Fired heaters are major energy consumers and key emission sources across crude, vacuum, and conversion units. Improving efficiency protects coil life, stabilizes product quality, and lowers fuel costs and pollutants. This guide organizes proven actions that operators, maintenance teams, and process engineers can deploy without compromising safety or reliability. It connects field practices with control strategies and hardware upgrades so each heater can run closer to its design intent. The Top 10 Fired Heater Efficiency and Emissions Controls in Petroleum Refining provide a structured path to achieve quick wins, sustain performance, and demonstrate compliance while building a culture of continuous improvement across shifts.
#1 Combustion tuning and excess oxygen control
Start with accurate O2 and CO readings at the stack and validate analyzer calibration with certified gases. Map burner curves across load and ambient ranges, then set cross limited air and fuel to prevent rich spikes during transients. Trim excess O2 to the minimum that avoids CO slip and afterburning, typically two to three percent for clean fuels, while verifying uniform flame shapes. Balance registers, adjust tile angles, and correct swirl to reduce hot spots. Repeat tuning seasonally, and document setpoints and bias limits so operators maintain targets during start up, turndown, and normal operation.
#2 Heat recovery with air preheaters and economizers
Recovering sensible heat from flue gas reduces fuel immediately. Install or upgrade combustion air preheaters to raise air temperature within burner limits, and add gas to liquid or gas to gas economizers where corrosion risks are managed. Track approach temperatures, leakage rates, and pressure drop to confirm performance. Inspect seals, bearings, and baskets, and clean deposits that degrade effectiveness. Coordinate preheater operation with burner management so light off and turndown remain stable. Design cold end metallurgy for acid dew point margins, and use bypasses thoughtfully to avoid condensing regions while still maximizing recovered duty.
#3 Radiant and convection surface cleanliness
Deposits on radiant tubes and convection banks raise bridgewall temperature and stack losses. Implement online sootblowing or offline washing tailored to fuel impurities and feed coking tendencies. Trend tube metal temperature and coil pressure drop to detect fouling early, and use infrared surveys to find low emissivity areas. Remove warped fins and replace sagged supports that trap particulates. Consider emissivity enhancing coatings or ceramic sleeves where duty and fuel price justify capital. After cleaning, revalidate heat balances and adjust draft and excess O2 targets so the heater operates at the new, improved transfer conditions.
#4 Balanced firing, draft stability, and leakage control
Uniform firing keeps coil metal temperatures within limits and reduces local NOx formation. Survey flames, confirm tile alignment, and equalize burner registers to eliminate lopsided heat flux. Maintain steady furnace draft using responsive dampers, reliable transmitters, and tuned PID settings that avoid hunting. Fix air inleakage at observation doors, casing joints, and peep sights, which inflates measured excess O2 and wastes fuel. Verify breeching and stack seals, and check fan performance against curves. Document burner light off procedures and pilot health checks so restart conditions reproduce balanced firing profiles every time.
#5 Advanced controls with cross limit, oxygen trim, and model predictive control
Cross limited logic coordinates air and fuel to prevent excursions during load changes. Oxygen trim closes the loop on excess O2 using fast analyzers and validated biases to hold targets through ambient swings. Model predictive control supervises coil outlet temperature, draft, and excess O2 while respecting constraints on bridgewall temperature, fan limits, and burner stability. Add feedforward from charge rate, fuel composition, and preheat. Include valve stiction tests, analyzer drift alarms, and bumpless transfer strategies. Train operators with dynamic simulations so manual actions support the same control philosophy used by automation.
#6 Low NOx burners, staging, and flue gas recirculation with downstream cleanup
Low NOx burners reduce peak flame temperature and control mixing to limit thermal NOx while maintaining stability. Fuel or air staging lowers oxygen availability near the flame core. Internal or external flue gas recirculation dilutes reactants and reduces adiabatic temperature where fan head allows. Validate performance with burner to burner NOx traverses and confirm CO remains within limits. When permits require deeper cuts, apply selective catalytic reduction or selective non catalytic reduction sized for turndown and sulfur tolerance. Protect catalysts from fouling and maintain ammonia to NOx ratios to prevent slip.
#7 Fuel gas quality, heating value control, and sulfur management
Stable flames demand predictable fuel composition and pressure. Install continuous Wobbe index or calorific value monitoring and integrate chromatograph data with density to compute control variables. Use knockout drums, coalescers, and strainers to prevent liquid carryover and particulate erosion of tips. Blend streams with high hydrogen and heavier components to smooth variability and maintain nozzle pressure. Treat fuel for sulfur when acid dew point or SO2 limits drive corrosion or environmental risk. Heat trace regulators and lines to prevent condensation, and document purging, line up, and relight practices for safe restarts.
#8 Refractory, insulation, and casing heat loss minimization
Wall, roof, and floor losses can consume several percent of fuel input. Survey casing temperatures using infrared cameras to locate damaged refractory, wet insulation, or hot spots near anchors and penetrations. Repair burner tiles, jambs, and expansion joints to block cold air ingress that distorts measured excess O2. Select materials for temperature rating, chemical resistance, and thermal shock from decoking. Add insulation to hot ducts and stack breechings where accessible, then reconfirm draft and fan load. Track heat loss in energy balances so the benefits of repairs remain visible to operations and maintenance teams.
#9 Coil metallurgy, coking control, and decoking strategy
Tube roughness and coke increase film temperature, fuel demand, and risk of failure. Select alloys, internal finishes, and coil layouts that resist carburization and coking for the service duty. Hold coil outlet temperature, velocity, and steam dilution within ranges that minimize cracking. Trend tube metal temperature hot spots and calculate remaining life using creep and oxidation models. Trigger decoking based on pressure drop, duty loss, and risk, not only calendar intervals. Use controlled steam air decoking or pigging procedures, then verify coil cleanliness and recalibrate heat balance targets after return to service.
#10 Monitoring, CEMS, and continuous improvement routines
Measure to improve. Install reliable stack analyzers for oxygen, carbon monoxide, nitrogen oxides, and where required sulfur dioxide, and connect results to a historian. Add draft, bridgewall temperature, tube metal temperature, fuel flow, and fan power to a daily performance dashboard. Calculate energy intensity and heat balance by shift, and investigate deviations after maintenance, weather changes, or feed shifts. Benchmark sister heaters by duty class and share best practices. Schedule periodic audits to validate emission factors, analyzer alignment, and control loop health, then update procedures, training, and targets based on findings.