Turbine High pressure

Example 23.2 A process heating duty of 25 MW is to be supplied by the exhaust steam of a back-pressure turbine. High-pressure steam at 100 barg with a temperature of 485°C is to be expanded to 20 barg for process heating. The heating duty of the 20 barg steam can be assumed to be the sum of the superheat... 

One refrigeration system is electrically driven a second is operated by a condensing turbine. High pressure steam from a power house is pressure-reduced for use by the plant as it passes through one air compressor turbine, one refrigeration machine turbine, and the high pressure section of the turbogenerator. 

HPST. See turbine, high-pressure, steam HPT. See turbine, high-pressure HRI. See Hydrocarbon Research Institute HT. See temperature, hemispherical HTFT. See Fischer-Tropsch (FT) synthesis, high-temperature... 

A common thread in many of the reactor technologies that currently exist or that are under development is the use of water as the heat transport medium (the coolant ). In many respects, water is an ideal coolant, because it has a high heat capacity, can be obtained in a high purity, is inexpensive, has a wide liquid range (0-374.15 °C), is easily handled, and had been used since the dawn of steam power. Thus, in their most fundamental form, water-cooled nuclear reactors (WC-NRs) comprise a nuclear boiler, a heat transport system (piping, channels, steam generators, etc.), a set of turbines (high pressure, intermediate pressure, and low... 

Figure 6.33 shows a steam turbine integrated with the process above the pinch. Heat Qhp is taken into the process from high-pressure steam. The balance of the hot utility demand Qlp is taken... 

Exampie A.3.1 The pressures for three steam mains have been set to the conditions given in Table A.l. Medium- and low-pressure steam are generated by expanding high-pressure steam through a steam turbine with an isentropic efficiency of 80 percent. The cost of fuel is 4.00 GJ and the cost of electricity is 0.07 h. Boiler feedwater is available at 100°C with a heat capacity... 

The efficiency of gas turbines is limited by the maximum allowable turbine inlet temperature (TIT). The TIT may be increased by cooling of the blades and vanes of the high pressure turbine. Cooling channels can be casted into the components or may be drilled afterwards. Non-conventional processes like EDM, ECD or Laser are used for drilling. Radiographic examination of the drilled components is part of the inspection procedure. Traditional X-Ray film technique has been used. The consumable costs, the waste disposal and the limited capacity of the two film units lead to the decision to investigate the alternative of Real-Time X-Ray. 

An important application of the HMT is the test for ferrous inclusions in high pressure turbine disks made from a non-magnetic metal alloy. On principle, such ferrous inclusions can be introduced during the manufacturing process and, if present, they can be the origin of cracks in these most critical parts. Therefore such tests are stringent necessary. 

Niobium carbide is used as a component of hard metals, eg, mixtures of metal carbides that are cemented with cobalt, iron, and nickel. Along with tantalum carbide, niobium carbide is added to impart toughness and shock and erosion resistance. The spiraling rise in the price of tantalum has spurred the development of a hafnium carbide—niobium carbide substitute for tantalum carbide (68). These cemented carbides are used for tool bits, drill bits, shovel teeth, and other wear-resistant components turbine blades and as dies in high pressure apparatus (see Carbides). 

The superheated steam generated in the superheater section is coHected in a header pipe that leads to the plant s high pressure steam turbine. The steam turbine s rotor consists of consecutive sets of large, curved, steel aHoy disks, each of which anchors a row of precision-cast turbine blades, also caHed buckets, which protmde tangentiaHy from the shaft and impart rotation to the shaft when impacted by jets of high pressure steam. Rows of stationary blades are anchored to the steam turbine s outer sheH and are located between the rows of moving rotor blades. 

PWRs operate differendy from BWRs. In PWRs, no boiling takes place in the primary heat-transfer loop. Instead, only heating of highly pressurized water occurs. In a separate heat-exchanger vessel, heat is transferred from the pressurized water circuit to a secondary water circuit that operates at a lower pressure and therefore enables boiling. Because of thermal transfer limitations, ultimate steam conditions in PWR power plants ate similar to those in BWR plants. For this reason, materials used in nuclear plant steam turbines and piping must be more resistant to erosion and thermal stresses than those used in conventional units. 

The steam balance in the plant shown in Figure 2 enables all pumps and blowers to be turbine-driven by high pressure steam from the boiler. The low pressure exhaust system is used in the reboiler of the recovery system and the condensate returns to the boiler. Although there is generally some excess power capacity in the high pressure steam for driving other equipment, eg, compressors in the carbon dioxide Hquefaction plant, all the steam produced by the boiler is condensed in the recovery system. This provides a weU-balanced plant ia which few external utiUties are required and combustion conditions can be controlled to maintain efficient operation. 

The second law can also suggest appropriate corrective action. Eor example, in combustion, preheating the air or firing at high pressure in a gas turbine, as is done for an ethylene (qv) cracking furnace, improves energy efficiency by reducing the lost work of combustion (Eig. 4). 

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