1、1 英文翻译原文Prediction of economic operating conditions for Indian coal preparation plantsabstractThe most important optimization concept, which, has long been recognized in coalprepar- ation with multiple cleaning circuits, is the constant incremental quality approach. However, this approach maximizes
2、the overall plant yield for a targeted product quality, without putting any em- phasis on coal value/price. So, sometimes confusion arises in the determination of the overall pl- ant yield that would more than offset the price due to lower quality of product. In this paper a me- thod is presented to
3、 maximize the coal value by considering the equal incremental quality approa- ch as well. Here the predicted yield of composite coal has been calculated by using a designed pro- bable error value, then the value of a particular coal is maximized. A case study with six differrent coals of different c
4、haracteristics is presented to ascertain the merit of this approach. This techni- que offers the coal preparation engineer an effective and straight forward method for determining the optimum cut points of separation for different coals to achieve maximum economic gain.1. IntroductionIndian coals in
5、 general are of drift origin and high ash content with poor washability characteristics, which make these unsuitable for use without further upgrading. At the same time the quality of run-of-mine (ROM)coal hasprogressivelydeteriorateddue to the availability of inferior grade coal reserves and high d
6、egree of mechanization introduced in large opencast mines. Furthermore, the Ministry of Environment and Forest (MoEF), Government of India, has imposed arestriction on the use of high ash coal (N34%) in power plants located 1000 km away from the pit-head, sensitive localities, and critically pollute
7、d areas. All these factors necessitated a long term strategy for improvingthe qualityof coal by adopting an appropriate cost effective washing technology.Coal washing has been used since the early 1950s in India to meet the required coal quality. Infact , the coal is washed when it is beneficial to
8、do so, and the optimum operating condition schosn fo rwashing are decided on a cost basis. While taking up this exercise, it was immediately realized that the solution to the cost versus quality problem came from two aspects: technological and economics vis-vis optimum ash level of the washed coal.
9、The technological optimum condition addresses the concept of constant incremental product quality to maximize the plant yield18, while the economic optimum condition deals with coal value/price.Presently, some models and commercial software package, like EPRIs coal cleaning cost model 9, CCS 10, CPO
10、 11, Utah-MODSIM 12, an Excel-based cost-estimate model developed by the United States Geological Survey 13, SIU-SIM SIMULATOR 14 and Apex provided by Western Mine Engineering, Inc., are available for economic analysis of coal preparation. However, these software packages render little practical ins
11、ight for the Useful Heat Value pricing structure of coal and wide frequent variations of ROM coal qualities. Moreover, in actual practice most of the coal washing devices are not perfect and their performance depends on feed qualities, which in turn necessitates a correction to account for the exten
12、t of imperfection. In the proposed method thepricestructure of coal,imperfection of washingdevices and variation of feed quality have been implemented and can be changed according to the processre quirements. The approach adopted hereis to maximize the value of coal subjected to equal quality constr
13、aint by using a spread sheet-based program within a framework of price structure, equipment imperfection, and feed quality variation. This method has been found to be a practical approach for determining the optimum operating parameters for different washing equipment to maximize the value of coal.
14、2. Method2.1. Optimum specific gravity of separation from price structureIf a sample of coal whose fractional ash content is x1 and price y1 rupees per ton then the mass and ash content of this coal for one rupee will be 1y1 tons and x1 y1 tons respectively. Similarly another coal having ash content
15、 x2and pricey2 will have the mass1 y2 tons and ash content x2 y2 tons for one rupee. This clearly shows that these two coals have different weights and contain different amounts of ash, although their values are same (one rupee). The increment having weight of 1y21y1 tons containing x2y2x1y1 tons of
16、 ash will therefore have no value. Hence the fractional ash (critical ash) content of an increment of zero value is x2 y2x1 y1 1 y21 y1 orx2y1x1y2 y1y2. From the above derivation it is seen that if any quantity of coal containing a critical ash ofx2y1x1y2 y1y2 was added to another coal, the value of the latter would remain substantially unchanged, whatever its original ash content. If a coal containing less than this critical ash had been added
