Condensing apparatus on steam locomotives.

I was thinking while watching footage of the LU150 steam specials (of course, early underground engines had condensing gear, which sparked this thought in my head) could locos operating on the mainline, where water capacity is a major constraint, be kitted out with condensing apparatus to save water?

Bit of a whimsy, but could it be done? Would it be effective enough to make it worthwhile?

 

I think the significant problem (apart from all the extra plumbing) is that the feedwater would gradually heat up, eventually getting to near boiling point. At that point, the injectors (which rely on cold water to condense a jet of steam) no longer work. So you can't get water in.

If you look at most 19th century locos that had feedwater heating and / or condensing gear, they also had something other than injectors to get the water into the boiler: either steam driven donkey pumps (favoured by Beattie, amongst others: take a look at an early photo of a Beattie well tank) or crosshead driven feed pumps (favoured by Stroudley, amongst other). Donkey pumps have the advantage that you can run them even when the loco is stationary, but mechanically they are another system on the loco that needs building and maintaining, with moving parts that need lubricating, valves that need maintaining etc. Crosshead pumps tend to be simpler, but only work when moving - if you needed to put water in the boiler while stopped in a station, you needed to find a convenient siding to run up and down, or, in extremis, slip the loco on greased rails.

You then have two secondary problems. Firstly, the condensed steam is contaminated with oil, which either has to be separated out, or else enters the boiler as a contaminant and can cause problems such as excessive priming.

Secondly, the hot water can cause degradation of the paint on the water tanks (and could also scold a passenger inadvertantly leaning against the tank or tender). If you look at a Stroudley loco such as Terrier, they have an inner tank, surrounded by an outer sheet with a small gap between, so that the hot water in the proper tank is insulated from the outside of the loco. Billinton continued that pattern of tanks even though his engines didn't have condensing gear: call it conservative drawing office practice.

I suspect it would be a non-starter on the modern railway, certainly to retrofit to an existing loco.

Tom

 

There was also the Steam Heat Conservation Company experiment with the Southern Railway N class
The Holcroft-Anderson Recompression Locomotive.

 

There's a condenser tender from a BR52 in Neuenmarkt-Wirsberg germany.. just no loco to go with it

 

The other problem is that the steam, if directed into the tanks to condense, is not exhausting up the chimney to draw air through the fire in proportion to the working of the loco. So there had to be a compromise between using the condensing facility and switching to normal exhaust whenever possible to keep the fire going.

Besides LT engines, some LNER locos, particularly Class N2 0-6-2T, were fitted with condensing apparatus for use over the Metropolitan "Widened Lines" to work to Moorgate. These were in use up to the 1960s.

 

Interesting article about firing a 25 condenser here Firing a Condensing Steam Locomotive, 1991

 

As were the 97xx panniers and some ex LMS 3F tanks eg 47202. Ray.

 

Another problem with the Stroudley variant was that sharp stops caused oily mucky water to surge back through the condensing pipes into the smokebox, where it would be ejected through the chimney upon starting, to the detriment of the locomotive's paint finish and the clothes of any nearby passenger. A sharp clout with a heavy hammer by the driver on the end of the copper condensing pipes generally worked wonders on the future cleanliness of the engine and passengers, but didn't do much for the future ability to condense steam...

Tom

 

Also add the Fowler 2-6-2 tanks based at Cricklewood and Kentish Town and the Mersey Railway locos, such as Cecil Raikes.

 

One of the more interesting must have been the Dean Goods fitted with Pannier Tanks and Condensing gear for wartime service. Reading the piece about managing the condensing system linked above makes me thing that one set of tanks must have been reserved for the hot water.

 

Does the preserved LNER N2 still have working condensing gear, or is it cosmetic only these days? (I assume cosmetic, but would be nice to know).

Tom

 

It's cosmetic only. Other than the external pipes which are blanked off there is no condesing equipment fitted.

 

In Britain there was never any shortage of water so condensing was only ever used for locomotives on underground railways to try to limit the emission of smoke and steam. Therefore it was only on tank locomotives where there was no room for cooling and the water in the tanks did warm up, but not to an impossible extent as the underground sections, where condensing was next to compulsory, were not too long. In South Africa, condensing was used on tender locomotives to conserve water in desert regions. There was room for cooling equipment which, whilst not producing cold water, could keep its temperature down to workable limits.

As John Webb says, there is bound to be a deleterious impact on steaming. Whilst the opposite of condensing, the Franco-Crosti boilers remain a dreadful lesson in the perils of interfering with the proven way of working boilers.

 

The German BR 52 could cover several hundred miles between water stops... but also had thousands of screws to separate engine from Tender... (in order to turn them)...however they were kind of built to only go one way... East...

 

Was an awesome sight Ralph. Saw this run at the Kimberley Steam Festival in July 1991.
Will have to get round to getting the video off u-matic onto the pc and YouTube.
Regards, John.

 

The Metropolitan and the District Railways both had locomotives fitted with condensing apparatus, but I believe this was to do with reducing the volume of smoke and steam exhausted rather than saving water. I know that the Met. had a series of troughs into which the locomotives would dump their condensing water when they were being serviced. Where this waste water ended up is not recorded - presumably it found its way into the Thames! Secondly, the Met condensing locos had a lever for the driver to close or open the condensing feed - presumably when the came out on the Hammersmith branch they would shut the condensing off and run as a normal locomotive. This is still present on number 23 in the London Transport Museum.

Fenchurch also has dummy condensing pipes fitted.

 

The Mersey Railway locos also dumped water & re-filled their tanks at the end of each journey. Mersey no. 5 'Cecil Raikes' still has its condensing gear despite 50 years of industrial service.

Bob.

 

I guess that mode of working you get the primary advantage of reducing condensation in tunnels, but by trapping the condensate in a separate tank that is not part of the main water feed system, you avoid the disadvantages of lubricating oil carry over into the boiler.

Tom