Plant systems

Programs to develop MCFC technology are also under way in Europe. Ansaldo SpA (Italy) is setting up faciUties to produce 1-m cells in an automated process, and their goal is to test 100-kW stacks in 1994. The 100-kW stack is also to be tested by IBERDROLA in Spain as part of a complete power plant system. Two Dutch companies. Stork and Royal Schelde, have joined with the Dutch government to form Brandstofcel Nederland (BCN), which plans to test a 50-kW MCFC and two 250-kW MCFC stacks in 1994. 

Air pollutants may enter plant systems by either a primary or a secondary pathway. The primary pathway is analogous to human inhalation. Figure 8-2 shows the cross section of a leaf. Both of the outer surfaces are covered by a layer of epidermal cells, which help in moisture retention. Between the epidermal layers are the mesophyll cells—the spongy and palisade parenchyma. The leaf has a vascular bundle which carries water, minerals, and carbohydrates throughout the plant. Two important features shown in Fig. 8-2 are the openings in the epidermal layers called stomates, which are controlled by guard cells which can open and close, and air spaces in the interior of the leaf. 

The subtle interaction of air pollutants with these other stressors to plants and vegetation is the subject of ongoing research. For some plant systems, exposure to air pollutants may induce biochemical modifications which interfere with the water balance in plants, thereby reducing their ability to tolerate drought conditions. 

The turbine temperature, flow, and speed increases in a very short time of about three to five minutes to the full rated parameters. There is usually a short period of time where the temperature may overshoot. If supplementary firing or steam injection for power augmentation is part of the plant system, these should be turned on only after the gas turbine has reached full flow. The injection of steam for power augmentation, if done before full load, could cause the gas turbine compressor to surge. 

The H AZOP leader selects an appropriate aspect of the plant s process systems (a process node) and associated systems that affect the selected process variable for the selected mode of plant operation. The selection may be made fiom the plant system classification, or it may be from the nodal analysis of the process. 

The frequencies of plant damage and public consequence are calculated using plant logic combined with component fragilities. Event and fault trees are constructed to identify tiic accident sequences and the damage that may result from an earthquake. In performing a plant system and accident-sequence analysis, the major differences between seismic and internal events analysis are given in Table 5.1-4... 

The first step-in plant-system and accident-sequence analysis is the identification of earthquake-induced initiating events. This is done by reviewing the internal analysis initiating events to identify initiating events relevant to seismic risk. For example. Table 5,1 -5 shows the initiating events that were used in the Seismic Safety Margins Research Program for a PWR plant (Smith et al., 1981)... 

A flooding analysis for major plant systems uses a qualitative fault tree that takes into account the elevation of system components. This procedure, illustrated in Figure 5.3-1, uses a fault tree captioned for the top event, "core melt due to internal flood." The fault tree is developed under the assumption that a flood causes a transient, small, or large LOCA, or causes the failure of... 

Nuclear power plant systems may be classified as "Frontline" and "Support. . iccurding to their. service in an accident. Frontline systems are the engineered safety systems that deal directly with an accident. Support systems support the frontline systems. Accident initiators are broadly grouped as loss of cooling accidents (LOCAs) or transients. In a LOCA, water cooling the reactor is lost by failure of the cooling envelope. These are typically classified as small-small (SSLOCA), smalt (SLOCA), medium (MLOCA) and large (LLOCA). 

Analysis of External Events uses the models developed in the plant system analysis with considerations for seismic, fire, flood, high winds and missiles on the plant. Additional c cm trees or their equivalent may be needed for the external events. 

Lisk, K, C., 1972 Nuclear Power Plant Systems and Equipment Industrial Press, NY. 

Wilkins, D. R. and J. Chang, 1992, GE Advanced Boiling Water Reactors and Plant System Designs. 8th Pacific Basin Nuclear Conference, Taiwan, April. 

Plant system the equipment belongs to, e.g., feed-water... 

Discuss the advantages and disadvantages of physical versus computer modeling of plant systems. 

A fault tree is a grapliic teclmique used to analyze complex systems. The objective is to spotlight conditions tliat cause a system to fail. Fault tree analysis attempts to describe how and why an accident or otlier undesirable event lias occurred. It may also be used to describe how and why an accident or otlier undesirable event could take place. Thus fault tree analysis finds wide application in hazard analysis and risk assessment of process and plant systems. ... 

Pumping of liquids is almosl universal in chemical and petrochemical processes. The many different materials being processed require close attention to selection of materials of construction of the various pump parts, shaft sealing, and the hydraulics of the individual problems. A wide variety of qqtes and sizes of pumps have been developed to satisfy the many special conditions found in chemical plant systems however, since all of these cannot be discussed here, the omission of some does not mean that they may not be suitable for a service. 

To properly accomplish a good and thorough rat-ing/sizing of a centrifugal pump, the plant system designer should at a minimum ... 

Utility unit costs as well as any preference for maximum operating economy or minimum first cost should be stated if the manufacturer is to make a selection to best fit the plant system and economics. 

The use of vibration analysis is not restricted to predictive maintenance. This technique is useful for diagnostic applications as well. Vibration monitoring and analysis are the primary diagnostic tools for most mechanical systems that are used to manufacture products. When used properly, vibration data provide the means to maintain optimum operating conditions and efficiency of critical plant systems. Vibration analysis can be used to evaluate fluid flow through pipes or vessels, to detect leaks, and to perform a variety of non-destmctive testing functions that improve the reliability and performance of critical plant systems. 

The foundation must support the weight of the baghouse. In addition, it must absorb the vibrations generated by the cleaning system. This is especially true when using the shaker-cleaning method, which can generate vibrations that can adversely affect the structural supports, foundation, and adjacent plant systems. 

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