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  1. 1. EDUCATION HOLE PRESENTS ENGINEERING CHEMISTRY Unit-V
  2. 2. Fuels........................................................................................................................................ 3 Classification of fuels .......................................................................................................................3 Solid fuels.............................................................................................................................................................3 Liquid fuel.............................................................................................................................................................4 Gaseous fuels.......................................................................................................................................................4 Biofuels.................................................................................................................................................................5 Fossil fuels............................................................................................................................................................5 Nuclear............................................................................................................................................6 Fission ..................................................................................................................................................................6 Fusion...................................................................................................................................................................7 Analysis of Coal ....................................................................................................................... 7 Chemical properties of coal..............................................................................................................8 Moisture...............................................................................................................................................................8 Volatile matter .....................................................................................................................................................8 Ash .......................................................................................................................................................................9 Fixed carbon.........................................................................................................................................................9 Chemical analysis .................................................................................................................................................9 Physical and mechanical properties......................................................................................... 9 Relative density ...............................................................................................................................9 Particle size distribution ................................................................................................................ 10 Float-sink test................................................................................................................................ 10 Abrasion testing............................................................................................................................. 10 Special combustion tests ....................................................................................................... 10 Ash fusion test............................................................................................................................... 11 Crucible swelling index (free swelling index) .....................................................................................................11 Determination of Calorific values .......................................................................................... 11 Heating value................................................................................................................................. 11 Higher heating value..........................................................................................................................................12 Lower heating value...........................................................................................................................................12 Gross heating value............................................................................................................................................13 Measuring heating values..................................................................................................................................13 Relation between heating values.......................................................................................................................13 Biogas ................................................................................................................................... 14 Biomass......................................................................................................................................... 15 Cement and its application ............................................................................................................ 16 Applications of cement.......................................................................................................... 16
  3. 3. Plaster of paris............................................................................................................................... 16 Lubricant ....................................................................................................................................... 17 Types of Lubricants ............................................................................................................................................17 Application of UNICORN Brand Lubricants ........................................................................................................18 Corrosion............................................................................................................................... 18 Fuels Fuels are any materials that store potential energy in forms that can be practicably released and used as heat energy. The concept originally applied solely to those materials storing energy in the form of chemical energy that could be released through combustion, but the concept has since been also applied to other sources of heat energy such as nuclear energy (via nuclear fission or nuclear fusion), as well as releases of chemical energy released through non-combustion oxidation (such as in cellular biology or in fuel cells). The heat energy released by many fuels is harnessed into mechanical energy via an engine. Other times the heat itself is valued for warmth, cooking, or industrial processes, as well as the illumination that comes with combustion. Fuels are also used in the cells of organisms in a process known as cellular respiration, where organic molecules are oxidized to release un-usable energy. Hydrocarbons are by far the most common source of fuel used by humans, but other substances, including radioactive metals, are also utilized. Fuels are contrasted with other methods of storing potential energy, such as those that directly release electrical energy (such as batteries and capacitors) or mechanical energy (such as flywheels, springs, compressed air, or water in a reservoir). Classification of fuels Solid fuels Solid fuel refers to various types of solid material that are used as fuel to produce energy and provide heating, usually released through combustion. Solid fuels include wood (see wood fuel), charcoal, peat, coal, Hexamine fuel tablets, and pellets made from wood (see wood pellets), corn, wheat, rye and other grains. Solid-fuel rocket technology also uses solid fuel (see solid propellants). Solid fuels have been used by humanity for many years to create fire. Coal was the fuel source which enabled the industrial revolution, from firing furnaces, to running steam engines. Wood was also extensively used to run steam locomotives. Both peat and coal are still used in electricity generation today. The use of some solid fuels (e.g. coal) is restricted or
  4. 4. prohibited in some urban areas, due to unsafe levels of toxic emissions. The use of other solid fuels such as wood is decreasing as heating technology and the availability of good quality fuel improves. In some areas, smokeless coal is often the only solid fuel used. In Ireland, peat briquettes are used as smokeless fuel. They are also used to start a coal fire. Liquid fuel Liquid fuels are combustible or energy-generating molecules that can be harnessed to create mechanical energy, usually producing kinetic energy; they also must take the shape of their container. It is the fumes of liquid fuels that are flammable instead of the fluid. Most liquid fuels in widespread use are derived from fossil fuels; however, there are several types, such as hydrogen fuel (for automotive uses), ethanol, and biodiesel, which are also categorized as a liquid fuel. Many liquid fuels play a primary role in transportation and the economy. Some common properties of liquid fuels are that they are easy to transport, and can be handled with relative ease. Also they are relatively easy to use for all engineering applications, and home use. (Fuels like Kerosene are rationed and available in government subsidized shops in India for home use.) Liquid fuels are also used most popularly in Internal combustion engines. Most liquid fuels used currently are produced from petroleum. The most notable of these is gasoline. Scientists generally accept that petroleum formed from the fossilized remains of dead plants and animals by exposure to heat and pressure in the Earth's crust. Conventional diesel is similar to gasoline in that it is a mixture of aliphatic hydrocarbons extracted from petroleum. Kerosene is used in kerosene lamps and as a fuel for cooking, heating, and small engines. Natural gas, composed chiefly of methane, can be compressed to a liquid and used as a substitute for other traditional liquid fuels. LP gas is a mixture of propane and butane, both of which are easily- compressible gases under standard atmospheric conditions. It offers many of the advantages of compressed natural gas (CNG), but is denser than air, does not burn as cleanly, and is much more easily compressed. Commonly used for cooking and space heating, LP gas and compressed propane are seeing increased use in motorized vehicles; propane is the third most commonly used motor fuel globally. Gaseous fuels Fuel gas is any one of a number of fuels that under ordinary conditions are gaseous. Many fuel gases are composed of hydrocarbons (such as methane or propane), hydrogen, carbon monoxide, or mixtures thereof. Such gases are sources of potential heat energy or light energy that can be readily transmitted and distributed through pipes from the point of origin directly to the place of consumption. Fuel gas is contrasted with liquid fuels and from solid fuels, though some fuel gases are liquefied for storage or transport. While their gaseous nature can be advantageous, avoiding the difficulty of transporting solid fuel and the dangers of spillage inherent in liquid fuels, it can also be dangerous. It is possible for a fuel gas to be undetected and collect in certain areas, leading to the risk of a gas explosion. For this reason, odorizers are added to most fuel
  5. 5. gases so that they may be detected by a distinct smell. The most common type of fuel gas in current use is natural gas. Biofuels Biofuel can be broadly defined as solid, liquid, or gas fuel consisting of, or derived from biomass. Biomass can also be used directly for heating or power—known as biomass fuel. Biofuel can be produced from any carbon source that can be replenished rapidly e.g. plants. Many different plants and plant-derived materials are used for biofuel manufacture. Perhaps the earliest fuel employed by humans is wood. Evidence shows controlled fire was used up to 1.5 million years ago at Swartkrans, South Africa. It is unknown which hominid species first used fire, as both Australopithecus and an early species of Homo were present at the sites. As a fuel, wood has remained in use up until the present day, although it has been superseded for many purposes by other sources. Wood has an energy density of 10–20 MJ/kg. Recently biofuels have been developed for use in automotive transport (for example Bioethanol and Biodiesel), but there is widespread public debate about how carbon efficient these fuels are. Fossil fuels Fossil fuels are hydrocarbons, primarily coal and petroleum (liquid petroleum or natural gas), formed from the fossilized remains of ancient plants and animals by exposure to high heat and pressure in the absence of oxygen in the Earth's crust over hundreds of millions of years. Commonly, the term fossil fuel also includes hydrocarbon-containing natural resources that are not derived entirely from biological sources, such as tar sands. These latter sources are properly known as mineral fuels. Fossil fuels contain high percentages of carbon and include coal, petroleum, and natural gas. They range from volatile materials with low carbon:hydrogen ratios like methane, to liquid petroleum to nonvolatile materials composed of almost pure carbon, like anthracite coal. Methane can be found in hydrocarbon fields, alone, associated with oil, or in the form of methane clathrates. Fossil fuels formed from the fossilized remains of dead plants . by exposure to heat and pressure in the Earth's crust over millions of years. This biogenic theory was first introduced by German scholar Georg Agricola in 1556 and later by Mikhail Lomonosov in the 18th century. It was estimated by the Energy Information Administration that in 2007 primary sources of energy consisted of petroleum 36.0%, coal 27.4%, natural gas 23.0%, amounting to an 86.4% share for fossil fuels in primary energy consumption in the world. Non-fossil sources in 2006
  6. 6. included hydroelectric 6.3%, nuclear 8.5%, and others (geothermal, solar, tidal, wind, wood, waste) amounting to 0.9%. World energy consumption was growing about 2.3% per year. Fossil fuels are non-renewable resources because they take millions of years to form, and reserves are being depleted much faster than new ones are being made. The production and use of fossil fuels raise environmental concerns. A global movement toward the generation of renewable energy is therefore under way to help meet increased energy needs. The burning of fossil fuels produces around 21.3 billion tonnes (21.3 gigatonnes) of carbon dioxide (CO2) per year, but it is estimated that natural processes can only absorb about half of that amount, so there is a net increase of 10.65 billion tonnes of atmospheric carbon dioxide per year (one tonne of atmospheric carbon is equivalent to 44/12 or 3.7 tonnes of carbon dioxide). Carbon dioxide is one of the greenhouse gases that enhances radiative forcing and contributes to global warming, causing the average surface temperature of the Earth to rise in response, which the vast majority of climate scientists agree will cause major adverse effects. Fuels are a source of energy. Nuclear Nuclear fuel is any material that is consumed to derive nuclear energy. Technically speaking this definition includes all matter because any element under the right conditions will release nuclear energy, the only materials that are commonly referred to as nuclear fuels though are those that will produce energy without being placed under extreme duress. Nuclear fuel is a material that can be 'burned' by nuclear fission or fusion to derive nuclear energy. Nuclear fuel can refer to the fuel itself, or to physical objects (for example bundles composed of fuel rods) composed of the fuel material, mixed with structural, neutron moderating, or neutron reflecting materials. Most nuclear fuels contain heavy fissile elements that are capable of nuclear fission. When these fuels are struck by neutrons, they are in turn capable of emitting neutrons when they break apart. This makes possible a self-sustaining chain reaction that releases energy with a controlled rate in a nuclear reactor or with a very rapid uncontrolled rate in a nuclear weapon. The most common fissile nuclear fuels are uranium-235 (235 U) and plutonium-239 (239 Pu). The actions of mining, refining, purifying, using, and ultimately disposing of nuclear fuel together make up the nuclear fuel cycle. Not all types of nuclear fuels create power from nuclear fission. Plutonium-238 and some other elements are used to produce small amounts of nuclear power by radioactive decay in radioisotope thermoelectric generators and other types of atomic batteries. Also, light nuclides such as tritium (3 H) can be used as fuel for nuclear fusion. Nuclear fuel has the highest energy density of all practical fuel sources. Fission The most common type of nuclear fuel used by humans is heavy fissile elements that can be made to undergo nuclear fission chain reactions in a nuclear fission reactor; nuclear fuel can
  7. 7. refer to the material or to physical objects (for example fuel bundles composed of fuel rods) composed of the fuel material, perhaps mixed with structural, neutron moderating, or neutron reflecting materials. The most common fissile nuclear fuels are 235 U and 239 Pu, and the actions of mining, refining, purifying, using, and ultimately disposing of these elements together make up the nuclear fuel cycle, which is important for its relevance to nuclear power generation and nuclear weapons. Fusion Fuels that produce energy by the process of nuclear fusion are currently not utilized by man but are the main source of fuel for stars. Fusion fuels tend to be light elements such as hydrogen which will combine easily. Energy is required to start fusion by raising temperature so high all materials would turn into plasma, and allow nuclei to collide and stick together with each other before repelling due to electric charge. This process is called fusion and it can give out energy. In stars that undergo nuclear fusion, fuel consists of atomic nuclei that can release energy by the absorption of a proton or neutron. In most stars the fuel is provided by hydrogen, which can combine together to form helium through the proton-proton chain reaction or by the CNO cycle. When the hydrogen fuel is exhausted, nuclear fusion can continue with progressively heavier elements, although the net energy released is lower because of the smaller difference in nuclear binding energy. Once iron-56 or nickel-56 nuclei are produced, no further energy can be obtained by nuclear fusion as these have the highest nuclear binding energies. The elements then on use up energy instead of giving out when fused, and therefore fusion stops and the stars die. In attempts by human, fusion are only carried out with hydrogen (isotope of 2 and 3) to form helium-4 as this reaction gives out the most net energy. Electric confinement (ITER), inertial confinement(heating by laser) and heating by strong electric currents are the popular methods used. The power given out is enormonus as each kilogram of hydrogen can give out 0.41PJ. This means that burning 0.7 tonne of hydrogen per second can power the world, replacing the millions of tonnes of fossil fuels burnt and emission made by us each second. Unfortunately this clean energy whose product would dissipate harmlessly as helium if leak happens, and also does not emit any radiation or pollution, is not expected to contribute electricity to electricity networks until 2040. Analysis of Coal Coal Analysis techniques are specific analytical methods designed to measure the particular physical and chemical properties of coals. These methods are used primarily to determine the suitability of coal for coking, power generation or for iron ore smelting in the manufacture of steel.
  8. 8. Chemical properties of coal Coal comes in four main types or ranks: lignite or brown coal, bituminous coal or black coal, anthracite and graphite. Each type of coal has a certain set of physical parameters which are mostly controlled by moisture, volatile content (in terms of aliphatic or aromatic hydrocarbons) and carbon content. Moisture Moisture is an important property of coal, as all coals are mined wet. Groundwater and other extraneous moisture is known as adventitious moisture and is readily evaporated. Moisture held within the coal itself is known as inherent moisture and is analysed quantitatively. Moisture may occur in four possible forms within coal: • Surface moisture: water held on the surface of coal particles or macerals • Hydroscopic moisture: water held by capillary action within the microfractures of the coal • Decomposition moisture: water held within the coal's decomposed organic compounds • Mineral moisture: water which comprises part of the crystal structure of hydrous silicates such as clays Total moisture is analysed by loss of mass between an untreated sample and the sample once analysed. This is achieved by any of the following methods; 1. Heating the coal with toluene 2. Drying in a minimum free-space oven at 150 °C (302 °F) within a nitrogen atmosphere 3. Drying in air at 100 to 105 °C (212 to 221 °F) and relative loss of mass determined Methods 1 and 2 are suitable with low-rank coals but method 3 is only suitable for high-rank coals as free air drying low-rank coals may promote oxidation. Inherent moisture is analysed similarly, though it may be done in a vacuum. Volatile matter Volatile matter in coal refers to the components of coal, except for moisture, which are liberated at high temperature in the absence of air. This is usually a mixture of short and long chain hydrocarbons, aromatic hydrocarbons and some sulfur. The volatile matter of coal is determined under rigidly controlled standards. In Australian and British laboratories this involves heating the coal sample to 900 ± 5 °C (1650 ±10 °F) for 10 min.
  9. 9. Ash Ash content of coal is the non-combustible residue left after coal is burnt. It represents the bulk mineral matter after carbon, oxygen, sulfur and water (including from clays) has been driven off during combustion. Analysis is fairly straight forward, with the coal thoroughly burnt and the ash material expressed as a percentage of the original weight. It can also give an indication about the quality of coal. Fixed carbon The fixed carbon content of the coal is the carbon found in the material which is left after volatile materials are driven off. This differs from the ultimate carbon content of the coal because some carbon is lost in hydrocarbons with the volatiles. Fixed carbon is used as an estimate of the amount of coke that will be yielded from a sample of coal. Fixed carbon is determined by removing the mass of volatiles determined by the volatility test, above, from the original mass of the coal sample. Chemical analysis Coal is also assayed for oxygen content, hydrogen content and sulfur. Sulfur is also analysed to determine whether it is a sulfide mineral or in a sulfate form. Sulfide content is determined by measurement of iron content, as this will determine the amount of sulfur present as iron pyrite or dissolution of the sulfates in hydrochloric acid with precipitation as barium sulfate. Carbonate minerals are analysed similarly, by measurement of the amount of carbon dioxide emitted when the coal is treated with hydrochloric acid. The carbonate content is necessary to determine the combustible carbon content and incombustible (carbonate carbon) content. Chlorine, phosphorus and iron are also determined to characterise the coal's suitability for steel manufacture.An analysis of coal ash may also be carried out to determine not only the composition of coal ash, but also to determine the levels at which trace elements occur in ash. Physical and mechanical properties Relative density Relative density or specific gravity of the coal depends on the rank of the coal and degree of mineral impurity. Knowledge of the density of each coal ply is necessary to determine the properties of composites and blends. The density of the coal seam is necessary for conversion of resources into reserves. Relative density is normally determined by the loss of a sample's weight in water. This is best achieved using finely ground coal, as bulk samples are quite porous. To
  10. 10. determine in-place coal tonnages however, it is important to preserve the void space when measuring the specific gravity. Particle size distribution The particle size distribution of milled coal depends partly on the rank of the coal, which determines its brittleness, and on the handling, crushing and milling it has undergone. Generally coal is utilised in furnaces and coking ovens at a certain size, so the crushability of the coal must be determined and its behaviour quantified. It is necessary to know these data before coal is mined, so that suitable crushing machinery can be designed to optimise the particle size for transport and use. Float-sink test Coal plies and particles have different relative densities, determined by vitrinite content, rank, ash value/mineral content and porosity. Coal is usually washed by passing it over a bath of liquid of known density. This removes high-ash value particles and increases the saleability of the coal as well as its energy content per unit volume. Thus, coals must be subjected to a float-sink test in the laboratory, which will determine the optimum particle size for washing, the density of the wash liquid required to remove the maximum ash value with the minimum work. Floatsink testing is achieved on crushed and pulverised coal in a process similar to metallurgical testing on metallic ore. Abrasion testing Abrasion is the property of the coal which describes its propensity and ability to wear away machinery and undergo autonomous grinding. While carbonaceous matter in coal is relatively soft, quartz and other mineral constituents in coal are quite abrasive. This is tested in a calibrated mill, containing four blades of known mass. The coal is agitated in the mill for 12,000 revolutions at a rate of 1,500 revolutions per minute.(I.E 1500 revolution for 8 min.) The abrasion index is determined by measuring the loss of mass of the four metal blades. Special combustion tests Aside from physical or chemical analyses to determine the handling and pollutant profile of a coal, the energy output of a coal is determined using a bomb calorimeter which measures the specific energy output of a coal during complete combustion. This is required particularly for coals used in steam-raising.
  11. 11. Ash fusion test The behaviour of the coal's ash residue at high temperature is a critical factor in selecting coals for steam power generation. Most furnaces are designed to remove ash as a powdery residue. Coal which has ash that fuses into a hard glassy slag known as clinker is usually unsatisfactory in furnaces as it requires cleaning. However, furnaces can be designed to handle the clinker, generally by removing it as a molten liquid. Ash fusion temperatures are determined by viewing a moulded specimen of the coal ash through an observation window in a high-temperature furnace. The ash, in the form of a cone, pyramid or cube, is heated steadily past 1000 °C to as high a temperature as possible, preferably 1,600 °C (2,910 °F). The following temperatures are recorded; • Deformation temperature: This is reached when the corners of the mould first become rounded • Softening (sphere) temperature: This is reached when the top of the mould takes on a spherical shape. • Hemisphere temperature: This is reached when the entire mould takes on a hemisphere shape • Flow (fluid) temperature: This is reached when the molten ash collapses to a flattened button on the furnace floor. Crucible swelling index (free swelling index) The simplest test to evaluate whether a coal is suitable for production of coke is the free swelling index test. This involves heating a small sample of coal in a standardised crucible to around 800 degrees Celsius (1500 °F). After heating for a specified time, or until all volatiles are driven off, a small coke button remains in the crucible. The cross sectional profile of this coke button compared to a set of standardised profiles determines the Free Swelling Index. Determination of Calorific values Heating value The heating value (or energy value or calorific value) of a substance, usually a fuel or food (see food energy), is the amount of heat released during the combustion of a specified amount of it. The energy value is a characteristic for each substance. It is measured in units of energy per unit of the substance, usually mass, such as: kJ/kg, kJ/mol, kcal/kg, Btu/lb. Heating value is commonly determined by use of a bomb calorimeter.
  12. 12. Heating value unit conversions (for more visit Wolfram Alpha): • kcal/kg = MJ/kg * 238.846 • Btu/lb = MJ/kg * 429.923 • Btu/lb = kcals * 1.8 The heat of combustion for fuels is expressed as the HHV, LHV, or GHV. Higher heating value The quantity known as higher heating value (HHV) (or gross energy or upper heating value or gross calorific value (GCV) or higher calorific value (HCV)) is determined by bringing all the products of combustion back to the original pre-combustion temperature, and in particular condensing any vapor produced. Such measurements often use a standard temperature of 25°C. This is the same as the thermodynamic heat of combustion since the enthalpy change for the reaction assumes a common temperature of the compounds before and after combustion, in which case the water produced by combustion is liquid.The higher heating value takes into account the latent heat of vaporization of water in the combustion products, and is useful in calculating heating values for fuels where condensation of the reaction products is practical (e.g., in a gas-fired boiler used for space heat). In other words, HHV assumes all the water component is in liquid state at the end of combustion (in product of combustion) and that heat below 150°C can be put to use. Lower heating value The quantity known as lower heating value (LHV) (net calorific value (NCV) or lower calorific value (LCV)) is determined by subtracting the heat of vaporization of the water vapor from the higher heating value. This treats any H2O formed as a vapor. The energy required to vaporize the water therefore is not released as heat. LHV calculations assume that the water component of a combustion process is in vapor state at the end of combustion, as opposed to the higher heating value (HHV) (a.k.a. gross calorific value or gross CV) which assumes that all of the water in a combustion process is in a liquid state after a combustion process. The LHV assumes that the latent heat of vaporization of water in the fuel and the reaction products is not recovered. It is useful in comparing fuels where condensation of the combustion products is impractical, or heat at a temperature below 150°C cannot be put to use. The above is but one definition of lower heating value adopted by the American Petroleum Institute (API) and uses a reference temperature of 60°F (15.56°C). Another definition, used by Gas Processors Suppliers Association (GPSA) and originally used by API (data collected for API research project 44), is the enthalpy of all combustion products minus the enthalpy of the fuel at the reference
  13. 13. temperature (API research project 44 used 25°C. GPSA currently uses 60°F), minus the enthalpy of the stoichiometric oxygen (O2) at the reference temperature, minus the heat of vaporization of the vapor content of the combustion products. The distinction between the two is that this second definition assumes that the combustion products are all returned to the reference temperature and the heat content from the condensing vapor is considered not to be useful. This is more easily calculated from the higher heating value than when using the preceding definition and will in fact give a slightly different answer. Gross heating value • Gross heating value (see AR) accounts for water in the exhaust leaving as vapor, and includes liquid water in the fuel prior to combustion. This value is important for fuels like wood or coal, which will usually contain some amount of water prior to burning. • Note that GPSA 12th Edition states that the Gross Heating Value of a gas is equivalent to Higher Heating Value. This suggests that there may be different standards in play. The use of the term Gross normally describes a larger value than the Net, which usually describes a smaller value. GPSA is consistent with this, and equates the Gross Heating Value to the higher heating value (for a gas - so probably with no liquid water present), and the Net Heating Value to the lower heating value. Measuring heating values The higher heating value is experimentally determined in a bomb calorimeter. The combustion of a stoichiometric mixture of fuel and oxidizer (e.g., two moles of hydrogen and one mole of oxygen) in a steel container at 25° is initiated by an ignition device and the reactions allowed to complete. When hydrogen and oxygen react during combustion, water vapor is produced. The vessel and its contents are then cooled to the original 25°C and the higher heating value is determined as the heat released between identical initial and final temperatures. When the lower heating value (LHV) is determined, cooling is stopped at 150°C and the reaction heat is only partially recovered. The limit of 150°C is an arbitrary choice. Relation between heating values The difference between the two heating values depends on the chemical composition of the fuel. In the case of pure carbon or carbon monoxide, the two heating values are almost identical, the difference being the sensible heat content of carbon dioxide between 150°C and 25°C (sensible heat exchange causes a change of temperature. In contrast, latent heat is added or subtracted for phase transitions at constant temperature. Examples: heat of vaporization or heat of fusion). For hydrogen the difference is much more significant as it includes the sensible heat of water vapor between 150°C and 100°C, the latent heat of condensation at 100°C, and the sensible heat of the
  14. 14. condensed water between 100°C and 25°C. All in all, the higher heating value of hydrogen is 18.2% above its lower heating value (142 MJ/kg vs. 120 MJ/kg). For hydrocarbons the difference depends on the hydrogen content of the fuel. For gasoline and diesel the higher heating value exceeds the lower heating value by about 10% and 7% respectively, and for natural gas about 11%. A common method of relating HHV to LHV is: HHV = LHV + hv x (nH2O,out/nfuel,in) where hv is the heat of vaporization of water, nH2O,out is the moles of water vaporized and nfuel,in is the number of moles of fuel combusted. Most applications that burn fuel produce water vapor, which is unused and thus wastes its heat content. In such applications, the lower heating value is generally used to give a 'benchmark' for the process; however, for true energy calculations the higher heating value is correct. This is particularly relevant for natural gas, whose high hydrogen content produces much water. The gross energy value is relevant for gas burned in condensing boilers and power plants with flue- gas condensation that condense the water vapor produced by combustion, recovering heat which would otherwise be wasted. Biogas Biogas consists of about 2/3 methane (CH4), 1/3 carbon dioxide (CO2) a little hydrogen sulphide (H2S) and a little hydrogen (H2). It is created by the decomposition of manure and other forms of organic waste from industry or households in anaerobic (that is oxygen free) tanks where it is heated. In the reactor a biological decomposition takes place where the bacteria are producing biogas. The biomass stays in the reactor for about 2-3 weeks. Biogas can be used for production of heat and electricity. Biogas is created naturally by the decomposition of organic matter; one example in the natural world is from moors where marsh gas is created. It is possible to use about 65% of the energy available in biogas: 30% for electricity, 35% for heat This process has a loss of about 35%: 20% for the heating of the biomass 15% engine loss In principle any kind of organic material can be transformed for biogas. But if the biogas plant is supposed to be profitable with the current energy prices there should be used; manure (slurry) from the agriculture, sludge from cleaning of waste water, plants and waste from the food industry. Manure is the main ingredient – waste is an additive that increases the production. Pure waste material produces too much gas and thereby foam which destroys the gas (it has to be separated first). There are two kinds of different biogas plants in Denmark: common plants and farm plants. Common plants receive manure from industry and households. In Denmark the first common plant was inaugurated in 1984 and today there are 20 common plants. The gas that these plants produce can be sold to local CHP units
  15. 15. that generate electricity and heat. A farm plant uses only waste material from a single farm, but also uses manure as material. In Denmark the first farm plants were build after the energy crisis in the 1970ies, today there are about 60 plants running or under construction. Biomass In recent years, environmentalists and policymakers have struggled to evaluate the merits of various biomass resources. This has posed an enormous challenge, in part, because biomass brings together a host of environmental disciplines, including air, water, land-use, climate, and energy. Since few people have expertise in all of these areas, the full range of environmental impacts – both positive and negative – are not as readily apparent for biomass as they are for solar, wind, or traditional fossil resources. As a result, environmental groups, large and small, approach the topic of biomass with exceeding caution despite the fact that biomass has the potential to be one of the few carbon-neutral and renewable energy resources that is available on demand and has large-scale, commercially viable applications. Biomass electricity generation, or biopower, is a multi-stage process that converts non-fossil fuel-derived organic material into electricity. Biomass can also be used to produce fuels – biofuels – that can be used in vehicles. Because the vegetation that is the base for all biomass can be regrown, biopower and biofuels can be renewable. This means that biopower and biofuels can help reduce our dependency on fossil fuels and nuclear power. If the biomass is regrown, then it will sequester all of the carbon dioxide released when the biomass is burned. This means that biopower and biofuels can help reduce the risks of climate change. Furthermore, since biomass can be stored and burned when needed, biopower can be available on demand, unlike wind and solar which are only available when the wind blows and the sun shines. A 1997 Energy Innovations report from a group of environmental organizations forecasts that by 2030 with proper incentives, biomass could provide more than half of all renewable energy in our economy and over 15% of all our energy needs. However, in order for the United States to reduce its greenhouse gas emissions and create a sustainable energy industry, biomass companies must substantially increase their market share of electric generation. Unfortunately, the biomass industry operates under a dark cloud that seriously impairs its ability to meet this challenge. This is due, in large part, to the poor environmental record of the incineration of municipal solid waste (MSW), a highly suspect category of materials that can be laced with deadly toxins that are emitted into the air when burned. Unfortunately, MSW is often considered to be a form of biomass, a cause of great concern for environmental and public health interests who would prefer to focus the developmental potential of this technology on the many clean and renewable organic alternatives. In addition, the negative environmental impacts of factory farms, poor forest management, and large-scale agribusiness have compounded the pessimism surrounding America’s biomass industry. Biomass developers have done little to alleviate this problem, as many fail to adequately distinguish sustainable projects from their toxic siblings.
  16. 16. Cement and its application Cement in general, adhesive substances of all kinds, but, in a narrower sense, the binding materials used in building and civil engineering construction. Cements of this kind are finely ground powders that, when mixed with water, set to a hard mass. Setting and hardening result from hydration, which is a chemical combination of the cement compounds with water that yields submicroscopic crystals or a gel-like material with a high surface area. Because of their hydrating properties, constructional cements, which will even set and harden under water, are often called hydraulic cements. The most important of these is. Applications of cement Cements may be used alone (i.e., “neat,” as grouting materials), but the normal use is in mortar and concrete in which the cement is mixed with inert material known as aggregate. Mortar is cement mixed with sand or crushed stone that must be less than approximately 5 mm (3 /16 inch) in size. Concrete is a mixture of cement, sand or other fine aggregate, and a coarse aggregate that for most purposes is up to 19 to 25 mm (3 /4 to 1 inch) in size, but the coarse aggregate may also be as large as 150 mm (6 inches) when concrete is placed in large masses such as dams. Mortars are used for binding bricks, blocks, and stone in walls or as surface renderings. Concrete is used for a large variety of constructional purposes. Mixtures of soil and portland cement are used as a base for roads. Portland cement also is used in the manufacture of bricks, tiles, shingles, pipes, beams, railroad ties, and various extruded products. The products are prefabricated in factories and supplied ready for installation. Because concrete is the most widely used of all construction materials in the world today, the manufacture of cement is widespread. Each year almost one ton of concrete is poured per capita in the developed countries. Plaster of paris Plaster is a building material used for coating walls and ceilings. Plaster is manufactured as a dry powder and is mixed with water to form a paste when used. The reaction with water liberates heat through crystallization and the hydrated plaster then hardens. Plaster can be relatively easily worked with metal tools or even sandpaper. These characteristics make plaster suitable for a finishing, rather than a load-bearing material. The term plaster can refer to gypsum plaster (also known as plaster of Paris), lime plaster, or cement plaster. Gypsum plaster, or plaster of Paris, is produced by heating gypsum to about 300 °F (150 °C): 4CaSO4·4H2O + Heat → 4CaSO4·H2O + 3H2O (released as steam) When the dry plaster powder is mixed with water, it re-forms into gypsum. The setting of unmodified plaster starts about 10 minutes after mixing and is complete in about 45 minutes; but
  17. 17. not fully set for 72 hours.[3] If plaster or gypsum is heated above 392°F (200°C), anhydrite is formed, which will also re-form as gypsum if mixed with water. A large gypsum deposit at Montmartre in Paris led "calcined gypsum" (roasted gypsum or gypsum plaster) to be commonly known as "plaster of Paris". Plasterers often use gypsum to simulate the appearance of surfaces of wood, stone, or metal, on movie and theatrical sets for example. Nowadays, theatrical plasterers often use expanded polystyrene, although the job title remains unchanged. Plaster of Paris can be used to impregnate gauze bandages to make a sculpting material called modroc. It is used similarly to clay, as it is easily shaped when wet, yet sets into a resilient and lightweight structure. This is the material that was (and sometimes still is) used to make classic plaster orthopedic casts to protect limbs with broken bones, the medical use having been partly inspired by the artistic use (see orthopedic cast). Set modroc is an early example of a composite material. Lubricant The substance used between contact surfaces of moving parts to reduce friction and to dissipate heat is termed as lubricant. A lubricant may be oil, grease, graphite, or any substance—gas, liquid, semisolid, or solid—that permits free action of mechanical devices and prevents damage by abrasion and “seizing” of metal or other components through unequal expansion caused by heat. In machining processes (e.g. UNICORN automotive lubs) lubricants may also function as coolants to forestall heat-caused deformities. Types of Lubricants UNICORN brand Lubricants can be classified into four main types: v Automotive Lubricants v Marine Lubricants v Industrial Lubricants and v Specialty Products In today’s world, most lubricants are derived from mineral oils, such as petroleum and shale oil, which can be distilled and condensed without decomposition. Synthetic lubricants, like UNICORN Ultrasynt Brand lubricants are of great value in automotive applications involving extreme temperatures. In certain types of high-speed machinery films of gas under pressure have been successfully used as lubricants.
  18. 18. Application of UNICORN Brand Lubricants For the increasingly varied modern industrial requirements, UNICORN offers a wide range of selection for lubricants, differing widely in viscosity, specific gravity, vapor pressure, boiling point, and other properties. UNICORN brand lubricants efficiently replace dry friction with either thin-film or fluid-film friction, depending on the load, speed, or intermittent action of the moving parts. Thin-film lubrication, in which there is some contact between the moving parts, usually is specified where heavy loads are a factor. In the case of our fluid or thick-film lubrication, a pressure film is formed between moving surfaces and keeps them completely apart. But this type of lubrication cannot easily be maintained in high-speed machinery and therefore is recommended for use where reciprocating or oscillating conditions are moderate. Application method is highly significant for efficient operation of machinery. For most machinery, different methods of lubrication and types of lubricants must be employed for different parts. For example, in an automobile the chassis is lubricated with grease, the manual transmission and rear-axle housings are filled with heavy oil, the automatic transmission is lubricated with a special-grade light oil, wheel bearings are packed with a grease that has a thickener composed of long fibers, and the crankcase oil that lubricates engine parts is a lightweight, free-flowing oil. Grease lubricants are semisolid and have several important advantages: They resist being squeezed out, they are useful under heavy load conditions and in inaccessible parts where the supply of lubricant cannot easily be renewed, and they tend to form a crust that prevents the entry of dirt or grit between contact surfaces. It may be applied in various ways: by packing enclosed parts with it, by pressing it onto moving parts from an adjacent well, by forcing it through grease cups by a spring device, and by pumping it through pressure guns. Solid lubricants are especially useful at high and low temperatures, in high vacuums, and in other applications where oil is not suitable; common solid lubricants are graphite and molybdenum disulfide. Corrosion Corrosion is a general term used to describe various interactions between a material and its environment leading to degradation in the material properties. • Interaction with ambient oxygen can cause the formation of oxide layers via diffusion controlled growth. These may passivate the material against further oxidation. • In a wet environment, aqueous corrosion can occur due to electrochemical processes which depend upon metal ion transport and reaction. Gradients of metallic and electrolytic ion concentrations, temperature, ambient pressure, and the presence of other metals, bacteria, or active cells, all influence the corrosion rate. • Electric fields applied to corroding systems can accelerate or inhibit the rate of corrosion or material deposition. Galvanic corrosion between different metals in an aqueous
  19. 19. environment is due to the electric field arising from the different electrode potential of the two materials. External fields may enhance or supress this corrosion. • In all of these reactions, electron and ionic transport occurs. The following sections will be concerned with these processes and the effect of conditions on the corrosion rates.

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