Page 241 - Wastewater Solids Incineration Systems

Instrumentation and Control 203

Dating back to the industrial revolution, individual wires and instrument piping
have served these systems well. Present micro- and nano-electronics and digital com-
puter advances have provided expanded, sophisticated means to collect, analyze,
store, share, and communicate data so that operators can make decisions in the plant,
outside the plant, and, perhaps, from anywhere in the world.
The benefits of overall unit automation were recognized by large steam utility
boiler plants at least 50 years ago. Such a focus is still appropriate. Stultz (1972)
described automation’s advantages as follows:

• Improved protection of personnel and equipment through more complete
instrumentation, simplified information display, and more extensive and thor-
ough supervisory control.
• Reduced outages, reduced maintenance, and longer equipment life through
more uniform and complete control procedures of startups, online operations,
and shutdowns.

• Better plant efficiency through continuous and automatic adjustments to the
controls with the objective of optimizing plant operation.

• More efficient use of manpower during startup and online operation.
Its author continues with a discussion of installation and service needs and closes
with a cautionary and critical point: “A planned program of preventative mainte-
nance should be developed for the control system.”
There is no doubt that carefully planned preventive maintenance of instruments,
programmable logic controllers, computers, software backups, and similar activities
of bioenergy process control systems is absolutely essential for their proper and con-
tinued functioning and the ability to provide safe, efficient, and economical opera-
tions. Such systems are no longer an optional add-on but rather are integrated parts
of the entire process.

7.0 PROCESS CONTROL MEASURING
AND MONITORING

The wastewater industry most often controls “elements” that typically are powered
by electric motors: pumps, fans, compressors, blowers, conveyors, centrifuges, or
hydraulic power packs. This includes equipment that directs the output of or modi-
fies the power requirements of those elements, such as motor-operated valves, posi-
tioners, and dampers.