The long-term operation of the gasification unit at Enechemical Company has reached an internationally leading level

Thread Content

The long-term operation of the gasification units at Enehua Company has reached an internationally leading level. Author/Source: Enehua Company. Date: 2021-01-15. Clicks: 25. Thanks to technological innovation, the continuous operating time of a single BGL gasifier has reached 272 days. In recent years, China Coal Enehua Company has attached great importance to technological innovation, treating it as a vital factor for the company’s survival and development. Especially in 2020, which was designated as the year for improving the company’s basic management, significant progress was made in technological innovation and technological upgrades, alongside the continuous improvement in the level of refined management. To address various issues that arise over the long-term operation of the fixed-bed gasification system in gasification plants, such as a high proportion of raw coal powder in the feed, wear and leakage in water pipelines, leaks in agitators, blockages at the slag discharge ports, as well as blockages in the phenol-amine recovery heat exchangers and tray stacks, the company brought in specialized technical personnel to carry out thorough process optimization and equipment upgrades, thereby ensuring the stable, efficient, and reliable operation of the fixed-bed gasification system. First, optimize the coal preparation and transfer system to effectively reduce the powder content of the raw coal entering the furnace. The gasification feed coal must pass through 6 conveyor belts to be transported from the coal storage area outside the plant to the gasification plant, with a powder content as high as 20%. To address this issue, through research, analysis, and field tests, the coal preparation chute was changed from a straight layout to a curved one, which reduced the damage to the raw coal during transfer and significantly lowered the proportion of raw coal that ended up as powder upon entering the furnace. Second, carry out modifications to the coal lock and slag lock cone valves of the gasifier to extend its operating cycle. During long-term operation, the lubrication channels of various components in the coal lock and slag lock actuators of the gasification furnace are prone to being blocked by impurities and coal powder, resulting in issues such as the cone valve not operating properly and high leakage rates. Following thorough discussions, the lubrication system of the coal lock and slag lock cone valves was modified by sealing off areas within these devices where impurities might enter and by applying lubricant regularly, which effectively extended their operational life. Third, optimize the gas-water and slag-water pipelines to effectively prevent leaks. Due to the presence of fine particles in the gas and water from the gasification furnace, as well as in the slag water, prolonged operation leads to wear of pipes and valves, increasing the risk of leaks. Through comprehensive analysis and inspection, some water pipeline fittings prone to leakage were upgraded, using better structural designs and wear-resistant materials, which significantly reduced the occurrence of leaks. Backup lines were added to the key valves and pipelines, ensuring the continuous and stable operation of the device. Fourth, implement technical upgrades to the stirrer in the gasification furnace to completely resolve the water leakage issue. Leakage from the agitator is the main factor restricting the long-term and high-load stable operation of the gasifier. To address this issue, extensive technical efforts were undertaken to modify the existing design patterns; comprehensive technical improvements were made in various aspects such as the packing method, the layout of cooling water pipes, the number of coal drop holes, the number of impeller blades, the material of the agitator, and the welding process, thereby eliminating water leakage from the agitator. Fifthly, original factory components such as the oxygen vaporization nozzles, slag discharge ports, and ring burners were replaced, achieving full localization. Meanwhile, the welding process for the ring burners was improved, which significantly extended their service life and saved substantial costs annually on spare parts procurement. Sixth, carry out process optimization and renovation of the gas and water systems to improve the quality of crude phenol products. After prolonged operation, the phenol-water feed used in the phenol-amine recovery unit contains high levels of oil and dust, which causes blockages in the heat exchangers and tray plates used for phenol-amine recovery, thereby severely affecting the quality of crude phenol. To address this issue, thorough research was conducted; as a result, an additional primary tar separator and a conical buffer tank were added to the gas-water treatment system. The primary tar separator was also modified, with the mixing mechanism being changed from being driven by dual-axis sprockets as originally designed to being driven by a single motor connected to a central shaft. This arrangement ensures the proper operation of the mixer, thereby guaranteeing the quality of the water discharged from the system ； Designing the bottom of the conical buffer tank in a 45° conical shape allows for the effective removal of oil residues accumulated in the tank, thereby ensuring the quality of the water used for high-pressure water spraying in the conversion device as well as for phenol-amine recovery. Following a series of technological upgrades, the fixed-bed gasification system at the gasification center has been fully upgraded, enabling long-term, high-load, high-efficiency, safe, and stable operation. To date, the continuous operating time for a single BGL vaporizer has reached 272 days, with an average operating cycle of over 166 days, which is at the international leading level ； The effective gas coal consumption is ≤700 kg/1000 Nm3, and the raw coal consumption is at a leading level in the industry. Furthermore, compared to the initial stage of operation, the operating cycle of the gasifier has been significantly extended; shutdowns have been reduced by about 10 times throughout the year, resulting in substantial savings on maintenance and start-up/shutdown costs ； The pulverization rate of lump coal decreased by 8%, resulting in very significant economic benefits. This is not only a fruitful outcome of Enerchemical Company’s efforts in technological innovation but also a clear indication of the significant improvement in its management level.