coal-methanol fuel 5c

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Coal-Methanol FuelGroup 5Evangelista| Magtoto|Reynoso|Rosuelo

Green Boiler Technology: Coal-Methanol Fuel Group5

COALOne of the most abundant sources of energy, more so than oil and natural gasCoal is inexpensive when compared to other fossil fuels (or alternative energy sources)Burning coal can produce useful by-products that can be used for other industries or productsProduces carbon dioxide when burned compared to burning oil or gasGives off sulfur dioxide, a kind of gas that creates acid rainOILEasier to extract from the ground through the use of pipesEasily combustible, and produces high energy upon combustionCauses pollution and poses environmental hazards


MethanolHas technical advantages over other gas turbine fuelsCreates fewer pollutantsMay be a potential standby fuel for gas turbines during fuel supply disruptionsA combination of technical and cost factors prevent the widespread use of coal and methanol mixtures as boiler fuel.Extremely costlyLower thermal efficiency than other boiler fuels


Types of Coal SlurriesCoal-Oil Mixtures (COM)Coal-Oil-Water (COW)Coal-Water-Oil (CWO)Coal-Water Fuels (CWF)Coal-Methanol Fuel (CMF)Coal-Methanol-Water (CMW)


Coal-Methanol Fuel (CMF)Suspension of coal in methanolPossess favorable propertiesThe cost of methanol has all but eliminated them from further developmentMethacoal process are low, and the slurry need not be separated before combustion.


Specific Boiler Used

The study indicated that the overfiring process can achieve an effective reduction of NO, emissions in residual oil-fired boilers. It also indicated that methanol was more effective than natural gas in reducing NOx emissions when used as a secondary fuel in boiler reburning systems.


Sources: Coal:Mined coal available for or delivered to a processing plant. Many operations will subject the mined coal to sizing and pre-cleaning with screening systems or rotary breakers prior to delivery to processing plants.


Manufacturing:



ProcessCoal PreparationCoal GasificationGas Cooling and Particulate RemovalProduction of MethanolRaw Gas CompressionGas Shift ConversionAcid Gas RemovalMethanol Synthesis and PurificationSulfur RecoveryOxygen Production


Coal preparationThe coal is first crushed and then dried it will proceed to the gasifier.Particle size (3/8 x0)Fluid bed dryer


Coal GasificationThe gasifier is maintained as a fluidized bed operation under moderate pressure. A mixture of steam and oxygen is injected at several points within the bed to gasify the coal while steam alone is injected into the bottom most level to fluidize the coal and to cool the larger ash particles discharging from the gasifier bottom.The unreacted carbon in the discharged ash is a function of gasifier temperature and coal reactivity. Generally, reactivity varies inversely with geological age, lignites being the most reactive.


The primary coal gasification reactions are:C + O2 CO2 (EXOTHERMIC)C + .5O2 CO (EXOTHERMIC)C + CO2 2CO(ENDOTHERMIC)C + H2O CO + H2(ENDOTHERMIC)C + 2H2O CO2 + H2(ENDOTHERMIC)


Gas cooling and Particulate RemovalThe hot gases leaving the generator pass through the heat recovery train where heat is removed from the gas by generating and super-heating high pressure steam and preheating boiler feedwater.In combination, the heat recovery train and cyclones are designed to remove approximately 85% of the entrained solids. The char thus removed will be utilized as supplementary fuel in the boiler house.


Raw Gas compressionThe cooled and the dust free gas from the coal gasification section is compressed to 1480 psig in steam turbine driven compressors.


Gas shift conversionThe purpose of the shift conversion step is to adjust the ratio of carbon monoxide to hydrogen to that required for the methanol synthesis according to the exothermic shift reaction:CO + H20 = C02 + H2The compressed gas to the shift reactor is mixed with the shift reaction steam to give a 1.0 ratio of steam to the dry gas and preheated by heat exchange with the hot effluent gases from the shift reactor prior to its introduction to the reactor which contains a sulfur resistant catalyst. From the interchanger, the shift effluent is cooled in a series of waste heat recovery exchangers.


Acid RemovalThe Rectisol process has been selected to remove the acid gases as it has the advantage of using the plant product as the scrubbing medium.


Methanol Synthesis and PurificationThe unique feature of this process is the synthesis step, utilizing a copper based catalyst specially developed by ICI, which gives good yields of methanol at low temperatures (410F to 520'F).Final traces of sulfur are removed from the synthesis gas by a bed of zinc oxide after preheating to desulfurization temperature.The feed gas and the cold shot gas combine and react to form methanol as they pass downwards over the catalyst. The converter exit gas is first cooled in the converter interchanger and subsequently in the crude methanol condenser where the crude methanol product is condensed.


Methanol Synthesis and ProductionThe non-reactive components of the make-up gas, methane and nitrogen are purged from the synthesis loop between the separator and the point of makeup gas addition and are subsequently used as boiler fuel.The crude methanol collected in the separator is let down in a single stage to the let down vessel and the resultant product passes to the distillation plant.Flash gas from the letdown vessel (mostly dissolved gases) is mixed with the synthesis loop purge stream and used as fuel.The crude methanol is processed in a single column system to fuel grade methanol, and the overall efficiency of the distillation system is expected to be 99% at the end of life conditions.


Market Prices


Current Market Prices


Current Market Prices


Fuel Characteristics


Fuel Characteristics (Methanol Fuel)Burn at low temperatureHas a high heat of vaporizationLow energy content of 19.7 MJ/kg andstoichiometricair-to-fuel ratio of 6.42:1 mean that fuel consumption (on volume or mass bases) will be higher than hydrocarbon fuels.Contain soluble and insoluble contaminantHygroscopic, meaning it will absorb water vapor directly from the atmosphere


Fuel Characteristics Characteristics of coal mixtures is more complex than its coal because other than the physico-chemical characteristic of its original coal, the behavior of these coal mixtures with water/oil has to be understood through the science of rheology.Burning coal mixtures in a furnace is achieved by spraying or atomizing


Fuel Characteristics (Viscosity)Viscosity is the most important characteristic in the storage and use of fuel oil. It influences the degree of pre-heat required for handling, storage and satisfactory atomization. If the oil is too viscous, it may become difficult to pump, hard to light the burner, and tough to operate. Poor atomization may result in the formation of carbon deposits on the burner tips or on the walls. Therefore pre-heating is necessary for proper atomization.


Fuel Characteristics (Coal Concentration)For combustion, a good coal mixture shall have high coal concentration because an existence of water will increase heat losses for water evaporation. However, high coal concentration will increase viscosity of the coal mixture and in turn will create difficulties in handling and atomizing the coal mixture.


Fuel Characteristics (Particle Size)Particle size is especially important for it can have an effect on the reliability of automatic feeding systems as well as on the combustion efficiency of the boiler. It has a direct effect on the cost of the energy generated, and on the good running of the heating appliance.


Coal-Methanol Combustion By-Products


Coal-Methanol Combustion By-ProductsFly Ash a non-combustible powdery inorganic matter produced from burning coal


Coal-Methanol Combustion By-ProductsBottom Ash by-product formed in furnaces


Coal-Methanol Combustion By-ProductsBoiler Slag often used as a wear-resistant component in surface coatings of asphalt in road paving.


Coal-Methanol Combustion By-ProductsGypsum product of the flue gas desulfurization process known as scrubbing


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coal-methanol fuel 5c

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