Analysis of explosion risk factor potential on coal reclaim tunnel facilities by modified analytical hierarchy process

Abstract

This study focused on developing a risk assessment method for explosion at a coal reclaim tunnel (CRT) facility. The method was developed based on an analytical hierarchy process (AHP), which is an expert system that quantifies the factors of explosion incidents, based on events and hierarchies. In this paper, the proposed model was modification from original AHP model, specifically modifying the structure from ''alternative's results'' to ''total risk-rating's results''. The total risk-rating is obtained by summing up risk-rating of each factor, where the risk-rating is a multiplication product of the risk value by the AHP weighted value. To support decision-making using the expert system, data on the real conditions of the CRT were collected and analyzed. A physical modeling of the CRT with laboratory-scale experiments was carried out to show the impact of a ventilation system in CRT on diluting the methane gas and coal dust, in order to support the quantification of AHP risk value. The criteria to evaluate the risk of explosion was constructed from six components that are: fuel, oxygen, ignition, confinement, dispersion, and monitoring system. Those components had fifty-two factors that serve as sub-components (root causes). The main causes of explosion in CRT were found to be: mechanical ventilation failure and abnormal ventilation, breakdown of monitoring system, and coal spontaneous-combustion. Assessments of two CRT facilities at Mine A and Mine B were carried out as a case study in order to check the reliability of the developed AHP method. The results showed that the risk rating of Mine A was classified as high and Mine B was classified as medium, which is in a good agreement with the site conditions.

Development of comprehensive fire and explosion risk assessment on coal reclaim tunnel using Monte Carlo simulation and risk matrix method

“…Among the initial 52 factors identified by Widodo et al, 11 four factors, for example, total resistance, fan specifications, the distance between fans, and the number of fans, can be combined into 1 (one) new factor, namely, a “ventilation system” factor, therefore the number of factors in present research become 49 factors. To cluster the factors, this present study grouped the 49 factors into four aspects, for example, coal properties, CRT design and operation, environment, and management (see Table 1).…”

“…Widodo et al's 11 research studied factors that can cause fire and explosion in the CRT using the AHP method where the root cause diagram for the explosion in the CRT is shown in Figure 2. All factors are part of the “fire triangle” theory, which are a fuel, an oxidizer (usually air), and an adequate heat or ignition source 22 ; and also part of the “explosion pentagon” theory, that is, the five elements that must occur simultaneously to cause explosion, they are: fuel, heat (ignition), oxygen, suspension (dispersion), and confinement 23…”

“…AHP structure for CRT's fire and explosion root cause based on Widodo et al's 11 research. The symbol of factors is described in Table 1…”

“…Regarding safety standards at CRT facilities, New South Wales Government, Australia, has a comprehensive regulation and best practice for safety requirements, procedures, and controls against various risks in CRT 10 . Furthermore, Widodo et al 11 have developed a risk management method at CRT facilities by applying the analytical hierarchy process (AHP) method. However, the uncertainties data on CRT risk factors of fire and explosion hazard has not been addressed on that research.…”

“…From the research mentioned, very few studies have focus on the CRT area. This present study aims to analyze the application of Monte Carlo simulation and risk matrix using factor that have been identified by Widodo et al 11 . The new method has been developed by this present research, which evaluates the risk based on probability analysis of fire and explosion factors by adding the indicator in the risk analysis, namely, the total risk rating ( TRR ) value for each level of severity generated from the Monte Carlo simulation.…”