Low-cost solutions for increasing production with alternative fuels: Tahir Abbas, Cinar Ltd (UK)
Filmed at Cemtech MEA 2015, 8-11 February, Grand Hyatt Dubai, UAE
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These are some of the clients, some very familiar ones at the top, but for the Asia and Africa, we have worked for UltraTech in India and also for Votorantim plant we're working on now. And Arabian cement - ACC, also for Chirag cement in Pakistan, and also for Riwal cement and Canakkale in Turkey, and also for [xx] team plant there, and AKRO plant in Sudan. For Holcim alone, we have completed over 30 projects including their largest plant 12,000 tons per day at St. Genevieve. So, when it comes to the upgrades and that was the question asked earlier on with the ID fan capacity, these are the general criteria to look at the maximum capacity which can be obtained from the plant. So cooler area 40-60, 60 on the upper side tons for day meter square, and then the burner zone thermal load 6 Mega Watt per meter square, cyclone cross section area where the material would flow 100 to maximum 120 tons per day meters square. Kiln volume, 6 tons per day meter cube, Kiln Fill, 10%. Kiln velocity at the pinch point upper limit to around 35 meters per second, Kiln Burner, 7-12 Newton per Mega Watt, but when it comes to calciner combustion and calcination in a calciner, so there's no fixed criteria. There are some
criterias of the residence time, and the velocities, but various manufacturers or technology providers are using different criterias. That's the AFR co-processing and that was the question asked before. Water, the effect of the water content on heat consumption? What will happen to heat consumption and also the production law.
So when the alternative fuels would have higher water and the ash content, then they have to be paid for or having a gate fee. Whereas the false air and Oxygen level can be optimized or reduced through the process and combustion improvement. So, these are four main criteria. This slide was presented before and heat consumption would normally go up and production would go down.
That's four trend plant, Holcim plant and they were firing chipped-tyres, and that's the area where the chipped-tyres were fired there, and it's very important to note, these calciners are designed for micro size particles, and not for two inch by two inch typical cheap sizes of the tires. So, any chipped-tyres fired over air and the velocities in this region are around 28-25 meters per second which are designed for sub-micron or micron particles.
So they would fall down and plant was absorbing build up in the hot kiln area, so they could not fire more than 20% of the thermal substitution of the chipped tires. So, a throat restriction was added there to suspend at least the smaller size chip particles or chip sizes of the tyres and the velocities in this area would be around 40-42 meters per second at the length of around 3 meters, and that would be just enough to revert these falling chips back up with the upward flow.
So that's the computational grid, I won't go through the details but just in this area, a venturi was added there to have minimum pressure drop and higher velocities in the localized areas, because the falling chip have to be de-accelerated and after reaching the zero velocity or the stagnation point then after losing weight, losing volatiles, and burning, they would be lifted up and then we can go to higher substitution rates.