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Novel approach of Continuous Catalytic Reforming Unit Capacity augmentation Mr. T Sudhakar Indian Oil Corporation Limited, India Deputy Manager
Novel approach of
Continuous Catalytic Reforming Unit
Capacity augmentation
Mr. T Sudhakar
Indian Oil Corporation Limited, India Deputy Manager
Description: CCRU revamp for capacity augmentation is conventionally performed by addition of new reactor and furnace along with
associated modifications. This type of capacity augmentation revamp not only requires high number of shutdown days, but calls for high
Capex and Opex. This paper talks about novel approach implemented at Mathura Refinery, Indian Oil Corporation limited, India to
augment the CCRU capacity significantly without any major modification in CCRU.
Case Study: Crude processing capacity at Mathura Refinery necessitated capacity augmentation of CCRU by at least 20 %. Feedstock to
CCRU contains about 4.0 vol % of benzene and its precursors, as a result approx 12 vol % of product reformate was sacrificed as light
reformate draw in order to maintain benzene content in heavy reformate stream to the desired level of < 1.8 vol % to meet MS
specifications.
A study was done for CCRU capacity augmentation by (a) changing the design of CCRU reactor internals -replacement of single
concentric outer Johnson-screen by multiple scallop design (b) low cost revamp of Naphtha splitter unit (NSU) to improve CCRU feed
quality. Replacement of reactors internals design, allowed loading of 22 % additional catalyst with increase in T’put by corresponding
amount.
Low cost NSU revamp envisaged addition of preheat exchanger, overhead condensers and product coolers along with modification of
column internals. Post NSU revamp, the benzene and its precursors in CCRU feed was found to be in the range of 0.2-0.3 vol % against
the original level of 4.0 vol %. With this CCRU feedstock, the benzene in reformate stream is maintained well within the desired limit of <
1.8 Vol %, resulting in stoppage of reformer splitter unit (RSU).
Conclusion: The innovative approach of low cost CCRU capacity augmentation through changing the design of the reactor internals,
along with naphtha splitter unit revamp and stoppage of RSU in an integrated manner resulted in 20 % increase in CCRU capacity in
addition to 12 % reformate yield improvement due to stoppage of RSU. Thus not only the combined reformate yield has improved by 32
% but there has been significant energy reduction due to stoppage of RSU and light reformate processing in ISOM unit.
Abstract: Novel approach of Continuous Catalytic Reforming Unit (CCRU)
capacity augmentation
Introduction
Surge in MS demand necessitates capacity augmentation of existing
catalytic reforming unit (CRU)
Refiners normally use high octane heavy reformate stream ex CRU
as main MS blend stock to meet octane requirement in final MS pool
Reformate yield improvement become the key driver in maximizing
octane barrels
Low benzene reformate became critical to meet current Euro IV MS
specifications
CCRU at Mathura Refinery
Design capacity : 466 TMTPA
Design reformate RON : 98
Feedstock : 90-1500c naphtha cut
Design feedstock,N+2A : 66-96 vol %
Catalyst inventory : 40 MT of CR401 catalyst
(33 MT in reactors and 7 MT in regenerator)
Process Licensor : M/s Axens
Necessity for CCRU capacity augmentation at Mathura Refinery, IOCL, India
Naphtha dispatched as-such as low margin product due to CCRU capacity limitation
Change in refinery crude basket makes CCRU feed poorer. N+2A became 52 vol% against design of 66-96 vol %
Poor feedstock affected reformate RON (95-96 against design 98)
High content of benzene & its precursors (MCP and CH ) in CCRU feed led to reformate rich in benzene (4 vol%)
High benzene reformate resulted in loss of 12 vol % of reformate yield (as light reformate) to meet MS
specifications
Situation affected octane barrels and necessitated CCRU capacity augmentation
by at least 20 %
Conventional CCRU Capacity Augmentation
Conventional way of CCRU capacity augmentation envisages addition
of new reactor and furnace along with associated modifications
Requires high number of shutdown days for implementation
High Capex and Opex
Novel approach of CCRU Capacity Augmentation
Significant CCRU capacity augmentation without any major modification in
CCRU
Low cost in nature
Significant energy saving
Approach adopted
(a) loading of more catalyst in existing reactors by changing reactor internals
design
(b) improving CCRU feed quality by revamping NSU for reformate yield
improvement
Study and Analysis
Process study by licensor indicated significant additional catalyst loading
possible by changing design of the reactor internals
Replacement of reactors concentric outer Johnson screen by scallop design
envisage 22 % more catalyst loading in existing reactors
Correlative 22 % increase in T’put possible on account of catalyst activity
due to additional catalyst loading
Scallop design internals Concentric design Internals
Concentric vs Scallop design internals
Change in reactor catalyst inventory
Concentric outer grid vs Scallops internals of reactor
15R1 reactor 15R2 reactor 15R3 reactor
Attribute Concentric
Design
Scallop
Design
Concentric
Design
Scallop
Design
Concentric
Design
Scallop
Design
Catalyst inventory, MT 4.9 5.54 9.8 11.73 17.3 22.37
Δ M Catalyst - +14% - +20% - +24%
No. of scallop elements - 20 - 26 - 29
V gas in outer grid (m/s) 13.2 14.2 14.7 21.2 11.9 23.3
Δ (ΔP Catalyst Bed) - +4% - +6% - +7%
Salient advantages of scallop design
Increases catalyst loading in existing reactors
Better catalyst activity on account of reduction of WHSV
Low cost and easy in installation
Good mechanical resistance
Only minor increase in catalytic bed pressure drop
Minimum catalyst loss in case of mechanical failure
Impact on ΔWAIT at Iso-RON
80
90
100
110
120
5 10 15 20
RO
N
ΔWAIT
Concentric design
Scallop design
Severity Gain : 5 deg c
0
0.5
1
1.5
2
2.5
3
516 518 520 522
ΔR
ON
WAIT
Concentric design
Scallop design
RON Gain : 0.9
Impact on ΔRON on Iso-WAIT
Performance improvement in CCRU by Scallop Installation
Catalyst inventory in reactor system increased by 22%
Combined catalyst inventory in all reactors increased from 33 to 40.8 MT
At Iso-RON, reduction of WHSV results in decrease of WAIT by 5
C
At Iso-WAIT, 0.9 RON increase on account additional catalyst
Post reactor internals modification, CCRU being operated at 20 % more
than its earlier operating capacity
Reformate Yield improvement by Benzene precursor
management
In-house simulation study indicated, Bz & its precursors can be
reduced to < 1.0 vol % in CCRU feed by improving distillation in NSU
Low cost Naphtha splitter revamp was adopted for CCRU feed
quality improvement along with capacity augmentation
NSU revamp entailed additional preheat exchangers, overhead
condensers, product coolers and column internals modification
Reformate Yield improvement by Benzene precursor
management
Post NSU revamp, benzene & its precursors in CCRU feed restricted to <1.0
% against original 4.0 vol %
Improved CCRU feed stock restricted Benzene in reformate stream to desired
limit of <1.8 vol %
Reformate directly blended with Isomerate and De-sulphurised FCC gasoline to
meet final MS specifications
As Bz in reformate is controlled, light reformate draw was stopped (12 % earlier)
resulting in reformate yield increment by same extent
Stoppage of reformer splitter unit (RSU) offloaded ISOM unit capacity resulted
in significant energy reduction
Low cost NSU revamp for reformate yield maximization
Attributes Before Revamp After Revamp
NSU Unit T’put, MT/hr 144 180
Preheat, deg c 95 145
ΔH,( Pre-heaters), MKcal/hr - + 6.1
ΔH,( Overhead Condenser), MKcal/hr - -5.22
ΔH,( Product Cooler), MKcal/hr - -1.42
CCRU Feed, (Bz, MCP and CH) Vol % 4.0 <1.0
Benefits
CCRU reactors internals design change & low cost NSU revamp was executed in
Aug-10
Scallops being in segments were found to be easy in installation and the job was
completed in 17 engineering days
About 20 % CCRU capacity augmentation on account of additional catalyst loading
About 12 % reformate yield improvement on account of CCRU feed quality
improvement.
Combined reformate yield improvement of 32 %
Energy saving of about 1200 SRFT/annum on account of stoppage of RSU & light
reformate processing in ISOM unit
T Sudhakar is working as Deputy Manager at Mathura Refinery, Indian oil Corporation
Limited, India and is primarily responsible for rendering technical services for Continuous
catalytic Reforming unit and Crude & Vacuum distillation units. He has 9 years of varied
experience in process monitoring, simulations and operations. He holds Bachelor degree
in Chemical Engg. from Shri Venkateswara college of Engg, Tamil Nadu, India.
Email : [email protected]
Phone : 0091-565-2417318
T Sudhakar
Indian Oil Corporation Limited, India Deputy Manager
