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Show SLAGCING PROBLEMS IN FOSSIL FUELLED BOILERS . . The problems of boiler slagging are well known, bowever it would be fair . to say that very few boiler operators appreciate the magnitude of their .. - own slflgging problem and tb~ potential cost of tbis problem in terms of boiler derat1ng, outages. slag bridges, accelerated tube eros1on etc. Tne following cases studies use information from a long term boiler study to demonstrate the ineffectiveness of random sootblow1ng and the value of slag condition monitoring. These stu~ies were undertaken by Land Pyrometers 1n conjunct1on with the Central Electr1cty Research Laboratories(CERL) and aim to evaluate instrument performance and life expectancy. A total of 15 Fluxtubes and 20 Fluxdomes were installed and all instruments still function normally after a period of 10300 bours continuous operat1on. The bo1ler is a 500mw front wall coal fired unit. Pos1tions of 'Water Lance' sootblowers and Fluxtubes are shown in Figure 10. The 1nstruments are all adjacent to &ootblowers, with the exception of numbers 3 and 4. A boiler sootblow routine involves numeric seqenc1ng of water lances, from 1 througb to 15, each water lance being activated for approx1matly 45 seconds. The boiler was on full load during the tbree case studies in question . CASE STUDY 1 Case study 1 conc~rns a period when sootblow1ng was available on request and is used to demonstrate the potential problems which can occur, from an 1neffective sootblowing cycle, resulting from an ex~ended period of uncheck~d boiler wall foul1ng. T~e boiler back wall was not cleaned for the 14 bours preceeding the first scotblow, consequently average heat flux levels were reduced to a?prOxl~~tely 120Kw/m12 and th= slag was qu1te tougb, having had time to agglo~rate and sinter. Tne first ~ootblow was conducted at lO-29am and Figure 11 shows the effect of t!l1s sootblow. It can be seen that the only areas showing any i~provement were around Fluxtubes 1.7 and 11, , the effectiveness of ttlS soo~blow is obviously very low . Flgure 12 s:'ows the areas around Fl~x tu bes 1.2.5 and 6, these 1nstruoents re?resentlng the areas a~cu~d the top row of wa~er 1 ~nce6. It c~n be seen ~hat the areas aro u~~ Fluxtubes 2,5 and 6 shaw r.o benefit from the s2~t:low.however the are~ aro~nd Fluxtube 1 cleaned well and es one of :~e few clean areas in th~ t~~l er, experienced hi~h localised neat fl'Jxes . / b I I ,,-~ \ |