An Analysis on Heat Generation of Stored Coal by Oxidation and Heat Accumulation in Cargo Holdes

Abstract

Accompanying the gradual increase of consuming coal, a lot of powdered coal which tends to generate heat spontaneously by its oxidation is transported overseas by many bulk carriers. The self-heating of coal becomes a problem of great concern in the transportation of coal as bulk cargo for the reason that the quality of coal is fairy deteriorated and the accidents of spontaneous combustion occur occasionally. Consequently, it needs to take countermeasures to cope with preventing from excessive heat generation and surplus heat accumulation in cargo holds. For this purpose, it is a way of controlling the thermal environment of a coal carrier to take account of the fact that the rate of calorification of fine coal depends upon its temperature and oxygen concentration which could be expressed by the Arrheniuse's formula.The heat generation of stored coal by oxidation and the heat accumulation in cargo hold are investigated in this paper. Firstly, the simplified formulae based on the thermal conductivity equation with the self-heating source are introduced with a view to assume the variation of temperature in a cargo hold. Secondly, the experiment of measuring the variation of coal temperature as time proceeds is excuted using the octagon-sectioned hold model similar to a cargo hold of bulk carrier on the scale of one-thirtieth. Furthermore, a numerical three-dimensional analysis on the heat diffusion of packed particles attended the change of oxygen concentration is carried out to clarify the decisive factors governing the process of heat accumulation.