Is it possible to run an Antminer S9 on a 250v NEMA 10-30?
There are only 2 ways to hook this power supply up. 


120V line (either line) to neutral.  This would use the standard, common  NEMA 5-15 connector, you know the one. 
240V line to line. (akin to using only +12 and -12 for a 24V load).  Neutral is not used on this configuration, it doesn't even need to be wired to the receptacle. The proper connector is NEMA 6. This power supply will give 1600W of power on this config. 


Equipment safety ground is not comparable to electronics GND. Code requires it today, and it does two things for you: helps fight ESD, and helps prevent electrocutions.  A GFCI/RCD actually does a better job of the latter, but does nothing for ESD. 

Getting a ground

This is such a super good idea I assume you'll find a way.   Open up the box and look at the cable.  

If the neutral is a bare wire or bunch of bare strands surrounding the conductors, permanently reassign it to be ground instead of neutral.  Neutral and ground are tied in the main panel... but if it's a sub-panel, move the bare wire from the neutral bus to the ground bus.  This is one-way; converting it back to neutral violates code.  

If the neutral is a white wire, look and see if there's not already a ground wire in there. In 1993, maybe.  Otherwise Code now permits you to retrofit a ground wire, minimum #10 size, green or bare, via any workable route back to the panel.  Enter via a knockout and use a proper cable clamp.  #10 to be compatible with future dryer use, so you don't fail inspection when you sell the home. 

You can never retrofit neutral.

Wiring it up if only this plugs in here

Keeping in mind it will hurt your resale value if you can't roll it back to a dryer outlet. 

Get a NEMA 6-15 dual receptacle, correct box lid and cover plate.  Attach hot1, hot2 and ground to it. The dual sockets are for code compliance or a second server. 

You must also change the 30A breaker to a 20A breaker.  Normally socket amperage must match the breaker (hence not 30A) but there is a special exception for 15A sockets that makes multiples of them legal on a 20A breaker. 



Yup, same form-factor.  This a dual 6-15. 

If the dryer needs to function too

You must have neutral and ground.  Change the receptacle and dryer cord to NEMA 14-30, which will make your family safer too.   Remember to remove the neutral-ground tie on the dryer. 

Several options.  


Ask the Code geeks on diy.se whether you can really put a 30A plug on a 1600W server.  I don't think you can.  If you can't... 
Install a subpanel.  Get at least an 8-space subpanel rated 30A or more, no "main" breaker required.  One 30A 2-pole breaker goes to a NEMA 14-30 for the dryer, wired with #10 wire.  A 20A 2-pole goes to the NEMA 6-15 dual as described above, wired with #12. The rest are for expansion, as you can put up to 24A continuous on this panel.  (Continuous loads count as 125% of their actual measured draw.) 
connect a UL-listed PDU that is rated for 30A or more.  It must be installed according to its instructions, but fit a NEMA 6-30 or 14-30 plug if that is allowed.


If you want to use an L6-30, same deal as 6-30, the "L" means twist-lock.   Ditto L14-30.