Topic: Steam engines in real ships.... (Read 20862 times)

flashtwo · « **Reply #25 on:** July 12, 2009, 07:42:38 pm »

Hi,

Wasn't there a part of the old vaps called the "ebulation chamber". Why it wasn't called the boiling chamber I never did discover.

Ian.

boatmadman · « **Reply #26 on:** July 12, 2009, 07:44:10 pm »

Barry,
Laughed like a drain at the last paragraph - been there, done that both as apprentice and more senior engineer

Ian

BarryM · « **Reply #27 on:** July 12, 2009, 11:59:00 pm »

Ian,

I also recall another tradition which found Apprentices working on deck in January in northern Sweden in inadequate clothing while the Engineers always found work in the Engine Room. In the Tropics the reverse ocurred. This was known as 'Character Building' and always supported without question by all Engineers as being in the best traditions of the Merchant Navy.

The only persons on whom Engineer Apprentices could inflict minor atrocities were Deck Apprentices sent below for ER experience. They took every advantage then...

Cheers,

Barry M

Steamer · « **Reply #28 on:** July 13, 2009, 12:05:31 pm »

That was a funny paragraph Barry!

The source I have....can't put a finger on it at the moment...was speaking to Reciprocating engines only, and old ones at that.

The IP Receiver pressure was approximately 60 psi, or in that neighborhood, so that part agrees with your comments. As to how to make sure salt was not carried into the system, I am sure the old reference outlines old ways of doing things. Far older than 1950, more like 1900. My reference stated that the evaporated vapor went to the condenser or LP exhaust receiver....now what they meant by LP Exhaust receiver I don't know, To me it means the exhaust line from the engine to the condenser. I can gladly say, that I have never run an evaporator and only saw one first hand on a Liberty Ship........and it was open being either scaled or repaired....and I didn't have do it either!

I am sure that as pressures went up over the years since the turn of the century, the necessity of keeping salt out of high pressure boilers become more and more critical, and far better ways and means of doing so were developed.

I'll report back the title in bit.....

Dave

gondolier88 · « **Reply #29 on:** July 13, 2009, 05:26:29 pm »

Hi,

Am I missing something here?!?

Didn't ships in the early 1900's carry fresh water in tanks that were inneficiently condensed- being gradually diluted with salt water- then de-scaled when back in port, by apprentices of course!?

As condensing machinery got more efficient less and less salt water was needed to top up the system, until the more 'ideal' plants of the 40's/50's which were true closed systems, only needing topping up when back in port to replenish the tanks from steam leaks, blowdowns and drain valves opening?

Greg

BarryM · « **Reply #30 on:** July 13, 2009, 06:43:25 pm »

"Carry fresh water in tanks that were inefficiently condensed"? - You've lost me there.

Early steam plants of the 19th C. used seawater for feed and regular blowdown to keep the salinity to a tolerable level. However, eventually the boilers had to be shut down for manual cleaning. The changeover to fresh (shore) water and then distilled seawater feed was gradual. Some ships would initially use water loaded in port and then, when that ran out, switch to a seawater feed with all that meant in terms of blowdown and scaling. Eventually, evaporation plants were introduced (1910 or therabouts?) became more efficient enabling ships to make-up feed losses and then the Weir's Closed Feed System (the great advance for steam in the 20th C. ) arrived in ca. 1950(??)

Incidentally, at one time new Scotch Boilers were run on seawater to form an eggshell thin coat of scale on the internal surfaces. This was intended to stop corrosion 'bleeding' when mill scale cracked off.

Barry M

gondolier88 · « **Reply #31 on:** July 13, 2009, 07:23:38 pm »

Hi BarryM,

Quote from: BarryM on July 13, 2009, 06:43:25 pm

"Carry fresh water in tanks that were inefficiently condensed"? - You've lost me there.

Some ships would initially use water loaded in port and then...switch to a seawater feed...Eventually, evaporation plants were introduced (1910 or therabouts?) became more efficient enabling ships to make-up feed losses and then the Weir's Closed Feed System (the great advance for steam in the 20th C. ) arrived in ca. 1950(??)

To say I lost you that was the answer I was looking for, thanks!

Greg

BarryM · « **Reply #32 on:** July 13, 2009, 07:42:40 pm »

Have I been helping you with your homework?

Cheers,

Barry M

gondolier88 · « **Reply #33 on:** July 13, 2009, 07:54:48 pm »

Hi BarryM,

Always ready to do a bit of homework on steam!

Greg

Steamer · « **Reply #34 on:** July 13, 2009, 11:25:41 pm »

Quote from: Steamer on June 09, 2009, 06:11:51 am

Hi,
Very old vessels ran seawater in their boilers and if you google a "salinometer" you'll find out how they determined when to "blow down" the brine and refill with with "fresh" seawater.......Not the best thing for a boiler, but at 20 psig, it wasn't such a big deal.

In the modern era....1870's forward....and I speak to reciprocating engines only.

For ocean travel, ships used evaporators to create fresh water from sea water.

Boiler steam was run through coils in large tanks. The water would boil off and be collected. Periodically , the tanks would be opened and the salt cleared.

Of course these ships, at least the modern era, ran condensers...which also helped engine performance. The steam was condensed and brought to a tank called a "hotwell". This tank was used to dearate the condensed water brought there by the wet air pump and to remove any lubricating oils that might have been in the steam....A Wet air pump is an appropriate name as it took condensate and air out of the condenser.

Boiler water chemistry was and still is very important to the life and well being of a boiler. This analysis was done by the "Chief" by performing various chemical analyses usually by titration reactions. From there, The Ph , dissolved solids, and sulfates among other things could be determined and altered with various chemicals added to the feedwater usually in the hotwell. Keeping the Ph slightly alkaline was ideal......now in small scale....starting out with distilled water is easier!

Dave

This might answer your question.......

gondolier88 · « **Reply #35 on:** July 14, 2009, 07:28:05 am »

Hi Steamer,

Thanks for your reply. That has clarified things further for me. My knowlege is of SY Gondola's plant and other smaller freshwater launches, some of which have condensing machinery, but no evaporation plants, so I hadn't realised the part this technology played in the latter years of reciprocating machinery- and unfortunately in this life i'll probably never get the chance to.

Greg

Bunkerbarge · « **Reply #36 on:** July 14, 2009, 07:50:12 am »

Interestingly enough we still have the basic components of the steam system in evidence even in low pressure auxilliary boiler systems on ships today. On a modern cruise ship you will find exhaust gas boilers supporting two auxilliary oil fired boilers with the condensate coming back in two streams, one from clean tanks and one from dirty tanks to enable the seperation of any contaminants.

Feed is from the main fresh water evaporators with the normal path through the hardeners being by passed and pure condensate being stored in the feed tanks. In the time I have been with this ship we have had contamination of the feed tanks from a couple of different sources, both with disastrous results and one of which very nearly took the ship out of service.

It may be of interest to know that when we go to dry dock we change over one of the potable water storage tanks to hold distillate so that we have sufficient reserves of feed for the two weeks we are going to be without evaporators.

Steamer · « **Reply #37 on:** July 15, 2009, 06:29:25 am »

Hi Greg,Barry

My experience is similar to yours Greg. My own launch is condensing, but I have never worked the "big stuff" other than an engine restoration team I was on for a 750 BHP compound....all 40 ton of her!
The name of the reference was "Heat Engines" by Ripper. Not the most technically advanced book of the turn of the century, but it reads well....

If I can coral some time, I'll scan the pertinant page or two and post here if required..

I admire SY Gondola and salute you for your stewardship.....I trust she will sail for many more years. Check out "Sabino" when you get a chance. I was a volunteer in her engine room for 12 years.

Dave

BarryM · « **Reply #38 on:** July 15, 2009, 09:03:55 am »

It makes me smile when I read of "Traditional Steamship Courses" on the Sheildhall at £420 for a 4-day course. http://www.ss-shieldhall.co.uk/
I spent many years on steamships where the owner paid me considerably less.

Barry M

gondolier88 · « **Reply #39 on:** July 15, 2009, 10:42:28 am »

Hi Dave, Barry,

I like Sabino a lot, she's full of character, and a true steamboat- born through necessity rather than opulance or wealth- interesting that she was built with a watertube boiler- she must have been a dream to steam?!?!

Could we have some details of your launch, maybe some pics?

It makes me smile too Barry- the more you know about steam the more you realise there is to learn- however from Sheildhall Ltd.'s point of view it is a necessity to get punters in- something that we are fairly lucky with Gondola- being placed in the heart of the lakes- but we struggle enough- we normally only break even- so how hard SS Sheildhall, PS Kingswear Castle, PS Waverly etc find it I can't imagine!

Greg

Steamer · « **Reply #40 on:** July 16, 2009, 10:56:25 am »

Greg,

Sent you an email...

Dave

gondolier88 · « **Reply #41 on:** July 16, 2009, 08:42:52 pm »

Hi Dave,

Thanks for the email- very pretty little boat you have there- is the hull design your own- it looks very similar to Glynn Lancaster Jone's Mariamne Class launch?

Greg

Steamer · « **Reply #42 on:** July 16, 2009, 11:16:31 pm »

Thanks Greg,

It's a 25' x 5' "Panatela"....I designed her, the engine and boiler.

Dave

Martin (Admin) · « **Reply #43 on:** July 31, 2009, 05:36:20 pm »

Another question, can you over speed a steam engine?

1 Run a model engine at full bore with no load?
2.Run a full size engine at full bore with no load?

...what could happen?

BarryM · « **Reply #44 on:** July 31, 2009, 07:23:14 pm »

Martin,

Re No. 2 - In this situation one usually takes steps - b***dy great big ones out of the Engine Room.

Barry M

flashtwo · « **Reply #45 on:** July 31, 2009, 08:24:50 pm »

Hi Mayhemers,

Two cases come to my mind of steam turbines with failed overspeed protection system. One was at Uskmouth Power Station in Wales, where the hp turbine landed in the mud one mile away. A colleague of mine was a young engineer there and had only walked away from the turbine five minutes before it blew up taking a plant attendant with it. My colleague still carried a photo of the turbine in the mud in his wallet years after the event. The cause was esturine cooling water getting into the protection hydraulics.

The other case was at Woolwich Power Station when the turbine took off and landed on the other side of the River Thames.

The no load situation for turbo-generators is when they get disconnected from the National Grid when on load. These days there are sophisticated electronic overspeed protection devices, but even they have a mechanical system as the final backup.

You can get a partial no-load incident when the generator pole-slips. This is the electrical equivalent of a bicycle chain jumping a tooth. A friend of mine was finishing shift and having a wash, when a pole-slip caused the water to jump right out of the washing bowl, hit him in the face before settling back in the bowl again - like a minor earth-quake.

Most steam engines require a speed governor to stop them over-speeding, although I have noticed that one of the smaller pumping engines at Kew doesn't have one because it always has a pumping load - until the shaft breaks!

Ian

gondolier88 · « **Reply #46 on:** July 31, 2009, 10:37:18 pm »

As long as there is sufficient lubrication to the main bearings of the right quality oil and the bearings are large enough and the pistons have just the right fit and enough lubrication and the gudgeon pins are strong enough then technically no you can't, but we don't live in an ideal world so I wouldn't like to try on a full size- but I regularly run the model cheddar puffin plant at full speed with no load- but a basic oscillator with 11mm Sq. cylinders doesn't bear any resemblance to say a stuart D10, perhaps some other members have experiences with larger model engines (bogstandard step forth...)?

Flashtwo, we must remember that steam turbines and steam engines really are two wholly different beasts here!!!!!

At full size pressure is a square, speed is a constant, and disaster is to the power of 10- unless you can guarentee the engine has everything it needs to run at it's fullest speed.

Greg

BarryM · « **Reply #47 on:** July 31, 2009, 11:32:05 pm »

Steam turbines and steam reciprocating engines are certainly different beasts although both rely on the expansive powers of steam. However, Martin does not make it clear what he means by his idea of "full bore". If he means simply opening the throttle of full-size plant without applying load then nothing untoward will happen as the overspeed governor will act to limit the revs to a safe figure. If the overspeed governor is faulty or disconnected for whatever reason then the engine will likely suffer catastrophic damage no matter whether it is rotary or reciprocating in principle. There will be no difference whatsoever in the result; large bits of metal spread over the geography.

As far as the effects of running a model engine at excessive speed and off load (and usually without a governor are) are concerned, the outcome (probably possibly?) will be less drastic as the scale effect comes into play. Nevertheless, with no forced lubrication it risks seizure of bearings and galling of sliding surfaces while any weakness in construction may well lead to mechanical failure. Not an experiment to be attempted.

Barry M

derekwarner · « **Reply #48 on:** August 01, 2009, 12:01:02 am »

As Barry M notes.....nevertheless, with no forced lubrication it risks seizure of bearings and galling of sliding surfaces while any weakness in construction may well lead to mechanical failure

mmmmmmm, many years ago we completed an upgrade to a large axial turbo compressor.......steam driven & everything is fail safe

So on start up ....duplex electric lube pumps provide lubrication for the turbine...after a number of permissives have been attained [speed & pressure] the gear driven duplex lube pumps take over & the electrics are shut down

Well yes....

the two tonne rotating turbine element also came to a screaming halt [3000 rpm to ZERO in about about 3 minutes] ......the

investigation found flap style GHH lube pipe check valves were installed back to front

It was fail safe ...excluding human error

naturally a revised set of inspection procedures were written..........Derek

Steamer · « **Reply #49 on:** August 01, 2009, 11:40:03 am »

As Barry states, nothing good will come of it, and the bigger the plant, the worse the situation will get. This by way of the large increase in my by the 3rd power of the scale. The forces involved go through the roof....

Dave

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Author Topic: Steam engines in real ships.... (Read 20862 times)

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