How to turn plastic waste into diesel fuel cheaply

[operatorX225]

Hydro cracking has nothing to do with water. It has to do with hydrogen addition to a catalyst (platinum/palladium) in order to crack longer chain hydrocarbons into shorter ones. hence the term hydro-cracking

Hydrocracking is an important source of diesel and jet fuel - Today in Energy - U.S. Energy Information Administration (EIA)

[wheels]

Excalibur,
when you heat up your system do you find that your gas/water jar heats up radically?

Hmmm, the vapors should be cold by the time they reach the Jar, as Excalibur said. That is providing you are condensing the vapors before hand.
The Water jar is an interesting part of the Pyrolysis Plant. I see here that it is most commonly used for backfire protection. But in actual fact, the water jar barrier actually came about from a very different concept completely. It was used for a "poor mans method" of Hydrocracking. Instead of having the Hydrocarbons condensed in Vessels held at different temperatures, like most of you are doing, the original idea was to have the gasses condense within the water and the Hydrocarbons would float on top of the water to then be drained off. There are some benefits to doing it this way, as you can add Alkalines to the water to aid in the "washing" of acidic components from the Hydrocarbons, as well as washing dirt particles from the Hydrocarbons.
The Cracking itself is a lot more controlled and depending on how the water temperature is maintained, a very precise method of cracking can be employed. However, it adds a lot more complexity to the plant and the one big negative for backyard plants is that all the Hydrocarbon Chains are condensed together. This then means that if a range of fraction weights are required, further Distillation is required, which adds cost and complexity and thus many have dropped the idea. In larger commercial plants, the Water is heated to the various ranges of hydrocarbons required. Once the water is heated close to or over boiling point, it then has to be pressurized. Of course all that sort of thing is outside of what any of us can do in a "backyard"system.
So hence the water barrier is now just used as a safety feature. Although I suspect the idea may have been dropped due more to people not realizing what the water barrier was actually being used for in the very beginning.

[Excalibur]

As a further thought about heating up of the gas jar. If I had this happen, I'd be blaming the petrol condenser for not being effective enough. In my case the diesel condenser is targeting 60°C so the vapor stream temperature is reduced at the heat exchanger to maintain that figure. Petrol and lighter fractions then evaporate from the diesel, head downstream and are ideally quenched to ambient or thereabouts. So once the vapor leaves the petrol condenser vessel it does so at ambient temperature and then goes through the bubbler also at ambient. Then there is a quite a few meters of 3/4" hosing to reach the gas jar. Far safety reasons it is at a distance.
So therefore the bottom line is: the petrol condenser and its' contents can't be above ambient or else it isn't being efficient enough. A bigger plant will mean more liters per hour so the ability to cool the product will need to at least match stream volume.
At one stage I had experimented with a petrol condenser vessel of 30°C along with a heated bubbler to 50°C+. The object was to force some of the petrol fraction to stay as vapor and so be burned as retort heat. That particular trial was abandoned.
Hope this helps..

[Excalibur]

Rozier56,
No, there is no radical heating up of the gas jar. It remains at or around ambient temperature. The back pressure the head of water creates would be somewhat less than 1psi. The gas jar has no valves or moving parts. What is the gas release valve you have found? More info on the refinement prospect please? Always interested in safety.

[rozier56]

rozier56

Excalibur,
when you heat up your system do you find that your gas/water jar heats up radically?
As the water/gas jar is a safety feature,i think i have found a suitable gas release valve that will execute the gas and stop any flashback to the system.This also stops overflow of hot water exiting the gas outlet.These valves are controllable allowing me to set the right process pressure for optimum output.

[mercedes 308]

Interesting question. The Sulphur itself is not acidic and it does not cause rust. But Sulphur combines with water to create Sulphuric Acid and that is what causes corrosion. You will also get a small amount of carbolic acid as moisture reacts with the Co and Co2 in the combustion stage. As part of a lubricants additive pack, a form of Zinc is usually added to react with and neutralize Acids in the engine as they are created. It is this single issue that mainly results in the reason why lubricating oils need to be replaced every few thousand Km's. In fact a very high quality oil could be continuously used if you simply kept replacing the filter often enough and could add the Zinc regularly to keep neutralizing the acids as they are created.
The reason why Sulphur was removed from Diesel in many countries, was that the Suphur Dioxide that was spewed into the air, combined with the moisture in the air and then falls as Sulphuric Acid in the Rain water, thus Acid Rain. Very mild of course, but still caused damage. In saying that, Co2 in the atmosphere also creates Carbolic Acid in Rain. So Rain is always slightly Acidic, but that does not mean Acid rain is Bad. It is normal for Rain to be of a slightly acidic nature.
Anyway, back to the topic.
For a Petrol Engine, every 10ltrs of fuel consumed produces around 1 ltr of moisture and 1/10th of a ltr of Sulphuric acid.
I assume that you are referring to WMO being the feedstock and yes, this can contain Sulphur. Mainly in that some oils (Diff Oils for instance) have sulphur added as lubrication. Also there is likely a difference between cheap lub oil and more expensive higher quality lub oils. Synthetics will have no Sulphur unless added for a specific purpose.
Many lighter Gear oils had Sulphur removed because sulphur attacks bronze bushes and thrust washers etc.
Most Diesel is Sulphur free or low at least, but amounts of Sulphur will vary around the world I expect.
Because WMO is made of discarded oils, usually from Motor Vehicle Service Centres, we have no clue what has been dumped in their holding tanks and what has been dumped is going to vary from day to day. So knowing if an WMO oil contains Sulphur will be next to impossible for us to know.
The only positive is that much of the water, hopefully, will be separated during the heating of the plant and as Sulphuric acid is acidic water, hopefully most is therefore removed.
I did do an experiment on a batch once and poured the hot Fuel through Sodium Hydroxide. It reacted violently, which shows Acid was present, but it was just out of interest and I had no time to take that experiment further. I will do someday. Warning though, don't do this thinking the problem of Acid is taken care of. I was not able to test just exactly what reacted and the result of the Fuel afterwards. Any strong alkaline is also highly corrosive in the engine and the Fuel poured through the Hydroxide may well have been contaminated enough to cause just as bad or worse, damage to the engine.

Talking of WMO, has anybody recycled oil with slick 50 in there system?
It's supposed to have PTFE in it. And is there any way of testing for it, in oil.

Halfords | Slick 50 Engine Treatment 750ml

[wheels]

I was talking to a fellow the other day who does bulk tanker deliveries of dangerous goods. He tends to have conversations with various people when he delivers the products while he stands there for 30mins to 2 hours doing nothing / watching / making sure nothing goes wrong during the delivery. Sometimes he's talking to the head chemist of a chemical plant, sometimes it's the yard hand. Anyway - he said the sulphur in diesel causes rust in the engine, that it wasn't just an environmental concern about pollution driving the global move to reduce sulphur content. The refinery then adds some near food grade oil to restore lubricity in the absence of sulphur.
So, if we are cracking oil into diesel and have a high sulphur content are we at risk of rusting out our engines? or is this guy steering me down the garden path? He said the sulphur is very acidic and leads to instant rust.
IMBD gave us an acidity test to check if our fuel is acidic - has anyone used this test yet? What were your results? Has anyone had any issues with the fuel rusting their engine / whatever equipment you're using it in?
Thanks
Col
If I recall correctly, IMBD used his naptha in his line trimmer and it lasted a while (a season?) but then seized. Has anyone opened their engine and looked inside since using their own oil-cracked diesel?

Interesting question. The Sulphur itself is not acidic and it does not cause rust. But Sulphur combines with water to create Sulphuric Acid and that is what causes corrosion. You will also get a small amount of carbolic acid as moisture reacts with the Co and Co2 in the combustion stage. As part of a lubricants additive pack, a form of Zinc is usually added to react with and neutralize Acids in the engine as they are created. It is this single issue that mainly results in the reason why lubricating oils need to be replaced every few thousand Km's. In fact a very high quality oil could be continuously used if you simply kept replacing the filter often enough and could add the Zinc regularly to keep neutralizing the acids as they are created.
The reason why Sulphur was removed from Diesel in many countries, was that the Suphur Dioxide that was spewed into the air, combined with the moisture in the air and then falls as Sulphuric Acid in the Rain water, thus Acid Rain. Very mild of course, but still caused damage. In saying that, Co2 in the atmosphere also creates Carbolic Acid in Rain. So Rain is always slightly Acidic, but that does not mean Acid rain is Bad. It is normal for Rain to be of a slightly acidic nature.
Anyway, back to the topic.
For a Petrol Engine, every 10ltrs of fuel consumed produces around 1 ltr of moisture and 1/10th of a ltr of Sulphuric acid.
I assume that you are referring to WMO being the feedstock and yes, this can contain Sulphur. Mainly in that some oils (Diff Oils for instance) have sulphur added as lubrication. Also there is likely a difference between cheap lub oil and more expensive higher quality lub oils. Synthetics will have no Sulphur unless added for a specific purpose.
Many lighter Gear oils had Sulphur removed because sulphur attacks bronze bushes and thrust washers etc.
Most Diesel is Sulphur free or low at least, but amounts of Sulphur will vary around the world I expect.
Because WMO is made of discarded oils, usually from Motor Vehicle Service Centres, we have no clue what has been dumped in their holding tanks and what has been dumped is going to vary from day to day. So knowing if an WMO oil contains Sulphur will be next to impossible for us to know.
The only positive is that much of the water, hopefully, will be separated during the heating of the plant and as Sulphuric acid is acidic water, hopefully most is therefore removed.
I did do an experiment on a batch once and poured the hot Fuel through Sodium Hydroxide. It reacted violently, which shows Acid was present, but it was just out of interest and I had no time to take that experiment further. I will do someday. Warning though, don't do this thinking the problem of Acid is taken care of. I was not able to test just exactly what reacted and the result of the Fuel afterwards. Any strong alkaline is also highly corrosive in the engine and the Fuel poured through the Hydroxide may well have been contaminated enough to cause just as bad or worse, damage to the engine.

[Col]

Sulphur content in the cracked fuel

I was talking to a fellow the other day who does bulk tanker deliveries of dangerous goods. He tends to have conversations with various people when he delivers the products while he stands there for 30mins to 2 hours doing nothing / watching / making sure nothing goes wrong during the delivery. Sometimes he's talking to the head chemist of a chemical plant, sometimes it's the yard hand. Anyway - he said the sulphur in diesel causes rust in the engine, that it wasn't just an environmental concern about pollution driving the global move to reduce sulphur content. The refinery then adds some near food grade oil to restore lubricity in the absence of sulphur.
So, if we are cracking oil into diesel and have a high sulphur content are we at risk of rusting out our engines? or is this guy steering me down the garden path? He said the sulphur is very acidic and leads to instant rust.
IMBD gave us an acidity test to check if our fuel is acidic - has anyone used this test yet? What were your results? Has anyone had any issues with the fuel rusting their engine / whatever equipment you're using it in?
Thanks
Col
If I recall correctly, IMBD used his naptha in his line trimmer and it lasted a while (a season?) but then seized. Has anyone opened their engine and looked inside since using their own oil-cracked diesel?

[Excalibur]

The more I have looked into trying to solve issues, the more I have come to the conclusion that Simple is best.

When someone hears that all one needs to do is heat plastic to a vapor then subsequently condense it to fuel, they could be forgiven for thinking how easy the construction of a suitable plant would be. The principles aren't too difficult to grasp but adapting an apparatus to work in harmony with a good balance is the challenge. Simple works for me too. I think the best innovations are simple ones. I think that it's great that each is trying different things according to their means and resources. In this way we can learn things, compare and help one another.

BTW, I've started the rebuild of the refractory. First pics are up now on the refractory page of DIYdiesel.

Yesterday I saw diesel was 97c liter before tax. It hasn't been that cheap for a long time.

[wheels]

Ok thanks for vacuum tip.
I just ordered the switch if it works as it should ill share it.
Wheels keep us posted if you ever get an easy way do get a mixer working. Thanks

The more I have looked into trying to solve issues, the more I have come to the conclusion that Simple is best. The KISS approach KISS= Keep it simple stupid.
I have seen many plants around the world and as well as on this site, and many make the mistake of getting too big and complex in order to produce quantity. That is simply not the best way to approach it, because with quantity comes complexity and then problems.

[chacowako]

Ok thanks for vacuum tip.
I just ordered the switch if it works as it should ill share it.
Wheels keep us posted if you ever get an easy way do get a mixer working. Thanks

[Excalibur]

Excalibur my design is actually a pattern from yours so I would like to ask you
Do you have any problems you think that it needs a mixer?
AND MOST IMPORTANT how do you clean your Retort?
Also I finally found a level switch that can handle 600c yeay

I seriously considered a mixer when I was battling with boil-over problems but it looks increasingly likely that the feedstock was the primary cause so I dropped the idea.
Cleaning a retort that is deep and narrow presents a challenge. When the residue is dry, it will chip/scrape off and get pulverised to a coarse dust. Then I use a vacuum cleaner to suck it out.
Though untested, another thought for the future is to make a tool with the characteristics of a reamer.
The retort looks set to be shortened by a few hundred mm so this will make cleaning slightly easier.
Please share the 600°C level switch.

[wheels]

No experience but I believe a mixer would help the feedstock boil more calmly something a bit like Boiling chips/Anti bumping granules
My thought is that because there is next to no pressure in the retort, the shaft could be sealed with a simplified DIY version of a Mechanical seal
Looks nice. Am wishing you best of luck from far.

I tried a mechanical seal as well, but then I am working with the most nasty of plastics and I can't accept even the slightest leak of gasses as those gasses are highly toxic and corrosive, not to mention not wanting any oxygen to ever creep back in. The acid levels are extremely high, so any metals (brass etc) that work as a seal in any other application, do not work with acids at 400 to 500degC. I have considered a carbon face type seal, but have not gone further, due to time being taken up in other area's at the mo. Once fully back into the Pyrolysis part when I get back from Auckland, I will be trying several ideas.
The idea of having a stirring device was two fold. Firstly was actually to solve a problem of the Carbon caking in the bottom of the retort and keeping it moving was to aid in a way of automatically removing by a small port at the bottom. But this has to be done with extreme caution, because the last thing anyone wants is for oxygen to be introduced at the bottom of the retort. It results in a loud ringing in ears and possibly Sunday afternoon harp practice on a cloud somewhere.
The other thing the idea was to aid, was keeping the plastic stirred to aid in a faster and more even melt. Plastic is a great heat insulator and keeping it moving ensures the heat is able to flow evenly and quickly through the entire retort full of plastic.
As mentioned, the turning of the retort was yet another idea, but it posses an even bigger issue of seal. The thing is, the larger and more efficient we want a plant to become, the more complex a system becomes and the result is ever increasing dangers and difficulties to overcome.

[chacowako]

Excalibur my design is actually a pattern from yours so I would like to ask you
Do you have any problems you think that it needs a mixer?
AND MOST IMPORTANT how do you clean your Retort?

Also I finally found a level switch that can handle 600c yeay

[Excalibur]

Hi has anyone had experience with a Mixer OR is a mixer really necessary?
I am building a 300liter retort per day. I already have my small scale prototype working (2liter per hour) and going to scale up my issue is with the mixer. Anyone could suggest a good way to do it?

No experience but I believe a mixer would help the feedstock boil more calmly something a bit like Boiling chips/Anti bumping granules
My thought is that because there is next to no pressure in the retort, the shaft could be sealed with a simplified DIY version of a Mechanical seal

final state. hopefully no more wax

Looks nice. Am wishing you best of luck from far.