VC Fired Heater

⚙ Design Case Studies — Click any case to load all parameters

All module inputs (M1, M14, M15, M10, M9) cascade automatically. Use M25 → Run All Cases for side-by-side comparison table.

A — Standard Hot-Oil (Therminol 66, 155→220°C) · API 560 §6 sizing basis

B — HTRI Xfh / FRNC-5 PC / HYSIS Calibrated · Therminol 66 · 28–40 MW range

★ = HTRI Xfh v7 + FRNC-5 PC v3.1 calibrated · ⚠ = h/D below API 560 §6 minimum 1.5 — review geometry

C — Real Project Cases · Loaded from Client Datasheets (Gasco supplied) · As-built geometry

Sources: Q13946=50191C-DS-03-MA-5044 · P30339B=14-01-34-1607 · Q9446=2971-5-13-0061 · Q10539N=MAEE012-S0207-0235 · B-0105=Methanex · Waitsia=45954-DS-1400-M-62320

Project identification

[Vendor] Quote / Project number

Client / EPC contractor

End user / Owner

Project name / location

Heater tag / service

Process requirements

Total absorbed duty Q_abs (kW)

Process fluid

Fluid inlet temperature T_in (°C)

Fluid outlet temperature T_out (°C)

Design pressure P_des (kPa g)

Mass flow rate m_fluid (kg/h)

Number of radiant passes

Site conditions

Site location

Elevation above sea level (m)

Design ambient temperature (°C)

Basic wind speed V_w (m/s)3-second gust. UAE typical 35–40 m/s

Governing design code

Project summary

Heat & mass balance

Design basis — applicable codes & standards

Fuel composition (mole %)

Total100.00 % ✓

Quick presets — click to load, then adjust mole %:

Enter mole percentages. Click Normalise if total ≠ 100%.

Combustion conditions

Excess air (%)API 560 §6.2.1: gas ND 15–25%; forced draft 10–15%

Combustion air temperature (°C)Site ambient temperature unless air preheater fitted

Stack exit temperature (°C)Key driver of efficiency — from process simulation software simulation

Reference temperature T_ref = 15°C (LHV/net calorific value basis per API 560 §6.2.3)

Flue gas composition (mole %)

Heat balance (per kg fuel)

Combustion parameters — key outputs for M15

Fuel consumption & flue gas quantities

▦ Adiabatic Flame Temperature & Sulphur / Acid Dew Point

AFT computed by iterative energy balance on flue gas (JANAF Cp polynomials). SO₂ from H₂S combustion; H₂SO₄ ADP via Verhoff-Bournstein (1971). Stack temperature check against ADP margin.

H₂S in fuel (mole%)Enter 0 for sweet gas. Feeds SO₂ and ADP calculation. Typical refinery gas: 0.5–5%.

SO₃ conversion factor (%)Fraction of SO₂ oxidised to SO₃ in FG path. Typical: 1–4%. Use 2% for preliminary design. Higher at lower T (V₂O₅ catalyst range 320–420°C).

References & equations ▾

LHV = Σ(yᵢ × ΔHc_i) / MW_fuel [kJ/kg fuel]

Standard molar enthalpies of combustion (NIST/JANAF): CH₄ = 802,625; C₂H₆ = 1,427,820; C₃H₈ = 2,043,400; n-C₄H₁₀ = 2,658,000; H₂ = 241,818; CO = 282,989; H₂S = 518,000 kJ/kmol. Source: Chase, M.W., NIST-JANAF Thermochemical Tables, 4th Ed., J.Phys.Chem.Ref.Data, Monograph No.9, ACS/AIP, 1998.

Cp_fg = Σ(yᵢ × Cp_i) / MW_fg [kJ/kgK] where Cp_i are JANAF polynomial fits in T[K]

JANAF polynomial fits (kJ/kmol·K): CO₂: 37.14+0.0294T−8.74×10⁻⁶T²; H₂O: 32.22+0.00193T+1.06×10⁻⁵T²; N₂: 28.90+0.00167T; O₂: 29.52+0.00406T; Ar: 20.80 (monatomic). Source: Perry's Chemical Engineers' Handbook, 8th Ed., Table 2-172 (Green & Perry, McGraw-Hill, 2008). Also: GPSA Engineering Data Book, 14th Ed., Ch.27, Fig.27-5.

η_thermal = (LHV + Q_air_sensible − Q_stack − Q_rad_loss) / LHV × 100 [%]

Efficiency on LHV (net calorific value) basis per API STD 560, 5th Ed. §6.2.3. Radiation + casing heat loss = 1.5% of heat release for well-insulated heaters (API 560 §6.2). Source: API STD 560, 5th Edition (Feb 2016) + Addendum 1 (2021) + Addendum 2 (Dec 2023). Also: Borger, G.G., 'Approximate Formulae for Fired Heater Design', Hydrocarbon Processing, September 1994, pp.100-106.

Dry air composition: O₂=20.95%, N₂=78.09%, Ar=0.93% (mole%, dry basis)

Standard dry air composition per GPSA Engineering Data Book, 14th Ed., Fig.27-1. Molecular weight of dry air = 28.97 kg/kgmol. Actual air flow = stoichiometric × (1 + EA/100). Flue gas MW and composition calculated by atom balance on fuel + air.

Thermal inputs — from M14

Radiant absorbed duty Q_rad (kW)~65–70% of total as starting point; use rigorous zone model software/process simulation software value for definitive design

Allowable avg flux q_allow (W/m²)Hot oil service: 25,000–38,000 · Crude oil: 15,000–25,000

Bridgewall temperature T_g (°C)Flue gas leaving radiant section — from process simulation software or rigorous zone model software; typical 650–900°C gas-fired

Average fluid temperature T_fluid (°C)(T_inlet + T_outlet) / 2

Flue gas CO₂ (mole%)Copy from M14 output above

Flue gas H₂O (mole%)Copy from M14 output above

Geometry — quick presets & design variables

Quick size presets (click to load)

Tube NPS / OD selectionSelect standard NPS or enter custom OD below

Number of tubes N_tubesMust be even · Min 4 (API 560 §13) · More tubes = lower h/D = wider firebox

Flow passes / paths N_passHTRI/FRNC-5: number of parallel flow circuits through radiant coil. N_tubes must divide evenly by N_pass. Single pass = all tubes in series; 2-pass = fluid splits into 2 parallel streams.

Effective tube length L_eff (m)API 560 §6.3.10: max 18.3 m · Reduce L if h/D > 2.75

Tube pitch (centre-to-centre) mmAPI 560 §6.3.11 min = 2×OD. VC heaters typically 2.5–4×OD. Zeeco [End User] design: ≈2×OD (3.67×OD) for 42T on calculated TCD

Pitch = 2.00×OD (minimum per API 560)

Refractory clearance each side (mm)Gap: outer tube surface to refractory face. Min 100mm per API 560 §6.3.11; typically 150–300mm

▮ Flow Direction — Radiant Section

Process fluid flow direction through coilCounter-current (typical VC heater): fluid enters at top (arch, coolest FG zone) and exits at bottom (near burners, hottest zone). Co-current: fluid enters at bottom (near burners). Co-current gives lower peak tube metal temp but higher exit T. Zone-by-zone gradient analysis is performed for each case.

Counter-current: maximum tube metal T at bottom zone (near burners) where ΔT is highest. This is the conservative design case — API 560 preferred for stress/creep calculations.

Process fluid inlet temperature T_proc_in_rad (°C)Coil inlet temperature. Counter-current: enters at top (arch). Co-current: enters at bottom (near burners).

Process fluid outlet temperature T_proc_out_rad (°C)Coil outlet temperature.

Approximate flame temperature T_flame (°C)Adiabatic flame temperature less pyrometer correction. Typical gas-fired VC: 1200–1550°C. Used for gradient zone analysis only — does not affect Lobo-Evans result.

Radiant gradient zones N_zonesNumber of vertical segments for HTRI-style zone analysis. 6–12 recommended. More = finer profile.

Inside film h_i (W/m²K)Process-side film HTC. Used for tube metal temperature calculation in gradient analysis. Typical forced convection liquid: 500–1500 W/m²K.

Iterate pitch, N & L until all checks pass and Q_R ≥ Q_required. Use M10 Burner module to check flame clearances.

Plan view — tube & burner layout

● Tubes • TCD • Burner circle • D_int

Elevation — radiant section geometry

Geometry computed

Lobo-Evans radiation model

Heat transfer results

Flux & volumetric checks

API 560 / IS 13705 Compliance Checks

Radiant Section Design Summary

Cross-check: Area method vs Lobo-Evans

▦ HTRI Xref-Style Radiant Zone Gradient Analysis

Zone-by-zone temperature, heat flux and tube metal temperature profile using fired heater methodology. The radiant section is divided into N vertical zones from burner floor (bottom, Zone 1) to bridgewall arch (top, Zone N). Flue gas temperature declines from T_flame → T_bridgewall. Local Lobo-Evans radiation is applied at each zone. Both co-current and counter-current process fluid routings are solved and compared.

References & equations ▾

Q_R = σ · (α · A_cp) · F · (T_g⁴ − T_w⁴) [W] — Lobo-Evans fundamental equation

Lobo, W.E. & Evans, J.E., 'Heat Transfer in the Radiant Section of Petroleum Heaters', Transactions AIChE, Vol.35, 1939, pp.743-778. The foundational reference for all fired heater radiant section calculation. σ = 5.67×10⁻⁸ W/m²K⁴ (Stefan-Boltzmann). Tube absorption factor α = 0.97 for single tube row against refractory wall, pitch/diameter = 2.0, from Wimpress, R.N., 'How to Rate Fired Process Heaters', Hydrocarbon Processing, October 1963, pp.115-126.

A_cp = N_tubes × pitch × L_eff [m²] Cold plane area (tubes in circular arrangement)

Cold plane area = projected tube bank area (plane through tube centrelines). For circular VC arrangement the cold plane is the developed cylindrical surface. Effective (absorbed) area = α × A_cp where α from Wimpress (1963) effectiveness chart. Source: GPSA Engineering Data Book, 14th Ed., Chapter 13, Fig.13-2.

L_m = 0.60 × D_int [m] Mean beam length for vertical cylindrical heater

Mean beam length formula for cylindrical firebox per Wimpress, R.N. (1963). The mean beam length represents the characteristic path length of radiation through the gas volume. For other configurations: box heater = 0.60×(V_rad)^(1/3); general = 3.5×V/A_surface. Reference also in Hottel, H.C. & Sarofim, A.F., 'Radiative Heat Transfer', McGraw-Hill, 1967, Chapter 6.

ε_g ≈ 0.53·(1−exp(−1.4·PL^0.7))·(1100/T_g)^0.45 — curve-fit of Lobo-Evans emissivity

Analytical approximation of the Lobo-Evans (1939) flue gas emissivity chart. P = sum of CO₂+H₂O partial pressures [atm]. Temperature correction exponent per Borger (1994). For rigorous design, use the Hottel-Sarofim weighted-sum-of-grey-gases (WSGG) model as implemented in rigorous zone model software (rigorous zone model software technical literature). The WSGG model accounts for spectral band overlap between CO₂ and H₂O absorption bands across the full temperature range 500–2000 K.

F = ε_g / [ε_g + (1−ε_g) / (1 + A_w/αA_cp)] — Mekler-Fairall exchange factor

Overall radiant exchange factor accounting for gas emissivity and refractory re-radiation. Mekler, L. & Fairall, R.S., 'Better Heater Performance by Improved Design', Petroleum Refiner, June 1952, Vol.31, pp.101-110. Also tabulated in GPSA Engineering Data Book, 14th Ed., Ch.13, Fig.13-3. This is equivalent to the Hottel crossed-string formula for a single enclosure with partially absorbing gas.

h/D = H_rad / D_int ≤ 2.75 (API 560 §6.3.5 — mandatory)

API STD 560, 5th Edition, February 2016, §6.3.5: 'Vertical cylindrical heaters shall be designed with a maximum h/D of 2.75 [minimum 1.50]'. This ensures adequate combustion volume and prevents excessive height that would create temperature gradients requiring multi-zone analysis. h = H_rad; D = D_int (internal firebox diameter).

q_max ≤ 1.5 × q_avg (API 560 §6.1.4 — circumferential flux non-uniformity)

API STD 560, 5th Ed. §6.1.4: maximum heat flux density must not exceed 1.5× the average. F_max ≈ 1.30 for single tube row, s/d=2.0 (Wimpress 1963 circumferential non-uniformity chart). Higher F_max (1.4–1.5) occurs at tight pitch — confirm with burner supplier for flame impingement assessment. Also see Jegla, Z. et al., 'Numerical Analysis of Heat Transfer in Radiant Section of Fired Heaters', Chemical Engineering Transactions, Vol.39, 2014.

Tube specification

Material (ASTM grade)

Tube OD d_o (mm)NPS 6"=168.3mm · NPS 4"=114.3mm · NPS 8"=219.1mm · NPS 5"=141.3mm

Design pressure P (kPa g)Maximum operating pressure + surge allowance (typically +10%)

Design metal temperature (DMT) inputs

Max fluid outlet temperature T_fluid_max (°C)Process outlet T + operating margin; from process datasheet

Avg radiant flux q_avg (W/m²)Calculated value from M15 radiant module

Inside film coefficient h_i (W/m²K)From Dittus-Boelter: Nu=0.023·Re⁰·⁸·Pr⁰·⁴. Typical: liquid hot oil 600–1200; gas 80–250

Thickness allowances (API 530 §4.4)

Corrosion allowance CA (mm)API 560 §7.1.2: minimum 1.5mm non-corrosive · 3.2mm corrosive service

Mill undertolerance TOL (%)ASTM seamless A106/A213/A335: 12.5%. API 560 §7.1.4: seamless tubes only — mandatory.

⚠ API 530 design life = 100,000 hours (§4.2.3). Schedule table shown is for NPS 6" (OD 168.3mm). Scale wall thickness for other NPS sizes using API 530 Eq.3.1/3.2 with the correct OD.

Calculating…

DMT build-up (API 530 §4.2)

T_DMT = T_fluid_max + ΔT_film + ΔT_wall + ΔT_safety

Thickness calculation steps

NPS 6" Schedule Selection — ASME B36.10M (OD = 168.3 mm, all schedules)

Schedule	Wall (mm)	ID (mm)	Wt (kg/m)	Status	Notes

Source: ASME B36.10M-2018 (CS/alloy) and B36.19M-2018 (stainless). Selected schedule = first standard schedule with t_nominal ≥ t_specified.

Material allowable stresses — API 530 Annex B

Temp (°C)	σ_a elastic (MPa)	σ_r 100kh creep (MPa)	Notes

API 530 / API 560 Compliance Checks

References & equations ▾

T_DMT = T_fluid_max + q_avg/h_i + q_avg·t_wall/k_metal + ΔT_safety [°C]

API RP 530, 7th Ed. (2015) §4.2.2. Minimum safety adder = 15°C. Inside film h_i from Dittus-Boelter: Nu = 0.023·Re⁰·⁸·Pr⁰·⁴ (heating), valid Re>10,000 (Bergman, T.L. et al., 'Fundamentals of Heat and Mass Transfer', 7th Ed., Wiley, 2011, Eq.8.60). Tube wall k_metal: CS A106-B = 45 W/mK; Cr-Mo alloys (T11/T22/T9) = 30 W/mK; austenitic SS (304H) = 16 W/mK (ASME BPVC Sec.II Part D).

t_min_elastic = P·d_o / (2·σ_a·f_t + 0.8·P) [mm] — API 530 Eq.3.1 (elastic design)

API RP 530, 7th Ed. (2015) §4.3.1. Identical formulation in ISO 13704:2021. Weld joint factor f_t = 1.0 for seamless tubes (mandatory per API 560 §7.1.4). σ_a = allowable stress = min(Yield_min/1.5, UTS_min/3) from API 530 Annex B material stress curves. Units: P in MPa, d_o in mm → t in mm. For P in kPa: divide by 1000 before substituting.

t_min_creep = P·d_o / (2·σ_r) [mm] — API 530 Eq.3.2 (creep-rupture design)

API RP 530, 7th Ed. (2015) §4.3.2. Applies when T_DMT exceeds the elastic limit temperature of the alloy. σ_r = minimum 100,000-hour rupture strength at T_DMT from API 530 Annex B rupture stress curves. Design life = 100,000 hours per §4.2.3. Governing thickness = max(t_el, t_cr). For remaining life / retirement thickness assessment see API 530 Annex A (Larson-Miller parameter).

t_specified = t_min + CA + t_min × (TOL/100) [mm] — API 530 §4.4

Corrosion allowance per API 560 §7.1.2 and process corrosion assessment. Mill undertolerance 12.5% for ASTM A106/A213/A335 seamless per ASTM A530 standard tolerances. Selected schedule must have t_nominal ≥ t_specified. Tube scheduling per ASME B36.10M-2018 (CS/alloy steel) and B36.19M-2018 (stainless). All material specifications are seamless construction only (API 560 §7.1.4 — no ERW or SAW tubes permitted in radiant section).

Burner model library

Select burner model (or enter custom)

Zeeco GLSF-14: Ultra-low NOx “Free-Jet” design. Free-jet method mixes fuel with inert recirculated flue gas before combustion — dramatically lowers thermal NOx. Turndown ≥6.9:1. Round flame. Forced draft. Ref: vendor quote, Rev.1, April 2025.

Thermal design basis

Total heater absorbed duty Q_total (kW)Radiant + convection absorbed. From process datasheet.

Number of burners N_bMin 1 for small heaters. ≥4 recommended for VC (uniform heat, API 560 §6.1.1). This design: 8 burners.

Overall heater efficiency η (%)LHV basis from M14. Typically 85–90% for gas-fired.

Excess air at design (%)FD burners: 10–15%. ND gas: 15–25%.

Burner operating parameters

Design heat release per burner Q_d (MW LHV)From vendor datasheet. Zeeco GLSF-14: 7.257 MW

Normal heat release per burner Q_n (MW LHV)Zeeco: 6.310 MW

Minimum heat release per burner Q_min (MW LHV)Zeeco: 1.050 MW

Draft type

Combustion air temperature (°C)Zeeco [End User]: 58°C

Max available burner ΔP (Pa)FD: 500–1000 Pa typical. ND: 75–200 Pa. Zeeco: 800 Pa

Flame envelope (from vendor datasheet)

Flame length at design L_f (m)Zeeco GLSF-14: 7.0 m at 7.257 MW. Must be < 60% of H_rad per API 560 & burner doc.

Flame width/diameter at design W_f (m)Zeeco GLSF-14: 1.1 m. Must fit within tube circle minus clearance.

Burner tile OD / throat diameter D_tile (m)From vendor drawing B-ZB-0650. Controls tube circle diameter.

Burner circle diameter D_bc (m)Diameter of circle on which burner CL are placed. Zeeco: 3.0 m for 8 burners.

Radiant section dimensions (from M15)

Tube circle diameter TCD (m)From M15. Zeeco [End User]: 8.25 m

Firebox internal height H_rad (m)From M15. Zeeco [End User]: 18.0 m

Firebox internal diameter D_int (m)From M15. Zeeco [End User]: 8.456 m

Emission guarantees (from vendor)

NOx guarantee (mg/Nm³ @ 3% O&sub2;)Zeeco GLSF-14: 100 mg/Nm³ all fuels. <20 ppm ultra-low NOx = ~40 mg/Nm³.

CO guarantee (mg/Nm³)Zeeco: 50 mg/Nm³ all fuels

Noise (dBa @ 1m single burner)Zeeco: 82 dBa @ 1m

Bridgewall temperature for emissions (°C)Zeeco: 705°C. Emissions basis — CO2 checked above 621°C.

Calculating…

Heat release summary

Geometry & flame envelope checks

Burner spacing & floor loading

Draft & pressure drop

API 560 §13 & Burner Selection Compliance Checks

Burner floor layout — plan view

● Burners · ○ Tube CL · - - TCD · - - D_int

Flame envelope cross-section

Emission & noise summary

References & equations ▾

Flame length check: L_f < 0.60 × H_rad — API 560 & burner selection criteria

The flame at maximum heat release must not impinge on the arch (convection section floor). API 560 guidance and Burner_selection.docx: aim for radiant height to be at least 1.5–2.0 times the flame length. Conservative target: L_f < 60% of H_rad at design. Source: API STD 560, 5th Ed. §6.1.1; Zeeco GLSF-14 datasheet (vendor quote); Burner_selection.docx, [Vendor] internal document.

Burner CL to tube CL clearance: C_bt = (TCD − D_bc) / 2 − W_f / 2

Minimum clearance from flame edge to tube surface. API 560 §13.2 table gives minimum CL-to-CL distances by burner capacity. For burners >10 MMBtu/hr (2.93 MW): minimum 3–4 ft (0.9–1.2 m) CL-to-CL. Burner_selection.docx Rule: TCD typically 2.5–3.0× burner throat diameter. Flame impingement causes rapid tube failure (coking and oxidation).

Burner spacing check: D_bc / N_b ≥ 1.5 × W_f (prevent flame coalescence)

Burner_selection.docx §3: multi-burner arrangement requires careful spacing to prevent “flame coalescing” (multiple flames merging). Rule: arc spacing between adjacent burner CL should be ≥ 1.5× flame width at design to prevent coalescence. Source: Zeeco application engineering guidelines; John Zink Combustion Handbook (Baukal, 2001), Ch.12.

Burner design capacity ≥ 1.25 × Q_normal (N ≤ 5 burners) or 1.10 × (N ≥ 6)

API STD 560, 5th Ed. §13.1: where 5 or fewer burners, each shall have a design capacity of not less than 125% of normal heat release. Where 6 or more burners, design capacity shall be not less than 110% of normal heat release per burner. This provides single burner-out capacity. Zeeco GLSF-14: Design = 7.257 MW, Normal = 6.310 MW, ratio = 1.149 (115% for 8 burners ≥ 110% ✓).

NOx [mg/Nm³] = NOx [ppm] × 1.333 @ 3% O&sub2; dry basis

Conversion factor for NOx at standard conditions (0°C, 1 atm). 1 ppm NOx = 2.054 mg/Nm³ (as NO2 basis, MW=46). @ 3% O2 correction: NOx[corrected] = NOx[measured] × (21-3)/(21-O2_meas). Source: EN 14792:2005; EPA Method 7E; Zeeco burner data sheet note 4-4.

Thermal inputs — from M14 & M15

Convection duty Q_conv (kW)Q_total − Q_rad; or from process datasheet

Flue gas inlet T_fg_in (°C)= Bridgewall temperature from M15

Flue gas outlet T_fg_out (°C)Target stack entry temp; typically 280–350°C

Flue gas mass flow W_fg (kg/h)From M14

Flue gas Cp (kJ/kgK)At mean flue gas temperature — from M14

Process fluid inlet T_proc_in (°C)

Process fluid outlet T_proc_out (°C)

Process fluid mass flow m_proc (kg/h)Used for gradient analysis. Enter 0 to derive from Q & Cp below.

Process fluid Cp (kJ/kgK)Mean value over temperature range (used when m_proc=0)

▮ Flow Direction — Convection Section

Flow configurationCounter-current = FG up, process down (API 560 preferred — maximises LMTD). Co-current = both streams flow in same direction. Affects LMTD, tube metal temperature & gradient profile.

Counter-current: ΔT₁ = T_fg_in − T_proc_out | ΔT₂ = T_fg_out − T_proc_in

Tube bank geometry

Tube OD (mm)Usually same NPS as radiant section

Tubes per row N_wideBox width ≈ N_wide × pitch

Flow paths (parallel passes through conv.)HTRI/FRNC-5: usually = N_wide ÷ 2 for U-tube or = 1 for single-pass serpentine. Must divide N_total evenly.

Tube length L_conv (m)Approx = radiant tube-circle diameter

Total rows N_rowsMin 3 bare shield + finned rows

Shield rows N_shield (bare)API 560 §6.3.7: minimum 3 bare rows

Transverse pitch S_T (mm)Typical 1.25–1.50×OD staggered

Extended surface type

▦ Fin/Stud Efficiency η_f (Gap 3 — new)

Fin height h_fin (mm)Helical fin: 12–19 mm typical for NPS 4–6". Stud length: 25–40 mm.

Fin thickness t_fin (mm)Helical: 1.2–2.0 mm. Stud dia: 9–12 mm (treat as pin fin with d_stud).

Fin material k_fin (W/mK)Carbon steel: 45. 304SS: 16. Alloy 625: 10. Cu alloy: 200.

Fin/stud density (fins/m or studs/m²)Helical: 120–200 fins/m (3–5 FPM). Studs: 30–50 per m² typical.

▦ Shield Row Radiation Component (Gap 4 — new)

T_arch / bridgewall (°C)From M15 T_g. FG temperature at arch — source of radiation to shield rows. Typically 700–850°C.

Arch opening area A_arch (m²)Area of the arch opening seen by shield rows. Approx = π×D_int²/4 − tube footprint. Typical: 30–90 m².

▦ Inside Film h_i — Process Fluid Phase (Gap 5 — new)

Process fluid phase

h_i = 800 W/m²K (liquid default)

HTC correlation methodSelect correlation for outside film h_o

API 560 §6.3.4: allow space for 2 additional future rows. §6.3.8: corbels required (except 1st shield row).

Thermal performance

Geometry & dimensions

Heat transfer coefficients

API 560 compliance

Convection section — elevation view

Tube cross-section (bare vs extended surface)

References & equations ▾

Burner design capacity ≥ 1.10×Q_normal (N ≥ 6) per API 560 §13.1

Where N ≥ 6 burners, each shall have design capacity ≥110% of normal heat release per burner — provides single burner out capability. For N ≤ 5: minimum 125%. Source: API STD 560, 5th Ed. §13.1.

Scruton: Sc = 2πδ·m_s/(ρ_a·D²) ≥ 10 to avoid VIV — ESDU 96030

Flame length check: L_f < 0.60×H_rad (arch impingement). Burner CL to tube CL per API 560 Table 1 (function of burner rated capacity). Volumetric heat release ≤ 25,000 Btu/hr·ft³ = 259 kW/m³. Source: API 560 §6.2.5; API 535 (2014); Zeeco engineering guidelines.

Burner supplier comparison — key specifications

Parameter	Zeeco GLSF-14 Free-Jet	John Zink RCLS	Callidus CXLS	Faber BIC/BVFS
Technology	Free-jet fuel staging + IFGR	Radiant cup + fuel staging	Staged fuel, ND/FD	Multi-port staged
Turndown ratio	6.9:1 (tested)	8:1 (typical)	10:1 (typical)	6:1 (typical)
NOx (mg/Nm³ @3% O₂)	100 (FD gas)	50–80 (FD gas)	30–60 (FD gas)	80–120 (FD gas)
Draft type	FD (also ND)	FD and ND models	FD and ND	FD and ND
H₂ fuel capability	Up to 60% H₂ (special tips)	Up to 100% H₂ (HiTH)	Up to 80% H₂	Up to 50% H₂
Flame shape	Round (free-jet)	Round / flat	Round	Round
Max single burner capacity	~15 MW (GLSF-17)	~20 MW	~15 MW	~10 MW
Tip material	310SS or HK-40	310SS or Inconel	310SS	310SS
Pilot type	JM-1S-EF electric HT	Electric HE spark	Electric spark	Electric spark
Flame scanner	ZPF-120 UV/IR	QuadFlame UV/IR	Honeywell UV/IR	Forney UV/IR
Lead time (typical)	40–44 wks ARO	30–36 wks ARO	28–34 wks ARO	32–40 wks ARO
Standards	API 560/535, NFPA 86	API 560/535, NFPA 86	API 560/535, NFPA 86	API 560/535, EN 746

Sources: Zeeco product literature (GLSF series); John Zink Hamworthy Combustion Handbook, 3rd Ed. (Baukal, 2013); Callidus Technologies product data sheets; Faber Industrie product literature. All data indicative — obtain vendor quotation for project-specific sizing. API 535 (2014) Burners for Fired Heaters in General Refinery Services.

▦ HTRI Xref-Style Gradient Thermal Analysis — Convection Section

Row-by-row temperature & heat flux profile following HTRI Xref methodology. Each tube row is treated as a discrete heat transfer zone. Both co-current and counter-current profiles are calculated and compared. Local ΔT, q-flux, U·A and tube metal temperature are shown at every row position.

Flue gas & air properties

Flue gas mass flow W_fg (kg/h)From M14

Flue gas MW (kg/kgmol)From M14

Air mass flow W_air (kg/h)From M14

Ambient temperature T_amb (°C)

Atmospheric pressure P_atm (kPa)

Stack (DP1)

Stack inside dia D_stack (m)

Stack length H_stack (m)

Stack exit temperature (°C)

Moody friction factor f_stackTurbulent steel: 0.016–0.022

Radiant (DP3) & Convection (DP2)

Radiant section height H_rad (m)From M15

Avg flue gas temp in radiant (°C)

Convection ΔP DP2 (mmH₂O)From M4 or enter manually

Burner (DP4) & Windbox (DP5)

Burner ΔP from vendor (inH₂O)ND gas burner: 0.1–0.3 inH₂O typical

Windbox width X (mm)

Windbox height Y (mm)

Windbox length L_wb (m)

Windbox friction factor f_wb

Stack DP1 & buoyancy Dr1

Radiant Dr3 & Convection DP2

Burner DP4 & Windbox DP5

Fluid densities

Natural Draft Balance — Node Pressures P0 → P4

References & equations ▾

ΔP_fric = f×(L/D)×G²/(2×ρ) × 0.1020 [mmH₂O] — Darcy-Weisbach

1 Pa = 0.1020 mmH₂O. Friction factor f from Moody chart. Source: GPSA 14th Ed. Ch.17; Crane Technical Paper TP-410.

Dr = g × H × (ρ_amb − ρ_fg) × 0.1020 [mmH₂O] — buoyancy draft

ρ = P×MW/(R×T). R = 8.314 kJ/kgmol·K. Source: fired heater calculation methodology; internal ref DP calculation sheets ([Vendor] 2008). API 560 §12: adequate draft required at all operating conditions.

Radiant casing & structure (from M15)

Casing outside dia D_cas (mm)D_int + 2×(refrac+plate). Pull from M15 once designed.

Radiant section height H_rad (m)

Casing plate thickness (mm)

Number of support columns

Column section (kg/m)UC310×198=198; UC250×149=149; UC200×100=100

Column height (m)

Base ring plate thickness (mm)

Number of access doors

Number of burner openings

Radiant process coil (from M15)

Number of tubes

Tube OD (mm)

Wall thickness (mm)

Effective tube length (m)

Return bends (No.)

Return bend unit weight (kg)

Number of inlet/outlet nozzles

Inlet/outlet nozzle weight each (kg)

Number of tube support guides

Guide weight each (kg)

Convection section box

Conv. box length (mm)

Conv. box width (mm)

Conv. box height (mm)

Conv. box plate (mm)

Conv. tube count

Conv. tube OD (mm)

Conv. tube wall (mm)

Conv. tube length (m)

Conv. tube corbels/supports (No.)

Stack (from M9)

Stack inside dia (mm)

Stack height (m)

Stack plate (mm)

Stack sections (No.)

Stack damper weight (kg)

Platforms, ladders & access

Platform levels (No.)

Platform area each (m²)

Handrail perimeter total (m)

Ladder height total (m)

Process fluid (for operating weight)

Fluid density (kg/m³)

Bill of Quantities — component weight breakdown

Item	Description	Unit wt (kg)	Qty	Total (kg)

Weight summary

Lifting study notes

References & equations ▾

W_cyl = π×D_mean×H×t×7850 [kg] W_tube = (π/4)×(OD²−ID²)×L×7850 [kg/tube]

Steel density 7850 kg/m³. Tube unit weight per ASME B36.10M-2018. Platform grating: 35 kg/m² (bar grating AS 1657). Handrail: 15 kg/m (AS 1657 galv. post & rail). Ladder: 20 kg/m (AS 1657 cage ladder). 5% structural SF covers cleats, stiffeners, misc. steel.

Global site & code parameters

Ambient temperature T_amb (°C)

Wind speed (m/s)0 = still air; 2 m/s = gentle breeze (ASTM C680 default); 5 = moderate

Casing emissivity εPainted CS ≈ 0.85; bare CS ≈ 0.70; insulated jacketed ≈ 0.90

Sulfurous fuel (H₂S >10ppm)?

Casing temperature limits — dual check

Both limits are checked per zone. The governing limit is the lower value (more conservative). API 560 §11.4 sets the code minimum; client may specify stricter.

API 560 §11.4 code limit (°C)§11.4.1 radiant/arch: 82°C; §11.4.2 convection: 90°C; external insulated: 65°C. Enter the applicable limit.

Client-specified limit (°C)Client may specify 60°C or 65°C for additional personnel safety margin. Set equal to API value if no client requirement.

Governing = min(API, Client). API 560 §11.4 requirements by zone:
• §11.4.1 — Radiant walls, arch, floor: 82°C
• §11.4.2 — Convection section: 90°C (non-accessible)
• External insulated accessible surfaces: 65°C (personnel protection BS EN 563)
• Stack acid dew point: inner surface >90°C when sulfurous fuel

Heater zones — layer stack (hot face → casing)

Each zone: add/remove layers, select material, set thickness. Calculation uses ASTM C680 iterative solver (100-step bisection) updating k at mean layer temperature. Radiant floor has 3 layers pre-set: Dense Firebrick top + IC backup + CF blanket.

Radiant Walls (cylindrical)

Walls: CF modules/blanket or castable. No bricks — expansion risk.

Hot-face T (°C)

Inner radius (mm)

Area (m²)

#	Material (hot face → casing)	t (mm)

Radiant Arch / Roof (flat)

Arch/roof: CF modules or castable only.

Hot-face T (°C)

Geometry

Flat plane

Area (m²)

#	Material (hot face → casing)	t (mm)

Radiant Floor (flat — brick top)

⚠ Floor: Castable + firebrick only. No ceramic fibre (abrasion/traffic).

Hot-face T (°C)

Geometry

Flat plane

Area (m²)

Floor: brick top layer (hot face), IC backup, CF blanket at casing. Adjust thicknesses to achieve T_casing goal.

#	Material (hot face → casing)	t (mm)

Convection Walls (flat)

Conv. walls: CF blanket + castable + mineral wool acceptable.

Hot-face T (°C)

Geometry

Flat plane

Area (m²)

#	Material (hot face → casing)	t (mm)

Convection Tube Plates

Tube plates: Castable (dense or insulating) preferred.

Hot-face T (°C)

Geometry

Flat plane

Area (m²)

#	Material (hot face → casing)	t (mm)

Transition Piece / Cone (flat)

Transition: CF blanket / castable / mineral wool.

Hot-face T (°C)

Geometry

Flat plane

Area (m²)

#	Material (hot face → casing)	t (mm)

Exhaust Stack — lower section

Stack: Castable inner lining or mineral wool.

Hot-face T (°C)

Inner radius (mm)

Area (m²)

#	Material (hot face → casing)	t (mm)

Heat loss & compliance summary

Anchor schedule

Methodology & references ▾

ASTM C680 — Standard Practice for Estimate of Heat Gain/Loss and Surface Temperatures of Insulated Systems

Bisection iteration: assume T_casing, calculate Q_loss = (h_c + h_r)×(Tc−Ta). Walk inward through layers using Fourier law (flat: R=t/k; cylindrical: R=r_out×ln(r_out/r_in)/k). Converge when T_hot_total = T_firebox. h_c = 1.31×ΔT^0.333 (still air, MacAdams) or 5.7+3.8V (wind). h_r = ε×σ×(Tc⁴−Ta⁴)/ΔT. k interpolated at mean layer T each iteration. Source: ASTM C680-04; API 560 §11.4; API RP 936.

Refractory materials — AU / Malaysia suppliers

CF Blanket/Modules: Unifrax (Silverwater NSW / Selangor MY); Pyrotek (Brisbane QLD / Petaling Jaya MY); Morgan Advanced Materials (Dandenong VIC / KL MY). IFB / Dense Castable: Plibrico (Sydney NSW / Shah Alam MY); Imerys / Minerals Technologies AU; ANH Refractories AU. Mineral Wool: Rockwool AU (Pty Ltd, Padstow NSW); Isover MY. Calcium Silicate: Promat AU / Promat SEA (MY). All k-values from manufacturer data sheets at mean layer temperature.

Thermal inputs (from M15/M6/M16)

Average radiant flux q_avg (W/m²)From M15. API 560 §6.1.3.

Peak flux factor F_maxWimpress 1963: 1.35 at s/d=2.0; 1.22 at s/d=3.0

Process fluid bulk temperature T_b (°C)

Inside film coefficient h_i (W/m²K)From M16 Dittus-Boelter

Inside fouling r_fi (m²K/W)TEMA: 0.0002 clean oil; 0.0004 crude

Tube geometry (from M6)

Tube OD (mm)

Wall thickness t_w (mm)

Tube material k_w (W/mK)

Tube row / radiation exposure

Coke/deposit layer & limits

Coke thickness (mm)0 = clean; typical fouled: 1–3mm

Coke k (W/mK)

Max fluid film temperature (°C)Therminol 66: 380°C; Dowtherm A: 400°C; crude: 370°C

Max tube metal T (°C)API 530 T_el: CS=371°C, T11=454°C, T22=538°C

Calculating…

Temperature cascade — average flux

Temperature cascade — peak flux (worst case)

Thermal resistances

API 530 & API 560 compliance

Temperature profile through tube wall (SVG)

References & equations ▾

T_tube_OD = T_b + q×(OD/(h_i×ID) + r_fi×OD/ID + t_coke/k_coke + t_w×OD/(k_w×D_lm))

Cylindrical wall resistance: R_wall = t×D_OD/(k×D_lm). D_lm = log-mean diameter = (D_OD-D_ID)/ln(D_OD/D_ID). API RP 530, 7th Ed. §4.3. Bergman et al. HMT 7th Ed. §3.3.2.

Labour rates (A$/hr)

Project Manager / Sr Engineer

Engineer

Draftsperson / Designer

Management margins

Contingency (%)

Finance & bank guarantees (%)

Technical risk / warranty (%)

Profit markup (%)

Agent commission (%)

Key bought-out items (A$)

Burners (supply only)

Engineering & PM hours

Drafting hours

C&I — Control & Instrumentation budget

Process instruments (TI/PI/FI/LI)

Analysers (O&sub2;, NOx, CO)

Control valves

Field junction boxes

Wiring & cable trays

DCS/PLC I/O cards & marshalling

C&I installation & testing (labour)

Gas Train & Fuel Skid budget

Main shutoff valves (ESDV/MSOV)

Control valves (pressure/flow)

Pressure regulators

Strainers & filters

Piping, flanges & fittings

Skid frame & baseplate

Instrumentation on skid

Gas train fabrication & testing (labour)

BMS & PLC / Safety System budget

Safety PLC (SIL-rated, TÜV certified)

HMI / SCADA workstation

Flame detectors (UV/IR per burner)

Combustion air proving switches

BMS panel enclosure & wiring

SIL assessment & HAZOP (labour)

FAT, SAT & commissioning (labour)

A$ —

Estimated Selling Price (excl. agent commission)

24-line cost estimate

Margin build-up to selling price

Fluid selection

Fluid / service

Evaluate at temperature (°C)

Therminol 66: synthetic heat transfer fluid, max bulk temperature 345°C, max film 380°C. Excellent stability. Westlake/Eastman Chemical.

Manual override (Custom fluid)

Density ρ (kg/m³)

Dynamic viscosity μ (mPa·s)

Specific heat Cp (kJ/kgK)

Thermal conductivity k (W/mK)

Operating conditions for h_i

Mass flow rate (kg/h)

Tube inside diameter (mm)From M6 selected schedule

Number of parallel passes

Properties at T

h_i — inside film coefficient

Properties vs temperature (every 25°C)

T (°C)	ρ (kg/m³)	μ (mPa·s)	Cp (kJ/kgK)	k (W/mK)	Pr	h_i (W/m²K)

Property trend chart (SVG)

References & equations ▾

h_i = Nu × k / d_i Nu = 0.023 Re^0.8 Pr^0.4 (Dittus-Boelter, heating)

Valid Re>10,000, L/D>60. Source: Bergman et al., 'Fundamentals of HMT', 7th Ed., Wiley, 2011, Eq.8.60. Therminol 66 properties: Eastman Chemical Technical Bulletin (2013). Water: IAPWS-IF97. MEG: ASHRAE HoF 2017 Ch.31.

Stack geometry (from M5 draft)

Stack inside dia D_s (m)Size for flue gas velocity ≤ 12 m/s at exit

Total stack height H_s (m)Including section above roofline

Freestanding height above base H_free (m)For cantilever bending calc — top of conv. box to stack tip

Shell plate thickness (mm)

Number of helical strake sets0=none; 3 sets×120° on top 1/3 of stack is standard VIV fix

Loads & material

Shell material

Design wind speed V_wind (m/s)AS/NZS 1170.2 3-sec gust. From M1.

Air density at site (kg/m³)~1.1 at 45°C sea level; ~1.0 at elevated altitude/temp

Damping ratio δSteel stack ~0.01 (1%). With guy wires or base isolation: 0.03–0.05.

Flue gas conditions (from M14/M5)

Flue gas mass flow W_fg (kg/h)

Exit temperature T_exit (°C)

Flue gas MW (kg/kgmol)

Acid dew point (°C)Clean NG: 55–70°C. H₂S: 130–150°C. Stack exit must be > ADP.

Multi-section design & lining

Number of sections / cansSplit stack into bolted/flanged sections for transport and erection. Typically 2–4 sections.

Lining type

Lined height from base (m)Protect lower section from condensate & acid attack

Lining thickness (mm)

Expansion joint required?

Aircraft warning light required?Required if stack > 60m in most jurisdictions (CASA/FAA/ANSP)

API 560 §12.4: stack must accommodate thermal growth at base connection. AS 4100: provide access platform at ≤9m intervals for stacks >18m height.

Calculating…

Structural sizing (AS 4100)

Velocity & draft

Weight & thermal growth

Multi-section details

Stack compliance checks

Stack elevation diagram

VIV / wind force diagram

References & equations ▾

Scruton: Sc = 2πδ·m_s / (ρ_a·D²) Strouhal: f_s = 0.20·V/D Critical Sc≥10

ESDU Data Item 96030 (VIV of circular cylinders). API 560 §12.2: helical strakes mandatory when Sc<10. Damping δ≈0.01 for welded steel stack. Source: Vickery & Basu (1983); CICIND Model Code for Steel Chimneys, 2nd Ed. (2010).

Wind bending: M_w = 0.5×C_d×ρ_a×V²×D×H²/2 C_d≈0.70 (Re>5×10⁵)

Combined stress: σ_total = P/(A) + M_w×(D/2)/I ≤ φ×Fy (φ=0.9, AS 4100 §5.1). Thermal expansion: ΔL = 11.7×10⊃⁻&sup6;×L×ΔT [m/m·°C for CS]. Source: AS 4100:2020 Steel Structures; API 560 §12.

Vertical Cylindrical Fired Heater — API 560 Design Modules

M14 — Combustion Stoichiometry & Heat Balance