How to turn plastic waste into diesel fuel cheaply

[Betopty]

free ldpe

And exactly what kind of companies are you talking about, that would LOVE to have someone haul off their plastic bags? I assume this is someone who otherwise is throwing them in a dumpster, and PAYING someone to haul them off.Jim

Mostly large clothes retailers, they receive thousands of single packed items that have to be hung from clotheshangers to be exhibited. This generates literally a daily income of thousands of bags. Even if they are currently paying someone to haul their wastes they will (50-50 chance) give you as much as you can carry, as their haul off will charge them for the dumpster volume, and anything you carry away will not be disposed of.
You just cant be embarased to ask or embarased to be "the garbage guy". These bags are not as interesting to recycle as other plastics, as they usually have to be "densified" (hope that is the correct word) to be pelletized as recycled raw materials. Even so they are preferably remade as lower cost black or grey garbage bags. I believe Depolymerizing them is an excellent alternative if the densifying technology is unavailable.

[tony steinke]

Mostly large clothes retailers, they receive thousands of single packed items that have to be hung from clotheshangers to be exhibited. This generates literally a daily income of thousands of bags. Even if they are currently paying someone to haul their wastes they will (50-50 chance) give you as much as you can carry, as their haul off will charge them for the dumpster volume, and anything you carry away will not be disposed of.
You just cant be embarased to ask or embarased to be "the garbage guy". These bags are not as interesting to recycle as other plastics, as they usually have to be "densified" (hope that is the correct word) to be pelletized as recycled raw materials. Even so they are preferably remade as lower cost black or grey garbage bags. I believe Depolymerizing them is an excellent alternative if the densifying technology is unavailable.

I have attempted to consolidate that type of plastic. It was extremely time consuming, and it takes a whole lot of that type of plastic to generate any kind of real weight. Bear in mind, we need approx. 9 lbs of plastic just to make 1 gallon of fuel. I recently built a baler that will allow me to compact 500 1 gallon milk jugs into a 100 # propane tank. Even all that will only amount to about 75 lbs of stock. Fully solid hdpe weighs about 57 lbs per cubic foot, meaning I could feasibly fit a blob weighing about 225 lbs into that very same tank. I know that Jim had the idea of pre-melting, and it works, but I'm finding it to be more time and energy expended. My point being, that without good heavy stock, or an auger screw feed of sorts, air space seems to be a bit of a dilemma.

[dutchdivco]

Focusing on the challenge

Despite occasional wanderings 'off topic', it seems to me we ARE focusing in on the major challenge of utilising this technology, which is EFFICIENCY.At every stage, finding ways to improve the efficiency.

Starting with aquiring and 'prepping' the plastic; the 'ideal' material would be the pelletised plastic, except for the cost and green considerations.On the other hand, as Tony has pointed out, even tho 'dirty' plastic is 'free for the taking', its not REALLY 'Free'; there is the cost in fuel and labor to collect it, (I have no problem with being the 'garbage man', and going to clothing stores for bags, or restaurants for food containers, but it does require fuel, time and 'labor'. However, again as Tony has pointed out, once you collect this 'free' material, we still need to find some way to EFFICIENTLY 'prep' it for processing.Unlike the pelletised material, it is not in an ideal form; either it needs to be chopped up, or melted, or somehow transformed into a dense form, so that it can easily be loaded into a reactor, and (as much as possible) totally fill up the reactor, to eliminate air space, and for efficient heating.
Stirrers, to mix the plastic, or an auger feed system, would also make for greater efficiency in heating the plastic.And, of coarse ther is finding the most efficient way to heat the plastic.
One of the 'downsides' of this technology, that could possibly be turned into an upside, is the vaporous fuel that is produced; it is bulky to store, and requires a lot of energy to compress in order to store in a practical form. So, using this fuel, as much as possible, for a heat source reduces or eliminates the need to use an external source, or use up the more useable liquid fuels.
Catalysts is certainly an area for additional research, but while an infinetly reusable catalist would be ideal, it seems like a cheap materal that is periodically replaced is practical.
I am kind of likeing the work Jetsis did with the auger feed, which lends itself to a hind of 'preheating' the plastic, in order to get it into a form that is practical for resolving what seems to me to be the major challenge. If a system could be developed, where a hopper is used to melt the plastic, at a high enough temperature to make it liquid/paste, so it could be auger fed into a reactor, while at a low enough temperature that it would actually start pyrolsisis, and if this could be done in a energy efficient manor, this MIGHT 'solve' what seems to me to be the major issue. That is, it wouldn't matter what form the plastic is in, originally. Plastic bags, milk cartons, etc. could just be dumped into the 'hopper', where they would melt, and then be moved via auger into the airtight reactor, where the pyrolisis would take place.
Anyway, this is my thinking at this point. I am still leaning heavily towards burning the vaporous gas in a genset, and using the exhaust to provide the heat for the initial pyrolisis, with electric heaters (running off the genset) to provide the more controlled heat for the various condensers. Wondering if I could get a 'water cooled' genset, and use the 'coolant' water from it, to heat the hopper up enough to melt the plastic? After all, 180F. to 220F. ought to be enough to melt the plastic, without triggering pyrolsis, I would think. Jim

[Betopty]

that without good heavy stock, or an auger screw feed of sorts, air space seems to be a bit of a dilemma.

I fully agree Tony, the material must be fed continuously for the process to be interesting. Also bags tend to burn very easily when heated. Theoretically they would "prefer" to join a pre-plasticized soup and easily melt (not burn) there, once melted they should behave (at least in the plastic industry they do) exactly like solid feedstock. Another possible problem is water. Bags left outside, or moved from an air conditioned retailer to a hot truck tend to develop some moisture. This moisture requires heat to be expended drying the stock so that it will surpass 100oC. My design will attempt to harness flue heat, as well as heat from the cooling condensers to dry/preheat and if possible pre-plasticize or densify the product either for the next batch, or for an auger feeder. I have no idea of pyrolysis as of yet but I've worked with plastics for 20 years.

Here is a question. We are seeing more and more oxobiodigradable or oxodegradable (at least they are called so here) supermarket bags. They have a d2w sign in the space provided for the recycle number.

Anybody have any idea what this might do to the process, does the oxo mean they have oxygen as PETE (PET) does? BAD

Or does the oxo mean they will "eat" oxygen? GOOD
This would make them more desirable to our process to be used as oxygen scavengers, and in this function allowing the use of oxygen providers (such as PET) as one might (in some proportion to be figured out) cancel the other. Even if this weren't an option they could still be used as initial feedstock in a continuous process by vacating the oxygen from the vessel without need for nitrogen, as well as guarantee that the whole system remained oxygen free.

[tony steinke]

So far,I have been unable to melt pe at a temperature less than 320 f. I have read that it can depend specifically on the type of pe, but the lower end of the range is still far above 220 f.

[Asad Farooqui]

My 1000-liter Baby

I fully agree Tony, the material must be fed continuously for the process to be interesting. Also bags tend to burn very easily when heated..

Hello ;
Iam attaching a file for a 1000-liter capacity, designed for my client .
Who want's me to make a pyro unit & than come to USA to commission it with technology transfer .

The flow diagram is self explanatory.
I hope tony,betopty & dutchdivco will get many answers regarding continuously feeding system .

I designed it so that waste PE,PS & also PP-bags of sugar,floor,rice, cement.Which are dumped by many food-processing companies can be fed-In directly without even washing it .

I would like the forum community to comment about it . Specially Jetijs .
Anyone can also e-mail at
[email protected]

[tony steinke]

Betopty, sorry but I haven't a clue as to what d2w means, but my hat is off to you if you can utilize that source. Asad, do you have an idea as to the cost of constructing your design at that scale?

[blackchisel97]

Betopty, sorry but I haven't a clue as to what d2w means, but my hat is off to you if you can utilize that source. Asad, do you have an idea as to the cost of constructing your design at that scale?

D2W is referred top as "controlled life" degradable plastic. I found some info here - Symphony Environmental - What is d2w?



V

[Jetijs]

Looks good Asad
Would you elaborate about how the pre melted plastic is delivered to the main reactor? Is there a feeding mechanism or is it supposed to be free flowing?
Thank you!
Jetijs

Hello ;
Iam attaching a file for a 1000-liter capacity, designed for my client .
Who want's me to make a pyro unit & than come to USA to commission it with technology transfer .

The flow diagram is self explanatory.
I hope tony,betopty & dutchdivco will get many answers regarding continuously feeding system .

I designed it so that waste PE,PS & also PP-bags of sugar,floor,rice, cement.Which are dumped by many food-processing companies can be fed-In directly without even washing it .

I would like the forum community to comment about it . Specially Jetijs .
Anyone can also e-mail at
[email protected]

[Betopty]

I would like the forum community to comment about it . Anyone can also e-mail at
[email protected]

Hi Asad your design looks excelent.
I`ll make a couple suggestions not from the pyrolisis point of view were I know nothing, but from the plastics production point of view.
1.Unless you use some sort of auger feeder system, pressure differential system, I`d doubt you would be able to get the plastic to flow, specially if you are using fracytional melt index plastics such as bags, or blowmolded articles. Fracyional melt indexes (for those of you who do not work with plastics are plastics that are designed not to drip so that they can either be turned into bags or moulded bottles and such) This antidripping property so valuable when procesing would work against the design.
Alternatives might be the addition of waste oil might which might allow your plastic to flow by lowering the general melt index of the mixture. Perhaps placing some water in your mix would give you steam that would increase the pressure in your vessel allowing the displacement of the mix, if you calculated your water right you might end up with a mostly empty chamber and little no no water in your mix. The feeding reactor would of course need to be airtight which I see no problem in achieving. Compressed syngass or nitrogen might be pumped into the plastic reactor as well to enforce the displacement of the plastic, it just might be slightly costlier.
2. My boilers have flue temperatures in excess of 250oc even after 3 passes through 12 meters of water surrounded pipes. Assuming your main reactors burner`heat transfer is as efficient as a boiler (which it might not be) your flue gases will be at least as hot as mine. I believe that these gases directed into the space between a double layered plastics reactor, would allow for working temperatures of over 125oC to where our plastic would become liquid and allow itself to be pooped and farted (could not think of any other expression; sorry for the image) into the main reactor. This would allow you to skip the heating elements in the initial plastic reactor. In fact it might even (optimistically speaking) allow to skip some of the heating elements in the diesel/kerosene/oil condenser. or at least in your catalyst vessel (asuuming it is heated)
3I'd Take the air expelled from the radiator cooling your condensor tubes and focus it on the material waiting to be placed in the plastics rector thereby your plastics, when entering your plastics reactor would already be hot and dry.

Questions
1.Are you using 400oc+ Ball valves, or slide gates? I`d like to know more about these.
2.Your burner seems interesting as well. Do you worry about your vessel getting hotter on one side than the other? or will the stirrer solve this.
3. How do you know when your vessel is empty so that you empty your char/as deposit? How do you know the level of your soup inside the Main reactor so that you dont add your plastics to soon(overflow) or too late (inefficient)?

I`m hoping you do not see me as critizicing your design, in fact it is quite the opposite it is an almost ideal design, one that with your permission I`d ideally like to mimic at some point.

[Asad Farooqui]

feeding system

Looks good Asad
Would you elaborate about how the pre melted plastic is delivered to the main reactor? Is there a feeding mechanism or is it supposed to be free flowing?
Thank you!
Jetijs

Hello ;
Thanks for your comment .
Yes there is a feeding mechanism . Initially its a forgesteel valve operated manually .
Afterwords it is possible to automize the system by placing 02-censors, in the main reactor . As soon as the level of the feedstock drops to 25% level, the censor will open the valve & as soon as the level of the reactor is 75% filled, the second censor will shut-off the valve .

[Asad Farooqui]

heating system

Hi Asad your design looks excelent.
1.Unless you use some sort of auger feeder system, pressure differential system, I`d doubt you would be able to get the plastic to flow.

2. My boilers have flue temperatures in excess of 250oc even

Questions
1.Are you using 400oc+ Ball valves, or slide gates? I`d like to know more about these.
2.Your burner seems interesting as well. Do you worry about your vessel getting hotter on one side than the other? or will the stirrer solve this.
3. How do you know when your vessel is empty so that you empty your char/as deposit? How do you know the level of your soup inside the Main reactor so that you dont add your plastics to soon(overflow) or too late (inefficient)?

I`m hoping you do not see me as critizicing your design, in fact it is quite the opposite it is an almost ideal design, one that with your permission I`d ideally like to mimic at some point.

Hello ;
It's nice to hear different concepts the forum community puts up .

1) You can notice I have One Furnace only.
The flu-gas coming out of the main reactor will definitely be utilized to heat-up other vessels .

2) Flowability of waste plastic into main reactor. I don't forsee any problem .

3) Only High temperature forgesteel gate valves are used . Hand-valves have teflon seal with the ball which will melt soon .
Ordinary gate-valves have glanddori resistant upto 150celcius which is not enough .

4) Stirrer definitly helps in homogeneous heating + mixing catalyst & most importantly Char removal .

5) Level indicators . I just explained to Jetijs .

[Betopty]

more questions...

Hello ;

3) Only High temperature forgesteel gate valves are used .

5) Level indicators .

Understanding this is your invention, you probably spent much time designing it, and you are in bussiness doing it, please feel to just respond to the questions that are not "classified" or "secret" to your design.
1.How are you solving the problem of flowability? I seem to remember you have a background with plastics or paints.Simply allowing the plastic to flow would either not happen or take quite a while, so I`m assuming you have something I overlooked.
2.When your client decides to upgrade to automatic he can use electric or hydra-pneumatic operated. Schubert &Salzer has some good sistems for 450 degrees, and their (2" steam are the ones I use) valves last a lifetime, although they are not cheap. Vatac is another option as well as KOLINK that are cheaper, but i do not know how long they last. There is an italian company i will try to find the name that uses the same valve body for automatic and manual. Therefore when you upgrade only the top portion must be replaced, saving 50% of the cost, and all the instalation cost, as existing valve is not removed
3. Can you more detailed specify What sort of level indicators you will be using? I looked up O2 sensors and I can`t quite see how they would work in an O2 deprived reaction vessel. My boiler has warrick sensors but I doubt they would work/survive the atmosphere inside the main reactor. Banner has some inductive (or condustive or someductive )sensors that are rated to 450oC but I doubt they would work as they require an electric current to be passed /or convected or bounced or something and I do not know if plastic would be able to do this. Perhaps flow sensors that would detect a swirling mass... Any hints?

[dutchdivco]

Just my thought

"O2 sensors" like the ones used on autos, in the exhaust, don't actually measure oxygen; they measure temperature, and can go up to 1000 degreesF. I'm just thinking that may be what he was referring to? Jim

[benadrit]

Pressure canner

Sorry if this has come up. Yes I'm quite new to the forum. First post. I did see that a pressure cooker/canner was posited for the inner chamber early on. It was dismissed as being unusable as the seals would be unable to handle the heat. I've been hooked and poring through the postings, but I'm only up through page 10 and have run out of time.

Anyways on to the point. It may not be well known out there that the All American company manufactures pressure cookers/canners that are gasketless. Metal to metal seals. Can be purchased in stainless steel or aluminum. Approximately $200 to $300. They are here All American Pressure Canner

Might be useful to those without easy/affordable access to welding. I got mine at a second hand store for $15, but have never seen another used at less than $100. That's the general e-bay price.