Coal is the largest source of energy for the generation of electricity worldwide, at the same time, one of the largest anthropogenic sources of oxides of carbon and other green house gases released in to atmosphere. Coal gasification has emerged as a cleaner technology for production of combustible gases for power and heat generation which reduces the carbon dioxide emission.
The effect of operating conditions (temperature and pressure) on the rate of gasification of coal-char is very important regarding the design and operation of coal gasifier. It is obvious that the rate of coal-char gasification reaction depends on the operating conditions, which is studied by using the shrinking spherical ashless (un-reacted) particle model. The rate of gasification of coal-char increases with increasing temperature and partial pressure of CO2 but the total system pressure shows the negative effect on the conversion of coal-char.
Keywords: Coal gasification, shrinking core model
INTRODUCTION
The reaction of carbon with CO2 is important in a variety of the applications including power generation using coal gasification and the smelting of iron and steel. Since several commercial gasifiers for IGCC operates at a high temperature and a high pressure (1200-1600 0C, 2.5 MPa). Form the existing literature, information on coal gasification characteristics at atmospheric pressure can be found [1-3]. However, only a few fundamental studies on coal gasification reactivity at high temperature and elevated pressure were reported [4-7]. The gasification of coal consists of two major reactions: pyrolysis of coal and gasification of char. Since the rate of char-gasification is much slower than that of devolatilisation, the gasification characteristics o...
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...on data X vs. time at reaction temperature of 1300 0C, total pressure of 1 MPa.
3. CONCLUSIONS
Gasification kinetics of an Indonesian sub-bituminous coal-char with CO2 is studied by use of un-reacted shrinking core model. The following results are obtained.
The rate of gasification is dependent on the total pressure, temperature, and partial pressure of gasifying agents.
The conversion fraction of coal-char will decreases with increasing the total pressure from 0.5-1.5 MPa at constant temperature and partial pressure of gasifying agent.
The conversion fraction of coal-char will increases on increasing the temperature from 900-1400 0C at constant total pressure and partial pressure of the gas.
The conversion fraction of coal-char will also increases on increasing the partial pressure of gasifying agent from 0.2-0.5 MPa at constant total pressure and temperature.
Fossil fuels, such as coal and oil, are Carbon rich compounds, the combustion of which produces Carbon Dioxide, a pollutant and a greenhouse gas. A large amount of energy is released during this process, which is why the pollutants off products are tolerated. This process occurs constantly throughout the world, in power stations, vehicles and cooking ovens, leading to an immense volume of CO2 being released every second, 50% of which is absorbed by oceans (Oce...
= = = == I predict that as the concentration of the hydrochloric acid decreases the rate of reaction will decrease and therefore the time taken for 75ml of gas to be released will increase.
Coal also can be very damaging to the environment. People in the coal industry don’t always follow the precautions needed for helping the recovering environment that coal mining hurt. Most of the time water is polluted from the byproduct the is produced while mining coal. Like acid mine drainage, air pollution from coal-fired power plants, coal dust, coal sludge, and mountaintop
Temperature increases the rate of reaction between molecules; this will have a profound impact on the rate of respiration. Rate is determined on how fast something is being consumed in a reaction, or how fast something is being crated. The rate of respiration is measured the easiest by the amount of C02 produced by the reaction or by the amount of C02 consumed. The best way to measure gasses is by creating a closed system for an experiment to take place. Consuming oxygen decreases the volume of gas while the production of CO2 increases the production of gas.
On February 2, 2014, a coal ash spill occurred in Eden, North Carolina which affected the Dan River; wildlife, drinking water, and other surroundings were destroyed or contaminated. The spill was caused by a leaky 48-inch storm water pipe located in a defunct steam station. The spill not only devastated its surroundings, but “sent millions of gallons of sledge” into the river which is used by North Carolina and Virginia citizens for drinking water (Shoichet, 2014). The leak was eventually patched, but left traces of copper, aluminum, iron, and arsenic that state environmental officials stated were “above state standards for surface water” (Shoichet, 2014). At the time, the article was published by CNN, environmental officials were working on a plan for cleaning up the river and remaining pollutants. Although the spill was not a major spill, the future effects that coal ash may have on the river, wildlife and citizens of North Carolina and Virginia are unknown.
Coal is one of the world’s most abundant fossil fuels. Coal was formed during the Carboniferous Period when dead plant material was buried and subjected to high pressure and heat. Coal is classified by moisture content and composition. There are four d...
Roughly 68 percent of the electricity generated in the United States of America is produced by fossil fuels. That includes petroleum, natural gases and coal. Although coal contributes around 37 percent to the factor, it is by far not the cleanest of them all. Some might argue that it is good for the economy because it is cheap and it creates jobs.. But the other side of the story portrays coal mining as a process that kills thousands of coal miners a year and that it practically destroys the environment around the mining with soot and air pollution. Mining now days is a big part of urbanization; due to how cheap the process is. There are different ways that coal mining is done. Mainly mountain top removal is done but there are many other
The process of gas exchange is very important in living things as it allows the production of energy which is required in body cells in order for life process such as reproduction to take place. Oxygen and carbon dioxide are the main gases involved in this process. Gas exchange is the diffusion of oxygen and carbon dioxide in and out of the cells. It is essential for respiration to occur. A carbon dioxide build up in the body is extremely dangerous so this must be removed from the body. Respiration is a process which is required for living things as it removes carbon dioxide from the body and replaces it with oxygen, this being a requirement for survival.
The natural resource that I am writing this paper on is coal. Coal is a cheap, dirty fossil fuel which we burn to create power. Coal is the most abundant in North America and in Russia, including the area around it. China also has a fairly good amount of coal in it too. Coal, like all of the other fossil fuels is nonrenewable and will eventually run out, in the not so near future. Coal is very important to many of the countries of the world. The countries that use the most coal are China, the United States, India, Russia, and Japan. These five countries “account for 76% of total global coal use.” (World Coal Association, 2014).
...ch is used to replace natural gas. He also stated that, among the equipment used to burn the biofuel, the suspension burner have the ability to exceed 99% efficiency and whole-tree burner can reduce the cost of harvesting and handling woody fuels by about 35% (Brown, 2003). Moreover, the usage of bio-energy in long term is to provide a degree of ecological balance and climate change, avoid acid rain, reduce soil erosion and minimize water pollution (Gevorkian, 2007). Therefore, biomass is environmental friendly like solar energy. Based on the research that has been carried out regarding the synthesis of gas from biomass, the gas gasifies in the internal combustion engine. The relative energy density of synthesis gas is higher than the fossil fuel under certain conditions. In addition, the relative flame speed of synthesis gas can reduce the time for spark ignition.
When coal gets burned they start to release harmful dangerous toxins such as mercury, lead and arsenic that will then escape into the air. It also releases large amounts of carbon dioxide (CO2) into the atmosphere. These emissions increase the greenhouse effect in the atmosphere and lead to global warming.
All different kinds of secondary products are discussed in these section such as particulate matter (section 2.3.1), Tar compound (section 2.3.2), Sulphur compound (2.2.4). Although not much literature is available, section 2.3.3 briefly introduces the importance of Alkaline, heavy metals and halides compounds as secondary products. It is worth mentioning that secondary products come out from the gasification process concentrations of which in the gas depend on the biomass composition and the technology used.
The emission of green house gasses due to human activity contributes the most in increasing global warming. Today, fossil fuels are used as a source of energy for transportation, electricity, industrial process and to increase human comfort in this era. Over the last decade humans have created mass amount of industries. These industries have been burning fossil fuels such as coal, which release carbon dioxide and carbon monoxide; carbon dioxide absorbs heat that raises the temperature of the earth. More than 80% of carbon dioxide comes from tr...
Compacting of loose material other combustible waste products to improve the volumetric calorific value of fuel
Coking coal is a process that is used to help drive away impurities and leave almost pure carbon based material. The properties of coking coal cause the coal to soften, liquefy and then resolidify into a hard and porous lumps when heated in the absence of air. Coking must also have very low sulphur and phosphorous content this is due to the fact that almost all metallurgical coal is used in coke ovens. At this point the coking process undertakes being heated to around 1000 - 1100⁰C this has to be in the absents of oxygen to drive off any volatile compounds (Pyrolysis).