Method of cleaning stack gas and using same for generation of electric power

#The present invention relates to a method of treating pressurized stack gas. More particularly this invention concerns the treatment of such gases issuing from high-pressure blast furnaces and the like.

#Hot stack gases which issue from a blast furnace or the like at a pressure of several atmospheres are usually passed through a cleaning or purifying device which first separates out the larger particles carried by the gas and then subjects the gas to a scrubbing operation which removes many of the water-soluble gas components and removes additional particles from the gas stream.

#The above-cited earlier works describe so called Venturi or differential-pressure (annular-gap) washers which comprise a tube having a narrow waist in which is received a body that is displaceable within this tube so as to define a variable gap therewith. A sprayer is provided in the upstream end of the tube so that the turbulence and pressure drop in the tube will thoroughly scrub the remaining particles from the gas.

#The above and other objects, features, and advantages of the present invention will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

#FIG. 1 is a vertical sectional view partly in diagrammatic form illustrating a system according to the present invention;

#FIG. 2 is a section taken along line II -- II of FIG. 1, drawn to an enlarged scale;

#As shown in FIGS. 1 and 2 an apparatus for cleaning stack gas coming from a blast furnace 1 has a conduit whose extreme upstream section 2a leads from the cupola of the furnace to a coarse-particle separator 3. Another conduit section 2b leads from this particle separator 3 to a prescrubber 4 having a plurality of spray heads 5 that discharge waer sprays which, by washing, serve further to remove particles from the stack gas. The thus partially purified gas then passes through a set 6 of annular-gap washers from which the gas passes through conduit sections 2c and 2d to a final droplet separator 7 having angled vanes 8. The latter separator 7 removes all of the liquid from the gas before it is pulled away in a clean-gas output conduit 9. The pressure in the conduit section 2a is between 2 and 3 atmospheres and that in conduit 9 at the output of the system is approximatly 1 atmosphere.

#The set 6 of annular-gap washers comprises a plurality of Venturi-type pressure-drop washers 10 and 11 as shown in FIG. 2 having respective tubes or sleeves 10a, 11a and 11b within each of which is displaceable a central body 12. Spray heads 13 are provided in the tubes 10a, 11a and 11b above the bodies 12 in a manner substantially as described in the above-cited patents.

#The prescrubber 4 and the pressure-drop washer arrangement 6 are provided in a single upright tower 14 in which the stack gas passes from top to bottom. An upwardly concave conical horizontal partition wall 15 is provided in the tower 14 with the annular-gap washers 10 and 11 passing vertically through this wall 15. Water collected by this wall 15 is drawn off through a conduit 16. Thus the wall 15 divides the tower 14 into an upper chamber and a lower chamber. An upright partition wall 17 divides the chamber below the partition wall into a pair of compartments 18 and 19, the single annular-gap washer 10 opening into the compartment 18 and the two washers 11 into the compartment 19. The lower ends of these compartments are sealed by a single conical wall 20 in which are provided separate outlet conduits 21 and 22 for carrying off water.