【Haichuan Chemical Salary News】Southwest Chemical Research Institute: Hydrogen production using pressure swing adsorption on coke oven gas

The PSA hydrogen production turnkey project signed between the Southwest Research Institute and Ma’anshan Chenma Hydrogen Energy Technology Co., Ltd. is a key project within the chemical energy sector of MaSteel Group. The project covers an area of approximately 40 mu, with a total investment of around 200 million yuan. It makes use of internationally advanced patented and proprietary technologies from the Southwest Research Institute, such as those for removing tar and naphthalene from coke oven gas, benzene removal through temperature-dependent adsorption, hydrogen purification via pressure-swapped adsorption, as well as hydrogen purification and testing processes. These technologies enable full utilization of the excess coke oven gas available at the MaSteel Group to produce high-purity hydrogen with a purity of over 99.999%; further hydrogen purification techniques are then used to produce raw hydrogen. This project serves as a significant model for extracting inexpensive hydrogen, a raw material for hydrogen fuel cells, from the gas coke oven gas emitted by typical heavily polluting industries. It not only promotes the development of clean energy in the form of hydrogen but also helps to reduce waste gas emissions in industries such as steel and metallurgy, thereby minimizing environmental pollution and generating favorable economic benefits. Upon completion, the project will enable the reduction of about 120 million cubic meters of coke oven gas per year, as well as the production of about 48 million cubic meters of high-purity hydrogen per year. It is possible to achieve annual sales revenue of around 210 million yuan, and annual after-tax profits of around 50 million yuan.

Moving from mixed emissions to sorted recycling in order to turn waste into valuable raw materials, this project serves as a significant model for extracting inexpensive hydrogen, a raw material for hydrogen fuel cells, from the gas produced by coke ovens in industries that typically cause heavy pollution. It not only promotes the development of clean energy in the form of hydrogen but also helps to reduce waste emissions from industries such as steel and metallurgy, thereby minimizing environmental pollution while generating good economic benefits. Upon completion, the project will enable the reduction of about 120 million cubic meters of coke oven gas per year, as well as the production of about 48 million cubic meters of high-purity hydrogen per year. It is possible to achieve annual sales revenue of around 210 million yuan, and annual after-tax profits of around 50 million yuan.

The common methods for hydrogen extraction from coke oven gas include membrane separation, cryogenic separation, and pressure swing adsorption (PSA) technologies. 01 | Membrane separation hydrogen production technology. The principle of membrane separation technology lies in the selective permeability of membranes; at the molecular level, when mixtures of molecules with different sizes pass through a semipermeable membrane, those molecules with a size larger than the membrane’s retention threshold cannot pass through and return to the tank, while those with a size smaller than this threshold pass through the membrane to form the dialysate. However, in engineering operations, due to the unevenity of the fluid flow cross-section after pumping, a small amount of substances that move slowly through the membrane also penetrate to the hydrogen-rich side of the membrane. The purity of products produced by membrane separation hydrogen extraction technology is generally between 85% and 99%, while the hydrogen recovery rate is 65% to 80%. 02 | Cryogenic separation hydrogen extraction technology. Cryogenic separation technology is a process that utilizes the difference in condensation points of various gases to gradually liquefy mixed gases, thereby achieving gas separation. In the deep processing of coke oven gas, cryogenic separation is rarely used alone for the separation and purification of hydrogen; it is more often employed in conjunction with the separation and purification of methane. The purity of the hydrogen product obtained in this way can reach over 85%, while the recovery rate is around 95%. However, since the liquefaction temperatures of gases such as nitrogen and methane are very low, large-scale cryogenic separation units require a significant amount of cooling energy to liquefy the target gases, resulting in high energy consumption. In addition, due to the extremely low temperatures of the liquefied gases, substantial investment is needed in pipeline materials and insulation materials. 03 | Pressure Swing Adsorption Hydrogen Extraction Technology. Pressure Swing Adsorption hydrogen extraction technology is a gas separation process that has developed over the past few years. It utilizes the difference in adsorption capabilities of adsorbents for various substances at different pressures to achieve gas separation and purification. Thanks to its high degree of automation and low energy consumption, this technology has gradually increased its market share; it is widely used in areas such as hydrogen extraction and carbon removal in gas separation processes. Due to its advantages such as low energy consumption, high degree of automation, fast gas production rate, and low requirements for the purity of the feed gas, pressure swing adsorption technology is widely used in coking plants. The purity of the gas produced by this technology can reach up to 99.9%, while the recovery rate ranges from 60% to 90%. In some production lines, in order to stabilize the hydrogen purity of the product, there are also those that incorporate a membrane separation process in series after the pressure swing adsorption step. In addition, the conversion of methane and methanol into hydrogen, as well as the production of hydrogen from natural gas, are also widely used in industry, so no further explanation is needed.

As can be seen from Table 3, in terms of cost, both coal coking-based hydrogen production and gasification-based hydrogen production have advantages. Depending on the type of coal, the cost of large-scale coal-to-hydrogen production can be kept around 0.8 yuan per m3; in some projects it is even as low as 0.4–0.5 yuan per m3. Compared to natural gas-based hydrogen production, which costs at least 2 yuan/m3, as well as water electrolysis for hydrogen production that is even more expensive, the former offers significant economic advantages. It is understood that the 80 gasification units already built by **Energy Group (formerly Shenhua Group), if used to supply hydrogen for fuel cell vehicles, could produce 4 million tons of hydrogen per year, enough to power 40 million vehicles. Han Hongmei, deputy chief engineer of the Energy and Chemical Engineering Department at the Petroleum and Chemical Industry Planning Institute, also said in an interview: “A coking plant with a capacity of 2 million tons per year can produce hydrogen by using 5% of the coker gas generated as feedstock, enough to supply 100 taxis, 300 buses, and 100 delivery vehicles.” ”

According to news on July 14, the 10,000 cubic meters per hour PSA unit part of Dongming CNPC Fuel Petrochemical Co., Ltd.’s product quality improvement project – a 2 million tons per year diesel hydroprocessing unit – was successfully put into operation for trial runs recently, producing hydrogen of qualified quality with a purity of ≥99.9%. The facility utilizes the advanced PSA hydrogen production technology and proprietary equipment from Shanghai Huaxi Chemical Technology Co., Ltd., with the engineering design carried out by Anhui Huadong Chemical Pharmaceutical Engineering Co., Ltd. It is reported that this facility uses hydrogen desulfurization light gas and waste hydrogen as feed gases, and purifies hydrogen through pressure swing adsorption; its production capacity is 10,000 Nm³/h of hydrogen with a purity of ≥99.9%, and the purified hydrogen is used in oil hydrogenation units. The hydrogenation unit employs a special treatment process, adsorbents, and startup methods developed by Shanghai Huaxi to ensure its long-term stable operation; it has now been officially delivered for use by Dongming CNPC Fuel Petrochemical Co., Ltd.