Document o90oLn6Ok5wQV8GBGqwezoJgr

American Society of Heating and Ventilating Engineers Guidi Chapter 25--Boilers 3300 Btu per sq ft per hour for hand-fired boilers and 4000 Btu ne per hour for mechanically fired boilers when operating at design When operating at maximum food2 these values will run between finnn a60n0n0n Bdt.u..p__e_r__s_qcf.t._p__e_ri-h--o--u--r-. Bo_ i:liers opera- tin-g under f<-avorab- le coUnUdU it'^ at the above heat transfer rates will give exit gas temperatures that considered consistent with good practice. 316 TESTING AND RATING CODES The Society has adopted three solid fuel testing codes, a solid f, .T rating code and an oil fuel testing code. A.S.H.V.E. Standard and Short^l Form Heat Balance Codes for Testing Low-Pressure Steam Heatin' Solid Fuel Boilers--Codes 1 and 2--(Revision of June 1929)s, are intended'^ to provide a method for conducting and reporting tests to determine heat~i efficiency and performance characteristics. A.S.H.V.E. Performance^ Test Code for Steam Heating Solid Fuel Boilers--Code No. 3--(Edition of^ 1929)3.is intended for use with A.S.H.V.E. Code for Rating Steam Heating a Solid Fuel Hand-Fired Boilers4. The object of this test code is to specify]4 the tests to be conducted and to provide a method for conducting and' reporting tests to determine the efficiencies and performance of the boiler.^ The A.S.H.V.E. Standard Code for Testing Steam Heating Boilers? Burning Oil Fuel5 is intended to provide a standard method for con- i ducting and reporting tests to determine the heating efficiency and per- ' formance characteristics when oil fuel is used with steam heating boilers. The Steel Heating Boiler Institute suggests a single number dimensional i rating in the S.H.B.I. Code for the Rating of Low-Pressure Heating ] Boilers by Their Physical Characteristics6. BOILER OUTPUT Boiler output as defined in A.S.H.V.E. Performance Test Code for Steam Heating Solid Fuel Boilers (Code No. 3) is the quantity of heat available at the boiler nozzle with the boiler normally insulated. It should be based on actual tests conducted in accordance with this code. This output is usually stated in Btu and in square feet of equivalent heat ing surface (radiation). According to the A.S.H.V.E. Standard Code for Rating Steam Heating Solid Fuel Hand-Fired Boilers, the performance data should be given in tabular or curve form on the following items for at least five outputs ranging from maximum down to 35 per cent of maxi mum: (1) fuel available, (2) combustion rate, (3) efficiency, (4) draft tension, (5) flue gas temperature. The only definite restriction placed on setting the maximum output is that priming shall not exceed 2 per cent. These curves provide complete data regarding the performance of the boiler under test conditions. Certain other pertinent information, such as grate area, heating surface and chimney dimensions is desirable also in forming an opinion of how the boiler will perform in actual service. The output of large heating boilers is frequently stated in terms of *For definitions of design load and maximum load see pages 411 and 412. *See A.S.H.V.E. Transactions, Vol. 35, 1929. Also Chapter 41. `See A.S.H.V.E. Transactions, Vol. 36, 1930. Also Chapter 41. `See A.S.H.V.E. Transactions, Vol. 37, 1931. Also Chapter 41. See Rating of Heating Boilers by Their Physical Characteristics, by C. E. Bronson (A.S.H.V.E. Trans actions. Vol. 36, 1930). 410 iijiorsepower instead of in Btu per hour or square feet of equivalent ^I^^'ijorsepower: The evaporation of 34.5. lb of water per hour gjg f which is equivalent to a heat output of 970.2 X 34.5 = |$n#Btu per hour- 5 rN^aiFnt Evaporation: The amount of water a boiler would pounds per hour, if it received feed water at 212 F and at this same temperature and at atmospheric pressure. usUally Considered that 10 sq ft of boiler heating surface will pro1 a fated boiler horsepower. A rated boiler horsepower in turn ferry a design load of from 100 to 140 sq ft of equivalent radiation. "S^SS.i^pareht, therefore, that 1 sq ft of boiler heating surface can carry a load of from 10 to 14 sq ft of equivalent radiation, or somewhat the boiler is forced above rating. The application of these values discussed under the heading Selection of Boilers. f BOILER EFFICIENCY - term efficiency as used for guarantees of boiler performance is construed as follows: ftSolid Fuels. The efficiency of the boiler alone is the ratio of the heat absorbed by me`water and steam in the boiler per pound of combustible burned on the grate to the SBealonfic value of 1 lb of combustible as fired. The combined efficiency of hotter, furnace is the ratio of the heat absorbed by the water and steam in the boiler per pound jSofliiel as fired to the calorific value of 1 lb of fuel as fired. Liquid Fuels. The combined efficiency of boiler, furnace and burner is the ratio of iWttt'heat absorbed by the water and steam iti the boiler per pound of fuel to the calorific, ^sffivaliie of 1 lb of fuel. $Ftf&S%jS**olid fuel boilers usually show an efficiency of 50 to 75 per cent when Asoperated under favorable conditions at their rated capacities. Infor]?ijmation on the combined efficiencies of boiler, furnace and burner has {^resulted from research conducted at Yale University in cooperation with '*;j?tjbe A.S.H.ViE. Research Laboratory and the American Oil Burner 'M'Association7. For general information on heating efficiencies see.Chapter SELECTION OF BOILERS S-JSEstimated Design Load: The load, stated in Btu per hour or equiv^Asajent direct radiation, as estimated by the purchaser for the conditions of '3j*inade and outside temperature for which the amount of installed radiation V]5was determined is the sum of the heat emission of the radiation to be ..`jpiftually installed plus the allowance for the heat loss of the connecting o'Bjjiping plus the heat requirement for any apparatus requiring heat con^nttted with the system (A.S.H.V.E. Standard Code for Rating Steam ttxHeiting Solid Fuel Hand-Fired Boilers--Edition of April, 1932). .(JyssVrhe estimated design load is the sum of the following three items*: P' 1- The estimated heat emission in Btu per hour of the connected radiation (direct, "indirect or central fan) to be installed. 38. 1932). .-iIJSee A.S.H.V.E. Code of Minimum Requirements for the Heating and Ventilation of Buildings (Edition1 d 1929). 411