IR@CIMFR - Central Institute of Mining and Fuel Research (CSIR)
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Application of Fluidization Technique to Coal Carbonization
No full textFluidized and allied carbonization processes developed abroad are reviewed. The processes developed by Pittsburgh Consolidation Coal Co., Institute of Gas Technology, Bureau of Mines and United Engineers and Constructors Inc., are described. The first two processes propose to treat both non-caking as well as caking coals with the object of producing semi-coked char for blanding and power generation. The Bureau of Mines process which has been developed commercially is limited to coals with oxygen content above 12%, heating value less than 14250 B.t.u./lb. on pure coal basis. The process developed by United Engineers & Constructors Inc., operates continuously with any coal but it has not been tried on any large plant. The two processes developed by Imperial Chemical Industries and national Coal Board, in U.K., are described. The former could be operated continuously with caking coal and the latter has the object of using high volatile non-caking coals for producing smokeless domestic fuel for open grates. The fluidized carbonization process operating on a commercial scale in Germany is discussed
Assessment of the Yield of Products from Coal Carbonization
No full textCorrelation factors have been developed for the yield of different products, e.g., coke, tar, liquor, ammonia, and gas obtained from laboratory Gray-King Assay, pilot oven tests and from commercial coke Plants. The yield of gas from commercial oven is higher and the yield of coke lower, evidently due to higher carbonizing temperature which results in cracking. The correlation between assay and experimental oven yield is found to be poor and indicates the need of carrying out larger number of tests on the same types of coals. Addition of 4-5% of coke breeze to coking coals or their blends gives increased yield of coke, tar and gas per ton of coal charged. Blends of high volatile weakly coking coals from Raniganj with 15-20% of low volatile coking coals from Jharia filed or L.T.C. char give metallurgical coke ; the yield of coke is lower but the tar yield is more than double that normally obtained from Jharia coking coals
Removal of Sulphur from High Sulphur Coals
No full textThe effects of various gases e.g. coal gas, hydrogen, superheated steam and water gas on the desulphurization of Baragoiai (Assam) coal during carbonization have been studied. About 90% of the sulphur in Baragolai coal is organic. Two methods were generally adopted ; (i) the coal was carbonized at 925º±25ºC, and the reacting gas was then passed over the coke, (ii) the reacting gas was passed from the beginning of carbonization, the flow of gas being continued at 925º±25ºC. The second method was found to be more effective. The efficiency of desulphurization is higher in a vertical furnace than in a horizontal, probably of closer packing of the coal and coke
Blending of Coal for Carbonization
No full textThe Paper discusses the scope of blending, the development of the blending technique, the use of different types of crushers and mixers etc., the blending different materials such as coals of varying coking properties with high and low temperature coke, anthracite pitch, tar and oil and shows the large amount of saving that can be made by the coke-oven industry during the ensuing years by these methods
Fundamentals of Coal Carbonization Reactions
No full textThe reactions involved in the process of carbonization are disproportionate in nature, and are guided primarily by the chemical constitution and physical structure of coal and secondarily by varying operational conditions and pre-treatment of the coal charge. Low rank coals cannot attain high degree of freedom on heating due to their highly disorganized structure; besides, preponderance of reactive oxygen groups in them initiates a cross-linked, immobile structure at an early stage of carbonization. Very high rank coal also cannot soften due to their very large immobile molecules. Medium rank coal are more orderly than the low rank coals; their molecular sizes are not very large and they do not contain large amounts of reactive oxygen groups. They can, therefore, attain plasticity on heating. Major devolatilization takes place after the plastic stage and the semi-coke during its conversion into true coke is not weakened by severe strains. No absolute limit can be set to the coking potentiality of coal
Selective Crushing of Coal
No full textThe Burstlein-Longwy system of coal preparation recently developed in France for utilizing non-metal-lurgical coal for blast furnace coke manufacture is critically examined in this paper. The authors believe that the process is laborious and costly and not suitable highly vitrainous coking coals alternative systems of coal preparation are suggested. The crushing system at the Durgapur Coke Oven Project for use of blends of Raniganj and Jharia coals having different petrographic composition is also discussed
Upgrading of Difficult-cleaning Coals of Jharia Coalfield to Supplement the Future Coking Coal Reserves of India
No full textThe paper describes the results of experiments on the washing of some lower seam of Jharia in a 6” diameter cyclone and a 2,000 g.m. sub-aeration type Denver cell. The need for a survey of the cleaning possibilities of the difficult coals of Jharia and Bokaro is stressed. Industrial processes that can be tried are listed. The problems of screening and drying of coals, treatment of slurry, effluent etc., recovery and utilization of the middlings and rejects are considered in some detail. The authors then draw attention to the importance of evolving an integrated plan for the washing of difficult coals in India
