Sunday, December 30, 2007

Tuesday, December 18, 2007

Spray drier

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Spray drying

Spray drying is a commonly used method of drying a liquid feed through a hot gas. Typically, this hot gas is air but sensitive materials such as pharmaceuticals, and solvents like ethanol require oxygen-free drying and nitrogen gas is used instead. The liquid feed varies depending on the material being dried and is not limited to food or pharmaceutical products, and may be a solution, colloid or suspension. This process of drying is a one step rapid process and eliminates additional processing.

The liquid feed is pumped through an atomiser device that produces fine droplets into the main drying chamber. Atomisers vary with rotary, single fluid, two-fluid, and ultra-sonic designs. These different styles have different advantages and disadvantages depending on the application of the spray drying required.

The hot drying gas can be passed as a co-current or counter-current flow to the atomiser direction. The co-current flow enables the particles to have a lower residence time within the system and the particle separator (typically a cyclone device) operates more efficiently. The counter-current flow method enables a greater residence time of the particles in the chamber and usually is paired with a fluidised bed system.

Spray drying often is used as an encapsulation technique by the food and pharmaceutical industries. A substance to be encapsulated (the load) and an amphipathic carrier (usually some sort of modified starch) are homogenized as a suspension in water (the slurry). The slurry is then fed into a spray drier, usually a tower heated to temperatures well over the boiling point of water.

As the slurry enters the tower, it is atomized. Partly because of the high surface tension of water and partly because of the hydrophobic/hydrophilic interactions between the amphipathic carrier, the water, and the load, the atomized slurry forms micelles. The small size of the drops (averaging 100 micrometers in diameter) results in a relatively large surface area which dries quickly. As the water dries, the carrier forms a hardened shell around the load.

Load loss is usually a function of molecular weight. That is, lighter molecules tend to boil off in larger quantities at the processing temperatures. Loss is minimized industrially by spraying into taller towers. A larger volume of air has a lower average humidity as the process proceeds. By the osmosis principle, water will be encouraged by its difference in fugacities in the vapor and liquid phases to leave the micelles and enter the air. Therefore, the same percentage of water can be dried out of the particles at lower temperatures if larger towers are used.

The application of the spray drying encapsulation technique is to prepare "dehydrated" powders of substances which do not have any water to dehydrate. For example, instant drink mixes are spray dries of the various chemicals which make up the beverage. The technique was once used to remove water from food products; for instance, in the preparation of dehydrated milk.

Because the milk was not being encapsulated and because spray drying causes thermal degradation, milk dehydration and similar processes have been replaced by other dehydration techniques. Skim milk powders are still widely produced using spray drying technology around the world, typically at high solids concentration for maximum drying efficiency. Thermal degradation of products can be overcome by using lower operating temperatures and larger chamber sizes for increased residence times.

Nutritional evaluation of food processing second edition (1975), Robert S. Harris, Ph.D. and Endel Karmas Ph.D. (eds)
Keey, R.B., (1992). Drying of Loose and Particulate Materials, 1st, (pp504). Hemisphere Publishing Corporation,

External links
Marriott Walker Corporation, A World Leader in Spray Drying Technology.
Niro's expertise in spray drying.
Short overview on spray drying from Japanese manufacturer.
Spray drying on Hyfoma.
Niro A/S - article on Spray Drying. - CAE spray drying.
Anderson Custom Processing.
Delavan spray drying technologies.
Delavan's technical know how on spray drying.

See also
Spray Nozzle


Spray Dryers
Anhydro spray dryers can be used for a wide range of applications. The spray drying process is a continuous operation in which almost any pumpable liquid can be converted into a free flowing powder.With more than 3,500 spray dryers installed worldwide, Anhydro combines experience and cutting-edge technology into added-value solutions for its customersSpray Dryers - Function and principle of operationThe liquid is dried, collected and delivered for further treatment without any intermediate manual handling. The spray drying process is applicable to a wide range of products and industries, and plant capacities from a few gr/h to 80 tons/h are available. Anhydro handles projects ranging from laboratory size to large industrial spray dryer processing lines and turnkey plants.Correct atomization and air distribution are the keys to the spray drying process, as both greatly influence the final powder structure and quality. Often, spray dryers are equipped with high-speed centrifugal atomizers ensuring sturdy and reliable operation. High-Pressure nozzle atomization is used especially for products where a rather coarse powder with narrow particle distribution and high bulk density is required. In the nozzle atomizer, fines are returned around one or more central nozzles in order to facilitate optimum agglomeration. Two-Fluid nozzle agglomeration is typically applied in small chambers allowing maximum flexibility in particle design and particle engineering for both super-fine and agglomerated particles.Benefits of Anhydro Spray DryersAnhydro spray dryers are available in a wide range of sizes and configurations providing:
Uniform qualityComplete control of moisture content, particle structure, particle size distribution, solubility, and wettability, and retention of natural aromas and flavours
Unbeatable performance/cost ratioEnergy efficient components, continuous and rapid drying, ease of operation and process automation provide complete control over yield and costs.
VersatilityCustomizable plant design based on many years of experience in a wide range of applications is your assurance of complete compliance with your individual requirements.
Long service lifeTop-quality, reliable components, efficient and straightforward CIP and expert engineering increase service life and availability for maximum performance
TraceabilityAutomated process control enables end-to-end traceability in compliance with current food standards and regulations
Special featuresAnhydro spray dryers incorporate a number of special design features including atomizers as well as the Anhydro Controlled Flow Nozzle for easy start-up and shut-down, short off-spec period, controlled particle size and easy process control.Fields of applicationLiquid-to-powder spray dryer products throughout the dairy, food, feed, chemical, pharmaceutical and environmental sectorsCapacity profileA few gr/h to 80 tons/hSpray Dryer Designs availableTraditional open-cycle systems in single stage or multi-stage modesClosed curcuit systems applying either inert gas, Low-Ox or super-heated steam configurationMore than 20 different chamber designs including conical bottom, flat bottom, Tall Form, Uniflow and High Body

About Spray Bed Dryers


Anhydro Spray Dryer installed succesfully at a customer.
Related industries
Coffee Industry
Related products
Anhydro Triple-A Dryer
Dryers for Pharmaceutical Applications
Spray Drying
Spray Drying of Coffee
Spray Bed Dryers
Small Scale Plants
Small Scale Plant Rental
Test Centres
Related brochures
Chemical brochures
Dairy brochures
Food brochures
Pharmaceutical brochures



Psychrometrics or psychrometry are terms used to describe the field of engineering concerned with the determination of physical and thermodynamic properties of gas-vapor mixtures.
1 Common applications
2 Psychrometric ratio
3 Psychrometric chart
4 How to read the chart
5 Dry-bulb temperature
6 Wet-bulb temperature
7 See also
8 External links

Psychrometric Chart
The psychrometric chart is a useful design tool for air conditioning engineers. The chart presents a number of properties of moist air:
dry-bulb temperature
sling wet-bulb temperature
moisture content
specific enthalpy
specific volume
percentage saturation Related topics:
Ideal Gas
Air conditioning



Monday, December 17, 2007

Simulation of Processes

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Filter Press

The filter press is an industrial machine, used for solid/liquid separation processes.
The solid/liquid separation process with the filter press, is gotten through filtering cloths and plates. The filter presses are assembled with two different types of plates:
Recessed plate[1], suitable for the most of the standard applications
Membrane plate[2], adapted for special applications.
The filter press are used today in many industrial sectors: mining, metallurgical, chemical/pharmaceutical, municipality and alimentary.
View the Filter Press Operation [3]


Reactors and Reaction Vessels

16 litre Pharma Reactor


A fluidized bed reactor (FBR) is a type of reactor device that can be used to carry out a variety of multiphase chemical reactions. In this type of reactor, a fluid (gas or liquid) is passed through a granular solid material (usually a catalyst possibly shaped as tiny spheres) at high enough velocities to suspend the solid and cause it to behave as though it were a fluid. This process, known as fluidization, imparts many important advantages to the FBR. As a result, the fluidized bed reactor is now used in many industrial applications.

Basic diagram of a fluidized bed reactor.
1 Basic principles
2 History and current uses
3 Advantages
4 Disadvantages
5 Current research and trends
6 References
7 See also
8 External links

[edit] Basic principles
The solid substrate (the catalytic material upon which chemical species react) material in the fluidized bed reactor is typically supported by a
porous plate, known as a distributor.[1] The fluid is then forced through the distributor up through the solid material. At lower fluid velocities, the solids remain in place as the fluid passes through the voids in the material. This is known as a packed bed reactor. As the fluid velocity is increased, the reactor will reach a stage where the force of the fluid on the solids is enough to balance the weight of the solid material. This stage is known as incipient fluidization and occurs at this minimum fluidization velocity. Once this minimum velocity is surpassed, the contents of the reactor bed begin to expand and swirl around much like an agitated tank or boiling pot of water. The reactor is now a fluidized bed.Depending on the operating conditions and properties of solid phase various flow regimes can be observed in this reactor.

[edit] History and current uses
Fluidized bed reactors are a relatively new tool in the industrial engineering field. The first fluidized bed gas generator was developed by Fritz Winkler in Germany in the
1920s.[2] One of the first United States fluidized bed reactors used in the petroleum industry was the Catalytic Cracking Unit, created in Baton Rouge, LA in 1942 by the Standard Oil Company of New Jersey (now ExxonMobil).[3] This FBR and the many to follow were developed for the oil and petrochemical industries. Here catalysts were used to reduce petroleum to simpler compounds through a process known as cracking. The invention of this technology made it possible to significantly increase the production of various fuels in the United States. [4]
Today fluidized bed reactors are still used to produce gasoline and other fuels, along with many other chemicals. Many industrially produced
polymers are made using FBR technology, such as rubber, vinyl chloride, polyethylene, and styrenes. Various utilities also use FBR’s for coal gasification, nuclear power plants, and water and waste treatment settings. Used in these applications, fluidized bed reactors allow for a cleaner, more efficient process than previous standard reactor technologies.[4]

[edit] Advantages
The increase in fluidized bed reactor use in today’s industrial world is largely due to the inherent advantages of the technology.
Uniform Particle Mixing: Due to the intrinsic fluid-like behavior of the solid material, fluidized beds do not experience poor mixing as in packed beds. This complete mixing allows for a uniform product that can often be hard to achieve in other reactor designs. The elimination of radial and axial concentration
gradients also allows for better fluid-solid contact, which is essential for reaction efficiency and quality.
Uniform Temperature Gradients: Many chemical reactions produce or require the addition of heat. Local hot or cold spots within the reaction bed, often a problem in packed beds, are avoided in a fluidized situation such as a FBR. In other reactor types, these local temperature differences, especially hotspots, can result in product degradation. Thus FBRs are well suited to
exothermic reactions. Researchers have also learned that the bed-to-surface heat transfer coefficients for FBRs are high.
Ability to Operate Reactor in Continuous State: The fluidized bed nature of these reactors allows for the ability to continuously withdraw product and introduce new reactants into the reaction vessel. Operating at a
continuous process state allows manufacturers to produce their various products more efficiently due to the removal of startup conditions in batch