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pm | The structure and (12th Dec 22 at 1:15am UTC)
The structure and | | Original title: Structures and principles of 27 reactors (with pictures and texts), all you want to know is here. Introduction Chemical reactor is the core equipment of chemical production, and its advanced technology has an important impact on chemical production, which directly affects the investment scale and production cost of the device. It is also the heart of the chemical production process, from raw materials through reactors to the products we want. Type of reactor There are many types of reactors, which can be summarized as the following types according to the working principle of the reactor: Expand the full text 1. Tubular reactor In chemical production, the continuously operating tubular reactor with a large length-to-diameter ratio can be approximately regarded as an ideal displacement flow reactor (Plug flow reactor, referred to as PFR). It is suitable for both liquid and gas phase reactions. PFRs are particularly suitable for pressurized reactions due to their ability to withstand high pressures. It has the advantages of small volume, large specific surface area, less backmixing, continuous change of reaction parameters and easy control, but for slow reaction, it has the disadvantages of long tube and large pressure drop. Type of tubular reactor 1 Horizontal tubular reactor Is formed by connecting a seamless steel pipe with a U-shaped pipe. The structure is easy to process, manufacture and overhaul. High pressure reaction piping is connected with standard groove butt-welded steel flanges, which can withstand 1600-10000 kPa pressure. If a lens face steel flange is used, the pressure can be up to 10000-20000 kPa. 2 Vertical tubular reactor The vertical tube reactor is used in liquid phase ammoniation reaction, liquid phase hydrogenation reaction, liquid phase oxidation reaction and other processes. Coil reactor 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. 4 U-tube reactor 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. 5 Multi-tube parallel tubular reactor Tubular reactors with multi-tube parallel structure are generally used for gas-solid phase reactions, for example, gas-phase hydrogen chloride and acetylene react to produce vinyl chloride in reactors with multi-tube parallel structure filled with solid phase catalyst, and gas-phase nitrogen and hydrogen mixture synthesizes ammonia in reactors with multiple tubes parallel structure filled with solid phase iron catalyst. 6 Plug flow reactor Performance characteristics: ① The length-diameter ratio of the reactor is large. ② It is assumed that there is no backmixing between the materials entering the reactor at different times. (3) The reactant flows along the length of the tube, the reaction time is a function of the length of the tube, and its concentration changes with the flow direction from one section to another. 2. Kettle-type reactor Kettle reactor, also known as tank reactor and pot reactor, is a kind of reactor with simple structure and wide application. It can be used for both homogeneous reactions and heterogeneous reactions in which the liquid phase predominates. Uch as heterogeneous liquid phase, liquid-solid phase, gas-liquid phase, gas-liquid solid phase and the like. The structure of the kettle type reactor is mainly composed of a shell, a stirring device, a shaft seal and a heat exchange device. Heat exchange device: Stirring device: 1 Intermittent kettle 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 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. 2 continuous kettle Continuous kettle reactor, or continuous kettle 3 Stirred Tank Reactor Stirred tank reactor has vertical vessel central stirring, eccentric stirring,wiped film distillation, inclined stirring, horizontal vessel stirring and other types. Among them, the stirred tank reactor centered in a vertical vessel is the most typical one. 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. 4 multi-stage series reaction kettle III. 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,hemp extraction centrifuge, 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. 1 Axially Adiabatic Fixed Bed Reactor 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 The figure below is a schematic diagram of an adiabatic fixed bed reactor. 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 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 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. Xternal heat exchange type fixed bed reactor Most of the external heat exchange reactors are tubular. Usually, the catalyst is placed in the tubes and the heat carrier is passed between the tubes (when high-pressure water or high-pressure steam is used as the heat carrier, the catalyst is placed between the tubes and the high-pressure fluid is passed through the tubes). Multistage adiabatic fixed bed reactor 3 Self-heat exchange reactor (autothermal reactor) The materials before and after the reaction exchange heat by themselves in the bed, which is called autothermal reactor. IV. 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 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. Bed type of fluidized bed reactor The advantages of a fluidized bed reactor over a fixed bed reactor are: 1, jacketed glass reactor ,decarboxylation after extraction, 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.
5. 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 per unit. 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 Compared with fixed bed reactor and fluidized bed reactor, the main advantages of moving bed reactor are that the residence time of solid and fluid can be changed in a wider range, the backmixing is smaller (similar to fixed bed reactor), and it is also applicable to the reaction process in which the properties of solid materials change at medium speed (in hours). In contrast, the fixed bed reactor and the fluidized bed reactor are only suitable for the reaction process in which the properties of solid materials change very slowly (in months) and very quickly (in minutes and seconds), respectively. The disadvantage of a moving bed reactor is that it is difficult to control the uniform downward movement of the solid particles. Simulated moving beds are sometimes used in industry to avoid these disadvantages (see fixed bed mass transfer equipment). VI. Trickle bed reactor Also known as trickle bed reactor, it is a kind of reactor in which gas and liquid flow concurrently through the bed of granular solid catalyst to carry out gas-liquid solid phase reaction process. The catalyst in the trickle-bed reactor exists in the form of fixed bed, so this kind of reactor can also be regarded as a kind of fixed bed reactor. Trickle bed reactors are often operated under pressure in order to facilitate dissolution of the gas in the liquid. Hydrocracking and hydrodesulfurization (HDS) in petroleum refining are industrial processes using large-scale trickle-bed reactors. Trickle bed reactors are also used in chemical production, but on a small scale, for example, in the preparation of isopropanol from propylene hydration with tungsten trioxide as catalyst. The fluid flow condition in the trickle-bed reactor is slightly different from that in the packed column. The gas and liquid phases flow downward in parallel without flooding. A certain amount of nearly static liquid is stored in the micropores of the catalyst. The trickle-bed reactor is usually of multistage adiabatic type, in which heat is exchanged between stages or materials are supplemented to adjust the temperature, and a distributor is installed at the top of each stage to make the liquid flow uniform To ensure sufficient wetting of the catalyst particles. Compared with the slurry reactor commonly used in the gas-liquid solid phase reaction process, the trickle-bed reactor has the following main advantages: 1, the backmixing is small, so that higher conversion rate can be achieved conveniently; 2, that liquid-solid ratio is low, and the liquid phase side reaction is less; And 3, the recovery problem of the catalyst fine powder is avoided. The disadvantages are that the temperature is difficult to control, the inner surface of the catalyst particles is often not fully utilized, and the catalyst cannot be continuously discharged for regeneration during the reaction. VII. Tower Reactor Tower reactors are mainly divided into the following types: 1 Bubble column reactor The column is filled with liquid, and the gas is introduced from the bottom of the reactor and dispersed into bubbles rising along the liquid, which contacts with the liquid phase for reaction while stirring the liquid to increase the mass transfer rate. This type of reactor is suitable for medium-speed and slow-speed reactions in which the liquid phase also participates in the reaction and for reactions with large heat release. Advantages: the bubble column reactor is simple in structure, low in cost, easy to control, easy to maintain, and easy to solve the problem of corrosion prevention, and has no difficulty in being used for high pressure. Disadvantages: The liquid in the bubble column is seriously backmixed, and the bubbles are easy to coalesce, so the efficiency is low. 2 Packed column reactor 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, and 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. 3 Plate column reactor The liquid flows transversely through the tray and overflows into the downcomer through the overflow weir, and the liquid releases the entrained gas in the downcomer and flows to the next tray from the bottom gap of the down-comer. The gas below the tray passes through the gas phase channels on the tray, such as sieve holes, float valves, etc., and enters the liquid layer on the tray for bubbling, and the gas and liquid contact for mass transfer. The gas phase leaves the liquid layer and rushes to the upper tray for multi-stage contact mass transfer. 4 Spray Tower Reactor 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 the continuous phase and the liquid is the dispersed phase. Spray tower is a gas film controlled reaction system, which is suitable for instantaneous, interfacial and rapid reaction processes. Hollow inside the tower, especially suitable for systems with sludge, sedimentation and solid product formation VIII. Several Combined Reactors 1 Cyclone reactor Cyclone reactor is a new type of chemical reaction equipment with high efficiency, which is improved from the traditional cyclone dust collector and hydrocyclone. When some auxiliary equipment is added, it can be used for two-phase or three-phase reaction at high temperature. When working, the fluid enters the reactor from the tangential direction, and under the combined action of centrifugal force, friction force, gravity and the like, all components rotate and move downwards along the inner wall of the reactor, during which all fluid components fully contact and react. Finally, the component with high density is discharged from the lower part of the reactor, and the component with low density is discharged from the upper part of the reactor by flowing upstream along the axial direction of the reactor. At present, it has been used in photochemistry, bioengineering and industrial fields, such as cement decomposition outside the kiln, cyclone combustion of debris fuels, cyclone furnace and fluidized bed roasting. However, because the research on the transfer characteristics of cyclone reactor involves many disciplines such as chemistry, fluid mechanics, heat and mass transfer, it is difficult to study, so the research on its working mechanism has made slow progress. 2 Loop reactor The loop reactor combines the excellent performance of the bubble column and the mechanical stirred tank. It has the advantages of fast reaction speed, simple structure, no mechanical transmission parts and easy engineering scale-up. It is a kind of efficient gas-liquid contact reaction equipment. The loop reactor comprises an ascending pipe, a descending pipe, a gas-liquid separator and a bottom connecting section. 3 Multiphase Combined Membrane Bioreactor Multiphase composite membrane bioreactor is a new type of equipment for wastewater treatment and reuse, which combines membrane separation technology with traditional biological wastewater treatment process. The organic substances discharged from the fine chemical production process are mostly toxic and difficult to degrade, which seriously endanger the environment, so the treatment of chemical waste liquid has been paid more and more attention. Multiphase combined membrane bioreactor technology greatly improves the separation efficiency through the efficient separation of membrane modules, while the isolation and filtration of membranes provide raw materials with higher mass fraction for subsequent biological reactions. For example, in solid-liquid separation, the mass concentration of activated sludge in membrane bioreactor can reach (20000 ~ 30000) mg/L. Because of such a high biomass, the degradation ability of membrane reactor to organic matter is very significant, and it has been widely used in reclaimed water treatment projects at home and abroad. This is Chemical 707, thank you for reading! Good things should not only be collected, but also be shared in the circle of friends! Chemical 707 WeChat ID: hg707 _ com Deputy editor wechat: lyh _ 707 We are all chemical workers,cbd centrifugal extractor, chemical road, go together! > > Haven't you enjoyed it yet? Click "Read the original article", and then see "38 valve Gif working status and principle at a glance!" Return to Sohu while loading to see more Responsible Editor:. toptiontech.com | |
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