Calculating conveyor belt capacity is essential for optimizing material handling processes in various industries. The capacity, typically measured in tons per hour (TPH), is determined by several key factors. The fundamental formula for this calculation is:
Capacity (TPH) = Belt Speed (ft/min) x Load Cross-Sectional Area (ft²) x Material Density (lb/ft³) x 60 min/hr / 2000 lb/ton.
Key parameters in conveyor belt capacity calculation
To accurately calculate the capacity, you need to understand the following parameters:
- Belt speed (V): this is the speed at which the conveyor belt is moving, usually measured in feet per minute (FPM) or meters per second (m/s).
- Belt width (W): the width of the conveyor belt, measured in inches or meters. A wider belt can generally carry more material.
- Material density (ρ): also known as bulk density, this is the weight of the material per unit of volume, typically in pounds per cubic foot (lb/ft³) or kilograms per cubic meter (kg/m³).
- Load cross-sectional area (A): this is the area of the material on a cross-section of the belt, measured in square feet (ft²) or square meters (m²). It is influenced by the belt’s shape (flat or troughed) and the material’s surcharge angle.
- Surcharge angle: this is the angle that the material naturally forms on the moving belt. It is usually 5 to 15 degrees less than the material’s angle of repose. The angle of repose is the angle a granular material makes with the horizontal when piled.
- Troughing angle: for troughed conveyors, this is the angle of the side idler rolls. Common troughing angles are 20, 35, and 45 degrees. A deeper trough allows for a larger cross-sectional area.
How to calculate conveyor belt capacity: a step-by-step guide
Determine the load cross-sectional area (A): This is a critical and often complex part of the calculation.
- For a flat belt: the cross-sectional area is approximated by the width of the material on the belt multiplied by the average height of the material.
- For a troughed belt: the calculation is more involved as it includes the area of the trapezoid formed by the troughing idlers and the area of the circular segment formed by the surcharge angle.
Gather the other key parameters: measure or find the specifications for the belt speed.
- Determine the bulk density of the material being conveyed. This information is often available in engineering handbooks or from the material supplier.
Apply the formula: Once you have all the necessary values, plug them into the capacity formula.
- Ensure that your units are consistent. If you are using a mix of units (e.g., belt speed in ft/min and material density in kg/m³), you will need to convert them to a consistent system before calculating.
Example calculation
Let’s consider a scenario with the following parameters:
- Belt Speed: 300 ft/min
- Load Cross-Sectional Area: 0.5 ft²
- Material Density: 100 lb/ft³
Capacity (TPH) = 300 ft/min x 0.5 ft² x 100 lb/ft³ x 60 min/hr / 2000 lb/ton Capacity (TPH) = 450 TPH Therefore, the conveyor belt has a capacity of 450 tons per hour.
Additional factors influencing conveyor belt capacity
Several other factors can affect the actual capacity of a conveyor belt:
- Incline angle: if the conveyor is inclined, the effective cross-sectional area of the material may be reduced, thus lowering the capacity.
- Material characteristics: the size, shape, and flowability of the material can impact how it sits on the belt and, consequently, the surcharge angle and cross-sectional area.
- Loading conditions: the way material is fed onto the belt can affect the load distribution and, therefore, the carrying capacity.
- Idler spacing: the distance between the idler rollers can influence belt sag, which can affect the material’s cross-sectional area.
