1 / 27

TOWARDS AN ENERGY EFFICIENT NATION

TOWARDS AN ENERGY EFFICIENT NATION. ISO 9001 INSTITUTION. A n Experience of Third Party Sampling of Coal. A. Choudhury , Kalyan Sen C.F.R.I, Dhanbad (India).

darby
Download Presentation

TOWARDS AN ENERGY EFFICIENT NATION

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. TOWARDS AN ENERGY EFFICIENT NATION ISO 9001 INSTITUTION An Experience of Third Party Sampling of Coal A. Choudhury , Kalyan Sen C.F.R.I, Dhanbad (India) New Challenges for Indian Coals

  2. Quality Monitoring (QM) of Coalis an essential requirement for process control, plant performance or for any commercial transaction between Consumer and Producer QM requires proper implementation of standard sampling, preparation and test procedures New Challenges for Indian Coals

  3. Sampling methods depend on • mechanical or manual sampling • sampling from moving belt • sampling from stationary lot (wagon, stockpile, etc.) New Challenges for Indian Coals

  4. Nos of increments of sample is to be optimized in such a manner that whole volume of the lot is repesented, thus minimising the variance because About 80% of the error comes from collection of samples New Challenges for Indian Coals

  5. Sampling variance is a function of product variability i.e. different results can be obtained from • same increments for different coal • different increments for same coal New Challenges for Indian Coals

  6. The objective is to reduce the sampling variance as far as practicable New Challenges for Indian Coals

  7. Any Sampling scheme normally conforms with the national or international standards (BIS/ISO/ASTM, etc.) Constraint - technical, cost and time Thus modifications in sampling procedures are necessary with mutual agreement between parties New Challenges for Indian Coals

  8. Precision • measures the closeness of data in given condition • indicates the reproducibility of the results • measures the chance error as expressed by variance SMALLER THE RANDOM ERROR, PRECISE IS THE METHOD A commonly accepted index of precision is twice the population standard deviation New Challenges for Indian Coals

  9. Precision depends on • Variability of coal • number of samples from a lot • number of increments comprising each sample • mass of sample related to the nominal top size New Challenges for Indian Coals

  10. Bias Systematic error which leads to the average value of a series of results being persistently higher or lower than those which are obtained using a reference sampling method which is intrinsically unbiased New Challenges for Indian Coals

  11. Reference method of sampling is ‘Stop Belt Method’ (free of Bias) New Challenges for Indian Coals

  12. General principle of Sampling • Primary increments should account for the Variability • Equal probability to all particles to be selected and included in the sample • Largest particle of the lot should pass freely through the sample device • Sufficient mass of the sample to enable particles to be present in the same ratio as in the lot New Challenges for Indian Coals

  13. General Scheme for Sampling New Challenges for Indian Coals

  14. General scheme for sampling . . . • Decide purpose of sampling e.g. plant performance, process control, commercial transaction • Identify the quality parameters, viz., general analysis, TM, size, washability, etc. • Define the lot • Define the precision required • Decide whether continuous or intermittent sampling is required New Challenges for Indian Coals

  15. General scheme for sampling . . contd.. • Determine the number of sub-lots, increments to achieve the required precision. • Determine the nominal top size of the coal • Determine the min. mass/ increment and the min. mass of the total sample • Decide on the method of combining the different increments for gross sample • Decide on drawing common or separate samples, for analysis New Challenges for Indian Coals

  16. Design of sampling scheme • Division of lots • Basis of sampling • Time basis • Mass basis • Precision New Challenges for Indian Coals

  17. SAMPLING FOR COMMERCIAL TRANSACTION • Joint Sampling • Washed coking coal • Power coal New Challenges for Indian Coals

  18. Joint sampling • at loading point - by customer and producer on mutually agreed methods • at both ends - mean value • bonus/penalty to producer for values beyond agreed tolerance limits • requires periodic testing • . . . Unfortunately rarely practiced in India New Challenges for Indian Coals

  19. Reasons for discrepancies in results • level of precision not defined • Non-identical procedures for sampling at both ends • manual sampling results in large human error • deviation in procedures from agreed one New Challenges for Indian Coals

  20. Primary requirements for development of a methodology • testing for estimation of the variances, Viand Vpt • decision on level of precision of the ash value • calculation for no. of sub-lot and increment /sublot at desired precision from known values of variances • estimation of precision for the existing procedure • estimation of min. mass/ sub-lot form the std. Table • estimation of min. mass/ increment New Challenges for Indian Coals

  21. SAMPLING SCHEME is designed based on the above test The procedure can significantly reduce the discrepancies in the results at both ends New Challenges for Indian Coals

  22. Sampling of washed coking coal Samples are drawn from the • Automatic mechanical Sampler (AMS) • Conveyor Belt For day to day quality monitoring, samples are reduced by offline and/or manual means to analyze ASH & TOTAL MOISTURE New Challenges for Indian Coals

  23. Sampling of Power Coal Best option: AMS at loading/ unloading point AMS for coal x200mm or above is not a proper choice to ascertain quality parameter Suggestion: sampling on crushed coal below 50mm or preferably at 20mm New Challenges for Indian Coals

  24. Where AMS is non-existing/ non-functioning , sampling may be done for the time being, at loading point from the wagon by manual means • Wagon top sampling is difficult, because • segregation occurs because of large size • impractical to collect sample from the full depth • introduces bias due to manual operation Suggestion: smaller size (< 50mm) of the sample New Challenges for Indian Coals

  25. Conclusion: • Choice of Sampling methodology depending on the purpose • Efforts to reduce the sampling variance to a min. possible limit • Sampling on mechanically crushed coal below 50mm • Preferable size is 20mm ( feed to most power plants) New Challenges for Indian Coals

  26. Conclusion…………contd. • Replacement of manual sampling method by AMS • In absence of AMS, manual wagon top sampling of this size would give better results • In absence of AMS, manual sampling from wagon top can be done as an temporary option, following the prescribed methodology New Challenges for Indian Coals

  27. THANKS New Challenges for Indian Coals

More Related