Document q3EnZaQ0E1GqegkreezD531bR

334 CHAPTER 13 1952 Guide' \ Fuels and Combustion 335 T a b le 6. T y p ic a l Gas A nalyses Constituents o f Oas--Percent by Volume 0ThAits6t0aFblaenadb3st0rianc.temdefrroourmy,GaasbesooulsutFeuperl*e,ssAurme.erican Goa Association, and from A.G.A. Laboratories Data. HH mEO s1 0la) t- OhhwWh =? "oo cS c3<N: . * W -W.S d d^ W O w _o_ w o QONO W5N o S3 o o tNJ* UcHO5 O**NIs*ffOieON050OC4OJHtO*. oo ' Nca. - 0U50NC5N0000 o N o' SgBSSSS-5i3S S- g - S oooooo-oooo o* co oo e* . . HCONM ;oot^ : C c iN0 co a <N e*0de3o co t ? co- os oo co ^ tH^.H-h Cc <oe*C"-o>uate*oot'-co o <?< oo c rHoi TjJ T* ^ CO CM to c o o eo t-h od c dddd -H o* c* to to or- co d *-I d d d co c* d c8 a3 3 <8 _*3_ *t3o- *bo. *UoS'Uo, Sages H>aOaoOoaOaoOoa dOJ4 . as r Ife (o5d o> ^is-g :o3o Et = -Sg fc 5 o O S fta -g.S odroS 3- .* ca e* *- .S 2 g o^qg>SaPLsOiOsO W?c35 >ja d .1 nWWfc o 55 Q Ht ab9o -- as a c h ee o5 fl a fl 3*2 2o0.02o*033 3**28 f*l*fl Js&.ckmwm aj & c-- *T3 aS 2* 3 |!au"!gn|1T13 TJogo. M> a qq o O 2(8 "^S B'O to ffl "g 2.2 = 3 5;= OOOA.CPPqOOS t* 00 *-H C* CHO ^Tf44 tHo H |hHs* 0H000 H . Cl foot of gas saturated with water vapor and measured at 60 F and 30 in. of mercury, with air at the same temperature and pressure. Products of 1 combustion are cooled to the initial temperature of the gas and air and the water formed by combustion of free and combined hydrogen is condensed to the liquid state. Classification of Gases Representative properties of gaseous fuels commonly employed for do mestic heating processes are shown in Table 6. Natural gas contains from 55 to 98 percent methane with various per centages of higher hydrocarbons, chiefly ethane. In addition to these components, small quantities of non-combustible gases such as carbon dioxide, nitrogen, and helium are sometimes present. Percentages of the different components vary with the area from which natural gas is with drawn. They may even vary slightly from any given well during its lifetime but these variations are inconsequential insofar as the utilization of the gas is concerned. Heating values of natural gases vary from 900 to 1400 Btu per cu ft but the usual range for use is from 1000 to 1050 Btu (gross) per cu ft. A typical analysis is given in Table 6. Manufactured gases commonly produced are listed in Table 6. Gross, f or higher, calorific values of typical send-out gases made from these manu factured gases generally range from 500 to 600 Btu per cu ft. Due largely to the greatly increased demand for city gases the tendency during recent years has been to increase rather than to decrease heat content of manu factured gases, thus making it possible to serve more customers through the existing distribution system. Mixed gases are a result of increased distribution of natural gas, through transcontinental transmission lines, into areas having existing manufac tured gas facilities. In such instances some gas companies supply a 600 to 800 Btu mixture (See Table 6). In some territories these mixtures are distributed as an intermediate step in changing over from manufactured gas to natural gas. Although the burden of adjusting installed heating and air conditioning equipment and supplying, new orifices and burner equipment is generally assumed by the gas companies when the gas ischanged, it is advisable to consult the local gas company to insure that equipment is provided with proper orifices and burners when installed. Most states enforce legislation through their public service commissions to require delivery of a gas of specified average or minimum heating value within their respective limits. Any given heating value within reason fortunately may be maintained and yet permit considerable latitude in the composition of the gas distributed. Hence the constituents of city gases are not necessarily the same in different districts nor even at succes sive stations in the same district. In every community, however, the objective is to maintain variations in composition and gas pressure within limits which will provide satisfactory operation and performance of all common types of gas burning equipment. Liquefied petroleum, gases, such as propane and butane or mixtures thereof have calorific values ranging from 2500 to 3200 Btu per cu ft. These fuels are often supplied as liquids under pressure in tanks or bottles. In such cases the liquid evaporates when pressure is relieved, the heat neces sary for vaporization being obtained from the surrounding air or ground. As butane boils at 32 F some provision is necessary, for maintaining the gas above this temperature or for lowering- the partial pressure by dilution