Method and apparatus for improving boiler combustion

Abstract

A combustion air system for a recovery boiler is described in which multiple levels of secondary and tertiary combustion air ports each have an even number of ports, with the ports on opposing walls interlaced. The air system lends itself equally well to front/rear wall or sidewall applications and is especially beneficial for rectangular boilers. The air system features large and small-scale horizontal circulation zones superimposed on each other and the ability to adjust the angle of the air jets. Additional features include port dampers for the starting burners and system control based on kinetic energy.

1. A combustion air system for a recovery boiler comprising a large first and second opposing walls and a plurality of combustion air ports disposed on each opposing wall in an inboard/outboard configuration with at least two inboard ports spaced laterally apart on the first wall and at least two outboard ports spaced laterally apart on the second wall with the inboard ports laterally within an interior boundary defined by the outboard ports imparting multiple upwardly spiral circulation pattern patterns of gasses around the inside perimeter of the boiler defined about a substantially vertical axis of the boiler superimposed on a series of plural smaller upwardly spiral gas circulation patterns defined about plural substantially vertical axes of the boiler contained inside the large pattern. 
     
     
       2. A combustion air system for a recovery boiler consisting of one or more primary air levels, two or more secondary air levels, and two or more tertiary air levels incorporating an two or more number of combustion air ports at each of the secondary and tertiary air levels with half of the ports at each level on a first wall of the boiler, and half on the opposing wall, with all of the ports on the first wall either interlaced or in an inboard/outboard configuration with the ports on the opposing wall,
 in which the upper secondary ports are located directly above the lower secondary ports +/−2 tube spaces, and the upper tertiary ports are located directly above the lower tertiary ports +/−2 tube spaces, 
 in which all of the tertiary ports on a first wall are located directly above the secondary ports on said first wall +/−2 tube spaces, and all of the ports on said first wall are inboard/outboard with secondary and tertiary ports similarly located on the opposing wall. 
 
     
     
       3. A combustion air system for a recovery boiler consisting of one or more primary air levels, two or more secondary air levels, and two or more tertiary air levels incorporating an two or more number of combustion air ports at each of the secondary and tertiary air levels with half of the ports at each level on a first wall of the boiler, and half on the opposing wall, with all of the ports on the first wall either interlaced or in an inboard/outboard configuration with the ports on the opposing wall,
 wherein the configuration is inboard/outboard, and the flow for at least one outboard port is different than flow for an inboard port. 
 
     
     
       4. A combustion air system for a recovery boiler consisting of one or more primary air levels, two or more secondary air levels, and two or more tertiary air levels incorporating an two or more number of combustion air ports at each of the secondary and tertiary air levels with half of the ports at each level on a first wall of the boiler, and half on the opposing wall, with all of the ports on the first wall either interlaced or in an inboard/outboard configuration with the ports on the opposing wall,
 in which the lower boiler is rectangular in plan form with the front and rear walls longer than the sidewalls and the secondary and tertiary ports located on the front and rear walls. 
 
     
     
       5. A combustion air system for a recovery boiler consisting of one or more primary air levels, two or more secondary air levels, and two or more tertiary air levels incorporating an two or more number of combustion air ports at each of the secondary and tertiary air levels with half of the ports at each level on a first wall of the boiler, and half on the opposing wall, with all of the ports on the first wall in an inboard/outboard configuration with the ports on the opposing wall,
 in which the lower boiler is rectangular in plan form with the sidewalls walls longer than the front and rear walls and the secondary and tertiary ports located on the sidewalls. 
 
     
     
       6. A combustion air system for a recovery boiler consisting of one or more primary air levels, two or more secondary air levels, and two or more tertiary air levels incorporating an two or more number of combustion air ports at each of the secondary and tertiary air levels with half of the ports at each level on a first wall of the boiler, and half on the opposing wall, with all of the ports on the first wall in an inboard/outboard configuration with the ports on the opposing wall,
 in which the lower boiler is rectangular in plan form with the sidewalls walls shorter than the front and rear walls and the secondary and tertiary ports located on the sidewalls. 
 
     
     
       7. The combustion air system of claim 1, wherein the multiple circulation patterns comprises counter rotating circulation patterns. 
     
     
       8. The combustion air system of claim 1, wherein:
 the boiler comprises a primary port level and a liquor gun port level located above the primary port level; and   the plurality of combustion air ports imparting the circulation patterns comprise a tertiary port level located above the liquor gun port level or a secondary port level located above the primary port level and below the liquor gun port level.   
     
     
       9. The combustion air system of claim 8, wherein the plurality of combustion air ports imparting the circulation patterns comprise the secondary and the tertiary levels. 
     
     
       10. The combustion air system of claim 1, wherein the injection rates of the combustion air ports are balanced to inject substantially equal kinetic energy from each port. 
     
     
       11. The combustion air system of claim 1 wherein there are an equal number of air ports on each opposing wall. 
     
     
       12. A combustion air system for a recovery boiler comprising:
 at least one primary air level, at least one secondary air level located above the primary air level, at least one liquor gun port level located above the secondary air level, and at least one tertiary air level located above the liquor gun port level;   wherein the primary air level comprises one or more combustion air ports;   wherein the secondary air level incorporates multiple combustion air ports with one or more combustion air ports on each of two opposing walls of the boiler,   wherein the tertiary air level incorporates multiple combustion air ports with multiple combustion air ports on each of two opposing walls of the boiler, and   wherein there are an equal number of air ports of the tertiary air level on each opposing wall interlaced to impart multiple upward spiraling combustion gas circulation patterns.   
     
     
       13. A combustion air system for a recovery boiler comprising:
 at least one primary air level, at least one secondary air level located above the primary air level, and at least one liquor gun port level located above the secondary air level;   wherein the primary air level comprises one or more combustion air ports;   wherein the secondary air level incorporates multiple combustion air ports with multiple combustion air ports on each of two opposing walls of the boiler,   wherein there are an equal number of air ports of the secondary air level on each opposing wall interlaced to impart multiple upward spiraling combustion gas circulation patterns.   
     
     
       14. The combustion air system of claim 13:
 further comprising a tertiary air level located above the liquor gun level comprising multiple combustion air ports with one or more combustion air ports on each of two opposing walls of the boiler;   wherein the air ports of the tertiary air level are positioned to reinforce the multiple upward spiraling combustion gas circulation patterns imparted by the air ports of the secondary air level.   
     
     
       15. The combustion air system of claim 14, wherein there are an equal number of air ports of the tertiary air level on each opposing wall interlaced to reinforce the multiple upward spiraling combustion gas circulation patterns imparted by the air ports of the secondary air level. 
     
     
       16. The combustion air system of claim 14, wherein the injection rates of the ports of the secondary and the tertiary levels are balanced to inject substantially equal kinetic energy from each level. 
     
     
       17. A combustion air system for a recovery boiler comprising:
 at least one primary air level, at least one secondary air level located above the primary air level, at least one liquor gun port level located above the secondary air level, and at least one tertiary air level located above the liquor gun port level;   wherein the primary air level comprises one or more combustion air ports;   wherein the secondary air level incorporates multiple combustion air ports with one or more combustion air ports on each of two opposing walls of the boiler,   wherein the tertiary air level incorporates multiple combustion air ports with one or more combustion air ports on each of two opposing walls of the boiler,   wherein air flow to a plurality of the combustion air ports is configured to impart multiple upward spiraling combustion gas circulation patterns, each defined about a different substantially vertical axis within the boiler; and   wherein the combustion air ports of the secondary air level are biased downward.   
     
     
       18. The combustion air system of claim 17, wherein the gas circulation patterns within the boiler comprise multiple circulation patterns, each defined about a different substantially vertical axis within the boiler, without a larger circulation pattern superimposed around the multiple circulation patterns. 
     
     
       19. The combustion air system of claim 17, wherein the combustion air ports of the secondary air level or the tertiary air level are positioned in an interlaced configuration. 
     
     
       20. The combustion air system of claim 17, wherein the combustion air ports of the secondary air level or the tertiary air level are positioned in an inboard/outboard configuration. 
     
     
       21. The combustion air system of claim 17, wherein a circulation rotational direction imparted by the secondary air level is reverse to a circulation rotational direction imparted by the tertiary air level. 
     
     
       22. The combustion air system of claim 17, wherein the injection rates of the ports of the secondary or tertiary air levels are balanced to inject substantially equal kinetic energy from each port. 
     
     
       23. The combustion air system of claim 17, wherein the gas circulation patterns within the boiler comprise multiple circulation patterns with a larger circulation pattern superimposed around the multiple circulation patterns. 
     
     
       24. The combustion air system of claim 17, wherein the combustion air ports of the tertiary air level are directed in a substantially horizontal direction. 
     
     
       25. A combustion air system for a recovery boiler comprising:
 at least one primary air level, at least one secondary air level located above the primary air level, at least one liquor gun port level located above the secondary air level, and at least one tertiary air level located above the liquor gun port level;   wherein the primary air level comprises one or more combustion air ports;   wherein the secondary air level incorporates multiple combustion air ports with one or more combustion air ports on each of two opposing walls of the boiler,   wherein the tertiary air level incorporates multiple combustion air ports with one or more combustion air ports on each of two opposing walls of the boiler,   wherein air flow to a plurality of the combustion air ports is configured to impart multiple upward spiraling combustion gas circulation patterns; and   wherein a circulation rotational direction imparted by the secondary air level is reverse to a circulation rotational direction imparted by the tertiary air level.