1,721,032 research outputs found
New lifing criterion for land-based gas turbines in flexible operation mode
No full textUnder the ongoing global energy transition, gas turbines are increasingly experiencing new modes of operation. In the recent years, primarily in Europe and similarly in various parts of the world, renewable energies are gaining momentum to support more environmentally friendly energy policies. Renewable Energy Sources (RES), such as wind and solar are intermittent by nature and a rise in their contribution is associated with grid instabilities. As a result, reliable energy sources such as fossil fuel-based plants are required to fill flexible back-up or reserve power, capable to rapidly response in case of RES downtime. This introduces new operating conditions, characterized by very high start/stop cycles (almost daily) and load cycling operations, beyond those foreseen under the classic base-load or cyclic operations.The present criteria used for establishing the inspection intervals and components' lives, are put in place based on the assumptions that the gas turbine will operate at base load for the most part, with some exposure to cyclic operations. This paper identifies the most critical gaps in the present criteria, particularly due to increased thermal instability or sustained transient under the flexible operation requirements. (C) 2022 The Authors. Published by Elsevier Ltd
Novel Gas Turbine Challenges to Support the Clean Energy Transition
No full textThe ongoing energy transformation, which is fueled by environmentally cautious policies, demands a full synergy with existing back-up gas turbines (GTs). Renewable energy sources (RESs), such as wind and solar, are intermittent by nature and present large variations across the span of the day, seasons, and geographies. The gas turbine is seen as an essential part of the energy transition because of its superior operational flexibility over other non-renewable counterparts, such as hydro and nuclear. Besides the technical aspects, the latter are less popular due to controversies associated with safety, ecological, and social aspects. GTs can produce when required and with acceptable reaction times and load ranges. This allows a balance between the energy supply and demand in the grid, mitigating the variations in RESs. The increased cycling due to operational flexibility has adverse effects on GT components and the unit efficiency. The latter dictates how well GTs make use of the burned fuel and influence the emissions per energy unit. This paper investigates these aspects. First, it presents the effects of increased penetration of renewable energy sources (RESs) into the grid. Second, it defines the new operation requirements including more dynamic load regimes, the provision for high occurrences of starts and stops, continuous and variant load cycling operations, extended partial loading or stand-by, and other conditions not foreseen under the classic baseload or cyclic operations. Finally, it proposes the overhauling of the present GT inspection and lifing criteria to meet the new role of GTs
The development of a Novel Hybrid Gas Turbine digital twin to predict performance deterioration
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Analysis of diabatic compressed air energy storage systems with artificial reservoir using the levelized cost of storage method
No full textA detailed analysis has been carried out to assess the thermodynamic and economic performance of Diabatic Compressed Air Energy Storage (D-CAES) systems equipped with above-ground artificial storage. D-CAES plant arrangements based on both Steam Turbine (ST) and Gas Turbine (GT) technologies are taken into consideration. The influence of key design quantities (ie, storage pressure, turbine inlet pressure, turbine inlet temperature) on efficiency, capital and operating costs is analysed in detail and widely discussed. Finally, D-CAES design solutions are compared with Battery Energy Storage (BES) systems on the basis of the Levelized Cost of Storage (LCOS) method. Results show that the adoption of D-CAES can lead to better economic performance with respect to mature and emerging BES technologies. D-CAES ST based solutions can achieve a LCOS of 28 €cent/kWh, really close to that evaluated for the better performing BES system. Interesting LCOS values of 20 €cent/kWh have been attained by adopting D-CAES plant solutions based on GT technology
Full-admission radial turbine for waste heat recovery organic Rankine cycles
No full textOrganic Rankine Cycle (ORC) plants are interesting systems for power production by Waste Heat Recovery (WHR), although their application, especially for small/medium plants, could be not economically convenient. This is due to the inherent low thermodynamic cycle efficiency connected to the temperature of the heat source. Therefore, to avoid further penalizations, plant components (especially the turbine) should reach high performance both at nominal and off-design conditions. The paper deals with the design (from a 1-D to a fully 3-D level) of a full-admission radial-inflow turbine for a WHR ORC plant with a power output less than 50 kW. A parametric study was carried out to improve the turbine performance varying the most relevant geometric parameters, and the most promising geometry was analyzed in off-design conditions
Two-stage radial turbine for a small waste heat recovery Organic Rankine Cycle (ORC) plant
No full textLooking at the waste heat potential made available by industry, it can be noted that there are many sectors where small scale (< 100 kWe) organic Rankine cycle (ORC) plants could be applied to improve the energy efficiency. Such plants are quite challenging from the techno-economic point of view: The temperature of the primary heat source poses a low cutoff to the system thermodynamic efficiency. Therefore, high-performance components are needed, but, at the same time, they have to be at low cost as possible to assure a reasonable payback time. In this paper, the design of a twostage radial in-flow turbine for small ORC industrial plants is presented. Compared to commonly applied mono-stage expanders (both volumetric and dynamic), this novel turbine enables plants to exploit higher pressure ratios than conventional plants. Thus, the theoretical limit to the cycle efficiency is enhanced with undoubted benefits on the overall ORC plant performance. The design process involved 1D/2D models as well as 3D Computational Fluid Dynamic ones. After the design of the preliminary configuration, sensitivity analyses were carried out varying the most relevant geometric parameters for design performance improvement. Thereafter, the stages were both analyzed in off-design conditions giving their performance maps. Moreover, a stage stacking procedure was applied to obtain the overall turbine behavior
On the possibility of using an industrial steam turbine as an air expander in a Compressed Air Energy Storage plant
No full textSmall/medium size CAES systems (1–10 MW) could be efficiently and successfully employed for off-grid and self-consumption applications and for the delivery of ancillary services on the lower grid levels. A critical issue affecting the feasibility of such systems is related to the availability of efficient and affordable air expanders. Taking into consideration that typical CAES applications are characterized by inlet pressure levels in the range of 40–60 bar, an attractive opportunity to reduce development efforts and investment costs is to resort to the consolidated steam turbine engineering practice. In the present paper, the possibility of using existing building blocks developed to assemble industrial steam turbines to arrange air expanders for CAES applications is explored. A general model for off-design calculation capable of simulating, for a given turbine geometry, steam and air operations as well, has been developed and applied to a case study. On the basis of available information about an existing industrial steam turbine, a possible arrangement for an air expander has been set up and investigated. Results have evidenced a performance loss in terms of both power output and efficiency with respect to steam operations. Nevertheless, the air expander behavior in a wide range of operation can be considered satisfactory. Therefore, the use of industrial steam turbines technology might be considered interesting for the applications under consideration
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