Purge gas ammonia recycling method and ammonia recycler

Abstract

The invention relates to a purge gas ammonia recycling method and an ammonia recycler. According to the method and the ammonia recycler, an ammonia recycler is arranged between an ammonia synthesis procedure and an ammonia liquid storage tank; the ammonia recycler is multistage; in the ammonia synthesis procedure, the low temperature ammonia liquid discharged by an ammonia separator after the ammonia is cooled is singly conveyed to an upper ammonia liquid inlet pipe of the ammonia recycler, the purge gas flashed and desorbed from the ammonia liquid in the ammonia recycler is mixed with the purge gas flowing bottom up from the ammonia liquid storage tank, and the purge gas with reduced ammonia content is recycled in a constant pressure ammonia recycling tower or a non-power ammonia recycling tower through a wire mesh demister and a purge gas outlet on the upper part of the ammonia recycler; the low temperature ammonia liquid with flashed and desorbed purge gas is discharged from the ammonia recycler via a low temperature ammonia liquid outlet of the ammonia recycler and is conveyed to a low temperature cold exchanger and the ammonia liquid storage tank via an adjusting valve or directly conveyed to the ammonia liquid storage tank; and a purge gas inlet on the lower part of the ammonia recycler is connected with the purge gas outlet of the ammonia liquid storage tank. The purge gas ammonia recycling method and the ammonia recycler in the invention have the advantages of consuming no power and recycling refrigeration capacity of the ammonia liquid.

Description

technical field [0001] The invention relates to a synthetic ammonia chemical process and supporting equipment. That is, a part of ammonia in the purge gas of liquid ammonia in the ammonia synthesis process is recovered, and a purge gas ammonia recovery method and an ammonia recovery device that can recover the cooling capacity of liquid ammonia. Background technique [0002] In the existing technology, the ammonia synthesis process of large, medium and small synthetic ammonia plants in my country is equipped with secondary ammonia separation or tertiary ammonia separation. No matter the secondary or tertiary ammonia separation process, there is an ammonia separator after ammonia cooling , In addition to the ammonia separator after ammonia cooling for the secondary ammonia separation, there is also an ammonia separator after the cold exchange or ammonia separator after the water cooler, and there are three kinds of ammonia separators for the tertiary ammonia separation. Most ...

AI Technical Summary

Problems solved by technology

[0007] 1. The temperature of the low-temperature liquid ammonia separated from the ammonia separator after ammonia cooling in the ammonia synthesis process is generally -10°C to 0°C, accounting for about 50% of the total ammonia production in the ammonia synthesis process. At present, these low-temperature liquid ammonia and cold exchange The cold liquid ammonia separated from the rear ammonia separator and the room temperature liquid ammonia separated from the rear ammonia separator of the water cooler are combined and then go to the liquid ammonia storage tank together. Different recycling and utilization of the cooling capacity of these liquid ammonia;

[0008] 2. There is no flash evaporation and desorption equipment before the liquid ammonia storage tank, and there is no flash evaporation and desorption of liquid ammonia at a relatively low temperature before the liquid ammonia enters the liquid ammonia storage tank, and the vast majority of the liquid ammonia is pre-separated. Part of the relaxation gas with low ammonia content, but some of the relaxation gas that has been flashed and desorbed in the liquid ammonia and the liquid ammonia are all passed through the liquid ammonia storage tank, and the relaxation gas is bubbled out in the "hot" liquid ammonia , not only greatly increases the ammonia concentration in the purge gas, but also increases the amount of purge gas passing through the liquid ammonia storage tank, so that the total amount of ammonia in the purge gas to the isobaric ammonia recovery tower increases;

[0009] 3. The cooling capacity of low-temperature liquid ammonia and cold liquid ammonia is not used to wash and recover the ammonia in the purge gas with high ammonia content by flash evaporation and desorption from liquid ammonia storage tanks, normal temperature liquid ammonia and cold liquid ammonia. ;

[0010] 4. After the gas dissolved in low-temperature liquid ammonia and cold liquid ammonia is flashed, desorbed, and separated, the cooling capacity of low-temperature liquid ammonia and cold liquid ammonia is still a lot, and there is no excavation, recycling, and utilization of these cooling capacities at present;

[0011] 5. Using the ammonia cooling method to recover and reduce the ammonia in the relaxation gas will consume power, increase the load of the ammonia compressor, increase power consumption, and increase equipment;

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