An Experimental Study of Water Injection Into a Rolls-Royce Model 250-C20B Turboshaft Gas Turbine

Author(s):  
Daniel Golden ◽  
Martin Cerza ◽  
David Myre
Author(s):  
Nicolas Demougeot ◽  
Jeffrey A. Benoit

The search for power plant sustainability options continues as regulating agencies exert more stringent industrial gas turbine emission requirements on operators. Purchasing power for resale, de-commissioning current capabilities altogether and repowering by replacing or converting existing equipment to comply with emissions standards are economic-driven options contemplated by many mature gas turbine operators. NRG’s Gilbert power plant based in Milford, NJ began commercial operation in 1974 and is fitted with four (4) natural gas fired GE’s 7B gas turbine generators with two each exhausting to HRSG’s feeding one (1) steam turbine generator. The gas turbine units, originally configured with diffusion flame combustion systems with water injection, were each emitting 35 ppm NOx with the New Jersey High Energy Demand Day (HEED) regulatory mandate to reduce NOx emissions to sub 10 ppm by May 1st, 2015. Studies were conducted by the operator to evaluate the economic viability & installation of environmental controls to reduce NOx emissions. It was determined that installation of post-combustion environmental controls at the facility was both cost prohibitive and technically challenging, and would require a fundamental reconfiguration of the facility. Based on this economic analysis, the ultra-low emission combustion system conversion package was selected as the best cost-benefit solution. This technical paper will focus on the ultra low emissions technology and key features employed to achieve these low emissions, a description of the design challenges and solution to those, a summary of the customer considerations in down selecting options and an overview of the conversion scope. Finally, a technical discussion of the low emissions operational flexibility will be provided including performance results of the converted units.


Author(s):  
Joseph Rabovitser ◽  
Stan Wohadlo ◽  
John M. Pratapas ◽  
Serguei Nester ◽  
Mehmet Tartan ◽  
...  

Paper presents the results from development and successful testing of a 200 kW POGT prototype. There are two major design features that distinguish POGT from a conventional gas turbine: a POGT utilizes a partial oxidation reactor (POR) in place of a conventional combustor which leads to a much smaller compressor requirement versus comparably rated conventional gas turbine. From a thermodynamic perspective, the working fluid provided by the POR has higher specific heat than lean combustion products enabling the POGT expander to extract more energy per unit mass of fluid. The POGT exhaust is actually a secondary fuel gas that can be combusted in different bottoming cycles or used as synthesis gas for hydrogen or other chemicals production. Conversion steps for modifying a 200 kW radial turbine to POGT duty are described including: utilization of the existing (unmodified) expander; replacement of the combustor with a POR unit; introduction of steam for cooling of the internal turbine structure; and installation of a bypass air port for bleeding excess air from the compressor discharge because of 45% reduction in combustion air requirements. The engine controls that were re-configured for start-up and operation are reviewed including automation of POGT start-up and loading during light-off at lean condition, transition from lean to rich combustion during acceleration, speed control and stabilization under rich operation. Changes were implemented in microprocessor-based controllers. The fully-integrated POGT unit was installed and operated in a dedicated test cell at GTI equipped with extensive process instrumentation and data acquisition systems. Results from a parametric experimental study of POGT operation for co-production of power and H2-enriched synthesis gas are provided.


Author(s):  
Hai Zhang ◽  
Qun Zheng ◽  
Mustapha Chaker ◽  
Cyrus Meher-Homji

The air pressure drop over the nozzles manifolds of inlet fogging system and the flow resistance downstream of the nozzle array (manifold) have always been an area of concern and is the object of this paper. Fogging nozzles arrays (involving several hundred nozzles) are mounted on channels and beams, downstream of the inlet filters and affect the pressure drop. The water injection angle, nozzle injection velocities and the progressive evaporation of the water droplets evaporation all influence the inlet pressure seen at the gas turbine inlet. This paper focuses on a numerical simulation investigation of flow resistance (pressure drop) of inlet fogging systems. In this research effort, the inlet duct is meshed in order to compute the pressure drop over the nozzles frames in fogging and non-fogging conditions. First, the resistance coefficients of an air intake filter are obtained by numerical and experimental methods, and then the coefficients are used for the simulation of the inlet duct by considering the filter as a porous media. Effects of nozzle spread pattern and water injection pattern are then modeled. The results indicate that injection velocity and arrangement of nozzles could have significant effects on the pressure drop and intake distortion, which will affect compressor performance. This paper provides a comprehensive analysis of the pressure drop and evaporation of inlet fogging and will be of value to gas turbine inlet fogging system designers and users.


Author(s):  
Malath I. Arar

Gas Turbine, GT, control methodology applied to power generation is being evaluated. Corrected parameter control methodology has been adopted for this purpose. This method uses the corrected physical ambient conditions such as pressure, temperature and humidity in controlling the GT operations. Humidity correction becomes increasingly important in this control scheme. The following are the reasons for accurate and robust humidity measurement: (1) Humidity measurement is important to the operation control of the dry low NOX, DLN, combustor system. (2) GT inlet performance enhancing devices, such as evaporative coolers and inlet foggers, depend upon the accurate humidity measurement to determine the amount of water needed for inlet temperature depression. (3) Humidity measurement is used to determine the amount of water to be injected in the combustor for NOX abatement when running on liquid fuel as an alternative to natural gas fuel. In order to obtain accurate and reliable humidity readings, several commercially available humidity sensors were extensively tested and evaluated in a controlled laboratory environment. The sensors were tested for their measurement accuracy, saturation conditions, power interruption and surge, sudden temperature changes and medium air speed. Test ambient temperature ranges from −30 °C to 50 °C. This covers the operating ambient conditions range for the Gas Turbine. The test criterion is that the error in the response of the sensor shall not exceed ±1 °C from the test reference for all the tests conducted on the sensors. The combustion requirements for Dry Low NOX operations and mode transfer dictate this criterion. Also, as a DLN requirement, error in specific humidity shall not exceed 0.904 g/g of air. This test criterion also satisfies the water injection requirements for NOX abatement and inlet performance enhancing devices. The results show that for ±1 °C error in the sensor measurement, the resulting error in NOX calculation is less than 0.2 ppm. The test results show that all sensors except the current one in use have met the test criterion. The current sensor, General Eastern DT-2, has a large measurement error in the order of ±5 °C. Programs have been launched to field test and evaluate these sensors in order to replace the current one.


Author(s):  
Frederick E. Moreno ◽  
Philip J. Divirgilio

A gas turbine cogeneration system is described that offers fuel flexibility plus substantially reduced NOx emissions without water injection or selective catalytic reduction (SCR). The entirely new turbine design developed by TurboEnergy Systems permits boiler repowering and other cogeneration applications. The first application will be in the California heavy oilfields; the system will be retrofitted to an existing 50 million btu/hr oilfield steam generator used in thermally enhanced oil recovery. The turbine, rated at 1250 kw (site output), was sized to match the combustion air flow requirements of the steam generator. A reheated design was selected to maximize power output from the limited airflow available and to maximize the exhaust temperature for cogeneration and industrial process applications. The oilfield cogeneration system being developed includes a new heavy oil burner for the steam generator which will be fired on the high temperature exhaust from the turbine. The system will also provide low NOx emissions, below the tightest projected standards in Kern County, which has a large concentration of heavy oilfields. Both the turbine and the steam generator burner will burn heavy (API 13 gravity) crude oil. The paper describes the overall system, its interface with the existing process, the design techniques used, and presents performance projections. Field testing will begin at a site near Bakersfield, California, starting in early to mid-1987.


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