Firebox boiler with reduced temperature variation

Abstract

A boiler firebox comprises arcuate front and rear end water walls connected respectively to front and rear ends of right and left side water walls. The end walls curve outward from respective ends of one side water wall and then inward to the respective ends of the other side water wall. The end and side water walls enclose a combustion chamber, and are connected at ends thereof such that water can circulate through the end and side water walls. Water input ports can be provided in water walls on opposite sides or ends of the firebox such that the flow of circulating water can be divided with about half entering the water wall on one side or end of the boiler and the other half entering on an opposite side or end, thereby reducing temperature variations in water near the input ports compared to boilers with a single input port.

1 . A boiler firebox comprising:
 right and left side water walls;   front and rear end water walls connected to corresponding front and rear ends of the right and left side water walls to enclose a combustion chamber, and such that water can circulate around the combustion chamber through the end and side water walls; and   wherein at least one of the front and rear end water walls is arcuate, curving outward from the a corresponding end of the right side water wall and then inward to a corresponding end of the left side water wall.   
   
   
       2 . The firebox of  claim 1  wherein the at least one arcuate end water walls is substantially vertical. 
   
   
       3 . The firebox of  claim 2  wherein the at least one arcuate end water wall is semi-circular. 
   
   
       4 . The firebox of  claim 1  wherein the end and side water walls each comprise an inner wall and an outer wall, and wherein inner walls of the end and side water walls are connected at ends thereof, and outer walls of the end and side water walls are connected at ends thereof such that a water chamber is formed between the inner and outer walls of the end and side water walls. 
   
   
       5 . The firebox of  claim 1  further comprising a first water input port adjacent to a bottom of a central portion of a first water wall, and a second water input port adjacent to a bottom of a central portion of an opposite second water wall. 
   
   
       6 . The firebox of  claim 5  further comprising a first conduit connected to the first water input port at one end thereof and to a first port of a T-connector at an opposite end thereof, and a second conduit connected to the second water input port at one end thereof and to a second port of a T-connector at an opposite end thereof, such that a circulating conduit can be connected to a third port of the T-connector such that circulating water can enter the water walls through the first and second water input ports. 
   
   
       7 . The firebox of  claim 6  wherein the first and second water walls are end water walls, and wherein circulating water can be connected to enter the water walls at opposite ends of the firebox. 
   
   
       8 . The firebox of  claim 6  wherein the first and second water walls are side water walls, and wherein circulating water can be connected to enter the water walls at opposite sides of the firebox. 
   
   
       9 . A boiler apparatus comprising:
 a firebox according to  claim 4 ;   a boiler shell mounted above a front portion of the firebox such that the boiler shell is in fluid communication with the side and end water walls and such that the boiler shell forms a top wall of the front portion of the firebox, and a lower rear face of boiler shell is exposed to a rear portion of the firebox;   a lower transition plate joining a top end of the inner wall of the rear water wall to a top of the lower rear face of the boiler shell to form a top wall of the rear portion of the firebox;   an upper transition plate joining a top end of the outer wall of the rear water wall to the boiler shell above the lower transition plate, the upper and lower transition plates forming a channel to allow water to flow between the rear water wall and the boiler shell;   a plurality of fire-tubes extending substantially horizontally from the lower rear face through the boiler shell to a front face of the boiler shell;   wherein the lower transition plate is curved such that material deposited on a top surface of the lower transition plate tends to slide off the top surface of the lower transition plate and fall to a bottom of the water chamber.   
   
   
       10 . The apparatus of  claim 9  further comprising a first water input port adjacent to a bottom of a central portion of a first water wall and connected to a first port of a T-connector, and a second water input port adjacent to a bottom of a central portion of an opposite second water wall and connected to a second port of a T-connector, and a circulating conduit connected to a third port of the T-connector such that circulating water can enter the water chamber through the first and second water input ports. 
   
   
       11 . A boiler comprising:
 a firebox comprising right and left side water walls and front and rear end water walls enclosing a combustion chamber, and connected at ends thereof such that water can circulate through the end and side water walls;   a boiler shell mounted above the firebox such that the boiler shell is in fluid communication with the side and end water walls and such that water in the boiler shell is heated by a burner in the firebox;   an output port operatively connected to the boiler shell;   a first water input port adjacent to a bottom of a central portion of a first water wall and a second water input port adjacent to a bottom of a central portion of an opposite second water wall;   wherein circulating water flows out of the boiler through the output port, through a distribution network and back into the boiler through the first and second water input ports.   
   
   
       12 . The boiler of  claim 11  wherein the first and second water walls are end water walls, and wherein circulating water enters the boiler at opposite ends of the firebox. 
   
   
       13 . The boiler of  claim 11  wherein the first and second water walls are side water walls, and wherein circulating water enters the boiler at opposite sides of the firebox. 
   
   
       14 . The boiler of  claim 11  wherein the end and side water walls each comprise an inner wall and an outer wall, and wherein inner walls of the end and side water walls are connected at ends thereof, and outer walls of the end and side water walls are connected at ends thereof such that a water chamber is formed between the inner and outer walls of the end and side water walls. 
   
   
       15 . The boiler of  claim 11  comprising a first conduit connected to the first water input port at one end thereof and to a first port of a T-connector at an opposite end thereof, and a second conduit connected to the second water input port at one end thereof and to a second port of a T-connector at an opposite end thereof, and a circulating conduit connected to a third port of the T-connector at one end thereof and to the distribution network at an opposite end thereof. 
   
   
       16 . The boiler of  claim 11  comprising:
 an arcuate front end water wall connected to a front end of the right side water wall and connected to a front end of the left side water wall, and curving outward from the front end of the right side water wall and then inward to the front end of the left side water wall; and   an arcuate rear end water wall connected to a rear end of the right side water wall and connected to a rear end of the left side water wall, and curving rearward from the rear end of the right side water wall and then forward to the rear end of the left side water wall.   
   
   
       17 . The boiler of  claim 16  wherein the arcuate front and rear end water walls are substantially vertical. 
   
   
       18 . The boiler of  claim 17  wherein at least one of the front end water wall and the rear end water wall is semi-circular. 
   
   
       19 . A boiler firebox comprising:
 a right side water wall comprising an right inner wall and a right outer wall;   a left side water wall comprising an left inner wall and a left outer wall;   a front end water wall comprising an arcuate front inner wall connected to a front end of the right inner wall and connected to a front end of the left inner wall, and curving outward from the front end of the right inner wall and then inward and connected to the front end of the left inner wall, and a front outer wall connected to the front end of the right outer wall and to the front end of the left outer wall;   a rear end water wall comprising an arcuate rear inner wall connected to a rear end of the right inner wall and connected to a rear end of the left inner wall, and curving outward from the rear end of the right inner wall and then inward and connected to the rear end of the left inner wall, and a rear outer wall connected to the rear end of the right outer wall and to the rear end of the left outer wall;   wherein the right, left, front, and rear inner walls enclose a combustion chamber, and wherein water can circulate through a water chamber formed between the inner and outer walls of the end and side water walls.   
   
   
       20 . The firebox of  claim 19  wherein the arcuate front and rear inner walls are substantially vertical. 
   
   
       21 . The firebox of  claim 20  wherein at least one of the front inner wall and the rear inner wall is semi-circular.