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Cooling Tower ExplosionVisakhapatnam, India, 2013
Richa Sarkar
MS, Safety Engineering
Mary Kay O’Connor Process Safety Center
Artie McFerrin Department of Chemical Engineering
Texas A&M University
Steering Committee Meeting January 19th, 2017
Case Study
1
About Myself
• Hometown - Bihar, India
• Bachelors in Chemical Engineering (2005-2009)
National Institute of Technology, Trichy, India
• Process Engineer (2009-2015)
Hindustan Petroleum Corp. Ltd., Visakh Refinery, India
• MS Safety Engineering
Texas A&M University, College Station, USA
2
Outline
• Background
• Incident Description
• Consequences
• Analysis
• Lessons Learned
• Acknowledgement
3
Hindustan Petroleum Corporation Ltd. (HPCL)
•Indian state-owned oil & natural gas company, HQ in Mumbai, India.
• A public sector undertaking of the Govt. of India.
• Formed in 1974 by combining Esso and Lube India
•Two refineries – Mumbai and Visakhapatnam
4
Visakh Refinery• Commissioned as Caltex
Oil Refining India in 1957
• Taken over by government of India and merged with HPCL in 1978
• Visakh Refinery Expansion Projects –
VREPI – 4.5 MMTPA (1985)
VREPII – 7.5 MMTPA (1999)
Effective April 2010 – 8.3 MMTPA
5
Cooling Towers
• The refinery has 3 cooling towers
• Each added during expansion projects
VREPI
VREPII
VRCFP (Visakh Refinery Clean Fuels Project)
• Each provided with 4 cells and induced draft operating mechanism
• 5th cell was to be added to VRCFP cooling tower – to meet the requirements of Diesel Hydrotreater (DHT) Block
6
Sequence of events
VRCFP cooling tower – all cells collapse
Interconnection schemes – to sustain operations
New (5th) cell construction complete
Explosion during commissioning of new cell
7
Cooling tower operation
• Heat rejection to atmosphere
• Inexpensive means for handling low grade heat
• Fills are provided to increase contact area
http://www.svlele.com/piping/cooling_water.htm
8
Cooling tower operation
Fig 2 - Closed loop cooling water system [1]
9
Incident Description
• VRCFP cooling tower commissioned in 2009-10
• All 4 cells collapsed within 2-3 years
• Internal investigation concluded – design issues, improper load distribution
• Design modifications carried out for flow redistribution to individual cells
• Re-construction work of collapsed cells – handled by Maintenance department
• Construction of new 5th cell – handled by Projects department
10
Incident Description
• To sustain operations and reduce flaring –
interconnection provided between old and VRCFP cooling tower return and supply headers
Make-up water quantity was increased
• Decided to take the 5th cell in service – while construction continued on remaining 4 cells
11
Incident Description
Fig 3- sketch of cooling water lines to VRCFP cooling tower [5]
12
Incident Description
• Construction work for 5th cell completed
• Jump over to take 5th cell online, executed in field on 23rd
August
• Decided to go ahead with commissioning at shift change-over time
• Explosion occurred at 1646 hrs on 23rd August 2013, when the isolation valve was opened to commission 5th cell
13
Incident Scene: Before
http://www.process-cooling.com/ext/resources/issues/April2015/Emerson/PC0415_Slideshow_Emerson_1.jpg?1435691229
14
Incident Scene: Damage
http://www.thehindu.com/news/national/andhra-pradesh/one-dead-39-injured-in-vizag-refinery-blast/article5052564.ece
15
Consequences:
• 28 fatalities – 1 employee + 27 contract workers
• Several others with burn injuries
• Further delay in commissioning and limited production
16
Analysis: What went wrong
• Accumulation of hydrocarbon in the jump-over line
• No sample analysis of line content prior to commissioning
• Hot-jobs continued in adjacent cells at the time of commissioning
• Failure to check HC leakage in to cooling water in connected process units
17
Analysis: Management decisions
• Failure to prevent commissioning activities, with plenty of jobs unfinished
HC/H2S detectors were not installed
Fan cabling was incomplete
Improper co-ordination between Operations, Maintenance and Project departments
• Decision to go ahead with commissioning at shift change-over time
• Failure to implement procedures – PSSR, pre-com audit
• Commissioning procedure not followed – 16 jobs were going on, with 9 permits for hot job
• Standard operating procedure was not available
18
Analysis: Technical deficiencies
• Jump-over connection was at elevated location –resulting in accumulation of light hydrocarbons
• Significant distance between the isolation valve and the location where tie-in was made
19
Lessons Learned: Procedural
• Hot works and commissioning activity should not be allowed simultaneously
• PSSR should be done prior to commissioning new facility
• Check points of pre-commissioning audits and internal audits should be completed
• Minimum number of operating crew and nobody should be present at work site
• Provision of HC and other detectors as applicable should be ensured
• Hazard Identification and Risk Assessment should be ensured prior to commissioning of any new system
• Lack of operating procedure
20
Lessons Learned: Technical
• Always check and follow industrial standards
• Wherever possible avoid creation of dead-zones
• Provide high point vents, low point drains and appropriate sample points
• Ensure flow pattern within the line when providing take-off
21
Acknowledgement:
• Dr. M. Sam Mannan
• Dr. Guanlan Liu
• Pritishma Lakhe
• Ankita Taneja
• Valerie Green
• Alanna Scheinerman
• Members of MKOPSC
• Members of SC
22
References:
1. Lj. Matijasevic, A. V., and I. Dejanovic. (2014). Analysis of Cooling water systems in a Petroleum Refinery. Chemical and Biochemical Engineering Quaterly, 8.
2. Analysis of Incidents reported to PNGRB from July, 2013 to December, 2014. (2015). Retrieved 1/10/2017, from Petroleum & Natural Gas Regulatory Board http://pngrb.gov.in/Notices.html
3. http://www.oisd.nic.in/
4. http://oisd.nic.in/PDF/OISDCaseStudies/OISDCaseStudyCoolingTowerFire.pdf?WhatNewId=20&button=Edit
5. https://www.icheme.org/shop/lpb/2015/issue%20245/explosion%20in%20a%20cooling%20tower.aspx
6. http://www.hindustanpetroleum.com/documents/pdf/AnnualReport2013-14.pdf
7. http://www.thehindu.com/news/national/andhra-pradesh/one-dead-39-injured-in-vizag-refinery-blast/article5052564.ece
8. http://www.thehindubusinessline.com/companies/death-toll-in-hpcl-accident-rises-to-28/article5159682.ece
9. http://indiatoday.intoday.in/story/death-toll-in-vizag-hpcl-refinery-fire-rises/1/301164.html
