Elesco Tangential Steam Dryer

PMC · **Joined:** Sat Oct 17, 2015 5:55 pm **Posts:** 2876

Nashville Steam, the group restoring NC&StL 576, posted a diagram and photo of something called an Elesco Tangential Steam Dryer on their facebook page (https://www.facebook.com/NashvilleSteam/). It says that this device was used to dry steam before sending it to the superheater tubes, on a locomotive so equipped. What I am curious about is two things: was this device common and useful, and would this device be useful on a non-superheated locomotive? My guess is it post-dates the introduction of superheaters ans so likely wasn't ever used on a non-superheated locomotive. I really am out of my pay grade here though so thought I would ask the board.

Baldwin feeder · **Posted:** Tue Feb 21, 2017 7:35 pm

I had not seen one of these before but it looks very interesting. It appears to me that it would not work well with a dome throttle which would eliminate its use with saturated steam locomotives and limit the use to superheated steam with front end throttles.

EWrice · **Joined:** Wed Jan 15, 2014 9:14 am **Posts:** 367

This thing looks exactly like a centrifugal pre cleaner for an air intake system on a piece of equipment. The only way I could see this working is at heavier throttle where the steam velocity through this unit is higher. Interesting concept.

tom moungovan · **Posted:** Tue Feb 21, 2017 9:35 pm

Baldwin feeder wrote:

I had not seen one of these before but it looks very interesting. It appears to me that it would not work well with a dome throttle which would eliminate its use with saturated steam locomotives and limit the use to superheated steam with front end throttles.

This makes some sense, a number of the postwar ng Baldwin 2-8-2 built for service in Guatemala had these devices when delivered. Engines 175-206 were indeed, equipped with front-end throttles and had superheat.

The device was also known as a "foam breaker".

I'm going to have to correct the above. I believe that I was mistaken and what I was thinking of on the Guatemalan locomotives was a Wilson Steam Separator. For whatever reason, most, if not all of these devices were removed and I cannot remember any at all when I traveled there in the 1970's.

Overmod · **Joined:** Thu May 24, 2012 1:37 pm **Posts:** 2492

There was an assumption in the initial design of this device that the centrifugally-separated carryover would be drained from the tray back into the boiler water.

It would appear that some of the folks at the Locomotive Superheater Company didn't quite recognize how the water under the dry pipe actually behaves in a large working steam locomotive -- a common result is that on some locomotives the drain from the separator is piped outside the boiler, and no attempt appears to be made to recover the separated water, either back into the feedwater or for some other purpose.

576 was notable for having extreme change in the working water level (there was a plate in the cab showing correct indicated level on 2% grade) which may have affected the level under the dome. It would be interesting to see what the specific arrangements for the dryer's drain are.

joe6167 · **Posted:** Wed Feb 22, 2017 4:33 am

From a pamphlet I have and an article I wrote...

Quote:

Elesco Tangential Steam Dryer

"The carrying over of moisture with the steam into the locomotive superheater units causes a substantial and needless loss in the efficiency of the locomotive. For each one per cent of moisture that is carried over into the superheater with the steam, there is a drop of about 17 degrees in superheat. In large locomotives the carryover of moisture into the superheater may be as high as five to ten per cent resulting in the lowering of the superheat correspondingly. The carrying over of moisture into the superheater will also cause internal encrustation of the superheater units, with a resultant decrease in temperature, an increase in pressure drop, and a shortening of the life of the superheater.

The space in the steam dome, which was previously occupied by the throttle before the introduction of the smokebox throttle, is suited for the application of a steam dryer. The Elesco tangential steam dryer, as shown below, is suitable for application in the steam domes of locomotives equipped with either the types A, H-A, or E designs of superheaters. The steam going to the superheater is dried by separation, and the moisture is returned to the boiler. It is very efficient under normal operating conditions, and will effectively handle as much as 20 percent of moisture in the steam at an efficiency of better than 80 per cent.

The Elesco Tangential Steam Dryer is located at the highest point in the dome. Its inlet is unobstructed and non-cloggable and it has no moving parts. It functions with a minimum of pressure drop, is easy to install, is low in first cost and maintenance cost is negligible."

The CNR would have applied the Tangential Steam Dryer to larger power equipped with a front end throttle. Most Northern's for example were either built with it, or had it applied after the fact. Records show that many engines had the Tangential Steam Dryer removed. One possible motive for this is that the Tangential Steam Dryer obstructs access into the boiler through the steam dome for the purposes of maintenance and inspection.

Lastly, the price tag on the Tangential Steam Dryer was about $209.00 CDN in the 1940's.

Seems it was aimed at reducing the amount of moisture entering the superheater units, and in all likelihood not intended for saturated engines.

CNR 6167 was built with one in 1940, and my records say it was removed in 1944.

Overmod · **Joined:** Thu May 24, 2012 1:37 pm **Posts:** 2492

I think there would be substantial value to the device on a saturated engine, particularly since a larger mass flow of steam would be necessary to do work comparable to the same size locomotive with adequate superheat. The 'catch', as noted, is that the device is located precisely where a typical dome throttle is mounted, for much the same operational reason (keeping the device intake as high above water/steam interface and foam as possible) and so you'd want some form of front-end throttle to make the idea work.

I distinctly remember a thread on one of these forums that discussed this device, and the routing of its separated-water drain outside the boiler shell. The specific locomotive was one of the preserved Canadian locomotives -- could it be 6060? One conclusion was that it was a wise idea to provide positive drainage from the separator tray, in part because some of any 'backup' and particularly any unbroken foam there could be re-aerated into the steam flow fairly readily at high mass flow.

Kimball · **Joined:** Fri Jan 10, 2014 5:00 pm **Posts:** 71

How could you allow the water to run outside the boiler without creating a leak in the boiler?

PMC · **Joined:** Sat Oct 17, 2015 5:55 pm **Posts:** 2876

Thanks for the very informative replies. I found out about the steam dryer right after re-reading the C&NW 1385 thread, also very informative, where there was speculation about whether new-build boilers should be superheated or not. What I took from that discussion is that superheating definitely improves performance but is more expensive, both in initial cost as well as additional maintenance due to the mechanical complexity. I think the consensus is, however, that unless it is forever to be a park engine pulling a few cars on a level grade, that you want the supeheater for its better performance.

Among the other problems discussed with a saturated engine is the additional water use, and that they tend to spray the rails in front of the drivers (as well as patrons at station stops) with condensation. So, what I am wondering is, if you were to build a park engine without superheater, would this device help prevent the spray, and if so, would it be worth the additional complexity? I wonder if a test was ever performed to see how much condensation it actually removes per hour, and thus the potential water savings, etc.

I apologize if any of these questions are naive, just sort of speculating here.

Dave · **Posted:** Wed Feb 22, 2017 5:32 pm

If you run infrequent short trips with a lot of sitting still, superheaters may not pay. If you run longer trips - half an hour or more, hauling some real tonnage - the added efficiency might be worth the extra cost of not only the superheater itself, but also the other lubricating and other retrofits necessary to make use of the hotter steam. Slide valves don't generally like superheated steam either.......

I think if you don't have good water treatment programs and carry high water close to the entrance to the dome, some drier like this could work to some extent in saturated service, but again, you'd have to find someplace for the throttle to go. It might be better to work on other ways to prevent water and foam intrusion instead.

Overmod · **Joined:** Thu May 24, 2012 1:37 pm **Posts:** 2492

Quote:

"How could you allow the water to run outside the boiler without creating a leak in the boiler?"

One approach would be to use a check valve and trap, as is done with condensate draining in steam lines without venting steam.

The line from 'inside to outside' of course goes through the boiler shell just like the feedwater line in reverse, so there isn't any 'leak' around the penetration.

DRS.GPBensman · **Posted:** Tue Feb 28, 2017 2:35 pm

The drain line returns the water to the boiler, it does not evacuate it from the boiler out to the ground. The "King", B&LE #643 also had this device in it's steam dome.
Looking at the photo of the NC&St.L #576 - that copper gasket looks like it only had one tightening of the dome lid onto it. Also, very nice looking dome studs. This engine continues to show itself as a well maintained locomotive.

Overmod · **Joined:** Thu May 24, 2012 1:37 pm **Posts:** 2492

Quote:

"The drain line returns the water to the boiler, it does not evacuate it from the boiler out to the ground."

It was designed that way, and some of the contemporary drawings show it that way, but at least some North American prototypes found that the device would not drain with adequate speed or volume under conditions of high steam demand. This may have been due to a lack of knowledge of the physical characteristics of boiler water at the steam/water interface under the dome (not really dissimilar from the lack of knowledge shown by the Nathan drop-plug people illustrating how they thought water over the crown sheet of a large American boiler under steam behaves).

I, too, thought it was extreme to vent the water completely outside the boiler rather than change the internal drain size and routing; it was clear to me, however, that so extreme a thing wouldn't have been done without need, and subsequent recognition of the problems.

Stationary Engineer · **Joined:** Thu Dec 12, 2013 1:26 pm **Posts:** 258

By draining it outside the boiler, it would help reduce TDS. Especially if the boiler was foaming.

Tom

joe6167 · **Posted:** Tue Feb 28, 2017 10:26 pm

Heh, that's where NALCO Continuous Blowdown comes into play. See Here:

viewtopic.php?f=1&t=40412