Part 29 (2/2)
TYPICAL analYSES OF BLAST FURNACE GAS
+----------------------------------------------------------------+ |+-----------------------+------+----+-----+----+------+--------+| || |CO_{2}| O | CO | H |CH_{4}| N || |+-----------------------+------+----+-----+----+------+--------+| ||Bessemer Furnace | 985|036|3273|314||5392 || ||Bessemer Furnace | 114 ||277 |19 | 03 |587 || ||Bessemer Furnace | 100 ||262 |31 | 02 |605 || ||Bessemer Furnace | 91 ||287 |27 | 02 |593 || ||Bessemer Furnace | 135 ||252 |143||5987 || ||Bessemer Furnace[47] | 109 ||278 |28 | 02 |583 || ||Ferro Manganese Furnace| 71 ||301 |||628[48]|| ||Basic Ore Furnace | 160 |02 |236 |||602[48]|| |+-----------------------+------+----+-----+----+------+--------+| +----------------------------------------------------------------+
Until recently, the ias has been the capacity that can be developed with practically no attention given to the aspect of efficiency This phase of the question is noing attention and furnaces especially designed for good efficiency with this class of fuel are demanded The essential feature is aasessurfaces The gases have the power of burning out co surfaces, provided the initial teh, but where the combustion is completed before such time, the results secured are more satisfactory A furnace volume of approxiive a combustion space that is ample
Where there is the possibility of a failure of the gas supply, or where steam is required when the blast furnace is shut down, coal fired grates of sufficient size to get the required capacity should be installed
Where grates of full size are not required, ignition grates should be installed, which need be only large enough to carry a fire for igniting the gas or for generating a small quantity of stearates has no direct bearing on the size of the boiler The grates as burners in a standard position or as furnace and fired froe is claier of explosion on the re-ignition of gas after a tee of the supply and also that a considerable aood deal with this class of fuel and which is difficult to remove, deposits on the fire and is taken out when the fires are cleaned In any event, regardless of the location of the grates, a this dust, not only fro as a whole
Blast furnace gas burners are of two general types: Those in which the air for combustion is admitted around the burner proper, and those in which this air is adn of burner, provision should be as supply independently A gas opening of 8 square inch per rated horse poill enable a boiler to develop its noas pressure in the main of about 2 inches This pressure is ordinarily fros of the above size will be good for ordinary overloads The air openings should be from 75 to 85 square inch per rated horse power Good results are secured by inclining the gas burners slightly doard toward the rear of the furnace Where the burners are introduced over coal fired grates, they should be set high enough to give headroo
Ordinarily, individual stacks of 130 feet high with dia horse power are large enough for this class of work Such a stack will give a draft sufficient to allow a boiler to be operated at 175 per cent of its rated capacity, and beyond this point the capacity will not increase proportionately with the draft When more than one boiler is connected with a stack, the draft available at the damper should be equivalent to that which an individual stack of 130 feet high would give The draft from such a stack is necessary to hout all parts of the setting If the draft is increased above that which such a stack will give, difficulties arise from excess air for combustion with consequent loss in efficiency
A pooraction in the furnaceThis actionmore air to the furnace On account of the possibility of a pulsating action of the gases under certain conditions and the puffs or explosions, settings for this class of work should be carefully constructed and thoroughly buckstayed and tied
Natural Gas--Natural gas from different localities varies considerably in coiven a nuas froenerating purposes to a considerable extent in so It is best burned by e capable of handling 30 noe nu or blowpipe action, which e burners are used Ordinarily, such a gas, as it enters the burners, is under a pressure of about 8 ounces For the purpose of coas reduced to the standard conditions of terees Fahrenheit and 147 pounds per square inch When the tes are known, the voluas under standard conditions s in cubic feet by 3354 P/T, in which P equals the absolute pressure in pounds per square inch and T equals the absolute te work, the evaporation should always be reduced to that per cubic foot of gas under standard conditions
TABLE 50
TYPICAL analYSES (BY VOLUME) AND CALORIFIC VALUES OF NATURAL GAS FROM VARIOUS LOCALITIES
+----------------+-----+-----+-----+-----+-----+----+-------+------+--------+ |Locality of Well| H |CH_{4}| CO |CO_{2}| N | O | Heavy |H_{2}S|B t u| | | | | | | | |Hydro- | | per | | | | | | | | |carbons| | Cubic | | | | | | | | | | | Foot | | | | | | | | | | |Calcul- | | | | | | | | | | |ated[49]| |----------------+-----+-----+-----+-----+-----+----+-------+------+--------+ |Anderson, Ind | 186|9307| 073| 026| 302|042| 047 | 015 | 1017 | |Marion, Ind | 120|9316| 060| 030| 343|055| 015 | 020 | 1009 | |Muncie, Ind | 235|9267| 045| 025| 353|035| 025 | 015 | 1004 | |Olean, N Y | |9650| 050| | |200| 100 | | 1018 | |Findlay, O | 164|9335| 041| 025| 341|039| 035 | 020 | 1011 | |St Ive, Pa | 610|7554|Trace| 034| | | 1812 | | 1117 | |Cherry Tree, Pa|2250|6027| | 228| 732|083| 680 | | 842 | |Grapeville, Pa |2456|1493|Trace|Trace|1869|122| 4060 | | 925 | |Harvey Well, | | | | | | | | | | | Butler Co, Pa|1350|8000|Trace| 066| | | 572 | | 998 | |Pittsburgh, Pa | 964|5785| 100| |2341|210| 600 | | 748 | |Pittsburgh, Pa |2002|7218| 100| 080| |110| 430 | | 917 | |Pittsburgh, Pa |2616|6525| 080| 060| |080| 630 | | 899 | +----------------+-----+-----+-----+-----+-----+----+-------+------+--------+
[Illustration: 1600 Horse-power Installation of Babcock & Wilcox Boilers and Superheaters at the Carnegie Natural Gas Co, Underwood, W Va
Natural Gas is the Fuel Burned under these Boilers]
When natural gas is the only fuel, the burners should be evenly distributed over the lower portion of the boiler front If the fuel is used as an auxiliary to coal, the burners e combustion space is essential and a voluive good results The burners should be of a design which give the gas and air a rotary motion to insure a proper mixture A checkerall is sometimes placed in the furnace about 3 feet fron of burner this is unnecessary Where the gas is burned alone and no grates are furnished, good results are secured by inclining the burner doard to the rear at a slight angle
By-product coke Oven Gas--By-product coke oven gas is a product of the destructive distillation of coal in a distilling or by-product coke oven In this class of apparatus the gases, instead of being burned at the point of their origin, as in a beehive or retort coke oven, are taken froh an uptake pipe, cooled and yield as by-products tar, aas product is burned in the ovens and the re or fuel purposes, thewith plant operation and locality
Table 51 gives the analyses and heat value of certain saas utilized for fuel purposes
This gas is nearer to natural gas in its heat value than is blast furnace gas, and in general the reas and the features to be followed in furnace design hold as well for by-product coke oven gas
TABLE 51
TYPICAL analYSES OF BY-PRODUCT cokE OVEN GAS
+----------------------------------------------+ |+------+-------------------------------------+| ||CO_{2}| O |CO |CH_{4}| H | N |Btu per|| || | | | | | |Cubic Foot|| |+------+-----+---+------+----+----+----------+| || 075 |Trace|60|2815 |530|121| 505 || || 200 |Trace|32|1880 |572|180| 399 || || 320 | 04 |63|2960 |416|161| 551 || || 080 | 16 |49|2840 |542|101| 460 || |+------+-----+---+------+----+----+----------+| +----------------------------------------------+
The essential difference in burning the two fuels is the pressure under which it reaches the gas burner Where this is ordinarily froas, it is approximately 4 inches of water in the case of by-product coke oven gas This necessitates the use of larger gas openings in the burners for the latter class of fuel than for the foras comes to the burners saturated without of water of condensation This gas too, carries a large proportion of tar and hydrocarbons which form a deposit in the burners and provision should bethis out This is best acco out of the burners by steam