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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Energetic Analysis of Hydrogen Production in a Sugar-Ethanol Plant / Energetisk analys av vätgas produktion i en socker-etanol anläggning

Roberts, Justo January 2011 (has links)
In the present work it is evaluated the possibility of incorporating the production of hydrogen through the steam reforming of ethanol in a sugar-alcohol plant. The analysis is made using as a model an existing plant located in São Paulo, the Pioneros Distillery. An energetic and exergetic analysis is performed. Three operating scenarios were analyzed. In the first configuration the plant only generates electricity to supply its internal needs. In a second scenario the plant uses all the bagasse to generate electricity, targeting to sell electric power. Finally it was considered the possibility to incorporate the hydrogen production by ethanol steam reforming. The capacity of the plant to produce hydrogen is evaluated. The surplus bagasse is used to generate the electricity and thermal energy required for hydrogen production. A part of the anhydrous alcohol is used in the reformer for hydrogen production. An energetic study of the plant is developed based on the first law of thermodynamics. Some important parameters related to the thermal system performance are evaluated like: steam consumption in the process, specific consumption of steam turbines; and those properly related to plants of sugar-ethanol sector as: electrical or mechanical power generated from one ton of sugarcane and power generated from a given amount of bagasse burned in the boiler. It is considered the possibility of generating electricity using bagasse, which could be sold to the local energy concessionaire. Characteristic parameters of a cogeneration system (α and β) are also evaluated, these parameters depend on the characteristics of the thermodynamic system and the operating strategy. The system energy losses, excluding those located in the boiler and the electric generator, are higher in scenario 2 than in scenario 1. The efficiency is 70% in Scenario 1 and 57% in scenario 2. In scenario 3, the plant's potential for hydrogen generation is 4,467,000Nm3/year (951Nm3/h). To achieve this, the new process uses 7 % of the anhydrous ethanol produced in the plant, which implies a surplus of 37 lethanolanhydro/tcane available for sale. In this configuration all the bagasse is used for electricity and heat generation required for the hydrogen production. The hydrogen could be used for fuel cell vehicles. The plant is able to supply 68 buses with autonomy of 200 to 300 km per day. The incorporation of the hydrogen production process by steam reforming represents an attractive alternative to the sugar-alcohol sector.
2

Ecological and Exergetic analysis of Hydrogen Production in a Sugar-Ethanol Plant / Ekologisk och exergetisk analys av vätgasframställning i en socker-etanol anläggning

Colombaroli, Tulio January 2011 (has links)
This work aims an ecological and exergetic analysis of the hydrogen production by steam reforming of part of the ethanol produced in a sugar-ethanol plant. The Pioneiros Distillery, located in São Paulo, is used as model for this study. Three cases are described. In case 1 the plant produces energy only for domestic needs. A part of bagasse is not burned and it is stored. In Case 2, all available bagasse is used for production of steam. Part of the steam is used in the production process meeting the demand of the plant and the rest of steam is converted into electrical energy that can be sold at concessionaires. In Case 2 it is produced more energy than in Case 1. Case 3 includes the production of hydrogen by steam reforming of a part of the produced ethanol. Steam and energy for steam reforming is generated from combustion of bagasse. An exergetic analysis is performed. The exergy flows associated with the sugar-ethanol plant are calculated locating and quantifying the losses and irreversibility.  The ecological impact of use of the bagasse as fuel to generate thermal and electrical energy for the ethanol reformer was studied. The main pollutants that damage the atmosphere, namely: CO, CO2, NOx and PM have been taking into account. Carbon Dioxide emissions were calculated taking into account the carbon cycle (considering the absorption of carbon dioxide by the sugarcane during its growth), resulting in negative balance emissions, i.e., carbon dioxide was absorbed in higher amounts than emitted. The thermodynamics (ηsystem) and ecological (ε) efficiencies of Steam reforming of ethanol were calculated. The thermodynamic efficiency was 56% and the ecological efficiency was 80%. When the carbon cycle is taking into account the ecological efficiency is 90%. The incorporation of an ethanol reformer in a sugar-ethanol plant for hydrogen production is a very interesting option where environmental benefits are obtained. Problems related with the storage of bagasse are avoided because all the bagasse is burned for the production of steam and energy to the reformer. The amount of hydrogen that can be produced in Pioneiros Distillery could supply fuel for 68 buses with a range from 200 to 300 km per day.

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