A Paper Presented at the AIChE San Francisco Meeting November 6, 2013
A CASE STUDY OF PROCESS IMPROVEMENT IN A PETROCHEMICAL
PLANT
CHIKE OKECHUKWU and BAL SHRIVASTAVA Indorama Eleme Petrochemicals Ltd (IEPL)
Port Harcourt, Nigeria [email protected]
EMMANUEL A. DADA ChemProcessTechnologies (CPT), LLC
League City, TX 77573 [email protected]
OUTLINE
• Introduction Indorama Eleme Petrochemical Ltd (IEPL) integrated program and master plan to modernize its plants and facilities. • Scope Of Indorama Eleme Petrochemical Complex
Olefins Plant Polyethylene Plant Polypropylene Plant Butene-1 Plant
• Process Improvements
• Conclusion
INTRODUCTION
Process Plant Improvement is Aimed at Achieving: • Plant’s Efficiency and Availability • Optimizing Raw Material Consumption and Energy • Capacity Utilization • Safety and Environment Rating • Competitiveness and Profitability
Scope Of Indorama Eleme Petrochemical Complex
• The main objective of Indorama Eleme Petrochemical Ltd (IEPL) is to satisfy Nigeria’s domestic needs of polyolefin resins with a growth rate put at 7-8% per annum.
• The major feedstock to the complex is Natural Gas Liquid (NGL) supplied from AGIP-NNPC-CONOCO PHILLIPS joint venture NGL Plant located at Obrikon about 83km away.
The Petrochemical Complex is made up of the following Process Plants: • OLEFINS • POLYETHYLENE • POLYPROPYLENE • BUTENE-1 PLANT.
OLEFINS PLANT
Olefins Plant Employs the milli-second Furnace Technology from KBR (Kellog Brown and Root) by cracking Natural Gas Liquid (NGL) as the main Feedstock. Products are: • Ethylene 260 KTA • Propylene 126KTA • VC5+(Virgin C5+) • CC5+(Cracked C5+) • Methane Rich Fuel gas • Hydrogen • Heavy/Light oil
POLYETHYLENE (PE) PLANT
PE Plant employs the Solution Phase Polymerization of Ethylene in the Presence of Cyclohexane Solvent using Catalyst and co-Catalyst to produce varieties of polyethylene products. Co-polymerization Requires the addition of Butene-1 The Plant is designed to produce 270 KTA polyethylene resins. • HDPE • LLDPE
POLYPROPYLENE (PP) PLANT
PP Plant employs the Basell Technology to produce PP resins. This technology permits the slurry based polymerization of propylene in the presence of catalyst and co-catalysts. The Plant is designed to produce 80 KTA PP Homo and co polymer products.
BUTENE-1 (But-1) PLANT
• But-1 Plant employs AXENS technology of dimerization of Ethylene using LC catalyst (C32H68O8)Ti and TEAL co-catalyst Al(C2H5)3. Amine is used to terminate the reaction.
• The Plant is designed to produce 22 KTA Butene-1
IEPL COMPLEX LAYOUT
The overall configuration of the IEPL complex shows the integration of the four process plants and the interdependency in the design philosophy to achieve operational efficiency, effective energy and capacity utilization.
PROCESS IMPROVEMENTS
Process Improvements were aimed at integrating the process plants, highlighting their interdependency in achieving operational efficiency and capacity utilization. In our discussion we shall follow this order: • Explanation of the Problem
• Consequences of the Problem • Action Taken to Resolve the Problem
• Performance after Implementation of Actions
Process Improvements In Olefins Plant
• CO2 breakthrough during furnace switch over and during Plant start-up after routine maintenance jobs.
• Failure/ineffective injection of DMDS (Di-methyl disulphide) to the furnace feed
• High CO2 in the NGL feed stock in excess of 250 wt ppm. • Inability to confirm DMDS inventory. • Acetylene in Ethylene (>1.0 mol ppm) and CO2 in C2H4 (>5 mol
ppm) are poisonous to the downstream PE/PP/Butene-1 plants catalysts.
• High CO2 in ethylene product leads to higher chemical/catalyst consumption in downstream plants.
• Loss of reaction in the PE /PP/Butene-1 plants • Products downgrading • Flaring of Products with resultant losses and environmental
challenges.
OLF-01: Resolution of Frequent CO2 Break-Throughs
OLF-01: Resolution of Frequent CO2 Break-Throughs (Contd.)
• DMDS transfer pump to DMDS tank provided thus eliminating the incidence of water ingress due to unloading defects.
• Provision has been made for higher nozzle bore size for DMDS injection lines to each of the furnaces in addition to the DMDS injections in the common header.
• SOP for furnace start-up and DMDS dosing reviewed and socialized.
• DMDS LT indication has been provided in DCS to monitor level drop.
• DMDS Splash has never occurred since 2010 • Red Hot Tubes (RHT) appearance due to high CO2 variations
reduced to Nil. • Furnaces now have high run lengths up to 30 days as against
maximum average of 10.
OLF-02: Fuel Gas (FG) System Stabilization
• Olefins Plant operations has been hampered in the past by FG failures from AGIP or fluctuations in pressure.
• Shutdowns due to external FG failure lead to quick shutdowns of furnaces without decoking and saw tube failures and plugging of several radiant tubes.
• Modifications via tie-in from NGL feed fractionator overhead to Boiler LP FG line has enabled “NGL dumping” which is utilized to fire the Boiler furnaces during FG upsets.
• Another modification employed the use of tie-in from Ethane recycle to the HP FG drum which is used to fire the Furnace in the event of FG outage from AGIP.
• Furnace Availability and Operational Stability Achieved.
OLF-03: Process Gas Compressor (K-1)/Ethylene Refrigerant Compressor(K-3)/Propylene Refrigerant Compressor(K-2) Lube Oil Pump Change Over From Steam to Motor Driven.
• Trips of K-1/K-2/K-3 compressors and consequently Olefins Plant total shutdown were frequent and rampant due to fluctuations of the steam header pressure tied to the LO (Lube Oil) turbines of the compressors.
• LO turbines were outdated and difficult to maintain. • Olefins’ Plant unavailability and shutdown of other downstream
plants were also common occurrences. • The lube oil circulation for the compressors were changed from
Turbine to Motor driven due to the advantage of stable power supply.
• The modification has led to improvement in the compressors reliability and availability.
Process Improvements in Polyethylene (PE) Plant
Fouling of the 1st stage condensers in the distillation unit caused a lot of plant offsets. • The fouling was as a result of polymer entrainment along with
LPS-1 solvent vapor stream • The condensers were subjected to frequent cleaning and
subsequently plant unavailability. • The Plant throughput was also seriously constrained. • Higher quantity of Cyclohexane was flared due to high outlet
temperatures (>80*C) .
PE-01 Installation of LPS-1 (Low Pressure Separator), K.O. (Knock Out) Pots in Extrusion Trains#1/2 LPS-1 Overhead Lines
PE-01 Installation of LPS-1 (Low Pressure Separator), K.O. (Knock Out) Pots in Extrusion Trains#1/2 LPS-1 Overhead Lines ( Contd)
• K.O. pots were installed in the LPS-1 overhead lines to the distillation units.
• The LPS-1 K.O. pots had cyclohexane spray nozzles installed inside to knock out trace polymers that may entrain with overhead vapors.
• Improvement in PE plant throughput • Improvement in Equipment Reliability • Minimal plant shutdowns for first stage condensers cleaning.
PE-02 Provision of Chilling System for Improved Bed Absorption Capacity and Availability of SH Purifier
• Insufficient cooling of the Recycled Cyclohexane (SH) from the HB Column Reflux Drum was a major constraint for improved bed absorption.
• Original cooling system was not sufficient for removal of impurities.
• Removal of impurities like ketones & moisture were major problems.
• The purifier changeover was not smooth & efficient. • Excess catalyst/co-catalyst consumption manifested. • Chiller Installation was effected.
• Purifier changeover is now smooth & efficient. • Reduced catalyst & co-catalyst consumption.
PE-03: Installation of LP Diluent Surge Tank for Smooth Supply of LP Diluent for Catalyst & Co-Catalyst Injection in Reactor
• Failure of the LP diluent pumps was frequent due to fluctuations in recycled cyclohexane pressure.
• Original design which provided for direct SH supply from purifier outlet and feeding to the catalyst/Co-catalyst pumps through a master pressure controller was not adequate.
• Loss of Reaction. • Downgrading of Products due to color problems. • Installation of LP diluent Surge Tank for smooth supply of LP
Diluent for the catalysts/co-catalyst pumps.
• Minimal Catalyst/Co-Catalyst Consumption. • Loss of Reaction Reduced.
Process Improvement In Polypropylene (PP) Plant
• Production of a pumpable slurry from the polymerization catalyst powder result in the choking of the upstream and downstream overflow lines of the In-Line Mixer pre-polymerization process.
• Frequent choking of these lines had led to frequent plant shutdowns.
• Manual Flushing done with high pressure oil resulting in high risk of oil splash.
• Line flushing provides for a DCS solenoid operated hand valves
(HVs) on the oil flushing line.
• Improved Safety, Operations and Equipment Reliability
PP-01: Incorporation of Oil Flushing System for In-line Mixers (ILMs) from Control Room DCS
CONCLUSION • The Federal government of Nigeria quest to reform the oil and gas
sector through privatization has recorded tremendous endorsement by the success story of Indorama Eleme Petrochemical Ltd (IEPL).
• The former ailing petrochemical plant after the privatization process has recorded improved capacity utilization, enhanced productivity and safety and environmental rating.
• IEPL has won awards in areas of Product Quality, Occupational Health and Safety, Environment and Corporate Social Responsibility
• IEPL has increased the revenue base of the government and driven
the non-oil export base contribution to Nigeria’s gross domestic product (GDP) to the highest level in recent times.
