Industrial hydrochloric acid in China is not a single-product commodity. It is produced as synthetic acid from chlor-alkali chlorine/hydrogen combustion and as byproduct acid from chlorination, fluorination, and organic intermediate plants. The geographic distribution of HCl factories therefore follows chlor-alkali clusters by province. The question Where Are HCl Factories in China? Chlor-Alkali Clusters by Province is best answered by mapping integrated chemical parks rather than stand-alone acid units. Shandong, Jiangsu, Zhejiang, Henan, Inner Mongolia, Xinjiang, Hebei, and Sichuan contain the largest reported clusters. Synthetic HCl is formed by burning chlorine and hydrogen in graphite or quartz combustion chambers and absorbing the gas in adiabatic or falling-film absorbers to 31–35 wt%. Byproduct HCl streams are recovered from chlorinated paraffin, chlorinated benzene, fluorochemical, and vinyl chloride intermediate operations. Merchant acid movement is limited by corrosion and fume pressure; bulk haul economics typically constrain 31 wt% liquid acid to 300–500 km. Published data for HCl-specific provincial capacity are limited; chlor-alkali caustic soda capacity and integrated downstream chlorination units are the most reliable indicators.

What Explains the Province-Level Concentration of Chlor-Alkali-Derived HCl?

Provincial concentration is driven by salt brine, electricity tariffs, downstream alumina and steel demand, and environmental permitting. Membrane chlor-alkali electrolysis produces approximately 1.13 t of caustic soda and 0.028 t of hydrogen per tonne of chlorine. When HCl synthesis is operated to balance chlorine demand, each tonne of chlorine can yield approximately 1.03 t of HCl gas, equivalent to roughly 3.3 t of 31 wt% acid. Coastal provinces with large brine fields and port access have historically added HCl synthesis capacity to convert surplus chlorine into storable acid for regional alumina, rare-earth, and steel-pickling off-take.

These shares should not be read as HCl capacity. A province may hold large caustic soda capacity but report little merchant HCl because acid is consumed captively in PVC or alumina circuits. In Shandong, merchant acid is comparatively liquid because multiple chlor-alkali sites lack captive VCM capacity and sell acid to steel and alumina customers. In Xinjiang, the opposite occurs: integrated PVC complexes consume HCl within the acetylene-to-VCM route, leaving limited merchant volume.

Shandong’s Weifang–Dongying–Zibo Transect as a Synthetic Acid Complex

In Shandong, brine wells around Weifang and underground salt formations in Dongying feed membrane electrolyzer lines that commonly operate at current densities of 3–6 kA/m². Chlorine and hydrogen from electrolysis enter HCl synthesis furnaces built with graphite combustion chambers and water-cooled steel shells. The combustion is controlled at a slight excess of hydrogen to minimize chlorine slip; flame temperature can exceed 2000 °C, and the synthesis unit is interlocked to shut down on burner flame failure or chlorine breakthrough. Absorption trains use falling-film absorbers followed by tail-gas scrubbers. Acid strength is held at 31–35 wt% because atmospheric HCl-water azeotrope behaviour near 20.2 wt% and vapour pressure rise above 35 wt% make higher strengths more difficult to store and load as merchant liquid.

Shandong acid balances are coupled to alumina refining and steel pickling. Spent pickling acid containing ferrous chloride is regenerated by spray roasting or fluidized-bed hydrolysis, releasing HCl gas that returns to the absorption loop. The regeneration units have annual maintenance cycles that create regional acid shortages or surpluses depending on outage timing. Underground Shandong brines often carry sulfate and calcium impurities; chlorine purity from electrolysis may be affected if brine polishing is insufficient, and HCl synthesis feed hydrogen can contain traces of oxygen that require catalytic removal to avoid explosive limits in the burner feed header.

Chlorine balance is the operational variable that links HCl availability to provincial capacity. In chlor-alkali, chlorine is the principal coproduct and cannot be stored economically in large quantities; when PVC and chlorinated intermediate demand slows, operators shift chlorine to HCl synthesis if acid storage and market demand exist. The shift is constrained by absorption train capacity, hydrogen availability, and burner turndown limits. Synthesis units have finite turndown, often 30–100% of design feed rate, below which flame instability and chlorine slip occur. Therefore HCl production cannot always absorb the full swing of chlorine supply. Shandong sites with larger HCl synthesis and storage capacity manage this swing more effectively than integrated Xinjiang PVC sites, where the VCM train is the primary chlorine sink.

Across the Yangtze River Delta, acid supply is split between chlor-alkali sites in Lianyungang, Nanjing, and Yancheng and byproduct streams from chlorinated benzenes, chlorinated paraffins, and fluorinated intermediates in the Ningbo–Shaoxing–Quzhou corridor. In Jiangsu, older acid synthesis units were forced into chemical parks with centralized wastewater treatment by Yangtze River protection rules; batch-to-batch byproduct acid from aromatic chlorination carries dissolved organics and must be stripped or filtered before it can meet GB/T 320-2006 limits for residue and metals. Zhejiang byproduct acid is tied to fluoropolymer and refrigerant operating rates; when fluorination lines reduce throughput, the local merchant acid surplus tightens. Published data for the exact merchant share of Jiangsu and Zhejiang HCl is limited, but the port and industrial park infrastructure makes these provinces the most active coastal merchant market outside Shandong.

In Henan, Hebei, and Sichuan, HCl production clusters are more inland and are linked to alumina, PVC, and chlorinated intermediate demand. Henan sites around Jiaozuo and Zhengzhou supply acid to alumina and refractory producers; Hebei facilities in Cangzhou and Shijiazhuang serve PVC and agrochemical chains; Sichuan brine resources support chlor-alkali units that feed titanium dioxide and phosphate chemicals. These inland plants operate with shorter acid haul distances to local consumers, and merchant acid prices respond strongly to local alumina and steel production rates rather than port-export economics.

When Coal-Based VCM Chains in Inner Mongolia and Xinjiang Absorb Synthetic HCl

In the calcium carbide acetylene route to vinyl chloride, acetylene is reacted with HCl over a mercuric chloride or low-mercury catalyst. The HCl consumed in this reaction is often synthesized on-site from chlorine and hydrogen produced by salt electrolysis. As a result, large chlor-alkali complexes in Inner Mongolia and Xinjiang are not reliable merchant HCl suppliers; acid from the synthesis unit is routed directly to the VCM reactor. If the VCM train slows for maintenance or mercury catalyst replacement, the site may divert HCl to storage or local merchant sale, but storage capacity is typically limited to a few days of production. In Inner Mongolia, complexes in Wuhai, Ordos, and Baotou operate under provincial energy intensity audits that can curtail electrolyzer load during summer peak power periods. This load reduction lowers both caustic and chlorine output, reducing HCl synthesis even if downstream VCM demand remains stable.

Xinjiang’s integrated salt-coal-PVC complexes around Urumqi, Shihezi, and Korla benefit from low electricity costs but face long rail distances to coastal acid consumers. Railcar loading of 31 wt% HCl requires lined tank cars and vent protection; winter temperatures below −15 °C in Xinjiang and Inner Mongolia increase acid viscosity and can cause freezing in stagnant loading lines. Published HCl capacity data for these integrated sites is limited, as acid is seldom reported as merchant output. The effective merchant availability from these provincial clusters depends on the difference between chlorine synthesis capacity and PVC acetylene consumption, a site-specific value that is not captured by caustic soda capacity alone.

Merchant Acid Logistics, Corrosion Control, and Standard-Grade Boundaries

Merchant hydrochloric acid in China is moved predominantly as 31–35 wt% liquid in rubber-lined carbon steel tanks, fiberglass-reinforced plastic tank trailers, and high-density polyethylene IBCs for smaller quantities. Hydrochloric acid solution is classified under UN 1789 for corrosive liquid transport; loading terminals in Shandong and Jiangsu commonly use closed-loop vapour recovery with pH-neutralizing scrubbers. Scrubber outlet HCl concentration is often controlled to 10–30 mg/Nm³ under site permits. Fuming acid above 36 wt% is generally avoided in bulk because vapour pressure increases and vent treatment costs rise. GB/T 320-2006 defines industrial hydrochloric acid grades by total acidity, iron, sulfate, and residue on ignition; electronic and food-grade acid require additional purification units such as high-purity absorption, sub-boiling distillation, or ion exchange.

Storage at northern provincial sites requires heat tracing or insulated tanks where ambient temperatures drop below −15 °C. Acid tanks are vented through scrubbers or desiccated vent systems to avoid moisture ingress and fume release. Transfer piping is typically lined with PVDF or polypropylene for low-iron service, while pumps use magnetically coupled sealless designs to reduce leak points. Corrosion is managed by selecting alloy-free non-metallic materials and by keeping acid velocities below 2 m/s in thermoplastic piping to limit erosion-corrosion at fittings. Atmospheric storage tanks for 31 wt% merchant acid are commonly sized for holding times of 5–15 days, with scrubber liquid returned to the tank to maintain acid strength and reduce water addition.

Provincial permitting has reshaped site viability. Jiangsu’s Yangtze River protection actions restricted new chemical projects within 1 km of the river; Shandong’s chemical park consolidation eliminated scattered synthesis units below threshold scale; Inner Mongolia’s energy intensity audits curtailed chlor-alkali operating rates during peak load periods. These administrative constraints affect merchant acid availability more than the basic HCl synthesis chemistry. Facilities without captive acid demand and without rail access face periodic shutdown when downstream alumina or steel demand contracts; the result is regional price volatility in merchant acid, particularly during winter heating-season logistics restrictions in northern provinces.