Steam pressure of the engines


khoi nguyen

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Given that the steam pressure supplied by the boilers was A psi and the two main engines were running full ahead.

Q1: Would both engines get that A psi or would they get only a half of it ?

Q2: Then they stopped one engine, would the pressure and speed of the other engine increase as a consequence?
 

Jim Currie

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Given that the steam pressure supplied by the boilers was A psi and the two main engines were running full ahead.

Q1: Would both engines get that A psi or would they get only a half of it ?

Q2: Then they stopped one engine, would the pressure and speed of the other engine increase as a consequence?
The initial pressure to each HP cylinder was constant. It was the volume of steam allowed into the cylinders which regulated the rpm. Consequently, by varying the amount of steam to each HP cylinder, the engineers could select the required speed on each engine.
 
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khoi nguyen

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The initial pressure to each HP cylinder was constant. It was the volume of steam allowed into the cylinders which regulated the rpm. Consequently, by varying the amount of steam to each HP cylinder, the engineers could select the required speed on each engine.
If one engine stopped, wouldn't it cause a surge of steam into the HP cylinder of the other engine?
 

Arun Vajpey

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One question about steam pressure and stopping distance. In a ship like the Titanic running on two reciprocating engines and one turbine, how would steam pressure affect its stopping distance?

Putting the question another way, if the Titanic was doing only 11 knots, I assume the steam pressure would be lower. Would that lower pressure affect the ship's "braking" ability?
 
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The ships boilers produced steam at 215 psi. You didn't turn it up or down as required, you just used valves to control how much pressure you wanted to use of the 215 psi that was available. Just like, Arun, the oxygen supply next to a bed in the hospital. The system is pressurised and you crack a supply valve to the required flow rate.
 

Jim Currie

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The ships boilers produced steam at 215 psi. You didn't turn it up or down as required, you just used valves to control how much pressure you wanted to use of the 215 psi that was available. Just like, Arun, the oxygen supply next to a bed in the hospital. The system is pressurised and you crack a supply valve to the required flow rate.
Actually the initial inlet pressure was the same at 215 psi wherever you used it, Roger, unless there was a pressure regulator up stream.
The principal of Triple Expansion , was that you got a volume of steam at 215 psi entering into the HP cylinder - a small space - which used up part of the energy. Then as it passed into a larger space the pressure dropped as the volume expanded into a larger space i.e. steam moved into the IP (Intermediate Pressure) cylinder which used more energy and then the pressure dropped again as the same amount of steam expanded even more, into an even larger space.. the LP (low pressure cylinder,
 
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Putting the question another way, if the Titanic was doing only 11 knots, I assume the steam pressure would be lower. Would that lower pressure affect the ship's "braking" ability?
What would be lower would be the volume of steam supplied to the engines by controlling what's called the cut-off point, not the pressure. Shorter cutoff meant a smaller volume of steam available to expand in the engines and therefore a slower running rate. In an emergency they would still have the full pressure to use for reversal, and they could use a higher cutoff point to allow a greater volume of steam into the engines for reversing.
 
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Mike Spooner

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Those who think recycling is some thing new of to-day, they were well on to it over a 100 years ago now.
As one can see from triple-expansion engines. Another way to look at steam pressure is recycling the exhausted steam from the high pressure cylinder to the intermediate cylinder then the exhausted steam is entered into the lower cylinder, then the exhausted steam on to the condenser. Condenser is a cold chamber coursing a vacuum and recusing the temperature to the point of water. From there into a hotwell pumps heated to about 175f then back into boilers. As steam is reduced in pressure and temperature it will only expanded in volume hence the three different size cylinders bores. HP 54" IP 84" LP 97" times two cylinders. However Olympic/Titanic had another used of the exhausted steam from the two lower pressure cylinders to drive a low pressure turbine from 9psi to 1psi and then into a hotwell pump back to boilers. The turbine was only engage went the two expansion engines had reach 50rpm.
 
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Tim Aldrich

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Mr. Halpern, my mechanic's brain is equating steam cut off points to the open time of the valves with adjustments being made via the valve gear. Would that assumption be correct?
 

khoi nguyen

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It's hard to figure out the law of physics behind this.

Let's say the pressure in the main steam line was maintaining constant.
The boilers produced A volume of steam per second and the HP cylinder of each engine consumed averagely A/2 volume of steam per second.
When one engine stopped where would that amount of A/2 volume of steam per second would go ? for not causing a surge of steam into the HP cylinder of the other engine.
 

Jim Currie

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It's hard to figure out the law of physics behind this.

Let's say the pressure in the main steam line was maintaining constant.
The boilers produced A volume of steam per second and the HP cylinder of each engine consumed averagely A/2 volume of steam per second.
When one engine stopped where would that amount of A/2 volume of steam per second would go ? for not causing a surge of steam into the HP cylinder of the other engine.
The inlet pipe to the cylinder will only allow a certain volume of steam at a given pressure to pass, therefore no surge.
 
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Mar 22, 2003
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When one engine stopped where would that amount of A/2 volume of steam per second would go ?
It would build up in the boilers creating a higher pressure unless the firing rate of the boilers was reduced. That's why when they stopped Titanic's engines, the firemen were told to shut the dampers. If the pressure builds up too high the safeties would blow. There was also a manually operated silent blow-off valve which allowed some steam from the engine feed line to be bled directly into the main condensers.
 
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my mechanic's brain is equating steam cut off points to the open time of the valves with adjustments being made via the valve gear.
To control the direction of the engine and set the cutoff point, the engineer at the controls would have to move a “reversing” lever that would cause the expansion linkage to move to an ahead or astern position. For large engines such as on the Titanic, a hydraulic cylinder called a Brown’s engine would be used to actually move the linkage. The movement of the linkage would be adjusted to control the desired cutoff point that steam is admitted to the cylinders and thereby set the desired degree of steam expansion within the cylinders. At full ahead speeds, a cutoff point of about 40 to 45% of the piston stroke might be used.

See: Titanic’s Propulsion Plant
 
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Mike Spooner

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While on the subject of 29 boilers pressure which the system is design to run at 215psi.
However that's is a requirement from the fireman or some time know as the black gang to check out each boiler for the correct pressure at 215psi.
The question I ask at what stage when there drop in psi pressure do the firemen add more coal?
 

khoi nguyen

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Another question,

First case, the main steam pressure was 215 psi, they cracked open the throttle valve to bring the pressure gauge of the HP cylinder up to 100 psi.

Second case, the main steam pressure was 150 psi, they cracked open the throttle valve to bring the pressure gauge of the HP cylinder up to 100 psi.

Would both cases yield the same rpm for the engine ?
 

Jim Currie

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While on the subject of 29 boilers pressure which the system is design to run at 215psi.
However that's is a requirement from the fireman or some time know as the black gang to check out each boiler for the correct pressure at 215psi.
The question I ask at what stage when there drop in psi pressure do the firemen add more coal?
1622203389975.png
As Sam advised, read the article
Another question,

First case, the main steam pressure was 215 psi, they cracked open the throttle valve to bring the pressure gauge of the HP cylinder up to 100 psi.

Second case, the main steam pressure was 150 psi, they cracked open the throttle valve to bring the pressure gauge of the HP cylinder up to 100 psi.

Would both cases yield the same rpm for the engine ?
 
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Jim Currie

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Another question,

First case, the main steam pressure was 215 psi, they cracked open the throttle valve to bring the pressure gauge of the HP cylinder up to 100 psi.

Second case, the main steam pressure was 150 psi, they cracked open the throttle valve to bring the pressure gauge of the HP cylinder up to 100 psi.

Would both cases yield the same rpm for the engine ?
The upper cylinder in both cases would contain a fixed volume of steam at whatever the inlet pressure was.
The throttle - as is the case in all engines - was opened to produce the desired number of engine rpm which was equivalent to the desired speed.
 

Mike Spooner

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I have looked into the history of Kilroy fireman/stoker indicator regulator gauge and can see why it was invented in the first place. As ship technology moved on with the use of multi boilers and in different boiler rooms things get a lot more complicated in controlling the equal performance of each boiler.
As if we had a ship with just one boiler per engine that is quit straight forward for a fireman/stoker to keep an eye on the pressure and heat. As with Titanic 29 boilers in 6 boiler rooms that now comes a problem to make sure each boiler is performing to the same level. Where a Mr Kilroy comes up with quite a clever idea by putting a time clock for each boiler when requires attention. With the large boilers port entry for the coal three in the front and three at the back, and never have the back or front port open at the same time for each boiler. Add to the problem of different boiler rooms to. Kilroy was smart enough to add a buzzer and a light to, due to the roaring noise of the boilers.
1. (Just a matter of interest do we know what the decibel reading were?
2. I still ask the question where was the pressure and heat temperature gauge placed on each boiler? As for a fireman when is the time to put more coal in and can see the boiler is up to the correct pressure and temperature why bother to add more coal!
3. As for Titanic with 24 boilers in operation I see 12 boilers will power each engine. If there is 12 steam pipes from the boilers into one for the high pressure cylinder. Was there a check valves or non return valves to prevent the steam entering back into the other boilers?
4. Then there is the in balance of boilers of having 5 per room. Or is it just the case the fifth boiler is used alternative per room for each engine?
 

Jim Currie

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I have looked into the history of Kilroy fireman/stoker indicator regulator gauge and can see why it was invented in the first place. As ship technology moved on with the use of multi boilers and in different boiler rooms things get a lot more complicated in controlling the equal performance of each boiler.
As if we had a ship with just one boiler per engine that is quit straight forward for a fireman/stoker to keep an eye on the pressure and heat. As with Titanic 29 boilers in 6 boiler rooms that now comes a problem to make sure each boiler is performing to the same level. Where a Mr Kilroy comes up with quite a clever idea by putting a time clock for each boiler when requires attention. With the large boilers port entry for the coal three in the front and three at the back, and never have the back or front port open at the same time for each boiler. Add to the problem of different boiler rooms to. Kilroy was smart enough to add a buzzer and a light to, due to the roaring noise of the boilers.
1. (Just a matter of interest do we know what the decibel reading were?
2. I still ask the question where was the pressure and heat temperature gauge placed on each boiler? As for a fireman when is the time to put more coal in and can see the boiler is up to the correct pressure and temperature why bother to add more coal!
3. As for Titanic with 24 boilers in operation I see 12 boilers will power each engine. If there is 12 steam pipes from the boilers into one for the high pressure cylinder. Was there a check valves or non return valves to prevent the steam entering back into the other boilers?
4. Then there is the in balance of boilers of having 5 per room. Or is it just the case the fifth boiler is used alternative per room for each engine?
1622290738954.png
 
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