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Coal Combustion - Science topic

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Regarding the diagnostic ratios used for identifying sources of Polycyclic Aromatic Hydrocarbons (PAHs) and Volatile Organic Compounds (VOCs), such as those from traffic, coal combustion, or industrial activities, how should we approach the need for updates? Given that industrial processes, urban development, and technology evolve over time, do these ratios remain reliable for source apportionment? Should we periodically revise these diagnostic ratios to account for changes in emission profiles, new pollution sources, or advancements in analytical techniques? What methodologies would you recommend for validating or updating these ratios, considering both historical data and current environmental conditions?
Regards.
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These volatile organic compounds cause pollution through improper disposal, leakage of industrial effluents and infiltration into underground water. Of course, in some cases, VOCs may enter drinking water through chlorination process. These substances are formed in the reaction of chlorine with plastic pipes and are observed in the form of Tetrachloroethylene. And PAHs are considered as indicators of oil pollution. Due to the presence of oil wells in the sea these matters are considered as pollutants of soil and water ecosystem and are very toxic and deadly for aquatic life. So PAHs diagnostic ratios should be used with caution, as their values may change during the environmental fate of these compounds.
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What is the risk of air quality deterioration during the next heating season, which will be the result of the energy crisis and the fact that due to energy poverty, some citizens may throw various types of waste into combustion furnaces?
In the situation of a significant share of dirty combustion energy in the total energy sector, as well as in the situation of coal shortages and rising prices of various types of fossil fuels, unfair, unethical practices appear for sale of waste advertised as substitutes for fossil fuels. There are anti-environmental and anti-climatic, misleading citizens, sales offers on the Internet, the so-called "rubber eco-pea coal" made of ground tires, which is unfair practice of selling waste offered as substitutes for other combustion fuels. This type of unethical and extremely anti-environmental, anti-climatic practices result from many years of neglect of energy policy consisting in inhibiting the development of renewable and zero-emission energy sources, many years of supporting the development of dirty energy based on coal combustion and, consequently, not preparing the energy sector for the energy crisis, ignoring the progressing global warming process, leading to a low level of energy security, low air quality, and frequent smog in many cities in Poland. In economies where most of the electricity and heat is generated by burning fossil fuels, a shortage of these fuels creates a risk of increased fuel poverty and incineration of waste in furnaces. As a result, the level of air pollution in the next heating season (fall-winter 2022) may increase significantly. Burning plastic and rubber waste generates carcinogenic chemicals that are present in the air. Therefore, due to the current energy crisis, the air quality in the country in which I operate may drop significantly in the coming months.
In view of the above, I address the following research question to the Honorable Community of Researchers and Scientists:
To what extent can the energy crisis translate into increased pollution and deterioration of air quality?
What do you think about it?
What is your opinion on this topic?
Please reply,
I invite everyone to the discussion,
Thank you very much,
Best regards,
Dariusz Prokopowicz
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The energy crisis, especially with rising fuel costs and coal shortages, presents a major threat to air quality in the upcoming heating season. As you noted, energy poverty may lead people to engage in harmful and unethical practices, such as burning waste materials like rubber, plastic, and tires in place of traditional fuels. This releases toxic and carcinogenic substances into the air, worsening the already serious air pollution problem. This is particularly concerning in regions where fossil fuels are still the primary energy source, and renewable energy options are underdeveloped.
The core issue lies in the combination of economic struggles, poor energy policies, and environmental damage. The energy crisis magnifies existing weaknesses in the energy system, leading to harmful and unsafe practices. With a continued dependence on coal and other fossil fuels, the shortage of these resources amplifies the risks of energy insecurity and poses serious threats to public health. Governments must take immediate action to transition to renewable energy sources and implement policies that reduce dependence on polluting fuels. Without such measures, air quality will likely worsen, and public health risks will increase, along with more frequent smog and toxic air events. In my view, the energy crisis is not just an economic issue but an environmental one that requires a comprehensive approach, including both short-term solutions to reduce waste-burning practices and long-term strategies to adopt renewable energy. Public awareness, incentives for clean energy, and strong policies are essential to ensure energy security without compromising public health and environmental quality. It is vital for policymakers to consider both the immediate effects of energy shortages and the long-term sustainability of the energy infrastructure.
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In my research, I am focused on identifying traces of coal combustion residuals in lake sediments. We have analyzed 54 elements, and one of the key steps in assessing contamination is calculating the enrichment factor. However, I am uncertain about which element to use for normalization. Commonly recommended elements include Al, Fe, La, Li, Sc, Ti, and V. The results we obtained vary significantly, leading to conflicting conclusions. I suspect that Fe, V, and Li may be influenced by coal combustion and are redox-sensitive, so I am considering excluding them. Any suggestions on how to refine the approach and which element might be the most appropriate for normalization would be greatly appreciated. Thank you in advance for any guidance or insights!
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It should be favorable to persue two branches a geogenic one and an antropogenic one both of which should be ultrastable. It is rather simple in tehe geogenic part wher the ZTR index (Zr /zircon, T=B/ tourmaline R=Ti/ rutile). Artificial products have been originated from smelting and belong to the spinel group (Zn Cr, Fe), carbides (W carbide). Hereby you might get an idea of the two different pathways aeolian and fluvial (rarely mass wasting).
HGD
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PAHs can indicate coal combustion, but how can they more accurately indicate that it is coal combustion?
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Coals, depending on the grade of coal, will tend to give very high molecular weight PAHs, biomass lower molecular weights, but the analysis for these would not be online and would have to be done by sampling and GC-MS analysis - and you still won't be able to analyse for everything. Its the 3 T's - time, temperature and turbulence, and excess O2 to ensure burnout of the PAHs. Water in the gas is needed to avoid H2 deficiency in the combusted gases, which leads to soot formation.
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Hello everyone,
I'm currently working on a coal combustion project and exploring various combustion models available in ANSYS CFX, such as EDM and FRC. I've come across references to the importance of the Damköhler number in determining the appropriate model choice. However, I'm seeking guidance on how to calculate this number.
If anyone has expertise in this area or can provide insights into the calculation process, I would greatly appreciate your help. Thank you all in advance.
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To calculate the Damköhler number for coal combustion models in ANSYS CFX, you'll need to perform a few steps.
1. Define the Damköhler number: The Damköhler number represents the ratio of the chemical reaction timescale to the mixing timescale. It helps characterize the dominance of chemical reactions over mixing processes. It is defined as Da = τ_c/τ_m, where τ_c is the characteristic chemical reaction timescale and τ_m is the characteristic mixing timescale.
2. Determine the characteristic chemical reaction timescale (τ_c): In coal combustion models, this timescale can vary based on the specific reaction mechanism you're using. It is often related to the kinetics of the combustion process and can be estimated based on the chemical reaction rates.
3. Determine the characteristic mixing timescale (τ_m): This timescale is related to the flow and mixing properties of the system. It depends on the velocity and turbulence characteristics within the domain.
4. Calculate the Damköhler number (Da): Once you have the values for τ_c and τ_m, you can compute the Damköhler number by dividing τ_c by τ_m.
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Germany has taken two environmentally-friendly decisions to phase out nuclear and coal power by 2022 and 2030 respectively. The country also has shown the capability of expansion of renewable energy to replace the gap, and it is successful to date.
However, facing future energy demand within this framework could be a challenge. I would like to discuss this matter with energy experts.
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I have worked in the power industry for over 40 years and have been inside most of the nuclear plants they're closing in Germany. I've even been to the top of the tower in Uentrop before they tore it down. Sadly, many of these decisions are being driven by public sentiment rather than science and made by politicians rather than experienced engineers, who are seen as evil and stupid. I want what is best in the long run for the most people and the environment, which is complicated in a day when only simplistic feel-good answers are allowed.
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The issue of reducing greenhouse gas emissions is currently one of the most important problems for urgent solutions in connection with the accelerating process of global warming.
The fact that the development of human civilization is largely responsible for the emission of greenhouse gases is an irrefutable fact confirmed by numerous independent research centers.
However, in individual countries, the development of industry is at various stages of development.
In individual countries, sources of greenhouse gas emissions can be presented in a different source structure of these emissions.
In some countries, in large agglomerations, the main source of greenhouse gas emissions is transport based on traditional combustion of fossil fuels, combustion of low-quality mineral and non-mineral minerals in domestic furnaces, and energy based on mineral combustion.
Therefore, I am asking you the following questions:
And how is greenhouse gas emissions in your countries or cities?
What are the main sources of greenhouse gas emissions in your country, in the cities where you live?
If you live in cities, is smog a problem?
Is smog the problem in your cities mainly in the winter season or also in other seasons?
Is the greenhouse gas emissions structure in your country significantly different compared to global greenhouse gas emissions data?
Please, answer, comments. I invite you to the discussion.
Chart. Global Warming. CO2 emissions of greenhouse gases, a forecast of the increase in the average temperature on Earth. Source: NOAA, NASA.
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Globally, the primary sources of greenhouse gas emissions are electricity and heat (31%), agriculture (11%), transportation (15%), forestry (6%) and manufacturing (12%). Energy production of all types accounts for 72 percent of all emissions.
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Dear all,
I'm currently doing my thesis working on a coal combustion and pyrolysis simulation in DWSIM. I've been trying to find a way to create a coal stream with its parameters of proximate and ultimate analysis.
Does anyone know if it is possible in this simulator? (I know that this is possible on Aspen)
Thank you so much.
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Did you tested to fix an den json File with your chemical settings? Or did you only used Files you find?
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Hi everyone
I am doing biomass gasification simulation in fluidized bed reactor. What is the popular and helpful reference book in this area explaining fluidization, pyrolysis, gasification and reactions Kinetics?
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Biomass Gasification and Pyrolysis- Practical design and Theory by Prabir Basu - Elsevier ISBN 978-0-12-374988-8
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I am doing coal combustion simulation through blast furnace Tuyere and wish to see impact of Natural gas or coke oven gas injection on pulverized coal combustion. I have separate inlets for pulverized coal and gaseous fuel. As I am doing coal combustion I am having coal volatile-air mixture as default mixture. I am able to add methane-air mixture in material stream but cannot assign it as fluid to cell zones of gaseous fuel. I also tried to add CH4 and other gaseous components to coal volatile - air mixture and change first reaction with CH4 and O2 as separate reacting species is it right doing so?
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It is not very clear from your explanation that which models you are using to simulate the problem (Eulerian-lagrangian approach). Usually, these kinds are handed through DPM model (lagrangian particles in you case) in fluent. The mass, momentum and energy of the solid phase are added to eulthe erian phase (gas-phase) through a source in the conservation equation. There are some standard tutorials available on the web. However, you can contact me through msgs for further clarifiaction on the theroy.
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I am interested in studying the devolatilisation characteristics of coal in a bid to compute the kinetic constants of devolatilisation. Is it possible to do it with a simple TGA? Or is there a need to use a TGA coupled with FTIR or GC/MS
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I agree V R Arun Prakash
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Hello Everyone.
Can any please tell me the main principles and techniques of Ultra Low emission (SO2, NOX etc) monitoring in coal fired power plants?
Thank you for your valuable time.
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please be more clear, make a distinction (both can be measured and there are special techniques/procedures to apply):
emissions from the stack or
air quality in the limits of the plant
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Thermal power generation through coal combustion produces minute particle of ash(Fly Ash) that causes serious environment problems.
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In 2008 in Europe, 38,000 kt of fly ash was produced from the combustion of lignite and coal. They are composed mainly of SiO2 and Al2O3. There are many and diverse applications of fly ash. They are mainly used to produce cement in the construction sector, but they are also used to make bricks. In other sectors they are used for the formation of embankments and fillings in road construction.
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In South Africa, every December (since 5 December 2014) the residents are suffering from electricity cut by Eskom for at least two hours per day and that results to some negative impacts e.g. it disturbs businesses without back-up systems such as educational institutions, clinics and some community serving businesses . Apart from increasing coal supplies, what can be done whether scientifically to avoid this suffering of residents and businesses?
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Load shedding is strategically performed by the electric utilities as work around the peak demand periods. In India for example, daily periodic brownout, and possibly blackout, is done for the residential customers during the daily peak demand periods. Accordingly, residential customers can use backup rechargeable batteries or small diesel generators to produce power during the brownout periods of the day.
In general, renewable energy sources such as wind farms and solar PV farms are suitable backup means for energy generation when conventional electricity generation (burning coal, natural gas, or oil) faces peak load demands.
Hope this help answer your question and good luck!
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Hi,
How can I calculate the stoichiometric air to fuel ratio for coal combustion in a 2 step reaction.
Reaction 1 : C2.9H3.75O0.61N0.1081 + 2.40 O2 -> 2.24 CO +0.65 CO2 + 1.87 H2O + 0.054 N2
Reaction 2: CO + 0.5 O2 -> CO2
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You need to include N2 in air in Equations 1 and 2 . The molar ration of N2 to O2 in air is 79/21 or 3.76. For example, in E.q. (1), we need to add (2.4 x 3.76 moles of N2). Assume that N2 in air will not react (viz., an inert gas), then you will need to add 2.4 x 3.76 moles of N2 on the right-hand side of E.q. (1).
In Eq. (2), you'll need to add 0.5 x 3.76 moles of N2 on both sides of this equation.
One last comment: The elemental nitrogen in coal in Eq. (1) is typically combusted to NO2 and, hence, you could account for that if you like.
Hope this helps answer your question and good luck.
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I need advice to choose proper thermal boundary condition on the wall of furnace and burners of pulverized coal combustion boiler. I am not sure that t=constant is satisfied condition which is used in many cfd computations. Insted I think using heat transfer coefficient is better? I found in literature just a few works, but value of coefficient is very different from 150 to 10000 and more.
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If you are modeling only steam generation inside tubes then you can use heat flux boundary condition
If you are modeling only coal combustion inside furnace then you can use negative heat flux (energy taken by fluid e.g. water/steam)
and If you are modeling both then boundary condition will be coupled
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Hello, i was working on combustion modeling of coal in furnace. my question is related to DPM iteration report, would you please guide me. In the DPM iteration report num tracked =107250 , escaped = 102803, abroted =0 , traped =0 , evapoorated =0 , incomplete =4447 What is the physical meaning? Should be the total num of escaped similar to the total num of tracked?
Can we consider these num. as a satisfactory simmulation of the discrete phase? Is there any numbering criteria for each, escaped , abroted , traped , evapoorated and incomplete in modeling? Thank you in advance.
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I think so.
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I am using a DTF (drop tube furnace) for coal combustion experiments that has a long vertical quartz tube. there are many stains on it that i want to remove . Can anyone recommend me some solutions or procedures?I already tried ethanol but it didnt work.
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Thanks a lot for your valuable input. I will try with these acids. The problem is that the nature of the contaminants is unknown as this tube is only used in heating environment with air, no chemicals involved at all.
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Water under 250 Bar artificially applied pressure, even if heated to 340 Celsius, remains as water. So if I can bring hot oil, and remove cold oil economically with a Heatgate, through the pressure, and the water stays as water, can I use a .1mm copper interface?
2nd, question, if the artificial pressure is maintained at 400 Bar, what happens if we used hot salt to heat it up to 450 Celsius, over the critical point, can I still use the .1mm copper?
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I am pleased that you have got a Heatgate working - I still think the sliding valves will cause a lot of problem in practice, and for this application the pressure is 4 times what you have used. But there is another issue with this design, that it may be (I am not sure I understand what the researcher is trying to do) that the working fluid - water - is to have its pressure reduced to atmospheric in the Heatgate. I hope it is well understood what water at 320C will do if its pressure is suddenly reduced to atmospheric . . . I think that this work requires the attention and involvement of a qualified mechanical engineer used to working with extremely high pressure fluids and valves. Even reducing the pressure of water at 320C to atmospheric will require special valving and a heat removal system to perform safely. I do hope all the relevant safety precautions are being taken in this endeavour. Nevertheless, all pioneering work requires effort and some risk - so I hope it can all be made to work safely. At the moment I am very nervous about this process.
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Does fly ash obtained from coal combustion need to be treated to be used as an adsorbent for removal of lead from wastewater?
How effective is fly ash as an adsorbent?
Can anyone recommend websites to buy fly ash for experimental purposes?
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Please refer to the following attached file. Regards
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See above.
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Dr. Erkan Yersel,
Pulverized coal (PC) is also known as powdered coal or coal dust. PC combustion is being used in over 90% of coal-fired plants worldwide. In such firing system, the pulverised fuel is used in the whole volume of the furnace for the combustion of solid fuels. Coal is ground to the size of a fine grain, mixed with air and burned in the flue gas flow.  The ash produced is removed as bottom ash and fly ash. The bottom ash produced is removed at the furnace bottom.
There are three main types of thermal power plants, namely sub-critical, super-critical and ultra-supercritical with increasing thermodynamic efficiency. A supercritical steam cycle typically has pressure > 226 bars and temperature > 537°C .Ultra-super critical cycle typically operates at 357 bars/625°C. Pulverized coal provides the thermal energy which produces about 50% of the world's electric supply.
For a simple concept on designing a pulverized coal combustion system, you can see net. For technical details and other information, you can visit the website of CIMFR, Dhanbad, India (http://www.cimfr.nic.in/) - The best institute in India on coal & coal mining research.
Please see the links given below for more literature on coal combustion.
Regards 
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Biochar is obtained from slow pyrolysis at 450 and 550C at 10C per min heat rate. Assuming 66.1% C, 2.84% H, 6.57% N, 0.6% S, 23.89% O with GHV 24.45 MJ/kg and moisture 1.74%. What could be the enthalphy for this particular biochar?
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Hi Raj,
If you have access to a software HYSYS or AspenPlus, you can simply enter the chemical composition that you specified and the simulation software to calculate the enthalpy of the biochar. You can download at a no cost a trial version of HYSYS or AspenPlus from Aspen technologies at:
Best,
Prof. Khalil
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I have been trying to produce biodiesel by heterogeneous catalysts viz. Li doped CaO, mixed CaO/Al2O3 and limestone based cement clinker. Having prepared these catalysts severally, there have not been conversions. What could have been wrong?
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Li doped CaO or CaO/Al2O3 catalysts are all active basic catalysts for biodiesel production. However, two important aspects need to be clarified before applying a heterogeneous catalyst for biodiesel synthesis. The feedstock used (palm oil, waste cooking oil or jatropha oil) must be analysed for acid value content determination. If the acid value is <3%, your basic catalysts could work. If the free fatty acid value is >3%, the catalyst must possess some acid sites that can help for esterifying the FFA (>3%) content in the feedstock (waste cooking oil, jatropha oil). Otherwise two step reaction processess are necessary before you achieve any conversion. The first reaction process is to reduce the excess FFA to <1% and then subject the feedstock to transesterification reaction. The second aspect to be considered is the reaction conditions (Temperature, methanol to oil ratio, catalyst loading and time). Before the conversion of any feedstock to biodiesel, the reaction conditions must be applied in an appropriate manner. If the aforementioned information doesn't work, review the catalyst preparation method you used. I hope this information will help you.
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Hello everybody.
Someone knows free software to design zeolite structures.
Preferably free software. But it can indicate other software.
For any operating system.
Regards
Fábio
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Dear Nitin Goyal 
Thanks for help
Fabio
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Facing CO emission problem.
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The process is carried out inside a tubular rotary kiln, which has a burner of concentric tubes that allows the combustion of fuels in different phases, in this case, natural gas. The modeling accounts for phenomena such as the turbulence produced due the high Reynolds number in the feed streams; the convective heat loss from the shell to the environment; and a three-step and two-step eddy brake-up combustion model for natural gas and volatiles.
Check details here 
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I just need very coherent information about methods used to measure these parameters.
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I have already found it in Regulation of the Environmental Minister.
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i read that the length of each bed depends on the temperature rise, how is this determined?
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I highly recommend that you use a chemical process simulation program called HYSYS from Aspen Technologies Corporation. HYSYS will automatically perform mass and energy balances for your simulated system using its own thermodynamic equations. Using HYSYS, you can model any unit operation and it has many chemical reactor designs that you can choose from to do your simulation.
Here is the URL to explore HYSYS and possibly download a trail version.
Aspen Tech. has a product similar to HYSYS called AspenPlus and it does the same simulations like HYSYS. However, at Yale University I use HYSYS.
I use HYSYS program in the Chemical Engineering Process Design course CENG-416 that I teach at Yale University.
Hope this helps answer your question.
Professor Yehia Khalil, Yale University, USA
Fellow of the University of Oxford, UK
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I just wanted to know what will happen when we decrease the particle size of coal and then use it for combustion? Will the heating value of the powdered form be different.? Will the ignition temperature required be less? Has this size reduction something to do with "Low Temperature Combustion"? 
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The heating value is a chemical property (kJ/kg), so the physical structure of the coal is immaterial.  What will change is that it will ignite easier and the duration of burn is likely to be less, although this depends on whether you can manage to effectively separate the powder and distribute it through the air.  As the previous poster mentioned, there is an optimal size: if it is too big, the surface-area-to-volume ratio is too small, then the air doesn't interact with as much fuel; if it is too small, then the pyrolysis from the coal and the burned products surround the fuel too much and the air can't get to it.
Low-Temperature Combustion is more about the design of the combustor than the fuel.  For a furnace, MILD combustion will give you LTC, and the way it does this is to dilute the air with the burned products.  This preheats the air, making it easier to ignite the mixture, but being a diluent, there is more mass to heat for the same energy release, so the temperature cannot become as high.
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In fly ash, the crystal and amorphous phases both exist. But I don't know how to determine the mineral phase of silicate and aluminum silicate in the fly ash, especially in amorphous phase. which test can I do to figure out the structure of amorphous phase? Who can help me? 
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You can determine the mineral phased through quantitative XRD analysis. Through XRD, you can have the information of the crystalline phase. After that, you can get the information of the amorphous phase through the information of the total ash composition and the crystalline.
You can also read my paper 'Slagging characteristics of fly ash from anthracite gasification in fluidized bed'. You can find a way to determine the mineral phase in the fly ash.
Many thanks
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Is it possible to synthesize pure CuO-promoted natural ilmenite to use as an oxygen carrier in the chemical looping combustion process?
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I have synthesized pure CuO nanoparticles from copper nitrate and sodium hydroxide precursors. The resultant copper hydroxide precursors were dried overnight and the colour changed from pale blue to black CuO. The purity was confirmed by XRD. Try if this would help for what you are talking about.
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Is there anyone who familiar with the simulation of pulverized coal combustion with the Plasma torch (200 kW) using Ansys Fluent software. I am quite familiar with combustion problem (like RT Burner) but didn't know much how to incorporate plasma in the Fluent environment to initiate the coal combustion?? Please provide some guidance.    
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Check this: MODELING OF PULVERIZED COAL COMBUSTION
STABILIZATION BY MEANS OF PLASMA TORCHES
by
Miroslav SIJER^I], Srdjan BELOŠEVI],
and Predrag STEFANOVI]
Original scientific paper
UDC: 662.62:66.088
BIBLID: 0354-9836, 9 (2005), 2, 57-72
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I am simulating pulverized coal combustion using eddy-dissipation model (Turbulence-Chemistry Interaction). I have specified few reactions with their default Arrhenius rate parameters like (pre-exponential factor, activation energy etc.). The temperature that I am getting at the outlet of the burner is at least 300-400 K higher than what I am getting in the experimental setup, DO radiation model is also activated with all other 2nd order upwind. I read papers regarding this case in which they mentioned different Arrhenius rate parameters. I want to incorporate these parameters in my simulation instead of default values. But the problem is that Arrhenius rate parameters are not visible anymore, I can't change them further, only the  mixing rate is visible. Please guide how to modify these "Arrhenius rate parameters" . The figure is attached for the understanding of my problem.
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Certainly you know that the predicted results might be less/higher than experiments depending on your solution procedure. So, your problem has, probably, another reason than what you mentioned. In my understanding, Eddy-Dissipation model (EDM) works for Turbulence-Chemistry Interaction depending only on turbulence quantities (k, w, e), which means that EDM ignores chemical kinetics and then Arrhenius equation. 
I advice you to use Eddy-Dissipation concept (EDC) in which turbulence quantities and chemical kinetics are both exist. 
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I am wondering is it a clear process or more complex? And is the isotopic composition constant for example the d15N value of NOx from gasoline or coal combustion and the d15N-org of lichen thalli is the same?
I will be grateful for any answer or references.
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we are considering to mix sub bituminous with bituminous coal.
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Under my point of view, this is an economical keypoint. The moisture is a thermal power consumer. The limit moisture value will depend on the performance and budget issues. But if we focus on coal type, the moisture limit will depend on the thermal power, thus high thermal power cola will accept higher moisture content that other with lower thermal power.
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Some mechanisms to explain SOx formation (example :- Zeldovich for NOx)
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Dear Kalimuthu Selvam 
One of the easiest and best references about mechanism of SOx formation is ANSYS theory guide. In this reference you could find the mechanism of SOx  formation and its' equations in different type of fuels like liquid fuels, coal and etc.
Good Luck
Amir Javad Ahmadian Hosseini
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how to calculate required operational temperature for coal gasifier experimental furnace for low rank coal or biomass.
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Dear Mahesh Kumar Sharma,
your question is actually very general and thus cannot be answered easily. For example, the temperature depends not only on the fuel itself, but also on the process technology. Is it a moving bed downdraft or updraft gasifier? Or a fluidized bed system? What about autothermal or allothermal operation? What is your gasification Agent?
For the beginning, I suggest the book from Chris Higman "Gasification".
Best regards
Andreas
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In description of fly ash mineralogy it is frequently stated "magnetite crystals in fly ashes are derived from decomposition and high temperature oxidation of pyrite of feed coal in combustion boiler." What does decomposition mean? Is it complete melting of pyrite grains in boiler? Or solid state transformation of pyrite to magnetite without involving melting of pyrite (m.p. of pyrite- about 1180 deg. Celcius)?
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Decomposition means that the pyrite FeS2 first becomes FeS, while the "second" sulphur leaves as a gas and is oxidized to SO2
FeS (pyrrhotite) then oxidises
FeS is a liquid and the particles become droplets and therefore the iron-oxide particles are also spherical.
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We experienced strange SO2 readings during biomass gasification. The SO2 reading of the IR analyser incereases when the oxygen concetration decreases. This is rather suprising, considering that the decrease in oxygene (and the increase of carbon monoxide) suggests reducing conditions therefor SO2 concetration should decrease and other sulfur forms (like H2S) are expected.
I attached figure presenting the concentrations of the CO2, CO, O2, and SO2 during experiment for clarification.
How can it be explained?
Regards,
Marcin Stec
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Dear Muhammad and Jai,
Thank You for the involvement. The culprit (accurate description) was found - it is carbon monoxide. I've compared trends of CO and SO2, and verified the composition of gas using chromatography and no measurable sulfur compounds were found. An the comparison of CO and SO2 trends prooved that they are correlated.
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Hi all,
I am modelling coal combustion using the PDF mixture fraction approach however as my job solves I have the following message appear at most iterations...
Minimum PDF table temperature in 1023 cells on zone 10
...the number of cells varies however it never seems to reduce down to zero. I have tried changing the number of enthalpy points and mean mixture fraction points when creating the PDF table however at present this does not seem to make any difference. Also the air entering my kiln is at 337K and ~1000K while I have set the minimum temperature as 298K
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I also had the same problem with ch4 combustion. it was resolved after introducing secondary air stream. 
note: for secondary air stream RFL value should be = 1.0
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Good day. I am using ideal gases (CO2, H2O,N2,O2,SO2) to model the products (flue gases) of coal combustion. I need to develop a lookup table of the enthalpies of the ideal gases at different temperatures. I know how to calculate the volumes of the different ideal gases, but I struggle to calculate the volumetric heat capacity of each ideal gas. An example of how I need to calculate the enthalpy of CO2 is the following:
HCO2 = CpCO2 * T * VCO2,
where HCO2 is the enthalpy (kJ/kg) of CO2 at temperature T, CpCO2 is the volumetric heat capacity (kJ/m^3.K), T is the temperature (K), and VCO2 is the specific volume (m^3/kg) of CO2.
How does one calculate CpCO2 (kJ/m^3.K)?
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There is a really good book on syngas manufacture called "Concepts in Syngas manufacture" if you can get hold of it it has temperature dependant heat capacities for all of your molecules of interest to fairly high temperatures.
Here is a link with some information about the book, but not the book itself. I would expect most technical universities to have it available. http://www.worldscientific.com/worldscibooks/10.1142/p717
Also, Cp = dH/dT at constant pressure. To calculate change in enthalpy  then you need to integrate both sides. Thus you integrate the polynomial ideal heat capacity equation. (It is generally a polynomial).
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Why the coal-fired boiler power plant need to have low rear pass temperature?
Can anyone help answering my question or share any related links/journals
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It is designed to maintain low temperature for not allowing more heat to be carried out by exit flue gases for efficient operation practice.
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Posafai et al (2004), argued that to their knowledge, individual-particle studies of coal and oil burning emissions and of urban aerosols do not indicate the presence of tar balls. In my research I have identified spherical organic particles that have similar characteristics to tar balls in smoke emissions from domestic fixed-bed coal combustion.
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I would extend the explanation to include high EA conditions when you are burning bituminous and sub-bituminous coal.
I tried some Virginia coals (3) in a bottom-lit downdraft (BLDD) stove and had significant tar formation which was not in the form of balls, but a general gluing together of all the coal. Loose coal was put in, it got hot under adequate air conditions, it all glued itself together into a single mass. The glue was flowing high melting temperature tar, which later burned away leaving individual pieces of coke. If the Time Temperature Turbulence combination was inadequate, the consequence would be condensed tar PM.
I attributed this to the tars which have melting temperatures high enough to resist instant vaporisation. I expect that during incomplete combustion of that material, you will get spherical PM with a similar composition.
If you can get an XRF and XRD analysis, send it to Prof Lodoysamba in Mongolia and ask him if it is recognisable. He has done a lot of nuclear analysis of PM in Ulaanbaatar.
From his lessons, you can develop the capacity to use those two tests to track particles back to their origins (source apportionment).  He was able to differentiate between carbonaceous particles that came from high and low temperature combustion.(i.e. power stations and domestic stoves).
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When estimating the CO2 emissions consequences of new electricity production facilities, the emissions of the marginal production technology, often coal power, are used as a reference. What fossil fuel production technology could be assumed when estimating CO2 emissions consequences of changing fuels?
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Dear Roman Hackl
As concerned to  fossil fuels utilization for power generation, Natural gas combined cycle has lower CO2 emissions without CCS, while Pulverized Coal fuel has highest CO2 emissions. similarly UCG-IGCC-CCS has the lowest emissions.
For your understanding I have attached a slide of Air emissions.
Regards.
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I want the  chemical name of the Quinone used as a reducing agent in H2S removal process from syn gas stream on commercial level process.                       Regards
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Dear Dr. Ralf,
Thanks for your guidance.
Regards.
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How much amount of practical Air using solid coal and powder coal down gasifier?
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Not knowing t he ultimate analysis and based on the typical stoichiometric air/coal ratio I know from different biomass which is around 5 I can say your ER value is somewhere around 0.6 which is quite a large value. 
How did u come up with this flow?
My suggestion to you is to search for any kind of coal air gasification ( regardless the gasifier type) to get a feeling about the typical ratio for your case.
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I want to prepare composites refractory material from literature, slaked lime and clinkers (from coal combustion residues). How can I choose the best formulation and the best preparation method to achieve good thermal (conductivity and capacity) and mechanical properties?
Thanks you in advance for your help.
Eric
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As I know you can make the small particle size of your raw material, and sinter  at temperature 1000- 1300
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I am carrying out life cycle analysis of coal power plant for Indian condition. Where can I find complete details regarding coal power plants? For example, energy consumption, material consumption, water consumption, land usage for construction of power plant.
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Yes. Complete set of technical specifications are given in the following literature
STANDARD TECHNICAL SPECIFICATION FOR MAIN PLANT PACKAGE
OF SUB- CRITICAL THERMAL POWER PROJECT
2x (500 MW OR ABOVE)
Government of India
Ministry of Power
Central Electricity Authority
New Delhi
SEPTEMBER, 2008
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How much actual (practically) air is required for 1kg/hr coal gasification?
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@Rasool: You are right, but I was trading oxygen against ashes - at least for the 1st order approximation. :-)
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I am trying to model low grade coal combustion in a CFB. Its a 3D riser of 4 m length. I am using FLUENT as a CFD solver, however, I am encountering some convergence problems. Can we model the same problem in any other CFD solver more easily?
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It depends on the nature of the problem itself. Sometimes it is not an easy task to determine the conditions of divergence. According to my little experience, defining, implementing and mishandling of boundary conditions are one of main sources of divergence in simulation.