ISA 77.43.01 – Fossil Fuel Power Plant Unit/Plant Demand Development – Drum Type

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.