Supercritical state pump 1

[talin9]

What type of pump could be used (helical, *) to act as a one-way isolating valve pumping from a low (800psi) vapor phase to high pressure (1500 psi) supercritical gradient with minimal losses ! Low pressure side is around 70 deg C high pressure side is 110 deg C.

MINIMAL losses regards to competing against the pressure gradient. Flows would be in excess of 20 litres / Sec and around 1.5 Kw energy is available just for overcoming this gradient. More energy could be harnessed:

In a 3 port rotary system I could divert some high pressure in a feedforward sequence provided it was isolated from the low side when cyclically recharging.

Valve budget $1000 in hundreds.

 

[pmover]

your first posting . . .

are you certain a pump is the proper equipment?

what is the fluid and what are the fluid properties at inlet/outlet conditions (given only P & T)?

forum readers cannot completely respond to your question because it lacks sufficient information to provide a response.

otherwise, good luck!
-pmover

 

[talin9]

We have inlet /outlet conditions already explained :
let me re-iterate working the other way - maybe the original writing was lost in some minds:

A supercritial (fluid or very-high density vapor) state is at 1500psi at the outlet of the 'pump' at a temp of 110deg C- in the semiconductor field a pump may be a band-gap junction a tuned cavity as in TWT or even an old klystron, or a tube filled with biphase liquid.

You are free to choose the liquid \ gas - any mixture you feel meets the conditions given which I also conclude the inlet conditions as being a high-density vapor phase at 800 psi and 70 deg C - CO2 happens to be one acceptable .

This is not your simple pump - it must perform like a transistor (with gain) and there is high pressure (1500psi) available to power it. I know a slow rotating 3 lobe system - but there may be a high speed unit like an air motor or radial turbine impellor that can work in a closed loop - albeit 2+ loops, with some (minimal) external power
(gating valves) to overcome pressure locks.

What were you saying about 1st post .... this is a thermodynamics issue - Even WINSIM cannot mathematically cope - so please.... a little lateral thinking

 

[dcasto]

You explaination is clear as mud or you are trying to describe a perpetual motion machine.

If you have 20 liters/second of CO2(at STP) that is 6.7 lb-moles/hour. the energy required to boost the CO2 at a 80% polytropic efficency is 1.621 KW. The discharge temp will be 125 C. a small piston compressor is all you need. It's a simple single stage job.

If you want to let the pressure down from 1500 psi to 800 psi, a piston type would be best for the small volume. Youd have to let down nearly 2twice as much CO2 to get the power required to pump it up.

If you want to see one that might work, go here.

http://www.kimray.com.cn/pdf/G_10.16.pdf

BTW, I built the model in WinSim is under 3 minutes.

 

[talin9]

Thank U dcasto your energy exchange dehydration pumps are the closest approximation to our problem - I noticed your past expert input, and now I can add the missing power source to our project - thermal @ 200 deg C.
The thermal source is finite, thus reduces temp as it is used the mass may easily hold >1 Gj

Ambition is to assemble a closed loop rotary expander with shaft output of 6 KW to harness the thermal mass, thus the power required to pump it up is available.

Question is: the fluid state at higher pressure appears supercritical (higher density) at the inlet of the expander which drives a shaft at the desired 6 KW ( 2 - 6 ) by the pressure difference (drop) X throughput volume, which is expanded - How to best recirculate this pressure reduced output, given I have more high pressure supercritical fluid than I can use with no extra moving parts - I believe cyclic mixing with this high pressure is achievable to reduce external pump up demand. After all the pressures need to be equalized before remixing in the closed loop. Any suggestions ?

 

[dcasto]

a 1 gigajoule of energy is worth less than $15US at a 100% efficient system.

there are some miniture ORC units, here are some small ones.

http://www.turboden.eu/en/products/products-chp.php

http://www.azcentral.com/12news/spe...2009/01/05/20090105greenmotorwebbonus-CR.html

http://infinityturbine.com/ORC/ORC_Waste_Heat_Turbine.html