Reference
The practice plant
One imaginary plant carries every worked example in the academy: a 6 TPH husk-fired shell boiler at 10.5 kg/cm²g feeding a dryer, a jacketed vessel and a hot-water duty. These are its standing numbers — each one linked to the lesson that establishes it and to every lesson that uses it, so the arithmetic compounds instead of restarting, and drift has nowhere to hide.
Teaching values on public rates (IF97 steam data). Your plant deserves its own card — eight measured, dated numbers on the boiler-house wall. The printable version is in A12.
| Quantity | Value | Derived in | Used in |
|---|---|---|---|
| Boiler | |||
| Boiler rating | 6 TPH F&A | B3 | A1B1B2B6F9 |
| Boiler pressure | 10.5 kg/cm²g | A3 | A1A4A7A9A10B1B3B6B9B10C1C2C3C9+10 more |
| Saturation temperature at 10.5 kg/cm²g | 185 °C | A3 | A7B9C6C7C12 |
| hf at 10.5 kg/cm²g | 188 kcal/kg | A5 | A9B6B9 |
| hfg at 10.5 kg/cm²g | 476 kcal/kg | A6 | A4A7A9A12 |
| hg at 10.5 kg/cm²g | 664 kcal/kg | A5 | A7B2B3D2 |
| vg at 10.5 kg/cm²g | 0.173 m³/kg | A5 | B9C2C3 |
| Typical steaming rate (day average) | 5,000 kg/h | B3 | A9A10B5B6F9F12G5 |
| Actual maximum at 10.5 kg/cm²g, 90 °C feed | 5,630 kg/h | B3 | — |
| Boiler efficiency (GCV) | 75% | B4 | A1B2F1 |
| Users | |||
| Dryer steam demand | 3,500 kg/h | A10 | A8C3D7F11 |
| Dryer pressure | 7 kg/cm²g | A10 | A2A8B10C3C7C9D8F11F12G1 |
| Saturation temperature at 7 kg/cm²g | 170 °C | A8 | — |
| hfg at 7 kg/cm²g | 489 kcal/kg | A10 | — |
| Jacketed vessel — steam supply after its PRS | 3.5 kg/cm²g (148 °C) | C3 | A1A2A3A5A6A7A8A9A10A11A12B9C2C5+12 more |
| Jacketed vessel — jacket at full load (valve wide) | 3.0 kg/cm²g = 3.96 bar a (143 °C) | D3 | A11C11G3 |
| hfg at 3.5 kg/cm²g | 507 kcal/kg | A5 | A1A4A6A10A12B9C13D13F13 |
| vg at 3.5 kg/cm²g | 0.419 m³/kg | A5 | C2C3C5 |
| Vessel warm-up demand | 760 kg/h | A10 | C2C11D3 |
| Vessel holding demand | ~70 kg/h | A10 | B6D3F12 |
| Jacket area | 10 m² | A11 | D1 |
| Jacket U, clean | 500 kcal/h·m²·°C | A11 | — |
| Hot-water calorifier | 8 m³/h, 60 → 85 °C, 3 m² | D13 | G6 |
| Water side | |||
| Feedwater temperature | 90 °C | B5 | A1A5A6B2B3D4E7 |
| Condensate return | 60% | C1 | D6F1 |
| Feed TDS (blended) | 300 ppm | B6 | G4 |
| Boiler TDS limit | 3,500 ppm | B6 | — |
| Blowdown | 9.4% ≈ 470 kg/h | B6 | C1F12 |
| Dryer condensate flash — vented to atmosphere | 465 kg/h (13.3%) | A8 | D7F2F4F11 |
| Dryer condensate flash — harvested at 0.5 kg/cm²g | ~395 kg/h (11.3%) | D7 | B6D13F12 |
| Steam table anchors | |||
| hfg at atmospheric | 539 kcal/kg | A5 | A4A6A8A12B3 |
| vg at atmospheric | 1.694 m³/kg | A5 | — |
| Heat invested per kg of steam (90 °C feed → 10.5 kg/cm²g) | 574 kcal/kg | A1 | A5A6B2B3B5F1G5 |
| Reference states | hf/hfg/hg from 0 °C · the 574 from the 90 °C feed | A5 | — |
| Money | |||
| Running hours | 7,300 h/yr (20 h × 365) | A12 | C7C9D5F9G2 |
| Husk GCV | 3,200 kcal/kg | B2 | A1A6B11E7G5 |
| Husk price (indicative) | ₹2,500/t | B2 | A1A6E7F1 |
| Husk per tonne of steam | 240 kg | B2 | F12 |
| Husk per 20-h day | 29 t (≈ ₹72,000) | A1 | B2B4B11F12 |
| Steam cost, fuel-only | ₹600/t | B2 | A12B5C9C13E7F1 |
| Steam cost, marginal (for savings) | ₹650–700/t (₹675) | F1 | G2 |
| Steam cost, full stack | ₹820/t | F1 | A12 |
| Heat cost on husk | ₹1.04 per 1,000 kcal | B2 | C7 |
| Electricity (teaching rate) | ₹8/kWh | E7 | F6F13 |
| Value of returned condensate | ≈ ₹150/t | D6 | G3 |
Built from content/site.json → practice_plant; the build fails if a lesson types a canon number that disagrees (the drift gate, added after the 2026-09-06 audit).