H make-up reduced purity - CO/CO & light ends built-up
Recycle gas
Recycled compressed gas
Gas compressor
Reactor e uent
03 out
01 out
02 out
Sweet gas
AA sour gas
Sep-1
Hex 01
Hex 02
Hex 03
Lean amine
S-2 S-3
Rich amine
04 out
05 out
06 out
Amine absorber
Intermittent wash water
Alkaline stress corrosion cracking
Hex 04
Hex 05
Hex 06
S-4
Flash tank
Continuous ww inj. mixer
Mix-3
AA rich amine
09 out ww
10 out
07 out
08 out
09 out
AC01 out
10 out
HP sep. sour gas
Diesel stripper condensate
ww
Hex 10
Intermittent ww inj. mixer
AC01
Hex 07
Hex 08
Hex 09
HP separator
Diesel stripper OVHDs
Light ends increase
Solid
CO 2 build-up
Continuous injection system
DS OVHD coolers
DS OVHD receiver
HP separator HC
LP separator
HP separator water
To diesel stripper
NH Cl corrosion & fouling risk
Tail gas
Diesel stripper
Pre-heat
DS water
HP separator water
LP separator HC
Wild naphtha
Diesel product
Stripping steam
Water to SWS
LP separator water
HP separator water to SWS
Increased water production
Lower density & increased cetane number
Figure 1 OLI Flowsheet ESP – 50% POME – ionic survey
load (such as organic and inorganic chlorides by means of a pretreatment system or a quality control system of the feedstock). Alternatively, two new intermittent wash water injec- tion facilities should be installed upstream of HEX 06 and HEX 07, providing that the co-processing is intermittently operated. The material of construction (MoC) for piping and tube bundles should be upgraded from carbon steel or stainless steel to a corrosion-resistant alloy (CRA) to with- stand chloride water corrosion during intermittent washing. Additionally, intermittent water injection should be as close to the continuous water injection point as possible to mini- mise the impacts of the intermittent washing procedure on unit operation. Furthermore, the issues of ASCC and CO₂ build-up in the amine absorber, as well as the increase
in light ends, continue to be a concern, necessitating an upgrade of the current metallurgy. General corrosion risk A corrosion risk assessment was conducted using OLI Studio’s proprietary Stream & Corrosion Analyser to eval- uate the suitability of MoC with the new configuration for the intermittent and continuous new wash water injection facilities to be installed upstream of HEX 06 and HEX 07. The Corrosion Analyser, a first principles corrosion pre - diction tool, was used to perform the corrosion analysis. It is used to predict the rate of general corrosion, the propensity of alloy to undergo localised corrosion (pitting), depletion profiles of heat-treated alloys, and thermodynamic stability of metals and alloys.
1.03
3.83
Corrosion rate (mm/yr) pH (Y2)
0.93
3.73
0.83
3.63
0.73
3.53
0.63
3.43
0.53
3.33
0.43
Temperature (˚C)
Figure 2 HEX 06 outlet to HEX 07 outlet – corrosion rate – carbon steel
42
PTQ Q3 2024
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