Liquid Expanders

[Zoobie]

I have some questions about the use and practicality of liquid expanders. The particular application would be to replace a valve at the bottom liquids outlet of a separator with an expander to recover the power (this is in a cryogenic natural gas extraction plant). The pressure drop is about 500 psi and I estimate the amount of power available to be somewhere between 200-300 hp. I am having a vendor provide me with budget numbers but I know that these devices are not very common (at least in this application).

Are there reasons for not using an expander besides possibly high capital costs? Is it difficult to integrate the power produced into the plant's power system (I was planning to use to power to operate smaller 600 V motors)? Our gas turbo-expander is virtually trouble free and a breeze to operate...how does a liquid expander compare?

I would appreciate any comments from people with experience with these devices.

Thx

 

[Leclerc]

liquid expander? Usually liquids are virtually incompressible.

 

[Zoobie]

True. It can be thought of as a pump running backwards (though a bit fancier). As I stated in my original post, they are not very common, but they do exist...well at least in literature.

 

[rmw]

We can get hung up on terminology, but the concept that you are seeking information on has been dealt with in this forum. Do a search on hydro turbines as a starter.

rmw

 

[cub3bead]

This may not be an exact fit for your application but look at Pump Engineering web page

http://www.pumpengineering.com/

I am familiar with them for energy recovery in RO systems but they have branched out into energy recovery in other processing equipment.

 

[Zoobie]

cub3bead,

Thanks. Their devices look just like what I was looking for and they have some gas plant installations (albeit in amine units).

I'm still interested though in anyone's perspective from the end user side of things.