The major responsibilities and functions of a chemical engineer in a chemical process plant can be identified on the basis of the previous discussion:
• Design and operation of the reactor: The chemical reactor is the key unit of the process where the raw materials are converted into desired products. The success of the process is dependent on efficient, economic functioning of the reactor. A chemical engineer should be able to obtain the fundamental information about the intrinsic rate of reaction and its dependence on system parameters, and on the basis of this information, specify the type and size of the vessel that would be used to conduct the reaction. He/she should be able to understand the effect of operating parameters on the reaction and manipulate the conditions to obtain the desired production rate and product composition and purity.
• Design and operation of separation equipment: The vast majority of units in the process plant are aimed at accomplishing physical separation of components: obtaining reactants of the desired purity from the available raw materials, recovering the desired product from the product stream exiting the reactor, and removing pollutants from waste streams before they are released into the environment. In general, no chemical reaction or changes in molecular species occur in the separation units. However, reactive separations, where separations are effected by incorporating a chemical reaction in the separation scheme, are not uncommon. A chemical engineer should be able to quantify the nature of interactions among various components of any stream, identify the separation technique and obtain fundamental thermodynamic and kinetic data, and design the equipment to accomplish any separation needed in the process. He/she should be able to manipulate the operational parameters to obtain the desired purity in the separated streams.
• Design and operation of material and energy transfer equipment: Even a cursory glance at a chemical plant will reveal a number of units interconnected with an impressive network of pipes. This network is needed to transfer vast quantities of material through various processing steps. A chemical engineer should be able to design and operate an efficient system to accomplish these transfers. This system will typically include pumps, compressors, and piping for transferring fluids—gases and liquids. Transfers of solid materials can be effected by dissolving or suspending them in appropriate liquids and pumping the solutions or slurries. Solids can also be conveyed pneumatically using gases or on conveyer belts. Chemical process plants also involve transferring vast quantities of energy required for separations and conducting reactions. A chemical engineer should also be able to design systems for transferring energy to and from process streams to achieve and maintain process units at their desired design temperatures. As mentioned in Chapter 2, the chemical sector is one of the highest energy-consuming sectors of the economy. Most chemical processes are energy intensive, and a chemical engineer should be able to minimize the energy cost by properly designing and operating the energy transfer equipment.
• Process control: All the steps in a chemical process—whether physical separations or chemical reactions—are typically designed to occur at specific conditions. Deviation from these design operating conditions inevitably results in formation of off-quality product or incomplete separations of components. Maintaining the process plant conditions (pressure, temperature, flow rates, concentrations, etc.) at their setpoints is absolutely critical for meeting product quality specifications and efficient operation of the plant. A chemical engineer must be able to design and tune the control system to ensure that the process operates as designed and corrective actions are taken to counteract any disturbances within the processing units. These corrective actions should allow the process unit to return to its setpoint within a reasonable period of time such that the disturbances are not propagated throughout the plant.
Each chemical process is unique with respect to the species involved, reactions, and separations; however, analysis of each step is based on unifying scientific and engineering principles. The education of a chemical engineer does not involve teaching specifics of a particular process but rather imparting a knowledge of these unifying principles and concepts that can be applied to any process. The curriculum that accomplishes this educational objective is described in the next section.
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