Dear Nishtha,
the following publications cover the answer to your question.
The first publication is a review article containing a comprehensive data on the topic of concern.
1-http://www.sciencedirect.com/science/article/pii/S0304389409013727
Journal of Hazardous Materials
Volume 173, Issues 1–3, 15 January 2010, Pages 19–32
Hazard and operability (HAZOP) analysis. A literature review
Jordi Dunjóa, Vasilis Fthenakisb, c, Juan A. Vílcheza, Josep Arnaldosa
Abstract
Hazard and operability (HAZOP) methodology is a Process Hazard Analysis (PHA) technique used worldwide for studying not only the hazards of a system, but also its operability problems, by exploring the effects of any deviations from design conditions. Our paper is the first HAZOP review intended to gather HAZOP-related literature from books, guidelines, standards, major journals, and conference proceedings, with the purpose of classifying the research conducted over the years and define the HAZOP state-of-the-art.
http://www.sciencedirect.com/science/article/pii/S0304389409013727
2-CHEMICAL ENGINEERING TRANSACTIONS
VOL. 31, 2013
The Italian Association
of Chemical Engineering
Online at: www.aidic.it/cet
Guest Editors: Eddy De Rademaeker, Bruno Fabiano, Simberto Senni Buratti
Copyright © 2013, AIDIC Servizi S.r.l.,
ISBN 978-88-95608-22-8; ISSN 1974-9791
CFD - Assisted Safety Design in a Flue Gas Treatment
Plant Retrofit
Pietro Arestaa
, Stefano Di Pilatob
, Marco Derudia
, Giuseppe Nanob
A retrofit project related to an Al2O3 calcination flue gas treatment line, consisting in the installation of a fabric filter downstream an existing electrostatic precipitator (ESP) was the object of this study. In this case, the replacement of the existing exhaust fan with a more performing one would have been potentially exposed the existing precipitator to suction conditions that did not fall within the process conditions considered when the ESP was designed. In other words, performing a detailed safety analysis focused on the interface between new and existing plants it was highlighted a possible risk of implosion that would not be easily found by following the most common classical approaches as the historical analysis or an HAZOP limited to the new equipments. This hazard would not have been easily reduced by installing reinforcements due to the difficulty (both technical and economical) to modify such existing equipment. The chosen approach was to face the problem analogously to the protection of a vessel from overpressure, that means to size a direct action PSV (counterweight actuated), which opens when a given differential pressure (with opposite sign with respect to the traditional PSV design) is reached. The risk thus determined was translated in terms of a worst case scenario, on the basis of which the design of safeguards has been carried out. In particular, this scenario was identified considering that all the pressure drops are concentrated upstream the equipment to protect, exposing the filter to maximum
suction levels. The presence of a fabric filter bypass duct, allowing direct communication between fan and ESP, the complete obstruction of a duct upstream of it and the fan running at full rotational speed were the main hypotheses constituting the worst case scenario. Design choices were verified and validated through a computational fluid-dynamics analysis, evidencing that CFD can be a powerful and useful tool to address safety design issues, allowing to numerically test safeguards actions and consequently evaluating the impact that design choices would have for the purposes of risk reduction and mitigation.
Hoping this will be helpful,
Rafik
Dear Nishtha,
the following publications cover the answer to your question.
The first publication is a review article containing a comprehensive data on the topic of concern.
1-http://www.sciencedirect.com/science/article/pii/S0304389409013727
Journal of Hazardous Materials
Volume 173, Issues 1–3, 15 January 2010, Pages 19–32
Hazard and operability (HAZOP) analysis. A literature review
Jordi Dunjóa, Vasilis Fthenakisb, c, Juan A. Vílcheza, Josep Arnaldosa
Abstract
Hazard and operability (HAZOP) methodology is a Process Hazard Analysis (PHA) technique used worldwide for studying not only the hazards of a system, but also its operability problems, by exploring the effects of any deviations from design conditions. Our paper is the first HAZOP review intended to gather HAZOP-related literature from books, guidelines, standards, major journals, and conference proceedings, with the purpose of classifying the research conducted over the years and define the HAZOP state-of-the-art.
http://www.sciencedirect.com/science/article/pii/S0304389409013727
2-CHEMICAL ENGINEERING TRANSACTIONS
VOL. 31, 2013
The Italian Association
of Chemical Engineering
Online at: www.aidic.it/cet
Guest Editors: Eddy De Rademaeker, Bruno Fabiano, Simberto Senni Buratti
Copyright © 2013, AIDIC Servizi S.r.l.,
ISBN 978-88-95608-22-8; ISSN 1974-9791
CFD - Assisted Safety Design in a Flue Gas Treatment
Plant Retrofit
Pietro Arestaa
, Stefano Di Pilatob
, Marco Derudia
, Giuseppe Nanob
A retrofit project related to an Al2O3 calcination flue gas treatment line, consisting in the installation of a fabric filter downstream an existing electrostatic precipitator (ESP) was the object of this study. In this case, the replacement of the existing exhaust fan with a more performing one would have been potentially exposed the existing precipitator to suction conditions that did not fall within the process conditions considered when the ESP was designed. In other words, performing a detailed safety analysis focused on the interface between new and existing plants it was highlighted a possible risk of implosion that would not be easily found by following the most common classical approaches as the historical analysis or an HAZOP limited to the new equipments. This hazard would not have been easily reduced by installing reinforcements due to the difficulty (both technical and economical) to modify such existing equipment. The chosen approach was to face the problem analogously to the protection of a vessel from overpressure, that means to size a direct action PSV (counterweight actuated), which opens when a given differential pressure (with opposite sign with respect to the traditional PSV design) is reached. The risk thus determined was translated in terms of a worst case scenario, on the basis of which the design of safeguards has been carried out. In particular, this scenario was identified considering that all the pressure drops are concentrated upstream the equipment to protect, exposing the filter to maximum
suction levels. The presence of a fabric filter bypass duct, allowing direct communication between fan and ESP, the complete obstruction of a duct upstream of it and the fan running at full rotational speed were the main hypotheses constituting the worst case scenario. Design choices were verified and validated through a computational fluid-dynamics analysis, evidencing that CFD can be a powerful and useful tool to address safety design issues, allowing to numerically test safeguards actions and consequently evaluating the impact that design choices would have for the purposes of risk reduction and mitigation.
Hoping this will be helpful,
Rafik
Dear Nishtha,
the following publications cover the answer to your question.
The first publication is a review article containing a comprehensive data on the topic of concern.
1-http://www.sciencedirect.com/science/article/pii/S0304389409013727
Journal of Hazardous Materials
Volume 173, Issues 1–3, 15 January 2010, Pages 19–32
Hazard and operability (HAZOP) analysis. A literature review
Jordi Dunjóa, Vasilis Fthenakisb, c, Juan A. Vílcheza, Josep Arnaldosa
Abstract
Hazard and operability (HAZOP) methodology is a Process Hazard Analysis (PHA) technique used worldwide for studying not only the hazards of a system, but also its operability problems, by exploring the effects of any deviations from design conditions. Our paper is the first HAZOP review intended to gather HAZOP-related literature from books, guidelines, standards, major journals, and conference proceedings, with the purpose of classifying the research conducted over the years and define the HAZOP state-of-the-art.
http://www.sciencedirect.com/science/article/pii/S0304389409013727
2-CHEMICAL ENGINEERING TRANSACTIONS
VOL. 31, 2013
The Italian Association
of Chemical Engineering
Online at: www.aidic.it/cet
Guest Editors: Eddy De Rademaeker, Bruno Fabiano, Simberto Senni Buratti
Copyright © 2013, AIDIC Servizi S.r.l.,
ISBN 978-88-95608-22-8; ISSN 1974-9791
CFD - Assisted Safety Design in a Flue Gas Treatment
Plant Retrofit
Pietro Arestaa
, Stefano Di Pilatob
, Marco Derudia
, Giuseppe Nanob
A retrofit project related to an Al2O3 calcination flue gas treatment line, consisting in the installation of a fabric filter downstream an existing electrostatic precipitator (ESP) was the object of this study. In this case, the replacement of the existing exhaust fan with a more performing one would have been potentially exposed the existing precipitator to suction conditions that did not fall within the process conditions considered when the ESP was designed. In other words, performing a detailed safety analysis focused on the interface between new and existing plants it was highlighted a possible risk of implosion that would not be easily found by following the most common classical approaches as the historical analysis or an HAZOP limited to the new equipments. This hazard would not have been easily reduced by installing reinforcements due to the difficulty (both technical and economical) to modify such existing equipment. The chosen approach was to face the problem analogously to the protection of a vessel from overpressure, that means to size a direct action PSV (counterweight actuated), which opens when a given differential pressure (with opposite sign with respect to the traditional PSV design) is reached. The risk thus determined was translated in terms of a worst case scenario, on the basis of which the design of safeguards has been carried out. In particular, this scenario was identified considering that all the pressure drops are concentrated upstream the equipment to protect, exposing the filter to maximum
suction levels. The presence of a fabric filter bypass duct, allowing direct communication between fan and ESP, the complete obstruction of a duct upstream of it and the fan running at full rotational speed were the main hypotheses constituting the worst case scenario. Design choices were verified and validated through a computational fluid-dynamics analysis, evidencing that CFD can be a powerful and useful tool to address safety design issues, allowing to numerically test safeguards actions and consequently evaluating the impact that design choices would have for the purposes of risk reduction and mitigation.
Hoping this will be helpful,
Rafik
Dear Nishtha
HAZOP is a structured and systematic examination of a planned or existing process or operation in order to identify and evaluate problems that may represent risks to personnel or equipment, or prevent efficient operation. HAZARD and OPERABILTY (HAZOP) is a well known and well documented study. HAZOP is used as part of a Quantitative Risk Assessment (QRA) or as a standalone analysis
1. Familiarisation with background documentation.
2. Planning of the workshop meeting in a pre-meeting with the customer in order to identify HAZOP strategy, division of the subsystems/nodes (e.g. line, pump, vessel, compressor), choose relevant Piping and Instrument Diagrams (P&ID), and identifying guide words.
3. Accomplishment of the HAZOP review.
4. Documentation of observations into information and actions point, document findings on the P&IDs.
5. Draft report for client review.
6. Final HAZOP report.
Dust removal from a gas stream is a common problem in many industrial processes . In the last decades, plant managers faced more and more often the necessity to improve de dusting systems in order to meet more stringent law requirements, inspired by the principle of the “maximum safety technologically feasible” Following points may consider for HAZOP study. SAFETY PLAN AND HAZOP STUDY must be supplied by equipments designer, like Control loop types pressure, temperature, Level, air to fuel ratio, Control configuration, Fuel changeover, Simultaneous fuel firing, alarms etc.
1. CFD is suitable to be a very useful tool in assisting risk analysis, since it allows simulating different scenarios on the same geometry or, on the other hand, changing easily the geometrical configuration (e.g. insertion of guide vanes, modification of the position of a safeguard) and evaluating the direct impact of safeguards action on the risk reduction and consequences mitigations.
2. Retrofit of existing plants, where the designer is required to introduce changes on an existing line to improve its performance or useful life, poses a problem of interface between new and existing elements that must be addressed in a critical manner.
3. The vacuum breaker device to be defined, the actual gas flow-rate can be calculated as the intersection between the damper aspiration function and the fan characteristic curve.
4. Each equipment to be properly designed, considering the process condition existing in the plant until the retrofit operation; the new de dusting plant cannot protect against high negative pressure events.
5. A safety system can be designed for the retrofit of an alumina calcinations flue gas de dusting plant where, downstream to the existing electrostatic precipitator (ESP), a new bag filter may be installed. In particular, the sizing of safeguards and auxiliary equipments installed to reduce possible risks to be verified by means of a Computational Fluid-Dynamics (CFD) study of the unsafe case scenarios.
6. This hazard would not have been easily reduced by installing reinforcements due to the difficulty (both technical and economical) to modify such existing equipment. The chosen approach was to face the problem analogously to the protection of a vessel from overpressure, that means to size a direct action PSV (counterweight actuated),
Advantages and benefits.
HAZOP puts large efforts into high quality of preparation, planning, accomplishment and documentation and this makes accidents free.
Regards,
Prem Baboo
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