Small liquid ring pump how it works
Another application is the vacuum forming of molded paper-pulp products egg cartons and other packaging. Other applications include soil remediation, where contaminated ground water is drawn from wells by vacuum. In petroleum refining, vacuum distillation also makes use of liquid-ring vacuum pumps to provide the process vacuum. Liquid-ring compressors are often used in vapor recovery systems.
Liquid-ring vacuum pumps can use any liquid compatible with the process, provided it has the appropriate vapor pressure properties, as the sealant liquid. Although the most common sealant is water, almost any liquid can be used.
The second most common is oil. Since oil has a very low vapor pressure, oil-sealed liquid-ring vacuum pumps are typically air-cooled. For dry chlorine gas applications concentrated sulfuric acid is used. The ability to use any liquid allows the liquid-ring vacuum pump to be ideally suited for solvent vapor recovery. If a process, such as distillation or a vacuum dryer, is generating toluene vapors, for example, then it is possible to use toluene as the sealant, provided the cooling water is cold enough to keep the vapor pressure of the sealant liquid low enough to pull the desired vacuum.
Ionic liquids in liquid-ring vacuum pumps can lower the vacuum pressure from about 70 mbar to below 1 mbar. From Wikipedia, the free encyclopedia. Ionic liquids — designable materials for high-performing fluids.
Retrieved from " https: Webarchive template wayback links. Views Read Edit View history. In other projects Wikimedia Commons. The white dots are confined between the cone and the ring of rotating liquid. The gas is compressed as the liquid ring converges with the cone. This represents the compression of air or gas from vacuum up to atmospheric pressure, or from atmospheric up to positive pressure in a liquid ring compressor. When each chamber rotates to the discharge port opening, the compressed air or gas escapes from that chamber through the discharge port to the internal discharge passage.
Air or gas, with the dots closely packed to indicate higher pressure, is shown here flowing out of the discharge connection at right. The flow is continuous without pulsation. In this completed schematic, the entire vacuum pumping cycle is shown. Here air or gas entering the NASH pump is shown as white dots at the inlet connection. This represents the compression of air or gas from vacuum up to atmospheric pressure, or from atmospheric up to positive pressure in a liquid ring compressor Discharge 9.
The discharge pressure of the pump is needed to determine any reduction of pump capacity or any increase in operating horsepower. Most liquid ring vacuum pumps are designed to operate from a vacuum suction to an atmospheric discharge pressure. If the discharge pressure is increased, then more energy or brake horsepower is required to operate at the increased compression range.
By changing the discharge pressure, the efficiency of the pump is changed and the capacity of the pump may be reduced to compensate for this greater compression range. Liquid ring vacuum pump manufacturers are able to determine if cavitation can result from a particular application. Cavitation occurs as a result of rapid boiling of the seal liquid. During boiling, bubbles form in the liquid and seek to escape.
As the bubbles rise in the liquid, they are subjected to higher pressure zones and can collapse. The void of space that is left after the bubbles collapse is instantly filled with liquid.
This phenomenon leads to extensive erosion or pitting of the pump internals. Cavitation can be detected by a rumbling noise that sounds like marbles rolling around inside the pump.
This sound should not be confused with that occurring as a result of "water hammer. If the liquid ring pump is disassembled and the impellers and port plates are pitted, cavitation is evidently occurring. A liquid ring pump with flat port plates can be easily machined and reassembled.
In contrast, a liquid ring pump with conical ports is more difficult to machine because of the taper and angle of the cone. Visual inspection should be performed once the liquid ring pump is up and running.
The vacuum level, seal fluid temperature and seal fluid pressure should be checked and compared with the design conditions. The bearing housing should be warm to the touch. A hot bearing housing can indicate a bad or worn bearing, or misalignment.
A liquid ring vacuum pump is a very versatile machine. It can handle wet loads and has no metal-to-metal contact. It also acts like a direct contact condenser; it can absorb the heat generated by the compression, friction and condensation of the incoming gas; and it will absorb and wash out any contaminants entrained in the gas.
In spite of this versatility, however, sizing and selection of the most economical system still requires full information concerning not only what fluids it will handle, but how it will be operated. Vacuum Pumps Liquid ring vacuum pumps are commonly used to handle wet gas mixtures i.