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Self-Stabilized and Highly Reliable Oil Igniter – Forney’s DURAFire®

An oil igniter is used to light off fuel in a wide variety of applications. As the name suggests, oil is used as the combustion fuel. To achieve ignition, the oil is atomized and piped toward the spark igniter to initiate combustion. The Forney DURAFire® is an oil igniter with a variety of innovations to ensure at least 95% igniter light-off efficiency is maintained. This article will explore the DURAFire® oil igniter and describe how it can achieve such a high level of reliability.

Why Is a Reliable Oil Igniter Important?

Oil igniters are used to provide a stable and reliable ignition source for fossil fuel burners. Unreliable burner ignition not only creates a burner problem but also results in significant financial losses. As such, it is important that the igniter can be counted on to reliably start ignition within the burner. The Forney DURAFire® oil igniter (Figure 1) is one such oil igniter that offers over 95% light-off reliability.

Figure 1: Forney DURAFire® Oil Igniter

Table 1 below details the Forney DURAFire® oil igniter specifications:

Fuel No. 2 oil
Capacity Rating* 6–33 MBtu/hr (1.76–9.67 MW)
Atomization Media Air
Fuel Pressure 60 psig (4.22 kg/cm2) at igniter
Atomizing Air Pressure: 80 psig (5.62 kg/cm2) at igniter.
Flow: 0.40 lb air/1 lb fuel
Cooling/Combustion Air Flow: 60 SCFM ( 1.7 Nm3/min) at igniter.
Pressure Drop: Approximately 3 in. (76.2 mm ) WC across device Connection: 1½ inch NPT female
Length Available in 2” (50.8 mm) increments from 24 to 180 inches (609 to 4572 mm)
Guide Tube Outside Diameter A 4” (101.6 mm) - igniter can be installed in an existing mount tube for a 4” (101.6 mm) diameter device
Mount Tube Outside Diameter 4.5” (114.3 mm)
Construction Material Guide Tube and Mount Tube - Carbon Steel.
Furnace End of Guide Tube - 304 Stainless Steel.
Oil Tip Assembly - 304 Stainless Steel

Where Are Oil Igniters Used?

The DURAFire® oil igniter can be used in most burner applications provided there exists a supply of no. 2 oil, compressed air and combustion/cooling air. DURAFire® Igniters are used in a wide variety of industries, from power generation to furnaces, and can be used for class 1,2, & 3 applications. The oil is atomized by externally supplied compressed air that is ignited with a HESI (high-energy spark igniter).

What Is the Combustion Zone?

For the DURAFire® oil igniter, the combustion zone refers to an area inside the oil igniter where the atomized oil/air mixture is ignited by the spark igniter. Combustion air is supplied through the guide tube and is diffused through a diffuser plate that ensures the combustion air is evenly distributed throughout the combustion zone. The combustion zone is protected from the general burner environment by the guide tube so that the optimal air-fuel mixture is maintained. This is part of the reason why the DURAFire® igniter operates so reliably.

About Oil Igniter DURAFire® 

A Forney DURAFire® oil igniter is assembled from the components listed below and indicated in Figure 2 below:

Figure 2: Oil Igniter Schematic
  1. Guide Tube: The guide tube contains the atomizer, air/fuel transport pipe, diffuser, and spark rod. The guide tube is manufactured from a standard 4” tube. The front of the tube is utilized as the primary combustion zone and also serves to transport combustion and cooling air into the primary combustion zone via the diffuser.
  2. Atomizer: The atomizer has two inputs, namely oil and air. The oil is injected into the airstream inside the atomizer, which causes the oil to break up into a fine mist. The atomizer is positioned far from the combustion zone, which reduces fouling and, by extension, maintenance.
  3. Oil/Air Mixture Transport Tube: After the fuel-oil mixture has been generated via the atomizer, it is transported down the length of the guide tube into the combustion zone. The oil/air mixture enters the combustion zone directly behind the spark igniter for optimal ignition conditions.
  4. Spark Rod: The spark rod uses a high-voltage arc to ignite the oil/air mixture. The HESI (High-Energy Spark Ignition) is supplied as standard and can reliably ignite the mixture.
  5. Diffuser: The diffuser plate is a plate that provides even airflow into the primary combustion zone. This air, coupled with the atomized oil, is ignited inside the combustion zone.

The DURAFire®  igniters also have a viewing port to allow operators to inspect the status of the ignition. In addition to this, the Forney range of flame detectors can be installed on the DURAFire® oil igniter.

Dependable Oil Igniters with Forney

Dependable first light off is critical to the optimal functioning of any burner system. The DURAFire® igniter employs a range of innovations to achieve unparalleled reliability. These include a protected combustion zone for optimal ignition conditions, HESI (High-Energy Spark Igniter) for reliable spark generation and fuel ignition, and an optimized atomizer location to reduce fouling and maintenance requirements. 

To learn more about how our oil igniters can provide reliable and consistent burner ignition for your plant, contact a Forney representative today.

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.