New cyclone preheater system boosts productivity
With over 135 years of expertise in pyro technology, our latest top-stage Counter Current Cyclone (CCX) has proven to be a revolutionising solution in the pyro processing area to cement plant owners who wish to enhance their production, lower their fuel and power consumption by a significant amount.
With traditional cyclones in which co-current heat transfer occurs between the material and gas stream in the riser duct, the exit gas would have a higher temperature than that of the material by 5-100C, but with CCX, as the name suggests, the use of counter current heat transfer mode between the material and gas within the cyclone, leads to an increase in the heat transfer efficiency, resulting in the material having a higher temperature than the preheater exit gas by 60-700C.
The CCX is an attractive buy for new installations as well as for retrofits and upgrades. For new projects, the CCX will decrease the initial cost of the preheater structure and installation time.
A simple comparison of a four-stage preheater with CCX and a traditional five-stage preheater for a 3000 tpd clinker production could result in a height reduction of more than 12 m of preheater structure. (See illustration for comparison). In existing preheater towers, the acting loads on the structure usually limit installation of larger top-stage cyclones than originally installed. However, due to its lightweight design, the CCX is well suited for such upgrades. For plant owners, this means the ability to boost preheater operation at a lower cost.
CCX Operating Principle
The CCX cyclone combines heat exchange and material separation in one process, ensuring a more efficient cyclone with low pressure drop.
Unlike conventional cyclones, the raw meal is fed to the top of the CCX and dispersed to the gas stream from the centre via a rotating spreader. The gas stream enters the cyclone through the riser duct of the next stage cyclone. As the material travels towards the cyclone wall, heat transfer from gas to material occurs in a more efficient counter-current transfer mode and the material and gas travels down to exit through their respective outlets.
Separating material from gas is done in the same process. The material will travel towards the periphery of the cyclone due to the centrifugal forces acting on it and exit through the material outlet situated at the bottom by gravity. The gas stream exits the cyclone through the gas outlet duct/ centre pipe also situated at the bottom of the cyclone.
Both material and gas flows naturally by gravity and centrifugal forces. Changes in flow direction, as in traditional top stage cyclones are avoided, leading to reduced pressure drop, as the work required to lift material is eliminated. Comparing the CCX cyclone with a traditional top stage cyclone of similar flow condition, the pressure loss is lower by up to 50 per cent.
Benefits of CCX
Savings in fuel due to reduction in net heat consumption by 8-10 kcal/kg clinker.
Savings in power due to reduced pressure drop up to 50 per cent.
Increase in capacity up to 5 per cent.
Lowest civil/structural cost in new preheaters
Fast, simple installation
High flexibility for retrofits and upgrades
Performance results from Ivano Frankvisk Cements
Together with Ivano Frankivsk Cement, we recently successfully completed a CCX upgrade at their site in Ukraine. The results have proven very successful (refer table) and now led to the order of another CCX for their new production line.
A 30 per cent increase in production was obtained with other modifications including CCX.
In India, five CCX cyclones have been sold to Ramco Cements-Jayanthipuram, OCL India Limited-Rajgangpur and JK Cement Works-Mangrol.
Mykola Makoviichuk, Production Director at Ivano Frankvisk Cement, stated, "When we saw reduced pressure losses of 40-50 per cent, we were pleasantly shocked! This cyclone has the equivalent effect of 1.8 standard cyclones, which meant we could reduce one section of the preheater, ultimately reducing construction costs. I want to thank FLSmidth for their collaboration on this upgrade project. Their new CCX is far ahead of anything else on the market and enables us to increase our outputs. We are very happy with the results."
Design features of CCX
Rotating Spreader with VFD: The raw meal is fed at the top of the cyclone to the spreader which disperse the meal to the gases entering through the riser duct. It is easily accessible and changeable from the access platform at the top of the cyclone. As a mitigation plan, in the unlikely event of any issues in the spreader, the CCX can operate as a DDX (Downward Draft Cyclone), the only difference being the feed enters along with the gas stream from the riser duct. In this case, the meal distribution box will be a part of the second stage riser duct which allows the plant to operate without stoppage.
New densulate lining: CCX comes with a new two layer light-weight lining concept. This reduces lining weight by approximately 60 per cent compared to traditional lining.
The new CCX delivers cement plant owners greater opportunities to reduce initial installation expenses and improve plant operations. Leading the way as the next generation of top-stage cyclone technology, the CCX is designed to make the preheating process more economical.
ABOUT THE AUTHOR: Ram Kumar Sridharan, Product Line Manager-Pyro, FLSmidth.