Oil burner
Encyclopedia
An oil burner is a heating device which burns fuel oil
. The oil is atomized
in to a fine spray usually by forcing it under pressure through a nozzle
. This spray is usually ignited by an electric spark
with the air being forced through by an electric fan.
.
The nozzles are usually supplied with high pressure oil. Because of problems with erosion
, and blockage due to lumps in the oil, they need frequent replacement typically every year. Fuel nozzles are usually rated in fuel volume flow per unit time e.g. USGal/h (U.S. Gallons per hour).
A fuel nozzle is characterized by 3 features:
Alternatively fuel may be passed over a tiny orifice
fed with compressed air. This arrangement is referred to as babington atomiser/nozzle after its inventor. As the oil flows over the nozzle , the fuel needn't be under any great pressure. If the pump can handle such the oil may even contain lumps such as scraps of food. Because it is only compressed air that passes through the orifice hole, such nozzles do not suffer much from erosion.
A fuel oil pump
consists of two parts:
This sucks the oil and increases the pressure in the nozzles to 15 bar maximum. Usually a gear pump
of the sickle type is used. This type of pump is a simple and therefore cheap pump
consisting of one or more radical pairs of gear
s and with a very small space between the gears and the pump casing. Gear pumps are used frequently in oil burners because of their simplicity, stability and low price.
To set the heat output of the burner, the rate of fuel delivery via the nozzle must be adjustable. This is often achieved by an adjustable pressure relief valve between the pump and the nozzle. When the set pressure is reaches usually 10 - 11 bar, this valve opens and allows excess oil through a bypass back to the fuel tank or pump suction.
of the fan is powered by a electric motor
.
Many use high voltage generated by a voltage-step up transformer and use a spark plug to initiate ignition
A light sensitive resistor (LDR
) detects the flame. The LDR (or Light Dependent Resistor) resistor is an electrical resistor whose value changes by the amount of light
that it present. The resistance value of an LDR becomes smaller, as the LDR is more and more exposed. The material is usually cadmium
sulfide
, the dark resistance is 1.10 MΩ resistor while the light resistance is about 75-300 Ω. LDR's have a relatively slow response time.
capacitor start motor. It is a vortex shortage tank motor because it also contains a short cage or cage
holds. The difference with a three-phase motor is in the stator
. Where the vortex power motor has three coils aligned at 120° in the stator, the capacitor start motor holds one main winding and one auxiliary winding aligned at 90°. The phase shift of 90° between the main winding and the auxiliary winding is achieved by a connected capacitor which feeds the auxiliary winding and is connected on the single-phase AC mains. The capacitor will achieve a phase shift of 90° between the main and the auxiliary winding, producing an acceptable initial torque. This motor is intended for continuous operation.
If the burning does not catch on, the burner will go into alarm and must then be manually reset.
Fuel oil
Fuel oil is a fraction obtained from petroleum distillation, either as a distillate or a residue. Broadly speaking, fuel oil is any liquid petroleum product that is burned in a furnace or boiler for the generation of heat or used in an engine for the generation of power, except oils having a flash...
. The oil is atomized
Atomizer nozzle
An atomizer nozzle is an aspirator nozzle for producing a fine spray of a liquid based on the Venturi effect.-Principle of operation :When a gas is injected under pressure through a tube with a decreasing section, it speeds up, generating a pressure drop at the narrowest point .The reduced...
in to a fine spray usually by forcing it under pressure through a nozzle
Nozzle
A nozzle is a device designed to control the direction or characteristics of a fluid flow as it exits an enclosed chamber or pipe via an orifice....
. This spray is usually ignited by an electric spark
Electric spark
An electric spark is a type of electrostatic discharge that occurs when an electric field creates an ionized electrically conductive channel in air producing a brief emission of light and sound. A spark is formed when the electric field strength exceeds the dielectric field strength of air...
with the air being forced through by an electric fan.
Fuel injection
Fuel is injected into the combustion chamber by a spray nozzleSpray nozzle
A spray nozzle is a precision device that facilitates dispersion of liquid into a spray. Nozzles are used for three purposes: to distribute a liquid over an area, to increase liquid surface area, and create impact force on a solid surface...
.
The nozzles are usually supplied with high pressure oil. Because of problems with erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
, and blockage due to lumps in the oil, they need frequent replacement typically every year. Fuel nozzles are usually rated in fuel volume flow per unit time e.g. USGal/h (U.S. Gallons per hour).
A fuel nozzle is characterized by 3 features:
- A flow of 7 bar pump pressure (0.65 (USGal / h))
- The spray characteristic (S)
- The spray angle (60 °)
Alternatively fuel may be passed over a tiny orifice
Orifice
An orifice is any opening, mouth, hole or vent, as of a pipe, plate, or a body.* Body orifice* Orifice plate* Calibrated orifice* Nozzle* Back Orifice-See also:* Choked flow* Needle valve* Venturi effect* Flow measurement...
fed with compressed air. This arrangement is referred to as babington atomiser/nozzle after its inventor. As the oil flows over the nozzle , the fuel needn't be under any great pressure. If the pump can handle such the oil may even contain lumps such as scraps of food. Because it is only compressed air that passes through the orifice hole, such nozzles do not suffer much from erosion.
Oil pump
Oil pump
Oil pump may refer to:*A hydraulic pump, which pressurizes hydraulic fluid in a hydraulic system*An oil pump , a part of the lubrication system that pressurizes motor oil for distribution around the engine...
consists of two parts:
- Gear pump type
This sucks the oil and increases the pressure in the nozzles to 15 bar maximum. Usually a gear pump
Gear pump
A gear pump uses the meshing of gears to pump fluid by displacement. They are one of the most common types of pumps for hydraulic fluid power applications. Gear pumps are also widely used in chemical installations to pump fluid with a certain viscosity...
of the sickle type is used. This type of pump is a simple and therefore cheap pump
Pump
A pump is a device used to move fluids, such as liquids, gases or slurries.A pump displaces a volume by physical or mechanical action. Pumps fall into three major groups: direct lift, displacement, and gravity pumps...
consisting of one or more radical pairs of gear
Gear
A gear is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit torque. Two or more gears working in tandem are called a transmission and can produce a mechanical advantage through a gear ratio and thus may be considered a simple machine....
s and with a very small space between the gears and the pump casing. Gear pumps are used frequently in oil burners because of their simplicity, stability and low price.
- Pressure regulator
To set the heat output of the burner, the rate of fuel delivery via the nozzle must be adjustable. This is often achieved by an adjustable pressure relief valve between the pump and the nozzle. When the set pressure is reaches usually 10 - 11 bar, this valve opens and allows excess oil through a bypass back to the fuel tank or pump suction.
Electromagnetic valve
This enables fuel to be shut off from the sprayer by electrical control. This helps avoid drips when it is inactivated. It also eases the purging of the burner (and any boiler) of fuel mist, during start up, or while restarting after a misfire. If the burner were not purged the oil/air mixture could explode dangerously.Fan
The fan blows air into the combustion chamber. The rotorRotor
Rotor may refer to:*A rotating part of a mechanical device, for example in an electric motor, generator, alternator or pump.In engineering:...
of the fan is powered by a electric motor
Electric motor
An electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...
.
Ignitors
Some oil burners use glow bars which operate much like the glow plugs of a diesel engineMany use high voltage generated by a voltage-step up transformer and use a spark plug to initiate ignition
Photocell
Photoresistor
A photoresistor or light dependent resistor is a resistor whose resistance decreases with increasing incident light intensity. It can also be referred to as a photoconductor or CdS device, from "cadmium sulfide," which is the material from which the device is made and that actually exhibits the...
) detects the flame. The LDR (or Light Dependent Resistor) resistor is an electrical resistor whose value changes by the amount of light
Light
Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...
that it present. The resistance value of an LDR becomes smaller, as the LDR is more and more exposed. The material is usually cadmium
Cadmium
Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low...
sulfide
Sulfide
A sulfide is an anion of sulfur in its lowest oxidation state of 2-. Sulfide is also a slightly archaic term for thioethers, a common type of organosulfur compound that are well known for their bad odors.- Properties :...
, the dark resistance is 1.10 MΩ resistor while the light resistance is about 75-300 Ω. LDR's have a relatively slow response time.
Capacitor start motor
The fan and motor which drives the oil pump is usually acapacitor start motor. It is a vortex shortage tank motor because it also contains a short cage or cage
Cage
Cage may refer to:* Cage , a structure made of mesh, bars or wires, used to confine, contain or protect something. Examples include:** Batting cage, an enclosure for baseball players to practice batting...
holds. The difference with a three-phase motor is in the stator
Stator
The stator is the stationary part of a rotor system, found in an electric generator, electric motor and biological rotors.Depending on the configuration of a spinning electromotive device the stator may act as the field magnet, interacting with the armature to create motion, or it may act as the...
. Where the vortex power motor has three coils aligned at 120° in the stator, the capacitor start motor holds one main winding and one auxiliary winding aligned at 90°. The phase shift of 90° between the main winding and the auxiliary winding is achieved by a connected capacitor which feeds the auxiliary winding and is connected on the single-phase AC mains. The capacitor will achieve a phase shift of 90° between the main and the auxiliary winding, producing an acceptable initial torque. This motor is intended for continuous operation.
Order for starting an oil burner
- Connect the oil burner to a power source.
- Turn off the 'Emergency Shut Down' located on the furnace.
- Purge the burner/boiler with air
- Atomize the fuel oil
- Deflagrate the Atomized fuel oil with a high voltage between two electrodes
- Check with flame detection whether the fuel oil fires up
If the burning does not catch on, the burner will go into alarm and must then be manually reset.
See also
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