Fluid catalytic cracking Wikipedia. A typical fluid catalytic cracking unit in a petroleum refinery. Fluid catalytic cracking FCC is one of the most important conversion processes used in petroleum refineries. It is widely used to convert the high boiling, high molecular weight hydrocarbon fractions of petroleumcrude oils into more valuable gasoline, olefinic gases, and other products. Cracking of petroleum hydrocarbons was originally done by thermal cracking, which has been almost completely replaced by catalytic cracking because it produces more gasoline with a higher octane rating. It also produces byproduct gases that have more carbon carbon double bonds i. The feedstock to FCC is usually that portion of the crude oil that has an initial boiling point of 3. C or higher at atmospheric pressure and an average molecular weight ranging from about 2. La Pelicula Patch Adams. This portion of crude oil is often referred to as heavy gas oil or vacuum gas oil HVGO. Providing study notes, tips, and practice questions for students preparing for their O level or upper secondary examinations. You can find notes and exam questions. Organic chemistry is the chemistry of carbon compounds. All organic compounds contain carbon however, there are some compounds of carbon that are not. NPL Report MATC A 95 Steam Turbine Operating Conditions, Chemistry of Condensates, and Environment Assisted Cracking A Critical Review Shengqi Zhou and Alan. Table 2 Additives used in the manufacture of polyurethanes. Manufacturing process. As an example, consider the manufacture of a moulded item that might otherwise be. Fig9.jpg' alt='Example Of Cracking In Chemistry' title='Example Of Cracking In Chemistry' />Ig Nobel Prizes spotlighted scientists whose work walks the fine line between silly and significant. MJ03 3 Alkenes are unsaturated hydrocarbons. They undergo addition reactions. Two of the methods of making alkenes are cracking and the thermal. Example Of Cracking In Chemistry' title='Example Of Cracking In Chemistry' />In the FCC process, the feedstock is heated to a high temperature and moderate pressure, and brought into contact with a hot, powdered catalyst. The catalyst breaks the long chain molecules of the high boiling hydrocarbon liquids into much shorter molecules, which are collected as a vapor. EconomicseditOil refineries use fluid catalytic cracking to correct the imbalance between the market demand for gasoline and the excess of heavy, high boiling range products resulting from the distillation of crude oil. As of 2. 00. 6, FCC units were in operation at 4. FCC to produce high octane gasoline and fuel oils. During 2. FCC units in the United States processed a total of 5,3. FCC units worldwide processed about twice that amount. FCC units are less common in Europe and Asia because those regions have high demand for diesel and kerosene, which can be satisfied with hydrocracking. In the US, fluid catalytic cracking is more common because the demand for gasoline is higher. Flow diagram and process descriptioneditThe modern FCC units are all continuous processes which operate 2. There are several different proprietary designs that have been developed for modern FCC units. Each design is available under a license that must be purchased from the design developer by any petroleum refining company desiring to construct and operate an FCC of a given design. There are two different configurations for an FCC unit the stacked type where the reactor and the catalyst regenerator are contained in a single vessel with the reactor above the catalyst regenerator and the side by side type where the reactor and catalyst regenerator are in two separate vessels. These are the major FCC designers and licensors 1346Side by side configuration Stacked configuration Each of the proprietary design licensors claims to have unique features and advantages. A complete discussion of the relative advantages of each of the processes is beyond the scope of this article. Reactor and RegeneratoreditThe reactor and regenerator are considered to be the heart of the fluid catalytic cracking unit. The schematic flow diagram of a typical modern FCC unit in Figure 1 below is based upon the side by side configuration. The preheated high boiling petroleum feedstock at about 3. C consisting of long chain hydrocarbon molecules is combined with recycle slurry oil from the bottom of the distillation column and injected into the catalyst riser where it is vaporized and cracked into smaller molecules of vapor by contact and mixing with the very hot powdered catalyst from the regenerator. All of the cracking reactions take place in the catalyst riser within a period of 24 seconds. The hydrocarbon vapors fluidize the powdered catalyst and the mixture of hydrocarbon vapors and catalyst flows upward to enter the reactor at a temperature of about 5. C and a pressure of about 1. The reactor is a vessel in which the cracked product vapors are a separated from the spent catalyst by flowing through a set of two stage cyclones within the reactor and b the spent catalyst flows downward through a steam stripping section to remove any hydrocarbon vapors before the spent catalyst returns to the catalyst regenerator. The flow of spent catalyst to the regenerator is regulated by a slide valve in the spent catalyst line. Since the cracking reactions produce some carbonaceous material referred to as catalyst coke that deposits on the catalyst and very quickly reduces the catalyst reactivity, the catalyst is regenerated by burning off the deposited coke with air blown into the regenerator. The regenerator operates at a temperature of about 7. C and a pressure of about 2. The combustion of the coke is exothermic and it produces a large amount of heat that is partially absorbed by the regenerated catalyst and provides the heat required for the vaporization of the feedstock and the endothermic cracking reactions that take place in the catalyst riser. For that reason, FCC units are often referred to as being heat balanced. The hot catalyst at about 7. C leaving the regenerator flows into a catalyst withdrawal well where any entrained combustion flue gases are allowed to escape and flow back into the upper part to the regenerator. The flow of regenerated catalyst to the feedstock injection point below the catalyst riser is regulated by a slide valve in the regenerated catalyst line. The hot flue gas exits the regenerator after passing through multiple sets of two stage cyclones that remove entrained catalyst from the flue gas. The amount of catalyst circulating between the regenerator and the reactor amounts to about 5 kg per kg of feedstock, which is equivalent to about 4. Thus, an FCC unit processing 7. Figure 1 A schematic flow diagram of a Fluid Catalytic Cracking unit as used in petroleum refineries. Distillation columneditThe reaction product vapors at 5. C and a pressure of 1. FCC end products of cracked petroleum naphtha, fuel oil, and offgas. After further processing for removal of sulfur compounds, the cracked naphtha becomes a high octane component of the refinerys blended gasolines. The main fractionator offgas is sent to what is called a gas recovery unit where it is separated into butanes and butylenes, propane and propylene, and lower molecular weight gases hydrogen, methane, ethylene and ethane. Some FCC gas recovery units may also separate out some of the ethane and ethylene. Although the schematic flow diagram above depicts the main fractionator as having only one sidecut stripper and one fuel oil product, many FCC main fractionators have two sidecut strippers and produce a light fuel oil and a heavy fuel oil. Likewise, many FCC main fractionators produce a light cracked naphtha and a heavy cracked naphtha. The terminology light and heavy in this context refers to the product boiling ranges, with light products having a lower boiling range than heavy products. The bottom product oil from the main fractionator contains residual catalyst particles which were not completely removed by the cyclones in the top of the reactor. For that reason, the bottom product oil is referred to as a slurry oil. Part of that slurry oil is recycled back into the main fractionator above the entry point of the hot reaction product vapors so as to cool and partially condense the reaction product vapors as they enter the main fractionator. The remainder of the slurry oil is pumped through a slurry settler. Ceramics Chemistry Encyclopedia structure, water, uses, elements, examples, metal, number, salt. Photo by Acik. Ceramics can be defined as heat resistant, nonmetallic, inorganic solids. Although different types of ceramics can have very. Most ceramics are also good insulators and can. These properties have led to their use in. The two main categories of ceramics are traditional and advanced. Traditional ceramics include objects made of clay and cements that have. Traditional ceramics are. Advanced. ceramics include carbides, such as silicon carbide, Si. C oxides, such as. Al. nitrides, such as silicon nitride, Si. Advanced ceramics require modern processing. Glass is sometimes considered a type of ceramic. However, glasses and. The structure of glasses is amorphous, like that of liquids. Ceramics. tend to have high, well defined melting points, while glasses tend to. In addition. most ceramics are opaque to visible light, and glasses tend to be. Glass ceramics have a structure that consists of many tiny. This structure gives. In general, glass. Composition. Some ceramics are composed of only two elements. For example, alumina is. Al. zirconia is zirconium oxide, Zr. O. and quartz is. Ceramics are good insulators and can withstand high temperatures. A. popular use of ceramics is in artwork. Si. O. Other ceramic materials, including many minerals, have complex and even. For example, the ceramic mineral feldspar, one of. KAl. Si. The chemical bonds in ceramics can be covalent, ionic, or polar covalent. When the components. Mg. O, and barium titanate, Ba. Ti. O. In ceramics composed of a. BN, and silicon carbide, Si. C. Most ceramics have a highly. For example, magnesium oxide. In this structure, Mg. O. ions along each. Manufacture of Traditional Ceramics. Traditional ceramics are made from natural materials such as clay that. In. fact, the word ceramic comes from the Greek. When artists. make ceramic works of art, they first mold clay, often mixed with other. Special ovens called kilns are used. Clay consists of a large number of very tiny flat plates, stacked together. The water allows the plates to. As a result, clay is easily molded into shapes. High. temperatures drive out water and allow bonds to form between plates. Binders. such as bone. The common clay used to. White ceramics are made from rarer and thus more. The oldest known ceramics made by humans are figurines found in the former. Czechoslovakia that are thought to date from around 2. It was determined that the figurines were made by mixing clay with bone. The manufacture of functional. Greece and Egypt during the period 9. An important advance was the development of white porcelain. Porcelain is. a hard, tough ceramic that is less brittle than the ceramics that preceded. Its strength allows it to be fashioned into beautiful vessels with. It is made from kaolin mixed. C, or 2,3. 72F. Porcelain was developed in China. Tang dynasty and was perfected during the Ming. The porcelain process. Arab world in the ninth century later Arabs brought. Spain, from where the process spread throughout Europe. Bone china has a composition similar to that of porcelain, but at least 5. Elysee Soft Touch Reviews. Like porcelain, bone. Stoneware is a dense, hard, gray or tan ceramic that is less. As a. result, stoneware dishes are usually thicker and heavier than bone china. Manufacture of Advanced Ceramics. The preparation of an advanced ceramic material usually begins with a. Before it is fired, the ceramic body is called green. The. It is then heated to a high temperature until it is. At. this time, individual particles of the original powder fuse together as. During sintering the ceramic may shrink. Because shrinkage is not uniform. Sol gel technology allows better mixing of the ceramic components at the. In the sol gel. process, a solution of an. Typically the solution is a metal alkoxide such as. The sol forms when the. The sol can then be spread into a thin film, precipitated into tiny. The many crosslinks between the formula units result in a ceramic that is. Although the sol gel process is very expensive, it has many advantages. Porous ceramics are made by the sol gel process. These ceramics have. The pore size can be large. Because of the large number of pores, porous. For example, zirconium oxide is a ceramic oxygen sensor that monitors the. Aerogels are solid foams prepared by removing the liquid from the gel. Because. aerogels are good insulators, have very low densities, and do not melt at. Properties and Uses. For centuries ceramics were used by those who had little knowledge of. Today, understanding of the structure and properties of. Most ceramics are hard, chemically. Ceramics also have low densities. These properties make ceramics attractive for many applications. Ceramics. are used as refractories in furnaces and as durable building materials in. They are also used as common electrical and thermal insulators in the. However, ceramics also tend to be brittle. A. major difficulty with the use of ceramics is their tendency to acquire. To. prevent ceramic materials from cracking, they are often applied as. For. example, engine parts are sometimes coated with ceramics to reduce heat. Composite materials that contain ceramic fibers embedded in polymer. They are used in tennis rackets, bicycles, and. Ceramic composites may also be made from two distinct ceramic. Cracks generated in one phase will not be transferred to the. As a result, the. Composite ceramics made from diborides andor carbides of zirconium and. Break resistant cookware with outstanding thermal shock. Although most ceramics are thermal and electrical insulators, some, such. Indium tin oxide is. Some ceramics are semiconductors, with. For. example, silicon carbide, Si. C, is used as a semiconductor material in high. High temperature superconductors are ceramic materials consisting of. That is, they lose all resistance to electrical current. One. example is the material YBa. Some ceramics, such as barium ferrite or nickel zinc ferrites, are. They are made by heating powdered ferrite in. Ceramic magnets are. The properties of piezoelectric ceramics are modified when. For. example, lead zirconium titanate is a piezoelectric ceramic used to. Some ceramics are transparent to light of specific frequencies. These. optical ceramics are used as windows for infrared and ultraviolet sensors. However, optical ceramics are not as widely. An electro optic ceramic such as lead lanthanum zirconate. These electro optic materials are used in color filters. Creatures Labs. Still other ceramics are important in medicine. For example, they are used. The fact that. many ceramics can be easily sterilized and are chemically inert makes. Drugs. and other chemicals can be carried within microsphere pores to desired. Bibliography. Ball, Philip 1. Made to Measure New Materials for the Twenty First Century. Princeton, NJ Princeton University Press. Barsoum, Michael W. Fundamentals of Ceramics. New York Mc. Graw Hill. Brinker, C. Jeffrey, and Scherer, George W. Sol Gel Science The Physics and Chemistry of Sol Gel Processing. Boston Academic Press. Calvert, Paul 2. Advanced Materials. In. The New Chemistry. Nina Hall. New York Cambridge University Press. Kingery, W. D. Bowen, H. K. and Uhlmann, D. R. 1. 97. 6. Introduction to Ceramics. New York Wiley. Richerson, David W. Modern Ceramic Engineering Properties, Processes, and Use in Design. New York Marcel Dekker. Richerson. David W. The Magic of Ceramics. Westerville, OH American Ceramic Society. Shackleford, James F., ed.