Monitoring a degradation of steam generator boiler tubes

Abstract

An on-line degradation monitoring is disclosed for boiler tubes in large combustion facilities, in particular waste incineration plants. The degradation of the tubes, for example corrosion or caking, is determined in a more or less continuous manner while the combustion facility is operating, and thus not restricted to optical inspection during downtimes. A rate or accumulated degradation can be related to an operation mode of the facility. Appropriate degradation sensors are arranged outside of a the flue gas tract where the boiler tubes are exposed to noxious flue gases from the combustion process, and receive ultrasonic signals from a space or volume within the flue gas tract. A test tube is provided exclusively for the monitoring of the degradation progress and introduced into the flue gas tract at a particularly corrosion-exposed location.

1 . A method of monitoring a degradation of steam generator boiler tubes in large combustion facilities, wherein the boiler tubes are arranged in a flue gas tract and exposed to flue gases from a combustion process, wherein the method comprises, while steam is being generated, receiving and evaluating signals indicative of a degradation of the boiler tubes from within the flue gas tract.  
   
   
       2 . The method according to  claim 1 , wherein it comprises receiving the signals by degradation sensors located external to the flue gas tract.  
   
   
       3 . The method according to  claim 1 , wherein it comprises receiving ultrasonic signals by ultrasonic transducers.  
   
   
       4 . The method according to  claim 1 , wherein it comprises receiving the signals from a test tube arranged in the flue gas tract and being exposed to the flue gases.  
   
   
       5 . The method according to  claim 1 , wherein it further comprises relating the monitored degradation to a plant operation mode, and adapting the latter if necessary.  
   
   
       6 . A system for monitoring a degradation of steam generator boiler tubes in large combustion facilities, wherein the boiler tubes are arranged in a flue gas tract and exposed to flue gases from a combustion process, wherein the system comprises degradation sensors for receiving and evaluating, while steam is being generated, signals indicative of a degradation of the boiler tubes from within the flue gas tract.  
   
   
       7 . The system according to  claim 6 , wherein the degradation sensors are arranged outside of the flue gas tract.  
   
   
       8 . The system according to  claim 6 , wherein the degradation sensors are ultrasonic transducers.  
   
   
       9 . The system according to  claim 6 , wherein it comprises a separate test tube arranged in the flue gas tract and being exposed to the flue gases, wherein the degradation sensors receive signals from the test tube.  
   
   
       10 . The system according to  claim 6 , wherein the combustion facility is a waste incineration plant.