Clarification on pneumatic conveying formulas

I was hoping someone here could help clarify some things that are used in calculating pressure drop for pneumatic conveying.

With regards to the formula on dispersed solids density, a book I have read (cannot remember which one as of now) formally defines it as (weight of solids in test section/volume of test section). Another book (also cannot remember which as of now) seems to imply that the formula is (mass of solids in test section/volume of test section). My question is which one is correct?

Another question is about Hinkle's relation that is used to find superficial gas velocity. Is it used only for dilute phase flow?

Would appreciate any help you could offer with these questions.

 

[abeltio]

Regarding your 1st question, do not know the specifics... but from your posting seems that one author uses weight and the other uses mass.

W = M*g (W = weight, M= mass, g= acceleration of gravity)

SI units:
[W]= Newtons = kg*(m/s^2)
[M]= kilogram = kg
[g]= m/s^2

The so called "engineering" or "technical" system uses:
Force Kg (kgf) which on Earth is the weight of a mass of 1 kg.

The Std or customary system is very confusing (lbm, lbf, poundal) and all that jazz.

Regarding your question #2... don't have the foggiest idea.
HTH
Saludos.
a.

 

Thanks for the help. I know that one author was using mg and the other one was using m. Only thing is that I don't know which one is correct. It is quite important because using mg will increase the pressure drop calculations by a factor of 9.81 (acceleration due to gravity) which is quite a bit.

Other equation is from a classical thesis done by Hinkle in 1953 (yes, it's that old). A bit difficult to write it out here. I can't obtain the thesis so I don't really know the conditions under which he obtained the formula.

Thanks for the help!

 

[abeltio]

if you use consistent units it should be evident which one the author meant.
e.g. when using SI the pressure drop will be in N/m^2 or Pascal, when using the engineering system pressure drop will be in kgf/m^2 or kgf/cm^2
HTH
Saludos.
a.

 

[arkhan]

Dear LeeBK

I would appreciate if you could guide me on calculating the pressure drop across a pneumatic conveying line.

Thanks

arkhan

 

[KSEngineering]

Hello !

The calculation of pressure drop in pneumatic conveying lines is not so complicated for dilute phase conveying:

there are 4 main contributors:
-acceleration of solids (and fluid)
-friction along horizontal and vertical pipes
-bends
-vertical height

If you need more details about the formulas please let me know.
regards
Klaus Schneider

 

[KSEngineering]

For more information please read this interesting article online:

http://www.erpt.org/014Q/rhoe-00.htm

regards
Klaus Schneider