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Ok once again confusion get me again.

1. I,ve noticed venturi systems pulling from flash tank through condenser and venturi discharge back into flash tank. (closed loop). This would mean no vacuum?

2. I've also noticed venturi pulling on flash tank through storage tank, then condenser, discharging into air.

3. I've also noticed venturi pulling on flash tank through condenser and discharging into storage tank then into the air.

I was under the impression a vacuum is best to reduce heat needed. So 1, 2, or 3. Maybe even a 4th.

Thanks David
 
Registered: January 04, 2007Reply With QuoteReport This Post
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Ok put is way.

What is a recommended way to recover methanol without it going into the atmosphere.

Heat transfer is easier when there is a higher differential between the two.
Maybe instead of so much interest in heating the source, more interest should be on chilling the destination. Also all applications seam to be "the shorter the time frame the better". For example methanol will eventually evaporate with just ambient temperatures. What if you don't heat source methanol but chill well insulated destination to lets say 32 deg. Put a small vacuum and let it do it's thing 24/7. Just thinking outside the box.
 
Registered: January 04, 2007Reply With QuoteReport This Post
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Hello anyone out there. I guess no one wants to touch this one. I just want to know, circulate or vaccuate?
 
Registered: January 04, 2007Reply With QuoteReport This Post
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Hi David

In the first situation you describe the purpose of the venturi is to create a movement of methanol-laden air through a condenser but not create a vacuum in what you call the "flash tank."

The second situation is to create a vacuum in the "flash tank" and cause methanol to evaporate at a lower pressure than normal.

Have a look at Rick's http://www.make-biodiesel.org/...le&id=111&Itemid=142
 
Location: New Zealand | Registered: August 15, 2006Reply With QuoteReport This Post
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Rick's method recirculates the bio/methanol mix. There is no vacuum. A vacuum means less heat will be needed. Pulling all the time a continuous 24/7 28 hg maintained vacuum from a less heated to no heated large tank of bio/methanol mix will increase evaporation. The problem is the discharge has to go somewhere. Instead of Rick's method It would seem to me implementing vacuum, moderate heat, very very chilled evaporator which would practically eliminate methanol vapor, followed by even a second chilled accumulator, tanked then into the atmosphere. I will experiment and put into action. I will try this with very little electricity. I'll let you know.
 
Registered: January 04, 2007Reply With QuoteReport This Post
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David,

Distillation at atmospheric pressure or distillation at reduced pressure? There has been an ongoing debate for years as to which is more energy efficient. A couple of years ago, the distill at atmosphere crowd came up with an energy balance, that proved to me, their method was more energy efficient. It is here somewhere but I wouldn't know how to tell you to find it.

The usual reason for distilling at reduced pressure is because the stuff being distilled, chemically breaks down at the temperatures required for distillation. One example is glycerin refining. Glycerin starts to break down at the temperatures required to remove the last 10% of water from it. So, when refining glycerin, a multi stage vacuum distillation process is used to remove all the alcohols and water without breaking down the glycerin chemically.

The second most common reason is to take advantage of flash evaporation on a continuous process. You heat your mash really hot, pressurize it, and spray it into the strong vacuum of a 'flash tank'. The stuff left behind has to be pumped out of the "flash tank" while the vacuum is initiated by an expensive vacuum pump and the vacuum maintained by a very efficient condenser, typically operating with chilled water. The system is not cheap.

At one time I considered a vacuum system to be safer because it would suck air rather than blow out toxic vapors. However, when it sucks air, it puts the explosive atmosphere inside the unit rather than outside. Explosive atmosphere inside means more shrapnel when/if it goes boom.

Rick
 
Location: Cowboy Country | Registered: December 06, 2004Reply With QuoteReport This Post



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