A method for controlling a combustion process in a gas turbine wherein a combustion chamber, a control device storing a calculation model of the combustion process, and an exhaust air measurement device are used. A permissible limit value for nitrogen oxides and for carbon monoxide as pollutants is set. The actual value of at least one of the two pollutants is measured continuously in the exhaust air. When a signal to reduce the power of the gas turbine to a lowest possible value is given, then a minimum fuel supply at which the limit values are complied with is calculated. The fuel supply is then reduced either until the calculated minimum fuel supply is reached or until the continuously measured proportion of the pollutant reaches the permissible limit value.

Emissions of NO.sub.X and/or CO are reduced at the stack by systems and methods wherein a primary fuel is thoroughly mixed with a specific range of excess combustion air. The primary fuel-air mixture is then discharged and anchored within a combustion chamber of a burner. Further, the systems and methods provide for dynamically controlling NO.sub.X content in emissions from a furnace by adjusting the flow of primary fuel and of a secondary stage fuel, and in some cases controlling the amount or placement of combustion air into the furnace.

Systems and methods operate to infer a fuel composition in a combustion system. The fuel composition may be inferred by receiving measured operating parameters including one or more of fuel data defining fuel characteristics used in combustion within a heater of the combustion system, emissions data defining emission gasses exiting the heater, airflow data defining ambient air being supplied to the heater and airflow rate of the air within the heater. One or more relationships within the measured operating parameters may be identified that result in a list of potential fuel compositions. One of the potential fuel compositions from the list may be selected having sufficient likelihood of resulting in the measured operating parameters as an inferred fuel composition. The output the inferred fuel composition to a heater controller of the combustion system and used for automatic control thereof.

Combustion heater control systems and methods that include dynamic safety settings. Current operating parameters of the combustion heater are sensed at a plurality of time intervals and converted into a time-varying signal. The time-varying signal is compared to a burner stability envelope indicating when a burner is likely to enter an unstable state. The unstable state may include huffing, flashback, and/or liftoff. When the burner is likely to enter an unstable state, the combustion heater is controlled to prevent the unstable state.

A fluid heating system including a burner unit is operated based on feedback control loops. The fluid heating system comprises a burner unit configured to heat a fluid, a sensor configured to sense a characteristic of the appliance, and a controller coupled to the burner unit and the sensor. The controller includes an electronic processor and a memory. The controller is configured to receive a first signal corresponding to the characteristic from the sensor, determine, based on the first signal, a first feedback loop control, control combustion of the burner unit based on the first feedback loop control, determine, based on the first feedback loop control, a second feedback loop control, and control combustion of the burner unit based on the second feedback loop control.

Systems and methods include a computer-implemented method for monitoring emissions in real time. Flaring emissions are determined in real time for a flare stack based on: 1) a flaring volume in conjunction with heat and material balances of systems that discharge to a flare system, and 2) a composition of each relief source that discharges to the flare system. A molar balance around the flare stack is performed in real time using the flaring emissions to determine the emissions.

Emissions of NO.sub.X and/or CO are reduced at the stack by systems and methods wherein a primary fuel is thoroughly mixed with a specific range of excess combustion air. The primary fuel-air mixture is then discharged and anchored within a combustion chamber of a burner. Further, the systems and methods provide for dynamically controlling NO.sub.X content in emissions from a furnace by adjusting the flow of primary fuel and of a secondary stage fuel, and in some cases controlling the amount or placement of combustion air into the furnace.

A method for reducing combustion temperature and/or thermal radiation within a lime kiln of a pulp production plant, which kiln is a rotary kiln having a kiln tube (1) internally covered with refractory tiles (13) and having a burner (2) supplied by fuel for heating of the rotary kiln by a flame (3). The effects are achieved by supplying calcium carbonate containing particles to the flame (3) and/or to surrounding area around the flame (3). The particles are supplied into the rotary kiln by at least one lance (9) to the upper part of the flame (3). Calcium oxide containing particles may be supplied to the rotary kiln to areas surrounding the flame (3) for reducing the thermal radiation to an area over the flame (3) and/or to the area at the side of the flame (3), where the refractory tiles (13) of the kiln are rotating downwards.

Boiler systems and associated control systems, methods for operating same, are described herein. In one example embodiment, a boiler system includes a furnace, an exhaust passage, an air passage, a FGR passage, a flue gas valve that is adjustable by way of a first actuator, a NO.sub.X gas sensor, an oxygen gas sensor, and an additional valve that is adjustable by way of a second actuator. Further, the boiler system includes at least one processing device coupled to the NO.sub.X gas sensor, the oxygen gas sensor, the first actuator and the second actuator. The at least one processing device is configured to generate control signals that are provided to the first actuator and second actuator, and also configured to generate correction factors by way of a calibration process and to utilize one or more of the correction factors in determining one or more of the control signals.

A water heater includes a water tank having an inlet and an outlet, and a flue extending through the tank. A nozzle is positioned near a first end of the flue, arranged so as to emit a fuel stream into the flue, and a flame holder is located within the flue in a position to receive the fuel stream and to hold a flame entirely within the flue. A controller variably controls a flow of fuel to the nozzle according to a temperature of water in the tank.