the Research Of Possibility Of Obtaining Semicoke From İstanbul-yenköy Region Coals

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 1995Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 1995Bu çalışmada, İstanbul - Yeniköy bölgesi kömürlerine düşük sıcaklık koklaştırması uygulanarak; hava kirliliği açısından sorun yaratmayacak semikok elde etme olanakları araştırılmıştır. Çalışmalar, istanbul - Yeniköy bölgesi kömürleri üzerinde yürütülmüştür. Bir özel firmaya ait ocaktaki alt, orta ve üst damarlardan temsili bir şekilde numune alınmış ve özellikleri birbirine yakın olduğu için üç damar numunesi harmanlanmıştır. Deneysel çalışmalarda harman numunesinin, öncelikle, fiziksel ve kimyasal özellikleri belirlenmiştir. Kömür numunesinin kuru baza göre; %32.5 rutubet, %12.30 kül, %46.57 uçucu madde, %40.82 sabit karbon, %1.88 toplam kükürt, %1.05 yanabilir kükürt içerdiği ve üst ısıl değerin ise 5426 Kcal/kg olduğu belirlenmiştir. -100 mm boyutundaki kömüre yüzdürme ve batırma uygulanmış ve ancak ince boyutlarda zenginleştirilebileceği anlaşılmıştır. Düşük sıcaklık koklaştırması deneylerinde, -100 + 19 mm tuvenan ile -19 + 1 mm boyut grubunda jig ve sarsıntılı masadan elde edilen temiz kömürün birbirine karıştırılması ile elde edilen ürün kullanılmıştır. Yapılan düşük sıcaklık koklaştırması deneylerinde sıcaklık, tane boyutu ve sürenin koklaştırma üzerine etkileri incelenmiştir. Deneylerde, -50+19 mm, -19+10 mm ve -10+1 mm boyut gruplarına ayrılan kömürler, 1500 cm3 hacimli ve sabit yataklı koklaştırma firınında 400, 500, 600, 700 °C sıcaklıklarda; 20, 40, 60, 80, 100, 120 dak. sürelerle koklaştırmaya tabi tutulmuş ve İstanbul - Yeniköy bölgesi kömürleri için en iyi koklaştırma koşullan saptanmıştır. Ayrıca, ısıl işlemler sonucu ince boyutlara (-10 mm) inen semikokun briketlenerek boyutunun büyütülmesi olanakları araştırılmış ve bu amaç doğrultusunda tane boyutu, presleme yükü ve bağlayıcı madde oranlarının briketlemeye etkisi belirlenmiştir. Düşük sıcaklık koklaştırmasın deneylerinden en önemli parametrenin sıcaklık olduğu sonucuna varılmış ve koklaştırma sıcaklığı olarak 650 °C seçilmiştir. Koklaşma süresinin saptanmasında kömürdeki katranın uzaklaştırılması dikkate alınmıştır ve % 1 5 dolayında uçucu madde içeren semikok ürünleri elde etmek için 50 - 76 dakikalık koklaştırma süresinin yeterli olduğu belirlenmiştir. Ayrıca, en iyi koşullarda elde edilen semikokun yanabilir kükürt içeriği %0.40'a inmiş; sabit karbon içeriği %68.09'a ve sabit karbona bağlı olarak da ısıl değeri 6404 Kcal/kg'a yükselmiştir. Briketleme deneylerinde semikokun boyutu lmm'nin altına indirildikten sonra bu ürüne %12 melas, %3 kireç ilavesiyle 30 ton presleme yük altında oluşturulan briketin en yüksek shatter indeksine (1505) sahip olduğu saptanmıştır. En iyi koklaştırma koşullarında yapılan deneyde, kömürün %60.2'sini semikok, %20.3'ünü gaz ve %19.5'ini de sıvı ürünlerin oluşturduğu belirlenmiştir.In this study, the possibility of obtaining semicoke that would not create any problems in terms of air pollution has been researched by applying the low temperature coking on Istanbul- Yeniköy region coals. Experiments have been carried out for samples taken from Istanbul- Yeniköy region coals. Some 500 kg. samples were taken from bottom, middle and top seams which belong to a private mining company. After these samples have been reduced to 10 mm below, they have been subjected to experiments. The result of ash and sulphur distribution has been specified in according with their sizes. From the results, particles have completely constituted big size and had low ash content. As their sizes reduces, so the ash content increases, too. The sulphur content of top seams has been diminished when their sizes are reduced whereas this case has not been met for other seams. The sulphur content of various size coals for bottom seams has increased 3-5 times compared to other seams. As a results of tests made on coal seams, it was observed that these seams had similar features each other and samples from each seams should have blended in accordance with their reserves. And therefore experiments have been carried out for these blended samples. The blended samples have been consisted of 33.3% top seam, 53.3% middle seam and 13.4% bottom seam. The macroscopic observations made on the coal samples have shown that these region coals have completely constituted mat and dark brown. In addition to this, some fibber structure zones with light brown have been met as well as the smallest size (40-10 urn) pyrite phases, majority located at the bottom seams. First of all, physical and chemical features were determined for blended material (the sample) during the experiment. It was observed that this sample consists of 32.50% moisture, 12.30% ash, 46.57% volatile material, 40.82% fixed carbon, 1.88% total sulphur and 1.05% combustible sulphur, and has 5426 Kcal/kg of upper calorific value. For the purpose of determination of washable features of the sample, coals with - 100 mm in size were classified as -100 +50 mm, -50 +19 mm, and -19 +1 mm, and individual sink and float experiments were made for each YTTT classification. Particle -ash -curves obtained by classifications has showed that concentration of this coal would be achieved with small particles rather than big particles in size. Inherit ash in coal was defined as 7.3% by sink and float experiments. Because of the high ash (16.05%) in coals with -19 +1 mm in size, firstly they were classified as - 19 + 10 mm, -10 +6 mm, -6 +3.36 mm and -3.36 +1 mm; secondly concentration with jig was used for coal between 3.36 mm and above; lastly shaking table was employed for coal with -3.36+1 mm in size. From this experiment, Yeniköy blended-coal sample (-19+1 mm) resulted in a clean coal with 11.49% ash and 79.7% combustible output in a ratio of 75.78% in quantity. Run-of-mine output with -100 +19 mm in size and clean coal with -19+1 mm in size obtained by jig and shaking table were mixed, and this blend was used in low temperature coke experiments. This coal (+ 50 mm) size was reduced to -50 mm below by taking into consideration of inside volume of retort used for coking. Dilatation tests have been carried out to determine the dilatation features of coal so that this would indicate the low temperature coking tests. Experiments were verified by heating between 300 - 650 °C with 3 °C/min heating speed. When results were examined, it was observed that coal had shrinkage event rather than dilatation. Low temperature coking tests were made with the 500 gr samples which has no surface moisture. An average inherit moisture of coal was found to be 14.18%. Additionally, the effect of particle size and time on coking was examined at low temperature coke - tests. Coals classified as - 50 +19 mm, - 19 +10 mm, -10+1 mm in size were subject to coke with a period of 20, 40, 60, 80, 100 and 120 minutes at coking furnaces which have fixed bed and inside volume. As a result of experiments made with different temperatures, regarding the other parameters, the biggest effect in coking was observed to be the temperature. Coal was converted to semicoke in a short period, especially in high temperatures. Meanwhile, the sulphur and tar content of coal has reached the desired level namely, 1.40% and 0% respectively. The content of volatile material which previously was made at 400 °C with 120 minutes was resulted in 700 °C temperature at about 15 minutes, too. For example, while the volatile content of semicoke between -50 +19 mm in size was becoming 27.82% at 400 °C with 120 minutes, the content was decreased to 9.62% at 700 °C with 120 minutes. vrv There are some liquid with tarry in volatile material of coal as well as gas. By the effect of the temperature, these materials has started to move apart from coal. While the liquid with tarry was completely left the coal at about 600 °C, gas emission has continued until 900 - 1000 °C temperature. According to the experiments, the removing of the liquid products from the coal has continued until the coal would has 15% volatile material. While the decrease of volatile part (volatile material + inherit moisture) of coal, during the coking, has tended to close to the linear curve at 400 °C (low temperature), it would present three different behaviour at 700 °C (high temperature). The volatile part has rapidly (a straight curve) left the coal in 20 - 25 minutes whereas removing speed of volatile material has reduced on a large scale at 25 - 60 minutes, and coking has almost been completed in the end. The removing of volatile material has slowed down (close to a plain curve) 60 minutes later. In case of being 500 - 600 °C, the removing of volatile material was found to have two different tendency. It was understood that the removing tendency of volatile material was the same for three different particle size. As long as the volatile material of coal is removed, fixed carbon content of coal is increased. While this increase becomes less at low temperatures, it has a lot at high temperatures. Low temperature coking which has been achieved at 700 °C in 20 minutes has not have fixed carbon content at 400 °C in 120 minutes. For instance, for - 50 +19 mm, the fixed carbon content of dry coal in the air was 36.02% whereas this value reached 70.77% at 700 °C with 120 minutes. When fixed carbon curves are concerned, these curves behave close to the linear curves at low temperatures, and this case changes as the temperature increases. At the beginning of the semicoking, the fixed carbon content of coal has rapidly increased at high temperatures (700 °C). Later, this increase has slowed down, and had a low value at the end of semicoking. Because the fixed carbon content of coal is increased with semicoking, the upper calorific value is increased, too. While an average upper calorific value of dry coal is 4748 Kcal/kg in the air, this value has increased to 6585 Kcal/kg at 700 °C with 120 minutes as a result of the coking process. From the result of semicoking experiments made for each particle size, considerable part of combustible sulphur has been determined to remove the coal. The amount of total sulphur removed from the coal has increased depending upon the coking temperature and time. From the sulphur removing curves, the biggest effect for total sulphur removed from coal has been considered to be the temperature. An example is that the total sulphur removal made at 700 °C with 20 minutes was not obtained even to 400 °C with 120 minutes. It was YV realised that the process of sulphur removal occurred at high temperatures (600- 700 °C) with very fast speed. If curves of the total sulphur removed are generally examined, the majority (60%) of total sulphur which is found in coal at 600 - 700 °C with a period of 60 - 80 minutes will remove the coal. The total sulphur content of coal for the three size group was determined to increase a little both at 400 °C coking temperature and beginning of the coking. This matter was due to the loss of water at the beginning and being low temperature like 400 °C, and that removal kinetics of volatile parts from coal become higher than disintegration kinetics of sulphur. According to the dry base, the total sulphur with 1.88% in run-of-mine output coal has reduced about 1% (1.06 - 1.20%) at 700 °C with 2 hours coking period. The combustible sulphur of this coal has changed from 1.05% to 0. 10% levels. Disintegration of coal has happened at low temperature coking. The quantity left on lower size for each size group has been decreased with regard to coking temperature and its time. Since particles are dispersed by coking, they show the same tendency for different temperatures for each size group. However, as long as the original size of particle becomes small, their dispersions will be reduced during the coking. For example, coal with -50+19 mm in size at 700 °C, coking by a period of 120 minutes, 56.8% of semicoke has passed under 19 mm in size. However, if coal with -10+1 mm in size are semicoked under the same semicoking temperature and time, 8% of semicoke has passed under 1 mm in size. From these results, thermic shock in big size coal becomes more effective. In order to remove the termic shock effect relatively on the particle, coal which belongs to three separate size has placed furnaces which have different room temperatures. The temperature has increased to be 100 °C/minute and been subjected to semicoking. When the results were examined for sizes between -50 + 19 mm according to direct semicooking, the quantity left on the sieve (+19 mm) risen about 8.69%, this case was 1.66% for -19 + 10 mm size group, and the others did not have any increases. From these tests, the best semicoking conditions have been specified for Îstanbul-Yeniköy region coals. We have agreed that an important parameter would be the temperature and chosen 650 °C for coking temperatures at semicoking tests. Removing of tar in coal was considered to be determine the coking time. The coking period between 50 and 76 minutes would be enough to get semicoke which has 15% volatile material. Moreover, semicoke which was obtained under the best conditions has had 16.67% ash, 15.24% volatile material, 68.09% fixed carbon, 1.45% total sulphur, 0.40% combustible sulphur, and 6404 Kcal/kg upper calorific value. Additionally, the ignition heat value of this semicoke is determined as 321 °C. wi In order to specify the secondary products which have happened during the coking, the coal which has no moisture for -50 +1 mm in size has been used for coking. From this test made with the best conditions, the coal has had 60,2% semicoke, 20.3% gas and 19.5% liquid products. The liquid products were analysed to determine the gas compounds. As a result, these gases were constituted majority by CH», CO, H2 and C02. In addition to these, there were some sulphur gasesYüksek LisansM.Sc