Originally posted by chacowako
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How to turn plastic waste into diesel fuel cheaply
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Plastic Extruder
Gentleman
I have been away from my project for some time, I'v decided to make an automatic feed for the Plastic feedstock.
My retort has diesal burner blowing into a spiral bound system outside the. retort.
i was thinking of using the exhaust to heat the Plastic Feeder through a screw type mechanism .
Q's
1. can anyone supply a simple drawing of how to design a system,
The real query here is would I need to heat the Funnel feeding the extruder or just concentrate on heating the extruder element
2. Would I require a non return valve in case the feeder is running empty to stop The vapour stream entering the Feeder? If so any further suggestion's would be appreciated.
3. Would there be any problems of overheating the Feeder using the exhaust gases, how could we control the temperature- a manual/automatic wastegate ? or not required
4. Last question does anybody have any simple ideas of developing a plastic shredder ?
Thankyou
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Very dangerous ground. If you can not work out the design and issues yourself, do not attempt it.Originally posted by dippy909 View PostGentleman
I have been away from my project for some time, I'v decided to make an automatic feed for the Plastic feedstock.
My retort has diesal burner blowing into a spiral bound system outside the. retort.
i was thinking of using the exhaust to heat the Plastic Feeder through a screw type mechanism .
Q's
1. can anyone supply a simple drawing of how to design a system,
The real query here is would I need to heat the Funnel feeding the extruder or just concentrate on heating the extruder element
2. Would I require a non return valve in case the feeder is running empty to stop The vapour stream entering the Feeder? If so any further suggestion's would be appreciated.
3. Would there be any problems of overheating the Feeder using the exhaust gases, how could we control the temperature- a manual/automatic wastegate ? or not required
4. Last question does anybody have any simple ideas of developing a plastic shredder ?
Thankyou

You need a very specially designed screw/auger. You need to be able to expel all oxygen that went into the feed with the plastic particles. You have to be able to contain all the gasses produced, as the screw heats the plastic as it gets closer to the Retort. It requires some well designed, highly engineered and complex controlled machinery.
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I doubt it. I am using 30Kw to heat a vessel just a fraction of that size. It takes a specific amount of energy per Kg to Pyrolyze Plastics and do that efficiently. The amount of energy varies between plastic types, but it takes the following just to melt these Plastics. It takes even more energy to take plastic right through to Pyrolysis.Originally posted by kedigen View Postreactor of 330 cm height. 127 cm diameter. Does 45 kW resistance enough?
HDPE= 250,000 J/kg
LDPE= 200,000 J/kg
You also have to take into account the Steel the vessel is made from. That has to be heated to temperature first. That takes energy as well and then you havr to take into account the amount of steel exposed to Air. This is where heat will transfer and escape and that heat must be replaced all the time. The bigger you go, the more chance of loss and the heat required to do the job has to increase exponentially. This is because Area/Volume increases exponentially.
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I thought i should clarify that last statement. I meant how thick the Steel is, which will be mass and mass will take time to heat to temperature.HDPE= 250,000 J/kg
LDPE= 200,000 J/kg
You also have to take into account the Steel the vessel is made from.
Also, this formula may help for you to work out the energy required.
P(W) = E(J) / t(s)
So,
watt = joule / second
or,
W = J / s
To work out how many Watts you will need for a Minute, x the Sum by 60 and then 60 again if you want the Sum per hr. Per hr would be helpful to work out against the amount of plastic you are wanting to process per hr. You would want a Heat source with more output than what you work out in theory, because there will be some variables. Like how much moisture is in the plastic, in the air, Air temp, Steel thickness, heat loss through insulation, heat loss traveling through pipe work with Hydrocarbon vapors and heat loss due to inefficiency of heat transfer, which you will have escape out through the Flu.
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Yes you can mix the two, but why?? What are you trying to achieve? Activated Carbon acts purely a "Filter". It does not act as a Catalyst. Zeolite can also be used as a filter in certain situations and in specific ways of use, but more commonly, it is used as a Catalyst. And in saying that, it is a particular type of Zeolite that tends to work the best as that Catalyst, although any of the other Zeolites will do better than nothing.Originally posted by chacowako View Postcan you mix activated carbon and zeolite?
would the zeolite become useless?
The next question that needs asking is, what is happening to your end product that you think you may need a catalyst?
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Early on, Jetijs discovered that waxing occurred when the reflux temperature was allowed to run too high. The retort temperature should be at a point where the contents is simmering in a controlled fashion and not too vigorous. The reflux should be at a point belowOriginally posted by Piet View PostCan anybody tell me at what temperature wax is made and and what temperature diesel is made either in the retort or reflux.
Thanks, Piet.
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I am doing a bit of guessing here, but wax may possibly be the wrong description. It is possible that another thing is taking place causing the liquid to solidify. This idea came about from Excalibur and I discussing a slightly different situation and he discovered that a particular Hydrocarbon when at room temperature, existed in a solid crystal form. It did not melt to a liquid till 70degC. I made a comment then, "I wonder what that does to the other liquids once the temperature drops below 70Deg". I am sorry I have forgotten the name of the Hydrocarbon, so Excalibur, can you remind me again please?Originally posted by Excalibur View PostEarly on, Jetijs discovered that waxing occurred when the reflux temperature was allowed to run too high. The retort temperature should be at a point where the contents is simmering in a controlled fashion and not too vigorous. The reflux should be at a point below
Anyway, what surprised me was that this Hydrocarbon is a short chain one. These very short chains can be formed by the types of Plastic's and to high a temperature causing over cracking. Cracking is caused by anyone or a combination of.... Heat, Time in the Retort, what weights are cycled back from reflux and Catalyst. So if the desired end product is wanted as a Diesel weight Fuel, then it is quite possible that the Plastics are being "overcooked" in the process. Hence jetji's comment about having a waxing problem at high temps. It is possible that a high proportion of this crystal form of Hydrocarbon is causing the liquid to solidify to a consistency of wax.
A lot of trial and error maybe required, but I suggest changing a few of the processes. Firstly, as it is desirable to have the process go as fast and efficiently as possible, plus we don't all have perfect heat control, I suggest that perhaps the removal of the catalyst (if one is used) be tried first. Second, the temperature of the reflux vessel is possibly more important than the Retort temp. But it is possible the temperature may need to be varied either up or down. That is going to be a little trial and error. Temperature of reflux will affect the weight of fractions sent back to retort as well as what continues on through the system, as well as time the Hydrocarbons remain within the Reflux vessel. Any vessel that is heated will affect Hydrocarbons that have a Boiling point below that heated Vessel temp. Once Fractions are heated to above boiling point, they can under go cracking. Obviously the hotter the temp, the more likely a chain will crack.
This is however, just an idea. I could be wrong, but most certainly if you are having a waxing problem, then try changing a few of the suggestions and report back on what was found.
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Dear friends
is any one utilizing uncondensed (remaining) gases in a diffferent manner that means other then heating the retort like to produce electricity or any other novel idea
all in advance
Last edited by sunilkm153; 11-10-2014, 05:23 PM.
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