Method and system for SCR optimization

• US 7,500,437 B2
• Filed: 12/15/2004
• Issued: 03/10/2009
• Est. Priority Date: 08/27/2004
• Status: Active Grant

• Current Assignee: GE Digital Holdings LLC (GE Aerospace)
• Original Assignee: NeuCo Incorporated (General Electric Company)
• Inventors: Lefebvre, Wesley Curt, Kohn, Daniel W.
• Primary Examiner(s): RINEHART, KENNETH
• Application Number:
  US11/012,630
• Publication Number:
  US 20060042525A1
• Time in Patent Office: 1,546 Days
• Field of Search: 110185-191, 110341-345
• US Class Current: 110/186
• CPC Class Codes: F23G 5/50 Control or safety arrangements
• CPC Class Codes: F23J 15/02 of purifiers, e.g. for removing noxious material traps for solid residues F23J3/04
• CPC Class Codes: F23J 2219/10 Catalytic reduction devices
• CPC Class Codes: F23J 3/00 Removing solid residues from passages or chambers beyond the fire, e.g. from flues by soot blowers
• CPC Class Codes: F23N 2241/10 Generating vapour
• CPC Class Codes: F23N 5/003 using detectors sensitive to combustion gas properties F23N5/02, F23N5/18 - F23N5/26 take precedence

Abstract

Methods and systems are provided for controlling SCR performance in a boiler. The boiler includes one or more generally cross sectional areas. Each cross sectional area can be characterized by one or more profiles of one or more conditions affecting SCR performance and be associated with one or more adjustable desired profiles of the one or more conditions during the operation of the boiler. The performance of the boiler can be characterized by boiler performance parameters. A system in accordance with one or more embodiments of the invention can include a controller input for receiving a performance goal for the boiler corresponding to at least one of the boiler performance parameters and for receiving data values corresponding to boiler control variables and to the boiler performance parameters. The boiler control variables include one or more current profiles of the one or more conditions. The system also includes a system model that relates one or more profiles of the one or more conditions in the boiler to the boiler performance parameters. The system also includes an indirect controller that determines one or more desired profiles of the one or more conditions to satisfy the performance goal for the boiler. The indirect controller uses the system model, the received data values and the received performance goal to determine the one or more desired profiles of the one or more conditions. The system model also includes a controller output that outputs the one or more desired profiles of the one or more conditions.

Claims

1. A system for controlling performance of a selective catalytic reduction (SCR) system for reducing NOx levels in flue gas associated with a fossil fuel boiler having one or more generally cross-sectional areas, each cross-sectional area being characterized by a profile of a condition affecting SCR performance at said cross-sectional area, the system comprising:

one or more devices associated with said one or more cross-sectional areas for adjusting the profile characterizing a cross-sectional area, said one or more devices operating in accordance with adjustable operating parameters;

one or more sensors associated with said one or more cross-sectional areas for detecting conditions at said one or more cross-sectional areas; and

a computer programmed to operate as an indirect controller for determining operating settings for the one or more devices, said indirect controller including;

a system model that relates operating settings for the one or more devices to desired profiles of said conditions affecting SCR performance at said one or more generally cross-sectional areas,

a controller input in communication with said one or more sensors, said indirect controller using the conditions detected by said one or more sensors, the system model, and the desired profiles to determine operating settings for the one or more devices, and

a controller output in communication with said one or more devices to transmit said operating settings to said one or more devices associated with said one or more generally cross-sectional areas of the fossil fuel boiler;

wherein said one or more devices include an SCR sootblower associated with at least one of said one or more cross-sectional areas for cleaning a surface in a catalyst bed to adjust a catalyst activity profile, an NH₃ injector associated with at least one of said one or more cross-sectional areas to inject NH₃ in said boiler and to adjust a NH₃ profile, and a fuel and air injector associated with at least one of said one or more cross-sectional areas to inject fuel and air in said boiler and adjust a NOx profile;

wherein said one or more sensors associated with at least one of said one or more cross-sectional areas detect a NOx level, an NH₃ level, and catalyst activity at said one or more cross-sectional areas;

wherein said indirect controller includes a system model that relates operating settings for the SCR sootblower to a desired catalyst activity profile, operating settings for the NH₃ injector to a desired NH₃ profile, and operating settings for the fuel and air injector to a desired NOx profile;

wherein the indirect controller uses the NOx levels, the NH₃ levels and the catalyst activity detected by said one or more sensors, the system model, and the desired catalyst activity profile, the desired NH₃ profile, and the desired NOx profile to determine operating settings for the SCR sootblower, the NH₃ injector, and the fuel and air injector, respectively; and

wherein the controller output of the indirect controller communicates with said SCR sootblower, NH₃ injector, and air and fuel injector to transmit said SCR sootblower operating settings to said SCR sootblower, said NH₃ injector operating settings to said NH₃ injectors, and said fuel and air operating settings to said fuel and air injectors.

2. A system according to claim 1, wherein said boiler has a plurality of said generally cross-sectional areas.

3. A system according to claim 1, wherein said one or more generally cross-sectional areas of the boiler include at least one cross-sectional area external to the SCR system.

4. A system according to claim 1, wherein said one or more generally cross-sectional areas of the boiler include at least one cross-sectional area upstream of an SCR catalyst.