First Integrated Hydrocracker-DHT unit in ME –

Its Design, Challenges and Benefits

Talal Al-Rawahi, Orpic

Keshav Nagarhalli, Orpic

Alok Srivastava, ART

Agenda

Introduction to Orpic

Introduction to ART

Integrated Hydrocracker (HCR) - Diesel Hydrotreater (DHT) Unit

in Orpic

HCR in Refinery flow scheme

Orpic HCR configuration

Integrated HCR-DHT advantages

Commissioning challenges

Test run and current performance

Conclusion

Who are we

Orpic is Oman’s national refining and petrochemicals company owned by the

Government of Oman.

Orpic’s Business Model

Orpic Journey

Advanced Refining Technologies (ART)

Who we are

Grace-Chevron joint venture leveraging CLG’s hydrocracking catalyst technology and McDermott's process technology

What we have

A complete portfolio of hydroprocessing catalysts

Substantial resources dedicated to customer support and product development

What we do

Improve the operation and profitability of our customers in the petroleum refining industry

How we do it

Exceptional design of catalyst systems

Fully integrated technical support teams

Why we do it

To provide a single point of contact for

refiners hydroprocessing catalyst needs

Integrated HCR-DHT unit in Orpic

Objective: The objective of the unit is to produce Jet and Ultra Low Sulfur Gasoil product (ULSD) and send Unconverted oil to RFCC

Licensor: Chevron Lummus Global ( CLG)

Unit Configuration:

Hydrocracker ( Isocracking ) unit consists of a two stage hydrocracker (HCR)

integrated with a diesel hydrotreater (DHT).

Total Capacity : 4.055 MMTPA (87,771 BPSD) with turndown at 50% feed rate

HCR I Stage : 2.077 MMTPA (43,043 BPSD)

HCR II Stage : 0.54 MMTPA (11,952 BPSD)

DHT : 1.978 MMTPA ( 44,728 BPSD)

Hydrocracker Conversion – 60 wt.% ( 57 Vol.%), Cycle length – 2 years

The two-stage HCR and DHT share common recycle gas, fractionation, light ends

recovery, LPG treating, fuel gas treating, and make-up hydrogen sections

Integrated HCR-DHT unit in Orpic,

contd.

Unit Feeds:

Hydrocracker section : Designed to process Vacuum gas oil (VGO) from VDU and Heavy Coker Gas Oil (HCGO) from Coker Unit. Straight Run To Cracked Feed Ratio : 75 wt.% : 25 wt.%

Hydrotreating section : Designed to process defined blend of Light Coker Gas Oil (LCGO) from Coker Unit, Heavy Aromatics feed from AOL, Coker Naphtha and Straight run gas oil (SRGO) from CDU. Straight run feed to Cracked Feed Ratio is 51 wt.% : 49 wt.%

Products:

The following major products are produced from the Integrated Hydrocracker Unit:

• Treated Fuel Gas to Header

• Liquefied Petroleum Gas (LPG) to storage

• Light Naphtha to Isom unit

• Heavy Naphtha to AOL

• Jet A-1 to storage

• Diesel with Euro V Specification (<10ppm S) to storage

• Unconverted Oil to RFCC (CCR <0.1Wt%)

YIELDS SOR EOR

Product WT% WT%

H2S 1.72 1.72

NH3 0.14 0.14

C1-C4 1.1 1.39

Light Naphtha 3.45 3.79

Heavy Naphtha 12.42 13.23

Jet A-1 27.15 27.06

Diesel 35.38 34.04

UCO 20.49 20.49

HCR in Refinery Flow Scheme

C4 to LPG Merox

C4

Petroleum

CokeVDU

RFCC

HCR

LPGH N to AOL

JET A1

Diesel

CDU

CDU2

Crude Oil

AR from MAF

BBUBitumen

DCU

HCR Bottom

VGO

VR

CN

LCGO

HCGO

AR

AR

ISOM

L Naphtha

Isomerate

L Naphtha from AOL

Raffinate from AOL

Propylene to OPP

Legend

Existing Units New Units

HA

Integrated HCR-DHT unit in Orpic

Integrated HCR-DHT unit - advantages

Integrating hydroprocessing units saves up to 30% capital cost. Savings are mainly from :

Common Recycle gas and Make Up compressors

Common Fractionation , l ight ends recovery, LPG treating, fuel gas treating systems

Coker Naphtha also processed in DHT section thereby avoiding a Coker Naphtha Hydrotreater

DHT section operates at higher pressures resulting in superior product

quality and longer cycle life

Savings in maintenance and man power costs

Commissioning challenges

Pre-commissioning activities started from July 2017

❖ Catalyst loading done for all three reactors by July

❖ Catalyst wetting and sulphiding done in August

❖ Commissioning of the unit with feed cut-in was done by end August

❖ Performance test run done in December

Challenges faced during commissioning are :

Frequent choking of Amine Filters

Leakage of FT Flanges in HP Loop

High vibrations in Make up gas compressors

LPG Off-spec on Copper corrosion

HP Steam header contamination

Foundation Field Bus issues

Commissioning challenges -

Frequent choking of Amine Filters

Problem

As per design, HCR unit is provided with feed filters in Lean Amine supply line to the unit to remove particulates up to 10 microns. HCR is major consumer of Amine with design flow of 170 m3/h (~65% of total amine circulation)

Post catalyst sulphiding, when HP Amine absorber was taken on line, the amine filters started choking frequently (pressure drop reached limit within 15 mins) making the operation unsustainable and lead to high H2S in Recycle Gas ( up to 2%)

High TSS (above 400 ppm) loading observed in Lean Amine system

Resolution

Rx temperatures were lowered and unit put on long loop circulation @ 50% feed rate and reactor temperatures maintained around 250 oC with 10 m3/h fresh feed to DHT to keep up to 500 ppm H2S in recycle gas system.

Third party temporary filtration skid was installed in the unit with disposable filters. It took more than a week to clean up entire system and establish Amine circulation back to normal values

One of the observation was that during pre-commissioning, each unit amine degreasing was done separately and system did not see full design flowrate.

Commissioning challenges -

Leakages of FT Flanges in HP Loop

Twice unit was shutdown due to leakages resulting in more than 2 weeks downtime

On 25th August , leakage from FT-049 ( II stage treat gas flow orifice ) observed.

Leak was from the spare instrument tapping plug (seal weld).V isual inspection revealed a crack on 1/4th perimeter of the seal welding circumference at the plug.

PMI indicated that the plugs were of Carbon Steel, while they must have been of 1-1/4Cr – 1/2Mo as per Piping Specification

Other Low alloy steel orifice flanges FT’s checked and at total 18 places such anomalies were found. All CS plugs replaced with low alloy F-11 material plugs.

On 16th September, leakage observed on FT-027 ( I stage treat gas flow orifice flange spare plug)

Visual Inspection indicated a crack ¼” above seal welding circumference at the Upper North-East plug

Orifice Flanges related to High Pressure Systems were inspected and those with any issues replaced ( total 59 Plugs replaced)

Issues identified were : Plugs threads not fully engaged, poor quality welding, Small diameter plugs and short length plugs used etc.

Commissioning challenges -

LPG Off-spec on Copper corrosion

Problem

LPG product was going off-spec

on Copper Corrosion since unit commissioning

Unit configuration includes Product

Stripper followed by Fractionator. Feed to Light End Recovery (LER)

section is from Product stripper

overhead and also fractionator overhead.

Troubleshooting actions included : Increasing Temperature profile,

Pressure reduction and purging's

from related columns and frequent caustic replenishments

Resolution

Sampling survey of relevant streams indicated higher H2S slippage from Product Stripper to Fractionator (design < 1ppm slippage). Fractionator overhead naphtha showed high H2S (50-350 ppm).

Licensor was contacted and in house analysis and operating data was shared.

Licensor suggested modification to route fractionator overhead naphtha to Sponge Oil Absorber in LER section to strip off H2S. Earlier this naphtha was fed directly to Debutanizer. Modification was carried out and LPG product came On-Spec after the new line-up was commissioned.

Commissioning challenges -

High vibrations in Make up gas compressors

Problem

High Vibrations observed on

Motor side and on Compressor

Frame

High vibrations are resulting in

foundation getting damaged, bolt loosening, damage to

compressor internals l ike stuffing

box packing and piston ring seals. Instrument tapping also

getting affected. Also crack

found on suction snubber of one compressor.

Resolution

Specialist company hired to study the natural frequencies along with OEM

Counter weights are added as suggested by experts with some respite.

At lower compressor loadings, higher vibrations are observed. So we are forced to run machine at higher loads (less efficient operation). Loading has increased over time to keep vibrations within limit.

Root cause for high vibration is stil l under investigation by vendor.

Commissioning challenges -

HP Steam header contamination

Problem

HP steam header got contaminated asVacuum Distillation (VDU) heateremergency steam to heater pass flowcheck valve was passing and AtmosphericResidue (AR) backed through steam trap tohot clean condensate system. SteamSystem got contaminated with oil for morethan a week before getting noticed.

Boiler feed water contamination withhydrocarbon created excessive foaming inthe steam drum of steam generation systemand led high conductivity water droplets tosteam system passing through demister.Steam turbine blades were fouled due tosteamquality.

Impact was first seen on WGC of DelayedCoker unit and later on RGC inHydrocracker unit. Fouling of HP steamheader led to full opening of governor valveof turbines.

Unit shutdown taken. RGC Turbine openedand fouling observed on rotor blades.

Resolution

Sample result indicated chlorides, piping rustetc. Improper HP Steam Line blowing towardsprocess side was identified as one of the rootcauses.

Turbine blades cleaned by hydroblasting andturbines restarted

Entire steam and condensate systems waspurged to remove trace contaminants andsystem re-established.

Commissioning challenges -

Foundation Field Bus issues

Problem

Control Valves in HCR were opening suddenly and going to their fail safe positions in random fashion.

This happened with approximately 10 control valves including reactor quench control valves

Alert panel engineers took quick action thereby avoiding any upsets and mishaps

Resolution

Problem was identified as

communication failure between DCS and FF Field

instruments

Field barriers firmware changed/upgraded for

120 segments which

appeared suspect

No further problem is

reported since the change.

Test run and current performance

Performance guarantee run and current performance

Unit Performance Guarantee Test Run (PGTR) was done in Dec’17 for a period

of 10 – 12 days after resolving all commissioning issues, in presence of both

CLG and ART personnel

Unit met all the guarantees, viz feed rate, conversion, products yields &

qualities, hydrogen and util ities consumption

Feed properties being monitored closely. Reactor top bed pressure drops are

under control ( less than 1 bar)

Orpic and ART jointly estimating conversion from I and II stage of HCR on weekly basis

Conclusion

Conclusion

Unit is running normal since commissioning

After nearly one year of run length , Catalyst Average Temperatures (CAT) in

reactors are stil l below Start Of Run (SOR)

Unit has been tested on 100% load with higher conversion (65 Vol%) and also

tested at 65% load and 95 Vol% Conversion.

Based on current performance, it will be exceeding 2 years guaranteed

catalyst life. Aim is to extend catalyst life to 4 years to meet turnaround target

with one pit stop for reactor top bed catalyst skimming.

THANKS