IanLK Wrote:
-------------------------------------------------------
> Here is a Master Mechanic front end:
> [
ngdiscussion.net],
> 413952#msg-413952
>
> An Anderson cyclone is basically a set of baffle
> plates stood on end below the petticoat, without
> any netting. Here's 484's with netting added, but
> you get the idea:
> [
ngdiscussion.net],
> 442195#msg-442195
Go back earlier still, the early coal burning engines usually mounted the spark netting in the stack, usually along with a cone for the cinders to beat on. That's where you get the diamond stack coal burners from in the early days. Stack-mounted spark netting worked okay for wood burners (using bonnet stacks, radley & hunter, etc) but coal cinders are a lot harder and it's more problematic if you suck some down into the cylinder pipes, good way to damage things. So hence you saw the development of the extended smokeboxes that put the smark netting and baffle plates inside there. Usually it's arranged so it not only reduces cinders being blown out the stack, but also provides protection for the pipes leading from the cylinders. This protection is very evident in the drawing linked above. Sometimes you saw similar smokebox-mounted arrangements used on wood burning engines, since it's convenient, but never became so greatly predominant for them like it did for coal fueled engines. Between the 1870's and the adoption of the "master mechanic" front end around the turn of the century you saw a wide variety of individual arrangements utilized, some more effective than others.
It's harder to come up with a satisfactory solution on a coal burning engine because on average you need a stronger draft to burn coal decently than you do wood. Coal's crabby stuff at times. It likes to smoke, it likes to clinker, sometimes you get loads that seem like more dirt than coal, it can be a pain. Every obstruction reduces draft so it's a balancing act. If the C&T is sufficiently determined they ought to be able to find *some* system that satisfactorily reduces spark emissions. Only real question is how much experimentation they want to do and how often they want to send someone in to shovel out the smokebox.
Those screens do require somewhat regular inspection and periodic replacement. One big advantage to the cyclone was it was practically a "set it and forget it" device. The screens, eventually from scouring action they develop weak spots and holes, which of course allows large objects through and defeats the point of the system. I do not say this for the benefit of the C&T workers--they certainly know how to do their jobs--but for the benefit of other readers who might be less familiar.
