Advanced development of a pressurized ash agglomerating fluidized-bed coal gasification system. Quarterly progress report, April 1-June 30, 1982 Page: 93 of 105
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The local gas velocity can be calculated readily from:
U = g AP(8
f
The experimental pressure drop measured by the pitot tube was substantially
larger than heat calculated from equation (7). It was concluded that the
pitot tube must have been measuring both the gas and the solids momentum. The
correct equation should be
AP P . U g s (1-0).Us2
AP = g + (9)
- 2gc +2 gc
Equation (9) has three unknowns, i.e., the gas velocity U , the solid
particle velocity, Us, and the local voidage, E. In order to calculate
the gas velocity profiles from the measured pressure profiles using equation
(9), two more assumptions were made. The voidage distribution in the jet was
assumed to depend exponentially only on the distance from the jet nozzle. The
voidage at any height, Eh, can then be calculated from:
Qn e
h exp E L L h], (10)
where co = voidage at the jet nozzle; eo = 1 when the jet is a pure
gas jet
cL = voidage at the end of jet penetration can be assumed to be equal
to emf, voidage at minimum fluidization
L = jet penetration depth
The slip velocity between the gas and the solid particles was assumed to be
equal to the terminal velocity of a single particle. Or,
Us= Ug-Ut (11)
Solving equations (9) through (11), the gas velocity profile can be obtained.
A typical gas velocity profile using these assumptions is shown in Figure
5-5. Reasonable results have been obtained through this approach. The
detailed results will be reported in the next quarterly report.83
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Advanced development of a pressurized ash agglomerating fluidized-bed coal gasification system. Quarterly progress report, April 1-June 30, 1982, report, October 21, 1982; United States. (https://digital.library.unt.edu/ark:/67531/metadc1058542/m1/93/: accessed April 20, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.