How to turn plastic waste into diesel fuel cheaply

[jonathan]

retort explosion

hello what is the risks of retort explosion? l thing backfire from burner is there another risks? did someone try to run an engine with exhaust gases thanks

[imakebiodiesel]

As a general rule copper fittings should be avoided with any kind of hydrocarbon fuel. The copper reacts with the fuel causing accelerated oxidation. This will reduce the storage life of the fuel.
However most small scale producers do not need long storage life as they use their fuels within a few months of making it. If long storage is required it would be better to avoid copper or add an antioxidant with a metal deactivator. There are many of these products for sale.
Tyre rubber and waste plastics pyrolyse under different temperatures and conditions so mixing them will not work very well. A better combination would be waste motor oil and rubber as they crack in similar conditions. The motor oil helps to transfer heat through the rubber as well. The yieild from rubber is not very high about 70 per cent at best, leaving you with a very smelly, toxic waste product that must be disposed of.

[Heartburn]

As a general rule copper fittings should be avoided with any kind of hydrocarbon fuel. The copper reacts with the fuel causing accelerated oxidation.

when you feed stock is contaminated if elements that produces HCL then having copper and aluminum would release hydrogen that would stabilse the hydrocarbons no ?

Tyre rubber and waste plastics pyrolyse under different temperatures and conditions so mixing them will not work very well. A better combination would be waste motor oil and rubber as they crack in similar conditions. The motor oil helps to transfer heat through the rubber as well. The yieild from rubber is not very high about 70 per cent at best, leaving you with a very smelly, toxic waste product that must be disposed of.

I would have thought that in a feed stock of tires, plastics and WMO if you increase your retort temperature slowly thru out the process the output would be good.

I have been using copper and brass plumbing fittings, and aluminum containers, throughout my pyrolysis experiments, and no explosive reactions took place, so using them does not seem to be dangerous, but I also know from experience cracking TCE that copper tubing and fittings are not going to mitigate all of the HCL liberated when cracking a chlorinated hydrocarbon.

I would inspect your aluminum containers on a regular basis if HCL is present as the reaction transforms Aluminum to aluminum chloride. I would add a ball of aluminum shavings, having high surface area to react with it should keep your vessels safe.

On a side note, be careful with aluminum chloride that is not in a water solution as it will react with water and make more HCL until the solution is balanced.

I have been distilling WMO, and fund it is commonly contaminated with antifreeze, which is not a problem. In fact I have settled out about 10 gallons of antifreeze and plan to distill it to recycle it.

Hummm... so the antifreeze evaporates and re condenses relatively intact ? Nice to know it doesn't decompose at the temps we're using. I was worried as when antifreeze burns in an engine for to long it gums it up pretty good.

[imakebiodiesel]

By stabilization I assume you mean hydrogenation, adding hydrogen atoms to saturate, unsaturated hydrocarbons. This will only happen at very high pressures and temperatures in specially designed reactors. It wont happen in the pipework leading away from our type of retort. The hydrogen will exit the system via the bubbler mixed with the uncondensable gases,
Im sure a method could be developed to pyrolyse plastic and tyres together by raising the temperatures in steps but it seems hardly worth the trouble. If you process them separately you will get better results with less contamination.

[saqmaq]

controlling temperature in system

I deliberately showed a range of temperatures for the top of the reflux column because you must match the temp to the type of fuel you want. At 220 I get kerosene, at 290 I get winter diesel at 330 I get summer diesel.
These figures will vary according to the actual shape and design of the reflux column and whether you use a catalyst or not, so I dont want to give the impression that these temps are absolute.
The only way to know the correct reflux temp is to build a reactor, test it for safety, and then experiment with different temp settings until you find a method that works. As I said before you need accurate temperature measurement in the top of the retort and the top of the reflux column otherwise you wont be able to repeat a successful result.
It doesnt matter whether the thermometer is digital or analog provided it can cope with temperatures of up to 450C

hi

nice pic, but how do we control the temperature at top of reflux?
so if the temperature at top of my reflux is higher, i remove the insulation from reflux and blow a fan
and if the temeprature is lower. i install heating bands?

did i get the above right

[saqmaq]

maximuizing diesel frac

Hello ;
1) I can separate gasoline from kerosene .
The trick is first I collect all the gasoline fraction upto 160 celsius, than I raise the temperature of my diesel condensor upto 225-celsius to trap the kerosene fraction .

2) The machine I have to stop after 20-hours as the Ash-bin is filled-up .
My bigger machine of 2000 kg/day capacity which Iam also making will be able to run 24-hours as an Ash-removing auger is specially made for this purpose .

3) Both type of catalysts liquid & gas-phase catalysts can be used according to the end-product requirement .

Hi

I have gone through the pages here, it seems that friends are using the same plastics but are using different operating temperatures and catalysts etc to get desired product range.
so what will be teh parameters to maximize the following fraction (assuming 60%WMO and 40% PE/PP)
1) Diesel (what temp in reactor,reflux and condensor; catalyst location-in liquid or solid or both, catalyst type)
2) Gasoline (what temp in reactor,reflux and condensor; catalyst location-in liquid or solid or both, catalyst type)

[Beyond Biodiesel]

hello everyone?
I'm about to start a small scale waste tire to fuel oil project. The raw material is waste tire at the beginning, but I would like to convert waste plastic too. Can a pyrolysis plant, which converts waste tire, be able to convert plastic as well?

Yes, the same pyrolysis plant can covert almost anything to fuel, such as: WMO, tires, plastic, wood, newspaper, agricultural wastes, old paint, etc. I have a pile of painted lumber here that is growing because a contractor in this warehouse bay likes to recycle, and he knows I am interested in recylcing, and I have a fireplace which I burn recycled wood in, but I do not want to burn painted wood in it, so I plan to run all of the painted wood through my new larger pyrolysis retort first, which will extract the volatiles, and leave me charcoal, which I plan to burn in the fireplace.

What would happen if I mix the two raw materials at the same time?

Thank you.

I see no reason why a wide range of hydrocarbons could not be run through the same pyrolysis unit at the same time; however, I like to know what my yield is for each source material, so I am segregating them just to acquire information. Later I plan to dump anything into the unit to see how they process together.

Thanks BBD. My question was not related to pyrolyzing chlorinated hydrocarbons, as I do not have intentions to include them in the feedstock. My question was mainly focused on the quality of the fuel produced.

Thanks
Marso Green

That part of my response was directed toward Heartburn, and was more of a question than an answer. So, the fact that random acid gasses are commonly liberated during pyrolysis, and they can be neutralized by just having copper, iron and aluminum components in the pyrolysis and refluxing zones strikes me as a really great solution for the small-scale operator. So, I plan to put the wad of copper chore-boys back into my system somewhere.

Right now I have a wad of aluminum shavings from machining in my retort,

then a wad of aluminum screening in my first condenser trap,

then grades of steel wool in the following condenser traps starting with the coarsest grade in the first trap with steel wool, then the finest grade of steel wool in my last trap with steel wool.

Baffles are used to separate the in and the out on each condenser trap.
Copper will be in the last of the condenser traps,
before I got to water jacketed condenser, then to a 20ft coil in a bucket of ice.

imakebiodiesel's point that copper components in a retort can result in accelerated polymerization is well-documented in the petroleum industry; however, I also agree with him, most of us are small-scale operators who are going to consume our product in a short period of time. For instance most of my distillate goes either into my crankcase or my fuel tank within a week.

hello what is the risks of retort explosion? l thing backfire from burner is there another risks? did someone try to run an engine with exhaust gases thanks

I believe the risk of retort explosion and fire is high with anyone operating a pyrolysis unit, whether that is at an oil refinery, or a backyard operation. So, exercise extreme caution and educate yourself for the solutions. This link will take you to a list of the precautions I believe everyone who is operating a pyrolysis unit should address.
Precautions for operating a hydrocarbon cracking/distillation unit

Hummm... so the antifreeze evaporates and re condenses relatively intact ? Nice to know it doesn't decompose at the temps we're using. I was worried as when antifreeze burns in an engine for to long it gums it up pretty good.

Antifreeze is easily separated from WMO through settling. I have accumulated 10 gallons of antifreeze, and expect that I will have much more as I work through the 200 gallons of WMO I have sitting around here. So, I plan to distill the antifreeze in a separate run, which should separate the water from the antifreeze, so I can discard the water and reduce the volume of antifreeze, and use that in my radiator.

hi

nice pic, but how do we control the temperature at top of reflux?
so if the temperature at top of my reflux is higher, i remove the insulation from reflux and blow a fan
and if the temeprature is lower. i install heating bands?

did i get the above right

The top of the reflux should never be over that of the retort temperature, unless you have a fire in your refluxing zone, which would be very bad to have.

I have band heaters, and hot plates and insulation, and control my condenser traps and refluxing zones with electric heat. If you have plenty of insulation, then it should not take much heat to control them, because they are going to acquire heat from your fluid stream.

I have at this time 3 condenser traps before I go to a water cooled trap. The last condenser trap is uninsulated and unheated. The previous 2 condenser traps are insulated and heated. I have about 5 stages of condensers because I want to separate my fractions. Also, having 5 stages of condensers reduces my loses.

Hi

I have gone through the pages here,

Good to know.

it seems that friends are using the same plastics but are using different operating temperatures and catalysts etc to get desired product range. so what will be teh parameters to maximize the following fraction (assuming 60%WMO and 40% PE/PP)

I do not think anyone here is operating their retorts at varying temperatures. We are all taking our retorts up to cracking temperature, which is about 425c (800f). You might be confusing retort temperature with condenser temperature. The condensers will be operated at various temperatures depending upon what you want to trap.

1) Diesel (what temp in reactor,reflux and condensor; catalyst location-in liquid or solid or both, catalyst type)
2) Gasoline (what temp in reactor,reflux and condensor; catalyst location-in liquid or solid or both, catalyst type)

You are going to get wax, grease, motor oil, hydraulic oil, diesel fuel, kerosene, gasoline and uncondensable gasses from any pyrolysis unit. You just have to decide what you want to condense out. Any of the heavy fractions can simply go back into the pyrolysis unit to be cracked again.

There is some debate about where to put the catalyst. Since most of us are operating a back-yard home-brew, DIY pyrolysis unit, then we have to make it simple. So, putting the catalyst in the retort seems to me to be the easiest way to do it. Some people find having the catalyst in the refluxing zone above the retort works best for yield.

[jonathan]

retort explosion

thanks beyond biodiesel l read them but l dont understand this? Never operate a hydrocarbon cracking, or distillation, unit that is not purged before the heat it turned on and remains on until the the unit returns to ambient temperatures.
sorry what u mean purged?

[operatorX225]

what BB means by purging is to get rid of any free oxygen in the entire system before beginning the process of cracking your feedstock. This is to insure you do not complete the fire triangle. heat + fuel + oxygen = FIRE/explosion! since you have heat and fuel to perform your reaction you need to take the oxygen away. Some people argue there is not enough oxygen present and that one would drive the oxygen out by gradual heating of the retort long before you get to a lower explosive limit (LEL) which is the very smallest air to fuel ratio to cause a fire. To 100% guarantee no fire means to purge the system. usually done with nitrogen or other inert gases.

[imakebiodiesel]

In small experimental reactors a small quantity of water added to the waste plastic will create steam at 100C and purge the system initially. However this will not help at the end of the process. As the remaining gases in the retort cool down they create a partial vacuum and will suck air in back through the bubbler. My solution to this was to collect the gas in a large mylar balloon and then allow it to be sucked back into the retort.
With larger reactors it is very dangerous to operate without a proper purging system. Sooner or later you will have a fire and most likely an explosion.

[waterboost]

Safety

Would a preburner that exhausts into the loading hopper be sufficient to purge the oxygen? a rich flame would burn the oxygen quickly and would be cheaper than inert gas.

While my batch unit is being welded into existence it has left me with time to ponder a continuous loading attachment. I looked at Knife Blade Valves but they were too expensive (no cheap second hand ones) so I got my CAD running and designed a simple 5 piece knife blade valve.

I am hoping to use the plastic no one wants to recycle, particularly plastic bags... will a standard auger move plastic bags?

Would a large ram that squeezes the bags into a pipe, against a closed blade valve, successfully remove enough air? then open the valve and push it inside the reactor?

Or... would a large melting pot be safer? remove moisture and premelt plastic to remove air? Would it be too sticky?

Any other ideas? Its always rainy here so plastic will be wet...

I have a DIY waste oil stove for the house and one small drip of water causes a huge boom and a flash of white light as it hits the burning oil... Its entertaining...

I've noticed that on small scale units the ratios from plastic in KG to Litres of fuel is almost 1:1 On the commercial units the ratios are lower... could this be that a small amount of oxygen is reaching the reactor and burning the fuel before it vaporises. As it gradually enters there is no explosion but the fuel yields are lower and carbon higher because a small controlled burn is happening in the reactor...

Any other ideas for methods of removing/reducing oxygen?

[Beyond Biodiesel]

Or... would a large melting pot be safer? remove moisture and premelt plastic to remove air? Would it be too sticky?

If I were to make a continuous feed retort for processing plastics, then at this time I favor a pre-melt pot with a screw to deliver the melted plastic into the retort, with now valve between the pre-melt pot and the retort, because the screw and mass of melted plastic should be sufficient barrier to the migration of gasses from an unpressurized retort.

[mjohnson1]

If I were to make a continuous feed retort for processing plastics, then at this time I favor a pre-melt pot with a screw to deliver the melted plastic into the retort, with now valve between the pre-melt pot and the retort, because the screw and mass of melted plastic should be sufficient barrier to the migration of gasses from an unpressurized retort.

This works well and is in fact relatively cheap to do.

Make sure you install a purging point somewhere in the continious feed line to ensure air from the atmosphere isn't let into the reactor in large quantities.

[PLASTICTRIX]

Hello. I finally broke down and joined this forum after reading this thread from top to bottom about 6 times in the last 4 months..I usually am pretty reserved with sharing any of my ideas but am starting to fold a bit just from the sheer anticipation of building a unit myself. I see that the wealth of info shared on these 71 pages is priceless, and info like it can not be found anywhere else on this planet..period. I would like to thank everyone here that have shared such great ideas and in depth knowledge on such a technical subject. Anyway I will reply to the auger feed issue with some of my own thoughts. I know auger feed units are being used in many large scale operations but from what i have seen they are mainly used with the tumbler units that use tires as feedstock. Auger systems to me on small scale reactors seem to be very problematic, feed rate, air induction issues, jamming,electric motors, gearing, and just the overall mechanical complexity of it does not seem worth it.
I think a direct hot melt injection system would be alot less problematic by far. One could fashion a set of moulds from copper pipe with removable end caps, that are mounted (like a pool cue rack) vertically close enough to the reactor so that they could be maintained at 300degf +-, could be funneled full of plastic chips during the boring hours of a run. When full and melted could be removed and replaced with cool pipes to fill. so while your reactor is running anyway you could in affect use a bit of the external waisted heat to make piles of huge plastic (glue sticks) to continuously feed at leisure. So a cone shaped nozzle with the orifice to be determined, could be welded up high on the side of the reactor with a long feed pipe that the plastic sticks fit snuggly into, attached at a upward angle steep enough to facilitate a gravitational drip feed (so to speak) a high temp gate valve installed close enough to be in the liquid zone so it could be shut at any time for any reason. The temp range of melted plastic in the feed tube from liquid to solid would fill the pipe and effectively make an airtight seal, as long as the reactor is an ambient pressure unit. It makes sense and seems like it would be much less problematic. just to try making the sticks I have already made a few 48in long pp hdpe blend sticks in a piece of 3/4 in copper pipe next to my woodstove and the plastic dosent stick to the pipe, it pushes right out easily after it is cool, they look real nice, no air bubbles etc. and could be set up automated with a caulking gun ratchet type system fairly easy.

[jonathan]

retort explosion

thanks to all so can you make vacuum pump to remove oxygen? thanks