Difference between revisions of "Importance of venting a processor"

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<span style="color:red">This page will soon be completed by Mark following an intensive and extensive wiki lesson.
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==Introduction==
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It is imperative that all Biodiesel processors be vented safely to atmosphere via an un-valved pipe.  All the processor designs shown on this wiki are vented. 
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A vent will not mitigate an explosion.  The generation of gas in an explosion is far too rapid for the vent to cope.
  
Only if I was paying attention Julian.</span>
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The vent is designed to allow air to be displaced when filling with oil, adding Methoxide or to be entrained into the processor when pumping out finished Biodiesel.  It will also allow the contents to safely expand and contract when heating and cooling.
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Heh well done so far Mark - Tony :)
 
  
Thanks Tony.
 
  
looking good mark keep up the good work! :) weeeeeeeeeeee
 
  
funky kingston
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==Simple vents==
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[[File:Appleseed_processor_schematic.png|250px|thumb|right|Vented path direct from processor tank shown in red.]]
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On a processor without methanol recovery i.e. no vapour circuit, the vent can be a simple small bore pipe with no valves from the ullage space of the processor, leading outside and terminating safely as far away from human contact as possible. 
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On the Appleseed processor, right, there is an additional vent which incorporates a relief valve which would operate in the event of the main vent becoming blocked.
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==Introduction==
 
  
  
[[File:Fan and circuit dia.png|right|]]
 
  
All processors shown in the pages must be vented to allow air to be displaced/replaced when oil/bio is added to or removed from the vessel.
 
  
It is important that the vent does not have a valve on it as it '''must''' stay open at all times.
 
  
The way the vent system works is the vapour is pulled out of the reactor by the venturi, through the condenser and back to the venturi.
 
So the vapour circulated around the system and is not under any pressure. 
 
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The vent on a GL is normally on the vapour line (highlighted in red) after the condenser, this way any methanol fumes that are released during the reaction,or in the de-meth stage, will get condensed off and collected in the Methanol collection vessel.
 
  
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Only non flexible pipe should be used in the vent system.
 
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[[File:GL processor with vent path in red.png]]
 
  
  
  
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==Vents on a GL type processor==
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[[File:GL processor with vent path in red.png|400px|thumb|right|Vented path for processor shown in red.]]
  
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Whilst it's possible to vent a GL type processor, direct from the tank, it is more ecologically beneficial to install the vent on the vapour line, after the condenser (highlighted in red in the top graphic). This way any methanol fumes that are released during the reaction, or in the de-meth stage, will get condensed off and collected instead of being released to atmosphere.
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[[File:Fan and circuit dia.png|150px|thumb|left]]
  
==Consequences==
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Because the vent is on the vapour circuit, one of the most commonly asked questions is why doesn't the venturi blow vapour from the vent. The answer is best described by the diagram below where the fan is located in a chamber. It blows the same volume of air out of the chamber to the left, as it sucks in from the right, so it creates a circulation. There is no vacuum or pressure in the circuit, therefore no air sucks in through, or blows out of, the vent.
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The theory is exactly the same in the processor, except in place of a fan you have a venturi (far safer as there are no moving parts). The only time air will come out of the vent is when you add oil or Methoxide to the processor or when the oil and air expand whilst heated. Similarly when you drain glycerol or pump out the finished biodiesel, the vent will suck air back in.
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===Negative pressure===
 
  
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On any vent arrangement, the safest material to use is rigid pipe, preferably metal.  Soft flexible pipe work can kink or be flattened by things leaning against it and are also susceptible to the effects of heat, compounding other issues.
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==Consequences==
  
If the vent becomes blocked it can produce a build up of positive or negative pressure.
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If the vent becomes blocked a build up of positive or negative pressure can occur.  This will have sever effects on the most vunerable part of the system, namely the reactor tank.
  
This can have sever effects on the reactor itself.
 
  
Negative pressure can and will cause the reactor to implode as seen in these pictures.
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===Negative pressure===
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As seen in these pictures negative pressure can and will cause the reactor to implode .  This is due to the atmospheric pressure on the out side of the tank pushing inwards.
  
  
<gallery caption="This is a steel, cone bottomed drum" widths="300px" heights="300px" perrow="3">
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<gallery caption="This is a steel, cone bottomed drum" widths="250px" heights="200px" perrow="3">
 
File:Collapsed processor 1.jpg|Reactor still with insulation on.
 
File:Collapsed processor 1.jpg|Reactor still with insulation on.
 
File:Imploded-reactor-3.jpg|With the insulation removed you can see just how damaged it is.
 
File:Imploded-reactor-3.jpg|With the insulation removed you can see just how damaged it is.
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These photos were supplied by Baseaddict.
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These photos were supplied by BassAddict.
The reason his reactor imploded was he had used flexible hose for his vent, this got a small restriction in it and the negative pressure created when the bio was pumped out collapsed the vent pipe sealing the vent.
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The reason his reactor imploded was he had used flexible hose for his vent, this got a small restriction in it and the negative pressure
This is why we advocate using non flexible pipe for the vents.
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created when the bio was pumped out collapsed the pipe sealing the vent.
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This is why we advocate using rigid pipe for the vents.
  
  
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The most likely way to produce positive pressure in a GL is by pumping oil into it with a closed vent, although in most cases it is unlikely the pump will produce enough pressure to cause a problem.
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The most likely way to produce positive pressure in a GL is by pumping oil into it with a closed vent, although in most cases it is unlikely
  
However if a reactor full of cold oil was heated with a closed vent this could build up a surprising amount of pressure.
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the pump will produce enough pressure to cause a problem.
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However, if a reactor full of cold oil was heated with a closed vent this could build up a surprising amount of pressure.
  
 
It is possible the the reactor or pipework could rupture, but an explosion is highly unlikely in this scenario.
 
It is possible the the reactor or pipework could rupture, but an explosion is highly unlikely in this scenario.
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[[Category:Biodiesel]]
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[[Category:Processors and equipment]]

Revision as of 22:03, 3 February 2013

Introduction

It is imperative that all Biodiesel processors be vented safely to atmosphere via an un-valved pipe. All the processor designs shown on this wiki are vented.

A vent will not mitigate an explosion. The generation of gas in an explosion is far too rapid for the vent to cope.

The vent is designed to allow air to be displaced when filling with oil, adding Methoxide or to be entrained into the processor when pumping out finished Biodiesel. It will also allow the contents to safely expand and contract when heating and cooling.



Simple vents

Vented path direct from processor tank shown in red.

On a processor without methanol recovery i.e. no vapour circuit, the vent can be a simple small bore pipe with no valves from the ullage space of the processor, leading outside and terminating safely as far away from human contact as possible.

On the Appleseed processor, right, there is an additional vent which incorporates a relief valve which would operate in the event of the main vent becoming blocked.
















Vents on a GL type processor

Vented path for processor shown in red.

Whilst it's possible to vent a GL type processor, direct from the tank, it is more ecologically beneficial to install the vent on the vapour line, after the condenser (highlighted in red in the top graphic). This way any methanol fumes that are released during the reaction, or in the de-meth stage, will get condensed off and collected instead of being released to atmosphere.

Fan and circuit dia.png

Because the vent is on the vapour circuit, one of the most commonly asked questions is why doesn't the venturi blow vapour from the vent. The answer is best described by the diagram below where the fan is located in a chamber. It blows the same volume of air out of the chamber to the left, as it sucks in from the right, so it creates a circulation. There is no vacuum or pressure in the circuit, therefore no air sucks in through, or blows out of, the vent. The theory is exactly the same in the processor, except in place of a fan you have a venturi (far safer as there are no moving parts). The only time air will come out of the vent is when you add oil or Methoxide to the processor or when the oil and air expand whilst heated. Similarly when you drain glycerol or pump out the finished biodiesel, the vent will suck air back in.


On any vent arrangement, the safest material to use is rigid pipe, preferably metal. Soft flexible pipe work can kink or be flattened by things leaning against it and are also susceptible to the effects of heat, compounding other issues.




Consequences

If the vent becomes blocked a build up of positive or negative pressure can occur. This will have sever effects on the most vunerable part of the system, namely the reactor tank.


Negative pressure

As seen in these pictures negative pressure can and will cause the reactor to implode . This is due to the atmospheric pressure on the out side of the tank pushing inwards.


These photos were supplied by BassAddict. The reason his reactor imploded was he had used flexible hose for his vent, this got a small restriction in it and the negative pressure

created when the bio was pumped out collapsed the pipe sealing the vent. This is why we advocate using rigid pipe for the vents.



Positive pressure

The most likely way to produce positive pressure in a GL is by pumping oil into it with a closed vent, although in most cases it is unlikely

the pump will produce enough pressure to cause a problem.

However, if a reactor full of cold oil was heated with a closed vent this could build up a surprising amount of pressure.

It is possible the the reactor or pipework could rupture, but an explosion is highly unlikely in this scenario.