Calculating the Heating Surface Area of a Fire-Tube Boiler Given 10 Ton/hr Fuel Wood Capacity and 10 Bar Operating Pressure
Understanding how to calculate the heating surface area of a fire-tube boiler is crucial for ensuring optimal performance and efficiency. This guide will walk you through a step-by-step process to determine this key parameter. Whether your boiler specification is available on the boiler plate or needs to be manually measured, this approach will help you find the required heating surface area.
Step 1: Determine Boiler Capacity
First, confirm the boiler's steam capacity. You mentioned that the boiler capacity is 10 tons/hr (fuel wood). This value indicates the amount of steam the boiler will produce per hour.
Step 2: Convert Capacity to kW
To proceed with the calculation, convert the boiler's capacity from tons/hr to kilowatts (kW). The conversion factor is as follows:
1 ton of steam per hour is equivalent to approximately 0.278 kW.
Therefore, for a 10 ton/hr boiler:
10 tons/hr 10 × 0.278 kW 2.78 kW
Step 3: Estimate the Heat Transfer Coefficient
The heat transfer coefficient is a key factor in determining the heating surface area. For fire-tube boilers, the heat transfer coefficient can vary based on the design and operating conditions. A common approach is to use a heat transfer coefficient of around 1000 to 1500 W/m2·°C for water and steam.
Step 4: Determine Temperature Difference
To calculate the temperature difference, you need to know the inlet and outlet temperatures of the boiler. For example, if water enters at 80°C and steam exits at 180°C, the average temperature difference can be approximated as:
ΔT T_{steam} - T_{water} 180°C - 80°C 100°C
Step 5: Calculate Heating Surface Area
The basic formula for calculating the heating surface area (A) is:
A (frac{Q}{U × ΔT})
Where:
Q is the heat transfer rate in kW. U is the overall heat transfer coefficient in W/m2·°C. ΔT is the temperature difference in °C.Assuming Q 2.78 kW or 2780 W and using U 1200 W/m2·°C, the calculation would be:
A (frac{2780 W}{1200 W/m^2·°C × 100°C} (frac{2780}{120000} approx 0.0232 m^2)
Step 6: Adjust for Design Considerations
In practical applications, additional factors like fouling, safety margins, and boiler design specifics must be considered. It is common to increase the calculated area by 10-20% to account for these factors.
Conclusion
The calculated heating surface area is a starting point. For accurate designs, consulting boiler design standards, manufacturer specifications, and using detailed thermodynamic calculations is recommended. It is also advisable to consult a thermal engineer or boiler manufacturer to tailor designs to specific operational conditions.