SB Liquid Ring Compressors - nsb ... with maximum discharge pressure up to 5,5 bar, ... Manufactured to comply with Section VIII, Division 1 of Asme c...

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Liquid Ring Compressors

Pompetravaini-NSB API SB Liquid Ring Compressor for Gas Processing A family of API liquid ring compressors has been developed and has been in the market for nearly a decade, they are specifically made for the Petroleum, Chemical and Gas Process Industries. The design takes into account all the applications where heat sensitivity of the gas, explosion hazard, wet gas or operational problems make impossible the use of other type of compressors. Reliability at highest level and low maintenance costs are the distinctive factors for this range of compressors.

Working Principle The liquid ring technology is based on a rotor centrally positioned in an oval shaped casing. Rotor is not touching the casing in which there is a precise amount of liquid that during rotation forms a ring, caused from the centrifugal force, that follows the casing outer shape. Due to the patented oval shape the ring is filling differently the volumes in between the blades of the rotors. In two points the liquid fills completely the volumes. In between the two points the liquid is receding in the beginning and up to half way, thus creating suction, it is then advancing creating pressure. The gas is entering the casing, where suction is generated, through the inlet port and it is leaving after it has been compressed through the outlet port. The liquid that is used for sealing is flowing continuously and is fed with a dedicated line. The sealing fluid is absorbing the heat of compression and it is leaving the casing together with the compressed gas and it is separated in a discharge separator tank.

Design The compressor has been designed in accordance with the requirements of API 681. It is available in single stage version, with maximum discharge pressure up to 5,5 bar, or double stage version, up to 14 bar discharge pressure. True back pullout design enables maintenance of the compressor without disassembly of piping and service liquid connections. By means of cylindrical gas distributors and relative large inlet gas passages, friction losses are reduced to the very minimum. Radial forces acting on the compressor shaft are balanced from the double acting design reducing shaft deflection and vibrations. The simple but sturdy construction of the SB compressor is completed from the overhung arrangement that requires only one shaft seal and bearing housings externally accessible. This features, linked to the liquid ring technology that ensure running without metal-to-metal contact, made the SB compressor highly reliable with very low running cost.

Each component is analyzed and optimized for the application. Modelling of the impeller with acting torque

The result showing the extent of displacement

Forces, moments and pressure acting on the cover

The result showing stress on the cover

Service liquid Gas mixture Compressed gas and liquid



Simple and robust construction Precision design and fit of impeller

No gap adjustment is necessary to the impeller. Proper positioning is assured through product design and precise manufacturing. Result is a faster re-assembly, shortening the downtime.

High efficiency shrouded impeller

Impeller designs optimizes energy transfer creating a highly efficient compression cycle. The impeller is dynamically balanced for smooth operation. This ensures a lower running cost.

Standard cartridge type mechanical seals per API Standards

Flanged connections per API standard 681

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Liquid Ring Compressors

All process and drain connection are flanged and conform to DIN or ANSI B16.5 norms. This feature will shorten installation time.

Innovative hydraulic design (patented)

Highly efficient cylindrical distributor features large inlet and discharge ports for optimum efficiency. Eliminates the need for compensated seal flow liquid. Simple and effective then big saving in running cost.

Available with single or double mechanical seals and API seal flush plan systems. Maximum flexibility in selecting the optimum mechanical seal configuration.

Bearing frame design in accordance with API Standard 681

Engineered piping arrangement

Features self-draining vertical or tangential inlet and tangential discharge connections to eliminate the collection of condensable fluids and service liquids in the piping system.

- True back pullout construction allows for service of seals and bearings without removal of process piping and motor. This will shorten intervention time. - Designed with dual thrust bearings and radial bearing for maximum reliability. Maintenance cost is reduced in a sensible way. - Grease lubricated bearings are standard, Oil Mist and Oil Flooded systems are available. This advantages prolong bearings life. - Vibration probe connection points are standard design. This ensures reliable and trouble free operation of the compressor with a more economical running cost. - Bearing frame inspection and drain ports. will speed up inspection and maintenance operation thus less expensive.

Low startup torque and operational speed

The low starting torque and low operational speed requirement, combined with a direct motor driven design, ensures a long compressor life, reducing running cost.

Robust overhung design

Manufactured to comply with Section VIII, Division 1 of Asme code or European Standards

The rigid shaft construction requires the use of a single shaft mechanical seal. A single moving element ensures trouble free operation, thus more economical life cycle.

Impeller and casing design allow for real back-pullout repair 4

Landing areas safely secure the impeller within the compressor allowing for the removal of the shaft. Non-interfering fit of impeller and distributor ensure the impeller will not seize. This solution ensures a less expensive maintenance intervention.

Materials of construction

Standard compressor materials include Carbon Steel and Stainless steel, optional materials are available. This allows the optimum material selection for each specific application.

- Forged steel materials are utilized for all pressure containing components. - Welding procedures are performed in accordance to European or ASME code. - Full penetration welds of all pressure containing components. - Inspection procedures are performed according to International Standards and Codes.


Customer’s Benefits

Engineered Compressor Systems

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Liquid Ring Compressors

- The liquid ring design principle allows for the handling of saturated, corrosive or contaminated gas streams. - No contact between components, minimizes wear and reducing heat, vibration, noise and maintenance requirements. - The continuous supply of cooled service liquid removes the heat of compression and maintains thermally stable conditions for the safe compression of hazardous, explosive and thermally sensitive process gases. - Almost isothermal process allows the compressor to run at low temperatures and thus longer service life.

Industries and Applications - Chemical - Chlor-Alkali - Chlorine Gas Compression - Carbon dioxide Compression - Drinking Water - Flare Gas Recovery - Gas Production

- Hydrogen & Phosgene Compression - Ozone & Oxygen Compression - Polymers - Pulp & Paper - Refineries - Vent Gas Compression - VCM Recovery

Materials Standard compressor materials are carbon steel and stainless steel, other materials are available as options. Contact our sales office for additional information.

We supply both standard and custom engineered compressor systems. Pompetravaini-NSB engineered systems are designed in compliance with the industry standards, international code requirements and/or customer’s specifications.

Capacity range 16 14

Discharge pressure (bar a)

12 10

The complete system design gives to the customers the confidence that each component is compatible with the system and the application.

8 6 4 2


0 100

7 1000 Suction capacity (m3/h)