The acceptable levels of pyrolytic matter in the exhaust air stream, before different alarm stages are triggered, depending on the applied safety concept as well as on a number of material properties and process conditions such as the formation of pyrolytic matter during different self-heating stages and amount of airflow during the drying process.

 

 

Where, in a drying process or even during storage, process conditions can lead to self-heating and formation of ignition sources the ACOM Detection System will through multiple alarm levels give an early indication and/or take appropriate countermeasures (depending on the safety concept) ranging from warnings to emergency shut down and deluge activation. More than 500 products have so far been tested for their potential of producing enough pyrolytic matter when exposed to excessive heating. A typical example is shown in the picture below, where a heating deposit of milk powder in a spray dryer has been detected. After removal, the dryer could go immediately back into production without activation of deluge or other protection measures.

 

The system continuously samples all incoming airstreams as well as all outgoing airstreams of the process. The absolute CO concentrations for both, inlet and outlet airstreams are measured at the same time. This unique measurement principle allows to immediately eliminate CO entering into the process from such generated in the process. Both continuously measured CO values from the air inlet and air outlet are converted directly into delta CO values defining the trigger levels for the alarms and countermeasures. The adopted measuring principle even allows for setting different alarm levels for product change and/or varying process conditions (varying Self-heating properties, mass flow of air, etc., one of our customers even uses a slow increase of delta CO to define the dryers cleaning frequency).