Pumping solids

The problem

 Poor reliability and high maintenance costs were causing problems at the R & D Chemistry Pilot Plant in Stevenage. These issues were arising in the Fume scrubbing applications and the pumps that operated in that area.

 

The existing pumps resilience to cope with general process problems associated with frequent stop start, suction filter blockage and the capability to handle solids were identified as the main issues that needed attention.

 

The Solution

Verder proposed the adoption of the TB Series of pumps that not only provide excellent solids handling but also a very low NPSH capability and a zero, balanced thrust design.

 

Verder were invited to supply and install a trial unit which after 14 months of trouble free zero failure operation lead to a contract to supply and install a further 42 units.

 

This has completely eliminated the annual maintenance spend of £80K. In addition to this, plant utilisation has been increased and the requirement to hold a substantial spares stock has been eliminated, Verder holding a specific stock of all components on a next day delivery basis by agreement.

 

The existing Iwaki pumps have now been relocated to another Glaxo site that for the moment continues to use the older style units.

 

The Detail

The original Iwaki pumps utilise aluminium oxide shafts and point load thrust dissipation, in addition the solids handling capability is limited. Protection from solids is provided by suction filter baskets but these have a tendency to block and expose the NPSH requirement of the pump resulting in cavitation and damage to the pump. Due to variations in the the process solids can form in solution and there is always the potential of carbonates to form in the scrubber liquor, this can vary site to site depending on the degree of hardness of the local water.

 The Verder TB series works with these problem areas, the pump has a zero balanced thrust design and hence no internal thrust bearings eliminating any internal high force areas where solids can abrade the pump. The rear of the pump is further protected by a self contained rotary filter that ensures that all solids are contained in the impeller end of the pump and are quickly dissipated through the discharge.

 

The TB shaft and bearings are manufactured only in silicon carbide, the remperature gradient of this material is slower on the build up and quicker on dissipation than ceramic making the pump much more forgiving and tolerant of any intermittent short term dry running.

 

The pumps are highly efficient and have exceptionally low NPSH requirements giving a stable hydraulic platform that can cover a wide range of process demands.

 

 

Extra Information