Fuel Oil Pumps

Overview

Engineering reference data for Fuel Oil Pumps in combustion engineering.

Key Formulas

Heat Release

$Q = \dot{m} \cdot HV$

Fuel energy release rate.

Air-Fuel Ratio

$AF = \frac{m_{air}}{m_{fuel}}$

Mass of air per mass of fuel.

Excess Air

$EA = \frac{O_2}{21 - O_2} \times 100\%$

From flue gas oxygen measurement.

Variables

Suction Line Vacuum Estimation

The performance of fuel oil pumps is often constrained by the suction side. High vacuum levels can cause light fuel fractions to evaporate, leading to pump choking. The total vacuum in the suction line can be approximated based on several factors:

• Vertical Lift: Each foot of lift contributes approximately 1 inch of vacuum.
• Elbows: Each 90° elbow adds about 1 inch of vacuum.
• Horizontal Pipe: For 3/8 inch horizontal suction pipe, vacuum is estimated at 1 inch per 10 feet or 1 inch per 20 feet, depending on the system layout.

Vacuum Contribution Factors

The total vacuum $V$ (in inches) can be estimated with the formula:

$V = L + E + \frac{P_{10}}{10} + \frac{P_{20}}{20}$

Where:

• $L$ = vertical lift in feet
• $E$ = number of 90° elbows
• $P_{10}$ = length in feet of 3/8 inch horizontal suction pipe with a vacuum rate of 1 inch per 10 feet
• $P_{20}$ = length in feet of 3/8 inch horizontal suction pipe with a vacuum rate of 1 inch per 20 feet

Note: These values are rough estimates; actual vacuum may vary with fuel viscosity, temperature, and pipe conditions. Single-stage pumps are typically used for low vacuum (5–10 inches), while two-stage pumps handle medium vacuum (10–15 inches). For higher vacuum, separate lifting pumps and dedicated reservoirs are recommended.

References

• Original Source