| The flue-gas desulphurization (FGD) system in coal-fired power plants is in the initial period of large-scale construction and operation in China. Strict monitoring began to be conducted over the operating status of the desulphurization system, which has already become an evidence of assessment on the onto-grid electricity prices for FGD equipment in power plants. It is very hard for the enterprise to reach the requirements of power plant on security, reliability, economization and high efficiency due to poor reliability of desulphurization system. At present, few researches are developed on the reliability of FGD. Most of thermal power plants have measured FGD reliabilities mainly in accordance with the desulphurization efficiency and the service rate. The article has dealt with the reliability of flue-gas desulphurization system from these aspects including the assessment of reliability, analysis of factors and Optimization of maintainment.The evaluation system for the reliability of FGD system is established in accordance with the feature of desulphurization system and the requirements of operating verification index. Firstly, it is necessary to make reasonable division on the status of FGD reliability; secondly, to proposed 12 characteristic; finally, Procedure for point estimates and confidence intervals of 5 characteristic is provided. The maintenance factor is given to describe the status of reliability so as to set up the model of FGD reliability growth. After the flue-gas desulphurization facilities have been constructed, the acceptance inspection and compliance test are required to be done on the reliability status of the facilities. The total time for acceptance inspection and the appraisal evidences shall be determined for reliability characteristic qualities. A project of verification test shows the effectiveness of the proposed method in the article.In the article, detail analyses are made on the factors which may affect the health conditions of main equipments including desulphurization flue, booster fan, flue damper, flue gas heat exchanger, circulation slurry pump, absorption tower, limestone preparing system and plaster dehydrating system. Corrosion, scaling, wear, clogging, fouling and leaks are thought to be main reasons which may affect the reliability of main equipment. Comprehensive measures have been provided to improve the reliability of main equipment through the enhancement of process conditions, the control of optimum operation and the increase of maintenance and repairing.Taking the reliability of 2×600MW wet-process FGD operation as research object, its operational reliability is researched with the tool of reliability design technology. The reliability block diagram of the system is drawn; reliability model is established according to the logic and relationships of the subsystems; fix the service rate (SR) as the characteristic quantity of reliability in the system operational reliability; allocate total reliability indexes by using estimated failure rate allocation method and calculate the examples; divide the operational reliability model into four levels such as system, subsystem, equipment and parts; make failure mode, effects and criticality analysis (FMECA) on those parts; establish key equipment parts which may affect operational reliability of the system and its failure mode so as to supply analysis evidence for the optimization of the system.In accordance to media property of the environment to which main equipment and equipment parts attribute, dry/wet state, temperature, wear and the corrosive ion concentration, it is divided into strong corrosive division, weak corrosive division, non-corrosive division, strong wear division and weak wear division. The failure mechanism of anticorrosive material used in FGD installations is approached. By introducing relevant theories related to damage tolerance into the evaluation of glass-flake coatings, put forward the evaluation test method on damage tolerance of glass-flake coatings, formulate the steps of damage tolerance evaluation and enact the evaluation test standard on damage tolerance of glass-flake coatings. The damage failure period of anti-corrosive glass-flake coatings is divided into four stages, stipulating the failure features of every stage and treatment measures with strong operation. Aiming at more use of fiber reinforce plastic (FRP) structural components in FGD system and the failure to judge its aging in the course of use, the reliability of aging course for FRP structural components and the model for service life calculation are seted up.Reliability centered maintenance (RCM) is introduced into the maintenance and inspection of FGD system. The optimization procedure of maintenance strategy is designed. In the course of the implementation of maintenance strategy optimization, the norms to evaluate the probability of failure occurrence in FGD system has been formulated by virtue of qualitative method. The influence of the failure upon the equipment itself and the whole system is estimated by taking the systematic view. The matrix of FGD risk evaluation is established, and the classification of equipment and regular maintenance in accordance with the result of risk evaluation is realized...
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