Page 186 - Advanced Mine Ventilation

166 Advanced Mine Ventilation

Figure 11.1 A schematic for a permissible filtration system.

The efficiency of the filtration system varies from 70% to 95% but most of them
have 90% to 95% efficiency. Synthetic paper filter is thermally resistant and hence
preferred but it is more expensive than the ordinary paper filter.

11.3.4.2 High-Temperature Filtration System
They are a bigger version of the catalytic converter but similar in principle. The
exhaust gases pass through a filtration system made of a ceramic or silica body that
are coated with catalytic metals such as platinum, rhodium, and palladium. They

require that exhaust temperature be maintained above 350 C for a short duration
each shift for proper operation. They are ideally suited for heavy-duty diesel equip-
ment working out by but may not be suitable for light-duty equipment for they cannot
raise the exhaust temperature high enough for the filter to regenerate. Gradual soot
buildup in the filtration system often reduces the efficiency and increases the pressure
drop across the unit. In most cases, it is desirable to remove the filtration system and
regenerate (burn all soot) in an external regenerating kiln. A spare is needed for contin-
uous operation of the equipment.
Table 11.10 compares the various performance characteristics and cost for the two
main types of DPM filtration systems.