Part-Load Behavior of a Solar-Heated and Fossil-Fuelled Gas Turbine Power Plant

Solar energy can be converted effectively into electrical or mechanical energy. The radiant heat of the sun is collected by a parabolic dish, concentrated intensely and reflected into a cavity receiver. Air flowing through tube panels in front of the receiver inner walls absorbs the radiant energy. Downstream of the receiver is a fossil-fired combustion chamber (hybrid construction). The fuel energy is converted at a higher utilization than in a straight fossil-fuelled power plant. The overall efficiency of the hybrid plant rises with increasing turbine inlet temperature. The power delivered by the turbine serves to drive the compressor and the generator. A description of the thermodynamic design of the cycle is followed by statements on the performance characteristics of the individual components and by a description of the steady-state part-load behavior of the plant considering specific conditions such as variations in solar and fossil fuel-generated heat and fluctuating load on the power transmission grid.

The Extension of Gas Turbine Power Plants to Combined Cycle Power Stations

In industrial countries as well as in developing countries there is a continuous growth of electricity consumption. The normal way to meet these requirements is the stepwise extension of electricity producing plants. In countries where clean fuel is available at acceptable prices the advantages of combined cycle plants in terms of efficiency and of smooth meeting the requirements can be used. The following essay concentrates on the influences of design criterias and ambient conditions on efficiency, output and plant cost for the type of CCP which is most frequently excecuted. As a result of an optimization an executed plant is described also with regard to lay out, required space and erection time.

Row Resolved Heat Transfer Variations in Pin-Fin Arrays Including Effects of Non-Uniform Arrays and Flow Convergence

Measured streamwise (longitudinal) heat transfer variations, spanwise (transverse) averaged and resolved to single row spacings, are presented for large aspect ratio ducts containing staggered arrays of circular pin fins which span the entire duct height. A number of different array geometries have been investigated in an experimental program, including uniformly spaced arrays in constant cross sectional area ducts with streamwise row spacings over the range 1.5 to 5.0 pin diameters. Such arrays, with pin length-to-diameter ratio of order unity, are often used to enhance heat transfer in internal cooling passages of gas turbine engine airfoils. The effects of various length interruptions in the pin pattern and of abrapt changes in pin diameter are presented for constant cross sectional area ducts. In addition, results are presented for the effect of duct convergence, a common situation in the cooled turbine airfoil application. A concise summary of all the observed behavior is given, useful for predicting the performance of arbitrarily spaced pin fin arrays that may be specified to produce a particular cooling distribution. Predictions are compared with two final test, configurations which combine aspects of all of the effects investigated in the experimental program.

Rotating Heat Transfer Experiments With Turbine Airfoil Internal Flow Passages

Internal convective cooling is used to maintain acceptable gas turbine rotor blade temperatures. The heat transfer from the blade coolant passage walls is governed by forced convection, Coriolis forces and buoyance due to wall and coolant temperature differences. Currently little data is available to designers regarding the combined effects of these three parameters. To obtain required data, a rotating heat transfer facility was developed for experiments with large scale models and run at rotation and flow parameters typical of current gas turbine operating conditions. Analysis of the equations of motion showed that the perinent nondimensional parameters were Reynolds number, Rossby number, the difference in wall fluid and bulk fluid density and geometric ratios. The models were instrumented to measure average heat transfer rates on the coolant passage wall elements, and with pressure taps for friction data. An initial set of experiments have been conducted with rough wall geometries, typical of those used in blades. Results from the rotating experiments showed large heat transfer coefficient increases and decreases on the coolant passage leading and trailing surfaces compared to nonrotating heat transfer coefficients. The heat transfer was shown to be a function of inward or outward flow direction and Rossby number for the experiments conducted.

Dynamic Behavior of a Solar Heated Receiver of a Gas Turbine Plant

The mainly instationary operation of a solar heated receiver can be simulated with sufficient accuracy only if data about the dynamic behavior are available. For this reason, the dynamic behavior of a solar cavity receiver with parabolic dish collector is investigated. The development of a mathematical simulation considering heat transfer and storage processes is presented and the procedure for a numerical solution is illustrated. The performance of the calculation method is finally demonstrated by simulating the passage of a cloud.

Selective Catalytic Reduction Impact on Heat Recovery Steam Generator Design and Operation

Selective Catalytic Reduction (SCR) is a post-combustion method to reduce the oxides of nitrogen (NOx), present in flue gases such as gas turbine exhaust streams, to N2 and water. It involves the injection of ammonia and the use of a catalyst module to promote the reaction to obtain high efficiency (60–86+%) NOx reduction. Several operating parameters can influence catalyst performance to include temperature, gas flow distribution, presence of sulfur compounds and catalyst age. This paper examines the impact of a SCR integration in a gas turbine heat recovery steam generator (HRSG) design/operation. Limitations on HRSG load and following capabilities, effect on capital cost and overall performance and current SCR system experience represent a number of areas that are examined.

Analysis and Optimization of a Compressed Air Energy Storage System in Aquifer

This paper discusses the thermo-economic analysis and optimization of a constant pressure Compressed Air Energy Storage system, in aquifer, subjected to an exogenous, periodic electricity price function of the interconnection. The target function considered is the net benefit of the plant. It is related to the fundamental planning parameters of the system like the compressor pressure ratio, the maximum temperature ratio, the charging-discharging duration ratio and the plant capacity factor. The results of the analysis permit to obtain the optimal values of the fundamental parameters to be used in the planning process.

Small Diameter Film Cooling Holes: Wall Convective Heat Transfer

The wall heat transfer resulting from small diameter holes drilled at 90° through gas turbine combustion chamber and turbine blade walls is considered. Available information is briefly reviewed and shown to generally omit the hole approach surface heat transfer and to relate only to the internal hole heat transfer. Experimental techniques are described for the determination of the overall heat transfer in a metal plate with a large number of coolant holes drilled at 90°. The results are compared with conventional short-tube internal heat transfer measurements and shown to involve much higher heat transfer rates and this mainly resulted from the additional hole approach flow heat transfer.

Measurements of Mass Transfer Coefficient and Effectiveness in the Recovery Region of a Film-Cooled Surface

Mass transfer coefficients and the film cooling effectiveness are measured downstream of a single row of holes inclined 30 degrees with the surface and inline with the main turbulent boundary layer flow. The mass transfer coefficients (based on the difference between the free stream and the surface concentrations) are measured using a naphthalene sublimation technique. The effectiveness is determined through the injection of a trace gas into the secondary (cooling jets) flow and measuring its concentration at the impermeable wall. Experiments are carried out in a subsonic, zero pressure gradient turbulent boundary layer, under isothermal conditions with three blowing ratios (Uj/U∞): 0.4, 0.8, and 1.2. The data is collected in a region 7 to 80 jet diameters downstream of the injection location. From the data on mass transfer coefficients and effectiveness obtained under the same flow conditions a general mass transfer equation is derived. This paper presents extensive data and discussions; and is believed to be one of the few studies in which both of these variables are measured on the same surface and in a large area in the recovery region.

Acid Corrosion in a CAES Recuperator

Cold end corrosion and deposit formation due to sulfuric acid is a phenomenon not uncommon in boilers and waste heat boilers. Normally, the operating conditions can be changed to reduce or eliminate the corrosion and deposition problem. In a Compressed Air Energy Storage (CAES) recuperator, changing the operating conditions is not a practical solution. This paper presents the results of three different test periods using various materials at different operating temperatures.