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simulation and determination of spray drying parameters


Key words Spray drying, operating parameters, drying kinetics, a priori, liquid foodstuff, free water, bound water, desorption, Spray dryed oil powder, Encapsulation of lycopene, Modification of phospholipids
Latest version 2013/09/05
Completed by INRA - IATE

How does it work?

Primary objective To forecast the operating parameters of spray dryers used in the dairy and food industry before Spray drying (a priori). This allows an improvement in accuracy: the gap between calculated energy and real energy to provide for the spray drying of 15% with conventional methods is reduced to 5% with this method.
Working principle The principle is based on determining precisely and in advance the thermodynamic parameters of the Spray drying of dairy products or food concentrates from their physico-chemical characteristics, determined using drying by desorption.

The analysis of the data coming from the drying kinetics of desorption allows determining the ratio of free and bound water. The total energy to remove 1 kg of (free and bound) water is then calculated.

The developed method is made up of the following steps:

  1. Drying by desorption, in order to determine experimentally the quantities of free and bound water of a food product.
  2. Determination of the drying kinetics of the product.
  3. Display of the drying kinetics of the product through a graph showing drying kinetics versus time.
  4. Determination of inlet and outlet temperatures of air in the spray dryer: a priori calculation of the drying parameters (postulating that if the drying speed decreases by half, the system needs two times more energy to maintain a constant speed, and taking into account specific characteristics of both the spray drier and the food product).
  5. Display of the calculated theoretical parameters versus measured values (including inlet and outlet air temperatures). A database of more than 100 experimental results (dairy and non-dairy products) is used to validate the calculated theoretical parameters [1-5]
Additional effects The accuracy improvement enables energy saving.

It is possible to have an indirect idea of the powder behaviour in the spray dryer by considering its stickiness.

Important process parameters specific characteristics of the spray drying facility: cell wall loss, evaporating capacity of the facility or air and product flow, absolute humidity of outside air
Important product parameters specific characteristics of the product: temperature of the product to be dried, humidity, energy cost to reach.

What can it be used for?

Products Concentrates and liquid dairy and food products.

Any product that can be spray dried.

Operations Spray drying (stabilizing)
Solutions for short comings Save time & energy

Facilitate spray-drying processes

What can it NOT be used for?

Products Solid products
Operations Any other operation than spray drying
Other limitations No limitations for dairy and food concentrates.

Current methods: as far as we know, no method exists at this time to precisely determine a priori spray drying parameters for dairy or food products. Most industrial dairy manufacturers determine milk powder production parameters empirically and then attempt to transpose them to other products without taking into account the physico-chemical composition of these new products. This is why some pilot spray dryers enable manufacturers to determine operating parameters a posteriori. However, tests are complex, costly and must be repeated for each new product.

Risks or hazards No risks nor hazards known


Maturity The method has been formalized through the design of a software: SD2P® (Spray-Drying Parameters Simulation & Determination).

This software has been tested on spray dryers from pilot scale (5 kg.h-1 of water evaporation) to industrial scale (6000 kg.h-1 of water evaporation).

Last version of the software: 2009-12-02

SD2P® is currently designed for the dairy industry but additional research could make it possible to validate this approach for products made of crystallisable sugars thus opening the way for other applications in the agri-food sector and pharmaceuticals.

Modularity /Implementation The SD2P® software is useful for R&D or/and production team.

The SD2P® software can be inserted in an existing production line.

Consumer aspects not applicable
Legal aspects registered software: IDDN.FR.001.480002.003.R.P.2005.000.30100
Environmental aspects The SD2P® software enables to optimize and/or to reduce the energy cost to produce dairy and food powders.

Further Information

Institutes INRA - STLO, Monash University
Companies Laiterie de Montaigu, Rotronic
References [1] Schuck P., Briard V., Mejean S., Piot M., Famelart M.H., Maubois J.L., 1999. Dehydration by desorption and by spray drying of dairy proteins : Influence of the mineral environment. Drying Technol. 17 (7/8), 1347-1357

[2] Schuck P., Mejean S., Dolivet A., Jeantet R., 2005. Thermohygrometric sensor: a tool for optimizing the spray drying process. Innov. Food Sci. and Emerg. Technol. 6, 45-50

[3] Schuck P., Dolivet A., Méjean S., Zhu P., Blanchard E., Jeantet R., 2009. Drying by desorption: a tool to determine spray drying parameters. J Food Eng. 94,199–204

[4] Zhu P., Patel K., Lin S., Méjean S., Blanchard E., Chen XD., Schuck P., Jeantet R., 2011. Simulating industrial spray drying operations using a reaction engineering approach and a modified desorption method. Drying Technol. 29, 419-428

[5] Zhu P., Méjean S., Blanchard B., Jeantet R., Schuck P., 2011. Prediction of dry mass glass transition temperature and the spray drying behaviour of a concentrate using a desorption method. J Food Eng. 105, 460-467

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Created by Hte inra on 27 September 2011, at 14:53