Behavior analysis of synthesis unit in fertilizer plant

ISA transactions, 2012

The main objective of the present paper is to propose a methodology for analyzing the behavior of the complex repairable industrial systems. In real-life situations, it is difficult to find the most optimal design policies for MTBF (mean time between failures), MTTR (mean time to repair) and related costs by utilizing available resources and uncertain data. For this, the availability–cost optimization model has been constructed for determining the optimal design parameters for improving the system design efficiency. The uncertainties in the data related to each component of the system are estimated with the help of fuzzy and statistical methodology in the form of the triangular fuzzy numbers. Using these data, the various reliability parameters, which affects the system performance, are obtained in the form of the fuzzy membership function by the proposed confidence interval based fuzzy Lambda-Tau (CIBFLT) methodology. The computed results by CIBFLT are compared with the existing fuzzy Lambda-Tau methodology. Sensitivity analysis on the system MTBF has also been addressed. The methodology has been illustrated through a case study of washing unit, the main part of the paper industry.

2008

This paper introduces a decision support system for urea synthesis system of a fertilizer plant. It consists of five subsystems arranged in hybrid configurations. Decision support system for urea synthesis system has been designed with the help mathematical formulation using probabilistic approach. For this purpose, differential equations have been developed. Then steady state probabilities have determined. Besides, a pay off matrix is also developed which provides the various availability levels (Aii) for the different combinations of failure and repair rates for each subsystem. The optimum values of failure and repair rates for each subsystem are also determined. This decision model could be useful in a comparative evaluation of alternative maintenance strategies. So, the results of this paper would be highly useful in determining the optimal maintenance strategy, which will ensure the maximum availability of urea synthesis system in a fertilizer plant.

This paper deals with the Markov modeling and reliability analysis of urea synthesis system of a fertilizer plant. This system was modeled using Markov birth–death process with the assumption that the failure and repair rates of each subsystem follow exponential distribution. The first-order Chapman–Kolmogorov differential equations are developed with the use of mnemonic rule and these equations are solved with Runga–Kutta fourth-order method. The long-run availability, reliability and mean time between failures are computed for various choices of failure and repair rates of subsystems of the system. The findings of the paper are discussed with the plant personnel to adopt and practice suitable maintenance policies/strate-gies to enhance the performance of the urea synthesis system of the fertilizer plant. Keywords Reliability Á Chapman–Kolmogorov differential equations Á Markov birth–death process

IOP Conference Series: Materials Science and Engineering

this work treats dependability from a functional (systemic) standpoint, which implies meeting a function required within an input/output system. This approach is demanded and necessary within technical equipment design stages, and is an integrant part of systems integrity design methodology. Designing the system integrity includes design criteria for reliability, availability, maintainability and safety of any system and equipment. The combination of these four concepts leads to the necessity of a comparative and integrative methodology that should ensure a good systems design, with required integrity values that can be computed easily, analyzed the most complete possible, and with the possibility to be modified accordingly. During the recent years, artificial intelligence techniques have been developed for dependability, that make use of, statistic methods (necessary for the realization of an operation history), deterministic mathematic algorithms (to determine the exact solutions ...

2012

Journal of Industrial Engineering …, 2009

This paper discusses the performance evaluation and availability analysis of ammonia synthesis unit of a fertilizer plant. The fertilizer plant is a complex and repairable engineering system comprises of various units viz. shell gasification and carbon recovery, desulphurization, co-shift conversion, decarbonation, nitrogen wash and ammonia synthesis etc. One of the most important functionaries of a fertilizer plant is ammonia synthesis unit. This unit consists of five subunits arranged in series and parallel configurations. For the evaluation of performance and analysis of availability, a performance evaluating model has been developed with the help of mathematical formulation based on Markov Birth-Death process using probabilistic approach. The findings of this paper are therefore, considered to be useful for the analysis of availability and determination of the best possible maintenance strategies in a fertilizer plant concerned.

Chemical Process Plant as a complex system requires good scientific knowledge on different issues including Process Safety Analysis (PSA). Fuzzy logic is the collective name for “Fuzzy set analysis” and “Possibility theory”, able to use random or approximate data in the Process Safety Analysis. This paper explains the impact of fuzzy set theory for basic tools used in Process Safety Analysis. It also discusses the sources and types of uncertainties encountered in PSA and also methods to deal with them. There are different methods to improve the quality of the PSA, for example sensitivity analysis, expert systems, statistics and fuzzy logic.Fuzzy logic is one of the promising methods for reliability assessment. The traditional PSA tools like Fault Tree analysis (FTA) and Event Tree (ET) were trimmed and free of uncertainty by the application of Fuzzy logic. Now these tools provide correct process risk level and safety assurance.

Advances in Mechatronics and Mechanical Engineering

Reliability is one of the important aspects in product quality that shows efficiency or operation of the product, failure rate, and confidence. When the efficiency of the product is reduced below a desired level, the product is said to have failure. In real world, data collection or access of detailed features of the system is often difficult because of incomplete or unavailable information and probabilistic approach to the conventional reliability analysis. Therefore, to solve this problem, fuzzy set theory is used to evaluate system reliability. This research studies the literature on the reliability of fuzzy systems. Several studies have shown that fuzzy logic method can be more appropriate in comparison with classical methods and mathematical modeling.

Journal of Quality and Reliability Engineering, 2013

The present paper investigates the reliability analysis of industrial systems by using vague lambda-tau methodology in which information related to system components is uncertain and imprecise in nature. The uncertainties in the data are handled with the help of intuitionistic fuzzy set (IFS) theory rather than fuzzy set theory. Various reliability parameters are addressed for strengthening the analysis in terms of degree of acceptance and rejection of IFS. Performance as well as sensitivity analysis of the system parameter has been investigated for accessing the impact of taking wrong combinations on its performance. Finally results are compared with the existing traditional crisp and fuzzy methodologies results. The technique has been demonstrated through a case study of bleaching unit of a paper mill.

Journal of Mathematics and Statistics, 2009

Problem statement: The purpose of this study was to compute fuzzy reliability and fuzzy availability of the serial process in butter-oil processing plant for various choices of failure and repair rates of sub-system. This plant consists of eight sub-systems out of which two are supported by standby units with perfect switch over devices and considered that these two sub-systems never fail. The effect of coverage factor on the fuzzy availability also studied. Approach: In this study the chapman-Kolmogorov differential equations were formed using mnemonic rule from the transition diagram of the butter-oil processing plant. These equations were solved for steady state recursively and results were obtained by computer program. Results: Result in the study analyzed fuzzy availability for various values of system coverage factor, failure and repair rates. Industrial implications of the results also briefly discussed. Conclusion: The findings in the study suggested that the management of butteroil processing plant's sensitive sub-system is important to improve its performance.