Energy content of the fuel (e.g., Oil ~10,000, Coal ~4,000).
Thermal efficiency of the boiler unit.
Total heat of steam (Saturated steam at 10 bar ≈ 665 kcal/kg).
Temperature of water entering the boiler.
Total Heat Input:0 kcal/hr
Useful Heat Absorbed:0 kcal/hr
Enthalpy Added to Water:0 kcal/kg
Steam Generation Rate:0 kg/hr
Steam-to-Fuel Ratio:0
function calculateSteamFlow() {
// Get input values
var m_fuel = parseFloat(document.getElementById('fuelConsumption').value);
var gcv = parseFloat(document.getElementById('gcvFuel').value);
var eff = parseFloat(document.getElementById('boilerEfficiency').value);
var h_steam = parseFloat(document.getElementById('steamEnthalpy').value);
var t_feed = parseFloat(document.getElementById('feedwaterTemp').value);
// Validation
if (isNaN(m_fuel) || isNaN(gcv) || isNaN(eff) || isNaN(h_steam) || isNaN(t_feed)) {
alert("Please fill in all fields with valid numbers.");
return;
}
if (eff > 100 || eff <= 0) {
alert("Efficiency must be between 0 and 100.");
return;
}
// Logic
// 1. Calculate Feedwater Enthalpy (h_f)
// Approximation: Specific heat of water is ~1 kcal/kg/°C, so h_f ≈ Temperature in °C
var h_feed = t_feed;
// Check physics constraint
if (h_steam 0) ? (steamFlow / m_fuel) : 0;
// Display Results
document.getElementById('results').style.display = 'block';
document.getElementById('resHeatInput').innerHTML = heatInput.toLocaleString('en-US', {maximumFractionDigits: 0}) + " kcal/hr";
document.getElementById('resUsefulHeat').innerHTML = usefulHeat.toLocaleString('en-US', {maximumFractionDigits: 0}) + " kcal/hr";
document.getElementById('resEnthalpyAdded').innerHTML = enthalpyDiff.toLocaleString('en-US', {maximumFractionDigits: 1}) + " kcal/kg";
document.getElementById('resSteamFlow').innerHTML = steamFlow.toLocaleString('en-US', {maximumFractionDigits: 1}) + " kg/hr";
document.getElementById('resSteamFuelRatio').innerHTML = steamFuelRatio.toLocaleString('en-US', {maximumFractionDigits: 2}) + " : 1″;
}
How to Calculate Steam Flow Rate from a Boiler
Determining the steam flow rate of a boiler is a critical task for plant engineers and operators. It measures how much steam a boiler generates over a specific period, usually expressed in kilograms per hour (kg/hr) or tons per hour (TPH). Accurate calculation helps in monitoring boiler efficiency, fuel consumption, and ensuring the system meets the process heat requirements.
The Indirect Method (Fuel Consumption Basis)
While steam flow meters provide direct readings, they can sometimes be inaccurate or require calibration. The most reliable way to verify steam generation is through calculation based on the energy balance principle. This method uses the fuel consumption rate and the calorific value of the fuel to determine how much energy is being converted into steam.
The core concept is simple: The energy absorbed by the water to become steam is equal to the energy supplied by the fuel, adjusted for the boiler's efficiency.
The Steam Flow Rate Formula
To calculate the steam generation rate, use the following thermodynamic formula:
Steam Flow Rate (ṁs) = (ṁf × GCV × η) / (hg – hf)
Where:
ṁs = Steam Flow Rate (kg/hr)
ṁf = Fuel Consumption Rate (kg/hr)
GCV = Gross Calorific Value of the fuel (kcal/kg)
η = Boiler Efficiency (expressed as a decimal, e.g., 0.85 for 85%)
hg = Enthalpy of Steam (kcal/kg) – determined by boiler pressure
hf = Enthalpy of Feedwater (kcal/kg) – determined by feedwater temperature
Step-by-Step Calculation Example
Let's assume you have a boiler running on heavy fuel oil and you want to calculate the steam output.
Measure Fuel Consumption: The boiler consumes 600 kg/hr of oil.
Determine Fuel Energy: The GCV of the oil is 10,200 kcal/kg.
Check Efficiency: The boiler operates at 88% efficiency (0.88).
Find Steam Enthalpy: At 10 bar pressure, saturated steam has an enthalpy of approx 665 kcal/kg.
Measure Feedwater Temp: The water enters at 85°C (Enthalpy ≈ 85 kcal/kg).
1. Efficiency Monitoring: If your calculated steam flow is significantly higher than what your flow meter reads, your meter might be drifting. Conversely, if the calculation shows you should be producing more steam than you are, your boiler tubes might be scaled, reducing heat transfer.
2. Cost Analysis: Understanding the relationship between fuel input and steam output allows for precise calculation of the steam-to-fuel ratio. A dropping ratio indicates a loss of efficiency and increased operational costs.
3. Capacity Planning: Before expanding production lines, calculating the exact steam flow ensures your current boiler can handle the additional load without dropping pressure.
Tips for Accurate Results
Enthalpy Values: Always use Steam Tables to find the exact enthalpy ($h_g$) corresponding to your boiler's operating pressure.
Units Consistency: Ensure all energy units match. If using kJ/kg for GCV, use kJ/kg for enthalpy. This calculator uses kcal, which is standard in many industrial settings.
Feedwater Temperature: Increasing feedwater temperature by 6°C generally improves boiler efficiency by 1%. Accurate temperature measurement is crucial for the calculation.