PTQ Q3 2024 Issue

2.0

Corrosion potential [V (SHE)] Repassivation potential [V (SHE)]

1.0

0.0

-1.0

-2.0

Temperature (˚C)

Figure 7 HEX 06 outlet to HEX 07 outlet – localised corrosion – Hastelloy C-276

an issue when processing renewable feedstocks in this configuration. • Reactors cycle length reduction and performance decrease: Catalyst deactivation and reactor pressure drops increase mainly due to phospholipids and other reactive species: ■ Implementing new reactor internals such as filtering trays, pretreatments, and inert grading or filtering trays can mitigate these issues. Phospholipids, which are reactive species containing phosphorus, act as catalyst deactivators. ■ Utilising lipid storage tank blanketing to limit peroxide value, employing different catalysts, and installing an arse- nic trap can help address peroxide compounds. Peroxide compounds are highly reactive and can lead to gum formation (peroxide hydrogenation, diolefins, and ole - fins hydrogenation, and hydro-dematillisation reactions). Olefinic and di-olefinic compounds, indicated by a high bromine/iodine index/MAV, suggest radicalic polymerisation of unsaturated compounds. The Bromine Number measures the olefinicity of a stream (grams of bromine that will react

with 100 grams of the sample). A rule of thumb is that the olefin fraction of the sample is half the Bromine Number. A Bromine Number exceeding 15g/100g is considered critical. Metals such as Ca, P, and Mg increase catalyst deacti- vation and catalyse the dehydrogenation of hydrocarbon molecules, leading to coke formation at high temperatures and pressures. These metals typically exist as phosphates of calcium and magnesium. • REAC – Fouling, uniform corrosion and pitting corro- sion risk by chlorides in the effluent reactor side: ■ Install n.2 new wash water injection system, upstream HEX 07 and HEX 08 to be intermittent if the co-processing is intermittent and the percentage of biogenic feedstock processed is < 5 wt%. Alternatively, they should be oper - ated continuously with an injection rate of 25 and 15 t/h, respectively. ■ Upgrade the MoC of HEX 07/08/09/10 tube bundles and connecting piping from CS to Hastelloy C-276 if the percentage of co-processed biofeedstock is >10 wt%. ■ Upgrade the size of HEX 07 to HEX 08 common line from 10in to 14in.

Corrosion risk assessment – 10% POME co-processing

Stream

Uniform corrosion Uniform corrosion

Uniform corrosion

Pitting corrosion

Pitting corrosion Pitting corrosion

CS (mm/y)

SS316 L (mm/y)

C-276 (mm/y) 1.1-1.2 * 10 - ³

CS (A/m²)

SS316L (A/m²)

C-276 (A/m²)

HEX 06 out – HEX 07 out HEX 07 out – HEX 08 out HEX 08 out – HEX 10 out HEX 10 out – AC 01 out HP separator LP separator Diesel stripper

0.45-1

0.019-0.022

0.2

rp > E corr

E rp > E corr

0.52-2.21

0.035-0.055

9.9 * 10 - ⁴ 1.1 * 10 - ³

0.016-0.21

0.02 – 0.15

rp > E corr

0.28-1.5

0.024-0.04

8.3 * 10 - ⁴ 1.0 * 10 - ³

0.01-0.02

rp > E corr

E rp > E corr

0.27-0.67

1.0 * 10 -3 -0.02

4.5 * 10 - ⁴ 8.7 * 10 - ³

0.01

rp > E corr

E rp > E corr

0.23 0.62

2.25 * 10 - ³ 7.38 * 10 - ³ 0.01-0.18

3.59 * 10 - ⁴ 3.19 * 10 - ⁴

E E E

rp > E corr rp > E corr rp > E corr

E rp > E corr E rp > E corr E rp > E corr

1-1.6

3.0 * 10 - 4 3.7 * 10 - ⁴

OVHD

Table 2

PTQ Q3 2024