What is the service life of a section of furnace conversion catalyst?
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For ammonia synthesis plants using natural gas as a feedstock, the service life of the conversion catalyst in the first stage furnace is the shortest. It is understood that most of them need to be replaced after 2 to 3 years of use. Please share: how is your experience with it? How many years is the service life?
The two models of conversion catalyst used by our company are Z107 and Z111; the volume of catalyst loaded is 12 m3, and its service life is two years. In actual production, since carbon deposition easily occurs on the catalysts in certain sections of the furnace, if these catalysts are properly maintained, they can generally reach their designed service life; in some cases, they may even last longer than that.
Our factory uses those produced by Sichuan Chemical; they generally last for about 5 years before needing to be replaced. The equilibrium temperature difference meets the requirements well for the first two or three years after use; it is only gradually that an increase becomes noticeable later on, and this increase is not rapid.
The key factor affecting the service life of a furnace conversion catalyst is likely carbon deposition. Using naphtha as a raw material led to deactivation within just half a year due to carbon deposition. I won’t go into detail about the reasons for this carbon deposition, but the heat flux density in a certain section of the furnace is indeed a crucial factor that cannot be ignored.
Which company are you from? Z107 and Z111 are very old models of conversion catalysts; their activity and strength at low temperatures are much worse compared to modern catalysts. If it’s convenient, we can discuss this aspect further.
The lifespan of a conversion catalyst depends on the process used and the operating *practices of each plant. K-type plants, due to their high water-to-carbon ratio, are less prone to pulverization and have a longer lifespan, which can reach up to 6 years; whereas B-type plants, with their low water-to-carbon ratio, have a lifespan of no more than 3 years. The dual-stage conversion lifespan is 1-3 years, and the overall lifespan is generally short.
A conversion catalyst generally lasts for 2-3 years, with the following factors influencing its lifespan: 1. The quality of the gas fed into the unit. 2. The gas composition must meet the requirements. 3. The water-to-carbon ratio should be appropriate during operation. 4. The steam entering the process section must be clean. 5. The operating temperature should be stable. This post was last edited by *aoye613 on 2009-3-9 19:16]
The service life of the catalyst is closely related to the process conditions as well as the composition of the gas. When the gas has a favorable composition – with little ash, low condensate water, low sulfur content, and minimal fluctuations in process operations – the catalyst’s lifespan is correspondingly extended. On the contrary, poor gas composition will lead to a shortened lifespan of the catalyst. Only by strictly controlling these parameters can the service life of the catalyst be ensured!
We have two major maintenance cycles, about 4 years each
It can be used for 4 years. During normal operation, it is important to ensure stability; the water-to-carbon ratio should be controlled by interlocks, and changes to this ratio should not be made arbitrarily. In critical situations, reliance on humans is not sufficient – interlocks are what are needed. Note that the desulfurization in the previous system must ensure that the sulfur content remains below 0.1PPM to prevent catalyst poisoning. When jumping out of the vehicle normally, the system should release pressure at a controlled rate. Make sure that no section of the furnace operates above its temperature limit.
Our plant has been using it for three years. Last year, due to changes in the composition of natural gas, the sulfur content exceeded the allowable limits; this was not detected in time, resulting in catalyst poisoning. Later, by increasing the water-to-carbon ratio and operating at reduced load, we managed to keep things running for a while, and new catalysts were installed during the annual maintenance at the end of the year.