The Design Consideration of the Biomass Plants - Assignment Example

Name Subject Name of Instructor Institution Date Biomass technology Biomass has taken the enormous trend in the current world as an alternative source of electricity. The availability of common products that are used in its power generation makes it to take a centre stage in the acquisition of this approach. Electricity is consumed in virtually all realms of the industrial sector. It is unfortunate that the main source of electricity has been water, coal and to some extent nuclear [2]. However, this approach poses to be expensive and at times unpredictable due to the weather changing patterns. It is with this perspective that we have decided to come up with the alternative source of electricity, with biomass being the main source of power. The design consideration of the biomass plants are as stipulated below. Design details There is a collector that may be used to produce the gas from the available recyclable materials such as, wood, animal waste, rice husks grass and tree leaves. The collectors have the parameters as indicated below. Diagram 1 Vc= The volume of gas collecting chamber Vgs= The volume of the storage chamber Vf=Volume of the fermentation chamber VH= Volume of the hydraulic chamber Vs= Volume of the sludge The total volume of the digester may be obtained by V= Vc+ Vgs+ Vf+ Vs There are a number of assumptions that would be considered in the design consideration The value of Vc  Vs Vgs +Vf=80%V Vgs=VH Vgs=0.5(Vgs +Vf+ Vs) k . K represents the rate of gas production in m3 at a given day The geometrical dimensions would have the values, D=1.3078*v1/3 V1=0.0827D3 V2=0.05011D3 V3=0.3142D3 R1=0.725 R2=1.0625D F1=D/5 F2=D/8 S1=0.911D2 S2=0.8345D2 Volume of the chamber The volume in the digester chamber may be ascertained from. The form of waste taken from a sample of six cows that have a weight of about 200kg and the temperature is more than 30oC. The biomass plant is designated to incorporate the fuel section, a cooling system , condensing turbine and the fluidized bed boiler. The design is aimed to have an output of 50MW. The study conducted, indicated the biomass collected from the region is sufficient to uphold this output. The project also demands lower financial capital. The fluidized bed has the capacity to hold a wide range of the biomass fuel. It has capability of holding different biomass fuels without having cases of damages. Design requirements The source of water would be from a nearby river named as Rajput [11] . The clean recycled wood, switch grass and animal waste would be used as the source of fuel. However, the main source would entail tree stumps, pallets and the tree chips. There would be the production of the gas that would be converted to electricity. The materials are brought then are fed to the gasifier feeder Due to the dry nature of these materials, there would be less need of drying which is seen to save on the capital cost of the project. Here there would be the conversion of these materials to combustible substances such as carbon monoxide, methane and hydrogen. Design specifications Magnetic separator- This would perform the action of removing any ferrous material that accidentally falls in to the biomass material. The wood hopper ensures there is continous supply of the wood chips and other materials to the Gasification design In cooperates the fuel and the ash which are contained in the process. It also has a cooling and the cleaning mechanisms. The water treatment plant ensures there is no pollution which is exhibited to the environment. There is a cylindrical reactor located throughout the system from the top to the bottom. The duration in which the mixture takes to react determines the amount of gas that has to be produced. The combustible gas has to be re-burned as it passes through the hot char [9]. This ensures that, there is sufficient cracking of the molecular compounds which have higher weight. It is noted that approximately, 75kg/hr of the gas may be affected during this process. Equations for gasification C+ CO2 2CO C+ H2O CO + H2 C+ 2H2 CH4 Design process A pressurised oxygen blower is utilised. The gas is placed it the chambers at temperatures of about 100 degrees Celsius. The gas is cooled then cleaned after which it is passed through the gas turbine in which power is generated. Exhaust gases emanating from the turbine, is incorporated with heat generated from other parts through a recovery mechanism of the heat system to generate more power. The oxygen is supplied to the system via an air integrated system added at the steam generator. Heat is directed from the rest of the system which requires cooling from the hot region areas. This brings the aspect of maximization of the efficiency that is attained by the recycling of the available products. The pinch analysis is utilised where it matches the parts which requires heating [5]. The gasifier operates at conditions which range at about thirty bars and 1000oC. The pressure is set to ensure the gas entering has sufficient amount of pressure to enter the combustible chamber. The additives may be added to the bed of the gasifier material so as to inhibit the fusion of the ash in the biomass combustors. These reactions would lead to the production of gases such as ammonia, char which is the form of unconverted carbon, hydrogen sulphide, ammonia and some form of the alkali compounds. Oxygen may be added to the free board of the gasifier that enhances tar and oil cracking to molecules which are lighter. As suggested by Barnard [5], about 92 5 of the conversion is achieved through this process. Exothermic reaction would occur making the raw material temperature to increase to about 1015oC. The cyclone would separate the unconverted char from the gas to ensure that, a clean gas is obtained. To eliminate the effect of the char, the materials would be re-circulated in the gasifier to ensure it is totally consumed. Fig 2 (Biomass production plant Michael, 2008) The plant configuration may be stated as to contain, a low pressurised fluid bed that is gasified. The heating systems also contain the gas engines. The wood pellets may be used which have moisture content of about 9.5 %. The product composition to the gas engine contains; 23.4% volume of CO, 9.9% vol of CO2, 20.71% vol of H2, 3.32% vol of H2O, 0.93 % of CH4 and 41.72 % of N2 [14]. Cooling of the gas is achieved through the steam generating gas cooler running from 900 to 200oC. The gas scrubbers use water to ensure water is cooled from 200oC to 30oC. The gas engine operates on four stoke having a capacity of about 2mWe. The tar reformers eliminate the tar and the hydrocarbons from the gases. It also ensures the gas is converted to lighter compounds which are more combustible such as hydrogen and carbon monoxide. Ammonia gas is also removed. Cleaning of the gas The leaving gas has the temperature cooled by the cooler by the gas leaving the cyclone to about 350oC. The fire tube is made to be vertical so as to facilitate the condensation of the alkali particles. After cooling the gas to about 350oC there would be condensation of the particulate matter which occurred at the suspension of matter. The temperature of the gas has to be kept to an optimum condition to avoid clogging. This also prevents the condensation of the formic acid and ammonia gas that could cause severe damage to the equipment. The gas is passed through the barrier filter which performs the function of filtering the combustor of the gas turbine. At this point the impurities and tar are entirely burnt as the gas expands towards the turbine. Air separation This ensures there is separation of gases having about 96% of the oxygen and about 98 % of Nitrogen. The oxygen undergoes a compression into three stages where it would be compressed before being directed to the gasifier. Most of the nitrogen would be directed to the atmosphere as some of it would be taken to the compressor. The nitrogen sent to the compressor ensures there is a balance which is attained between the turbine and the compressor to have high amount of power output. To efficiency purposes, the air separation chamber is integrated together with the turbine operation. Materials for gasifier The upper section is made of the lined carbon steel shell which has refractory properties. The lower region is fitted with the boiler which is annular. The lower section is made of the mild steel and has the feeders through which the raw gas takes off to the man hole. The inner section has refractory material having insulation. The fuel feeders have a gap that allows the disengagement of the gases. The four pokes are located at the top plate so as, the rods may be inserted and the bed condition may be ascertained. The gasification section is made of mild steel and also has pipes that circulate the hot water to the steam drums where it is flushed off. The pressure released may reach 172Kpa. The grate allows the ash to be disposed off from the reaction region. References [1] B, Jonathan. Well Completion Design. Amsterdam, Netherlands: Elsevier, 2009. Print. [2] B , John. and H, Brunkhorst. Sources of Electricity. Santa Monica, CA: Enterprise for Education, 1991. [3] G, Ellwood. and L. Schmidt. Engineering Design. Boston: McGraw-Hill Higher Education, 2009 [4] F, Mahmud. Selection of Materials and Manufacturing Processes for Engineering Design. New York: Prentice Hall, 1989. [5] G. Barnard and L, Timberlake. Gasifiers: Fuel for Siege Economies. London: Published by International Institute for Environment and Development, 1983. [6] G, Lance. Miscanthus Hybrids for Biomass Production. Ames, IA: Iowa State University, University Extension, 2007. [7] H, Michael. Biomass Recalcitrance: Deconstructing the Plant Cell Wall for Bio-energy. Oxford: Blackwell Pub., 2008. [8] L, Chris. Os Biomas. Lisboa: Meriberica, 1988. [9] M, Johnson. Renewable and Alternative Energy as a Source of Electricity in Alberta: Report to the CASA Board. Edmonton, Alberta: Clean Air Strategic Alliance, 2005. [10] R, Rabson,. "The Role of Fundamental Biological Research in Developing Future Biomass Technologies." Biomass 1.1 (1981): 17-37. [11] R, Rajput. Engineering Thermodynamics. Sudbury, MA: Jones and Bartlett, 2010. [12] S, Sayigh. Renewable Energy: Technology and the Environment; Proceedings of the 2nd World Renewable Energy Congress, Reading, UK, 13-18 September 1992. Oxford U.a.: Pergamon, 1992. [13] T, Garrett. Chemical Engineering Economics. Van Nostrand Reinhold: New York, 1989. [14] W, Riley and D. Schell. Technical and Economic Analysis of an Enzymatic Hydrolysis Based Ethanol Plant. Solar Energy Research Institute Internal Report. Golden: CO, 1991. Read More

The combustible gas has to be re-burned as it passes through the hot char [9]. This ensures that, there is sufficient cracking of the molecular compounds which have higher weight. It is noted that approximately, 75kg/hr of the gas may be affected during this process. Equations for gasification C+ CO2 2CO C+ H2O CO + H2 C+ 2H2 CH4 Design process A pressurised oxygen blower is utilised. The gas is placed it the chambers at temperatures of about 100 degrees Celsius.

The gas is cooled then cleaned after which it is passed through the gas turbine in which power is generated. Exhaust gases emanating from the turbine, is incorporated with heat generated from other parts through a recovery mechanism of the heat system to generate more power. The oxygen is supplied to the system via an air integrated system added at the steam generator. Heat is directed from the rest of the system which requires cooling from the hot region areas. This brings the aspect of maximization of the efficiency that is attained by the recycling of the available products.

The pinch analysis is utilised where it matches the parts which requires heating [5]. The gasifier operates at conditions which range at about thirty bars and 1000oC. The pressure is set to ensure the gas entering has sufficient amount of pressure to enter the combustible chamber. The additives may be added to the bed of the gasifier material so as to inhibit the fusion of the ash in the biomass combustors. These reactions would lead to the production of gases such as ammonia, char which is the form of unconverted carbon, hydrogen sulphide, ammonia and some form of the alkali compounds.

Oxygen may be added to the free board of the gasifier that enhances tar and oil cracking to molecules which are lighter. As suggested by Barnard [5], about 92 5 of the conversion is achieved through this process. Exothermic reaction would occur making the raw material temperature to increase to about 1015oC. The cyclone would separate the unconverted char from the gas to ensure that, a clean gas is obtained. To eliminate the effect of the char, the materials would be re-circulated in the gasifier to ensure it is totally consumed.

Fig 2 (Biomass production plant Michael, 2008) The plant configuration may be stated as to contain, a low pressurised fluid bed that is gasified. The heating systems also contain the gas engines. The wood pellets may be used which have moisture content of about 9.5 %. The product composition to the gas engine contains; 23.4% volume of CO, 9.9% vol of CO2, 20.71% vol of H2, 3.32% vol of H2O, 0.93 % of CH4 and 41.72 % of N2 [14]. Cooling of the gas is achieved through the steam generating gas cooler running from 900 to 200oC.

The gas scrubbers use water to ensure water is cooled from 200oC to 30oC. The gas engine operates on four stoke having a capacity of about 2mWe. The tar reformers eliminate the tar and the hydrocarbons from the gases. It also ensures the gas is converted to lighter compounds which are more combustible such as hydrogen and carbon monoxide. Ammonia gas is also removed. Cleaning of the gas The leaving gas has the temperature cooled by the cooler by the gas leaving the cyclone to about 350oC. The fire tube is made to be vertical so as to facilitate the condensation of the alkali particles.

After cooling the gas to about 350oC there would be condensation of the particulate matter which occurred at the suspension of matter. The temperature of the gas has to be kept to an optimum condition to avoid clogging. This also prevents the condensation of the formic acid and ammonia gas that could cause severe damage to the equipment. The gas is passed through the barrier filter which performs the function of filtering the combustor of the gas turbine. At this point the impurities and tar are entirely burnt as the gas expands towards the turbine.

Air separation This ensures there is separation of gases having about 96% of the oxygen and about 98 % of Nitrogen.

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