Identifying the operational characteristics of an ammonia synthesis column, taking into account changes in the operating parameters of the process plant
DOI:
https://doi.org/10.15587/1729-4061.2026.359439Keywords:
combined mathematical model, ammonia synthesis column, transport delay, stability margin, catalyst degradation, steady-state errorAbstract
This study explores the technological process of ammonia synthesis in a synthesis column as a complex multi-tonnage chemical and technological facility with a transport delay and variable state parameters. The task addressed relates to the lack of quantitative assessment of the impact of catalyst degradation on the dynamic characteristics of the facility, in particular on the transport delay and the stability margin, which complicates the determination of the limits of effective equipment operation and timely adoption of technological decisions.
As a result of analysis, it was established that a decrease in the synthesis gas flow rate by 10% leads to an increase in the transport delay time from 61 s to 67 s and a decrease in the stability margin in terms of modulus from 15.7 dB to 15.0 dB. It is shown that restoring the stability margin to the base level is possible by reducing the gain factor by 8%, which, in turn, is accompanied by an increase in the steady-state error to 8.39%, that is, a deterioration in the control accuracy and deviation of technological parameters from the set values.
The results are based on the use of the stability margin in terms of the modulus as an integral indicator sensitive to changes in the parameters of the object's state, which makes it possible to quantitatively link the degradation of the catalyst with the dynamic characteristics of the control system. The established patterns are explained by the fact that an increase in the transport delay causes an additional phase shift in the system and reduces the stability margin, while a decrease in the gain factor increases stability, but leads to an increase in the steady-state error, forming a compromise between stability and accuracy.
The practical value of the results is the possibility of their use for assessing the technical condition of the ammonia synthesis column, determining the limit modes of its operation, and substantiating the time of catalyst replacement. The application of the findings is appropriate under conditions of quasi-stationarity of the process, limited disturbances. and the use of linearized mathematical models of the object
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Copyright (c) 2026 Petro Yeliseyev, Maryna Loriia, Olexii Tselishchev, Liudmyla Karpiuk, Oleksandr Duryshev, Yevgen Kobzarev
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