SYNGAS CAPABLE COMBUSTION SYSTEMS DEVELOPMENT FOR ADVANCED GAS TURBINES
In the age of volatile and ever increasing natural gas fuel prices, strict new emission regulations and technological advancements, modern IGCC plants are the answer to growing market demands for efficient and environmentally friendly power generation. IGCC technology allows the use of low cost opportunity fuels, such as coal, of which there is a more than a 200-year supply in the U.S., and refinery residues, such as petroleum coke and residual oil. Future IGCC plants are expected to be more efficient and have a potential to be a lower cost solution to future CO2 and mercury regulations compared to the direct coal fired steam plants. Siemens has more than 300,000 hours of successful IGCC plant operational experience on a variety of heavy duty gas turbine models in Europe and the U.S. The gas turbines involved range from SGT5-2000E to SGT63000E (former designations are shown on Table 1). Future IGCC applications will extend this experience to the SGT5-4000F and SGT6-4000F/5000F/6000G gas turbines. In the currently operating Siemens’ 60 Hz fleet, the SGT6-5000F gas turbine has the most operating engines and the most cumulative operating hours. Over the years, advancements have increased its performance and decreased its emissions and life cycle costs without impacting reliability. Development has been initiated to verify its readiness for future IGCC application including syngas combustion system testing. Similar efforts are planned for the SGT6-6000G and SGT5-4000F/SGT6-4000F models. This paper discusses the extensive development programs that have been carried out to demonstrate that target emissions and engine operability can be achieved on syngas operation in advanced F-class 50 Hz and 60 Hz gas turbine based IGCC applications.
ADVANCED GAS TURBINE COMBUSTION SYSTEM DEVELOPMENT FOR HIGH HYDROGEN FUELS
Integrated Gasification Combined Cycle (IGCC) technology makes possible the utilization of low cost coal and opportunity fuels, such as petroleum coke, residual oil and biomass, for clean efficient and cost effective electricity generation. Siemens is a leading supplier of products and services for IGCC plants and it is adapting its most advanced gas turbines for successful integration into IGCC plants. To expedite this, Siemens is pursuing combustion system development for application in IGCC plants operating on syngas/hydrogen fuels. Detailed combustion system testing has been carried out during 2005 and 2006 on syngas/hydrogen fuels derived from different feed stocks and gasification processes. The test programs addressed both the Fand G-Class firing temperatures and operating conditions. Fuel transfer capability to and from natural gas, which is the startup and backup fuel, and syngas was explored over the operating range. Optimization studies were carried out with different diluent (H2O and N2) addition rates to determine the effect on emissions and operability. The focus of this development was to ensure that only combustion system modifications would be required for successful enriched hydrogen syngas fuel operation. This paper summarizes the results from the Siemens combustion system development programs to demonstrate that low emissions and wide engine operating range can be achieved on hydrogen fuel operation in advanced 50 Hz and 60 Hz gas turbines in IGCC applications with carbon dioxide capture.
Experimental study on bond behavior between high-strength grout and deformed steel bars
Abstract Engineers use high-strength grout to connect precast concrete members for its low shrinkage and good fluidity. This paper designed 87 central pull-out specimens using the control variable method to investigate the influence of factors on the rebar-grout bond property such as compressive strength, steel grade, bar diameter, transverse stirrups, and bond length. The test result showed that improving grout compressive strength (85.8 MPa–122.7 MPa) cannot improve the bond strength, which was different from the previous conclusions of concrete pull-out tests. Simplified formulas were presented for calculating the characteristic values of bond strength, residual strength, peak slip, and relative slip of load-holding platform based on parameter analysis. Then, a constitutive model was proposed to predict the full-range bond stress-slip curve of high-strength grout and steel bar specimens from bearing to failure. Finally, FEA models were established to evaluate the applicability and accuracy of the constitutive model.