WNS GAS STEAM BOILER SELECTION
How to Select a 1–20 TPH Gas-Fired Steam Boiler
Select a gas-fired steam boiler from the steam load range, user pressure, feedwater condition, burner turndown and fuel data.
QUICK ANSWER
Select capacity, pressure and burner control as one operating decision.
Capacity
Build normal, peak, startup and minimum-load steam demand from the actual users. Do not add every nameplate load at 100% unless they truly operate together.
Pressure
Start from the user requiring the highest upstream supply pressure after distribution and control-valve losses. Identify gauge and absolute pressures.
Fuel use
Calculate from steam enthalpy rise, feedwater condition, efficiency and the contracted gas LHV or HHV—not from a universal “gas per tonne” figure.
Selection boundary: the boiler, burner, economizer, feedwater, blowdown, condensate return, controls and stack must be reviewed together.
01 · STEAM DEMAND
Build the load from process users and operating time.
List each steam user’s flow, pressure, operating hours and warm-up demand. Identify simultaneous loads and short batch peaks. Adding all nameplates can oversize the boiler and cause low-load cycling.
For a process heat balance, steam flow can be estimated from:
ṁsteam = Qprocess ÷ (hsteam − hcondensate)
Use steam and condensate enthalpies at the process heat exchanger. Add justified distribution, startup and future steam demand. Account for blowdown in the feedwater and fuel balance, not as steam delivered to users. See the steam boiler capacity calculation guide.
02 · PRESSURE
Specify pressure at the users before boiler pressure.
Allow for losses through piping, headers, separators and control valves at the controlling user. Excess pressure raises saturation temperature and may increase losses; insufficient pressure impairs process control.
| Pressure item | What to record | Why it matters |
|---|---|---|
| User requirement | Minimum pressure and steam condition at every process | Defines the real duty |
| Distribution loss | Header and branch pressure drop at peak flow | Sets the supply margin |
| Control allowance | Required drop across the pressure-control valve | Maintains controllability |
| Design basis | Operating, design and safety-valve pressures; gauge or absolute | Avoids specification ambiguity |
JIELI’s published WNS preliminary range lists rated working pressures from 1.0 to 2.5 MPa. The final pressure, materials, code and safety-valve settings must be confirmed for the project jurisdiction and process requirement.
03 · 1–20 TPH PRELIMINARY RANGE
Use the capacity table as a screening tool, not a final fuel guarantee.
Example basis: 2,400 kJ/kg steam-to-feedwater enthalpy rise, 92% LHV efficiency and gas LHV 35.8 MJ/Nm³. Values exclude a separate blowdown allowance. Recalculate for the project steam, feedwater and fuel conditions.
| WNS model | Rated steam | Illustrative useful output | Illustrative gas at full load |
|---|---|---|---|
| WNS1 | 1 t/h | 0.67 MW | ≈73 Nm³/h |
| WNS2 | 2 t/h | 1.33 MW | ≈146 Nm³/h |
| WNS3 | 3 t/h | 2.00 MW | ≈219 Nm³/h |
| WNS4 | 4 t/h | 2.67 MW | ≈291 Nm³/h |
| WNS5 | 5 t/h | 3.33 MW | ≈364 Nm³/h |
| WNS6 | 6 t/h | 4.00 MW | ≈437 Nm³/h |
| WNS8 | 8 t/h | 5.33 MW | ≈583 Nm³/h |
| WNS10 | 10 t/h | 6.67 MW | ≈729 Nm³/h |
| WNS12 | 12 t/h | 8.00 MW | ≈874 Nm³/h |
| WNS15 | 15 t/h | 10.00 MW | ≈1,093 Nm³/h |
| WNS20 | 20 t/h | 13.33 MW | ≈1,457 Nm³/h |
Use the gas boiler fuel-consumption calculator and formula for a project-specific screening range. Keep LHV/HHV and the efficiency basis consistent.
04 · BOILER ARRANGEMENT
WNS is a packaged fire-tube option; some duties require an SZS review.
WNS offers a packaged wet-back fire-tube arrangement. Evaluate SZS water-tube construction alongside it where capacity, pressure, response, transport or site conditions justify the comparison.
Compare steam condition, load range, access, water quality, emissions and installation scope. See the WNS fire-tube vs SZS water-tube boiler guide.
05 · BURNER AND FUEL
Turndown must follow the minimum stable steam load.
Check gas pressure, composition, heating value and volume reference conditions. Match burner output to the maximum and minimum load, furnace resistance, emissions and site altitude.
JIELI’s preliminary WNS table lists hi-low-off regulation for WNS1–WNS5 and proportional regulation for WNS6–WNS20. That is a screening basis only; the final burner and control method should follow the load profile and applicable emissions rules. See the gas, oil and dual-fuel burner selection guide.
06 · WATER AND ENERGY
Feedwater temperature, condensate return and blowdown change the plant result.
Specify water analysis, treatment, deaeration, feedwater temperature, condensate return and blowdown. Scale impairs heat transfer; blowdown and cold makeup increase fuel demand.
Evaluate economizing, blowdown control and heat recovery against operating hours. Check stack temperature and O₂ to identify combustion losses; excessive air carries additional heat to the stack.
Data required for a 1–20 TPH gas steam boiler proposal
- Normal, peak, startup and minimum steam demand in kg/h or t/h;
- Required steam pressure, temperature or dryness at each user;
- Daily hours, batch sequence, future allowance and redundancy philosophy;
- Feedwater temperature, water analysis, condensate return and blowdown basis;
- Natural-gas pressure, LHV/HHV, composition and backup fuel;
- Site altitude, ambient range, emissions limits and local code;
- Boiler-house layout, transport limits, stack and complete auxiliary scope.
TECHNICAL REFERENCES
Primary guidance and related calculations.
- U.S. Department of Energy — Industrial steam-system resources
- U.S. Department of Energy — Improve Your Boiler’s Combustion Efficiency
- JIELI — Industrial steam boiler system and piping guide
- JIELI — Published WNS1–WNS20 preliminary product range
Final selection requires the project load balance and agreed fuel, efficiency and operating conditions.
FREQUENTLY ASKED QUESTIONS
1–20 TPH gas steam boiler FAQ
How much gas does a 10 TPH steam boiler use?
Using an illustrative 2,400 kJ/kg enthalpy rise, 92% LHV efficiency and gas LHV of 35.8 MJ/Nm³ gives about 729 Nm³/h at full load. The project value changes with steam pressure, feedwater temperature, blowdown, gas composition and guaranteed efficiency.
What pressure should a gas-fired steam boiler use?
Select pressure from the minimum required at the process users plus justified distribution and control-valve losses. State whether values are gauge or absolute, then confirm operating, design and safety-valve pressures under the applicable code.
Should I select the boiler from peak load?
Peak load matters, but its duration, simultaneous users, minimum stable load and redundancy also matter. A measured load profile is more reliable than selecting from one peak number.
When should an SZS water-tube boiler be evaluated?
Evaluate WNS and SZS arrangements together when capacity, pressure, steam quality, load response, transport, plot space, maintenance access or emissions requirements make the boiler configuration a significant project decision.
Is natural-gas use per tonne of steam always the same?
No. The enthalpy rise, feedwater temperature, boiler efficiency, blowdown, condensate return, fuel heating value and operating load all affect consumption.
JIELI THERMAL ENGINEERING
Turn the steam profile into a project-ready WNS or SZS selection.
Provide steam demand, pressure, feedwater conditions, gas data, location and equipment scope.
Request a steam boiler selection