Operation and Control of a Steam Ships Engine

[Dan Rowe]

Dave,
I was the day working 3rd assistant engineer and I asked why we did not use the old shell and tube evap to make water from sea water. They were only using it with shore water to make boiler water. Well they simply said to try it and see. Well I did make some water but I spent the next day knocking the salt scale off the tube bundle. Modern flash type evaps do not suffer this problem.

The Civil War era ships used sea water in the boilers. This was not good for the boilers but they were low pressure and it was the ONLY possible way to operate on the ocean at the time for any extended period of time.

Dan

[crueby]

For boiler water they would also condense the steam back to liquid to reuse, so you won't need to use new constantly, just to replenish losses. Nice thing about a boat, plenty of water to cool with.

[Gas_mantle]

Even condensing the steam back to water the Titanic must have been one thirsty beast, according to this page it had 29 boilers with a total of 162 fireboxes needing need 600 tons of coal per day.

Can't see any reference to how much water it used though.

http://www.titanic-titanic.com/titanic_boilers.shtml

[steamer]

Dave,
I was the day working 3rd assistant engineer and I asked why we did not use the old shell and tube evap to make water from sea water. They were only using it with shore water to make boiler water. Well they simply said to try it and see. Well I did make some water but I spent the next day knocking the salt scale off the tube bundle. Modern flash type evaps do not suffer this problem.

The Civil War era ships used sea water in the boilers. This was not good for the boilers but they were low pressure and it was the ONLY possible way to operate on the ocean at the time for any extended period of time.

Dan

YUP...hence my preceding comment regarding the period that unit was used.     Note the big cover and jib boom to service it....it must have been a LOT of fun to clean it.

[Dan Rowe]

I am not able to get to my marine engineering books so I googled to find the evaps for the Titanic. This page is a gold mine of Titanic marine engineering.  The last paragraph of A Closed Loop System has the answer they had 3 evaps with a 60 ton per day capacity each.

http://www.titanicology.com/Titanica/TitanicsPrimeMover.htm

[Gas_mantle]

Cheers Dan, looks like an interesting read.

I bet despite all it's lavish rooms above deck the Titanic must have been a dirty hell hole below deck, it must have been savage firing it.

[Tennessee Whiskey]

I've been quite entertained and educated by this thread.  The last "real job" in which I was employed  (before I lost my mind and became self employed  ) was a boiler inspector.  Our company built and rebuilt recovery boilers for the paper industry in the deep South, Northeast,  and Northwest.  The boilers were gas lit and fired by "black liquor", a byproduct of the paper process.  Folks, you talking about some nasty,  caustic,  flammable,  crap; it's black liquor.  The "fuel" was sprayed into the cavity at 2-4 locations thru nozzles much like those on big fire trucks.  I'll shut up now,  back to the boats and more education 

Cletus

[b.lindsey]

I was curious about what was used for boiler feed water too on the open sea. Glad Dave filled in that blank. The same question had occurred to me on the marine donkey engine thread as well, but figured that since the donkey engine/boiler would only be used in ports, there would be a fresh water supply there to use.

Bill

[Dan Rowe]

Bill,
This thread started about the Uss Monitor which was to early to have the type of evap that Dave illustrated. I called it a shell and tube type as that is what I remember they are called. This wiki article calls them Combined Supply which is not a term I have heard before. The article states the combined supply type was introduced around 1867.

https://en.wikipedia.org/wiki/Evaporator_(marine)#cite_note-Rippon.2C_Vol_1.2C_60-4

Dan

[b.lindsey]

Interesting article Dan, thanks for the link.

Bill

[Gas_mantle]

I came across this info on the Titanic - it seems the desalinated feedwater was stored in 15 tanks in a double skinned hull and they could store 5700 tons of water.

https://www.encyclopedia-titanica.org/titanic-hidden-deck.html

[Dan Rowe]

The figure you listed was the total water capacity of the double bottom tanks. Of these tank #10 ,#11 and #12 were designed for FW or fresh water with a total capacity of 1,002 tons. Double bottoms #1,#2,#3,#13,#14 and #15 could carry FW or WB water ballast with a total capacity 796 tons of FW. These tanks normally had WB.

Figure 7 shows the FW tanks that were not double bottoms the total of these tanks were 962 tons of FW.

So normally the FW capacity was 1,964 tons, and using the reserve set of tanks an additional 796 tons of FW could be carried.

Now all this FW was not for the boilers....not by a long shot. I do not know if the Titanic used FW for sanitation but my guess is that they used salt water sanitation because of the number of the crew and passengers. The same ship I was on with the shell and tube evap had salt water sanitation. Changing a leaky flushing water pipe took a real ginger touch with a pipe wrench because all the pipe was rotten from the inside out and I did not want to repipe the whole system.

Anyway simply figuring a gallon or two a day for the people on board adds up fast, but with cooking and cleaning and washing even 2 gallons a person per day would be extremely conservative.

With the maintenance required on a shell and tube evap it is doubtfull that more that two could be run continuously giving the makeup capacity of something greater than 120 tons a day.

Cheers Dan

[Maryak]

Dave,
I was the day working 3rd assistant engineer and I asked why we did not use the old shell and tube evap to make water from sea water. They were only using it with shore water to make boiler water. Well they simply said to try it and see. Well I did make some water but I spent the next day knocking the salt scale off the tube bundle. Modern flash type evaps do not suffer this problem.

The Civil War era ships used sea water in the boilers. This was not good for the boilers but they were low pressure and it was the ONLY possible way to operate on the ocean at the time for any extended period of time.

Dan

Shell and tube vaps are blowndown to descale. you were had!!

Build the shell pressure up to 15psi open the blowdown to sea. When its blown out pull a vacuum and induce cold seawater back up over the coils the scale cracks off the coils and the whole lot is blown out again only this time to bilge. One ship I served in had lost the blowdown striker plate and at the start of the watch the blowdown to bilge resulted in the South China Sea blowing back into the boiler room. This cause considerable consternation as every plug driven into the hole made it bigger. Finally some solid hull was encountered, the leak slowed to a trickle, a cofferdam was made and the whole area filled with concrete!

The joys of handme downs from our Imperial Masters in the North.

On a good day make up feedwater was around 250gals per hour or a bit over a ton. We carried around 56 ton of feed and 40 ton of potable water. Any problem with the vaps and no showers. Same ship we lost one vap 3 weeks into a 6 week patrol of Borneo during Confrontation. No showers, overall tied with rope and hung over the stern for washing. Until you sweated them loose you move about like Willie the Penguin.

[Captain Jerry]

Hi Jerry,

With Marine recip engines using browns reversing gear an emergency full ahead to full astern is done by first grabbing the reversing lever in one hand and pulling like mad, if the links don't want to swing over and your away astern then whilst still hanging onto the reversing lever use the other hand to spin the throttle shut. Once the links are over spin the throttle open. After this you can start to think about the little things like opening the drains as it is highly likely a stop is on the cards. All round gear takes its own sweet time to move the links so start the motor and close the throttle to help ease the load on the valves, particularly the big slide vales on the LP cylinder(s). Same again once the links are over, spin open the throttle.

As an aside, I have never heard of a gate valve as a throttle. They would be difficult to operate quickly and more importantly would be subject to large doses of wire drawing resulting in not being able to completely shut off steam to the engine. Most Maneouvering Valves, (throttles), are of a type known as a double beat balanced valve.

With steam turbines operation of the ahead and astern throttles is done simultaneously i.e. the ahead is spun shut at the same time as the astern is spun open.

With direct drive diesels and a fixed pitch propeller it is necessary to stop shaft before reversing else the bloody thing wont start in the right direction. Fairbanks Morse are a prime example of this. (Ask me how I know!!!)




Extract from 1962 PR film you may notice that the order is full ahead but the throttles are being operated for ahead to astern and the tacho on the left is currently showng the engine running ahead. Only a story and I suspect what in fact was happening is a backdown where the engines are used as a brake to reduce from approach speed, (say 25+ knots to tanker speed say 12 knots),  for a RAS, (USN UNREP) approach. Still you get the idea of both throttles being operated simultaneously.

HTH

Best Regards
Bob

Hi Bob,

Thanks for this.  It answers all of my questions and a few that I hadn't asked yet.  So the first action is to attempt to move the valves with the reversing lever but if that can't be completed, because of the load on the valves, ease the load by closing thee steam valve and then after the reversing lever goes over, open the steam valve.  This confirms my original thinking that the steam valve may need to be closed but not always.

Your term "spin" the valve closed, answers my question as to how fast can it be  closed and this says "as fast as you can."  It also answers a question that I had wondered about but never asked, "Why are the hand wheels on the steam valves so big."  I had always equated big hand wheels with fine control or with heavy torque, but your term "spin" and the later video changes that thinking completely.  They are big so that they can be spun like a flywheel so that one good yank might give you three or four revolutions.  I will look at big hand wheels with a different view from here on.

I incorrectly called Ericsson's throttle a "gate" valve when it is in fact when it is actually a "gridiron" valve, a more common type of throttle.  On Ericsson's Monitor, it is closed using a relatively small, horizontal hand wheel and a vertical shaft.  The small hand wheel has a handle like the handles on my mill so it may not spin like a big hand wheel.

Ericssons's Monitor does not have a reversing "lever."  It was reversed using a big hand wheel.  I have only seen this  operated in the video of Carlstadt's model and the wheel was turned very slowly to demonstrate the function of the crank arms and bevel gear segments that are used to roll the eccentrics over.  If the big wheel could be spun like a steam valve while the engine was turning, it changes the whole picture.  It could be easily reversed within two or three engine revolutions.

I have been looking at this valve gear all wrong.  My brain had been trying to equate it with some kind of Stephenson's gear. There are four eccentrics, two per cylinder but that is because it has an early cut of valve stacked on top of the normal slide valve.  The second eccentric has nothing to do with reversing.  To reverse the valve events, the entire stack of four eccentrics is rolled over 180 degrees.  This is a SLIP ECCENTRIC, a very simple reversing method but with a very sophisticated method of actuating it.

These are new conclusions that I have come to that I would never have reached without your revelations.  Thanks again, Bob.  You old hands probably new all about spinning big hand wheels but I didn't.

[Maryak]

Hi Jerry,

Glad to be of some help.

I have notice several times in the thread and in your last post the mention of a slip eccentric and the slip roll over of 180deg. The little I know about a slip eccentric is that the roll over is somewhere around 107deg dependent on the amount of lap and lead. It is equal to the ahead and astern eccentric positions of the eccentrics in a normal Stevenson's link.






The handwheel for reversing equates to my term All Round reversing and was used when the electric motor driving the reversing gear worm failed. Was great for warming through as the links cycled from ahead to astern without the operator having to do anything other than ensure steam to the engine was only a trickle!!

Hope this helps

Regards
Bob