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margin: 20px auto;
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border-radius: 12px;
background-color: #ffffff;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
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.calc-header {
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margin-bottom: 25px;
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.calc-header h2 {
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width: 100%;
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font-weight: bold;
cursor: pointer;
transition: background-color 0.3s;
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.calc-btn:hover {
background-color: #004494;
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#scavengerResult {
margin-top: 25px;
padding: 20px;
background-color: #f8f9fa;
border-left: 5px solid #0056b3;
border-radius: 4px;
display: none;
}
.result-value {
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padding-bottom: 5px;
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.calc-table {
width: 100%;
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.calc-table th, .calc-table td {
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.calc-table th {
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Feedwater Flow Rate (m³/hr)
Dissolved Oxygen Level (ppb – Parts Per Billion)
Scavenger Type (Stoichiometric Ratio)
Sodium Sulfite (7.88:1)
Hydrazine (1.0:1)
DEHA (1.3:1)
Carbohydrazide (3.0:1)
Custom Ratio
Custom Stoichiometric Ratio
Desired Excess/Residual (ppm)
Chemical Product Concentration (%)
Calculate Dosing Rate
Required Chemical Dosing Rate:
—
Understanding Oxygen Scavenger Dosing
Oxygen scavengers are essential chemical agents used in boiler water treatment to remove residual dissolved oxygen. Oxygen in boiler systems leads to rapid pitting and localized corrosion, which can cause tube failure in a very short period. This calculator helps plant engineers determine the exact amount of chemical required based on water flow and oxygen levels.
The Calculation Formula
The dosing rate is determined by three main factors: the oxygen to be removed, the desired chemical residual for safety, and the concentration of the product used. The formula used is:
Dose (g/hr) = [Flow (m³/hr) × ((O2 ppb / 1000 × Ratio) + Residual ppm)] / (Strength % / 100)
Common Stoichiometric Ratios
Chemical
Ratio (Part per 1 Part O2)
Typical Application
Sodium Sulfite
7.88
Low to medium pressure boilers
Hydrazine
1.00
High pressure/Nuclear (carcinogenic)
DEHA
1.30
Steam condensate systems
Carbohydrazide
3.00
Closed loops/High pressure
Practical Example
If you have a boiler feedwater flow of 20 m³/hr with 100 ppb of dissolved oxygen entering the deaerator, and you want a 30 ppm residual of Sodium Sulfite (using a 10% solution):
Oxygen Demand: 100 ppb = 0.1 ppm. 0.1 × 7.88 = 0.788 ppm demand.Total Demand: 0.788 (demand) + 30 (residual) = 30.788 ppm.Total Mass: 20 m³/hr × 30.788 g/m³ = 615.76 g/hr of pure sulfite.Product Dose: 615.76 / 0.10 = 6,157.6 g/hr or 6.16 kg/hr of product.
function calculateDosing() {
var flow = parseFloat(document.getElementById('flowRate').value);
var o2 = parseFloat(document.getElementById('dissolvedO2').value);
var residual = parseFloat(document.getElementById('targetResidual').value);
var strength = parseFloat(document.getElementById('productStrength').value);
var scavengerType = document.getElementById('scavengerType').value;
var ratio = 0;
if (scavengerType === "custom") {
ratio = parseFloat(document.getElementById('customRatio').value);
} else {
ratio = parseFloat(scavengerType);
}
if (isNaN(flow) || isNaN(o2) || isNaN(residual) || isNaN(strength) || isNaN(ratio)) {
alert("Please enter valid numerical values in all fields.");
return;
}
if (strength 100) {
alert("Product concentration must be between 0 and 100%.");
return;
}
// Calculation Logic:
// 1. Convert O2 ppb to ppm (mg/L)
var o2ppm = o2 / 1000;
// 2. Calculate chemical demand for O2 removal (ppm)
var demand = o2ppm * ratio;
// 3. Total concentration needed in water (ppm)
var totalConcentrationNeeded = demand + residual;
// 4. Calculate total grams per hour of active chemical
// Flow (m3/hr) * Concentration (g/m3) -> 1 ppm = 1 g/m3
var activeGramsPerHour = flow * totalConcentrationNeeded;
// 5. Adjust for product strength
var productGramsPerHour = activeGramsPerHour / (strength / 100);
var resultDisplay = document.getElementById('scavengerResult');
var rateOutput = document.getElementById('finalRate');
var breakdownOutput = document.getElementById('calculationBreakdown');
resultDisplay.style.display = 'block';
if (productGramsPerHour >= 1000) {
var kgRate = (productGramsPerHour / 1000).toFixed(3);
rateOutput.innerHTML = kgRate + " kg/hr";
} else {
rateOutput.innerHTML = productGramsPerHour.toFixed(2) + " g/hr";
}
breakdownOutput.innerHTML = "Logic: " + demand.toFixed(3) + " ppm (O2 Demand) + " + residual + " ppm (Residual) = " + totalConcentrationNeeded.toFixed(3) + " ppm total active concentration.";
}