Category: Fluidized bed meaning in hindi

Fluidized bed meaning in hindi

This is usually achieved by the introduction of pressurized fluid through the particulate medium. This results in the medium then having many properties and characteristics of normal fluids, such as the ability to free-flow under gravity, or to be pumped using fluid type technologies. The resulting phenomenon is called fluidization. Fluidised beds are used for several purposes, such as fluidized bed reactors types of chemical reactorssolids separation, [1] fluid catalytic crackingfluidized bed combustionheat or mass transfer or interface modification, such as applying a coating onto solid items.

This technique is also becoming more common in aquaculture for the production of shellfish in integrated multi-trophic aquaculture systems. A fluidised bed consists of fluid-solid mixture that exhibits fluid-like properties.

As such, the upper surface of the bed is relatively horizontal, which is analogous to hydrostatic behavior. The bed can be considered to be a heterogeneous mixture of fluid and solid that can be represented by a single bulk density.

Furthermore, an object with a higher density than the bed will sink, whereas an object with a lower density than the bed will float, thus the bed can be considered to exhibit the fluid behavior expected of Archimedes' principle.

As the "density", actually the solid volume fraction of the suspensionof the bed can be altered by changing the fluid fraction, objects with different densities comparative to the bed can, by altering either the fluid or solid fraction, be caused to sink or float. In fluidised beds, the contact of the solid particles with the fluidisation medium a gas or a liquid is greatly enhanced when compared to packed beds.

This behavior in fluidised combustion beds enables good thermal transport inside the system and good heat transfer between the bed and its container. Similarly to the good heat transfer, which enables thermal uniformity analogous to that of a well mixed gas, the bed can have a significant heat-capacity whilst maintaining a homogeneous temperature field.

Fluidized beds are used as a technical process which has the ability to promote high levels of contact between gases and solids. In a fluidised bed a characteristic set of basic properties can be utilised, indispensable to modern process and chemical engineering, these properties include:. Taking an example from the food processing industry: Fluidized beds are used to accelerate freezing in some individually quick frozen IQF tunnel freezers.

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These Fluidized bed tunnels are typically used on small food products like peas, shrimp or sliced vegetables, and may use cryogenic or vapor-compression refrigeration.

The fluid used in Fluidized beds may also contain a fluid of catalytic type; that's why it is also used to catalyse the chemical reaction and also to improve the rate of reaction. Fluidized beds are also used for efficient bulk drying of materials.

Fluidized bed technology in dryers increases efficiency by allowing for the entire surface of the drying material to be suspended and therefore exposed to the air. This process can also be combined with heating or cooling, if necessary, according to the specifications of the application. InFritz Winkler made the first industrial application of fluidization in a reactor for a coal gasification process.

Bed types can be coarsely classified by their flow behavior, including: [6]. When the packed bed has a fluid passed over it, the pressure drop of the fluid is approximately proportional to the fluid's superficial velocity.

In order to transition from a packed bed to a fluidised condition, the gas velocity is continually raised. For a free-standing bed there will exist a point, known as the minimum or incipient fluidisation point, whereby the bed's mass is suspended directly by the flow of the fluid stream.

At the base of the vessel the apparent pressure drop multiplied by the cross-section area of the bed can be equated to the force of the weight of the solid particles less the buoyancy of the solid in the fluid. InProfessor D. Geldart proposed the grouping of powders in to four so-called "Geldart Groups". Design methods for fluidised beds can be tailored based upon the particle's Geldart grouping: [11]. Prior to the initiation of a bubbling bed phase, beds from these particles will expand by a factor of 2 to 3 at incipient fluidisation, due to a decreased bulk density.

Most powder-catalyzed beds utilize this group. Bubbling typically forms directly at incipient fluidisation. Group C This group contains extremely fine and consequently the most cohesive particles.From professional translators, enterprises, web pages and freely available translation repositories. Bed bug. Bed sheet. Lied on the bed. Amo Mari chudali. Fluidized bed drying. Fluidized bed processing. I am Still laying on bed. We work at out relationship, you have to keep working, both of you.

She needs to do her part, in bed and out of bed.

fluidized bed meaning in hindi

More context All My memories Ask Google. Add a translation. English Bed. English Bed bug.

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English Bed sheet. English parupu of meaning. Telugu meaning of parupu. English Lied on the bed. Telugu Amo Mari chudali. English bed lo ethuukovadam.

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Telugu bed lo ethukovadam. English bed lo padukovadam.

fluidized bed meaning in hindi

Telugu bed lo eth ukovadam. English Fluidized bed drying. English Fluidized bed processing. English fluidized bed combustors. English fluidized bed reactors.

English bed meaning in telugu. English i am lying on the bed.

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English now i am going to bed. Telugu nenu padukovadaniki veltunanu.Fluidized bed dryer also called fluid bed dryer is a kind of equipment used extensively in the pharmaceutical industries to reduce the moisture content of pharmaceutical powder and granules.

In fluidization process, hot air is introduced at high pressure through a perforated bed of moist solid particulate. The wet solids are lifted from the bottom and suspended in a stream of air fluidized state. Heat transfer is accomplished by direct contact between the wet solid and hot gases. The vaporized liquid is carried away by the drying gasses. Sometimes to save energy, the exit gas is partially recycled. The choice of distributor used during and drying process apart from ensuring uniform and stable fluidization also prevents.

The pressure drops across the distributor must be high enough to ensure good and uniform fluidization. In order to improve operation, efficiency, and reproducibility of a fluidized bed dryer, some parameters need to be controlled. These parameters are categorized into:. Read Also: Rotary Dryer. In many instances, several different types may provide similar performance at the same cost. It should be noted also that not all modified fluidized bed dryers are necessarily better than the conventional dryers in terms of product quality, or energy efficiency, or drug performance.

Various types of modified fluidized bed dryers have been developed and are applied in many industrial processes to overcome some of the problems encountered while using conventional fluidized bed dryers for a drying process.

They include but not limited to. It should be noted that not all modified fluidized bed dryers are necessarily better than the conventional dryers in terms of product quality, or energy efficiency, or drying performance.

High rates of moisture removal due to excellent gas-particle constant which results in high heat and mass transfer rates. High thermal efficiency is usually achieved if part of the thermal energy for drying is supplied by the internal heat exchanger. High pressure drops results as a result of the need to suspend the entire bed in gas which equally leads to high energy consumption.

Requires increased gas handling due to extensive recirculation of exhaust gas for high thermal efficiency operation. The conventional hot air fluidized bed dryers are not a good choice of dryer when handling toxic or flammable solids since there is danger of fire or explosion of flammability limits are exceeded. Your email address will not be published. Notify me of follow-up comments by email. Notify me of new posts by email. Enter your email address to subscribe to this blog and receive notifications of new posts by email.

fluidized bed meaning in hindi

Email Address. Thursday, January 21, Post Ads For Free. Fluidized Bed Dryer by Pharmapproach.Ankur Choudhary Print Question Forum 5 comments. Fluidized bed dryer FBD is well known and widely used equipment in granulation area of pharmaceutical manufacturing.

It is used in the granulation process for drying the material to get desired moisture content in the tablet formulation granules required for perfect compression of tablets. The Principle of Fluidized Bed Dryer: If air is allowed to flow through a bed of solid powdered material in the upward direction with the velocity greater than the settling rate of the particles, the solid particles will be blown up and become suspended in the air stream.

At this stage, this solid bed looks like the boiling liquid, therefore this stage is called as fluidized. Use of hot air to fluidizing the bed will increase the drying rate of the material. FBD contains a stainless steel chamber having a removable perforated bottom known as the bowl. Material to be dry is placed in this bowl.

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Air is introduced from the bottom of the bowl and heated at required temperature by the heaters. This air is filtered through the filter and then passes through the bed of the material. The flow rate and the operating temperature are adjusted by the control panel. Due to the regular contact with air, the material gets dry.

The air leaving the FBD passes through the filter to collect the fine particles of the material. Fluidized bed dryer has a high drying rate and the material is dried in a very short time. Material remains free-flowing and uniform.

FBD bags are finger-like in structure to increase the surface area of the drying bed that helps to increase the drying rate and decrease the drying time during the fluidized bed drying process. Burning of the material in the fluid bed dryer equipment is experienced in many cases in different pharmaceutical companies.

Outlet filter blockage is a common problem of the fluidized bed dryer equipment. Therefore, handling of the equipment should be done carefully. Pin it. Ankur Choudhary is India's first professional pharmaceutical blogger, author and founder of Pharmaceutical Guidelines, a widely-read pharmaceutical blog since Sign-up for the free email updates for your daily dose of pharmaceutical tips.

Visitors are also reading:. You can ask questions related to this post here. Unknown 19 August.Fluidization or fluidisation is a process similar to liquefaction whereby a granular material is converted from a static solid -like state to a dynamic fluid -like state.

This process occurs when a fluid liquid or gas is passed up through the granular material. When a gas flow is introduced through the bottom of a bed of solid particles, it will move upwards through the bed via the empty spaces between the particles.

At low gas velocities, aerodynamic drag on each particle is also low, and thus the bed remains in a fixed state. Increasing the velocity, the aerodynamic drag forces will begin to counteract the gravitational forces, causing the bed to expand in volume as the particles move away from each other. Further increasing the velocity, it will reach a critical value at which the upward drag forces will exactly equal the downward gravitational forces, causing the particles to become suspended within the fluid.

At this critical value, the bed is said to be fluidized and will exhibit fluidic behavior. By further increasing gas velocity, the bulk density of the bed will continue to decrease, and its fluidization becomes more violent, until the particles no longer form a bed and are "conveyed" upwards by the gas flow.

When fluidized, a bed of solid particles will behave as a fluid, like a liquid or gas. Like water in a bucket : the bed will conform to the volume of the chamber, its surface remaining perpendicular to gravity ; objects with a lower density than the bed density will float on its surface, bobbing up and down if pushed downwards, while objects with a higher density sink to the bottom of the bed. The fluidic behavior allows the particles to be transported like a fluid, channeled through pipesnot requiring mechanical transport e.

A simplified every-day-life example of a gas-solid fluidized bed would be a hot-air popcorn popper. The popcorn kernelsall being fairly uniform in size and shape, are suspended in the hot air rising from the bottom chamber. Because of the intense mixing of the particles, akin to that of a boiling liquid, this allows for a uniform temperature of the kernels throughout the chamber, minimizing the amount of burnt popcorn.

After popping, the now larger popcorn particles encounter increased aerodynamic drag which pushes them out of the chamber and into a bowl. The process is also key in the formation of a sand volcano and fluid escape structures in sediments and sedimentary rocks.

Fluidized bed

Most of the fluidization applications use one or more of three important characteristics of fluidized beds:. In the s, the Winkler process was developed to gasify coal in a fluidized bed, using oxygen.

It was not commercially successful. The first large scale commercial implementation, in the early s, was the fluid catalytic cracking FCC process, [1] which converted heavier petroleum cuts into gasoline. Carbon-rich " coke " deposits on the catalyst particles and deactivates the catalyst in less than 1 second. The fluidized catalyst particles are shuttled between the fluidized bed reactor and a fluidized bed burner where the coke deposits are burned off, generating heat for the endothermic cracking reaction.

By the s, fluidized bed technology was being applied to mineral and metallurgical processes such as drying, calciningand sulfide roasting. In the s, several fluidized bed processes dramatically reduced the cost of some important monomers.

Examples are the Sohio process for acrylonitrile [2] and the oxychlorination process for vinyl chloride. In the late s, a fluidized bed process for the synthesis of polyethylene dramatically reduced the cost of this important polymermaking its use economical in many new applications.

A similar process is used for the synthesis of polypropylene. Currently, most of the processes that are being developed for the industrial production of carbon nanotubes use a fluidized bed. A new potential application of fluidization technology is chemical looping combustionwhich has not yet been commercialized.

One solution to reducing the potential effect of carbon dioxide generated by fuel combustion e. Chemical looping uses a metal oxide as a solid oxygen carrier. These metal oxide particles replace air specifically oxygen in the air in a combustion reaction with a solid, liquid or gaseous fuel in a fluidized bed, producing solid metal particles from the reduction of the metal oxides and a mixture of carbon dioxide and water vaporthe major products of any combustion reaction.

The water vapor is condensed, leaving pure carbon dioxide which can be sequestered. The solid metal particles are circulated to another fluidized bed where they react with air and again, specifically oxygen in the airproducing heat and oxidizing the metal particles to metal oxide particles that are recirculated to the fluidized bed combustor.

Liquid-solid fluidization has a number of applications in engineering [8] [9] The best known application of liquid-solid fluidization is the backwash of granular filters using water. Fluidization has many applications with the use of ion exchange particles for the purification and processing of many industrial liquid streams.Related to fluidised: Fluidised bed.

All rights reserved. Copyright, by Random House, Inc. Mentioned in? References in periodicals archive? Rowe, "Prediction of bubble size in a gas fluidised bed," Chemical Engineering Science, vol. Research Article. Polycyclic aromatic compounds in oils derived from the fluidised bed pyrolysis of oil shale. Combined fluidized bed retorting and circulating fluidized bed combustion system of oil shale: 1. System and key issues.

fluidized bed meaning in hindi

The velocity through the fluidized state was almost uniform which confirmed uniform void age and porosity through the fluidised state. Simulation for supporting scale-up of a fluidized bed reactor for advanced water oxidation.

Fluidized Bed Dryer

Industrial Fluidised Baths remove all polymers and hydrocarbon-based products from tooling, components and parts. Techne Industrial Fluidised baths offer "fastest and lowest cost plastic extrusion tool cleaning system".

The new TC-9D control unit incorporates a flow meter in addition to a thermocouple, for more accurate and reproducible operation of the Techne SBL range of fluidised sand baths. Investigation into the hydrodynamics of gas--solid fluidized beds using particle image velocimetry coupled with digital image analysis. The system, the idea of group chairman Chris Clayton, uses advanced fluidised bed technology to remove sand cores from castings, clean the sand for re-use and provide a means of heat treatment for the same castings.

Clayton wins Euro patent for system. Dictionary browser? Full browser?Fluid Mechanics for Fluidized Beds To better understand fluidization of a particle bed, it is necessary to determine what range of flow rates allow fluidization, and also, what flow rates will begin to carry the particles out the top of the particle chamber.

We wish to determine a minimum flow rate allowing the particles to become fluidized, the minimum fluidization velocity umand the flow rate which carries the first particle out of the chamber, the terminal velocity ut.

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We used the Ergun equation on the packed bed page to describe the drag exerted on a particle bed by the fluid flow. By setting this equation equal to the gravitational force of the particle bed, we can determine the minimum fluidization velocity um. In this case, the equation is rearranged: The above equation is a quadratic in u, where u now stands for um, the minimum fluidization velocity. The next step is to determine ut.

The ut is the velocity that is large enough to lift a single particle and carry it out of the fluidized bed. Then the equations are those for drag past a sphere. This implies there are three different equations for ut corresponding to these flow regimes. The image below contains the ut equations for the three flow regimes.

Fluidized Bed Animations The plot below represents the Ergun equation the first equation shown abovewhere the left hand side of the equation is the pressure drop.

Click on the curve to see the effects of increased gas velocity on particle movement.


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