Gasification of Biomass: The Consequences of Equilibrium

2003 ◽  
Author(s):  
S. A. Scott ◽  
A. T. Harris ◽  
J. S. Dennis ◽  
A. N. Hayhurst ◽  
J. F. Davidson
Keyword(s):  
Free Energy ◽  
Heat Balance ◽  
Alternative Fuels ◽  
Calorific Value ◽  
Process Variables ◽  
Heating Value ◽  
Thermodynamic Limits ◽  
The Impact ◽  
The Heat Balance ◽  
Insight Into

A model minimising Gibbs Free Energy is used to examine the thermodynamic limits of performance of a gasifier for biomass and other alternative fuels. The minimisation of free energy is highly flexible in that it allows a large number of species to be examined. Such an equilibrium model gives insight into the differences in the behaviour of coal and biomass in gasifiers. Biomass differs from coal in terms of heating value, ash, volatile and carbon contents and the amount of elemental oxygen. The model has been used to explore, entirely from a thermodynamic viewpoint: (i) the off-gas compositions, (ii) the impact of process variables on the heat balance and when gasification is complete, (iii) the effect of different gasification agents on process performance and (iv) optimisation of the calorific value of the hot and cold gas produced. Dried sewage sludge was used as a typical biomass fuel for these simulations. For biomass fuels with a low calorific value, it is shown that co-gasification with a support-fuel of higher calorific value, for example coal, is more practicable than gasification of the biomass alone.

Comparison Between Two-Shaft Simple and Single-Shaft Recuperated Brayton Cycles Using Different Types of Gaseous Fuels

2010 ◽  
Author(s):  
A. K. Malkogianni ◽  
A. Tourlidakis ◽  
A. L. Polyzakis
Keyword(s):  
Natural Gas ◽  
Gas Turbines ◽  
Alternative Fuels ◽  
High Efficiency ◽  
Heating Value ◽  
Gaseous Fuels ◽  
Oil And Natural Gas ◽  
Parametric Studies ◽  
The Impact ◽  
Lower Heating

Geopolitical issues give rise to problems in the smooth and continuous flow of oil and natural gas from the production countries to the consumers’ development countries. In addition, severe environmental issues such as greenhouse gas emissions, eventually guide the consumers to fuels more suitable to the present situation. Alternative fuels such as biogas and coal gas have recently become more attractive because of their benefits, especially for electricity generation. On the other hand, the use of relatively low heating value fuels has a significant effect to the performance parameters of gas turbines. In this paper, the impact of using four fuels with different heating value in the gas turbine performance is simulated. Based on the high efficiency and commercialization criteria, two types of engines are chosen to be simulated: two-shaft simple and single-shaft recuperated cycle gas turbines. The heating values of the four gases investigated, correspond to natural gas and to a series of three gases with gradually lower heating values than that of natural gas. The main conclusions drawn from this design point (DP) and off-design (OD) analysis is that, for a given TET, efficiency increases for both engines when gases with low heating value are used. On the contrary, when power output is kept constant, the use of gases with low heating value will result in a decrease of thermal efficiency. A number of parametric studies are carried out and the effect of operating parameters on performance is assessed. The analysis is performed with customized software, which has been developed for this purpose.

Research on the Influence of Kitchen Waste Separation on MSW Incineration

2015 ◽  
Vol 768 ◽  
pp. 264-272
Author(s):  
Xuan Ye Liang ◽  
Jun Tang ◽  
Jie Xu ◽  
Xue Feng Gu ◽  
Feng Chao Yin ◽  
...  
Keyword(s):  
Heat Balance ◽  
Air Pollutants ◽  
Calorific Value ◽  
Combustion Efficiency ◽  
Kitchen Waste ◽  
Handling Stress ◽  
Msw Incineration ◽  
Incineration Process ◽  
Waste Separation ◽  
The Impact

With the acceleration of urbanization and industrialization, the amount of MSW in China generated is growing fast, while the pollutants generated in the disposal process of MSW has gradually attracted people’s attention. This paper presents the generation and composition status of MSW in China, summarizing the problems during MSW incineration disposal, providing an assumption of kitchen waste separation and using heat balance calculation to analysis the impact of kitchen waste separation on MSW incineration. Results shows that after kitchen waste separated from MSW, the amount of MSW reduced obviously, moisture content dropped, calorific value improved, auxiliary fuel is not need to ensure the proper incineration process and combustion efficiency improved; meanwhile, the generation of greenhouse gases and air pollutants is reduced significantly. Overall, the separation of kitchen waste not only reduced the difficulty and handling stress of MSW incineration, but also improved the incineration efficiency, reduced the generation of pollutants during incineration process.

scholarly journals Torrefaction Treatment on Fuel Properties of Bambusa Vulgaris and Gigantochloa Scorthecinii

2019 ◽  
Vol 8 (2S4) ◽  
pp. 492-494
Keyword(s):  
Growth Rate ◽  
Reaction Time ◽  
Calorific Value ◽  
Fuel Properties ◽  
Fuel Quality ◽  
Heating Value ◽  
Bambusa Vulgaris ◽  
The Impact ◽  
Fast Growth Rate

There is a great potential for bamboo to be applied as a biofuel for the future due to its good fuel properties with low alkali index and fast growth rate. Torrefaction treatment can increase the fuel quality of biomass in terms of the calorific value, energy density and storability. The aim of this research was to explore the effect of torrefaction temperature and reaction time on the fuel properties of B. vulgaris and G. scorthecinii. The bamboos were treated at various torrefaction temperatures (200, 250 and 300˚C) and reaction time (15, 30, 45 mins). In overall, the highest higher heating value was obtained from bamboos torrefied at 300ºC for 45 mins. In general, the temperature used in torrefaction has a relatively stronger effect on the higher heating value while the impact of the residence time was considerably lesser.

scholarly journals The Interactive Impact of Building Diversity on the Thermal Balance and Micro-Climate Change under the Influence of Rapid Urbanization

2019 ◽  
Vol 11 (6) ◽  
pp. 1662 ◽  
Author(s):  
Mehdi Makvandi ◽  
Baofeng Li ◽  
Mohamed Elsadek ◽  
Zeinab Khodabakhshi ◽  
Mohsen Ahmadi
Keyword(s):  
Air Temperature ◽  
Heat Balance ◽  
Thermal Balance ◽  
Heat Island ◽  
Rapid Urbanization ◽  
Air Movement ◽  
Water Surfaces ◽  
Urban Heat ◽  
The Impact ◽  
The Heat Balance

Numerous cities face the serious problems of rapid urbanization and climate change, especially in recent years. Among all cities, Wuhan is one of the most affected by these changes, accompanied by the transformation of water surfaces into urban lands and the decline of natural ventilation. This study investigated the impact of surface urban heat island enlargement (SUHI) and block morphology changes in heat balance. Accordingly, the interactive impact of building diversity with major building forms (low-rise, mid-rise, and high-rise) on thermal balance and microclimate changes under the influence of urban land expansion at the residential block scale was studied. To investigate the heat balance changes by air temperature intensification and air movement reduction, a long-term and field observational analysis (1980–2018) coupled with computational fluid dynamic simulation (CFD) was used to evaluate the impact of building diversity on thermal balance. Outcomes show that urban heat island intensity (UHII) increased by 2 ℃ when water surfaces in urban areas decreased; consequently, there was a deterioration in the air movement to alleviate UHII. Thus, the air movement declined substantially with UHII and SUHI enlargement, which, through increased urban surfaces and roughness length, will become worse by 2020. Furthermore, the decline in air movement caused by the transformation of urban water bodies cannot contribute to the heat balance unless reinforced by the morphology of the urban blocks. In the design of inner-city blocks, morphological indicators have a significant impact on microclimate and heat balance, where increasing building density and plot ratio will increase UHII, and increasing water surfaces will result in an increase in urban ventilation. Lastly, a substantial correlation between air temperature and relative humidity was found, which, together with the block indicators, can help control the air temperature and adjust the urban microclimate.

Analysis of the Impact of Boiler Slag’s Physical Sensible Heat Recovery on the Thermal Economy of Thermal Power Plant

2012 ◽  
Vol 608-609 ◽  
pp. 1298-1301
Author(s):  
Yong Li ◽  
Shi Ming Xu ◽  
Sheng Wen Huang ◽  
Wu Yi Du
Keyword(s):  
Power Plant ◽  
Heat Balance ◽  
Heat Recovery ◽  
Power Plants ◽  
Thermal Power ◽  
Sensible Heat ◽  
Whole Plant ◽  
Before And After ◽  
The Impact ◽  
The Heat Balance

Based on the situation that the transformations of the technology which is used to reclaim the physical sensible heat of the boiler slag in some industrial captive power plants, it has been used the heat balance method and the equivalent heat drop method to calculate and analyze the thermal economic indicators before and after the transformations of the unit, and then reveal the mechanism of the impact of the boiler slag’s physical sensible heat on the thermal economy of the whole plant.

Comparison and Evaluation of Performance, Emission and Wear Analysis of Diesel, JP-8 and Pure Karanja Biodiesel in a Military 780 hp CIDI Engine

2013 ◽  
Author(s):  
Anand Kumar Pandey ◽  
M. R. Nandgaonkar ◽  
P. Sivakumar ◽  
Anand Kumar Kammanni Veerabhadrappa ◽  
A. Kumarasamy
Keyword(s):  
Alternative Fuels ◽  
Specific Energy Consumption ◽  
Calorific Value ◽  
Diesel Emissions ◽  
Nox Emission ◽  
Biodiesel Fuel ◽  
Oxides Of Nitrogen ◽  
Brake Mean Effective Pressure ◽  
Karanja Oil ◽  
The Impact

Investigating the impact of JP-8 and pure Karanja oil biodiesel fuel on diesel engine performance, emission and pump wear are very important for military track and wheeled vehicles due to their great potential as alternative fuels. In the present study, a military 780 hp CIDI engine was fuelled and tested with diesel, JP-8 and pure Karanja oil biodiesel respectively. The performances of fuels were evaluated in terms of brake horse power, specific fuel consumption, brake specific energy consumption, brake mean effective pressure, thermal efficiency and heat release rates. The emission of carbon monoxide (CO), unburnt hydrocarbon (UHC), and oxides of nitrogen NOx with the three fuels were also compared. Both Karanja oil, after transesterification and JP-8 exhibit the properties (density, viscosity and calorific value) within acceptable limits of ASTM standard. Performance of both JP-8 and pure Karanja oil biodiesel were slightly lower than diesel. Emissions of CO and UHC were found lower with both JP-8 and Karanja oil biodiesel as compared to diesel fuel. However, only JP-8 fuel had lower NOx emission whereas Karanja oil biodiesel had 10% higher NOx emission. The fuel pump wear was tested after a 100 hours run.

scholarly journals The Use of Biodrying to Prevent Self-Heating of Alternative Fuel

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3039 ◽  
Author(s):  
Teresa Gajewska ◽  
Mateusz Malinowski ◽  
Maciej Szkoda
Keyword(s):  
Alternative Fuels ◽  
Fossil Fuels ◽  
Calorific Value ◽  
Alternative Fuel ◽  
The Self ◽  
Process Efficiency ◽  
Self Heating ◽  
Maximum Temperatures ◽  
Refuse Derived Fuels ◽  
The Impact

Alternative fuels (refuse-derived fuels—RDF) have been a substitute for fossil fuels in cement production for many years. RDF are produced from various materials characterized by high calorific value. Due to the possibility of self-ignition in the pile of stored alternative fuel, treatments are carried out to help protect entrepreneurs against material losses and employees against loss of health or life. The objective of the research was to assess the impact of alternative fuel biodrying on the ability to self-heat this material. Three variants of materials (alternative fuel produced on the basis of mixed municipal solid waste (MSW) and on the basis of bulky waste (mainly varnished wood and textiles) and residues from selective collection waste (mainly plastics and tires) were adopted for the analysis. The novelty of the proposed solution consists in processing the analyzed materials inside the innovative ecological waste apparatus bioreactor (EWA), which results in increased process efficiency and shortening its duration. The passive thermography technique was used to assess the impact of alternative fuel biodrying on the decrease in the self-heating ability of RDF. As a result of the conducted analyses, it was clear that the biodrying process inhibited the self-heating of alternative fuel. The temperature of the stored fuel reached over 60 °C before the biodrying process. However, after the biodrying process, the maximum temperatures in each of the variants were about 30 °C, which indicates a decrease in the activity of microorganisms and the lack of self-ignition risk. The maximum temperatures obtained (>71 °C), the time to reach them (≈4 h), and the duration of the thermophilic phase (≈65 h) are much shorter than in the studies of other authors, where the duration of the thermophilic phase was over 80 h.

An Analytical and Computational Investigation of Room Heating due to Complex Geometry Heat Sources

2015 ◽  
Author(s):  
Fabian Friedrich ◽  
Philipp Epple ◽  
Michael Steber ◽  
Antonio Delgado
Keyword(s):  
Heat Balance ◽  
Complex Geometry ◽  
Electrical Energy ◽  
Compressed Air ◽  
Heat Sources ◽  
Computational Investigation ◽  
New Production ◽  
Decisive Influence ◽  
The Impact ◽  
The Heat Balance

The compressed air generated by a compressor, is one of the most expensive known energy forms. The reason therefore is that electrical energy is converted directly into heat. The dissipation of the heat has a decisive influence on the performance of a compressor. Due to lack of standards during the planning phase of new production halls the heat balance, i.e. the supply and removal of the generated heat, very often the compressor is not considered proper. Even the German Engineering Association Directive VDMA 4363 “Lüftung der Betriebsräume luftgekühlter Kompressoren” (Ventilation of Industrial Premises Air-Cooled Compressors) [4] does not answer this question. In order to close this gap the impact of the volume of the room in order to keep the compressor running at a proper temperature is investigated. The influence of the orientation and size of the hot surfaces on the room heating is analyzed in detail as well.

scholarly journals Modelling Lake Titicaca's daily and monthly evaporation

2019 ◽  
Vol 23 (2) ◽  
pp. 657-668 ◽  
Author(s):  
Ramiro Pillco Zolá ◽  
Lars Bengtsson ◽  
Ronny Berndtsson ◽  
Belen Martí-Cardona ◽  
Frederic Satgé ◽  
...  
Keyword(s):  
Water Resource ◽  
Heat Balance ◽  
Resource Planning ◽  
Mountain Range ◽  
Lake Titicaca ◽  
Upper Limit ◽  
Lake Evaporation ◽  
Annual Evaporation ◽  
The Impact ◽  
The Heat Balance

Abstract. Lake Titicaca is a crucial water resource in the central part of the Andean mountain range, and it is one of the lakes most affected by climate warming. Since surface evaporation explains most of the lake's water losses, reliable estimates are paramount to the prediction of global warming impacts on Lake Titicaca and to the region's water resource planning and adaptation to climate change. Evaporation estimates were done in the past at monthly time steps and using the four methods as follows: water balance, heat balance, and the mass transfer and Penman's equations. The obtained annual evaporation values showed significant dispersion. This study used new, daily frequency hydro-meteorological measurements. Evaporation losses were calculated following the mentioned methods using both daily records and their monthly averages to assess the impact of higher temporal resolution data in the evaporation estimates. Changes in the lake heat storage needed for the heat balance method were estimated based on the morning water surface temperature, because convection during nights results in a well-mixed top layer every morning over a constant temperature depth. We found that the most reliable method for determining the annual lake evaporation was the heat balance approach, although the Penman equation allows for an easier implementation based on generally available meteorological parameters. The mean annual lake evaporation was found to be 1700 mm year−1. This value is considered an upper limit of the annual evaporation, since the main study period was abnormally warm. The obtained upper limit lowers by 200 mm year−1, the highest evaporation estimation obtained previously, thus reducing the uncertainty in the actual value. Regarding the evaporation estimates using daily and monthly averages, these resulted in minor differences for all methodologies.

How Is a Correct GT Combustor Heat Balance Established?

2020 ◽  
Author(s):  
Hans E. Wettstein
Keyword(s):  
Ambient Temperature ◽  
Specific Heat ◽  
Gas Turbine ◽  
Flow Rate ◽  
Heat Balance ◽  
Specific Enthalpy ◽  
Complete Combustion ◽  
Heating Value ◽  
Combustion Gas ◽  
The Heat Balance

Abstract The heat balance of gas turbine (GT) combustors is used for determining the average Combustor Exit Temperature (CET). It is important for designing the hot parts in this area. Sensor measurements of the CET are nearly impossible due to its high level up to above 1700°C. Therefore it is typically evaluated based on a 1-D cycle calculation, in which the combustor receives compressed air and fuel and it discharges the hot combustion gas at the temperature CET. In the classic approach the fuel heat received in the combustor is evaluated based on the lower heating value (LHV) of the fuel and after the complete combustion the mixture of excess air and combustion products leaves the combustor at the temperature CET, which is calculated based on its specific enthalpy function. So far so simple but this is tricky. The reaction energy is not the LHV but the higher heating value HHV, which includes additionally the discharged energy for condensing the combustion water at ambient temperature. The total heat comes into the flue-gas in the combustor, which is designed for a combustion efficiency of typically 99%+. There is no significant downstream reaction known, which could add the missing difference of HHV-LHV. In GT based power stations condensation is mostly avoided by sufficiently high stack temperature. For methane as a fuel the HHV is around 11% higher than the LHV. Thus the CET derived with the LHV for a given fuel mass flow rate may be underestimated. The method comparison shown below indicates values around 10K. This is a “grey” issue. The intention of this paper is an attempt to understand this practice both technically and historically. Gas turbine catalogues indicate performance data based on burning pure methane. This may have its historic roots in the fact that methane (only Methane, not higher hydrocarbons) burns with oxygen without a change of the specific volume. This simplified the cycle calculation in the sense that combustion could be modelled by adding the LHV to air and methane (assuming an equal temperature) and by calculating the expansion of air and methane separately (corresponding to mixed if no chemical reaction due to the high temperature is assumed) but with the same polytropic efficiency. At ambient temperature this fuel-air mixture is still gaseous and therefore the heat balance of the GT matches exactly with the LHV (used before in the combustor heat balance) because there is no condensation issue. Another feature of the air may compensate the CET mistake partly when using the LHV. It is the effect of dissociation. This increases the specific heat and therefore reduces the calculated CET. In the older time the used specific heat function of air did not include the dissociation effect while nowadays it is mostly included assuming chemical equilibrium. In this paper the good match of a cycle calculation considering the HHV and dissociation with published OEM data will be demonstrated. Indeed this method contradicts existing standards and practices and a further discussion considering the evidence shown below is welcome. In its current development state it allows considering any fuel defined only by the HHV and by its composition with hydrogen to carbon ratio by mass. Additionally it also allows considering high fogging with water injection rates up to several mass % of the air inlet flow rate.

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