[BABAR]

Hi
I m facing this problem
*vertical reactor,10 ft height,3 inch dia
*from upper side powder is falling at rate of 7 kg/hr
*a gas is also entering from upper side which react with powder to give product
*there is a stirror which disperse powder and mix in gas phase
what should be proper design inside to increase stay time of powder
Tap density of powder is 1.2

waiting
Babar

[eugenedakin]

Hi BABAR,

I am quite fluent on reactor design, but will need some more information.

Could you tell me the current problem? I am guessing that the powder reacts with the gas to form a solid.  My guess is that this is micronize particles. Why do you want extra stay time (purpose)?  What are you trying to make?

Thanks for your help.

Sincerely,

Eugene

[BABAR]

Dear Sir
my problems are as follows
INFORMATIONS
1-GAS REACTS POWDER AND FORMS ANOTHER GAS
2-FLOW OF GAS AND POWDER IS CO-CURRENT
3-A STIRROR SHAFT DISPERSE POWDER,MAKES A CLOUD OF POWDER TO MAKE GOOD REACTION WITH GAS
PROBLEMS
1-SOME TIMES,FEED SCREW FAILS TO MAKE THE POWDER FLOW
2-SOME TIMES,POWDER FALLS INTO RECTOR AND IMMEDIATLY REACHES AT BOTTOM OF REACTOR i.e.MINIMUM STAY TIME IN THE REACTOR
3-HOW CAN WE IMPROVE STAY TIME
BABAR

[tripton]

Hi, here are some ideas and comments :

Problem 1 - I don´t understand why the screw fail. Something is clogged?

Problem 2 - Is very important to know the consistence of the solid. I guest it is dry powder and the particles doesn´t paste between them.
Suggestion A - Install some metalic plates in the tower. Probably you can use solid plates (wihout holes) and install them with a slope. The plates shape would be similar than the plates used in distillation towers.
Suggestion B - Change the feeding devices. Probably if you divide the solid in several feeds and increase the feeding speed using smaller inyectors, you will get a better mix with the gas. You might also modify the gas inyectors and inyect some gas protions at diferent points of the reactor (after the stirrer).

Problem 3 - I don´t know the limitations of your process, but perhaps if you increase the temperature you will get a faster reaction. You can do it pre-heating the gas.
Why do you use co-current? Perhaps counter-current flow improve the residence time.