Thread Content
Recently, the optimization and renovation project for the hydrogen production facilities associated with Huizhou Petrochemical Phase II is set to begin. The total investment for this project is estimated at 676.8 million yuan. It is planned to add 2 multi-nozzle water-coal slurry gasification furnaces, operating in a 1-in-service/1-backup configuration. The existing 3 E-gas hydrogen production units will be adjusted from a 2-in-service/1-backup setup to a 1-in-service/1-backup/1-under-repair configuration, and the supporting facilities will undergo adaptive modifications. Currently, there are only two operating E-Gas coal-to-hydrogen plants in the world, which feature high carbon conversion rates, high thermal efficiency, and low oxygen consumption. Compared with traditional natural gas-based hydrogen production processes, it can reduce costs by 20%–25%. This facility ensures that pollutants such as nitrogen oxides, sulfur dioxide, and wastewater are discharged at levels that meet the specified standards, reaching an advanced level for the industry. The process system of the E-Gas coal-to-hydrogen integrated plant is complex, and any issue in any stage can affect the stable operation of the system, which is why many companies hesitate to undertake it. Since 2018, without any prior experience in operating coal-to-hydrogen facilities or having any trial operation experience, Huizhou Petrochemical has, through continuous exploration and practice, overcome a series of key technical challenges such as blockages in the tubes of waste heat boilers, high failure rates in carbon recovery systems, and ash accumulation in the second stage of the gasifier. It developed an automated control system for the entire gasification process on its own, worked to localize imported equipment such as backflow valves for coke filters, filter elements, and carbon recovery systems, and innovatively introduced fiber-optic temperature measurement technology. It also formulated operating methods for waste heat boilers and low-load operation procedures for sulfur units, thereby ensuring the safe and stable operation of the E-Gas coal-to-hydrogen complex under various load conditions. Reason for adding new gasifiers: Since the E-GAS gasification hydrogen production unit of Huizhou Refining & Chemicals’ Phase II project came online in August 2018, frequent blockages in the system have created safety risks associated with operating it under design conditions. As a result, the gasifiers could only operate in a mode of one in use, one in standby, and one under maintenance, which meant that the amount of hydrogen and syngas produced was only half of what was designed. This has severely affected the long-term stable operation of the hydrogen-consuming devices in the refining area. Additionally, the frequent start-up and shutdown cycles led to large amounts of water gas being discharged directly into flares, increasing pollutant emissions. To address the aforementioned issues, CNOOC Huizhou Petrochemical plans to add 2 multi-nozzle water-coal slurry gasifiers, operating in a 1-in-service/1-backup configuration. The existing 3 E-gas hydrogen production units will be adjusted from a 2-in-service/1-backup setup to a 1-in-service/1-backup/1-under-repair arrangement, and the supporting facilities will undergo adaptive modifications. Upon completion of the renovation, the operating mode of the gasification-based hydrogen production plant was optimized to 2 in operation, 2 in standby, and 1 under maintenance. The production volumes of hydrogen and syngas were maintained at the levels specified in the environmental impact assessment for the second phase of the project, namely 151,400 tons of hydrogen and 119,000 tons of syngas per year. The design capacity of the gasification unit remains unchanged, while coal consumption decreases. The units related to the downstream stage of gasification, such as low-temperature methanol washing, acidic water stripping, and sulfur recovery, remain unchanged; there are no modifications to the incoming and outgoing materials or to the design capacity. The new installations mainly include a multi-nozzle gasification unit, slag water treatment, sewage hardening removal, a slag shed, and a 10kV substation. To make full use of the thermal energy of the water gas produced by the newly added multi-nozzle gasifier, a heat recovery system is installed, which can generate 64.0 tons/h of low-pressure steam at 0.4 MPa for use in the steam distribution network. With the E-gas vaporizer configured as 1 in operation, 1 in standby, and 1 under maintenance, the production of ultra-high pressure steam from heat recovery was reduced by 50%. Introduction to the existing coal-to-hydrogen plant in Huizhou Petrochemical Phase II: The coal-to-hydrogen facility at CNPC Huizhou Refining and Chemicaling Phase II utilizes the E-Gas water-coal slurry pressurized gasification technology provided by the American company CBI, to produce 150,000 tons per year of hydrogen and 117,600 tons per year of carbonyl synthesis gas. Hydrogen is supplied to the refinery’s hydrogenation units, while syngas is used in the butyl octanol production units. Commissioned in 2018. According to the publicly released environmental impact assessment information on the optimization and renovation of hydrogen production facilities, the status of each process is as follows. Gasification: The hydrogen production via E-GAS coal gasification in the second phase of Huizhou Refining & Chemical Complex uses the E-Gas slurry pressurized gasification technology developed by the American company CBI. There are 3 gasifiers in operation (2 in use and 1 as a backup), with an effective gasification capacity of 264,000 m3/h. The main raw material is Shenfu coal. The coal gasification unit uses coal, water, and oxygen as raw materials to produce syngas through a partial oxidation process. After being washed, the syngas is sent to the downstream units for hydrogen production. A small amount of syngas drawn from the lower part of stage 1 of the gasifier is washed in the gasification unit using a Venturi device and a circulating scrubber tower, before being sent to the extracted gas pretreatment unit for further washing and cooling. The transformation process employs a sulfur-resistant shift process with a low water-gas ratio to produce syngas with a high hydrogen content that meets the required CO concentration. It includes the syngas modification section and the low-temperature heat recovery section. The processed raw material syngas volume is 445,498 m3/h (on a wet basis), with the main product being 44.5×104 m3/h of shifted gas. Low-temperature methanol washing: The Ruchi low-temperature methanol washing process is used. It mainly includes transformed gas absorption, untransformed gas absorption, pre-wash liquid flashing, hydrogen sulfide flashing, carbon dioxide flashing, and thermal regeneration of methanol-rich liquid. The treated transformed gas volume is 42,4005 m3/h, and that of the untransformed gas is 20,995 m3/h. The pressure swing adsorption process is designed to produce 151,400 tons per year of industrial hydrogen with a purity of 99.9%. Purification is carried out using the PSA method; high-purity hydrogen is produced using purified shifted gas as raw material. The purified exhaust gas is pressurized by a compressor and then sent to the plant’s fuel gas network. It includes PSA purification, exhaust gas compression, and the hydrogenation section for purifying unconverted gas. For the refrigeration system, the freezing station utilizes propylene-based refrigeration technology to supply cooling capacity to the acid gas removal unit. The design provides 7400 kW of cooling capacity. The device is formed by propylene compression and propylene condensation cooling. Acidic water stripping unit: The design capacity of the unit is 80 tons per hour for stripping the acidic water discharged from the gasification scrubber (Series 1), and 90 tons per hour for stripping the acidic water generated from process condensate, sulfur-tolerant shift, and low-temperature methanol washing (Series 2). Both Series 1 and Series 2 adopt a single-tower low-pressure full-exhaust process. Acidic gas is sent for sulfur recovery, while the treated water is sent to the wastewater treatment plant and not reused. Sulfur recovery is designed with a capacity of 30,000 tons per year; under normal operating conditions, the sulfur production amount is 12,000 tons per year. The sulfur production section employs a modified CLAUS process consisting of a primary thermal reaction plus two stages of catalytic conversion reactions. Tail gas combustion employs a thermal combustion process, while the flue gas is denitrified using SCR ； The ion liquid absorption section uses ion liquids to remove sulfur dioxide from flue gas. This includes sulfur production, flue gas combustion, liquid sulfur degassing and loading, ionic liquid absorption, and utility systems. Coal-to-hydrogen is an important approach to the effective utilization of coal resources, offering competitive advantages in terms of safety and environmental protection, mature technology, and low cost. In the future, Huizhou Petrochemical will continue to advocate for the clean and efficient use of coal in the field of refining and chemical manufacturing, thereby contributing to the transformation of Huizhou’s energy structure and its development in a green and low-carbon manner.