best practices in a refinery wide implementation of apc€¦ · best practices in a refinery wide...
TRANSCRIPT
ERTC 22nd Annual Meeting November 15th, 2017 – Athens
Eleni Zouridaki: [email protected]
Maurizio Rossi: [email protected]
Best Practices in a Refinery
wide implementation of APC
1
Outline
• Introduction to Motor Oil Hellas and Alpha Process Control
• Refinery and APC: the program
• Lesson learnt: APC focus on constraints and targets
• From APC to Optimizer
• Benefit of APC maintenance program
2
• MOH was founded in 1970 by Vardinoyiannis Group.
• Located near the city of Corinth in Greece
• One of the largest and most flexible Refineries in the Eastern Mediterranean
In full operation since 1972 and gradually expanded to an industrial complex of over 30 licensed processes; the major unit blocks are as follows:
2 CDU, 2 VDU, FCC, CCR, LUBES PLANT, MHC, HPU, 3 HDT, VISBREAKER, MTBE, HF ALKYLATION, TIP, 4 SRU, DIMERSOL
Nominal Capacity of 173,000 barrels/day
About Motor Oil Hellas
3
About Alpha Process Control
© 2012 Alpha Process Control. Confidential Information.
Technology Independent to maximize flexibility of implementation
Engineering Consulting Company specialised in Process Performance Optimization
Experts in the implementation of APC strategies to the Refining and Petrochemical Industry
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APC Background
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Motor Oil started collaborating with Alpha Process Control in 2013 in a refinery-wide program as part of its Operational Excellence Initiative using Advanced Process Control.
2013
2014
2015
2016
2017
CDU#1 CDU#2
FCC VDU
HDS HDT MHC H2NET
CCR
LUBE ALKY
ISOM Optim. Study
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APCs Structure (#MVs/#CVs)
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CDUs
FCC VDU
HDS HDT
MHC
H2
CCR
LUBE
ALKY
ISOM
Largest number of CVs and MVs; some of them not used (not real targets for the unit)
Smaller number of CVs and MVs; more focused on real constraints
Design reviewed in the Alpha Maintenance Program
Commissioning to be finalized
Small APC, real constraint focus
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Poll Questions
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Have APC applications have you implemented on your process? How many large
APC (#MVs > 15, #CVs > 30)?
Do you have small applications (#MVs
< 5, #CVs < 8)?
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APC focus on Constraints • As shown above, some of the applications have a large number of
CVs and MVs, making them complex to handle and less user-
friendly to operators
• During the APC implementation program a set of critical constraint
for the units were defined and the APC actions were focused on
these constraints
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The Message
Catch the most impacting benefits from the unit with the most simple APC structure
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CV
s
Dew Dist
Merox Max. Feed
DSL 85%
Other Capacity
Constraints
DSL 95%
Analysis of constraints; among top-ten: • MEROX max. feed • DEW Point Distance • Diesel 85%/ 95%
Few Examples
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H2
CCR
ISOM
CDUs
CDUs On CDUs: focus on the most impacting constraints
Designed as target-focus APC fetching the main
constraints in the unit in a simple APC structure
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CDUs: Minimizing the Naphtha
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Refinery in Diesel Production asset: Naphtha minimization is a target
• Dew Point distance • Jet Flash Point • Naphtha 90% - 95%
Real Constraint of the unit
Normally not used. CVs in OFF
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0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 7000
DewPointDistance
Samples
Baseline WithAPCONDew Point Rebuilt in APC equation and compared to rigorous model in different operating conditions
With APC Naphtha is minimized against the dew-point distance
Main Target of Naphtha Minimization for 100% of the time
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CDUs - Diesel Optimization
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• DSL 85%, 95%, Cloud Point
• LGO-DSL Mix 85%, 95% • LGO 85%, 95%, Cloud Point
Based on the refinery asset the Diesel target is given on DLS 85% or DSL 95%. The real target should be in the Diesel Pool (85%, 95% or Cloud Point)
APC mainly working on DSL constraints
Limit often adapted for the Diesel Pool
specification
Normally not used. CVs in OFF
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CCR – RON Maximisation
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ST.DEV Reduction of Duty
ON OFF REDUCT
DUTY 1 0.527 0.840 -37.28%
DUTY 2 0.580 1.055 -45.05%
DUTY 3 0.734 3.023 -75.73%
DUTY 4 0.932 1.380 -32.49%
• 4 reactors • To maximize RON the constraint is the Max Duty for each furnace • Simplified APC with only 4 MVs (COTs) and 4 CVs (Duties)
Reduced APC scope
Simplified Structure – more user-friendly for operators
The larger benefit of the unit (RON Max.) has been achieved without inferential or analyzer. No RON prediction
High Service Factor, always pushing to the proper constraint: Duty on High limit for each furnace
Utilization of the controller almost 100%, without any moves from the control-men
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ISOM – Stabilizer
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07/08/17 09/08/17 11/08/17 13/08/17 15/08/17 17/08/17 19/08/17 21/08/17
RVPBias
RVP(Inferential,LAB)
HighLim LowLim ReadValue SSValue RVPInfer LAB BIAS
Focus on a single column: target is to maximize the RVP in bottom to promote LPG to Isomerate
Reduced APC scope
Simplified Structure
Benefit Achieved
Bo
tto
m S
team
R
VP
(in
fere
nti
al, L
AB
)
Second target: reduction of iC5 in overhead Section to maximize RON in Isomerate
Influenced by the upstream section - deisopentanizer column. In stabilizer only influenced by overhead pressure – increased to the high limit of MV
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H2 Network
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MV1
MV2
• Complex Scheme.
• Selected 2 MVs only that will provide the most of benefits by reducing the H2 loss to fuel gas network
0
100
200
300
400
500
600
700
31-Dec-13 1-Mar-14 30-Apr-14 29-Jun-14 28-Aug-14 27-Oct-14 26-Dec-14kg/h
APC OFF APC ON
H2 Loss to FG Net
DSL 85%/95% Limit often adapted for the Diesel
Pool specification
Kero and Jet Maximised on CDUs; however the
real constraints are in the MEROX unit
APC on CDUs/VDU APC on MHC APC on HDS/HDT
Optimizing the diesel against DSL 85% or DSL 95%. Local optimum.
Optimizing the Kero against Freezing. Local optimum: mixed with Kero
from CDUs.
Optimizing the Sulphur for each
unit. LCO maximization
requires coordination.
Perspective Change
Refinery Optimizer
The implementation of APC on different unit created the need of a refinery-wide optimization
APC Coordination with Refinery-Wide optimization
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Maintenance Program Outline • APC Maintenance allows keeping their performances to top level.
• From the lesson learnt in the APC implementation program, the maintenance report should focus on – Real constraints of the unit
– Detailed analysis of process constraints
– Real indicators of performances
• Maintenance reports automatically generated are not focused on real process constraints; they often are limited to statistical analysis of CVs/MVs: useful analysis but not complete.
• Maintenance report aim is to detect any sub-optimal application and suggest the actions to return to top performances
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Summary • MOH, as part of their Operational Excellence Initiative, has implemented
several APC on different units
• APC applications have different targets and constraints; one of the lessons
learnt is to focus on the real constraints of the units to reach the largest
possible benefits with the most simple APC structure
• The APC implementation changed the focus of the refinery from single-unit
optimization to refinery-wide optimization (next phase)
• Alpha and MOH have in place an APC maintenance program to keep all
applications to top performances and to maintain the focus on the real
process constraints and targets of the units
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