How is a steam engine's boiler water topped up without........ (1 Viewer)

[Spriddler]

losing the steam pressure?
Surely the boiler has to be 'opened' to replenish the water exhausted as steam but wouldn't that let all the steam pressure out of the boiler and cause a long delay whilst the fresh cold water heated up and pressure was restored?

Secondly. A higher than atmospheric pressure raises the boiling point of water so does that mean that the pressurised boiler water has to be raised to a greater temperature than 100degC before generating steam?

Thirdly. At what pressure (lbs/sq. in.) does the boiler operate?

I've trawled no end of graphics and YouTube videos on t' web without finding answers.

John Barrett ?

 

[funflair]

The water is replenished under pressure, this seems to answer a couple of your questions, https://www.steamlocomotive.com/appliances/injector.php

 

[funflair]

Actually a very clever bit of kit if you follow the link to "Locomotive Injectors" I have learnt something today so thanks for asking Spriddler

I have a lawn to scarify but there is some good reading there for another day.

^{_{Subscribers  do not see these advertisements}}

 

[bigwood]

As said an injector is one way of topping up a boiler whilst in steam. This applies to full size boilers but model boilers could use a mechanical pump instead. The water will be fed into the boiler via a one way valve known as a clack valve.
The second question sort of makes sense to me but let the more expert people answer that one.
A boiler has a safety valve fitted that is set to regulate the pressure in the boiler via a spring loaded valve.
I hope this helps but John will correct me if I am a bit adrift with my answers.

 

[bigwood]

Further to my last. If you are thinking of small boilers like the Mamod style they can’t be topped up once in steam. The thinking being if the boiler is full when you start will last as long as the burner stays lit.
I have seen at couple of Mamod boilers damaged by the burner being topped up to try and keep the engine running without topping up the water.
In the days of steam there were some nasty boiler explosions caused by operators weighing the safety valves down to raise the steam pressure.

 

[HarryML7]

I can’t remember what the feed water pressure was but on a Y100 boiler the steam pressure was 550psi at 850°F. If you search for Yarrows Y100 boiler there is lots of info on ships main boilers.

^{_{Subscribers  do not see these advertisements}}

 

[Geo]

Actually a very clever bit of kit if you follow the link to "Locomotive Injectors" I have learnt something today so thanks for asking Spriddler

I have a lawn to scarify but there is some good reading there for another day.

I'd start looking now
For a steam powered scarafyer.....lol

 

[ADJF]

Steam injector and oneway opening clack valve. I send a lot of time on locomotives#

 

[meanders]

Having spent several years as a volunteer at Bressingham before my ankle injury put paid to it, I remember well the feeling of panic when the damn clack valves wouldn't work. Notoriously temperamental things and the reason you generally have two to play with. You need a head of steam to operate the valve as the steam pressure forces the water into the boiler. I never had to drop the fire, but one or two did.

Safety valves should be the last resort, but when they go off, they make one hell of a din.

^{_{Subscribers  do not see these advertisements}}

 

[meanders]

Incidentally, while most steam locos run at about 200 to 300psi. There were trials of much higher pressures. Look at wikipedia.org/wiki/High-pressure_steam_locomotive for a longer read.

 

[funflair]

On a slightly different tack but still the power of steam, http://www.force-of-nature.com/content/home-page it doesn't generate steam but runs on a tank of superheated steam at very high pressure, the engineering on it is fantastic.

My brother built the carbon fibre bodywork

 

[WillH]

I am a retired marine engineer, cut my teeth on boilers, 600 psi, superheated. We had turbo feed pumps capable of 750 psi to feed the boilers.

^{_{Subscribers  do not see these advertisements}}

 

[knickam]

I served my time at an Oil/Gas fired power station
One of the main boilers heated over 2 tonne of water a second to 541degC running at a pressure of 160bar
This powered a 660 Megawatt generator.
The main boiler water feed pump was steam driven and was equivalent to a 30 Megawatt motor

 

[HarryML7]

I served my time at an Oil/Gas fired power station
One of the main boilers heated over 2 tonne of water a second to 541degC running at a pressure of 160bar
This powered a 660 Megawatt generator.
The main boiler water feed pump was steam driven and was equivalent to a 30 Megawatt motor

I wouldn’t like to be in vicinity of at leak at those pressures/temps.

 

[knickam]

I wouldn’t like to be in vicinity of at leak at those pressures/temps.

Used to get steam leaks on valve glands that had to be repaired on line.
Specialist company came in to drill into and inject a sealant into the stem with superheated steam flying past them.

^{_{Subscribers  do not see these advertisements}}

 

[olley]

I served my time at an Oil/Gas fired power station
One of the main boilers heated over 2 tonne of water a second to 541degC running at a pressure of 160bar
This powered a 660 Megawatt generator.
The main boiler water feed pump was steam driven and was equivalent to a 30 Megawatt motor

That's over 8000psi!

 

[Spriddler]

Great info. Thanks all.
I wondered about the refilling process after watching a prog when Fred Dibnah took on water from a street hydrant whilst on a trip with his traction engine and with the engine boiler obviously still in steam.

I had considered that it would be possible to pump the fresh water into the boiler at a higher pressure than the boiler but discounted it on two points which I still can't get my head around:

1. The water must be pumped into the boiler at a higher pressure than the pressure already in the boiler, so physics says that the steam or mechanically driven water pump is generating more energy (pressure) than is being delivered to it from the boiler................... in spite of the pump's frictional and leakage losses.

2. The volume of water pumped into the boiler must have more potential energy than the water being consumed to power the pump (mechanically or steam driven) to deliver the water or there wouldn't be any point in doing it as eventually the boiler would become empty.

Both scenarios seem to be perpetual energy (i.e. getting more power out than put in).

I shall now go into the sunny conservatory with a brew and browse the links given. I may be some time.

 

[knickam]

Great info. Thanks all.
I wondered about the refilling process after watching a prog when Fred Dibnah took on water from a street hydrant whilst on a trip with his traction engine and with the engine boiler obviously still in steam.

I had considered that it would be possible to pump the fresh water into the boiler at a higher pressure than the boiler but discounted it on two points which I still can't get my head around:

1. The water must be pumped into the boiler at a higher pressure than the pressure already in the boiler, so physics says that the steam or mechanically driven water pump is generating more energy (pressure) than is being delivered to it from the boiler................... in spite of the pump's frictional and leakage losses.

2. The volume of water pumped into the boiler must have more potential energy than the water being consumed to power the pump (mechanically or steam driven) to deliver the water or there wouldn't be any point in doing it as eventually the boiler would become empty.

Both scenarios seem to be perpetual energy (i.e. getting more power out than put in).

I shall now go into the sunny conservatory with a brew and browse the links given. I may be some time.

It is the fuel that heats the boiler that produces the energy, Not the pump pumping in the water
So the more fuel used the more steam is generated and only a small percentage of this steam is used to drive the water pump.
Not sure what the percentage is in a Locomotive but in the power station I was at it was roughly 5% of the steam generated was used to pump the water in.

^{_{Subscribers  do not see these advertisements}}

 

[funflair]

Used to get steam leaks on valve glands that had to be repaired on line.
Specialist company came in to drill into and inject a sealant into the stem with superheated steam flying past them.

Furmanite by any chance, I did a bit of that serving my apprenticeship in ICI, the foreman was a bit reluctant to let apprentices too close to the live steam but the fitters thought it was good experience though.

 

[JJ]

The Fat Controller makes sure all the boilers are full at the start of the day...

JJ

 

[roger7]

one bar =14.5 psi so 160 bar =2320 psi

^{_{Subscribers  do not see these advertisements}}

 

[Gromett]

losing the steam pressure?
Surely the boiler has to be 'opened' to replenish the water exhausted as steam but wouldn't that let all the steam pressure out of the boiler and cause a long delay whilst the fresh cold water heated up and pressure was restored?

Secondly. A higher than atmospheric pressure raises the boiling point of water so does that mean that the pressurised boiler water has to be raised to a greater temperature than 100degC before generating steam?

Thirdly. At what pressure (lbs/sq. in.) does the boiler operate?

I've trawled no end of graphics and YouTube videos on t' web without finding answers.

John Barrett ?

I love questions like this. I love learning new stuff and this is one that is probably going to send me down the rabbit hole when I finish work tonight Thanks for asking

 

[Gromett]

That's over 8000psi!

Did you know that the Toyota Mirai hydrogen fuel cell car hydrogen tank is at 10,000 psi?

Can you imagine driving around with a hydrogen tank at 10,000psi under you? Double boom. 10,000 psi tank letting go then hydrogen explosion.

 

[jockaneezer]

Think of a boiler feed pump a bit like a hydraulic bottle Jack Spriddler, the tiny hand pump can exert a few tons of pressure to lift a heavy load ? Now injectors, they're a totally different story that I think involves black magic !

^{_{Subscribers  do not see these advertisements}}

 

[knickam]

Furmanite by any chance, I did a bit of that serving my apprenticeship in ICI, the foreman was a bit reluctant to let apprentices too close to the live steam but the fitters thought it was good experience though.

Thats the boys, Used to think they were nuts

 

[olley]

I love questions like this. I love learning new stuff and this is one that is probably going to send me down the rabbit hole when I finish work tonight Thanks for asking

If you pressurise the water enough you can prevent it turning to steam as you increase the temperature until you reach the critical temp grom, thats about 705 F at 3200psi at that point it turns to steam no matter the pressure, if you continue it becomes super critical which was and is above my pay grade.

 

[bigwood]

I think the boiler for my truck is a bit low scale with safety valves set at 80 psi. I remember a guy with a traction engines at one of the steam rallies leaning over the side and clouted the injector with a shovel.
He said lime scale blocked the jets so a good clout cleared them. Not sure if that’s good practice at a public event.

^{_{Subscribers  do not see these advertisements}}

 

[Spriddler]

One thing I hadn't realised was the extremely high boiler pressures involved.
Those early steam engineers were a great deal cleverer than I realised (or maybe cleverer than they themselves realised).

The Fat Controller makes sure all the boilers are full at the start of the day...

JJ

That was the nickname which the family used covertly when referring to one of my son's bossy girlfriends, and she really was a big unit.........
Fortunately it didn't last.

 

[olley]

one bar =14.5 psi so 160 bar =2320 psi

We were taught 14.7 but where I got 8000 from in a previous post I have no idea.

 

[John Barrett]

losing the steam pressure?
Surely the boiler has to be 'opened' to replenish the water exhausted as steam but wouldn't that let all the steam pressure out of the boiler and cause a long delay whilst the fresh cold water heated up and pressure was restored?

Secondly. A higher than atmospheric pressure raises the boiling point of water so does that mean that the pressurised boiler water has to be raised to a greater temperature than 100degC before generating steam?

Thirdly. At what pressure (lbs/sq. in.) does the boiler operate?

I've trawled no end of graphics and YouTube videos on t' web without finding answers.

John Barrett ?

I missed this thread as I was on the wagon for a lot of this month and didn't go near MHF!
Some good answers on here.
John

^{_{Subscribers  do not see these advertisements}}