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Part 2: First large-scale biomass preparation and firing at Messebo Cement: Michael Suppaner, A TEC (Austria)

The second part of the presentation, co-authored with Getachew Okbay, Messebo Cement Factory. Filmed at Cemtech MEA 2015, 8-11 February, Grand Hyatt Dubai, UAE

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Thank you Mr. Getachew for the introduction before of the situation in Ethiopia and also your plant. I want to go more into detail about the project we did together was Messebo under the leadership of Mr. Getachew to implement this biomass, sorry, biomass plant and biomass firing into the Messebo Cement Factory. Okay.

First here, this is just giving an overview where is the factory located? In northern part of Ethiopia, as Mr. Getachew already mentioned they have two kiln lines, one 2,000 tons per day, one 3,000 tons per day, and up to now after they were changing a couple of years ago to coal firing, they were using some local coal, and mainly South African coal with imported via Djibouti.

This is just a view of the plant which is 2 kilns, the left one, the big one is line number two. One challenge is as Mr. Getachew also mentioned that the materials coming from 4/500 kilometers away where the Sesame Straw farm is located. So one challenge was also to get the weigh to bale the material, it was a density, that the logistic, that the transport of the material is still feasible and reasonable, and this is basically the first part of the, of our project there, of our joint project.

This is what the material looks like at the farm. We see here the stocks to store and this is after harvesting the wheat. Basically, it's taken by the cement factory by Messebo at the harvesting site. Here's the comparison of the fuels which are the moment in use and which are now coming into use. You see the Sesame straw, you see the South African coal, good quality, local coal, relatively low quality, and for biomass, the Sesame straw, excellent quality basically.

You can see that the moisture content is low, ash content is low. Principally wonderful fuel for a cement plant. The firing is as usual in most modern state of the out cement plant, 4o/60% in the main burner, 60% in the calciner, and then the first phase, or let's say basically it's planed to fire the sesame straw in the calciner.

You have the quantity is 6,700 kilograms of the main burner, 10,000, about 10 tons at the calciner on coal. Here we have some calculations which quantities of fuel will be used. At the end of phase one, when the whole plant is running in full operation, plant is approximately 40% of total fuel to be fired in the calciner. Here are the quantities of 10 tons per hour. We're talking about kiln number 2 now, the 3,000 tons per day day lining, phase one.

Here is the general layout of the processing of the biomass of the straw processing plant. We have here storage hole, we've here the shredder line and the intermediate storage, which extraction and then a long conveyor coming here to kiln line number two. Kiln line number one will be coming in phase two

put into this whole system. Here are pictures, we have seen already from Mr. Getachew, similar pictures from the harvesting site. The straw is pressed into bales with a target of 600 kilograms per cubic meter. This makes it feasible to transport it, also a quite long distance. We have to go there, the trucks are 40 ton trucks and here is the size of the bales which are used there.

Yes, it's a very rough flow diagram or flow block diagram of the handling system starting with the baling at the harvesting site, then we have to transport, and then [xx] storage of bales at the cement factory. The plant is not yet in n operation, it is now final the stage of construction and will be commissioned probably within the next four to six weeks, and here you see the storage hole which has the capacity of about 4-5,000, close to 5,000 tons of the straw and bales.

From this plant, with kind of four clips, the bales are brought out to their debaling shredding plants, here's the flow sheet of it. If you are interested in more detail, we can talk after the presentation. I'll push about it, I don't want to go into every single detail now of course of the flow sheet, it will be boring for most of you here. Here are pictures of two lines so that we can guarantee this 10 tons per hour material supply 24 hours a day. We have of course operate as we were told in the previous presentation by using various fuels alternative fuels, it is very necessary to have a continuity otherwise the raw material has to be adjusted newly.

So we have to make sure that this plant is working 24/7 that's why we decided together with the plant engineers to go for two lines. We have here, just the bales are put on here and come to the de-balers and shredders to pieces. You see that the capacity is. From the shredding plant we come to the intermediate storage. With this case, 350 cubic meters, capacity of about 72 tons and the extraction of this is quite special type of Walking Floor extraction. If someone is interested in more detail, I have a video also on my computer, I could show later at our booth in case somebody wants to get more details about this highly efficient intermediate storage and the extraction device, Walking Floor device.

From there via a Weigh Feeder, the extraction from the walking floor, and then which is true and then which is true to the weigh feeder, we have here adjustable feed rate between 0.2 tons-10 tons per hour, so there is a high flexibility given to the plant. You see it's everything under construction still here, as I said, it will be hopefully finished within the next couple of weeks.

After the dosing system we go on the long conveyors, and the first phase to kiln number two, where we see pictures while it was on the erection. Now that we have come in here, we have to go up, it's quite a challenge. In this case for the installation because we had to lift up the height of the bridges for the conveyor to a height of 65 meters and the crane availability gave us a little bit headaches sometimes in Ethiopia because not many cranes are there that can lift to these heights and these weights.

The feeding into the calciner, we do with our own, this is a A TEC product, high safety A TEC Swing Chute for alternative fuels. We use this for RDF fuels, this for biomass. This is, I would say, principally relatively simple feeding device with a very high safety issue here, because this part you see here is lighter.

As soon as the temperature, either the pressure and the calciner is getting too high. Let's say if the under pressure it's getting too low, or if we get over-heating in the calciner, this piece is automatically swinging out closing automatically. The tube and all the equipment above will not be hugged by high temperature in hot case from the calciner. It's completely automatic, relatively simple, very successfully used in many, many plants already.

Also, for instance, in Europe for the RDF firing, we would have the possibility also with this swing chute to use it more less like a burner in case we have a combustion chamber, which we don't have in the case of Messebo Cement Factory, but many plants using combustion chamber, we also can put primary air and we can use it as a burner.

It's not only a treating chute, it's also possible to use it as a burner. One important part is of course, we also learned in the previous presentation that the influence of the fuel on the fire process has to be considered. When we use material like straw, like sesame straw, rice husk, or any other biomass, any other RDF for instance,

we have to be aware that the gas volume in the pre-heater will go up quite considerably. In the case of biomass, we are talking about 8-10% increased gas volume which has influenced eventually on your kiln capacity, because now it is many, many kilns are running on the limits. Everybody needs production, nearly everywhere depending on the economy but everybody wants to squeeze the kiln to the limit and squeeze out usually above or beyond the design capacity of the kilns and when the ID fan, the main ID fan, the filter fans are already running on the limits and you start changing and putting in 40% alternative fuel of biomass, most likely the kiln capacity will come down.

In case of Messebo, this will not be the case after the margin and also we will probably in the later phase, in this plant, upgrade the kiln to even have the possibility to go for higher production, but this has to be taken care of in any case that the capacity of the kiln could come down by using alternative fuel or biomass in case your kiln is running on the limits already.

Of course with increasing gas volume, we have also to be aware that the pressure drop of the pre-heater goes up which not only may cause problems with the ID fan capacity, but also with the power consumption on the ID fan. High pressure drop means also high power consumption. The next issue is of course that the raw meal has to be, the raw material has to be adjusted otherwise you will get problems with your clinker quality, because the ash content of this alternative fuel is very different in coal, and also for coal it has to be adjusted of course, but in case of such biomass where we have very low ash content, the lab has to work out the concept for the raw materials, that's why we also need this continuous feeding 24/7. We cannot just switch on and switch off biomass feeding, and it has to be done continuously in parallel with coals.

And one of the big issue is that combustion time, the burnout time in the calciner, also when you go to the main burner, obvious these materials is usually higher than on fossil fuels, on coal. So the calciner retention time is a very, very big issue in case of Messebo kiln number two, we have at the moment sufficient retention time.

We're talking about, slightly about four seconds where we expect that material will burnout completely and will not create any problems, but we have to be aware if material does not burnout completely in the calciner, the biomass, comes in the lowest stage cyclone, usually in this case is the fifth stage cyclone and then go through into the kiln, will make a problem in the kiln, inlet with high CO, low oxygen.

The oxygen could come down below 1%, the CO could go up to very high values which could subsequently create the problem with dust deposits and maybe even clogging of the lower cyclone stage, kiln inlet chamber which avoid any in cases, in any case. So in case, cement plant is changing to biomass alternative fuel firing, the retention time in the calciner is a very, very important issue to look into, and it has to adjusted otherwise the problems in the operation will definitely start.

Here's a final, basically the final slide here, it's a very, just starting calculation of the savings per year on fuel costs Messebo factory will have. This is a rough calculation, not the detailed feasibility study. Here we have already included the production cost and transport cost of the fuel to the cement plant, and actually, where's the price, here and actually, this price is now slightly higher at the plant, so it's a little bit better even than shown on these slide. But the slide shows that savings of 1.6 in the first phase, this is only Phase I of the project, million Euros, we're talking about [xx] is a very, very viable and very feasible way to go ahead and the side effect is, Mr.Getachew already mentioned this presentation at the end, the ecological impact and I will say the signs Messebo Cement is giving to the cement industry in Ethiopia of social responsibility and ecological thinking is an additional benefit of course of using biomass there.

So basically, that's what I wanted you to explain about this biomass implementation in Messebo Cement Factory. If you have any questions, please feel free. If you want to see more details, please come to our booth, I can show in the computer much more details about this plant and flow sheet, and capacities etc., etc.

Thank you very much.

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