The HCl burner is a core component of the hydrochloric acid synthesis furnace, responsible for mixing chlorine gas and hydrogen in precise proportions and burning them to produce hydrogen chloride gas. Since 1960, more than 600 units of the Mersen Sintaclor series have been installed worldwide, with individual capacities ranging from 2 to 180 metric tons per day. The product’s acid concentration can reach 38%, and free chlorine is controlled to less than 1 ppm. HCl burner maintenance directly determines the operational safety of the synthesis furnace. At a chemical plant in Le Pont-de-Claix, France, the hydrogen flow rate gradually decreased during the night, causing condensation to form an ice blockage in the pipeline and resulting in the burner extinguishing. After maintenance personnel purged the flame arrester and restarted the system, a hydrogen pressure spike caused operators to partially close the hydrogen feed valve. Unreacted chlorine gas accumulated inside the burner, forming an explosive mixture with the recirculating hydrogen, which was ignited by static electricity or sunlight, causing the pipeline to rupture. Following the incident, the plant enhanced the thermal insulation of the hydrogen supply lines and re-evaluated safety thresholds in collaboration with the burner supplier. This article builds upon the "HCl Furnace Maintenance" framework outlined in the hydrochloric acid synthesis furnace maintenance and decommissioning procedures, focusing on the specific operations involved in "HCl Burner Removal" and "HCl Burner Disassembly."
The first step in HCl Burner Maintenance is preparation and isolation. After emptying the furnace of its contents, nitrogen is purged through the system until oxygen and combustible gas levels meet specified standards. Work may only commence after blind flanges have been installed on the chlorine and hydrogen pipelines. SGL Carbon recommends conducting a performance inspection every 15,000 operating hours or 3 years, and maintaining long-term operational capability through disassembly, cleaning, and resealing every 25,000 hours or 5 years. The gas feed pressure for Sintaclor burners is typically maintained between 77 and 80 inches of water column; deviations from this range directly affect combustion efficiency and safety.
During the disassembly and inspection phase, first remove the sight glass to verify that the glass is intact, then remove the burner head to inspect the concentric tubes. Chlorine flows through the inner tube, while hydrogen flows through the annular gap between the inner and outer tubes. Due to prolonged high-temperature oxidation and chlorine corrosion, the ends of the concentric tubes must be replaced if they are more than 20 mm in length. Graphite burner head pulverization is a common issue; SGL confirms that the reaction between graphite and oxygen at high temperatures is unavoidable, and the graphite burner head typically needs to be replaced after 2 to 3 years of operation. Checking the gap of the ignition electrode is equally critical; an excessive gap can cause ignition failure and must be adjusted to approximately 1.5 mm according to the manufacturer’s specifications. After repairs and replacements are completed, proceed to reassembly and commissioning. The deviation in the verticality of the burner head must be controlled within 1 mm, and the deviation in the concentricity between the metal nozzle and the brick opening must also not exceed 1 mm.
The removal of the HCl burner begins with shutdown and isolation. Gradually reduce the gas flow into the furnace, shutting off the chlorine first, followed by the hydrogen. After nitrogen purging meets specifications, relieve pressure and allow the system to cool. Once the flanges on the chlorine-hydrogen pipeline are disconnected, install blind flanges. SGL recommends disassembly, cleaning, and resealing at least once every three years.
When removing the connecting flanges, use two wrenches in coordination to avoid damaging the burner body due to force applied to only one side. The sealing surfaces of graphite joints are extremely fragile; do not apply direct force to the graphite flange surfaces with a pry bar during disassembly. After the entire burner has been removed from the furnace bottom, transport it using specialized lifting equipment. Keep it level during lifting to prevent the concentric tubes from bending under their own weight. Immediately cover the exposed flange surfaces with protective caps to prevent impact damage.
The disassembly sequence for the HCl burner is: concentric tube, nozzle, ignition electrode, sight glass, and gasket. Before removing the concentric tube, measure and record its original protrusion length; restore it to the same position during reassembly. When removing the nozzle, check the spray holes for blockages or wear; graphite nozzles with slag holes or cracks must be replaced. If the ceramic insulating portion of the ignition electrode has cracks or carbon buildup, replace it immediately. Replace the sight glass after each disassembly inspection as needed; gaskets must never be reused. Number and store all components after removal; avoid direct contact between graphite parts and steel tools.
After inspection, proceed with reassembly and alignment. The vertical deviation of the burner head must not exceed 1 mm, and the concentricity deviation between the concentric tube and the furnace centerline must also be controlled within 1 mm. Mersen offers automated burner diagnostics and online combustion diagnostics as optional components in its Sintaclor system, enabling real-time monitoring of combustion conditions during operation. After reassembly, perform a leak test by pressurizing with nitrogen to the operating pressure and inspecting all flanges and sealing surfaces with leak detection fluid. Once the leak test is passed, ignition and commissioning are performed. First, nitrogen is introduced to purge the furnace chamber, followed by the sequential activation of hydrogen and chlorine, while observing the flame color. A normal flame is bluish-white; a yellowish or dull flame indicates a deviation in the hydrogen-to-chlorine ratio, which must be adjusted immediately. After successful ignition and commissioning, the system transitions to normal operation.
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