Catalysis 2022 issue

Study of CCRU first reformer reactor ∆P behaviour using multiple linear regression Determinants and explanatory variables affecting the behaviour of the first reformer reactor ∆P are identified, with the aimof controlling it and avoiding a shutdown

ALI AL SHEHHI ADNOC

I n this article, the significant increase in pressure drop across the first reactor in the catalytic reforming unit is studied using lin- ear regression modelling. Initially, 10 variables were identified: the total lift gas flow, secondary lift gas, lift “A” partial ∆P, first heater inlet temperature, reactor inlet tempera- ture, research octane number (RON) control temperature, unit feed, recy - cle gas flow, hydrogen to hydrocar - bon ratio, and hydrogen flow to first reactor for elutriation. These varia- bles were considered as explanatory variables for the response variable, which is the first reactor ∆P in this case. The variables were accepted or rejected based on the P-value with

Both Microsoft Excel and Minitab Statistical software were used in the study. Study background A continuous catalytic reforming unit (CCRU) processes heavy naph - tha to convert the naphthenes and normal paraffins into principally aromatic and iso-paraffins with higher octane number. The CCRU also produces hydrogen and light hydrocarbons. The main purpose is to obtain high octane number refor- mate for the motor gasoline pool. This study was initiated because the first reactor in the CCRU was facing a rapid increase in ∆P, up to ~1 kg/cm 2 against normally <0.2 kg/

RON summary at the refinery

Year

Research Octane Number

2011-2015

93 95 98

2015- July 2020

July 2020-October 2020

Table 1

a significance screening indicator of α=0.05. Finally, six variables were shortlisted for further study, one of which is the RON control tempera- ture. This was identified as the main explanatory variable behind the repaid increase in the first reactor ∆P as the unit severity increased dur - ing the period from July to October 2020 in addition to catalyst attrition.

Recycle hydrogen

H for NHDT

O gas

Reactor 2

Reactor 3

Reactor 1

H for GOHDT

For LPG recovery

Overhead condenser

H for FG/are

Charge heater-3

Charge heater-1

Charge heater-2

H to catalyst lifting & seal

Overhead receiver

Reformer absorber

To are

Packinox

Recycle hydrogen compressor

Stabiliser

Feed / Rx E. Packinox exch

Cooler

LPG to vapouriser

Feed

Separator

Cooler

Fin fan cooler

Hydrogen multi-stage compressor

to LPG sweetening unit

Chlorine guard

Suction KOD

Reformate to storage

Figure 1 Catalytic reforming unit process flow diagram

Catalysis 2022 29