New liquid ring vacuum pumps

Capable of operating reliably in humid and dusty environments, the sturdy AWS and AWD units are designed to deliver vacuum to a wide range of industries including food and beverage processing, mining and minerals, petrochemicals, steel, cement, plastics, pulp and paper, textiles and pharmaceuticals.

“Our latest liquid ring pumps combine a low-maintenance design with highly efficient performance and near-silent running,” says UK vacuum product manager Richard Oxley, highlighting the benefits of the technology. “They are extremely well suited for wet or corrosive processes and offer short lead times and minimum life cycle costs.”

Capacities for liquid ring pumps typically range from 170 to 37,500m³/h. Lower capacity units below 5500m³/h are available as single-stage AWS models or two-stage AWD models pre-configured with direct-drive options in 50 and 60Hz speeds. For larger installations, high capacity AWL pumps with belt or gearbox transmission are available.

Single stage AWS pumps are said to offer outstanding efficiency above 200mbar (absolute), making them suitable for general process applications such as filtration and dewatering, and pump down or evacuation duties. 

Meanwhile, the two-stage AWD pumps provide continuous high performance at operating pressures below 200 mbar (absolute). Two synchronised pump chambers work in series to achieve high performance and improved efficiency on continuous process duties such as drying, degassing exhausting and solvent recovery. 

All AWS and AWD pumps can achieve ultimate pressure levels as low as 30 mbar (absolute). They are available in three pre-engineered modular configurations designed for once-through, partial recirculation or total recovery of service water. In most cases all wetted system components are manufactured from stainless steel. 

“We try to make our customers’ lives as easy as possible – so we offer all three configurations as pre-fabricated, plug-and-play modules, including pump, motor and water recirculation system mounted on a compact skid,” Oxley explains. “This means they will receive a complete solution that can be easily installed and commissioned with a minimum amount of work.”

The once-through pump is the module with the simplest design. It consists of a pump with an electric motor, drive system and skid. It is ideal for installations with an adequate supply of site water, which can then be continuously drained from the pump for re-use. The pumping system adds no contaminates to the service water other than those coming from the process.

In the case of partial recovery, the discharge liquid-process gas mixture is collected in a vessel where it is mixed with fresh sealing liquid to ensure a constant temperature in the pump. Excess liquid is released from the system via an overflow. Atlas Copco says that, compared with once-through operation, this mode of operation typically saves 50% of the fresh water required. 

“With total recovery, liquid savings of up to 95% are possible,” Oxley explains. The recovered liquid is cooled via a high efficiency heat exchanger before being returned to the pump chamber. “This configuration works with a closed liquid cycle and is recommended because it physically separates the cooling water circuit from possible process contaminates.”