Suggestion Sought on Liquid Ring Vacuum Pump/Compressor

Looks okay. The only problem I could see is if the vacuum goes down to the point that the liquid will start to boil. Maybe for moderate vacuums only.

The conventional liquid ring vacuum pump also experiences the similar process of liquid getting boiled at low suction pressure. Yes, low suction pressure or with a low 'liquid boiling point' does have lesser efficiency. Using as compressor should not have any problems.

As an example, a 1500 CFM compressor will fit into a 6ft cube, require a 100 hp motor, and it can accept slugs of liquid and solids without skipping a beat, in paper making applications. They are often installed without inlet separators. 1500CFM is a kind of small vacuum pump for a paper machine.

To move 1500 CFM of gas, we would need to move 7.481 gallons of water x 1500 Cubic feet = 11,221 gallons per minute of liquid. It takes about the same amount of power, but fits into a smaller space. As an example, a paper making machine might have 6 or 7 liquid ring pumps, all operating at different flow rates, and different vacuum levels, pulling water from the pulp slurry through several different appliances on the machine web path.

I wonder how your vacuum pumps run with slugs and solids without inlet separators. Think there have to be strainers, if not separators. Such strainers can be installed here as well.

Yes, the suggested system requires more space than conventional machines.

No strainers, they would plug with pulp soon. The liquid ring pumps tolerate solids of the type produced by paper machines with no trouble.

i’m curious as to how you provide a truly continuous flow of air or gas with your system. It would perhaps require the two tanks and a specially matched water and gas valves that could switch smoothly, so the vacuum is steady once you run out of tank. Or maybe I missed something in your concept drawing?

You may find the possible applications for a highly efficient heavy vacuum source such as this are limited, where the initial cost and space required will be higher, it seems likely.

You also need to consider the efficiency of your water pump, 80% at best, pumping 24,000 gpm in a two tank system, maybe?

I am visualizing three vessels such that the flow would be continuous. When vessel 1 is taking air/gas/vacuum, vessel 2 would be halfway towards pumping out or in and vessel 3 would be clearing the air/gas.

That seems reasonable. It would be interesting to see how water & energy efficiency plays out. There will come a time when water will be more costly than energy, recycling of liquid ring vacuum pump compressant has limits in many applications. Tissue machines have used high speed multiple stage turbines in lieu of liquid ring pumps, the operating cost was proven for the concept, but flexibility to address new process requirements was limited, so liquid ring pumps were added in.

Please look at my first pic, the liquid is circulated and, on the way cooled to reduce the evaporation loss.

Towards, “water & energy efficiency plays out”, centrifugal pump and liquid ring pump should theoretically consume the same energy. Practically, for the same energy spent, the liquid ring pump might fall short due to eddies happening in maintaining a perfect liquid ring inside an eccentric or elliptical casing. In a liquid ring pump, the liquid pistons successively go in and out between the blades of the rotor. This happening is effected by liquid ring and suction/discharge ports. This, I expect, may not be as smooth as in the case of the uniform shape of a piston inside a cylinder.

I personally have never seen such a method to create gas flow, where liquid ring pumps are typically applied.

Perhaps if you designed one to replace a liquid ring pump, you would get an idea of the cost to execute, and an idea if the efficiency, especially with centrifugal pump selection, and then get an idea of the actual savings in water and energy, if any. My guess is that it might be marginally efficient in certain special cases, but the time to recoup the investment would be excessive.