This invention discloses systems and methods for control of a gas turbine or a gas turbine generator, where the gas turbine is connected to a dryer vessel in which gas turbine exhaust gases are used to heat treat a material in the dryer vessel. The control system comprises one or more sensors for temperature, moisture and/or flow rate in the dryer vessel and/or of the material inside, entering and/or exiting the dryer vessel and a controller responsive to the sensor for controlling the fuel and/or air flow into the gas turbine. This control system and method enables providing the appropriate heat output from the gas turbine to meet the process heat required for the desired material treatment. Optionally, the gas turbine can be a liquid fuel turbine engine, or a reciprocating engine can be substituted for the turbine engine.