How to turn plastic waste into diesel fuel cheaply

[Excalibur]

color problems ...
The first tank dark brown / black, second tank is orange. I tried to delete the color with clay. . When using large amounts clay of yellow color. but this time, cost too much. activated carbon, clear more liquid of clay. but activated carbon is expensive than clay. maybe distill again. or, What do you recommend to delete the color?

It would be prudent to determine if the color was from contamination or oxidation. Does the diesel get darker with age? What is the specific gravity? Does sludge/sediment settle to the bottom of a sample? What was the feedstock?

[Col]

De-colouring the distilled fuel

There are filters for sale that look much like toilet rolls. They do a reasonable job of lightening the colour. I have some at work. You could knock together your own out of pipe and toilet rolls, though I don't know what the result will be like. I'm off sick but when I get back into work I could take some photos and put 'em up here for you.

[kedigen]

color problems ...
The first tank dark brown / black, second tank is orange. I tried to delete the color with clay. . When using large amounts clay of yellow color. but this time, cost too much. activated carbon, clear more liquid of clay. but activated carbon is expensive than clay. maybe distill again. or, What do you recommend to delete the color?

[Excalibur]

Do you have any idea how I can obtain a light color liquid in the first tank as well?
And what would you suggest me to do to seperate water from the liquid fuel?

A second or third tank is typically going to be more pure and clear because it is double or triple distilled.
My diesel tank has a drain tap at the lowest point so at 60°C operating temperature I consider it safe to periodically crack open.
In practice there is never been any vacuum created by water removal because my gas-jar automatically compensates. The same applies to diesel product removal during operation, provided there is sufficient quantity of gas stored, the pressure of the water with push gas back upstream to occupy the space made by the vacating product.

I had intended to run continuously and leave the outlet valve open (once the tank level had reached the height of the valve at the end of the riser) and let the condensed diesel flow from the bottom of the tank up the riser and out to a storage vessel. This would of course leave a certain amount of fuel in the tank, below the top of the riser.
Q - Is this a safe idea? I imagine that if any vacuum was generated in the diesel catch tank by the outlet valve dribbling diesel out, the vapours of the system would 'fill the vacuum' and a gulp of air wouldn't be sucked in. Surely there's enough expansion of vapours from the retort to counteract any vacuum generated by gradually releasing liquid from the system?
If not, how do we extract diesel (or naptha) from the system on the run?
Any help?

Actively pumping out liquid from a (diesel) tank will create a vacuum so the situation will need to be managed. Vacuum will lift water out of the bubbler, drawing it upstream unless there is a suitable draw-back-arrestor.

Ok, so if you want to run a small plant continuously, with say a 60L diesel collection tank, a 40L naphtha collection tank and a 20L chilled tank but want to run 1000L of feed product through it, what is the best / safe way to keep the liquid collection tanks at an appropriate level? I thought an overflow weir would do the job. Do we need a float level to actuate a gear or other positive displacement pump to maintain the levels while excluding air ingress?
How are any of you doing it right now? Or is everyone processing in batches using collection tanks large enough to hold all the feed volume?

Comments assuming you are using standard series condenser setup: 60L tank is small for 1000L batch so given this is the case, diesel will be removed before it has had sufficient time to bleed off the lighter volatiles. Therefore some further processing of the removed diesel will likely be necessary. My tank is 500L.

[wheels]

Ok, so if you want to run a small plant continuously, with say a 60L diesel collection tank, a 40L naphtha collection tank and a 20L chilled tank but want to run 1000L of feed product through it, what is the best / safe way to keep the liquid collection tanks at an appropriate level? I thought an overflow weir would do the job. Do we need a float level to actuate a gear or other positive displacement pump to maintain the levels while excluding air ingress?
How are any of you doing it right now? Or is everyone processing in batches using collection tanks large enough to hold all the feed volume?

1000ltrs is a huge volume for a backyard operation. As I understand it, this Forum is supposed to be for the amateur fuel maker. Please correct me if I am wrong. But I doubt many amateurs are going to be processing that kind of volume. You are getting into some fairly complex controlling, monitoring and pumping etc etc which is all going to be expensive and way outside the reach of amateurs and of course, commercial guys are not going to share too many secrets

[Col]

Fuel collection in a continuous plant

Ok, so if you want to run a small plant continuously, with say a 60L diesel collection tank, a 40L naphtha collection tank and a 20L chilled tank but want to run 1000L of feed product through it, what is the best / safe way to keep the liquid collection tanks at an appropriate level? I thought an overflow weir would do the job. Do we need a float level to actuate a gear or other positive displacement pump to maintain the levels while excluding air ingress?
How are any of you doing it right now? Or is everyone processing in batches using collection tanks large enough to hold all the feed volume?

[wheels]

Hi Kedigen
If you were to drain water from the bottom of the tank when the tank has cooled below the liquid flash point that's fine. If you were to do it while the tank is still hot and above the flash point of the liquid inside you could have an explosion, right? Although there would be enough head pressure to push the water out in full flow at first as water drains out the vacuum inside the tank may reach the point where it sucks a gulp of air in, possible explosion.
So, if we want to drain liquid from the bottom of the tank while processing, we would need to do as IMBD suggested and turn the drain pipe up, use a riser, turn it back down and add a valve. This means the air would have to go down the riser before it could get into the tank... but now I think about it I guess it is possible that it could still generate enough of a vacuum to pull air into the tank through the riser...
I had intended to run continuously and leave the outlet valve open (once the tank level had reached the height of the valve at the end of the riser) and let the condensed diesel flow from the bottom of the tank up the riser and out to a storage vessel. This would of course leave a certain amount of fuel in the tank, below the top of the riser.
Q - Is this a safe idea? I imagine that if any vacuum was generated in the diesel catch tank by the outlet valve dribbling diesel out, the vapours of the system would 'fill the vacuum' and a gulp of air wouldn't be sucked in. Surely there's enough expansion of vapours from the retort to counteract any vacuum generated by gradually releasing liquid from the system?
If not, how do we extract diesel (or naptha) from the system on the run?
Any help?

You can only drain water when the system is cold. While the Fluid temp is above the boiling point of water, the water will only exist as steam and will tend to be mixed in among all the other vapors. When the Liquids cool, the water will condense and settle. The longer the Fluids can be left to settle, the more water will settle out of the Fluids. Some Carbon particles may settle out as well. There are other methods used to "dry" Fuels as well, but they are just an added Expense and complexity. Allowing the Fuel to cool and the water to settle is simple and easy for the backyarder.
Filtration of the Fuel is critical and a Filter with Water separating ability is an even bigger help.
By the way, it is really hard to ignite the vapors, even when they are super hot. Not saying they won't and it is best practice to think safety and that ignition is very possible. However, there are far greater dangers that just ignition to consider. The vapors are extremely Toxic at the best of times. If you are using waste Plastics, you may get a few pieces of the wrong type in the jix by accident. Many of the Plastics other than PP and PE produce some highly corrosive and extremely toxic gasses. Hydrogen Chloride, Hydrogen Cyanide being just two. You simply do not want vapors escaping anywhere at anytime. Whatever plastic is Pyrolyzed, including PP and PE, some of the Hydrocarbons produced can be very toxic and tend to be longer term Toxins. Causing Cancers like Lukemia etc. I have seen many video's on YouTube that have horrified me, of People that are breathing Fumes while pouring off the liquids. You have to be really careful people.

[Col]

draining water,...or fuel

Hi Kedigen
If you were to drain water from the bottom of the tank when the tank has cooled below the liquid flash point that's fine. If you were to do it while the tank is still hot and above the flash point of the liquid inside you could have an explosion, right? Although there would be enough head pressure to push the water out in full flow at first as water drains out the vacuum inside the tank may reach the point where it sucks a gulp of air in, possible explosion.
So, if we want to drain liquid from the bottom of the tank while processing, we would need to do as IMBD suggested and turn the drain pipe up, use a riser, turn it back down and add a valve. This means the air would have to go down the riser before it could get into the tank... but now I think about it I guess it is possible that it could still generate enough of a vacuum to pull air into the tank through the riser...
I had intended to run continuously and leave the outlet valve open (once the tank level had reached the height of the valve at the end of the riser) and let the condensed diesel flow from the bottom of the tank up the riser and out to a storage vessel. This would of course leave a certain amount of fuel in the tank, below the top of the riser.
Q - Is this a safe idea? I imagine that if any vacuum was generated in the diesel catch tank by the outlet valve dribbling diesel out, the vapours of the system would 'fill the vacuum' and a gulp of air wouldn't be sucked in. Surely there's enough expansion of vapours from the retort to counteract any vacuum generated by gradually releasing liquid from the system?
If not, how do we extract diesel (or naptha) from the system on the run?
Any help?

[wheels]

The liquid in my first tank is in dark color and light color in the second.
Do you have any idea how I can obtain a light color liquid in the first tank as well?

And what would you suggest me to do to separate water from the liquid fuel?

Last question first, the easiest way to remove water is to have a settling tank and a tap at the bottom and simply run off the water as it collects. A sight glass that can show you how much water is collecting could be helpful.

The dark colouration can be several factors. But the most simple and most likely is the weight of the Hydrocarbon being collected. The longer the chain (hence the thicker the liquid) the darker the Fuel will look. Think of the extreme being Tar, that is dark Brown almost black. The shorter the chains, the less brown colour. Basically it is that the larger hydrocarbons reflect more light and the very small Hydrocarbons let the light go right through.
Another possible is oxidation of the Fuel. This is often seen as the Fuel getting darker over a period of time. If you collect a sample in a glass jar and leave it in the Sun light, it may darken over several days. This means you are producing a high proportion of Unsaturated chains (alkenes) and the unsaturated(means that it is an open ended chain) chains grab Oxygen Molecules. Alkanes are saturated, which means they are closed chains and unable to grab anything undesirable. Alkenes need to be closed off with something to stop them grabbing oxygen. This is in a very basic way, how Fuel stabilizer works.
When you crack Hydrocarbons with just heat, the chains tend to break in a way that produces one Alkane and two Alkenes. This is where Catalyst and other methods of controlled Cracking come in. They crack the chain in such a way so as to produce Alkanes and no of few Alkenes.
The final possible is Carbon particles. You need a very very fine filter or centrifuge to spin out the carbon particles. It is possible that the 2nd Distillation pot is not getting as much carbon traveling through to it.
And finally, it could be a mix of all three scenarios.

[kedigen]

The liquid in my first tank is in dark color and light color in the second.
Do you have any idea how I can obtain a light color liquid in the first tank as well?

And what would you suggest me to do to seperate water from the liquid fuel?

[Excalibur]

half inch.

[rozier56]

rozier56

Thks for explanation.
On your condenser pics you mention you have 9 tubes for cooling, what diameter tubes are those internally.
This means you have approx 11,7 meters of direct cooling?

[Excalibur]

The purple color heat-exchanger-condenser condenses the vapor stream which falls into the diesel reservoir via the sight glass. Only perhaps a few percent of that distillate will be evaporated out, continuing downstream to the petrol-condenser vessel. This vessel is a condenser and reservoir "in one". For the flow I'm getting it is working, but if I get the system going faster I'd expect to have to upgrade its' capability.
Look at it like this: any piece of the system has to be able to cope with volume of vapor it will receive. The vapor stream is a relentless one with lots of heat energy so any/every condenser must be able to reduce the temperature of the vapor to the target mark because overheating will mean product loss downstream.

[rozier56]

rozier56

Excalibur are you saying you have TWO condensers on your system?
I only see one in your schismatic diagram.

[wheels]

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)

Yes you are correct. Here in NZ, we use the word Hydro to refer to water. It also refers to Hydraulic and for NZ, it is the combination of those two in Hydroelectric generation that we thus use the term rather incorrectly.
However, I also should not have said Cracking, because the water is not being used to crack, but to simply be a precise method of temperature control and a medium in which the various Hydrocarbons condense out into. In stead of using the walls of a vessel or a condenser of some form to condense the various hydrocarbons. Many Refineries still use the method of water in their Distillation towers. Steam Distillation is another method, but Steam is used to crack the Chains. There is also an Azeotropic Distillation method that also uses water.
All summed up, there are many various methods of Cracking and Distillation and in the Commercial Petrol Chemical World, they are very complex considering what is done in the Back yard plants that are discussed here.