【3D Process Flow】Summary Post -- Xinjiang Zhundong’s 33.8-billion-yuan green hydrogen industry chain: the entire process from hydrogen production via wind and solar power to its use in chemical industries

03 Large-scale alkaline electrolysis for hydrogen production: Alkaline water electrolysis for hydrogen production (ALK) is currently the only electrolysis technology that has undergone engineering verification at the 100-megawatt scale, and it is also the core equipment chosen for the Zhundong project. Compared to the competing PEM electrolysis technology, the advantage of ALK lies in the use of nickel (Ni) as the electrode material instead of platinum-group metals, resulting in costs that are about 50-70% lower ； Using 30% KOH liquid electrolytes instead of the expensive Nafion proton exchange membrane results in low marginal costs for scaling up ； The hydrogen production rate per cell has been verified to be 1000 Nm³/h (approximately 90 kg/h), allowing for direct stacking for scale-up. Working principle of a single alkaline electrolyzer: Two nickel-steel bipolar plates serve as the cathode and anode respectively, and are immersed in a 30% KOH aqueous solution (the alkaline environment enables OH⁻ ions to conduct electricity). When direct current is applied, a reduction reaction occurs at the cathode: 2H₂O + 2e⁻ → H₂↑ + 2OH⁻⁻ ； At the anode, an oxidation reaction occurs: 4OH⁻ → O₂↑ + 2H₂O + 4e⁻. The anode and cathode are separated by a diaphragm (Zirfon porous composite membrane) to prevent the mixing of H₂ and O₂, while allowing the KOH solution and OH⁻ ions to pass through freely. The electrolyte continuously flows through the tank driven by a circulation pump, carrying away the heat of reaction (to maintain an operating temperature of 80°C), while simultaneously transporting the bubbles dissolved in the electrolyte to a gas-liquid separator outside the tank for collection. The main engineering challenge in the BaiTai-scale projects in Jungdong lies in the DC power supply system: each electrolyzer with a capacity of 1000 Nm³/h requires approximately 4–5 MW of DC power, so 100 such electrolyzers together need 400–500 MW. This requires a large number of rectifier transformers (which convert high-voltage alternating current into low-voltage direct current with high current), each of which has an efficiency of around 98%; at a scale of 100 units, the total rectification loss amounts to approximately 8–10 MW. Furthermore, the uniform preparation, recycling, and regeneration of KOH electrolyte are also key infrastructure components for large-scale operation.

04 Hydrogen purification + storage and transportation: The purity of hydrogen produced by alkaline electrolysis is approximately 99.5–99.9%, with the main impurities being water vapor (from the KOH aqueous solution) and trace amounts of oxygen (due to membrane permeation). Downstream chemical industries have varying requirements for hydrogen purity: ammonia synthesis requires H₂ purity of ≥99.9%, methanol synthesis requires ≥99.99%, and fuel cells require ≥99.999%. Therefore, purification is a necessary step before hydrogen enters the chemical pipelines. The Zhundong project employs a PSA (Pressure Swing Adsorption) purification process: multiple towers (usually 4–12) take turns adsorbing impurities under high pressure (activated carbon/molecular sieves selectively adsorb water, O₂, CO, CO₂, etc.), and undergoing regeneration and desorption under low pressure; sequential switching between the towers enables continuous output. The advantages of PSA are low energy consumption (electricity consumption of about 0.2–0.5 kWh/kg H₂), simple operation, and effectiveness against various impurities ； The downside is that the H₂ recovery rate is about 85–95%, with approximately 5–15% of H₂ lost along with the regenerated exhaust gas. Purified hydrogen needs to be compressed in order to be stored and transported. The Zhundong project plans three complementary storage and transportation solutions: ① High-pressure storage tanks (35–70 MPa, pressurized using multi-stage reciprocating compressors), suitable for short-term storage (hours to days), with each tank having a capacity of several tons of H₂ ； ②Long-distance pipelines (operating pressure of 4–10 MPa; hydrogen pipelines require special steels resistant to hydrogen embrittlement) are suitable for large-scale, continuous transportation to downstream chemical plants ； ③Hydrogen storage in salt caverns represents the most strategically valuable innovation of this project: by utilizing the underground cavities formed by deep salt deposits in the Qudong area (with a single cavity having a volume of hundreds of thousands of m³), hydrogen can be stored at pressures of 10–20 MPa. This approach enables the adjustment of supply and demand on a seasonal basis – hydrogen is injected during the summer when there is ample sunlight and excess electricity, while it is extracted during winter when there is high demand from the chemical industry. The theoretical storage capacity of a single cavity can reach several thousand tons, which is hundreds of times higher than that of surface storage tanks.

05 Utilization in the green hydrogen chemical industry: Once green hydrogen enters the chemical industry, it is utilized through three different pathways. The core value of each route lies not only in manufacturing products, but also in replacing traditional gray hydrogen (hydrogen produced by natural gas reforming) with green hydrogen, thereby achieving a reduction of 10–15 tons of CO₂ per ton of product produced. 「\"Green hydrogen → synthetic ammonia\" is the largest-scale route and the core approach for the decarbonization of ammonia. Traditional ammonia synthesis (Haber-Bosch process) uses hydrogen produced by the reforming of natural gas, resulting in approximately 2.5 tons of CO emitted per ton of ammonia produced₂ ； With the switch to green hydrogen, carbon emissions drop to near zero. Process flow: The air separation unit separates air to obtain N₂ (99.9%), which is then mixed with green H₂ in a molar ratio of N₂:H₂ = 1:3. Ammonia (NH₃) is produced through a reaction at 450°C and 15–25 MPa in the presence of an iron-based catalyst (Fe₃O₄), with K₂O and Al₂O₃ as additives. The equilibrium conversion rate of the reaction is approximately 15–25% per pass; the unreacted gas is recycled back to the reactor, resulting in an ultimate ammonia yield of >98%. The planned production capacity for green ammonia in Jungdong is around 400,000 tons per year, intended mainly to supply the local fertilizer market in Xinjiang (Xinjiang is China’s largest agricultural cotton-producing region, with high demand for fertilizers). 「\"Green hydrogen → Methanol\": This process utilizes the hydrogenation of CO₂ (CO₂ + 3H₂ → CH3OH + H2O), thereby sequestering CO₂ while producing chemical raw materials with high added value. The reaction is carried out on a Cu/ZnO/Al₂O₃ catalyst (250°C, 5-10 MPa), with a one-pass conversion rate of approximately 25-35%; the product is purified by distillation to yield AA-grade methanol (purity ≥99.85%). Methanol is an important basic chemical raw material that can be further used to produce ethylene/propane (MTO process), formaldehyde, acetic acid, and others. 「\"Green hydrogen → hydrogenation in refining processes\" represents a direct replacement for the gray hydrogen currently used in refineries; it is the shortest-term implementation approach that is closest to the market and most cost-effective for Qudong green hydrogen. The high-pressure H₂ required for hydroprocessing of oil products (desulfurization, denitration) and hydrocracking can be supplied directly through pipeline-based green hydrogen, without the need to build any new chemical facilities – simply replacing the existing gray hydrogen supply system suffices to achieve large-scale emissions reductions

【3D Process Flow】Summary Post–Xinjiang Zhundong’s 33.8-billion-yuan green hydrogen industry chain: the entire process from hydrogen production via wind and solar power to its use in chemical industries https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=5717774 (Source: Huchuan Chemical Industry Forum (Hua Hai Chuan Liu hcbbs))

【Haichuan Equipment Guessing Game】What is tied to the pipe? ? https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=5718037 (Source: Haichuan Chemical Industry Forum (Hua Hai Chuan Liu hcbbs))