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Advanced combustion technology for low grade and course alternative fuels: Sebastian Frie, ThyssenKrupp Industrial Solutions AG (Germany)

Filmed at Cemtech MEA 2015, 8-11 February, Grand Hyatt Dubai, UAE

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Welcome again to this the presentation of the PREPOL Step Combustor which is a new developments of the ThyssenKrupp Industrial Solutions, formally known as Polysius. My name is Sebastian Frie, I've been working quite a long time in research development and I was deeply involved in development of this technology.

And it's my pleasure to show you today this technology and principle, and to give you also an insight into the first operational results of our first installation in Germany, which are quite promising. What is the Step Combustor about? It's some kind of green technology, so the idea is to make it possible to burn alternative fuels, that means wastes or bio-masses.

I think one of the major problems of our time is to get rid of those, especially of those municipal waste and you might know that it's quite a big effort in order to turn those wastes into some kind of fuels that can be burnt inside cement kilns. So, normally you have only a calciner loop of a combustion of fuel and towards entering zone burner, and into those cases it's necessary to treat the waste in a very deep way, so that the fuel is fly-able inside this calciner loop. So as a consequence normally you can only accept two dimensional particles,

that means foils or something like this. With a particle size around about 80/100 mm of which, so this is a necessary effort to produce such kind of fluid, which is fly-able and now with all our system which is some kind of great incinerator that is also used in incineration plants. You can now accept, they are very lumpy and cost alternative fuels which are non-fly-able, that means you can place the fuels on the grate of our combustor, and now you can accept very coarse particles that are 3 dimensional and have particle sizes of up to 300 mm.

The system itself is quite simple, it's just some kind of pipe, some kind of Calciner extension and you can see here an example of how it is adopted or re-co-fitted also to existing pre-calciners, here's an example of our design. So you have a combustor and the combustor is just placed at the bottom of Calciner loop directly over the Cane In-nets hosing.

Then you have a tertiary air connection which is going to the system, and you extract a meal from the second lower most cyclone and bring it to the units for the temperature control. So, basically it's a quite easy and it's possible to bring this system to any kind of pre-calciners. Let's go a little bit more into detail, here we have a site view of a system and you can see now here we have the grates, and as you can see the grates is formed in steps, that's the reason why we call it step combustor, and this grate has area which is suitable to burn the fuels for around about 15-20 minutes.

So, if you compare that to normal 3-5 seconds, you might have standard pre-calciner loop. You have particle retention time which is round about 300 times higher compared to the standard technology, and this of course has the big advantage that you really can burn almost everything inside here. Ignition is done with help of tertiary air, so you get the air from the clinker cooler, and the air is hot enough in order to make the ignition of fuels possible, that means, you do not need any kind of burner, or other equipment so that you'd just let the air flow above the grate which makes the ignition and also delivers of course the oxygen which is necessary for the combustion.

And you can see we have here a splash box at the tertiary air duct, so you just bring near to the air duct in order to get a good distribution of the meal and this meal starts before calcination reaction inside the unit and therefore we have temperature control or cooling effect of the meal here. The waste is brought to the system of a feeding screw, and these feeding screw now pushing the fuel into the unit and you can see that the first step is a little bit longer. So, on this

first step we get some kind of fuel pile which has already a residence time of a couple of minutes and this fuel pile is good for drying process of a fuel if they're high in moisture for the heating up and then for the ignition. And then the new coal's incoming fuel is pushing the fuel from the pile to the first steps, and then we have a couple of steps afterwards and those steps, they are connected with standard or ordinary air cannons and those air cannons, they are standard but they are operated in a different way than you normally do it. They are just fields to over pressure over on the[incomprehensible] so you don't really get a short but soft air push to the fuel, and the fuel is then pushed from step-to-step.

What are the main advantages of these technology? First of all, it's safe application. Safe means, we can use a lot of air excess [incomprehensible] tertiary air here, so we do not have any risk of CO formation or even hydrocarbons, and we have here a quite a long residence time as already mentioned, so we have a good burnout result. Then it is simple, it is simple because it is static system, so as nothing moving, it's just a some kind of metal pipe at here to the calciner, and the only things that are moving they are outside of the unit, so the screw is outside, and also air cannons or oil equipment you use is well known in the cement industry and it's completely outside of hot combustion chamber with former and chemical stresses and easy also to reach for maintenance.

And then it is finally also effective and it is effective because one of the advantages that you use those air blass in order to push up fuel and you can imagine that it's every pushes some kind of agitation effects so you really improve the burnout since you bring the fuel in, almost perfect content to the air.

Of course, the system has also an economic advantage in order to expand your vet, we have short looked to a standard application you normally need in order to turn the waste into a fuel. So normally you have a waste preparation plants and you can see a typical picture of such an installation, a default of course, but normally they have four steps.

So in the first step, you normally have a first shredder system and this is needed in order to receive bio-material which is normally coming to the plant in compressed manner, just to get the bikes away and to have really a loose material. Then we have normally a seving, type of seving, it's necessary in order to control the heating value of a final product, that means we have a seving and we get rid of every small particle type of fuel, and those small particles, they are normally rich in bio masses, and stones, and small glass or shapes, and something like this, so you can extract them in order to get a higher heating value.

And then the third step is the wind classifier. In the wind classifier, we normally blow against the fuel and to check all the, if fuel is fly-able or not, so if you have a standard application then you must refuse everything which is 3 Dimension and take it away. And then finally, you have a second shredder step which then cuts down the fuel to the final size.

So if you bring the step combustor into the game now, everything becomes much easier, because at least the second step at the end, that can be eliminated because they are needed in order to control the particle size, and in order to adjust the quality regarding the property to be fly-able inside the calciner loop. So, now we have to grate into, do not need other steps anymore.

And you can see that you can use more of the waste as a fuel, and of course you need less energy here for the shredder and for the separator, and it's also obvious that you spend less money for the installation, but which is more important for driving those very poorly consuming machines. Let's, have a look to a first installation which we have in Germany at the Holcim plant in Lagerdorf. So this is an operation now since November 2013, that means, I can show you today we're, experience we gained during one and a half year, we went to a lot of operation.

Here in the front, you see alternative fuel storage hall then we have long distance tube-conveyor to pre-heat a tower, and here you can see a buff of thekiln, the tertiary air duct, and for connection to a step combustor which is then connected to a calciner loop. If we follow the raw material of a fuel from the beginning to the end, so then we start with the storage hall and we see that it's quite easy, we just have some piles of fuel which are then placed before a shovel loader into dozing boxes, walking floor boxes in order to get the mass control, flow to the combustion equipment, and afterwards it's going upwards to into the pre-heater [incomprehensible].

Here you can see the end of long distance conveyor of a first step, it's a double pendulum flap, so we have two layers of flaps and all are to a void, that's false air coming into the system, and then we go further down here in this shoot, and we have distributor gate, this gate splits up the fuel unto the tool fittings screw which are underneath, you can see them here, and you can see internal view, but has an internal shoot, and this shoot is moved to one screw or to the other screw, and this is only done if that [incomprehensible] pendulum flap the buffers in close position, that means the fuel is falling down only if this internal shoot is in position, and therefore, we have a very smooth and undisturbed fuel flow to the combustion.

Here you can see the feeding screws, here at the workshop, you can see compared to this work idea that they're quite big in size, they're really well equipped in order to accept any kind of fuels to be handled, and those feeding screws are now pushing the fuel unto the first stepping.

What you can see here, this moving, is a trial we did at our test center in Germany during the development, and you can see now how the fuel is pushed onto this first step, and you can see the advantage of its first pile. So you can see that screw itself is completely covered by the fuel which is coming in, so you do not have any kind of former stresses to the top of the screw. When you have a quite a long residence time before the start of ignition, and you can also imagine that this fuel pile then itself has some kind of natural sealing effect against of [incomprehensible] to come into the system.

This is a view on to the steps, so this fuel transport is some kind of intelligent fuel transport because we use only standard air cannons, air vessels which are connected to the nozzles, which are inside here of the refractory. And now you have the advantage so that you have some kind of internal wind classifier effect, you know that we are [incomprehensible] over a grate, so we have certain velocity inside the combustor and if you make now short of a fuel and you lift up the fuel and you get internal separation effect. It means, only those particles which are really heavy and which must be treated on this grate, they are falling down again and everything which was already fine by nature or which has already been burnt down to such a particle size is now extracted over two a calciner loop. So, we really only treat those materials on the grate which really need this treatment and therefore we can have quite high mass loads per square meter.

So, this is another view of unit with the steps and the nozzles inside. Here are some words regarding the installation of the units. We delivered first step combustor completely mounted here on site as a complete piece, and so it was possible to lift a complete unit by crane into the pre-heater tower. At the beginning of a project, we had to stand out to kiln shutdown and for the shutdown we prepared already a adaptor piece, and this adapter piece was connected already at the beginning to the calciner loop and with this way, it was possible to lifts and to install the complete units during the kiln in operation.

That means a complete mounting process was online with the kiln in operation, and finally, it was necessary to just stop the kiln for one week from clinker to clinker only for cooling down and taking this refractory oil outside of the adaptor piece in order to receive a final air connection. Now, the commissioning started in November 2013, it went extremely smooth. If you put a mild adhesive prototype installation, you can see here the blue bars, they are the run-time per day in average, and the red line is for thermal power that we achieved, and you can see that we had already an average run-time of 22 hours on day 4, and here you conceive a poor performance of a kiln and this was only due to a [incomprehensible].

So from this point of view, very successful and also the thermal power, already 80% of warranty value per day and an average was reached after 9 days. Here you can see the type of fuel switch used in Lagerdorf, on the one hand we have, municipal waste which is pre-treated, you can see here the movie from the scatter, and the second fuel is a tar or roof paper and the plant is mixing both together in order to burn them inside the unit. And then some impressions from the internal of the combustor, here we can see two pictures which are done from the sites looking on the steps. So here, during the startup and then in full operation, and then we have here this movie, and this is done with a Control-Comma which we have in the back, and you can see it's burning quite intensively which is the proof of a good burnout behavior.

Regarding the development, the most challenging step or need was to find a refractory solution here for this units, so we can imagine that you have quite a higher level of stress on the refractory regarding thermal loads and also on [incomprehensible] loads, and here you can see a picture of steps after one year of operation. So they look quite nice where you do not have any cracks, no coating formation that you can also see that the air cannons can really permanently move the fuel away.

Now this was possible due to very intense investigations regarding suitable refractory properties, until we did a lot of testing also together with Refra-Technik and finally found a solution. You can see here such a test where you melt or where burn to such a temperature, or fuels to such a temperature that it's netting, and then you can check out if slack which is formed can infiltrate for the refractory.

Second reason that this is working so well also with the refractory is the design of the geometry shape until you use the CFD calculation in order to find best geometries. The challenge is of the idea is that you must have meal inside in order to control the temperature. So you can see here the meal concentration at the top of the ceiling, the more red it is, it means you have more particle concentration inside, so we have our special box here at the top, and we can really have a good cooling effect at the ceiling where the temperatures are the highest, but the flow is very smooth and strict, so that we can avoid that any meal is falling down onto the gradients results and any kind of ignition effect, extinguishing the effect, and so it's possible to have both, good cooling and high combustion temperatures.

If we've to look to the process parameters, we're also quite positive. We don't have any increase in CO emission after the pre-heater. There is no increase in SO3 concentration of hot meal. We discussed this already this morning that SO3 cycles may form if you have incomplete combustion, but here the server concentration was low, and also the Calciner-end temperature is unaffected which is also of course also a proof for a good burnout. And finally, also the coanting formation didn't change, that means there's no problem with coating inside the complete Pre-heater. it also has the benefits [incomprehensible] the air emission will stable, the NOx emission even drops after installing the sub-combustion because we have here some kind of air staging effect. And finally, you had the warranty test then last year in May, you can see here we've achieved former performance over six days of performance test. Colored by mix of the fuel and you can see here the warranty value was 40 Mega Watts, and it was very easy to reach those values. At the end of the test, we even demonstrated a full capacity, we reached here up to 54 Mega Watts, which is more that 25% over the warranty value. And so on V-line, we had no fundamental problems during the commission.

We had no affect of the kiln process. This the process reacted very positive on this new installation. We tested a wide variation of different fuels, they also went very smoothly, no problems here. And we had very high throughput from the beginning. So all in all, the client was very satisfied, he also was very nice first installation here.

Before I come to the end, I would like to have a short look also to the future. What is maybe possible or interesting for you is, it is also nice to have a simplified version of a step combustor, which basically looks exactly like the big one, you can see here we would also use here a feeding screw, but we would make the combustion units much shorter. So the effects that you have is the residence time on the fuel pile on the first step, good [incomprehensible] ignition behavior, but we would not install for the short version of tertiary air duct, so that's kind of application might be very interesting if you just at the beginning with alternative fuel uses or if you have a pre-heater or one where you have limited space available.

This is an example of such an application, if the calciner has a very complicated shape, then the unit becomes quite small, and would be a very nice possibility also to bring this to existing pre-heater. Yeah, I hope I could raise your interest into this new technology and thank you very much.

Advanced combustion technology for low grade and course alternative fuels: Sebastian Frie, ThyssenKrupp Industrial Solutions AG (Germany)

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