Study of the effect of the temperature of caustic tower
operation on red oil formation in olefin units
| Mortaza Gholizadeh
| Mohsen Samudi
School of Material Science and
Engineering, University of Jinan, Jinan
250022, P. R. China
Faculty of Chemical and Petroleum
Engineering, University of Tabriz, Tabriz,
Tabriz Petrochemical Complex, Off Km 3
Bakeri Freeway, Kasaei Highway End,
Mortaza Gholizadeh, Faculty of Chemical
and Petroleum Engineering, University of
Tabriz, Tabriz, Iran.
Natural Science Fund of Shandong Prov-
ince, Grant/Award Number:
This study aims to investigate the effect of caustic tower operation temperature
on red oil formation and clogging of the tower. For this aim, the caustic tower
of Tabriz Petrochemical Plant was used. The operation temperature of the
tower was varied from 38 up to 50 °C, and the amount and composition of
the red oil formed were investigated. Our results indicate that the amount
and composition of the red oil formed inside the tower were different at varied
temperatures. At 42–45 °C, minimum amount of the red oil formed, whereas at
other temperatures, the products with 2 phases (oil phase on the top and aque-
ous phase in the bottom) were produced. The red oil formed is mainly alkanes,
alkenes, dienes, and also aldehydes. They are produced from the cracking of
naphtha, which some could undergo polymerisation reactions in the caustic
tower, resulting in the formation of red oil. This formation of the red oil could
decrease the efficiency of absorption column due to the problem of chocking.
In addition, the red oil will accumulate on internal surfaces of equipment
and the bottom of the column, leading to fouling and eventually plugging.
The analysis showed that the polymerisation reactions produce heavy alkanes,
aromatics, and cyclic compounds. Via optimisation of caustic tower operation
temperature, the red oil formation could be drastically decreased.
caustic tower, olefin, optimisation, red oil, temperature
1 | INTRODUCTION
Increasing demands for polymeric product from crude
petroleum have stimulated the development of petro-
chemical plants. Petrochemical plants are classified to
olefins or aromatics producers. In olefin‐based plants,
the majority of the olefins are produced through cracking
of naphtha or other products from petroleum refinery.
Olefins are the basis for producing of various polymers
including plastics, resins, fibers, elastomers, lubricants,
Cracking of naphtha could produce different
chemicals such as H
, and –RSH, along with ole-
Acid gases need to be removed from the cracking
unit products, either to meet environmental emission reg-
ulations or to protect the downstream catalysts.
One of the methods to remove the acid gases is the
using of caustic absorption tower. During the absorption
of acid gases in caustic tower, a significant fraction of
the gases such as H
S and CO
will be removed in the
forms of Na
S and other compounds.
Mainly, there are two mechanisms for the forma-
tion of polymers in caustic wash tower: radical poly-
merisation and aldol condensation.
dienes, and also aldehydes, products from the cracking
of naphtha, some have inherent tendency to undergo
polymerisation reactions in caustic tower, resulting in
Received: 14 November 2017 Revised: 28 February 2018 Accepted: 7 March 2018
Asia‐Pac J Chem Eng. 2018;13:e2189.
© 2018 Curtin University and John Wiley & Sons, Ltd.wileyonlinelibrary.com/journal/apj 1of6