Record of the integrated SE water-coal (coke) slurry gasification technology of East China University of Science and Technology

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Record of SE Water-Coal (Coke) Slurry Gasification Technology from East China University of Science and Technology – Author/Source: Sinochem New Network, Date: 2019-09-20, Clicks: 92. At the recently held 21st China International Industry Fair, the SE water-coal (coke) slurry gasification technology project, led by Professor Dai Zhenghua from the Institute of Clean Coal Technology at East China University of Science and Technology, offered an efficient technical solution. This project features three innovations: dual-slurry and dual-hydrogen peroxide nozzles, a plug-flow gasification furnace, and automatic coal slurry distribution. It overcomes the problem of easy ablation of the nozzles, and boasts a simple process flow and low investment costs. 　　On September 18, East China University of Science and Technology and Sinopec signed another cooperation agreement regarding the SE water-coal (coke) slurry gasification technology at the Industry Expo. This time, the engineering design for 3 2,500-ton-class water-coal (coke) slurry gasification units is set to be carried out at Zhenhai Refining & Chemical Co., Ltd. 　　Three innovations to overcome challenges Hydrogen is currently the most widely used chemical raw material in the petrochemical industry. Traditional methods for producing hydrogen in refineries are costly, while hydrogen production via water-coal slurry gasification is one of the most cost-effective large-scale methods currently available in refineries. However, coal-based hydrogen production faces significant challenges such as a short gasification operation cycle, easy ablation of nozzles, and a large amount of fine ash. 　　The short service life of nozzles has always been a challenge that hinders the long-term operation of gasification furnaces. By the end of its usage period, the nozzles suffer severe ablation and wear, resulting in poor atomization performance. To ensure safe operation, it is necessary to stop the plant and replace the nozzles, which makes it difficult to provide hydrogen supply in a stable manner for the refinery’s subsequent systems over the long term. Therefore, extending the service life of nozzles is one of the effective ways to increase the operating cycle of gasification furnaces and boost efficiency, which is particularly important for refineries. 　　Aiming to address this industry challenge, the Institute of Clean Coal Technology at East China University of Science and Technology began a 10-year effort to develop relevant technologies starting in 2009. 　　The nozzle is a key device for delivering coal slurry and oxygen to the gasification furnace, where the temperature reaches up to 1300 degrees Celsius. If the combustion intensity at the tip of the nozzle can be effectively reduced, its lifespan can be significantly extended. To this end, based on their research into the oxidation reaction pathways within the gasifier, the R&D team invented a dual-coal (coke) slurry channel gasification nozzle – in this nozzle, the materials flowing through its four channels are oxygen, slurry, oxygen, and slurry from inside to outside. The greatest advantage of this arrangement is that the water-coal slurry in the outermost channel acts as a cooling medium, enhancing the nozzle’s self-cooling capability and thereby significantly extending its service life. 　　Refineries have very high requirements for hydrogen purity; to reduce the burden on the purification processes, it is necessary to minimize the amount of fine ash generated during coal gasification. The so-called \"fine ash\" is an impurity that enters subsequent processes along with the gas; in contrast, the larger \"coarse slag\" is a liquid slag similar to magma, and when cooled by water, carbon reacts more fully. 　　Based on research into the reaction characteristics of particles within the gasification furnace and the control of the flow field inside it, the development team proposed a flow field structure characterized by a predominantly plug flow pattern. This approach significantly improved the distribution of particle residence time as well as the furnace temperature, resulting in a carbon conversion rate of over 99%. The ratio of fine ash to coarse ash was reduced from approximately 4:6 in existing technologies to 2:8, while the residual carbon content in the ash also decreased from around 30% in existing technologies to about 20%. 　　Furthermore, based on their research on the complex rheology of water-coal slurry, the research team developed high-precision mathematical models for the distribution of slurry flow rate and resistance. They also invented a multi-channel distribution technique for coal slurry that utilizes a combination of branch streams and throttling components, enabling precise automatic distribution of two streams of coal slurry without the need for pumps or control devices. 　　Successful industrial application: On January 30, 2019, the entire process of Sinopec Zhenhai Refining & Chemical Company’s coal and coke hydrogen production unit (POX project) was successfully operationalized, with qualified products being produced – marking the successful commissioning of a hydrogen production unit that utilizes domestically developed high-pressure water-coal (or coke) slurry gasification technology. 　　This is the first industrial application of the SE water-coal (coke) slurry gasification complete set of technology. In 2012, Sinopec collaborated with East China University of Science and Technology to establish the Sinopec–East China University of Science and Technology Gasification Technology Research Center. Through industry-university-research cooperation, efficient coal gasification technologies were developed, among which the SE water-coal (coke) slurry gasification technology is one such technology; it was included in Sinopec’s “Ten Dragon” key technology research projects. 　　As a key unit in Zhenhai Refining & Chemical’s POX project, the SE water-coal (coke) slurry gasification unit employs SE water-coal (coke) slurry gasification technology. It is equipped with three gasifiers capable of processing thousands of tons of coal per day, with two in operation and one as a backup; it uses a quenching process and operates at a pressure of 6.5 MPa. The 3 gasification furnaces were successfully commissioned on January 30, February 20, and April 22, 2019, respectively, and are now in a stage of stable operation. 　　Advantages in the utilization of hazardous waste Refining and chemical enterprises generate various types of hazardous waste, such as oily sludge, spent catalysts, and waste oil slurries; entrusting their disposal to environmental protection companies comes at a high cost. If companies can recycle materials, wouldn’t that bring economic and environmental benefits? Another technical advantage of the SE water-coal (coke) slurry gasification technology becomes apparent: it transforms waste into valuable resources by enabling the simultaneous treatment of liquid and solid wastes generated by refining companies. “Through experiments, we have found that the calorific value of oily sludge is sometimes similar to that of coal, giving it gasification potential. ”Professor Dai Zhenghua told the reporters. 　　Professor Dai Zhenghua still remembers the tension surrounding the commissioning of the first gasifier in Zhenhai Refining & Chemical’s POX project. It was near the Spring Festival at that time; although schools were already on holiday, as part of the R&D team for SE water-coal (coke) slurry gasification technology, they, together with the company, designers, and contractors, were present at Zhenhai Refining & Chemical Plant to witness the successful commissioning of the gasifier. 　　After a brief surge of excitement, the team remained “ready to follow orders at any time.” “After all, it is the first prototype device, so it still has a certain experimental nature. ”According to Professor Dai Zhenghua, after the first gasification furnace had been in operation for over 60 days, inspections showed that there was no significant damage to the nozzles. “For us, this represents a new starting point.” ”