ABSTRACT INTRODUCTION. Gabriel Filgueiras. Centrais Ele;tricas Brasileiras S.A. ELETROBRAS Rio de Janeiro, Brazil

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1 ENERGETIC CONCEPTION FOR DISTILLERIES OF ETHYEHC, ANHYDROUS OR POTABLE ALCOHOL, WITH SIMULTANEOUS PRODUCTION OF LIQUID CARBURANT, BIOFERTILIZER AND ELECTRICAL ENERGY Gabriel Filgueiras, Centrais Ele;tricas Brasileiras S.A. ELETROBRAS Rio de Janeiro, Brazil ABSTRACT A new concept of processing in the autonomous distillery of ethyl-alcohol looks at a better utilization of the energy that exists in sugarcane, making the production of the following possible from one ton of cane liters anhydrous alcohol kw energy for sale k of biofertilizers (dry material) This new concept utilize techniques already developed separately but which were now set up jointly, to allow distillery operation for the whole year even if the crop is seasonal. INTRODUCTION Petroleum crisis in 1973 and 1979, haqe caused the increase in prices, through successive reactions wh~ch seem endless. Consequently, technicians from all over the world devoted time to analyze possible solutions to solve the problem of finding replacements for gasoline and fuel oils derived from fossils. As the crop which provides a larger tonnage of carbon per hectare, sugarcane is one of the greatest potential source of fuel. Superficial examinations of the processes presently used in Brazil, show that they are similar to that utilized 40 years ago when we established the first anhy-, drous alcohol distilleries with imported equipment. It is easy to understand that the energy utilization of sugarcane could be more useful if we broke off with the existing conventions and adopt modern mwcepts and technology for better output and lower level of environment pollution. This is the line we decided to take for the conception of a project that 2607

2 2608 BY PRODUCTS could integrate known processes. Manufacturing units that utilize sugarcane as raw material could produce fertilizers, besides ethyl alcohol, from the recycling of the organic materials that comes from photosynthesis and the mineral salts from the soil. And yet electrical energy favoring the electrification of the areas surrounding the distillery and consequently, leading to the economics of the electrical energy distributing companies, obviating the implantation of supplier trunks. Finally, these manufacturing units could collaborate for the solution of rural sanitation problems of the people around the distillery. The period of sugarcane harvest in the majority of the Braz~lian areas is only 160 to 190 days a year so the production of alcohol consumed with carbofurant should be increased to assure its supply throughout the year. This is made possible by doubling the necessary tonnage for the daily production of alcohol in the extraction of the total sugar. The other part not used in the day was converted to inverted syrup and storea for later use during off season. Another solution would be to improved the index of the sucrose extraction. Use 2 rotary-knives and one defibrizer which would reduce the cane to one structure with 90% of the open-cells assuring extraction of at least. 97% of the total suqar available in the diffuser Consequently, the bagasse which comes from the diffuser, with 85% humidity, would pass through a dewater Rols, which would reduce the humidity to 65%. Bagasse under such humidity levels would be conducted to a series of biodigesters together with the rotary cake filter from the decanted juice. All the industrial sanitary sewage and even the residue of the manufacturing unit through an anaerobic fermentation, were transformed into the following products, (per ton of the cane utilized) : - 40m3 of biogas (equal to zoom3 of biogas per ton of bagasse in dried material basis); kg of biofertilizer (with 60% of humidity) which allow a recycling of the organic material and all the mineral salts extracted from the soil by the cane itself. This way, neither would we destroy the organic material, nor deposit the mineral salts within the boilers, if we would not burn the bagasse, according to the world wide conventional practice. Such a system will allow the production of biofertilizer which will be used in the renovation of the cane soil which, has become unfertile due to traditional harvest practices. According to the proposed technology, the cane will be harvested with harvesters, without burning the cane. Its leaves and tops will be harvested, disintegrated and conducted to the biodigesters up to a quantity which may reach 350kgl TC which in turn will produced 250m3 of biogas per ton of volatile solids. This basically cellulosic material produces more biogas than cane bagasse. It should be kept in stock for use during the off-season.

3 G. FILGUIRAS 2609 The cane syrup frw the diffuser is treated, decantedand concentrated at 22"Brix in a pre-evaporator which would be heated by the exhaust steam from the turbines (back pressure = 1.5kg/cm2) generating steam and which are conducted to the column A column of the stillage distillation of the distillery. Half of the vqlume of the treated and decanted syrup is carried to an evaporator quadruple-effect where the 22"Brix is raised up to 55'Brix. Through enzyme invertase, the enrolling of the saccharose is then processed until the syrup has less than 20% of the sugar to avoid crystallization. At this time, the concentration of the syrup already changed to 85" Brix, still remains. We may cool and keep it in stock for use in the off-season without running the risk of losing the total sugar contents by fermentation. The other half of the volume of the syrup daily extracted, conducted to the fermentation room. A wine with more than 8% of ethyl alcohol is obtained at the end of that biochemical process. This wine is centrifuged to recover the yeast cells which came back to the recirculation in the distillery; and the clean wine is pumped to the same column A of the distillery. The residue of the distillation is the stillage which, when cooled in the heat inter-exchanger, is conducted to a biodigester and produces around 31m3 of biogas per cubic meter of stillage. This biogas has calorific power of around 6000K cal m3. The volume of the stillage is, at least, 12.5lliter of the alcohol produced. So, we have three sources of biogas: the first is the bagasse and filter-cake; second, the cane leaves and its tops; and third, the stillage. The biogas is produced in quantities sufficient to generate steam and electrical energy, for all the processes. It also has a surplus of 1 lokw of electrical power per ton of cane utilized. The liquid effluent of the anaerobic fermentation of the stillage is, in turn, concentrated at 60" Brix an equipment named "Quadruple-vertical-effect of descendent film" utilizing as heating agent, steam from several distillery columns, i.e, "A", already mentioned above and the other "B", "C" and "D" With the heat's change between the column's steam and the effluent of the stillage, it becomes unnecessary to utilize conventional condensers, reducing the refrigeration water consumption. The solid effluent of the stillage is added to the soild effluent of the anaerobic fermentation of bagasse and is distributed in the field, as a rich biofertilizer. The leaves and tops collected in the field are carried to the packing section and stocked to be used as raw material in the bagasse biodigesters during the offseason. The amount of leaves plus tops studied during the off-season is so calculated to assure continuous operation of the biodigesters. 11 With this technology during the off-season, we will use the inverted syrup as raw material for the production of alcohol, the leaves, tops and the stillage for biogass using a process as energetic at that time even though it demands steam and power in few quantities. Nevertheless, it will result to large electrical capacity that

4 could be sold to the electrical energy distribution concessionaires. Besides this biofertilizers for recycling in agriculture will also be produced. The sewage of industrial and agricultural workers living near the distillery will be added to the bagasse and leave digesters as activator for the anaerobic fermentation. This will result to the elimination of the pathogenic germs. The biogas obtained (CHq and C02) could be utilized in several different ways and with different energy productivities. They are as follows: a) direct burning in boilers with thermal efficiency of 90% when the bagasse (with 50% humidity) would reach 65% humidity at the utmost; b) burning biogas in turbines of combined cycle, producing usually twice the electrical energy, besides, of course, of the low pressure of the steam (1,5,kg/cm2) which is necessary for the industrial process, In the last option, we may get the following as final products of thisltechnology : f { I I - 75 liters of alcohol/ton of cane utilized; - 1 lokw electrical energyrc - 440kg of biofertilizer/tci with organic material, mineral salts and % of water. Aside from the above-mentioned output of the technology, environmental pollution is almost avoided and the rural sanitation of the residents in the vicintty of the sewage system of the enterprise is assured. Countries which depend on petroleum may be supplied w~th l~quid fuel In the form of ethyl alcohol, for rut'al and transportation purposes, by mainly ut~lizing sugar-cane as raw-material. In this new processing concept for setting up an ethyl alcohol distillery, we take advantage of the total energy the cane besides alcohol. Electrical energy wih be produced for rural energization or for the citles and the next villages. Biofertilizers can also be produced by economizi~g foss~l fuels in both cases,biogas may be utilized for cooking, heating and power at home. I It also looks at the recyciing of the sanltary sewage of the manufactur~ng unlt dllow~ng for the installat~on of the pldnt w~thout pollut~ng any area whlch produces cane sugar

5 CONCEPT0 ENERGICO PARA DESTILLERIAS DE ALCOHOL ETILICO ANHYDRO 0 POTABLE, CON PRODUCCION SIMULTANEA DE LIQUID0 CARBURANTE, BIOFERTILIZANTE, Y ENERGIA ELECTRICA. Gabriel Filguiras RESUMEN Nuevo concepto para el procedimiento en el Destilo Autonomo de Alcohol Etilico, que busca la mejor utilization de la energia que existe en caila de azucar, haciendo posible la produccion de un TC: I - Alcohol Anhydro 75 litros (como combustible) kw (para venta) k de bbfertilizantes (materia seca) En este nuevo concepto, se utilizaron tecnicas ya desarrolladas, sepafadamente, y ahora instituidas juntamente, todaviapermitiendo que la destileria funcione todo el aiio dentro de un gran control de arnbiente, aunque la cosecha de cafla sea de temporada o de epoca.