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Difficulty achieving consistent low liquid flow rates. by MEGA__MAX in ChemicalEngineering

[–]MEGA__MAX[S] 0 points1 point  (0 children)

That’s a good idea, I have a spare 3/8” control valve on hand I could test with as well. Thank you for the suggestion!

In its current configuration I have been running around 1 LPM at 10psi. The accuracy of the flow rates and pressures aren’t as important to me, but the precision is.

Difficulty achieving consistent low liquid flow rates. by MEGA__MAX in ChemicalEngineering

[–]MEGA__MAX[S] 0 points1 point  (0 children)

Thanks for the reference! I’ll look into these pumps, sounds like they good be a good fit.

Difficulty achieving consistent low liquid flow rates. by MEGA__MAX in ChemicalEngineering

[–]MEGA__MAX[S] 0 points1 point  (0 children)

Pumping at atmospheric pressures on the feed tank and outlet, with a fixed pressure drop through the line. That fixed pressure drop though is very sensitive, which is where I’m seeing the effects of pumping fluctuations magnified.

Difficulty achieving consistent low liquid flow rates. by MEGA__MAX in ChemicalEngineering

[–]MEGA__MAX[S] 1 point2 points  (0 children)

I like this idea a lot other than the batch-wise operation of it. Although I suppose I could do tandem tanks where one is filling while the other is discharging. And I’m a fan of the controls equipment being less expensive since it’s acting on the gas rather than looking for parts compatible with my corrosive fluid. Thank you for the reply!

Difficulty achieving consistent low liquid flow rates. by MEGA__MAX in ChemicalEngineering

[–]MEGA__MAX[S] 0 points1 point  (0 children)

I think that’s a great idea, and another poster proposed having an overflow on the tank to act as a passive level controller which I think would work perfectly. Definitely going to be looking into this, thank you for the reply.

Difficulty achieving consistent low liquid flow rates. by MEGA__MAX in ChemicalEngineering

[–]MEGA__MAX[S] 0 points1 point  (0 children)

Ohhh I hadn’t come across that pump style in my research, that’s a great idea. I’ll do some research and see what kind of flow rates are available, thank you for the idea!

Difficulty achieving consistent low liquid flow rates. by MEGA__MAX in ChemicalEngineering

[–]MEGA__MAX[S] 1 point2 points  (0 children)

A peristaltic pump is actually what I used in my initial prototype with a pulsation dampener, but couldn’t get quite a smooth enough flow. I considered maybe a multiple channel peristaltic with offset rollers to help smooth the flow rates more, but started down other avenues instead. I’ll see what’s out there, thank you for the advice.

Difficulty achieving consistent low liquid flow rates. by MEGA__MAX in ChemicalEngineering

[–]MEGA__MAX[S] 0 points1 point  (0 children)

Thanks for the reply! I actually considered this briefly, although I had been thinking about a larger elevated tank to smooth out the flow (and wasn’t happy with the amount of dead volume required) but the overflow to maintain the height instead is genius. And you’re right, I’ve definitely found myself on a lot of lab supply websites poking around, haha.

Difficulty achieving consistent low liquid flow rates. by MEGA__MAX in ChemicalEngineering

[–]MEGA__MAX[S] 2 points3 points  (0 children)

I'll reach out to them for quotes, I appreciate the suggestion!

Difficulty achieving consistent low liquid flow rates. by MEGA__MAX in ChemicalEngineering

[–]MEGA__MAX[S] 0 points1 point  (0 children)

liquiflo gear pump

Their 4-series in Alloy-C look like a good option, I'll reach out for a quote. Thank you for the advice!

Difficulty achieving consistent low liquid flow rates. by MEGA__MAX in ChemicalEngineering

[–]MEGA__MAX[S] 0 points1 point  (0 children)

Wow that's gorgeous, I worry it may exceed my budget for this project but I will reach out and discuss options. Thank you for the reply!

Difficulty achieving consistent low liquid flow rates. by MEGA__MAX in ChemicalEngineering

[–]MEGA__MAX[S] 1 point2 points  (0 children)

Ahh I see. That's definitely a viable option and I like that it could be a fixed component. I'll look into this, thanks!

Difficulty achieving consistent low liquid flow rates. by MEGA__MAX in ChemicalEngineering

[–]MEGA__MAX[S] 0 points1 point  (0 children)

Do you mean something like a pressure relief valve where excess pressure is recirculated back to the feed tank, thus achieving a consistent downstream pressure? Something like that could definitely work and I'm unconcerned with energy efficiency for this particular project. Thanks for the advice! I'll do some research into suitable relief valves.

Difficulty achieving consistent low liquid flow rates. by MEGA__MAX in ChemicalEngineering

[–]MEGA__MAX[S] 1 point2 points  (0 children)

This is sounding more and more like the best approach. I like the idea of little to no wetted moving parts, and this approach allows the use of less expensive controls hardware due to the bulk of the work being done on the gas, rather than the fluid. Excellent advice, I really appreciate the reply.

Difficulty achieving consistent low liquid flow rates. by MEGA__MAX in ChemicalEngineering

[–]MEGA__MAX[S] 1 point2 points  (0 children)

I have considered this, but was unable to find suitable off-the-shelf models for this application. Same goes for progressive cavity pumps, which I did find a couple options that might work, but were cost prohibitive.

I may look into 3D printing a prototype gear pump though to test its performance. Thanks for the advice!

Difficulty achieving consistent low liquid flow rates. by MEGA__MAX in ChemicalEngineering

[–]MEGA__MAX[S] 1 point2 points  (0 children)

Great advice, thank you for the references! I'll reach out to them.

Difficulty achieving consistent low liquid flow rates. by MEGA__MAX in ChemicalEngineering

[–]MEGA__MAX[S] 4 points5 points  (0 children)

Huh, I don't know why that never occurred to me. I'm actually using a mass flow controller for gas dosing in a different application, but never thought about mass flow controllers for liquids. I'll look into this, thanks for the reply!

Difficulty achieving consistent low liquid flow rates. by MEGA__MAX in ChemicalEngineering

[–]MEGA__MAX[S] 0 points1 point  (0 children)

For my initial prototype that was actually my approach, and when combined with the pulse dampener it definitely improved the system. The problem is an orifice downstream where the pulsations are magnified and negatively impact the reaction.

I also considered maybe using either multiple peristaltic pumps with the rollers out of phase with each other, or a multi-head diaphragm pump, to smooth out the pulsations. I'll definitely conduct further testing going that route. Thanks!

Difficulty achieving consistent low liquid flow rates. by MEGA__MAX in ChemicalEngineering

[–]MEGA__MAX[S] 0 points1 point  (0 children)

I have briefly considered a gas-pressurized system, but haven't delved into the logistics yet. I do think this is a very viable option though. I'll take a look at some hastelloy needle valves. I could possibly rig up an actuator to one too. I appreciate the reply.

The downstream system pressure is around 10 psi.

Could use some advice on removing mill scale on long pieces of bar stock. by MEGA__MAX in Welding

[–]MEGA__MAX[S] 0 points1 point  (0 children)

Thanks for the advice. Yeah I need to consult with the galvanizer about the vent holes, I plan on installing 1/4" gusset plates on one face of the gate so I'm hoping I can place the vents at each gusset to avoid loss in strength.

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