Ben,
That makes a lot of sense. I didn't realize that there was a reasonable
pressure at which LN2s boiling point was above the freezing point of LNG.
Very clever.
Did they design the inner tank to be able to take crush loads where it was
unpressurized and the outer tank was at MEOP?
~Jon
On Mon, Jan 4, 2016 at 5:46 PM, Ben Brockert <wikkit@xxxxxxxxx> wrote:
[Replying to a thread from 8 years ago like a normal person]
On Thu, Mar 13, 2008 at 11:58 PM, Jonathan Goff <jongoff@xxxxxxxxx> wrote:
It should still be possible to liquefy natural gas using liquid
nitrogen, though it'd take quite a while at the usual commercial feed
pressure.
At least according to some of the guys at XCOR, they did just that,
and it ended up being a royal pain in the backside. IIRC, it was very
easy to accidentally freeze the methane instead of just liquifying it.
I visited the propulsion lab at Purdue last year and they had run a
LOX/CH4 propulsion test program off methane they liquefied from a
natural gas line. Their very clever trick was that they had a dual
walled, insulated liquefaction vessel. Inside was gas turning to
liquid, cooled by liquid nitrogen. The clever part of the trick was
that they kept the liquid nitrogen pressure far enough above
atmospheric via a relief valve that its boiling temperature was above
the freezing point of methane. So the natural gas would liquefy, not
turn into a methane plug in a heat exchanger as Randall complained
elsewhere in this thread.
Their other clever trick is that they have a bunch of students who can
be assigned to do boring shit like monitoring the methane condenser,
which is similar to paint drying in reverse.
(Also relevant to the personal perspective of safety of propellant
handling discussion from today, a professor there thought that it was
needlessly reckless that Armadillo didn't do all of their propellant
transfers remotely. I don't actually know of any small newspace
companies that do nontoxic propellant transfer as a fully remote
activity. LOX is really not that scary.)
Ben
