Plant Power Utility Systems

A number of utilities are required to run a chemical plant cooling water, steam at various pressure levels, electricity, refrigeration, air, and inert gas (nitrogen). Those utilities associated with providing power (electricity and steam) normally generate both electricity and process steam. The two most common power plants are  

After the steam is used in the various plant unit operations, it is typically returned as condensate to the boiler house for reuse. 

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Electric Power System Design For specific applications, fuel cells can be used to supply DC power distribution systems designed to feed DC drives such as motors or solenoids, controls, and other auxiliary system equipment. The goal of the commercial fuel cell power plant is to deliver usable AC power to an electrical distribution system. This goal is accomplished through a subsystem that has the capability to deliver the real power (watts) and reactive power (VARS) to a facility s internal power distribution system or to a utility s grid. The power conditioning... 

IFC has been marketing the PC25, a 200 kW atmospheric PAFC unit, since 1992. Details of this commercial cycle are proprietary and not available for publication. In order to discuss an example PAFC cycle, a pressurized (8 atm) 12 MW system will be presented (50). This cycle is very similar to the 11 MW IFC PAFC cycle that went into operation in 1991 in the Tokyo Electric Power Company system at the Goi Thermal Station, except that two performance enhancements have been incorporated. Limited data are available regarding the Goi power plant. However, it is understood that the average cell voltage is 750 mV and the fuel utilization is 80% (51). The enhanced 12 MW cycle presented here utilizes values of 760 mV and 86%. This enhanced cycle (Figure 9-8) is discussed below with selected gas compositions presented in Table 9-6. 

Hydropower provides an essential contribution to the national power grid its capability to respond in seconds to large and rapidly varying loads, which other baseload plants with steam systems powered by combustion or nuclear processes cannot accommodate. Also, ownership is spread over a broad base. The owners comprise federal and state agencies, cities, metropolitan water districts, irrigation companies, and public and independent utilities. Individual persons also own small plants at remote sites for their own eneigy needs and for sale to utilities... 

Seawater-based utility systems for condenser and process cooling systems in power plants exhibit serious corrosion, erosion and fouling problems. Equipment made from carbon steel and even stainless steel shows sign of degradation from galvanic effect, corrosion, erosion and microbiological induced corrosion (MIC). Corrosion... 

Wind Power Plant A group of wind turbines interconnected to a common utility system through a system of transformers, distribution lines and (usually) one substation. Operation, control and maintenance functions are often centralized through a network of computerized monitoring systems, supplemented by visual inspection. This is a term commonly used in the United States. In Europe, it is called a generating station. 

Besides the main components, particular emphasis was placed on the essential subsystems/peripherals/balance-of-plant, including utility and auxiliary subsystems (instrument/operating air supplies, nitrogen supply, demineralised water/KOH systems, ventilation, etc.), process and safety control subsystems, and extensive test data acquisition subsystems. Also power conditioning (converters and inverters) as a way of improving the operability and efficiency of the overall system was considered. Some of the integration issues investigated in detail were ... 

An important early step is the definition of system boundaries within which impacts are accounted for. A good example of the issues in system boundary definition is the case of utility systems. The process plant in Figure 6 may consume electricity, but this consumption implies impacts at the power station through fuel combustion and water use. For a coal-fired power station, this, in turn, implies impacts at the coal mine. If the plant consumes natural gas for heating, impacts in exploration, extraction, treatment, and compression of the natural gas are implied. The environmental impacts incurred in such utility systems have... 

Problems with utility systems are probably the most prevalent of common cause effects, as already illustrated with the electrical power event in the fault trees shown above. Utilities such as electrical power, cooling water, steam, and plant air are typically used throughout a facility. Should they fail, many other systems are likely to fail at the same time. 

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