Pump for circulating hot Limonene liquid
Pump for circulating hot Limonene liquid
(OP)
I need to find a pump that will circulate hot Limonene to create flow within a heated vessel. The Limonene will be at 80C and in a vessel that has been pumped down to 1 psia. It will be just under it's boiling point (VP at 80C is just over 1 psi. Properties of Limonene are; Sg .84, 0.9 Cp (at 25C, don't know at higher temp). Will be drawing from bottom of vessel and putting back in at 8" higher. Flow should be in the order of 5 gpm. Stainless Steel and Viton are good compatible materials. Any suggestions or education would be appreciated.





RE: Pump for circulating hot Limonene liquid
Maybe a air operated diaphragm pump, running very slowly with a large diameter intake.
If you pull any suction the solution will boil.
= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube
RE: Pump for circulating hot Limonene liquid
AND is protected from limonene vapor by construction materials, cold trap, filters, etc.,
AND if the limonene will not be degraded by a modest flow of air through it,
you could try a sparge pump.
I.e., insert a stainless tube through a gland in the tank top, extending to nearly the bottom of the tank.
Leave the top of the tube open, or restrict it with a needle valve, etc. to control the flow of air into the tank.
The rising bubbles will circulate the liquid.
To make it more effective, surround the tube with an inverted funnel, small end up, which localizes the upward flow, and will more effectively stir the tank.
To make it still more effective, fit the bottom of the tube with a showerhead/ garden sprinkler/ perforated plate, pointing up, so that a cloud of tiny bubbles rises instead of an irregular burp of air from the bare tube end. (I use pneumatic mufflers for this, but they're commonly made of polyethylene, which may not be happy at 80C.)
No moving parts other than the air.
One new penetration.
Mike Halloran
Pembroke Pines, FL, USA
RE: Pump for circulating hot Limonene liquid
I can place the pump as far as about 2 ft below the vessel bottom. I guess that will get me a little static head for the pump inlet. I don't have air available for an air-diaphragm pump, but maybe slow motor driven diaphragm? How about an oversized vane pump run at a low speed?
Sparge is a good suggestion but pumping air thru the Limonene is not good for this as I believe it's oxidization creates unwanted compounds. Could use N2 but that is not readily available either.
maybe I should look into some kind of mechanical stirrer (shaft thru a seal in the tank cover?
RE: Pump for circulating hot Limonene liquid
Keith Cress
kcress - http://www.flaminsystems.com
RE: Pump for circulating hot Limonene liquid
A piece of somewhat counterintuitive advice about a centrifugal pump if you choose to go that route: choose one with a full-sized impeller. The largest impeller size for a particular volute gives the minimum NPSHR. So what you're looking for will be a sub-ANSI centrifugal pump suitable for that low flow (5gpm), operating at low speed- you don't need much differential head, so that won't punish you much. Pumps made by people like Magnatex, March etc. come to mind. Under vacuum, you'd want a magdrive in my opinion, not a single mech seal.
An air diaphragm pump won't be damaged by the boiling which occurs in the pump suction- it will suffer from a capacity loss though. Unfortunately you can't really modulate the rate at which an air diaphragm pump's suction stroke takes place- you can only really change the stroke frequency. They're not a good choice for systems already operating under vacuum anyway. A slow moving motor-driven diaphragm pump might be a better option.
A mixer won't suffer from those problems and is likely what you really want.
A sparger isn't a practical option in a vessel under vacuum containing a boiling fluid.
RE: Pump for circulating hot Limonene liquid
A mixer or propeller is off the table at this time.
Also, there is no air available for an air diaphragm pump.
Good news is the process vacuum requirement is much reduced - now we will probably run the vessel at around 300 mmHg. Also, the flow requirement might be as low as 2 gpm. So I think I should be able to use a slow speed centrifugal pump. (BTW - my liquid operating level is only 10 inches, so my total head from the surface to the pump inlet is no more than 32 inches.)
I have thought mag drive would be good also, but my inquiry to Iwaki (who I have used in the past for other apps)led to them not recommending their mag drive pump (at least the small ones) in a sub-atm pressure due to the balance of pressure on the pump impeller being forced the wrong way (in a direction that did not have a bearing surface. Do you know if this is true for other manufactures of small mag drive? Or maybe with 2 gpm I should just fins a slow moving electric driven diaphragm.
RE: Pump for circulating hot Limonene liquid
A motor driven diaphragm such as a Hydracell is another option as long as you have compatible elastomer materials and operate it slow enough. They can only handle limited temperature but I think you'd be OK there.
RE: Pump for circulating hot Limonene liquid
RE: Pump for circulating hot Limonene liquid
RE: Pump for circulating hot Limonene liquid
(Edit: Removed all those awful blank lines, where'd they come from?!)
RE: Pump for circulating hot Limonene liquid
RE: Pump for circulating hot Limonene liquid
RE: Pump for circulating hot Limonene liquid
RE: Pump for circulating hot Limonene liquid
If that is the reason, I will say that I have been able to use peristaltic pumps in vacuum conditions but I will admit that the inlet tubing submersion to maximize static head is is very critical and not at all forgiving.
RE: Pump for circulating hot Limonene liquid
Can you use a peristaltic as a crude vacuum pump at low temperature with nonhazardous fluids? Sure- you can also use them to pump mixtures of gas and liquid etc.
RE: Pump for circulating hot Limonene liquid
AND the limonene doesn't decompose when boiling,
a percolator pump could work ok.
Comprising, e.g.:
- a heater raising the temperature of a small area on the bottom
- a shallow cup, covering the heated area of the tank shell
- a standpipe joined to the cup, and extending upward a bit,
- cup and standpipe loosely constrained so they can rise together, but not translate laterally
... in operation, the limonene within the cup will star to boil,
a vapor bubble will appear and lift the cup and standpipe,
then 'burp' out of the standpipe,
and the cup will refill with less hot limonene as it falls.
Mike Halloran
Pembroke Pines, FL, USA
RE: Pump for circulating hot Limonene liquid
Do you have pure nitrogen available? Use an eductor and N to make a jet pump to stir with.
= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube
RE: Pump for circulating hot Limonene liquid
RE: Pump for circulating hot Limonene liquid
Keith Cress
kcress - http://www.flaminsystems.com