OCR Text |
Show Where P is the pressure of operation of the burner. For conditions such that i) W t b > 1.0 or ii) tw/tres > 1.0 no ash will be rejected on the wall. For the present MHD burner, condition (i) applies. Thus the condition tJth > 1 w b implies that the following group A°-7/ y-7 r i-v-3 ? ? \vopg,o/ rw P tml 1.7 1.3 ' 3.2 1.3 d P rg,i Y n > i 0,°° (19) for the zero ash capture break point, where v , p are the properties evaluated at pressure P = 1 atm. An increasing value of G implies decreased ash rejection. The dominant operational parameter appears to be the particle size. Note that a lesser concentration of Y (a richer environment) as in o» a two-stage cyclone enhances slag rejection due to increased burning times of particles relative to transport time to wall, as well as a lower bulk temperature driving ash vaporization. The time scales so far obtained for t presumes that gas is injected tangentially a at the walls. However, the center line of the secondary air-jet is at a radius of 17.7 cm while the cyclone radius is 20 cm. * If residence time t falls . below intersection point P, a different law exists. All the article sizes below point Q-> will be burned; particles having size dp,3 < dp < dp,4 wil' e s " P e unturned. Ash will be lost for all particles having size below d ». Consequently, one should keep tpes above P. IMPACT TIME BURNING TIME RESIDENCE TIME 'P.3 BP.4 -25- Z///AVCO EVERETT |