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- Herstad-Svärd, S., et al.
(författare)
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Ramprogram – Åtgärder för samtidig minimering av alkalirelaterade driftproblem, Etapp 2
- 2007
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Combustion of an increasing amount of biofuel and waste woods has resulted in certainenvironmental advantages, including decreased emissions of fossil CO2, SO2 andmetals. On the other hand, a number of chloride and alkali related operational problemshave occurred which are related to combustion of these fuels.Alkali related operational problems have been studied in a project consisting of twoparts. The overall scope has been to characterise the operational problems and to studymeasures to minimise them. The first part was reported in Värmeforsk report 997 wherethe results were summarised in a table of different measures. In part two, additionalmeasures have been included in the test plan and initial corrosion has been studiedlinked to the different measures. The tests have also in part two been carried out at the12 MW CFB boiler at Chalmers. The effect of the selected measures has beeninvestigated concerning both deposit formation and bed agglomeration, and at the sametime emissions and other operational conditions were characterised.The second part of the project has among other things focused on:• To investigate measures which decrease the content of alkali and chloride in thedeposits, and consequently decrease the risk for corrosion (by investigating theinitial corrosion). Focus was also on trying to explain favourable effects.• To investigate if it is possible to combine a rather low dosage of kaolin and injectionof ammonium sulphate. This was done in order to reduce both bed agglomerationand problems from deposits during combustion of fuels rich in chlorine.• To investigate if co-combustion with sewage sludge, de-inking sludge or peat withhigh ash content, could give similar advantages as conventional additives.• Investigate if ash from PFBC is possible to use as an alternative bed material.By comparing the different measures in part two, it could be concluded that cocombustionof sewage sludge gave the best overall effect. The judgement was based onthe effects concerning bed agglomeration, level of alkali chloride in the flue gas,deposits and initial corrosion. Simultaneous addition of kaolin and ammonia sulphatealso had a favourable impact both in the bed and on the alkali chlorides in the gas phase.Dosage of kaolin did not reduce the effect of injected ammonium sulphate. Cocombustionof peat could also be a very attractive alternative, but it is critical to select asuitable peat type. It is of special concern to avoid peat with a high content of calcium,since it can increase the level of alkali chlorides by reacting with available sulphur.Change of bed material to ash from PFBC can decrease problems with bedagglomeration, but there is a risk of increased deposit formation and corrosion. A boileroperated with high steam data should consequently combine the change of bed materialwith injection of ammonium sulphate or another source of sulphur.Co-combustion of de-inking sludge from pulp and paper production can reduceproblems with bed agglomeration. There is, however, an increased chance of corrosiondue to the high content of calcium. Injection of sulphates may improve the situationconcerning corrosion. The results also showed that low potassium chlorine content in the flue gas decreasesthe risk of corrosion. Increased amount of potassium chlorine content in the flue gaswill not necessary give a high amount of chlorine content in the deposits if there is sulphur in the system.Key words: agglomeration, deposits, corrosion, alkali, kaolin, ammonium sulphate,sludge
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| 2. |
- Svärd, Anna, et al.
(författare)
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Presence and utility of IgA-class antibodies to cyclic citrullinated peptides in early rheumatoid arthritis : the Swedish TIRA project
- 2008
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Ingår i: Arthritis Research & Therapy. - : Springer Science and Business Media LLC. - 1478-6354 .- 1478-6362. ; 10:4
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Tidskriftsartikel (refereegranskat)abstract
- IntroductionThe present study was carried out to assess whether IgA-class antibodies against cyclic citrullinated peptides (IgA anti-CCP) in recent-onset rheumatoid arthritis add diagnostic and/or prognostic information to IgG anti-CCP analysis.MethodsSerum samples were obtained from 228 patients with recent-onset (<12 months) rheumatoid arthritis at the time of inclusion in the Swedish TIRA cohort (Swedish Early Intervention in Rheumatoid Arthritis). Sera from 72 of these patients were also available at the 3-year follow-up. Disease activity and functional ability measures (erythrocyte sedimentation rate, serum C-reactive protein, 28-joint count Disease Activity Score, physician's assessment of disease activity, and the Swedish version of the Health Assessment Questionnaire) were registered at inclusion and at regular follow-ups during 3 years. An IgA anti-CCP assay was developed based on the commercially available IgG-specific enzyme immunoassay from EuroDiagnostica (Arnhem, the Netherlands), replacing the detection antibody by an anti-human-IgA antibody. A positive IgA anti-CCP test was defined by the 99th percentile among healthy blood donors.ResultsAt baseline, a positive IgA anti-CCP test was observed in 29% of the patient sera, all of which also tested positive for IgG anti-CCP at a higher average level than sera containing IgG anti-CCP alone. The IgA anti-CCP-positive patients had significantly higher disease activity over time compared with the IgA anti-CCP-negative patients. After considering the IgG anti-CCP level, the disease activity also tended to be higher in the IgA anti-CCP-positive cases – although this difference did not reach statistical significance. The proportion of IgA anti-CCP-positive patients was significantly larger among smokers than among nonsmokers.ConclusionAnti-CCP antibodies of the IgA class were found in about one-third of patients with recent-onset rheumatoid arthritis, all of whom also had IgG anti-CCP. The occurrence of IgA-class antibodies was associated with smoking, and IgA anti-CCP-positive patients had a more severe disease course over 3 years compared with IgA anti-CCP-negative cases. Although IgA anti-CCP analysis does not seem to offer any diagnostic information in addition to IgG anti-CCP analysis, further efforts are justified to investigate the prognostic implications.
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