Does this include reheat or extractions?

No. This is a single-pressure expansion screen. Reheat and multi-extraction balances need OEM / process-simulator heat balances.

How is heat rate defined here?

Screening heat rate ≈ SSC · (h₁ − h_fw) with h_fw = hf(P₂) condensate enthalpy — not a full plant heat-rate guarantee.

When is exhaust moisture a concern?

Above about 12% moisture, last-stage (L-0) blade erosion risk rises — raise exhaust pressure or inlet temperature, or confirm OEM wetness limits.

Steam Turbine Power Output & Specific Steam Consumption Calculator (ASME PTC 6 / IAPWS-IF97) — 1200 psia · 950 °F · 200 klb/h

Engineering Reference & ASME Code Basis

1. Core Formula & Variable Definitions

ASME PTC 6-2004 (R2014) — Steam Turbines Performance Test Codes · IAPWS-IF97 — Industrial Formulation 1997 for Water and Steam (Regions 1, 2, 4)

h_2s = f_IF97(P₂, s₁) · Δh_ideal = h₁ − h_2s

h₂ = h₁ − η_is·Δh_ideal · W_elec = ṁ·(h₁−h₂)·η_mech·η_gen

SSC = ṁ / W_elec · Heat rate ≈ SSC·(h₁ − h_fw)

ASME PTC 6 · IAPWS-IF97 Region 1 / 2 / 4 — single-pressure screening (no reheat / extraction)

Standard ASME PTC 6Steam IAPWS-IF97Hero W_elecSSC kg/kWh · lb/kWh

Inlet state from Region 2 (P₁, T₁). Isentropic exhaust from (P₂, s₁) on the wet dome or Region 2. Feedwater enthalpy for heat-rate screening is saturated liquid hf at P₂. No reheat or multi-extraction heat balance.

P₁, T₁ (Inlet steam pressure & temperature) — Absolute inlet pressure and temperature (barA/°C or psia/°F).
P₂ (Exhaust / condensing pressure) — Absolute back pressure or condenser pressure.
ṁ (Main steam mass flow) — t/h (metric) or lb/h (imperial).
η_is (Isentropic internal efficiency) — Fraction of ideal enthalpy drop realized in the expansion.
η_mech, η_gen (Mechanical & generator efficiency) — Shaft and electrical conversion efficiencies.
W_elec (Electrical power output) — Generator terminal power (MW).
SSC (Specific steam consumption) — Steam mass per unit electrical energy (kg/kWh or lb/kWh).
h_fw (Feedwater / condensate enthalpy) — Screening uses saturated liquid hf at P₂.

2. Screening rules & default duty (PTC 6)

Default metric duty: P₁ = 60 barA, T₁ = 480 °C, P₂ = 0.1 barA, ṁ = 50 t/h, η_is = 80%, η_mech = 98%, η_gen = 97%. Engine assert: W_elec ≈ 12.84 MW, SSC ≈ 3.90 kg/kWh.

Expansion modelSingle pressure

No reheat or multi-stage extraction — use a process simulator for cogeneration heat balances.

Inlet stateSuperheated Region 2

T₁ must be at or above Tsat(P₁). Wet inlet is out of scope.

Exhaust moistureWarn > ~12%

Higher wetness increases L-0 blade erosion risk — raise P₂ or T₁ or confirm OEM limits.

Out of scopeReheat / extraction / supercritical

Critical and supercritical cycles, gland leakage, and part-load maps are not included.

Quick Reference Lookup Table

Illustrative PTC 6 / IAPWS-IF97 turbine duties (this app — engine assert)
Case	W_elec	SSC
60 barA · 480 °C · 50 t/h · η_is 80%	12.84 MW	3.90 kg/kWh
100 barA · 540 °C · 100 t/h · η_is 84%	30.76 MW	3.25 kg/kWh
850 psia · 850 °F · 100 klb/h · η_is 80%	11.25 MW	8.89 lb/kWh
1200 psia · 950 °F · 200 klb/h · η_is 82%	24.76 MW	8.08 lb/kWh

W_elec = ṁ·Δh_actual·η_mech·η_gen with IAPWS-IF97 states. Values are from the calculator engine, not LLM placeholders.

3. Applicability & IAPWS-IF97 / PTC 6 limits

Industrial water/steam within the IAPWS-IF97 formulation used by this app (Region 1 liquid, Region 2 vapor, Region 4 saturation). Screening temperatures 100–600 °C and pressures within the calculator ranges — not a full ASME steam-table / OEM acceptance test.

Group / Regime	Range / Condition	Limit / Criterion	Engineering Notes
Water / steam (IAPWS-IF97 Regions 1, 2, 4)	Screening 100 °C to 600 °C (IF97 industrial up to ~800 °C)	P up to ~220 barA screening (IF97 industrial to 100 MPa)	Supercritical and ultra-supercritical states are out of this Region 2/4 screen.
Condensing / back-pressure single-pressure turbines	Exhaust P₂ 0.02–30 barA	N/A — thermodynamic screen	Extraction / reheat machines need a multi-node heat balance beyond this tool.
Wet exhaust / L-0 blade erosion regime	N/A	Moisture warn ≈ 12%	Confirm OEM wetness / Baumann factor practice for final-stage blades.

Code Applicability & Safety Boundaries

Field screening only — not a stamped ASME PTC 6 acceptance test report.
No reheat, feedwater heaters, or extraction steam accounting.
Heat rate uses condensate hf at P₂ as h_fw — not a full plant heat-rate guarantee.
Export / PDF is a duty worksheet — verify with OEM heat-balance software.

4. Step-by-Step Worked Example

Field VerificationShow

Step-by-Step Worked Example: 60 barA · 480 °C · 50 t/h Metric

Screen a single-pressure condensing steam turbine at P₁ = 60 barA, T₁ = 480 °C, P₂ = 0.1 barA, ṁ = 50 t/h, η_is = 80%, η_mech = 98%, η_gen = 97% using IAPWS-IF97 states.

P₁ / T₁:60 barA / 480 °CP₂:0.1 barAṁ:50 t/hη_is / η_mech / η_gen:80% / 98% / 97%

Inlet enthalpy and entropy

h_{1}, s_{1} = f_{I F 97} (P_{1}, T_{1})

Region 2 at 6.0 MPa, 753.15 K gives h₁ ≈ 3375 kJ/kg and s₁ ≈ 6.76 kJ/kg·K.

Result:h₁ ≈ 3375 kJ/kg

Isentropic exhaust and actual drop

h_{2} = h_{1} - η_{i s} (h_{1} - h_{2 s})

At P₂ = 0.01 MPa with s = s₁, h₂s ≈ 2160 kJ/kg (wet). Δh_ideal ≈ 1215 kJ/kg. With η_is = 0.80, Δh_actual ≈ 972 kJ/kg and h₂ ≈ 2403 kJ/kg.

Result:Δh_actual ≈ 972 kJ/kg

Electrical power and SSC

W_{e l ec} = m ˙ Δ h η_{m ec h} η_{g e n}

ṁ = 50 000 kg/h. W_shaft ≈ ṁ/3600·972·0.98 ≈ 13.23 MW shaft. W_elec ≈ 12.84 MW. SSC = 50 000 / 12 836 ≈ 3.90 kg/kWh.

Result:W_elec ≈ 12.84 MW · SSC ≈ 3.90 kg/kWh

Open /60bar-480c-50th-metric for the live default case.

Conclusion: For the default 60 barA · 480 °C · 50 t/h duty, electrical output is about 12.84 MW with SSC ≈ 3.90 kg/kWh under Category PTC 6 / IAPWS-IF97 screening (exhaust moisture under the 12% warn band).

5. How to calculate steam turbine power and SSC

1
Enter inlet steam
Set absolute inlet pressure and temperature (must be superheated vs Tsat).
2
Enter exhaust pressure and flow
Set condenser / back pressure and main steam mass flow (t/h or lb/h).
3
Set efficiencies
Enter isentropic, mechanical, and generator efficiencies in percent.
4
Read W_elec and SSC
Hero shows electrical MW. Badges show SSC and ideal enthalpy drop. Check moisture callout if wetness is high.

6. Frequently Asked Questions & Technical References

Show

SSC is the main steam mass required per unit electrical energy — kg/kWh (metric) or lb/kWh (imperial).