Ympäristöllisten lupamenettelyjen yhden luukun lainsäädäntöhankkeen vaikutusten arviointi

Selvityksessä on arvioitu ympäristöministeriössä valmisteltavaa lainsäädäntöehdotusta ympäristöllisten lupamenettelyjen ajalliseksi yhteensovittamiseksi (ns. yhden luukun menettely). Uudistus koskisi eniten ympäristö- ja vesilupia, ympäristövaikutusten arviointia, rakennuslupaa ja kemikaaliturvallisuuslupaa. Arvioinnin perusteella investointien nopeutumisesta ja yritysten hallinnollisten kustannusten vähentymisestä johtuvat taloudelliset hyödyt jäävät vuositasolla vähäisiksi. Taloudellisten vaikutusten suuruus ja suunta riippuvat kahdesta epävarmasta tekijästä: siitä, kuinka paljon lupien käsittelyajat todellisuudessa lyhenevät sekä siitä, kuinka paljon monilupaisia hankkeita lopulta käsitellään yhdessä luukussa. Ilmeistä kuitenkin on, että lupamenettelyjen pidemmälle viety integrointi vahvistaisi vaikutuksia eli lisäisi etenkin investointien nopeutumisesta saatavia hyötyjä. Lupamenettelyjen ajallinen yhteensovittaminen vaatii toimiakseen koordinoivan viranomaisen. . Yhden luukun lupapalveluiden onnistumisen kannalta olennaista on myös sähköisen palveluympäristön toimivuus. Lainsäädäntöhankkeella ei arvioida olevan merkittäviä ympäristövaikutuksia. Kansalaisten osallistumismahdollisuuksien kannalta ajallinen yhteensovittaminen voi olla ongelmallinen, koska kansalaisten ja järjestöjen voi olla vaikea saavuttaa riittävä ymmärrys monilupaisesta hankkeesta ja valmistella sitä koskeva muistutus tai mielipide laajasta kuulemisaineistosta lyhyen kuulemisajan puitteissa. Selvityksessä on arvioitu myös YVA- ja lupamenettelyjen yhteensovittamista erityisesti tarkastelemalla ympäristövaikutusten arviointiselostuksen ja lupahakemuksen kuulemisen yhdistämistä, josta voi seurata enimmillään 3 kuukauden aikasääst

The effects of microalloying on the scale formation of AISI 304 stainless steel in walking beam furnace conditions

Abstract Austenitic stainless steel is steel alloyed with nickel and chromium. The alloying amounts of chromium and nickel, and possibly other elements, defines what type of an austenitic stainless steel it is. These types are categorised according to steel standards, such as EN and AISI. The standard defines the limits for the alloyed elements in the steel. Microalloying is used to alter the alloying amounts within the limits. The unit processing path for manufacturing steel products mostly follows the same path: after the molten steel is cast into slabs, the slabs are reheated in a furnace prior to hot rolling. Introducing a metal phase to high temperatures and an oxidising atmosphere results in oxidation and the formation of an oxide scale layer. This scale layer has a distinct formation rate and an amount and morphology based on the hold time, the conditions in the furnace and the composition of the steel. Dependent on the factors, the scale layer can be protective, easy to remove, grow at a steady rate, grow evenly, be of a simple consistency or their opposite. By introducing microalloying amounts of 35 and 55 ppm B and 400 ppm Ti in comparison to a baseline AISI 304 austenitic stainless steel, the formed oxide scale layer amount, rate and morphology in the walking beam slab reheat furnace conditions are investigated in this thesis. The atmospheres involved are O2 containing and H2O containing atmospheres, with holding times varying between 3600 and 10800 seconds and temperatures ranging from 800 to 1300 °C. Comparison is also made to B and Mo microalloyed AISI 301. In some temperatures in the O2 containing atmosphere, boron microalloying has a decreasing effect on the scale formation amount and in other cases an increasing effect. This is attributed to Si oxide formation at the metal-oxide interface. In the H2O containing atmosphere, the same decreasing effect of B microalloying is observed at higher temperatures and linked to both the Si oxide formation and Ni oxide behaviour in oxide pockets. Ti microalloying is shown to overall decrease slightly the oxide scale formation in almost all studied cases. Microalloying amounts of 35 and 55 ppm B also produced a more even metal-oxide interface during the tests.Tiivistelmä Austeniittinen ruostumaton teräs on terästä, joka on seostettu nikkelillä ja kromilla. Nikkelin, kromin ja muiden alkuaineiden seosmäärät määrittelevät minkä tyyppinen teräs on kyseessä. Eri terästyypit on kategorioitu standardien, kuten AISI ja EN mukaan. Standardi määrittelee eri seosaineiden pitoisuusrajat kullekin terästyypille. Alkuaineiden pitoisuuksien muuttamista rajojen sisällä kutsutaan mikroseostamiseksi. Terästuotantoon liittyvä yksikköprosessiketju on kutakuinkin sama kaikille teräksille: sulasta teräksestä valetut aihiot kuumennetaan ennen kuumavalssausta. Kun metallifaasi asetetaan korkeaan lämpötilaan ja hapettavaan atmosfääriin, tapahtuu hapettumista ja metallin pintaan syntyy oksidi-, eli hilsekerros. Tällä hilsekerroksella on olosuhteista riippuva ominainen muodostumisnopeus ja -määrä, sekä morfologia. Nämä kaikki ovat riippuvaisia pitoajasta uunissa, uunin olosuhteista ja teräksen koostumuksesta. Muodostunut hilsekerros voi olla suojaava, helposti irrotettava, kasvaa tasaista nopeutta, kasvaa tasaisesti, olla yksinkertainen rakenteeltaan, tai olla edellä mainittujen vastakohtia. Tässä väitöskirjassa tutkitaan 35 ppm ja 55 ppm B, sekä 400 ppm Ti mikroseostamisen vaikutuksia lähtökohtaiseen AISI 304 ruostumattomaan teräkseen. Tutkimus kohdistuu aihioiden kuumennusuunia vastaavissa olosuhteissa muodostuvan hilsekerroksen määrään, nopeuteen ja morfologiaan. Atmosfääreinä ovat O2 ja H2O sisältävät atmosfäärit, pitoajat vaihtelevat 3600 ja 10800 sekunnin välillä ja lämpötila välillä 800 °C ja 1300 °C. Muodostunutta hilsekerrosta verrataan B ja Mo seostettuun AISI 301 hilsekerrokseen. Tietyissä lämpötiloissa O2 sisältävässä atmosfäärissä boorin mikroseostamisella on hilseenmuodostusta vähentävä ja toisissa sitä lisäävä vaikutus. Tämä on sidoksissa Si oksidin muodostumiseen metalli–oksidi rajapinnalla. H2O sisältävässä atmosfäärissä sama boorin aiheuttama hilseenmuodostumista vähentävä vaikutus on havaittavissa korkeammissa lämpötiloissa kuin happea sisältävässä atmosfäärissä ja se on sidoksissa sekä Si oksidin muodostumiseen, että Ni oksidin käyttäytymiseen oksiditaskuissa. Ti mikroseostamisella havaitaan olevan lievä hilseenmuodostumismäärää alentava vaikutus kauttaaltaan lähes kaikissa olosuhteissa. Mikroseostettaessa 35 ja 55 ppm B havaitaan metalli–oksidi rajapinnan tasaisuutta edistävä vaikutus

The Atmosphere’s Effect on Stainless Steel Slabs’ Oxide Formation in a CH4-Fuelled Reheating Furnace

Utilising the oxyfuel practice for CH4-fuelled combustion has positive effects on the emissions, efficiency and cost of high temperature furnace practices. However, especially in older installations, oxyfuel usage requires retrofitting and alters the atmosphere in which the oxidation of the steel occurs, when compared to using air as the oxidiser. Stainless steel slab oxide growth during reheating was studied in different atmospheres. The simulated post-burn atmospheres from oxyfuel, lean oxyfuel and air-fuel practices were used to compare oxide-scale layer growth and morphology during simulated typical AISI 304 stainless steel slab reheating prior to hot rolling. Thermogravimetric measurements, glow discharge optical emission spectrometer (GDOES) and field-emission scanning electron microscope energy dispersive X-ray (FESEM-EDS) methodology were applied to discern differences between oxide growth and inner oxide layer morphology between the three practices. Switching from air to oxyfuel practice at a single temperature had the same increasing effect on the scale formation amount as a 25 °C temperature increase in air atmosphere. Inner oxide layer depth profiling revealed C, Si and Ni to be the main elements that differed between temperatures and atmospheres. A morphology study showed Si and Ni behaviour to be linked to breakaway oxidation

In‐depth oxide scale growth analysis of B and Ti microalloyed AISI 304 in oxygen‐containing furnace atmospheres and CH₄ burn‐simulating furnace atmospheres

Abstract The effects of boron and titanium microalloying on scale‐layer formation and structure on AISI 304 austenitic stainless steel are studied. The research is focused on a steel slab’s oxide scale formation in a reheat furnace prior to hot rolling. The studied boron microalloying amounts are 7, 35, and 55 ppm and the studied titanium microalloying amounts are <100 and 400 ppm. In‐depth temperature and atmosphere tests span from 1100 to 1300 °C for an O₂‐containing atmosphere and 1100 to 1250 °C in an H₂O‐containing atmosphere, both using 25 °C increments. Research shows that microalloying 55 ppm B reduces scale growth at above 1175 °C in an H₂O atmosphere, all microalloying elements show significant scale growth reduction at 1175 °C in an O₂ atmosphere, microalloying 35 and 55 ppm B increases scale growth amounts at above 1225 °C in an O₂ atmosphere, while microalloying 400 ppm Ti reduced it. The inhibiting effect on scale growth that results from boron microalloying is tied to silicon oxide infiltration of the steel substrate

The atmosphere’s effect on stainless steel slabs’ oxide formation in a CH₄-fuelled reheating furnace

Abstract Utilising the oxyfuel practice for CH₄-fuelled combustion has positive effects on the emissions, efficiency and cost of high temperature furnace practices. However, especially in older installations, oxyfuel usage requires retrofitting and alters the atmosphere in which the oxidation of the steel occurs, when compared to using air as the oxidiser. Stainless steel slab oxide growth during reheating was studied in different atmospheres. The simulated post-burn atmospheres from oxyfuel, lean oxyfuel and air-fuel practices were used to compare oxide-scale layer growth and morphology during simulated typical AISI 304 stainless steel slab reheating prior to hot rolling. Thermogravimetric measurements, glow discharge optical emission spectrometer (GDOES) and field-emission scanning electron microscope energy dispersive X-ray (FESEM-EDS) methodology were applied to discern differences between oxide growth and inner oxide layer morphology between the three practices. Switching from air to oxyfuel practice at a single temperature had the same increasing effect on the scale formation amount as a 25 °C temperature increase in air atmosphere. Inner oxide layer depth profiling revealed C, Si and Ni to be the main elements that differed between temperatures and atmospheres. A morphology study showed Si and Ni behaviour to be linked to breakaway oxidation

The effect of boron and titanium microalloying on the scale formation of AISI 304 austenitic stainless steel in simulated walking beam furnace conditions

Abstract The effect of microalloying boron and titanium on AISI 304 austenitic stainless steel scale formation is studied. Thermogravimetric tests simulating walking beam furnace conditions are performed at temperatures of 800, 1100, and 1300 °C for 3 h on samples of AISI 304 steels with different alloying amounts of B and Ti. Scaling at 800 °C is negligible on all the samples, while scaling is clear at 1100 and 1300 °C. The thermogravimetric results show that even in small amounts, boron and titanium have an effect on scale growth rate. FESEM microscopy and accompanying EDS analyses are used to study oxidation area element composition. The FESEM images are also used to compare the oxidation zones’ area fractions of metal, pores, and oxide between different alloying amounts for the samples of 1300 °C tests. Calculations for scale formation activation energy are done based on the thermogravimetric data. The steel sample with the lowest alloying of boron and titanium shows a noticeably different growth rate, which is nearly linear in both the 1100 and 1300 °C tests. Differences between alloying amounts in accumulated scale during the 180 min period in kg m−2 are greater at 1100 °C than they are at 1300 °C

Oxide scale formation of stainless steels with different heating methods:effect of hydrogen as fuel

Abstract The evolution from natural gas usage to new technologies, such as the use of hydrogen as fuel or electricity-based heating, strongly influences the oxidation of the stainless steel surface in the reheating furnace. Thermogravimetric tests using different simulated combustion and induction reheating conditions are performed for austenitic AISI 301, AISI 304, and ferritic AISI 444 steel grades. Simulated furnace atmospheres in combustion methods are based on methane–air, methane–oxygen, hydrogen–oxygen, and methane–hydrogen–oxygen combinations. For induction simulations, air and nitrogen are used as furnace atmospheres. The results indicate that changes in heating conditions to H2-fueled combustion or induction only have a minor influence on the oxidation of the ferritic grade; whereas, their effects on the austenitic grades are more pronounced. The transition from a methane–air to H2–oxyfuel combustion increases the total oxidation by 1.7 and 4 times for steel grades 304 and 301, respectively; therefore, grade 304 can be considered better suited for transition for H2–oxyfuel use. The shorter induction heating considerably decreases the amount of oxide scale for austenitic grades, but the nitrogen atmosphere produces a subscale inside the steel matrix, which can hinder the descaling process

Oxide scale formation of EN 1.4622 and EN 1.4828 stainless steels during annealing and descaling behavior in neutral electrolytic pickling

Abstract Oxide scale formation during short-term annealing and electrolytic pickling behavior of ferritic EN 1.4622 and austenitic EN 1.4828 stainless steels are investigated. The annealing is performed at temperatures between 1000 and 1100 °C for ferritic and 1100 and 1200 °C for austenitic steel grade under humid atmospheres in simulated industrial process. Neutral electrolytic pickling, also referred to as neutral electrochemical pickling or the Ruthner Neolyte Process, is performed in Na₂SO₄ electrolyte, and pickling efficiency is evaluated visually and by image analysis of pickled surfaces. The results show that annealing conditions have a more impactful effect on the structure and the composition of the resulting oxide in the austenitic grade within the studied condition range. The thicknesses of the ferritic scales are mainly less than 0.4 μm, while almost all austenitic scales are thicker than it. In addition, the amount of silicon oxide formation inside the steel matrix of the austenitic and ferritic grades is highly different. Longer exposure times and higher temperatures promote scale growth during annealing, resulting in inefficient electrolytic pickling for the ferritic grade. For the austenitic grade, almost all steel surfaces are still covered with oxide scale after electrolytic pickling

Effect of simulated annealing conditions on scale formation and neutral electrolytic pickling

Abstract Scale formation of AISI 304 stainless steel during annealing at temperatures between 1100 and 1200 °C under a water vapor‐containing atmosphere is studied. Characterization of the oxide scale is performed with field‐emission scanning electron microscopy–energy dispersive spectroscopy (FESEM–EDS) and glow discharge optical emission spectroscopy (GDOES) and removal of oxide scale is done via neutral electrolyte pickling. The pickling conditions are kept constant and the effect of the annealing conditions and scale properties on the pickling result are examined. The effectiveness of pickling is evaluated using analysis FESEM images taken on polished sections of pickled surfaces. Research shows that the thickness, morphology, and composition of the oxide scale are dependent on annealing temperature and time. The thicknesses of the scale formed under the established conditions vary from 0.2 to over 30 μm, and morphologies between the chromium rich oxide layer and layered scale structure formed by breakaway oxidation. The pickling response of oxide scales remains good at all annealing temperatures with the shortest exposure time