Engineering Data
Engineering Publication by Preferred Utilities
Useful Combustion Engineering Data
Fuel Oil Handling System Design
A well thought design is the key to a good Fuel Oil Handling System. To learn more about designing a proper fuel system, click on the following link:
Fuel Oil Handling System Design.PDF
Characteristics of Typical Fuel Oils
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(View the Characteristics of Typical Fuel Oils Table)
Grade of Fuel Oil: The American Society for Testing and Materials (ASTM) has standardized on five basic grades, designated as Nos. 1, 2, 4, 5, and 6. Grades Nos. 4 and 5 are subdivided into light and heavy. The oils viscosity determines into which subdivision it is classed.
Percent by Weight: The fuels elements are expressed as a percentage of the fuels total weight.
Gravity: The unit weight of a liquid in lbs./gal. is the density of that liquid. The ratio of unit weight, or density of any liquid to the density of water is the Specific Gravity (SG) of that liquid. The density of water at 60 F is 8.328 lbs. The oil industry uses the API Gravity or Gravity scale. The relationship between API Gravity and specific gravity is as follows:
Degrees API Gravity = (141.5 SG at 60 F) - 131.5.
Thus, an oil with a specific gravity of 1.0 would have an API Gravity of (141.5 1.0)-131.5 = 10.0 degrees API.
Pour Point: The Pour Point temperature is 5 F. above the point where the oil congeals into a semi-fluid or a solid.
Viscosity: Viscosity is the measure of the oils resistance to flow, or simply expressed as its thickness or thinness. Kinematic Viscosity is usually given in terms of Centistokes, SSU (Saybolt Seconds Universal at 100 F) or SSF (Saybolt Seconds Furol at 122 F). Absolute viscosity is given in terms of Centipoises and can be calculated from Kinematic Viscosity as follows:
Kinematic viscosity (centistokes) = Absolute viscosity (centipoises) density (g./cm.3)
BS&W or Bottom Sediments and Water: BS&W are non-petroleum contaminates sometimes found in fuel oils. Some of the problems that can be associated with high levels of BS&W are erratic and unsteady combustion, sparking and spitting of the flame, flashback, plugging of burner tips and screens, loss of heat release and/or
erosion of burner tips and mechanical parts.
HHV or Higher Heating Value: The HHV is the total heat content of a given measure of oil including the latent heat of evaporation of the water vapor formed during combustion. The Lower Heating Value assumes that the latent heat is not recovered because the water vapor is not condensed. When performing calculations for combustion or appliance sizing, always use the HHV.
Contents of Horizontal Cylindrical Tanks
Percent of Total Volume Filled vs. Percent of Liquid Depth
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(View the Percent of Total Volume Filled vs. Percent of Liquid Depth Table)
Note: These figures apply only to tanks with flat ends, not to tanks with dished ends. For greater accuracy, consult the stick chard prepared by the tank manufacturer.
Example
A 12 foot (144") diameter tank has 98.5 inches of oil by the stick. Dividing the depth (98.5") by the tank inside diameter (144"), yields 68% tank depth. From the table, the volume is 72.4% of capacity. For a 20,000 gallon tank, the contents would be approximately 14,480 gallons.
Volumetric Corrections for Fuel Oil
Due to the thermal expansion and contraction of petroleum products, all are purchased and sold based on a volume at 60 F. Therefore, all petroleum products are corrected to this temperature by using a correction factor. This factor converts quantities of oil at different temperatures to a comparable volume at a standard temperature.
When mechanical flow meters or differential pressure type flow elements are used for invoicing or efficiency calculations, the reading must be temperature compensated to provide an accurate reading.
To convert gross gallons at the loading and unloading temperature to net gallons at 60 F, the temperature, the API Gravity of the oil and the coefficient of expansion factor must be known. A rough approximation of net gallons can be obtained from the equation provided. For a more precise conversion consult the factory or the Manual of Petroleum Measurement Standards jointly issued by the American Society for Testing and Materials, the American Petroleum Institute and the Institute of Petroleum. Included in these Standards are Table 5B (Correction of Observed API Gravity to API Gravity at 60 F) and Table 6B (Correction of Volume to 60 F against API Gravity at 60 F). Table 5B is used to correct the observed gravity and temperature to gravity at 60 F. Table 6B is used to obtain the coefficient of expansion factor from the observed gravity and temperature and is used to convert gross to net gallons.
Rough Approximation Method
Correction Factor = 1 - (ΔT x Multiplier)
Oil API
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Multiplier
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Example:
Oil having 17 API is clocked through a positive displacement meter at 565 GPH. The oil is 190 F at the meter. Find the corrected (i.e. 60 F) volumetric flow.
190 - 60 = 130 T
Correction Factor = 1 - (130 x 0.0004) = 0.9480
Corrected Volumetric Flow = 565 x 0.9480 = 535.62 GPH
Energy Required to Heat #6 Oil
Electric
Watts = 1.25 X GPH X ΔT (F)
Amps (single phase) = watts/volts
Amps (three phase) = watts/(volts X 1.73)
Example
To heat 600 GPH of #6 oil from 90 F (32 C) to 150 F (65.5 C):
ΔT=60 F (15.5 C)
Watts = 1.25 X 600 X 60 = 45,000
KW = 45
Amps at 460/3/60 = 56.5
Steam
lbs/hr steam = (lbs/hr oil X ΔT) / 1920 (#6 oil & 5 psi steam)
lbs/hr steam = (gph X lb/gal X ΔT) / 1920
Example
To heat 600 GPH of #6 oil from 90F (32C) to 150F (65.5C):
lbs/hr steam = (600 X 8 X 60) / 1920 = 150
Unit Conversion Tables
Pressure or Force Per Unit Area
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Power or Rate of Doing Work
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Boiler Horsepower and Quantity of Fuel Oil Burned
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Dimensions of Welded and Seamless Pipe
Carbon and Alloy Steels
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(View the Carbon and Alloy Steels Table)
Typical Fuel Oils Temperature-Viscosity Curves
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(View the Typical Fuel Oils Temperature-Viscosity Curves Diagram)
The above chart should be used as a guide to determine the proper or minimum temperature to be maintained in oil storage tanks and pipe lines to insure reliable oil pumping; and to dictate the required fuel temperature to satisfy the viscosity required for proper burner atomization.
When using the chart for determining the proper oil temperature for atomization, the operator should obtain from his fuel oil supplier (or by an independent laboratory analysis) the viscosity of the fuel expressed in Centistokes, Saybolt Seconds Universal (SSU) or Saybolt Seconds Furol units. (NOTE: All expressed referenced to a specific temperature) With this information the particular fuel oil viscosity line can be located on the chart by either drawing it as a parallel to the diagonal lines or using the next highest diagonal line as printed. At the point where this diagonal line crosses the horizontal line marked with the burner manufacturers recommended viscosity, read vertically down and note the proper temperature at which this oil should be burned.
When using the chart as a basis for the design of storage tank and piping layouts, a similar minimum temperature can be determined by reading vertically down from that point where the diagonal line crosses the horizontal line marked Limit of Easy Pumpability. For example, a fuel oil having a viscosity of 30 Centistokes at 154 F should be kept in storage and in the pipe lines at a minimum temperature of 99.5 F to assure reliable pumping of the fuel.
Simplex Strainer Model No. 72
Approximate Strainer Pressure Drops
in Inches of Mercury (1Hg 0.49 PSI = 13.622 H2O)
Number 2 Fuel Oil (with clean 40 mesh baskets)
Number 6 Fuel Oil at 5000 SSU (with clean 3/64 perforated baskets)
*** Indicates insignificant pressure loss
### Indicates excessive pressure loss
Simplex Strainer Model No. 53
Approximate Strainer Pressure Drops
in Inches of Mercury (1Hg = 0.49 PSI = 13.622 H2O)
Number 2 Fuel Oil (with clean 40 mesh baskets)
Number 6 Fuel Oil at 5000 SSU (with clean 3/64 perforated baskets)
*** Indicates insignificant pressure loss
### Indicates excessive pressure loss
Pressure Gauge Terminology
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Flow of Water through Schedule 40 Steel Pipe
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Carbon and Alloy Steel Pipe Data
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