Design, manufacture and test of a micro-turbine renewable energy combustor

The ever-increasing demand on highly efficient decentralized power generation with low CO2 emission has made microturbines for power generation in micro gas turbine (MGT) systems popular when running on biofuels as a renewable source of energy. This document presents a state-of-the-art design, and optimization (in terms of design, performance and emission control) of a micro-turbine renewable energy combustor that fits into the existing Bladon 12kWe recuperated microturbine plenum while running on a range of biofuels as it can successfully provide the required power of the MGT. Governing equations for in-depth analysis of the combustor consist of manufacturer empirical data to simulate system-level operation with respect to replacement of the fossil with biofuels. The Model developed and validated at the company's ISO conditions confirms the output power of the new combustor fits the conventional system with slight eco-energy improvements. The modeling of the combustor in a complete microturbine assembly system is performed, then was utilized to further analysis of the microturbine with the designed combustor. The results gave on average 46.7% electrical efficiency, 83.2% system efficiency, 12 kWe electrical power, and 90% recuperator effectiveness at nominal operating conditions of microturbine (MT). Sensitivity analyses evaluate changes in performance with respect to fuel phase (e.g., liquid or gaseous) and design variables (e.g., orientation, shape, and dimensions of combustor), leading to energy optimization of the unit. Findings demonstrate that the combustor in microturbine can meet the target performance specifications of a company conventional diesel microturbine with significant savings. An objective function including both combustor and recuperator technical energy data is defined for finding the best ratio of fuel and air and their flow rates to find the most effective operating points for the operation of MT. Annual time series simulations completed for Coventry, West Midlands, United Kingdom indicate a new combustor can reduce operational costs of diesel fuel combustor by 8%, 2%, 36%, and 25% when supplying bioethanol, DME, biogas, and NG, respectively. Annual operating time of the renewable microturbine combustor at rated capacity included an 11% reduction in exergy loss with biogas fuel relative to diesel fuel.The Micro-Turbine Renewable Energy Combustor (MiTREC) project is funded by INNOVATE UK under grant number 103502, as part of the Energy Catalyst Programme-Round 4 for Mid-stage Technology Development to accelerate innovation in the energy sector

Design and numerical analysis of a 3 kWe flameless microturbine combustor for hydrogen fuel

In this work, a new 3 kWe flameless combustor for hydrogen fuel is designed and analyzed using CFD simulation. The strategy of the design is to provide a large volumetric combustion for hydrogen fuel without significant rise of the temperature. The combustor initial dimensions and specification were obtained from practical design procedures, and then optimized using CFD simulations. A three-dimensional model for the designed combustor is constructed to further analysis of flameless hydrogen combustion and consideration that leads to disappearance of flame-front and flameless combustion. The key design parameters including aerodynamic, temperature at walls and flame, NOX, pressure drop, combustion efficiency for the hydrogen flame is analyzed in the designed combustor. To well demonstrate the combustor, the NOX and entropy destruction and finally energy conversion efficiency, and overall operability in the microturbine cycle of hydrogen flameless combustor is compared with a 3 kWe design counterpart for natural gas. The findings demonstrate that hydrogen flameless combustion is superior to derive the microturbines with significantly lower NOX, and improvements in energy efficiency, and cycle overall efficiency with low wall temperatures guaranteeing the long-term operation of combustor and microturbine parts

Retrofitting Practice of a 100kWth Coal/Biomass Air-firing Combustor to the Oxy-firing Mode: Experiences and the Experimental Results

Air-firing of the fossil fuels results to relatively low concentration of CO2 in flue gases which make the capture of CO2 difficult and expensive. Oxy-firing combustion is a novel method of using enriched oxygen for coal/biomass combustion with Recycled Flue Gases (RFG) to control the adiabatic flame temperature and to increase the CO2 concentration of the off-gases up to a 60-70% oxy-firing mode (compared to air-fired mode, around 12-14%). This new technology is being applied at Cranfield University to retrofit an existing 100kWth air-firing combustor to the oxy-firing mode. This paper presents the procedure of the modifications applied on the combustor and the excellent results obtained for co-firing of pulverised coal and biomass in this rig

Modelling of wax deposition by perturbed hard sphere chain equation of state

Research data for this article: Data not available / The authors do not have permission to share data.Supplementary data are available online at: https://www.sciencedirect.com/science/article/pii/S0920410519310782?via%3Dihub#appsec2 .This article presents a model to predict the wax appearance temperature (WAT) and the quantity of wax deposition in eight different n-alkane mixtures using a correlative technique. The perturbed hard sphere chain equation of state (PHSC EoS) was employed in conjunction with the multi-solid model to describe the liquid-liquid and solid-liquid equilibria. The results are compared with experimental data. The results showed that PHSC EoS for some mixture of n-alkanes can perceptibly outperform the sole solid solution theory, improving the modelling of wax deposition quantities and wax appearance temperature by giving predictions closer to experimental values

The role of heat recirculation and flame stabilization in the formation of NOX in a thermo-photovoltaic micro-combustor step wall

The health and durability of micro thermophotovoltaic systems are contingent upon the level of gaseous emissions of micro combustors regarding their small size, thickness, and compactness. In small combustion devices, the flame stabilization is achieved via conjugated heat transfer from the stabilized flame to the fresh reactant via the step of the micro-combustors. The step could also create a recirculation of products, and a stagnation zone for the fluid, as a result leading to the accumulation of pollutants. In turbulent H2 flame, the main attention is given to the NOX as no other noxious emission, especially carbon emission (CO, CO2, PAH, and VOC), form during the combustion of hydrogen. The existence of NOX in the presence of water, as in the combustion of hydrogen is prevalent, could lead to corrosion in combustor interior walls and other detrimental impacts for the ecosystem. In the presented work, micro-combustion of H2 flame in a cylinder with a step is simulated and the formation of nitrogen oxides is analyzed. The influence of different combustor specifications (equivalence ratio, solid materials) NOX species are discussed and evaluated. Results revealed nitrogen oxides form and accumulate in the vertical step of the microchannel and that the microchannel walls are more prone to the high concentrations of nitrogen oxides. The application of cavity promotes the two-dimensionality of flow, resulting in effective heat transfer from the hot gas to the cavity walls. This not only leads to flame anchoring to the cavity walls but also results in significant NOX

OxyCAP UK: Oxyfuel Combustion - academic Programme for the UK

12th International Conference on Greenhouse Gas Control Technologies, GHGT-12, Austin TexasThe OxyCAP-UK (Oxyfuel Combustion - Academic Programme for the UK) programme was a £2 M collaboration involving researchers from seven UK universities, supported by E.On and the Engineering and Physical Sciences Research Council. The programme, which ran from November 2009 to July 2014, has successfully completed a broad range of activities related to development of oxyfuel power plants. This paper provides an overview of key findings arising from the programme. It covers development of UK research pilot test facilities for oxyfuel applications; 2-D and 3-D flame imaging systems for monitoring, analysis and diagnostics; fuel characterisation of biomass and coal for oxyfuel combustion applications; ash transformation/deposition in oxyfuel combustion systems; materials and corrosion in oxyfuel combustion systems; and development of advanced simulation based on CFD modelling

Analysis of flame stabilization to a thermo-photovoltaic micro-combustor step in turbulent premixed hydrogen flame

One of the effective strategies in meso and micro combustors for flame stabilization is to consider a wall cavity in a step. This extends the blow-off limit that can cause flame stagnation and anchoring. In the present work, the premixed hydrogen turbulent flame in a thermo-photovoltaic combustor with a step is simulated, validated and researched in terms of flame stabilization at different operating points including jet temperature, velocity, hydrogen, nitrogen, water content, and equivalence ratios. The effect of preferential transport of species is also evaluated and discussed. The results of simulations were employed to investigate the flame anchoring by showing the interplay between the flow field, heat recirculation, elementary reactions, transport of species. The results confirm that in this combustor the fresh reactant is gradually heated by the channel walls. This shifts the threshold of the combustion to the vicinity of the microchannel interior walls and more intense combustion downstream. The combustion in partially reacted materials is intensified by passing the duct interior walls when it faces the recirculating materials in the channel cavity leading to flame anchoring and stabilization from the cavity wall. The flame anchoring mechanism in this channel is the heat recirculation via channel walls, recirculating materials, and radical pool in the channel cavity for premixed hydrogen/oxygen flame. The effect of heat recirculation is found dominant in flame anchoring as in most case studies the flame stabilizes and evolves from the duct interior walls

Carbon Capture Technologies for Gas-Turbine-Based Power Plants

Carbon Capture Technologies for Gas-Turbine-Based Power Plants explores current progress in one of the most capable technologies for carbon capture in gas-turbine-based power plants. It identifies the primary benefits and shortcomings of oxy-fuel combustion CO2 capture technology compared to other capture technologies such as pre-combustion and post-combustion capture. This book examines over 20 different oxy-combustion turbine (oxyturbine) power cycles by providing their main operational parameters, thermodynamics and process modelling, energy and exergy analysis and performance evaluation. The conventional natural gas combined cycle (NGCC) power plant with post-combustion capture used as the base-case scenario. The design procedure and operational characteristics of a radial NOx-less oxy-fuel gas turbine combustor are presented with CFD simulation and performance analysis of the heat exchanger network and turbomachinery. Overview of oxygen production and air separation units (ASU) and CO2 compression and purification units (CPU) are also presented and discussed. The most advanced stages of development for the leading oxyturbine power cycles are assessed using techno-economic analysis, sensitivity, risk assessments and levelized cost of energy (LCOE) and analysing technology readiness level (TRL) and development stages. The book concludes with a road map for the development of future gas turbine-based power plants with full carbon capture capabilities using the experiences of the recently demonstrated cycles