Complex system of a thermal power plant

Simulation modeling and analysis of a complex system of a thermal power plant, The present paper deals with the opportunities for the modeling of flue gas and air system of a thermal power plant by making the performance evaluation using probabilistic approach. The present system of thermal plant under study consists of four subsystems with three possible states: full working, reduced capacity working and failed. Failure and repair rates for all the subsystems are assumed to be constant. Formulation of the problem is carried out using Markov Birth-Death process using probabilistic approach and a transition diagram represents the operational behavior of the system. Interrelationship among the full working and reduced working has been developed. A probabilistic model has been developed, considering some assumptions. Data in feasible range are selected from a survey of thermal plant and the effect of each subsystem on the system availability is tabulated in the form of availability matrices, which provides various performance/availability levels for different combinations of failure and repair rates of all subsystems. Based upon various availability values obtained in availability matrices and graphs of failure/repair rates of different subsystems, performance and optimum values of failure/repair rates for maximum availability, of each subsystem is analyzed and then maintenance priorities are decided for all subsystems.

The thermal industry is becoming quite complex with a huge capital investment being incurred on process automation to enhance the reliability of system. Invariably, the proper maintenance of such systems and the frequency of maintenance are some of the issues that are gaining importance in industry. The production suffers due to failure of any intermediate system even for small interval of time. The cause of failure may be due to poor design, system complexity, poor maintenance, lack of communication and coordination, defective planning, lack of expertise/experience and scarcity of inventories. Thus, to run a process plant highly skilled/ experienced maintenance personnel are required. According to Kumar and Pandey (1993), for efficient functioning, it is essential that various systems of the plant remain in upstate as far as possible. However, during operation they are liable to fail in a random fashion. The failed subsystem can however be inducted back into service after repairs/replacements. The rate of failure of the subsystems in the particular system depends upon the operating conditions and repair policies used.

A probabilistic analysis of the system under given operative conditions is helpful in forecasting the equipment behavior which further helps in design to achieve minimum failure in the system i.e. to optimize the system working. A thermal power plant is a complex engineering system comprising of various systems: coal handling, steam generation, cooling water, crushing, ash handling, power generation, feed water, steam & water analysis system and flue gas & air system. These systems are connected in complex configuration. One of the most important functionaries of a thermal plant is flue gas & air system. The optimization of each system in relation to one another is imperative to make the plant profitable and viable for operation. Effectiveness of thermal power plant is mainly influenced by the availability, reliability and maintainability of the plant, and its capability to perform as expected. The present paper provides a probabilistic model to plant personnel to analyse system performance and to achieve the maximum availability. Some of the salient features of the proposed model are as follows:

  • The proposed model provides an integrated modeling and analysis framework for performance evaluation of the flue gas and air system of thermal plant
  • The proposed model combines a strong mathematical foundation with an intuitive graphical representation
  • The transition diagram represents the possible states of the system.

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