| 1. |
- Nordberg, Åke, et al.
(författare)
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Selective desorption of carbon dioxide from sewage sludge for in-situ methane enrichment : Enrichment experiments in pilot scale
- 2012
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 37, s. 196-204
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Tidskriftsartikel (refereegranskat)abstract
- The application of in-situ methane enrichment for upgrading the biogas from anaerobic digestion to vehicle fuel or natural gas quality, has been studied in pilot scale and by computer simulation of the desorption step. Pilot plant experiments have been performed using a 19 m(3) and 15 m(3) continuously stirred tank reactor operating with municipal sewage sludge at mesophilic conditions connected respectively to a 90 dm(3) and 140 dm(3) external bubble column for selective desorption of CO2. The results show that the CH4 yield is unchanged during the experiments, and accordingly there is no evidence that the oxygen in the air used in the desorption of CO2 has a negative impact on the CH4 producing activity. The sludge recirculation system must be designed to avoid leakage of air into the digester, in order to maintain a low N-2 concentration in the biogas. At best, a biogas with a volume fraction of 87% CH4 and (p N-2 = 2% was obtained. The CH4 loss however amounted to 8%, which is unsatisfactory. The experimental results are compared with previous data in the literature and explanations are deducted for the difference in the performance. Computer simulations reveal that the sludge flow rate recirculated through the desorption column should be as low as possible to minimize the loss of CH4. An increased air flow rate through the desorption column and an increased desorption column volume will promote the desorption of CO2 and improve the ratio of CO2 to CH4 desorption.
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| 2. |
- Albero Caro, Jesus, et al.
(författare)
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Semibatch reaction crystallization of salicylic acid
- 2014
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Ingår i: Chemical engineering research & design. - : Elsevier BV. - 0263-8762 .- 1744-3563. ; 92:3, s. 522-533
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Tidskriftsartikel (refereegranskat)abstract
- Reaction crystallization of salicylic acid has been investigated by experiments and modeling. In the experimental work, dilute hydrochloric acid has been added to an agitated aqueous solution of sodium salicylate in 1 L scale, and product crystals have been characterized by image analysis. The results show that the product crystal number mean size at first increases with increasing agitation rate but then gradually decreases again at further increase in stirring rate. At lower stirring rate, larger crystals are obtained when the feeding point is located close to the agitator instead of being located out in the bulk solution. The mean crystal size increases with decreasing feeding rate and with decreasing reactant concentrations. There is a decrease in mean size with increasing feed pipe diameter. These trends in the experimental results show great similarity with previous results on benzoic acid. The experimental results have been examined by a population balance model accounting for meso and micro mixing, and crystal nucleation and growth rate dispersion. It is found that the crystallization kinetic parameter estimation is quite complex, and the objective function hyper surface contains many different minima. Hence, parameter estimation has to rely on a combination of mathematical optimization strategies and a scientific understanding of the physical meaning of the parameters and their relation to current theories. As opposed to our previous work on benzoic acid, it has not been possible to find a set of kinetic parameters that provides for a good description of all experimental data.
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| 3. |
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| 4. |
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| 5. |
- Gracin, Sandra, et al.
(författare)
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Controlling polymorphism of p-aminobenzoic acid by sonication
- 2005
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Ingår i: the 16th International Symposium on Industrial Crystallization. - : VDI verlag Dusseldorf. ; , s. 677-682
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Konferensbidrag (refereegranskat)abstract
- The influence of ultrasound on the nucleation of p-aminobenzoic acid in supersaturated aqueous solutions has been investigated. The induction time and the solid phase structure has been determined in experiments with and without ultrasound. Different sonication schemes and intensities have been evaluated. It is found that sonication leads to a much shorter and reproducible induction time. In addition, it has been found that sonication preferentially favor the formation of one of the polymorphs.
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| 6. |
- Hammer-Olsson, Roy, et al.
(författare)
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Method of purifying potassium hydroxide
- 2007
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Patent (populärvet., debatt m.m.)abstract
- Method of purifying potassium hydroxide comprising (a) providing a solution of saturated potassium hydroxide solution having a temperature in the range from about -25 to about 60 0C (b) controling the temperature of the solution in such a way that the variation in temperature is in a range from about 0 to about 5 °C/h to form crystals of potassium hydroxide (c) separating the crystals from the solution.
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| 7. |
- Munroe, Aina, et al.
(författare)
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Analysis of FII crystals of Sulphathiazole : Epitaxial growth of FII on FIV
- 2011
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Ingår i: CrystEngComm. - : Royal Society of Chemistry (RSC). - 1466-8033. ; 13:3, s. 831-834
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Tidskriftsartikel (refereegranskat)abstract
- This work describes the phenomenon of a less stable polymorph wedged as a middle layer in a more stable polymorph of sulfathiazole. Isolation of the pure FII polymorph of sulfathiazole consistently yielded crystals with a distinctive middle layer. Raman spectroscopy and X-ray diffraction have identified this middle layer as another polymorph of sulfathiazole, namely FIV. The solubilities of FII and FIV sulfathiazole are almost identical, with FIV slightly more soluble. It is thought that this causes FIV to nucleate first, followed by the epitaxial growth of FII. A morphological examination of the crystals demonstrated that the (100) face of the FII crystal matches the (101) face of the FIV crystal. It is proposed that the similarity of these faces supports the epitaxial growth of the FII polymorph on the surface of the FIV polymorph.
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| 8. |
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| 9. |
- Nordström, Fredrik, et al.
(författare)
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Phase equilibria and thermodynamics of hydroxybenzoic acid isomers
- 2005
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Ingår i: 16th International Symposium on Industrial Crystallization, Volym 3. - : V D I Verlag GmbH. ; , s. 35-40
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Konferensbidrag (refereegranskat)abstract
- Thermodynamics of ortho-, meta- and para-hydroxybenzoic acid have been investigated. Thermodynamic data were acquired through determination of solubility, enthalpy of fusion and melting temperature. The solubility of polymorphic and solvated modifications of the isomers have been determined by comprehensive measurements between 10 and 50°C in acetonitrile, acetic acid and acetone. For each isomer and modification a strong correlation was obtained between solubility and the van't Hoff enthalpy of solution. These trends were attributed to both solution and solid-state properties. The observed correlations could also be used to differentiate between solid phases.
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| 10. |
- Nordström, Fredrik, et al.
(författare)
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Primary nucleation of salicylamide
- 2008
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Ingår i: Proc. 17’th International Symposium on Industrial Crystallization. ; , s. 713-720
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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