Calculating plant efficiency

Was the meter really a problem The primary reasons for suspicion were the calculated plant efficiency (with no operating history, this figure was questionable) and the calculated UNACCOUNTED FOR GAS, the accuracy of which was also questionable. 

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. 

Fig. 4.10. Calculation of efficiency of. -iimple CBT plant—single-step cooled [CBT n ] as a function of iseniropic temperature ratio with maximum temperature (7 ) as a parameter.

Fig. 4.11. Calculation of efficiency of simple CBT plants—single-.step cooled ICBTlica uncooled [CBT ]ii—a.s a function of specific work with pressure ratio (r) and maximum temperature as parameters and with r)p< = t), = 0.9. 7hi = 1073 K (after Ref. 5 ).

Fig. 4.12. Calculation of efficiency of ICBT] plant uncoolcd CBT uj a.s a function of combustion lemperalurc (7eoi) single-step cooled (CBT)k i as a function of rotor inlet temperature (TVi,). Pres,sure ratio r = 30. t)c — 0.8.

Chapter 5. Full calculations of plant efficiency A new temperature difference ratio is written as... 

Fig. 6.4 then shows a more complete calculation of plant efficiency for varying S. The optimum condition of maximum efficiency is reached at 5 = 0.208. The picture changes for a gas turbine with a higher pressure ratio, for which the increase to maximum efficiency is less, as is the optimum value of S 2]. 

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... 

With the fuel energy input known from the calculation of the gas turbine plant performance, F = Aff[CV]o, the combined plant efficiency is determined as... 

Newby et al. 6 also studied a steam/TCR cycle with similar parameters and steam/air ratio. They calculated an efficiency of 48.7%, compared with 35.7% for a comparable CBT plant, 45.6% for a STIG plant and 56.8% for a CCGT plant, all for similar pressure ratios and top temperatures. 

A gas turbine plant with an overall efficiency t]cq = 0.25 matching a heat load Acc, = 2.25 is again considered as the basic CHP plant also implied is a non-useful heat rejection ratio (Cnu)cg( cg = [1 ( cg)( g + 1)1 =. 3/16. For FESR calculations, we again take the conventional plant efficiency as 0.4 and the conventional boiler efficiency as 0.9. At the fully matched condition the.se assumptions previously led to EUF = 0.8125 and FESR = 0.2. 

Some experiences with olfactometric measurements in connection with odour abatement processes, mainly in sewage sludge and waste water treatment plants and in the fish meal industry, are presented. Studies have been carried out to calculate the efficiency of various odour reducing Methods. The additional information provided by the measurements was of practical use for the management of the process to improve odour reducing efficiency. 

Calculate the efficiency of a combined-cycle electricity generating plant. In this plant, the gaseous products of combustion at 1500°C are first directed into a gas turbine, from which the gas exits at 900°C and which operates at 90% of theoretical efficiency. Eighty-five percent of the energy of the effluent from the turbine is used to produce steam at 500°C. This steam is used in a steam electric generating plant which uses a river at 30°C as a cold reservoir and operates at 55% of theoretical efficiency. 

Frequently process plants contain recycle streams and control loops, and the solution for the stream properties requires iterative calculations. Thus efficient numerical methods for convergence must be used. In addition, appropriate physical properties and thermodynamic data have to be retrieved fi om a data base. Finally, a master program must exist that links all the building blocks, physical property data, thermodynamic calculations, subroutines, and numerical subroutines, and that also supervises the information flow. You will find that optimization and economic anafy-sis are really the ultimate goal in the use of flowsheet codes. 

TABLE 14.11 Results of power plant efficiency calculations ... 

The following equations are used by the plant chemist to calculate column efficiencies ... 

SNG meter flow computer. The overall plant efficiency is also calculated which is another check on both the process and the metering (Figure 7). 

Design Basis is the design inputs, the design constraints, and the design analysis and calculations, It includes topical areas such as seismic qualification, fire protections, and safe shutdown, It encompasses consideration of such factors as plant availability, plant efficiency, costs, and maintainability, and that subset that relates to safety and the authorization basis. 

Efficiency is the ratio of actual units produced to the standard rate of production expected in a time period, or actual hours of production to standard hours, or actual dollar volume to a standard dollar volume in a time period. For example, if there is a standard of 100 pieces per hour and 780 units are produced in one eight-hour shift, the efficiency is 780/800 multiplied by 100, or 97.5%. Another term that some companies use is operating efficiency. This is defined by the APICS Dictionary as a ratio (represented as a percentage) of the actual output of a piece of equipment, department, or plant as compared to the planned or standard output. For example, if the standard time for production of a part at your work center is 10 minutes and you have 420 minutes of capacity available at your work center (i.e., you can produce 42 parts in a shift), you would calculate your efficiency for an output of 50 parts during that 420 minutes as (50/42) (100) = 119%. 

The importance of the moderator cost to the power cost for a nuclear plant can be seen by the very approximate data indicated in Table VI. In this table, the cost contribution of the moderator material has been calculated for reactor conditions typical of some gas-cooled reactors. The capital cost of the moderator in dollars per installed kilowatt(e) is related to the unit cost of the moderator, the moderator/fuel weight ratio, the reactor specific power, and the plant efficiency by... 

Reduced penalty for higher heat rejection temperatures. The capital costs of dry cooling systems can be reduced by rejecting heat at a higher temperature but with the penalty of lower plant efficiency. That penalty becomes smaller as the peak temperature of the power cycle increases. For the AHTR Brayton cycle with a minimum helium temperature of 35°C, the losses in efficiency for a 10°C rise in the compressor inlet temperature were calculated to be 1.5, 1.3, and 1.1%, respectively, for AHTR peak coolant temperatures of 705, 800, and 1000°C. 

Kriebitzsch [77] determined the net primary production (NPP) of two light and two shadow plant species by means of bomb calorimetry and calculated their efficiencies as percentage of energy fixed in dry matter related to solar radiation energy. Efficiency was more homogeneous among the four species in a shaded area (0.9 to 2.2 %) than in the open field (0.4 to 2.7 %) with a maximum NPP of about 860 MJ/(ha.d). 

The calculated thermal efficiency represents also the power plant efficiency. 

In Section 3.6 we described briefly a simple steam power plant and in Example 3.12 we calculated the thermal (or power plant) efficiency of such a plant. For this purpose we used an arbitrary set of operating... 

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