Boiler Heat Balance, Blowdown Loss & Flash Recovery

The formula

This is the expression the tool evaluates. Every term is named underneath, with the unit it must be supplied in.

How the result is derived

Step by step, from the values you type to the figure on screen.

1. The 13 inputs are read from the form on every keystroke: Steam Demand, Steam Enthalpy, Feedwater Temperature, Specific Heat of Water, Blowdown Rate, Blowdown Enthalpy, Boiler Efficiency, Fuel Calorific Value, Fuel Cost, Condensate Returned, Condensate Enthalpy, Enthalpy at Flash Pressure and Latent Heat at Flash Pressure.
2. Each value is checked against the accepted range in the input table below. A value outside its range stops the calculation rather than producing a misleading figure — the results blank out and a message appears.
3. The validated values are substituted into the expression above, which resolves Cost per Tonne of Steam together with every supporting figure in one pass — no value is carried over from a previous entry.
4. The supporting outputs — Feedwater Enthalpy, Heat Added per kg of Steam, Boiler Heat Load, Blowdown Flow, Blowdown Heat Loss, Blowdown Share of Fuel, Fuel Energy Input, Fuel Consumption, Fuel Cost, Make-Up Water, Flash Fraction of Condensate and Flash Steam Recoverable — come from the same pass, so they always describe the same case as the headline figure.
5. Results are rounded for display only. The full-precision value is used throughout the chain, so reading a rounded intermediate figure back into the tool by hand can shift the last digit.

What each input means

Where to read each value on the floor, the unit it must be in, and the range the tool accepts.

What the tool returns

The headline figure and every supporting value it is built from.

Worked example

The tool loads with this case already solved — the Cost per Tonne of Steam shown above is its answer. Change one value and the difference from this baseline is the sensitivity of the result to that variable.

How to use it

1. Work through the input groups in order — Steam Demand, Boiler and Condensate & Flash. The defaults are a realistic case, so you can change one value at a time and watch what moves.
2. There is no calculate button. Every figure recalculates as you type or drag, which is what makes this usable for a what-if sweep rather than a single answer.
3. Read Cost per Tonne of Steam in the dark results panel — that is the headline figure, expressed in cost/t.
4. Check the supporting rows underneath (Feedwater Enthalpy, Heat Added per kg of Steam, Boiler Heat Load, Blowdown Flow, Blowdown Heat Loss, Blowdown Share of Fuel, Fuel Energy Input, Fuel Consumption, Fuel Cost, Make-Up Water, Flash Fraction of Condensate and Flash Steam Recoverable) before acting on the headline — they are where an implausible input usually shows itself first.
5. Reset to defaults returns every field to the reference case, which is the quickest way to check whether a surprising result came from the tool or from an input you had changed earlier.

Where this is used

• Process planning — establishing Cost per Tonne of Steam before a trial is booked, so machine time and material in Quality Systems, Traceability, Utilities & Factory Decisions are committed against a calculated figure rather than an estimate.
• Costing and quotation — Cost per Tonne of Steam is an input to the cost sheet, and quoting from a worked number rather than a remembered one is what keeps a margin intact.
• Troubleshooting — when the floor result drifts from plan, entering the measured values (starting with Steam Demand) shows how much of the gap in Cost per Tonne of Steam each variable explains.
• Teaching and study — the accepted ranges bracket normal Quality Systems, Traceability, Utilities & Factory Decisions practice, so moving one variable at a time shows the shape of the relationship rather than a single answer.

Assumptions and limits

• This is a steady-state balance on the boiler and says nothing about the distribution system, where most of the losses a textile mill actually has are found: uninsulated line, failed traps passing live steam, and a plant carrying far more header pressure than any user needs. A mill with an excellent boiler figure and poor traps is burning fuel this calculation cannot see. Blowdown here is continuous surface blowdown at a declared rate; intermittent bottom blowdown is additional and is set by sludge rather than by conductivity, and neither should be reduced on the strength of a heat figure alone - blowdown exists to control dissolved solids, and cutting it to save the fraction of a percent shown here buys carryover, foaming and eventually tube damage. The honest way to reduce it is better feedwater. Flash steam is reported as recoverable rather than recovered: capturing it needs a flash vessel and a genuine use at the lower pressure, and a plant with no low-pressure demand cannot use it however much of it there is. Fuel cost per tonne of steam is the number worth carrying into every other calculation on the site, since it converts a thermal saving anywhere into money.
• Every input is bounded to the range normal practice occupies (Steam Demand 100 to 100000 kg/h, Steam Enthalpy 2600 to 3100 kJ/kg and Feedwater Temperature 10 to 180 degC, and so on for the rest). Those bounds are guard rails against typing errors, not a claim that the formula fails one unit outside them.
• The calculation is deterministic: the same inputs always give the same result. It carries no allowance for machine condition, operator skill, ambient conditions or lot-to-lot material variation unless an input above explicitly represents one.
• Nothing is sent anywhere. The maths runs in your browser, so the numbers you type never leave the page.

Questions people ask