Minimizing the Impact of Red Tide Environmental
Events on Safety Critical Equipment of a Reverse
Osmosis Desalination Plant
A.F Al Hinai*, B.M Alkali B.M**and M. El Sharif***
Department of Mechanical, Electrical and Environmental Engineering, School of Engineering &
Built Environment, Glasgow Caledonian University, G4 0BA
Red Tide in North Oman
Overview of Presentation
•Introduction
•Presentation Objectives
•Importance of Seawater desalination
•Frequent occurrences of red tide events
•Case Study-RO Plant in Sultanate of Oman
•RCM-Decision Making Grid
•Research Methodology
•Competing Risk Modeling
•Conclusions
Introduction
• Desalination is the process of removing Salt from seawater (or brackish
water) to make it fit for human consumption.
• The relation between poor maintenance strategies and inefficient Energy
Recovery and huge power consumption.
• Membranes Scaling and fouling.
• Red Tide has significant impacts on equipments reliability deterioration.
• Excessive usage of chemicals during environmental events
• Off-spects products
Petrochemical Plants and Reverse Osmosis Outfall
System
To Main Channel
(RO Plant Database)
The impact of Red Tide Event on Seawater Quality
(RO Plant Database)
Desalination Plant Challenges- Poor Maintenance
then Leaking, Fouling and Scaling
Beach Wells – Types
•Vertical / Slant Wells
•Collector Wells
•Modified Wells (Galleries,
micro tunneling, well points)
Mathematical Maintenance Modelling
Repairable Systems
• Repairable system is the system which is after failing to
perform one or more of its functions satisfactorily, can be
restored to fully satisfactory performance by any method other
than replacement of the entire system.(Henry, 2011Maintenance of Repairable Systems)
• Non-repairable systems are the systems that are upon failure of
one their components the failed component is permanently
taken away from service and replaced with a new one. They
are more expensive to repair it than to replace it (Steven et al.,
2008) .
RCM- RO Plant Critical Equipment's Identification
Approximate Frequency of
failures from 2006-2010
Downtime estimation per failure
Downtime in days
Cartridges Filter
89
An average of 2 hours per failure
7.42
RO Membrane
37
An average of 3 hours per failure
4.625
High Pressure Pump
31
An average of 6 hours per failure
7.75
Membrane O-ring
29
An average of 3 hours per failure
3.625
Effluent Pump
28
An average of 6 hours per failure
7
SBS Dosing Pump
22
An average of 6 hours per failure
5.5
Clarifier Sludge Pump
21
An average of 6 hours per failure
5.25
Backwash Waste Transfer Pump
19
An average of 6 hours per failure
4.75
Service Water Pump
9
An average of 6 hours per failure
2.25
Acid Dosing Pump
3
An average of 6 hours per failure
0.75
Critical Equipment Name
Time of failure(dates)
1/05/2010
1/01/2010
1/09/2009
1/05/2009
1/01/2009
1/09/2008
1/05/2008
1/01/2008
1/09/2007
1/05/2007
1/01/2007
1/09/2006
Inter-arrival times(days)
Data Collection and Analysis
Scatterplot of Inter-arrival times vs T ime of failure
35
30
25
20
15
10
5
0
Research Methodology(Continued)
Oman RO Plant Inter-Arrival Times for month of
2008 red tide
Scatterplot of Inter-arrival times vs Time of failure
9
Inter-arrival times(days)
8
7
6
5
4
3
2
1
0
1/10/2008
1/11/2008
1/12/2008
Time of failure(dates)
1/01/2009
1/02/2009
Research Methodology(Continued)
RO plant downtimes in November, 2008 Red Tide
400
Scatterplot of Downtime vs T ime of failure
Downtime (days)
300
200
100
0
1/10/2008
1/11/2008
1/12/2008
Time of failure (dates)
1/01/2009
1/02/2009
Critical Equipment Failure in a Complex RO
Desalination Plant
•
•
•
•
•
•
•
•
•
•
Cartridges Filter
RO Membrane
High Pressure Pump
Membrane O-ring
Effluent Pump
SBS Dosing Pump
Clarifier Sludge Pump
Backwash Waste Transfer Pump
Service Water Pump
Acid Dosing Pump
Research Methodologies
•
•
•
•
RCM-Decision Making Grid
Failure Mode and Effect Analysis(FMEA)
Preventive Maintenance Optimization
Mathematical Maintenance Modeling
RCM-Decision Making Grid
Sr. No
Downtime
Frequency
1
Low
Low
Failure Equipment Name
Decision taken
OTF
Acid Dosing pump
2
Low
Medium
Nil
FTM
3
Low
High
Nil
SLU
4
Medium
Low
Service Water pump
FTM
5
Medium
Medium
Nil
FTM
6
Medium
High
Nil
FTM
7
High
Low
Nil
CBM
8
High
Medium
End Connector, Effluent Pump, SBS
Dosing pump, Clarified Sludge
Pump, Backwash Waste Transfer
Pump,
FTM
9
High
High
High Pressure Pump, Cartridge Filter,
RO membrane
DOM
FMEA-Information Worksheets
Equipment Function
Description
Membrane
Functional Failure
1.
A.
Sea Water Blocking
Filtration
B.
Deterioration of Membrane
life Cycle(Off spec. Product
water)
Failure Mode
Failure
Effect
1-Fouling: Seclusion of organic suspended
particles such as Colloids (org.,inorg.)
Metal oxides(Fe2+, Mn4)
Bacteria, microorganisms
Degradation 4
of RO
membrane's
performance
Crystal
4
Precipitation
2-Scaling:Seclusion of suspended inorganic
particles, such as
Calcium Carbonate(CaCO3)
Calcium Sulphate(CaSO4)
Barium Sulphate(BaSO4)
Calcium Fluoride(CaF2)
Magnesium Hydroxide(MgCO3)
Silica(SiO2)
1-Permeate back pressure(Ref.19)
Frequency Severit Detecti RP
of
y
on
N
Occurrence
Rate
9
9
324
9
9
324
Membrane
damage
1
9
9
81
C. Feed water leak into the
1-Excessive Pressure on the membrane surface
permeate
D. Deterioration of Membrane 1-Transition Metals Presences in the Feed water
life Cycle(Off spec. Product
water)
Membrane
damage
Oxidation
1
9
9
81
1
9
9
81
E. Deterioration of Membrane 1-Hydrocarbons Presence in the Feed water
life Cycle(Off spec. Product
water)
Membrane
1
Contaminatio
n
9
9
81
Analysis using RCMcost Availability Workbench
variables considered are:
•Cost of Repair
•Safety Criticality
•Operation Criticality
•Environmental criticality
•Safety target
•Operation target
•Environmental target
PM Optimization for Fouling through simulation
1.7E+05
Cost
0.002
Saf ety Criticali
1.65E+05
Operational
Criticality
0.0018
Environmental
Criticality
Saf ety target
1.6E+05
0.0016
1.55E+05
0.0014
1.5E+05
0.0012
1.45E+05
0.001
1.4E+05
0.0008
1.35E+05
0.0006
1.3E+05
0.0004
1.25E+05
0.0002
1.2E+05
0
0
3000
6000
9000
12000
15000
18000
21000
24000
Interval
Re comme ndation: Run to failure
27000
30000
Environmental
target
Criticality
Cost
Operational
target
PM Optimization for Scaling through simulation
5.5E+05
Cost
0.0014
Saf ety Criticality
Operational
Criticality
5E+05
Environmental
Criticality
0.0012
Saf ety target
4.5E+05
Operational
target
Environmental
target
0.001
4E+05
3.5E+05
Criticality
Cost
0.0008
3E+05
0.0006
2.5E+05
2E+05
0.0004
1.5E+05
0.0002
1E+05
50000
0
0
3000
6000
9000
12000
15000
18000
21000
24000
Interval
Re comme ndation: PM at 1460
27000
30000
Competing Risk Model Framework
Competing risk model can be expressed as;
Competing Risk Model (continued)
Published Work:
Conference Papers/Submitted Abstracts
• Hinai A.F, Alkali B.M, Zhou.C and Mohammad Farrag. (2014). Competing Risk Models for
modeling a Complex Multi Stage Flash Seawater Desalination Plant subject to Degradation,
8th IMA International Conference on Modelling in Industrial Maintenance and Reliability
(MIMAR)-10 - 12 July 2014 St Catherine’s, Oxford, UK.
• Hinai A.F, Alkali B.M, Zhou C & Farrag M.(2013). Assessing the reliability of seawater
desalination plant energy recovery through maintenance modelling. 3rd International
Conference on Harnessing Technology - 2nd - 3rd December 2013.
• Hinai A. F and Alkali B. M. (2013). A Competing Risks Model for assessing the impact of
red tide on Refineries and Petrochemical Industries desalination plant equipments. Quality
and Reliability Engineering International.
• Hinai A. F and Alkali B. M. (2012). Stochastic point process models for assessing red tide
impacts on desalination plant equipment.3rd Student Conference on Operational Research
(SCOR 2012-20-22 APRIL 2012), Nottingham, UK.
• Hinai A. F and Alkali B. M. (2012). Reliability and maintenance of Complex plant. OR52
Annual Conference (7-9 September, 2012) in Edinbrough University.
• Ramachandran. K. P and Hinai A. F. (2010). Decision Mapping and Optimal Inspection
Models for Plant Maintenance: Some Case Studies, IMETI 2011 international conference –
July 19th - July 22nd, 2011 – Orlando, Florida, USA.
Conclusions
• Competing risk is best fit for the desalination plant collected
data
• Preventive Maintenance Scheduling through simulation(Monte
Carlo Simulation) is useful tool in obtaining an effective
maintenance strategy for the plant critical equipments.
• Environmental events such as (Red tide) are considered as a
serious event impacting the reverse osmosis plant and the
petrochemical industries. A strong correlation between the
reverse osmosis plant equipments degradation and the
occurrences of red tide events.
Thank You