Homogeneous mixing of two different liquids

[supersonics29]

Guys,
I hope you guys are keeping well.


I have been working on developing an Inline Dispensing Station for my CNC Machine & Parts Washer where coolant is mixed with water in different concentrations & volumes as per the requirement which will vary on a day-to-day basis.


In the inline mixer & dispenser, how do you mix 500ml of Coolant in 49.5 Liter water to get a homogeneous mixture?


Both liquids need to be mixed in-line (in pipes) without using an additional tank & agitator. Venturi is not an option either. Water is supplied under gravity & coolant is pumped from a drum/tank.



I am using this as reference - https://tinyurl.com/y7ynh9qd


(Skip to 4:10 in the video).

From the video of the AF4 unit, we see that for mixing 1gal at 1%, they start the coolant pump & water flow together and then shut off the coolant pump after the 0.01 gallon has flown through, but for the remainder of the water to flow through takes a little longer. How does this mean the water & coolant are mixed uniformly?


Any help will be appreciated.
Thanks,
KV

[aslietz]

Afternoon KV,

Based on the limited requirements you describe this is how I would design the system.

I would use a pair of flow regulators to introduce the two liquids together at the correct ratio in-line. In your example I would run the coolant at (0.5)Liter/UnitTime and the water at (49.5)Liter/UnitTime. As long as the two liquids are being dispensed over the same UnitTime you wont need an additional reservoir.

I would then run the two liquids through a shear mixer. These are common in LSR(Liquid Silicone Rubber) injection molding for homogenizing colorant and multipart liquid silicone prior to the injection barrel.

Here is just the first link I pulled up for shear mixers online just so you have some reference.
https://tinyurl.com/y9dsnxtq

From there the system can be coupled to whatever you need downstream. Best of luck!

[supersonics29]

Afternoon KV,

Based on the limited requirements you describe this is how I would design the system.

I would use a pair of flow regulators to introduce the two liquids together at the correct ratio in-line. In your example I would run the coolant at (0.5)Liter/UnitTime and the water at (49.5)Liter/UnitTime. As long as the two liquids are being dispensed over the same UnitTime you wont need an additional reservoir.

I would then run the two liquids through a shear mixer. These are common in LSR(Liquid Silicone Rubber) injection molding for homogenizing colorant and multipart liquid silicone prior to the injection barrel.

Here is just the first link I pulled up for shear mixers online just so you have some reference.
https://tinyurl.com/y9dsnxtq

From there the system can be coupled to whatever you need downstream. Best of luck!

Thanks for the prompt response. Yes a static mixer is what we are going to use to mix the two liquids. But my question was mostly based on how to introduce the two liquids together since their volumes are so vastly different (1% coolant to 99% water).

Request you to answer these questions :-

1. Which flow regulators are you referring to?
2. Since water will be fed under gravity & coolant via pump and these two lines will converge into the static mixer, will the pressure difference in the two flows cause a problem?
3. I have been suggested to use a VFD controlled dosing pump for the coolant, but they are way too expensive for my budget. So I am wondering if there's an easier and slightly less expensive way of achieving this.

I am okay with an accuracy of about +-0.5%.

[aslietz]

1. Which flow regulators are you referring to?

- Any valve that's compatible with your liquid of choice and accuracy will be okay. McMaster Carr has a large selection you can browse.
https://www.mcmaster.com/flow-contro...stment-valves/

2. Since water will be fed under gravity & coolant via pump and these two lines will converge into the static mixer, will the pressure difference in the two flows cause a problem?

-In a sterile mathematic world you want the pressure to be exactly the same. In the real world if your coolant has higher pressure than the water and your confident your injecting it at the appropriate ratio you'll be fine. The amount of water that you would be displacing back into the tank will be small enough that you wont care.

3. I have been suggested to use a VFD controlled dosing pump for the coolant, but they are way too expensive for my budget. So I am wondering if there's an easier and slightly less expensive way of achieving this.

- The "dosing" will be taken care of by the flow valves, you just need to supply pressure upstream of the valves. If you want to go real cheap try a sump.

Best of luck!

[supersonics29]

1. Which flow regulators are you referring to?

- Any valve that's compatible with your liquid of choice and accuracy will be okay. McMaster Carr has a large selection you can browse.
https://www.mcmaster.com/flow-contro...stment-valves/

2. Since water will be fed under gravity & coolant via pump and these two lines will converge into the static mixer, will the pressure difference in the two flows cause a problem?

-In a sterile mathematic world you want the pressure to be exactly the same. In the real world if your coolant has higher pressure than the water and your confident your injecting it at the appropriate ratio you'll be fine. The amount of water that you would be displacing back into the tank will be small enough that you wont care.

3. I have been suggested to use a VFD controlled dosing pump for the coolant, but they are way too expensive for my budget. So I am wondering if there's an easier and slightly less expensive way of achieving this.

- The "dosing" will be taken care of by the flow valves, you just need to supply pressure upstream of the valves. If you want to go real cheap try a sump.

Best of luck!

These Mcmaster-Carr valves are manual. it is practically not possible to change the flow-rate each time as the concentration & volume of top-up liquid will vary. Although I have considered such Proportional control valves, but these are too costly. Burkert & Asco have such valves. Isn't it better to go for normal Solenoid Valves with Flow meters and turn the valves off as soon as the desired flow-rate is achieved?

[aslietz]

These Mcmaster-Carr valves are manual. it is practically not possible to change the flow-rate each time as the concentration & volume of top-up liquid will vary. Although I have considered such Proportional control valves, but these are too costly. Burkert & Asco have such valves. Isn't it better to go for normal Solenoid Valves with Flow meters and turn the valves off as soon as the desired flow-rate is achieved?

As long as the dispensed fluids go into some sort of reservoir to dilute with each other this will work. You wouldn't need the inline mixer either with this setup.