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Prepol Step Combustor – a simple combustion system for alternative fuels: Sebastian Frie, ThyssenKrupp Industrial Solutions AG (Germany)

Filmed at Cemtech Europe 2015, 20-23 September, Intercontinental Hotel, Vienna, Austria.

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Hey, good afternoon? Welcome to this presentation our Prepol Step Combustor, a brief of introduction so my name is Sebastian Frie, and I'm pleased to introduce you with new combustion system for alternative fuels and was working in research developement and I'm one of the developer of this system so I'm able to answer an questions you might have regarding this technology.

So if we are talking about alternative fuel combustion we already learned yesterday and also today but this is of course state of the art for cement production process so also we as Thyssenkrupp Industrial Solutions also known as polysius yes also known as polysius we are able to deliver everything which is needed for the combustion of alternative fuels I think we have special the main burner injection devices for consigner loops.

We know how to define consigner loops in order to reach high substitution rates. And we also can offer you all the waste fuel preparation storage and transport plant, and equipment. So what is achievable with this kind of technology for new plant especially is 80% of substitution and more, and you might wonder why is there the need to develop a new combustion device.

So in order to extend your vets I would like to talk a little about the limits which we see if we burn alternative fuels, so if we look for example to the consigner loop. So then we have on one hand the particle size of the fuels. So what you must avoid is that the particle size is too big, and that the fuel is not going together with the gas flow through the container but is directly looking into kiln inlet so if this is happening this causes high temperature in the kiln inlet area and you get problems process related with high alkali so this is normally limiting then substitution rate which is possibly to achieve.

So on the other hand you have of course the residence time that means despite the particle size which must be small enough, you need to have a consigner loop which is long enough so as the rule of thumb we say for really a good and high substitution rate we need residence time the consigner loop of six seconds, and above in order to get a good burn out.

container If you have waste fuels in mind, we have a research development center here in so what you can see here is a lavatory semi-scale wind classifier system, it's a cooling equipment here, what we can do is that check out your fuel how it looks like regarding the availability to be entrenched in the gas holder needs be, put it in a defined gas and check out if particles can follow or not and normally what we see is that every waste fuel contains a certain degree of heavy friction which is not flammable, so this heavy friction is colored in red so it is some kind of freedom engine particles which you most of the time find in your waste fuel, and now we have the second device which you can see at the left side of the laboratory skates we act out which is heated by electric heat and as you can see here baskets so we can determine the mass decrease over time which is happening due to to the combustion and the graph here at the bottom shows you the result of such an experiment, and what you can see is that there is of course a significant influence of a particle size on the combustion time you need.

Here in this case you need 75% more in time you need in order to get a good one equal burn out compared to the very fine fluffy and light affection in the fuel. So if you look to Europe here we have a lot of plants which are manufactured in the early stage, so that means those that tend to have very short consigner loops in order to make good application running for alternative fuels it's normally necessary to revamp those plants into make an elongation of a consigner loop to six seconds and more you can see an example of a such an elongation.

So the benefit is if you can do so that you can really use alternative fuels up to 100% we have different applications in this case, and its possible to go with this fluffy material two dimensional particles up to 80 mm and to run those consigner loops with very good results.

However if you must do such an elongation you are suffering some efforts of course, so that means for example if you are talking about 3000 tons per a day plant and you make an elongation of four seconds, you have not only the consigner loop you have to add but it's really a big mass you are bringing to the preheater.

So example in this case it could be round about 350 tones of material which you bring to the preheater tower and this really causes that you are also need to make reinforcement in the civil structure or even you are forced to build a new preheater tower in front in order to get this stage.

So such elongation is quite big investment and might limit for profitability of your waste fuel combustion. So this is exactly where our step combuster is now coming into refuel so idea is to bring device into the container which is great combuster. So it is possible now to place very heavy and non-flammable fuels on the grade and you have retention time which is above 1, 000 seconds.

So it's really complete different combustion device compared to a consigner loop and even if you have a very shortcut container you can really use very high substitution rate with this technology. So we got him a few quality of this means that you are not forced anymore to use only flammble material, but now you can really use very heavy and big particles in size.

How it looks like shown on this slide you can see here cross section of view of equipment so we have the grade you see it as shaped steps that's the reason why we call the unit step combuster and this grade to size so that we can accept nominal capacity fuels and burn them with 15, 20 minutes of residence time.

You can see here the pipe at the top so this is for tertiary air which we get from the cooler the air brings oxygen you need for the combustion, as well as temperature you need for ignition of the fuel. And the complete unit is then connected to the consigner loop group of any kind.

Then you see that we have splash box here at the top for the tertiary air. This is used in order to bring raw meal to the step combustion for temperatures control and of course we need fuel. So the waste fuel is feed via the feeding cruse from the back into the step combustor and is pushing the fuel onto first grade step you can see here which is a little it longer and then pushed on the steps itself and those steps they are connected with air canons so these are standards the air canons which are operated on low pressure and those canons they push the fuel from step to step, and they make the fuel transport happening inside this unit.

The technology has some advantages, so on the one hand I already explained is residence time, so you have good and perfect condition for the burning of material. We high access levels that means burn out conditions are really perfect in order to get a complete combustion, then it is very simple so you cant see that it's just static pipe without any moving parts especially inside the hot atmosphere only we have the screw and the air canons[sp?] which needs some kind of maintenance, but those parts, they're completely outside of combustion room in the [xx] area.

and it's very easy to do maintenance on those items, and then finally it's very effective because, the fuel is not just laying there on the table on the grade, but be have those cannons and the fuel is all the time moved and turned over, and we get a certain imitation of a fuel for combustion.

This unit has an advantage we have of course regarding the alternative fuel preparation you might know how this looks like. However I brought you shots over view of such fuel preparation plants, which is normally necessary in order to turn municipal waste into the waste fuel. You can see here both picture of installation and for corresponding flow sheet underneath.

So what we have normally is first shredder which is used in order to make open all the gates coming to the procreation plant then the second stage we have the the piece into two different particles and this is done due to effect that normally in the fine erased we have a high portion of everything which is not burning quite this stones, glasses and also bio masses quite more so that you normally do a circulation disappear in order to get lid of those items that are not burning well.

The oversee faction is rich in plastics therefore we call it high calorific faction and this plastic faction you normally in as the oversize of the sieve is further treated in a wind classifier system, so this is done for a standard consigner application in order to get rid of the heavy faction were not for everyone, and finally the fire faction is then further treated in the finer shredder in order to achieve this product quality of 50 to 80 mm with two dimensions only.

So with the step combustor the complete preparation looks different now it becomes much easier of course you do not need anymore of this retraction of heavy effection and there is no need to reduce the parting size any more so with this at the end we just need normally a one stage full preparation that means a fast shredder in order to open the bails which I delivered to the site.

This means OK, you can more waste because there is no need to refuse the three dimensional faction you need less energy for the particle size reduction of course and [xx] you need less money for few preparation. So if I have a theory doesn't look in reality so here are some pictures of waste fuels that can be treated, you can see that it's really a completely different class of material we can really handle very rough, prepared material with the step combuster now.

And we have the first installation in Germany at Thysssenkrupp plant in Legaroff and I would like to invite you now to some kind of plant tour, you can see here the installation and picture of complete unit, so what we have is alternative storage store here and at the front we have the fuel is stored and where we do the dozing and we offer long distance conveyer which is air supported[xx] and finally you see here connection of tertiary air of [xx] which you can see here, so this is the air which is going into the step combuster to preheater tower.

In the [xx] we just receive alternative fuels which are coming from a different supplier, so they are stored and big fuel pipes they are handled with the shuffle loader and there are two dozing so this are moving floor units and then we have some kind of protection sieve, in order to check all that really very huge particles, particle size much above a millimeters extracted before going to the preheater.

In the preheater we reach a few feeding system so on the first stage we have double pen and flap. Where you can see a picture here this pen and flap is needed in order to avoid that forth air is coming to system and then we have distribution that splits up the fuel into two sub shoots which are going to the two feeding screws we have.

We have two screws in order to get the best possible fuel distribution over the grade and also in order to have always some hot standby screws so if you have trouble on one screw you can still operate the complete units. There are screw one of the core ideas in the equipment of the step combuster for this I would explain them a little bit more in detail so you can see here picture on this screw on the workshop is really a used screw which is designed to handle really any kind of material and we have very good experience with those Screws they never had to stop to do any failure the client is also calling them bone breakers so they are really tough machines and those screws they are feeding all the fuel to the first platform inside the step combuster and what you can see in the bottom is a movie we took in our research development center so it's just a model of the first step of a step combuster but it is important it's in order to explain to you the idea behind this first step, so what we create as a fuel pile here in front of these screws.

So this is important in order to get a very constant and equally distributed feed of material. We're not just dropping material inside the unit but it's really very stable and controlled, and you can see that the fuel pile has quite a volume that means also quite a residence time so this is important in order to make the fuel ready for the combustion, so we get all the preheating, the drying, the devolatilization of the plastics and [xx] done already on this first platform.

And finally you can see that you cannot see anymore. That means the fuel pile also protects the feeding spools against radiation heat because we're always pushing you want cold, wet fuels into the system so that the screws are really completely cold. Here from the first step we are pushing the fuel under following steps you can see them here picture, so the steps are really only made out of re-factory and inside we have nozzles and those nozzles they are connected to sunlight air blasters which are now pushing with very low pressure with fuel from step to step, and this is some kind of intelligent fuel transport because we're not just moving the fuel, but we're also lifting the fuel up and everything which is already small enough to be entrenched inside the consigner loop is now leaving to gather with tertiary air units and only a very course particles they remain on the grid it's for the finer burnout.

So have a picture from the consigner to the filling screw upwards where you also can see another quite well. If it's units is done not only for new plants but especially also for existing plants so the mounting is quite easily due to it's design. So it's just a static system which can be even delivered free mounted on sides and then leg out of at what's possible to lift the complete unit in one piece into the pre-heater tower.

we used an adapter piece as adapter piece was installed or connected to the existing consigner loop already doing the first [xx] and for this it was easy now to make the complete installation while the kiln was running, but as you can see here a picture of step combuster is connected to the container loop it was possible to lift it in to make a welding with a complete plant in operation, so we need a couple of weeks of the complete installation all together with the tertiary air duct.

But finally it was only necessary to start looking for only one week in order to get rid of this wall in the ducts and kilns. This is how it looks like inside, so the combustion inside is quite heavy we have fully intense frame development because we have fewer air which we are using for the combustion that is quite elevated temperatures so the burn out is very [xx] to this high temperature treatment of fuel.

This high temperature of course important for combustion, but on the other side you can imagine a challenge for the factory nevertheless we have this developed quite intentively you can see here picture of the new [xx] factory and how it looks like after one year of operation as you can see that it is still in good shape [xx] and it's really possible to operate this plant of this unit with the soft air pulls it without any core information and this is also due to the fact that we really did deep investigations in the refractory quality together with different refractory suppliers.

What is the worst case which can happen is that you get so high temperatures that the ash inside the fuel is melted and that you get a formation of slag such as [xx] is really what you have to avoid. And in order to avoid this high temperatures so we did very deep investigation also on the geometry of a units, if we have in-house CFD calculation which do often so what you can see ventilation help cool or make the temperature control inside right inside going over the pressure special box into the unit so the red color means we have enough so ideas is to make perfect or equal over the complete cross-section, and to have such an smooth airflow that can meet us really distributed but not falling out onto the grades because this of course distinguish the flames [xx] this was tip installation very successful.

So we can see here the results of the performance test. We had a warranty power, assume that of 40 megawatts ,hence you can see that we're easy able to over value more than 50 megawatts doing the performance test. So this went without any problems in kiln and preheater corporation without any problems.

Yeah this is already almost everything which likes to tell you about step combuster and would close this presentation with a short out look, we got into alternate solutions. What I hope that you understand that this step combuster is really a high end solution for very perfect condition of very rough waste fluids.

However, they are also was different possibilities we have in mind, so an alternative solution would be to make some simplification of the system and to make some cuts and to turn this fuel combustion into a fuel preconditioning device, so the idea is to make the steps of the the great smaller to not to use potential a year from year supply to make those short extensional for consign out together with this feeding device to bring it to consign out loop, so this would look like this draft here so the idea is to make such a short extension with the same fitting device and the fast pre-conditioning a table so that you will still have a retention time of a couple of minutes for everything which is time consuming during the combustion process that means for heating up, for drying, for degasification and for the ignition and to really use this time in order to boost your Consigner loop which is maybe limited in space and length.

So with such technology we can say, we have some solutions which is going easy especially for of plants which have very narrow space for example and which really can take an advantage of this minutes of resonance time over few pre conditioning but still a very low installation costs.

Nevertheless so this was something about step combuster but as already shown you are doing beginning we are not limited to this type of technology of course we also have the standard bio processing with everything you need for standard applications also lower and by pass systems process advisors we can offer and everything which is maybe behind for emission of embedment but means also mockery of embedment when we experience for instance 40 years and the DeCONx unit we can offer you together with our daughter company Symex which is situated in Switzerland so we would be glad if we could support you in any kind here for this waste fuel combustion and I would like to meet you later on.

Thank you.

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