Clayton Industries offers two types of emission reduction systems to meet local air regulations and customer operating parameters. These are a Flue Gas Recirculation (FGR) system and an ultra-low NOx Fiber Metal Burner (FMB) system. Please discuss when and how these systems are applied with your local thermal sales representative.

Flue Gas Recirculation (FGR)

A coated exhaust gas recirculation ducting system with adjustable dampers can be provided on all units from 50 to 2,000 BHP. It reduces NOx emissions to levels below 30 ppmv and CO levels less than 400 ppmv. (corrected to 3% O2). This system is used when the primary fuel is natural gas or propane. It is required that the unit also be able to run on light oil for backup purposes. NOx reduction on light oil is guaranteed to be less than 90 ppmv. A separate cooling air blower is supplied to provide cooling for the heating coil outer shell. This item is off mounted from the main industrial steam generator frame and includes a centrifugal blower and motor with a flexible interconnecting hose duct. When permitted by local air regulations, the FGR system allows rapid changeover and operation on either gaseous or liquid fuel.

Ultra-Low NOx Fiber Metal Burner (FMB)

Clayton Industries’ newest burner assembly is an ultra-low NOx system utilizing a burner made of a high-temperature fiber metal and a unique air/fuel mixing system. It reduces NOx emissions to as low as 6 ppmv and CO emissions to less than 50 ppmv (corrected to 3% O2). This system is available for E-Series industrial boilers from 150 to 2000 BHP and on our

See SigmaFire models from 50 to 200 BHP.

This system does not incorporate any form of Flue Gas Recirculation (FGR). The main air blower is a high-pressure, aluminum, dual-taper radial type blower that is belt driven by a motor. The premix chamber on the E-series steam boilers is a rectangular duct with a gas diffusion pipe and mixing plates. A modulating air damper is mounted between the main blower and premix chamber. The outlet of the premix chamber is connected to the inlet volute, which directs the premixed air/fuel to the “Fiber Metal” burner assembly. The blower can also be supplied with a variable frequency drive as an additional power saving option.

The coil burner base is different from the standard non-low NOx unit design. The cooling air directed to the outer shell is segregated from the premixed air/fuel and the internal diameter is sized to fit the low NOx burner assembly. A thermocouple is mounted in the volute, with interconnecting circuits to the generator control panel to monitor volute temperature. The unit is automatically shut down upon an excessive increase in volute temperature.

The separate cooling air blower is supplied to provide cooling for the heating coil outer shell. This item is off-mounted from the main steam generator frame and includes a centrifugal blower and motor with a flexible interconnecting hose duct.

The amount of nitrogen oxides (NOx) formed during combustion is a function of three main variables. They are the amount of fuel bond nitrogen, the temperature of combustion and the duration (or length) of the flame. Clayton’s FMB system incorporates a combination of technologies to reduce the formation of NOx due to the last two variables. Improved air and fuel mixing, ultra-lean flame design and a low-flame residence time provide for excellent reduction of emissions compared to other systems. The Clayton Fiber Metal Burning system can be guaranteed to reduce NOx emissions to below 9 ppmv for units from 50 to 2,000 BHP. CO levels are guaranteed to below 50 ppmv. An optional O2 trim system is also available to reduce the level to less than 6 ppmv when required by local regulations.

Incorporated with the new FMB system is an improved Siemens linkage-less burner control management system that allows for more precise tuning and mixture control. This system replaces the older modulating motor system that used a single-modulating motor and linkage to control both the air damper and fuel valve.