[Kirja-arvostelu]

Kirjallisuusarvostelu

Kertomus sahasta ja modernisaatiosta

Kirjallisuusarvostelu

Lintu on toivon merkki

Kirjallisuusarvostelu

Hegelin feministinen tulkinta

Kirjallisuusarvostelu

Ainutlaatuinen arviointikulttuurimme

Kirjallisuusarvostelu

Towards sustainable Iron- and steelmaking with economic optimization

The iron and steelmaking industry is among the major contributors to the anthropogenic emissions of carbon dioxide in the world. The rising levels of CO2 in the atmosphere and the global concern about the greenhouse effect and climate change have brought about considerable investigations on how to reduce the energy intensity and CO2 emissions of this industrial sector. In this thesis the problem is tackled by mathematical modeling and optimization using three different approaches. The possibility to use biomass in the integrated steel plant, particularly as an auxiliary reductant in the blast furnace, is investigated. By pre-processing the biomass its heating value and carbon content can be increased at the same time as the oxygen content is decreased. As the compression strength of the preprocessed biomass is lower than that of coke, it is not suitable for replacing a major part of the coke in the blast furnace burden. Therefore the biomass is assumed to be injected at the tuyere level of the blast furnace. Carbon capture and storage is, nowadays, mostly associated with power plants but it can also be used to reduce the CO2 emissions of an integrated steel plant. In the case of a blast furnace, the effect of CCS can be further increased by recycling the carbon dioxide stripped top gas back into the process. However, this affects the economy of the integrated steel plant, as the amount of top gases available, e.g., for power and heat production is decreased. High quality raw materials are a prerequisite for smooth blast furnace operation. High quality coal is especially needed to produce coke with sufficient properties to ensure proper gas permeability and smooth burden descent. Lower quality coals as well as natural gas, which some countries have in great volumes, can be utilized with various direct and smelting reduction processes. The DRI produced with a direct reduction process can be utilized as a feed material for blast furnace, basic oxygen furnace or electric arc furnace. The liquid hot metal from a smelting reduction process can in turn be used in basic oxygen furnace or electric arc furnace. The unit sizes and investment costs of an alternative ironmaking process are also lower than those of a blast furnace. In this study, the economy of an integrated steel plant is investigated by simulation and optimization. The studied system consists of linearly described unit processes from coke plant to steel making units, with a more detailed thermodynamical model of the blast furnace. The results from the blast furnace operation with biomass injection revealed the importance of proper pre-processing of the raw biomass as the composition of the biomass as well as the heating value and the yield are all affected by the pyrolysis temperature. As for recycling of CO2 stripped blast furnace top gas, substantial reductions in the emission rates are achieved if the stripped CO2 can be stored. However, the optimal recycling degree together with other operation conditions is heavily dependent on the cost structure of CO2 emissions and stripping/storage. The economical feasibility related to the use of DRI in the blast furnace depends on the price ratio between the DRI pellets and the BF pellets. The high amount of energy needed in the rotary hearth furnace to reduce the iron ore leads to increased CO2 emissions.

Buller- och vibrationsbekämpning vid planering av markanvändningen

Planläggning är en central metod för att påverka buller- och vibrationsbekämpning. Genom planläggningen kan man förhindra eller bidra till uppkomsten av buller- och vibrationsproblem. Närings-, trafikoch miljöcentralen i Nyland har tagit fram ett redskap av typen ”Best practise guide”, en kunskapskälla med rekommendationer om hur buller och vibrationer ska beaktas när markanvändningen planeras. Publikationen baserar sig på den praxis som utvecklats inom ELY-centralens planstyrning. Utkastet till guide sändes på remiss till Miljöministeriet, planläggnings- och miljövårdsenheterna i 22 kommuner, andra ELY-centraler, Nylands förbund samt tre ledande konsultbyråer i branschen. Texten kompletterades och sågs över utifrån kommentarerna. Praktiska spelregler för bullerkämpning underlättar arbetet och minskar behovet av prövning i enskilda fall. I guiden har man försökt hitta spelregler för sådana frågor som återkommit i överläggningarna om planer. Dessutom innehåller den grunder för buller- och vibrationsbekämpning vid planering av markanvändningen samt en sammanställning av de planbeteckningar som gäller saken. Publikationen innehåller kapitel om - lagar och föreskrifter på lägre nivå om saken, - bullerutredningar, - allmänna principer för beaktande av buller vid planering av markanvändningen i detaljerad anvisningar för olika delområden, - beteckningar och bestämmelser för buller samt - vibrationer och stomljud. Guiden jämte anvisningar är avsedd att underlätta skötseln av buller- och vibrationsfrågor i samband med planering av markanvändningen.