WO2010085862A1

WO2010085862A1 - Process of fermentation for production of bioethanol

Info

Publication number: WO2010085862A1
Application number: PCT/BR2009/000030
Authority: WO
Inventors: Silvio Roberto Andrietta; Maria de Graça Stupiello ANDRIETTA
Original assignee: Universidade Estadual De Campinas - Unicamp; Dedini S.A. Indústria De Base
Priority date: 2009-01-30
Filing date: 2009-01-30
Publication date: 2010-08-05

Abstract

'Process of fermentation for production of bioethanol', it refers to a process of alcoholic fermentation that uses strains of flocculant yeasts, in bioreactor of fixed tower kind, expanded bed or fluidized, with an unit of regeneration of biocatalytic coupled, using vegetable products that contain saccharose, glucose and fructose as raw material; the developed process is applied in the unit of fermentation of sugary materials containing saccharose, glucose and fructose, coming from vegetable sources of direct way or after hydrolysis, in the industries of production of alcoholic drunk, fuel alcohol, industrial alcohol and anhydrous alcohol; such process comprehends the following stages: 1) Preparation of the must, 2) Alimentation of the bioreactor, 3) Process of conversion, 4) Degassing of the fermented material, 5) Recovery of the biocatalytic, 6) Treatment of the biocatalytic, 7) Return of the biocatalytic to fermenter, and 8) Recovery of ethanol.

Description

"PROCESS OF FERMENTATION FOR PRODUCTION OF BIOETHANOL"

FIELD OF THE INVENTION

The present patent of Privilege of Invention refers to a process of fermentation for production of bioethanol that allows the obtaining of high concentrations of ethanol, with high productivity, in fermented material.

The said process eliminates the use of centrifugal machines once the separation of the biocatalytic of the wine for subsequent regeneration can be accomplished by decantation, pointing out that the raw material to be fermented extends to different sources of carbohydrates of vegetable origin.

FOUNDATIONS OF THE INVENTION

The first processes of alcoholic fermentation operating in fed-batch appeared in France and they dated from the decade of thirty. It is known as Melle-Boinot process. In those systems the reuse of the ferment for more than one fermentation cycle already exists. This process provided great progress in the industrial production of ethanol (ALMEIDA, 1960).

Brazil only started to use the fed-batch from the decade of 60. Those processes only had its accelerated use with the coming of the National Program of the Alcohol (Proalcool) in the seventies. According to ZAPERLLON & ANDRIETTA (1992), all the distilleries installed with the creation of Proalcool in 1975 were equipped with this process.

The continuous processes appeared as a way of improvement of the Melle- Boinot process, in spite of not being a recent development (FINGUERUT et al., 1992). ZAPERLLON & ANDRIETTA (1992) affirm that in the nineties, 40% of the Brazilian industrial units use processes of continuous fermentation. Comparative studies and economic evaluations of several processes used in ethanol production by fermentation concluded for the advantages of the process of continuous fermentation regarding traditional batch (CYSEWSKI & WILKE, 1978; MAIORELLA et al., 1984). CYSEWSKI & WILKE (1978) demonstrated a reduction of 57% in the investment of fixed capital in distilleries with continuous fermentation when compared to the ones that use I prosecute batch. Reductions still larger, of the order of 68 and 71%, are obtained for the processes that use the recycle of cells and operation to vacuum, respectively. All the above presented processes use Saccharomyces cerevisae yeasts with characteristic not flocculants. In the more recent processes, both continuous and discontinuous, the cellular mass is recycled using centrifugal separators, with posterior acid treatment of the mass of recycled cells. An innovation for the fermentative processes occurs with the flocculant yeasts utilization, allowing to eliminate the centrifugal separators that have purpose of separating the cells of the fermented wine (BU'-LUCK, 1983).

The possibility of utilization of Saccharomyces cerevisae yeasts with flocculant characteristic in the fermentative processes for ethanol production has been being object of study of several research groups. There are many proposed variations for that kind of process, could the fermentation occur in two kinds of bioreactors, being them: of perfect mixture and of a tower kind.

The processes using perfect mixture reactors are usually constituted of 2 or more bioreactors linked, in series with external system of agitation and cooling to heat changers, to the plate. After letting the last bioreactor, the wine is sent to a decanter, where the cells are separated of the wine by decantation, being the supernatant liquid sent to the lung tank of the distillery and the decanted cells are re-circulated to the process. This kind of process is installed in at least 3 Brazilian industrial units, being them: Petribu Paulista,

Trapiche and Sao Jose. They are several articles that present fermentative processes using bioreactor of the tower kind and with flocculant yeast. To follow they are described the ones that more present likeness with the proposed process.

PAIVA et al. (1996) demonstrated that it is possible to decrease ethanol production costs operating with a reactor of continuous way, of a tower kind, with high concentrations of cells, using decanters as unit of separation when the used yeast strain has flocculant characteristics, obtaining elevated values of productivity (14,4g of ethanol/L).

NAGASHIMA et al., (1983) proposed two kinds of arrangements for systems of continuous alcoholic fermentation with immobilized yeast. The first arrangement praises the utilization of two tower reactors of fluidized bed in series. The second propose uses three kind of tower reactors linked in series all with different diameter/height relation. The obtained productivity was 20 times greater than the traditional processes with a conversion of 95% besides the good operational stability obtained by a long period of time. VIEGAS et al., (2002 a) worked with two kind of tower reactors linked in series using flocculant yeasts. This process obtained maxim productivity of 15,4Og of Ethanol/L.h, keeping the revenue in the average of 93%.

VIEGAS et al., (2002 b) proposed a process of alcoholic fermentation using a system constituted of three reactors in series obtaining high revenues (92%), high concentration of ethanol in the wine (9,5GL) and high productivities (21,68g of Ethanol/L. h).

WIECZOREK & MICHALSKI (1994) used an only bioreactor of tower kind with flocculant yeasts operating with fluidized bed for ethanol production, starting from a synthetic ambiance and molasses with concentration of 17%(p/v) of sugar, reaching productivities from 15 to 20 kg of ethanol/m3 of bioreactor x hour. This used aeration in bioreactor to keep the viability of the ferment.

The patents that describe this kind of process are: CN1352241-A - it describes a new auto-flocculant yeast lineage that can be used to ethanol production, staying capture in the fermentation tank and could be separated without the utilization of centrifugal separators; US2005019932-A1 - it describes a flocculant yeast lineage that can be used in reactors well shaken to ethanol production;

GB2199844-A and B - they use mixture reactors linked in series, being the first one to cells reproduction with air addition and control of the substratum concentration and the fermentation occurring in the subsequent reactors, where anaerobic process is dominant;

US6861248 - where it is described different processes of the kinds: continuous and batch for ethanol production. One of the examples relates to a bioreactor of fluidized bed, where air is injected to keep the bed in movement.

BRIEF DESCRIPTION OF THE INVENTION

The present Privilege of Invention patent was developed aiming to solve the problems above mentioned.

The said invention consists of a process of alcoholic fermentation that uses flocculant yeast strains, in bioreactor of fixed bed tower kind, expanded or fluidized, destitute of unit of separation and re-circulation of cells.

The raw material to be processed includes material that contains saccharose, glucose and fructose, obtained by direct extraction or by hydrolysis of vegetable products. Residual materials coming from units of processing that also contain these sugars can be used in this process.

Nowadays, ethanol production in the American continent represents about two thirds of the total world production. This production reached in 1998 a value of 31.2 billion liters. This value corresponds to 20.3 billion liters of the total production of the American continent, to 5.5 in Asia, to 4.7 in Europe, to 0.5 in Africa and to 0.2 in Oceania (Berg, 1999).

In the crop 2005/2006, of the 440 million of tons of sugar cane planted in

Brazil, 177.9 million were transformed in ethanol. It was expected a production of 17 billion liters of alcohol (Brazilian Yearbook of the sugar cane, 2005). Great part of this production was obtained in plants that operate with conventional systems, being of continuous way or batch way.

The developed process will be applied in the unit of fermentation of sugary materials contend saccharose, glucose and fructose, coming from vegetable sources of direct way or after hydrolysis, in the industries of production of alcoholic drunk, fuel alcohol, industrial alcohol and anhydrous alcohol.

The present process has as main advantages: smaller cost of ethanol production, for eliminating stages as centrifugation and acid treatment; larger easiness of operation; easy automation to cost relatively low for demanding smaller number of control equipments due to its simplified operation; larger productivity; smaller implantation cost, for not depending of high cost equipments, as centrifugal separators; besides being applicable to any plants size, allowing access of the small producers to the tip technology.

DESCRIPTION OF THE FIGURES

To follow, the present Privilege of Invention patent is explained in full detail with base in the figure 1 , which illustrates, schematically, the flow control strategy for sugar cane broth.

In this figure, the indication 1 represents the broth, the indication 2 represents the water, the indications 3 represent the tanks, the indication 4 indicates the level controller, the indication 5 represents the density indicator, the indication 6 represents the flow controller, the indication 7 represents the flow meter and the indication 8 represents the valve. DETAILED DESCRIPTION OF THE INVENTION

The objective of the process below detailed concerning to the transformation of vegetable raw material in bioethanol, with help of biocatalytic.

The fermentation process for bioethanol production, object of the present Privilege of Invention patent, occurs in an industrial plant constituted essentially of bioreactors, tank of degassing, decanter and tank of biocatalytic treatment.

Bioreactors, from two to six, linked in series, used in this process are of the tower kind with height/diameter relation comprehended in the band from 5 to 20, with system of external cooling constituted of a bomb/changers of heat assembly to plate. At the top of the bioreactors exists a chamber of gases expansion, aiming avoid the drag of foam to the ethanol recovery tower. This expansion chamber is constituted by an increase of diameter from the point that corresponds to 75% of the height of the same.

The tank of degassing is a cylindrical tank with height/diameter relation comprehended between 1,2 and 1,4. The same is equipped with a mechanical agitator that allows the removal of the whole gas dissolved in the fermented material.

Decanter used to the separation of biocatalytic is a cylinder tank with conic fund of 60°.

The unit of regeneration of the biocatalyser is constituted of a cylindrical tank with height/diameter relation of 1 ,4. This tank is equipped with an aeration system that allows the formation of micro-bubbles that percolate by biocatalytic mass to be regenerated.

The microorganism used in the process below described relates to a lineage of yeast native of Brazil, isolated of Brazilian distilleries of fuel alcohol production, in a study where 1343 lineages were studied, from which 97 presented characteristics of flocculation and only 3 the special characteristics of flocculation necessary to be used in this kind of process. These yeast lineages have characteristics of intense flocculation, which allows the formation of stable beds in the bioreactors, allowing its operation as a bioreactor of fixed bed, which brings great advantages for processes that have strong inhibition for the product, as the case of the alcoholic fermentation.

The used raw material is originating of different vegetable sources, containing saccharose, glucose and/or fructose.

The developed process consists in the following stages: 1) Preparation of the must, 2) Alimentation of the bioreactor, 3) Process of conversion, 4) Degassing of the fermented material, 5) Recovery of the biocatalytic, 6) Treatment of the biocatalytic, 7) Return of the biocatalytic to fermenter, and 8) Recovery of ethanol.

The stage 1, which is the stage of preparation of the must, it consists in adapting the raw material, originating from different vegetable sources, to feed the first bioreactor. The material containing saccharose, glucose and/or fructose, originated or not of units of pre-treatment, such as hydrolysis, sterilization, decantation and another, it is sent to a tank provided of a level control system used to stabilize the alimentation flow of the first bioreactor.

The strategy of adjustment of the sugars concentration and pour of this flow line can vary according to the used raw material, namely:

When it is used sugar cane broth added of sugar cane molasses, the strategy adopted for the preparation and flow control consists in add honey to the broth in enough quantity, manipulating the speed of the honey bomb through the signal sent by density sensor, positioned soon after the static mixer installed in this line. The control of must flow consists in keeping constant the alimentation flow to the process through the manipulation of a modulator valve located at production line, in function of the signal received from the flow meter. So that this mesh works adequately, a second mesh is necessary. This mesh keeps the level of the broth tank through water addition, when the broth flow is not enough to keep the wished must flow. This system is constituted of a valve located in water piping that is manipulated through the signal received from a level transmitter located in the broth box.

Figure 1 shows schematically the strategy of complete control for this kind of raw material

When it is used concentrated of liquor of last pressure of the orange pulp, which generally is supplied of concentrated way, it should be diluted before being fed to the first bioreactor. The strategy of prepare of this raw material consists in add water to the same in line, controlling the water flow in order to reach the wished value of density. The flow control of this material for bioreactor is made through a modulator valve located in the alimentation line, according to the signal received from a flow meter located in this same line. In the stage 2, which refers to the alimentation of bioreactors, the raw material already ready in the stage 1 is sent through bombs to the bioreactor, where it is initiated the conversion of the sugars in ethanol. The alimentation of bioreactor is accomplished by the bottom of the same, with controlled flow. This alimentation can be divided for the other bioreactors, depending on the configuration of the chosen process, being always accomplished by the bottom of the bioreactor.

The stage 3, in other words, the conversion process, it initiates in the instant that the ready raw material is fed to the bioreactor. In this phase, the sugared material percolate by the biocatalytic bed, formed by yeast cells with flocculant characteristic, where it is transformed in ethanol along the same. Due to flowed dynamic problems, caused by the great volume of carbon dioxide formed during the process, this biocatalytic bed is divided physically into different parts, contained in several bioreactors linked in series. This division allows the elimination of part of the carbon dioxide produced in each part of the bed, decreasing the drag of biocatalytic, increasing the operational stability of the system.

The conversion occurs of a gradual way, following the profile of a bioreactor of piston flow, what decreases the inhibition of ethanol on the constituent cells of the biocatalytic bed. For being an exothermic reaction, each bioreactor is equipped with a changer of external heat, where the material contained in bioreactor is pumped to the changers, leaving a point situated to 50% of the total height of the same and returning by the bottom, with the alimentation. This procedure dilutes the material fed to bioreactor, decreasing the possibility of inhibition by the substratum.

Depending on the operation conditions, the biocatalytic beds can behave like fixed, expanded or fluidized bed.

When letting the biocatalytic bed, about 99,5% of the total of fed fermentable sugars will have been converted in ethanol.

In the stage 4, which is the stage of degassing of the fermented material, when leaving the last bioreactor, the resultant material of bioconversion contains ethanol, biocatalytic particles and dissolved gas. Aiming the recovery of biocatalytic, it is necessary the elimination of the carbon dioxide contained in it, allowing to it separates of the wine by decantation. Being this way, the effluent material of the last bioreactor is sent to a shaken tank, where this gas is totally eliminated.

In the stage 5, which consists in the recovery of biocatalytic, after the degassing of the fermented ambience, the same follows from the tank of degassing to a decanter of a single tray, where biocatalytic particles are retained and concentrated, being removed by the bottom of the same. The fermented liquid exempt of biocatalytic particles is sent to the lung tank of the distillation devices. The recovered particles are sent to the unit of regeneration.

In the stage 6, in other words, the stage of treatment of the biocatalytic, the regeneration occurs in a tank with time of retention between 0,5 to 4 hours, where is added water and air of continuous way. The aeration rate is kept in a band from 0,1 to 1 wm

(volume of air by volume of liquid per minute). After regenerated, the treated biocatalytic is returned to the first bioreactor of continuous way. This practice allows the regeneration of whole biocatalytic of continuous way without the need of interruption of the process in cycles comprehended between 24 to 96 hours. In the stage 7, which refers to the return of biocatalytic to the fermenter, occurs that after regenerated, biocatalytic is then sent to the first bioreactor of continuous way, being injected in the tube of the return of wine that passed by the heat changer. This location was chosen to for allowing a better mixture of this biocatalytic with the material in fermentation.

In the stage 8, in other words, the final stage of the process, which refers to the recovery of ethanol, the gases that leave the bioreactor are sent to a column of gases wash, where ethanol contained in the gases are recovered by the wash water, which return to the lung tank of the distillation devices.

The above description of the present invention was presented with the purpose of description and illustration. Moreover, the description does not intend limiting the invention to the way here revealed. In consequence, variations and modifications compatible with the teachings above and the relevant ability or knowledge of the technique are inside the scope of the present invention.

The modalities above described intend better explain the well-known ways to the practice of the invention and to allow the technicians in the area use the invention in such, or another, modalities and with several necessary modifications by the specific applications or uses of the present invention. It is the intention of the present invention including all the modifications and variations of the same, inside the scope described in the report.

Claims

1. "PROCESS OF FERMENTATION FOR PRODUCTION OF BIOETHANOL", it comprehends a process of alcoholic fermentation, wherein it especially uses strains of flocculant yeasts as biocatalytic and different vegetable sources containing saccharose, glucose and/or fructose as raw material.

2. "PROCESS OF FERMENTATION FOR PRODUCTION OF BIOETHANOL", wherein it comprehends the following stages: 1) Preparation of the must, 2) Alimentation of the bioreactor, 3) Process of conversion, 4) Degassing of the fermented material, 5) Recovery of the biocatalytic, 6) Treatment of the biocatalytic, 7) Return of the biocatalytic to fermenter, and 8) Recovery of ethanol.

3. "PROCESS OF FERMENTATION FOR PRODUCTION OF BIOETHANOL", wherein it occurs in an industrial plant constituted essentially of bioreactor, tank of degassing, decanter and tank of biocatalytic treatment.

4. "PROCESS OF FERMENTATION FOR PRODUCTION OF BIOETHANOL", as the claimed in 1 , wherein the used microorganism refers to a yeast lineage that has characteristics of intense flocculation, what it allows the formation of stable beds in the bioreactors.