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- Brämming, Mats, et al.
(författare)
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BOS vessel vibration measurement for foam level detection
- 2011
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Ingår i: ISIJ International. - : Iron and Steel Institute of Japan. - 0915-1559 .- 1347-5460. ; 51:1, s. 71-79
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Tidskriftsartikel (refereegranskat)abstract
- In the BOS process liquid slag together with dispersed metal droplets, solid particles and process gases form an expanding foam. Certain process conditions may lead to excessive foam growth, forcing foam out through the vessel mouth, an event commonly known as 'slopping'. Slopping results in loss of valuable metal, equipment damage and lost production time. In the early 1980s a system for foam level and slopping control was installed at SSAB's steel plant in Luleå, a system based on the correlation between BOS vessel vibration in a narrow low frequency band and foam development. The technique, in this case with an accelerometer mounted on the trunnion bearing housing, soon showed its usefulness, for example when adapting existing lance patterns to a change in oxygen lance design from a 3-hole to a 4-hole nozzle. Estimating the actual foam height in the BOS vessel was of great importance in the recently completed RFCS funded research project "IMPHOS" (Improving Phosphorus Refining). Based on the earlier positive experiences, it was decided to further develop the vessel vibration measurement technique. Trials on an industrial size BOS vessel type LD/LBE have been carried out, this time with a tri-axial accelerometer mounted on the vessel trunnion. FFT spectrum analysis has been used in order to find the frequency band with best correlation to the foam level development. The results show that there is a correlation between vessel vibration and foam height that can be used for dynamic foam level and slopping control. © 2011 ISIJ.
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- Brämming, Mats, et al.
(författare)
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Comparison between vessel vibration and audiometry for slopping control in the top-blown BOS process
- 2011
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Ingår i: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 82:6, s. 683-692
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Tidskriftsartikel (refereegranskat)abstract
- Excess slag foam growth is a frequent problem in the BOS process. In the worst case, foam is forced out of the vessel and this phenomenon, commonly called slopping, not only results in loss of valuable metal yield but also in equipment damage and lost production time. In order to minimize slopping, accurate estimation of the foam level inside the vessel is an important part of BOS process control. In the top blown BOS vessel, slopping control is achieved using both static and dynamic measures. The most common implemented technique for dynamic foam height estimation and slopping control is the audiometer system. An alternative method, vessel vibration monitoring, has been investigated as part of the work in a RFCS funded research project called IMPHOS. In order to judge the usefulness of this method, parallel vibration and audio measurements have been carried out on 130 tonne as well as on 300 tonne BOS vessels. The results show that during stable process conditions there is good agreement between the two methods with regard to foam height estimation and, as vessel vibration and audiometry are largely independent of each other, a combination of the two is likely to increase significantly the accuracy of slopping prediction. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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- Ehn, B.-M., et al.
(författare)
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Modification of IgE Binding during Heat Processing of the Cow's Milk Allergen ?-Lactoglobulin
- 2004
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 52:5, s. 1398-1403
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Tidskriftsartikel (refereegranskat)abstract
- The effect of heat treatment on the IgE binding ability of ?-lactoglobulin, as pure protein or in whole milk, was studied by inhibition of IgE antibody binding using FEIA-CAP inhibition. A slight but significant decreased IgE binding was seen between unheated and heat-treated ?-lactoglobulin solution at 74 °C (IC50 = 2.03 and 3.59 ?g/mL, respectively, p = 0.032). A more pronounced decrease was found at 90 °C with an IC50 of 8.45 ?g/mL (p = 0.014). The inhibition of IgE binding of milk after heat treatment at 90 °C was also significantly decreased (p = 0.007). However, at all heat treatments, a similar total amount of IgE antibodies could be inhibited at a sufficiently high concentration of ?-lactoglobulin. The inhibiting ability of ?-lactoglobulin was significantly impaired in some fermented acidified milk products such as yogurt as compared to that in nonfermented milk (p < 0.001). There was only a small difference of IgE binding between the native forms of genetic variants A and B.
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- Ekstrand, Bo, et al.
(författare)
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Lipase Activity and Development of Rancidity in Oats and Oat Products Related to Heat Treatment during Processing
- 1993
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Ingår i: Journal of Cereal Science. - : Elsevier BV. - 0733-5210 .- 1095-9963. ; 17:3, s. 247-254
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Tidskriftsartikel (refereegranskat)abstract
- A pilot plant process simulation of dry and wet hydrothermic treatment of oats was performed in order to study the effect of the different process steps on lipase activity and the storage stability of the fat phase. A comparison was made between oats that had passed through a dry kiln treatment prior to steam preparation and oats that had only been steam-treated. Samples were taken after step in the process as well as during storage at +30°C for up to 44 weeks. The lipase activity disappeared after steam preparation, but not after the dry-heat treatment used in this process experiment. The fat phase was analysed with regard to the amount of free fatty acids (FFA) and the content of individual fatty acids. The initial content of FFA was about 8-9%. The hydrolysis of fat, giving an increase in the amount of FFA, took place in all the stored samples, but was much more pronounced in the samples that had not undergone dry- heat treatment. In the dry-heat-treated samples, the FFA concentration reached a maximum at 13-15% after 16 weeks of storage. In the samples that had not been dry- heat-treated, the FFA reached over 30% in whole oat grains after 16 weeks of storage and continued to increased to over 40% after 30 weeks of storage. In the flour the FFA concentration was lower than in whole grains. Unexpectedly, lipolysis in this case was more pronounced in the whole kernels than in the flour samples. Lipolysis was not related to the measured remaining lipase activity. Head-space analyses of hexanal indicated that the formation of volatile lipid oxidation products was dependent on the process design, but the hexanal concentration was not related to the amount of FFA.
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