Thermal protective catalyst RK-11-3 is a high-temperature resistant thermal protective agent prepared by means of high temperature sintering method, including a small amount of nickel as active components and alumina as the carrier. The catalyst is used as a thermal protective agent in the top of the secondary reformer by matching with RK-11-4. The main performance of the catalyst is the adaptation to the specific operating environment and conditions in the top of the secondary reformer, and its resistance to high temperature and air impact is better.
1.Physical properties and chemical components
1) Composition: NiO, SiO2, Al2O3 and other oxides
Specification (outer diameter * inner diameter * length): φ25*17*10mm
3) Bulk density, 0.8-0.8 kg/L
4) Operating temperature: < 1400℃
5)eat-resisting performance: the catalyst will not melt into pieces while operating at 1450℃, and the catalyst has thermal shock resistance.
2.Requirements of thermal protection agent to raw materials and poisons
1)Sulfur is the main poison of the thermal protective agent, so that the content of sulfur within the raw material gas entered into the furnace shall be reduced as far as possible; generally, the content of sulfur shall be less than 0.5ppm, and the best content of sulfur shall be less than 0.2ppm.
2)Chlorine and other halogens also will poison the catalyst, and inhibit the recovery of activity of the catalyst, so that the content of chlorine in the raw material shall be reduced as far as possible.
3)Arsenic will deactivate the catalyst permanently, so the raw material gas shall not include arsenic.
4)Copper, lead and the like can also reduce the activity of protective agent, so the raw material gas shall not include these poisons.
5) The water vapor used shall not include these poisons and the chemical drugs used for the treatment of boiler feed water.
3.Storage and loading of thermal protection agent
1)The thermal protective agent packed in plastic bag well shall be placed in a moisture-proof and anti-pollution iron drum or hard plastic drum to prevent from damping, freezing and shaking at any time, and it shall be prevented from falling from the place of 0.5m and above. Moreover, the thermal protective agent shall be prevented from the pollution caused by sulfur or other soluble salts during the storing and transportation process.
2)The thermal protective agent shall be lifted into the furnace with a container, in which the operator can enter into the furnace, it is forbidden to walk and trample directly on the catalyst of the second section, and the catalyst shall be provided with a board. During the loading process, the catalyst shall be loaded evenly and loaded to the height expected. Moreover, the catalyst shall not be piled before leveling.
3) The loading amount of thermal protective agent is 20-30% of the catalyst generally.
4)If the thermal protective agent shall be removed, it shall be subject to passivation treatment together with the catalyst of the second section.
4.Notes in operation
1)Thermal protective catalyst RK-11-3 shall be subject to the temperature-rising reduction together with the primary and secondary reformers, and the operation procedures, methods, temperature-rising reduction condition, operation notes, starting and shutting down and exception handling shall be the same with that of reforming catalyst of the second section, and it has no special requirements. The starting, shutting down and operation conditions can be carried out according to the large ammonia plants of the United States and Japan as well as other ammonia plants with similar technical processes.
2)For the secondary reformer, the process air can be added when the temperature is more than 650℃, in which the excessive process gas into the furnace shall be controlled strictly.
3)RK-11-3 also cannot be subject to intense overtemperature accident, so the mixer of the secondary reformer shall be inspected regularly, and the small changes to the furnace temperature shall be noted carefully, and the local the overtemperature condition shall be judged by combining with the composition of reforming gas in the second section. In case of the overtemperature phenomenon, the various measures shall be taken until stopping for checking.