Method for treating emissions

A method for removing NOX from flue gas with an emission treatment system, the flue gas being generated by a plant having one or more burners located at an inlet end of a vertically extending stack, the stack including a first ID fan disposed therein, the flue gas being discharged through an outlet end of the stack, the emission treatment system including a major component module, inlet ductwork, outlet ductwork, and an ammonia addition subsystem, the major component module having an SCR segment, a heat exchanger segment, and a second ID fan, the SCR segment having at least one catalyst unit composed of materials for selectively catalyzing NOX, the ammonia addition subsystem being in fluid communication with the inlet ductwork, the method comprising the following steps:

• attaching the inlet ductwork to the stack at a first position intermediate the inlet end of the stack and the first ID fan;
• attaching the outlet ductwork to the stack at a second position intermediate the first ID fan and the outlet of the stack;
• closing the stack at a third position intermediate the first and second positions to prevent the flow of flue gas through the first ID fan;
• drawing the flue gas from the stack through the inlet ductwork and through the major component module with the second ID fan;
• injecting ammonia vapor into the inlet ductwork with the ammonia addition subsystem;
• removing the NOX from the flue gas with the SCR segment of the major component module to produce a clean flue gas;
• and
• discharging the clean flue gas through the outlet ductwork to the stack with the second ID fan.

A method for removing NOX from flue gas with an emission treatment system, the flue gas being generated by a plant having one or more burners located at an inlet end of a vertically extending stack, the stack including a first ID fan and a feedwater heating coil disposed therein, the flue gas being discharged through an outlet end of the stack, the plant also having a boiler and a feed pump circulating feedwater to the boiler, the emission treatment system including a major component module, inlet ductwork, outlet ductwork, and an ammonia addition subsystem, the major component module having an SCR segment, a heat exchanger segment, and a second ID fan, the SCR segment having at least one catalyst unit composed of materials for selectively catalyzing NOX, the heat exchanger segment having feedwater feed and return lines, the ammonia addition subsystem having a source of ammonia vapor, an ammonia injection grid disposed in the inlet ductwork, an ammonia vapor pipe providing fluid communication between the source of ammonia vapor and the ammonia injection grid, and a throttle valve disposed in the ammonia vapor pipe, the method comprising the following steps:

• attaching the inlet ductwork to the stack at a first position intermediate the inlet end of the stack and the first ID fan;
• attaching the outlet ductwork to the stack at a second position intermediate the first ID fan and the outlet of the stack;
• closing the stack at a third position intermediate the first and second positions to prevent the flow of flue gas through the first ID fan and the feedwater heating coil;
• drawing the flue gas from the stack through the inlet ductwork and through the major component module with the second ID fan;
• injecting ammonia vapor into the inlet ductwork with the ammonia addition subsystem;
• removing the NOX from the flue gas with the SCR segment of the major component module to produce a clean flue gas;
• discharging the clean flue gas through the outlet ductwork to the stack with the second ID fan;
• controlling the flow rate of the flue gas through the major component module by regulating the pressure decrease across the second ID fan;
• controlling the rate of ammonia addition by regulating the throttle valve;
• and
• controlling the flow of the feedwater through the heat exchange segment by regulating the speed of the feed pump.