Patented Technologies

PLASMA RESONANCE FLAME DETECTION

The Preferred Flame Detection Method

Plasma Resonance is a Stackmatch Patented method of flame detection specifically designed for instantaneous pilot flame recognition and when unavoidable, to fail in the fail safe condition.

Background Information

Flare or burner pilot systems must normally operate under difficult and dirty ambient conditions. To know that a pilot is functioning properly and that a stable flame exists at the pilot nozzle is critical for safe pilot operations. Likewise, proper flame detection for a pilot operating inside a vessel intended for ignition of main burner gas is crucial to the safety of the operation. The speed of detection for both ignition and when flame failure has occurred is extremely important. Unlike slow responding systems that depend on temperature settings for detection, plasma resonance is a technology that provides for instantaneous pilot flame recognition, even under the worst of conditions.

Origins for the Name

To further understand the origins for the name given to this Stackmatch patented method of flame detection, these definitions are offered:

  • Plasma: A hot electrically neutral, highly ionized gas composed of free electrons, ions and neutral particles.
  • Resonance: The natural excitation frequency exhibited by a burning gas confined within an open chamber.

Operating Principle

Gas becomes electrically conductive when its temperature is elevated to release the free electrons available within the gas composition. This process, which describes the generation of an electron cloud that can move within the gas envelope, is better known as the Ionization Principle.

Ionization as a method of flame detection employing fire rods or probes inserted into a flame has been available to the industry for many years. This method determines the absence or presence of flame by monitoring the amount of current passing between the two conductive electrodes, each in contact with the flame and powered by an external power supply. Unfortunately this method known as ionization flame detection is easily fooled when the electrode insulators become wet or dirty causing current to flow even when no flame is present. This failure mode is well known throughout the industry and is further complicated as it occurs as a failure in the non-failsafe condition. When other gas sources exist that depend solely on the failed Pilot for ignition a non-failsafe condition can quickly become catastrophic.

Even though plasma resonance, the Stackmatch method for flame detection, utilizes the same basic ionization principle, what is detected is not the amount of current but rather the current variations irregardless of current amounts. The combustion process within a pilot elevates the gas temperature releasing quantities of electrons with naturally occurring current variations that range in frequency between (500 to 5,000 Hz). With the electronics tuned to this known plasma resonance frequency, wet or dirty electrode isolators that cannot produce a frequency are of no consequence to plasma resonance. In addition, should the electrodes become shorted or the insulators so degraded that the signal is weakened to lower than acceptable levels, the system will indicate no Pilot flame even when the Pilot flame may still exist. This type of failure in detection is in the failsafe condition.

Utilized in many different and difficult applications, and in daily operation at many locations throughout the world, plasma resonance as a method of pilot flame detection has, over the years, proven to be an effective and preferred state of the art technology.

MICRO FLAME FRONT IGNITION

Background Information

Pilot systems must normally operate under difficult and dirty ambient conditions. Since ignition of a pilot is critical during any start-up process, components intended for ignition must be ready to operate satisfactorily at a moment’s notice. Designs utilizing high voltage probes requiring ceramic isolators are prone to degradation and premature failure when wet or dirty. External flame front lines, not an integral part of the pilot have also been employed for pilot ignition, however, these systems are very expensive and over time can collect water or moisture which causes scaling and other types of obstruction failures.

Operating Principle

Stackmatch Pilots operate with our patented Micro Flame Front Ignition technology that is built with an ignition tube located inside the pilot body. This tube is allowed to fill with the same volatile fuel normally processed through the pilot body. Adjacent to this tube is a high-energy semiconductor component that originates pilot ignition. This design allows for all ignition components to be located at a safe distance from the excessive heat expected at the pilot nozzle. In addition, no water is allowed to remain within the pilot to cause ignition failure. During an ignition event, the nozzle is showered with flame for strong and sound pilot ignition. Because the micro flame front tube is internal and constantly purging forward, all internal components remain cool.

Internally, this pilot is equipped with the unique Stackmatch patented ignition method. An internal Micro Flame Front Ignition is ignited at the base of the pilot by our exclusive “Low Voltage-High Energy” component. This generates a ball of flame at the base of the pilot which escapes the pilot through the nozzle cavity insuring proper pilot ignition.

How It Works

  • Air and gas flow through the primary pilot
  • As mixed air and gas is passed through the primary pilot, small amounts enter the Micro Flame Front Ignition tube through small orifices. It is here where the mixed air and gas is ignited creating a small ball of flame which purges forward and exits the end of the Micro Flame Front Ignition tube igniting the Primary Pilot.
  • Since the Micro Flame Front Ignition is inside the primary pilot, it is cooled due to the cool mixed air and gas passing on the outside of the tube.

COOL TIP

 

INVERTED NOZZLE

Stackmatch designed and patented for extreme efficiency.

This unique “Inverted Nozzle” arrangement, with top and bottom diversion plates, was designed to allow the spent nozzle gas to continuously clean the pilot nozzle. As the spent gas escapes to atmosphere, this downward jetting action further protects the nozzle cavity from contamination should liquids or solids be expelled from the flare opening.

  • Nozzle – Type (310) Stainless Steel Construction
  • Patented Inverted Self Purging Design
  • Patented Top & Botton Diversion Plates
  • Rated up to 200 MPH winds
  • Can be Retrofitted With 2 or 3 Jet Configuration

Pilot Nozzle Cavity

Allows for extreme Flame Stability

The internal construction of the nozzle cavity is calculated to provide a firmly rooted and highly protected pilot flame configuration, which results in extreme pilot flame stability. Even when subjected to 200 MPH winds and rain, this pilot nozzle can be easily ignited when cold.

Pilot Diversion Plates

Allows for excellent flare flow dynamic range

Besides protecting the nozzle area from inadvertent liquid spills, these plates are strategically located so that any waste gas escaping the flare is forced to circulate within these two plates. This patented circulating function allows for proper waste gas ignition even when the exit velocity of the waste gas is very slow or above MACH 1.

Lower pilot diversion plate can also used as a manifold outputting 2 or 3 by-pass jets to reach over the top of flaring application.