The kiln is the heart of the cement plant. Inside, temperatures reach over 1500 °C as raw materials are transformed into clinker. They are also big, reaching diameters of 6 m or more and lengths of over 100 m. To operate in such conditions, components must be well designed and flawlessly made. No easy task. But one in which we at KHD have a long and distinguished history.
Can your kiln take the heat? Ours can. Read on and discover how we engineer our kilns to thrive amid the burn.
Getting it right from the inlet
By the time material enters the kiln from the preheater, it is already hot; the chemical reactions that create clinker, already underway. So, you really want to avoid material leakage and heat loss in the transition – which is the job of the kiln inlet.
Our kilns come with a couple of features that make sure the inlet does this job – and does it well. Firstly, a scoop ring runs around the diameter of the kiln at the junction between preheater tower and kiln. This ring catches any material that falls out and returns it to the kiln, so you don’t lose valuable product.
Meanwhile, a choice of either spring-loaded or pneumatic seals keeps hot gas and dust in, and false air out. This helps maintain stable operating pressure, which facilitates greater process efficiency and, ultimately, lowers energy consumption. And that will keep the accountants happy.
Floating tire mounting
Much like the suspension on a car, a kiln tire mounting should compensate for uneven loads and stresses to provide a smooth ride. Which is exactly what our floating mounting does. As a bonus, it also makes adjustments easier compared to a fixed or splined mountings – with no welding on the rotary tube required.
But what about kiln deformation (ovality)? We are happy you asked! Our floating mountings offer similar performance as splined fastenings. So, you can enjoy the benefits without risking higher degrees of deformation – and hence extend the life of your refractory.
Don’t stop turning
Whatever you want your kiln to do, you need it to keep turning. Because if it stops with all that hot material inside, there is going to be damage. A lot of it. You could well end up with a kiln as bent as a banana. Yes, it is a nightmare scenario. But one you must avoid nonetheless.
To give you peace of mind, our kiln drives are designed for ease of maintenance and reliability, even under extreme conditions, and can safely restart from standstill, even under load. We also offer an auxiliary diesel motor as an emergency power supply, in case main power fails.
Trouble-free roller bearings
You have bigger things to worry about than roller bearings. They are however critical components that you don’t want to fail unexpectedly. It is why ours are built to keep rolling – even under exceptional loads and without a lot of maintenance (which is straightforward when it is required). In short, they are simple, robust – truly, trouble free.
Hydraulic thrust roller
This nifty little device is designed to control the axial movement of the kiln, and thus ensure uniform contact between tires and supporting rollers. In doing so, it maintains an even wear across components, extending and regularizing time between replacement, as well as minimizing the risk of breakdown.
Our two-pier kilns come with one hydraulic thrust roller under the first tire station (from the inlet side). For our three-pier kilns, a second hydraulic thrust roller is installed at the middle tire for bigger kiln sizes.
It also continuously monitors kiln movement, automatically informing the control room if it passes pre-set limits to allow corrective action to be taken before damage can occur.
Cooling? Don’t sweat it.
It gets hot inside the kiln. Really hot. In ideal conditions, the kiln forms its own defense against this heat: a protective layer of clinker that coats the kiln wall. The use of alternative fuels and raw materials, however, can make this layer unstable, exposing the refractory and shell to extreme thermal stress.
To counter this, cooling systems can be installed at critical points along the kiln: for example, at the central clinkering zone where the heat is most intense. Lowering the shell temperature supports the formation of a stable coating. Which in turn promotes process stability and lower refractory wear. Both of which are major headaches, cured.
- Tyre cooling
- Tyre cooling
- Sintering zone cooling
Coming to the end: kiln outlet
We have come the length of the kiln and reached the end – the kiln outlet. As at the inlet, a choice of either spring-loaded or pneumatic seals keeps pressure inside the kiln stable. Some ambient air is however carefully guided around the outlet to cool it, mitigating the thermal stress caused by the hot clinker and gases as they exit the kiln.
Rotary kilns are the industry standard. Everyone makes them! So, what makes our rotary kiln components better than the rest?
Robust, reliable and worry free
You rely on your kiln to do its job, day in, day out, without trouble. With our history of engineering excellence and reputation for quality, we provide kilns and kiln components that bring peace of mind. Long-lasting, low maintenance, proven globally in hundreds of installations: we know what we are doing and we lead the world in doing it.
- Revenue of high availability
- Revenue of low availability
- Total cost of ownership (OPEX & CAPEX)
Easy to operate, easy to maintain
So, the reactions that goes on inside a kiln are pretty intense. You need a pretty advanced degree in chemistry to understand them. But that is not true of operating or maintaining our kilns. In fact, we make both as simple and safe as possible – even with complex raw materials and fuels. No PhDs required.
When needed, we can also offer replacement parts for both KHD and third-party kilns, including seals, tires, shell sections and inlet/outlet sections. With our deep process knowledge, you can be sure that any replacement parts will be designed and manufactured to do the job in the unique process conditions at your plant.