Pokazatelji rada kružne peći u restriktivnim uvjetima proizvodnje

The heating operation of the rotating-hearth furnace involving semi-finished steel products was analysed, and specific heat consumption was determined as a function of furnace productivity. The aim was to find out how a change in productivity, which is not accompanied by a modification of the thermal regime, can affect the heating quality and surface oxidation of products.Analizirana je provedba zagrijavanja čeličnih poluproizvoda u kružnoj peći i određena je specifična potrošnja topline u ovisnosti o proizvodnosti peći. Istražen je utjecaj promjene proizvodnosti kružne peći pri nepromijenjenom toplinskom režimu na kvalitetu zagrijavanja čeličnih poluproizvoda i na oksidaciju njihove površine

Mogućnosti uspješnog poslovanja Valjaonice čeličnih cijevi u tržišnim uvjetima

Taking statistically-documentary basis as a starting point and applying adequate mathematical methods, numerical functional relations between total annual production and single production expenses, i.e. average total production expenses are defined. Functional relation between both of them with different number of employees compared to the average number of employees in the analysed period of time is also defined.Polazeći od statističko-dokumentacijske osnove i primjenom odgovarajuće matematičke metode određeni su numerički funkcionalni odnosi među ukupnom godišnjom proizvodnjom i pojedinačnim troškovima proizvodnje, odnosno prosječnim ukupnim troškovima proizvodnje. Također je određen funkcionalni odnos među jednim i drugim pri različitom broju zaposlenika u odnosu na prosječan broj zaposlenika u analiziranom razdoblju

Analiza stanja u proizvodnji čeličnih bešavnih cijevi u Željezari Sisak

The paper deals with the production of seamless steel tubes at the Sisak Steel Works in Sisak, Croatia since 1992, i.e. during the war and the postwar years. Due to operation at a greatly reduced capacity the steel mill and the rolling mill have faced major financial losses. Based on those negative experiences a way of overcoming the current state of affairs in steel production has been sought. The cost of specific energy consumption is analysed in respect to its share in the selling price of the product for the purpose of predicting the terms of operational profitability and reducing the financial losses caused by occasional drops in the production rate below the profit-making level.Prikazuje se ratno i poratno stanje od 1992. godine u proizvodnji bešavnih cijevi u Željezari Sisak. Zbog rada sa znatno manjim kapacitetom od nominalnog u čeličani i valjaonici bešavnih cijevi stvarani su znatni financijski gubici. Ta negativna iskustva poslužila su za iznalaženje načina prevladavanja postojećeg stanja u proizvodnji čelika. Analizirana je specifična potrošnja energije i njezino sudjelovanje u prodajnoj cijeni proizvoda u cilju prognoziranja rentabilnog poslovanja i stvaranja manjih financijskih gubitaka kod povremeno manje proizvodnje od rentabilne

Profil potisne peći i potrošnja goriva

Operating data for two pusher-type furnaces, old and new, of approximately identical length but having different longitudinal profiles were analysed. The old furnace had a partly inclined longitudinal profile and the new one had a rectangular longitudinal profile. Results of analysis showed a higher rate of specific fuel consumption for the old furnace than for the new one. To reduce the difference a possibility was considered of building in an air-preheating recuperator instead of relocating the burners and altering the longitudinal profile of the old furnace. Results of quantification demonstrated that by building a recuperator into the old furnace specific fuel consumption would greatly diminish and would become comparable to that of the new furnace.Analizirani su pogonski proizvodni zapisi dviju potisnih peći podjednake dužine ali različitog uzdužnog profila. Starija peć ima djelomično ukošeni uzdužni profil a novija peć pravokutni uzdužni profil. Rezultati analize su pokazali da starija peć ima veću specifičnu potrošnju goriva od novije peći. U cilju smanjenja navedene razlike razmatrana je mogućnost dogradnje rekuperatora za predgrijanje zraka umjesto analognog rješenja da se premještaju gorionici i promijeni uzdužni profil starije peći. Rezultati provedene kvantifikacije pokazuju da bi se dogradnjom rekuperatora na stariju peć znatno smanjila specifična potrošnja goriva i približila onoj novije peći

CO2 emisije u industriji čelika

Global CO2 emissions caused by the burning of fossil fuels over the past century are presented. Taking into consideration the total world production of more than 1,3 billion tons of steel, the steel industry produces over two billion tons of CO2. Reductions in CO2 emissions as a result of technological improvements and structural changes in steel production in industrialized countries during the past 40 years are described. Substantial further reductions in those emissions will not be possible using conventional technologies. Instead, a radical cutback may be achieved if, instead of carbon, hydrogen is used for direct iron ore reduction. The cost and the ensuing CO2 generation in the production of hydrogen as a reducing agent from various sources are analysed.Prikazane su globalne emisije ugljičnog dioksida tijekom proteklog stoljeća izazvane izgaranjem fosilnih goriva. Uzimajući u obzir ukupnu svjetsku proizvodnju čelika od više nego 1,3 milijardu tona, čelična industrija proizvodi preko dvije milijarde tona CO2. Opisana su smanjenja emisija CO2 tijekom posljednjih 40 godina u proizvodnji čelika industrijski razvijenih zemalja poboljšanjem učinkovitosti i strukturalnim promjenama. U postojećim tehnologijama daljnje bitno smanjenje CO2 emisija neće biti moguće. Radikalno smanjenje moguće je postići zamjenom ugljika vodikom u postupku izravne redukcije željezne rudače. Provedena je analiza cijena i popratnog generiranja CO2 u proizvodnji vodika kao redukcijskog sredstva iz različitih izvora

Mogućnosti uspješnog poslovanja Valjaonice čeličnih cijevi u tržišnim uvjetima

Taking statistically-documentary basis as a starting point and applying adequate mathematical methods, numerical functional relations between total annual production and single production expenses, i.e. average total production expenses are defined. Functional relation between both of them with different number of employees compared to the average number of employees in the analysed period of time is also defined.Polazeći od statističko-dokumentacijske osnove i primjenom odgovarajuće matematičke metode određeni su numerički funkcionalni odnosi među ukupnom godišnjom proizvodnjom i pojedinačnim troškovima proizvodnje, odnosno prosječnim ukupnim troškovima proizvodnje. Također je određen funkcionalni odnos među jednim i drugim pri različitom broju zaposlenika u odnosu na prosječan broj zaposlenika u analiziranom razdoblju

Tehnološki pokazatelji rada kružne peći u uvjetima diskontinuirane proizvodnje

Quality heating of the steel charge to be rolled into seamless tubes in the rotating-hearth furnace requires continuous operation of the pilger mill. Interruption of the charging schedule leads to impaired charge heating process. Prolonged heating time causes a rise in the charge temperature above the limit values, and that in turn brings to a larger quantity of scale formed on the charge surface. Final result is loss of metal and overheating of the charge accompanied by increased fuel consumption and lower furnace productivity.Kvalitetno zagrijavanje čeličnog uloška u kružnoj peći zbog njegove prerade u bešavne cijevi zahtijeva kontinuirani rad pilger valjaonice. Promjene vremenskog perioda ulaganja dovodi do narušavanja tehnološkog procesa zagrijavanja uloška. Porast vremena zadržavanja uloška u peći dovodi do porasta njegove temperature iznad neke granične vrijednosti, a ovo pak dovodi do porasta količine formirane ogorine na površini uloška. Konačni rezultat je gubitak metala, pregrijavanje uloška uz povećanu potrošnju goriva i smanjenje proizvodnosti peći

Methodological framework for an integrated multi-scale vulnerability and resilience assessment

The deliverable illustrates the methodological framework to assess vulnerability and resilience across different temporal and spatial scales, acknowledging the different domains where the latter may manifest, and in particular in the natural and the built environment, allocating a large importance to the so called “critical infrastructures”, in social and economic systems. A set of four matrices has been developed to identify what aspects should be looked at before the impact, that is to say what shows the potential ability or inability to cope with an extreme; at the impact, addressing in particular the capacity (or incapacity) to sustain various types of stresses (in the form of acceleration, pressure, heat…); in the time immediately after the impact, as the ability (or inability) to suffer losses and still continue functioning; and in the longer term of recovery, as the capacity to find a new state of equilibrium in which the fragilities manifested during and after the impact are addressed. Developing the framework, a particular attention has been paid to the relationships among systems within the same matrix and among matrices, across spatial and temporal scales. A set of matrices has been developed for different natural hazards, including in particular landslides and floods, trying to include as much as possible what past cases, the international literature and prior experience of involved partners have indicated as relevant parameters and factors to look at. In this regard, the project builds on the state of the art, embedding what has been learned until now in terms of response capacity to a variety of stresses and in the meantime identifying gaps to be addressed by future research

Profil potisne peći i potrošnja goriva

Operating data for two pusher-type furnaces, old and new, of approximately identical length but having different longitudinal profiles were analysed. The old furnace had a partly inclined longitudinal profile and the new one had a rectangular longitudinal profile. Results of analysis showed a higher rate of specific fuel consumption for the old furnace than for the new one. To reduce the difference a possibility was considered of building in an air-preheating recuperator instead of relocating the burners and altering the longitudinal profile of the old furnace. Results of quantification demonstrated that by building a recuperator into the old furnace specific fuel consumption would greatly diminish and would become comparable to that of the new furnace.Analizirani su pogonski proizvodni zapisi dviju potisnih peći podjednake dužine ali različitog uzdužnog profila. Starija peć ima djelomično ukošeni uzdužni profil a novija peć pravokutni uzdužni profil. Rezultati analize su pokazali da starija peć ima veću specifičnu potrošnju goriva od novije peći. U cilju smanjenja navedene razlike razmatrana je mogućnost dogradnje rekuperatora za predgrijanje zraka umjesto analognog rješenja da se premještaju gorionici i promijeni uzdužni profil starije peći. Rezultati provedene kvantifikacije pokazuju da bi se dogradnjom rekuperatora na stariju peć znatno smanjila specifična potrošnja goriva i približila onoj novije peći