Exam type Q Flashcards
Design in Chemical Engineering is generally considered to be the specification of the properties of the process chemistry. Suggest 3 areas where chemical engineers have a further role to play in the design and operation of process plant.
There are a number of strategies which should be considered during design,
Stable, non-toxic, non-flammable chemical processes used for making a product must be one of the objectives of the conceptual design.
Then considering how Inherent Safe Design may be planned, followed by Layers of Protection through relief & control systems. Finally the Operation Management through controlling management of change, permits, hazid and hazop
(c) Based on your answer to question (b) give two examples from the case studies discussed in class where failure in these principles has occurred
Examples come from CSB videos, PEMEX
Explain what is meant by risk assessment in process safety.
Risk assessment is the quantitative evaluation of the likelihood of undesired events and the likelihood of harm or damage being caused, together with the value judgements made concerning the significance of the results.
There are three steps to Risk Assessment, known as:- How Big? - (is the problem).
How Often? - (will it occur)
So What? - (shall I do about it)
A number of course case studies demonstrate a failure to complete a Risk Assessment. Report on two such events and suggest the steps that could have been taken to avoid this failure
Students should be able to use the T2 Reactor, Grangemouth Cracker and CAI Danvers incidents to demonstrate that the use of risk assessment and Hazop would have eliminated these incidents
Describe the focus of HAZID analysis in accordance with chemical plants
Operations involved • Reactor operation • Production/ loss of containment • Protective systems • Alarms/communications
• HAZID is high level analysis
Areas of interest • Corrosion • Erosion • Mechanical impact • Fatigue • Overstress/load • Environment
Safeguards
• Operating instructions
• Entry permit
• Hot work permit
• Electrical isolation permit
• Permit to work
• Isolation permit (valves)
Emergency procedures
What operational routines and procedures need to be considered in the maintenance and/or modification of chemical plant process to ensure the elimination of potential hazardous activities?
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(b) Describe five mechanisms whereby a piece of equipment may be over-pressured (you may use any of the incidents reviewed in class as an exemplar).
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- Organisations are required to have a duty of care in place.
(a) Describe the legislation which specifies this and who or what does that duty of care might be to?
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(b) Suggest 3 practices should an organisation have in place to achieve this and give examples where that was not the case from incidents discussed in class?
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The HASAW Act calls for a “duty of care”, how may operators of chemical plant processes ensure that the requirement of the Act is followed?
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Suggest four appropriate strategies that lead to safer chemical engineering design that you might expect to see at a large chemical process installation.
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From your answers above, suggest one incident with which you are familiar where this did not occur. Report on what the resulting consequences were and how they may have been avoided? Support your report here with evidence form UK legislation
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Explain how risk is considered and managed in process safety
Risk - The likelihood of a specified undesired event occurring within a specified period or in specified circumstances.When and how to consider risk
• Define system boundaries
• Qualify the risks
• Don’t attribute greater precision than is needed
• Recognise social, political and economic implications
• Stimulate public debate on perceived risks and benefits
• Establish consultation and feedback with stakeholders
Risk management
• About control and maintenance to reduce human and financial loss
• Proactive and not reactive => achieved through applying engineering principles
• Acceptable risk when humans involved
Quantitative definition - The estimation of specific loss caused by failure over an operating period of time (108 hours)
Explain what is meant by loss prevention in process safety
Loss prevention - A systematic approach to preventing accidents or minimising their effects. The activities may be associated with financial loss or safety issues. • More defences, less risk
Defence in depth means the use of a diverse strategy based on prevention, protection and compliance. It can be broken down into four main management functions:
• Procedure – The correct way to do it
• Equipment – Specification and Maintenance
• Training - Skills and Knowledge
• Supervision - and Assessment
Loss Prevention
• Process design - design any hazards out of process
• Plant design - design plant ,select and equipment , safe layout
• Plant protection - always a risk of equipment failure and human error , fire risk - leak and fire detection system
Human aspects - accidents due to human error
Define the risks posed to stakeholders described in the HASWA act
Individual risk - The frequency at which an individual may be expected to sustain a given level of harm from the realisation of specified hazards.
Societal risk - The relationship between frequency and the number of people suffering from a specified level of harm in a given population from the realisation of specified hazards.
