Ask a plant manager where last month's money went and you get a ledger to the rupee. Ask where last month's steam went and you usually get a shrug toward the dryer. The steam balance is the missing ledger: one drawing that accounts for every kilogram per hour — generation on one side, every consumer, loss and vent on the other, arranged by pressure level. Lesson F1 priced the kilogram; this lesson is the drawing that shows where they all go. Most plants have never made it — which is why headers vent, why nobody can say what the dryer actually takes, and why recovery projects get sized on folklore.
Step zero, not step five
Every serious move this faculty teaches stands on the balance. Lesson F2's eight wastes assume you know the flows you are comparing against; lesson F3's audit method spends its first phase building one. And no recovery hardware can be sized without it: a flash project (D7) needs the condensate flows, an accumulator (B9) needs the swing between average and peak, a thermocompressor (F4) needs the steady LP surplus, and a back-pressure turbine (F13) lives or dies on the steady flow crossing between two headers. An imbalance between pressure levels — one header starving while another lifts its safety valve — is invisible on the plant floor and obvious on the drawing.
A morning, a notebook, no meters yet
The first balance costs nothing but honesty. Generation comes from the fuel side: lesson B2's lorry-count arithmetic — 29 t of husk a day ÷ 240 kg per tonne of steam ≈ 120 t of steam a day. Across the 20-hour run that is ~6,000 kg/h at steady fire; allow for the low-fire hours and the practice plant's real average is the familiar ~5,000 kg/h (lesson B3's derate thinking, applied to the clock). Consumers come from nameplates and lesson A10's m·cp·ΔT estimates. Losses come from the walk: leaks (C9), bare pipe (C7), vents (D7). Then the discipline that makes the drawing trustworthy, borrowed straight from F3: every number carries an M or an E — measured or estimated. An unlabelled number gets believed like a measurement, and that is how mistakes get automated.
Finally, close it: generation minus everything accounted. The remainder is not an embarrassment to be rounded away — the closing gap is the first finding. It is the sum of everything you cannot name: unlisted users, failed traps (G2), leaks not yet walked, a vent nobody counts. A first balance that closes within 5–10% is working knowledge; a 15% gap is a project list wearing a percentage sign.
One morning with lorry receipts, nameplates and A10's arithmetic:
Read what the letters say before the numbers: one M in a column of Es. The balance closes — and it also just wrote the instrumentation plan (the biggest Es earn meters first, lesson D8) and the survey plan (the 220 goes to lesson G2's trap survey and C9's leak walk before any capex is proposed).
The pressure-level view
Redraw the same numbers as horizontal levels — 10.5, 7, 3.5, 0.5 kg/cm²g — and the drawing starts answering design questions. What crosses between levels today is two reducing stations, working for nothing; that is exactly the flow a back-pressure turbine could cross for power (F13), or a thermocompressor could climb the other way (F4). What leaves each level should only ever be process condensing — so every vent that appears on the drawing is a question with a rupee value attached, and the deaerator's tuned wisp (B5) should be the only one left standing. The practice plant's 0.5-level is fed by recovered flash; before lesson D7's project, that same line read "vent, 465, ₹18–19 lakh" — the balance is where that kind of line refuses to hide.
- Draw version one in a morning: lorry counts (B2), nameplates, m·cp·ΔT (A10). Label every number M or E — the letters matter more than the digits.
- Walk every vent on the drawing with A8's arithmetic in hand. A vent without a rupee value next to it isn't finished.
- Put the next flow meter where the balance leans hardest on an E — that is lesson D8's shopping list, written by the drawing.
- Redraw seasonally and after every project, and date each revision. An undated balance is folklore with arrows.
- Gap above ~10%? Book the trap survey (G2) and the leak walk (C9) before proposing capital for anything.
- Generation on one side, every consumer, loss and vent on the other, by pressure level — with M or E on every number.
- The closing gap is not an error to hide; it is the first finding, and it has a rupee value.
- Blowdown is water and recovered flash is recycled — neither is a steam consumer.
- No flash project, accumulator, thermocompressor or turbine gets sized without this drawing.
Walk into the control room of any power station and somewhere near the door hangs the heat-balance diagram — every flow, every pressure level, framed like a family photograph. Utilities learned a century ago that you can only run what you can draw, and a station's balance is redrawn for every ageing survey and every retrofit. Process industry runs the same physics at smaller scale and mostly never picked up the habit — which is why an experienced auditor's first question on site is not "where are your meters?" but "may I see your drawing?" — and why the answer to the second question predicts the findings of the first.
FAQ
How accurate does a first steam balance need to be?
Closing within 5–10% makes it working knowledge — good enough to rank projects and place meters. Chasing the last percent with estimates is wasted polish: the point of version one is to expose the big unknowns, and the closing gap itself is a finding with a rupee value, not an error to be massaged to zero.
We have no steam meters at all. Can we still draw one?
Yes — that is exactly who the morning method is for. Generation comes from the fuel side (lorry counts and lesson B2's kg-per-tonne), consumers from nameplates and lesson A10's m·cp·ΔT arithmetic, losses from the walk. Label everything E, close it, and let the drawing tell you which one or two meters would firm it up most (lesson D8). Meters refine a balance; they cannot replace it.
Is the steam balance the same as the boiler heat balance?
No, and you need both. Lesson B4's heat balance is the boiler's own efficiency ledger, in kilocalories — where the fuel's heat went. The steam balance is the plant's flow ledger, in kg/h — where the steam went after the boiler did its job. A perfect boiler feeding a venting header scores 78% on one drawing and fails the other.
What does a header imbalance actually look like on the plant floor?
A reducing station that never stops passing while the low-pressure header's safety valve weeps; or an accumulator-shaped complaint — the boiler hunting between high fire and low fire as batch loads slam on and off (lesson B9). On the drawing it is unmissable: more steam crossing between levels than the lower level's consumers can explain. That crossing flow is also the first number a turbine or thermocompressor proposal needs.
Why doesn't blowdown appear among the steam consumers?
Because it never became steam. Blowdown leaves the boiler as hot water, sized by lesson B6's solids balance — so it belongs on the feedwater side: feed flow ≈ steam out + blowdown out. Subtracting it from steam generation double-counts it and quietly corrupts every downstream number by ten percent — one of the two classic balance-wrecking mistakes, alongside counting recovered flash as boiler output.
Check yourself
Five quick questions on this lesson. No marks, no records — the score is for you.