(1) From the results of the measurements on the length of flame and the composition of gas at various points in the flame, in which coal gas streams upwards from a tube into air, it was revealed that: the rate of combustion of coal gas is governed by the rate of mixing of gas and air. When the gas is emitted with a high velocity, turbulence is introduced into the flow stream and at the same time the burning velocity increases extremely.
In the coal gas flame it is remarkable that the partial oxydation of methane occurs in the first stage of combustion to form carbon monoxide and hydrogene, and the combustion of methane can be replaced by the combution of the corresponding amount of these gases. Therefore the concentration gradient of combustible gas in the flame can be determined by the same procedure as in the case of water gas.
(2) The equation expressing the distribution of concentration gas in the flame was derived mathematically on the base of the following condition: the boundary between flue gas and external air is not constant, but varies with flame travel.
(3) From the results of the determination of dynamic pressure and temperature in the flame it was confirmed that: (a) the average velocity of the flue gas decreases with an increasing of the distance from the burner top. (b) By the line reversal method the value of correction, which must be added to the value of flame temperature measured by an ordinary ther mocouple method, can be obtained.
(4) Compared with the calculated and experimental flame temperatures the agreement is satisfactory.
(5) The experimental formula expressing the effect of diameter of burner and port velocity of gas upon the length of flame was derived. In the case of turbulent flow, the length of flame L (cm) is indicated by L=62.8d1/2, where d (cm) is the diameter of burner.
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