Part 35 (1/2)

The heat losses are:

(A) Loss due to moisture in coal,

= 01831 ((212-81)+9704+47(480-212)) = 22 B t u, = 015 per cent

(B) The loss due to the burning of hydrogen:

= 90560((212-81)+9704+47(480-212)) = 618 B t u, = 434 per cent

(C) To coases per pound of coal the weight of such gases ht per pound of coal is:

(11CO_{2}+8O+7(CO+N)) (-------------------)C ( 3(CO_{2}+CO) )

where CO_{2}, O, CO and H are the percentage by voluas analysis and C is the percentage by weight of carbon in the dry fuel Hence the weight of gas per pound of coal will be,

(111433+8454+7(011+8102)) (-----------------------------)7857 = 137 pounds

( 3(1433+011) )

Therefore the loss of heat in the dry gases carried up the chimney =

137024(480-81) = 1311 B t u, = 922 per cent

(D) The loss due to incomplete coas analysis is:

011 ----------785710,150 = 61 B t u, 1433+011 = 43 per cent

(E) The loss due to unconsumed carbon in the ash:

The analysis of the ash showed 179 per cent to be combustible matter, all of which is assumed to be carbon The test showed 1000 of the total dry fuel fired to be ash Hence 1000179 = 179 per cent of the total fuel represents the proportion of this total unconsumed in the ash and the loss due to this cause is

179 per cent 14,600 = 261 B t u, = 183 per cent

The heat absorbed by the boilers per pound of dry fuel is 11719704 = 11,363 B t u This quantity plus losses (A), (B), (C), (D) and (E), or 11,363+22+618+1311+61+261 = 13,636 B t u accounted for The heat value of the coal, 14,225 B t u, less 13,636 B t u, leaves 589 B t u, unaccounted for losses, or 415 per cent

The heat balance should be arranged in the form indicated by Table 58

TABLE 58

HEAT BALANCE

B T U PER POUND DRY COAL 14,225

+----------------------------------------------------------------------+ |+--------------------------------------------------------------------+| || |B t u|Per Cent|| |+--------------------------------------------------+--------+--------+| ||Heat absorbed by Boiler | 11,363 | 7988 || ||Loss due to Evaporation of Moisture in Fuel | 22 | 015 || ||Loss due to Moisture foren| 618 | 434 || ||Loss due to Heat carried away in Dry Chimney Gases| 1311 | 922 || ||Loss due to Incomplete Combustion of Carbon | 61 | 043 || ||Loss due to Unconsumed Carbon in the Ash | 261 | 183 || ||Loss due to Radiation and Unaccounted Losses | 589 | 415 || |+--------------------------------------------------+--------+--------+| ||Total | 14,225 | 10000 || |+--------------------------------------------------+--------+--------+| +----------------------------------------------------------------------+

Application of Heat Balance--A heat balance should be made in connection with any boiler trial on which sufficient data for its computation has been obtained This is particularly true where the boiler performance has been considered unsatisfactory The distribution of the heat is thus determined and any extraordinary losssuch a heat balance is not available, such a calculation based on certain assumptions is soest loss is ordinarily due to the chias and its te the boiler As pointed out in the chapter on flue gas analysis, the lower lias is fixed by the minimum air supplied hich complete combustion may be obtained As shohere this supply is unduly s the carbon to CO instead of to CO_{2} as