Drive System for a Ship Elevator/Lift

Well, at least you were honest this time:

http://cr4.globalspec.com/thread/108397/Need-Help-Selecting-A-Motor-Type

Yeah sorry about my first post

The Three Gorges lift took a team of specialists many months to design, it is state of the art....are you trying to improve their design? Are you trying to copy their design? In either case you are wasting your time here, you should take a tour of the dam, or call the design firm...

Based on the information above, an internal University design project, assumed NOT to be a real world job under construction.

The Falkirk Wheel is an elegant design. The 2 locks that hold the vessels are full of water & always balanced. Any vessel entering the lock displaces it's own mass in water to maintain equilibrium. The drive motor used to rotate the wheel is tiny as it only has to overcome inertia & friction.

Yes, I watched a documentary on it which is why I singled it out especially. The tiny motor allowed by the simple balance system showed that you could move a ship quickly and efficiently.

The Falkirk Wheel is beautiful; both aesthetically and from an engineering point of view - their website reckons the power to boil the water in 8 kettles is enough for the half revolution for a trip top to bottom which is just inspired engineering.

However the proposition in this case is far larger 3 x the height and more then 6 x the weight (the wheel has a combined water and boat of 500 tonne) so the sheer size of the arms for 20x the leverage is going to be enormous and the space required for that size of revolution.

But I have to say I would absolutely LOVE to see a Falkirk Wheel of that size.

I agree,the Falkirk Wheel is a stroke of genius.

So why not use a series of them,like a gear train, each handing off to the next one in line?

Imagine two or more Falkirk Wheels,each offloading into the next one.

This would reduce the weight and size of the materials used,each one carrying only it's share of the load.

They could be arranged in parallel or at right angles to each when required to save space.

The complexity would be simple,as in the original,just repetitive.

The energy used would still be minimal.

The original poster mentioned the magic words "There is no limitation to the cost", making almost anything possible (although probably not practical).

The general idea of my post though was to inspire with different ways of doing something rather than say produce a direct copy.

Vertical lifts are by no means as common as your reference suggests. In the UK the majority of the lifts are in fact boat slides, going up a ramp rather than vertically. The Anderton boat lift and the Falkirk wheel both use two boat-carrying caissons, each counterweighting the other, so that the total power required is quite small.

Maybe this will give some ideas.

The Three Gorges Dam works by controlling the flow of water in the Yangtse from one level to another to provide the lift, the same in principle as any other canal lock that has ever been built only on a much grander scale than anything else on the planet. Motors are employed there to raise and lower the paddles that control the flow of water in and put of the chambers, and to move the lock gates; they do not raise the vessels in themselves. There is certainly enough water available to lift ships as in addition to that function, the facility also provides something approaching 2% of China's electricity supply!

A visit to the Three Gorges Dam installation will certainly impress. There again, any visit to a canal lock anywhere in the world will probably provide the same fascination. The basic technology is over 200 years old, and certainly predates the invention of the motor.

Google "how does a canal lock work?" for more information.

The Three Gorges Dam has both lifts and locks. The main route for shipping is a series of 5 locks of the classic design (but just breath takingly enormous)

There are also two ship lifts (different sizes) which do the whole thing in one step. These sadly were not completed when I did my Yangtze cruise. The smaller lift was close to commissioning but essentially a vessel goes into a box which is raised and lowered mechanically (or possibly using hydraulics as I said there was no information available at the time I went). Even the larger ship lift only takes ships maybe 10% the size of those that use the main lock system.

When reading the assignment, I immediately thought of the Falkirk wheel, so GA to this already mentioned.

Simple and elegant, not necessarily cheap.

Some "operating constraints" however are of concern. "Operate at minum 30 deg C" might be a bit of an isue. I do not have experience in that area except chamber testing for automotive components. I think the water viscosity might be problematic.

Since seawater freezes at minus 2 deg C, it will be a difficult engineering challenge to raise or lower any ship into minus 30 deg C ice.

Still possible but you have to allow for the huge block of ice that goes with it.

<...temperature range Minimum: -30 degrees celsius...> will prove problematic, as water is actually solid at those sorts of temperatures.

<...a hoisting system where there are four drums with ropes...> does not equate to <...similar to the new three gorge dam design...>.

Drums with ropes are actually used in ship salvage operations to slice the sunken vessels into manageable pieces that can be towed away for scrapping!

Doesn't it rather depend on whether there is a balancing counterweight, i.e. as one chamber is going up, the other is going down (rhetorical question - NNTR)? 3000T of ship plus, say 5000T of chamber and say 5000T of water, going against gravity at 110 meters per hour is a power of.....er......tap...tap....tap....press equals......nearly 4 megawatts not including friction and efficiency losses. That figure could be greatly reduced by counterbalancing, and virtually eliminated either by using a lock system or by making one chamber heavier than the other in some way [hint - transfer water from the upper level to the lower].

So, before sizing the motor, the mechanical design has to be on the table. Only, it isn't.

If one were doing this in real life, one would start with the "as built" drawings for the existing one, and utilise current operating experience to develop the design for the next one. However, it is likely to depend upon local terrain as to what will fit, and what won't, and the design will follow from that. The thing about the Three Gorges Dam is that the terrain and geology is specific to that location. If one were building it again, one would utilise as much of the existing dam as possible. However, for this hypothetical design, there is no hint of the traffic to be accommodated nor the terrain through which it has to pass...

Three Gorges Dam.

Foxton Inclined Plane.

have you considered something like this:

https://www.youtube.com/watch?v=_tBH9SE-Kw8

https://en.wikipedia.org/wiki/Falkirk_Wheel

The beauty of this design is that it does not require a huge motor because it is always balanced. The tonnage in each arm is always equal to the (equivalent) water mass which is set purely by the depth. Ship size and tonnage (as long as it is floating) does not matter.

In addition to all the points well made in previous posts, engineering a project like this for a life span of only 30 years is absolutely ridiculous. From a practical point of view I would say it should be at least 50 years, but then what do I know compared to the course designers!

why not use locks, as in the Panama Canal?

LINK

Time. Lift is much quicker, from website in #15

We have thought about using a canal lock system but from all the existing designs it is much slower than a vertical lift, since the ship has to be lifted from upstream to downstream and vice versa within 1 hour

Ok so a bit more digging reveals that your professor has just copied the specs for the Ship Lift at the Three Gorges dam

The locks take 4 hrs to traverse

http://probeinternational.org/library/wp-content/uploads/2011/01/Ship-lift-at-Three-Gorges-Dam-China-design-of-steel-structures.pdf

The lift is still under construction! The size for the lift is designed for the cruise ships to speed up their transit (OK so I am a geek and I loved passing through the lock system) and to get them out of the locks so that they can be used for freight.

The Falkirk Wheel idea is not feasible due to space

IMHO you are looking at two key issues

Safety - under no circumstances can you drop the lift so a simple cable is a non starter - worm gear and toothed wheel I think are fail safe in this manner. The Three Gorges solution is LOTS of cables and counterweights so failure of one is not catastrophic

Power - Counterweights reduce power; cables v tooth gear reduces power (I think - less friction)

Enjoy

Acceleration load is likely to be quite significant, even if weight balancing is nearly perfect.