Metso Power AB

Gothenburg, Sweden

Metso Power AB

Gothenburg, Sweden

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Gourdon M.,Chalmers University of Technology | Vamling L.,Chalmers University of Technology | Andersson U.,Metso Power AB | Olausson L.,Metso Power AB
Journal of Pulp and Paper Science | Year: 2010

In industrial black liquor evaporation plants, large amounts of sodium crystals are produced every day which all have the potential to scale the evaporator surfaces. In this project, research on the crystallization during evaporation of softwood black liquor has been performed. The results are based on measurements in a research black liquor evaporator. The distribution of scale vertically along the heat transfer surface has been investigated, as well as the influence of different operating conditions, such as the circulating flow rate of black liquor (between 0.2 and 3.7 kg/ms), the residence time for the black liquor in the evaporator (between 76 and 226 s), and the temperature difference between the liquor and the heating steam (between 11 and 26 °C). The sodium scale formed during evaporation is mainly in the form of double salts of sodium carbonate and sodium sulfate. The ratio between the two salts is one important parameter affecting the crystallization and scaling. The effect of the carbonate-to-sulfate ratio has been investigated for aqueous sodium carbonate - sodium sulfate solutions. In this paper, the results of these investigations are presented and a number of industrial significances are illustrated.


Thunman H.,Chalmers University of Technology | Lind F.,Chalmers University of Technology | Breitholtz C.,Metso Power AB | Berguerand N.,Chalmers University of Technology | Seemann M.,Chalmers University of Technology
Fuel | Year: 2013

The initial experiences of using an oxygen-carrying metal oxide, ilmenite, in the 12-MWth circulating fluidized bed (CFB) boiler/gasifier system at Chalmers University of Technology are presented. The rationale for the addition of ilmenite to the solids inventory is that ilmenite has the ability to alternately take up and release oxygen, and thereby improve the distribution of oxygen throughout the furnace. As a consequence, less air is needed to maintain low emissions from carbon monoxide (CO) and unreacted hydrocarbons (HC) during the combustion of volatile-rich fuels, such as biomass. One of the conducted experiments involved only the boiler, and the reference case corresponded to operation solely with silica-sand as the bed material, while in an additional three cases, ilmenite in various amounts was added to make up to 40 wt.% of the total bed inventory. During the experiments, the concentrations of CO and nitric oxide (NO) in the convection path of the boiler were measured. The addition of ilmenite to the silica-sand decreased the concentrations of CO and NO by 80% and 30%, respectively. Additional experiments were performed in which a concentrated stream of raw gas produced in the indirect gasifier was injected into the freeboard of the boiler. In one experiment, only silica-sand was used, while 12 wt.% ilmenite was added to the bed material in a separate experiment. The concentrations of CO and HC were measured at three different heights in the boiler and at nine positions over a cross-section of the furnace. The concentrations of CO and total HC in the furnace cross-section during concomitant gasification operation were reduced by the addition of ilmenite. © 2013 Elsevier Ltd. All rights reserved.


Gourdon M.,Chalmers University of Technology | Olausson L.,Metso Power AB | Vamling L.,Chalmers University of Technology
Nordic Pulp and Paper Research Journal | Year: 2010

Crystallization measurements during semi-batch operation of a pilot evaporator have been performed. The experimental analysis is based on changes in heat transfer coefficients and crystal masses. With this method of operation, the total crystal mass as well as the distribution of the crystal mass between the circulating solution and on surfaces can be measured continuously during the evaporation. Experiments with black liquor and different black liquor model substances, all with equal carbonate-to-sulfate ratio, crystallizing burkeite have been evaluated. The results are compared to each other and to two aqueous reference solutions crystallizing dicarbonate and sodium carbonate. The results presented include solubilities and metastable limits as well as different crystallization rates and fouling rates. Generally, the supersaturation at the metastable limit observed for the different liquors was high (14-25%). All the different liquors crystallizing burkeite were seen to have significantly lower fouling rates than the reference solutions crystallizing dicarbonate and sodium carbonate. The burkeite liquors showed no specific attraction to crystallize on the heat transfer surface as the reference solutions did.


Nguyen T.D.H.,Chalmers University of Technology | Maschietti M.,Chalmers University of Technology | Belkheiri T.,Chalmers University of Technology | Amand L.-E.,Chalmers University of Technology | And 4 more authors.
Journal of Supercritical Fluids | Year: 2014

A high-pressure pilot plant was developed to study the conversion of LignoBoost Kraft lignin into bio-oil and chemicals in near-critical water (350 C, 25 MPa). The conversion takes place in a continuous fixed-bed catalytic reactor (500 cm3) filled with ZrO2 pellets. Lignin (mass fraction of approximately 5.5%) is dispersed in an aqueous solution containing K2CO3 (from 0.4% to 2.2%) and phenol (approximately 4.1%). The feed flow rate is 1 kg/h (reactor residence time 11 min) and the reaction mixture is recirculated internally at a rate of approximately 10 kg/h. The products consist of an aqueous phase, containing phenolic chemicals, and a bio-oil, showing an increased heat value (32 MJ/kg) with respect to the lignin feed. The 1-ring aromatic compounds produced in the process are mainly anisoles, alkylphenols, guaiacols and catechols: their overall yield increases from 17% to 27% (dry lignin basis) as K2CO3 is increased. © 2013 Elsevier B.V.


Gourdon M.,Chalmers University of Technology | Vamling L.,Chalmers University of Technology | Andersson U.,Metso Power AB | Olausson L.,Metso Power AB
Industrial and Engineering Chemistry Research | Year: 2010

Sodium carbonate and sodium sulfate cause problems by forming scales in black liquor evaporators, reducing heat transfer and cleaning intervals. An experimental investigation of the crystallization behavior during evaporation of different aqueous solutions of sodium carbonate and sodium sulfate has been carried out. The analysis is based on changes in heat transfer coefficients and crystal masses. The results from this work show large variation in the distribution of the crystal mass, depending on the composition of the solution. Solutions with the crystalline form of either dicarbonate or sodium carbonate exhibit high propensity to form scales on the heat transfer surface. Solutions with the crystalline form of burkeite, however, do not show the same attraction to the heat transfer surface; they are more likely to crystallize in the circulating solution. Thus, the heat transfer is not as affected as for dicarbonate or sodium carbonate. © 2010 American Chemical Society.


Karlsson E.,Chalmers University of Technology | Gourdon M.,Chalmers University of Technology | Olausson L.,Metso Power AB | Vamling L.,Chalmers University of Technology
International Journal of Heat and Mass Transfer | Year: 2013

In this study, heat transfer measurements for falling film evaporation were performed up to very high Prandtl numbers, from 10 to 2800. Black liquor, a residual stream from the pulping process, was used as an example of a fluid that can have very high Prandtl numbers. To overcome the problem with fouling, which can be severe for black liquor due to crystal formation at higher concentrations, a new measurement method has been successfully developed which enables reliable measurements. Viscosity was clearly the most important parameter for the heat transfer coefficient, while the specific mass flow rate had a weak and positive dependence. The results were compared with existing heat transfer correlations, but none of them were able to capture the heat transfer behavior of black liquor throughout the whole range of Prandtl numbers. © 2013 The Authors. Published by Elsevier Ltd. All rights reserved.

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