Page 102 - Boiler plant and distribution system optimization manual
P. 102
The Control of Boilers 87
logic.” Digital control systems often combine 1. The control instructions and set points can
the functions previously performed by separate be easily changed.
hardware systems such as combustion control,
2. The systems are easily expanded to include
safety controls and interlocks, and monitoring
more control features or more boilers.
and data acquisition.
In a typical DDC system, input devices such 3. Low cost control redundancy.
as sensors, switches and position encoders are ac- 4. Boiler operation diagnostics and perfor-
cessed at very short intervals insuring any prob- mance data acquisition.
lem is dealt with almost immediately.
The advantages of distributed digital based 5. Control system self-diagnostics.
control systems include: 6. Easy access to important real time or histori-
cal information by telecommunication links.
Figure 8.14—A carbon monoxide trim system is capable of maintaining the most effi-
cient air fuel ratio because it does not need a buffer zone. It locates the most efficient
operating level automatically.
