Page 43 - Wastewater Solids Incineration Systems

12 Wastewater Solids Incineration Systems

In addition, multiple-hearth incinerators pose unique personnel safety problems
because they include observation ports, which are used to check combustion condi-
tions within the incinerator. Many units are equipped with sliding or hinged covers
that can expose the observer to hot incinerator gases when open, particularly if the
incinerator should lose negative pressure. Personnel working near or on those incin-
erators should wear proper eye protection, clothing, and other equipment. Modifica-
tions to provide better protection include glass covers for observation ports to allow
visual checking without direct exposure to incinerator gases.
Multiple-hearth incinerators are equipped with hearth doors to provide access
for maintenance of the plows and arms and removal of clinkers. Such maintenance is
normally scheduled for periods when the incinerator is out of service. In the event
that emergency “hot” maintenance is required, it must be performed under condi-
tions that pose risk to personnel. Special safety precautions, including protective
clothing, gloves, and hoods must be observed.

3.2 Fuel Safety Provisions

Either oil, natural gas, or both, can be used to initially heat the incinerator and as sup-
plemental fuel when needed. Fuel supply and combustion systems should include
the following safety features:

• Design of supplemental fuel supply piping, with consideration for sizing,
materials, configuration, support, shutoff valves, and pressure and flow con-
trols in accordance with applicable standards.
• Design of supplemental fuel safety systems, with consideration for gas condi-
tioning, burner equipment standards, pilot type, ignition type, flame moni-
toring, combustion air pressure monitoring, fuel pressure control and moni-
toring, emergency fuel shutoff, venting, and purging, in accordance with
applicable standards.

3.3 Fire and Explosion Protection
Modern incinerators, both fluid bed and multiple hearth, have a good safety record
in prevention of fire and explosions. Here are some of the provisions that should be
included in the design of either fluid bed or multiple-hearth incinerator systems:

• Solids handling systems configured to reduce the risk of spills and accumula-
tion of solids that could dry and produce combustible dust, which could lead
to explosion.