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Structure and working principle of reactor (reaction kettle) _


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Original title: Structure and working principle of reactor (reaction kettle) Source: Coal Chemical Knowledge Base The reactor is a device for realizing a reaction process, and is used for realizing a liquid-phase single-phase reaction process and a liquid-liquid, gas-liquid, liquid-solid, gas-liquid-solid and other multiphase reaction processes. Stirring devices (mechanical stirring, airflow stirring, etc.) Are often installed in the device. When the ratio of height to diameter is large, multiple layers of stirring blades can be used. When the materials need to be heated or cooled in the reaction process, a jacket can be arranged on the wall of the reactor, or a heat exchange surface can be arranged in the reactor, or heat exchange can be carried out through external circulation. By mode of operation 1. Batch reactor or batch reactor Flexible operation, easy to adapt to different operating conditions and product varieties, and suitable for the production of products with small batch, multiple varieties and longer reaction time. The disadvantages of the batch reactor are that it needs auxiliary operations such as charging and discharging, and the product quality is not easy to be stable. However, some reaction processes, such as some fermentation reactions and polymerization reactions, are still difficult to achieve continuous production, and batch reactors are still used so far. The intermittent operation reactor is characterized in that the raw materials are added into the reactor at one time according to a certain proportion, and the materials are discharged at one time after the reaction reaches a certain requirement. A continuously operate reactor is one in which that raw materials are continuously char and the reaction products are continuously discharged. When the operation reaches a steady state, the material composition, temperature and other state parameters at any position in the reactor do not change with time. A semi-continuously operate reactor, also known as a semi-batch operated reactor, is somewhere in between, usually with a one-time addition of one reactant follow by a continuous addition of that other reactant. After the reaction reaches a certain requirement, the operation is stopped and the material is discharged. The advantage of batch reactor is that the equipment is simple, and the same equipment can be used to produce a variety of products, especially suitable for small batch and multi-variety production in pharmaceutical, dye and other industrial sectors. In addition, there is no backmixing in the batch reactor, which is beneficial to most reactions. The disadvantage is that it needs auxiliary processes such as loading and unloading, cleaning and so on, and the product quality is not easy to stabilize. 2. Continuous kettle reactor, or continuous kettle The disadvantages of the batch reactor can be avoided, but the stirring action will cause the backmixing of the fluid in the reactor. When the stirring is intense, the liquid viscosity is low or the average residence time is long, the material flow pattern in the kettle can be regarded as a complete mixing flow, and the reaction kettle is correspondingly called a complete mixing kettle. The backmixing phenomenon in the tank reactor is a disadvantageous factor when high conversion is required or when there are side reactions in series. In this case, a reactor with multiple reactors in series can be used to reduce the adverse effects of backmixing, and the reaction conditions can be controlled by separate reactors. Continuous reactors should be used as much as possible for large-scale production. The continuous reactor has the advantages of stable product quality and easy operation and control. Its disadvantage is that there are different degrees of backmixing in continuous reactors, which is unfavorable to most reactions and should be suppressed by reasonable reactor selection and structural design. By structure 1. Tubular reactor Consists of a hollow tube or a filled tube with a large length-diameter ratio, and can be used for realizing a gas-phase reaction and a liquid-phase reaction. Expand the full text Performance characteristics: 1. Since the residence time of the reactant molecules in the reactor is equal, the reactant concentration and chemical reaction rate at any point in the reactor do not change with time, but only with the length of the tube. 2. Tubular reactor has small volume,decarboxylation after extraction, large specific surface and large heat transfer area per unit volume, which is especially suitable for reactions with large thermal effect. 3. Because the reaction speed and flow rate of the reactants in the tubular reactor are fast, its production capacity is high. And 4, the tubular reactor is suitable for large-scale and continuous chemical production. 5. Compared with the tank reactor, the backmixing is smaller, and the flow pattern of the fluid in the tube is close to the ideal fluid under the condition of lower flow rate. 6. Tubular reactor is suitable for both liquid phase reaction and gas phase reaction. Are particularly suitable for pressurize reactions. In addition, the tubular reactor can realize sectional temperature control. Its main disadvantage is that when the reaction rate is very low, the required pipeline is too long, which is not easy to realize in industry. Horizontal tubular reactor 1 Vertical tubular reactor 2 The vertical tube reactor is used in liquid phase ammoniation reaction, liquid phase hydrogenation reaction, liquid phase oxidation reaction and other processes. Coil reactor 3 The tubular reactor is made into the form of a coil pipe, so that the equipment is compact and the space is saved. However, it is difficult to overhaul and clean the pipeline. U-shape tubular reactor 4 A porous baffle or a stirring device is arranged in the tube of the U-shaped tubular reactor to strengthen the heat transfer and mass transfer process. The diameter of the U-tube is large, and the residence time of the material is increased, so that the U-tube can be applied to a reaction with a slow reaction rate. Multi-tube parallel tubular reactor 5 Tubular reactors with multiple tubes in parallel are generally used for gas-solid phase reactions, for example,wiped film evaporator, gas-phase hydrogen chloride and acetylene react in a reactor with multiple tubes in parallel filled with a solid phase catalyst to produce vinyl chloride, and gas-phase nitrogen and hydrogen mixture is used to synthesize ammonia in a reactor with multiple tubes connected in parallel filled with a solid phase iron catalyst. II. Kettle-type reactor It is composed of a cylindrical container with a small ratio of length to diameter, usually equipped with a mechanical or pneumatic stirring device, and can be used in liquid-phase single-phase reaction process and liquid-liquid phase, gas-liquid phase, gas-liquid solid phase and other multiphase reaction processes. Performance characteristics: The kettle type reactor has the characteristics of wide applicable temperature and pressure range, strong adaptability, large operation flexibility, easy control of temperature and concentration during continuous operation, uniform product quality and the like. But require a larger volume when use in higher conversion process requirements. It is usually operated under mild operating conditions, such as normal pressure, low temperature and below the boiling point of the material, and this kind of reactor is most commonly used. Batch Kettle 1 Batch reactor, or batch kettle. Flexible operation, easy to adapt to different operating conditions and product varieties, and suitable for the production of products with small batch, multiple varieties and longer reaction time. The disadvantages of the batch reactor are that auxiliary operations such as charging and discharging are required, and the product quality is not easy to stabilize. However, some reaction processes, such as some fermentation reactions and polymerization reactions, are still difficult to achieve continuous production, and batch reactors are still used so far. Continuous kettle 2 Continuous kettle reactor, or continuous kettle Stirred tank reactor 3 Stirred tank reactor has vertical vessel central stirring, eccentric stirring, inclined stirring, horizontal vessel stirring and other types. Among them, the stirred tank reactor centered in a vertical vessel is the most typical one. Multi-stage series reaction kettle 4 III. Tower Reactor Tower equipment for realizing gas-liquid phase or liquid-liquid phase reaction process, including packed tower, plate tower, bubble tower, jacketed glass reactor ,wiped film distillation, etc. Bubble column reactor 1 Bubble column reactor is widely used in medium-speed, slow-speed reactions and reactions with large heat release, in which liquid phase also participates in the reaction. For example, the oxidation reaction of various organic compounds, the chlorination reaction of various paraffins and aromatic hydrocarbons, various biochemical reactions, aeration oxidation of sewage treatment and carbonization of ammonia water to produce solid ammonium bicarbonate all use this bubble column reactor. Packed column reactor 2 Packed column is a kind of mass transfer equipment in which the packing in the column is used as the contact member between gas and liquid. The liquid is sprayed onto the packing from the top of the tower through the liquid distributor and flows down along the surface of the packing. The gas is sent from the bottom of the tower, and after being distributed by the gas distribution device (the small-diameter tower is generally not provided with a gas distribution device), it continuously passes through the gap of the packing layer in countercurrent with the liquid. On the surface of the packing, the gas and liquid are in close contact for mass transfer. The packed column is a continuous contact gas-liquid mass transfer equipment, and the composition of the two phases changes continuously along the height of the column. Under normal operating conditions, the gas phase is the continuous phase, and the liquid phase is the dispersed phase. Plate column reactor 3 The liquid of the tray column reactor is a continuous phase and the gas is a dispersed phase, and a chemical reaction is carried out by contacting the liquid phase on the tray by dispersing the gas phase into small bubbles through the tray. The plate column reactor is suitable for fast and medium speed reactions. The use of multiple plates minimizes axial back mixing and allows operation at very small liquid flow rates, enabling very high liquid phase conversions to be achieved directly in a single column. At the same time, the gas-liquid mass transfer coefficient of plate column reactor is large, so cooling or heating elements can be installed on the plate to meet the requirements of maintaining the required temperature. However, the plate column reactor has the disadvantages of large pressure drop and small mass transfer surface. Spray tower reactor 4 The structure of the spray tower reactor is relatively simple, the liquid is dispersed in the gas in the form of fine droplets, the gas is a continuous phase, and the liquid is a dispersed phase, so the spray tower reactor has the advantages of large phase contact area, small gas phase pressure drop and the like. It is suitable for instantaneous, interfacial, and rapid reactions, as well as reactions that produce solids. Spray column reactor has the disadvantages of small liquid holdup, too small mass transfer coefficient on the liquid side and serious backmixing of gas and liquid phase. IV. Fixed bed reactor Also known as packed bed reactor, it is a kind of reactor filled with solid catalyst or solid reactant to realize heterogeneous reaction process. The solids are usually granular, with a particle size of about 2 to 15 mm, and are packed into a bed of a certain height (or thickness). The bed is stationary and the fluid passes through the bed to react. It differs from fluidized bed reactors and moving bed reactors in that the solid particles are at rest. Fixed-bed reactors are mainly used to realize gas-solid catalytic reactions, such as ammonia synthesis tower, sulfur dioxide catalytic oxidizer, hydrocarbon steam reformer, etc. When used for gas-solid or liquid-solid non-catalytic reactions, the bed is filled with solid reactants. Trickle bed reactors can also be classified as fixed bed reactors, in which the gas and liquid phases flow downward through the bed layer in a gas-liquid solid phase contact manner. Axially adiabatic fixed bed reactor 1 The fluid flows through the bed layer from top to bottom along the axial direction, and the bed layer has no heat exchange with the outside. Adiabatic fixed bed reactor 2 Its structure is simple, the catalyst is uniformly stacked in the bed, there is no heat exchanger in the bed, and the reaction material preheated to a certain temperature flows through the bed layer for reaction. Radial adiabatic fixed bed reactor 3 The fluid flows through the bed layer along the radial direction, the centrifugal flow or the centripetal flow can be adopted, and the bed layer has no heat exchange with the outside. Compared with the axial reactor, the radial reactor has shorter fluid flow distance, larger flow channel cross-sectional area and smaller fluid pressure drop. However, the structure of radial reactor is more complex than that of axial reactor. The above two types are adiabatic reactors, which are suitable for the situation where the reaction heat effect is not large, or the reaction system can withstand the temperature change caused by the reaction heat effect under adiabatic conditions. Tubular fixed bed reactor 4 Is formed by connecting a plurality of reaction tubes in parallel. The catalyst is placed in the tube or between the tubes, and the heat carrier flows through the tube or between the tubes for heating or cooling. The tube diameter is usually between 25 and 50 mm, and the number of tubes can be up to tens of thousands. The tubular fixed bed reactor is suitable for the reaction with large reaction heat effect. In addition, there is a reactor composed of the above basic forms in series, which is called a multi-stage fixed-bed reactor. For example, when the reaction heat effect is large or the temperature needs to be controlled in sections, a plurality of adiabatic reactors can be connected in series to form a multi-stage adiabatic fixed bed reactor, and a heat exchanger is arranged between the reactors or materials are supplemented to adjust the temperature so as to operate under the condition close to the optimal temperature. Multistage adiabatic fixed bed reactor 5 5. Fluidized bed reactor Fluidized bed reactor is a kind of reactor which uses gas or liquid to pass through the granular solid layer to make the solid particles in suspension motion state and carry out gas-solid phase reaction process or liquid-solid phase reaction process. When used in gas-solid systems, it is also called ebullated bed reactor. The early application of fluidized bed reactor in modern industry is the Winkler furnace (see coal gasifier) for pulverized coal gasification, which appeared in the 1920s; however, the development of modern fluidized reaction technology is represented by the petroleum catalytic cracking in the 1940s. At present, fluidized bed reactors have been widely used in chemical, petroleum, metallurgy, nuclear industry and other sectors. The advantages are: 1, the continuous input and output of solid materials can be realized; 2, the motion of the fluid and the particles ensures that the bed layer has good heat transfer performance, the internal temperature of the bed layer is uniform and is easy to control, and the method is particularly suitable for strong exothermic reactions; 3. It is convenient for the continuous regeneration and circulation operation of the catalyst, and is suitable for the process with high catalyst deactivation rate. The rapid development of catalytic fluidized bed cracking of petroleum fractions is a typical example in this respect. Bed type of fluidized bed reactor 1 Large Bubbles and Swellings in Fluidized Beds of Gas-Solid System VI. Moving bed reactor The reactor with solid particles is similar to the fixed bed reactor, but the difference is that the solid particles are continuously added from the top of the reactor, move from top to bottom, and discharged from the bottom. It is suitable for the catalytic reaction process and solid-phase processing reaction in which the catalyst needs to be regenerated continuously. Lurgi furnace At the beginning of the development of iron and steel industry and city gas industry, moving bed reactors have been used for coal gasification. The moving bed pressurized gasifier (Lurgi gasifier), which was successfully developed in 1934, is still the largest coal gasification plant, with a daily production capacity of more than 1 Mm. In the early stage of the development of petroleum catalytic cracking, moving bed reactors were used, but now they have been replaced by fluidized bed reactors and riser reactors. At present, the important chemical production processes using moving-bed reactors include catalytic reaction processes such as continuous reforming and xylene isomerization, and continuous ion exchange water treatment processes. Process flow diagram of three-tower moving bed Moving bed reaction process flow Pay attention to our energy-saving internal reference public micro-signal: jnnc01 We insist on original depth or selected every article, welcome to pay attention and share. If you need to reprint, please be sure to indicate the source, and retain the words "energy-saving internal reference" and two-dimensional code. I also hope to know more like-minded friends through this platform, communicate with each other, learn from each other, make progress together, and make a contribution to the cause of green environmental protection! (Disclaimer: This article only represents the views of the author, and does not represent the position of this public account. In case of intellectual property disputes, contributions and cooperation matters, please contact) Pay attention to our energy-saving internal reference public micro-signal: jnnc01 We insist on original depth or selected every article, welcome to pay attention and share. If you need to reprint, please be sure to indicate the source, and retain the words "energy-saving internal reference" and two-dimensional code. I also hope to know more like-minded friends through this platform, communicate with each other, learn from each other, make progress together, and make a contribution to the cause of green environmental protection! (Disclaimer: This article only represents the views of the author,nutsche filter dryer, and does not represent the position of this public account. If there are intellectual property disputes, contributions and cooperation matters, please contact) Return to Sohu to see more Responsible Editor:. toptiontech.com

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