Method of determining a local temperature anomaly in a fluidized bed of a combustion boiler, method of calibrating a numerical model of a fluidized bed of a combustion boiler, method of estimating a risk of fluidized bed combustion boiler bed sintering, method of controlling a fluidized bed boiler, as well as a combustion boiler

A method of determining a local temperature anomaly in a fluidized bed of a combustion boiler system that comprises a furnace having a boiler grid that is equipped with at least three temperature sensors that together define a measurement grid where each temperature sensor represents a measurement point (Pi, i=1, . . . , n), the method comprising:

• monitoring current operation data of the boiler, including the measured bed temperature (TMi;
• i=1, . . . , N) at each measurement point (Pi, i=1, . . . , N) and at least primary air flow (x1), fuel moisture (x2), main steam flow (x3), flue gas oxygen (x4) and bed pressure (x5);
• is monitored;
• preparing and calibrating a numerical model between boiler operation data, namely, at least primary air flow (x1), fuel moisture (x2), main steam flow (x3), flue gas oxygen (x4), and bed pressure (x5), and the measured bed temperatures (TMi;
• i=1, . . . , N) at each measurement point (Pi, i=1, . . . , N);
• computing bed temperatures for the measurement points (Pi, i=1, . . . , n) using the numerical model, to obtain computed bed temperatures (TCi;
• i=1, . . . , n) under normal operation conditions of the combustion boiler system (10);
• and
• comparing the measured bed temperatures (TMi) with the computed bed temperatures (TCi) for at least some of the measurement points (Pi, i=1, . . . , n), and, if an anomaly threshold is exceeded, determining that local temperature anomaly is present.

A method of estimating a risk of fluidized bed combustion boiler bed sintering, wherein the combustion boiler system comprises a furnace having a boiler grid that is equipped with at least three temperature sensors that together define a measurement grid where each temperature sensor represents a measurement point (Pi, i=1, . . . , n), the method comprising

• measuring current operation data of the boiler, namely, the measured bed temperature (TMi;
• i=1, . . . , N), is at each measurement point (Pi, i=1, . . . , n);
• computing, based on the current operation data of the boiler:
• (i) an average of the measured bed temperatures;
• (ii) a standard deviation of measured bed temperature;
• (iii) a difference between measured bed maximum temperature and measured bed minimum temperature;
• and
• (iv) s spread (xspread, i=xi−x˜xi) for the measured bed temperatures;
• and
• (v) using the computation results from (i), (ii), (iii) and (iv) to prepare a bed sintering index.

A combustion boiler system that is configured to carry out a method of determining a local temperature anomaly in a fluidized bed of a combustion boiler system that comprises a furnace having a boiler grid that is equipped with at least three temperature sensors that together define a measurement grid where each temperature sensor represents a measurement point (Pi, i=1, . . . , n), the method comprising:

• monitoring current operation data of the boiler, including the measured bed temperature (TMi;
• i=1, . . . , N) at each measurement point (Pi, i=1, . . . , N) and at least primary air flow (x1), fuel moisture (x2), main steam flow (x3), flue gas oxygen (x4), and bed pressure (x5);
• preparing and calibrating a numerical model (f) between boiler operation data, namely, at least primary air flow (x1), fuel moisture (x2), main steam flow (x3), flue gas oxygen (x4), and bed pressure (x5), and the measured bed temperatures (TMi;
• i=1, . . . , N) at each measurement point (Pi, i=1, . . . , N);
• computing bed temperatures for the measurement points (Pi, i=1, . . . , n) using the numerical model, to obtain computed bed temperatures (TCi;
• i=1, . . . , n) under normal operation conditions of the combustion boiler system (10);
• and
• comparing the measured bed temperatures (TMi) with the computed bed temperatures (TCi) for at least some of the measurement points (Pi, i=1, . . . , n), and, if an anomaly threshold is exceeded, determining that local temperature anomaly is present.

A method of determining a local temperature anomaly in a fluidized bed of a combustion boiler system that comprises a furnace having a boiler grid that is equipped with at least three temperature sensors that together define a measurement grid where each temperature sensor represents a measurement point (Pi, i=1, . . . , n), the method comprising:

• estimating a risk of fluidized bed combustion boiler bed sintering;
• measuring current operation data of the boiler, namely, the measured bed temperature (TMi;
• i=1, . . . , N), at each measurement point (Pi, i=1, . . . , n);
• computing, based on the current operation data of the boiler:
• (i) an average of the measured bed temperatures;
• (ii) a standard deviation of measured bed temperature;
• (iii) a difference between measured bed maximum temperature and measured bed minimum temperature;
• and
• (iv) a spread (xspread, i=xi−x˜xi) for the measured bed temperatures;
• and
• using the computation results from (i), (ii), (iii) and (iv) to prepare a bed sintering index.