DE102007004788A1 - Process for the distillation of a biologically produced alcohol - Google Patents

Abstract

The present invention relates to a process for the distillation of a biologically produced alcohol from a mash, characterized in that at least one HIDiC column is used for the process (Figure 3).

Description

Technical background

The Distillation is a thermal separation process to a liquid Mixture of different, mutually soluble substances the different boiling temperatures or different vapor pressures to separate at a given temperature. Typical applications of distillation are burning alcohol and distilling petroleum in the refinery.

at the distillation is first the starting mixture for Brought boiling. The resulting steam, resulting from the different Components of the solution to be separated is composed condensed in a condenser. Following is the liquid Condensate collected. The separation effect is based on the different Composition of the boiling liquid and gaseous Steam. The condensation temperature of the vapor (also vapors called) is lower than the boiling temperature of the starting mixture.

The Rectification represents a further development of distillation. This is a generally continuous process with several, consecutively connected distillation steps, which proceed in rectification column. The column consists of several Trays or layers of packing or packing. The region of the column above the feed is used as a reinforcing part or rectifying section, the area below the inlet, however, as a stripping section or Stripping section. The column and their floors are designed so that the steam in the reinforcing part rise and the condensate in the stripping section can flow.

The The main advantages of rectification are that the plant is continuous can be operated and that the separation effect compared to Distillation is many times higher, since the steam in continuous countercurrent with the liquid several times in contact with each other. The column works energetically cheaper, technically less complex and space-saving than one Series connection of single distillations.

The Contact surface between the vapor and liquid phases is replaced by internals (eg bubble trays, packing, Packs).

at Any contact between vapor and liquid phase will be appropriate the phase equilibrium from the vapor mixture a mixture with modified Concentration condense, whereby by the liberated heat of condensation again a mixture with higher concentration of the more volatile Part of the liquid phase will evaporate.

Becomes evaporates a liquid mixture, the result is the Concentrations of the individual substances in the gas and in the liquid phase from the temperature and the pressure. With enough contact a balance is established. Only in the case of a pure substance or an azeotropic mixture is the equilibrium composition the same in the gas phase and in the liquid phase. In all other cases is the concentration of low-energy higher in the gas phase than in the liquid phase.

So can be distilled off during the distillation of ethanol an aqueous solution, the concentration up maximum 95.58% alcohol increase. From this point are the Boiling temperatures of the alcohol-water mixture and of the water are identical, d. they are azeotropic. This is due to the presence of Hydrogen bonds, ie dipole moments.

distillation and rectification are thermally or energetically complex Procedure, since used large amounts of heat Need to become. The operating costs of such facilities will be therefore essentially determined by energy costs. in principle the professional world is therefore already for reasons of economy strives to maximize the energy efficiency of these processes to design.

For this reason, the method of vapor recompression has been developed, in which the vapors leaving the enrichment section of the column, known as vapors, are compressed by means of a compressor, the higher pressure increasing the condensation temperature of the vapor Condensation can thus be carried out in the range of the boiling temperature of the solution, which means that the heat of condensation for heating the stripping section of the column, ie to evaporate the solution, can be exploited, saving a large part of the heating energy but energy can be applied to operate the compressor.

Brüdenkompressionsverfahren are often used to concentrate liquids used, such. B. in sugar production or seawater desalination.

There in the case of burden compression, only the condensation temperature is increased, the distillation temperature is not affected. This is especially true in the distillation of bioethanol from mash of great importance. Although the distillation of ethanol from mash one of the oldest industrial processes of human history, but so far played less energetic aspects, as the ethanol produced predominantly was intended for human consumption and therefore relatively manageable Quantities was produced.

Also play other cost factors (elaborate maturation, quality raw materials, Taxation) in the production of ethanol for human Consumption plays a much more important role than the energy expenditure of distillation.

However, ethanol has come under discussion as a non-fossil fuel substitute for gasoline in the name of "bioethanol." Against the backdrop of CO ₂ production and related emission rights, consumer acceptance of such fuel, and moreover In order to be competitive with petrol, the production costs of bioethanol must be massively reduced to a possible tax preference favoring the production of bioethanol as petrol as energy-efficient as possible.

There the starting product mash a complex substance mixture with different organic ingredients, high temperatures lead to fouling processes in the column, especially if the latter complex soil or Have packing structures with narrow passageways.

Just in the production of bioethanol as a gasoline substitute energetic and economic aspects of enormously high Importance.

Object of the invention

task The present invention therefore provides a process for distillation to provide a biologically produced alcohol that is the manufacture large quantities with simultaneously reduced energy expenditure and at a lower cost.

Summary of the invention

These Task is with a method according to the submitted Main claim solved. The subclaims give preferred embodiments. Ranges of values by Certain numerical values are to be limited as inclusive these numerical values are understood.

Therefore is a process for the distillation of a biologically produced alcohol provided from a mash, which is characterized in that at least one HIDiC column is used for the process.

Of the Term HIDiC means "heat integrated distillation column" ("Heat integrated distillation column") This column type is a further development of the Load compression column. Unlike the latter here is the column physically in a stripping and a reinforcement part bisected and the compressor is between the output and the Reinforcement arranged. Furthermore, every floor is of the reinforcing part via heat exchangers coupled with a bottom of the stripping section, allowing heat flows from the reinforcing member in the driven part. The HIDiC therefore has a significantly higher efficiency as a column with vapor compression on.

Under the term "biologically produced alcohol" are all such alcohols subsumed, which are produced using essentially biological processes were, d. H. taking advantage of metabolic activity of microorganisms like bacteria or fungi, or with the help of Enzymes derived from such microorganisms or the derived from such microorganisms enzymes and / or material functionally similar or correspond.

With Help of the method according to the invention is on the one hand the pressure in the driven part reduced, resulting in a reduction of Boiling temperature leads, while the other Pressure in the reinforcing part is increased, which in turn leads to an increase in the condensation temperature. As a result, the temperature in the stripping section is reduced so much that it is below the temperature in the reinforcement part and thus a heat transfer from the individual soils of the reinforcing part to the respective coupled floors the stripping section is possible. Ideally - and this depends on the boiling properties of the ingredients of the mixture to be distilled and the set pressure ratios - approach Both temperatures are very strong. With the help of heat exchangers can now the heat of condensation on the respective stages transferred to the stripping section and to produce the required boiling temperature can be used.

The Supply of external heat is thus reduced substantially which is especially true of the large-scale Generating bioethanol as a gasoline substitute a big one Plays a role, since here the energy balance in the production both for tax reasons as well as for consumer acceptance is of great importance. On top of that, the manufacturing cost can be significantly reduced, which helps that the bioethanol thus produced is petrol can become competitive.

Of the particular advantage of the process in connection with the distillation of bioethanol is that lower through the HIDiC process Distillation temperatures in the stripping section can be achieved. To this Way, the thermal load of non-ethanolic ingredients reduced to a minimum, which in turn reduces the Fouling in the column and thus less stoppages (Cleaning) or leads to cost savings.

Farther it is preferably provided that it is the biologically produced Alcohol is about bioethanol.

Of the Term Bioethanol referred to by alcoholic fermentation biomass-derived ethanol. The responsible for this Fermentation processes, which usually bakers yeast (Saccharomyces cerevesiae) are used, are sufficient known.

In this case, biological polymers (usually polysaccharides such as starch) are first degraded to glucose and further on the glycolysis pathway to pyruvate. Pyruvate is then degraded by the enzymes pyruvate decarboxylase and alcohol dehydrogenase to acetaldehyde and then further to ethanol, thereby carbon dioxide is released. These last two steps are used to regenerate NAD ⁺ , which would otherwise be consumed in the glycolysis necessary for ATP recovery.

When Raw materials are all starchy substances (eg grain, Potatoes, sugar cane, corn, molasses, cassava). In middle and South America are preferably used cane and molasses, in Asia mainly cassava and in North America maize. Come in Europe especially wheat, rye, barley, triticale or over sugar juice and sugar beet molasses are used.

in principle But you can also ethanol by synthesis of water and ethene under Add sulfuric acid as catalyst. in this connection to obtain a not yet highly pure ethanol mixture whose Naturally, distillation causes less problems since the substrate to be distilled contains no substances, which could lead to fouling in the column.

bioethanol can be used as fuel for gasoline engines, fuel cells and Turbines driving motor vehicles or aircraft. This use comes in connection with the shortage of fossil fuels and the climate discussion as regenerative Fuel to increased importance. This is pure Ethanol (so-called E100) and mixtures of ethanol with gasoline or other Alcohols (eg methanol) are used. In particular, bioethanol doing mixed in different proportions with gasoline to both to reduce the gasoline consumption as well as the environmental impact. The Gasoline-alcohol mixture is used in the US as Gasohol and in Brazil designated as Gasolina Tipo C. In the US, the blends are E10 and E85, each containing 10% and 85% ethanol, disseminated. In Brazil most mixtures have an ethanol content between 21% and 23%.

According to the invention, it is preferably provided that the following pressure values are set in the HIDiC columns with the aid of the compressor (s): pressure ranges stripping section reinforcing part in principle 50-800 mbar 1100-4000 mbar prefers 150-600 mbar 1500-2500 mbar particularly preferred 250-400 mbar 1800-1950 mbar

Care must be taken to ensure that pressure gradients build up within the buoyancy and reinforcement sections; Thus, the pressure in the stripping section of the compressor increases in the direction of the sump, while the reinforcing part seen from the compressor falls in the direction of the upper end (see 5 ).

Especially It is preferably provided that as HIDiC column soil, packing and / or packing columns are used.

In Tray columns are built sieve, bell or valve floors, over which the liquid flows. By special Slots or holes, the steam is passed, leaving a Bubble layer is created. On each of these floors presents a new evaporation equilibrium.

packed columns can be filled with different substrates become. Due to the surface enlargement the approximately 10-40 mm large packing Heat and mass transfer are optimized and the separation ability the column thus increased. Well-known examples are the Raschig ring (one hollow cylinder), Pall ring, Hiflow ring, Intalox saddle, Berl saddle and hedgehogs. The fillers are random (as Bed) introduced into the column. As materials Glass, ceramics, metal and plastics come into question.

Structured Packs are a further development of the ordered packing. They have a regularly shaped structure. This makes it possible for packings, constrictions for the gas flow (with considerable influence on the pressure loss) to reduce. There are different versions of packages z. B. tissue or sheet metal packages. The material may be metal, Plastic, glass and ceramic (depending on wettability) used become.

Farther it is preferably provided that in the HIDiC column heat pipes (heat pipes) used as a heat exchanger.

In contrast to this, HIDiC columns known from the prior art are used in particular as so-called "heat transfer panels" as heat exchangers between the reinforcing part and the driven part EP1332781 such columns. A common problem with this type of heat exchanger is the expected pressure loss in the fluids flowing through the panels, which necessitates the use of additional pumps. The latter, in turn, has a negative influence on the energy balance of the overall process.

Heat By contrast, pipes consist of a hermetically sealed pipe each of a terminal heat transfer surface for heat source and sink, in which a fluid trapped is that evaporates in the area of the heat source and in the area the heat sink condenses. The generated at the source Steam of the fluid flows to the sink and gives the heat of vaporization by condensation. With suitable construction of the heat pipe The fluid circulates solely by gravity or by capillary action a arranged in the heat pipe, suitable material, eg. B. a wick. Heat pipes are characterized by a high heat transfer rate λ, which is about 200 × higher than that of copper. she are powerless and therefore low maintenance and consume no energy.

The use of heat pipes in distillation columns is already in the EP10253 described. However, it does not address the specific benefits that this process offers in relation to the distillation of bioethanol.

Especially it is preferably provided that in the inventive First process the mash a pre-distillation step passes. The purpose of this process step is the removal Volatile substances

Farther can be provided that in the inventive Method several, in the distillation process in series HIDiC columns are used. These can be z. B. in relation to the set pressures and / or temperatures differ.

Especially it is preferably provided that in a first HIDiC column in whose reinforcing part produces an intermediate distillate, fed to the stripping section of a second HIDiC column becomes. By this interconnection is achieved that the second column no solids are supplied and therefore there is no fouling occurs.

Farther is inventively provided that the or at least one of the distillation columns in the distillation process Pressure swing adsorber is connected downstream.

• 1) Adsorption bei hohem Druck
• 2) Druckabsenkung
• 3) Spülen mit Produktgas bei niedrigem Druck
• 4) Druckaufbau mit Rohgas bzw. mit Produktgas

The function of pressure swing adsorbers is based on the principle that the loading capacity of the adsorbent depends on the pressure and the temperature. The process is carried out in such a way that a gas mixture to be decomposed is passed through an adsorbent bed at ambient temperature and elevated pressure, with easily adsorbable gas components accumulating on the surface, while the components which have little or no adsorbability pass through the bed. The loading of the adsorbent can take place to an equilibrium state; then its adsorption capacity is exhausted. In order to perform the gas separation process again, the regeneration (desorption) of the loaded adsorbent is required, which can be done either by raising the temperature or, as in the pressure swing adsorption, by lowering the pressure. In order to be able to build up an adsorptive separation process with (quasi-) continuous product delivery, at least two adsorbers operated in parallel are required, of which one is currently in the adsorption cycle while the other is being regenerated at the same time. The process of pressure swing adsorption is based on the following four steps:

• 1) Adsorption at high pressure
• 2) pressure reduction
• 3) Rinse with product gas at low pressure
• 4) Pressure build-up with raw gas or with product gas

pressure adsorption are used in large numbers for the selective separation and extraction of Gases from gas mixtures and used for gas purification.

Farther is inventively a distillation unit having at least one HIDiC column provided, characterized is that these are for the distillation of a biologically produced alcohol a mash is used. Likewise, the invention is the Use of a distillation unit having at least one HIDiC column for the distillation of a biologically produced alcohol provided from a mash.

drawings

The The present invention will become apparent from the drawings discussed below explained in more detail. It should be noted that the examples just descriptive and not meant to be To limit the invention in any way.

bezeichnet einen Wärmetauscher, bei welchem 2 in Bewegung befindliche Fluide miteinander in einem Wärmeaustausch stehen. Bei dem einen Fluid handelt es sich um ein zu kühlendes oder zu heizendes Fluid (insbesondere das Destillat bzw. das Ausgangsprodukt, die Maische), während es sich bei dem anderen Fluid um das kühlende bzw. heizende Fluid handelt (insbesondere Kühlwasser oder Wasserdampf).
Das Symbol

bezeichnet einen Kompressor, wie er z. B. zwischen Abtriebs- und Verstärkungsteil einer HIDiC-Kolonne geschaltet ist.
Das Symbol ⋈ bezeichnet überdies eine ggf. regelbare Drossel im Leitungssystem.
Das Symbol

bezeichnet eine gesondert vorgesehene Heizeinrichtung.The following preliminary remarks apply:
The symbol

denotes a heat exchanger in which 2 moving fluids are in heat exchange with each other. The one fluid is a fluid to be cooled or heated (in particular the distillate or the starting product, the mash), while the other fluid is the cooling or heating fluid (in particular cooling water or water vapor).
The symbol

denotes a compressor, as he z. B. is connected between the output and amplification part of a HIDiC column.
The symbol ⋈ also designates an optionally controllable throttle in the line system.
The symbol

denotes a separately provided heater.

The 1 - 3 show in succession a conventional distillation unit ( 1 ), a plant operating according to the vapor compression method ( 2 ) and a plant according to the HIDiC method.

1 shows a conventional distillation plant 10 with a rectification column 11 , a heating device 12 and a cooling device 13 , The two latter devices are designed as heat exchangers according to the above description. The letter F indicates the raw material feed, the letter D indicates the discharge for the vapor fraction, and the letter B indicates the sequence for the distillation residue. In principle, it can be stated that in this embodiment the condensation temperature of the steam in the cooling device 13 (also called vapor) is lower than the boiling point of the starting mixture in the heater 12 ,

2 shows a distillation unit 20 according to the vapor compression method, with a rectification column 21 , a heat exchange device 22 and a compressor arranged in the region of the discharge for the vapor fraction 23 , By increasing the pressure in the region of the vapor fraction, its condensation temperature is raised so that the condensation temperature of the vapor and the boiling point of the starting mixture approach each other. For this reason, the cooling device for the steam as well as the heating device in a common heat exchange device 22 to be united. That is, in this heat exchange device, the steam flow acts as a heating fluid and the drain of the distillation residue acts as a fluid to be heated. In this way, the heat of condensation for heating the stripping section of the column, ie for evaporation, exploited. Here, a large part of the heating energy is saved. However, energy must be applied to operate the compressor.

3 shows a distillation unit 30 according to the HIDiC method, as used in the method according to the invention. The plant has a column with a stripping section 31a and a reinforcement part 31b on. The stripping section of the column is via a heater 32 heated during the resulting in the reinforcing part of the steam in a cooling device 33 is cooled. The two latter devices are designed as heat exchangers according to the above description. Between output part 31a and reinforcement part 31b is a compressor 34 connected, which reduces the pressure in the stripping section (and thus the boiling temperature of the distilled material), and increases pressure in the reinforcing member (and thus the condensation temperature of the steam); both temperatures are approaching in this way. stripping section 31a and reinforcement part 31b are interconnected via heat exchangers, z. B. in the form of heat pipes (heat pipes) may be formed. In this way, a large part of the condensation heat from the reinforcement part 31b in the Abtrienbsteil 31a transferred, and the energy use in the heater 32 is greatly reduced.

4 gives a schematic overview of the above-described relative ratios of boiling and condensation temperature in the three aforementioned embodiments.

5 shows the functional principle of a large-scale plant for the distillation of bioethanol, which has two HIDiC columns. Both columns are preceded by a pre-distillation column, which is passed through by the mash, and which serves to remove the volatile substances.

Farther Are the columns two pressure swing adsorbers (Pressure Swing Absorber, PSA) whose function is described above.

Out 5 go in the inventive method for the distillation of bioethanol adjustable pressure and temperature values.

Investigations by the inventors have surprisingly shown that with such an arrangement the energy consumption of the process can be reduced by about 30% compared to conventional methods. Thus, the ratio of steam flow (superheated steam) to ethanol flow m ' steam / m ' ethanol in a projected bioethanol plant according to the vapor compression method 2,4, while a parallel projected bioethanol plant according to the HIDiC method had a value of 1.7.

While the invention in detail veran in the drawings and in the foregoing description has been described and described, such illustrations and descriptions should be considered as exemplary and non-limiting. The invention is not limited to the embodiments shown. The scope of the invention and any equivalents are defined in the claims.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 1332781 [0038]
• - EP 10253 [0040]

Claims (11)

A process for the distillation of a biologically produced alcohol from a mash, characterized in that at least one HIDiC column is used for the process. Process according to claim 1, characterized characterized in that it is the biologically produced alcohol is bioethanol. Method according to one of the previous Claims, characterized in that as HIDiC column soil, Packed and / or packed columns are used come. Method according to one of the previous Claims, characterized in that in the HIDiC column Heat pipes (heat pipes) as a heat exchanger between Buoyancy and reinforcing part are used. Method according to one of the previous Claims, characterized in that the mash first goes through a pre-distillation step. Method according to one of the previous Claims, characterized in that in the method several, in the distillation process one behind the other switched HIDiC columns be used. Method according to one of the previous Claims, characterized in that in a first HIDiC column in the reinforcing part of an intermediate distillate is generated, which fed to the stripping section of a second HIDiC column becomes. Method according to one of the previous Claims, characterized in that the distillation column or columns downstream at least one pressure swing adsorber in the distillation process is. Distillation plant comprising at least one HIDiC column, characterized in that they are for the distillation of a biological produced alcohol from a mash. Use of a distillation unit having at least one HIDiC column for the distillation of a biological produced alcohol from a mash. Distillation plant according to claim 9 or use thereof according to claim 10, characterized in that this a) Heatpipes as a heat exchanger between buoyancy and reinforcement part, b) used for the distillation of bioethanol, c) at least has two HIDiC columns, and / or d) at least one pressure swing adsorber having.