Steam Tube Rotary Dryers and Solids Handling Capacity

Hi

There are a number ofissues that can cause drying problems. Just wondering what the product is you are drying and the size of the material going through the dryer. Also what temprature you are running the system at.

My email is andy.hall@cds-group.co.uk

Regards

Andy Hall

CDS Group

In addition Andy's comments. Is there a slight amount of air flowing co-current through the unit? This will reduce water at the surface allowing increadeddrying

We need more information to answer this. What is the material, temp of steam, direct or indirect heat, how dry does it need to be, what is the air flow, is a dust explosion a concern.....?

In order to optimize a dryer like this you need a drying curve(s) for the material you are drying. (Temperature, time and airflow against dryness or % water) Even with the same materials, the porosity and morphology of the solids that you are drying may have different properties. There are companies that will generate curves and many curves are established.

The slope and internal lifters and air/steam flow determine residence time.

Some materials require high heat quickly that cause water to vaporise and create fractures and paths for vapors to move out.

Other solids will singe, sinter or melt the surface if the initial heat is too high causing the surface to be less porous and drying more difficult.

Some dryers use lifters, slope and draft to retain wet product while the lighter dry solids are "blown" out.

One method is to use a slope to allow dry solids to flow out and backwards lifters to retain wet solids by moving them back.

Please give more details or you may get the right answer for a different application.

Thank you all for enthusiasm to help me. Here is more information.

The dryer is in-direct steam-tube rotary dryer. The dryer is slopped, wet cake is dried by the steam tube inside the dryer, the solids is transported to the outlet end by slope and dryer rotating.
The material handled is one kind of organic acid , the particle size is about 130 micron, the feed temperature is about 96 C with 10% water. The outlet temperature is 120 to 130 C. We use steam to heat up the tube. the supply steam pressure is 5.5 barg, while we control steam pressure to control solid temperature, the steam pressure to dryer is between 3.5 barg to 4.3 barg after control valve.
We use a little bit counter-current inert gas to drive steam vapor out of the dryer.

I just wondering what is the difference between dryer speed and dryer slope in terms of solid handling capacity, as we are going to do some modification to increase the dryer solid handling capacity. In other words, the solids can not be transported to outlet end from feed end at design capacity, so a lot of solids is accumulated on dryer feed end and we can not feed more due to dryer feed end screw motor over current.The dryer has enough heating capacity as I mentioned before

We had increased the final product temperature by increasing the dryer feed steam pressure and it helped 10% more capacity, but we can not do much as the down stream unit limitation.

We had increased the speed by 25% by changing the gear in the gear box, while it seems that the capacity was increased only by 10%, it made us hesitate to increase the speed further, also we can not increase the dryer speed too much due to mechanical limitation. We can increase dryer speed by another 25% which is the max we can reach, while we are not confident to do that due to the observation we had on the first change. So I am wondering if we can increase the dryer speed or increase the dryer slope, and that is why I am trying to get some help to understand the difference between dryer speed and dryer slope in terms of solid handling capacity.
Our goal is to increase the solid handling capacity by 20% to 30%.

Thanks again for your attention.