Methods and systems for cleaning heat exchange surfaces of a heat exchange system

Abstract

Means for obtaining accurate knowledge of location and amount of fouling inside a heat exchange system, such as a boiler of a power plant, are provided. According to the invention this knowledge can be used to optimize cleaning of a heat exchange system. The system of the invention comprises: Means for measuring particles in the exhaust gas stream of the heat exchange system. These particles are at least partly released when cleaning a certain part of the heat exchange surface of the heat exchange system. Means for creating information of the fouling in an electronic memory by linking together coordinates of the part of the heat exchange surface being cleaned and the measurement data created during the cleaning of said part.

1 . Method of air/fuel control of burners in a pulverized coal firing boiler which comprises controlling input parameters of the boiler on the basis of a measurement of a flow of particles in burner ducts. 
     
     
         2 . The method according to  claim 1 , wherein the input parameters controlled on the basis of the measurement comprise at least one of the group of mill parameters, primary airflow of the burners and secondary airflow of the burners. 
     
     
         3 . The method according to  claim 2 , wherein the input parameters controlled on the basis of the measurement comprise secondary airflow of the burners. 
     
     
         4 . The method according to  claim 1 , wherein the measurement comprises measuring ECT signals. 
     
     
         5 . The method according to  claim 4 , wherein the controlling is based on spectral analysis of the ECT signals. 
     
     
         6 . The method according to  claim 5 , wherein the controlling is based on a high frequency (HF) component of the ECT signals, reflecting the state of the flame in the boiler. 
     
     
         7 . The method according to  claim 4 , wherein the controlling is based on ECT signals obtained by several antennas so as to measure a particle distribution in the burner ducts. 
     
     
         8 . The method according to  claim 4 , wherein the controlling is based on a correlation analysis between the input parameters, the ECT signals, and output parameters of the boiler including readings of at least one emission metering device of the boiler. 
     
     
         9 . The method according to  claim 5 , wherein the controlling is based on a correlation analysis between the input parameters, high frequency (HF) bands of the ECT signals, and output parameters of the boiler including readings of at least one emission metering device of the boiler. 
     
     
         10 . The method according to  claim 8 , wherein the size of a correlation matrix obtained in the correlation analysis is reduced by eliminating ECT signals having a high correlation with another ECT signal. 
     
     
         11 . The method according to  claim 8 , wherein the controlling is based on fuzzy modelling of the dependencies between the ECT signals and the output parameters. 
     
     
         12 . The method according to  claim 9 , wherein the controlling is based on fuzzy modelling of the dependencies between the high frequency (HF) bands of ECT signals and the output parameters.