1986

Reunanen, Markku; Suokas, Jouko

Some operational errors and structural failures may cause in a black liquor recovery boiler plant explosion leading to consider-able material damages and to human injuries. Serious explosions, however, have been rare and the comparison between the accident frequencies shows that, for instance, the frequency of smelt-water explosions is in Finland essentially smaller than in North America. On the other hand, the black liquor recovery boiler explosions during the last few years show that the problem is still actual. The safety analysis of the plants was started with a risk mapping applying potential problem analysis. As a result 13 hazards with 78 contributors were found. The pipe lines, vessels and process equip-ment of the black liquor recovery plant were then examined in detail using hazard and operability study (HAZOP). 41 hazards with over 200 contributors were thus identified. For instance, in the liquor system over 60 cases were identified in which indadvertent dilution may appear. Occupational accident risks were sought using work safety analysis (WSA). Three important operator tasks were studied - boiler keeper, stoker and evaporation plant keeper. Altogether 79 hazards with over 100 contributors were found. The most important problems were connected to the accessibility of appliances and the walkways used. Problems and hazards connected to maintenance were sought by using the MORT-method and action error analysis (AEA). A total of over 260 different improvements were proposed as a result of the safety analysis. About one third were found during the operability study, one third during the maintenance study and the rest during the risk mapping and work safety analysis. Over one half of the proposals were technical in nature.