(56u) An Understanding of Hazards Analysis Using LOPA for Plants Handling and Processing Combustible Dust Products

Manjunath, K., Dow Chemical Co.
Baldwin, G. W., The Dow Chemical Company
Koch, J. F., The Dow Chemical Company

Designing and operating plants handling particulate solids is not straightforward due to many reasons such as plugging/fouling due to variation in product quality, uneven flow resulting in erosion and wear of the equipment and degradation of the product, influence of humidity resulting in adhesion, cohesion and more. If plants handle and process solids which are combustible, then the design is even more challenging. Once the design is done then the operation of solids plants must comply with hazards analysis of the unit operations for safer and reliable operation. In this paper, we plan to provide examples of various unit operations and show how a hazards analysis can be carried out using the layers of protection analysis, LOPA.

In order to carry out LOPA, one must consider realistic scenarios for the process step that results in a “cause-consequence” pair which is unique. There can be more than one event leading to the same undesired consequence, and each “cause-consequence” pair is a separate scenario. In order to identify the unique scenarios for the process step, one must engage a knowledgeable person who has experience and understanding in handling and processing of combustible solid products in terms of particle size variation, fines concentration, interpretation of combustible data, relevant local standards and codes. This will then enable quantifying the total risk for the project resulting in a robust design and long term minimum cost of ownership