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What are the responsibilities of Chemical Engineers? • Chemical Engineers are concerned with the designing, supervision, construction, installation and operation of plants and equipment’s for manufacturing chemical products. • Chemical Technologists deal with the production of substances with new properties which require new methods of production in the fields of petroleum refining & fertilizer technology. • Chemical Engineers involves in the processing of food and agricultural products, paints and dyes, recycling metals, glass and plastics, cosmetics, mineral based industries and prevention and control of environmental hazards. • Chemical Engineers involves in the research and development activities in the Bio-Tech firms to find out new drugs. Can you explain the flameless oxidizers? These are used to treat volatile organic compounds (VOC) and liquid organic streams. Traditionally, these types of streams were combusted to break down the molecules. The disadvantage of this treatment method was the formation of NOx. Flameless oxidizers use electrically heated ceramic packing and a high velocity introduction system to initiate the destruction of the organic compounds into carbon dioxide and water. Once this oxidation reaction begins, it continues via self-perpetuation. Capital cost for such systems is usually about 25% less than traditional combustion systems and capacities can range from 250 to 40,000 SCFM (standard cubic feet per minute). Thermatrix Inc. is the pioneer for this technology. Visit their website below. which type of compounds are responsible for the foul smells from wastewater plants? The following compounds are responsible for the foul smells from wastewater plants: • Hydrogen Sulphide, • Methyl Mercaptan, • Dimethyl Sulphide, • Dimethyl Disulphide. Can you define TLV (threshold limit value) and it explain? The threshold limit value was set by American Conference of Governmental industrial Hygienists, Inc (ACGIH) which is defined as the level of concentration of a chemical substance in which a worker can work without an unreasonable risk of disease or injury. It can be expressed in ppm or mg/m3. For example the TLV of chlorine for an 8 hrs work day is 0.5ppm or 1.5 mg/m3. Which indicates a worker can work without any unreasonable risk of disease or injury for 8 hours if and only the chlorine concentration in his/her vicinity is within 0.5ppm. What do you understand by Wet bulb Globe temperature? It is used to measure the sultriness of the environment. The sultriness is calculated on the basis of the humidity affects, the air speed and temperature and also the sun`s radiant heating factor. The sultriness in some cases could be fatal and hence it is very important to keep this under consideration. The wet bulb globe temperature index number was developed in the 1950`s and is now accepted as an industry standard. It is comprised of three temperature readings: • Wet bulb temperature • Ordinary dry bulb temperature • Black bulb globe temperature. What is the difference between fractionation and distillation? Fractionation and distillation both methods are used to separate the components present in the solution based on the melting points. Distillation: It is used when boiling point of chemicals are different in the mixtures. Fractionation: It is used when boiling point of chemicals are close to each other in the mixtures. Fractionation. Fractionation distillation mostly used in petroleum industry. What is oxidation and reduction reaction? Oxidation: When there is a loss of hydrogen or electrons, OR gain of oxygen is known as Oxidation reaction. Reduction: When there is a gain of hydrogen or electron OR loss of oxygen is known as reduction reaction Example of oxidation-reduction reaction is observed in human body, when an electron is transferred into the cell and oxidation of glucose take place from which we get the energy. What is the difference between CFM and SCFM? CFM (Cubic Feet Per Minute) and SCFM (Standard Cubic Feet Per Minute) are both measure of flow rate. CFM might refer to either the flow rate of a gas or a liquid, whereas SCFM refers only to the flow rate of a gas. The same mass flow rate of a gas (i.e., lbs/minute) is equivalent to various volumetric flow rates (i.e., CFM) depending upon the gas pressure and temperature. Thus, when gas flow rates are specified, it is very important to specify at what pressure and temperature the gas was measured. When the gas flow rate is specified as SCFM, it means that the flow rate was measured at a set of standard pressure and temperature conditions. In the USA, the most common set of standard conditions used in industry is 60 degrees Fahrenheit and one atmosphere of pressure. Note that we have stressed most common, because there are other standard conditions that may be used. It is always best to spell out what standard conditions are being used (i.e., 1200 SCFM at 600F and 1 atmosphere pressure). When gas flows are expressed simply as CMF, the reader Is can only speculate as to what gas temperature and pressure apply to that flow rate… and, because of that, the CFM flow rate cannot be converted to a mass flow rate. What is the maximum recommended velocity for steam in a plant pipe network? • High pressure steam should be limited to about 150 ft/s and Low pressure steam should be limited to about 100 ft/sec. • Saturated steam at low pressure is common for heating services and secondary process pipes 99 - 131 ft/sec. • Saturated steam at high pressure is common in powerhouse, boiler and main process lines 82 - 131 ft/sec. • Superheated steam is common in power generation and turbine plants is 100 - 300 ft/sec. • Saturated Steam at peak load is < 164 ft/sec. How can you keep our seawater used for heat rejection clean before entering our heat exchangers? Seawater is used as a cooling agent in condensers and coolers. Intermittent injection of chlorine gas is used to eliminate marine growth. The system is a once through type. The band screens before the suction of the pumps are supposed to eliminate scales and other suspended materials. The band screens are not properly functioning. Cooling water flow is about 2.6 million gallons per hour. The pre-screening and mobile screens are not a sufficient protection for the recirculating water. This is a very common problem. In clean salt water the biological grow in the cooling water pipes is the main problem (mussels, barnacle, algae, etc.). After the life cycle is finished, they die and blocking the condenser tubes. To solve this debris problems, use self-cleaning Debris Filters (DF) directly installed in front of the water box of the heat exchangers. We have some pieces of metals that have been “powder coated”, how does that work? Powder coatings are similar to paint, but they are usually much more durable. Rather than adding a solvent to the pigments and resins in paint, as is typically the case, powder coatings are applied to the surface in a fine granular form. They are typically sprayed on so that they stick to the surface. Once the surface has been sufficiently spray coated, the piece is baked at high temperatures, and the pigment and resins pieces melt and form a durable, color layer. What is the chemical composition of fat in human body? Fat found in human body is mainly composed of: • Glycerides • Glycerides+Phospholipids • Glycolipids • Phosphoinotisides • Tocopherol. Why graphite rod is used in nuclear reactor? Graphite rod is used in nuclear reactor to convert fast moving neutrons into thermal neutrons. What is iron ore consisting of? Iron ore is consisting of Fe2O3 Iron ores are rocks and minerals from which metallic iron can be economically extracted. The ores are usually rich in iron oxides and vary in colour from dark grey, bright yellow, or deep purple to rusty red. The iron itself is usually found in the form of • magnetite (Fe3O4, 72.4% Fe), • hematite (Fe2O3, 69.9% Fe), • goethite (FeO(OH), 62.% Fe), • limonite (FeO(OH)·n(H2O), 55% Fe) or siderite (FeCO3, 48.2% Fe). What is the difference between unit operation and unit process? When a unit operation is considered, changes take place in mass and concentration where energy is provided from an external source without any chemical change. Few examples would be evaporation, distillation, and mixing. In the same manner, when a unit process is considered, the reactant is processed in the feed which means that reactants present in the feed are transformed to products by means of chemical reaction and with the assistance of energy being supplied to the system. Can you explain a solvent? A solvent can be defined as a liquid which has the capability to suspend, dissolve or to take out other chemicals where they do not perform any chemical change to the material or solvent. The main process of solvents is to clean, apply, process or to separate materials. Can you define Gibbs free energy? Gibbs free energy is mentioned as the maximum amount of mechanical work or available energy which is done by the system under stable temperature and pressure.