Liquid ring vacuum pump start up

[Glenfiddich]

Have you had experience with the start-up of the liquid ring compressors/vacuum pumps? Is it a fairly operator intensive start-up procedure? Can it be started on auto? or does it need more TLC from an operator to start-up? How much time would it take to start up a vacuum pump?

 

[btrueblood]

They are simple enough to be used in commercial carpet cleaning machines (the kind mounted in vans/lorries that come to your house and steam-clean your carpet). Given that the lads who do this type of work are fairly low down the food chain, they can't be that user-unfriendly.

 

[Artisi]

0.5 or 1000kW?

 

[Glenfiddich]

75 kW and 149 kW.

 

[nickelkid]

Auto start should not be a problem when the pump, reservior, valves, and controls are configured correctly.

An OEM manual may help with you concerns, read and understand it well.

NB Regardless of size, an improperly installed liquid ring pump or compressor is a nightmare, on the other hand a proper installation (& application) can be trouble free for years.

 

[PISA]

Glenfiddich,

the key rules are:

1. never run the pump dry

2. do not start the pump over-flooded with water.


If you are running "once-thru" (without any recirculation of the seal liquid) then just open the seal liquid supply (solenoid valve) simultaneously with the vacuum pump / compressor motor.

In case of a recirulation the key issue is the level control in the discharge separator (always enough water in order not to run dry, but never higher than shaft level for the next automatic start.)

Never start the vacuum pump / compressor with a casing fully filled with water.
The water (in the compression chambers betwwen the blades) cannot be compressed,
the consequences will be shaft deflection and posssibly a pump ceasing.

A check-valve in the inlet or discharge piping may avoid the filling of the pump with liquid at shut-down (the system is still under vacuum but the discharge separator is at atm. pressure).

Ideally, with a good piping design, the seal liquid (after shut-down ) will communicate between separator and pump, to get an equlibrium at the right (shaft) level.
If it is not possible then add an equalization (liquid) line (1 inch) between discharge separator and vacuum pump casing.


It takes time to build a stable ring, from 20-30 seconds up to 2-3 minutes depending of starting conditions.


Anne Delestre

http://www.cutes-europe.com

 

[quark]

Good advice by PISA. Auto drain valves are provided to the casing to take care of drainage when the pump stops. These drain valves work as NRVs as well and doesn't allow atmospheric air breaking in.

Fill the sealing fluid with starting of the pump as already suggested. I always use an NRV in the pump suction line if the pump is installed at a level above the user equipment.