Steady state behaviour and maintenance planning of a desulphurization system in a urea fertilizer plant

This paper presents the steady state behaviour and maintenance planning of the desulphurization process in the fertilizer industry. The process consists of four subsystems, A, B, C and D in series with three states; good, reduced and failed. One standby unit is provided for each pump. Taking constant failure and repair rates for each subsystem, mathematical modelling is done using the Chapman-Kolmogorov birth-death process. An expression for steady state availability is given. Based on the data available from a medium sized ammonia production process, the behaviour of each working unit in the process has been analysed. The computed results are discussed with the concerned plant personnel which is helpful to the management for implementing any future plan regarding design modification of the system/processes.     

Performance modeling in critical engineering systems using RAM analysis

Reliability, availability and maintainability (RAM) analysis of system is helpful in carrying out design modifications, if any, required to achieve minimum failures or to increase mean time between failures (MTBF) and thus to plan maintainability requirements, optimize reliability and maximize equipment availability. To this effect, the paper presents the application of RAM analysis in a process industry. Markovian approach is used to model the system behavior. For carrying out analysis, transition diagrams for various subsystems are drawn and differential equations associated with them are formulated. After obtaining the steady state solution the corresponding values of reliability and maintainability are estimated at different mission times. The computed results are presented to plant personnel for their active consideration. The results proved helpful to them for analyzing the system behavior and thereby to improve the system performance considerably by adopting and practicing suitable maintenance policies/strategies.     

Behavioural analysis of shell gasification and carbon recovery process in a urea fertilizer plant

The paper discusses the behavioural analysis for shell gasification and carbon recovery process in a urea fertilizer plant. The system consists of three subsystems D, E and F arranged in series, with three possible states good, reduced and failed. The subsystem D has three parallel operating units with two units in cold standby. Failure and repair rates for each subsystem are taken as constant. Formulation of the problem is carried out using simple probability consideration. The expression for steady-state availability is derived. Taking data from a medium size plant, the effect of each working unit on the system availability is tabulated. The results are supplied to the plant personnel for improvement in designing the system and planning the process for minimum failure.