Re: Concrete Vs Carbon Steel Silo Wall
dear Mr Mall
Indeed, in my work, sometimes I encounter cement lumps.
The first place is in the ships and barges, due to leaking hatch covers or ballast tanks.
Inside the silos, lumps can also be formed by leakages, where rain is entering the silo.
Other phenomena are, in my opinion, rather unlikely to form lumps in cement.
Chemical changes, as dehydration of gypsum release water, should be evenly rpread over the total content, unless there are areas of higher local concentration.
A lump is not an evenly spread occurrence.
as for condensation, one has to determine the available amount of water first (vapor and condensated water)
That determines the maximum of cement that can be bonded. (The evenly spread requirement is still valid)
Only breathing on top of a silo-content can accumulate water over time.
How much can be estimated with the attached spreadsheet calculation.
If this condensated water is dropping at one place or around the circumference of the silo (specially a steel silo, because of the high heat conductivity), lumps could be being built up.
In your case, where ythe inside silo is 80-90 degr Cel and the outside is 29-30 degr Cel, condensation would already start at an internal RH=2%
(See attached calculation)
Is the silo air that dry and how many times is it replaced with (may be wetter) air?
Use the attached RH calculation spreadsheet to verify your situation and let us know your findings.
(This file is an update from the thread "Water condensation in convey air" in the group "Pneumatic conveying"
Good luck
Attachments
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Teus
Re: Concrete Vs Carbon Steel Silo Wall
U did not say if the lumps were in the steel or concrete silo?
The main causes of this are...
Water ingress into the silo eg leaks thru cracks or poor seals in hatches > the lumps will be near the source....and in one area
Gypsum dehydration - do U have a cement cooler > must for most applications. WHat type of gypsum (semi/demi hydrate ?? etc etc ) are U using > talk to your lab/process people about the process side and de hydrations...
These will be the main causes
Cheers
James ■
Re: Concrete Vs Carbon Steel Silo Wall
actually both silo will form the lump besides the wall the matter slow or fast.
if leaking we already did the testing on the silo wall and the result shows ok....
we use natural gypsum, CaSO4.2H2O......
talk about cooler, few years back we discuss to install cooler before cement entering the silo but when we ask supplier is the cooler really works to eliminate lump problem, they just say dont know so the project is KIV by management.
do you have experience in the cooler operation, type pls share...
tq ■
Re: Concrete Vs Carbon Steel Silo Wall
Dear Mr Mall
I do not pretend to be an chemical expert, far from that, but may be this could be a theory.
If the natural gypsum is dehydrating and the water is released as vapor in the air above the silo content.
After that this vapor is condensated against the silo wall (and roof), the lumps can form there.
(High temperature is fuelling this dehydration ???)
May be you should set up a multi discipline team to combine, evaluate and estimate the various ideas and options.
the condenstaion calculation spreadsheet should be of help to you
success ■
Teus
Concrete vs carbon steel silo wall
hi
we are having lump forming at internal wall of the silo so we have to clean it after sometimes. now we have both steel and concrete cement silo.
some say the formation of lump inside silo wall is due to the dehydration of gypsum-release water & other opinion say condensation due to temperature different inside and outside of the silo.
air temp outside silo=29-32 deg Cel
air temp inside silo = 80-90 deg Cel (during grinding)
input from you guys how to solve the lumpy formation inside the silo.
tq ■