Coal combusting boiler

Abstract

A coal consuming boiler is provided with a combustion chamber having a divider of refractory material formed therein which separates the combustion chamber into primary and secondary combustion areas. A coal burner head for combusting coal is located in the primary combustion area. Primary combustion air is directed to the burner head while additional secondary combustion air is directed to the secondary combustion area to ensure that all combustible gases are thoroughly burnt up prior to the exhaust exiting the combustion chamber through a heat exchanger of the boiler. Exhaust tubes extending through the heat exchanger are configured in a horizontal double-pass configuration. A cleaner is provided in the form of nozzles associated with each of the exhaust tubes which are arranged to direct a high pressure flow of gas periodically therethrough for removing collected ash from the exhaust tubes to increase efficiency of the heat exchanger.

1 . A boiler comprising: 
 a coal burner head for combusting coal;    a combustion chamber above the coal burner head;    a heat exchanger for exchanging heat between exhaust exiting the combustion chamber and a heat exchanger fluid circulated through the heat exchanger;    a divider formed of refractory material separating the combustion chamber into a primary combustion area on a first side of the divider and a secondary combustion area on a second side of the divider; and    air supply means for directing primary combustion air to the primary combustion area on the first side of the divider and for directing secondary combustion air to the secondary combustion area on the second side of the divider.    
   
   
       2 . The boiler according to  claim 1  wherein the divider includes through holes formed therein for passage of exhaust gases therethrough.  
   
   
       3 . The boiler according to  claim 2  wherein the divider fully spans interior walls of the chamber so that the exhaust can only pass through the holes in the divider.  
   
   
       4 . The boiler according to  claim 1  wherein the divider extends generally horizontally, locating the secondary combustion area thereabove and the primary combustion area therebelow.  
   
   
       5 . The boiler according to  claim 1  wherein the divider is formed of a material including alumina and silica.  
   
   
       6 . The boiler according to  claim 1  wherein the secondary combustion air is introduced into the secondary combustion area directly adjacent the divider.  
   
   
       7 . The boiler according to  claim 1  wherein the primary air is introduced into the primary combustion area adjacent the burner head.  
   
   
       8 . The boiler according to  claim 1  wherein the primary and secondary combustion air are introduced under pressure.  
   
   
       9 . The boiler according to  claim 1  wherein the heat exchanger includes horizontal exhaust tubes for directing the exhaust therethrough.  
   
   
       10 . The boiler according to  claim 9  wherein the exhaust tubes are oriented in a double-pass configuration through the heat exchanger.  
   
   
       11 . The boiler according to  claim 10  wherein the exhaust tubes include first exhaust tubes and second exhaust tubes oriented parallel to one another and which are commonly joined at one end by an exhaust manifold.  
   
   
       12 . The boiler according to  claim 1  wherein the heat exchanger includes a plurality of exhaust tubes for directing exhaust therethrough and wherein there is provided an exhaust tube cleaner comprising a nozzle associated with each exhaust tube which is arranged for directing a high pressure flow of gas therethrough for removing collected ash when activated.  
   
   
       13 . The boiler according to  claim 1  wherein coal is augered up through a center of the burner head from below.  
   
   
       14 . The boiler according to  claim 1  wherein the burner head is supported above an ash collection hopper including an auger for removal of ash therefrom.  
   
   
       15 . The boiler according to  claim 1  wherein the heat exchanger includes a pressure relief tank coupled in communication therewith.  
   
   
       16 . A boiler comprising: 
 a coal burner head for combusting coal;    a combustion chamber above the coal burner head;    air supply means for directing combustion air to the combustion chamber;    horizontal exhaust tubes communicating with the combustion chamber for directing exhaust gases therethrough;    a heat exchanger for exchanging heat between the exhaust tubes and a heat exchanger fluid circulated through the heat exchanger; and    an exhaust tube cleaner comprising a nozzle associated with each exhaust tube which is arranged for directing a high pressure flow of gas therethrough for removing collected ash from the exhaust tubes.    
   
   
       17 . The boiler according to  claim 16  wherein a manifold is coupled in communication with all of the nozzles for supplying air under pressure to all of the nozzles when air under pressure is introduced therein.  
   
   
       18 . The boiler according to  claim 16  wherein the exhaust tubes comprise first exhaust tubes and second exhaust tubes communicating in series with one another through an exhaust manifold and wherein all of the nozzles are located at the exhaust manifold.  
   
   
       19 . The boiler according to  claim 16  wherein the nozzles are oriented in at least some of the exhaust tubes to direct the flow of air under pressure towards the burner head.  
   
   
       20 . The boiler according to  claim 16  wherein the exhaust tube cleaner is operated automatically at periodic intervals to periodically direct a high pressure flow of gas through the exhaust tubes.