3 replies to this topic

[saleda]

Dear All

In vacuum tray drier where we recover acetone from solid material being dried, does operation under vacuum effects the flow rate of vapors compared to same in ATM conditions.

we try to recover 28 litres over 03 hours of operation and have water ring vacuum pump with 300 m3/hr suction capacity.Can I assume 14 kg/hr flow rate of acetone vapors flowing from driers

and please validate this excel condenser design.

Regards

Saleda

 Copy of Condenser Design.xls   42.5KB   86 downloads.

[Art Montemayor]

Saleda:

I don’t understand your calculations. They should be well-explained and detailed – as well as accurate. You show that water is being condensed; yet, you are using acetone as the fluid (solvent) to be recovered. How is this happening??

I don’t believe you understand the basic Unit Operation of oven drying. You would have a better understanding if you generated at least a Process Flow Diagram and a P&ID to follow, after generating the heat and mass balance. Since you haven’t done this, it is hard for us to explain what is happening. That is why I have had to generate a PFD for you to explain what you are trying to understand and are getting confused about. Please study the revision 1 of your workbook and generate a complete heat and mass balance in accordance to the process description I have furnished.

You should not have to assume anything coming out of the oven. You should know that the exact amount of acetone that you put into the oven with the solids will exit out of the oven if the solids are heated and a partial vacuum pulled. All you have to do is execute and generate a heat and mass balance that will produce the amount of energy you are required to furnish as well as the quality and rate of coolant fluid you require to condense out the acetone in the time frame you desire.

This is the Industrial Professional Forum and I shouldn’t have to generate a PFD or a heat and material balance to demonstrate to you what you should already have produced in order to define the problem. However, I did it anyway in order to accelerate the lesson that should be learned here. I hope this helps.

Attached Files

•  Condenser Design Rev1.xls   141.5KB   44 downloads

[saleda]

Dear Art Montemayor

I feel highly obliged for the work you have done for me.

Now as per your guidance I have edited my excel sheet and have provided correct and detail data.

Would you again be kind enough to validate that design and to guide me in cracking my very 1st industrial assignment.

Regards,
Saleda.

Attached Files

•  Condenser Design Rev2.xls   146KB   18 downloads

[Art Montemayor]

Saleda:

All you have done is corrected your one spread sheet with the correct process fluid as I indicated. You have not provided detailed data:

What is it exactly that you are doing (or want to do)? You don’t supply a scope of work or a detailed heat and mass balance as I requested. You don’t explain if you are designing, or rating a condenser. You want me to validate a condenser “design” – and yet you say the condenser is 5 years old. Just WHAT is it that you are doing? Give us ALL THE DETAILED BASIC DATA AND SCOPE OF WORK. I continue to do all the engineering work on your work book, while you don’t supply all the basic data.

I am forced to have to GUESS what it is that you are doing:

• You are running an existing lab-scale operation, recovering acetone solvent with an existing condenser – and doing it poorly, with a lot of acetone losses.
• You don’t have a condenser data sheet and what’s more, you have no calculations on heat and mass balances around the system. You therefore don’t know if your condenser is the right one for the job.
• You have tried to rate the existing condenser, but you fail to tell us the basic data, Data sheet, dimensions, and characteristics of the condenser.
• You are trying to condense the acetone in the tube side of the existing condenser and this is probably what is causing a lot of your acetone losses.
• You are using a liquid ring vacuum pump but haven’t furnished a detailed schematic PFD that shows how it is installed and how you are controlling the vacuum operation.
• You haven’t furnished a detailed process description and sequence of operations, so you probably haven’t those written operational notes either.

Attached find my comments and recommendations on your Rev2 workbook. Please note all my comments in bold RED. If you follow my comments and apply them, you should have no problems in recovering 90 to 95% of the acetone in the tray dryers.

Note that I make a simple, direct tube layout for a very small and low-cost TEMA BEM condenser that has a 6” shell and is 3 meters long. You should be able to easily build such a condenser wherever it is that you are located. All the materials should be available locally and the installation should follow what I sketched in my PFD.

I can’t justify continuing to help you with all my work input based on simply guesses because you don’t furnish all the scope of work and basic data. This work should, however be enough to let you know what it is that you are doing wrong (or not doing) and allow you to succeed in recovering essentially all of the acetone solvent in your process.

Good luck.

Attached Files

•  Condenser Design Rev2(1).xls   273KB   56 downloads