Steam turbines calculations

Cost of 10-barg steam. Here, 41-barg steam is now expanded to 10 barg in a steam turbine. Details of steam turbine calculations were gpven in Sec. 6.7. From steam tables, inlet conditions at 41 barg and 400 C are... 

Even for this simplest CCGT plant, iterations on such a calculation are required, with various values of p, in order to meet the requirements set on T, the steam turbine entry temperature, and 7s (the calculated value of 7s has to be such that the dewpoint temperature of the gas (7jp) is below the economiser water entry temperature (7b) and that may not be achievable). But with the ratio /i satisfactorily determined, the work output from the lower cycle Wl can be estimated and the combined plant efficiency obtained from... 

This chapter discusses centrifugal compressors and steam turbines. Centrifugal compressors are best discussed by going through a calculation procedure and discussing each part. 

A steam turbine operates with inlet steam conditions of 40 barg and 420°C and can be assumed to operate with an isentropic efficiency of 80% and a mechanical efficiency of 95%. Calculate the power production for a steam flowrate of 10 kg s-1 and the heat available per kg in the exhaust steam (i.e. superheat plus latent heat) for outlet conditions of ... 

A steam turbine is operating between inlet steam of 40 barg and 420°C and outlet steam of 5 barg. Using the Willans Line Model with parameters from Table 23.1 for large turbines and intercept ratio of 0.05, calculate the power production for a turbine at full load with a flowrate of steam of 10 kg s-1. 

The carbon emission reduction of the two considered storage options is calculated with reference to a conventional gas turbine or gas and steam turbine. The result is shown in Fig. 16.6. The emission reduction refers to 1 kWh surplus wind electricity. The black bars reflect the reference emissions of the conventional gas turbine (GT) and gas-steam turbines (GST). The other bars show the figures for the CAES and the hydrogen paths. The emissions that occur during the storage paths are marked in grey the emission reduction is visualised in grey and white stripes. 

The performance of a SOFC system with a Brayton-Rankine bottoming cycle for heat and fuel recovery has been calculated. Gas turbine compressor and expander efficiencies of 83% and 89% and a steam turbine efficiency of 90% have been assumed. 

An interesting application of this approach in another field has been described by Keller (K2). In the design of steam turbines rather complicated heat-balance calculations are required. While each particular installation is different, and therefore requires a different mathematical model, the components of each turbine are always similar. A large-scale computer program was developed, therefore, which would through suitable instructions combine the calculations required for each component into an over-all heat balance for the turbine. 

Step 6. Multiply the horsepower per pound of steam value calculated in step 5 by the turbine steam flow, in pounds per hour. This is the total shaft work that appears at the turbine s coupling. This is the amount of horsepower that is available to spin a centrifugal pump. 

Official Properties. The International Association for Properties of Water and Steam (IAPWS), an association of national committees that maintains the official standard properties of steam and water for power cycle use, maintains two formulations of the properties of water and steam. The first is an industrial formulation, the official properties for the calculation of steam power plant cycles. This formulation is appropriate from 0.001 to 100 MPa (0.12-1450 psia) and from 0 to 800 C (32-1472 F) and also from 0.001 to 10 MPa (0.12-145 psia) between 800 and 2000°C (1472 3632 F). This formulation is used in the design of steam turbines and power cycles. IAPWS maintains a second formulation of the properties of water and steam for scientific and general use from 0.01 MPa (extrapolating to ideal gas) at O C (1.45 psia at 32 F) to the highest temperatures and pressures for which reliable information is available. 

The air-feed compressor is a dual-stage unit with a calculated duty of 3 MW. Compressor shaft power is provided by tail-gas expansion (80% of required power) and a steam turbine. 

The calculations for the steam-turbine condenser can only be performed if the steam condensate flowrate is known. This... 

Boiler Feedpump Drives. Second-Law techniques are applied to a practical problem determing when to drive feedpumps with electric motors and when to use steam turbines. This analysis was performed by Fehring and Gaggioli (40) for the Wisconsin Electric Power company. The Second-Law costing procedures are straightforward, avoiding the extremely laborious calculations associated with traditional methods, and/or avoiding the erroneous conclusions often drawn when those methods are simplified. 

To size a steam turbine requires calculating the steam flow rate, which will eventually be needed to size a steam boiler. A summary of equations for sizing a steam turbine are given in Table 5.11 and the calculation procedure in Table 5.12. In this case, the mass balance is simple in that the steam flow rate into the turbine is equal to the steam and the condensate flow rate out of the turbine. 

Table 5.12 Calculating Procedure for Sizing Steam Turbines ...

The two-part nomograph presented here estimates the electrical power generated at the alternator terminals. If the electrical power is known, the extracted or condensed steam flow in the turbine can be estimated. Estimation is quick and accurate it does not require aids such as the steam tables, calculators or personal computers. 

CHP applications based on a state of the art technology show a realistic scenario. The industrial steam turbine CHP with a CF-value of 0,75 is much nearer to competitiveness as the steam piston engine CHP, (Existing Austrian industrial steam turbine CHP plants in pulp mills can use very low value or negative value biomass and therefore are corr )etitive compared to fossil fuels). The co-combustion of biomass in coal power plants seems to be not competitive at the first look. In Austria a big size co-combustion different to the application investigated is analysed at the moment first calculations show very good chances with CF-values of about 1. As these calculations are based on sensible company data, they are not integrated in this paper. 

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