Flare stacks on agricultural biogas plants – safety and operational requirements

Abstract

The flare stack is a piece of equipment, which is used as a safety element at a biogas plant. In the case of a cogeneration unit or gas boiler failure, the biogas is redirected to the flare stack where it is burned. When the flare stack fails, the biogas releases to the atmosphere and an explosive mixture can form. The paper is focused on the description of the causes, which can cause the failure of the equipment. For this purpose, the individual components are described and, subsequently, the possibilities of their failure are discussed. In the next part of the work, the following scenario is considered: failure of the cogeneration unit and flare stack, the subsequent leakage of the biogas to the atmosphere. The calculation for determining the consequences of the biogas leakage is carried out. The size of the gaseous cloud and the explosion pressure in the case of a vapour cloud explosion are determined. The calculations were carried out by the software ALOHA (version 5.4.7).