In March the Vaal branch was fortunate to have its Technology Evening sponsored by WIKA Instruments when general manager, Ralf Hesse, gave a presentation on multipoint thermocouple systems and furnace tube-skin measurement.
Even though WIKA has a world of experience with temperature measurement and a large range of supporting products, in 2012 it saw an opportunity to expand its product range and improve service delivery to clients by acquiring Gayesco, a specialist in the field of reactor and skin-point temperature measurement.
The Gayesco systems are specifically developed for chemical and petrochemical customers and the design is usually done together with process licencers like Lummus or UOP, who may specify the product as a recommendation, a best practice, a preferred product or an equivalent. Traditional reactor bed installations consist of bundles of thermowells to measure temperature gradients in the catalyst. These systems normally provide a localised group of measurements and usually have slow response to change due to the large thermowell wall thicknesses. The effectiveness of such measurements is not optimal and catalyst damage may occur in areas that are not covered by measurement points.
Gayesco developed the radial thermocouple systems during the 1980s to offset the shortcomings of the traditional measurement techniques. First installations were done in 1988 and most of these systems are still running. In the radial thermocouple system, a large number of thermocouples enter a reactor flange and are routed along pre-manufactured runners towards the specified distributed measuring points within the reactor beds. Having fast response accurate measuring points improves the lifespan of catalysts and gives process engineers more reliable data for the control of the reactor. As many as 72 thermocouples have been connected through one flange already, only limited by the flange size.
The second part of the presentation covered skin-temperature measurement of boiler tubes in furnaces, the intent being to extend tube life and prevent catastrophic failures. Both subjects are seen as critical for the efficient and safe operation of furnace installations. Traditionally skin temperature measurement was done by inserting a thermocouple into a contact block welded to a boiler tube. Mounting of the contact block requires specialised welding procedures and these installations are prone to failure due to direct flame impingement and corrosion.
Gayesco provides two options for improvement. The Refractopad consists of a weld-pad and a thermocouple shield that can be installed to protect against flame impingement and corrosion. The second option is a further refinement and called the Extractopad. It provides an extractable thermocouple installation that allows for replacement of a failed thermocouple without additional welding. It consists of a guide tube and a heat shield with moulded insulation for maximum thermocouple protection.
Both of these solutions showed the commitment of an organisation to engineering reliabile solutions for a specific industry. The branch thanks WIKA for sharing this well received presentation.
Vaal branch Technology Evenings are usually held on the first Thursday of every month at the Iscor Bowling club in Vanderbijlpark. If you or your company are interested in joining us as a visitor or speaker, please contact Dirk van der Walt at dirk.vanderwalt@proconics.co.za
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