BASIC DESIGN


INTERCAT addition system Johnson Matthey

The basic INTERCAT addition system consists of a storage vessel for the additive or catalyst, associated piping and equipment to load the vessel and a control system which controls the supply of catalyst to the FCC unit.

The flow of the catalyst from the hopper is precisely controlled by the INTERCAT Management System (IMS), the heart of the addition system.  The IMS is a self-contained, digital, electronic controller which controls and tracks the catalyst or additive loaded into the regenerator.  The operator enters the amount of catalyst or additive to be added daily to the process as a set point.  By reading the vessel load cell output directly, the IMS automatically adjusts the periods between fixed shot additions to control catalyst addition rates precisely to refinery requirements, automatically spreading the additions out over a full 24 hour period each day.  The IMS then controls, monitors and logs the catalyst or additive additions.  It also provides graphical displays which show current and historic additions and how these compare with set points.  The IMS can be interfaced with the plant's distributed control system (DCS) via a serial digital inteface (MODBUS) and/or using a 4-20 mA signals.

The hopper is mounted on three load cells.  Any change in weight is detected by means of these load cells allowing the IMS to precisely monitor and control catalyst and additive additions.

The catalysts flow through a patented control valve, the Everlasting Valve, located below the outlet of the vessel, into the catalyst feed line.  The Everlasting valve is the only moving part of the system in frequent contact with catalyst during normal operation.

When refilling, carrier air is usually vented to atmosphere.  To prevent any fines escaping, the INTERCAT loader is fitted with a sintered metal filter (SMF).  This is a stainless steel mesh, self-cleaning system which prevents any powder escaping the addition system during refill.  There is a back pulse system that cleans the filter whilst in operation and blows back the fines into the vessel.

These SMF's are also available for retrofitting to existing addition systems, and refinery main catalyst storage hoppers to eliminate dust emissions.