Start-Up Process of 50kW-Class Gas Turbine Firing Ammonia Gas

Ammonia combustion gas turbines have drawn much attention for their potential to power hydrogen-carrier applications. In 2014, 21-kW of power generation was achieved with kerosene-ammonia co-combustion using a 50-kW-class micro gas turbine. In 2015, methane-ammonia co-combustion and 100% ammonia gas combustion were separately employed to generate 42-kW of power in both cases. However, this microgas turbine still requires kerosene to start. In gas turbines, the suitability of the air flow for ignition depends on the fuel. Low-NOx combustors were developed using the staged combustion concept to achieve rich-lean combustion. These combustors can burn kerosene at start-up but not at full load. We have also developed a micro gas turbine system that utilizes 100% ammonia gas in combustion during full-load operation. However, start-up with ammonia gas is difficult without hot air. The ignition of ammonia gas is so difficult that during the startup process, a more easily ignitable fuel is also used. In this study, we developed a new 50-kW-class micro gas turbine that can be started with gaseous fuel. Start-up with methane gas was achieved using a newly designed low-NOx combustor. In addition, because hydrogen can be easily obtained from ammonia decomposition, the addition of hydrogen gas to ammonia gas has garnered attention for ammonia gas turbine applications. The application of hydrogen to initiate combustion in a micro gas turbine was also investigated.

Biomass cogeneration plants integrated into poultry slaughterhouses for reducing industry costs with energy

A technical and economic feasibility analysis was performed concerning biomass cogeneration to supply the thermal and electricity demands of poultry slaughterhouses. The analysis considers measured data referring to the annual energy consumption from an existing industry as well as the characteristics of equipment available in the Brazilian market. The cogeneration plant is equipped with a water tube steam generator and a condensing-extraction steam turbine in a Rankine cycle. Four different configurations were evaluated, including impulse and reaction turbines at two steam pressure/temperature levels (43 bar / 450 °C and 68 bar / 520 °C). A steady state full load operation is considered at cogeneration mode on the weekdays and at Rankine power plant mode on the weekends, when there is no process steam consumption. The technical analysis pointed out the reaction turbine at 68 bar / 520 ºC as the best alternative, leading to the highest overall efficiency. In addition, this plant configuration showed economic advantages represented by an Internal Rate of Return (IRR) of 21%, a Net Present Value (NPV) of US$ 10.93 million, and a payback time of 6 years, enabling a reduction on the industrial cost with energy in the slaughterhouse to 19 US$/ton of product (-30% in comparison to the base case). Finally, the calculated LCOE of 73 US$/MWh was lower than the current price of the electricity in the market, indicating potential economic feasibility of the proposed concept.

Effectiveness Assessment of an Innovative Ejector Plant for Port Sediment Management

The need to remove deposited material from water basins is common and has been shared by many ports and channels since the earliest settlements along coasts and rivers. Dredging, the most widely used method to remove sediment deposits, is a reliable and wide-spread technology. Nevertheless, dredging is only able to restore the desired water depth but without any kind of impact on the causes of sedimentation and so it cannot guarantee navigability over time. Moreover, dredging operations have relevant environmental and economic issues. Therefore, there is a growing market demand for alternatives to sustainable technologies to dredging able to preserve navigability. This paper aims to evaluate the effectiveness of guaranteeing a minimum water depth over time at the port entrance at Marina of Cervia (Italy), wherein the first industrial scale ejector demo plant has been installed and operated from June 2019. The demo plant was designed to continuously remove the sediment that naturally settles in a certain area through the operation of the ejectors, which are submersible jet pumps. This paper focuses on a three-year analysis of bathymetries realized at the port inlet before and after ejector demo plant installation and correlates the bathymetric data with metocean data (waves and sea water level) collected in the same period. In particular, this paper analyses the relation between sea depth and sediment volume variation at the port inlet with ejector demo plant operation regimes. Results show that in the period from January to April 2020, which was also the period of full load operation of the demo plant, the water depth in the area of influence of the ejectors increased by 0.72 mm/day, while in the whole port inlet area a decrease of 0.95 mm/day was observed. Furthermore, in the same period of operation, the ejector demo plant’s impact on volume variation was estimated in a range of 245–750 m3.

A study on the high pressure EGR transport and application to the dispersion among cylinders in automotive engines

The objective of this study is to explore the limits of a one-dimensional model to predict the movement and mixing of the air and exhaust gases recirculation (EGR) flows in compact intake manifolds of recent automotive engines. In particular, the high pressure EGR loop configuration is evaluated in this study from the perspective of the EGR dispersion among cylinders. The experimental work includes the use of a fast CO2 tracking system that provides crank-angle resolved results in six locations of the intake manifold together with the acquisition of the time-averaged CO2 concentration in all the intake pipes (eight locations) to evaluate the EGR dispersion empirically. A specific system was developed to inject the EGR in three locations of the intake manifold in a flexible way to modify the dispersion. Up to 29 engine running conditions defined by engine speed, engine torque and EGR rate, spanning the entire engine map, including full load operation, were evaluated. A one-dimensional engine model was built to detect the limits in reproducing the EGR transport in the intake manifold and quantify the accuracy when predicting the dispersion among cylinders. The study concludes that the predicted EGR rate in the cylinders may differ up to 75% from the experimental measurement at low engine averaged EGR rate. The model prediction improves to differences lower than 40% in EGR rate per cylinder if the engine operating points with an EGR rate lower than 10% are excluded. In this situation, 80% of the predicted in-cylinder EGR rates have differences lower than 25% when compared to experiments.

Hydrodynamic analysis of a low head prototype Francis turbine for establishing an optimum operating regime using CFD

Hydraulic turbines need to operate at regimes other than designed ones. Off-design functioning of these turbines yields an inefficient and uneconomical operation of hydro projects. Performance and energy losses at different possible operating conditions need to be evaluated before finalizing the design of water turbines for satisfactory operations. Moreover, hydraulic turbines are unique machines designed for unique set of operating conditions and cost a huge percentage of the overall cost of the project. This work is compiled with twofold objectives; derivation of complete performance characteristics of a 48m head prototype Francis turbine in order to establish an optimum operating regime and, determination and analyses of head loss at different components of the turbine. Steady state flow simulations for four different load operations (60%, 80%, 100% and 120%) have been carried out using computational fluid dynamics. It is found that the optimum regime of operation lies within the speed factor range of 0.412-0.48 along with discharge factor range of 0.27-0.329 and maximum efficiency is obtained as 90.64% at full load operation. Maximum head loss in critical components of the turbine such as runner and draft tube is found as 12.7% at speed factor of 0.568 and 26.31% at 0.202 speed factor respectively. Also, the maximum total head loss in all the components is found as 47.8% at 60% load and 0.609 speed factor. It is concluded that the functioning of the turbine at higher speed factors is more detrimental than that at lower speed factors. Requirement of performance improvement at off-design conditions (especially at 60% load operation) is also suggested in order to widen the range of optimum operating regime. Obtained computational results are validated with experimental results and a strong agreement is found between the two.

Coordinated Control Using Backstepping of DFIG-Based Wind Turbine for Frequency Regulation in High Wind Energy Penetrated System

The expansion of renewable generation has raised some red flags in terms of power system stability, control, and management. For instance, unlike traditional synchronous energy sources, the doubly-fed induction generator- (DFIG-) based wind turbines (WTs) do not instinctively act against frequency deviations. In fact, the power electronics interfacing the generator, merely controlled to warrant maximum wind power conversion, make its output power and mechanical speed immune to the characteristics of the electric network frequency. Moreover, significant wind power penetration (WPP) promotes the retirement of many traditional generation groups, consequently curtailing the power system corresponding inertia and displacing the primary reserves that are essential to retain the frequency within an acceptable range of variation. This paper explores different control approaches, using backstepping, allowing DFIG-based WTs to engage actively in frequency regulation using a coordinated control of the rotor speed and pitch angle to regulate the system during both partial- and full-load operation modes. The first method momentarily discharges part of the kinetic energy stored in the WT spinning masses, and the second method follows a deloaded operation characteristic, so as to keep a specific power reserve that can be automatically activated at the events of frequency excursions. A study case considering an isolated power system that consists of synchronous generators, DFIG-based wind farm, static load, and a sudden frequency disturbance was performed. The simulation result in a Matlab/Simulink environment highlights the robustness and capability of the coordinated control scheme to furnish, under variant operation conditions, active power aid, consequently lifting the frequency nadir up to a superior level than that obtained with 0% wind power penetration in the system.

Reduction of Cold-Start Emissions for a Micro Combined Heat and Power Plant

Decentralized power generation by combined heat and power plants becomes increasingly popular as a measure to advance the energy transition. In this context, a substantial advantage of small combined heat and power plants is based on the relatively low pollutant emissions. However, a large proportion of the pollutant emissions is produced during a cold-start. This fact is not reflected in governmental and institutional emission guidelines, as these strongly focus on the emission levels under steady-state conditions. This study analyzes the spark advance, the reference air/fuel ratio and an electrically heated catalyst in terms of their potential to reduce the cold-start emissions of a micro combined heat and power plant which uses a natural gas fueled reciprocating internal combustion engine as prime mover and a three-way catalytic converter as aftertreatment system. Based on these measures, control approaches were developed that account for the specific operating conditions of the class of small combined heat and power plants, e.g., full-load operation and flexible, demand-driven runtimes. The experimental data demonstrates that even solutions with marginal adaptation/integration effort can reduce cold-start emissions to a great extent.

Experimental Investigation on Jatropha-Methanol Blends in Direct Injection Diesel Engines

This paper describes about the usage of Jatropha fuel in direct injection water-cooled diesel engine. In order to make use of Jatropha fuel in diesel engine, the properties of Jatropha oil has to be converted to diesel fuel, so for that methanol was added. There are three different blends are prepared by varying the ratio of Jatropha and methanol mixture, such as blend 1 (Jatropha 75%, methanol 25%), blend 2 (Jatropha 80%, methanol 20%), blend 3 (Jatropha 85%, methanol 15%). The prepared fuels are supplied to the conventional diesel engine, then the performance and emission characteristics were analysed. It is found that Jatropha methanol mixtures results are acceptable in half load and highly considerable in full load operation. Considerably torque developed is very low in low load than half and full load operations. Methanol addition has improved the performance and emission characteristics.