scholarly journals Analysis of Exergy and Energy of Gasifier Systems for Coal-to-Fuel

2012 ◽  
pp. 246-252
Author(s):  
Nishant Sharma ◽  
Bhupendra Gupta ◽  
Ranjeet Pratap Singh Chauhan
Keyword(s):  
Exergy Analysis ◽  
Second Law Of Thermodynamics ◽  
Conservation Of Energy ◽  
Synthetic Natural Gas ◽  
Entrained Flow ◽  
Technology Improvement ◽  
Water Quench ◽  
Entrained Flow Gasifier ◽  
Quench Cooling

The purpose of this study is to investigate the performance features of coal-to-fuel systems based on different gasification technologies. The target products are the Fischer–Tropsch synthetic crude and synthetic natural gas. Two types of entrained-flow gasifierbased coal-to-fuel systems are simulated and their performance features are discussed. One is a single-stage water quench cooling entrained-flow gasifier, and another one is a two-stage syngas cooling entrained-flow gasifier. The conservation of energy (first law of thermodynamics) and the quality of energy (second law of thermodynamics) for the systems are both investigated. The results of exergy analysis provide insights about the potential targets for technology improvement. The features of different gasifier-based coal-to-fuel systems are discussed. The results provide information about the research and development priorities in future.

Energy and Exergy Analysis of Gasifier-Based Coal-to-Fuel Systems

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Yunhua Zhu ◽  
Sriram Somasundaram ◽  
James W. Kemp
Keyword(s):  
Exergy Analysis ◽  
High Efficiency ◽  
Second Law Of Thermodynamics ◽  
Conservation Of Energy ◽  
Transportation Fuels ◽  
Synthetic Natural Gas ◽  
Entrained Flow ◽  
Technology Improvement ◽  
Entrained Flow Gasifier ◽  
Construction Operation

National energy security concerns related to liquid transportation fuels have revived interests in alternative liquid fuel sources. Coal-to-fuel technologies feature high efficiency energy conversion and environmental advantages. While a number of factors are driving coal-to-fuel projects forward, there are several barriers to wide commercialization of these technologies such as financial, construction, operation, and technical risks. The purpose of this study is to investigate the performance features of coal-to-fuel systems based on different gasification technologies. The target products are the Fischer–Tropsch synthetic crude and synthetic natural gas. Two types of entrained-flow gasifier-based coal-to-fuel systems are simulated and their performance features are discussed. One is a single-stage water quench cooling entrained-flow gasifier, and another one is a two-stage syngas cooling entrained-flow gasifier. The conservation of energy (first law of thermodynamics) and the quality of energy (second law of thermodynamics) for the systems are both investigated. The results of exergy analysis provide insights about the potential targets for technology improvement. The features of different gasifier-based coal-to-fuel systems are discussed. The results provide information about the research and development priorities in future.

Energy and Exergy Analysis of Gasifier-Based Coal-to-Fuel Systems

2008 ◽  
Author(s):  
Yunhua Zhu ◽  
Sriram Somasundaram ◽  
James W. Kemp
Keyword(s):  
Exergy Analysis ◽  
High Efficiency ◽  
Second Law Of Thermodynamics ◽  
Conservation Of Energy ◽  
Transportation Fuels ◽  
Entrained Flow ◽  
Number Of Factors ◽  
Technology Improvement ◽  
Entrained Flow Gasifier ◽  
Construction Operation

Interests in coal-to-liquid (CTL) and other fuels have grown greatly in the last couple of years with steadily increasing oil prices. National energy security concerns related to liquid transportation fuels also have revived interests in alternative liquid fuel sources. Coal-to-fuel technologies feature high efficiency energy conversion and environmental advantages. While a number of factors are driving coal-to-fuel projects forward, there are several barriers to wide commercialization, such as financial, construction, operation, and technical risks. The purpose of this study is to investigate the performance features of CTL and other coal-to-fuel systems based on different gasification technologies. The target products are Fischer-Tropsch (F-T) crude and synthesis natural gas (SNG). Two types of entrained-flow gasifier based coal-to-fuel systems are simulated and their performance features are discussed. One is single-stage water quench (WQ) cooling entrained-flow gasifier, and another is two-stage syngas cooling (SC) entrained-flow gasifier. The conservation of energy (first law of thermodynamics) and the quality of energy (second law of thermodynamics) for the systems are both investigated. The results of exergy analysis provide insights about the potential targets for technology improvement. The features of different gasifier-based coal-to-fuel systems are discussed. The results provide information about the research and development priorities in future.

Review of Coal-to-Synthetic Natural Gas (SNG) Production Methods and Modeling of SNG Production in an Entrained-Flow Gasifer

2016 ◽  
Author(s):  
Xijia Lu ◽  
Ting Wang
Keyword(s):  
High Temperature ◽  
Computational Model ◽  
Catalytic Reaction ◽  
Reaction Rates ◽  
Sensitivity Study ◽  
Synthetic Natural Gas ◽  
Entrained Flow ◽  
Methanation Reaction ◽  
Gasification Process ◽  
Entrained Flow Gasifier

In this paper, the coal-to-synthetic natural gas (SNG) technologies have been reviewed. Steam-oxygen gasification, hydrogasification, and catalytic steam gasification are the three major gasification processes used in coal-to-SNG production. So far, only the steam-oxygen gasification process is commercially proven by installing a catalytic methanation reactor downstream of the gasification process after syngas is produced, cleaned, and shifted to achieve an appropriate H2/CO ratio for methanation reaction. This process is expensive, less efficient, and time consuming. Ideally, it will be more effective and economic if methanation could be completed in an once-through entrained-flow gasifier. Technically, this idea is challenging because an effective gasification process is typically operated in a high-pressure and high-temperature condition, which is not favorable for methanation reaction, which is exothermic. To investigate this idea, a computational model is established and a sensitivity study of methanation reactions with and without catalysts are conducted in this study. In modeling the methanation process in a gasifier, correct information of the reaction rates is extremely important. Most of known methanation reaction rates are tightly linked to the catalysts used. Since the non-catalytic reaction rates for methanation are not known in a gasifer and the issues are compounded by the fact that inherent minerals in coal ashes can also affect the methanation kinetics, modeling of methanation in an entrained-flow gasifier becomes very challenging. Considering these issues, instead of trying to obtain the correct methnation reaction rate, this study attempts to use computational model as a convenient tool to investigate the sensitivity of methane production under a wide range methanation reaction rates with and without catalysts. From this sensitivity study, it can be learned that the concept of implementing direct methanation in a once-through entrained-flow gasifier may not be attractive due to competitions of other reactions in a high-temperature environment. The production of SNG is limited to about 18% (vol) with catalytic reaction with a pre-exponential factor A in the order of 107. A further increase of the value of A to 1011 doesn’t result in more production of SNG. This SNG production limit could be caused by the high-temperature and short residence time (3–4 seconds) in the entraind-flow gasifier.

scholarly journals Heat, work and subtle fluids: a commentary on Joule (1850) ‘On the mechanical equivalent of heat’

2015 ◽  
Vol 373 (2039) ◽  
pp. 20140348 ◽  
Author(s):  
John Young
Keyword(s):  
Second Law Of Thermodynamics ◽  
Scientific Work ◽  
Conservation Of Energy ◽  
First Law Of Thermodynamics ◽  
Mechanical Equivalent ◽  
Scientific Establishment ◽  
Series Of Experiments ◽  
Scientists And Engineers ◽  
350Th Anniversary

James Joule played the major role in establishing the conservation of energy, or the first law of thermodynamics, as a universal, all-pervasive principle of physics. He was an experimentalist par excellence and his place in the development of thermodynamics is unarguable. This article discusses Joule's life and scientific work culminating in the 1850 paper, where he presented his detailed measurements of the mechanical equivalent of heat using his famous paddle-wheel apparatus. Joule's long series of experiments in the 1840s leading to his realisation that the conservation of energy was probably of universal validity is discussed in context with the work of other pioneers, notably Sadi Carnot, who effectively formulated the principle of the second law of thermodynamics a quarter of a century before the first law was accepted. The story of Joule's work is a story of an uphill struggle against a critical scientific establishment unwilling to accept the mounting evidence until it was impossible to ignore. His difficulties in attracting funding and publishing in reputable journals despite the quality of his work will resonate with many young scientists and engineers of the present day. This commentary was written to celebrate the 350th anniversary of the journal Philosophical Transactions of the Royal Society .

scholarly journals ANALISIS EKSERGI PENGERINGAN IRISAN TEMULAWAK

2016 ◽  
Vol 36 (01) ◽  
pp. 96
Author(s):  
Lamhot Parulian Manalu ◽  
Armansyah Halomoan Tambunan
Keyword(s):  
Exergy Analysis ◽  
Second Law Of Thermodynamics ◽  
Exergy Efficiency ◽  
Energy Utilization ◽  
Second Law ◽  
Process Conditions ◽  
Drying Process ◽  
Conservation Of Energy ◽  
Thin Layer Drying ◽  
Curcuma Xanthorrhiza

Java turmeric (Curcuma xanthorrhiza Roxb.) is a medicinal plant used as raw material for making herbal medicine, its rhizome cut into slices and dried so called simplicia. Curcuma has a harvest moisture content is high enough to need a great energy for drying. Generally, the theory used to analyze the energy efficiency is the first law of thermodynamics that describes the principle of conservation of energy. However, this theory has limitations in measuring the loss of energy quality. To determine whether the energy used in the drying process has been used optimally in terms of quality, the second law of thermodynamics -known as exergy analysis- is used. The purpose of this study is to determine the efficiency of the thin layer drying of curcuma slices with exergy analysis. The results show that the process conditions affect the energy utilization ratio and exergy efficiency of drying. Exergy analysis method based on the second law of thermodynamics has been used to determine the amount of exergy destroyed so that the efficiency of the drying process can be determined more accurately. Exergy efficiency varies between 96.5%-100% for temperatures of 50 °C to 70 °C at 40% RH and 82.3% - 100% for 20% to 40% RH at 50 °C.Keywords: Drying, energy, exergy efficiency, curcuma slices ABSTRAKTemulawak (Curcuma xanthorrhiza Roxb.) merupakan tanaman obat yang simplisianya digunakan sebagai bahan baku pembuatan jamu atau obat tradisional. Pengeringan merupakan proses utama dalam memproduksi simplisia. Untuk menganalisis efisiensi energi suatu proses pengeringan umumnya digunakan hukum termodinamika pertama yang menjelaskan tentang prinsip kekekalan energi. Akan tetapi teori ini mempunyai keterbatasan dalam mengukur penurunan kualitas energi. Untuk mengetahui apakah energi yang digunakan pada proses pengeringan sudah digunakan secara optimal dari sisi kualitas, digunakan hukum termodinamika kedua atau yang dikenal dengan analisis eksergi. Tujuan penelitian ini adalah menentukan efisiensi proses pengeringan lapisan tipis irisan temulawak dengan metode analisis energi dan eksergi. Dalam studi ini, metode analisis energi dan eksergi berdasarkan hukum termodinamika pertama dan kedua telah digunakan untuk menghitung rasio penggunaan energi dan besaran eksergi yang musnah (exergy loss). sehingga efisiensi proses pengeringan irisan temulawak dapat ditentukan secara akurat. Hasil penelitian menunjukkan bahwa kondisi proses pengeringan mempengaruhi rasio penggunaan energi dan efisiensi eksergi pengeringan. Semakin tinggi suhu dan RH pengeringan maka rasio penggunaan energi semakin rendah dan efisiensi eksergi semakin tinggi. Efisiensi eksergi pengeringan temulawak bervariasi antara 96,5%-100% untuk selang suhu 50 oC hingga 70 oC pada RH 40% serta 82,3% - 100% untuk selang RH 20% hingga 40% pada suhu 50 oC. Kata kunci: Pengeringan, energi, efisiensi eksergi, temulawak

scholarly journals Exergy Analysis of Energy Systems in Buildings

Buildings ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 180 ◽  
Author(s):  
Gianpiero Evola ◽  
Vincenzo Costanzo ◽  
Luigi Marletta
Keyword(s):  
Energy Conversion ◽  
Fossil Fuels ◽  
Exergy Analysis ◽  
Second Law Of Thermodynamics ◽  
Energy Conversion Efficiency ◽  
Lessons Learned ◽  
Energy Sources ◽  
Heating And Cooling ◽  
Energy Conversion Systems

The performance of space heating and cooling systems in buildings is usually measured by applying the first law of thermodynamics, which makes it possible to quantify the energy losses of the single components and to measure their energy conversion efficiency. However, this common approach does not properly consider that different forms of energy have different potentials to produce useful work, the latter being a function of the temperature at which energy is made available. As a result, it is not possible to properly address how the “quality” of energy is exploited or conserved in the different processes. On the contrary, the second law of thermodynamics is able to do that by introducing the concept of exergy: This is the maximum amount of work that can be produced through an ideal reversible process evolving until a full condition of equilibrium with the environment is attained. Exergy is; thus, a possible way to measure the “quality” of an energy flow or an energy source. This perspective is particularly relevant when dealing with buildings and their energy conversion systems, which usually deliver thermal energy at a temperature level that is close to the environmental temperature. This means that the users require “low-quality” energy; notwithstanding, this energy comes from the depletion of “high-quality” energy sources, such as fossil fuels and electricity. The exergy analysis helps with identifying such irrational use of the energy sources, which cannot come to light from the energy analysis. In this paper, a literature review identifies methods and metrics commonly used to carry out the exergy analysis of buildings and their energy technologies, while also underlining discrepancies and open methodological issues. Then, the review discusses the main lessons learned from selected works, providing significant advice about the rational use of energy in buildings as well as the most effective technological solutions.

Exergy Distribution Characters Analysis of a 130t/h Biomass-Fired Boiler

2015 ◽  
Vol 713-715 ◽  
pp. 1356-1359
Author(s):  
Fang Yang ◽  
Chang Qing Dong ◽  
Zhi Zhong Kang ◽  
Zong Ming Zheng ◽  
Xiao Ying Hu
Keyword(s):  
Heat Balance ◽  
Exergy Analysis ◽  
Second Law Of Thermodynamics ◽  
Energy Utilization ◽  
Analysis Model ◽  
The Real ◽  
First Law Of Thermodynamics ◽  
The Heat Balance ◽  
Exergy Losses

Currently, most of the boilers in power plant are designed by the heat balance based on first law of thermodynamics only, and it analyses the condition of using energy from the perspective of quantity of energy. However, The real energy utilization should be justified not only from the quantity but also from the quality, because the quality of energy based on second law of thermodynamics can reflect the irreversibility in processes and components. In order to revealing the real energy losses, we must establish exergy analysis model of 130t/h Biomass-Fired Boiler. This article calculates the exergy losses of all kinds of boiler surface and the overall exergy efficiency of boiler, together with exergy distribution characters analysis result of 130t/h Biomass-Fired Boiler. The results obtained open out the greatest exergy loss and the place to generate these losses of boiler, and provide scientific gist for improving utilization of boiler energy.

Thermodynamic Analysis of a Multi-Fueled Single Cylinder SI Engine

2011 ◽  
Author(s):  
M. Z. Haq ◽  
M. R. Mohiuddin
Keyword(s):  
Thermodynamic Analysis ◽  
Chemical Properties ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Si Engine ◽  
Gaseous Species ◽  
Single Cylinder ◽  
Engine Cylinder ◽  
Si Engines

The paper presents a thermodynamic analysis of a single cylinder four-stroke spark-ignition (SI) engine fuelled by four fuels namely iso-octane, methane, methanol and hydrogen. In SI engines, due to phenomena like ignition delay and finite flame speed manifested by the fuels, the heat addition process is not instantaneous, and hence ‘Weibe function’ is used to address the realistic heat release scenario of the engine. Empirical correlations are used to predict the heat loss from the engine cylinder. Physical states and chemical properties of gaseous species present inside the cylinder are determined using first and second law of thermodynamics, chemical kinetics, JANAF thermodynamic data-base and NASA polynomials. The model is implemented in FORTRAN 95 using standard numerical routines and some simulation results are validated against data available in literature. The second law of thermodynamics is applied to estimate the change of exergy i.e. the work potential or quality of the in-cylinder mixture undergoing various phases to complete the cycle. Results indicate that, around 4 to 24% of exergy initially possessed by the in-cylinder mixture is reduced during combustion and about 26 to 42% is left unused and exhausted to the atmosphere.

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