Addition systems

INTERCATTM addition systems have been in widespread use on the FCC process since the mid 1980s, and today there are over 300 units installed in refineries throughout the world.

These come in a variety of configurations, for adding FCC additives from a few kilograms per day to fresh catalyst systems at tens of tonnes per day. Our fresh catalyst addition systems are recommended for new FCCs by licensors Technip Stone & Webster, Axens, UOP and CBI Lummus.

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The advantages of an INTERCAT addition system include:

  • Reliable and precise additions. Allows for improved control of unit severity
  • The ability to control e-cat activity. Permits higher throughputs, higher severities or the processing of a greater range of feed stocks.
  • The ability to add additives separately from the fresh catalyst. Allows the refiner the flexibility to quickly respond to changing market conditions.
  • More stable and efficient FCCU operation. Adding small shots of additive over a 24 hour period is up to three times more efficient than adding large quantities at the end of each shift


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.

  • Single Additive Addition System (AAS), usually 1 to 10t capacity.
  • Fresh Catalyst Addition System (CAS), up to 120t capacity or 4t day hopper design.
  • Multi-Compartment Addition System containing three separate compartments (MC3).
  • Multi-Source Catalyst Addition System (MSCAS) – A skid mounted unit that can draw catalyst and additives from up to 4 separate hoppers or tote bins.

In the INTERCAT Catalyst Withdrawal System hot spent catalyst is withdrawn continuously into a collection vessel which is very similar to a 200ft3 addition system on load cells. The rate of catalyst withdrawal is dynamically controlled using vessel weight readings and differential pressure control. When the vessel is full, catalyst is automatically transferred to the spent catalyst hopper. The skid contains a specially designed heat exchange module allowing the withdrawn catalyst to be cooled to a specified temperature.

Gases vent from the collection vessel through a Sintered Metal Filter (SMF) and the vessel pressure is regulated by a valve on the clean side of SMF thus eliminating erosion.

Most existing FCC Catalyst Withdrawal Systems are very basic with simple manual control by gate valve and manual carrier air adjustment. High temperatures and poor velocity control result in high erosion rates of valves and lines resulting in frequent maintenance being required with the subsequent risk of hot catalyst spills. Erosion of the throttling device for controlling withdrawal rate is completely eliminated with the INTERCAT Catalyst Withdrawal System by a pressure balance design allowing the use of a simple on/off Everlasting valve.

Infrequent withdrawals also result in large, sudden changes in regenerator catalyst bed level which can have a significant impact on unit operation and flue gas emissions. With the INTERCAT Catalyst Withdrawal System withdrawal is continuous so bed level can be kept constant.

Johnson Matthey has the ability to manufacture addition systems to multiple National Standards, including:

  • The National Board of Boiler Pressure Vessels (NB) Stamp.
  • The National Board of Boiler Pressure Vessels (R) Stamp.
  • The American Society of Mechanical Engineers (U) Stamp.
  • The American Society of Mechanical Engineers (S) Stamp.
  • KGS Certification (Korea).
  • SELO Certification (People’s Republic of China).
  • PED: Johnson Matthey Process Technologies are qualified to build pressure vessel in accordance with The European Community Pressure Equipment Directive 97/23/EC.
  • Canadian Certification (CRN)

Control systems can be supplied with Zone 1 or Zone 2 certifications through ATEX, UL, CSA, CMRI/CCOE, KOSHA or KGS.

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