Dehumidification/Product Moisture Load

[Fox99]

Looking for some help in regards to "product moisture load" in LBS/HR of moisture removal to size dehumidification equipment properly. We have pharmacuetical softgel capsules of 500mg each, of which we need to remove about 10% moisture from this product. This issue is that this 10 % water content removal is being done slowly over a 36 hour process in a drying room that recives 129 lbs. of this product each hour. (Thats 117,000 capsules produced each hour X 500mg each capsule converted to LBS, which gives us our 129LBS of product each hour).
The moisture load that we calculated from this info above is 12.9Lbs/hr "product moisture load in lbs/hr". (10% of our original 129lbs).If this sounds correct please let me know?

If so, how would we calculate the 12.9lbs/hour over the 36 hour drying process? Multiply 12.9Lbs/hr X 36 hours and just take the 10% of that number to be our "moisture load content" for the drying room?

We are not concerned with any other loads at this time, such as room loads, etc.
Just our product load.

Any help would be greatly appreciated.

 

[Drazen]

you should be careful - are you removing 10% per overall product weight, or 10% of water content in product? this apparently makes large difference.

as your product stays for 36 hours you cannot calculate only new 129 lbs received.

i believe load should be (quantity removed per product)/36x(existing stock)

you should take other realistic load into account (door opening, people), at least to see how much to add to capacity.

another issue is how did you get to data that 10% is removed within 36 hours? it sounds to me as manufacturers spec which says "10% will be removed in 36 hours if space dry bulb temp is x and relative humidity is y", so you likely need capacity which will maintain such conditions against outdoor conditions.

 

[317069]

What is your goal of this, is it to keep the room RH within certain limits.

 

[Fox99]

We are removing 10% of water content in product, not 10% of overall product weight.

So you believe it should be (quantity removed per product, per product meaning 129lbs of product each hour / 36 hours X existing product load)?

Now would my existing product load be basically the 129lbs hour of product we are producing X 36 hours, giving us a product load of 4644lbs of product sitting in drying room. Every hour we are removing 129lbs of product from room and also adding a new batch of 129lbs every hour. So we have a constant of 4644lbs always in drying room.

The 10% moisture removal should be met over a 36 hour process if we maintain 68F dry bulb and 20RH conditions in the drying room environment.

We need to be at 68F 20RH 20grains/lb.
We are using a liquid dessicant system, but are having an issue with what size to use based on not accuratley being able to determine exact product load.

Again, I appreciate the input. Thank you.

 

[Fox99]

Our goal is to be at 68F dry bulb and 20RH.

That is achievable with a liquid dessicant system, but the product load really determines what size system to use. So we are really trying to be as accurate as possible with the product load and moisture of lbs/hr removal. We do not want to make a mistake on our calculations and size the system to small.

 

[Drazen]

are you not contradicting yourself or it is me who did not read carefully enough (neither i would in current squeeze)?

if you are removing 10% of water content, than you need to find quantity of water content in product, not use that 129 lbs of overall product weight.

next, as mentioned in my previous formula, the fact is that all products lay for 36 hours, so they make load, and 129 that are coming in within one hour are possibly balances with 129 coming out each hour; even if it is not, again your maximum storage content makes load, not only hourly input, putting hourly input into equation would make sense only if drying process lasts one hour, but if it lasts 36 hours, all existing product which lay in storage less than 36 hours make load.

 

[Compositepro]

For your purposes, the 36 hour residence time is irrelevant. All that is important is that you need to remove 12.9 lbs. of water per hour. I think a refrigerant based system would be far more economical and reliable.

 

[MintJulep]

As Drazen has already correctly pointed out, you most likely want to remove 10% of the original water mass. Not 10% of the total mass. These will not be the same, unless your product is water.

If you are removing mass in the drying room then product mass flow rate in will not equal product mass flow rate out.

Is 500mg the entering mass, or the leaving mass?

Is 500mg even the actual mass of the capsule? Most medical capsules are named for the mass of the important ingredient. But there are many fillers, the capsule casing, etc.

 

[Fox99]

The total mass per capsule is about 2800mg.
But we are only removing water content from the shell of the capsule. The shell weighs about 500mg. Of which we need to remove 10% of that moisture content from the shell.

 

[Compositepro]

Fox, I assumed your meaning, but it is remarkable how ambiguous your "clarifications" are. 90% of solving a problem is defining it completely. I assume you mean 10% of the cover mass because that is the only data that you've given that allows the problem to be solved. But, you contradict this by saying 10% of moisture content.

 

[Fox99]

Compositepro,
The 500mg shell is holding water content. We only need ro remove 10% of the water content from the shell. Just the content of the shell.
Do i need to calculate in the other fill material inside the shell, the 2800mg - 500mg = 2300mg. I dont believe i need to calculate in the other 2300mg into the equation. Or do I?

Just base my product load on the 500mg.

If my product load is 129lbs of product pet hour @ 10% moisture removal. Is it safe to say that my LBS/hr water removal is 12.9 LBS/hr?

 

[MintJulep]

The 500mg shell is holding water content. We only need to remove 10% of the water content from the shell.

So how many mg of water do you think you need to remove from each shell?

(hint: The answer is not 50 mg.)

 

[317069]

How will you remove moister or water from the shell, can you explain?

 

[Fox99]

317069,
We are attempting to remove the moisture through a liquid dessicant HVAC system.

 

[MintJulep]

Fox99,

The level of engineering assistance that you need appears to be more than is reasonable to obtain through an internet tips forum.

You should take advantage of whatever engineering capabilities the supplier of the desiccant system offers.

 

[317069]

How will you make sure that you are removing exactly 10% (not 9.5% or 10.5%) of moisture from your product by the HVAC

 

[Fox99]

We are able to check capsule moisture levels throughout the process. At specific times with moisture analyzing equipment of which we are able to base our drying times on.

 

[317069]

if you are able to do that, then why you are not able to know your moisture load.