Electric power drives

It can be seen from Figure 13 that the results meet the standard GB 12668.3, EN 55022A and lEC 61800 (Adjustable speed electrical power drive system—Part 3 EMC requirements and specific test methods) after using the new EMI filter. 

Inspection and maintenance periods should be determined by reference to the recommendations of the manufacturer, consideration of the operating conditions and the environment in which equipment is located. The importance of equipment within the plant, from the plant safety and operational viewpoint, will also have a bearing on inspection and maintenance periods. The mechanical safety of driven machinery is vital and the electrical maintenance and isolation of the electrically powered drives is an essential part of that safety. 

BS EN 61800-5-2 2007 Adjustable Speed Electrical Power Drive Systems... 

The hot gases from the combustor, temperature controlled to 980°C by excess air, are expanded through the gas turbine, driving the air compressor and generating electricity. Sensible heat in the gas turbine exhaust is recovered in a waste heat boiler by generating steam for additional electrical power production. 

Many units have waste heat recovery systems that generate low pressure steam from reaction heat. Such steam is often employed to drive adsorption refrigeration units to cool the reactor feed stream and to increase polymer conversion per pass, an energy-saving process that reduces the demand for electrical power. 

Steam turbines are divided into two broad categories those used for generating electric power and general-purpose units used for driving pumps, compressors, etc., and frequently called mechanical-drive turbines. 

Any downtime of an expander results in significant lost revenue. When this particular damage occurred, the user no longer obtained power from the process to drive the equipment. Instead, the user was forced to buy electricity to drive the axial compressor. Depending on the power capability of the expander, losses of 300,000 per month or greater may be experienced. 

One of the critical measurements is torque or shaft power. A variety of methods is recognized direct methods such as torque meters or reaction mounted drivers (dynamometers) and indirect methods such as electrical power input to drive motors, heat balance, or heat input to a loop cooler. See Part 7, Measurement of Shaft Power, PTC 19.7 1961 [3] for additional information. 

There is a close kinship between the chemical process industry and the nuclear electric power industry. In tact once the physics of nuclear reaction was established the rest is chemistiy and hc.it ii an.sfer. The word "reactor" is from chemistry for the location the reaction takes place.. nuclear reactor consists of a vessel in which a nuclear reaction heats water to make steam to drive a turbine o generate electricity. Thus the primary components are pipes, valves, pumps heat exchangers, and water purifiers similar to the components found in a chemical plant. Following the success of WASH-1400, PSA was used to analyze the chemical proce.ssmg of nuclear fuel and. aste preparation for disposal. 

The Joule-Brayton (JB) constant pressure closed cycle is the basis of the cyclic gas turbine power plant, with steady flow of air (or gas) through a compressor, heater, turbine, cooler within a closed circuit (Fig. 1.4). The turbine drives the compressor and a generator delivering the electrical power, heat is supplied at a constant pressure and is also rejected at constant pressure. The temperature-entropy diagram for this cycle is also... 

All process plants require both steam and electric power in their operations. Power is cither purchased from local utility companies or generated at the plant site. Even if power is generated by the process plant, arrangements for standby power from the local utility must be made for emergency purposes. Steam is rarely purchased but is generated at the plant for use in the process and as a driving medium for pumps and compressors. 

Large-scale crude oil exploitation began in the late nineteenth century. Internal combustion engines, which make use of the heat and kinetic energy of controlled explosions in a combustion chamber, were developed at approximately the same time. The pioneers in this field were Nikolaus Otto and Gottleib Daimler. These devices were rapidly adapted to military purposes. Small internal-combustion motors were used to drive dynamos to provide electric power to fortifications in Europe and the United States before the outbreak of World War I. Several armies experimented vith automobile transportation before 1914. The growing demand for fossil fuels in the early decades of the twentieth centuiy was exacerbated by the modernizing armies that slowly introduced mechanization into their orders of battle. The traditional companions of the soldier, the horse and mule, were slowly replaced by the armored car and the truck in the early twentieth century. 

Steam turbines, which generate more than 80 percent of the world s electric power, differ from steam engines m that steam drives blades and not pistons. Steam turbines expand pressurized steam through nozzles that accelerate the steam at the expense of heat energy and pressure. Work is created by transferring a portion of steam velocity to blades, buckets, or nozzles affixed to a rotor to move at high speeds. Steam turbines are relatively compact in relation to steam... 

Figure 12-5F. Lubricated and nonlubricated balanced opposed process reciprocating compressors, designed to API 618 code. Fixed- and variable-speed drives using gas or diesel engines, steam or gas turbines, or electric motor. Note power drive to connect to right side of cross-head box in center. (Used by permission Bui. PROM 635/115/95-11. Nuovo Pignone S. P. A., Florence, Italy New York Los Angeles and Houston, Texas. All rights reserved.)...

As discussed in Section 15.2.2, the gas turbine s main disadvantage is its low efficiency of around 25-35 per cent in open cycle. However, this can be significantly improved by the use of a heat-recovery boiler that converts a good proportion of the otherwise waste heat in the turbine exhaust gases to high-pressure superheated steam, which, in turn, drives a conventional steam turbogenerator for supplementary electrical power. This can increase the overall efficiency to 50 per cent for no further heat input as fuel. 

Among the advantages of electric motor drive are compactness and ease of control. The internal combustion engine is preferred for mobile units, emergency standby units, or where electric power is not available. 

From an engineering point of view, a more relevant figure-of-meril is the power efficiency t]r(J), defined as the ratio of emitted optical power to the driving electrical power. It is given by ... 

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