On the New York episode of Strip the City on SBS, they talk about NY’s steam system which is said to be bigger than the next 9 steam systems combined. It seems sensible at first – a centralised method of making steam to use for heating etc throughout the city.

Apart from the risk associated with floods (water hammer, pipes exploding, etc, which is what this show is about), it seems like a huge waste of energy. Shirley it’d be better for each building to generate its own steam, or other heating method, than delivering 1.1×10 ¹⁰ kg of steam every year? What would the energy loss be if they made their own, instead of transporting it?

Dunno, but it looks great in movies like Batman.

I saw an for a steam cleaner the other day.

It referred to ‘heated steam’.

I thought ‘is there another kind?’.

yes, superheated steam.

;-)

captain_spalding said:

I saw an for a steam cleaner the other day.

It referred to ‘heated steam’.

I thought ‘is there another kind?’.

super heated steam

steam that’s been heated

The best way to convey energy using steam is to use super heated steam but I doubt that this system would use super heated steam on safety grounds alone.
If it’s saturated steam you’d need steam traps every 30 metres or so.
When I were lad, well laddish, I knew all this stuff, steam is a complex.

critter.

in a powerstation boiler water is flashed into steam, the steam then goes up into a steam drum and any liquid water removed, it then comes back for a return run back into the boiler where the steam is super heated

super heated steam should ideally have NO droplets in it or it destroys the turbine blades, the force that the steam hits the blades means that the droplets would be like stones hitting the blades.

the steam might be taken back through the boiler again, heated up and pushed through another turbine

the steam then enters the condenser. as the steam is cooled it creates a vacuum which draws steam in after it – a condenser is one of the ways they improved on the original steam engines

in a powerstation boiler water is flashed into steam, the steam then goes up into a steam drum and any liquid water removed, it then comes back for a return run back into the boiler where the steam is super heated

super heated steam should ideally have NO droplets in it or it destroys the turbine blades, the force that the steam hits the blades means that the droplets would be like stones hitting the blades.

the steam might be taken back through the boiler again, heated up and pushed through another turbine

the steam then enters the condenser. as the steam is cooled it creates a vacuum which draws steam in after it – a condenser is one of the ways they improved on the original steam engines

How long is a piece of string?

Large, centralised utilities are usually more efficient that lots of small ones.

I have images in my mind of boilers in the basement of buildings in American movies. Perhaps that isn’t New York but some other cities. Perhaps that might be a basis for comparison?

the way the steam normally hits the turbine is so that it gets split 180 deg

the idea is that if it hit the face of just one turbine it would as you could imagine, actually push very hard onto the turbine and would want to push it backwards, you’d need some massive bearing to do this

by splitting the steam and get it to hit two turbines and the two turbines push against each other rather than against a bearing taking all the force.

>If it’s saturated steam you’d need steam traps every 30 metres or so

I suspect that it is steam traps that are responsible for the steam that wafts up from gratings around NY city. I remember those from a chemical plant I worked in once. They used to choof out steam and condensate periodically.

stop calling me surly

the steam isn’t used just for heating. it is used for cooling, cleaning, disinfecting, power and a few others.

one reason it might be cheaper to simply pipe steam is that the end user would need to maintain a huge system to create steam or other

one major producer of steam would be more efficient in producing power

electricity might be very expensive, the major steam provider must be cheaper than electricity

the energy being used to simply heat something up is probably a hell of a lot cheaper and efficient that heating steam to superheated steam then extracting the kinetic energy from it – powerstations pour vast amount of heat from their cooling towers – wasted heat

a steam system means that practically all the energy used is absorbed by the system with some losses where insulation has failed

Numbers, people, I like numbers.

What are the losses? (Within half an order of magnitude will do.) Compare centralised steam production with individual building steam production.

What about other methods of producing heat (let’s keep it simple and assume that’s all they use it for)?

from alex.

Alex: do the math.

ChrispenEvan said:

Numbers, people, I like numbers.

What are the losses? (Within half an order of magnitude will do.) Compare centralised steam production with individual building steam production.

What about other methods of producing heat (let’s keep it simple and assume that’s all they use it for)?

from alex.

Ta…

by reason alone a thought experiment

why wouldn’t they have a separate petrol motor powering each wheel rather than one engine turning all wheels on a car?

if you had a hot water system in your house, why wouldn’t you have a separate system for each hot water tap?

wookiemeister said:

if you had a hot water system in your house, why wouldn’t you have a separate system for each hot water tap?

We had two hot water systems in our old house.

OCDC said:

wookiemeister said:

if you had a hot water system in your house, why wouldn’t you have a separate system for each hot water tap?

We had two hot water systems in our old house.

it would have got expensive right?

grabbing on to the other end of the stick

they are telling people to dump their bar fridge and just use one fridge to save money.

i guess it depends on the locations the hot water is needed. with the new instantaneous it would work out more economical to have two than long runs of piping.

Surely it all depends on the insulation around the pipes?

Numbers? You want numbers?

Read this. Well figure 1 and the associated text as a minimum. It isn’t easy to come up with simple numbers.

http://www.poyrycapital.com/assets/files/downloads/Technical%20Analysis%20&%20Costing%20of%20DH%20networks%200904.pdf

Sibeen will vouch for these people. ;)

Then you’d have twice the cost of purchase and install

And maintenance

I don’t know how they produce the steam in NY, but if it is a combined heat and power system this can be hugely more efficient than power generation + separate local heat generation.

The problem with electricity production is that 1/3 of the energy in the fuel is converted into electricity and the other 2/3 is just thrown away.

That’s an opportunity.

The Rev Dodgson said:

I don’t know how they produce the steam in NY, but if it is a combined heat and power system this can be hugely more efficient than power generation + separate local heat generation.

The problem with electricity production is that 1/3 of the energy in the fuel is converted into electricity and the other 2/3 is just thrown away.

That’s an opportunity.

I think what we need is a tax on the use of resources, and a tax on emissions from burning fuels, to force people into adopting the many opportunities for improvements in efficiency, rather than just following the easiest (and at the moment cheapest) route of literally throwing 2/3 of the available resource away.

It seems that NY does use co-generation:

New York Steam

And I’ll never say a word against Allan Jones again:

Allan Jones, now in Sydney

http://en.wikipedia.org/wiki/2007_New_York_City_steam_explosion

“The official report released by the utility company on December 27, 2007, cited a combination of these factors, accepting responsibility for deficient repair work done by a contractor that ultimately led to the rupture. The report said that excess sealant, previously used to repair a leaking joint, migrated to two steam trap valves used to drain excess condensed water, clogging them. Then when heavy rains on the day of the event cooled the pipe causing excess condensate to collect in the steam pipe, the valves could not remove it. As a precaution, the utility replaced more than 1600 similar valves throughout the system, but did not find any other clogs”

http://en.wikipedia.org/wiki/New_York_City_steam_system

>>but did not find any other clogs

Wasn’t New York originally called New Amsterdam?

Since we’re doing the free association thing, clogs and all.

http://en.wikipedia.org/wiki/New_Amsterdam

New Amsterdam (Dutch: Nieuw-Amsterdam) was a 17th-century Dutch settlement established at the southern tip of Manhattan Island which served as the seat of the colonial government in the New Netherland territory. It was renamed New York in 1665 in honor of the then Duke of York (later James II of England) after English forces seized control of Manhattan Island, along with the rest of the Dutch colony.

The Rev Dodgson said:

It seems that NY does use co-generation:

Thanks Rev.