ISA 77.43.01

The scope of this standard is to address the unit/plant demand development subsystem for boilers with steaming capacities of 200,000 lbs/hr (25 kg/s) or greater. This subsystem includes generation demand, boiler demand development, turbine demand development, throttle/header pressure control, and unit megawatt/steam flow control as applicable.

This standard will address two types of process applications:

a) a single boiler supplying a single turbine, typical of an electric utility power plant; and

b) a single boiler or multiple boilers supplying a common distribution header, typical of an industrial power plant.

Specifically excluded from consideration are:

a) dispatch control;

b) turbine/generator control (other than turbine demand);

c) feedwater controls

d) steam temperature controls (covered separately by ANSI/ISA-77.44.01, Fossil Fuel Power Plant – Steam Temperature Controls);

e) combustion controls (covered separately by ANSI/ISA-77.41.01, Fossil Fuel Power Plant Boiler Combustion Controls);

f) steam distribution control systems;

g) economic loading of boilers; and

h) fluidized bed boilers.

Purpose

The purpose of this document is to establish the minimum requirements for the functional design specifications of unit/plant demand development for control systems for fossil-fueled power plant boilers.