Date : Replies: 17/07/2017 Q: What is the effect of reducing the system pressure in a gas oil/naphtha hydrotreater? Will this be able to reduce the hydrogen. To the point answers to common automotive question and links to more detailed information. Web. Corr Corrosion Consulting Services, Corrosion Short Courses, Corrosion Expert Witness, Corrosion Consultancy, Corrosion Analysis. Copyright . All rights reserved. Oil demulsification - Demulsification is the breaking of a crude oil emulsion into oil and water phases. From a process point of view, the oil producer is interested in three aspects of demulsification. Rate or the speed at which this separation takes place. Amount of water left in the crude oil after separation. Quality of separated water for disposal. A fast rate of separation, a low value of residual water in the crude oil, and a low value of oil in the disposal water are obviously desirable. What Is Biodiesel? Biodiesel is an alternative fuel similar to conventional or . Biodiesel can be produced from straight vegetable oil, animal oil. About this Wiki. The E46 Wiki should be used as a tool to help all E46 owners. The greatest feature of the Wiki is that anyone with an account on Bimmerfest has the. How Catalytic Converters Reduce Pollution - Catalysts are substances that cause or accelerate chemical reactions. Learn about catalysts and find out how catalysts are. Produced oil generally has to meet company and pipeline specifications. For example, the oil shipped from wet- crude handling facilities must not contain more than 0. BS& W) and 1. This standard depends on company and pipeline specifications. The salt is insoluble in oil and associated with residual water in the treated crude. Low BS& W and salt content is required to reduce corrosion and deposition of salts. The primary concern in refineries is to remove inorganic salts from the crude oil before they cause corrosion or other detrimental effects in refinery equipment. The salts are removed by washing or desalting the crude oil with relatively fresh water. This stability arises from the formation of interfacial films that encapsulate the water droplets. To separate this emulsion into oil and water, the interfacial film must be destroyed and the droplets made to coalesce. Therefore, destabilizing or breaking emulsions is linked directly to the removal of this interfacial film. Factors that affect the interfacial film are discussed in Stability of oil emulsions. The factors that enhance or speed up emulsion breaking are discussed here. An increase in temperature has the following effects. An economic analysis should be performed that takes into consideration factors such as. Heating costs. Reduced treating time. Residual water in the crude. An increase in temperature also can be achieved by burying crude- oil pipelines or by insulating them. These factors should be evaluated carefully during development, especially at facilities where emulsion problems are anticipated. Very high shear is detrimental and should be avoided. High shear causes violent mixing of oil and water and leads to smaller droplet sizes. Smaller droplets are relatively more stable than larger droplets; therefore, measures that increase shearing of the crude oil should be avoided or minimized where possible. Such measurees include. Mechanical chokes. Valves. Flow obstructions. Pressure drops. However, a certain amount of shear is required for mixing the chemical demulsifier into the bulk of the emulsion. This typically is between 1. An increase in residence time increases the separation efficiency and reduces the residual amount of water in the crude. Increasing residence time, however, comes at the expense of high separator- equipment costs. Removing the solids or their source is sometimes all that is required for eliminating or reducing the emulsion problem. Oil- wet solids stabilize water- in- oil emulsions. Water- wet solids can also be made oil- wet with a coating of heavy polar materials and can participate effectively in the stabilization of water- in- oil emulsions. The solids can be removed by dispersing them into the oil or can be water- wetted and removed with the water. Some of the ways to control emulsifiers include the following processes. The chemicals include, for example, acids and additives during acidization, corrosion inhibitors for corrosion protection, surfactants and dispersants for organic- and inorganic- deposition control, and polymers and blocking agents for water- production control. Laboratory compatibility testing of these chemicals should be conducted before field injection to avoid tight emulsions. Avoiding incompatible crude- oil blends. A crude- oil blend is incompatible if it results in the precipitation of solids (organic and inorganic). The word petroleum comes from Greek: . The term was found (in the spelling. All different types of corrosion: pitting, galvanic corrosion, crevice corrosion, filiform corrosion, stress corrosion cracking, SCC, MIC corrosion, graphitic. This occurs, for example, when an asphaltic crude oil is mixed with a paraffinic crude oil, resulting in the precipitation of asphaltenes. Again, laboratory testing can identify incompatible crudes. Use of dispersants for controlling the precipitation of asphaltenes and the use of pour- point depressants for controlling waxes. Alternatively, emulsion stability can be controlled by raising the temperature of the crude above its cloud point. Neutralizing the effect of stabilizing film encapsulating the water droplets by demulsifiers. These chemicals promote coalescence of water droplets and accelerate water separation. Retrofitting. Additional water separation can be achieved by retrofitting the existing equipment. Invariably, emulsion problems increase after the separation equipment has been installed because of field aging, increased watercuts, improper design, or several other reasons. Additional equipment (for example, free- water knockout drums and heater treaters) can be installed to assist in the breaking of oilfield emulsions. Internals can also be installed or retrofitted in production- separation traps. The most common retrofitting is the installation of a coalescer section that assists in coalescing water droplets. There are several options available, and re- engineering is generally required on a case- by- case basis. Emulsion treating provides further information. The first step is flocculation (aggregation, agglomeration, or coagulation). The second step is coalescence. Either of these steps can be the rate- determining step in emulsion breaking. During flocculation, the droplets clump together, forming aggregates or . Coalescence at this stage only takes place if the emulsifier film surrounding the water droplets is very weak. The rate of flocculation depends on the following factors. The rate of flocculation is higher when the water cut is higher. Temperature of the emulsion is high. Temperature increases the thermal energy of the droplets and increases their collision probability, thus leading to flocculation. Viscosity of the oil is low, which reduces the settling time and increases the flocculation rate. Density difference between oil and water is high, which increases the sedimentation rate. An electrostatic field is applied. This increases the movement of droplets toward the electrodes, where they aggregate. Coalescence. Coalescence is the second step in demulsification. During coalescence, water droplets fuse or coalesce together to form a larger drop. This is an irreversible process that leads to a decrease in the number of water droplets and eventually to complete demulsification. Coalescence is enhanced by the following factors. The system tries to reduce its interfacial free energy by coalescing. High water cut increases the frequency of collisions between droplets. Low interfacial viscosity enhances film drainage and drop coalescence. Chemical demulsifiers convert solid films to mobile soap films that are weak and can be ruptured easily, which promotes coalescence. High temperatures reduce the oil and interfacial viscosities and increase the droplet collision frequency. Sedimentation or creaming. Sedimentation is the process in which water droplets settle down in an emulsion because of their higher density. Its inverse process, creaming, is the rising of oil droplets in the water phase. Sedimentation and creaming are driven by the density difference between oil and water and may not result in the breaking of an emulsion. Unresolved emulsion droplets accumulate at the oil/water interface in surface equipment and form an emulsion pad or rag layer. A pad in surface equipment causes several problems including the following. Emulsion separation into oil and water requires the destabilization of emulsifying films around water droplets. This process is accomplished by any, or a combination, of the following methods. Adding chemical demulsifiers. Increasing the temperature of the emulsion. Applying electrostatic fields that promote coalescence. Reducing the flow velocity that allows gravitational separation of oil, water, and gas. This is generally accomplished in large- volume separators and desalters. Demulsification methods are application specific because of the wide variety of crude oils, brines, separation equipment, chemical demulsifiers, and product specifications. Furthermore, emulsions and conditions change over time, which adds to the complexity of the treatment. The most common method of emulsion treatment is the application of heat and an appropriate chemical demulsifier to promote destabilization, followed by a settling time with electrostatic grids to promote gravitational separation. Increased temperatures also result in the destabilization of the rigid films because of reduced interfacial viscosity. Furthermore, the coalescence frequency of water droplets is increased because of the higher thermal energy of the droplets. See Heating oil emulsions for more information. Heat accelerates emulsion breaking; however, it very rarely resolves the emulsion problem alone. Increasing the temperature has some negative effects. The cost- effectiveness of adding heat should be balanced against. Longer treatment time (larger separator)Loss of light ends and a resultant lower oil- product price. Chemical costs. The costs of electrostatic grid installation or retrofitting. See also Economics of treating emulsions. Some of the associated gases may be separated in these drums. Free- water knockout drums are supplementary equipment that aid in the treatment of produced crude oil emulsions. These separators can be either horizontal or vertical in configuration. Each separator is sized with a set retention time to provide adequate separation at a given throughput rate. The separator may include. Heater section. Wash water. Filter section. Coalescing or stabilizing section. Electrostatic grids. Fig. 1 shows a typical three- phase separator. For example, a separator may have a large heater section or may have no coalescer packing. Selecting the right separator for any given set of conditions is a complex engineering task that depends on several factors.
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