The end of an era - or at least a gas holder

[whole diary]

[BBM]

I've just discovered a Twitter account for the gas holder! 

https://twitter.com/TowerGas

[stuving]

Some more of them falcons is at it ... this time in Wales. From NR^» (Network Rail - home page):

Best laid plans: Network Rail amends bridge refurbishment work after protected birds found nesting in tower
April 20, 2021


Network Rail has had to make changes to planned refurbishment works on the Grade II listed Britannia Bridge, in North Wales, after a pair of peregrine falcons were found to be calling it home.

The rare and protected birds were spotted, by a member of the public, flying back and forth to the top of the middle tower of the bridge – which links Anglesey and the mainland of Wales across the Menai Strait.

With restoration works planned on all three towers, Network Rail quickly teamed up with Ecological Consultants, Whitcher Wildlife Ltd, to get advice on how to best protect the falcons.

“After a few visits to the bridge, it soon became clear that a solitary peregrine falcon was roosting, preening and hunting from the central tower”, James Campbell, Ecological Consultant at Whitcher Wildlife Ltd said.

“It was displaying the typical field signs of an adult male, defending the nesting site and tending to feed the female peregrine falcon on the nest.

“Falcons are usually found nesting in high-up places, like cliff tops or tall buildings, but this is the first time I have been called out to monitor these magnificent and rare birds nesting in the tower of a bridge. 

“We are working closely with Network Rail to continue to monitor the birds over the next few months, with work on the central tower now paused until the young peregrines have fledged the nest, later in the year”

Following advice from the ecologist and Natural Resources Wales, the restoration work will continue on Anglesey and Caernarfon towers with scaffolding now being erected in preparation for the main work to begin next month.

[CyclingSid]

There is a planned exhibition (subject to the various current problems) at the Riverside Museum part of Reading Museum in September of artworks related to the gas holder

I believe the dates of the exhibition are 10th-26th Sept 2021. 10:00 - 18:00 daily at The Turbine House, Riverside Museum, Reading, RG1 3EQ

[CyclingSid]

Dates for the exhibition are confirmed
https://www.readingmuseum.org.uk/whats-on/heritage-open-days-exhibition-last-gasometer-and-reading%E2%80%99s-changing-skyline
Bar and restaurant (Bel & Dragon) adjacent https://belandthedragon-reading.co.uk/

[jamestheredengine]

Dates for the exhibition are confirmed
https://www.readingmuseum.org.uk/whats-on/heritage-open-days-exhibition-last-gasometer-and-reading%E2%80%99s-changing-skyline
Bar and restaurant (Bel & Dragon) adjacent https://belandthedragon-reading.co.uk/

Unusual name for the bar/restaurant – named after a book of the Apocrypha.

[CyclingSid]

... and the demolition begins (or the preparation for it) https://www.bbc.co.uk/news/uk-england-berkshire-58543251

[CyclingSid]

Video report from ITV News Meridian's Mel Bloor

https://www.itv.com/news/meridian/2021-09-21/dismantling-of-readings-final-gas-holder-begins
As one of the contributors says, topographical art was common about the time the gasometer was built, but relatively rare nowadays.
Not sure how long this is available for.

[broadgage]

Imagine the outrage if the building of similar structures was proposed today.
And the shock at discovering that they are to be filled with gas that is both toxic AND flammable. Near CHILDREN !

And the wicked fat cat persons building the evil monstrosities are then going to sell the gas at a PROFIT, charging even the poor.
Nearly as bad as the smoke breathing, spark snorting iron monsters that are roaming the countryside at will, destroying crops by fire, tumbling down the hovels of the poor, preventing hens from laying, causing horses to become extinct, and other disasters to tedious to list.
And what if a spark from such a monster were to land upon a giant gas holder ? Disaster of almost unimaginable proportions would follow.
Truly the apocalypse is upon us.

[CyclingSid]

Better not ask about the gas leak they are trying to repair on the Bath Road bridge in Reading. Did wonder if a steam locomotive going underneath would be an added hazard.

[paul7575]

Someone posted about the apparent dangers of gas holders to modern thinking, I was wondering if records show how many were bombed intentionally or accidentally during WW2, and what the resulting damage was?

Secondly, recent news about a general lack of storage has sometimes been illustrated with images of traditional gas holders, but were they really ever providing medium term storage, or did they simply act as accumulators to deal with demand fluctuation over the normal 24 hour peaks and troughs?

[stuving]

Someone posted about the apparent dangers of gas holders to modern thinking, I was wondering if records show how many were bombed intentionally or accidentally during WW2, and what the resulting damage was?

Secondly, recent news about a general lack of storage has sometimes been illustrated with images of traditional gas holders, but were they really ever providing medium term storage, or did they simply act as accumulators to deal with demand fluctuation over the normal 24 hour peaks and troughs?

I think it's best to see them as pressure stabilisers. It would never be feasible to exactly match gas production from retorts to demand, and they are designed to keep the pressure constant. Their volume I suspect was dictated more by coping with variations in supply than demand. In the early days the one retort might only be manned during the day, and later you always needed to shut them down to clean them out, plus quite frequent unplanned outages. And later on production was moved out of town too and pumping stations had fixed capacity (when working). Later on, with north sea gas, control of pumping was good enough to exploit the capacity of the bigger long-distance pipes at higher pressure to do the same job.

[stuving]

I think it's best to see them as pressure stabilisers. It would never be feasible to exactly match gas production from retorts to demand, and they are designed to keep the pressure constant.

That can't be quite true, of course, as each lift adds weight to the cap and increases the pressure. But all the words I've found dismiss that and say the cap is weighted. What we need is numbers!

The only numbers I can find are in "The Design of gas Holders", C S Spillsbury (1911). That includes as worked examples a single-lift and a four-lift design, but omits the pressure calculation from the latter - frustratingly. Elsewhere he cites pressures of 4" plus 2" per lift (water gauge), which doesn't look very constant to me!

So what stabilised the supply pressure? The governor, that's what. We'd now call that a regulator, like the one on the top of your gas meter (only bigger). So provided the holder pressure was high enough, it would be regulated down to a constant level into the supply network.

If you want a load more detailed detail about gas works' workings, I suggest you look at this combined set of four "Gas profiles". They were done by the technical director of Parsons Brinckerhoff, oddly enough, though it looks like this is a personal interest of his! Even then, he hardly mentions supply and its pressure management.

One general problem throughout this "how did it work" subject is that gas engineering advanced a lot from the early (pre-Victorian) systems to the post-1920 ones we are used to seeing awaiting demolition. And during that later period the technology keeps changing and ended up looking much like current systems.

[broadgage]

The gas in a gas holder was at a modest pressure, but this pressure varied a lot and was well in excess of the pressure supplied to consumers.
Governers or pressure regulating valves were used to maintain a constant pressure to consumers.

Gas holders were used to balance supply and demand. Large gas works worked 24/7 and the rate of production could be adjusted within certain limits, but a gas holder was still required to handle short term differences between production and demand.
Smaller gas works might only be worked for one shift per day, with demand between production shifts being met from the gas holder.
Very small gas works produced as needed, as little as once a week in summer for very small works.

The quality of the gas also varied during the production cycle, and the mixing in the gas holder gave a more consistent product to the consumer. Freshly made gas was hot and contained a lot of moisture. In the gas holder it cooled and excess water could condense out and be removed.