Fuel Oil Burners

Fuel Oil Burner Fuel Oil Burner must be capable of properly atomizing the oil within a furnace of minimum dimensions. The burner must be producing efficient firing over a wide range of oil flow rates. The burner must be able to rapidly respond to changes of load to meet maneuvering requirements.

Fuel Oil Burner Before combustions can take place the fuel must be changed from a liquid to a atomized condition and simultaneously mixed with sufficient air. The burner assembly consists of two parts: the atomizer which serves to deliver a flow of atomized oil to the furnace, and the register which serves to supply a flow of air to the furnace.

Turndown Ratio Turndown Ratio = Max oil flow / Min oil flow Turndown Ratio = (Max Pressure / Min Pressure)0.5 If the Fuel oil pump output is 300 psi and the minimum pressure for atomization is 100 psi Turndown Ratio = (300/100)0.5 = 1.732

Burner Systems Straight Mechanical type of atomizer consists of an atomizer which converts the potential energy of the oil pressure into a flow of atomized oil particles. The register is designed to introduce and mix the air with the oil spray produced by the atomizer.

Mechanical Type Burner The sprayer plate transforms the solid stream of oil under high pressure into a cone of fine fog particles by means of tangential slots leading to the whirling chamber and outlet orifice.

Mechanical Type Burner Sprayer plates are designated by four digit numerals, of which the first two digits represent the size of the drill used in making the orifice in the sprayer plate, and the last two digits represent ten times the ratio of the total cross sectional area of the tangential slots to the cross sectional area of the orifice.

Mechanical Type Burner The sprayer plate designation number is stamped on the face of the plate by the manufacturer. It should be noted having the smaller numbers have the larger capacity, since the smaller number of the drill, the larger diameter drill which is used to make the orifice hole. The second number on the burner tip is ten times the ratio of the area of the orifice.

Mechanical Type Burner This ratio determines the angle of the cone. It should be noted that for a particular orifice, the larger the angle of the cone, the shallower the oil spray will be in the furnace. The capacity of the burner is the amount of oil, in pounds per hour under specific viscosity and pressure conditions.

Return Flow Burner Systems Return Flow type of atomizer functions with a constant pressure oil supply, and the atomizer barrel contains a passage which permits a portion of the oil to return to the fuel oil settling tank. The firing rate is varied by regulating the control valve in the return line.

Return Flow Burner Systems This type of burner is capable of producing a more uniform fuel oil distribution and a complete atomization pattern over a much wider range of load applications than the straight mechanical type of oil burner.

Steam Atomized Burner Systems Steam Atomizing type of atomizer utilizes a flow of steam which mixes in the atomizer tip with the oil flow. A portion of the energy in the steam serves to break up the oil particles and better atomization results.

Steam Atomized Burner Systems This type of unit provides for a wide range of firing rates without changing the sprayer plates.

8Y - 47 – 55 – 50 – 80 - H 8 – Number of Jets Y – Type 47 – Drill size of exit 55 – Drill size of Steam hole 50 – Drill size of Oil hole 80 - Angle H – High Carbon Steel

Air Registers Air registers form the second part of the burner assembly and performs the function of delivering the air to the furnace required for the combustion of fuel. It also serves to distribute the air in such a manner that it mixes intimately with the oil at it leaves the atomizer.

Air Registers To a limited extent the air register may be used to perform the secondary function of controlling the amount and velocity of air entering the furnace. This control is accomplished primarily by regulating the dampers or by varying the blower speed to control the rate or air discharge of the force draft system

Air Registers Air registers may be either conical or cylindrical. The burner opening is at right angles to the face of the front wall. The register door arrangement may be classified as axial door, radial door or a combination of both.

Air Registers Air registers when open direct air flow from the double casing into and around the cone of fog like oil particles produced by the atomizer. When closed, they prevent air from entering the furnace. When closed, they are not air tight.

Air Registers Present air registers employing pressure atomizers, consist of two principle parts the diffuser and air foils. The use of two separate air streams. The primary thru the diffuser. Secondary thru the air foils has enabled capacity and flexibility to be increased greatly..

Air Registers The diffuser institutes primary mixing of the oil droplets with air and prevents blowing of the flame from the atomizer The air foils guide the major quantity of air to mix with oil particles, after they leave the diffuser and to envelop the flame.

Air Registers The construction of the diffuser, air foils and register doors is such that the oil and air are given a whirling motion in the clockwise or counter-clockwise direction.