Ideas for dissolving salt through pressure vessel inlet

[ekraft4]

We are designing a pressure vessel that will hold salt water. Distilled water will be entering the vessel through a transfer line supplied by a facility. We are brainstorming ideas on how to dissolve the salt at a fast time. The existing design had a nozzle at the top of the vessel to dump the salt in. Then a pump would mix the salt within a recirculating loop. This caused a lot of damage to the pump. We also can't use any means of agitation. Any ideas on how to mix the salt with the water? We are thinking of slowly dumping the salt within the water transfer line that ends with an educator within the vessel. Any ideas are appreciated. Thank you!

 

[SandCounter]

Heat the water to dissolve salt faster. Crush the salt into smaller particles to increase the surface area.

I used to count sand. Now I don't count at all.

 

[ConstantEffort]

There are pumps made to handle solids if you're looking for a quick improvement without other changes.

Otherwise, do you have a batch or continuous process?

Does the pump return the water to the bottom of your vessel to agitate any salt that has settled to the bottom?

Can you use static mixers in the piping of the recirc loop?

 

[zdas04]

Are you dumping dry salt directly into the vessel? Any way to fill the salt hopper with water to create a slurry that you could pump into your salt-water vessel with a jet pump? More details on your process will almost always lead to better answers.

[bold]David Simpson, PE[/bold]
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

 

[ekraft4]

Thank you for the replies! The existing system dumps salt directly into the vessel from the top. The pump/recirculation loop is the only mixing technique. The problem is that it takes them 8+ hours to fully dissolve the salt in the 150 gallon vessel. Our goal is to drastically decrease the dissolve time. We cannot introduce heat into the system. We have looked in to static mixers in recirculation loop, but we are trying to minimize how much we have to use the recirculation loop. We would like to come up with an idea on how to enhance the mixing process on the inlet line to the vessel. We'll look in to adding these static mixers there. We also thought of fining the salt through a sifter that enters directly in to the water transfer line (pressure vessel inlet) to help create the slurry that you mentioned zdas04. They also told us we can't use any agitation, such as an impellor inside the vessel. I understand the options are limited, but I do appreciate your help!

 

[bimr]

We are designing a pressure vessel that will hold salt water. Distilled water will be entering the vessel through a transfer line supplied by a facility. We are brainstorming ideas on how to dissolve the salt at a fast time. The existing design had a nozzle at the top of the vessel to dump the salt in. Then a pump would mix the salt within a recirculating loop. This caused a lot of damage to the pump. We also can't use any means of agitation. Any ideas on how to mix the salt with the water? We are thinking of slowly dumping the salt within the water transfer line that ends with an educator within the vessel. Any ideas are appreciated. Thank you!

C'mon man. People are not mind readers here. What is the salt and the consistency? What fluid is the salt dissolving into? What salt concentration do you want to achieve?

If you are just dissolving sodium chloride into water, there are plenty of brinemakers on the market.

Brinemaker brochure

Brine Tank

 

[ekraft4]

Bimr, I'm not asking people to be mind readers. The salt concentration is irrelevant. I'm just asking for mixing technique ideas that I may be unaware of that would help mix salt with distilled water. Zdas04 mentioned static mixing in the inlet pipe, and SandCounter mentioned fining the salt to increase surface area. These are excellent ideas and the type of ideas I'm looking for. We can't use COTS mixing tanks. I wish we could, as that would solve the problem immediately.

 

[Compositepro]

Salt is dissolved in water for regenerating water softener tanks. They simply use a open top plastic tank with a lid that is completely full of coarse salt or salt briquettes. Water is added at the top of the tank to keep the level constant and saturated salt water is drawn out of the bottom of the tank. Salt water is denser than water so there is almost no mixing occurring. The salt concentration just increases as the water flows down through the salt bed. You cannot get more efficient than that. This is what is shown in BIMR's second link.

Are there additional process requirements that you have not told us about?

 

[EdStainless]

Put the salt hopper in the recirc loop, fill it with salt and seal the lid. The use the recirc pump to force water through the salt bed and back into the tank.
Use the finest salt that you can handle.
There is no water in the brine tank for my water softener. Every time it cycles it puts the correct amount of water into the salt, waits 2 hours, and then sucks it all out during regen.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[bimr]

The rate of dissolving salt depends on what salt you are trying to dissolve. Don't know how you expect someone to come up with a solution to your problem when you do not fully describe what you are trying to do. Otherwise, it is just a bar game of twenty questions.

Sodium chloride will reach saturation at 26% solution. For that reason, many users will use brinemakers. Brinemakers have a gravel bottom so that the excess salt solids above 26% solution are retained in the brining tank.

A 3' diameter brining tank will make up approximately 3.5 gallons per minute of brine. That would fill your tank in 150 gallon tank in about 40 minutes.

 

[georgeverghese]

Refined salt, which is mostly NaCl will dissolve a lot quicker than unrefined sea salt, which contains MgCl2, bromides etc.

If this is a vertical vessel, add a hold down grating with a rigid metallic retaining gauze at the bottom, load in some small size inert ceramic balls to a depth of say 3-6inches (you could ask a column packing vendor like Norton for these) below the salt bed. That should stop the salt from carrying under into the pump suction.