| Q. |
Why is vacuum necessary or desirable? |
| A. |
Probably a better question is WHEN. The answer
is that the vacuum drying process eliminates 95-99% of air emission losses from either
idling OR working mode. Therefore, anytime emission losses are undesirable or illegal,
vacuum drying is an excellent choice. |
| Q. |
When would cryogenic capture be a
better choice (or not) ? |
| A. |
Usually, the choice has to do with economics.
The more expensive the solvent the more likely cryogenic capture is desirable. This is
because what you capture is returned to the system unaltered. Less expensive solvents
i.e., TCE, PCE, don't represent the investment and would not have the payback. |
| Q. |
Isn't liquid nitrogen expensive? |
| A. |
Probably the cheapest liquefied gas you can
buy. Certainly volume counts, and if you are using LN2 somewhere else in your operation it
will reduce your cost. |
| Q. |
But adsorb/desorb carbon systems are
available. Why not use them? |
| A. |
Again, we are dealing with small vessel
systems. Automatic carbon systems are expensive and justifiable only with large vessel
systems. |
| Q. |
I understand that vacuum pumps are
unreliable and high maintenance. True? |
| A. |
That depends. There are many type of vacuum pumps.
We use one or a combination of three different types. The first type is a multistage
ceramic claw dry pump. It is powerful, uses no oil and requires very little maintenance.
A major drawback is that it is expensive compared to the other pump technologies. We use
this style in larger vessel sizes and where fast cycle times are required. Our second type
of pump is a diaphragm pump. This is also a dry pump requiring no oil. It is much less
expensive. A drawback is that it is slower and cannot pull as high a vacuum. We use this
style in smaller systems, slower systems. The third and least used pump is an oil pump.
This pump has excellent vacuum characteristics and is much less expensive than a ceramic
claw pump. The major drawback is that it is an oil pump and must be maintained regularly.
Companies that are used to this type of pump have no problem maintaining it. |
| Q. |
What kind of vacuum can
you achieve? |
| A. |
We have the ability to reach vacuums of 35
millitorr. Is that necessary? Probably not. The point is, we can achieve any vacuum level
necessary to do the job. |
| Q. |
What about overall
maintenance? Isn't this a complicated machine? |
| A. |
While it is true that there is a lot going on
during a cleaning cycle, superior design and proper component selection has either
eliminated frequent maintenance or make it simple to perform. As an example we use genuine
vacuum components for valving and piping. Although these components are expensive,
maintenance on valves and piping can be done in minutes and without tools. |
| Q. |
With all the expensive components,
isn't the "Freedom Series" expensive? |
| A. |
Our saving grace is that our design is free
from complex system and subsystem design. This saves us a great deal of floor space and
cost. Bottom line, we are extremely competitive. |
| Q. |
What about the use of condensers for
solvent distillation and condensation? |
| A. |
We use water cooled condensers for
distillation condensation of higher boiling point solvents. We use onboard refrigerated
condensation for distillation of lower boiling point solvents. We also use refrigerated
condensation for condensation of vapors being evacuated out of larger vessels by vacuum.
This lessens the load on the cryogenic trap or a carbon recovery system. |
| Q. |
Isn't refrigerated condensing good
enough without the use of cryogenics? |
| A. |
Maybe good enough for many. Cryogenics at
approximately -300F captures condensable solvent vapor and non condensable solvent
molecules such as the type being emitted from non boiling solvent. The point is that a
cryogenic trap is much more efficient because of the extreme low temperature used. |
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