Addition systems

Johnson Matthey's addition systems have been in widespread use on the FCC process since the mid-1980s, and today there are over 400 units installed in refineries throughout the world. Without continuous catalyst addition, the FCC cannot operate. Many additives are used in the FCC process to increase profitability or to meet environmental regulations. Without a dedicated addition system the FCC cannot perform it's basic functions. 

The addition systems come in a variety of configurations. There are designs for single additive or catalyst addition, and different types of multi-loaders for multiple additive and catalyst addition. The addition amount can range 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 Lummus.

The advantages of an INTERCAT addition system include:

  • Reliable and precise additions to improve control of catalyst activity and yields, and reduce catalyst consumption.
  • Ability to add additives separately from the fresh catalyst. Brings user the flexibility to quickly respond to changing market conditions.
  • Ability to add additives separately from the fresh catalyst. Brings user 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. 
  • Improved operability, improved profitability, and improved reliability. 


Basic design

The standard Johnson Matthey addition system consists of a storage vessel mounted on 3 load cells for continuous weight measurement. These load cells ensure the utmost accuracy of the system to allow the IMS controller to precisely regulate the catalyst or additive additions. The discharge line from the vessel to the FCC is equipped with a patented Everlasting valve, the only regularly moving part in the system. The Addition System also includes a Sintered Metal Filter for particulate emissions.

The INTERCAT Management System (IMS) controls the flow of the catalyst from the hopper to the FCC. 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. The IMS has the ability to be controlled locally and can be interfaced with the plant's distributed control system (DCS). The DCS connection options include analog, digital and/or Modbus.

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 catalyst and additives flow through a patented control valve, the Everlasting Valve, located on 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. The everlasting valve is a main contributor to the high reliability of these systems.

To prevent any fines escaping during the refill process, the Johnson Matthey loader is fitted with a sintered metal filter (SMF). The filter element is a special alloy fiber compatible with high temperature and abrasive operation.  As catalyst enters the hopper, it displaces air which exits via the filter unit before being discharged to the atmosphere. The filter cartridge media collects catalyst particulates preventing discharge to the atmosphere. The particulates build into a filter cake on the surface of the filter elements leading to increased filter element differential pressure. The SMF includes an air back pulse system that uses pulse jet air to release the filter cake from the SMF and it is controlled by the Intercat Management System.

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

Addition system sizes and designs

  • Single Additive or Catalyst 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.
  • COP Mini Loader designed to add shots as small as 0.1 kgs/day to accurately spread promoter addition throughout the day to improve afterburn and CO control.

INTERCAT catalyst withdrawal system

In the Johnson Matthey 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 Johnson Matthey 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 Johnson Matthey Catalyst Withdrawal System withdrawal is continuous so bed level can be kept constant.

Fabrication certification and qualifications

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.
  • 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)

Standard control systems are supplied with Zone 2 (Class 1, Div 2) certification.

Get in touch

FCC additive team