Boiler combustor side blockage detection system and method

Abstract

Disclosed is a boiler blockage detection system and method utilizing inputs from a pressure sensing elements. A logic circuit may determine a boiler firing rate based on an input signal from the combustion controller. An indication of the exhaust pressure level and an indication of the inlet pressure level are received. A pressure differential between the exhaust pressure level and the inlet pressure level is determined. Alternatively, a pressure differential transmitter may determine the pressure differential. The determined pressure differential is compared to a predetermined pressure level differential threshold. The predetermined pressure level differential threshold is dependent on the determined firing rate. Based on a result of the comparison of the determined pressure differential to the predetermined pressure level differential threshold, it may be determined that there is a blockage of an intake or an exhaust of the boiler. In response to the blockage determination, an interrupt signal is output.

What is claimed: 
     
         1 . A system for detecting blockage of air entering a boiler or exhaust gas exiting the boiler, the system comprising:
 an exhaust pressure sensing element configured to be coupled to the boiler and to detect an exhaust pressure level of exhaust gas exiting the boiler;   an inlet pressure sensing element configured to be coupled to the boiler and to detect an inlet pressure level of air entering the boiler; and   a logic circuit coupled to the exhaust pressure sensing element and the inlet pressure sensing element and configured to be coupled to a combustion controller of the boiler, the logic circuit being configured to:
 determine a firing rate of the boiler based on an input signal received from the combustion controller; 
 determine a pressure differential between the exhaust pressure level detected by the exhaust pressure sensing element and the inlet pressure level detected the inlet pressure sensing element; 
 compare the determined pressure differential to a predetermined pressure level differential threshold, the predetermined pressure level differential threshold being dependent on the firing rate; 
 determine whether a boiler duct is at least partially blocked based on a result of the comparison of the determined pressure differential to the predetermined pressure level differential threshold; and 
 based on a determination that the boiler duct is at least partially blocked, output an interrupt signal; and 
   a relay coupled to the logic circuit, the relay configured to:
 receive the interrupt signal from the logic circuit, and 
 pupon receipt of the interrupt signal, interrupt power to the combustion controller to shut down a combustion process of the boiler. 
   
     
     
         2 . The system of  claim 1 , wherein the logic circuit is further configured to output an alarm signal for generating an audible and/or visual indication indicating one or more of: an at least partially blocked inlet air duct, an at least partially blocked exhaust duct, an at least partial fouling of a heat exchanger component, an at least partial fouling of a combustor component, an improper sizing of a duct, or an improper sizing of a duct termination. 
     
     
         3 . The system of  claim 1 , wherein the inlet pressure sensing element is coupled to an inlet duct of the boiler. 
     
     
         4 . The system of  claim 1 , wherein the exhaust pressure sensing element is coupled to an exhaust duct of the boiler. 
     
     
         5 . The system of  claim 1 , wherein an additional parameter is used to adjust the predetermined pressure level differential threshold at a given firing rate. 
     
     
         6 . The system of  claim 1 , further comprising:
 a memory, coupled to the logic circuit, said memory storing the predetermine pressure level differential threshold and program code, wherein the logic circuit is configured to perform functions upon execution of the program code stored in the memory.   
     
     
         7 . A system for detecting blockage of air entering a boiler or exhaust gas exiting the boiler, the system comprising:
 a differential pressure transmitter configured to:
 detect a differential pressure across a boiler, and 
 output a pressure differential signal indicating the detected differential pressure across the boiler; 
   a logic circuit coupled to the differential pressure transmitter, the logic circuit being configured to:
 receive the pressure differential signal from the differential pressure transmitter; 
 compare the pressure differential signal to a predetermined pressure level differential threshold; 
 determine, based upon a result of the comparison of the pressure differential signal to the predetermined pressure level differential threshold, whether there is at least a partial blockage of a duct of the boiler; and 
 in response to a determination of the at least partial blockage of a boiler duct, output a interrupt signal; and 
   a relay coupled to the logic circuit, the relay configured to:
 in response to receiving the interrupt signal from the logic circuit, halt a combustion process of the boiler. 
   
     
     
         8 . The system of  claim 7 , wherein the logic circuit is further configured to:
 determine a boiler firing rate based on an input signal from a combustion controller, wherein the pressure level differential threshold is dependent on the determined boiler firing rate.   
     
     
         9 . The system of  claim 7 , wherein the pressure differential signal indicates a negative pressure when an inlet duct is blocked. 
     
     
         10 . The system of  claim 7 , wherein the pressure differential signal indicates a positive pressure when the exhaust duct is blocked. 
     
     
         11 . The system of  claim 7 , wherein the comparison between measured system pressure differential and the pre-determined pressure differential is performed via analog circuitry. 
     
     
         12 . The system of  claim 7 , wherein more than one differential pressure transmitter is utilized as a means to confirm proper operation of the more than one differential pressure transmitters and logic circuit. 
     
     
         13 . The system of  claim 7 , wherein a second system variable is used to adjust the allowable system pressure drop at a given firing rate. 
     
     
         14 . A method for detecting a blockage in a boiler system, the method comprising steps of:
 determining, by a logic circuit, a firing rate of the boiler system based on an input signal received from a combustion controller of the boiler system;   receiving an indication of exhaust pressure level;   receiving an indication of inlet pressure level;   determining a pressure differential between the exhaust pressure level and the inlet pressure level;   comparing the determined pressure differential to a predetermined pressure level differential threshold, wherein the threshold is dependent on the determined firing rate;   determining there is at least a partial blockage of an intake duct or an exhaust duct of the boiler based on a result of the comparison of the determined pressure differential to the predetermined pressure level differential threshold; and   in response to the blockage determination, outputting an interrupt signal.   
     
     
         15 . The method of  claim 14 , further comprising:
 detecting an exhaust pressure by an exhaust pressure sensing element;   outputting the exhaust pressure indication by the exhaust pressure sensing element;   detecting an inlet pressure indication by an inlet pressure sensing element; and   outputting the inlet pressure indication by the inlet pressure sensing element.   
     
     
         16 . The method of  claim 14 , further comprising:
 receiving the exhaust pressure indication via a port coupled to an exhaust outlet tube; and   receiving the inlet pressure indication via a port coupled to an inlet tube.   
     
     
         17 . The method of  claim 14 , further comprising:
 forwarding the outputted interrupt signal to a relay coupled to the combustion controller.   
     
     
         18 . The method of  claim 14 , further comprising:
 determining the predetermined differential pressure threshold by using the determined firing rate and additional parameters, wherein the additional parameters are received from the combustion controller.   
     
     
         19 . The method of  claim 14 , further comprising:
 based on the result of the comparison, identifying a combustion blower of the boiler as operating improperly.   
     
     
         20 . A boiler system configured for detecting blockage of air entering the boiler system or exhaust gas exiting the boiler system, the boiler system comprising: a boiler having a combustion controller and a boiler duct;
 an exhaust pressure sensing element coupled to the boiler and configured to detect an exhaust pressure level of exhaust gas exiting the boiler;   an inlet pressure sensing element coupled to the boiler and configured to detect an inlet pressure level of air entering the boiler; and   a logic circuit coupled to the exhaust pressure sensing element and the inlet pressure sensing element and the combustion controller, the logic circuit being configured to:
 determine a firing rate of the boiler based on an input signal from the combustion controller; 
 determine a pressure differential between the exhaust pressure level detected by the exhaust pressure sensing element and the inlet pressure level detected the inlet pressure sensing element; 
 compare the determined pressure differential to a predetermined pressure level differential threshold, the threshold being dependent on the firing rate; 
 determine whether the boiler duct is at least partially blocked based on a result of the comparison of the determined pressure differential to the predetermined pressure level differential threshold; and 
 based on a determination that the boiler duct is at least partially blocked, output an interrupt signal; and 
 a relay coupled to the logic circuit, the relay configured to: 
 receive the interrupt signal from the logic circuit, and in response to receiving the interrupt signal, interrupt power to the combustion controller to shut down the combustion process of the boiler system. 
   
     
     
         21 . The boiler system of  claim 20 , wherein the inlet pressure sensing element is coupled to an inlet duct of the boiler. 
     
     
         22 . The boiler system of  claim 20 , wherein the exhaust pressure sensing element is coupled to an exhaust duct of the boiler. 
     
     
         23 . The boiler system of  claim 20 , wherein an additional parameter is used to adjust the predetermined pressure level differential threshold at a given firing rate. 
     
     
         24 . The system of  claim 20 , wherein the determined pressure differential indicates a negative pressure when an inlet duct is blocked. 
     
     
         25 . The system of  claim 20 , wherein the determined pressure differential indicates a positive pressure when the exhaust duct is blocked. 
     
     
         26 . The boiler system of  claim 20 , further comprising:
 a memory, coupled to the logic circuit, said memory storing the predetermine pressure level differential threshold and program code, wherein the logic circuit is configured to perform functions upon execution of the program code stored in the memory.   
     
     
         27 . The boiler system of  claim 20 , further comprising:
 the combustion controller, wherein the combustion controller is configured to monitor and control the combustion process of the boiler system.