© 2012 Delmar, Cengage Learning Chapter 11 Engineering Controls

© 2012 Delmar, Cengage Learning Risk Evaluation Hazardous materials Chemical process Physical operations Equipment design Plant location and layout Operator practices and training

© 2012 Delmar, Cengage Learning Hazardous Materials Evaluation A detailed analysis of all the properties of the materials handled, stored, and processed in the plant: Quantities Physical properties Toxicity Stability hazards Corrosiveness Impurities

© 2012 Delmar, Cengage Learning Chemical Process Evaluation Analyzes the hazardous properties of reactants, which are products that might be formed under certain conditions, and the environmental effects of those products.

© 2012 Delmar, Cengage Learning Physical Operations Evaluations Dusting Heat transfer Pressure Vaporization Spaying Mixing Separation Generation

© 2012 Delmar, Cengage Learning Equipment Design Evaluation Equipment systems are designed so that the failure of one or more devices will not result in a disaster.

© 2012 Delmar, Cengage Learning Plant Location and Layout Evaluation Key elements include: Drainage and runoff control Climatic conditions Effects of uncontrolled release Community capability and emergency response Plant accessibility Available utilities Gate security Hazardous unit placement Spacing of equipment

© 2012 Delmar, Cengage Learning Operator Practices and Training Evaluation Operational failures have been identified as the most frequent cause of industrial disasters.

© 2012 Delmar, Cengage Learning Design and Operation of Plants for Safety There must be adequate spacing between process equipment, specific storage, and loading facilities. Evaluate and limit the storage of hazardous material. Evaluate the use of open structures and will recommend new designs for total storage containment.

© 2012 Delmar, Cengage Learning Figure 11-1 Triangular Equipment Placement

© 2012 Delmar, Cengage Learning Alarms and Indicators The most effective tool used by process technicians in the operation of a large chemical facility are alarms and indicators.

© 2012 Delmar, Cengage Learning Fire Alarms and Detection Systems Automatic fire alarm systems come in three types: Fixed-temperature type Rate-of-rise type Nuclear detector type

© 2012 Delmar, Cengage Learning Redundant Alarm and Shutdown Devices Operating a large chemical complex requires the use of redundant systems that provide emergency warning and shutdown protection. Redundancy is a process that uses two or more devices to shut down a system.

© 2012 Delmar, Cengage Learning Interlocks and Automatic Shutdown Devices An interlock is a device that will prevent an operational action unless a specific condition has been satisfied Software Hardwire A permissive is a special type of interlock that contains a set of conditions that must be satisfied before a piece of equipment can be started.

© 2012 Delmar, Cengage Learning Process Containment and Upset Control There are a number of elements in controlling process containment and in the design of upset control: Reduction in hazardous material storage inventory Storage of liquefied gases and the conditions under which these should be stored Plan for a design that provides total containment

© 2012 Delmar, Cengage Learning Figure 11-3 Traditional and Nontraditional Diking Systems (Totally Self-Contained).

© 2012 Delmar, Cengage Learning Closed System/Closed-Loop Sampling Closed systems/closed-loop sampling is a procedure where a bypass loop is installed that allow a small part of the system to be diverted from the main flow.

© 2012 Delmar, Cengage Learning Figure 11-4 Closed-Loop Sampling System

© 2012 Delmar, Cengage Learning Floating Roof Tank and Ventilation Systems Floating roof storage tanks are used for storing materials at atmospheric pressure. Ventilation systems are usually designed to protect process technicians from organic vapors, harmful additive dusts, and fumes.

© 2012 Delmar, Cengage Learning Figure 11-5 Floating Tank Designs

© 2012 Delmar, Cengage Learning Effluent Control and waste Water Treatment New technicians are typically assigned to this area in order to train on a variety of complex systems.

© 2012 Delmar, Cengage Learning Figure 11-6 Clarifier

© 2012 Delmar, Cengage Learning Figure 11-7 Settling Basin

© 2012 Delmar, Cengage Learning Noise Abatement Noise abatement is an engineering procedure designed to reduce or limit noise through the use of modern technology.

© 2012 Delmar, Cengage Learning Flares Flares are used to burn waste gases and control pressure generated by process upsets.

© 2012 Delmar, Cengage Learning Figure 11-8 Flare System

© 2012 Delmar, Cengage Learning Pressure Relief Devices Safety valves for gases Relief valves for liquids Rupture discs for both

© 2012 Delmar, Cengage Learning Figure 11-9 Pressure Relief Devices