• Sealed system
  
• Constant low pressure, but with simple, safe overpressure release ability.
  
• Inert environment
  
• Self extinguishing in event of leak
  
• Visible gas volume available, won't run out unexpectedly
  
• Visible gas volume - any leak would be apparent
  
• Minimal usage of inert gas - costs/wastage kept low
  

quote:

Originally posted by producer:
My results suggest that a 5% prewash is a must in order to MAINTAIN high conversion BD. The prewash pulls most of the glycerol out of the BD before the methanol recovery stage. Any dissolved glycerol that remains in the BD after settling tends to drive the reaction in reverse during methanol recovery.

With that in mind I think I will use the hardest water I can fine for the prewash. I want the soap to become insoluble and sticky. If it is sticky, it may pull even more glycerol out during settling.

And, insoluble soaps would still be captured in an ion exchange filter, it one were using such an item.

Just a theory, but I think I will try it. If I do, then I will report results.

quote:

Originally posted by producer:
.... The operating temperature of the biodiesel can be increased or the temperature in the condenser can be reduced. Either will result in more methanol recovery. But, the maximum methanol recovery will be based on the methanol saturation limit at the operating temperature inside the condenser.

I modified my system with an additional valve not shown in GL's plans (which I used as my guide). The valve opens to the atmosphere and is located between the condenser and the reactor. I open the valve and pull fresh air into the system right at the end of the methanol recovery cycle when, virtually, no more methanol is being captured. The movement of the unsaturated air into the reactor headspace picks up methanol vapor. This air then passes through the condenser and out the vent line to the outside atmosphere. This allows me to achieve very, very low levels of methanol in the biodiesel.

quote:

Originally posted by Dave Calkins:
. . . it travels through the venturi which creates a pressure change in the air / fluid mixture which also facilitates the removal of the methanol from the BD.

quote:

Originally posted by GrahamLaming:
Hi Jim

CO2 would be fine too.

Here's a thought for you to ponder ... super-low vapour release system with in-built fire extinguisher ...

...mini gasometer on oil. ... constant low pressure less than 1 psi (pressure in psi = floating cap weight in pounds, divided by the surface area of the cap lid in square inches), variable volume as the thermal expansion takes effect, minimal loss of gas or methanol vapour, no route in for oxygen.






The gasometer would be tapped to the outlet of the condenser to minimise high pressure (hot) Methanol vapours from entering the gasometer and causing it to burp.

Purge reactor first, then connect to gasometer full of N or CO2. Not on water, or the CO2 will dissolve, and if using N, the water may freeze in winter.

Advantages:-

• Sealed system
  
• Constant low pressure, but with simple, safe overpressure release ability.
  
• Inert environment
  
• Self extinguishing in event of leak
  
• Visible gas volume available, won't run out unexpectedly
  
• Visible gas volume - any leak would be apparent
  
• Minimal usage of inert gas - costs/wastage kept low
  

Mount it outside.

The bottom skirt of the cap can have vee-notches to allow stable, graduated release of over-pressure (in the unlikely event), without causing a big turbulent burp. (which would happen if the skirt were made of simple continuous sheet.)

Procedure for minimal oxygen exposure / minimal methanol release / minimal use of inert gas:-
(Using the EcoSystem processing method)

1. Ensure gasometer is full of inert gas, then shut valve from N tank to gasometer.
2. Fill reactor TO THE BRIM with oil.
3. Shut all vents, and open valve connecting gasometer to reactor via condenser.
4. Drain oil to required processing amount. (this draws nitrogen in, from gasometer)
5. Continue with reaction steps and process.
6. After reaction/methanol removal from biodiesel, pump extra biodiesel into reactor until BRIM FULL.
7. Close valve joining reactor to gasometer (which should now be full again, for re-use next batch)
8. Drain biodiesel for settling / soap removal.

quote:

Originally posted by Spencnaz:
No the low pressure area is just downstream of the throat of the venturi.