Electo Eduardo Silva Lora

Design approach for a biomass fed fluidized bed gasifier using the simulation software CSFB.

In the paper a design approach for a biomass fluidized bed gasifier using the comprehensive simulator for fluidized bed equipment (CSFB) is proposed. Performance parameters such as air factor, feeding point position and bed height are determined looking for a maximum gasifier efficiency and gas heating value and a minimum tar content in the gas. Other parameters optimized by using the CSFB software are the pressure drop, the bubble diameter and the gas velocities in the bed.

Preliminary tests with a sugarcane bagasse fueled fluidized-bed air gasifier

This paper discusses the performance characteristics of a 280 kWth fluidized bed gasifier fueled with bagasse pellets. The gasifier was designed by the State University of Campinas (UNICAMP) and built by TERMOQUIP Energia Alternativa Ltda, based in Campinas, Brazil. Preliminary tests were performed in 1996 to determine the reactor performance as part of the gasification pilot plant test programme. A series of parameters, such as the lower heating value, heat losses, cold and hot gas thermal efficiency and gas yield, were measured as a function of the gasification air factor.

Performance evaluation and case studies of microturbines fuelled with natural gas and diesel

Abstract The high reliability and simple design of microturbines make them an attractive prime mover in the generation and distribution of electricity in the low capacity range. This paper gives an overview of microturbines in the Brazilian environment and provides a performance assessment and an economic analysis of these machines fuelled by natural gas and diesel and also an indication of their emission levels. This work was based on data that were obtained from experimental tests on microturbines operating at full and part load. The performance assessment indicated that it is possible to obtain up to 27 per cent microturbine efficiency at full load under local conditions. The nitrogen oxides (NOx) and carbon monoxide (CO) emissions level of the machines tested are less than 7 ppmv@15%O2 at full load when natural gas is the fuel. The units are therefore clean enough to be sited among residential and commercial establishments. The results of the economic analysis show that with the natural gas microturbine used in cogeneration, it is possible to achieve a payback time on capital equipment of less than 4 years. The return on the investment has improved with the favourable pricing policies of some of the natural gas distribution companies and with the rise in electricity prices in Brazil.

Gasification of Municipal Solid Waste for Power Generation in Brazil, a Review of Available Technologies and Their Environmental Benefits

This article reviews the literature on thermochemical processing of municipal solid waste as the final disposal in Brazil, explores recent publications in the field of solid waste generated, its origin, characteristics and removal mechanisms currently employed, in the same way , available technologies for the thermochemical treatment of MSW with an emphasis on gasification and clean technology are evaluated, highlighting the current technical and reported in the literature in order to identify indicators of efficiency and flexibility of the technology. From the review it is concluded that gasification is a technically feasible option for the thermochemical conversion of municipal solid waste and subsequent power generation, besides being a technology that meets the applicable emission limits. Some of the main advantages of gasification of municipal solid waste are: (a) the sharp reduction in the waste mass (about 70-80%) and volume (approximately 80-90%); (b) the drastic reduction in land use, 1:3000; (c) destruction of organic pollutants and other halogenated hydrocarbons; (d) concentration and immobilisation of inorganic contaminants so that they can be used effectively and safely removed; (e) use recyclables, such as ferrous metals, ferrous ash and slag materials; (f) reducing emissions of greenhouse gases by anaerobic decomposition of organic waste and (g) power generation.

Case Studies of Distributed Generation Projects With Microturbines in Brazil

Microturbines have showed good perspectives for the distributed generation of the electricity in low capacity range, because they have high reliability and simple design (high potential for a cheap manufacture and in large scale). Besides, this technology must have a great application in systems of cogeneration of the public service (malls, hotel, hospital, etc.) and in the distributed generation of the electricity in the developing countries in order to get a reliable operation system, in a range of power compatible with the isolated communities. In Brazil, The Thermal Systems Study Group (NEST) of Federal University of Itajuba (UNIFEI) sponsored by The Energy Company of Minas Gerais (CEMIG), are developing a project of experimental valuation of the system with microturbines for electricity generation fueled with natural gas and diesel. The objective of this paper is to show an economic evaluation which presents the generation costs and the payback period with the Capstone 30 kW natural gas microturbines business in three cases: microturbines operating on base load in gas station, microturbines operating on peak shave in the industry and a microturbine cogeneration system operating in the residential segment. It was considered the cost of microturbines at this moment and the projection for the future, as well as the cost of electricity and natural gas in Brazil. An economical analysis was carried out for different variables involved and the results show the Capstone 30 kW natural gas microturbines business are feasible firstly in cogeneration cases which is possible to get until 3 years of payback period. Besides, the return on the investment have shown improvements with the incentive of the natural gas distributing companies and with the rises in the electricity price of Brazilian utilities.Copyright

A comparative study of biomass integrated gasification combined cycle power systems: Performance analysis

The Biomass Integrated Gasification Combined Cycle (BIGCC) power system is believed to potentially be a highly efficient way to utilize biomass to generate power. However, there is no comparative study of BIGCC systems that examines all the latest improvements for gasification agents, gas turbine combustion methods, and CO2 Capture and Storage options. This study examines the impact of recent advancements on BIGCC performance through exergy analysis using Aspen Plus. Results show that the exergy efficiency of these systems is ranged from 22.3% to 37.1%. Furthermore, exergy analysis indicates that the gas turbine with external combustion has relatively high exergy efficiency, and Selexol CO2 removal method has low exergy destruction. Moreover, the sensitivity analysis shows that the system exergy efficiency is more sensitive to the initial temperature and pressure ratio of the gas turbine, whereas has a relatively weak dependence on the initial temperature and initial pressure of the steam turbine.

Programming the Inverse Thermal Balance for a Bagasse-Fired Boiler, Including the Application of a Optimization Method in MATLAB

Thermal balance of steam boilers can be done by two ways, the direct or indirect method; the direct method is not accurate. The reason why it is not accurate is that some operating parameters of biomass boilers cannot be obtained by direct measurements, like the measurement of fuel flow. These facts make it difficult to apply the direct method in the heat balance and force to use indirect one to determine these parameters and the boiler efficiency; hence, the indirect method is generally used for heat balance. Indirect method provides more accurate values and additionally, quantifies each of the energy losses, allowing to determinate causes of low efficiency of the equipment. Large amount of data involved implies the use of more affective calculation means; being iterative, assumed values for fuel flow must be compared with a value calculated until both match. In this work, the indirect method has been programmed in MATLAB; and for the preliminary fuel flow evaluation an optimization method could be used to prevent having to assume a value. Calculation details and a MATLAB algorithm are also presented.

ANÁLISE DO CICLO DE VIDA DE VEÍCULOS CONVENCIONAL, ELÉTRICO E HÍBRIDO PLUG-IN PARA CONDIÇÕES BRASILEIRAS

Vehicle emissions and high energy consumption linked to the chain of automobile production and use have significant environmental impacts. Some measures can be implemented to minimize the damage caused by these activities. The efficient use of energy, as well as choices for products and services that release lower amounts of pollutants are practices that aim at reducing the environmental impacts. Given this reality, electric and hybrid vehicles has attracted the attention of manufacturers, governments and consumers, mainly due to problems related to air pollution caused by vehicle emissions, global warming and reducing the use of fossil fuels. This work has the objective to carry out a Life Cycle Assessment (LCA) for different scenarios of vehicle technology / fuel in Brazil, in order to find out the environmental impacts caused by each of these systems. The results show that scenarios using ethanol as part of the fuel, has the biggest potential impact to acidification. The Systems that use gas as fuel has the biggest potential impact to global warming. Finally, electric and hybrid vehicles using lithium-ion battery have major impacts on human toxicity.

Steam Gasification of Miscanthus in a Double Stage Downdraft Gasifier

Gasification is the incomplete combustion of biomass, which produces syngas, biochar and tar. A study of steam gasification of Miscanthus was done on a double stage down draft gasifier at Federal University of Itajuba. The main objective of this paper is to analyze and characterize the syngas produced from the double stage downdraft system. Compared to the previous publication that focused on the gasification of corn using air, this paper elaborates on the steam gasification of Miscanthus.In a double stage downdraft gasifier, Miscanthus with 12% moisture was inserted into the system from the top. The gasifier has two inlets: primary and secondary. The steam was inserted through these inlets.The Miscanthus briquettes entering the gasifier were passed through a drying zone where the moisture content was removed. The fuel was then passed through a combustion and pyrolysis zone followed by a reduction zone. The syngas produced exited the gasifier through a grate and was analyzed for a continuous period of time.When using steam as a gasifying agent, it was found that the syngas showed a 15 % increase in hydrogen, a 50% decrease carbon monoxide with no change in methane composition. The increase in hydrogen can be used for alternate energy such as in fuel cells. The syngas heating value was obtained to be 4.64 MJ/Nm3.This paper compares the syngas composition evolved from the gasification of Miscanthus when using air and steam as gasifying agents.Copyright

REPOWERING: AN OPTION FOR REFURBISHMENT OF OLD THERMAL POWER PLANTS IN LATIN-AMERICAN COUNTRIES

The operational rules for the electricity markets in Latin America are changing at the same time that the electricity power plants are being subjected to stronger environmental restrictions, fierce competition and free market rules. This is forcing the conventional power plants owners to evaluate the operation of their power plants. Those thermal power plants were built between the 1960´s and the 1990´s. They are old and inefficient, therefore generating expensive electricity and polluting the environment. This study presents the repowering of thermal power plants based on the analysis of three basic concepts: the thermal configuration of the different technological solutions, the costs of the generated electricity and the environmental impact produced by the decrease of the pollutants generated during the electricity production. The case study for the present paper is an Ecuadorian 73 MWe power output steam power plant erected at the end of the 1970´s and has been operating continuously for over 30 years. Six repowering options are studied, focusing the increase of the installed capacity and thermal efficiency on the baseline case. Numerical simulations the seven thermal power plants are evaluated as follows: A. Modified Rankine cycle (73 MWe) with superheating and regeneration, one conventional boiler burning fuel oil and one old steam turbine. B. Fully-fired combined cycle (240 MWe) with two gas turbines burning natural gas, one recuperative boiler and one old steam turbine. C. Fully-fired combined cycle (235 MWe) with one gas turbine burning natural gas, one recuperative boiler and one old steam turbine. D. Fully-fired combined cycle (242 MWe) with one gas turbine burning natural gas, one recuperative boiler and one old steam turbine. The gas turbine has water injection in the combustion chamber. E. Fully-fired combined cycle (242 MWe) with one gas turbine burning natural gas, one recuperative boiler with supplementary burners and one old steam turbine. The gas turbine has steam injection in the combustion chamber. F. Hybrid combined cycle (235 MWe) with one gas turbine burning natural gas, one recuperative boiler with supplementary burners, one old steam boiler burning natural gas and one old steam turbine. G. Hybrid combined cycle (235 MWe) with one gas turbine burning diesel fuel, one recuperative boiler with