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Efficient kiln seals – a strategic component for kiln optimization:Yoann Picard, Iteca Socadei SAS (France)

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

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The kiln seals of course are now a big component of your plant so that's the biggest one. But I will try to show you, if you increase the efficiency of your kiln seals, how you can save energy. I will give you figures, I will give you some case study to know how you can optimize your energy consumption only by increasing of kiln seal efficiency.

So the problem of kiln seals, the problems, is in the inlet and the outlet, is you have cold air, you have false air entering into your kiln. So this cold air, you have to use, you're losing some kilo-calories, you're using your burner only to compensate the problem of this false air. So you are losing a lot of energy. Some plants they know approximately how much we are losing,

 some plants we have no idea how much we are losing. If we list all the problem, it's not only energy savings, the main problem of inefficient kiln seals is the fuel consumption of course because of the false air. You have also production capacity decrease because if you burn your fuel to compensate the false air, you don't burn your fuel to produce kiln air. I will show you some figures.

You have also to think about the ID fan electricity consumption. If you have false air, your sucking false air with ID fan, with no force air your ID fan can be used only for the process, not sucking false air. If you have dust ceiling, you will also have a escape of dust maybe if you have positive pressure into the kiln, you can have also hot material escaping from the ceiling, so you will have damage on every mechanical component in the area, fans, belt, motors, something like that.

So you have also maintenance cost, difficult to estimate which you have to take account about it. Also important, it is unstable pressure into the kin. If you have false air, you cannot control as best as possible the pressure into your kiln, so with a perfect sealing you have stable pressure into the kiln, your operator will manage your kiln better.

And also just environmental concern because in some plants, even in UAE, we have one of two plants in UAE where if you're near cities, if you're in the middle of cities, you can have if you have escape of the dust from the sealing, it can be a problem. So you have also environmental concern with the sealing not only the tower, not only the filter you have also dust escaping from this side.

Some examples, the most common seals we can see is piston, spring, lamellas, we have all kinds of systems but mainly lamellas and piston. So you can see here are some typical example is the piston seal, you have the gap, here you have the red light inside, so it's very little gap, 1 cm may be 2 cm but I will show you with estimation, calculation with even 1 cm, it's a big loss of energy, okay.

Lamellas also, you know that lamellas, it's not so bad sealing at the beginning when it's new but you have to do a lot of maintenance. If you shut down, you have to replace some lamellas, you have to put cables to keep in pressure into the kin, it's not really good solution. Another example, here you have kiln with positive pressure, you have dust escaping, it's a problem for the surrounding area, you have no system to [xx] the dust and here even hot materials escaping, may be you have a ring which is the kiln.

So even for safety, it's not a good solution for you people walking around, it's hot material maybe 700 degrees, very dangerous, okay. I will not explain you all the mathematical formulas, we are not here for that. It's just to show you you can easily in your plants, estimate, you can estimate the air flow entering into the kiln, you just observe how much leakage you have 1cm, 2cm, 3cm, average leakage. You can estimate air flow and with some values of temperature and pressure, outside and inside, you can estimate the kilo calories you are using to compensate the problem of false air.

And if you know the cost of your energy, you can estimate how much money you're losing everyday, every week, every month, every year, only because of the false flow problem. I did the calculation for you in average case, inlet seal, only the inlet seal, a kiln of 4m of red seal with normal condition, normal cost, I don't know exactly the cost in UAE, it depends the countries.

But normal cost, you can see that for 6mm gap is nothing, 6mm is really nothing. With normal pressure, you can reach per year $150, 000 dollars lost only to compensate the false air problem. So today the plants are trying to catch money to do some savings, but only by replacing the seal of mechanical components, if you succeed to increase the efficiency of the sealing, you can reach this kind of savings.

In the outside, it is the same. The savings are less but they're still interesting. You see, 10mm gap, 1 cm, you can reach approximately $100,000 dollar in these cases. Also an important thing, the stability of your sealing system. When you install a pistol, lamella, spring seal when it's new, it's okay, no leakage.

But after some weeks, after some months, the leakage begin to appear, and you have to wait for next maintenance, next shutdown to repair it and to have again a good ceiling. But between two maintenance, you've a loss of efficiency here and this loss of efficiency, it's a loss of energy and the loss of money. A good sealing should be to reduce the time between two maintenance, of course, if we can but most between two maintenance to keep constant efficiency.

It's clear for everyone. So what should be the good request toward to design a good sealing. First have a perfect sealing, avoid false air, of course. Second one, improve the pressure stability into the kiln to allow your operators to control it with better efficiency. To have a constant efficiency, like I said before, to limit the maintenance to the minimum, if every shutdown you have to replace your lamella, piston, it's a cost also.

And also able to installing every kind of king. That's the list of things you have to see when you design a good sealing system. so our French company named Iteca, we have one solution some of them knows already, they have been to our plant, some of them maybe don't know or you just heard about it. So our solution is sealing with Graphite block system, inlet and outlet.

So graphite block system, it's not a new technology, not at all. Actually the first sealing system with graphite block was installed in Lafarge in 1980. It's a patent made by Lafarge, only for Lafarge plants at the beginning. No Iteca is the owner of this patent, so we spread this technology to all the plants.

But it's 40 years experience on this technology. It's already proved it's efficiency. How it looks like? You can see you have a sliding track here on the kiln seal rotating with the kiln, sliding track here you have a fixed spot and between both of them you have graphite blocks. Graphite blocks are not very big, they're approximately this size and the graphite blocks are maintaining pressure on the siding track with cables, you can see here on counterweight. The principal is simple. I let you see the video, so you see [xx]. The principle, if you have here is the kiln rotating, here is we have the inlet, you have a sliding track, we put a sliding track to compensate the ovality of your kiln, so it's a perfect circle, okay.

So graphite blocks are maintaining pressure on the sliding track with a cable on counterweights. We have a cooling system because graphite needs to be cool to increase a life time of the graphite blocks. So cooling system, full independent, no air go to the kiln of course. To avoid dust on hot material escaping from the kiln, you have a system of scope here besides of sliding track, with the rotation of the kiln it's allows dust to come back into the kiln. If you have a big problem, you have huge amount of dust escaping from the kiln, we have a system of hopper here with a double valve track to expel this hot material to a secured area. You have no dust no hot material, just near the sealing point, so no problem.

No dust escape by this way, only by this way. The benefits of graphite blocks there's a lot, if the kiln is moving in translation with piston, it cannot follow. With graphite blocks, no problem. So the graphite blocks continues the sealing, no problem with the translation of the kiln. If your kiln has ovality, that perfect circle, we put the sliding track with a perfect circle but even if you have a few centimeters more of ovality, some graphite blocks will follow.

I will show you a video where you can see the graphite blocks following the movement of the ovality of the kiln. This is just a drawing to show you that if you have little dust escaping, it fall into the scope and with rotation of the kiln, it come back inside. If you have problem like the ring for example, you have hot material escaping, it will go here, you have some detectors, the double valve tracks open and it expel it to a secured area, no dusting or whatever. This is to show you the cooling system, it's not a big cooling system. You have one flow from the top, one flow from the the bottom to protect the graphite blocks. You can see the hopper here, so you see kiln area. Here you can see, counterweights on the cables, very easy to operate for your team. So you can see the graphite blocks, maybe you will see in between graphite blocks where is some leakage between two blocks. Actually the graphite blocks are S shaped in order to overlap together, so you have no leakage between two blocks.

This view is interesting, it is a view of the top. You have this sliding track, you have the graphite blocks, the cables put in pressures of graphite blocks, and you can see here there is a deposit of graphite. In this case the kiln is in translation, so the graphite block with time, let a deposit of graphite.

So you have contact between graphite blocks on the deposit of graphite. So two benefits, first one, no leakage. Second one, no lubrication, graphite is lubricating by itself, no need to add anything to lubricate it. The noble benefits, graphite block's life time is at least five years. You wear approximately one centimeter per year of the graphite.

So you can keep it at least five years, some plants that succeed to keep it to 10 years, but most of the plan is five to seven years. So you don't have to change every shutdown, every year or every two year, your the set of graphite blocks, for five years you have no big maintenance. And also you have a constant efficiency.

At the beginning, the graphite block are straight, but after some weeks, they will take the shape of the kiln. Once we have the shape of the kiln for five years, constant efficiency. It's another video, so now you know a little better, so sliding tracks and graphite blocks, and we see there's a little ovality of the kiln, as the graphite blocks you see they follow the movement, grand contact here and they follow the movement of the ovality.

For example with lamella seal, with time we'll have a problem, we'll have some red lights. A more interesting video is to see at night. One of our customer took this picture at night, so if you are not sleeping, if you want to visit your plant at night, you have no red lights, okay. So no leakage, no false air. The installation, one shutdown is enough.

The first point is to install the sliding track, perfect circle will compensate the ovality of the kiln. We install the fix part with the hopper, to evacuate the hot material, we install the cooling system, we put the graphite blocks on the cable, on the counterweight. So the total installation, commissioning is approximately nine days, for one seal.

The same for the outlets, the principle is approximately the same. The only difference maybe is a way to fix the sliding track to the kiln because we need to let the nose ring system cooling to operate well, okay. But the principle is exactly the same. Just one point about the cooling system of the nose ring, if you increase the efficiency of your kiln, if you have no false you will also increase the temperature of your nose ring. So sometime you some plants the cooling system is not enough size to cool enough nose ring system, so we come, we look if your cooling system is enough and we can install a new one to compensate the increase of temperature of the nose ring system of the outlet.

Just to resume the benefits, so we adapt on every kind of kiln, [xx], we don't modify the kiln shell. The most important for you is fuel savings and also production increase, I will show you after some figures, some case study, you will see it. The typical payback, if you have big problem on your sealing system, it will be six months.

Average value is approximately 12 months from the payback, even if you have little leakage. To show you the efficiency of the kiln, it's one example. This kiln was installed in 1996, I think it's Idlebird group. So it's a picture in 2004 and this is a video in 2009 so 14 years after, still in good status.

Just to finish, to show you a case study, it's a plant in Asia. So before we have lamella at the inlet, [xx] we have graphite blocks, the outlet is the same, we had lamella, [xx] graphite blocks. Here, you can see we had the big problem, of course, in this case but what's interesting is that the we compare before and after, before and just few weeks after.

You can see the prediction, they keep the same rate, exactly the same rate. They didn't change anything else than the kiln seals, okay. What's interesting is the coal burner, they decrease the consumption from 6.5-5.8, 10%. They change kiln inlet and outlet, only with the change where we would use a coal burner by 10%. Also the pre-calciner burner and also ID fan electricity.

Of course, 1.5 is not big one but if you compare everyday, every week for 10 years of use, it's not a little amount of money. More interesting, we came back six months after to take the data. It is the view of the control room of the plant, so it's not very clear but you have a real value here, so six months after we have new datas, so what happens?

They increased the production by 6%, okay, they come back to the same consumption of energy. So that means now, we are not losing energy to compensate the false air, we are using the same energy to increase their production. Actually you can choose, you can keep the same production and reduce your energy, or you can use this energy to increase your production, it's your choice.

ID fan also, the ratio between production on ID fan electricity is 7%, on total consumption by turn off clinker 6%. In this case, of course, the ceiling was in a bad status but even in your case if you divide this raise by two, only by replacing the mechanical component kiln seal, it's interesting. We did some estimation in this cases, how much money we have save per year, it's huge, okay. So you have to take care, if you have either 1 cm or 2 cm of false air.

Even if you divide this number by two or by three, the investment is interesting. You lose nothing, you can, it's a huge amount of money, every year. Just to tell you, now we have have approximately almost 200 blocks seals in the the world and mainly in Europe and Asia, 98% of them are still in operation since 30 years now. Just to finish, I have a calculation file, an excel calculation file which you can put your own figures, kiln diameter, pressure, your cost of energy, all the values you have you can do it by youself, if you're interested I can give you, you let me your contact I can give you or you can estimate how much is the cost of your false today. So we usually provide to our customer this file, they put their own figures, production [xx]. They put all their datas and the other approximately the savings for you.

Okay, thank you very much.

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