Utility power

In the ease of an offshore facility, electrical power is generally ge ated on site by engine- or turbine-driven generator sets using natural or diesel as fuel. Most installations are designed to handle the total e tri. 1 even if one generator is out of service. To minimize the siz st quipment, some facilities have a system to automatically f 

The choice of whether to purchase or generate electricity and decisions on generator or cable configuration and sparing are often not obvious. An economic study evaluating capital and operating costs and system reliability of several alternatives may be required. 

Utility companies have a power system network including large generating plants, overhead transmission lines, power substations which reduce transmission line voltages to distribution line voltages, and over-head/underground distribution lines which carry power to the end users (such as a production facility). 

The electrical distribution system design and equipment selection must consider requirements of the utility company for protection and metering. Available short circuit currents from the utility distribution network to the primary of the facility s main transfoiTner must be considered in selecting circuit protection devices for the facility distribution system. 

In calculating generator loads it must be remembered that each motor will only draw the load demanded by the process. It is this load and not the nameplate rating of the motor that should be used in the load list. For example, even though a pump is driven by a 100 hp motor, if the process conditions only demand 75 hp, the total load that will be demanded from the generator is 75 hp. 

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Utility Data Institute. (1994). Electric Utility Power Plant Construction Costs. Washington DC Utility Data Institute. 

The following sections describe the various compliance options for controlling emissions from utility power plants. 

For example, sulfur emissions from utility power plants in the United States are subject to an emissions cap and an allowance-trading system established under the Clean Air Act. An effective cap on annual sulfur dioxide emissions took effect in 2000, so no more than 8.95 million tons of SO can be emitted annually. Utilities that want to build another coal plant must purchase sulfur emission allowances from others who do not need them. This system provides a market incentive for utilities to reduce their sulfur emissions as long as the cost of such reductions is less than the price of purchasing the allowances. 

Bolton, H. R. and Ray, N. J., Non-Utility Power Generation Steam Plant. Inst. Mech. Eng. (1989)... 

Very large, modem WT boilers with sophisticated heat-recovery auxiliaries may attain efficiencies approaching 88 to 90%. However, the overall efficiency of a fossil fuel utility power generation plant system falls to only 32 to 38% when the efficiency of electricity generation and condenser cooling is included. Nevertheless, it only requires 10% more in fuel costs to operate a boiler at 1,250 psig than... 

The first three boiler types may be variously used for commercial, institutional, or industrial applications. Fire tube boilers also may be used for steam turbine generator duty at lower electrical outputs, whereas only WT and nuclear reactor boilers are employed for utility power generation. 

Water tube boilers are installed in all manner of commercial and institutional buildings, smaller industries, large industrial processors, and power generators. (In fact, the utility power industry is the single largest user of WT boiler capacity in the world.)... 

Utility power boilers Most modem plants usually operate at over 1,500 to 2,000 psig and feature some of the most complex engineering available in the world. Older plants may operate at only, say, 450 to 950 psig. 

Figure 2.6 (a) Small WT boiler, for HW/steam (b) large D-type, steam raising, industrial WT boiler (c) radiant WT boiler for utility power and (d) pulp mill recovery boiler, burning black liquor. 

Radiant power boilers are two-phase boilers. Designs typically employ only one drum for the largest installations, whereas smaller power boiler designs generally incorporate two drums. Fossil fuel-fed, radiant power boilers are probably the most common type of equipment employed for large-scale utility power generation. 

Power boilers typically produce one kWh of electricity for every 8,500 to 9,500 Btu (8,968-10,023 kJ) gross fuel input, providing a net thermal efficiency of 34 to 40%. (As a rule, utility power plants are seldom more than 34 to 36% efficient, although some modem designs may go as high as 40%.)... 

Water treatment for utility power boilers must be first class and generally necessitates extremely sophisticated pre- and post-boiler treatment processes. Internal water chemistry usually rellies on the use of caustic-free, phosphate treatment or all-volatile treatment (AVT) programs. 

Although the complexity of operating an average industrial boiler plant (with perhaps only two or three FT boilers) cannot be compared to that of a large utility power generating station, the potential for waterside problems, while different, may be just as difficult to control. As an example, consider some differences between a utility and a factory. 

NOTE As a consequence of the different kinds of operational and management problems associated with raising steam in industrial boiler plants, it often requires a different mindset than that needed for a base-load utility power house, where personnel strive to maintain steady-state (but knife-edge) operating conditions. The differences between industrial plants and power generators is also reflected in the waterside chemistries and monitoring and control objectives of their respective boiler plant systems. 

Closed FW heaters, which are specialist shell and tube heat exchangers for utility power application... 

Feedwater heaters also may be considered as BOP equipment (with the exception of economizers), especially in utility power plants. Blowdown receivers and flash steam and heat recovery (FSHR) also may be considered BOP equipment. 

NOTE This book is not primarily intended for nuclear or utility power plant facilities, which often require ultrapure water of even higher specifications than those discussed in this chapter. Reaching the highest possible levels of purity requires additional controls, use of nitrogen blankets, submicron filters, and point-of-use polishers. 

HP utility power-generating stations, operational standards ... 

For example, in some very specialized areas of boiler water treatment (such as nuclear power units and especially utility power generation), there is probably little or nothing of any practical value that service companies can teach the current practitioners. 

Chu, P and D.B. Porcella. 1995. Mercury stack emissions from U.S. electric utility power plants. Water Air Soil Pollut. 80 135-144. 

Failure Mode - The action of a device or system to revert to a specified state upon failure of the utility power source that normally activates or controls the device or system. Failure modes are normally specified as fail open (FO), fail closed (FC) or fail steady (FS) which will result in a fail safe or fail to danger arrangement. 

Steam turbines are an even older technology, providing power for over 100 years. Most utility power is produced by steam turbines. The steam turbine generator depends on a separate heat source for steam, often some type of boiler, which may run on a variety of fuels, such as coal, natural gas, petroleum, uranium, wood and waste products including wood chips or agricultural by-products. 

M. Farooque, "Evaluation of Gas-Cooled Pressurized Phosphoric Acid Fuel Cells for Electric Utility Power Generation," Final Technical Report, NASA CR-168298 prepared by Energy Research Corp. under Contract No. DEN 3-201 for NASA Lewis Research Center, September 1983. 

A diagnostic system for the steam system chemistry of utility power plants is described. It is an expert system which accepts data from a monitoring system and generates... 

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