In the ammonia synthesis process you are using, where are the addition and venting points located?
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In the ammonia synthesis process you are using, where are the addition and venting points located?
Our plant’s ammonia synthesis process follows a post-tower configuration; fresh gas is introduced at the cold exchanger, that is, before the ammonia cooler, while vent gas is generally located after the ammonia separation unit.
In the company where I work, fresh gas is supplied to the cold exchanger; the advantage of this is that it makes full use of the cooling capacity, facilitates oil-water separation, and protects the synthesis catalyst.
Our plant supplies make-up gas at the ammonia cooling outlet, while the vent downstream of the tower is connected to the ammonia cooling inlet. Please check these two connections: 1. The location where the synthesis make-up gas is supplied; 2. The optimal location for the ammonia synthesis vent. This post was last edited by snowdfr on 2009-3-13 at 19:52.]
The fresh gas inlet points for the two systems in our plant are both located at the outlet of the ammonia cooler, where it merges with the liquid ammonia that has been cooled in the heat exchanger. And wash out trace amounts and oil and water from the fresh gas. To combine and protect the catalyst. The ammonia outlet is placed behind the tower to reduce waste of ammonia in the exhaust air.
We added ammonia cooling to both sets, and the air release was also done after the ammonia stage
Ammonia separation is carried out after the tower; the fresh gas enters the synthesis tower directly, while the vent gas is separated from ammonia. Here, the ammonia concentration is at its lowest and the inert gas content is at its highest, which allows for a reduction in the amount of gas that needs to be vented.
Your process is quite good; could you please explain it in detail?； Is there a purification device installed before the supplemental gas enters the synthesis tower in the synthesis system, and what technology is used?
The vent is located between the outlet of the cold exchanger and the ammonia cooler, while the make-up gas is situated between the outlet of the ammonia cooler and the ammonia separator.
Our fresh gas is supplied before the ammonia inlet cooler, and on the gas pipeline after liquid ammonia is separated in the heat exchanger; this helps to lower the temperature of the mixture, thereby allowing the oil and water present in the fresh gas to be removed. The downside is that the purity of the liquid ammonia is not very high. Back-pressure venting is located on the gas pipeline after the cold exchanger, where the proportion of inert gas is the highest. Especially when the hydrogen content in the system gas is low, the venting after the tower can be increased for adjustment.
Several of the newly designed sets are placed at the ammonia-cooled outlet, where the proportion of inert gas is the highest; of course, we also have our own unique supporting equipment and processes； Then, fresh gas is supplied before the cold exchanger inlet, thereby reducing the oil and water content in the fresh gas. In short, it’s different from traditional processes; both the procedures and the equipment have been innovated, and the results are excellent.
After water cooling but before ammonia cooling, our make-up gas is treated by using separated liquid ammonia to remove the toxic gases and oils present in it. The gas is released at the inlet of the circulation pump, where the loss of useful gas is minimal.
Fresh gas is introduced between the circulating gas and the ammonia cooler, with the aim of washing the fresh gas with ammonia to remove impurities and further purify the gas. From there, it goes to the synthesis tower after undergoing cold heat exchange. Venting is carried out between the cold exchanger outlet and the ammonia-cooled circulating gas, as the ammonia concentration is low here and methane levels are highest. The temperature also did not incur cooling load due to ammonia cooling.
Gas replenishment is at the ammonia section, while venting takes place after ammonia cooling
Why is the process I’m working with different from everyone else’s? Gas replenishment takes place at the outlet of the circulation machine, while air release occurs at the outlet of the heat exchanger!
Ammonia is separated behind the tower; fresh gas is introduced at the inlet of the compressor’s low-pressure cylinder, while the outlet of the compressor’s high-pressure cylinder is equipped with a return inlet as well as an anti-surge valve in the circulation section. There are 5 vent points: one in front of the compressor inlet (during synthesis); one 2 inches before the inlet to the circulation section (during startup and shutdown); another vent point before the inlet to the circulation section. Additionally, there is an inert gas vent control valve at each of the chiller outlet and the low-pressure ammonia separation tank.
Fresh ammonia is supplied at the inlet of the No. 2 ammonia cooler; after mixing with the circulating gas, it enters the ammonia cooler for cooling. Subsequently, it goes through an ammonia separation unit before entering the heat exchanger. Behind the tower is the 1# ammonia outlet; this is the location where inert gases accumulate in the recycle gas, and the synthesis purge gas is fed here to a membrane separation system for the separation and recovery of hydrogen. Reduce waste.
In the process I designed, venting takes place after #1 ammonia separator and before #1 ammonia cooler, while gas replenishment occurs after #1 ammonia cooler and before #2 ammonia cooler.
In summary, except for the 7th and 16th floors, most facilities use the ammonia separation process before the tower; it seems that very few manufacturers opt for the ammonia separation process after the tower. What are exactly the challenges associated with the technology that allows fresh gas to be processed without being purified by liquid ammonia?