Steam Engines > Steam engines

Trying to get feedpump right

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JW:
Hi All

Recently I have been working on my steam engine. For any steam engine you need a feed pump, whether driven by the crankshaft or externally It can be difficult to get right.

For my application Im using an injector valve that is fed by a pump(ceramic piston) driven by the crankshaft. The injector valve features variable lift, for throttling.

Volumetric efficiency must be considered so the expansion of water to steam is 1600 to 1.

the displacement of the engine is X volume and the feedpumps volume Y Its an offset that is predictable. so the engine is 2 cups volume whereas the feedump only needs a fraction of that to be introduced by the feedpump.

Every revolution produces water pressure that is then released by the injector.

So what does this calculated volume mean it real terms, gear ratio...

I started using a chain and sprockets, I started the ratio was 4 to 1. This overloaded the pump, so lower gear ratio is easyier on it to If differental volume. Even at 1 to 2 is prefered, remember displacement is fixed at the pump and the engine. Calculate differental displacement and move it 1 to 1. The piston on the feedpump is much smaller than the engine. 

If there is any interested I can post some pictures
 

Frank S:
 Will you have an over pressure bypass on the pump I would think this would be required to prevent over pressure

JW:

--- Quote from: Frank S --- Will you have an over pressure bypass on the pump
--- End quote ---

At the highest point in the water injector circuit there is an (LSA) relief valve. My gauge only goes to 3000psi and pressure is sent from the pump. The relief valve bleeds the circuit.







Target rpm is 650

John Bouchard:
I agree with Frank on being hyper careful on pressure  as I'm sure your already aware of potential hazard's.  I have just a 60psi fermenter and read stories of those blowing  causing injury and property damage can't imagine 3000psi.

JW:
I will just post this picture. This cant not happen When working with a 4 cycle engine because the intake valve cam ensures that both are open in this event valve is open at BDC. In this way the engine cannot explode... 2400PSI

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