University of Jyväskylä

Dissertation: 1.12.2017 Combustion Behavior of Black Liquors – Droplet Swelling and Influence of Liquor Composition (Chen)

Start date: Dec 01, 2017 12:00 PM

End date: Dec 01, 2017 03:00 PM

Location: Ylistönrinne, YlistöKem 4

Chengcong Chen picture: Li-Tang Tsai
MSc Chen Chengcong defends his doctoral dissertation in Chemistry "Combustion Behavior of Black Liquors – Droplet Swelling and Influence of Liquor Composition". Opponent Professor Esa Vakkilainen (Lappeenranta University of Technology) and custos Professor Raimo Alén (University of Jyväskylä). The doctoral dissertation is held in English.


The material for papermaking (i.e., cellulosic pulp) is made from wood that is cooked in alkaline solution. Such chemical pulping process produces a huge amount of waste liquor, namely black liquor, which contains dissolved wood materials (mainly lignin and carbohydrates-derived degradation products) together with inorganic components. At the moment, the best available technology for handling the black liquor is to burn it in a special boiler. The heat from combustion (burning) is used for production of steam and electricity that can be used in various mill activities. Also, this process recycles the cooking chemicals for pulping. In order to achieve a smooth operation of the overall process, concentrated black liquor is sprayed into the boiler as droplets, which need to travel a certain flight-path to the bottom of the boiler (char bed) during combustion. In addition to the operational parameters directing the combustion process, the chemical composition of the black liquor itself has a great effect on the burning process of the droplets.

Conventional pulp mills are converting towards modern biorefineries that produce energy, chemicals, and biomaterials from more versatile selection of renewable feedstocks by utilizing different environmentally friendly chemical and biochemical processes. For this reason, the chemical composition and burning behavior of the black liquors generated during the modern pulping processes will be greatly different from traditional black liquors. The main objectives of this thesis were to describe the behavior of black liquor droplet during combustion and to determine the changes caused by the different chemical composition of the black liquors formed in modern pulping operations. The results of this thesis can be used in the design and operation of recovery boilers installed in modern pulp mills/biorefineries.

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Chen Chencong,, +45 28 25 89 03

Communications Officer Anitta Kananen,, 040 805 4142

Jyväskylä: University of Jyväskylä, 2017, 39 p. Department of Chemistry, University of Jyväskylä, Research Report No. 206. ISSN 0357-346X, ISBN 978-951-39-7246-2, ISBN 978-951-39-7245-5. Permanent link:

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Chengcong Chen
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