Reliability considerations in the design of gypsum producing flue gas desulfurization plants in the UK

Her Majestys Inspectors of Pollution (HMIP) Have stipulated that Flue Gas Desulphurisation (FGD) plants built in the UK must achieve a minimum availability of 97.5% per boiler stream. This has resulted in FGD contracting companies carrying out extensive Reliability, Availability and Maintainability (RAM) studies to prove that the FGD plant designs can achieve the required availability. John Brown carried out a number of reliability studies to prove the FGD plant configuration selected would have an availability of over 97.5%. The following major techniques were used: Established, Novel Features and Preferred Parts Analysis; Buffer Storage Analysis; Failure Modes, Effects and Criticality Analysis; and Fault Tree Analysis. In addition a failure and routine maintenance model was developed that predicted total maintenance hours for an FGD plant, split by craft disciplines. The interdependency between each model was studied in detail culminating in a predicted availability figure of 99+% for the average operating case. Sensitivity analysees were completed for different operating and fault scenarios. John Brown are confident that the original reliability objectives have been met by the approach taken to develop a lowest life cycle cost plant