WO2007082976A1

WO2007082976A1 - Method for obtaining bioethanol in a sugar plant

Info

Publication number: WO2007082976A1
Application number: PCT/ES2007/070008
Authority: WO
Inventors: Vicente Merino Febrero
Original assignee: Vicente Merino Febrero
Priority date: 2006-01-18
Filing date: 2007-01-16
Publication date: 2007-07-26
Also published as: ES2278532A1; ES2278532B1

Abstract

The invention relates to a method for obtaining bioethanol in a sugar plant, which comprises i) the fermentation of a solution with a content of sugars originating from: the actual sugar plant’s diffusion juice and/or other raw materials (cereals, beet, etc.) from outside the sugar plant; and ii) the distillation of the fermented product. The uses of the bioethanol obtained also form part of the present invention.

Description

PROCEDURE FOR OBTAINING BIOETHANOL IN A PLANT

SUGAR

The present invention relates to an alternative process in a sugar plant for obtaining a product, in addition to sugar, such as bioethanol. More particularly, it refers to the obtaining of bioethanol in a sugar plant by means of the raw materials of the same or other foreign ones that produce sugary solutions.

BACKGROUND OF THE INVENTION

World sugar production, in recent years, has been close to 110 million tons, with Brazil, Thailand, Australia, Cuba, India and the European Union as the main producers. More than 50% of world sugar consumption is obtained from sugarcane as raw material; while the rest comes from sugar beets, the main source of sugar for most of Europe.

Beet is a biannual plant, therefore, the normal sugar production line depends on its cultivation cycles.

If, in addition, we add the restrictions that are imposed, by official agencies, on the rates of sugar production and that are established for each country, the consequences are, among others, that the sugar industry will be in operation for a period less than 120 days a year, reduction in tons of sugar beet, with the consequent economic losses for the sector of both the sugar industry and the beet crop.

A series of by-products are derived from the sugar production line that can be marketed for later use in other industries. Among these by-products is molasses, which is obtained in the sugar extraction process and can be used as raw material in the manufacture of ethyl alcohol, citric acid, baking yeast and feed for cattle. EXPLANATION OF THE INVENTION

In accordance with one aspect of the present invention, a process for obtaining bioethanol is provided taking into account the normal sugar manufacturing line in a sugar plant, which comprises the following steps:

(a) the fermentation of a solution containing sugar, from: - the diffusion juice of the same sugar plant and / or

-other raw materials outside the sugar plant.

(b) the distillation of the fermented product;

In a preferred embodiment of this aspect of the invention, the bioethanol resulting from the distillation of step b above is subjected to a molecular dehydration process for purification.

The raw materials used in a sugar plant are usually beet or sugar cane, where the diffusion juice comes from them is obtained by washing and cutting the raw material and subsequent introduction into diffusers to extract the sucrose.

This sucrose extraction is carried out by means known as osmosis from the diffuser cells to the water or to the surrounding environment.

In a particular embodiment of the invention, it comprises the total or partial use of said diffusion juice for obtaining bioethanol. That is, the use of diffusion juice for the production of bioethanol, sugar or both products. This use of the diffusion juice will depend on the sugar plant itself, as it may be, the restriction imposed by official agencies on the reduction in tons of sugar or the time of collection of the raw material, among others.

The present invention provides a process for obtaining bioethanol in a sugar plant comprising the fermentation of cereals or other energy crops. Such cereals or crops they constitute a raw material outside the plant, which can be used in the same bioethanol manufacturing line, in order to increase the bioethanol production yield.

In a more preferred embodiment the cereal can be selected, but not limited, among corn, barley, wheat or any combination thereof.

In an also preferred embodiment, the energy crop can be selected, but not limited, among the chicory, thistle, etc.

The cereal used in the present invention is treated for subsequent fermentation, in the same manufacturing line to obtain bioethanol by means of diffusion juices of the raw material of the sugar plant. This treatment is carried out by different sieves and grinding, said grinding is mixed with water.

The difference of this process with the use of diffusion juices of the same plant is that now the sugars will be stored in the form of starch (30% amylose and 70% amylopectin) by what the fermenting microorganism must have, between others, amylases, glucanases (amylopectin 1-6 glucosidases de-branching agents) maltose to carry out the alcoholic fermentation.

In an even more preferred embodiment of the present invention, it includes including molasses, from the manufacture of sugar, in the fermentation process.

The process of the present invention comprises obtaining bioethanol with a purity of at least 90%.

A second aspect of the present invention provides bioethanol obtained by the described process.

By "Bioethanol" as used throughout the description should be understood, in general, ethyl alcohol or ethanol obtained through a biological procedure, such as an alcoholic fermentation. This Bioethanol is an important source of renewable energy in its use as a biofuel.

A third aspect of the present invention comprises the use of bioethanol obtained by the described process, as fuel, improver or oxidant, among others.

In the process of obtaining bioethanol described in the present invention from the distiller, a series of by-products will come out, among them, organic material, light alcohols, such as methanol, heavy alcohols, water. These byproducts can be used in other industries.

Therefore, a fourth aspect of the present invention includes the use of the by-products obtained in the process of obtaining bioethanol in a sugar plant for the manufacture of feed, paints, solvents, among others.

Throughout the entire description and claims of the specification, the word "comprises" and the variations thereof, are not intended to exclude other aspects of the present invention, which will be apparent to an expert in the field in view of the description .

The detailed exposition of the embodiments and the figures that follow are provided by way of illustration and are not intended to be limiting of the present invention.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1.- Schematic representation of the flow of materials in the process of obtaining bioethanol in a sugar plant.

DETAILED EXHIBITION OF REALIZATION MODES

EXAMPLE 1.- Derivation of the diffusion juice of the beet to fermentation for the production of bioethanol. In this example, there was another possibility of flow at the outlet of the diffuser juices that until now only had sugar production as a direction.

In a normal process in the sugar plant, this begins with the introduction of the raw material, in this case we use beets.

The beet was washed and cut into knife mills. Once the beet is cut into crops, it is introduced into the diffusers to extract the sucrose, this extraction was performed by osmosis from the diffuser cells to the water or to the surrounding environment.

The harvest, the name given to beet once washed and cut in the mills, and the water is introduced against the current in the diffuser causing the greatest possible contact, hence the diffusion juice is obtained.

The diffusion juice, which normally in a sugar plant passes to calcocarbon purification, which consists of the addition of lime (CaO) forming soluble sucrates and sucrates and subsequent steps to finally obtain sugar (Fig. 1)

Starting from this beet diffusion juice, the following phases were carried out:

A new outlet (or pipe) was installed that communicates said outlet of the diffusers with the fermenters, passing through both the diffusion juice to be fermented. Additionally, before the fermentation, an addiction of industrial enzymes can be carried out, either of chemical or biological synthesis to improve the fermentation performance. This addiction of enzymes can be made for any type of juice to be fermented. Enzymes that can be added include but are not limited to: Amylases, Glucanases, Invertas, etc. A treatment of U. HT was then carried out. (high temperature sterilization method) at 141.5 degrees Celsius for 5 seconds, with steam at the outlet of said juice to sterilize it and avoid degradation of sugars by other bacteria, mainly lactic and acetic acid bacteria.

The choice of this treatment U. HT. It is based on the fact that high temperatures and short times damage microorganisms, but are less aggressive for sugars.

Once the juice was sterilized, it passed to a vacuum chamber of the U. HT where, thanks to the action of a vacuum pump, it went to 8O ⁰ C.

In a later step the juice was cooled in a heat exchanger leaving at 3O ⁰ C temperature, at which it passed to the fermenter, where an alcoholic fermentation was carried out by microorganisms that possess

The enzyme invertase. This diffusion juice has appropriate characteristics for fermentation, therefore, we only add an ammoniacal phosphate yeast extract and some sulfur before fermentation.

The following reaction occurs:

C ₆ H ₁₂ O ₆ ^ 2C ₂ H ₅ OH + 2 CO ₂

From 1 mole of glucose, 2 moles of CO ₂ and another 2 of ethanol are obtained.

For one mole of glucose we will get 2 moles of ethanol. That is, for every 180.16 grams of glucose we will obtain 92.14 grams of ethanol as a theoretical maximum. In reality, the amount will be less, because some losses will occur.

This fermenter has its own heat exchanger to cool the heat produced in the exothermic fermentation reaction. further It also has stirrers, CIP cleaning showers and an ethanol recovery wash column where CO ₂ was released.

Once the juice was fermented, the CO ₂ was removed and the must, or fermented diffusion juice, was sent to a lung tank that allowed us to vary the flow rate into the distiller as well as homogenize it.

After the lung deposit, the juice went to a 4-column distiller.

From the first two distillation columns, called wort stripping columns, comes organic matter that can be used to produce feed. Then follows a third purification column in which we remove components with a lower boiling point than ethanol and water. Finally, we have the fourth rectification column, where we separate heavy and light alcohols that may be left and ethanol plus water to the azeotrope, that is, the point from which the ethanol cannot be separated from water by distillation because it is not a ideal mix.

In the next phase the water and ethanol passed through a molecular dehydrator of zeolite, and the ethanol came out with a purity of approximately 99.8%.

Once this purity was reached, the ethanol was ready to be stored and sold.

The various processes are connected by positive displacement pumps prepared to pump sugar fluids.

For a diffusion juice with 80% water and 20% dry matter (m.s.) of which 92% is sucrose. For this diffusion juice, 0.19688 kg sucrose / liter of juice were obtained.

With a 94% yield of the procedure for obtaining the bioethanol described in this example, and for a juice where we had 196,888 grams of ethanol per liter, the amount of ethanol we obtained per liter was 94.6535 grams of ethanol / liter.

EXAMPLE 2.- Obtaining bioethanol by the fermentation of molasses.

Molasses are to be obtained while producing sugar, assuming 4.5% of the total beet that is transformed into sugar.

Once the diffusion juice was fermented, the molasses were fermented, using the same procedure described in the previous example, with an expected yield of 43 grams of bioethanol for each liter of molasses introduced into the fermenters.

EXAMPLE 3.- Production of bioethanol through cereal fermentation.

This process has the following phases:

The choice of the varieties of these cereals was based on the starch richness of their grains, and therefore those varieties with the greatest genetic predisposition to store starch in larger quantities should be chosen (for example, 500-cycle and even 600-starch corn).

In this specific example a mixture of cereals selected from corn, barley and wheat is used.

First we proceed to the reception of cereal and storage in silos of 45,500 tons. It is very important to include dust vacuum cleaners and a storage tank, thus avoiding the presence of explosive atmospheres.

A mixture of the cereals indicated above was lifted by means of conveyor belts, from buckets to a hopper located in the upper part of the cereal grinding building, thus facilitating the displacement by gravity of it from now on.

The cereal mixture passed through a magnetic separator to avoid the inclusion of metal parts in the rest of the process.

Subsequently, it passed through separation sieves with the characteristic that said sieves could be adapted to various cereals, by means of the relevant changes in the meshes and grain separation discs.

Once passed the sieves were ground and transformed into flour in hammer mills. The amount of ground cereal was 1050 tons per day.

The flour was combined with water in a mixer.

The flour mixture with water was pumped by a UHT positive displacement pump already mentioned in example 1.

Once the cereal juice was sterilized, it passed to a vacuum chamber of the U. HT, where thanks to the action of a vacuum pump, it went to 8O ⁰ C.

Then the cereal juice was cooled in a heat exchanger, leaving at 3O ⁰ C temperature at which it passed to the fermenter.

The following reaction occurs:

C ₆ H ₁₂ O ₆ ^ 2C ₂ H ₅ OH + 2 CO ₂

For each mole of glucose you can get 2 moles of ethanol, that is, every 180.16 grams of glucose we would have 92.14 grams of ethanol as a theoretical maximum. The amount was smaller, because we had certain losses of the process.

This fermenter has its own heat exchanger to cool the heat produced in the exothermic fermentation reaction. further It also has stirrers, CIP cleaning showers and a wash column for ethanol recovery when CO2 is released.

Once the must was fermented, the CO2 was removed and the cereal must was sent to a lung tank that allowed us to vary the flow rate into the distiller and homogenize it.

Following the lung deposit, the cereal juice went to a 4-column distiller. From the first two distillation columns, called wort stripping columns, came organic matter that can be used to produce feed. Subsequently, it passed to a third purification column in which components with a lower boiling point than ethanol and water were removed. Finally, in the fourth rectification column, heavy and light alcohols that could remain and ethanol plus water were separated to the azeotrope, that is, the point from which the ethanol can no longer be separated from the water by distillation because it is not a mixture ideal.

In the next phase, the water and ethanol passed through a zeolite molecular dehydrator, and the ethanol came out with a purity of approximately 99.8%.

Once this purity was reached, the ethanol was ready to be stored and sold.

The various processes are connected by positive displacement pumps prepared to pump viscous fluids.

EXAMPLE 4.- Use of the by-products obtained in the manufacture of bioethanol for the production of feed.

In the procedures described in examples 1, 2 and 3, in the two distillation columns, called must stripping columns, organic matter came out, it was used to produce feed. The organic matter that came out of the first two distillation columns was taken to the dryer for drying, being subsequently pelletized and having as final product the feed that will be able to be commercialized and transported.

Approximately 18-20% of the ground cereal will be assumed, in the case that starchy corn is processed and 30% if it is wheat or barley.

Claims

1.- Procedure for obtaining bioethanol in a sugar plant comprising: a) the fermentation of a solution containing sugars, from:

-the diffusion juice of the same sugar plant and / or -other raw materials outside the sugar plant. b) the distillation of the fermented product.

2. Method according to claim 1, wherein the product resulting from step b is subjected to a molecular dehydration process.

3. Method according to any of claims 1 and 2, wherein the diffusion juice comes from beets or sugar cane.

4. Method according to any of claims 1, 2 or 3, wherein the diffusion juice can be used totally or partially to obtain bioethanol.

5. Procedure according to claim 1, wherein the raw material outside the sugar plant a cereal, any other type of energy crop or combinations thereof.

6. Procedure according to claim 5, wherein the cereal can be selected from corn, barley, wheat or any combination thereof.

7. Method according to claim 5, wherein the energy crop can be selected from the chicory, thistle or combinations thereof.

8. Method according to any of claims 5 or 6, wherein the cereal is treated for fermentation by sieving and grinding.

9. Method according to claim 1, wherein the molasses from of the manufacture of sugar can be used in said fermentation.

10. Process according to any of claims 1-8, wherein the bioethanol obtained has a purity of at least 90%.

11. Bioethanol obtained by the process according to claims 1 to 10.

12. Use of the bioethanol obtained by the process according to claim 11, as fuel, improver or oxidant.

13.- Use of the by-products obtained in the process for obtaining bioethanol according to the procedure claims 1 to 10, for obtaining feed, paints, solvents.