Catalytic Air Cleaner
Zero Gas Generators for Applications in General Purpose and Classified Areas (Zone 2)

Applications

System features

General description

Classified areas
Protection
Safe operation

Technical Data

System features

• Two models: Standard system AMS 8100 for general purpose, AMS 8150 for classified areas Operating principle: catalytic oxidation
• Desktop or 19“-rack for the AMS 8100,
• wall mountable IP65-enclosure for the AMS 8150
• Continuous purging for operating in CENELEC zone 2 according to EEX p IIC T3 (model AMS 8150)
• Different catalytic material to match custom demands
• Conditioning of the incoming and cleaned air
• Molecular sieve to remove water vapour
• Options: Filters and coalescers to remove oil vapours and dust

General description
To meet various customer demands, AMS air cleaner are supplied in different models as well as with a choice of catalysts.

• AMS 8100: for applications in general purpose areas
• AMS 8150: is designed for Ex-Zone 2
• Catalysts: Pt; alternatively Pt/Pd

The catalyst
The operating principle employed in both, the air cleaner AMS 8100 and the AMS 8150, is a catalytic oxidation process.
Due to the catalytic effect of platinum at temperatures of about 600°C all Hydrocarbons (inclusive Methane) and Carbonmonoxide will be oxidised into carbon dioxide and water.
Of course the amount of platinum catalyst applied will not be reduced through this reaction. But catalyst poisons as e.g. Sulphur compounds may reduce the efficiency of the catalyst gradually. To increase the reaction surface and to minmiize the amount of platinum material needed, the Pt-catalyst is actually a layer on granulated Al2O3.
Using the recently developed Pt/Pd-catalyst the operating temperature can be decreased to 380...400°C well below the ignition temperature of most hydrocarbons, of Hydrogen and Carbonmonoxide. This is a great advantage for operation in classified areas.

The catalytic reactor
The catalyst granulate is packed into a reactor and will be indirectly heated up to the proper temperature of about 380°C .... 600°C via an electric heater.
By a proprietary design of the reactor, the gas is forced to maeander through the catalyst mataerial, thereby both intensifying the contact between gas and catalyst and extending the time of contact as well.
A vertical set-up of the reactor (AMS 8150 only) prevents the built-up of catalytic inactive gas channels where the gas may flow without any contact to the catalytic material.

The heat exchanger
The heat of the cleaned air is used to warm up the incoming air. This is done in a counter-flow heat exchanger. By this, the cleaned air will be cooled down to approx. 35°C and the incoming air will be heated up to approx. 300°C.
This design is of great advantage achieving a more constant reactor temperature - even at higher flow rates or at lower ambient temperatures.
Finally, a molecular sieve removes water and traces of Nitric Oxides from the hydrocarbon- and CO-free air.

Operating parameters
The inlet air pressure may be up to 15 bar (abs), thatīs why in most cases an additional pressure controller is not necessary to be integrated into the gas flow.
The air flow should not exceed 300 Nl/h for the AMS 8100 and 500 Nl/h for the AMS 8150.
Measurements have proved, that even Methane (max. 1000 ppm) is quantitatively removed at this flow rate.

Classified areas
Protection
Using Pt/Pd as catalyst for the oxidation process the reaction temperature may be kept below 400 °C. This temperature is also below the ignition temperature of most Hydrocarbons, of Hydrogen and Carbonmonoxide. Additionally the instrument housing is continuously purged with air, ensuring an overpressure of 50 Pa (0,5 mbar) minimum. This design allows the operating of the air cleaner AMS 8150 in areas classified as CENELEC Zone 2, according to the requirements for EEx p IIC T3. The instrument meets the demands of EN 50021. But as some parts of EN 50021 are still under negotiation, the directions of the previous standard VDE 175 habe been used to fill the current gaps in standardisation.

Safe operation
The purging air is simultaneously used as coolant air for the housing and for the electronic parts builtinto the measuring unit. Actually the purge air flow must not be reduced below the factory adjusted value. Depending upon the ambient conditions at the point of installation, even an increase of the purge air flow above the rate necessary for the required over-pressure may be necessary to ensure a sufficient cooling of the unit.

The air purge must therefore also be kept in operation in general purpose areas.

To monitor the purge air flow, a flow monitor with an alarm signal in fail-safe wiring is provided. An additional safety measure to protect the instrumentīs electronic parts, is monitoring the temperature of the inner surface of the enclosure of the catalytic reactor. In case of an excessive temperature (Tsurface > 90 °C ), the heater of the catalyst is switched off and an alarm signal is generated. To reset this alarm, a manual reset is required, even if the temperature falls below the critical value.

Technical data