Pumping of latex agglomerate
Polimeri Europa is one of the major world producers of elastomers at their plants in Hythe and Grangemouth, United Kingdom.
For years, the latex agglomerate used during production had tended to clog in the existing centrifugal pumps causing them to overheat and leak. Despite a regular maintenance schedule of strip-ping, cleaning and rebuilding the pumps and re-packing the glands, seizures would still occur each month, some-times resulting in the failure of a shaft or bearings. The consequence was un-planned downtime and disruption to critical stages of the production process.
Polimeri Europa commenced a search for a pump with low levels of cohesion to avoid the latex build-up. In addition they were looking for a robust design with specialised mechanical seals to minimise pump seizures on the process side. No standard products were identified as being suitable and so Polimeri Europa invited a number of ISO9001 accredited pump suppliers with proven track records to propose how they could resolve the problem.
Amarinth were selected for their ability and willingness to work with Polimeri Europa on optimising a design which would include special features outside of their standard catalogue. The design parameters were for a pump that could run for some three weeks before requiring any maintenance.
The base pump chosen was an N-series which included a removable front suction cover enabling quick access for cleaning. A scalloped impeller was specifically designed to minimise clogging and an electro-polish was applied to the back-plate and impeller to create low cohesion surfaces. Finally a special mechanical seal was designed to contain the latex agglomerate.
The new pumps were delivered on-time and are meeting design expectations on this very demanding application. Reli-ability has improved by a factor of 15 and a quick internal jet-wash is all that is often needed. Previous pumps required cleaning and re-packing every few days, or even daily during difficult running conditions, a process that took 6 – 8 man hours for each pump. The resultant cost savings in parts and labour mean that the pumps will pay for themselves in just nine months.
Continuous design enhancements
The benefits of an electro-polished surface finish have been firmly established and research is now underway into how to make this process more cost effective for the next phase. Minor profile modifications will also be included, in particular to form an open wedge shape on the back of the impeller blade webs to further enhance their self-cleaning ability.
Polimeri Europa has now brought additional pumps on-line and is working with Amarinth to enhance existing pumping solutions in other applications.
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