Comparison of Various Fluidized Bed Combustor-Gas Turbine Systems

Pressurizing a fluidized bed combustor with a gas turbine greatly improves both sulfur retention and combustion efficiency. Operating the gas turbine with a high inlet temperature (e.g. 900°C) would yield a thermal efficiency about four points higher than for an atmospheric furnace, but 40 y of experience have failed to solve problems with flyash erosion and deposits. Extensive experience such as that with fluidized bed catalytic cracking units indicates that the gas turbine blade erosion and deposit problems can be handled by dropping the turbine inlet temperature below 400°C where the turbine delivers just enough power to drive the compressor. The resulting thermal efficiency is about half a point higher than for an atmospheric bed, and the capital cost of the FBC-related components is about 40% lower. While a closed-cycle helium gas turbine might be used rather than a steam cycle, the thermal efficiency would be about four points lower and the capital cost of the FBC-related components would be roughly twice that for the corresponding steam plant.

Numerical Method for Fuel Distribution Downstream of the Emulsifying Channel Injector

Based upon experimental results, the physical processes of fuel-air mixture formation downstream of the emulsifying channel injector (ECI) have been studied and a calculation model for predicting fuel distribution downstream of ECI has been proposed in this paper. The two-dimensional differential equation of diffusion is solved by numerical method and the fuel distribution downstream of ECI is calculated. The calculated values are in good agreement with the experimental results.

The Effect of Inlet Air Vitiation on Combustion Efficiency

Experimental results of the effect of inlet air vitiation produced by a vitiating preheater on combustion efficiency of a turbojet combustor and a model ramjet combustor are presented in this paper. An empirical correlation and a calculation method based on stirred reactor theory are derived to correct the vitiation effect. Results obtained by means of these two methods are in good agreement with test data.

Development of a Small Gas Turbine Combustor With Airblast Atomizer

Kawasaki Heavy Industries, Ltd. has recently developed the S5 gas turbine at rated output power of 24 KW for use primarily in driving generators. This paper describes the engineering difficulties we experienced in developing the combustor for the small gas turbine, and its performance characteristics. Particular difficulties that confronted us in developing the combustor that uses the airblast atomizer are ignition, combustor lean flame out limit and carbon deposit. To work out these problems, we used a “click baffle” in the airblast atomizer, and optimized combustor configuration and air flow distribution as well.

The Production of Jet Fuel From Alternate Sources

The most significant potential source of aviation gas turbine fuels in the continental United States of America is the western oil shale located in the Rocky Mountain States of Colorado, Utah, and Wyoming. Nearly 600 billion barrels of recoverable oil is located in this area. This paper discusses the availability of oil shale and reviews the recovery, upgrading and refining schemes necessary to produce fuel which can be used in present-day aircraft. Other synthetic fuels are discussed with regard to the processing necessary to produce suitable fuels for today’s high performance aircraft. Heavy oil and tar sand bitumen are likely to be refined in the next decade. Methods for producing suitable fuels are discussed. The chemical structure of these sources, which is basically cyclic, leads to the potential of heavier fuels with more energy per given volume and therefore longer range for certain aircraft. This exciting possibility is reviewed.

Fuel Deposit Characteristics at Low Velocity

An experimental program has been carried out to characterize the relationship between deposit mass, operating time and temperature in studies of the thermal stability of aviation gas turbine fuel. This information is required by fuel system designers to prevent deposit build-up in fuel system components, thus allowing for more efficient designs. The program has included the design, fabrication, and operation of a novel thermal stability test apparatus for the determination of deposition rates over a range of temperatures and test durations up to several hundred hours. Experiments were run to determine the rate of deposit formation as a function of temperature in heated stainless steel tubes at low velocity using Jet A fuel. The test tube had an inside diameter of 0.22 cm, a length of 0.91 m, and a flow rate of 0.73 kg/hr. Deposits obtained were often characterized as thick, porous, and non-uniform in nature. Deposit density, based on carbon content was 0.08 g/cm3. Deposit rates of 0.1 to 100 μgC/hr-cm2 were observed at surface temperatures between 400 and 600 K.

Study on Two-Phase Fuel Distributions in High Speed Hot Transverse Air Stream

It was found that fuel distribution in a hot high speed transverse air stream differed greatly from that in a cold stream. In a hot air stream there exist two-phase fuel distributions, hence, two mass center lines extending downstream. Experimental results of fuel distributions are presented. By using the model of trajectory with diffusion and also considering the fuel evaporation, a semi-empirical method to predict two-phase fuel distributions has been developed.

A Preliminary Calculation of the Combustion Recirculating Flow Behind Flame-Holders

In this paper the numerical method is adopted to predict the combustion recirculating flow behind flame-holders. A modified k-ε turbulence model and Magnussen’s combustion model are employed. Becouse of the large variation of density in combustion flow field, the influences of variable density have been considered. The results predicted include: the combustion recirculating flow field and the flame spreading; the variation of recirculation length with equivalence ratio, and inlet velocity, etc. All of these are qualitatively good comparing with experimental results.

Gaseous Fuels Capability of Industrial Gas Turbines

This paper describes the successful development and application of industrial gas turbines using alternate gaseous fuels. These fuels include liquid petroleum gas, medium-Btu fuels derived from biodegradation of organic matters found in sanitary landfills and liquid sewage, and ultra-low Btu fuels from oilfield fireflood operations. The analyses, mathematical modelling and rig verification performed in the development are discussed. The effects of burning these alternate fuels on the gas turbine and its combustion system are compared to those of using standard natural gas fuel. Gas turbine development required to use other alternative gaseous fuels is also assessed.

The Local Analytic Numerical Method for the Double Vortex Combustor Flow

A new hyperbolic function discretization equation for two dimensional Navier-Stokes equation in the stream function vorticity from is derived. The basic idea of this method is to integrat the total flux of the general variable ϕ in the differential equations, then incorporate the local analytic solutions in hyperbolic function for the one-dimensional linearized transport equation. The hyperbolic discretization (HD) scheme can more accurately represent the conservation and transport properties of the governing equation. The method is tested in a range of Reynolds number (Re=100~2000) using the viscous incompressible flow in a square cavity. It is proved that the HD scheme is stable for moderately high Reynolds number and accurate even for coarse grids. After some proper extension, the method is applied to predict the flow field in a new type combustor with air blast double-vortex and obtained some useful results.