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MAXFire® Gas Igniters: For Reliable, Low Maintenance Burner Ignition

Gas igniters are a type of burner igniter fueled with natural gas. They are used in fossil fuel boiler applications and provide high-reliability light-off. Forney gas igniters, like the MAXFire® range, deliver this high reliability by using a protected primary combustion zone, which creates a zone of ignition unaffected by the boiler environment. 

Functions and Importance

Gas igniters are designed to provide an ignition source for fossil fuel burners. However, unreliable burner ignition can result in significant financial losses while creating unsafe conditions within the boiler. Reliable gas igniters are critical to the safe and efficient operation of fossil fuel boilers by ensuring regular, first-time main flame ignition. Upgrading to the Forney MAXFire® gas igniters results in up to 99% light-off reliability and reduced air consumption and maintenance requirements. It helps ensure long-term operation due to the use of durable components and also prevents excessive downtime. A typical gas igniter is shown in Figure 1 below:

Figure 1: Gas Igniter

Table 1 below lists the Forney gas igniter specifications:

Maxfire Series Gas Igniter Specifications
Type MAXFire® 110 MAXFire® 130 MAXFire® 135 MAXFire® 140
Fuel Natural gas
Fuel Heating Value 1000 Btu/ft3
Guide Tube OD 1 7/8" 2 7/8" 3 ½" 4"
Capacity rating 0.3 to 0.5 MMbtu/hr @ 2 psig 0.2 to 1.5 Mbtu/hr @ 10 to 15 psig 1.5 to 6 MMbtu/hr @ 10 to 25 psig (orifice size dependent) 5 to 10 MMBtu/hr @ 10 psig 11 to 15 MMBtu/hr @ 15 to 20 psig 5, 10, and 15 MMBtu/hr @ 15 psig 20 and 25 MMBtu/hr @ 25 psig
Gas inlet port ½" NPT ¾" NPT 1 ½" NPT 1 ½" NPT
Cooling/Combustion air 23 scfm 45 scfm 50 scfm 80 scfm
Cooling/ combustion air pressure 3.0 to 6.0 inches w.c. above wind box pressure measured at the sight port/scanner
Air inlet port ¾" NPT ¾" NPT female 1 ½" NPT 1 ½" NPT female
Ignition source HESI, Series 90 HESI, Series 90EC HTSI
NFPA Class 1, 2, or 3
Recommended gas supply hose size ¾" ID 1" ID 1 ½" ID 1 ½" ID
Gas line strainer 0.033 inch-NPT female

Table 1: Gas Igniter Specification

Applications and Use Cases

MAXFire® gas igniters are used to ignite multi-burner fossil-fuel-fired boilers or duct burners. This means burners that make use of coal, natural gas, oil, or hydrogen as their primary fuel. These boilers can be found in various industries, from power generation to food production. Gas igniters use natural gas as the igniter fuel, while combustion air is provided from an external source. Typically, a HESI (high-energy spark igniter) is used to ignite this fuel-air mixture, but other types of igniters like an HTSI, are also available. 

Different Classes of Igniters

There are three different classes of gas igniters as defined by the boiler and combustion systems hazards code (NFPA 85). The Forney MAXFire® gas igniter can be configured for class-1, 2, & 3 applications with a capacity range from 0.3 to 50 MBtu/hr, whereas the HC MAXFire® igniter is limited to class-1 applications. The different igniter classes are described below:

  1. Class 1: used for burner light-off and support
  2. Class 2: used for burner light-off and burner support under prescribed conditions
  3. Class 3: limited to light-off use only and not for burner support or warm-up

MAXFire® Gas Igniter Components

The Forney MAXFire® gas igniter consists of the components listed below and indicated in Figure 2:

Figure 2: MAXFire® Gas Igniter Components
  1. Guide Tube: The guide tube houses the igniter assembly and provides a protected combustion zone to facilitate optimal air/fuel mixture for ignition. The mount tube is typically welded to the burner front plate. The burner assembly can also fit most existing mount tubes allowing for simple retrofitting. 
  2. Spark Tip: A high-energy spark igniter (HESI) is typically used and generates a 12-joule spark three times every second. Alternatively, a high-tension spark igniter (HTSI) can be used which offers high performance and reduced cost. The reliable, non-fouling, high-energy spark ensures MAXFire® gas igniters have up to 99 % reliability.
  3. Orifice Tube Assembly: A stainless steel orifice tube allows for diffused gas supply for optimal ignition conditions.
  4. Gas Transport Tube: The gas transport tube directs the gas from the gas supply port to the diffuser. 

Forney MAXFire® gas igniters have an integral viewport that can be used to house a flame detector, provided NFPA requirements are met. Cooling air is continually introduced into the guide tube to cool the igniter while also preventing the build-up of debris in the guide tube, providing a self-cleaning function. MAXFire® gas igniters have very low air volume requirements without compromising functionality, while their durable construction materials ensure long service life. The igniter assembly can be removed from the guide tube by removing the clamp.

Reliable Igniter Solutions With Forney

From day 1, Forney MAXFire® gas igniters provide dependable, first-time light-off with up to 99% reliability in most applications due to high-quality spark igniters, while also providing an optimal and protected fuel/air mixture inside the guide tube. After initial ignition combustion, air is used to cool the igniter while also preventing debris from accumulating inside the guide tube. The igniter assembly can be easily removed from the guide tube housing for quick and easy maintenance, resulting in limited downtime. 

Forney offers a 12-month warranty from installation or an 18-month warranty from delivery for this product. A MAXFire® gas igniter can be tested before purchasing with flexible testing times available (30, 60, or 90 days) to ensure it performs as advertised before purchase.

Contact a Forney representative today to learn more about how our gas igniters can provide reliable and consistent burner ignition for your plant.

About Forney

Forney Corporation has over 93 years of experience manufacturing the safest and most reliable combustion equipment for more than 1,000 power plants in over 100 countries. Customers have proved the quality and durability of Forney’s state-of-the-art front-end combustion components in many industries across the globe. Forney igniters, burners, burner management systems, flame detectors, dampers, and duct burners have provided efficiencies and cost savings for plant operators in electric utilities, chemical processing, pulp & paper, and cement industries.