Led -tekniikan käyttöönotto polyakryyliamidin valmistuksessa fotoinitiaatioprosessissa

Työssä tutkittiin Kemira Chemicals Oy:n Vaasan polyelektrolyyttitehtaalla led -tekniikan käyttöönottoa polyakryyliamidin valmistamisessa fotoinitiaatiolla. Led- tekniikan käyttöönoton seuraamisella ja erilaisten mittausten tekemisellä oli tarkoitus saada uudesta teknologiasta tietoa, jonka perusteella tulevaisuuden investointiesitykset voisivat olla paremmin perusteltavissa. Työn kirjallisuusosassa käytiin läpi valaistus- ja led -tekniikan perusteita sekä polymeerien perusteita. Lisäksi polyelektrolyyttien ominaisuudet ja käyttökohteet käytiin läpi. Kirjallisuusosan lopussa käytiin läpi polymerointia, fotoinitiaatiota ja vapaiden radikaalien toimintaa. Myös kustannuslaskentaa selvitettiin. Mittausten ja vertailujen perusteella voitiin todeta led -valojen vaikuttaneen positiivisesti prosessin toimintaan ja lopputuotteiden laatuun. Tämänlaisessa sovelluksessa led -tekniikka ei ole kuitenkaan vielä kilpailukykyistä vanhaan teknologiaan verrattuna puhtaasti taloudellisesti ajateltuna.

Development of new halogen-free and multifunctional flame retardants

I avhandlingen undersöktes nya typer av halogenfria flamskyddsmedel. De utvecklade azoalkanföreningarna skyddar polypropenplaster mot brand även i små halter och kan samtidigt förbättra plasternas övriga egenskaper. Undersökningen har medfört viktigt kunnande i övergången från effektiva men på flera sätt problematiska bromerade flamskyddsmedel mot miljövänligare alternativ. I Auberts undersökningar framkom att speciellt symmetriska cykliska azoalkaner, såsom dicyklohexylazoföreningar, uppvisar goda flamskyddande egenskaper i polypropenprodukter. Betydande flamskydd uppnåddes vid anmärkningsvärt låga koncentrationer av föreningarna (0,5-2 vikts-%) och formuleringarna klarar DIN 4102 B2-standardtestet som mäter brandsäkerheten i byggprodukter. I doktorsavhandlingen syntetiserades även en ny, innovativ radikalgenerator, bis(1-propyloxy-2,2,6,6-tetrametylpiperidyl)-4-diazen (AZONOR), som klarade av förutom det ovannämnda testet även NF P92-505- samt det mera krävande UL 94 VTM-2-standardtestet. Förutom flamskyddande verkan uppvisade denna multifunktionella förening ett utmärkt UV-skydd i polypropenplaster. Även efter 2000 timmar av föråldring i klimatkammare kunde ingen betydande minskning av flamskyddsmedlets effekt eller förvittring av polymerfilmen observeras. Konsumtionen av plastprodukter håller på att öka. För att kunna uppfylla de nutida kraven på brandsäkerhet bör man tillsätta flamskyddsmedel till de i sig mycket brandfarliga plasterna. Internationellt forskas det mycket i att finna ersättande produkter för de allmänt använda bromerade flamskyddsmedlen. I Auberts undersökning hittades välfungerande och till sina bieffekter lindrigare föreningar för att ersätta bromerade medel. De nya föreningarna har väckt stort intresse inom den akademiska och företagsvärlden.

New families of highly efficient, halogen-free flame retardants for polypropylene (PP)

The driving forces for current research of flame retardants are increased fire safety in combination with flame retardant formulations that fulfill the criteria of sustainable production and products. In recent years, important questions about the environmental safety of antimony, and in particular, brominated flame retardants have been raised. As a consequence of this, the current doctoral thesis work describes efforts to develop new halogen-free flame retardants that are based on various radical generators and phosphorous compounds. The investigation was first focused on compounds that are capable of generating alkyl radicals in order to study their role on flame retardancy of polypropylene. The family of azoalkanes was selected as the cleanest and most convenient source of free alkyl radicals. Therefore, a number of symmetrical and unsymmetrical azoalkanes of the general formula R-N=N-R’ were prepared. The experimental results show that in the series of different sized azocycloalkanes the flame retardant efficacy decreased in the following order: R = R´= cyclohexyl > cyclopentyl > cyclobutyl > cyclooctanyl > cyclododecanyl. However, in the series of aliphatic azoalkanes compounds, the efficacy decreased as followed: R = R´= n-alkyl > tert-butyl > tert-octyl. The most striking difference in flame retardant efficacy was observed in thick polypropylene plaques of 1 mm, e.g. azocyclohexane (AZO) had a much better flame retardant performance than did the commercial reference FR (Flamestab® NOR116) in thick PP sections. In addition, some of the prepared azoalkane flame retardants e.g. 4’4- bis(cyclohexylazocyclohexyl) methane (BISAZO) exhibited non-burning dripping behavior. Extrusion coating experiments of flame retarded low density polyethylene (LDPE) onto a standard machine finished Kraft paper were carried out in order to investigate the potential of azoalkanes in multilayer facings. The results show that azocyclohexane (AZO) and 4’4-bis (cyclohexylazocyclohexyl) methane (BISAZO) can significantly improve the flame retardant properties of low density polyethylene coated paper already at 0.5 wt.% loadings, provided that the maximum extrusion temperature of 260 oC is not exceeded and coating weight is kept low at 13 g/m2. In addition, various triazene-based flame retardants (RN1=N2-N3R’R’’) were prepared. For example, polypropylene samples containing a very low concentration of only 0.5 wt.% of bis- 4’4’-(3’3’-dimethyltriazene) diphenyl ether and other triazenes passed the DIN 4102-1 test with B2 classification. It is noteworthy that no burning dripping could be detected and the average burning times were very short with exceptionally low weight losses. Therefore, triazene compounds constitute a new and interesting family of radical generators for flame retarding of polymeric materials. The high flame retardant potential of triazenes can be attributed to their ability to generate various types of radicals during their thermal decomposition. According to thermogravimetric analysis/Fourier transform infrared spectroscopy/MS analysis, triazene units are homolytically cleaved into various aminyl, resonance-stabilized aryl radicals, and different CH fragments with simultaneous evolution of elemental nitrogen. Furthermore, the potential of thirteen aliphatic, aromatic, thiuram and heterocyclic substituted organic disulfide derivatives of the general formula R-S-S-R’ as a new group of halogen-free flame retardants for polypropylene films have been investigated. According to the DIN 4102- 1 standard ignitibility test, for the first time it has been demonstrated that many of the disulfides alone can effectively provide flame retardancy and self-extinguishing properties to polypropylene films at already very low concentrations of 0.5 wt.%. For the disulfide family, the highest FR activity was recorded for 5’5’-dithiobis (2-nitrobenzoic acid). Very low values for burning length (53 mm) and burning time (10 s) reflect significantly increased fire retardant performance of this disulfide compared to other compounds in this series as well as to Flamestab® NOR116. Finally, two new, phosphorus-based flame retardants were synthesized: P’P-diphenyl phosphinic hydrazide (PAH) and melamine phenyl phosphonate (MPhP). The DIN 4102-1 test and the more stringent UL94 vertical burning test (UL94 V) were used to assess the formulations ability to extinguish a flame once ignited. A very strong synergistic effect with azoalkanes was found, i.e. in combination with these radical generators even UL94 V0 rate could be obtained.

Hapettavan BIMODES-mikrobientorjuntamenetelmän vaikutukset paperikoneella

The aim of this study was to examine the effects of oxidising BIMODES microbiological control program on three paper machine process. The chemicals used in BIMODES program are sodium hypochlorite (NaOCl) and bromo-chloro-di-methyl-hydantoin (BCDMH). The literary part of this study discusses the microbiological problems in paper making industry, describes functional mechanisms of oxidants and also introduces the BIMODES- program. In the experimental part the aim was to examine the effects of BIMODES in three different paper machines. The purpose was to find out the effects and changes in wet end chemistry, bacterial counts, in the other additives and also in the sheet defects and holes. The study also examines what are the most important measurements to control BIMODES dosing. In addition the optimal dosing level for each machine was tried to find out. It was found that there is a clear correlation between the total chlorine level and bacterial counts. Changes in the BIMODES dosing level can be measured by redox potential, but the correlation is very poor. BIMODES program doesn’t have straight influence to pH values, but if dosage level is too low the bacterial activity can affect degreasing in the pH value. In this study couldn’t find any consequential effects for the other additives by using BIMODES. In addition the optimal dosing levels were found and by following correct halogen levels it is possible to decrease bacterial levels for very low level.

Ajax: Web-sovellusten uudet mahdollisuudet

Tässä työssä selvitettiin Ajax-tekniikan tilannetta web-sovellusten kehityksessä. Sitä varten kehitettiin demosovellus, jonka avulla tekniikoiden käyttökelpoisuutta voitiin arvioida. Samalla työssä on esitelty eri tekniikoita, jotka liittyvät kiinteästi Ajax-sovellusten toteuttamiseen. Demosovellus tehtiin vapaalla LAMP (Linux, Apache, MySQL and PHP) -alustalla. Työssä on arvioitu Ajax-tekniikan käyttökelpoisuutta ja ongelmia nykyisen webin, web-kehittäjien, käytössä olevien selainten ja käyttäjien kannalta. Lopussa on myös pohdittu hieman webin tulevaisuutta ja Ajaxin osaa siinä.

Biotransformation and endocrine disruptive effects of contaminants in ringed seals - implications for monitoring and risk assessment

Marine mammals are exposed to persistent organic pollutants (POPs), which may be biotransformed to metabolites some of which are highly toxic. Both POPs and their metabolites may lead to adverse health effects, which have been studied using various biomarkers. Changes in endocrine homeostasis have been suggested to be sensitive biomarkers for contaminant-related effects. The overall objective of this doctoral thesis was to investigate biotransformation capacity of POPs and their potential endocrine disruptive effects in two contrasting ringed seal populations from the low contaminated Svalbard area and from the highly contaminated Baltic Sea. Biotransformation capacity was studied by determining the relationships between congener-specific patterns and concentrations of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs) and their hydroxyl (OH)- and/or methylsulfonyl (MeSO₂)-metabolites, and catalytic activities of hepatic xenobiotic-metabolizing phase I and II enzymes. The results suggest that the biotransformation of PCBs, PBDEs and toxaphenes in ringed seals depends on the congener-specific halogen-substitution pattern. Biotransformation products detected in the seals included OH-PCBs, MeSO₂-PCBs and –DDE, pentachlorophenol, 4-OHheptachlorostyrene, and to a minor extent OH-PBDEs. The effects of life history state (moulting and fasting) on contaminant status and potential biomarkers for endocrine disruption, including hormone and vitamin homeostasis, were investigated in the low contaminated ringed seal population from Svalbard. Moulting/fasting status strongly affected thyroid, vitamin A and calcitriol homeostasis, body condition and concentrations of POPs and their OH-metabolites. In contrast, moulting/fasting status was not associated with variations in vitamin E levels. Endocrine disruptive effects on multiple endpoints were investigated in the two contrasting ringed seal populations. The results suggest that thyroid, vitamin A and calcitriol homeostasis may be affected by the exposure of contaminants and/or their metabolites in the Baltic ringed seals. Complex and non-linear relationships were observed between the contaminant levels and the endocrine variables. Positive relationships between circulating free and total thyroid hormone concentration ratios and OH-PCBs suggest that OH-PCBs may mediate the disruption of thyroid hormone transport in plasma. Species differences in thyroid and bone-related effects of contaminants were studied in ringed and grey seals from low contaminated references areas and from the highly contaminated Baltic Sea. The results indicate that these two species living at the same environment approximately at the same trophic level respond in a very different way to contaminant exposure. The results of this thesis suggest that the health status of the Baltic ringed seals has still improved during the last decade. PCB and DDE levels have decreased in these seals and the contaminant-related effects are different today than a decade ago. The health of the Baltic ringed seals is still suggested to be affected by the contaminant exposure. At the present level of the contaminant exposure the Baltic ringed seals seem to be at a zone where their body is able to compensate for the contaminant-mediated endocrine disruption. Based on the results of this thesis, several recommendations that could be applied on monitoring and assessing risk for contaminant effects are provided. Circulating OH-metabolites should be included in monitoring and risk assessment programs due to their high toxic potential. It should be noted that endogenous variables may have complex and highly variable responses to contaminant exposure including non-linear responses. These relationships may be further confounded by life history status. Therefore, it is highly recommended that when using variables related to endocrine homeostasis to investigate/monitor or assess the risk of contaminant effects in seals, the life history status of the animal should be carefully taken into consideration. This applies especially when using thyroid, vitamin A or calcitriolrelated parameters during moulting/fasting period. Extrapolations between species for assessing risk for contaminant effects in phocid seals should be avoided.

Pienloistelamppujen johtuvat RF-häiriöt verrattuna CISPR 15 - standardin raja-arvoihin

Hehkulamput tullaan kieltämään Euroopan Unionin alueella vuoden 2016 syyskuuhun mennessä. Hehkulamput korvataan suurimmaksi osaksi pienloistelampuilla, jotka omaavat hehkulamppuihin verrattuna paremman hyötysuhteen. Pienloistelamput aiheuttavat kuitenkin häiriöitä niitä syöttävään sähköverkkoon. Tässä kandidaatin työssä mitattiin 15 erilaisen pienloistelampun aiheuttamat johtuvat RF-taajuiset häiriöt. Tuloksia verrattiin CISPR 15 – standardissa esitettyihin raja-arvoihin, joita pienloistelamppujen tulisi noudattaa. Mittaukset suoritettiin käyttämällä CISPR 16 –standardin kanssa yhteensopivaa mittavastaanotinta (Rohde & Schwarz ESHS30) sekä myöskin CISPR 16 yhteensopivaa keinoverkkoa (Rohde & Schwarz ESH2Z5). Lamput mitattiin CISPR 15 –standardin mukaisesti, muutamia poikkeuksia lukuun ottamatta. Lamppuja ei mitattu käyttämällä CISPR 15 –standardissa vaadittua lampun pidintä. Eikä lamppuja myöskään esikäytetty ollenkaan. Lukuun ottamatta yhtä pienloistelamppua, kaikki jäivät raja-arvon alapuolelle. Rajan ylittäneen lampun tulos tosin mahtuu mittavastaanottimen mittavirheeseen. Joten kyseessä ei ollut suuren suuri ylitys. Muiden tutkittujen pienloistelamppujen johtuvat RF-häiriöt ovat hyväksyttävällä tasolla ja ne tuskin tulevat aiheuttamaan ongelmia.

Energiansäästölamppujen vaikutukset pienjännitteisen sähkönjakeluverkon kuormitukseen ja häviöihin

Euroopan Unioni kieltää matalan hyötysuhteen lamppujen käyttämisen sekä sisä- että ulkovalaisimissa. Näin ollen matalan hyötysuhteen lamput, kuten perinteiset hehkulamput tulee vaihtaa paremman hyötysuhteen lamppuihin, kuten energiansäästölamppuihin. Energiansäästölampuissa 230 V, 50 Hz verkkosähkö muunnetaan valonlähteelle sopivaksi tehoelektroniikan avulla. 50 Hz perustaajuisen virran lisäksi energiansäästölamput ottavat verkosta harmonisia yliaaltoja. Harmoniset yliaallot aiheuttavat lisähäviöitä verkostokomponenteissa, kuten muuntajissa ja johdoissa. Tässä kandidaatintyössä tutkitaan millaisia vaikutuksia hehkulamppujen vaihtaminen energiansäästölamppuihin aiheuttaa pienjännitteisessä jakeluverkossa. Työssä tarkastellaan lyhyesti myös energiansäästölamppujen energiatehokkuutta, sekä sitä, millaisia rajoitteita standardit asettavat harmonisille yliaalloille.

Jeg strikker, derfor er jeg! : læring og identitet i uformelle læringsrum

The dissertation ´I knit, therefore I am!´ Learning and identity in informal space has two main purposes. The first purpose being an investigation of how new value attributions and thinking can generate novel and usable knowledge to the field of craftsmanship, and the second purpose being a display of a different and overlooked philosophical and cultural potential in a reflexive mode of expression, which is able to reflect the normative comprehension of craftsmanship. The dissertation focuses on learning and identity in informal spaces of learning and how it is possible to relate such a learning perspective to crafts training in educational establishments. The empirical foundation of this dissertation is ‘craftivism’. In the dissertation activists from the Nordic countries have been interviewed about what they do when they put up their textile graffiti on lamp posts and house walls. Three research problems are presented: 1) What stories do people who work as crafts activists, tell about ways of relating and methods of action when they make crafts? 2) What do these stories tell about learning and identity? 3) How may the research results influence training and education in craftsmanship? These questions are being asked in order to acquire new knowledge in two aspects; first aspect being knowledge about crafts in relation to techniques, tradition and the objects in crafts, and the second aspect being knowledge about learning and identity in informal spaces of learning. The dissertations theoretical foundation is post structural and sociocultural combined with hermeneutical-inspired qualitative interviews. The author’s position and pre-understanding is subject to discussion in relation to the informant; the performing activist, as the background for both of them is craftsmanship. Starting from cultural studies, it is possible to see the activist subject’s conditions of possibilities in the culture, as the activism of the sub-cultural phenomenon’s craft lights up through a performing approach to the individual’s actions. First the research material has been analysed for events of textile graffiti and possible themes in the events, after which the results have been summarised. Next the research material has been analysed for events about learning and identity due to the author’s wish of comprehending the background of and motivational force in activism. The analysis is divided in main perspectives with different dimensions. The results of the analysis show the activist subject’s construction of an individual who actively takes part in a community by e.g. creating joy, changing the world’s perception of sustainability or by feminizing the public space. By taking crafts over the borders (and away from the class room) crafts become contextualized in a novel fashion thus obtaining an independent status. In this fashion the dissertation writes itself into a new method of comprehending and performing traditional craftsmanship techniques.

Hydrometallurgical recovery of valuable metals from secondary raw materials

Wastes and side streams in the mining industry and different anthropogenic wastes often contain valuable metals in such concentrations their recovery may be economically viable. These raw materials are collectively called secondary raw materials. The recovery of metals from these materials is also environmentally favorable, since many of the metals, for example heavy metals, are hazardous to the environment. This has been noticed in legislative bodies, and strict regulations for handling both mining and anthropogenic wastes have been developed, mainly in the last decade. In the mining and metallurgy industry, important secondary raw materials include, for example, steelmaking dusts (recoverable metals e.g. Zn and Mo), zinc plant residues (Ag, Au, Ga, Ge, In) and waste slurry from Bayer process alumina production (Ga, REE, Ti, V). From anthropogenic wastes, waste electrical and electronic equipment (WEEE), among them LCD screens and fluorescent lamps, are clearly the most important from a metals recovery point of view. Metals that are commonly recovered from WEEE include, for example, Ag, Au, Cu, Pd and Pt. In LCD screens indium, and in fluorescent lamps, REEs, are possible target metals. Hydrometallurgical processing routes are highly suitable for the treatment of complex and/or low grade raw materials, as secondary raw materials often are. These solid or liquid raw materials often contain large amounts of base metals, for example. Thus, in order to recover valuable metals, with small concentrations, highly selective separation methods, such as hydrometallurgical routes, are needed. In addition, hydrometallurgical processes are also seen as more environmental friendly, and they have lower energy consumption, when compared to pyrometallurgical processes. In this thesis, solvent extraction and ion exchange are the most important hydrometallurgical separation methods studied. Solvent extraction is a mainstream unit operation in the metallurgical industry for all kinds of metals, but for ion exchange, practical applications are not as widespread. However, ion exchange is known to be particularly suitable for dilute feed solutions and complex separation tasks, which makes it a viable option, especially for processing secondary raw materials. Recovering valuable metals was studied with five different raw materials, which included liquid and solid side streams from metallurgical industries and WEEE. Recovery of high purity (99.7%) In, from LCD screens, was achieved by leaching with H2SO4, extracting In and Sn to D2EHPA, and selectively stripping In to HCl. In was also concentrated in the solvent extraction stage from 44 mg/L to 6.5 g/L. Ge was recovered as a side product from two different base metal process liquors with Nmethylglucamine functional chelating ion exchange resin (IRA-743). Based on equilibrium and dynamic modeling, a mechanism for this moderately complex adsorption process was suggested. Eu and Y were leached with high yields (91 and 83%) by 2 M H2SO4 from a fluorescent lamp precipitate of waste treatment plant. The waste also contained significant amounts of other REEs such as Gd and Tb, but these were not leached with common mineral acids in ambient conditions. Zn was selectively leached over Fe from steelmaking dusts with a controlled acidic leaching method, in which the pH did not go below, but was held close as possible to, 3. Mo was also present in the other studied dust, and was leached with pure water more effectively than with the acidic methods. Good yield and selectivity in the solvent extraction of Zn was achieved by D2EHPA. However, Fe needs to be eliminated in advance, either by the controlled leaching method or, for example, by precipitation. 100% Pure Mo/Cr product was achieved with quaternary ammonium salt (Aliquat 336) directly from the water leachate, without pH adjustment (pH 13.7). A Mo/Cr mixture was also obtained from H2SO4 leachates with hydroxyoxime LIX 84-I and trioctylamine (TOA), but the purities were 70% at most. However with Aliquat 336, again an over 99% pure mixture was obtained. High selectivity for Mo over Cr was not achieved with any of the studied reagents. Ag-NaCl solution was purified from divalent impurity metals by aminomethylphosphonium functional Lewatit TP-260 ion exchange resin. A novel preconditioning method, named controlled partial neutralization, with conjugate bases of weak organic acids, was used to control the pH in the column to avoid capacity losses or precipitations. Counter-current SMB was shown to be a better process configuration than either batch column operation or the cross-current operation conventionally used in the metallurgical industry. The raw materials used in this thesis were also evaluated from an economic point of view, and the precipitate from a waste fluorescent lamp treatment process was clearly shown to be the most promising.

Sähkön laadun tutkimus hypermarketin pysäköintihallin valaistustekniikkamuutoksessa

Talotekniikan alalla valaistusmuutoksissa LED-valaistus on nykypäivää. Valaistuksen käyttöominaisuudet ja hyödyt tekevät siitä perustellun valinnan myös suurissa kohteissa. Näistä laajemmista valaistuksen muutoksista ja niiden vaikutuksista sähkön laatuun ei ole yleisesti mittaustietoa. Tämä tutkimus perustui sähkön laadun käytännön mittauksiin valaistusmuutoksessa, jossa elohopeahöyrylampuilla toteutettu valaistus vaihdettiin LED-valaistukseen hypermarketin pysäköintihallissa. Valaistusjärjestelmän muutoksen vaikutusta sähkön laatuun tutkittiin vertailemalla mittaustuloksia vanhan ja uuden järjestelmän välillä. Tutkimuksen tarkoituksena oli osoittaa miten LED-valaistukseen siirtyminen vaikuttaa sähkön laatuun valitussa tutkimuskohteessa. Tutkimuksessa tuotettu tieto on hyödynnettävissä vastaavissa kohteissa LED-valaistukseen siirryttäessä sekä valaistuksen käyttöönoton suunnittelussa ja toteuttamisessa. Tutkimuksen tuloksia voidaan hyödyntää myös kustannusten arvioimisessa valaistavan tilan sähkönkulutuksen osalta. Tutkimus toteutettiin käyttämällä triangulaatiomenetelmää eli teemahaastattelulla, kirjallisuuskatsauksella ja käytännön mittauksilla. Näiden menetelmien tulokset tukivat tutkimukselle asetettuja hypoteeseja. Valitulla tutkimusmenetelmällä saatiin selville, että LED-valaistukseen siirtymisellä ei ollut heikentäviä vaikutuksia sähkön laatuun tutkitun kohteen valaistusjärjestelmässä. Toisaalta positiivisina vaikutuksina huomioitiin muun muassa merkittävä energian säästö, virran harmonisten häiriöiden väheneminen sekä kokonaistehokertoimen parantuminen.

Leave a light on – Terracotta lamps from Agia Paraskevi of Arachamitai, from the Classical period until Roman times

This thesis deals with terracotta lamps found at the archaeological site of Agia Paraskevi of Arachamitai during the years 2010–2014. The research questions are: What kind of lamps were used on the site and when? For what purposes were the lamps used? Where were they manufactured? In order to address these questions, a total of fifty lamps have been chosen to form the body of research material. To answer the first research question, a typology for these lamps has been created with twenty-one types and one variant, after examining various lamp typologies and previous publications. The find contexts and distribution of the lamps are both examined to test the dates for the different lamp types gathered from other publications, and to answer the question on what purposes the lamps were used on the site. Visual observation of the clay of the lamps and information on clay materials from other sites are both examined to determine the lamps' origins. The lamps in this study date from the 5th century BC to the 2nd century AD. The find contexts allow the dating of the lamps according to the other publications, but suggestions of more site-specific dates are given to some lamps. The distribution of the lamps indicates that while most were used for everyday lighting at the sanctuary, some may have had ritual connections. Most of the lamps were manufactured locally or at a nearby Arcadian site. Few lamps can be regarded as imports.

Chemistry of potassium halides and their role in corrosion in biomass and waste firing

Compared to the use of traditional fossil fuels (coal, oil, natural gas), combustion of biomass and waste fuels has several environmental and economic advantages for heat and power generation. However, biomass and waste fuels might contain halogens (Cl, Br, F), alkali metals (Na, K) and heavy metals (Zn, Pb), which may cause harmful emissions and corrosion problems. Hightemperature corrosion occurs typically on furnace waterwalls and superheaters. The corrosion of the boiler tube materials limits the increase of thermal efficiency of steam boilers and leads to costly shutdowns and repairs. In recent years, some concerns have been raised about halogen (Cl, Br, and F)-related hightemperature corrosion in biomass- and waste-fired boilers. Chlorine-related high-temperature corrosion has been studied extensively. The presence of alkali chlorides in the deposits is believed to play a major role in the corrosion observed in biomass and waste fired boilers. However, there is much less information found in literature on the corrosion effect of bromine and fluorine. According to the literature, bromine is only assumed to play a role similar to chlorine; the role of fluorine is even less understood. In this work, a series of bubbling fluidized bed (BFB) bench-scale tests were carried out to characterize the formation and sulfation behaviors of KCl and KBr in BFB combustion conditions. Furthermore, a series of laboratory tests were carried out to investigate the hightemperature corrosion behaviors of three different superheater steels (10CrMo9-10, AISI 347 and Sanicro 28) exposed to potassium halides in ambient air and wet air (containing 30% H2O). The influence of H2O and O2 on the high-temperature corrosion of steels both with and without a salt (KCl) in three gas atmospheres (2% H2O-30% O2-N2, 2% H2O-2% O2-N2 and 30% H2O-2% O2-N2) was also studied. From the bench-scale BFB combustion tests, it was found that HBr has a clearly higher affinity for the available K forming KBr than HCl forming KCl. The tests also indicated that KCl has a higher tendency for sulfation than KBr. From the laboratory corrosion tests in ambient air (also called “dry air” in Paper III and Paper IV), it was found that at relatively low temperatures (≤ 550 °C) the corrosivity of KBr and KF are similar to KCl. At 600 °C, KF showed much stronger corrosivity than KBr and KCl, especially for 10CrMo9-10 and AISI 347. When exposed to KBr or KF, 10CrMo9-10 was durable at least up to 450 °C, while AISI 347 and Sanicro 28 were durable at least up to 550 °C. From the laboratory corrosion tests in wet air (30% H2O), no obvious effect of water vapor was detected at 450 °C. At 550 °C, the influence of water vapor became significant in some cases, but the trend was not consistent. At 550 °C, after exposure with KBr, 10CrMo9-10 suffered from extreme corrosion; after exposure with KF and KCl, the corrosion was less severe, but still high. At 550 °C, local deep pitting corrosion occurred on AISI 347 and Sanicro 28 after exposure with KF. Some formation of K2CrO4 was observed in the oxide layer. At 550 °C, AISI 347 and Sanicro 28 suffered from low corrosion (oxide layer thickness of < 10 μm) after exposure with KBr and KCl. No formation of K2CrO4 was observed. Internal oxidation occurred in the cases of AISI 347 with KBr and KCl. From the laboratory corrosion tests in three different gas atmospheres (2% H2O-30% O2-N2, 2% H2O-2% O2-N2 and 30% H2O-2% O2-N2), it was found that in tests with no salt, no corrosion occurred on AISI 347 and Sanicro 28 up to 600 °C in both the “O2-rich” (2% H2O-30% O2-N2) and “H2O-rich” (30% H2O-2% O2-N2) gas atmospheres; only 10CrMo9-10 showed increased corrosion with increasing temperature. For 10CrMo9-10 in the “O2-rich” atmosphere, the presence of KCl significantly increased the corrosion compared to the “no salt” cases. For 10CrMo9-10 in the “H2O-rich” atmosphere, the presence or absence of KCl did not show any big influence on corrosion. The formation of K2CrO4 was observed only in the case with the “O2-rich” atmosphere. Considering both the results from the BFB tests and the laboratory corrosion tests, if fuels containing Br were to be combusted, the corrosion damage of superheaters would be expected to be higher than if the fuels contain only Cl. Information generated from these studies can be used to help the boiler manufacturers in selecting materials for the most demanding combustion systems.