Catalyst Tank Multipoint Thermocouple Sensors

Problem

A customer was having problems developing a novel reaction vessel. They needed to understand and control the processes occurring in a fluidised bed catalyst tank producing Vinyl Acetate Monomer (VAM). Spontaneous fires were rapidly degrading platinum catalysts. A significant plant life extension was urgently required.

The objectives were to produce a temperature sensor with up to 60 discrete measuring points with temperatures up to 300C throughout the vessel. The customer requested no thermowell to avoid temperature averaging and to increase probe flexibility. Probes were to be inserted through a flanged port and then routed around internal framework. Measuring tips were to be located at strategic points near oxygen spargers. At the tank entry, double sealing was required to contain the pressure and to provide the termination point for cable extension to the instrumentation.

Our Solution

Designing the double pressure containment was done in collaboration with the customer to meet the physical constraints as well as safety concerns.

Mineral insulated type K thermocouples were used with a double Hastelloy C276 sheath to withstand the acid. They were very flexible and easily bent with hands. The probes had an epoxy resin seal within the flange assembly as well as secondary compression fittings to hold the pressure. ASME IX coded welding was used. A bespoke termination enclosure was secured to the flange assembly and pre-wired to Multicore extension cable.

The 60 discrete sensors were all different predetermined lengths. The probes were pre-bundled according to the defined routes. All the probes were marked for easy identification in the uncomfortable working space of a catalyst tank. This made installation easier. They were secured to the internal framework and the measurement points could be placed exactly where the customer required with no averaging between probes whatsoever. We also provided some straightening rolls to deal with any kinks or bends that may occur. They were delivered in a degreased clean condition.

Outcome

Probes were delivered onto site ahead of schedule and within budget. They were fully documented for all tests and materials used. They were installed straight into plant. A fault free performance has resulted in repeat orders for new plant.

Catalyst Tank Multipoint Sensors

Problem

Our Solution

Outcome