Patented Innovation for Fossil Fired Power Plants: Latest Tangentially Fired (T-Fired) Nozzle

Thermal Guard™ Series II Plus

The latest patented innovation to our Thermal Guard Nozzle Design, named the Thermal Guard Series II Plus (TG2 Plus), continues to improve firing system control through extended nozzle tip longevity.

For over 45 years R-V Industries, has been a leader and champion in the fossil fuel power industry, providing customers with innovative solutions for their combustion systems. In these changing times, as the global focus toward de-carbonization and renewables increases, the remaining fossil plants are under significant pressure to accommodate grid demands while retaining competitive power prices and minimal emissions.

Despite social sentiment, R-V continues its commitment to driving advancements in this vital sector. One such advancement is a new nozzle tip for tangentially fired units that further extends nozzle service life, the TG2 Plus. This patented design has demonstrated its longevity to support increased pressure for extended outage intervals. With aerodynamic stiffening and integral splitter plate cooling, this design represents a significant evolutionary step in service life over previous nozzle tip designs for tangential fired units.

This advancement adds to our pioneering history of coal and air tip nozzles innovation, beginning with the original Thermal Guard Nozzle Tip. For the past 15 years, its ability to cool burner nozzle surfaces exposed to furnace thermal radiation has proven itself time and time again. Check out our testing of the original Thermal Guard design here. These advancements represent our mission to support the fossil fired power industry toward longer operational efficiency and emission control across the load range of each unit.

Test Results: Nozzle Tip Distortion at the Splitter Plate

This new nozzle tip advancement focused on the internal fuel and primary air side of the nozzle tip by strengthening the splitter plates. Splitter plates are used to divert the fuel flow as nozzle tips are tilted vertically. When tilted, increased exposure to furnace radiation leads to the potential for an increased rate of thermal distortion. As splitter plates and nozzles distort, the flame aerodynamics become effected which increases emissions and eventually compromises the mechanical reliability of the nozzle tips. Plate distortion has plagued tangential fired units since the system’s inception.

Now with the demands placed on power and steam producers to operate at high and low load range, the sensitivity to distortion has increased. The patented design of R-V’s Thermal Guard Series II Plus design reinforces the exit of each splitter plate with specially designed stiffeners, boasting aerodynamic stiffening and a thermal cooling air barrier solution. Through these two design improvements, this nozzle has proven increased longevity across a 2-year in unit test.

For common splitter plate designs, the constant exposure to high temperatures leads to metallurgical creep, resulting in distortion and damage to various parts. Temperatures exceeding 1800oF are common for nozzle tips. Using high rates of combustion air for cooling is not an option when emission control does not allow it. This distortion and cracking not only compromise the aerodynamics of the nozzle outlets but also contribute to ash deposits that clog the outlets, rendering the nozzles ineffective and ultimately causing failure.

Common splitter plate distortion after 2 years in service.
Thermal Guard Series II Plus on the same unit after 2 years in service.

The Patented Innovation Explained

To combat these plate failures, R-V Industries developed, and has been installing, an aerodynamic design solution for these common splitter plate problems. This innovative design provides higher temperature strength while allowing for the aerodynamic passage of coal and air particles over the stiffener bar, eliminating the creation of low-pressure zones that were previously prone to flame attachment.

By integrating this airfoil-type stiffener, recirculating fuel and airflow is reduced. This mitigates the risks associated with flame attachment and the detrimental accumulation of ash. Additional thermal protection is added through perforations in the stiffener, which channel secondary air across the front of the nozzle tip. This provides maximum cooling from the hot furnace gas and radiation exposure. Cooling the stiffener also adds metallurgical rigidity, further strengthening the end of the splitter plate.

By mitigating distortion and failure of the splitter plates, this effective aerodynamic design significantly enhances the service longevity of the TG2 Plus nozzle tips. Consequently, the service life of the coal nozzle tips is extended, offering substantial operational and emission control advantages, particularly when dealing with high-sulfur coal. The prevention and reduction of coal ash adhesion, commonly observed in flat bar designs that create low-pressure zones, make this feature especially beneficial.