SU1490079A1 - Method of producing ammonia - Google Patents

Abstract

The invention relates to the production of ammonia and can be used in the chemical industry. The goal is to increase the productivity of the method. The ammonia released in the secondary condensation system is fed to the contact with the circulating gas before the primary separation stage and the product is withdrawn from the primary separation stage. The method allows to increase productivity and reduce energy and capital costs. 1 ill., 1 tab.

Description

The invention relates to the production of ammonia and can be used in the chemical industry.

The aim of the invention is to improve the performance of the method.

The drawing shows a circulation scheme of the ammonia synthesis cycle.

Circulating gas from column 1 of the synthesis enters the primary condensation system, which includes cooling ammonia with water and air to 20-40 ° C in condensation 2 and in two stages x 3 and 4 separations. Production ammonia is removed from the first separation stage 3 through line 5. Next, the circulating gas enters the contact with ammonia from the system 6 of secondary condensation 6, in which the gas is cooled by evaporating ammonia introduced through line 7 to -5-15 ° C. Cooled ammonia through line 8 can be directed to mixing with circulating In the process of contacting cold ammonia with the gas, it is cooled and additional condensation of ammonia from the gas mixture. Ammonia in line 10 is sent to mix with the injected ammonia in line 5 and in line 11 production ammonia is removed from the synthesis cycle. After the primary condensation system, the circulating gas is supplied to the compression by the circulating compressor 12, in front of which purge gas is discharged through line 13. Next, the circulating gas enters the secondary condensation system 8 and via line 14 is sent to the ammonia synthesis column 1.

Ammonia discharged from system 8 of secondary condensation through line 15 can be directed to contact with circulating gas before the primary condensation system to point 16, then all production ammonia is removed from the cycle after the first stage 9 of separation through line 5,

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In units 6 and 16 of contacting ammonia discharged through line 7 with circulating gas, injectors can be installed, which allows utilization of the energy of the ammonia pressure to compress the circulating gas.

An example. Aggregate of synthesis processing 157700 nitric mixture containing 1687 methane and 1687 nm / h of argon. After primary condensation, the temperature is circulating.

foot gas is reduced to AO C, after secondary condensation to -2 ° C. By

The known method implements an additional ammonia cycle in the amount of A, O m of ammonia per 1 ton of ammonia discharged from the primary condensation system, which makes it possible to reduce the temperature in the primary condensation system to AO C.

But to the proposed method, ammonia removed from the secondary condensation system with a temperature of -20 ° C is brought into contact with the gas that has passed through primary cooling to 4 () ° C and separation, while its temperature rises from -2 ° C to 36.5 ° C.

The table shows the data, characteristic of the proposed and well-known methods, subject to processing of 157700 nm / h of fresh gas, which corresponds to the productivity of the unit when working on the prototype, equal to 56.7 t / h of ammonia. The well-known is the best way to reduce the loss of a nitric mixture without secondary condensation. In the presence of secondary condensation, the loss of the nitric mixture increases. According to the proposed method, all the production: ammonia is recovered from the primary condensation system, therefore there is no point in the table to present data on the secondary condensation operation.

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The use of the known and proposed methods allows to increase the productivity of the unit operating according to the prototype scheme and reduce the volume of purge gases in comparable values. However, the proposed method is significantly simpler than the known method.

The proposed method of contacting the circulating gas after the synthesis column with ammcac, which has passed the secondary condensation system, makes it possible to increase the process efficiency and, in addition, to reduce energy and capital costs.

Claims (2)

1. A method of producing ammonia, including obtaining a nitrogen-hydrogen mixture from a hydrocarbon feedstock, maintaining ammonia synthesis, isolating it in a primary condensation system, containing condensation and separation stages, releasing ammonia in a secondary condensation system, returning a part of the circulating gas to the synthesis stage, and withdrawing the remaining parts of the cycle as a purge gas, characterized in that, in order to increase the productivity of the process, liquid ammonia released in the secondary condensation system is fed to the contacting circulation - tsionnm gas before the primary condensation step or before the primary separation stage and product withdrawal was carried out from the primary separation stage. 2. A method according to claim 1, characterized in that the contacting of the circulating gas with liquid ammonia is carried out upon injection. The volume of fresh gas containing 1.07% of CH and 0.3 Ar, nm / h Gas volume, solution, in ammonia after primary condensation, nm / h including: nitric acid mixtures inert gases Volume of gases, solution, in ammonia after secondary condensation, nm / h 0 15700 2710 1590 1123 No secondary condensation system 15700 2270 1330 943 including: nitric mixture inert gases Purging, nm / h including nitric mixture inert gases The total loss of the nitrogen-hydrogen mixture, nm Increase in unit capacity per t / h in% 6930 4900 2030 4900 6940 4870 216 4870 0.635 1.12 0.638 1.13  I  I V i.:.  I  I