What stainless steel is used for the internal components of the ammonia synthesis towers in various sister units?
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What type of stainless steel is used for the internal components of the ammonia synthesis towers in various sister companies? What temperature range for the synthesis catalyst has little impact on these internal components?
321 stainless steel internals for synthesis towers
The material of the internal components for medium-nitrogen ammonia synthesis is 304L
Our company also uses 304L material, at temperatures below 500 degrees. In fact, very high temperatures have little impact on the internal components; it’s mainly the catalyst that is affected. Our company has burned catalysts before.
I work in the design and manufacturing of internal components. In the past, carbon steel was used as material for ammonia-related internal components; later on, 321 (i.e., 1Cr18Ni9Ti) became commonly used, while currently 304 (i.e., 0Cr18Ni9) is more frequently utilized.
For the ammonia synthesis internals and the hydroxylamine synthesis internals in small nitrogen fertilizer plants, 1Cr18Ni9Ti was used in the past, but 0Cr18Ni9Ti is now used. The operating temperature is generally below 500°C; it can handle up to 650°C with no major issues, but the catalyst cannot withstand such temperatures. This post was last edited by Pastoral Poet on 2008-9-12 16:55]
We use 1Cr18Ni9Ti
Main material: 0Cr18Ni9
Our company has 9 towers, all of whose main structural materials are 304
We are currently using 0Cr18Ni9Ti. What was said on the 7th floor is correct – the internal components can withstand the effects of temperature, but the catalyst cannot.
At present, the only standards that can be referred to regarding the material specifications for the internal components of ammonia synthesis towers are \"Technical Requirements for Three-Tube-Type Internal Components of Ammonia Synthesis Towers\" (HG/T 2119-1991) and \"Technical Requirements for Single-Tube Co-current Type Internal Components of Ammonia Synthesis Towers\" (HG/T 2120-1991). The specifications regarding materials in these two standards are as follows: 1. The main material should be 0Cr18Ni11Ti or 0Cr19Ni9. 2. 1Cr18Ni9Ti can be used as a substitute material. The specification stipulates that the design temperature shall not exceed 550 degrees. In actual production, the maximum temperature of the catalyst is also required to not exceed 550 degrees. However, in emergency situations such as excessive temperature rise or high oxygen levels when the catalyst becomes deactivated, the temperature may rise above 600 degrees. As long as measures are taken to bring the temperature back below 500 degrees within a short period of time, this generally will not have a significant impact on the catalyst’s safe service life. Nevertheless, such situations must be strictly avoided, as they generally do not occur under normal conditions. Note: 0Cr19Ni9 corresponds to 304 ； 0Cr18Ni11Ti corresponds to 321. Both are austenitic stainless steels, and their recommended operating temperature range is -196 to 600°C. The maximum temperature can reach 650°C. However, considering the hydrogen embrittlement issue associated with syngas, the maximum operating temperature should remain below 550 degrees, and it is preferable to keep it at 500 degrees or less. With the advent of low-temperature, highly active catalysts, achieving this goal is no longer a problem. This post was last edited by zjyang168168 on 2009-2-3 10:55.]
Main material: 0Cr18Ni9