Water Treatment

[Chris Corney]

There was a proposal in the recent the newsletter suggesting using higher boiler pressures.
• I had a conversation with a work colleague who is an ex CEGB boiler specialist who thought that building a high pressure locomotive boiler would be feasible, but advised that the requirement for water quality is much more stringent as the pressure increases. In a power station, even the condensate is “polished” before it is fed back to the boiler.
• According to Nat Pres, some heritage railways are using Reverse Osmosis (RO) plants for the boiler feed water.
• I’ve heard of Porta water treatment, but don’t know anything about it.
• The Midland Railway/LMS had a water treatment plant at Garsdale water troughs on the S&C to clean up the acidic peaty stuff that came off the Pennines. I’m sure there must also have been others.
Other technologies are multistage distillation and freeze separation, but are probably uneconomic at the required scale.

That’s the sum total of my knowledge of water treatment.

I think that if you could guarantee a consistent supply of high quality water it might be feasible to operate boilers at higher pressures. This would be more trouble to organise than it’s worth on main line rail tours, but might be feasible on a self contained system. The L&B springs to mind if they are looking for new locomotives.

[Chris Newman]

Hi Chris – as mentioned in a recent email to you, I would have thought Porta’s water treatment system would be a more appropriate solution for locomotive use than systems requiring fixed plant. By my understanding, the advantages of Porta’s system are along the following lines:

• It requires no investment in fixed plant (beyond simple lab testing equipment);
• It requires no skills to implement – just some simple rules for the enginemen to follow;
• A locomotive carries its own treatment system with it, and can operate in areas with the hardest water supplies provided dosages are adjusted to keep the TDS in boiler water at a high level;
• It not only prevents scale build-up, but prevents corrosion and sludge formation and can extend the period between washouts to six months or more once confidence in it is gained.

The main problem with it is that the very high TDS levels it requires can result in heavy foam formation with the consequence of priming if a heavy-duty antifoam isn’t used.

Adaptations of Porta’s system are currently being used with success in the UK in 6024’s boiler and by Ian Screeton on the Kirklees Light Railway, and perhaps elsewhere. Of course, it’s long been used in Porta’s homeland, Argentina, most notably by the FCAF in Ushuaia where its success been long established.

A lot of hot air tends to cloud discussions about water treatment on heritage railways, many of which use systems that are claimed to be better than all others. It would therefore be interesting and potentially valuable if an independent study were to be undertaken that compared all the various water treatment options that are now available to the industry.

• This reply was modified 6 years, 7 months ago by Chris Newman.

[Chris Corney]

Hi Chris,

I’ve been reading about Porta’s water treatment, and to adds more additives to the boiler water to arrive at a mixture which is benign from a corrosion point of view. However it occurred to me that the boiling point of this mixture would be higher than for pure water, even though the steam produced would be pure and the saturation temperature equivalent to that produced by boiling pure water. I was wondering if there was any evidence that this increased boiling point reduced boiler efficiency, heat transfer or output.

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