Basic gas turbine cycles

In Section 3.4, we consider the open gas turbine cycle in which fuel is supplied in a combustion chamber and the working fiuids before and after combustion are assumed to be separate semi-perfect gases, each with Cp(T), c (T), but with R = [Cp T) — Cv( )l constant. Some analytical work is presented, but recently the major emphasis has been on computer solutions using gas property tables results of such computations are presented in Section 3.5. 

Subsequently, in Chapter 4, we deal with cycles in which the turbines are cooled. The basic thermodynamics of turbine cooling, and its effect on plant efficiency, are considered. In Chapter 5, some detailed calculations of the performance of gas turbines with cooling are presented. 

We adopt the nomenclature introduced by Hawthorne and Davis [1], in which compressor, heater, turbine and heat exchanger are denoted by C, H, T and X, respectively, and subscripts R and I indicate internally reversible and irreversible processes. For the open cycle, the heater is replaced by a burner, B. Thus, for example, [CBTX]i indicates an open irreversible regenerative cycle. Later in this book, we shall in addition, use subscripts 

U and C referring to uncooled and cooled turbines in a plant, but in this chapter, all cycles are assumed to be uncooled and these subscripts are not used. 

It is implied that the states referred to in any cycle are stagnation states but as velocities are assumed to be low, stagnation and static states are virtually identical. 

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There are several modifications to the basic gas turbine cycle that may be introduced to raise thermal efficiency. 

An examination of the above standards as they apply to the gas turbine and its auxiliaries are further examined in this section. The ASME B 133.2 basic gas turbines and the API standard 616, gas turbines for the petroleum, chemical, and gas industry services are intended to cover the minimum specifications necessary to maintain a high degree of reliability in an open-cycle gas turbine for mechanical drive, generator drive, or hot-gas generation. The standard also covers the necessary auxiliary requirements directly or indirectly by referring to other listed standards. 

Lloyd carried out a range of similar calculations, for differing thermodynamic parameters the results are presented in Fig. 8.12 in comparison with those for a basic STIG cycle with the same parameters of pressure ratio and maximum temperature. There is indeed similarity between the two sets, with the TCR plant having a higher efficiency. It is noteworthy that both cycles obtain high thermal efficiency at quite low pressure ratios as one would expect for what are essentially CBTX recuperative gas turbine cycles. 

The basic gas turbine generates in the open-cycle mode and Figure 15.4 illustrates this. Air is drawn into a compressor and after compression passes into a combustion chamber. At this stage, energy is supplied to the combustion chamber by injecting fuel, and the resultant hot gases expand through the turbine. The turbine directly drives the... 

Figure 15.4 Basic gas turbine in open-cycle mode...

The basic gas Brayton refrigeration cycle is the reversed Brayton gas power cycle. The components of the basic gas refrigeration cycle include a compressor, a cooler, a turbine, and a heater, as shown in Fig. 6.26. 

The thermodynamic analysis presented here is an outline of the air-standard Bray ton cycle and its various modifications. These modifications are evaluated to examine the effects they have on the basic cycle. One of the most important is the augmentation of power in a gas turbine, this is treated in a special section in this chapter. 

In the search for higher plant thermal efficiency, the simplicity of the two basic STIG and EGT cycles, as described by Frutschi and Plancherel, has to some extent been lost in the substantial modifications described above. But there have been other less complex proposals for water injection into the simple unrecuperated open cycle gas turbine one simply involves water injection at entry to the compressor, and is usually known as inlet fog boosting (IFB) the other involves the front part of an RWI cycle, i.e. water injection in an evaporative intercooler, usually in a high pressure ratio aero-derivative gas turbine plant. 

We consider next the cycles B of Table 8.IB and the associated Figs. 8.9-8.12 these cycles involve modification of the fuel used in the combustion process by TCR. There are two basic types of chemically recuperated gas turbine (CRGT) cycle ... 

After allowing for the performance penalties arising from the CO2 removal, Lozza and Chiesa estimated an efficiency of 46.1%, for a maximum gas turbine temperature of 1641 K and a pressure ratio of 15 (compared with the basic CCGT plant efficiency of 56.1%). They concluded that the plant cannot compete, in terms of electricity price, with a semi-closed combined cycle with CO2 removal (Cycle A2). 

Figure 16-8. This Brayton cycle describes the basic operation of a gas turbine.

Diesels, gas turbines and steam turbines are the more commonly used prime movers for the generation of electrical power. Additionally, the steam turbine can be employed in combination with either the diesel or gas turbine for combined cycle operation. The following describes the basic operation of each of these prime movers in relation to its associated power-generating scheme and reviews the more significant factors affecting performance and efficiency. Further information on the actual plant and installation is given later in Section 15.6. 

Figure 6.1 Basic components of a simple cycle gas turbine.

Heat engines that use gases as the working fluid in an open system model are treated in this chapter. The modern gas turbine engine operates on the Brayton cycle. The basic Brayton cycle consists of an isentropic compression process, an isobaric combustion process, an isentropic... 

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