AU2011357643A1 - Process for producing ethanol from the fermentation of sugar sources in a fermentation medium with high ethanol content - Google Patents

Abstract

The fermentation process comprises the steps of: (i) preparing a must to feed the fermentation medium containing a high sugar content, containing between 16% to 30% of TRS; (ii) cooling the must to temperatures between 8°C and 30°C; (iii) feeding the yeast cream of

Description

WO 2012/103609 1 PCT/BR2011/000038 "PROCESS FOR PRODUCING ETHANOL FROM THE FERMENTATION OF SUGAR SOURCES IN A FERMENTATION MEDIUM WITH HIGH ETHANOL CONTENT" Field of the Invention 5 The present invention refers to a process for producing ethanol from the fermentation of sugar sources in a fermentation medium with high ethanol content, especially a process for producing ethanol from the microbiological fermentation of sugars, such as sucrose, glucose and 10 fructose using yeasts, of the genus Saccharomyces sp, under controlled conditions of temperature and of high concentration of ethanol in the fermentation medium. Background of the Invention The current prior art comprises a production process in 15 which sugar sources are converted, through a high efficiency fermentation process, to ethanol. Among the carbohydrate sources which can be converted into fermentable sugars it is possible to point out: - Sources of sucrose (C 1 2

H

2 2 0 1 1 ) : sugar cane, beet and 20 sweet sorghum; - Sources of cellulosics and lignocellulosics: are ligneous compounds containing hemicellulose and cellulose, which can be chemically, or enzymatically converted to pentoses (not fermentable by Saccharomyces 25 sp) and hexoses, respectively. Examples of raw materials that can be used in this route are: ligneous materials, elephant grass fiber, sugar cane fiber, grass sorghum fiber, sugar cane or sweet sorghum straw. - Starchy sources: mainly grains and tubers. In the 30 process for converting sugars to ethanol using yeasts, more specifically the Saccharomyces cerevisiae, the sugar sources are the sucrose (C 1 2

H

2 2 0 1 1 ) or glucose and fructose

(C

6

H

1 2 0 6 ) . These microorganisms are able to convert sucrose to glucose and fructose through an exo-enzyme 35 called invertase. The equation (1) described below represents the biochemical reaction for converting WO 2012/103609 2 PCT/BR2011/000038 sucrose, glucose and fructose to ethanol. Evidently, starchy carbohydrate and lignocellulosic sources, before serving as substrates for fermentation, must be converted into fermentable sugars (hexoses) . The starchy sources 5 can be hydrolyzed by glucose, via acids/enzymes, in which the starch is converted to dextrin and posteriorly to glucose, using the alpha-amylase and glucose oxidase enzymes. The cellulose and lignocellulose sources. can be partially hydrolyzed to fermentable hexoses and to non 10 fermentable pentoses, via the concentrated or diluted acid, or via enzymes. In the case of cellulose: enzymatic cocktails based on endo-glucanase, exo-glucanase and beta-glucosidase; - to hemicellulose: hemicellulase, exo hemicellulase and xylosidase. 15 In said process, the control of fermentation enables obtaining a fermented must with high ethanol content and with high conversion of sugars to ethanol. The basic reaction (1) which expresses the biochemical conversion of sugars comprising the sucrose (C 1 2

H

2 2 0 1 1 ), 20 glucose (C 6

H

1 2 0 6 ) and fructose (C6H 1 2 0 6 ) to ethanol (C 2

H

5 OH) can be summarized as follows: (I)

C

12

H

22 0 1 1 + H 2 0 -- 2CGH 1 20 6 -- 2C 2 HsOH + 2 Co 2 + 54 kcal (1) 25 (I): invertase The first part of the reaction comprises the enzymatic conversion of the sucrose to glucose and fructose (reducing sugars) and, the second part, the biochemical 30 conversion of these sugars to ethanol and carbonic gas. As can be noted, the reaction is exothermal, in which heat is released. As previously mentioned, there are several sugar sources, but an important source of this raw material is sugar 35 cane. In the sugar cane, the predominant sugar is the sucrose, which contains approximately 99.5% of the WO 2012/103609 3 PCT/BR2011/000038 contained sugars (dry base) and, the remainder (0.5%), is basically glucose and fructose. The amount of the whole sucrose converted to reducing sugars, added to the originally contained reducing sugars, is denominated 5 total reducing sugars (TRS). Usually, the ethanol production and other process parameters are expressed as a function of this term. Brazil is the second largest ethanol producer in the world after the United States. In the 2007/2008 Brazilian 10 harvest there were processed 493 million tons of sugar cane, being produced 22.5 billion liters of ethanol (anhydrous and hydrated) and 30.7 million tons of sugar. There are basically two types of mills in Brazil, the autonomous mills, which only produce ethanol from sugar 15 cane, and the combined mills, which produce sugar and ethanol, the latter being manufactured from the juice and residual syrup (molasse) coming from the sugar manufacturing process. In the combined mills, on average, the equivalent to about 5o of the processed sugar cane 20 is destined to sugar manufacture and 50% to ethanol manufacture (anhydrous and/or hydrated) . The raw material used for manufacturing ethanol and sugar requires several processing steps. The juice destined to the ethanol manufacture undergoes a specific physical-chemical 25 treatment and is sent to the fermentation vessels, jointly with the exhausted final run-off syrup (mother liquor) resulting from the sugar manufacture. This mixture, called must, undergoes an alcoholic fermentation process, in agitated tanks (fermenters or vessels), using 30 mainly the Saccharomyces cerevisiae yeast, generating a fermented must typically containing from 6% to 11% of ethanol. As a byproduct of the fermentation process, it is further generated carbonic gas in a mass amount of 1:1 in relation to the ethanol, and the fusel oil (less than 35 1- in mass) which is separated in a posterior distillation step. The resulting fermented must is then WO 2012/103609 4 PCT/BR2011/000038 submitted to centrifugation, in which the yeast is separated and recycled, and the wine containing ethanol is sent to distillation. Subsequently, the wine is usually brought into direct contact with the steam in 5 distillation columns, generating two streams, an ethanol stream at the top and a vinasse stream at the bottom. Upon using the system of flushing the vapor directly in the column, the vapor is brought into direct contact with the wine, promoting the incorporation of condensate in 10 the vinasse, and the volume generated can be somewhat between 10 and 14 times the volume of alcohol, depending on the wine alcoholic degree. There also exists the distillation process by indirect contact, in which the generated vinasse volume is smaller, being 6 to 8 times 15 the produced ethanol volume. The mixed juice destined to sugar manufacture undergoes the operation of separating bagacillo in cush-cush type screens and/or rotary screens, being heated to about 40 0 C and is conveyed, in case of producing white sugar, to 20 sulfitation (usually in columns or hydro-ejectors) in which, by addition of sulfur dioxide resulting from the sulfur burning in the burners, has its pH reduced to about 4.0 to 4.5. After sulfitation, the juice receives the addition, of 25 lime milk (or calcium saccharate) in which the pH is elevated to about 7.0 to 7.2. The limed (or dosed) juice is then heated to about 105'C, subsequently undergoing a vaporization process (flash balloon) for removal of dissolved gases, receiving the 30 addition of a flocculating agent, usually a polyacrylamide polyelectrolyte, and is then submitted to the decantation in static decanters, with or without trays. This operation is also commonly known as clarification. 35 The clarification process generates two streams: a sludge stream and a clarified juice stream. The sludge, after WO 2012/103609 5 PCT/BR2011/000038 being added with bagacillo which is a type of a natural element, receives the addition of lime milk and, eventually, polyelectrolyte, usually a polyacrylamide, and is then filtrated in vacuum rotary filters or belt 5 press filters, thus producing the filter cake which is conveyed to the plantation site, as well as the filtrated juice which is re-conducted to the process. The obtained clarified juice is sent to evaporation in multiple effect vacuum evaporators, usually Robert type 10 evaporators with 4 or 5 stages, producing a concentrated juice known as syrup, which has a concentration of about 60-65oBrix. In the first evaporation stage, usually known as pre evaporation, it is effected the bleeding of vegetal vapor 15 (VI) used in the operations of evaporation and crystallization, heating of the mixed juice and distillation in the ethanol manufacture. There are mills that carry out the bleedings in the second and third effects, respectively called vegetal vapor V2 and V3, 20 these vapors being used for heating the juice, or even in the case of the vapor V2, for the cooking operation. The syrup obtained in the evaporation is sent to the posterior crystallization step, which is carried out in vacuum calender type evaporating crystallizers in systems 25 of two or three masses. Generally, the conventional crystallization process takes from 3 to 5 hours, and the crystal mass obtained is conveyed to horizontal crystallizers provided with a cooling jacket until reaching the ambient temperature. 30 The final mass is then submitted to a centrifugation cycle, in basket centrifuges, in which the crystals are washed upon application of water and steam and then conducted to the drying and bagging steps. The run-off syrup obtained in the centrifugation is 35 reused in the cookings for obtaining the second sugar (sugar B or magma) and, eventually, the third sugar WO 2012/103609 6 PCT/BR2011/000038 (sugar C or magma), which are also re-circulated in the first-sugar manufacturing process. The end syrup (molasse) originated in mass B in systems with two masses, or originated in mass C, is conveyed to ethanol 5 manufacture, jointly with part of the juice separated for the production of ethanol, thus compounding the must for the fermentation. The processes for fermenting sugar to ethanol can be continuous or by fed batch. In Brazil, the process 10 predominantly adopted is the fed batch fermentation. In the fed batch process, it is initially added, in the fermenter, a yeast fraction from about 8% to 15% of its useful volume. Subsequently, it is gradually added an increasing amount of must as the fermentation activates. 15 By activating the fermentation, there occurs the dissipation of heat coming from the metabolization of the sugar and conversion to ethanol and carbonic gas, by the microorganism (biochemical reaction 1). The heat removal is generally carried out through indirect thermal 20 exchange devices (heat exchanger and coils) between the must in fermentation process and the water coming from a tower or spray cooling system. In this process, the water effluent from the heat exchanger is sent to a cooling tower in which the heated water resulting from the heat 25 exchange with the fermented must receives a forced air flow. Accordingly, the water is cooled to the wet-bulb temperature of the ambient air, and returns to the cooling process of the fermenters. During the fermentation process, the total reducing sugars (TRS) in 30 the fermenter is maintained between 2% and 4% until the fermentation process is completed. The formed foam, resulting from the strong evolution of C02, is controlled through the addition of an antifoaming agent. The process is finished when the useful volume of the fermenter is 35 completed and the TRS is substantially exhausted, taking about 6 to 12 hours on average.

WO 2012/103609 7 PCT/BR2011/000038 The continuous fermentation system consists of agitated vessels connected in series, so that the must and the yeast are generally fed in the first stage and, in the outlet of the last reactor of the series, the TRS being 5 maintained in substantially zero values. In the same way as in the fed batch fermentation, the cooling of the fermenters occurs through the indirect thermal exchange devices, connected in each stage, the cold fluid coming from a spray system or cooling towers, which basically 10 comprises evaporative cooling at ambient temperature. In these systems, which operate using cooling water coming from cooling towers or sprays, at the end of the fermentation process, an alcoholic content in the fermented must is obtained, generally between 6.0 and 15 8 0 GL for non-optimized processes and from about 8.5 to ll 0 GL for well-optimized and controlled processes. The fermented must is then sent to centrifugation for separation of the yeast from the wine, the concentrated yeast ("yeast cream") being sent to an agitated tank in 20 which it frequently receives an acid treatment (based on sulfuric acid) and then re-used again in the process. The resulting wine is sent to distillation, in which the contained ethanol is recovered in its anhydrous and hydrated form, generating from about 5 to 14 L of 25 vinasse/L of produced ethanol. In the fermentation process and posterior distillation, the higher the alcoholic content, the better the performance of the posterior steps, since there is a higher production of ethanol by reactor volume, higher amount of ethanol 30 produced by distillation column volume, reduction of vapor consumption in the distillation and reduction of the generated vinasse volume. There are variants of the process in which part of the generated vinasse is returned to the fermentation process and used for 35 preparation of the must. The amount to be re-circulated evidently depends on the medium osmotic pressure, which WO 2012/103609 8 PCT/BR2011/000038 is the factor that limits the amount to be re-circulated. In case of a high amount, it can drastically affect the performance of the yeasts and impair, therefore, the alcoholic fermentation process. Typically, the re 5 circulation rates range from about 20% to 60% of the generated volume. Generally, in order to guarantee good conversion rates from sugar to ethanol, several factors must be controlled in the fermentation process, such as raw material 10 quality, sugar cane cutting time, impurity amount, contaminants, sugar cane juice treatment, process asepsis, yeast quality, yeast concentration, pH, nutrient complementation and, mainly, temperature of the medium in fermentation process, which must be typically maintained 15 in a range from about 30 to 34 0 C. Nevertheless, when one desires to obtain high ethanol levels in the fermented must, levels above 11 0 GL, the reduction and control of the temperature are fundamental. Several works prove that, in order to prevent the yeast from stressing when 20 one desires to operate with high alcoholic contents, reducing the temperature is one of the most relevant factors. Rivera et al. (E.C.Rivera et al., Evaluation of optimization techniques for parameter estimation: 25 Application to ethanol fermentation considering the effect of temperature, Process Biochemistry, 1682-1687, 2006) considered the temperature variable extremely important to evaluate the optimized and estimated parameters of the ethanol fermentation, based on 30 experimental data. These authors concluded that, between 28 and 311C, there is maximum ethanol production. Prescott e Dunn's (Prescott, S.Dunn's, A. Industrial Microbiology, 4a.ed. CBS Publishers and Distributors, New Delhi, India, p.541-581, 1987) verified that the optimum 35 temperature for the cell growth and ethanol production is 301C, higher temperatures (35-38 0 C) being tolerable, but WO 2012/103609 9 PCT/BR2011/000038 to the detriment of the alcoholic contents. In this temperature range, the cellular growth rate, the ethanol production and .the death rate can be drastically affected. 5 Joses et al. (Alcohol fermentation by yeast - the effect of environmental and other variables. Process Biochem., 1981) reported that the yeast S.cerevisiae tolerates temperature levels to about 33-C, in industrial conditions, for production of ethanol. The minimum growth 10 range occurs in temperatures from about 10 0 C to 40 0 C, the optimum operation temperature being in the range between 28 0 C and 35 0 C. Dias et al. (M.O.S.Dias, R.Maciel Filho and C.E.V Rossel, Efficient cooling of fermentation vats in ethanol 15 production. Proc. Int. Soc. Cane Technol. Vol. 26, 2007) reported that high temperatures in the fermentation affect the yeast metabolism and reduce the concentration of ethanol in the end wine, which increases the consumption of vapor in the distillation. The 20 fermentation conducted at 28 0 C enables operating with higher sugar concentrations in the must, which fact reduces the vapor consumed in the distillation and generates vinasse in levels of 5.76 L/L EtOH. Reducing the fermentation temperature, besides directly benefiting 25 the end ethanol contents in the fermented must, which results in an increase of the specific capacity for production of ethanol by total volume of fermenters, leads to less vapor consumption in the wine distillation and reduces the generation of effluents (vinasse), 30 besides other benefits. Among these benefits, it can be emphasized the reduction in the levels of bacterial infection of the must, the reduction of input consumption (antibiotic and sulfuric acid for control of contaminant microorganisms) for the treatment of the yeast in the 35 starter, a better foam control in the fermentation (reducing the consumption of the dispersant and of the WO 2012/103609 10 PCT/BR2011/000038 antifoaming agent) and an increase of the fermentation yield. During Brazilian harvest, the registered temperatures of the fermentation are in the range from 32 0 C to 36 0 C. 5 Thus, to lower the fermentation temperature to values between 28 0 C and 32 0 C, it is necessary to use adequate water refrigeration systems (chillers). The refrigeration system has the object of reducing the temperature of a fluid at a temperature substantially lower than the 10 ambient temperature. The thermodynamic principle, which rules this system, teaches that the energy cannot be created nor destroyed, and no system can receive heat at a given temperature and release it to a system at a higher temperature without receiving external work. 15 Usually, the industrial processes use equipment to generate cold. water, with the purpose of refrigerating heat generating units. The choice for efficient systems, at low cost and low energy consumption for producing cold water, as well as 20 the adequate strategy for cooling the must and the fermenters, are determinant to make the application of this system feasible. The chillers are basically divided into centrifugal chillers, screw chillers, reciprocating chillers and absorption machines. The three first types 25 are industrial refrigeration technologies which use the principle of vapor compression. Said systems present disadvantages in relation to the absorption system, since they present high electric energy consumption, do not allow using alternative energy sources, use synthetic 30 refrigerants with CFC/HCFC, present high operational cost and high indices of noise and vibration. On the other hand, the lithium bromide-based absorption machines allow using thermal sources, such as natural gas or LPG (liquid petroleum gas), exhaust steam from the turbines or 35 generator, low-pressure vegetal vapor from the evaporators, hot water or condensate, alcoholic vapors, WO 2012/103609 11 PCT/BR2011/000038 vinasse effluent from the distillation column, and even residual gases from the combustion. In order to make the use of the existing hot sources feasible, the latter are required to be at a temperature higher than 75 0 C. These 5 systems require a low investment and present a low operational cost. The absorption systems employ mainly water, lithium bromide or ammonia. The lithium bromide based absorption refrigeration machines use the vacuum principle and the high capacity of the lithium bromide 10 solution to absorb water vapor. The water, when maintained under intense vacuum, boils and vaporizes abruptly, besides being cooled to low temperatures. The lithium bromide solution is a highly hygroscopic solution, presenting the best solubility-vapor pressure 15 relationship, obtaining a highly efficient cycle therewith. The affinity of water for salt is measured by the reduction in the water vapor pressure. The higher the pressure reduction, the higher the salt concentration. An 20 absorption unit by lithium bromide consists, basically, of five main components: 1. Cooler Element: it comprises a pipe. section in which there occurs the return of the cold water which is indirectly cooled by the water pulverized on the tubes. 25 The evaporator element is maintained at an absolute low pressure, so that the sprayed water vaporizes and cools the water which passes through the tubes. 2. Absorber Element: it consists of a concentrated lithium bromide solution which absorbs the water vapor 30 vaporized in the evaporator element. The lithium bromide solution is discharged on the tubes through a pumping element. The total thermal load (refrigeration load + dilution heat + cooling of the condensed water + sensitive cooling of the solution) is indirectly 35 transferred to the cooling water, which comes from a cooling tower.

WO 2012/103609 12 PCT/BR2011/000038 3. Heat-Exchanger Element of the Solution: this component is used to improve the cycle efficiency by exchanging heat between the diluted solution, which leaves the absorber, and the concentrated hot solution, which comes 5 from the generator. 4. Generator Element: in this compartment, the diluted lithium bromide solution is maintained at the boiling point in the solution, through a hot source (above 75 0 C), to eliminate the absorbed vapors. 10 5. Condenser Element: in this compartment, the water vapor which was eliminated in the generator element is condensed to posteriorly return to the cooler element. The absorption cycle, therefore, is a cycle of two pressures in which it is usually maintained, for the 15 effluent cold water, a temperature between 7.2 0 C and 8.3 0 C. This water will be used for cooling, at an absolute pressure of 0.27 in of Hgo, in the section of the evaporator-generator elements, and of 3.0 in of absolute Hgo, in the section of the generator-condenser 20 elements. The absorption cycle basically comprises three circuits: one in which the refrigeration water is pumped to the evaporator element, and the lithium bromide, used as absorbent, circulates on the evaporator tubes, through the heat exchanger to the generator; the cooling water 25 flows in series, initially through the absorber tubes and, partially, through the condenser tubes. The water to be cooled is admitted in the bundle of tubes of the cooler, in which it is indirectly cooled by water pulverization. The vaporized water is absorbed by a 30 concentrated lithium bromide solution at a low pressure. The lithium bromide which absorbed the water vapor is then pumped, through the heat exchanger, from the solution to the generator, so as to reconstitute the diluted solution. The water vapor generator operates at 35 low pressure so as to expel the water vapor absorbed in the solution, thus concentrating the salt solution, WO 2012/103609 13 PCT/BR2011/000038 before re-entering in the absorber element. The solution flow which comes from the generator goes to the absorber by difference of gravity and pressure. The water which leaves the generator in the form of vapor is then 5 condensed, passes to the liquid state in the condenser element section, and the condensate returns to the evaporator element. Upon application of this cold water production system, besides an adequate protocol for feeding the cooled must and the cooling system of the 10 fermenters, it is possible to define a new process which operates with high ethanol contents in the end fermented must. The thermal sources to be used in the cold water production system must be fluids with temperature superior to 75 0 C. 15 Accordingly, among the sources available in the sugar and alcohol industry complex, there can be used: the vinasse effluent from the distillation, condensates from the juice evaporation, alcoholic vapors from the distillation, vegetal vapors coming from the juice or 20 vinasse evaporation, exhaust steam from the turbines or bled from the generators, biogas (methane) coming from the biodigestion of vinasse and chimney gases resulting from the bagasse and/or straw burning. Summary of the Invention 25 Considering the inconveniences mentioned above, it is an object of the of the present invention to provide a process which allows effecting the biochemical fermentation from sugar to ethanol, at low temperature, with high sugar concentrations, and which results in low 30 production of carboxylic acids and glycerol, and high conversion rates of TRS to ethanol, in order to obtain ethanol contents, in the end fermented must, superior to about 10-11 0 GL. The process consists of the following steps: (i) 35 preparing a must to feed the fermentation containing a high sugar content, containing between 18% to 35% of TRS, WO 2012/103609 14 PCT/BR2011/000038 preferably above 22% of TRS; (ii) cooling the must used in the fermentation to temperatures between 8 0 C and 30 0 C, preferably from 22 0 C to 25 0 C; (iii) feeding the yeast cream constituted of Saccharomyces cerevisiae, to the 5 fermenter, so as to maintain a concentration, on a volumetric basis, of about from 5% to 15%, preferably about 10%; (iv) gradually feeding, at. increasing flow rates, the cooled must to be fermented into the fermenter containing the yeast, so as to accompany the progressive 10 increase of the metabolic activity of the microorganism; (v) starting the cooling process of the fermenters, at the stage in which the temperature of the fermentation system surpasses from 28 0 C to 30 0 C, preferably 280C; (vi) maintaining the process of fermentation and must feeding; 15 (vii) maintaining the fermentation until reaching a substantially zero TRS value; (viii) sending the fermented must for separation of the wine and yeast in a centrifugation system; (ix) returning the separated yeast to be re-used in the process; and (x) sending the 20 centrifuged wine to distillation. In this process, it is preferably used a cold water generator system which uses, as thermal source, one of the sources available in the sugar and alcohol industry complex, such as: the vinasse effluent from the bottom of the distillation system, 25 alcoholic vapor condensates from the top of the distillation column, or even vegetal vapors effluent from the juice evaporation for the manufacture of sugar and/or ethanol, or exhaust steam bled from the turbines or generators. 30 Description of the Drawings The invention will be described below, with reference to the enclosed drawings, given by way of example of the currently employed system and some possible ways of carrying out the invention, and in which. 35 Figure 1 is a block diagram of the currently employed system for cooling the fermentation and the integration WO 2012/103609 15 PCT/BR2011/000038 thereof with the distillery. The raw materials used for compounding the must, such as clarified juice, pre evaporated juice, syrup and water, are sent to the must preparation unit (1) in controlled quantities. This must, 5 in the temperature range from 45 0 C to 95 0 C, is conducted to the thermal exchange device (2) to be cooled by the cooling water coming from the cooling system by tower or sprays (6) to the range from 30'C to 34 0 C. The cooled must is fed to the fermentation system (3) which can be 10 either a fed batch fermentation or continuous fermentation. In order to control the temperature of the fermentation process, the must in fermentation process is continuously cooled in the indirect thermal exchange devices (4), whose cold fluid is the evaporative cooling 15 water of the evaporative cooling system (6). The fermentation temperature is maintained controlled in the range from 32 0 C to 36 0 C. The end product of the fermentation (3), wine, is sent to the distillery (5) for recovery of the ethyl alcohol, generating a second 20 effluent from (5), which is used in regenerative thermal exchange devices for the pre-heating of the wine, before it is fed to the distillation device. After this use, the vinasse is then cooled to about 60 0 C and conveyed to be used in the sugar cane plantation site. 25 Figure 2 is a block diagram of one of the preferred forms of the invention, in which cold water is used to effect the cooling of the must and of the fermentation system. This cooling system consists of absorption chillers, in which the must prepared in the must preparation unit (1), 30 in the same manner as in the current system described in figure 1, with temperature range from 45 0 C to 95*C, is sent to the indirect thermal exchange device (2) to be cooled by the cooling water coming from the evaporative cooling system (6) to the range from 30*C to 34'C. Then, 35 it follows to the next cooling stage in the thermal exchange device (8), where it is cooled with cold water WO 2012/103609 16 PCT/BR2011/000038 at the range from 5 0 C to 250C, coming from the absorption chiller (7). This cold water used for cooling the must is refrigerated by the water of the internal circuit of the absorption refrigeration machine. The must, then cooled 5 to a temperature range from 70C to 27'C, is fed to the fermentation system (3). In this system, the temperature will be controlled in a temperature range from 20 0 C to 320C. Thus, the must in fermentation will be in constant circulation, passing through the indirect thermal 10 exchange device (4), in which the cold water coming from the absorption chiller (7) is maintained in the range from 150C to 270C. The available hot thermal sources for concentrating the lithium bromide solution of the absorption cycle of the chiller (7) in the distillery (5) 15 are: vegetal vapor, condensates, vinasse and alcoholic vapors and exhaust steam, preferably vinasse. One of these sources is sent to the absorption chiller (7) and, after passing through the generator element constituent of the chiller (7), will be disposed in the end 20 disposition unit (9) in the most economical manner. In case the heating fluid is the vinasse, its capture will be effected after passing through the regenerative thermal exchange device, described in figure 1. Then vinasse, in a temperature range between 80 0 C and 90*C, 25 will pass through the generator element of the chiller (7), indirectly exchanging heat with the diluted lithium bromide solution, leaving with the temperature in the range from 500C to 70 0 C. In case of using the vegetal vapor condensates, in a temperature range from 950C to 30 980C, the exit temperature thereof will be from about 60 0 C to 700C and they can be, therefore, re-used/treated for other purposes in the production process. In case of using alcoholic vapors as hot source, said vapors will be deviated from their conventional flow and, after passing 35 through the chiller, will return to the conventional flow of the condensed alcoholic vapors. In the absorption WO 2012/103609 17 PCT/BR2011/000038 cycle of the chiller (7) it is necessary to remove ' the heat from the process, through the cold water, and the heat from the hot source by means of a fluid available in range from 20 C to 35 0 C. In the conventional chiller 5 system, water is used in closed circuit by an evaporative cooling system 6). Figure 3 is a block diagram of another preferred form of the invention. In this system, there were basically excluded the thermal exchange devices (4) and (8) 10 represented in figure 2 and the water used as thermal exchange fluid in the generator of the chiller (7) was removed and substituted by a fluid of the process. The substitution of the water which circulates in the refrigeration system implies eliminating the auxiliary 15 indirect thermal exchange devices, equipment for transport of fluids, pipes and several accessories. In this innovative cooling system with absorption chiller, the must, prepared in the must preparation unit (1) in the same manner as in the current system, in the 20 temperature range from 45 0 C to 95 0 C, is sent to the thermal exchange device (2) to be cooled by the cooling water coming from the evaporative cooling system (6) to the temperature range from 30 0 C to 34 0 C. This must is conducted to the evaporator of the chiller (7) and cooled 25 by the refrigerant with temperature range from 5 0 C to 25 0 C. This cooled must is fed to the fermentation (3) . During the fermentation process, the temperature will be controlled at the range from 20 0 C to 320C, so that the must in fermentation will be in constant circulation, 30 directly passing through the evaporator of the chiller .(7). The hot circuit is the same described in Figure '2. On the other hand, the total heat of the absorption cycle of the chiller (7) will be removed by the wine coming from the fermentation (3) , at ambient temperature, and 35 will leave the chiller at the temperature range from 300C to 400C.

WO 2012/103609 18 PCT/BR2011/000038 Figure 4 is a block diagram of the refrigeration cycle of the preferred form of the invention represented in Figure 2, which uses cold water to effect the cooling. In this arrangement, in the lithium bromide vapor absorption 5 refrigeration machine, the refrigerant fluid, water coming from the condenser (3) at the liquid state, is sprayed in the evaporator (1), which is under vacuum of about 6 mmHg*. In this pressure level, the refrigerant evaporates and cools the water passing through the tubes. 10 The refrigerant, in the vapor state, is absorbed in the absorption device (1) in which a concentrated lithium bromide solution is sprayed on the vapors of the refrigerant, absorbing the latter and then diluting. The diluted solution is pumped to the generator device (2), 15 where it is heated in an indirect thermal exchange device, by a hot source, provoking the evaporation of the refrigerant fluid. Said refrigerant, at the vapor state, is sent to the condenser device (3), where it is condensed to the liquid state in an indirect thermal 20 exchange device, whose cooling fluid comes from an evaporative cooling device, for example, a cooling tower. The energy released during the absorption process is removed with cooling water coming from the condenser device (3). 25 Figure 5 is a block diagram of the refrigeration cycle of the other preferred form of the invention represented in Figure 3- and which does not use cold water to carry out the cooling, but instead fluids available in the fermentation and distillation process. In this 30 arrangement, the lithium bromide vapor absorption machine presents the following differences in relation to the system schematically represented in Figure 4: the cold water circuit in the evaporator device (1) is substituted by must and fermented must, and the cooling water used in 35 the condenser device (3), as well as the water of the absorber device (1) are substituted by wine.

WO 2012/103609 19 PCT/BR2011/000038 Detailed Description of the Invention In one of the preferred forms of the invention, the must is prepared from the mixed juice, or clarified juice, or juice pre-evaporated until from about 22% to 30% of dry 5 matter, or syrups and molasse effluent from the manufacturing process of sugar from sugar cane e/or its mixtures, so as to obtain a TRS from 18% to 28%. The must is then cooled to from about 15 0 C to 25 0 C, preferably from 22 0 C to 25 0 C, in indirect thermal exchange auxiliary 10 devices, whose cold fluid is cold water (from 10 0 C to 20 0 C) coming from a refrigeration machine, preferably a lithium bromide-based absorption machine. The yeast consisting of Saccharomyces cerevisiae, with a concentration from 30% to 60% (volume/volume), is fed 15 into the fermenters, in a proportion from 5% to 15% of its useful volume, preferably 10%. Next, the fermenter containing yeast is added with must, initially in a small flow rate, which is progressively increased as the metabolic activity for converting sugars to ethanol and 20 CO 2 , of the microorganisms constituent of the yeast, is accelerated. When the temperature of the must in fermentation process reaches from 28oC to 32 0 C, the refrigeration system of the fermenters is activated. This system consists of indirect thermal exchange devices, in 25 which the cold fluid is cold water generated in the refrigeration system, in a refrigeration machine, preferably a lithium bromide-based absorption machine, which exchanges heat with the must in fermentation process, so as to maintain in the fermenters a 30 temperature between 28 0 C and 32 0 C, preferably 30 0 C. The cold water fed to the indirect thermal exchange devices is usually dosed at a temperature range between 8 0 C and 12 0 C and is discharged with a temperature from about SoC to 8 0 C above de temperature in which the must in 35 fermentation process is maintained. The feeding of the refrigerated must is carried out until reaching the WO 2012/103609 2 0 PCT/BR2011/000038 useful volume of the fermenter, being interrupted thereafter. The fermentation is considered finished when the TRS of the must in fermentation process reaches the substantially zero value. The fermenters are closed 5 vessels, the gas (C0 2 ) emitted in the fermentation process being collected and washed with water in towers for recovery of the ethanol dragged jointly with the gas stream. Upon completion of the fermentation process, the concentration of ethanol in the fermented must lies in 10 the range from 8 to 16 0 GL, preferably above 1O 0 GL. The fermentation process becomes complete in a time interval of 6-12 hours, depending on the end ethanol content in the fermented must, presenting a typical value of about 10 hours. The fermented must is then sent to a system for 15 separating the yeast and the wine. The obtained wine is then conducted to the distillation and, the yeast, containing a concentration of 30% to 60%, returns to an acid treatment system and, subsequently, to the fermentation process. In this form of the invention, it 20 should be emphasized that the refrigeration of the must drastically reduces the possibility of the fermentation to be infected and reduces the exchange heat area of the exchangers which aid the fermentation, since a substantial part of the heat is directly withdrawn by the 25 simple mixture of the refrigerated must with the must in fermentation process. In the other preferred form of the invention, the must is prepared from the mixed juice, or clarified juice, or juice pre-evaporated until from about 22% to 30% of dry 30 matter, or syrups and molasse effluent from the manufacturing process of sugar from sugar cane e/or its mixtures, so as to obtain a TRS from 18% to 28%. The must is then cooled to from about 15CC to 25 0 C, preferably from 22 0 C to 250C, in an indirect thermal exchange device 35 constituent of the refrigeration system, preferably a lithium bromide-based absorption machine. In this case, WO 2012/103609 2 1 PCT/BR2011/000038 the must substitutes the water in the circuit of the preferred refrigeration system, being cooled through an indirect thermal exchange with the water of the internal circuit of said system, which water is sprayed over the 5 thermal exchange area which is submitted to a high-vacuum evaporation process. Thus, there are obtained temperatures from about 3 0 C to 4 0 C (temperature corresponding to water in the vapor state at a pressure of 6.0 mmHgo) in the inner side containing water in high 10 vacuum evaporation process. Next, the Saccharomyces cerevisiae yeast, with a concentration between 30% and 60% (volume/volume), is fed to the fermenters in a proportion of 5% to 15% of its useful volume, preferably 10%. The fermenter containing yeast is then added with 15 the must, initially in a small flow rate which is progressively increased as the metabolic activity for conversion of sugars to ethanol and CO 2 , of the microorganisms constituent of the yeast, is accelerated. When the temperature of the must in fermentation process 20 in the fermenters reaches from 28 0 C to 32 0 C, the refrigeration system of the fermenters is activated. In this system, the must in fermentation process is pumped to an indirect thermal exchange device constituent of the preferred refrigeration system (lithium bromide-based 25 absorption machine) . In this device, the water of the internal circuit is sprayed over the thermal exchange area which, since it is submitted to a high-vacuum evaporation process, allows obtaining temperatures, in the internal side, from about 3 0 C to 4 0 C (temperature 30 corresponding to water in the vapor state at a pressure of 6.0 mmHGo) . The now cooled must in fermentation process returns to the fermenters and, as such, allows maintaining a temperature from 28 0 C to 32 0 C, preferably 300C. 35 The vapors produced by evaporation of the water are absorbed by the lithium bromide which is thus diluted.

WO 2012/103609 22 PCT/BR2011/000038 For reconstituting the original concentration of the lithium bromide solution, it is necessary to evaporate the absorbed water, which is effected through another indirect thermal exchange device. In -this device, the 5 lithium bromide solution exchanges heat, above 75 0 C, with one of the hot sources which can be vinasse, condensates, vegetal vapor, alcoholic vapors and exhaust steam. The water vapor is sent to an indirect condensation device, in which the condensing fluid is the deyeasted wine 10 effluent from the fermentation. Thus, the wine is heated and conducted to distillation, completing the refrigeration cycle by adsorption. The other operations are identical to the ones described for the other preferred form of the invention. Thus, the auxiliary 15 indirect thermal exchange devices, used in the other form of the invention, are eliminated, leading to a more cost effective fermentation system. The process object of the present invention, in the two preferred forms, differs from the conventional process by 20 the aspects described below. In the case of a combined mill, the must is prepared from molasse, water and clarified juice and, in the case of an autonomous distillery, the must is prepared from pre-evaporated sugar cane juice. After the preparation, the must 25 temperature lies in the range from 70 0 C to 100 0 C. This must is then cooled using water from the cooling tower, or from the spray system, to be then conveyed to the fermentation process. In the alcoholic fermentation, it is necessary to remove the energy released in the form of 30 heat, in the proportion of about 150 kcal/kg TRS (equation 1), so as to maintain stable the fermentation temperature. Generally, the must cooling and the fermentation temperature control are carried out by using raw water/treated water from the mill circuit, which can 35 be an open our closed system. When the closed circuit is used, the cooling of the water is made through the WO 2012/103609 23 PCT/BR2011/000038 evaporative system, using equipment such as cooling towers or ambient air spray systems. The evaporative cooling process comprises, basically, two mechanisms. A first mechanism, in which the heat transfer results from 5 the vaporization of a small water portion, and a second one, in which the sensible heat transfer is caused by the difference of temperatures between the water and the air. The heat to be removed from the water, in the cooling tower, depends on the air temperature and humidity 10 content. An indication of the air humidity content is its wet-bulb temperature. Wet-bulb temperature is the dynamic equilibrium temperature reached by a water surface when the heat transfer rate to the surface, by convection, becomes equal to the heat consumption by mass transfer 15 from the surface to the ambient. That is, the wet-bulb temperature depends on the air temperature and humidity. The wet-bulb temperature will determine the minimum possible temperature in the evaporative cooling. The evaporative cooling devices are designed to provide an 20 approximation around 5oC. Hence, for example, a region with a wet-bulb temperature of about 240C, at a certain season of the year, will provide a minimum temperature for the cooled water around 290C. This will represent, therefore, the lowest temperature existing in the sugar 25 and ethanol manufacturing process. Thus, the cooling processes in the sugar and alcohol industry are limited to the climatic conditions and, accordingly, suffer a natural variation. During the harvest in Brazil, the registered fermentation temperatures , lie in the range 30 from 32 0 C to 360C. In different environmental and nutritional conditions, the yeast can adopt distinct metabolic routes for the production of different compounds. In anaerobic conditions, the glucose can be converted to ethanol, acetic acid, lactic acid and 35 carbonic gas, which reduces the ethanol produced by TRS unit. As reported by specialized literature, one of the WO 2012/103609 24 PCT/BR2011/000038 most important factors listed in the preferential yeast reaction is the temperature. There are several reports in literature which indicate temperatures below 32 0 C as being optimum values for the maximum conversion to 5 ethanol. Thus, the proposed process eliminates the limitations inherent to the control of the temperature at adequate levels. The advantages of adopting this process can be summarized below: - Elimination of the water open-circuit in the must and 10 in the fermentation cooling system, which consequently eliminates the water capture to make up the water lost in the evaporative cooling system and, accordingly, reduces the consumption of chemical products for water treatment; - The elimination of water allows employing smaller 15 cooling towers to fulfill the demand of the distillery. Usually, the water which is sent to the condensers is the water flowing after passing through the indirect thermal exchange devices of the fermenters, that is, water already at a temperature above 29 0 C. With the proposed 20 system, the water which will be sent to the condensers presents a temperature of about 32oC-350C coming from the evaporative cooling system; - Operating the fermentation at the ideal temperature (provides the production of ethanol and reduces the 25 secondary fermentations and microbial contaminations); - Operational stability of the fermentation; -.Reducing bacterial infection of the must; - Reducing the input consumption of inputs (antibiotic and sulfuric acid) for treatment of the starter and for 30 control of the fermentation foam (dispersant and antifoaming agent); - Increasing the fermentation yield; - Providing the increase of the wine alcoholic content at levels between from 12 to 16 0 GL. This causes an increase 35 of the specific capacity for producing ethanol by total volume of fermenters and distillation columns, as well as WO 2012/103609 25 PCT/BR2011/000038 less vapor consumption in the wine distillation; - Reducing the generation of effluents (vinasse), which reduces the expenses with transport and application of vinasse in the plantation site. 5 As previously described, the present process has the object of allowing effecting the biochemical fermentation from sugars to ethanol, at low temperature and with high sugar concentrations, resulting in low production of carboxylic acids and glycerol and in high conversion 10 rates from TRS to ethanol, so as to obtain ethanol contents, in the end fermented must, superior to about 10-11 0 GL. The present process is carried out in several steps, starting with the preparation of a must for feeding the 15 fermentation with high sugar content, containing from 16% to 30% of TRS, preferably above 22% of TRS, posterior cooling, fermentation, etc. In the preferred forms discussed above, the must is prepared from mixed juice, or clarified juice, or pre 20 evaporated juice until about from 22% to 30% of dry matter, or syrups and molasse effluent from the process for manufacturing sugar from sugar cane and/or its mixtures, so as to obtain a TRS from 18% to 35%. The process claimed in the two preferred forms differs 25 from the conventional process, regarding a combined mill, in that the must is prepared from molasse, water and clarified juice and, in the case of an autonomous distillery, in that the must is prepared from pre evaporated sugar cane juice. 30 The descriptive text presented below proposes examples of industrial application of the process in a plant with a nominal capacity to process 20,000 liters of ethanol/day, provided with a fermenter in stainless steel of 100 M 3 , an absorption chiller of 300 TR and an evaporative 35 cooling tower of 315 m 3 /h. In a first example, as a typical case of an ethanol plant WO 2012/103609 2 6 PCT/BR2011/000038 associated with a sugar factory, the must was prepared from clarified juice and molasse (residual syrup from a three-mass cooking system). After the preparation, the must presented the following characteristics: pH of 5.5; 5 0.30% of impurities; 52.90% of Brix; 54.26% of TRS; 82.37% of purity and 2.5g of acidity/ml. In a vessel previously cleaned with hot mass phlegm, vapor and heated water, yeast cream and water was added in such a proportion as to obtain a yeast cell concentration of 10 about 30%. The yeast cream received the addition of sulfuric acid until reaching a pH of 2.1. Next, the volume of 23m3 of yeast cream contained in the starter was pumped to the fermenter of 100m 3 (volumetric percentage of yeast of about 7%), at an average flow rate 15 of 45m 3 /h. Subsequently, it was initiated the feeding of the must, maintained at the temperature of 36 0 C in a controlled flow rate, for maintaining the fermentation medium with a concentration of 11% Brix. The must feeding average temperature was maintained at about 36 0 C and the 20 fermentation temperature at 29 0 C. The control of the fermentation temperature was carried out by means of a control loop actuating in the cold water circuit, maintained at 20 0 C, exchanging heat in the indirect form (plate heat-exchanger). The volume of the fermented must 25 in circulation was of about 85m 3 /h. After reaching the total volume of 70m 3 (70% of the fermenter volume), the must feeding was interrupted and the fermentation was maintained until obtaining a substantially zero TRS level. The total time of fermentation was of about 20 30 hours. The wine resulting from the process presented an alcoholic content of 15.90 v/v of ethanol; 10.96% of cells; 4.22 g of acidity/mL; pH of 4.8; 0.390% of glycerol; less than 1.0% of TRS and 73.37% of cell feasibility. 35 In a second example of industrial application, maintaining the same particularities of the plant cited WO 2012/103609 27 PCT/BR2011/000038 above, the must was prepared from liquor and water, as typically occurs in an autonomous ethanol plant. After the preparation, the must presented the following characteristics: pH of 6.01; 0.20% of impurities; 31.60% 5 Brix; 33.18% of TRS; 92.53% of purity and 0.729 of acidity/mL. In a previously cleaned vessel with hot mass phlegm, vapor and heated water, yeast cream and water were added in such a proportion as to obtain a yeast cell concentration of about 30%. The yeast cream received an 10 addition of sulfuric acid until reaching a pH of 2.1. Next, the volume of 26m 3 of yeast cream contained in the starter was pumped to the fermenter of 100m 3 , at an average flow rate of 45m 3 /h. Subsequently, it was initiated the feeding of the must, maintained at 29 0 C, in 15 a controlled flow rate so as to maintain the fermentation medium with a concentration of 11% Brix. The must feeding average temperature was maintained at about 29 0 C and the fermentation temperature at 300C. The control of the fermentation temperature was carried out by means of a 20 control loop actuating in the cold water circuit, maintained at the temperature of 200C, exchanging heat in the indirect form (plate heat-exchanger) . The volume of the fermented must in circulation was of about 85M 3 /h. After reaching the total volume of 71.7m 3 (71.7% of the 25 fermenter volume), the must feeding was interrupted and the fermentation was maintained until obtaining a substantially zero TRS level. The total time of fermentation was of about 11 hours. The wine resulting from the process presented an alcoholic content of 14.40 30 v/v of ethanol; 11.33% of cells; 2.41g of acidity/mL; pH of 4.5; 0.620% of glycerol; less than 0.169% of TRS and 73.37% of cell feasibility. In a third example of industrial application, maintaining the same particularities of the plant cited above, the 35 must was prepared from liquor and water, as typically occurs in an autonomous ethanol plant. After the WO 2012/103609 2 8 PCT/BR2011/000038 preparation, the must presented the following characteristics: pH of .5.65; 0.10% of impurities; 35.90% Brix; 39.07% of TRS; 94.17% of purity and 1.37g of acidity/mL. In a previously cleaned vessel with hot mass 5 phlegm, vapor and heated water, it was added yeast cream and water in such a proportion as to obtain a yeast cell concentration of about 28%. The yeast cream received an addition of sulfuric acid until reaching a pH of 2.0. Next, the volume of 27m 3 of yeast cream contained in the 10 starter was pumped to the fermenter of 10Om 3 , at an average flow rate of 45m 3 /h. Subsequently, it started the feeding with must, maintained at the temperature of 31 0 C, in a controlled flow rate, with the purpose of maintaining the fermentation medium with a concentration 15 of 11% Brix. The must feeding average temperature was maintained at about 31 0 C and the fermentation temperature at 30 0 C. The control of the fermentation temperature was carried out by means of a control loop actuating in the cold water circuit, maintained at 20 0 C, exchanging heat 20 in the indirect form (plate heat-exchanger) . The volume of the fermented must in circulation was of about 85m 3 /h. After reaching the total volume of 71.7m 3 (71.7% of the fermenter volume), the must feeding was interrupted and the fermentation was maintained until obtaining a 25 substantially zero TRS level. The total time of fermentation was of about 11.5 hours. The wine resulting from the process presented an alcoholic content of 14.84 v/v of ethanol; 13.3% of cells; 1.72g of acidity/mL; pH of 4.5; 0.720% of glycerol; less than 0.085% of TRS and 30 90% of cell feasibility. In a fourth example of industrial application, maintaining the same particularities of the plant cited above, the must was prepared from liquor and water, as typically occurs in an autonomous ethanol plant. After 35 the preparation, the must presented the following characteristics: pH of 5.53; 0.80% of impurities; 33.0% WO 2012/103609 2 9 PCT/BR2011/000038 Brix; 36.32% of TRS; 96.41% of purity and 0.59g of acidity/mL. In a previously cleaned vessel with hot mass phlegm, vapor and heated water, it was added yeast cream and water in such a proportion as to obtain a yeast cell 5 concentration of about 28%. The yeast cream received an addition of sulfuric acid until reaching a pH of 1.90. Next, the volume of 22.4m 3 of yeast cream contained in the starter was pumped to the fermenter of 10Om 3 , at an average flow rate of 45m 3 /h. Subsequently, it started the 10 feeding with must, maintained at the temperature of 26 0 C, in a controlled flow rate, with the purpose of maintaining the fermentation medium with a concentration of 11% Brix. The must feeding average temperature was maintained at about 26 0 C and the fermentation temperature 15 at 30 0 C. The control of the fermentation temperature was carried out by means of a control loop actuating in the cold water circuit, maintained at the temperature of 20 0 C, exchanging heat in the indirect form (plate heat exchanger) . The volume of fermented must in circulation 20 was of about 85m 3 /h. After reaching the total volume of 56m 3 (55% of the fermenter volume), the must feeding was interrupted and the fermentation was maintained until obtaining a substantially zero TRS level. The total time of fermentation was of about 11.5 hours. The wine 25 resulting from the process presented an alcoholic content of 16.78 v/v of ethanol; 16.67% of cells; 2.13g of acidity/mL; pH of 4.3; 0.49% of glycerol; less than 0.216% of TRS and 88.5% of cell feasibility.

Claims (21)

1. A process for producing ethanol from the fermentation of sugar sources in a fermentation medium with high ethanol content, characterized in that the fermentation 5 process is effected in a medium containing high TRS and ethanol content, comprising the steps of: (i) preparing a must to feed the fermentation medium containing a high sugar content, containing between 16% to 30% of TRS, preferably above 22% of TRS; (ii) cooling the must used 10 in the fermentation to temperatures between 8 0 C and 30 0 C, preferably from 22 0 C to 25CC; (iii) feeding the yeast cream of Saccharomyces cerevisiae, into the fermenter, so as to maintain a concentration, on a volumetric basis, of about from 5% to 15%, preferably about 10%; (iv) 15 gradually feeding, at increasing flow rates, the cooled must to be fermented to the fermenter containing the yeast, so as to accompany the progressive increase of the metabolic activity of the microorganism; (v) starting the cooling process of the fermenter, at the stage in which 20 the temperature of the fermentation system surpasses from 28 0 C to 30 0 C, preferably 28 0 C; (vi) maintaining the process of fermentation and must feeding; (vii) maintaining the fermentation until it reaches a stage in which the TRS value is substantially zero; (viii) sending 25 the fermented must for separation of the wine and yeast in a centrifugation system; (ix) returning the separated yeast to be re-used in the process; and (x) sending the centrifuged wine to distillation.

2. The process, as set forth in claim 1, characterized in 30 that the fermentation is of the fed batch type.

3. The process, as set forth in claim 2, characterized in that the process of feeding the must into the fermenter containing the must in fermentation process is effected when the useful volume of the fermenter is reached. 35

4. The process, as set forth in claim 1, characterized in that the fermentation is of the continuous type, which is WO 2012/103609 3 1 PCT/BR2011/000038 constituted of several fermentation stages connected in series.

5. The process, as set forth in claim 4, characterized in that the cooled must is fed in the first, second and 5 third fermentation stages connected in series, preferably in the first and second stages, and more preferably in the first stage.

6. The process, as set forth in claim 4, characterized in that the yeast cream is fed in the first, second and 10 third fermentation stages connected in series, preferably in the first and second stages, and more preferably in the first stage.

7. The process, as set forth in claim 4, characterized in that the fermenters are constituted of agitated reactors 15 in series, in such a quantity that the substantially zero TRS value is reached at the exit of the last fermentation stage.

8. The process, as set forth in claim 1, characterized in that the yeast cream receives an acid treatment before 20 being re-circulated in the fermentation system.

9. The process, as set forth in claim 1, characterized in that the system for refrigerating the must and/or the must in fermentation process in the fermenters comprises a cold water circulation through indirect thermal 25 exchange devices, between the latter and the cold water, respectively.

10. The process, as set forth in claim 9, characterized in that the system for refrigerating the must and/or the fermenters is preferably of the absorption machine type 30 and which uses, as hot source, at least one of the fluids at a temperature superior to 75 0 C, selected from vinasse, condensates, vegetal vapor, alcoholic vapors or exhaust steam, preferably condensates, alcoholic vapor or vinasse, more preferably vinasse. 35

11. The process, as set forth in claim 1, characterized in that the must is cooled by indirect contact in the WO 2012/103609 32 PCT/BR2011/000038 exchanger internal to the refrigeration system, eliminating the cold water circulation.

12. The process, as set forth in claim 11, characterized in that the hot source circulating in the absorption 5 refrigeration system is at least one of the sources, at a temperature above 75 0 C, selected from vinasse, condensates, vegetal vapor, alcoholic vapors or exhausted steam, preferably condensates, alcoholic vapors or vinasse, more preferably vinasse. 10

13. The process, as set forth in claim 11, characterized in that the fluid used in the water condenser of the absorption refrigeration machine is the wine effluent from the fermentation.

14. The process, as set forth in claim 11, characterized 15 in that the must is constituted of at least one of the components consisting of mixed juice, clarified juice, pre-evaporated juice, liquor or syrups, resulting from the sugar manufacturing process.

15. The process, as set forth in claim 1, characterized 20 in that the yeast is substantially formed of Saccharomyces cerevisiae yeast.

16. The process, as set forth in any of claims 9 or 11, characterized in that the yeast feasibility is maintained in values above 80%, by controlling the process, 25 sanitation, raw materials, fermentation, alcoholic degree, and by maintaining the must and the must in fermentation process in the fermenters at temperatures from 28 0 C to 30 0 C.

17. The process, as set forth in claim 1, characterized 30 in that the contamination level in the must in fermentation process is controlled at levels lower than about 105, by controlling the process, sanitation, raw materials, high alcoholic degree, fermentation, and by maintaining the must and the must in fermentation process 35 in the fermenters at temperatures from 28 0 C to 30 0 C.

18. The process, as -set forth in any of claims 9 or 11, WO 2012/103609 3 3 PCT/BR2011/000038 characterized in that the volume of generated vinasse, resulting from the wine distillation process, is reduced to about 40-60% of the volume usually generated in the distillation process, by maintaining the end alcoholic 5 content of the fermented product at about from 12 0 GL to 17.

19. The process, as set forth in any of claims 9 or 11, characterized in that the fermenters are sanitized upon application of mass phlegm coming from the device for 10 distilling ethanol and hot condensate and/or vapor, before being re-used.

20. The process, as set forth in claim 1, characterized in that the sugar source used in the fermentation process comes from at least one of the sources selected from: 15 sugar cane, beet, sweet sorghum, starchy sources hydrolyzed by glucose, cellulosic materials chemically or enzymatically converted to hexoses, or lignocellulosic materials chemically or enzymatically converted to hexoses. 20

21. The process, as set forth in claim 1, characterized in that part of the vinasse resulting from the must fermentation process and its posterior distillation are re-circulated in the fermentation process at a fraction from about 10% to 60%, preferably from 20% to 30%, more 25 preferably 25%.