🔄 How ORLEN Unipetrol is Using Pyrolysis to Transform Waste Plastics

 

​Interview transcript

ML (Michael Londesborough): Coffee finished but what do I do with this- my plastic cup? Well, I could just throw it away and forget about it, but the molecules of this cup will last for tens of thousands of years. Or maybe I can just throw it into the bin, where unfortunately it would end up most likely in a landfill site. Or (a bit better) it'll be incinerated for its energy content. Or, maybe we can do some recycling here, where we can use a new technology of pyrolysis that converts these molecules in this plastic cup back to the original molecules from which it was made. So, let's go and have a look! Hello Robert!

RS (Robert Suchopa): Hello Michael. Good to see you.

ML: So, Robert, listen I'm on a mission - I want to recycle my plastic coffee cup and I'm here at ORLEN Unipetrol to come and see you because I know that you're working on a project about pyrolysis which can recycle this plastic. So, where do I start? 

RS: Just throw it in there and actually I have something more to throw in there.

ML: So, pieces of balloon and I don't know, plastic containers, … 

RS: Yeah, you can see even like labels and caps and all sorts of material.

ML: Right, but it can go into there, can it?

RS: Yeah, of course.

ML: It's pretty dirty, is it okay? 

RS: It´s not really a problem.  

ML: Well, fantastic. Okay. 

RS: So, I will just throw it in there

ML: Come have a look. Okay, so this is where it all starts. We got this mixture of plastics and what happens now?

RS: Well, this is only just a storage container. Then it comes into this green conveyor, which moves it down to this shredder and the shredder basically just compacts it down - just makes it into smaller pieces and then there is another conveyor which goes up top and I can show you up there. 

ML: Well, okay. Let's go. Come with us, have a look. Mind your step

RS: So, this is where the conveyor ends. There is this process hopper, where the material is being accumulated, and this is where the reactor actually begins. So, we store the material in the hopper, then there is this compressing screw, which basically is used to compress the material so it gets rid of the oxygen which is there and then it's being fed into the reactor itself. 

ML: Okay, so then my plastic cup goes through the hopper into the reactor itself and what happens inside of this reactor? 

RS: Well, the reactor you can imagine is this metal box. It's full of refractories and there is this cavity on the bottom in the refractory and this is where a metal spiral actually is. 

ML: A metal spiral which does what? 

RS: Well, it's there to fulfill two functions - first, to move the material from start to beginning and second is to supply heat, because this is a thermal process. 

ML: Okay, so you're heating my plastic cup. What temperatures are we talking about? 

RS: Well, we're talking about somewhere around 600 – 650°C. 

ML: And so, what happens at 600 degrees centigrade to my plastic cup?

RS: Well, by 600 hopefully your plastic cup is not solid anymore. It heats up first, then it melts and then it decomposes. It starts to break down due to the heat. 

ML: Right, that's why it's important to have no oxygen, no air in there so it decomposes not to carbon dioxide, but gets deposited into useful gaseous molecules of hydrocarbons.

RS: Exactly. Exactly right. And then those hydrocarbons, while being in a gaseous phase, are drawn away from the reactor using this section over there, and then we can go down and I can show you the next column. 

ML: Okay, are you with us there at home? So our plastic cup started at the bottom over there, got shredded into very small little pieces, up this green tube, through this hopper, into our reaction chambre, where there is a hot coil that heats it up to about 600°C. We take away all the oxygen and air, and the gaseous molecules from the decomposition of my plastic cup go through this tube into this big column here. So, let's go have a look at the column and see what happens next. Let's go, come with us! Okay, down we go. Right, so we're now in this column. What happens to the hot gases?  

RS: Well, it’s basically a condenser, right? So it's pretty self-explanatory. There is cold water circulated inside in the top half and the hot gases, as they cool down, they condense. Those longer chain hydrocarbons form this condensed mixture of oils. 

ML: Right, so here we've got the liquid. So, the hot gas is going to the top, cools down with the 
water chambre, falls down as a liquid, as an oil. And then, I'm following the tubes, it then enters into this part here. So, what do we have going on here? 

RS: We call this section the oil management section. It basically does three things - first, it filters some of the particular impurities out. Second, you can dispense the oil product, the liquid product, because this is what we are after. And third, it cools further down the oil because the oil is then being used for a cold oil quenching system. 

ML: Okay, are you with that? So, my plastic cup has been decomposed into hot useful gases of hydrocarbons, goes into this condenser, falls down as a liquid, into here where it's cleaned and you've got to reflux to make sure that we optimize the amount of useful product coming out and then it comes into here as an oil. But this oil, I can't make my plastic cup directly from this oil, can I, yet? 

RS: Well, yeah this oil is not really good. But this is actually in the longer chain or, as far as the pyrolysis process goes, this is the end product. But as far as, let's say, longer technological chains, we need to process this further, before we can turn it into feedstock that we then use to produce monomers and eventually polymers.

ML: Fantastic! From which then we can generate my plastic cup back. 

RS: Right, exactly. 

ML: Well. So, Robert, you know, how much plastic waste can we recycle here? 

RS: Well, through this machine we can put up to like five kilograms of plastic per hour. The bucket that we threw in was like three or four kilograms. 

ML: Okay, so we've got a couple of hours of work here then. 

RS: Yeah, exactly. 

ML: So, but what's the future outlook, what would you like to achieve? How much throughput? 

RS: Yeah, scale up is a major challenge that lies in front of us and we would like to achieve capacity somewhere around one ton per hour of waste material. 

ML: One ton per hour. That's a 200 fold increase. That certainly… that means soon there's going to be some incredibly large condensing tower for this plastic waste. But, I like the fact that you're completing the circle.

RS: Well, hopefully we can, yeah. 

ML: So, from a plastic cup back to a plastic cup. 

RS: Exactly! 

ML: Well, Robert, good luck!

RS: Thank you, Michael!

ML: And thank you very much! All the best!