Gas cleaning device for controlling air pollution from the charging ports of a by-product coke oven and for obtaining superior quality by-products

Claim 1

In a by-product coke oven having charging ports for filling the coke oven with coal and having a vertical off-take pipe for collecting off-gases and smoke from a coke oven, the oven off-take pipe having upper and lower sections and including a steam aspirator in the upper section for aspirating the off-gases from the oven the improvement comprising an air pollution control device for cleaning coarse particulate matter from the off-gases during the period when coal is being charged into the oven, the device adapted to permit sufficient aspiration pressure so that substantially all of the off-gases and smoke are drawn through the off-take pipe during the oven charging period thereby preventing the escape of off-gases and smoke through the charging ports to the atmosphere, the device comprising of a shroud, cone baffle, spray nozzles and scrubbant collection piping, and designed so as to change the direction and velocity of the gases and wet the particulate matter, i.e., solid particles entrained in the gas, stream, so that the coarse particulate particles are separated and dropped from the gas stream before the gases are drawn upward into the upper section of the off-take piping by the action of the steam aspirator and thence discharged to the gas collection main; the lower part of the shroud is made sufficiently larger than the lower off-take pipe so that the area of the space between the shroud and the lower off-take pipe is larger than the cross-sectional area of the lower off-take pipe so as to allow the off-gases flowing upwardly from the lower off-take pipe to enter into the said larger shroud space and thus expand and reduce velocity; the base of the shroud, also being sloped so that the scrubbant liquid can effectively wash down the collected particulate matter; the upper part of the shroud being contoured so that the sides of the shroud and cone baffle are sloped in diverging directions so as to relieve the back pressure of the gas between the shroud and cone baffle, above the cone baffle and thus to increase the gas velocity and to produce a laminar flow of gases upwardly which will facilitate the aspiration of gas from the oven into the gas collection main during the oven charging period; a cone baffle located sufficiently high above the lower off-take pipe so as to minimize gas pressure drop as the gases are deflected into the shroud area, the base diameter of the cone baffle being sized to form a smaller area or constriction between the cone baffle and the shroud than the area between the shroud and the lower off-take pipe so as to increase the gas velocity through the constriction and thence flowing upward, aided by the diverging slopes of the shroud and cone baffle; the cone baffle may be modified from that depicted in FIG. 2 depending on the overall height of the off-take piping providing, however, that the slope of the cone baffle diverges from the slope of the shroud and the cone baffle is high enough to confine the liquid spray on the side of the cone corresponding to the respective spray nozzle; the liquid spray nozzles are located below and away from the steam aspirator so as to prevent the sprayed liquid from becoming entrained with the steam aspiration stream and thus being short circuited into the gas collection main; the spray nozzles being positioned near the cone baffle so as to direct the liquid uniformly distributed onto the cone baffle, said nozzles with flat elliptical orifices to produce a wide narrow spray pattern and the spray directed in a path normal to the surface of the cone so as to restrict the sprayed liquid to the cone surface, said nozzles also spaced equidistant around the cone baffle as required to evenly distribute the sprayed liquid around the cone baffle so as to produce a uniform liquid curtain fall between the cone baffle and the lower off-take pipe, such that the coarse particulate particles entrained in the gas stream are sufficiently wetted and forced to drop from the gas stream as the gas stream changes direction and velocity; the gases also passing through the upper sprays are further scrubbed of particulate matter; thus, the shroud, cone baffle and spray nozzles working in conjunction with the steam aspirator, are a means for wetting the particulate matter and changing the direction and velocity of the gas stream so as to effectively scrub the coarse particulates from the oven off-gases during the oven charging period.