Being a decision-making process, software evaluation and selection is complicated, time-consuming, costly and also critical to the success of the project/work/organization. In this study, evaluation and selection of customized software which are used to identify the physical effect (explosion, fire and toxic emission) distances for industrial establishments containing, using or storing hazardous chemicals has been considered. These software are called the “Hazard Analysis and Consequence Modeling” (HACM) software in the literature. This study first prepared Likert scale-based questionnaires which were distributed to Environmental Health and Safety (EHS) professionals to obtain their opinions. Likert scale was used with Analytic Hierarchy Process (AHP) method in the processing of data obtained from questionnaires in order to get over the inconsistency problem of pairwise comparison matrices. The Likert scale-based AHP method was used to determine the weights of the criteria, and Preference Ranking Organization METHod for Enrichment Evaluations (PROMETHEE) method was used to obtain the final ranking. PROMETHEE method was preferred for having the opportunity of evaluating the binary “Yes–No” questions in the solution process. Finally, application results were given to illustrate the proposed method by using the PROMETHEE software “Visual PROMETHEE 1.4.0.0”.
Anahtar kelimeler
AbstractIn this study, consequences analysis were performed with ALOHA Software for hazardous chemicals which were flammable substance (methane), toxic liquid (ethylene diamine) and toxic gas (methyl chloride). Analysis were carried out for special cases obtained by changing an atmospheric parameter in each of considering the average conditions of Kocaeli with the same amount of substance (1000 kg / s). Hazard source was assumed as a direct source and effect distances were identified for each specific case in the region of toxic area, flammable area and blast area of vapor cloud. The largest effect distance values (> 10 km) were obtained for toxic liquid (ethylene diamine). Among the examined parameters the most significant changes were determined for flammable substance (methane) with a change of weather stability class and the effect distances values were identified with an approximate 2-fold increase. It was indicated that the effect distances decreased with increasing the wind speed for all of the chemicals. The largest effect distance values were obtained on water environment for all chemicals among the rural, urban/forest area and water environment. It was determined that wind direction and humidity did not change the effect distance values for the three chemicals. It was shown that there was effect of air cloudiness on flammable substance (methane) effect distances in the entire threat zone. It was determined that atmospheric options, especially wind speed, atmospheric stability class and ground roughness, had significant effects on the effect distances within the threat zones for the selected three hazardous chemicals.
Yangın, patlama ve toksik yayılım etkileri meydana getiren tehlikeli kimyasalların kullanımı kadar taşınımı/sevkiyatı oldukça önemlidir. Bu çalışmada, ülkemiz denizyolu taşımacılığı tehlikeli madde kaynaklı kazaların nedenlerinin belirlenmesi amaçlanmıştır. Öncelikle, Ana Arama Kurtarma Koordinasyon Merkezi (AAKKM) 2001-2016 verileri detaylı olarak değerlendirilmiş, tehlikeli madde taşıması muhtemel gemi kaza/olayları ve tehlikeli madde kaynaklı yangın ve patlama ile sonuçlanan kaza/olaylar seçilerek istatistikler tespit edilmiştir. Haziran 2005 sonrasına ait tehlikeli madde kaynaklı yangın ve patlama yaşanan 43 kaza/olaydan 16'sının tehlikeli yük taşımacılığı ile ilgili olduğu belirlenmiştir. Tehlikeli yük ile dolu gemilerde en fazla yük yangının kazaya neden olduğu görülmüştür. 2005 yılı öncesi ise bu kaza/olayların bilinen nedenleri elektrik arızası ve kıvılcım kaynaklı olarak tespit edilmiştir. İkinci aşamada tehlikeli madde/yük taşımacılığı ile ilgili kaza/olayların nedenleri hata ağacı ile analiz edilmiştir. Tehlikeli madde kaynaklı yangın ve patlama ile sonuçlanan mevcut kaza/olayların insan, makine arızası, ısıl reaksiyon ve elektrik arızası temelinde gerçekleştiği belirlenmiştir. Çalışma sonuçlarının, konuya yönelik acil durum planlarının ve ilgili kaza veri kaydının daha etkin gerçekleştirilmesine katkı sağlayacağı düşünülmektedir.
ÖZETBu çalışmada, Cr/MCM-41 katalizörü üzerinde izobütan dehidrojenasyonu için reaksiyon mekanizmasının belirlenmesi amaçlanmıştır. Mekanizma çalışmalarına başlamadan önce deneysel reaksiyon hızlarının konsantrasyon ile değişimi değerlendirilmiş ve yüzey reaksiyonu kontrolünün önemli olduğu belirlenmiştir. Deneysel olarak belirlenen reaksiyon kinetik üssünün 1-2 arasında değişim göstermesi yüzey reaksiyonunun mono veya bimoleküler olabileceğini düşündürmüş, bu nedenle çok sayıda mekanizma çalışması arasından yüzey reaksiyon kontrollü (Model I&Model II) basit reaksiyon mekanizmaları üzerinde çalışılmıştır. Üs kuralına dayanan, çeşitli parametrelerin indirgenmesi ile elde edilen denklemler üzerinden de model (Model III) çalışması yürütülmüştür. Model çalışmalarına ait parametrelerin tahmininde SPSS 17,0 (Windows Evaluation Version) programından yararlanılmış doğrusal olmayan regresyon analizleri yapılmıştır. Model sonuçları ile deneysel reaksiyon hızı değerleri arasındaki en iyi uyum, bimoleküler yüzey reaksiyon kontrollü mekanizmada (Model I) belirlenmiştir. Reaksiyon için tahmin edilen aktivasyon enerjisi (49-55 kJ/mol) ve adsorpsiyon denge sabiti (1-3) parametre değerleri literatür ile uyumlu bulunmuştur.Anahtar Kelimeler: İzobütan dehidrojenasyonu, Cr/MCM-41, reaksiyon mekanizması, SPSS
REACTION MECHANISM RESEARCH FOR ISOBUTANE DEHYDROGENATION ABSTRACTIn this study, determination of the reaction mechanism on Cr/MCM-41 catalyst for isobutane dehydrogenation was aimed. The change of experimental reaction rate values with concentration was evaluated before the beginning of the mechanism studies and it was determined that it was important to control surface reactions. The reaction order (n) obtained by experimantally for isobutane dehydrogenation showing exchanges between 1-2 indicated that surface reactions would be mono or bimolecular, so surface reaction controlled basic reaction mechanisms (Model I&Model II) were studied among many mechanism studies. On the equations obtained by reduction of various parameters (Model III) based on the rule of order were also studied. Nonlinear regression analysis were carried out to estimate the parameters of the model studies utilizing the SPSS 17.0 program (Windows Evaluation Version). The best agreement with the experimental reaction rate values was determined on the bimolecular surface reaction controlled mechanism (Model I). Parameter values of activation energy (49-55kj / mol) and the adsorpsion equilibrium constants (1-3) estimated for isobutane dehyrogenation reaction were consistent with the literature.
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