Exploring the Effects of Skewed Cylinders in Rotary Kilns

In summary: Start a new thread with the following: Hi,I would like to ask if anyone can help me understand why a skewed roller bearing (shown in the attached picture) results in increased thrust force. I have seen this described as the "translating motion" between the two rollers. I am not sure if I am understanding this correctly.In summary, a skewed roller bearing creates translation movement between the two rollers, which in turn causes increased thrust force.
  • #1
Luiz Cavatte
5
0
Hi,

when two cylinders in contact, but not parallet to each other (skewed), are rotating, there is a development of forces between them which tends to push one cylinder along its rotation axis and the another one to the opposite side. In other words, there will be translation movement between them.

Could someone explain me why that happens?

This is the main mechanism to control thrust force in rotary kilns. Rotary kilns are normally supported with riding rings and support rollers on each pier. As the rotary kiln has a small slope to allowd the material fed in one side to go throught it, the thrust force due to the weight is controlled by skewing some support rollers in order to push the rotary kiln upwards and then keep it in balance.

Thank you
 
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  • #2
Start with the simple case when the rollers are crossed at right angles. In that case, it's obvious that if one roller turns, it tries to push the other one along its length.

When the rollers are at an arbitrary angle, the rotation of one roller can be resolved into components "parallel" and "perpendicular" to the other roller. If the rollers are nearly parallel, the "perpendicular" component is small, but it gives the same effect as if the rollers were crossed at right angles.
 
  • #3
Hi,

thanks for your explanation!
I attached a picture of a rotary kiln. You can see the kiln shell, the riding ring and a support roller. I put arrows to indicate the riding ring and roller rotation direction. The arrows on the bolts of the roller bearing housing shows one example of how the roller can be skewed. Here the upper bearing is pushed "out" and the lower bearing is pushed "in".

Could you explain how the forces develop in this example?

Many papers say that when the rollers are perfect parallel to the riding ring, there is pure rolling motion but, on the other hand, when the roller is skewed, actually sliding also occur in the ring/roller contact.

Could you explain that?

Thank you
 

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  • #4
Guys, this is a duplicate thread, which is agains PF guidelines. The matter is already being addressed in the first one. These should be consolidated into one.
 

1. What is a rotary kiln and how is it used in industrial processes?

A rotary kiln is a large cylindrical vessel used in a variety of industrial processes, such as cement production, waste incineration, and chemical reactions. It is typically made of steel and rotates on its axis to evenly distribute heat and materials inside. The high temperatures and controlled environment within the kiln allow for efficient and precise processing of materials.

2. How does the shape of a cylinder affect the performance of a rotary kiln?

The shape of a cylinder in a rotary kiln can greatly affect its performance. A skewed cylinder, where one end is wider than the other, can cause uneven distribution of materials and heat, resulting in inefficient processing and potentially damaging the kiln's components. It can also lead to increased energy consumption and reduced product quality.

3. What are the potential benefits of using a skewed cylinder in a rotary kiln?

While a skewed cylinder may have negative effects on a rotary kiln's performance, it can also provide some benefits. For example, a skewed cylinder can increase the residence time of materials inside the kiln, allowing for more thorough processing. It can also create a more turbulent flow, leading to better mixing and more uniform heating.

4. How do scientists study the effects of skewed cylinders in rotary kilns?

Scientists use a combination of experimental and computational methods to study the effects of skewed cylinders in rotary kilns. This may involve building physical models of the kiln and conducting experiments under controlled conditions, as well as using computer simulations to model the flow and heat transfer within the kiln.

5. What are some potential future research directions for exploring the effects of skewed cylinders in rotary kilns?

There are a number of potential future research directions for studying the effects of skewed cylinders in rotary kilns. This may include investigating different materials and geometries for the cylinder, as well as developing new techniques for optimizing the performance of skewed rotary kilns. Additionally, research may focus on the environmental impacts of using skewed cylinders, such as energy efficiency and emissions reduction.

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