Tank Containers on the Tesco Inverness Train

[plugwash]

I'm no gas tank design expert, but If the valve is ejecting two phase flow then it seems to me that the valve is badly designed. I'd think you would want to design the valve to only eject gas for two reasons, firstly because liquid is far more problematic than gas to release and secondly because boiling inside the tank will cool the remaining liquid.

 

[Meerkat]

The gas comes from the isle of grain by road to Daventry, the long way around the M25 due to being banned from the Dartford tunnel. They travel north using S44/S45. When they get to Mossend they get transshipped onto the Inverness Tesco train, then roaded from there to Wick and Shetland.

Do the Oban and Cambeltown ones also get the train, but put on road at Mossend??

 

[xotGD]

I'm no gas tank design expert, but If the valve is ejecting two phase flow then it seems to me that the valve is badly designed. I'd think you would want to design the valve to only eject gas for two reasons, firstly because liquid is far more problematic than gas to release and secondly because boiling inside the tank will cool the remaining liquid.

Joule Thomson cooling of the cryogenic vapour just above its dew point temperature as it expands results in reliquefaction across the relief valve.

Even more entertaining with relief of high pressure CO2 as it then crosses the phase boundary into the solid region and you get CO2 'snow'. And potentially block the relief valve with a plug of solid CO2.

 

[furnessvale]

Daventry is the nearest rail container terminal to Grain that isn't itself another port (London Gateway is definitely closer, not sure of Harwich and Felixstowe are)

Presumably, the Russell train from Barking to Daventry no longer runs? Given that the onward movement from Daventry to Scotland is also Russell, it would have made sense to start these boxes from Barking.

At least these 1-2 a day are a start to rebuilding a service from Barking.

 

[stuving]

There is a slow heat leak into the LNG tanks which results in the pressure increasing as the temperature rises. If you left one sat around for too long it would reach the point where the pressure relief valve would lift, ejecting cryogenic 2-phase flow of methane into the air. A situation to be avoided!

It is a slow leak too. The 40' ISO ones used by SGN are supplied by Wessington, and have a specified holding time of 80 days. That's from loading at 0 bar to the working maximum pressure of 10 bar; above that in quite big steps come the safety valve setting, the design maximum pressure, and the proof test pressure.

During transit there is a strict procedure to follow, monitoring the pressure rise (as well as never leaving it unattended in public etc.) If the pressure does reach the working limit, it has to be taken somewhere safe and some gas discharged. Rail transport should fit that regime rather better than long distance by road, I think.

 

[zwk500]

Presumably, the Russell train from Barking to Daventry no longer runs? Given that the onward movement from Daventry to Scotland is also Russell, it would have made sense to start these boxes from Barking.

At least these 1-2 a day are a start to rebuilding a service from Barking.

As the tanks are banned from the Dartford Tunnel, you would have to do 95% of the M25 to get them to Barking, which probably isn't much off the journey time to Daventry. I've no idea what freight flows are running atm, I've been out of the loop a while.

 

[furnessvale]

As the tanks are banned from the Dartford Tunnel, you would have to do 95% of the M25 to get them to Barking, which probably isn't much off the journey time to Daventry. I've no idea what freight flows are running atm, I've been out of the loop a while.

Yes, that makes sense. Are empty tanks also banned? If not, the round trip could balance out a bit.

 

[xotGD]

Yes, that makes sense. Are empty tanks also banned? If not, the round trip could balance out a bit.

The return empties go over the bridge, not through the tunnel.

 

[zwk500]

Yes, that makes sense. Are empty tanks also banned? If not, the round trip could balance out a bit.

Simpler to send it to Daventry both times, isn't it? Only thing that would make more sense is if the tanks were shipped to London Gateway or Tilbury rather than Grain, then they could be loaded onto the train directly as those routes are cleared for W9+
I know NR was looking at clearing a Wembley-Dollands Moor route to W9+ specifically for S45 swapbodies, but it was quite pricey and wouldn't have helped Grain much.

 

[furnessvale]

The return empties go over the bridge, not through the tunnel.

Doh! Of course they do!

 

[paul1609]

Simpler to send it to Daventry both times, isn't it? Only thing that would make more sense is if the tanks were shipped to London Gateway or Tilbury rather than Grain, then they could be loaded onto the train directly as those routes are cleared for W9+
I know NR was looking at clearing a Wembley-Dollands Moor route to W9+ specifically for S45 swapbodies, but it was quite pricey and wouldn't have helped Grain much.

I'd imagine the tanks are filled at the deliquidification plant at Grain, the only alternatives in the UK are near Milford Haven.

 

[zwk500]

I'd imagine the tanks are filled at the deliquidification plant at Grain, the only alternatives in the UK are near Milford Haven.

Could barge them across the Thames, I suppose .

More seriously, if this is the case then yes Daventry is by far the better option. Would the Lower Thames Crossing (if that is still on the cards) be similarly restricted to pressurised loads?

 

[ABB125]

Could barge them across the Thames, I suppose .

More seriously, if this is the case then yes Daventry is by far the better option. Would the Lower Thames Crossing (if that is still on the cards) be similarly restricted to pressurised loads?

I believe the lower Thames crossing is designed to avoid any restrictions as much as possible. Whether LNG is included I'm not sure. It'll certainly have a lot fewer restrictions than Dartford though!

 

[stuving]

Do the Oban and Cambeltown ones also get the train, but put on road at Mossend??

Yes ... or almost. When this LNG by rail started in 2018, those two were served by road from Coatbridge. Was there a switch from using Coatbridge to Mossend? Or do they use both? Maybe - obviously SGN are just looking for convenient multimodal trains to hitch a ride with. DRS should at least be able to handle the safety issues - they do all the nuclear waste (and indeed are owned by the Nuclear Decommissioning Agency, so ultimately by the government).

DRS listed the following trains they run for Tesco in January 2022:

• Daventry to Mossend
• Mossend to Teesport
• Daventry to Tilbury x 2
• Tilbury to Coatbridge
• Daventry to Wentloog
• Daventry to Teesport via Doncaster
• Mossend to Inverness

Tilbury to Coatbridge takes refrigerated containers.

 

[VideozVideoz]

For those wondering, the Natural Gas SIUs in Scotland are Campbeltown, Oban, Wick and Thurso. There is also apparently one in Wales.

- In response, I believe Llanwrtyd Wells is the welsh location for the independent gas network. *Wouldn’t let me quote original post*

 

[allaction]

Ah. Liquified gas coming from Pembrokeshire to the north of Scotland, while my gas at home in Pembrokeshire comes from, um, off the coast of north Scotland. Probably.

It all makes perfect sense.

 

[krus_aragon]

Ah. Liquified gas coming from Pembrokeshire to the north of Scotland, while my gas at home in Pembrokeshire comes from, um, off the coast of north Scotland. Probably.

It all makes perfect sense.

As much sense as seeing fully loaded coal trains running in both directions between Cardiff and Newport, a century (or so) ago.

 

[xotGD]

deliquidification

Great word! Alternatively, regasification or vaporisation, which tend to be used interchangeably.

my gas at home in Pembrokeshire comes from, um, off the coast of north Scotland

Or Qatar, if it is imported LNG, which is what fills the pipes in Pembrokeshire.

 

[Magdalia]

Often such isolated gas systems are hangovers from the days when towns had independent gas works, supplied with coal by rail. just circulated in a local area. They actually pre-dated electricity networks, and were used for gas lighting etc as well as domestic supply. There was no country-wide grid, which only arrived with "North Sea Gas" in the 1970s.

That's not correct. The National Gas Grid started in the mid 1960s, before the discovery of gas in the North Sea. It started with a pipeline up the middle of England to distribute gas imported as LNG from Algeria via a terminal at Canvey Island, which opened in 1964.

 

[InOban]

The first North Sea gas arrived in 1967. The switchover from coal gas began the following year and was completed in 8 years.
i assume that the earlier imports through Canvey Island were used in industry?

 

[Magdalia]

The first North Sea gas arrived in 1967. The switchover from coal gas began the following year and was completed in 8 years.
i assume that the earlier imports through Canvey Island were used in industry?

I'm not an expert, but my understanding is that there was a process at the Canvey Island terminal that enabled the imported LNG to be mixed with the gas produced in the local gas works, mainly Romford, Bromley by Bow and Beckton.

Canvey Island was the first place to be switched over to Natural Gas.

 

[airantraigh]

For those wondering, the Natural Gas SIUs in Scotland are Campbeltown, Oban, Wick and Thurso. There is also apparently one in Wales.

- In response, I believe Llanwrtyd Wells is the welsh location for the independent gas network. *Wouldn’t let me quote original post*

I thought Stornoway also had gas? not sure how their system is set up but i doubt its connected to the main network , i could be way off though

 

[simonw]

I thought Stornoway also had gas? not sure how their system is set up but i doubt its connected to the main network , i could be way off though

Stornaway has a piped Liquid petroleum gas supply.

 

[stuving]

That SGN plan I linked to before (post #16) explains the situation of Stornoway. That SIU uses LPG, not LNG, and can store 542 tonnes of it - enough for more than three months. I presume that is why LPG is preferred; it is at liquid ambient temperature, where that much LNG would need big insulated tanks and a cryocooler. LPG can be sourced within Scotland, and is carried by road tanker via the ferry. Up to 2018 they used to hire a special LPG tanker ship, but for the quantities involved the extra costs and installations needed for that were expensive.

 

[VideozVideoz]

I thought Stornoway also had gas? not sure how their system is set up but i doubt its connected to the main network , i could be way off though

Yes but it’s piped propane as Simon has said above. I was just responding to the bit about there also being a piped propane supply in wales and that’s llanwrtyd Wells

 

[airantraigh]

Yes but it’s piped propane as Simon has said above. I was just responding to the bit about there also being a piped propane supply in wales and that’s llanwrtyd Wells

Thank you

That SGN plan I linked to before (post #16) explains the situation of Stornoway. That SIU uses LPG, not LNG, and can store 542 tonnes of it - enough for more than three months. I presume that is why LPG is preferred; it is at liquid ambient temperature, where that much LNG would need big insulated tanks and a cryocooler. LPG can be sourced within Scotland, and is carried by road tanker via the ferry. Up to 2018 they used to hire a special LPG tanker ship, but for the quantities involved the extra costs and installations needed for that were expensive.

Sorry had been slightly hasty in my read of the thread. Thank you! That makes more sense