Evaluation of Combustion Turbine Systems for the Direct Combustion of Coal

A combustion turbine combined cycle that uses coal-derived dirty fuels can be economical if the fuel is processed at the plant site and cost of electricity (COE) is used as the criterion for configuring the power system and selecting its components. In a DOE/METC-sponsored study, 12 combinations of power components and conditioning components were evaluated for each of two fuels: a gas made from coal and a coal/water slurry. One baseline system was selected from each group of 12 systems, based on its potential to achieve a low COE. Each baseline system was then parametrically evaluated to show the effects of specific components on the COE of the power plant. In one of these studies, on-site coal conversion was shown as the key to reducing the COE and the operating cost of the plant, thus improving the chances of the plant being used for baseload operation.

A Method to Measure the Fuel Distribution and the Fuel Captured by V–Gutter Flameholder in High Speed Airstream

A method to measure the fuel distribution and the percentage of fuel flow rate captured by a V-gutter flameholder in a high speed airstream has been developed. The effects of configuration and size of the probe and temprature of the sample mixture in the probe on measurement have been investigated. The detailed determination of isokinetic sampling condition is described. The effects of V-gutter geometry on flowfield have been considered. The total experimental error is of the order ±5%.

Investigation of the Sampling Representativeness With Different Probes in a Gas Turbine Combustor

Three types of 12-orifice mixing cruciform sampling probes, i.e. the sampling orifices with or without stub pipes and arranged in spiral form or on three radii, and one single orifice traversing probe were used to investigate the sampling representativeness in the measurement of gas turbine emissions. The results obtained in the experiment show that the distribution of carbon monoxide, CO, and smoke number, S.N., may have certain relations with the distribution of fuel and air in the combustor, and the three types of probes mentioned, the angular position of the cruciform probe and the manner of extracting sample off the mixing probe can make a deviation of less than 1 S.N. for smoke and about 5% for carbon monoxide.

Sampling and Analysis of Alkali in High-Temperature, High-Pressure Gasification Streams

This paper describes the experiences leading to successful sampling of hot, contaminated, coal-derived gas streams for alkali constituents using advanced spectrometers. This activity was integrated with a multi-phase, combustion test program which addressed the use of minimally treated, coal-derived fuel gas in gas turbines. Alkali contaminants in coal-derived fuels are a source of concern, as they may induce corrosion of and deposition on turbine components. Real-time measurement of alkali concentrations in gasifier output fuel gas streams is important in evaluating these effects on turbine performance. An automated, dual-channel, flame atomic emission spectrometer was used to obtain on-line measurements of total sodium and potassium mass loadings (vapors and particles) in two process streams at the General Electric fixed-bed coal gasifier and turbine combustor simulator facility in Schenectady, New York. Alkali measurements were taken on (1) slipstreams of high temperature, high pressure, minimally clean, low-Btu fuel gas containing entrained particles from the gasifier and (2) a slipstream of the exhaust gas from the combustor/turbine simulator. Alkali detection limits for the analyzer were found to be on the order of one part per billion. Providing a representative sample to the alkali analyzer at the limited flows required by the instrument was a major challenge of this activity. Several approaches and sampling hardware configurations were utilized with varying degrees of success during this testing campaign. The resulting information formed the basis for a second generation sampling system which has recently been successfully utilized to measure alkali concentrations in slipstreams from the described fixed-bed coal gasifier and turbine combustor simulator.

An Experimental Study of the Mixing by an Acoustically Pulsed Axisymmetrical Air-Jet

The mixing by an acoustically pulsed axisymmetrical air-jet, flowing into the atmosphere, has been studied by means of velocity and temperature profile measurements. The strength of the velocity pulsation imparted to the jet flow and of the associated toroidal vortices were also measured. The entrainment rate was increased by up to two times, with the majority of the extra entrainment occurring over the first five diameters downstream of the jet orifice, where toroidal vortices are formed and attain their greatest strength. The jet response depends on Strouhal number and appears to be optimum at about 0.25. The response starts to saturate at the limit of pulsation strength used.

Gas Turbine Intake Filter Systems Related to Offshore Platform Installations

This Paper covers various aspects with respect to the selection and operation of air filtration associated to offshore gas turbine installations. As the Offshore North Sea industry moves into its second decade, Operators are still trying to improve machine availability and reduce maintenance costs. One of the main contributing factors in their failure to achieve the ideal condition has been poor inlet air filtration caused by bad design and incorrect filter selection. The majority of offshore installations are equipped with filter systems which were originally designed for use on ocean-going vessels. The performance of what has become known as the “High Velocity Salt Eliminator System” has, in most cases, been unsatisfactory, thereby creating a necessity for a continuing search into alternative filter systems. The experiences of most Operators in the North Sea have been very similar, and examination of the platform environment explains why this should be the case. To emphasize the affects of poor air filtration and the savings that can be achieved by the Operator in recognising and correcting the problems, specific reference is made to the experience of Mobil North Sea with the Beryl Alpha Production Platform.

Technical Evaluation of Simplified IGCC Components

Simplified integrated gasification combined cycle (IGCC) power plants offer attractive advantages for improving the performance of coal to electricity systems. This plant configuration, which utilizes a coal gasifier, hot gas cleanup system, and gas turbine combined cycle, has the potential to reduce both capital costs for equipment and fuel costs through improved efficiency. This paper reports the results of fuel supply and gas turbine testing on actual hot low-Btu coal gas. A pilot-scale advanced fixed-bed gasifier has been modified to supply hot coal gas to a particulate removal cyclone and then to a gas turbine simulator. The hot gas is combusted in a General Electric MS6000 combustor developed for low-Btu gas fuel. The combusted product flows through a MS6000 turbine first-stage nozzle sector. The exhaust gases from the nozzle sector pass over air-cooled cylindrical ash deposition pin specimens and then into a water quench exhaust system. Extensive instrumentation and sampling provisions are utilized to characterize the fuel gas, the combustion gases, and the ash deposits formed on turbine components. Two regimes of nozzle metal surface temperatures have been investigated by separate testing performed including 500–600 °F with water-cooled and 1500–1650 °F with air-cooled nozzle sectors. Results from the test program have provided key data related to fuel gas cleanup and the tolerance of gas turbine hot gas path parts to the products of combustion from coal-derived fuels.

Onshore Test Method for a 3 Unit 60 MW Gas Turbine-Generator Power Module

There has been an increasing demand for onshore testing of equipment destined for offshore operation. The justification for this requirement can be summarized as follows: 1. High cost of offshore commissioning where even minor faults detected, constitutes potentially serious problems. 2. Consequenses of delay of platform start-up are enormous. 3. Skilled experienced personel and diagnostic equipment is available onshore, and rectification of new units will benefit from the existence of previous experience. 4. Spare and renewal parts availability. This paper describes the method for string testing of a 3 unit 60 mw utility gasturbine-generator power module built for the gullfaks A platform in the Norwegian sector of the north sea. It describes the test facility and test equipment set up and also the test program which was followed. At the time of writing the paper the test program was barely initiated, and for that reason the test results will be presented in the form of an addendum to this paper during the meeting.

Vibration Baseline, a Useful Concept for Condition Monitoring of Rotating Equipment

The condition of rotating equipment can be assessed using vibration measuring techniques. A number of these techniques including signal processing and analysis methods will be discussed briefly. Finally experiences on gas turbines and centrifugal compressors, operating in the Dutch gas transmission system, will be used to define a useful vibration baseline for condition monitoring, maintenance purposes and availability.

Investigation of Swirler/Dilution Jet Flow Split on Primary Zone Flow Patterns in a Water Model Can-Type Combustor

LDA measurements of the three mean velocity components and the corresponding turbulence intensities have been made to provide qualitative and quantitative information on the flow field in a water model of a can type gas turbine combustion chamber. The combustor geometry comprised a swirl driven primary zone, annulus fed rows of primary and secondary jets and an exit contraction. The effect of variation of the flow split between the swirler and the dilution holes on the flow pattern in the primary zone has been investigated in detail. Flow visualisation studies revealed that significant changes occur in this region due to the interaction between the swirling flow and the radially directed primary jets. A large toroidal recirculation was formed and high levels of turbulence energy generated in the core of the combustor at low levels of swirler flow rate. As the swirl level increases the strength of this recirculation was observed to weaken and become less stable. Beyond a critical level, the primary recirculation was pushed off centre and the undesirable feature of a forward velocity on the combustor axis in the primary zone was observed. Despite the dramatic changes brought about in the primary zone the flow pattern downstream of the secondary jets was practically the same for all flow splits due to the strong mixing caused by the two rows of jets.