Leaf fall- Dry Ice Experimentation on the Northern Network

[Iskra]

It looks like a new way of cleaning the rails is being trialled. It could spell the end of traditional railhead treatment trains, which would be good as it saves paths, cancellations, emissions and costs if the regular DMU’s can cover the same work. Definitely one to watch:

Dry ice to help cut train delays caused by leaves on tracks

The new method of removing leaves from tracks will be trialled across northern England in the coming weeks.

www.bbc.co.uk

A new way of removing leaves more efficiently from railway lines to reduce delays is to be trialled across northern England.
The technique, developed by University of Sheffield engineers, involves blasting tracks with dry ice from a passenger train.
It will be trialled by operator Northern in the coming weeks.
Leaves cause a slippery layer on railway lines, leading to delays as trains must run at slower speeds.
Under the new method, pellets of dry ice are fired in a stream of air, making leaves frozen and brittle.
The dry ice then quickly turns back into gas, causing it to expand and destroy the leaves.

 

[GRALISTAIR]

As you say definitely one to watch - no chemicals used as such as the CO2 sublimes back to gas.

 

[2192]

As you say definitely want to watch - no chemicals used as such as the CO2 sublimes back to gas.

... and adds to the CO2 in the atmosphere, so contributing to global warming. Let's hope the quantities involved are minimal for the sake of the planet.

 

[edwin_m]

... and adds to the CO2 in the atmosphere, so contributing to global warming. Let's hope the quantities involved are minimal for the sake of the planet.

As with the CO2 used in the meat industry, it is probably the by-product of a process that would otherwise see it going into the atmosphere anyway.

 

[GRALISTAIR]

... and adds to the CO2 in the atmosphere, so contributing to global warming. Let's hope the quantities involved are minimal for the sake of the planet.

As with the CO2 used in the meat industry, it is probably the by-product of a process that would otherwise see it going into the atmosphere anyway.

If the CO2 is obtained from the fractionation of liquid air the only energy used is in the liquifaction of the air which needs to happen for other processes anyway such as oxygen production. So no real contribution to global warming.

 

[Iskra]

If the CO2 is obtained from the fractionation of liquid air the only energy used is in the liquifaction of the air which needs to happen for other processes anyway such as oxygen production. So no real contribution to global warming.

And it’s also saving the emissions of 37’s etc on RHTT’s that currently run in addition to the passenger service.

 

[Master Cutler]

The dry ice process is pretty efficient at removing degraded plastic from steel injection moulds, so it should be ideal for leaves on tracks.
The results, if the process is performed correctly, will leave the rails spotless.

 

[4COR]

If the CO2 is obtained from the fractionation of liquid air the only energy used is in the liquifaction of the air which needs to happen for other processes anyway such as oxygen production. So no real contribution to global warming.

It isn't - it's a very inefficient way of obtaining CO2 (hampered not only by the low percentage, but also by the fact that you must compress CO2 to get it into a liquid state as it sublimes/condenses directly from solid to gas and vice-versa at atmospheric pressure).

It's a waste product from various other processes, a major one being the production of ammonia, which relies on natural gas (CH4) to produce hydrogen for the Haber Process, which is why we're in the pickle at the moment with supply because of raw material cost...

 

[superkev]

They say everything is reinvented every 10years or so.
There was what sounds like a similar 1980s scheme from Derby RTC of firing ice at the rails. I believe it was abandoned as it didn't work too well and risked causing the railhead to delaminate.
K

 

[Master Cutler]

They say everything is reinvented every 10years or so.
There was what sounds like a similar 1980s scheme from Derby RTC of firing ice at the rails. I believe it was abandoned as it didn't work too well and risked causing the railhead to delaminate.
K

It could be a serious problem if the train stopped without cutting off the dry ice.
Localised rail freezing might create brittle cracks and subsequent rail failure.

 

[hwl]

The dry ice process is pretty efficient at removing degraded plastic from steel injection moulds, so it should be ideal for leaves on tracks.
The results, if the process is performed correctly, will leave the rails spotless.

They don't even need to be spotless just significantly better so a good chance in practice.

It is worth bearing in mind that CO2 is a useful solvent (unlike water) as regards leaf and plant products e.g. instant coffee manufacture and extraction of alpha acids from hops to use in more industrial beers (the hop extract has a much longer shelf life than hops) so that this may be partially chemical rather than just physical.

 

[GRALISTAIR]

It isn't - it's a very inefficient way of obtaining CO2 (hampered not only by the low percentage, but also by the fact that you must compress CO2 to get it into a liquid state as it sublimes/condenses directly from solid to gas and vice-versa at atmospheric pressure).

It's a waste product from various other processes, a major one being the production of ammonia, which relies on natural gas (CH4) to produce hydrogen for the Haber Process, which is why we're in the pickle at the moment with supply because of raw material cost...

But the nitrogen for the Haber process is obtained from liquefaction of air and then fractionation.

 

[Ediswan]

It is worth bearing in mind that CO2 is a useful solvent (unlike water) as regards leaf and plant products e.g. instant coffee manufacture and extraction of alpha acids from hops to use in more industrial beers (the hop extract has a much longer shelf life than hops) so that this may be partially chemical rather than just physical.

For that purpose, the CO2 is a supercritical fluid. This can only exist at pressures in excess of 1,000 psi. The original description says the CO2 is in the form of dry ice.

https://en.wikipedia.org/wiki/Supercritical_carbon_dioxide

 

[4COR]

But the nitrogen for the Haber process is obtained from liquefaction of air and then fractionation.

Yes, but the amount of CO2 obtained this way is small (and not enough for all the uses). Air is 78% N2, but only 0.04% CO2...

 

[GRALISTAIR]

Yes, but the amount of CO2 obtained this way is small (and not enough for all the uses). Air is 78% N2, but only 0.04% CO2...

and using dry ice to clean rails ain’t gonna raise it much - close to net zero imho

 

[AlastairFraser]

Yes, but the amount of CO2 obtained this way is small (and not enough for all the uses). Air is 78% N2, but only 0.04% CO2...

The amount of CO2 a Class 37 puts out a min will absolutely knock any dry ice based emission out the water.

 

[LNW-GW Joint]

Is this just one train running a limited test for the season, or the more general equipment of a fleet of trains?
Do we know which routes are being so treated?

 

[Master Cutler]

The only downside to using dry ice is the noise.
To fire the ice at the rail, the system uses compressed air which will sound like a steam locomotive blowing off cylinder condensation.
Not really what people want in urban areas in the middle of the night.

 

[4COR]

The amount of CO2 a Class 37 puts out a min will absolutely knock any dry ice based emission out the water.

I'm wasn't arguing that : I'm pointing out that liquefaction of air (as per post 5...) is not the way that CO2 is obtained for this or any purpose... This is drifting OT...

The technology is interesting - will be interested how it pans out.

 

[skyhigh]

Is this just one train running a limited test for the season, or the more general equipment of a fleet of trains?
Do we know which routes are being so treated?

It's a sole 153 being equipped to start off with. It'll run solo to start off with and may later enter service attached to a 158. If it does, the 153 will be locked out of passenger use. An operator will be on board the train at all times controlling the application.

 

[py_megapixel]

For comparison, what exactly to the current railhead treatment trains do to the rails?

 

[DarloRich]

For comparison, what exactly to the current railhead treatment trains do to the rails?

Blast them with water and lay sandite: https://www.networkrail.co.uk/runni...al-track-treatment-and-weather-support-fleet/

 

[Ediswan]

I followed the reference to Sheffield University
https://www.sheffield.ac.uk/news/nr...lutions-delays-dry-ice-how-to-remove-1.867967
and found this underlying technology
https://www.icetechtechnologies.com/about-dry-ice-blasting

No mention there about freezing the contaminant or expanding gas assisting its removal, just mechanical blasting.

The advantage claimed seems to be that cleaning a given length of track consumes a far smaller volume of dry ice than water.

 

[100andthirty]

I followed the reference to Sheffield University
https://www.sheffield.ac.uk/news/nr...lutions-delays-dry-ice-how-to-remove-1.867967
and found this underlying technology
https://www.icetechtechnologies.com/about-dry-ice-blasting

No mention there about freezing the contaminant or expanding gas assisting its removal, just mechanical blasting.

The advantage claimed seems to be that cleaning a given length of track consumes a far smaller volume of dry ice than water.

Those articles may not mention the benefit of the CO2 dry ice pellets turning to gas but the Professor in charge of the work certainly makes this point in his presentations.

 

[najaB]

To fire the ice at the rail, the system uses compressed air which will sound like a steam locomotive blowing off cylinder condensation.
Not really what people want in urban areas in the middle of the night.

I believe the intention is to run the system in passenger service, rather than overnight.

 

[Ediswan]

Those articles may not mention the benefit of the CO2 dry ice pellets turning to gas but the Professor in charge of the work certainly makes this point in his presentations.

The point at issue is not whether the dry ice turns into gas, but whether the resulting expansion plays any part in cleaning the rails. Is the presentation you mention publically avaialble ?

 

[yorksrob]

Whether it works or not, at least the railway will look atmospheric ! (Not in the Brunel sense).

 

[randyrippley]

This isn't new
I asked about it in a thread 3/4 years ago and someone else replied with a technical document explaining the process.
I couldn't find it using "search", but its in the forum somewhere

 

[markindurham]

The only downside to using dry ice is the noise.
To fire the ice at the rail, the system uses compressed air which will sound like a steam locomotive blowing off cylinder condensation.
Not really what people want in urban areas in the middle of the night.

I fancy it'll still be quieter than a 68 though!

 

[NoRoute]

Interesting idea but it did leave me wondering about the logistical arrangements for how you keep trains supplied with dry ice pellets, for example can a train carry a whole days supply?

Presumably train depots would need to start storing the stuff, but it needs to be kept at minus 80 celcius to remain frozen, so either needs some impressive freezing equipment, or frequent deliveries.