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Semester 2

Process Safety and Environmental Issues in Chemical Engineering 3 (CHEE09019)

Subject

Chemical Engineering

College

SCE

Credits

20

Normal Year Taken

3

Delivery Session Year

2023/2024

Pre-requisites

Course Summary

In this course, students cover contemporary safety and environmental concerns as they impinge on the practising engineer, the legal and regulatory background to engineering activity, to ensure safe operation of hazardous processes, and the procedures to be followed in seeking a license from the environmental protection agencies for the operation of processes involving prescribed substances. Generation, propagation and the fate of pollutants discharged to the air, to water and to the ground are discussed along with means of mitigating emissions by elimination, substitution and pre-discharge treatment are considered. Methods of identifying process hazards are introduced leading to risk assessment and consequence analysis using hand calculation methods are presented to allow risk assessment and its application to the process industries to be appreciated.

Course Description

For clarity the two topics are set out separately:Environmental Issues:- The national (UK and EU) and international environmental legislative framework- The importance of public perception and of basic science in informing regulations and engineering practice, and the interplay between all these.- Basic scientific mechanisms and facts that underpin some of the major environmental issues of our age, as well as what impact if any the process industries may have on these issues and how this impact can be addressed. A point is made that public perception may or may not be based on science and facts, and how important it is for the engineer to be mindful of it in his or her practice.- Deducing from existing regulations, environmental standards, Best Available Techniques and local state of the environment the required operating performance of chemical plant- Selecting plant and processes in the light of targets limiting the emissions of acid and greenhouse gases- Estimating dispersal of gaseous emissions in vents and plumes- Interpreting terms used in the regulation of aqueous emissions, translating these into limits on discharge rates. Calculate the effect of BOD discharge into waterways and select waste disposal treatments appropriate to effluents and body of water where the discharge is taking place- Performing basic material balances around biological treatment plants of waste water effluents, as would be required in any permit application; and preliminary selection and sizing of water treatment plants.- Selecting waste minimisation and recycling strategies as alternatives to, or mitigation of, discharge, dumping and incineration of waste.Process safety:- Overview of process safety. Problems of complexity. Principles of Inherent safety. Layers of Protection concept.- Uk and European Safety Legislation. Historical background. HASAWA, regulations, role of HSC and HSE. European legislative framework.- The Concept of risk. Definitions of risk andhazard. Acceptability of risk. Perception of Risk. Quantification of risk. Cost-benefit analysis. Fatal accident rate. ALARP.- Probability and Frequency for Risk Assessment. Basic probability calculations. Frequency and duration of coincident events.- Reliability. Definitions. Failure distributions. Reliability with multiple components. Active and passive failure. Trip reliability. Fractional dead time. Multiple channel trip systems.- Fault Trees. Construction of fault trees. Finding minimum cut sets.- Event Trees. Construction of event trees. Bow-Tie analysis. Buncefield accident and learning points.- Hazard Identification. Predictive vs. experience based hazard identification. Checklists and codes of practice. HAZOP methodology. Dow and Mond Indices.- Occupational Health. Damaging agents. Harmful substances. Assimilation routes. Exposure limits. Toxicology, epidemiology, other methods for establishing exposure limits. COSHH. Exposure control.- Source terms. Leak rates for liquids and gases. Evaporation rates from spills and jets.- Fire. Flammability limits, flash point, sources of ignition. Types of fire. Diffusion and pre-mixed flames. Damaging effects. Flame size. Radiation estimation. Boilover. Area Classification.- Explosions. Types of explosion. Damaging effects. TNT method for overpressure estimation. BLEVE. Dust Explosions.- Human Error. Human error rates. Types of error. Performance levels. Reducing human error.- Safety Management Systems. Hazards of operation and maintenance. Permit to work systems. Preparation of plant for maintenance.- Safety for Design. Specific advice on safety considerations for design projects.

Assessment Information

Written Exam 100%, Coursework 0%, Practical Exam 0%

Additional Assessment Information

Written exam: 100%

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