How to turn plastic waste into diesel fuel cheaply

[Col]

Heat exchanger / condenser orientation

Hi. Can I bounce this question off you guys?
I am about to put the heat exchanger / condenser into the system. It is a single pass shell and tube condenser, much like Excalibur's. It is 2.5m long (bit of an overkill for this smaller system but has extra capacity for the next upgrade). I was originally going to mount it horizontally with a bit of fall, but then thought about mounting it vertically. If I mount it vertically I will need to add a riser after it to get the discharge height back up to a practical level to enter the diesel holding tank.
If I use a riser the condenser will always be full up to the over-flow point of the riser. I was figuring I would set that point to the full height of the condenser. If I do this I think it will create back pressure and could bottleneck uncondensed gases at the condenser entry point. Perhaps then the heavier chains would be forced to condense but the light ends might be trapped and accumulate at that point.
So I figure mounting it horizontally is the better way to go, with a few degrees fall.
Thanks.
Col

[wheels]

I believe some of my production rate could be because my distillation column is to big.I notice that during a normal run at temps 350*C floe rate is good whilst the burner is on.When the burner shuts off at the desired point the rate reduces a lot waiting for the switch back on temp control. The fluctuation in temp is during the off stage of the burner. Burner switches off at 350*C, the temp continues to rise to 360*C and then reduces slowly to 345*C when the burner switches back on.
Maybe reducing the distillation column size will allow better forces present in the system to maintain steady flows on the shut off period.

I know exactly what your problem is here.
The Hydrocarbon chains are all wriggling around due to the heat energy being provided. The more heat, the faster they move around. The faster they move, the more space they create between each other. It's just like driving a Car around a corner. The faster you go, the more of the corner you need to use. So the chains require more and more space to move around in, the hotter they get. This is what is called heat expansion and affects all materials that expand and contract with temperature. Of course every material has a different rate of expansion. Gasses have the highest rates of expansion, because the Chains are free to move around in space.
Now lets just briefly side step here.
Remember that the vapor inside the Retort is at a very low pressure. Pressure affects the amount of room the molecules are allowed to take up. This is why increasing pressure requires more heat energy to bring something to the boil. If the Retort were under high pressure, the Vapors would still force their way out for a time, after you have removed the heat energy. But in our case, the Retort is at near zero pressure. So as soon as you remove the heat, the chains very quickly respond by maintaining their energetic state. As long as the solid plastic is producing new vapor, then the vapor already created gets pushed out of the Vessel. But if the heat is removed completely, the Molecules very quickly start to slow down and thus they don't need as much room and the vapor in the retort very quickly contracts. If the contraction continues, then the new vapor production does not push the already made vapor through the outlet. If the energy is removed long enough, the creation of the gasses in the plastic stops as well. This is because it takes energy to break apart the Solid plastic and release the vapor. Take the energy away and the breaking apart stops.
So basically, as soon as you stop the heat, the gas coming out of the Retort stops very quickly. You need to find away to maintain the temperature without turning off the burner. You need to try and either direct some excess heat away from the retort, or reduce the flame somehow. The other thing is to allow a higher Retort temperature and see if it reaches it's own natural temperature level. The most efficient range is about 460degC. But the hotter you go, the more non condensable gasses you produce. 460degC tends to be the sweet spot of most liquid to non condensable gas ratio. Processing WMO does not produce Wax, so you have no problem with waxes being produced by increasing the temp.

[Excalibur]

Thanks Wheels and Excal for your comments on my last requests. I have since removed the one way valve's due to blockages and no increase in production rates.
I believe some of my production rate could be because my distillation column is to big.I notice that during a normal run at temps 350*C floe rate is good whilst the burner is on.When the burner shuts off at the desired point the rate reduces a lot waiting for the switch back on temp control. The fluctuation in temp is during the off stage of the burner. Burner switches off at 350*C, the temp continues to rise to 360*C and then reduces slowly to 345*C when the burner switches back on.
Maybe reducing the distillation column size will allow better forces present in the system to maintain steady flows on the shut off period.
What size distillation column do you folks have relating to your retort size? My distillation unit is one third the size of my retort.
I have also noticed that during my diesel runs that i am producing a small amount of grayish sediment in the fuel. this product sits on the bottom of the collected fuel and is liquid.It is not ash/carbon as this is all filtered out.If it was a wax surely it would float. When i filter it out and inspect it feels waxy?
Thanks folks.

For comparison my retort to reflux ratio is now about 4.5:1 however it needs to be insulated to achieve target temperature. In my opinion, the burner should be switched by a sensor on the retort not the reflux chamber. I would constrain the retort temperature within a fairly tight range. Once this parameter is determined, the reflux temperature should be manipulated by adding/removing insulation or increasing/decreasing vessel size. The reflux temperature setting will then dictate product weight.
So the retort/reflux dynamics are finely balanced and in harmony with each other. Each needs to be run at pace that is not too fast or too slow.
Ultimately the operators' job is to establish the temperature settings based not on just performance but product quality as well. Drive the process too fast and the risk is boil-over which isn't distilling. Too slow and the downside is slow speed.

[rozier56]

rozier56

Thanks Wheels and Excal for your comments on my last requests. I have since removed the one way valve's due to blockages and no increase in production rates.
I believe some of my production rate could be because my distillation column is to big.I notice that during a normal run at temps 350*C floe rate is good whilst the burner is on.When the burner shuts off at the desired point the rate reduces a lot waiting for the switch back on temp control. The fluctuation in temp is during the off stage of the burner. Burner switches off at 350*C, the temp continues to rise to 360*C and then reduces slowly to 345*C when the burner switches back on.
Maybe reducing the distillation column size will allow better forces present in the system to maintain steady flows on the shut off period.
What size distillation column do you folks have relating to your retort size? My distillation unit is one third the size of my retort.
I have also noticed that during my diesel runs that i am producing a small amount of grayish sediment in the fuel. this product sits on the bottom of the collected fuel and is liquid.It is not ash/carbon as this is all filtered out.If it was a wax surely it would float. When i filter it out and inspect it feels waxy?
Thanks folks.

[Excalibur]

Thanks for the clear explanation. I guess I will have to stick with pyrolizing the WMO as I cannot tell for sure what other contaminates have been dumped into it. Unless of course I happen to bump into some clean WMO or WVO.

The clean waste is available but too often it's not free due to competition from folks wanting to recycle as chain bar lube etc.
I had to dump several hundred liters of oil because the contaminants were so bad. I thought it would distill OK but it just created too many problems. I know it had ethylene glycol coolant so this looks likely to be the cause of my boil-over problems recently. There was no real way of knowing what else it contained. The color was pitch black and it didn't look quite right in the way it poured and the way it sat. I hope that explains it.
With regard to clean waste oils, I use them to adjust my pyrolized fuel specific gravity. I use heavy or lighter to bring the fuel into a usable range. These days I've reduced my SG target to .83 ~.84 firstly because I found my vehicle fuel filter won't pass it with enough ease and partly because of winter.

[wheels]

Thanks for the clear explanation. I guess I will have to stick with pyrolizing the WMO as I cannot tell for sure what other contaminates have been dumped into it. Unless of course I happen to bump into some clean WMO or WVO.

As excalibur states, Centane is an issue, but only if perfect performance is required. I always used to joke that a Diesel engine will run of rubber gumboots if you could get them in the engine. The Diesel Engine was originally designed with the fuel in mind being Peanut Oil. Then Oil was discovered and the world changed.
One of the most abrasive substances to be in your engine, are carbon particles. They withstand extreme temperatures and will simply act as grinding paste on all the metal engine parts. These Carbon particles are what makes the engine oil turn black and the entire point of changing the Engine oil is too remove the buildup of those particles. So adding them back to the engine in your Fuel will simply work at wearing out your engine.
The next issue is that there are other components like Acids and moisture and resins, which are all created during combustion, which the old oil is now full of. Plus you never know what was ever put into WMO, if it has come from some workshop source. There could be Brake Fluid, Antifreeze, Cleaning Solvents etc etc that will all be very bad for the engine and most importantly, the Fuel Pump.

[Babataku]

Though not perfect, petrol/WMO or petrol/WVO blends will work. I first started blending about 12 years ago. These days I aim to pyrolize WMO or PE but otherwise I blend petrol with clean waste oil.
One downside to blending is the product will have a poor cetane number. This happens because the petrol component has octane which is the exact opposite of cetane. Another issue is the initial boiling point of petrol. Here it's 40°C but diesel has a boiling range of 180–360°C. Both these effects deteriorate as more petrol is added.
In summary, blending takes less effort though I do have to buy the petrol. Pyrolizing takes dedicated time though boiling point can be specifically targeted and cetane will not be seriously impacted though to get the diesel as good as bought product, cetane improvers would need to be added.
Blending oils that are contaminated and/or black as coal are best rejected.

Thanks for the clear explanation. I guess I will have to stick with pyrolizing the WMO as I cannot tell for sure what other contaminates have been dumped into it. Unless of course I happen to bump into some clean WMO or WVO.

[Excalibur]

Thanks Wheels for the reply...

I read that if you add petrol to WMO in the following ratio: 20%Petrol & 80%WMO and allow to settle for 1 - 7days...the gunk and dirt will settle to the bottom and can be easily drained off and the remainig blend can be used as "black" diesel...

I am just exploring my options...as I have access to free WMO.

Also read that Vegetable Oils can be mixed with Petrol in a similar fashion and used as Diesel without all the hassles of producing biodiesel...

I am looking for a simple solution to my Diesel needs...and anyone who has tried this before please help

Though not perfect, petrol/WMO or petrol/WVO blends will work. I first started blending about 12 years ago. These days I aim to pyrolize WMO or PE but otherwise I blend petrol with clean waste oil.
One downside to blending is the product will have a poor cetane number. This happens because the petrol component has octane which is the exact opposite of cetane. Another issue is the initial boiling point of petrol. Here it's 40°C but diesel has a boiling range of 180–360°C. Both these effects deteriorate as more petrol is added.
In summary, blending takes less effort though I do have to buy the petrol. Pyrolizing takes dedicated time though boiling point can be specifically targeted and cetane will not be seriously impacted though to get the diesel as good as bought product, cetane improvers would need to be added.
Blending oils that are contaminated and/or black as coal are best rejected.

[Babataku]

It is not really possible (in the backyard type plant) to turn Petrol into Diesel, or more accurately speaking, to take two short hydrocarbon chains and join them, to make a longer one. So the best thing to do, is to add the Petrol to Diesel at a rate of no more than 10%. At that rate, the Diesel engine will burn the fuel OK with out too much problem. If you put in too much Petrol, the engine will suffer from too much heat being produced and from too much punch from the combustion at ignition, which makes that Diesel rattle sound really harsh.
I would never use WMO without it ever being processed first, if I understand one of your questions correctly. It will be full of too much gunk and stuff you will never want to go through your engine.

Thanks Wheels for the reply...

I read that if you add petrol to WMO in the following ratio: 20%Petrol & 80%WMO and allow to settle for 1 - 7days...the gunk and dirt will settle to the bottom and can be easily drained off and the remainig blend can be used as "black" diesel...

I am just exploring my options...as I have access to free WMO.

Also read that Vegetable Oils can be mixed with Petrol in a similar fashion and used as Diesel without all the hassles of producing biodiesel...

I am looking for a simple solution to my Diesel needs...and anyone who has tried this before please help

[wheels]

Quick question for those who have done some WMO&RUG blends 80%WMO and 20%Gasoline...

My question is which is better quality diesel fuel? The one produced from pyrolysis process of WMO or simply blending WMO with gasoline? Or its just the same?

I have access to free WMO and want to know if there is any benefit for me to process in my small plastic pyro plant or I can just blend and pour in my tank...this will be simpler for me.

I know Excalibur has done WMO blends in the past and currently doing WMO pyrolysis as well as beyond biodiesel...

All comments are well come.

It is not really possible (in the backyard type plant) to turn Petrol into Diesel, or more accurately speaking, to take two short hydrocarbon chains and join them, to make a longer one. So the best thing to do, is to add the Petrol to Diesel at a rate of no more than 10%. At that rate, the Diesel engine will burn the fuel OK with out too much problem. If you put in too much Petrol, the engine will suffer from too much heat being produced and from too much punch from the combustion at ignition, which makes that Diesel rattle sound really harsh.
I would never use WMO without it ever being processed first, if I understand one of your questions correctly. It will be full of too much gunk and stuff you will never want to go through your engine.

[Babataku]

WMO Blend or WMO pyrolysis

Quick question for those who have done some WMO&RUG blends 80%WMO and 20%Gasoline...

My question is which is better quality diesel fuel? The one produced from pyrolysis process of WMO or simply blending WMO with gasoline? Or its just the same?

I have access to free WMO and want to know if there is any benefit for me to process in my small plastic pyro plant or I can just blend and pour in my tank...this will be simpler for me.

I know Excalibur has done WMO blends in the past and currently doing WMO pyrolysis as well as beyond biodiesel...

All comments are well come.

[Excalibur]

Orion made about 240 liters of diesel after major reconstruction work. There were a few problems with leaks, insulation, pumps etc. Feedstock was a variety of recycled waste oils, gear oils, hydraulic oils, engine oils etc. Actual production time was about 8 hours. Diesel measures at .848SG. Color ranged between light amber ~ ruby red ~ dark green depending on the thickness of transparent vessel the fuel was contained in. The fuel looks like the oil it was made from except specific gravity is close to target. Actually I was aiming for a slightly lighter weight but with all the running around, I elected to largely ignore the reflux temperature.

A new method of weighing the retort was trialed with success. A revised preheater is working well with further improvements likely. The I.D (induced draft) fan was particularly pleasing with considerably less lazy smoke wafting around. The retort insulation was a disappointment requiring more heat to overcome the inefficiency. The brickwork appears to be working nicely however these are not insulators so they store and conduct heat.

One really interesting phenomena discovered toward the final stages was the performance with low feedstock level in the retort. It was producing at a good clip with significantly less required heat. It will form the basis of the next run to see if any good, improved efficiency can be found.

More detail will be on DIYDiesel blog in coming days. As has been the custom, many of the early, obsolete postings will be retired to the redundant archive page.

[tesssweet]

I would love to come out and interview you for a film I am writing. This device looks amazing!

[Excalibur]

Excellent choice on starting small.

It's much easier to modify, tune and tweak a small installation. By comparison big rigs are exponentially much more difficult, costly and time consuming. The thought is to do all the learning, testing and trials on the small, easy to work on plant then once it's up to speed, look at how it can be up-scaled.

[wheels]

Hi Guys,
Good to be back.. I see a lot has gone on since I've been away. Still reading through with great interest. Well I've stopped construction on my larger plant and decided to build a small lab scale one first so I can easily tweek and test different catalysts. Plus the explosion will be kept at a minimum. I've posted a pic of my work (still under construction) and encourage all your comments please.. Good and Bad!

Excellent choice on starting small. I suggest you start with no catalyst and then use that as your reference point for your experiments. It is also worth doing tests with each plastic type separately and then with a mix of all types. Take note of your results.
It is also as important to learn about the Catalyst. It is important that the Catalyst is heated. A reaction requires energy. For many Chemical reactions, the energy(heat) is produced by the reaction. For a Catalyst, the heat needs to be input to cause the reaction to start. For some Catalysts, once the reaction starts, Heat energy is then continually produced as the reaction continues. Metal based Catalysts are common with that aspect. If you can place a temp sensor in the catalyst and watch the temperature slowly increase and then suddenly increase, that is usually a clue as to the activation temperature. You can often measure a lower input Gas temperature and a higher output gas temperature.
And most importantly, have fun