Wave-Powered Desalination

Climate change, drought, population growth and increased energy and water costs are all forces driving exploration into alternative, sustainable resources. The abundance of untapped wave energy often presents an opportunity for research into exploiting this resource to meet the energy and water needs of populated coastal regions. This paper investigates the potential and impact of harnessing wave energy for the purpose of seawater desalination. First the SWAN wave modeling software was used to evaluate the size and character of the wave resource. These data are used to estimate the cost of water for wave-powered desalination taking a specific region as a case example. The results indicate that, although the cost of water from this technology is not economically competitive at this time, the large available resource confirms the viability of significantly supplementing current freshwater supplies. The results also confirm that research into the feasibility of wave power as a source of energy and water in the area is warranted, particularly as water and energy become more scarce and expensive coinciding with the maturity of commercial wave energy conversion.

Component Test Facility (ComTest) Phase 1 Engineering for 760C (1400F) Advanced Ultra-Supercritical (A-USC) Steam Generator Development

Babcock & Wilcox Power Generation Group, Inc. (B&W) has received a competitively bid award from the United States (U.S.) Department of Energy to perform the preliminary front-end engineering design of an advanced ultra-supercritical (A-USC) steam superheater for a future A-USC component test program (ComTest) achieving 760C (1400F) steam temperature. The current award will provide the engineering data necessary for proceeding to detail engineering, manufacturing, construction and operation of a ComTest. The steam generator superheater would subsequently supply the steam to an A-USC intermediate pressure steam turbine. For this study the ComTest facility site is being considered at the Youngstown Thermal heating plant facility in Youngstown, Ohio. The ComTest program is important because it would place functioning A-USC components in operation and in coordinated boiler and turbine service. It is also important to introduce the power plant operation and maintenance personnel to the level of skills required and provide initial hands-on training experience. Preliminary fabrication, construction and commissioning plans are to be developed in the study. A follow-on project would eventually provide a means to exercise the complete supply chain events required to practice and refine the process for A-USC power plant design, supply, manufacture, construction, commissioning, operation and maintenance. Representative participants would then be able to transfer knowledge and recommendations to the industry. ComTest is conceived as firing natural gas in a separate standalone facility that will not jeopardize the host facility or suffer from conflicting requirements in the host plant’s mission that could sacrifice the nickel alloy components and not achieve the testing goals. ComTest will utilize smaller quantities of the expensive materials and reduce the risk in the first operational practice for A-USC technology in the U.S. Components at suitable scale in ComTest provide more assurance before applying them to a full size A-USC demonstration plant. The description of the pre-front-end engineering design study and current results will be presented.

Impact of Oxygen Enriched Air on High Intensity Combustion and Emission

The influence of oxygen enriched air-methane flame under non-premixed and premixed fuel-lean combustion conditions is examined with focus on the emission of NO and CO, combustor exit temperature (Texit), and distribution of OH* chemiluminescence intensity. A cylindrical combustor was used at combustion intensity of 36MW/m3.atm and heat load of 6.25 kW. Results are also reported with normal air (21% oxygen). Oxygen enrichment provided stable combustion operation at lower equivalence ratios than normal air and also reduced CO emission. Increase in oxygen concentration from 21% to 25% and 30% increased the NO and decreased CO emissions at all equivalence ratios examined. Using 30% O2 enriched air in premixed case showed NO emissions of 11.4 ppm and 4.6 ppm at equivalence ratios of 0.5 and 0.4, respectively. Oxygen enrichment also reduced CO emission to 38 ppm at equivalence ratio of 0.5. Operating the combustor with normal air at these equivalence ratios resulted in unstable combustion. OH* Chemiluminescence revealed increased chemiluminescence intensity with the reaction zone to shift upstream at increased oxygen concentration. The exhaust temperature of the combustor increased with oxygen enrichment leading to lower CO concentration and increased combustion efficiency. The oxidizer injected at higher velocities mitigated the impact of reaction zone to move upstream that helped to reduce significantly both the NO and CO emission specifically under non-premixed combustion.

The Impact of Qualified Bolting Specialists on the Safe, Reliable Assembly and Operation of Bolted Flanged Connections

Why do we certify welders but require no evidence of training or competence from those performing the critical bolted flanged joint assembly of pressure vessels and piping throughout the same industries? To remedy this situation ASME has recently released the first comprehensive standard in ASME PCC-1-2013 Appendix A that establishes uniform criteria, not just for the quality of the bolted joints but for the workers who assemble them. To support this critical training and qualification standard, ASME Training & Development has created a unique blended learning program for pipe fitters and mechanics to become Qualified Bolting Specialists (QBS), per the requirements outlined in PCC-1-2013 Appendix A. The purpose of this technical presentation is to explain the opportunities presented by this new standard and how industry can benefit from a better-trained work force in this critical area of bolted joint assembly. The authors have been integrally involved in the development of both the PCC-1 guideline document, and the ASME qualification program, and can authoritatively answer industry’s questions.

Impact of Internal Entrainment on High Intensity Distributed Combustion

Colorless Distributed Combustion (also referred to as CDC) has been shown to provide ultra-low emissions and enhanced performance of high intensity gas turbine combustors. To achieve distributed combustion, the flowfield needs to be tailored for adequate mixing between reactants and hot reactive species from within the combustor to result in high temperature low oxygen concentration environment prior to ignition. Such reaction distribution results in uniform thermal field and also eliminates any hot spots for mitigating NOx emission. Though CDC have been extensively studied using a variety of geometries, heat release intensities, and fuels, the role of internally recirculated hot reactive gases needs to be further investigated and quantified. In this paper, the impact of internal entrainment of reactive gases on flame structure and behavior is investigated with focus on fostering distributed combustion and providing guidelines for designing future gas turbine combustors operating in distributed combustion mode. To simulate the recirculated gases from within the combustor, a mixture of nitrogen and carbon dioxide is introduced to the air stream prior to mixing with fuel and subsequent combustion. Increase in the amounts of nitrogen and carbon dioxide (simulating increased entrainment), led to volume distributed reaction over a larger volume in the combustor with enhanced and uniform distribution of the OH* chemiluminescence intensity. At the same time, the bluish flame stabilized by the swirler is replaced with a more uniform almost invisible bluish flame. The increased recirculation also reflected on the pollutants emission, where NO emissions were significantly decreased for the same amount of fuel burned. Lowering oxygen concentration from 21% to 15% (due to increased recirculation) resulted in 80∼90% reduction in NO with no impact on CO emission with sub PPM NO emission achieved at an equivalence ratio of 0.7. Flame stabilization at excess recirculation can be achieved using preheated nitrogen and carbon dioxide, achieving true distributed conditions with oxygen concentration below 13%.

Gainesville Regional Utilities Kelly Plant Asset Management With Cycling Operation

Gainesville Regional Utilities (GRU) is a fully vertically-integrated utility with electric power generation, transmission, and distribution system owned by the City of Gainesville, FL. We have two primary generating plant sites: Deerhaven with two conventional coal-fired steam units (DH1 and DH2) and John R. Kelly (JCC1) combined-cycle Unit 1. Kelly Station (the focus of this study) is located in southeast Gainesville near the downtown business district. It has one - 120 MW combined-cycle unit (JCC1) in 1 × 1 configuration, consisting of: one GE Frame 7E combustion turbine (dual fuel), one Applied Thermal Systems two pressure HRSG, one 50-year old Westinghouse steam turbine unit with cooling tower, fuel storage, pumping equipment, transmission, and distribution equipment. In 2013, GRU with a seasonal peak load of approximately 500 MWs was to start receiving the output of a new 100 MW bio-fuel plant under a purchase power agreement. It was apparent that the operation of the GRU units would drastically change. It was predicted by GRU that DH2 a 255 MW coal unit would move to a cycling duty unit and the Kelly combined-cycle unit would be relegated to “peaking” operation. To better understand and predict future operational impacts, GRU contracted with Intertek AIM (APTECH) to conduct a Cost of Cycling study. This paper is our presentation of the results of the study and the changes that were indicated by the cycling analysis to manage the GRU system at the lowest cost and to incorporate the new modes of cycling operation. The expected modes of operation based on the results of the study were reversed to use the lowest cost unit for frequent cycling of JCC1 and changed the previously base loaded coal unit DH2 into a seasonal unit with long seasonal shut downs. This paper further shows the actions implemented by GRU at Kelly station to improve the cycling response and reduce the damage impact of each cycle by managing the startup ramp rates of the limiting equipment. The plant had limited budget for capital improvements and focused principally on managing the cost by modifying the startup procedures using real time operating data. Our conclusion was that by following the report recommendations, a new “Start Model” produced repeatable and acceptable results that minimized possible damage to the unit while meeting the need to use the renewable energy and support the customer by providing power at the lowest cost. The paper will demonstrate the improvement areas, the actual changes, and the results of those changes to the cycling data and the savings due to reduced damage.

Catalytic Oxidation of Jet Fuel Surrogates in a Meso-Scale Combustor

Oxidation behavior of dodecane and two mixtures of dodecane and m-xylene (90/10 wt. % and 80/20 wt. %) over an Rh catalyst in a meso-scale heat recirculating combustor was examined to isolate the effect of aromatic content on performance. The fuel conversion, product speciation and reaction kinetics were calculated, and the global combustion behavior observed. The results showed that increasing the amount of m-xylene in the fuel increased the fuel conversion from 85% (pure dodecane) to 92% (90/10) and further to 98% (80/20). The presence of xylene also significantly increased CO2/H2O selectivity and de-creased CO/H2 selectivity. Global activation energy increased linearly with increase in xylene content, supporting that addition of aromatic species to fuel lowers the overall reactivity. The non-catalytic reaction was also simulated using Chemkin software to determine the effect of the Rh catalyst on the combustor performance. The results revealed that the catalyst promotes total oxidation over partial oxidation, and lowers the global activation energy by up to 70%.

Preliminary Analysis of Compressor System Designed for Cyclical Operation

Conventional methods of the compressor performance analysis do not allow effective design matching to the specific operating conditions of cyclical or unsteady operated machines. Under dynamic loading the actual compressor performance often departs from the best efficiency region reducing its cycle efficiency. This departure may be caused by a number of reasons such as non-controlled deceleration, speed or torque constraints, and rapid boundary conditions variation caused by the cycle operation. In order to analyze this influence of cycle dynamics on compressor performance a modified lumped-parameter compressor-system model was applied. The model included time-dependent boundary conditions, effects of flow compressibility, motor and compressor inertia, and was combined with compressor speed control. The study was performed within the system constrains, e.g. surge avoidance, maximum motor torque and impeller speed. Results of the developed analysis showed that in the presence of rapidly changing boundary conditions the average cycle efficiency is strongly affected by the design specific speed of the compressor.

Performance Investigation of a Small Horizontal Axis Wind Turbine Equipped With Flexible Blades

Wind turbine technology has improved dramatically over the past decade, to the extent where wind turbine diameters are expected to soon exceed 160m and top 10MW in rated power output. While the development of these larger turbines has become immensely sophisticated, relatively little effort is being put forth to improve performance of smaller wind turbines, typically used in applications otherwise unsuitable for large installations. In this paper we investigate both computationally and experimentally the feasibility of a morphing turbine rotor, wherein blades are constructed of a flexible material and permitted to bend passively in response to external loading. The results indicate that the flexible blades can act as a passive pitch control device, resulting in significant improvements in efficiency when compared to a traditional rigid-blade design.