Chemical Engineering -Exam with complete solutions

Chemical Engineering - ANSWER Deals mostly with large-scale production of chemical products, responsible for the invention of new processes American Institute of Chemical Engineers (AIChE) - ANSWER Largest professio ...

Chemical Engineering - ANSWER Deals mostly with large-scale production of chemical products, responsible for the invention of new processes American Institute of Chemical Engineers (AIChE) - ANSWER Largest professional organization of chemical engineers Chemical Engineering Principles - ANSWER Dictate the way in which chemical engineers design, study, and troubleshoot chemical operations Chemistry - ANSWER Scientific study of materials, their composition and structure, their properties, their interactions, and changes they undergo Thermodynamics - ANSWER Study of work, energy, and efficiency in large-scale systems Zeroth Law - ANSWER thermal equilibrium First Law - ANSWER law of conservation of energy Second Law - ANSWER Energy will naturally disperse; Entropy Law Entropy - ANSWER the tendency of all energy and matter to seek a state of uniformity Third Law - ANSWER the colder a substance gets, the less its atoms move Fluid Dynamics - ANSWER Study of fluid flow Viscosity - ANSWER the liquid's thickness, resistance to being deformed Surface tension - ANSWER a characteristic created by liquid molecules being attracted to each other Turbulent flow - ANSWER Velocity fluctuations, highly disordered; inertial forces dominate Laminar flow - ANSWER Has no disruption between layers of fluid; viscous forces dominate Reynolds number - ANSWER Characterizes fluid flow: density(velocity)(diameter of pipe) / dynamic viscosity; under 2,300 - Laminar, Over 10,000 - Turbulent Applications of Fluid flow - ANSWER Aerodynamic design of planes / cars Mass Balance - ANSWER States that matter cannot be created or destroyed and must be constant in a closed loop - Amount of material that exists prior to chemical reaction is equal to amount of material after reaction Differential Mass Balance - ANSWER measurement taken at the same point over time; applied to a continuous process, should always be the same Integral Mass Balances - ANSWER taken at two different points to show what is happening between one point and another, typically taken at beginning and end of process Crucial Measurements - ANSWER Fluid flow rate, Pressure, Temperature Fluid Flow Rate Measurement - ANSWER Measure of flow per unit time Differential pressure flowmeter - ANSWER Relies on the concept that as speed of a fluid increases, its pressure decreases; constrict the flow using an obstruction or narrowing of the pipe Velocity flowmeter - ANSWER Measure the speed of passing fluid and the depth, used in airplanes to measure speed relative to the air Mechanical flowmeter - ANSWER uses a variety of mechanical devices inside pipe Impeller - ANSWER in a mechanical flowmeter, measure # of rotations per unit time Mass flowmeter - ANSWER measure mass rather than volume, used when measuring gases Open-channel flowmeter - ANSWER measure flow in a channel rather than in a pipe, as in a stream or river Pressure Measurement - ANSWER Pressure must be held within acceptable ranges, measured by force per unit area Gauge pressure - ANSWER relative to atmospheric pressure Absolute pressure - ANSWER is relative to vacuum, Gauge pressure + local atmospheric pressure Liquid column gauge - ANSWER a pressure meter that uses fluid in a tube, one end is connected to the pressure to be meaured Bourdon-style pressure gauge - ANSWER uses coil of tubing, shape of the coil changes in relation to the pressure changes Aneroid gauge - ANSWER uses a small bellows that changes shape as pressure changes, expands as pressure decreases; connected to a gauge Electronic gauges - ANSWER Use magnetism, optics, capacitance, etc. Temperature Measurement - ANSWER Many chemical reactions can only occur within certain safe and acceptable temperature ranges, too much variation in temperature can have serious consequences Thermocouple sensor temperature measurement device - ANSWER Made from two different pieces of conductive material, as temperature increases, voltage changes; often used as safety devices in gas appliances Resistance temperature measurement device - ANSWER Relies on the concept that resistance changes as temperature changes Infrared temperature measurement device - ANSWER Measures thermal radiation emitted from a material, useful when dealing with caustic materials, as there is no need for direct contact Bimetallic temperature measurement device - ANSWER Use the concept that different metals expand and contract due to temperature at different rates; strips of unlike metals are joined, and as temperature changes, the strips will bend Change-of-state temperature measurement device - ANSWER Typically stickers or labels, change colors permanently with temperature Chemical Engineering Applications - ANSWER Most chemical engineers plane and operate chemical plants, wastewater treatment facilities, biomedical facilities, food and beverage facilities, and power plants Continuous chemical plant operations - ANSWER Materials are fed into facility, reactions occur, and materials are fed out of facility constantly; most efficient and economical method for large-scale production, Ex. - Refining petroleum Batch chemical plant - ANSWER Chemicals are fed into system, chemical process takes place, and materials are removed; typically used for smaller-scale quantities of finish products, Ex. - Pharmaceuticals Chemical Plant Design - ANSWER Chemical plants must be profitable to owners, safe for workers, and friendly to environment Plant layouts - ANSWER Take into account: -Economics of construction and operation -Specific requirements of the processes -Convenience of the maintenance -Possibility of expansion -Safety of workers, environment and community ESCPS - Elephants see casual particular snakes Block flow diagrams - ANSWER show basic representations of major processes Process flow diagrams - ANSWER show main flow of chemicals, general processes, and main equipment Piping and instrumentation diagrams - ANSWER show every detail of plant layout and design Things to Consider for Plant Location - ANSWER -Location of raw materials: transportation may be expensive -Energy resources: resources should be readily available -Local communities: may welcome or oppose new plants, employee access Site Layout - ANSWER Describes specific location of all required facilities, includes plant, road, parking, storm water management, and utilities; should allow for efficient flow of materials through site Site Layout Accounts - ANSWER Accounts for waste - major consideration because of cost of disposal, should be minimized or recycled, disposal must meet local regulations Occupational Safety and Health Administration (OSHA) - ANSWER ensures safe and healthful conditions for workers, ensures workers remain safe and exposure to hazardous materials is limited OSHA's "right to know" laws - ANSWER Ensure people know what chemicals they are being exposed to and what health effects could be Material safety data sheets (MSDS) and training - ANSWER Provides information about OSHA and protection