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An implementation-oriented heat transfer model for black liquor evaporation

Miriam Johansson (Institutionen för energi och miljö, Värmeteknik och maskinlära) ; Lennart Vamling (Institutionen för energi och miljö, Värmeteknik och maskinlära) ; Lars Olausson (Institutionen för energi och miljö, Värmeteknik och maskinlära ; Extern)
Proceedings of the International Chemical Recovery Conference 2007, May 29-June 1, 2007, Quebec City, Canada Part 1, p. 155-158. (2007)
[Konferensbidrag, refereegranskat]

To improve the energy efficiency in the pulp and paper process, thermal integration of the evaporation plant with other parts of the plant is an option. Evaporation of black liquor up to higher dry solid content gives a higher heating value of the black liquor used in the recovery boiler. A high dry solid content means that the viscosity of the black liquor becomes very high. The link between viscosity and heat transfer for black liquor is therefore interesting. Experimental and theoretical knowledge is essential for proper design of evaporators for this purpose. A simplified model for the black liquor falling-film evaporation heat transfer coefficient is suggested. Without a substantial increase in uncertainty, only dependence on mass flow rate and viscosity is included in the model. The model is created from experimental data from experiments performed with a research evaporation plant with a 4.5 m long evaporator tube. Heat transfer in falling-film evaporators has been studied by other researchers before. The falling-film black liquor evaporation heat transfer coefficient dependence on mass flow rate (in a limited mass flow rate range) and viscosity according to this study is in agreement with some of these earlier studies. Above a certain mass flow rate limit, however, the experimental heat transfer coefficient was constant or even decreased with increasing mass flow rate.

Nyckelord: falling film, evaporation, black liquor, model, correlation

Denna post skapades 2007-06-15. Senast ändrad 2015-02-11.
CPL Pubid: 42778


Institutioner (Chalmers)

Institutionen för energi och miljö, Värmeteknik och maskinlära (2005-2014)


Industriell teknik och ekonomi

Chalmers infrastruktur

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Denna publikation ingår i:

Heat Transfer and Hydrodynamics in Falling Film Evaporation of Black Liquor