Page 46 - Wastewater Solids Incineration Systems

Safety 15

resolved, mitigated, or eliminated through design changes to improve the safety and
operability of the facility under design.
For incineration systems, HAZOP reviews are a systematic and structured
method to identify potential safety problems and the appropriate mitigation mea-
sures to reduce the risks. HAZOP reviews can be performed during all stages of
design of an incineration facility, from concept through various levels of completion.
HAZOP may also be used for existing facilities.
HAZOP reviews generally include the following:
• Description of the facility being reviewed. The review may include an entire
system, a part of it, or specific items of equipment. Drawings, particularly
process and instrumentation diagrams, are used to identify nodes for study
and to chart progress of the review.
• Nodes or parts of the facility are selected for individual review using parameters
such as flow, temperature, pressure, and level and deviation guidewords such as
more, less, obstructed, or reverse flow, or higher or lower temperatures, to dis-
cuss causes and effects of deviations and to determine consequences.

• For each cause, the consequences are discussed, and safeguards (anything that
could prevent or alleviate consequences) are identified. Recommendations for
modifications such as design changes or drawing changes, and requests for
additional information are also recorded. Such recommendations require
follow-up to ensure mitigation of concerns.
• When all nodes have been examined, the HAZOP study is completed. However,
additional review may be needed based on responses to the recommendations.
After completing the review, the design and operations team evaluates the safe-
guards and makes recommendations for incorporation into the design. If changes are
recommended, an additional HAZOP review should be considered.
HAZOP reviews increase awareness by designers, owners, equipment suppliers, and
operators of potential risks associated with operation of the process. Reviews should be
timed to allow design changes to be made before construction begins. Reviews also force
a more thorough discussion of the functions of facilities, which benefits all parties by
helping them understand operation before construction is completed.
As outlined above, a HAZOP review can provide safety benefits by ensuring that
the system has been thoroughly reviewed for safety concerns and providing an
opportunity to educate plant personnel of some of the safety issues involved in oper-
ating an incineration system.