I've been researching the use of pulse detonation in cleaning coal-fired furnaces. From what I've found there are two popular units currently in use, the Powerwave+ produced by GE and the SHOCKsystem by Pratt & Whitney. (But now it seems P&W has moved that business to another company, SHOCKsystem.) Does anyone have an idea which of these systems has been seeing more use? I appreciate any comments.

Thanks!

I'd guess the furnace repair guy who follows them around is really, er, cleaning up...

 

Mike Halloran
Pembroke Pines, FL, USA

Perhaps. Sending shock waves from pule jet detonation through a system not designed for that application could be problematic. However, I have not yet heard about any problems from using these methods. Anybody here involved in that industry that could comment?

 

In the old days, when men were men , and sheep were scared, they also had 2 pulse dentonation technologies for cleaning furnaces, under the trade names TNT and SHOTGUN.

And what was the name of that old bird that had all that business sewed up?  I saw him put a clinker about the size of a school bus into the furnace hopper once.

rmw

veritas86,

Shotgun usage was (is?) sufficiently common that special single shot "slag-buster" shotguns were (are?) made by major gun manufacturers.  They have much thicker, heavier barrels to withstand the large number of shell fired.  A side benefit of the greater barrel weight is reduced shock loading to the shoulder of the person(s) blessed with the duty of firing hundreds of rounds into a slagged up furnace.

Explosives usually don't do any significant damage directly, but as rmw noted, their effects in dropping large slag chunks can have very significant damage results.  Shotguns rarely drop the big, damaging chunks, but the shotgun noise commonly does drop some slag distant from the target area.  I would expect that the shock wave systems mentioned in the initial posting would likely have more in common with the explosives in terms of the risk of dropping large chunks.

I think his name was Hardy.  It just popped into my mind when I read the last post.  Am I right?  The shotguns were an on-line method, but the dynamite was off line (or mostly off line I think.)  While the goal was to set the charges into the larger clinkers, yes, often they didn't do what they were supposed to and pieces way larger than intended were dropped into the ash pit.

I will never forget when I was much younger sitting with a bunch of power plant mechanics in the kitchen during a break and they were discussing Mr Hardy's(?) work going on up above us and I asked what size clinker he was after.  Without hesitation one mechanic answered 'about the size of a school bus' to which another mechanic popped off 'that can't be right.  The first mechanic said well, what size is it to which the second guy replied; that clinker is about 35 ft long by about 10 feet wide by about 12-14 feet tall.....well, yes, I guess that is just about the size of a school bus isn't it?

rmw

rmw,

Hardy is the name that I remember, too.  Until I read your last posting, I couldn't remember it.

I worked at a small power plant that used pulse detonation on the backpass of the furnaces.  The system worked out very well for the plant.  They had to spend a lot less money on cleaning the backpass during maintenance outages.  And during my time at the plant the detonation system did not cause any problems with the boiler tubes.

I have also used shotguns and TNT to blow up slag off-line.  During online deslagging of superheat pendants in supercritical boilers, I would use a contractor that would insert a long water lance into the boiler.  The guy holding the lance was somewhat blind to where the slag was, especially if it was recessed into the pendants.  So me and one of his guys would be looking through the ports on the front of the boiler and would call back to the lance operator via radio to tell him where to move the lance.  It was high pressure water and you had to be careful not to let it spray on a tube for too long.  And you always had the risk of tripping a unit if a large piece of slag fell and upset the furnace draft, which the control room operator would change to give us more of a cushion.  I never had a unit trip on me but others have.

Knocking off large slag globs is not without its dangers.

during the 1990's ( about 1993) there was a case where operators at  a one  yr old large boiler in China had knocked off a large slag glob from the upper pendants of a tower type boiler. When it  hit the hopper , it broke loose a few waterwall feeders . Unfortunately, there were 23 workers in the hopper area, rodding out other slag accumulations from the clnker grinder. All 23 workers were killed from the steam/water mixture released from the failed feeders.