cities namáá will be approximately as follows:-- 13. · º - - · |----|-， ,|- . . . . . ， ， ， ， ， s - - - - |×|- ſae ， ！-----：） ----！ ſaeae|-|||TOE |-| 1 | ae*|- | |·|×|（） |-|- . . . ---- |·- |-| |（）| |：： -- |- |-·|- |-（） _ |-||--|-|- -|||||- |-||| |- | |·|- |-|||-|-| ſae | | | | |， !ſae| - |||-|| | _ ||-| ，} | 1 |-| 1 |×|× |-~ |||-\，|× |* |- |-|-ſº|||-~ ！№.| ， ، ، ،№è |-|-||×|-|- ~ |||ſº||（） | | | | | | | ||， ， ，\ | | | | | } | ſ（T）\ | | |} . . .|-|||- |-||-\，|×|-|×|№|-} -| |----- . .|- |-| // \， \！\， ,|| 3 |ſ 1， \ | \ | | | * |- | |-|-| ºz º. ºº ºr ºº ººz 14. New Orleans–––. . . . . . .-1. ^ San Francisco------- - 4.3 Kansas City---------- 7.8 New York -------------- 8, 8 Denver -------------- 9, 3 St. Paul-------------- 12.9 The above figures were obtained by integrating the areas included by the curve, the 70°line and vertical lines from the points where the curve crosses the 55° line. These figures do not take account of the wond ve— locity, humidity, or percentage of Surishine. All of these are governing factors in heat requirements. 15. The Type of Plant. The purpose for which the building was designed, whether for store, office building or shop will determine largely the type of structure, the number of windows, and in general the amount of artificial lighting which is in many instances the greater portion of the power load. Large department stores are lighted for the greater part of the working day. Certain types of factories with labor working eight hours per day have practically no lighting load. Stores in small cities rarely have individual power plants. In educational institutions the lighting and power loads are as a general thing very irregular. All these factors as well as the number of buildings to be heated by one plant, their exposure and relative location will govern the type of installation. It is common prac- tice to have central plants for both heat and power dis- tribution even though the distance of transmission is considerable. In well designed transmission systems the thermal loss is relatively small. 16. Types of Boilers. The use of steam of such pressures as are commonly employed in power plants, viz. from 60+ gage and upwards, eliminates the installation of boilers of low pressure types such as house heating boilers in combined heating and power plants. Occasionally a low pressure boiler is used in conjunction with high pressure boilers when the heating load is relatively large. The steam from the low pressure boilers will pass directly to the heating main into which the exhaust steam from the power units also passes. Of high pressure boilers there are two com— mon types, fire tube and water tube boilers. Each type has certain advantageous features. Water tube boilers are higher in first cost but as a rule are more efficient than fire tube boilers. Aside from the lower first cost there is little in favor of the fire tube types; and the more recent installations particularly plants of considere able capacity are mostly water tube boilers. On page 17 is shown a design of a boiler of the well known return tubular vtype and at the bottom of the same page is a cross section of the familiar Babcock and Wilcox water tube boiler. The common types of water tube boilers are the Heine, Babcook & Wilcox, Wickes, Cahall, Rust, Obrien, and Parker. == H _ –––. — I H == == == ======= == = == - == == === HIGH PRESSURE HORIZONTALTUBULAR BOILER FULL FLUSH FRONT SUSPENDED SETTING |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||| i |||||||||||||||||||||||| - |||||||||||||||||| |||||||||||||||| | ||||||||||||||||||||||||||| | - | | ||||||||||||||||||| | | ! 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Types of Prime Movers. Two important factors enter into the selection of prime movers; (1) the steam pressure to be carried and (2) the water consumption per horse-power-hour. These two factors are more or less interdependent and upon them depends to some extent the type of boiler to be se— lected. High and low speed engines, simple or compound, condensing or non-condensing, and steam turbines---all these must be taken into consideration. In combined heat- ing and power plants there is usually little to be gained by the use of high pressures or by an expremely low water rate. This then practically limits the selection to the simple high speed type. However there are conditions which would warrant the use of a compound engine and there are instances where the balance of heat and power loads might warrant taking steam from the receiver between the two cylinders. In case the steam required for heating is less than the amount delivered by a simple engine then one of lower water ºrate should be employed. The use of exhaust steam excludes the use of a Condenser during the heating season. Yet during the summer months it will usually be found economical to run condensing even though the condensing equipment is idle during the rest of the year. The saving in any instance can be reddily determined by comparing the fixed charges with the decrease in power cost förm the lower water l9. rate. At the Colorado School of Mines a gas producer plant has been installed. Thää is intended to provide power for the Experimental Plant at any time during the year and to the oampus buildings during the summer. There is no condenser for the steam units in the power plant, and because of the very low coal consumption of the gas plant it is found economical to leave the steam units idle during the summer. In the use of steam turbines considerations of back pressure are of the greatest importance. Turbines are peculiarly adapted to condensing operation and any increase in back pressure caused by forcing the ex- haust steam into a heating main immediately decreases the economy of the turbine. Yet because of their com— pactness and adaptability to direct driven generators they are often used, particularly in places where floor space is of prime importance. The high speed simple or compound direct driven generator sets are more commonly used than the turbine sets . 2O. systems of Heat Distribution. There are two general systems of heat distribution where exhaust steam is used; these are commonlyy known as the one-pipe and the two-pipe systems. In the one-pipe system steam is transmitted to the radiators by the same pipe line which returns the condensation. Air is re- moved from the radiators by a vacuum air line attached to the opposite end of the radiator from the intake. An air escape valve connects the radiator and this air pipe line. This valve is designed to open to permit air to escape and to close when steam somes in contact with it. This is commonly known as the Paul Return Air Line System. The two pipe system is coming rapidly into favor. This system has a steam pipe leading to the radiator and a separate pipe fºrm the opposite end of the radiator back to the vacuum pump which is usually located in the boiler room. To prevent the escape of steam into the vacuum line the radiator is fitted with a trap at the outlet which permits the passage of air and water and closes when steam comes in contact with it. This system is commonjºy called the Webster System and is the one considered in this the sis. A successful vacuum heating system should satisfy the following requirements; — l. The use ºf exhaust steam without increasing the back pressure on the engine. 21. 2. A rapid removal of air and a positive circu- lation of stem through the system. 3. Complete utilization of the heat value of the steam in the radiators. 4. No escape of steam into the vacuum line. 5. No leakage, air binding or noise. 6. Return of condensation to the boiler room. Steam may be transmitted at high or at low pressures the size of pipe depending of course upon the pressure at which the steam is transmitted as well as the total quantity of steam flowing per unit of time. When there are a number of buildings to be heated from a central plant steam may be transmitted at high pressures through small mains and reduced in pressure at each building. This method has the advantage of smaller boiler re- quirements and smaller pipe losses but has the dis-advan- tage of reruiring separate control at each building. It is impractical to use exhaust steam from engines in these mains so in exhaust heating systems and in instances where high pressure steam from the boilers must be supplied to make up the deficiency in exhaust steam it is usually advantageous to place reducing valves at the central plant. There are instances when the exhaust steam may be transmitted to one building of a group to advantage while the other buildings take high pressure steam from the boiless. The most satisfactory method of carrying pipe lines between buildings is by the use of underground tunnels. These pipes are not easily disturbed, are easily accessible and there is less loss of heat by radiation than if carried above ground. Moreover, a tunnel furnishes a place for other piping or wiring. The first cost of constructing a tunnel is considerable but the saving in labor for repairs or additions to the system usually warrants the extra first cost. On page 2:3 is shown a cross section of a tunnel at the Colorado School of Mines. This tunnel is well oonstructed and is satisfactory in every respect. A string of incandescent lamps controlled by a switch a each end of the tunnel furnishes the necessary light. piping is sometimes carried along the side of the tunnel rather than above. This has the advantage of additional head room. Zºzzº Teº|| 4%ìſ！!！ (($|#\|| || ~） \\$| Ķ| N % 24, Power. Load and its Relation to Heat Load. A proper balance between the power and heat loads must be maintained in order to reduce the cost of power to a minimum, and a ratio between the two may be found which will determine the proper use of exhaust steam, and whether it will be advisable to heat, with live or ex- haust steam. In this connection the steam consumption of engines, pumps, and othèr steam using apparatus should be taken into account. Gebhardt in his Steam Power Plantá Engineering gives the following water rates of different tunits: - Type of Engine Steam Consumption —-lbs per I. H. P. /hr. - Non-condensing condensing Simple High Speed 30- 35 22–-26 Simple four valve 27—-3O 20–-24. Compound High Speed 22––26 18––22. Compound Four Walve l8––22 13–-l8. Triple Expansion ------ 10%–13. Mr. C. L. Hubbard gives the following water rate for other units : –– Boiler feed pumps--------------------------- 125. Elevator pump-compound---------------------- 65. Elevator pump-triple expansion-----__________ 40. A 25. Air compressors generally will require 15% to 20% more steam per I. H. P. /hr. than steam engines of the same number of oylinders and operating under the same oonditions. Tests made by the writer on a two-stage compressor with a simple steam cylinder show a water rate of 40–45 lbs per I. H. P. per hour running non-condensing. The steam consumption of stage turbines is about the same as for compound engines.with a decrease when running condensing. Turbines are particularly adapted to condensing operation though they may be operated non- condensing. The steam consumption of turbines as compared with reciprocating engines is relatively lower when running condensing. A point in favor of usáng exhaust steam from turbines is the absence of oil or grease in the Steam. If exhaust steam is to be used for heating pur- poses manifestly it is a simple matter to alter materially the ratio of the steam consumption required for power to that required for heating. For example a plant in- dicates 500 h.p. with compound Corliss Engines running at full load. The steam consumption per hour would be 20 x 500 -10000 lbs. With two or more simple high speed engines the steam consumption would be about 30 x 500 Flå006 lbs. per hour. This is 50% more than in the per preceding case. If the heating system required about 15000 lbs. of steam per hour during the usual heating 26. season the proper installation would be simple high speed engines. or single stage turbines with condensing equipment for use during the summer months. If, however, the balance of heat and power was found to be best with 10000 lbs of steam per hour then compound engines or stage turbines would likely be the proper installation. 27, Heat Value of Exhaust, Steam. t this point let us consider the heat loss in steam as it passes through the cylinder of the engine, A card taken from a corliss engine operating non-condensing will be similar to the following:-- C7 4) | | | - | § -7ſ | z * ! º !. __L. J. • Y Ae/* 5.7-2/fe Steam enters at pressure P and a volume, repre- | | | | | | | | | | l I I t sented by the area abjk. In expanding along the line b c useful work is performed, the pressure is lowered to Pº represented by the line c e or the pressure at release, and exhaust takes place along the line d f. The back pressure is ordinarily from one to three lbs. gage. Consider a pound of steam at pressure P -100 #/ sq.in. gage. It contains approximately ll&9 b. t.u 's above Water at 32° Fah. If the same pound of steam were exhausted at atmospheric pressure, after expanding along the line b o it would still contain ll 50 b. t.u's above water at 329 Fah. It would retain then over 96% of its original heat. This assumption, however, is not correot. While but a small part of the original heat is converted into useful work directly, not all of this original amount enters the exhaust. Radiation and initial condensation take more of the heat; than is delivered as useful work. 28. Hubbard states that " We may assume in average practice that 80% of the steam supplied to an engine is diseharged in the form of steam at va lower pressure. The remaining 20% is partly converted into work and partly lost through cylinder condensation. One of the first uses to be made of exhaust steam in any plant is to heat the feed water. Tm the average power plant, the initial temperature of water supply may be taken at 60°Fah. Assuming that an open heater is used the temperature of this water may be raised to about 210° if there is ample steam. Each pound of water will therefore require about 210–60= 150 b. t.u. s. Each pound of exhaust steam will contain 20% moisture at 2129 and 80% steam which has a latent heat of 970 b. t.u. s. Each pound of live steam will have available therefore at exhaustO.80 x 970 - 776 b. t.u 's for heating purposes. If the 20% oondensation is returned to the boilers, then l6% of the 776 b. t.u. s would be sufficient to heat the 65% of cold water to 210°Fah. leaving 0.85 x 776 =670 b. t.u. 's for other heating purposes. However in well designed heating systems practically all of the water of Condensation from the radiators is returned to the heater at va temperature considerably higher than 60° Fah. So the amount of steam required for the feed water. heating is still further reduced. In many vacuum systems a spatay of cold water is injected into the return line 29. from the heating system at a point near the vacuum pump in order to maintain the vacuum. This water also supplies the makeup necessary for the plant. The final temperature of the water varies from 90° to 125°Fah. according to the system and the operating conditions or degree of vacuum. It is readily seen that considerable loss may occur by the water injection. This subject will be taken up in detail later. Common practice agrees that of the original amount of heat in live steam entering a steam cylinder, about 20% will be lost and 80% will be available for heating purposes. These values will be used in this thesis in calculations of power costs. 30. The Essential Elements of an Exhaust Heating System. In any exhaust steam heating there are several elements which may be called essential. These are enumerated as follows: l. A source of steam supply which may be direct from the boilers or from the exhaust of engines, turbines, pumps, or other steam operated machinery. 2. A system of piping to distribute the steam from the source of supply to the points of radiation. 3. A radiating system which may consist of common radiators or wrought iron piping of proper surface to radiate the required number of heat units per hour for the given conditions. 4. A system of piping to carry the water of con- densation back to the boiler room or to whatever point the discharge may be . 5. An apparatus usually a vacuum pump for pro- ducing a vacuum on the return line. This removes the air and water of condensation and has the effect of creating a greater difference in pressure between the outgoing and the return lines. This insures a positive circulation. 6. Valves on the radiators for controlling the air and condensation, allowing these to pass freely without the escape of steam. These are usually some form of 31. float or thermostatio trap. There are a number of different commercial traps on the market. The foregoing may be considered the ipportant elements of the heating system but there are several other elements of almost equal importance which are quite necessary to the successful operation of an ex- haust heating system. 1. A receiver for collecting and storing the re- turne from the heating system when the water is to be used for boiler feed. 3. An oil separator to remove oil, dirt,and Scale from the exhaust steam in order to permit the use of the condensation for boiler feed. 3. A make-up water regulator to control the water supply to the boilers. 4. A reducing valve to be used when live steam is needed to supplement the supply of exhaust steam. The diagrammatic outline on Page 32 shows a typical layout of an exhaust heating system and is self-explanatory. - - In all of the above items the only ones that are peculiar to vacuum systems are the radiator trap and the vacuum producing apparatus on the return line. Figure 7, on Page 33 shows the application of a trap to a radiator. Z A27//e/- 23, Z2/4/~zzzzzz- 2 A.2//e/- Aéez /7/zz72. /-, 5è22, 2722- 3, Aºazz/-//zz72/~ /7207?/ºr 23. Afzzzzzze 4. 4.2c/r/ºzeszzze /ø/ºre 26. Cze/Zeazzº Jº AZzzºz Jea/ /z /7222/c222 /ø/re. 6 &o.242es. /5, /7272/2/2/- - 2. Aºr/#22.57 Z//ze. /2 (2/2/22/ /27//re. ** . & & Szeozzz 7722. 22 /7.2/2/2/- ZZzza 2 /zzczzzzzz /*2/772 2/. A2czzzzzzz /7°zoz/~/7 /2. /7&gzz/2722. 22, & 2/7/22/2/- $2,904: //, //2/, /*ess2/re Azzºz. 23 //&azzzzz z/2//z /.2 : ** • A-22 O || || irº, To "Tº º º º A/22/~ Z//ze | 7 AA’zºzza,47/o/V or Æ4/7/472/7 777/7/2 Zºo /724/7/277 (2/P & of 96 34. The radiator trap is the distinguishing feature of the vacuum system and is the most important for upon it depends to a large extent the successful operation of the heating system. As previously mentioned a great many vacuum systems require the use of cold injection water near the vacuum pump to condense the vapor which passes the radiator trap. The writer has had occasion to test a number of radiator traps of different types and has found a great difference in the results. This is the more notable because many manufacturess claim exactly the same merit for their traps. The results of one of these tests is shown on Page32. 35. The Cost of Power in Isolated Plants. consider a small plant of 100 kilowatt average load operating 365 days of lo hours each per year, or a total of 3650 hours per year. The total output will be 365000 kilowatt hours per year. Install one 100 kilowatt and one 50 kilowatt engine generator sets. The exhaust steam is to be used in the heating system. A simple engine operating non-condensing will have a steam con- sumption of 35 lbs. ºf per T.H. P. per hour of about 50 lbs. per kilowatt hour, when running under normal conditions and good load. For fluctuating and small loads the above figure would be increased to about 60 lbs. per kilowatt hour. Assuming a boiler pressure of 100+/sq.in.gage, and a feed water temperature of 160°Fah., and a boiler efficiency of 65%. a pound of coal containing 12000 12OOO X , 65 12OOO x . 65 beit ali.' s Will evaporate ---—------ or ----------- H - (t–32) ll 88.8 - 128 = 7.4 pounds of water under actual conditions. If we assume that 20% of the heat of live steam is lost between boiler and heating system and that coal costs *3. oo per ton at the plant, then the cost of poałr for power during a period of six months when all of the exhaust steam were used for heating would be 3650" 60 3OO LOO X x -- x . 20 x --- = #444. oo 2 '7. 4 2OOO During the remainder of the year with no heating the 36. cost of coal for power will be 5 x*444. oo =#222O. oo Fixed charges. Two engine generator sets of this type will Cog tº about #55. oo a kilowatt rating, giving a total cost of •eºso.o. . Allowing 15% for interest, depreciation, insurance etc. gives an annual charge of . 15 x*8250. = #1240.o.o. ººl.9% The additional labor caused by the installation of power units over that required for the boiler plant alone in the case of a heating plant with no power might be considerable or it might amount to practically nothing. If we allow $1000. oo per year for one engineers wages plus the cost of oil, waste, and packing then we have - Fixed charges----------------ºl.240. oo Coal ------------------------ 2664. oo Labor, migo allaneous ------- 1000. oo total--------- 4904.00 The cost per kilowatt hour will be ($4904.xloo) + (3650x100) tº 1.34%. Note: No allowance has been made for the additional boiler horsepower that would be required for the power output. This would not amount to a great deal and could readily be calculated and added to the above total. It should be mentioned however that the type of boiler would be changed and ºris a low pressure boiker would likely be installed for the heating system alone. This 37. would be somewhat larger than the high pressure boiler for the same output. It should be mentioned also that; if we were making comparisons with a heating plant alone that no fireman would be needed during the period of no heating. For a heating period of 7 months the above items calculated in the same way would be as follows:-- coal (7 months of heat)---------4518. oo 5 months off no heat----- #1850. oo Fixed charge 3------------------ 1240. oo Labor -------------------------- 1COO ... O O Total ------ Agos.oo Cost per kilowatt hour----1.26%. On the above assumptions the following table has been obtained and the chart on page 41 has been plotted from the table . Cost of power per kilowatt hour Months of Price of coal in dollars. exhaust - Stebºrn l 2 3 4 5 2 1.02 1.37 1.67 2.07 2.43 3 .99 1.32 l. 59 l , 96 3, 29 4 .95 l. 26 l. 51 l . 86 2.15 5 , 93 l . 21 1. 43 l .75 2. O2 6 .9l l. lf l. 34 l. 64 l. 88 7. . 88 l , 10 l. 26 l. 53 l. 75 8 .86 l.05 l. 18 l. 43 l. 61 38. It must be kept in mind that no heating season should be assumed as ideal. In the preceding calculations it is assumed that the period of the year requiring heat starts and ends at a definite time; and that all of the steam is required for heating during all of the heating season which is not true. At the beginning and at the end of the heating season there is always a period when only part of the exhaust steam will be required for heating. It should also be mentioned in this connection that the costs could be reduced considerably during the non-heating period by operating condensing. This would reduce the coal oonsumption by about 20% for that time. No account has been taken of the water cost. This is often an important item and should not be overlooked. Water ordinarily costs from 104 to 15% a thousand gallong. 39, Influence of Labor on Power Costs. In any plant there are three large items of ex- pense. These are fuel cost, fixed charges, and labor. When the power load is very light as oompared with the heating load or when the power load is very light during the summer when there are no heating require- ments the labor charge is likely to be most significant. Institutions which have a small power load will usually find it an economical propositiºn to take advantage of any ordinary rate of power cost which may be ob- tained from the local power company. In the case of isolated plants, however, such an arrangment cannot be made; but it is often possible to distribute the labor costs to other accounts. For example, in a small plant a considerable portion of the attendant 's time may be spent on repairs. In a heating plant the bulk of repair work must be done during the summer months and this item of expense should not be charged against the costs of power when the latter is a by-product. To show the effect of the labor charge on the cost per kilowatt–hour let is again consider a 100 kilowatt plant operating 10 hours per day at 50% load factor with labor at #100.oo per month of 30 days. The labor cost per kw-hr r. would be 335+ (100 x 10 x. 5) F 0.67%. If the load factor were 100% the above cost item would be reduced one-half. This cost item would 40. reduce as the limit of a man's capacity were approached. This would be dependent upon the design and arrangment of the plant and the number of automatic devices. Figure 9 on Page 42 is plotted from a series of cal- culations similar to the preceding for both the labor and fixed charge items. Figure 10 shows a series of curves where the cost of coal is plotted against the coal cost per kilowatt–hour for different periods of exhaust; Steam heating. Fuel cost is of course almost directly proportional to the load factor while both the labor cost and fixed charge increase very rapidly when the load factor decreases below 30%. ∞ √° √≠ √∞ √° √∞№oººooºº oº ^ = ez， + c ∞ √ ！ ± 0， ..." », og aeon - o cc ：： ： ： ： : ： ： ： ： ： ： 7 -- º + √≠ √∞ √ √≠√∞ vae povolº， ， ， ， ， ， ，{i ：= ſ] ： （ ）AFZ2 /^^-^ 2， 4:/2% Z/2Z 2Ž The Measurement of Steam. It is usually very difficult to measure the steam distribution to diffenent parts of a power plant. The steam consumption of engines and auxilliaries may be readily determined by condensing tests but this cannot always be done under actual operating conditions par- ticularly in plants where the exhaust steam is used for heating purposes. Unless the plant is a central station plant selling heat to customers there is ordinarily no ready means for recording the steam flow to different parts of the plant. Practice differs in methods of measuring and of distributing the cost of steam. Condensation from rad- iators is best measured by condensation meters which automatically record the weight of water passing the radiators. This is a fairly accurate method of determin- ing the flow of steam. This method is not practicable in exhaust steam heating systems. The condensate which is handled by the vacuum pump can be easily measured provided no cooling water is injected at that point. When the distribution of operating costs is but a matter of transferal from one department to another of the same oompany as is often the case in isolated plants it is common practice to base the coat of steam on the manufacturer's rating of the power unit for the average load. This practice is followed by the Stearns Lighting 45. and Power Company of Ludington, Michigan. This company purchases its steam from the Stearns Salt & Lumber Com— pany on the engine rating basis. Part of the exhaust steam is returned to the salt evaporators but this is not credited to the Power Company. Manifestly this is not a correct distribution of costs. There are several forms of steam flow meters on the market which are designed to measure the flow of live steam. Opinions differ as to the merit of these devices. Recent tests seem to indicate that they may be adjusted to give fairly acourate results. A very complete description of these instruments and their use in con- nection with District Heating may be found in the Heating and Ventilating Magazine beginning with the January, 1915 issue. The series of articles is entitled "District, Heat- ing" and is written by Bushnell and Orr. 46 . Tests at the Colorado School of Mines Power Plant. l. A description of the plant. The data and calculations which follow were taken from a series of readings and tests made at the Sohool of Mines power and heating plant during the year 1914. In order to better explain these readings a brief descrip- tion of the plant and apparatus will be given here. The power plant is desighed to furnish the school with both heat and power and at the same time serve as a laboratory for experimental work. The boiler room contains the following equipment: One 200 h.p. and one 100 h.p. Babcock and Wilcox water tube boilers each equipped with a chain grate stoker. ; One 80 h.p. return tubular boiler with a plain grate; a green fuel economizer; a Webster feed water heater; two boiler feed pumps; two vacuum pumps for the heating system; one Willoox water weigher; one 125 h.p. Westinghouse gas producer with auxilliaries; a 125 steel stack supplemented by a 42" fan. The engine room contains the following main units: one lo" x 12" high speed Russell engine belted to two electrical generating units, one 30 k.w.. alternator and one 15 k.w.. continuous ourrent generator; one 7" x 6" two- cylinder Westinghouse Jr. vertical engine belted to a 6 and an 8 k. w.generator; a 75 k.w. DeLaval turbine geared to twin generators; a two-stage steam driven air compressor; a là" x 14" three-cylinder Westinghouse gas-engine; three small units for laboratory purposes only. 47. The exhaust steam from the steam units passes to a common main which delivers to the heater. The surplus Steam passes on to the heating mains at a pressure of from 0 to 2 lbs.gage. As will later be observed the exhaust steam is not sufficient to supply the requirements of the heating system. This neoessitates the addition of live steam from the boilers at reduced pressure to sup— plement the exhaust steam from the engines. Interior views of the plant are shown on Pages 48 and 49. Plates I and II show the floor plan of the power plant and the general looation of the buildings which are heated from the central plant. 2. Data to be obtained. Practically the only way to obtain data of value on a plant of this kind is to take readings of instru- ments for a considerable length of time, preferably a year. In this way all climatie changes will be taken into acoount as well as the variations in the power load. These readings should be checked and supplemented by testing various parts of the equipment at frequent inter- vals. The data desired may be itemized as follows :- l. Boiler efficiency. - 2. Fuel consumption of power units. 3. Total feed water. 4. Total Goal; coal per day. 5. Cooling water for vacuum pump; radiator losses. AZ Z2. The Gas Engine-Generator Set. Tº <* 50. 6. Heating requirements; outside temperatures. 7. Total kilowatt output; daily and monthly power load. 8. Temperatures of feed water, oooling water, condensation. 3. Method of obtaining data. To minimize the chance for error a system was worked out whereby each attendant should keep a record of read- ings for his shift and turn in the records each day to the chief engineer who records them on charts provided for this purpose. The chart on Page 55 is self-explan— atory of the readings taken for the month of January. A similar chart was worked up for each month of the year. l. Boiler Efficiency. - Tests were made at frequent intervals on var- ious parts of the equipment. The sources of greatest loss were found to be air leakage in the boiler settings and steam leakage in the radiator traps. Page 51 shows the tabulation of one oft the tests made on the 200 hp. boiler. This is but one of a series of tests on the same boiler to determine not only the efficiency but the best kind of coal for our purposes. Frequent tests of flue gas gave the following results; G02––4%; 0––16%; CO--zero. After replacing a damper under the stoker and plugging up the setting carefully this oondition was improved. Later tests of flue gas showed the following analysis:-302--9%; 0––8%; CO--trace. Some of the coal tests were made in the year 1913 and in 1914 the coal best suited to our conditions was Azorcóaseº Æ,2/ cerrº-erzº. 5l. (Iſ a Loratºric, - - - school at 3 ſtinez, Mechanical Engineering Laboratory (ſ; olòen Qſ olo. Experiment. Capacity and Efficiency Test of Boiler For - - / Duration of Trial . . . . . . . . . . . . . . . . . . . . . . . . . hours. . . . . . . . 2% ºf Factor of Evaporation. . . . . . . . . . . . . . . . . . . . . . . . . . . |.A.433. - Rind of Boiler. . . . . . . . . Aºzzzzzzzzzz'...... …? & Azº. || Total from and at 212 °. . . . . . . . . . . . . . . . . . . . Ibs. . . .262/.4242 - - d- /- Rind of Grate. . . . . . . . . . . . .&zzzz zazz .* P A2.2%.4° WATER PER HOUR Grate surface, length & 8 wide ff.3.7 sq. ft. ...4%. 63. | Weight Used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . lbs.... sº.2.3 &2. Water Heating Surface . . . . . . . . . . . . . . . . . . . Sq. ft. . a 4742 (2.... Evaporated Dry Steam . . . . . . . . . . . . . . . . . . . . . . lbs.....: 2.4247 Superheating Surface. . . . . . . . . . . . . . . . . . . . . Sq. ft. . . . . . . . . . . . . . . . . . . Evaporated from and at 212 °. . . . . . . . . . . . . . Ibs...., 2 3 42&7. Area, Chimney. . . . . . . . . . . . . . . . . . . . . . . . . . . sq. ft. . A.:7.é.3 ... EVAIPORATHON | Height, Chimney . . . . . . . . . . . . . . . . . . . . . . . . . . . ft. . . /23 ...... 2 Z. cº’ per pound of fuel Ratio, Heating to Grate Surface. . . . . . . . . . . . . . . . . . . . . ºf . . *... ." .\-f". . . . . | - | Actual . . . . . - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - lbs. . ... º. 33. AVERAGE PRESSURES Equivalent from and at 212 °. . . . . . . . . . . . . . . lbs. . . . . . .Jº. 23. Barometer.... 2%zºzzº S.A’ºrºs. Has. naeºetry. . . . . 22.2 Steam Gauge . . . . . . . . . . . . . . . . . . . . lbs. ºper sq. in . . 2. …a5. Actual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . º Absolute Steam Pressure . . . . . . . . . . lbs. per sq. in . . 2. .../Jº .... Equivalent from and at 212 °. . . . . . . . . . . . . . ibs......2.3.6. Draught Gauge . . . . . . . . . . . . . . . . . . . . . . ins, water...... 33. ... - | per square foot Ireating surface per hour r-Y. N TTF-HY AVERAGE TEMPERATURES Actual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . lbs. . ... Zºº. -- Tºvº tº a r. O External Air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F. . . .2%. 2: .. Equivalent from and at 212 °. . . . . . . . . . . . . . . lbs. . ...?. 23. Boiler Room . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . °F. . . . . . . 227 - -*-------- - - - - per square foot of grate per hour Flue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . o F. . . 22.2 . . . . . . . . Actual, from Feed Water Temperature. . . . . . lbs... // 37 Furnace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . o F. -- || || “. . . . . . . . . - * I - - - - - - - - - - - - - - - - Equivalent from and at 212 °. . . . . . . . . . . . . . . lbs. . . . . .2%2.3 Feed Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . °F. ...A.2/85.25. -----------T------ - - HORSE POWER steam <2222 2.7zº Zez-.............. o F. . . . 2 23. . . . . . O IFUIEL On basis 34% Ibs... equiv. evap. per hour.... H. P...../6.2. - Builder's Rating . . . . . . . . . . . . . . . . . . . . . . . . . H. P. . Total Coal Consumed . . . . . . . . . . . . . . . . . . . . . . . . lbs. . .2.2 6 (242 ull Clel' S bºatling ... 2.67 & ... - - “Fºx -- Ratio of Commercial to Builders' rating. . . . . . . . . . ©.3. M t - C l - - | . . . .º. -------- Ol St lll'e lll CO3] . . . . . . . . . . . . . . . . . . . . . . . per Cent. . ... 22.2%. | | Dry Coal Consumed. . . . . . . . . . . . . . . . . . . . . . . . . lbs. . . 22.5 ºz.3 || ANALYSIS OF FUIEL Total Refuse, dry. . . . . . . . . . . . . . . . . . . . . . . . . . . lbs. . . . 2.5/.3. Fixed Carbon . . . . . - - - - - - - - - - - - - - - - - - - - per cent.....? a.3% Total Refuse, dry. . . . . . . . . . . . . . . . . . . . . . pel Cent. . ... 23. 22 Volatile Matter . . . . . . . . . . . . . . . . . . . . . . . . per cent......?3. Zé. Total combustible . .34%:…....... • * * * * lbs. . .2% A.23. Moisture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . per cent....../42.42% FUEL PER HOUIR, Ash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . per cent....... 2.42%. Dry Coal, per hour. . . - lbs 372.2 Heat value per lb. Dry Coal . . . . . . . . . . . . B. T. U. ...573 &23. Combustible, per hour. . . . . . . . . . . . . . . . . . . . . . . lbs. . . . . . . .2 < e.... Heat value per 1b. Comb. . . . . . . . . . . . . . . . B. T. U.....(42.2%2 * Dry Coal, per sq. foot of Grate. . . . . . . . . . . . lbs. . ... Zoº. 32. Efficiency of Boiler. . . . . . . . . . . . . . . . . . . . per cent. . . . . . . . 2.É. 6. Combustible, per sq. foot of Grate . . . . . . . . . . lbs 2% C2 Efficiency of Boiler and Grate . . . . . . . . per cent. . . . . . . . @4. 2.3T Dry Coal, per sq. foot of Heating Surface. . . . lbs. . ... & Ż3. COST OF EVAPORATING WATER 3. Zo Combustible, per sq. foot of Heating Surface. Ibs;...... (2.3.6. | Cost Coal per ton 2222 lbs., delivered.............. 2 < .. TOTAL WATER | Cost Coal to Evaporate 1000 lbs. Water under ob- Quality of Steam . . . . . . . . - - - - - - - - - - - - - -per cent. . . . . . . &&.&. served conditions . . . . . . . . . . . . . . . . . . . . . ............….?/ 2' Total Weight Water Used. . . . . . . . . . . . . . . . . . lbs. . ... 26. A 62 Cost Coal to evaporate 1000 lbs. Water from and Total Evaporated Dry steam... - - - - - - - - - - - - - lbs. . ...23.3.3a at 212° . . . . . . . . . . . . . . . . . . . . . . . . . . . . --------- ... Z85, 3.2 Observers-------------------------------------...------- 52. 2. Fuel Consumption of the Power Units. A test for steam consumption of the steam unit 3 could not be made except by orifice method on acoount of the lack of condensing equipment and the complicated arrang- ment of the piping. The values used in the calvulations are slightly higher than those of the manufactur ! 3 rating under our conditions. The results of a test of the gas producer power plant are given on Page 65 . 3. Total Feed Water. The total amount of water fed to the boilers was determined by the use of an automatic water weigher and checked by the tests of the boilers when the water was weighed by the use of platform Scales. 4. Coal. Each fireman was required to weigh the coal used during his shift. This was done by weighing the con- tents of several small track cars and taking the average weight. The cars were then counted. These weights were checked frequently. It is well to note in this connection the interest taken by the firemen and the consequent re- duction in our yearly coal consumption. This method has been followed for about three years during which time the coal bill has been reduced by 25% while the power load has increased. 5. Cooling Water. In making an investigation and report of the power and heating apparatus to the Board of Trustees T 53. installed a water meter on the cooling water supply line for the vacuum pump of the heating returns. During a period - of three months, October, November, December, 1913, the meter indicated the astonishing total flow of 250,000 gal— lons of water. During the year 1914 about l, 250,000 gal- lons of water for condensing purposes was injected into this line. The average temperature of the water at the pump after mixing with the oondensation was 130°Fah. The temperature of the cold supply averaged 50°Fah. The loss may be computed as follows :- l, 250,000gallons = 10,420,000 lbs. Each lb. received approximately 10,420,000 x (130-50) B. t.tl. s = 833,600,000 B. t. u. s . Each lb. of ooal under existing conditions gives up 6500 useful B. t.u. 3. The cooling water then represents a heat loss of 65 tons of coal per year. This is a finan— oial loss of 65 x *l.90 = *125. oo in round numbers. in cost The loss of water itself at lå; per thousand gallons is (1,250,000 +:1000) x , lá =#187.50 . 6. Heating requirements. Outside temperatures were taken daily and com— pared with those of the U.S. Weather forecaster at Denver, Colorado. The ohart on Page i3 was plotted from the average figures and not alone for the year l'ºl.4. The buildings are all constructed of brick and there is a total of approximately la ,000 sq. ft. of radiating surface in all of the rºoms. The boiler hp. required for 54. the period Ootober 1 to April 1 is approximately 130. This is readily computed by allowing an average radiation of 250 B. t.u. 3 per sq. ft. per hour for the heating require- ment, 3. 7. Total Kilowatt-hr output. These results were obtained by the use of re- cording instruments placed on the switchboard terminals. In addition to the amount of current recorded there is a considerable amount ( estimated at 2000 kº-Ars.) used for electric furnace work. This is not included in the cal– culations. 8. Radiator losses. The losses in cooling water might be attributed to the radiator since this is the direct source of this loss. The lossesbegause of the leakage of steam through the radiator traps were the cause of the erection of the apparatus indicated by the chart on Page 55 for testing the traps for steam leakage. As a result of these tests which included eight of the best known traps a change will be made during the coming summer whereby the old float traps will be removed and a more recent design of expansion trap will be installed in their place. Since this part of the test has no direct connection with this the sis only one of the tests will be included here. All of the traps in the institution are the webster water Seal Motor. The results of a test on this trap is found on Page 57. The writer hopes to publish an article on the subject of Steam Radiator traps at an early date. ºº-~ſºxe ſº ao- C/ 67/ 5，7ZZZZZZZZZZZZZZZ$77ZZ53» Z -/2， s/z/， /zºo/a/， /ºZZZZZZZ A^|- 27zz//7a/ ZZ//7/7 2227 2ZJ/4/42/ 2/&sz/2424/2 4 ZāZEāZ 27@ZRĀŽĀZZ A7%7，7 s zzzz>2Zs （~~~~ º & ~^2/324/24/zºº/ 3 6. J/7e// 422/06/. /*/Oay7° /*A*.57e / /ø/e/- 5ea/ //ozzzz- Aºy. Zé 57. A Test of Steam Traps. TT Art OT Trap TTC TTT) ---------- Webster Water Seal Motor. Tºstºn Ry 2 ºza … natº -- February 6, 1914. AT The Colorado school of Mine 3. FAnt ATOT --American-14 sections–80% sq. ft. App ARATTS ––Shown by Figure 15. - *- - - - - - - - tº-------- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Back Temperatures - Time Ins. "Tao. Tress. tºl tº t3 t4 pi pº 9 : 10 9 #lb. 180 70 93 75 - 6 - 7 :13 9 179 ll 2 l?0 8O ... 3 ... 3 : 15 9 179 l2O l?8 86 ..l •l : 20 9 178 156 138 95 l. 2 l. 2 : 24 9. 196 180 174 llā l. 4 l. 4 : 25 9 198 190 173 lá8 l. 5 1.5 : 28 9 199 194 l'75 l'75 l. 4 1.4 : 30 9 2O2 198 176 176 ... 8 ... 8 : 32 9 2O2 l'99 l'79 178 l. 2 1.2 : 35 9 2OO 198 L'79 179 l. 2 l. 2 : 40 9 l39 l'º6 178 178 1. 3 1. 2 : 45 9 199 190 136 176 l. 4 l. 3 : 50 9 199 lºſ) l'73 172 l. 46 l. 4 : 55 9 199 197 174 173 l. 4, 1.4 10 : 00 8 l99 l84 175 173 l. 3 1. 3 : O5 ; 198 183 l’6 175 l. 5 1. 5 : 10 7; 198 l82 178 177 l. 4 l. 5 : lä 7 11b. 198 l80 178 176 l. 3 1. 4 : 3 6 198 180 177 176 1. 4 l. 4 : 35 7 198 l8 O 179 178 l, 5 l. 5 : 35 7 198 180 179 179 1.6 1.6 : 50 7 198 180 180 177 l. 4 l. 4 : 55 7. 198 l82 18O 178 1. 45 1.4 ll. O5 8 #lb 198 18% 180 177 l. , 3 1. 3 ll. l'O 9 198 182 178 177 l. 4 1 .. 4 Condensation from radiator--------------- 40 lbs. Condensed vapor ------ tº------------------ 3 lbs. No water backed up in the radiator, no air binding, no noise. Barometer reading–––25.1 ! 32? 2æraz | Zºº/Zºaſ”|sººvae (242 aſ./62 ſºee222 ºzřZÉŹź2 a'zºzº-6°€ //6.6 °/^Zºéº º „º42&P 9/^_º & ºS/42/42/ º = Z +4^2-2„Ź ŹŹ 42_º / 0 aº-2’é? || 9 /^^^ º^ | ±es 2^.^4;" | 42 º/º/arae--„^ ^ ^ 2^zº || …ººo..º º ar || Oºzº ſºa’ | € - aſ º „raeº | /ae 42.2 €3.67/^ || ~a’zº || 6?& 4242 2/^ | ^^^ º 6°-2^ < as 92 || …º ºſ º ar | 22 éº ePay I dº o ſº z eº |0& _º^^?^º/^ | ~9&º |&P&G>^ 2^ | z）^943-2^&?¿?ºzº | gºº gº aſ 2 ? || 6? ? ? €?a’ | _ſº- º 2-zer |es= 42 42/47/-/^ar | € / ar é? ^^ | 2 øø ºg-AFæºlº º gº/* 9 / 9 av | 24 aº 8 aº || 2 4 ：-/ º [ºa 42 ºz， ， /|-^ aeº | zº /ºa^ º^?/^ | € 2 /^{（4）-272.2° Øzº | € （4 / º 27 | 24 / Gºa’ | / 'azar/aer |zaº (2_º a’ Zº/^-27 ſº | a^2 < 22/^ | 429 4/6--o º aero º ar/ … º /º/ º Iºaº _º^ £ºzé-/^-4，4'- || 27472€· 263 | € /Z 26-/6 ? ?zº || 24 : º.ae_ſº2 | 22 249 ay || 9° 36' 0 º [ºa _º are：P^^ | —/A& | areºzº-4 42/^ | aº e aº 6，9-º_º º ºzº | _ºr:Zraeº ºaz I o Oo e aº || 2 '24; º éº |&aº _º^_^ º^-474 - || 9 er 9 / 42/^ | 662.9 Zºº-2° ſº 22 || 62 °/8°º aº || oavaeº ^27 || ? 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'GP/-ºãº I (24. º Zº’aº | eº º 22 ºſº |&P/ 2 º 9 aſ./^ | &?/^ 2746 Aº | ±± z º.º.， |zº'é?.6 6262-- ſº: º/， /ºa^ | 2ºze-Zar || №-2, º ºeſ |Z/ 2 º： 2^/^ | (? & 2）^zº º | 62 O 27 º Zr | ſ_º^ 429--/ Z^2 ºſº I o ‘º e º 2° aº || 4 （ 42 º 62 ſº | 9 / 22 º „º/~ || &ºara”áº_º | a2 aº ay 279 || 94º º aeº ^ | 22° e 4343&º|--£ º £20-ºſº | 62，Paº Aºaº | zº raz º 67&º || 42/ _º^ av 27/^ | 0 ? ?_º & | ± 4763 ± 9 |_º&&&P^-----± ‘a’º; & a’ || Oº ^|^2’ | & 6 & 2 € / £/ _º ay / / / | _ºſºa”Afz& | &P&º_º zº ſº | Zºzº， GP2，Aº_º & €Paº--.^ “Z && ? || 2 // „’a’ || (22 º 67.6° | €/ do o as / | &P/^2?4-éº | ºzº eº aºaº º | z-aſ é°4°4’.ſº.6" º €Põ’- -*Z * 2&z&a’ | 24 o Ara” I gº raray o € | €/ ø2 º ſº z / | & ? ä”zº | eºs ºazº ! oººº^O 24 º 69 zº-6 Z.Z. 4-a” | a2 eº º 2° aº | _º - / / zºº || // ...º.， 42 2 / | areº ar|-/4° | 67Z º 9.6 || / 42 aº ſº，-_cº_º ºzė || ? ' 4 2 4 aº | Q º es º ar || GP-9 º oeſ || 2/ 22/^ º^ | Øer ar-42.6°9.^ ø ±46 | € &ººº_^-ä”/ º 94 || 2 “Zº ſé, a’ | 29 Pºay | ±± ' eº º 26" | 6 © 2&Pº/^ | -9 araſ-AS&P || 6?45 º 2&P | € eº » 99 || 2× ſº aº<-9 ^ ^ º ſé- || º ? € ± 2’._.-'-9 _º^ a^2 / | _º^ är | 47^ ^ | & & | 22^.^_ºas || 6247zº ^ ^-ä”/6_ºzº | / Tºerae a’—|- º 247 € 9 /^ | Pé° 2 | € £P.'^ | < ∞9ÆPaes ſºº-|-|-&> 'é' /& 27|--Aº o 2 aº 9.° | 2’é" ar | 422^ ^ | 6 € | 62 cº-e-ſº&P | 92 º 22-º 9&P_2,4 || ? 'a',/^2-a^-- -6° O_gº_cº e ^ | 07& 2 | - ºº ^ | 2’ gº | zºº ^^6 | 2° 22' 6"9-ºº-Zº ºz |-ºººººº aº || 2e− × 9a7|-a' º）^2& 2&-/^ | 076° 27 | 29/^ | /ſêrZ-26 & 2 | _^º^º^ 2 | Qeſ， ºſºar-ºAGP º º gº || 2 / (24-aº24°， eº ? | Aº º 6 aº | / ºg Lae|-zez|º|…！！！！!！！！！!！！！ Zº|ºz seº||zzzzzzz|， 247|× oº|×ZZZK， Zºº /4222 || 2 //zz42/2a/22/2Z№,s.62.//^2^2）y -/2/22，224，7 Calculations. Coal : —— One pound of coal will evaporate 5% pounds of water under actual conditions. One i. h.p. / hr. will be developed on 40 lbs. of steam under our conditions. This is equiv- alent to 60 lbs. of steam per kw—hr. (approximately) Lbs. of coal per kw-hr = 60/5} = 10.9 On the assumption that 30% of the above amount should be charged to power when the exhaust steam góes to the heating system gives 10.9 x . 20 = 2.2 lbs. per kw-hr during the heating season. From the average atmospheric conditions and the requirements of the heating system all of the exhaust steam can be utilized for heating from Ottober 15 to May 15. Cost of coal per kw-hr = 2.2 x i:20 F . 208C cents. 2OOO - During half of October and half of May it was estimated that 40% of the steam used by the engines should be charged against power, and during June, July, August and September all of the steam used by the engines is oharged against power. Engineer 3 wages:-- It was found that the engineer of the plant whose duties are varied devotes approximately one-half of his time to the engine room. during 9 months of the year. In the summer months one of the firemen assumes these duties along with other work of repairing and cleaning in the plant. One fireman only is needed on each shift 6O. and he would be needed for the heating plant alone. On this basis one-half of the engineer's time is properly charged against the cost of power. Fixed charges :- Since the power plant is used for laboratory purposes it is proper to assume that the overhead charges would be the same regardless of whether" the plant were used to pro- duce power. Power is a by-product. The laboratory is essen- tial and is so arranged that practically any unit is avail— able for testing purposes at any time. For these reasons no fixed charges have been included in the power costs. The effect of fixed charges:-- The value of the steam units with the electrical generating apparatus may be placed at $10,000. oo . Allowing a rate of 14% for interest, insurance, taxes, and depreciation we would have an annual fixed charge equal to 14% of $10,000. oo or #1460. oo . This would then increas e the average cost per kw-hr to (1400 + 765. 20) + 47510 = 4.75 cents. The i.h.p. of the steam units totals 150 which is equiv- alent to ll:2 kw. The average lºad considering an 8-hour day for 300 days per year would be 47510 – 2400 = 20 kw. (nearly). However during the heating season there are two shifts and the engines are operated for about 16 hours per day. This would give us an average load of about 10 kw. For the 6l. remainder of the day the storage battery handles the löad which is lighting only. The load factor is, then, . 10 : 112 - approximately 9%. The boiler horse-power that would be required for the power load can be computed as foſſlows :- 10 40 x --- F 545 lbs. of steam per hour. , 746 Boiler pressure =80+ gage. Feed water temp. = 220°Fah. 1184.8 – (220–32) Factor of evaporation = ---------------- = 1.00 (very nearly) 97O .. 4 Boiler horse-power - 545/ 34.5 - 15.8 . Ratioſ of the boiler horsepower required for power to that required for heating - 15.8 / 130 + 0.122 Øī9 • T • OT gae, † +Ogg 94, º IH“ ŽÁ* XI Ią đ ſe o o 93 ere AV - - - - - - - - - - - - - - - - - - - - - - - ----~--~~~~ -.• • • • • • • • • • • ► ► ► ► ► ► ► - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - & * g 9,$0009OgOT GA, † ST?! Oſſ, Off º 99g3°#9 º303 ºTg * 3OOT G9908 ſ,* O 9ÇI 0 !, º !, G3gº T!,9 * T903 º86° 2008692ț7Ç992* A. ONI - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - … … ---- 00° A,99 ſ, º T#g º T{&# º0 * TT()()() iſ; †;# ÇO+;º q o O • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •- - - - - - - - - - - - - - - - - ••• • • • • • O †7 * ?, ?,†76° 2i 6 * T# O º Tç* # T- 00993829?º qđæS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -*- → -+ - - - - - - - - - - - - - - - - - - - - - - - -*- e- → • • • • • • • • • •- - - - - - - - - - - - - - - - - - - - - - - - - - - Og º ſg† # * g# * #șO º TÇ& * 9OO GOET9çTT • q sin?\n\ OO * 0962！ 9g3 * g# O º T6T * g0820-TÇ Ç6• ACȚn p 09 º 6 g&, # * 9dž; * g#Q * T30 * gO GOOT336* 9U n ſ Oț7 ° 69O 9 * TGO * T2șºA, g * 2TO 09:09T39#• Kºeſ O 9 * O 9O2 º T66°\903 º3 g * g003 QQT909• Iđºff O ）, * 09£3.2, Tº T!,6°303°§ 9º G00929999 TQ* Jºeſ O? * Ç9 -#66°gº 6°303 º26 º 90096939929* G3）. O? * [9ģ;ççT º TG36 °903 ºO 6 * g()()()6 ggOŤ; g * Uſe C • ng oo · IHºmº y red 2: TH’ A’yŹº III • W • XIJ. 3M O OEI OȚ* sq.T. T?! Oſſ,4 s 00 Teq o J, J 9 d. Joqº'I J 9 đi q S OO Te o O p3$.IetųO Te 00Tºe CO Tºº! Oſſ, º S.I.Hºff º yſ , SUĻĻU OȚ * & \ S OO I ĐAA 03 J O AC I'ºt IIIIm S 63. The Gas Power Plant. In 1909 the erection of a metallurgical plant necessitated the provision for about 150 h.p. motor drive. The committee in charge recommended a lă0 h.p. Westing- house gas producer power plant for this purpose. This outfit was installed at a cost of approximately $20,000. oo. It was estimated that the engine would have an average load equivalent to 45 motor h.p. or 35 kW. , 8 hours per day for 3OO days in the year. This would give a yearly output equal to 8 x 300 x 35 = 84000 kw—hrs. The engine fails to develop more than 120 h.p. at this altitude and at that load does not regulate well. The engine under actual operating con- ditiºns developes a kw-hr on approximately 3 lbs. of lignite coal. (See report on Page 65). About one half of one man's time is required to operate the plant. Under these condi- tions we have the following power costs:-- Fixed charges---16% of *20,000.00 ---------43200.oo Fuel-63 x 84000 x 1.90) + 2000 ------------ 240. oo Labor ---------------------------- ---------__600.og Total---- #4040. oo Average cost per kilowatt–hour F404000+84OOO= 4.8 cents. Had a steam unit been installed for the same purpose the costs would have been approximately as follows:- Cost of installation——100 h.p. engine-generator set with Condensing apparatus ------------------ $5000. oo , The present boiler capacity (380 h.p.) is adequate. Turing 6 months of the year all of the exhaust steam could be used in the heating system. During the remainder of 64. of the year the engine could be run condensing. We would then have the following :-- Fixed charge-–l4% of $5000. oo –––––––––– $700. oo Fuel-––––– 6 mo.-- (.308 x 84000) + 2 –––––– 84. 50 6 mo. -- .84 x 42000 --------- 354. oo Labor --------------------- * - - - - - - -m-- - - - 6OO. oo Total————— *1736.50 Cost per kw—hr. ---173850-84000 - 2. O7 cents. Note: In the above calculations it is assumed that the labot charge would be equal in each case. This is manifest– ly not correct because the boilers are equipped with mech- anioal stokers and no extra help would be needed in the boiler room. Experience shows that a gas producer plant and engine requires much closer attention than a steam plant. It is therefore certain that in the plant under consideration the labor charge would be greater for the gas power than for the steam power. No mention is made of the water consumption and cost in the above calculations. Tests show that it requires about 100 lbs. of cooling water per kw—hr output for the gas engine. The annual water consumption would then amount to 100 x 84000 = 8,400,000 lbs. = 1,050,000 gallons. At 15%/1000 gallons this would cost per year #157.50 . - For the steam plant the water would be re-usea for 6 months of heating . During the remaining 6 months when running condensing, the amount of cooling water needed 65. would be approximately 16 x 35 x 42000 = 23, 520,000 lbs. where 16 is the amount of water required to condense one lb. of steam, and 35 is the steam consumption per kw-hr when running oondensing. This is approximately 3 times the amount used by the gas engine. In either case it would be an economical proposi- tion to install a cooling device so the cooling water could be used again. Golden, Colorado. December 20, 1913. Report on the School of Mines gas power plant during the period of operation for the Golden Illuminating Co. DAT AND LENGTH OT RTTT. December 18, 19, 20,--------- day load. Actual time of operation----- 19 hours. L^ AT). The total output in kilowatt–hours by integrating Wat; time tº 31' was 595. LABOR. The time of A. L. Rae, Engineer, was charged to the run. TTL. Coal used during the actual run-------- 1754 lb 3. WATTP. Coaling water on the gas engine---- -------- 966 ou. ft. OIL. Engine oil----------- 3 quart 3. OpERATINY COST.S. Labor----Engineer's time at 50% an hour----------- #9. 50 Coal----- 1754 lbs Ø "2.15 per ton (2000 lbs.)----- 1.90 Water---- 966 ou. ft. (7200 gal. )--6 lbf/1000 ---- l. O5 Oil------ 3 quarts of gas engine oil at 27.4/gal.--_, 20 Total—--- #13.65 Cost per kilowatt hour---------------------------- 2.12% “”2-24.2- - - --> - &T 2 67. Conclusions. l. Power can be produced at a cost of from lº to 1.5% per K. W. Hr. under average conditions of heating require– ments and coal cost if all of the exhaust steam is used for heating. 2. Fixed charges will average between .34 and lº per kilowatt hour in any isolated plant at load factors between loog', and 30%. 3. It is economical to discharge the exhaust steam into the heating system if the engines furnish 30% of the steam required for heating during 6 or 8 months of the year. 4. In institutions which require very little power during the non-heating period it pays to buy the power if it can be obtained at a rate under 54 per Kilowatt hr. unless the labor can be charged to another accoumit. 5. Exhaust steam is practically as efficient as live steam at a pressure in ºbst, Ju delivery . 6. One of the sources of creates: loss is in the radiator trap. 7. The greater the load factor the less will be the cost per kilowatt hour. 8. The greater the heating requirements the less will be the cost per kilowatt hour. - 9. The cost of power will be a minimum when the heating load and the power load are mostky nearly balanced. 68. 10. Caution should be exercised in the selection of the type of plant. When exhaust steam can be utilized for heating it is seldom economical to install a gas-producer plant. ll. At the Colorado School of Mines current can be pur- chased for 2.94 per kw-kr. It was not an economical propo- sition there fore to install the gas producer plant. in any event. With the $20,000. oo spent on this plant #5000. oo would have purchased a steam engine with equal capacity. *5000.00 more would have purchased a small gas producer power plant for laboratory purposes. The remaining *lſ)000. oo could have been utilized to good advantage in purchasing other equipment which is needed. * RULES COVERING USE OF MANUSCRIPT THESES IN THE UNIVERSITY OF MICHIGAN LIBRARY AND THE GRADUATE SCHOOL OFFICE Unpublished theses submitted for the doctor's degrees and deposited in the University of Michigan Library and in the Office of the Graduate School are open for inspection, but are to be used only with due regard to the rights of the authors. For this reason it is necessary to require that a manuscript thesis be read within the Library or the Office of the Graduate School. If the thesis is borrowed by another Library, the same rules should be observed by it. Bibliographical refer- ences may be noted, but passages may be copied only with the permission of the authors, and proper credit must be given in subsequent written or published work. Extensive copying or publication of the thesis in whole or in part must have the consent of the author as well as of the Dean of the Graduate School. This thesis by . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . has been used by the following persons, whose signatures attest their acceptance of the above restrictions. A Library which borrows this thesis for use by its readers is expected to secure the signature of each user. NAME AND ADDRESS DATE A7, Azs .572a A- ºzwo/ºe/ / /./ d^2-c^2）/ - - - - - - - - - - - - - - - - |||||----------------------------------- -| N\,| Q)1|}} . \，\\). Ș|ș Q§ è| |N!<|yn yÈ È Q|< .N§ §| |Nſo º š|N. 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