WNS GAS STEAM BOILER SELECTION
How to Select a 1–20 TPH Gas-Fired Steam Boiler
A capacity label is only the starting point. Select a packaged gas steam boiler from the measured steam profile, pressure at the users, feedwater condition, burner turndown, fuel basis and complete boiler-house scope.
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 pressure required at the farthest user, then account for control valves and distribution loss. State clearly whether a pressure is gauge or absolute.
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 with required mass flow, pressure, operating hours, warm-up demand and whether it runs at the same time as other users. Separate continuous loads from short batch peaks. A boiler sized only from the sum of equipment nameplates is often oversized at normal production and may cycle at low load.
For a process heat balance, steam flow can be estimated from:
ṁsteam = Qprocess ÷ (hsteam − hcondensate)
Use consistent units and the actual steam condition. Then add justified distribution loss, startup duty, blowdown and a documented future allowance. Our steam boiler capacity calculation guide explains the load-sheet method in more detail.
02 · PRESSURE
Specify pressure at the users before boiler pressure.
The boiler pressure must support the most demanding user after losses through the header, piping, separators, control valves and elevation. Raising boiler pressure without a process reason increases saturation temperature and can increase losses, while insufficient pressure causes unstable control at the end users.
| 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.
The table below uses an illustrative enthalpy rise of 2,400 kJ/kg, 92% LHV efficiency and natural-gas LHV of 35.8 MJ/Nm³. It is useful for first-stage comparison. A proposal must use the selected steam pressure, feedwater temperature, blowdown, gas analysis and guaranteed efficiency basis.
| 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.
A WNS wet-back fire-tube boiler is often attractive where a compact packaged arrangement, factory assembly and straightforward installation are priorities. At higher capacity, pressure, load-change or emissions requirements, a water-tube SZS arrangement may deserve a parallel technical and lifecycle evaluation.
Do not switch boiler type from a single capacity threshold. Compare pressure, steam quality, turndown, transport envelope, access for tube inspection, plot space, water quality, emissions equipment, erection scope and local code. The WNS fire-tube vs SZS water-tube boiler guide provides a structured side-by-side review.
05 · BURNER AND FUEL
Turndown must follow the minimum stable steam load.
Record gas pressure range, composition, LHV or HHV, meter reference conditions and backup-fuel requirements. The burner must be checked at maximum site duty and at the lowest sustained load, including furnace pressure, excess air, emissions limits and fan margin at 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.
Define raw-water analysis, treatment system, deaeration method, feedwater temperature, condensate-return percentage and blowdown target. Scale and fouling raise heat-transfer resistance; excessive blowdown wastes hot water; low condensate return increases makeup-water heating and chemical demand.
For efficiency, evaluate an economizer, automatic blowdown control, blowdown heat recovery, insulation and oxygen trim where the operating profile supports them. The U.S. Department of Energy notes that stack temperature and flue-gas oxygen are key combustion-efficiency indicators and that unnecessary excess air increases stack loss.
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
All capacity and fuel figures in this article are preliminary engineering examples. Final selection requires a project heat balance, steam-table calculation, fuel data, code review and supplier-guaranteed performance.
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.
Send the load table, pressure, feedwater condition, gas data, site location and scope boundary. We can review the boiler, burner, economizer, feedwater, controls and boiler-house auxiliaries as one system.
Request a steam boiler selection