Crystallization Behavior of Ammonium Chloride in High-Pressure Heat Exchanger of Hydrotreating Unit

Jianwen Zhang, Fan Zhang, Yan Li, Yahui Zhao and Gang Sheng

Mathematical Problems in Engineering, 2021, vol. 2021, 1-15

Abstract:

In view of the corrosion failure of a high-pressure heat exchanger in a diesel hydrogenation unit, the formation mechanism of ammonium chloride in a multiphase flow system is investigated in this article. Numerical simulation is carried out by user defined function (UDF) on the process of adding source of mass transfer in computational fluid dynamics (CFD) solvers. The distribution characteristics of ammonium chloride are illustrated by the parameters including crystallization temperature of ammonium chloride, volume fraction of ammonium chloride, and mass transfer rates of NH 3 and HCl, and the causes of corrosion cracking in the U-shaped bend of the heat exchanger are discussed. The results show that there is a great risk of ammonium chloride deposition in the heat exchanger from 4.5 m away from the outlet of the second pass. The crystallization area in the tube gradually expands from the wall to the center along the flow direction, and the crystallization rate is higher near the tube wall. The field sampling test results show that the corrosion cracking is hydrogen-induced cracking, which is due to the existence of large amount of hydrogen, high impacting force, excessive flow rate, and the risk of ammonium chloride particle erosion at the U-bend. In order to alleviate the corrosion of ammonium chloride deposition, some improvement measures are put forward, such as raising the inlet temperature of the tube side to 215 °C and increasing the water injection by 30%, which play an important role in decreasing the formation of ammonium chloride in the heat exchange system.

Date: 2021
References: Add references at CitEc
Citations:

Downloads: (external link)
http://downloads.hindawi.com/journals/MPE/2021/5056631.pdf (application/pdf)
http://downloads.hindawi.com/journals/MPE/2021/5056631.xml (text/xml)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:hin:jnlmpe:5056631

DOI: 10.1155/2021/5056631

Access Statistics for this article

More articles in Mathematical Problems in Engineering from Hindawi
Bibliographic data for series maintained by Mohamed Abdelhakeem ().