Diagrams dual nature

At the heart of this issue is the question of how diagrams are used by the learner. Potentially, any diagram has a dual nature. This duality was briefly discussed at the end of chapter 7. On the one hand, a diagram may function as a marker, serving as the... 

A catalytic filter, rather than a filter followed by a catalytic bed, or a monolith followed by a filter, simplifies the process flow diagram, reduces equipment requirements, leads to higher thermal efficiency and reduces costs. Ceramic hot gas filters lend themselves naturally to adaptation for this dual purpose. 

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