Thread Content
Catalyst replacement in the shift converters at the Gasification Plant of Shaanxi Chemical Industry Author/Source: Shaanxi Chemical Industry Date: June 9, 2022 Page views: 14 As the major maintenance work on System B for ammonia synthesis progresses, news came from the Gasification Plant of Shaanxi Chemical Industry that the catalyst replacement process has begun for both the 705B-1 Shift Converter and the 705B-2 Shift Converter. The 705 system in the purification section of the Gasification Plant’s subsidiary plant is the shift conversion section. Its main function is to facilitate a reaction between CO present in the gas generated by the gasification process and water vapor under the action of a catalyst, thereby producing the required CO2 and H2O. After the CO content is reduced to below 1.5%, the gas is washed with demineralized water (cold seal water) to remove trace amounts of ammonia; the resulting qualified process gas is then sent to the Rectisol section. The shift converter is the key equipment for reducing CO levels, while the catalyst is essential for the sulfur-tolerant shift reaction. Due to fluctuations in system temperature in the past, excessively high temperatures at the inlet of the shift converter would damage the physical and chemical properties of the catalyst, rendering it inactive. Conversely, temperatures that are too low fail to reach the activation threshold, thus preventing any catalytic action from occurring; in severe cases, this can even lead to excessive CO levels. Additionally, prolonged use of the catalyst is another factor contributing to its decreased activity. Therefore, the catalyst was replaced during this major maintenance to increase the reaction rate and enable smoother operation of the system. Under the dual pressure of a furnace temperature of 400°C and an ambient temperature of 35°C, the main control operators in the central control room and on-site personnel at the gasification plant worked closely together to gradually lower the furnace temperature. Subsequently, fluid drainage and purging were carried out. Meanwhile, on-site workers removed the insulation layer. In accordance with the pre-established plan, blind flanges were installed and removed from the shift converter, thereby isolating two converters from the system. Though this step seems simple, it actually involves a laborious process. Demonstrating a spirit of perseverance and hard work, the staff at Shaanxi Chemical Industry advanced the maintenance tasks efficiently and to the highest standards. The isolation of the blind flanges on the shift converters has now been completed, and the removal of flanges as well as the replacement of catalysts are proceeding in an orderly manner—laying a solid foundation for the stable operation of the entire system.