How to prevent solids build-up in a dryer?
How to prevent solids build-up in a dryer?
(OP)
Respected community members, I have one (only?) problem with my powder processing system and I hope someone will be willing to share his/her knowledge/experience. Here it is:
Experimentsl reactor is 12" ID, 3 ft long (with a cone at the end) and filter/fan downstream. Powder is fed from the top of the reactor into a flame (burner mounted on the top). Particles generated are 0.5-1 micron. After running the system for 1/2 an hour, most of the powder is deposited on the walls of the reactor instead of being conveyed. Gas velocity is enough to keep particles entrained but why they are sticking to the wall? Reactor T is 500 C, gas flow rate 350 slpm.
Would decreasing ID/length help and how much? Or injecting air along the walls (sweeping)?
Thanks
Experimentsl reactor is 12" ID, 3 ft long (with a cone at the end) and filter/fan downstream. Powder is fed from the top of the reactor into a flame (burner mounted on the top). Particles generated are 0.5-1 micron. After running the system for 1/2 an hour, most of the powder is deposited on the walls of the reactor instead of being conveyed. Gas velocity is enough to keep particles entrained but why they are sticking to the wall? Reactor T is 500 C, gas flow rate 350 slpm.
Would decreasing ID/length help and how much? Or injecting air along the walls (sweeping)?
Thanks





RE: How to prevent solids build-up in a dryer?
Is your particle water wettable or react with water?
What is the reactor made of?
How are you adding the raw material to the flame?
If you can comeback with a little more information about your process.
One possibility is that you could have to have incipient melting or wetting of the particles to cause the sticking. Flame temperature is considerably high than your stated 500°C. The skin temperature of the reactor may be higher or cooler that the stated temperature of the gas stream.
We have the essentially the same problem with polymer pellets. We went from fluidized bed type dryers to a Wyssmount Turbo Dryer or a tumbling dryer. For our highest temperature tumbling dryer we added inert pellets that can be easily separated.
RE: How to prevent solids build-up in a dryer?
Reactor is SS (not polished enogh though). One of my speculations was that the rason may be the roughness of the wall. Water is actual media (suspension) but at a such high T of the wall I don't think it affects deposition.
RE: How to prevent solids build-up in a dryer?
RE: How to prevent solids build-up in a dryer?
RE: How to prevent solids build-up in a dryer?
Would bigger chamber diameter help? I am also thinking about adding sweeping gas along the chamber wall to wash away all particles that come close to it.
RE: How to prevent solids build-up in a dryer?
You could verify this by heating the dryer up to operating T and then slowly introducing your slurry to the atomizer. Ramp the slurry fed rate up until the deposition starts to occur.
Can you raise your drying T above 500 C?
RE: How to prevent solids build-up in a dryer?
RE: How to prevent solids build-up in a dryer?
Compositepro, thanks for the tip. When discussing the issue here with my coworkers, static electricity was mentioned but we actually didn't explore it further.
RE: How to prevent solids build-up in a dryer?
m777182
RE: How to prevent solids build-up in a dryer?
RE: How to prevent solids build-up in a dryer?
Ofcourse, the coat should be non-reactive to the reactor conditions.
I also have a question.
Is the reactor being uniformly heated up or are there some regions getting more heat and some getting lesser heat ?
Is is the particle agglomeration happening uniformly throughout the length of the reactor or is it restricted to top, middle or bottom ?
RE: How to prevent solids build-up in a dryer?