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              Structure and working principle of a packed column

              Packed column is to play the role of absorption, it is one of the chemical, petrochemical and refining production in the most important equipment.

              The following talk about the structural characteristics of the packed column:

              Packed tower is tower packings as the gas-liquid contact member between the two phases of mass transfer equipment. The tower is packed column has a vertical cylinder, the bottom with packing support plate, filler huddle or the whole puzzle set in a support plate. Install the packing above the filler plate to avoid being blown updraft. Liquid from the top through the liquid distributor sprayed onto the filler, and flow along the surface of the filler. Gas is fed from the bottom, through the gas distribution system (small diameter column generally no gas distribution device) after the distribution, and continuous countercurrent liquid through the gap filler layer was on the filler surface, in close contact with the two-phase gas-liquid mass transfer . Packed tower belonging continuous contact liquid mass transfer equipment, two phases along the tower height changes continuously under normal operating conditions, the gas phase is a continuous phase, liquid phase to the dispersed phase.

              When the liquid flows downward along the filler layer, there is a gradual trend towards centralized tower wall, making the fluid flow near the wall of the tower increases, a phenomenon known as wall flow. Wall liquid two-phase flow effects caused by the uneven distribution of the filler layer, so that the mass transfer efficiency. Thus, when a high packing layer, the need for segmentation, intermediate redistribution device settings. Liquid redistribution device comprises a liquid collector and liquid redistribution of two parts, a top packing shed liquid after the liquid collector to collect, to liquid redistributors, after redistribution sprayed onto the lower filler.

              Packed tower having large capacity, high separation efficiency, pressure drop, holding a small amount of liquid, operating flexibility and other advantages.

              Packed column, there are some shortcomings, such as packing high cost; when the liquid load is small can not be effectively wetting of the filler surface, so that the mass transfer efficiency is reduced; it can not be directly used for suspended solids or easily polymeric materials; contralateral line feed and the material is not suitable for complex distillation and the like.

              Classification filler

              Many types of fillers, depending on the filling mode can be divided into bulk packing and structured packing.

              1. Bulk Packing

              Bulk Packing is one with a certain geometry and size of granules, generally stacked in a random manner in the tower, also known as random packing or particulate filler. Bulk packing according to different structural characteristics, can be divided into the ring packing, saddles, saddle-shaped packing ring and ball packing. Now introduce some more typical bulk packing:

              Raschig ring Pall ring packing Ladder ring arc saddle saddle saddle packing filler metal ring spherical packing

              (1) Raschig ring packing in 1914 by the Rasi (F.Rashching) invention, the diameter and height equal to the ring. Raschig ring packing gas and liquid distribution is poor, low mass transfer efficiency, resistance, small flux, the current industry has been rarely used.

              (2) Pall rings Raschig rings packing is an improvement on the side wall Raschig rings out two rows of rectangular apertures, the side wall of the ring to be cut still connected with the wall, the other side curved inner ring, formed in extending the blade, all sides of the blade center of the ring with the ride. Pall rings due to the ring wall openings, greatly improving the utilization of space inside the ring and the inner ring surface, air resistance, liquid distribution. Compared with Raschig rings, Pall rings of gas flux increased more than 50%, the mass transfer efficiency of about 30%. Pall ring filler is a wider application.

              (3) ladder ring packing Pall Ring is an improvement compared with the pall ring, ladder ring height is reduced by half and added a taper at one end flange. Because of the high aspect ratio reduced, making the gas filler outer wall around the average path is much shorter, reducing the gas through the packing layer resistance. Conical flange not only increases the mechanical strength of the filler, and so dominated by the line contact between the filler becomes the main point contact, it will not only increase the gap between the filler, the same time as the liquid flows along the surface of the filler dispersed collection point can promote the liquid film surface renewal, in favor mass transfer efficiency. Overall performance is better than Pall ring ring ladder, becoming annular filler currently used in the most excellent kind.

              (4) arc saddle packing a case of saddles, saddle-like shape, usually made of ceramic material. Saddle filler arc is characterized by an open surface all, regardless of internal and external, uniform flow of liquid on both surfaces, surface high utilization, runner curved, small flow resistance. The drawback is prone to intussusception, causing a portion of the filler surface is coincident mass transfer efficiency. Arc saddle filler strength is poor, broken container, much industrial production applications.

              (5) saddle packing will saddle filler arc curved surface at both ends to a rectangular surface and sides vary in size, it becomes saddle packing. Intalox filler accumulation will not intussusception, liquid distribution is more uniform. Saddle packing generally made of ceramic material, its performance is better than Raschig rings. Currently, the vast majority of applications domestic porcelain Raschig rings occasions, have been replaced by ceramic saddle packing.

              (6) metal ring saddle packing ring saddle packing (abroad called Intalox) are both ring and saddle structural characteristics of the design of a new type of filler, which is generally made of metal material, it is also referred to as metal ring Intalox filler. Ring saddle packing filler both advantages and saddle ring packing set in one, its overall performance is better than pall ring and stepped ring, in bulk packing in more applications.

              (7) general spherical packing plastic injection molded, and its structure has a variety. Spherical filler is characterized as a hollow sphere, can allow gas and liquid from the inside through. Because even symmetry, filler loading density spherical structure, easy to produce holes and bridges, so good liquid dispersion properties. Spherical packing generally apply only to certain situations, the application of less engineering.

              In addition to the several more typical bulk filler, in recent years there have been a unique new packing configuration developed, such as conjugated ring packing, Haier ring packing, Nat ring packing. Characteristics of the industry commonly used bulk packing several documented manual.

              2. Structured Packing

              Structured packing is a certain geometry arranged neatly dumped packing. Many different types of structured packing, according to its geometry can be divided into a grid packing, packing, packing and other pulses.

              (1) grill packing unit body composition is strip made by certain rules, with a variety of structural forms. The first application for the wood grill grill packing packing industry. There are currently more general Geli Qi grill packing, packing mesh grille, honeycomb grille filler, of which the most representative Geli Qi grill packing.

              Lower than the surface area of the grill packing, primarily for applications requiring low pressure drop, load large and blockades and other occasions.

              (2) the application of the packing industry is currently structured packing when assembled with the vast majority of packing, which is disc-shaped filler composed of many corrugated sheet, corrugated and column axis inclination has 30 ° and 45 ° are two, two adjacent corrugated plates stacked against reverse. Each dish filler mounted perpendicular to the tower, between two adjacent disc packing 90 ° staggered arrangement.

              Packing according to the structure can be divided into net corrugated board packing and packing into two categories, the material but also metals, plastics and ceramics, etc. points.

              Metal gauze packing is the main form of net packing, which is made of a metal mesh. Metal gauze packing pressure to reduce high separation efficiency, especially for sophisticated distillation and vacuum distillation unit, difficult isolate system, heat-sensitive materials rectification system provides an effective means. Despite its high cost, but because of its excellent performance it is still widely used.

              Metal plate packing is a major form of corrugated board packing. Corrugated sheet of the filler has many f5mm about punching holes, can play rough liquid distribution plate on strengthening the role of the lateral mixing. Rolling corrugated board sheet into small grooves, can play a fine distribution of liquid on the plate, enhancing the role of surface wetting properties. High strength metal plate packing, corrosion resistance, especially for larger diameter columns and a large gas-liquid load applications.

              Metal rolling corrugated plate packing is another typical plate packing. The main difference between it and the metal plate corrugated packing sheet surface is not punched holes, but a puncture, with jarring manner to the sheet rolling out very dense pore size of 0.4 ~ 0.5mm small puncture. Its separation capability similar to net packing, but the anti-blocking ability than the net packing, and cheap, is widely used.

              Advantages packing is compact, small resistance, high mass transfer efficiency, large capacity, large surface area (such as several commonly used 125,150,250,350,500,700). Packing drawback is not suitable for handling high viscosity, easy polymerization or suspension of the material, and loading and unloading, cleaning difficulties and high cost.

              (3) Pulse filler is hollow prismatic individual by the band constriction, assembled from a certain way of a structured packing. Pulse filler assembly, will form a porous prismatic channel with the constriction of the longitudinal passage in alternating contraction and expansion of a strong turbulent gas-liquid two-phase through. In constriction segment, the highest gas velocity, turbulent violent, thereby strengthening the mass transfer. Expanding segment, the gas velocity is minimized, to achieve the separation of the two phases. Runner shrink, expand the alternately repeated to achieve a "pulse" mass transfer process.

              Pulse filler is characterized by large capacity, low pressure drop, is the ideal filler vacuum distillation. Liquid distribution because of its excellent performance makes the amplification effect reduction, it is particularly suitable for large column diameter occasions.


              Packing types and classification

              Many types of fillers, aluminum powder, zinc powder, silver powder and other metal powder may be used as the conductive filler. Cement, fly ash, etc. can be used as fillers. Wood flour, starch and other plant powder can be used as a filler. A small amount of calcium fluoride can be used in polyurethane adhesive and sealant systems; both carbon dioxide absorbing effect.


              In general, a fine powder filler or modified fine filler, and a fibrous, platy fillers, the use of a small amount can improve its overall performance, e.g., of an elastomeric polymer (e.g. rubber, polyurethane elastomer _) have a reinforcement effect, increase the modulus, strength, wear resistance, heat resistance, improved dimensional stability, for hard products can suitably improve strength, resistance to aging. However, excessive use of such material is reduced, and the operation difficulty filler content is large. Fillers are the following: Depending on the filling mode can be divided into bulk packing and structured packing. Bulk Packing is one with a certain geometry and size of granules, generally stacked in a random manner in the tower, also known as random packing or particulate filler.


              High temperature refractory material with nano-alumina

              Nano composite corundum brick and magnesia-chrome brick

              The use of certain mixing process, add a small amount of nano-powder to the batch composition system. Such as adding a few ingredients corundum brick nano-alumina (VK-L30N) and nano-silica (VK-SP30), adding nano ferric oxide in magnesite-chrome brick ingredients, can significantly improve the sample mechanical properties.

              Nano-silica (VK-SP30) composite corundum brick bending strength and compressive strength of the experimental test results show. Nano-silica is added, can greatly improve the mechanical properties of the sample, especially when adding an appropriate amount of 1% to 2% by firing sample 1450,1550 ℃, its strength and not relative Jia Nami material ratio increased by 1.5 to 2.0 times, such as the non-nano-powder sample and the sample was added 2% nano-silica (VK-SP30) when compared to the compressive strength, respectively, from 15.8, 60.5MPa rose to 170.4, 179.6MPa.

              After 1700 ℃ & times; specimen fracture SEM photograph 3h after treatment, it can be seen, after the MgO-Cr2O3 refractories added iron oxide nanoparticles microstructure changed greatly.

              2, nanocomposites Al2O3-SiC-C <b> castable

              Al2O3-SiC-C castable because of its excellent performance has been stable in the hook, the wide range of applications. To further enhance the Al2O3-SiC-C castable high temperature performance, especially high temperature mechanical strength, with a silica-alumina gel powder substitute the most calcium aluminate cement binder, its introduction could significantly reduce Sialon generation temperature, and to promote the & beta; -Sialon generating phase. Thus, nano Al2O3-SiO2 gel powder composite Al2O3-SiC-C castable with high temperature flexural strength (1400 ℃ & times; 0.5h).

              After adding the gel powder, nano-composite Al2O3-SiC-C castable Sialon generation temperature decreases, the temperature 1100 ℃ has been found that & beta; -Sialon, and the use of cement bound Al2O3-SiC-C castable at 1100 ℃ only Si2N2O phase transition occurs.

              Such nanocomposite Al2O3-SiC-C castable has been completed in a domestic steel mill blast furnace No.2 Industrial Test (1536m3) main grooves (including sand port) on. Without the one-time repair through iron reached 15.79t, than similar non-nanocomposite Al2O3-SiC-C castable 12t level, is currently promoting the application on other domestic ironworks blast ditch.

              Quality sizing mouth expanding decide billet casting of life fast rate. Analysis showed that the main reason for expanding product strength is low, large pores, thus reducing the use of nanotechnology ZrO2 quality sizing nozzle pores, it is expected to improve its performance.

              Nano zirconia (VK-R30Y3) ZrO2 composite of sizing nozzle body, through 1500 ℃ & times; and ZrO2 nanocomposite before sizing nozzle through 1800 ℃ & times 6h after firing; bulk density and 6h after firing same porosity and nano-composite samples were 800 ℃ & times; 6h after firing, which apparent porosity from 19% to 11%. Pore size and pore volume were smaller, mostly in 10nm. Visible, nano zirconia (VK-R30Y3) filled mainly plays the role in filling the pores and lead to sintering.

              Sintering mechanism refractories for evaporation - condensation process, as Cr2O3 at a high temperature sintering conditions exist easily evaporates and high evaporation rate, so the general magnesia chromite refractories showed that there were high porosity, large pore volume density low defects, thus affecting the performance of the anti-slag erosion.

              Nanotechnology beneficial to reduce the apparent porosity of magnesia chromite refractories and enhance its bulk density, which is expected to improve slag resistance of the treated magnesium chrome brick. From the microscopic structure, no matter how much temperature processing classics, with around the hole after MgO-Cr2O3 sol treatments were formed a dense MgO-Cr2O3 quality deposits.

              4, nano-coated graphite oxide film

              Carbon steel with easy to be moist and slag and high thermal performance characteristics, added to the oxide-based castable its performance can be greatly improved, therefore, the current carbon-castable research and development have been refractories industry has become a hot topic. Since water does not wet graphite surface, so that graphite is difficult to break down in castable, castable affect liquidity, which has become the most important issue impede the further development of the carbonaceous material and casting applications.

              For the graphite surface modification, through a variety of inorganic salt hydrolysis in natural flake graphite coated nano-oxide film.

              Various film-coated graphite oxide nano after 500 ℃ treatment, the surface coated with amorphous oxides are way exists, coated on the surface of graphite and graphite oxide formed COM (M represents a metal) bond with characteristic chemical adsorption. After the coated graphite oxide nano particle shape changes, the average particle size increases, increasing the surface fractal dimension.

              Nano-oxide coated graphite wetting angle with water relative to untreated graphite are greatly reduced, aluminum oxide coated graphite exhibit more excellent hydrophilic, high dispersion stabilizing performance.

              In addition, the oxidation reaction nano-coated aluminum oxide (VK-L30N) of graphite apparent activity can improve the antioxidant capacity enhancement. Graphite coated titanium dioxide oxidation resistance no big improvement, reduced antioxidant capacity of nano-coated zirconium dioxide and chromium oxide of graphite, which is zirconium dioxide and chromium oxide on carbon - oxygen reaction catalysis Caused.

              Nanotechnology can be better prepared performance refractories. Nano powder does refractories have significantly improved the performance of the role.


              Alumina industry definitions and usage analysis

              With the rapid development of China's electrolytic aluminum, ceramics, pharmaceuticals, electronics, machinery and other industries, the market demand for aluminum is still a large room for growth, alumina production will continue to grow. China reported hall below alumina industry consolidation definitions and usage analysis.

              Definition of alumina

              Alumina (Al2O3), industrial Al2O3 by bauxite (Al2O3?3H2O) and diaspore prepared for the high purity requirements of Al2O3, usually with chemical method.

              There are many allomorphs Al2O3, there are more than 10 kinds of currently known, there are three kinds of crystal, namely γ-Al2O3, β-Al2O3, α-Al2O3. Wherein the structures of different nature or different, at a high temperature above 1300 ℃ almost complete conversion of α-Al2O3.

              The use of alumina

              Ruby, sapphire main ingredients are all aluminum, as other impurities present different color, sapphire is iron oxide and titanium oxide and blue.

              ⒉ main ingredient in aluminum ore bauxite, and alumina highest. Industrially, bauxite purified via Bayer process alumina, and then change the Hall-Heroult process for the aluminum metal.

              ⒊ aluminum to react with oxygen in the air, generating a dense aluminum oxide film covering in aluminum surface exposed to air.

              ⒋ aluminum is a good conductor of electricity and heat. Crystal form of alumina because of the high hardness, suitable as abrasive and cutting tools.

              ⒌ alumina powder commonly pornographic layer analysis of vehicle.

              ⒍ 2004 August serving in the US company 3M scientists developed a synthesis of aluminum and rare earth element alloy called transparent alumina to produce tempered glass.

              For more information, please consult the alumina industry analysis report hall China "issued 2014--2018 China's aluminum industry market research and investment outlook report."

              Ceramic role

              Calcined alumina and alumina into general industrial alumina, calcined alumina is an essential raw material production of antique brick, but can be used for the production of industrial alumina ceramic stone, in traditional glaze, the alumina used as whitening. Because of antique brick and ceramic stone favored by the market, the amount of alumina is growing year by year.

              Therefore, alumina ceramic emerged in the ceramic industry - alumina ceramic is a kind of Al?O? as the main raw material, alumina-based polycrystalline ceramic material phase. Because of its high mechanical strength, hardness, high frequency dielectric low loss, high temperature, high insulation resistance, chemical resistance and good thermal conductivity and other excellent comprehensive technical performance and other advantages.


              The use of activated alumina ball have?

              The main purpose of active alumina ball are


              In the petrochemical, fertilizer industry, can be widely used in catalysts, catalyst supports. Activated Alumina ball and has a strong adsorption characteristics, and thus acts as a desiccant of gas and liquid, gas purification adsorbents, drinking water fluoride removal agent, industrial effluent color and odor elimination of agents. Activated alumina ball with a home fluorine cylinder supporting the use of drinking water is the ideal home fluoride devices. The fluoride removal filter also with waterworks fluoride device or devices supporting the use of fluoride for industrial use, the better. Household fluoride fluoride removal filter device activation: Configure aluminum sulfate solution (3 liters of water, 0.3kg of solid aluminum sulfate), alumina fluoride removal filter into the solution, soak for 5-10 hours was discarded immersion (dipping To properly mixed), then washed with water 3-5 times, each time for about two liters of water, or adjust PH reproduction method, PH value control in 7.5. Activated alumina fluoride removal filter can be used continuously for 6--8 years, when the surface appears brown when fluoride removal effect will be significantly reduced, due to impurities in the water pollution in this system, it is best to use three percent every six months once treated with dilute hydrochloric acid , its operation in the same manner with the regeneration method.


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