PROCESS SAFETY FOR CHEMICAL OPERATIONS

Preview This section provides a brief overview of process safety and its importance in chemical safety and hazard recognition. 

Your own safety is at stake when your neighbor s wall is ablaze. 

What lessons can be learned from this incident  

Perhaps the best known example occurred in Bhopal, India, in 1984. A highly toxic gas, methyl isocyanate (MIC), was released from a chemical plant into the surrounding community. The MIC cloud 

Laboratory Sctfety for Chemistry Students Second Edition. Robert H. Hill, Jr. and David C. Finster. 2016 John Wiley Sons, Inc. Published 2016 by John Wiley Sons, Inc. 

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The American Institute of Chemical Engineers (AIChE) has a 30-year history of involvement with process safety for chemical processing plants. Through its strong ties with process designers, builders, operators, safety professionals and academia, the AIChE has enhanced communication and fostered improvement in the high safety standards of the industry. AIChE publications and symposia have become an information resource for the chemical engineering profession on the causes of accidents and means of prevention. 

Boykin, R. F., and M. Kazarians, "Quantitative Risk Assessment for Chemical Operations," in Proceedings of the International Symposium on Prevention cf Major Chemical Accidents, p. 1. 87, Center for Chemical Process Safety/AIChE, New York, NY (1987). 

The ratios shown above depend heavily on the definition of a near miss and depend on the type of loss. For example, regarding quality-related incidents, there appear to be far fewer near misses and errors or failure conditions per operational interruption. The reason for the lower ratio is that quality-related incidents typically result from excursions that are less severe than personnel safety or process safety occurrences. Chemical processes are... 

The Guidelines for Hazard Evaluation Procedures, Second Edition, issued by the Center for Chemical Process Safety, includes a checklist-questionnaire for chemical operations that fills 45 pages. 

During a 10-week production campaign, over 300 tons of the polymer product was produced [89]. The micro structured reactor (65 cm long 290 kg heavy, special nickel alloy, several ten thousands of microchannels) was operated at a throughput of 1700 kg liquid chemicals per hour. A critical issue was the removal of the reaction heat, which was accomplished within seconds. The yield exceeds that of the former route, albeit it was not detailed. It was also found that the process safety for handling... 

To an experienced operator trained in the handling of industrial chemicals, the dimers present Httle cause for concern in handling or storage. The finished polymer coating presents even less of a health problem contact with the reactive monomer is unlikely. In the ancillary operations, such as cleaning or adhesion promotion, the operator must observe suitable precautions. Before using the process chemicals, operators must read and understand the current Material Safety Data Sheets, which are available from the manufacturers. 

Table 2 Hsts some of the physical, toxicity, flammabiUty, and reactivity properties of common chemicals (10,13,42,45—51). Also given are some of the quantities specified for reporting spills and for compliance with legislated requirements. The OSHA regulations require that material safety data sheets (MSDS) be developed for all process materials, so that the ha2ard data can be communicated to employees (52). Characteristics of toxicity, flammabiUty, chemical iastabiUty, reactivity and reaction energy, operatiag coaditioas, and corrosive properties of constmction materials must all be considered ia analy2iag ha2ard poteatials of chemicals and chemical operations.

R. D. Coffee, in H. H. Fawcett and W. S. Wood, Safety and Accident Prevention in Chemical Operations, 2nd ed., Wiley-Interscience, New York, 1982, p. 305 International Symposium on Runaway Reactions, Center for Chemical Process Safety, New York, 1989, pp. 140, 144,177, 234. 

As microprocessor-based controls displaced hardwired electronic and pneumatic controls, the impac t on plant safety has definitely been positive. When automated procedures replace manual procedures for routine operations, the probability of human errors leading to hazardous situations is lowered. The enhanced capability for presenting information to the process operators in a timely manner and in the most meaningful form increases the operator s awareness of the current conditions in the process. Process operators are expected to exercise due diligence in the supervision of the process, and timely recognition of an abnormal situation reduces the likelihood that the situation will progress to the hazardous state. Figure 8-88 depicts the layers of safety protection in a typical chemical jdant. 

Process Hazard Analysis (PHA) (Dowell, 1994, pp. 30-34.) The OSHA rule for Process Safety Management (PSM) of Highly Toxic Hazardous Chemicals, 29 CFR 1910.119, part (e), reqmres an initial PHA and an update every five years for processes that handle listed chemicals or contain over 10,000 lb (4356 kg) of flammable material. The PHA must be done by a team, must include employees such as operators and mechanics, and must have at least one person skilled in the methodology employed. Suggested methodologies from Process Safety Management are listed in Table 26-1. 

The Center for Chemical Process Safety (CCPS) has identified the need for a publication dealing with process safety issues unique to batch reaction systems. This book, Guidelines for Process Safety in Batch Reaction Systems, attempts to aid in the safe design, operation and maintenance of batch and semi-batch reaction systems. In this book the terms batch and semi-batch are used interchangeably for simplicity. The objectives of the book are to ... 

Britton, E. G., 1999. Avoiding static ignition hazards in chemical operations, American Institute of Chemical Engineers, Center for Chemical Process Safety. New York. 

The American Institute of Chemical Engineers (AICliE) wishes to thank the Center for Chemical Process Safety (CCPS) and those involved in its operation, including its many sponsors whose funding and technical support made this project possible. Particular thanks are due to the members of the Batch Reaction Subcommittee for their enthusiasm, tireless effort and technical contributions. Members of the subcommittee played a major role in the writing of this book by suggesting examples, by offering failure scenarios for the major equipment covered in the book and by suggesting possible solutions to the various Con-cerns/Issues mentioned in the tables. 

Operations Training Gnide for Process Safety. Chemical Mannfactnrers Association, Washington, D.C., 1993. 

Knowledge of the rate is important to design chemical reactors for industrial production. It is also important for optimizing the production and to define the safety limits of operation. As was mentioned in the introduction, various transfer processes can influence chemical rates. The recognition of such interference is of primary importance during any study of kinetics, especially in those studies that will serve as the basis of design for production reactors. 

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