advanced coking technologies abstract key words introduction

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IMPROVEMENTSIncreasing economic and environmental requirements led to various developments.For the conventional coking process this is valid for the battery part as well as forthe gas treatment. Alternatives refer to the heat-recovery process as well as toother utilization of the coke oven gas produced in the conventional process.Conventional CokingHigh Capacity Production Units - Chamber volumes of coke ovens started inearlier times with some 20 m³ in connection with oven heights of 4m, reachedapproximately 50 m³ for 7m – batteries leading to 76 m³ for the former Kaiserstuhlcoking plant with an oven height of 7.6 m. In addition to the increased oven heightsalso the chamber width has been changed from former 400 to 450 mm toapproximately 600 mm. The table in Fig. 1 summarizes the main technical featuresof different units for an annual coke production of 2 million tons of coke.Oven heightNumber of batteriesNumber of ovensUseful volume p. ovenNumber ofpushes/charges p. dayTotal length of sealings(doors, standpipes,charging holes)Required space for thebatteriesSets of oven machinesOperation teams7.6 m 6.0 m 4.3 m2 4 5140 220 32576 m³ 34 m³ 20 m³135 300 5204.8 km 6.0 km 6.5 km40,000 m 2 50,000 m 2213255,000 m 253Fig. 1 Comparison of ovens with different heights and useful volumesFurther improvements have been reached at least with the coking plantSchwelgern in Germany with an oven height of 8.4 m and a chamber volume of 93m³, producing 2.6 million tons of coke per year /2/.In case of high capacity ovens the advantages are obvious regarding the requiredspace and environmental impacts. Of high importance is the saving of operationcost due to the fact that only one operation team is needed instead of 2respectively 3 teams for the common ovens. Also the number of sets of ovenmachines comprises potentials for saving of investment and operation cost for thehigh capacity ovens.In case of the installation of high capacity ovens also the related gas treatmentplants have been designed accordingly for coke oven gas flows of 120,000respectively 155,000 m³ / h as single line units, providing comparable advantages.Battery partFor ensuring certain stability properties and homogeneous temperaturedistributions during heating up and normal operation both of influence for asatisfactory longevity and operation performance of batteries, the design conceptshave been improved and adapted accordingly. In parallel many environmentalissues have been developed respectively optimized.2 of 8
Chamber width – Apart from an influence on useful chamber volume a wider ovenchamber leads to higher absolute shrinkage of coal at the end of carbonization,followed by wider gaps between oven walls and outer surface of the coke cake.This results in less pushing forces required due to reduced frictions between thecoke and the oven walls. Consequently blocked ovens to be pushed have not beenobserved at such batteries. Last mentioned advantage additionally provides lessrisks for damage of the refractory material and increases the lifetime. A furtherpositive impact on the lifetime is caused by the following effect. Since typicalcoking times for ovens with wider average width are in the range of 25 h lesspushes per oven and day are the result in comparison to ovens with narrower ovenwidths and coking times of typical 18 h coking times.Another advantage caused by the wider is an increased coke quality, which meansa particle size distribution with an increase of greater coke particles can beobserved.In some cases the aforementioned higher absolute shrinkage values of the coalare used for an increase of the coke yield by applying coal blends with a loweramount of volatiles.Bracing system - Proper working bracing systems have been developed based onresults from research programs and practical experiences. In connection withstrong heating wall bonds the system CONTROLPRESS ® from Uhde providessufficient prestressing to the refractory material which can safely withstand thecoking pressure and all other forces from the operation. A schematic arrangementof this bracing system is shown in Fig. 2.F oF 1F 2F 3F 4F 5F 6F 710 20 30 40 50 60Load on heating wall in kN per mRequired load distributionsfor different oven heightsF 8F uFig. 2 CONTROLPRESS ®bracing systemHeating-up procedure - Homogeneous temperature distributions during theheating up period of a battery are also important for a long life. For this reasonUhde has developed a new procedure by applying external fan burners /3/. Byproducing an overall high volume flow of flue gas they generate a positive pressurein the entire oven bloc right from the beginning and this is accompanied byoptimum heat transfers inside the whole system. An arrangement of burners showsin Fig. 3. Local overheating in the area behind the coke oven door is ruled out.Fig. 3 Arrangement ofheating up burners3 of 8
Page 1: ADVANCED COKING TECHNOLOGIESMartin
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