1、1 英文翻译原文STABILITY STUDY OF AN AIR DENSE MEDIUM FLUIDIZED BED SEPARATOR FOR BENEFICIATION OF HIGH-ASH INDIAN COALA. K. SAHU, ALOK TRIPATHY, S. K. BISWAL, AND A. PARIDAMineral Processing Department, Institute of Minerals and Materials Technology, Council of Scientific & Industrial Research (CSIR), Bhu
2、baneswar, IndiaIndian high ash noncoking coal contains a substantial quantity of near-gravity materials (NGM). The presence of NGM needs beneficiation in dense medium separation process. Air dense medium fluidized bed separator (ADMFBS) uses the magnetite medium to improve the separation efficiency
3、of beneficiation of high NGM coal. Stability of the particulate fluidized bed in this system is the essential prerequisite for the separation of heavy and light particles. In this study, the characterization of medium and particulate fluidized bed was assessed to maintain the nonbubbling condition.
4、Stability of the fluidized bed was characterized by different expressions like fluidization index, particulate expansion function, Froude number of particle, Reynolds number of particle, and pressure drop ratio using the minimum fluidization velocity, minimum bubbling velocity, pressure drop of dist
5、ributor and bed, bed porosity, air viscosity, aspect ratio, density of air, and density of medium. It was found that the fluidization indexes of this system for different experimental runs are around 1 to 2. The system was scaled up from laboratory to pilot scale, having a feed throughput capacity o
6、f 600 kg/hr. Indian high ash noncoking coal at particular size (-25+6 mm) was used in continuous operation. The partition number was calculated based on washability data of product and reject. The Ep and imperfection value for the pilot-scale ADMFBS was found to be 0.12 and 0.071, respectively.Keywo
7、rds: Air dense medium fluidized bed separator; Fluidization; High-ash coal; Near-gravity material; Partition number; Stability characteristics of magnetite mediumINTRODUCTIONCoal will continue to play a major role in economic development of India with particular reference to metallurgical and energy
8、 sectors. India is heavily dependent on coal for meeting its energy requirements, which at present is satisfied to the extent of about 60%. The majority of Indian noncoking coal contains more than 40% ash and high near gravity material (NGM). The stringent regulation of Government of India on utiliz
9、ation of quality coal of ash less than 34% for particular utilization pattern has necessitated the beneficiation of high ash and high-NGM noncoking coal 1. The presence of high NGM coal needs efficient beneficiation technique for separation of high and low ash coal particles using dense medium techn
10、ique. Beneficiation of coal can be performed either by wet or dry methods before its utilization. On account of no water requirement, smooth handling and retention of higher calorific value, dry coal beneficiation is going to be the more attractive technology in future 28. Though there are number of
11、 methods using dry beneficiation of coal, the selection of method based on characteristics of coal is the key of success. Indian coal being Gondawana category, the liberation of coal particle is very poor. An air dense medium fluidization bed separator (ADMFBS) is one of the efficient dry beneficiat
12、ion techniques that use magnetite powder as a medium to improve the separation efficiency of high ash coal 7, 9. The coal particle separation with an air dense medium fluidized bed separator utilizes pseudofluid characteristics of the gas-solid fluidized bed to form a uniform and stable gas solid su
13、spension having certain density. According to Archimedes law, light and heavy particles separate from each other by the pseudofluid density with light particle floating and heavy particles sinking. The stability of the fluidized bed plays an important role in sharp separation between light and heavy
14、 particles. The system is considered to be stable if the fluidization system is operating within minimum fluidization velocity and minimum bubbling velocity. Wilhem and Kwauk 10 proposed that if the Froude number at minimum fluidization (Frmf) is less than 0.13 then it is a nonbubbling fluidization
15、and if Frmf1.3 then it is a bubbling fluidization 11. Romero and Johanson 12 proposed the combination of the following four dimensionless groups to measure or quantify the fluidization level: where: According to Romero and Johanson 12, if the product of the above four dimensionless groups is less th
16、an 100 then it is a smooth or nonbubbling fluidization and if the product is greater than 100 then it is a bubbling fluidization 11. The fluidization index is a ratio of minimum bubbling velocity and minimum fluidization velocity (Umb/Umf),which is an alternative way of examining the stability region. Fluidization index is always greater than 1 and normally lies within the range of 12. It is always desirable to have a fluidization index as high as pos
