Boiler Preheaters

Hi I was looking at some diagrams of Bullied Merchant navy cabs and I see that it had firebox preheating valve below the foot plate on the boiler back-head near the foundation ring.
Please could can any one enlighten me how this worked and would be practical for locos running on heritage railways to reduce thermal stress and operating costs on the boiler and firebox.
I did also read some time ago that one the Swiss rack railways built some new steam locos with small electric element to bring the water temperature up about 10 degrees and I would interested hear how that worked out or was just for frost protection.

 

The Swiss heaters where an external electrical immersion heater that then circulated hot water into the boiler. The principle reason was to pre steam a boiler automatically over night. The is could be switched on by phone is required.

 

DL Bradley notes, in "Locomotives of the Southern Railway", Vol. 2, the following about the first series Merchant Navies:

"On account of the unusually high working pressure, it was considered necessary to supply steam to the class while standing on shed and when lit up from cold after washout. To provide this, withdrawn Adams 4-4-0 No. 657 was converted to a stationary boiler in February 1941 and despatched to Salisbury. Later Adams 0-4-2 No. 646 took over this task and No. 657 was transferred to Exmouth Junction. Both locomotives had their pistons and valve rods removed, modified brick arches fitted, and steam hose connections on the dome. No. 657 was in use at Exmouth Junction on 11 October 1942, raising steam on 21C9 Shaw Savill following a boiler washout, but when Salisbury was visited on 2 July 1943, No. 646 was lying derelict and appeared not to have been steamed for many months. Experience had shown that their use was quite unnecessary."

Presumably the dates given were ones on which Bradley had visited those sheds, rather than a systematic listing.

No. 646 (the Adams Jubilee) had been nominally withdrawn in May 1939 with fractured frames, but evidently hung around long enough on the scrap line at Eastleigh to earn a temporary reprieve as stationary boiler.

No. 657 (the X6 4-4-0) was similarly withdrawn in September 1940, but again lasted long enough to be reprieved. After being found unnecessary as a stationary boiler, it was returned to Eastleigh in March 1944 and eventually broken up at Horley in November 1949. Incidentally - trivia alert - this was one of the locos that had a starring role in the Will Hay film "Oh! Mr. Porter".

Tom

 

UP Steam in USA, use either a hot water heater running water through the boiler, or steam on their boilers for a extended period of time, before the fire is lit, watched a video on it a while back, if I can find it on youtube, will post it.

Always thought it made sense, and wondered why it was never done by mainline operators in the UK, however, I am sure it costs a bucket load.

 

Found it :-



From around 3 minutes in....

 

The Swiss company DLM made these electric preheaters (may still do). I enquired about them 10 years ago as a thought for generating steam for the fireless loco 'Unique' that we have at the SKLR. They produced a 25kW and 50kW pre heater that could raise steam in the boiler to 10 Bar. It worked by extracting water from the boiler via a circulating pump, through a continuous flow heater and then back into the boiler. It is good for the boiler as it is heated from the water side uniformly. A thermostat could be adjusted to change the rate of heating. As I recall, the pre heater could be plugged into a telephone line via a modem and so the boiler could be heated remotely. The unit was in a box 1615 x 845 x 800 mm.

The price back then was about £15k but they did offer us a 2nd hand unit for £7k.

Lack of funds, labour and a spare 25kW supply made this WIBN dream stay as just that!

Nigel

 

https://www.martynbane.co.uk/modernsteam/dlm/dlmpreheat.htm

 

Thats actually a 25KW heater rather than a 25Kvolts power supply... looking at the photo and spec thats 40a 3ph - quite reasonable...

 

When the Swedish State Railways were electrified, grand scale in the 30-ties, there was the problem supplying enough stand by spare locomotives. Then electroboilers were installed at the main depots and an unknown numer of steam locomotives were fitted with extra insulation (e.g. insulated smoke boxes) and valves for connections. The electroboilers were mounted slightly lower than the locomotive boilers, so self circulation was sufficient. The stand by locomotives were kept at 6-8 bar (85-115 psi) pressure to assure a very short start up time.

 

One could take things a bit further.........

http://www.douglas-self.com/MUSEUM/LOCOLOCO/swisselec/swisselc.htm