6Aug2013 This pic is of the housing in the home workshop lathe. I'm using 3 1/2" silicon or Viton O-rings, which are heat rated for the application.
7Aug2013 Progress! The o-ring grooves are time consuming. The in and out ports yet to be finished.
20Aug2013 I have 3 types of o-ring to trial: Silicon, Viton and Nitrile. The temperature these O-rings will be subjected to ultimately will depend on the diesel condenser reservoir. The chosen method of temperature control is to allow cooling of the vapor stream only once the diesel reservoir has reached the target temp threshold. The plan is to attach a thermistor to the diesel reservoir which opens the water feed solenoid on the heat exchanger, once the required temperature is breached.
2 Sept 2013. TIG welded and finalized. (The bubbler also has a pair of viewing ports).
27Sept2013 I braze welded two 1/4BSP sockets to the diesel reservoir for the level gauge indicator. To avoid overflow with a continuous feed retort, it's important to know how much is going in and how much is coming out.
The level gauge will determine the diesel quantity which can be compared to ingoing feedstock. The 8mm tube material is polyethylene which has a melt point of at least 105*C so careful monitoring will be essential. The tube may need upgrading depending on the target temperature. A ball valve can isolate the tube in case of leakage, etc. The outlet will also be employed for pumping the diesel to the centrifuge.
The polyethylene sight level hose and fittings melted so will be making yet another upgrade.
Admittedly I had the temperature above my target however I'm going to opt for something safer.
Also I'll fit an addition isolation valve at the top so that any failure of sight glass material can be totally controlled, avoiding spillage..
An update to the polycarbonate sight glass pair on the prototype bubbler vessel shows considerable deterioration. Pics show the same window from opposing sides. Temperature to cause this was in the region of 90*C+. The cork gasket sealing surface has shallow etching. Deep adjacent shrink cracking and also very opaque. The material performs OK in the presence of volatile hydrocarbon vapors at somewhat lesser temperatures.
New generation of viewing port for Orions' gas flow indicator is underway. Pic shows Pyrex borosilicate glass cylinder cut to size. It is 82mm x72mm OD x 5mm wall. I used the super-thin diamond wheels in a dremmel. It cut well with a tiny bit of edge chipping only. Regular emery paper (60grit?) on a flat surface was used to dress the cut and give a smooth surface to seal against. The plan is to mount a paddle/blade inside to detect gas movement.
Step 2 is the mounting of an old fan from redundant PC hardware as a flow indicator. The fan windings are removed by peeling away the sticker and prying off a circlip. The housing was trimmed to be a tight fit in the borosilicate glass cylinder. The fan spins very freely on a pair of ball bearings..
The glass is recycled from Spray paint booth lights which use Pyrex covers on the fluorescent tubes as a means of making them explosion proof from the spray vapor. Mine came from scrap metal dealers.
The diesel reservoir is to be replaced with a bigger vessel that is fully seam welded. The old 200L drum vessel is suspected of leaking out of the rolled seam which are only crimped. It is subject to temperatures of up to 120*C so the upgrade is prudent on safety grounds.
The tank is repaired and ready for action. In hindsight I would have been happier with a heavier gauge vessel, perhaps 3mm but this should do OK. I hope to fit a bund as and when a suitable one turns up at a scrap yard.
27Aug2014 A 3way ball valve is fitted directly below the sight glass so that should "boil-over" events occur, they can be diverted to a separate tank. The reject product can be recycled. In this way good diesel will not be spoilt by dirty, uncracked hydrocarbons.