The power industry has seen various steam temperature control systems developed over the years to fit the needs of particular applications in the fossil fuel power industry. Plants must consider operating philosophy, plant layout, and type of firing before they ultimately select a system. They do not need a standard that limits the complexity or scope of the steam temperature control system design they might want to implement, but they do need one that establishes a minimum of control.
The ISA standard on steam temperature controls, ANSI/ISA77.44.01-2007, Fossil Fuel Power Plant -- Steam Temperature Controls, is up for reaffirmation this year to maintain its American National Standards Institute (ANSI) accreditation. The standard is part of a series resulting from the efforts of the ISA77 committee on fossil power plant standards, especially subcommittee ISA77.40 on boiler controls. Those using the standard should use it in conjunction with the other ISA77 series of standards for safe, reliable, and efficient design, construction, operation, and maintenance of the power plant. It is not the intent of the standard to establish any procedures or practices that are contrary to any other standard in the series.
The purpose of the standard is to establish the minimum requirements for the functional design specification of steam temperature control systems for drum type and once-through type fossil fuel power plant boilers.
The scope of the standard address the major steam temperature control subsystems in boilers with steaming capacities of 200,000 lb/hr (25 kg/s) or greater. These subsystems include but are not limited to superheat temperature control and reheat temperature control. Specifically excluded from consideration are controls associated with fluidized-bed, stoker-fired furnace combustion units and mud drum desuperheaters.
The committee ballot has passed to reaffirm the standard, and the committee expects publication to be complete by May 2012.
If you have any questions about the standard or wish to serve on the ISA77 Fossil Fuel Power Plant standards committee, please contact ISA Standards Administrator Ellen Fussell Policastro at efussell@isa.org.