Boiler

Abstract

The boiler is provided with: a boiler body in which the water level inside water pipes when combustion is stopped is lower than the upper ends of the water pipes; external water level detection means which communicates with upper and lower headers and detects a boiler body external water level; control means which controls the water supply means so as to lower the water level inside the boiler body when the water level detected by the external water level detection means reaches a first set water level; and header water level detection means which detects a water level existing inside the upper header by boiler water being pushed up by air bubbles. The control means controls the water supply means so as to lower the water level inside the boiler body when the water level detected by the header water level detection means reaches a second set water level.

1 . A boiler comprising:
 a boiler body including an upper header, a lower header, and a large number of water pipes to be heated by a burner, the water pipes connecting the upper header and the lower header to each other, wherein the water level in the water pipes when combustion by the burner is stopped is lower than the upper ends of the water pipes;   external water level detection means placed outside the boiler body, the external water level detection means communicating with an internal space of the upper header and an internal space of the lower header through communication pipes and detecting a boiler body external water level;   water supply means supplying boiler feed water into the boiler body;   control means controlling the operation of the water supply means so as to lower the boiler body water level when the water level detected by the external water level detection means reaches a first set water level; and   header water level detection means detecting a water level existing inside the upper header by boiler water inside the water pipes being pushed up by air bubbles generated by boiling of the boiler water, wherein   the control means controls the operation of the water supply means so as to lower the boiler body water level when the water level detected by the header water level detection means reaches a second set water level.   
     
     
         2 . The boiler according to  claim 1 , wherein the header water level detection means includes:
 a water level control chamber having communication holes respectively communicating with an upper part and a lower part of the upper header; and   an electrode detecting the second set water level inside the water level control chamber.   
     
     
         3 . The boiler according to  claim 2 , wherein the control means controls the water supply means so as to lower the boiler body water level when the external water level detection means detects the first set water level or the header water level detection means detects the second set water level. 
     
     
         4 . The boiler according to  claim 3 , wherein the control means controls the water supply means so as to raise the boiler body water level when the external water level detection means stops detecting the first set water level and the header water level detection means stops detecting the second set water level. 
     
     
         5 . The boiler according to  claim 4 , wherein
 the external water level detection means includes: a water level control chamber communicating with the upper header and the lower header; a first electrode detecting the first set water level inside the water level control chamber; and a second electrode detecting a third set water level lower than the first set water level inside the water level control chamber, and   the control means controls the water supply means so as to raise the boiler body water level when the second electrode stops detecting the third set water level.   
     
     
         6 . The boiler according to  claim 2 , wherein the water level control chamber of the header water level detection means is placed inside the upper header and communicates with the upper part and the lower part of the upper header through the communication holes. 
     
     
         7 . The boiler according to  claim 2 , wherein the water level control chamber of the header water level detection means is placed outside the upper header, and the upper part and the lower part of the upper header are connected to the respective communication holes through communication pipes. 
     
     
         8 . The boiler according to  claim 2 , wherein
 the header water level detection means includes an electrode detecting a plurality of different second set water levels corresponding to different combustion amounts, and   the control means controls the operation of the water supply means so as to lower the boiler body water level when the second set water levels corresponding to the different combustion amounts are detected.   
     
     
         9 . The boiler according to  claim 2 , further comprising a downcast pipe allowing the lower part of the upper header and the lower header to communicate with each other. 
     
     
         10 . The boiler according to  claim 2 , wherein
 the control means controls the water supply means so as to lower the boiler body water level when the external water level detection means detects the first set water level in a case where a combustion time of the burner does not reach a combustion time threshold after discharging boiler water existing inside the boiler body to the outside, and controls the operation of the water supply means so as to lower the boiler body water level when the header water level detection means detects the second set water level in a case where the combustion time has reached the combustion time threshold.   
     
     
         11 . The boiler according to  claim 2 , further comprising electric conductivity measuring means measuring the electric conductivity of boiler water inside the boiler body, wherein
 the control means controls the water supply means so as to lower the boiler body water level when the external water level detection means detects the first set water level in a case where the electric conductivity of boiler water measured by the electric conductivity measuring means does not reach an electric conductivity threshold, and controls the operation of the water supply means so as to lower the boiler body water level when the header water level detection means detects the second set water level in a case where the electric conductivity of boiler water measured by the electric conductivity measuring means has reached the electric conductivity threshold.   
     
     
         12 . A boiler comprising:
 a boiler body including an upper header, a lower header, and a large number of water pipes to be heated by a burner, the water pipes connecting the upper header and the lower header to each other, wherein the water level in the water pipes when combustion by the burner is stopped is lower than the upper ends of the water pipes;   water supply means supplying boiler feed water into the boiler body;   control means controlling the operation of the water supply means;   external water level detection means placed outside the boiler body, the external water level detection means communicating with an internal space of the upper header and an internal space of the lower header through communication pipes and detecting a boiler body external water level; and   header water level detection means detecting a water level existing inside the upper header by boiler water inside the water pipes being pushed up by air bubbles generated by boiling of the boiler water, wherein   the control means controls the operation of the water supply means so as to lower the boiler body water level when the water level detected by the external water level detection means reaches a low concentration set water level or a set water level lower than the low concentration set water level, and controls the operation of the water supply means so as to lower the boiler body water level when the water level detected by the header water level detection means reaches a high concentration set water level.