How to turn plastic waste into diesel fuel cheaply

[jonathan]

retort feed

thanks excalibur......do you thing diesel from waste oil do any harm in modern engines? l meant very modern like 2010 to 2012....thanks

[Excalibur]

fox32, I wondered about a series of TC probes for possible level monitoring as you have. I can't decide if it would work either. My retort is 1.5m deep, so it's a long length of TC pair which would need ceramic insulation.

I'll keep trying things till I find a solution to the boil over. It's just a bit frustrating.

The danger of bottom feed is the pipe goes straight through the flame zone. Should the pipe crack, raw hydrocarbon gases would be exposed directly to those flames. Once the heat began to increase, the fire would not stop till the fuel source was exhausted.

[fox32]

NIcely done, that looks like a big scale though... I was thinking at a way to monitor the level of the retort, and was thinking at temperature probes put at 10 cm one from another and record the difference in temp, dunno how viable will be though. Great work! Maybe the boil over comes from the continous feed dripping oil onto the very hot reactor walls? Why do you think a bottom feed is more troublesome/danerous? i Was thinking of a pipe next to the reactor wall going to the bottom, this way the oil will catch some heat from the reactor wall.

[Excalibur]

It sounds like you are on top of the variables you need to solve, and a solution for each. Causing over-boil seemed to me to be the basic problem with a continuous feed system, so a low feed rate seems to me to be one possible solution in addition to all of the other solutions you have proposed.

Agreed it's a fine balance. It's seems to be about knowing how much feed to have against how much addition heat to apply. Finding that sweet spot isn't so easy. I aim to process 400L a day so either I need continuous feed, batches in succession or a 500L retort.

great work excalibur.keep it up...do you feed oil from top or bottom of retort?

Thanks. Oil feed is from the top. For ultimate safety reasons I elected to not have any bottom or side pipe connections in the retort vessel. I was only just talking recently about internally piping the feed inside the retort to the bottom. So I was trying to understand whether it would be of any benefit. Perhaps isolating the feed inside a pipe would have less influence on the rising vapors. Another thought was there could be some additional preheating from the vapors heating the pipe however that would mean the vapors would lose heat so a mini reflux situation would occur. The heat has to come from somewhere. No free lunch as the saying goes...

[jonathan]

retort

great work excalibur.keep it up...do you feed oil from top or bottom of retort?

[Beyond Biodiesel]

It sounds like you are on top of the variables you need to solve, and a solution for each. Causing over-boil seemed to me to be the basic problem with a continuous feed system, so a low feed rate seems to me to be one possible solution in addition to all of the other solutions you have proposed.

[Excalibur]

I ran the Orion retort for the day and processed about 250 liters. There was a number of problems the worst of which was boil-over.

The balance scale for weighing the retort/reflux worked and I learnt quite a lot. Due to the growth of the retort, I eventually had to excavate underneath so it didn't sit on the ground and confound the balance scale reading.

Another initial pre-heater was trialed. It is a old water heater with a 240v immersion element. Temperatures up to 105°C were recorded at the heater vessel.

More thermocouple LCD temperature gauges were fitted all of which used non-grounded TC probes. Some exciting data obtained was the temperature of the exhaust pipe where it exits the retort. It recorded up to 250°C so I'm looking closely at harvesting that waste heat source for pre-heating ingoing feedstock.

Fiberglass insulation for the retort outer layer was added. Also the reflux was lagged with aluminum foil.

Most perplexing is the boil-over which spoilt a quantity of the diesel. It may need to be re-distilled. Some thoughts on the cause/s listed below:
1/. Too much water content in the (continuous fed) feedstock.
2/. Too much volatile fraction content in the (continuous fed) feedstock.
3/. A retort probe that is not immersed in the liquid isn't showing proper temperature, only recording that of the vapor.
4/. The extra insulation may be requiring a lot less added burner heat which confused earlier markers.
5/. Actual retort level might be higher than I think due to expansion said to be as high as 30% at 400°C.

Possible fixes include preheating the feedstock much more thoroughly allowing water and light fractions to boil off. Lengthen the retort probe to be in the liquid. Avoid the trap of trying to hurry the process.
Any thoughts on boil-over remedies?

(There's a new post on diydiesel about the run and some other pages are also updated.)

[Beyond Biodiesel]

Thank you for replies guys, i was thinking to do that, but i remembmered that there are some brickmakers in a forest near me, and they showed me an ancient romanian clay recepie that they use to insulate their brick burning ovens. It consists of 4 parts clay 1 part ash and 3 parts saw dust mixed together.
You can increse the saw dust if the brick dosn't have to suport itself or great weight. The saw dust will burn leaving tiny aer pockets in the material.
All the best!

That is a good idea. I will have to try it.

On the immersion heater discussion above, I agree with wheels. Water heater immersion heaters have many problems, mostly they are not built for the temperatures required for pyrolysis of plastics, or distillation of WMO.

Even if one were to purchase an immersion heater capable of dealing with the environment of hydrocarbon pyrolysis it would still coke up right away. So I prefer a combination of a hot plate, band heaters, and line wrap.

[fox32]

Filling the gap with dry, loose ash will work just fine for insulation. Coke is an even better insulator, but it will burn at 1200F (650c) unless O2 is not present.

Thank you for replies guys, i was thinking to do that, but i remembmered that there are some brickmakers in a forest near me, and they showed me an ancient romanian clay recepie that they use to insulate their brick burning ovens. It consists of 4 parts clay 1 part ash and 3 parts saw dust mixed together.
You can increse the saw dust if the brick dosn't have to suport itself or great weight. The saw dust will burn leaving tiny aer pockets in the material.
All the best!

[wheels]

deleted double post

[wheels]

I have a question for all the PROs on this topic, regarding immersed heater element.

Just wanted to state I read most of this topic and I just couldnt find the answer. It has been brought up but discarded because immersed water heaters are not designed for high temperatures!

My question is for scenario of turning WMO to diesel...

Would it be safe to have an immersed heater element inside the main reactor where WMO is if said heater element IS designed for temperatures up to 1000 C or more?

Thanks

No it won't. You will end up with two problems and one difficulty. Firstly it will not withstand Acids and will corrode through the very thin protective jacket very quickly. Secondly, it is not designed to operate at the temperature you will need. Water will keep the element at 100degC (212degF) because it is an excellent liquid at drawing the heat away. But Oil is not so good at wicking away the heat and it has a lot of carbon in it that will cake to the element surface and serve to insulate the element and of course, you have to have a temperature 4x hotter than water boils at. The difficult part is the Seal at it's base will be very difficult to maintain sealed. It is possible, but difficult.
So all in all, it is not something that will last long term.
The idea is a good one though and one that I have been scratching my head on for some time. I think the way to do it is to have a center Pipe and the element is inside that pipe. But there needs to be something inside that pipe that transfers the heat from element to walls of pipe. I have thought about perhaps mounting the element in a Pipe and then filling the pipe/element with molten Aluminium. This would ensure a good conduction of heat to pipe wall. Aluminium has a melting point of 630 degC, so melting is not an issue.

[osamaricu_te]

immersed heater

I have a question for all the PROs on this topic, regarding immersed heater element.

Just wanted to state I read most of this topic and I just couldnt find the answer. It has been brought up but discarded because immersed water heaters are not designed for high temperatures!

My question is for scenario of turning WMO to diesel...

Would it be safe to have an immersed heater element inside the main reactor where WMO is if said heater element IS designed for temperatures up to 1000 C or more?

Thanks

[Beyond Biodiesel]

Yes,actually i have the heating through a pipe that goes through the reactor, working as a heat exchanger,the heat going from the inside out.I was refering at gap between the barrel surounding reactor and outer barrel. i don't need to make it like a cement, i was thinking to fill that gap, just pour it in there dry and pack it tightly. I will also have rockwool at exterior. Thanks!

Filling the gap with dry, loose ash will work just fine for insulation. Coke is an even better insulator, but it will burn at 1200F (650c) unless O2 is not present.

[Excalibur]

Fox32
If perlite isn't an option then how about vermiculite , expanded clay aggregate, or maybe pumice could be worth a try.
The expanded clay is used in the hydroponic industry. It looks interesting as its' full of air pockets, likewise for pumice.
I have used vermiculite, not the others..

[fox32]

Yes,actually i have the heating through a pipe that goes through the reactor, working as a heat exchanger,the heat going from the inside out.I was refering at gap between the barrel surounding reactor and outer barrel. i don't need to make it like a cement, i was thinking to fill that gap, just pour it in there dry and pack it tightly. I will also have rockwool at exterior. Thanks!