Method and device for treating a vegetable raw material

Abstract

A method (100) for treating a vegetable raw material (20) is specified. The method (100) comprises the following steps: a) providing a vegetable raw material (20), (101), b) covering the vegetable raw material (20) completely with a fluid (13), (102), c) fermenting and / or allowing the vegetable raw material (20) to decompose under anaerobic conditions, wherein acids are formed and are dispensed into the fluid (13), (103), d) removing the acidic fluid (24) at least partially, (108), and e) adding further fluid (13), (110). In addition, a device (1) for treating a vegetable raw material (20) is specified.

Description

[0001] Method and device for treating a plant raw material

[0002] The present invention relates to a method and a device for treating a plant raw material, for example for the parameter-controlled microbial digestion of bast fibers.

[0003] Bast fibers are increasingly being used to produce textiles and composite materials because they are much more environmentally friendly than other plastic fibers.

[0004] Bast fibers, as defined by the invention, are fibers that can be obtained from bast fiber plants such as hemp, flax, ramie, kenaf, jute, or nettle. Bast fibers are elongated and thick-walled cells, which means they have only a very narrow cell space or lumen. They are non-lignified and occur in the form of multicellular fiber bundles in the bast of bast fiber plants. The bast fibers are arranged in a ring around the stem pith and run longitudinally along the stem axis.

[0005] Bast fibers are obtained from bast strips or ribbons. In hemp, bast strips can reach a length of 2 m to 2.5 m and a width of 12 mm to 25 mm. Bast strips, in turn, consist of several bast fibers with a cross-section of up to 1 mm, which in turn are composed of elementary fibers with a cross-section of 5 μm to 20 μm. The physiological function of bast fibers is to give the plant strength and stability.

[0006] The main task in the extraction of bast fibers is to separate the fibers from the woody stem pith. The removal of the bast fibers from the plant stem is called fiber pulping. Various techniques are used for fiber pulping, including mechanical and / or chemical processes. The wood removal of the bast fibers was traditionally carried out by hand, but also mechanically, in the steps of breaking, swinging, and hackling. During breaking, the woody stems of the reeded and dried fiber plants are broken into smaller pieces by repeated mechanical action. In the case of flax, a flax breaker or a friction grinder was previously used for this purpose. Retting, e.g. as water retting or field retting (dew retting), is a pre-pulping process in which biological breakdown takes place to minimize the plants' own germs, bacteria, and fungi.Furthermore, de-lignification, the separation of bast from the stem, is facilitated, and the separation of the fibers is promoted. This occurs because the microorganisms (bacteria, fungi) present on the plants destroy the natural adhesives of the plant fibers, particularly pectins and sometimes also hemicelluloses and lignins, and expose the fine cellulose fibers. Traditionally, retting was carried out either in the field (dew retting) or in open water (water retting). Water retting can be carried out in warm water, especially when carried out in containers, where the elevated temperature promotes the solubility of pectins and other saccharides.

[0007] Swinging is the process by which the small wood fragments and short, and therefore lower-quality, fibers resulting from the crushing process are separated from the high-quality long fibers. This was traditionally done using a swing knife, later using swinging machines and swing turbines.

[0008] Hackling is described in DE 34 14437 A1. The principle of hackling is based on the fact that the broken and pre-treated fiber plants, e.g., flax, are repeatedly pulled through a type of iron brush / needle grate, consisting of a board with pointed pins / needles, whereby the fiber bundles are increasingly separated and thus refined.

[0009] A dehulling process is described in DE 10 2015 110 227 A1. It proposes a method for fiber extraction in which the bast is rinsed from the stem using at least one or more high-speed liquid jets. Before treatment, particularly after the separation of woody components and especially after initial cleaning, the plant fibers are subjected to water retting or moist or wet pre-pulping.

[0010] Another automated dehulling process is known from DE 10 2013 013 657 A1, in which the bast bark is separated from the stalk using a "bast dehuller" or by means of tensile force. This process can also be applied to unretted fiber raw material. WO 2012 / 006 118 A2 describes an impact dehulling process in which the stalk is broken using cutting elements or edges attached to rollers and cylinders. This process causes the stalk to break into smaller pieces and be separated from the fiber material. Instead of swings and hackles, modern dehulling machines are equipped with shakers and sieves for the purpose of cleaning the fibers. Furthermore, the shives and dust can be washed off, for example, with a washing liquid (usually water) passed through pressure jet nozzles. Furthermore, dehulling machines are known which, among other things,Use immersion baths and ultrasound to increase the efficiency of deforestation.

[0011] Another process is known from DE 19 703 634 A1, in which an immersion bath with sodium hydroxide, high-speed liquid jets and ultrasound are used in the de-wooding and cleaning of bast fibres.

[0012] For further separation / stretching and cleaning of the fibers, techniques such as combing, carding, or special sawtooth devices can be used. EP 0 745 709 A1 describes a device for mechanically breaking up flax fibers using sawtooth devices (rollers equipped with sawtooths).

[0013] Using conventional mechanical pulping methods, increasing the ratio of fiber length to fiber thickness, i.e. separating the fibers, is only possible to a limited extent.

[0014] Furthermore, it is usually necessary to dry the fibers before mechanical pulping. Residual moisture contents above 17% negatively impact the dewooding results. Both the drying process and the operation of the special pulping machines require considerable energy.

[0015] Furthermore, mechanical deforestation processes are characterized by the fact that they result in an undesirably high proportion of dust and shives and in a significant shortening and damage of the fibers, which ultimately significantly limits the application of the fibers obtained.

[0016] Dew retting and water retting have in common that they are very time-consuming (several weeks), weather-dependent, difficult to control, and associated with significant environmental concerns (DE 10 2006 013 657 A1). The difficulty in controlling / managing the microbial processes means that the optimal retting time, during which the bast can be easily separated from the stalk and the fibers are easily separated but not yet damaged, is also difficult to determine or can only be determined through regular sampling. A further problem with retting is that the microorganisms or their enzymes are not selective, which can result in the microorganisms attacking and destroying not only the cement substances such as pectins, hemicelluloses, and lignins, but also the "useful" fiber substances such as cellulose. This can ultimately lead to a deterioration in fiber quality and a reduction in fiber yield.

[0017] To achieve fiber separation / refining, cementing substances such as pectins and lignins must be removed from the tissue structure of the plant cell walls (primarily the middle lamella). Various chemical, physical, and biological processes, or a combination of these, can be used to achieve this.

[0018] In the chemical processes, various chemicals such as caustic soda, borax, ammonia, trisodium phosphate, surfactants are used, the effect of which is sometimes enhanced by increased pressures and temperatures.

[0019] Such processes are described, among others, in patents EP 0 861 347 B1, DE 19 905 121 A1, and EP 0 706 585 B1. The use of chemicals is not advantageous from an ecological perspective. Furthermore, the use of these sometimes highly aggressive substances requires the use of chemical-resistant systems, machines, and containers. DE 10 2004 036 112 A1 also points out that the recycling of the chemicals or chemical mixtures used is usually not economically viable. Furthermore, chemical treatment of the fibers leads to reduced strength of the resulting fibers.

[0020] Among the physical pulping processes, those that utilize ultrasound, microwaves, or steam pressure are particularly noteworthy. These techniques require specialized equipment, requiring high pressures and temperatures, and are therefore associated with high energy consumption and considerable costs. A pulping process that uses steam and microwaves is disclosed, among others, in DE 19 617 909 A1. Furthermore, this type of treatment of fibers or fiber plants is not selective. Therefore, damage to the valuable fiber substances during the pulping process cannot be ruled out.

[0021] Biological pulping processes – essentially roasting – involve the use of special microorganisms and / or their enzymes that are particularly efficient in breaking down pectins or lignins.

[0022] DE 619779 C describes a roasting process using the pectin-decomposing bacterium Pectinobacter amylophilum.

[0023] DE 10 2006 013 657 A1 describes a roasting process in which the fibres are broken down using selected alkalophilic bacteria of the genera Bacillus and Xanthomonas.

[0024] Furthermore, WO 02 / 092887A1 discloses the use of isolated aerobic and anaerobic bacteria in biological digestion, in particular for the removal of pectins.

[0025] The combination of the presented digestion processes is described, among others, in the following patent specifications: EP 0 706 585 B1 , US 2004 / 0 191 888 A1 , DE 10 2007 030 576 A1 , DE 11 2005 001 792 B4.

[0026] From DE 10 2017 011 741 A1 a method for an enzymatic-surfactant fiber digestion of bast strips is known, which provides that bast strips or bast fibers are held at one end by a holder and guided into a container to be fermented, washed and rinsed in a liquid.

[0027] Furthermore, WO 2006 / 100560 A1 discloses a fiber pulping plant comprising a reactor, a closure device, and a control system, as well as a method for the microbial extraction of plant fibers. In the reactor, the fiber-containing material is covered with a liquid for retting, whereby the fiber-containing material is decomposed under anaerobic conditions. The special feature is that retting takes place after the vibrating process. This has the disadvantage that the fibers are mechanically prestressed before retting, resulting in an increased proportion of short fiber waste. Alternatively, the stems can be peeled, but this involves increased labor and is only applicable to plant raw materials with stems.

[0028] CN 101 050 549 A discloses a fiber pulping plant with a reactor in which the fiber-containing material is covered by a liquid. The supply of oxygen creates aerobic conditions in the reactor. This oxygen supply is energy-intensive. Furthermore, the targeted introduction of microorganisms is required. This process can lead to adverse fiber properties and is typically accompanied by unpleasant odors.

[0029] Against this background, the object of the invention is to provide a method and a device for treating a plant raw material with which the disadvantages described above can be at least partially avoided. In particular, an environmentally friendly and energetically advantageous pulping process for obtaining plant fibers and other plant components would be desirable.

[0030] The problem is solved by the subject matter of the independent claims. The dependent claims relate to embodiments of these solutions.

[0031] A first aspect of the invention relates to a method for treating a plant raw material. The plant raw material can be, for example, hemp plants, flax plants, nettle plants, ramie plants, kenaf plants, jute plants, banana plants, palm lily plants, or pineapple plants, or any mixture of the aforementioned plants. The method can preferably be used for treating plants with a fiber content, e.g., bast fiber plants.

[0032] The method comprises the following steps: a) providing a plant raw material, b) completely covering the plant raw material with a fluid, c) fermenting and / or decomposing the plant raw material under anaerobic conditions, whereby acids are formed and released into the fluid, d) at least partially removing the acidic fluid and e) adding further fluid.

[0033] The fluid can, in particular, be a liquid. The fluid can be water or a mixture of water and, for example, lactic acid bacteria, which is also called fermentation liquid. The process can be used in particular for obtaining bast fibers. The process can also be applied to obtaining leaf fibers, e.g., from the leaf sheaths of the banana plant or from the palm lily.

[0034] In addition to the microbial digestion of fibers, the proposed process can be used in the anaerobic fermentation of any organic biomass, e.g., for the purpose of producing short-chain organic acids. This significantly expands the range of potential applications.

[0035] The plant raw material can be provided, for example, by conveying the plant raw material, such as bundles of hemp stalks, into a reactor with at least one reactor chamber or by placing it into a reactor chamber of a reactor. The reactor is also referred to below as a container.

[0036] In other words, the reactor can be filled and emptied discontinuously, meaning the process can be carried out discontinuously. Alternatively, the process can be carried out continuously, for example, by continuously feeding the plant raw material into the reactor chamber using a conveying device, e.g., a conveyor belt, and continuously removing it after the completion of the fermentation and / or decomposition process.

[0037] The plant raw material is then completely covered by the fluid, for example by conveying the plant raw material into an already existing fluid and / or subsequently adding fluid.

[0038] The reactor may have an opening, which provides a connection to the environment and can be decoupled from the environment by means of a closure device such that an anaerobic environment is created in the reactor chamber and the plant raw materials in the reactor undergo a fermentation, decomposition, or a combination of these processes. A control device or controller and a sensor may be provided, with the sensor recording measured values. Means are provided by which the process values ​​can be regulated within a definable value range.

[0039] In one embodiment, the closure device can be a gas lock with a connection, wherein a gas sensor is provided for determining the oxygen and / or nitrogen content, with the nitrogen content in the gas lock being regulated by the controller. Furthermore, a pH sensor for measuring the pH value of the fluid and a filter for separating acids can be provided, with the fluid being passed through the filter as soon as the pH value falls below a value between 5.8 and 3.5.

[0040] After the plant raw material has been completely covered with the fluid, it is fermented and / or decomposed. This occurs under anaerobic conditions, i.e., in the absence of oxygen (= anaerobic conditions), the fermentation of the introduced plants now begins. These anaerobic conditions enable the conversion of pectin and other organic substances into short-chain organic acids, particularly acetic acid and lactic acid, through the activity of hydrolytic and fermenting microorganisms. Furthermore, intermediate metabolites such as butyric acid, propionic acid, valeric acid, and caproic acid can be formed during fermentation. Which acids are formed and in what quantities depends primarily on the specific plant raw material. The acids formed are released into the fluid.

[0041] The microorganisms, e.g., bacteria, can preferably be added together with the plant raw material, meaning that microorganisms that naturally occur on the plants can be used for the fermentation and / or decomposition process. Inoculation with microorganisms or the additional addition of microorganisms can advantageously be omitted, making the proposed process cost-effective. Sterilization is also not necessary at any stage of the process.

[0042] As a result of the formation of organic acids, the pH of the fluid drops from the initial pH of approximately 8 to between 5.8 and 3.5, with varying residence times required to reach this pH. After reaching a pH of 5.8 to 3.5, the activity of the fermenting bacteria gradually ceases, meaning that no more organic material (especially pectin and hemicelluloses) is decomposed.

[0043] In a further step, at least a partial liquid exchange is necessary to stimulate the microorganisms to resume their activity, namely the decomposition of organic material, especially pectin and hemicellulose. To do this, a portion of the acidic liquid in the fermenter is removed and replaced with fresh water. This lowers the concentration of organic acids in the container, which consequently leads to an increase in the pH value.

[0044] The fluid exchange can be carried out periodically or continuously at specified times, for example, depending on the pH value as described below. Preferably, the fluid exchange can be carried out in such a way that a predefined fluid level in the reactor is kept as constant as possible. Further preferably, the fluid exchange can be carried out in such a way that the plant raw material is always completely covered with the fluid and anaerobic conditions always prevail.

[0045] For example, bast fiber plants, tied in bundles, can be placed in a reactor for microbial fiber digestion. The bundles can be placed in the reactor or container standing upright, lying down, or suspended using a device. The container can be filled with a fluid so that the plants to be digested are completely covered by the fluid. Furthermore, the container is sealed from the environment in such a way that anaerobic conditions are created. This is necessary for the fermentation - the retting - to proceed optimally.

[0046] After the fermentation and / or decomposition process is complete, the resulting biomass can be separated from the fluid and rinsed with water, for example, for neutralization and purification. Subsequently, if a fibrous plant raw material is used, the fibers can be separated from the stems. This separation can be performed either in the wet or dried state, meaning the biomass or fibers can be dried before and / or after separation.

[0047] According to various embodiments, the method may comprise filtering the acidic fluid.

[0048] Filtration can be performed using a filter. The filter can be a flow-through filter, for example, with a filter surface with a pore size of 0.2 μm to 0.9 μm. The filter can be permeable to short-chain organic acids such as acetic acid, lactic acid, propionic acid, and / or butyric acid. This allows unreacted biomass and microorganisms to remain in the flowing fluid, while the acids formed can be removed. In other words, the extracted acidic liquid can be passed through a filter with an average pore size of 0.2 μm to 0.9 μm. This ensures that unreacted biological material and the beneficial bacteria are retained and returned to the container. This allows the formed microculture to remain in the container, allowing the fermentation and / or decomposition process to proceed uninterrupted.This can simplify process control and ensure consistent product quality.

[0049] Alternatively, the acidic fluid can be separated using vacuum filtration. This has the advantage that the organic acids are not only extracted or removed, but also simultaneously enriched, meaning the water is removed from the extracted acid solution. The more concentrated acid solution can subsequently be used more advantageously for material and / or energy recovery. In conventional filtration, however, water also passes through the filter, which is why the permeate usually has to be "concentrated" in a subsequent process step before further use.

[0050] According to further embodiments, the method may comprise determining the pH value of the fluid, e.g. by means of a pH sensor, wherein the fluid exchange, ie the at least partial removal of the acidic fluid and the addition of further fluid, is carried out as soon as a pH threshold value in a range between 3.5 and 5.8 is undershot.

[0051] This ensures that good conditions for the fermentation and / or decomposition process are continuously present and can take place without interruption.

[0052] According to further embodiments, the fluid exchange will be carried out repeatedly until the pH value of the fluid no longer changes, for example for a predefined period of time.

[0053] A time period can be specified for a possible change in the pH value, ie it can be specified, for example, that the fluid exchange is to be carried out repeatedly until the pH value no longer changes or changes only slightly, for example by less than 0.2 or less than 0.1, over a period of 3 days. For example, a pH value can also be regarded as unchanged if the change in the pH value is less than 5% or less than 2% compared to a pH value of a previous pH value measurement at intervals of at least 12 hours or at least 24 hours.

[0054] In other words, if necessary, the fluid exchange step can be repeated several times until the pH value does not drop again despite the exchange, or until the bast fibers easily detach from the stem and can then be easily separated mechanically. To determine this optimal time, regular pH checks or continuous pH determination are recommended.

[0055] According to further embodiments, the method may comprise regulating the temperature of the fluid to a temperature in a temperature range between 15 °C and 38 °C.

[0056] For this purpose, a temperature sensor can be provided to measure the fluid temperature, whereby the fluid can be passed through a heat exchanger for temperature control as soon as the target temperature exceeds or falls below a value between 15 °C and 38 °C.

[0057] In other words, the vessel or reactor and its contents can be tempered to a temperature of 15 °C up to 38 °C if necessary. This temperature has proven to be optimal for the fermentation process in general practice. Lower process temperatures can also be used, but this may increase the required roasting time.

[0058] According to further embodiments, the method may comprise circulating the fluid, e.g. by means of a circulation pump.

[0059] To evenly distribute the microorganisms in the fermenter and to compensate for any temperature and concentration differences that may exist within the container, the contents of the container can be circulated during fermentation using a pump. The circulation also ensures that the plants in the container are continuously rinsed, which can promote the detachment of the bast strips from the woody stem pith and also the separation of the fiber bundles. At the same time, the gentle movement of the container contents can cause the continuous removal of already decomposed or partially decomposed biological material from the plant surface. This can counteract the formation of mucus layers. Mucus layers can significantly hinder microbial processes. The advantage of rinsing during biological

[0060] Fiber pulping is also described in DE 10 2017 011 741 A1.

[0061] According to further embodiments, the method may comprise carding fibers of the plant raw material obtained after the liquid exchange has ended.

[0062] Carding can be performed with the fibers separated from the stems, preferably after the fibers have been dried. Aggressive degrinding (shredding and removal of the lignified stem pith) using crushers, rockers, and hackles, or machines as described in WO 2012 / 006118 A2 (impact pulping) is not necessary either before or after microbial pulping. In other words, the fibers obtained after the liquid exchange has ended can be carded directly, i.e., immediately, without the need for further fiber pulping. The process presented here enables gentle yet extremely efficient fiber pulping, with the resulting fibers being largely free of surface adhesions or contamination by dust and shives.The light carding of the fiber bundles or bast strips microbially digested according to the proposed process is sufficient to obtain fine, elastic, yet tear-resistant fibers. By avoiding harsh mechanical techniques for digesting and cleaning the fibers, the process presented here does not damage the fiber structure or shorten the fibers.

[0063] After microbial digestion, the bast fibers can be easily separated from the stem pith, e.g. manually or, for example, by means of a high-speed liquid jet, as described in DE 19 703 634 B4.

[0064] According to further embodiments, the process may involve the material or energy recovery of the acidic fluid. The energy recovery may include the generation of biogas.

[0065] In other words, the acidic liquid from the container can be recycled for material or energy purposes. Energy recovery can be achieved through the generation of biogas, which can be used to provide electricity and / or heat. The generated electricity and waste heat can be fed directly into the digestion process. This represents an important economic advantage and also offers the possibility of environmentally friendly energy generation from renewable resources.

[0066] According to further variants, the plant raw material can be provided fresh or green and / or dried.

[0067] In other words, both green, i.e., fresh, and dry material can be fed into the process according to the invention. This means that, with the exception of any drying, untreated plant raw material can be used directly. In particular, no vibrating takes place before the plant raw material is completely covered with the fluid, i.e., process steps b) to e) can be performed before vibrating.

[0068] However, if necessary, the fiber plants to be digested can be mechanically pretreated, e.g., using crushers, before microbial digestion. However, mechanical pretreatment is not mandatory.

[0069] A further aspect of the invention relates to a device for treating a plant-based raw material. The device comprises a reactor, the reactor comprising: at least one reactor chamber that can be filled with a fluid, an opening configured to supply a plant-based raw material into the reactor chamber, a closure device configured to close the opening such that an anaerobic environment can be formed in the reactor chamber, a fluid removal device configured to remove the fluid from the reactor chamber, and a fluid supply device configured to supply the fluid to the reactor chamber.

[0070] The proposed device may, for example, be suitable for implementing the proposed method explained above. Therefore, the above explanations for explaining the method also serve to describe the device. The advantages of the method are correspondingly associated with the device.

[0071] The device can be designed as a fiber pulping system. An exemplary fiber pulping system for the microbial pulping of bast fibers from plant raw materials, in which plant raw materials, such as hemp stalk bundles, are treated, comprises a reactor with at least one reactor chamber filled with a fluid. The reactor has an opening, wherein the opening represents a connection to the environment, which is decoupled from the environment by means of a closure device, so that an anaerobic environment is created in the reactor chamber and the plant raw materials in the reactor are subjected to a fermentation, decomposition process, or a combination of these. At least one controller and one sensor can be provided, wherein measured values ​​are recorded by means of the sensor, wherein means are provided by means of which the measured values ​​can be regulated within a definable value range.

[0072] The fluid removal device can be based on the principle of vacuum filtration, so that the acidic fluid can be removed from the reactor chamber by means of vacuum filtration.

[0073] According to various embodiments, the device can comprise a filter designed to filter the fluid to be removed by means of the fluid removal device.

[0074] The filter can be a flow-through filter with a pore size of 0.2 μm to 0.9 μm and is permeable to short-chain organic acids such as acetic acid, lactic acid, propionic acid, and / or butyric acid. The filter can be designed, in particular, for the separation of acids, and the fluid can be pumped through the filter using a pump.

[0075] According to further embodiments, the device can comprise a control device. The control device can be configured to generate and output control signals based on a pH value of a fluid present in the reactor chamber, which cause at least partial removal of the fluid from the reactor chamber and the addition of further fluid to the reactor chamber.

[0076] Alternatively or additionally, the control device can be designed to generate and output control signals based on a temperature of the fluid present in the reactor chamber, which cause heating or cooling of the fluid in the reactor chamber.

[0077] Furthermore, the device can have a pH sensor for measuring the pH value of the fluid and a temperature sensor for measuring the fluid temperature. The pH sensor and / or the temperature sensor can be operatively connected to the control device via signal technology, so that sensor signals generated by the sensors can be transmitted to the control device, received by the control device, and processed by the latter. The control signals are processed according to one or more routines based on instructions or code programmed in the control device. The generated control signals are output to actuators in response to the processed sensor signals and bring about the described measures, i.e., the removal and addition of fluid and / or the heating or cooling of the fluid.

[0078] A pump, e.g., a circulation pump, can be provided as the actuator for temperature control, with the fluid being pumped through a heat exchanger by means of a circulation pump. At least one pump, e.g., a pressure pump, can also be provided as the actuator for pH control, by means of which fluid is pumped into or out of the reactor.

[0079] According to further embodiments, the device may comprise a circulation pump designed to circulate the fluid in the reactor chamber.

[0080] According to further embodiments, the closure device can be a gas lock with a gas connection, whereby the nitrogen content in the gas lock can be regulated via the gas connection.

[0081] Additionally, a gas sensor can be provided, by means of which the oxygen and / or nitrogen content can be determined. The nitrogen content in the gas lock can be regulated based on the nitrogen content determined by the gas sensor. For this purpose, the control device can be configured to generate and output control signals based on the sensor signal of the nitrogen sensor, which cause a change in the nitrogen content in the gas lock.

[0082] The oxygen content can be used to check the tightness of the gas lock. If the oxygen content is too high, it can be assumed that there is unwanted ingress of outside air, i.e., that the gas lock is leaking. Since this can negatively impact the desired anaerobic conditions, appropriate countermeasures, such as repairing or replacing the gas lock, would be advisable. Alternatively, the closure device can be designed as a rotary valve. This allows for a simple, continuous implementation of the proposed process.

[0083] Further advantages of the present invention are apparent from the figures and the accompanying description, which will explain the invention in more detail below. They show:

[0084] Figure 1 is a schematic diagram of a device for treating a plant raw material in the form of a fiber pulping plant;

[0085] Figure 2 shows an exemplary fiber pulping plant for a continuous process;

[0086] Figure 3 shows a flow chart of an exemplary process.

[0087] It is understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. It is also understood that the features of the various exemplary embodiments described herein may be combined with one another unless specifically stated otherwise. The following detailed description is therefore not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.

[0088] In the figures, identical or similar elements are designated by identical reference numerals where appropriate. The term "and / or" used herein, when used in a series of two or more elements, means that each of the listed elements may be used alone, or any combination of two or more of the listed elements may be used.

[0089] Figure 1 shows a schematic diagram of an embodiment of a device for treating a plant raw material 20 in the form of a fiber pulping plant 1. The fiber pulping plant 1 can be used, for example, to carry out the method 100 for treating a plant raw material 20 described below with reference to Figure 3. The fiber pulping plant 1 has a reactor 2 with a reactor chamber 3, which serves to accommodate the plant raw material 20 or fiber raw material to be pulped and in which the microbial pulping takes place by means of anaerobic fermentation. In the embodiment, the plant raw material 20 is used as a bundle. The reactor chamber 3 can be filled with a fluid 13, e.g., water, optionally mixed with bacterial cultures.

[0090] The fill level h of the fluid 13 during operation of the fiber pulping system 1 is marked with the letter h in Fig. 1. The fill level h can be influenced by fluid removal by means of the fluid removal device 27 and fluid supply by means of the fluid supply device 28.

[0091] The dimensions of reactor 2, also called the fermenter, can be adapted to the fiber raw material to be digested or according to the fiber demand. For processing larger quantities of fiber raw material, several tanks can be connected in parallel.

[0092] To facilitate loading and unloading through the opening 6 of the reactor 2, a removable holder can be used, which in this embodiment is designed as a basket 7. The feed device 14 and the removal device 15 for feeding and removing the plant material are shown only schematically with arrows in Fig. 1. Suitable construction materials for the reactor 2 and its components include stainless steel, but in principle, glass, plastic, or fiberglass. Insulation may be appropriate depending on the selected operating temperature.

[0093] A filter 4 with an average pore size of 0.2 to 0.9 pm enables the separation of the acidic fluid 24 with short-chain organic acids such as acetic acid, lactic acid, propionic acid, and butyric acid, as well as the retention of unreacted biomass and microorganisms. This filter 4 is used when a portion of the acidic liquid is exchanged for fresh water to increase the pH in the fermenter. In the exemplary embodiment, the filter 4 consists of a ceramic membrane filter with an average pore size of max. 0.2 to 0.9 pm. The function of the filter is to separate organic acids and to retain fermenting microorganisms and unreacted biomass. The filter 4 is a flow-through filter, with the retained microorganisms and undecomposed biomass being pumped back into the reactor 2.

[0094] A pressure pump 8 enables the fluid 13 to be supplied to the filter 4. The pressure pump 8 upstream of the filter 4 applies a sufficiently high pressure to the acidic liquid taken from the reactor chamber 3 in order to achieve optimal filter performance.

[0095] Reactor chamber 3 is filled and emptied through opening 6. Filling and emptying can be done manually or using an automated device. The digested plants can be removed from reactor 2 through opening 6 manually or using an automated device.

[0096] Opening 6 can be closed by a closure device 17 such that anaerobic conditions can be created in the reactor chamber 3. In the exemplary embodiment, opening 6 is closed by a gas lock designed to allow an anaerobic process to take place in the reactor. The gas lock can be a hood filled with nitrogen.

[0097] A circulation pump 9 primarily enables the slow movement of the fluid 13 for the purpose of heating it to the desired process temperature via the external heat exchanger 5. The function of the external heat exchanger 5 is to temper the fluid to the desired digestion temperature.

[0098] Another goal of circulation is to create homogeneous conditions in reactor chamber 3 regarding acid concentration, temperature, and microbial activity. Furthermore, circulation serves to remove decomposed plant particles from the surface of the plants and to loosen the bond between the digested fibers and the stem pith.

[0099] The control device 12 regulates the temperature in the reactor 2 and the flow rates through the pressure pump 8 or the filter 4, as well as the circulation pump 9 for circulating the fluid 13 through the heat exchanger 5. For this purpose, corresponding control signals 26a, 26b are generated and transmitted to the pumps 8, 9. The control is based on the measured values ​​from the temperature sensor 11 and the pH sensor 10, which are transmitted to the control device 12 via sensor signals 25a, 25b. Further control signals 26d can be generated by the control device 12 and transmitted to the fluid supply device 28 to effect a supply of fresh fluid 13 and to maintain the fill level h.

[0100] The control device 12 also receives sensor signals 25c from a gas sensor 22, which can be used to determine the gas composition in the gas lock or closure device 17. Based on the gas composition, the control device 12 generates a control signal 26c, which is transmitted to a gas connection 23 to regulate a gas supply to the gas lock.

[0101] Some advantages of the proposed method are summarized below:

[0102] No mechanical stirring elements are used. This prevents the material to be digested from wrapping around the agitator. No energy is required for stirring. The gentle movement of the fluid 13 used in the present process by means of the circulation pump 9 fulfills several functions: stirring; transporting the fluid 13 to the heat exchanger and back to the reactor 2; and rinsing, thus cleaning and loosening the fibers to be digested.

[0103] De-wooding of the material to be digested - e.g. using a bast peeler as described in DE 10 2013 013 657 A1 - is not necessary before microbial digestion.

[0104] The microbial digestion process presented here is suitable for the extraction of fibers from all plant raw materials

[0105] The microbial digestion process presented here is suitable for the extraction of plant stems, as these are not destroyed by the proposed process.

[0106] In addition to providing fiber, the process also enables the extraction of short-chain organic acids such as acetic acid and lactic acid, possibly also propionic acid and butyric acid, as well as other acids produced during fermentation from the microbially converted plant material. These can be used either for material or energy recovery. Energy recovery can be achieved through the production of biogas and its conversion into electricity and heat. The electrical and thermal energy generated can be fed into the microbial digestion process or used for other purposes. This reduces the energy consumption of the digestion process and fiber recovery.

[0107] An important economic advantage of the microbial digestion presented here compared to existing processes results from the simultaneous provision of plant fiber bundles, stem pith and organic acids for subsequent material / energetic use.

[0108] No chemicals are used, so there's no need for complex disposal or recycling of chemicals or chemical mixtures after digestion.

[0109] Apart from acid resistance, no special requirements are placed on the pulping system. No special machinery is required for pulping. This significantly reduces energy and investment costs, which ultimately lowers the cost of fiber extraction. No high temperatures or pressures are required for the microbial pulping presented here. This results in gentle fiber pulping and reduced energy requirements compared to pulping processes, some of which are very complex from a technical, energetic, and economic perspective, and are described, among others, in DE 19 617 909 A1 and EP 0 115 172 B1.

[0110] The digestion is carried out in a hermetically sealed reactor 2. This process has no negative impact on the environment. The acidic liquid extracted in the proposed process can (and should) be fully utilized or recycled in downstream processes. This is a significant advantage over all currently practiced digestion processes.

[0111] Microbial digestion is intensified by regulating the acid concentration (or pH value). This increases fiber yield and improves the further processability of the fibers—ultimately, the fiber quality.

[0112] Figure 2 shows a continuously operating fiber pulping plant 1 with a feed device 14 for bundled plant material, i.e., bundles, as the plant raw material 20. The bundles are conveyed through the opening 6a, above which a gas lock 17a is arranged, into the reactor 2 or its reactor chamber 3. The reactor chamber 3 is filled with the fluid.

[0113] The conveyor belt 19 conveys the bundles 20 through the reactor chamber 3, with the bundles being completely immersed in the fluid 13. The bundles 20 exit the reactor 2 again via the removal device 15 or the opening 6b with the hood 17b arranged above it. From there, the bundles 20 are transported to the next processing step, as described above and below.

[0114] Figure 3 shows a flow diagram of an exemplary method 100 for treating a plant raw material 20, e.g., bast fiber plants. The method 100 can be carried out, for example, using the fiber pulping system explained with reference to Figure 1 or 2. After the plant raw material 20 has been provided in step 101, it is completely covered with a fluid 13 in step 102, and an anaerobic environment is created, so that a fermentation and / or decomposition process begins in step 103, whereby acids are formed and released into the fluid 13. During the fermentation and / or decomposition, the fluid is circulated (step 104), and the temperature of the fluid 13 is regulated to a temperature within a temperature range between 15°C and 38°C (step 105).

[0115] For example, after a certain period of time has elapsed, the pH of the fluid is determined in step 106. This decreases with ongoing fermentation and / or decomposition due to the acids formed and released into the fluid 13. In step 107, a check is made to see whether the pH changes over a predefined period of time, e.g., a period of 3 days. It is therefore possible to check within the specified period whether a change in the pH occurs. If this is the case, i.e., the pH changes, a check is made in step 108 to see whether the determined pH falls below a pH threshold, e.g., a pH of 5.0. If this is the case, the now acidic fluid 13 is filtered off and at least partially removed in steps 109 and 110. The removed acidic fluid 13 can be recycled for material or energy purposes in step 114.

[0116] In step 111, additional or new fluid 13 is added so that the fill level h remains essentially constant. The method 100 then continues with steps 103, 104, and 105, i.e., the fermentation or decomposition is continued with circulation and temperature control.

[0117] If, however, it is determined in step 108 that the pH threshold is not yet undershot but continues to change, the method 100 is initially continued unchanged with steps 103, 104 and 105.

[0118] If it is determined in step 107 that the pH value remains unchanged over the specified period, it can be assumed that the fermentation and / or decomposition process is complete and that a biomass with digested fibers is now present. The biomass is removed from the reactor in step 112 and subsequently rinsed with water in step 113. Further processing can then follow, e.g., by separating the fibers from the stem before and / or after drying.

[0119] Preferred features of the invention are:

[0120] 1. A process for the microbial extraction of bast fibres or fibres from plant raw materials, in which plant raw materials, such as hemp stalk bundles, are conveyed in a reactor with at least one reactor chamber so that they are completely covered by a fluid, the reactor having an opening, the opening constituting a connection to the environment which, by means of a closure device, decouples the reactor chamber from the environment such that an anaerobic environment is created in the reactor chamber and the plant raw materials in the reactor are subject to a fermentation or decomposition process or a combination of these, and in that at least one controller and one sensor are provided, measured values ​​being recorded by means of the sensor, means being provided by means of which the measured values ​​can be regulated within a definable value range.

[0121] 2. The method according to sentence 1, wherein the closure device is a gas lock with a connection, wherein a gas sensor is provided by means of which the oxygen and / or nitrogen content is determined, wherein the nitrogen content in the gas lock is regulated by means of the control system. 3. The method according to sentence 1 or 2, wherein a pH sensor is provided for measuring the pH value of the fluid and a filter is provided for separating acids, wherein the fluid is passed through the filter as soon as the pH value falls below a value between 5.8 and 3.5.

[0122] 4. Method according to one of sentences 1 to 3, wherein a temperature sensor is provided for measuring the fluid temperature, wherein the fluid is passed through a heat exchanger for temperature control as soon as the target temperature exceeds or falls below a value between 15 °C and 38 °C.

[0123] 5. Fiber digestion plant for the microbial digestion of bast fibers from plant raw materials, in which plant raw materials, such as hemp stalk bundles, are treated, comprising a reactor with at least one reactor chamber filled with a fluid, the reactor having an opening, the opening forming a connection to the environment which can be decoupled from the environment by a closure device, so that an anaerobic environment is created in the reactor chamber and the plant raw materials in the reactor are subject to a fermentation, decomposition process or a combination of these, and that at least one controller and one sensor are provided by means of which measured values ​​are recorded, means being provided by means of which the processes in the reactor can be regulated within a definable value range.

[0124] 6. Fiber pulping system according to sentence 5, wherein the closure device is a gas lock with a connection, wherein a gas sensor is provided by means of which the oxygen and / or the nitrogen content can be determined and the nitrogen content in the gas lock can be regulated via the connection.

[0125] 7. Fiber pulping plant according to sentence 5 or 6, wherein a pH sensor for measuring the pH value of the fluid and a filter for separating acids are provided, wherein the fluid can be pumped through the filter by means of a pump.

[0126] 8. Fiber pulping system according to one of clauses 5 to 7, wherein a temperature sensor is provided for measuring the fluid temperature, wherein the fluid can be pumped through a heat exchanger by means of a circulation pump for temperature control. 9. Fiber pulping system according to one of clauses 5 to 8, wherein the filter is a flow-through filter having a filter surface with a pore size of 0.2 pm to 0.9 pm and is permeable to short-chain organic acids such as acetic acid, lactic acid, propionic acid, and / or butyric acid, wherein unreacted biomass and microorganisms remain in the flowing fluid.

[0127] List of reference symbols

[0128] 1 fiber pulping plant

[0129] 2 reactors

[0130] 3 reactor room

[0131] 4 filters

[0132] 5 heat exchangers

[0133] 6; 6a, 6b opening

[0134] 7 basket

[0135] 8 pressure pump

[0136] 9 Circulation pump

[0137] 10 pH sensor

[0138] 11 Temperature sensor

[0139] 12 Control device

[0140] 13 Fluid

[0141] 14 Feeding device

[0142] 15 Withdrawal device

[0143] 17; 17a, 17b locking device

[0144] 19 Conveyor belt

[0145] 20 plant raw material

[0146] 22; 22a, 22b gas sensor

[0147] 23 Gas connection

[0148] 24 acidic fluid

[0149] 25a, 25b, 25c Sensor signal

[0150] 26a, 26b, 26c, 26d control signal

[0151] 27 Fluid extraction device

[0152] 28 Fluid supply device

[0153] 100 procedures

[0154] 101 Providing a plant-based raw material

[0155] 102 Completely covering the plant raw material with a fluid 103 Fermenting and / or decomposing the plant raw material under anaerobic conditions, whereby acids are formed and released into the fluid

[0156] 104 Circulating the fluid 105 Controlling the temperature of the fluid to a temperature in a temperature range between 15 °C and 38 °C

[0157] 106 Determining the pH value of the fluid

[0158] 107 Check if the pH value changes

[0159] 108 Check whether the pH value falls below a pH threshold 109 At least partially remove the acidic fluid

[0160] 110 Filtering the acidic fluid

[0161] 111 Adding more fluid

[0162] 112 Removal of biomass

[0163] 113 Flushing of the extracted biomass 114 Material or energetic utilization of the acidic fluid h Filling level

Claims

Patent claims 1. Method (100) for treating a plant raw material (20), the method (100) comprising the following steps: a) providing a plant raw material (20) (101), b) completely covering the plant raw material (20) with a fluid (13) (102), c) fermenting and / or decomposing the plant raw material (20) under anaerobic conditions, whereby acids are formed and released into the fluid (13) (103), d) at least partially removing the acidic fluid (24) (109) and e) adding further fluid (13) (111).

2. Method (100) according to claim 1, comprising: Filtering the acidic fluid (24) (1109).

3. Method (100) according to one of the preceding claims, comprising: determining the pH value of the fluid (13) (106), wherein steps d) and e) are carried out as soon as a pH threshold value in a range between 3.5 and 5.8 is undershot.

4. Method (100) according to one of the preceding claims, wherein steps d) and e) are carried out repeatedly until the pH value of the fluid (13) no longer changes.

5. The method (100) according to any one of the preceding claims, comprising: controlling the temperature of the fluid (13) to a temperature in a temperature range between 15 °C and 38 °C (105).

6. Method (100) according to one of the preceding claims, comprising: circulating the fluid (13) (104).

7. Method (100) according to one of the preceding claims, comprising: carding fibers of the vegetable raw material (20) obtained after step e).

8. Method (100) according to one of the preceding claims, comprising: material or energetic utilization of the acidic fluid (24) (114).

9. Method (100) according to one of the preceding claims, wherein in step a) the plant raw material (20) is provided fresh and / or dried.

10. The method (100) according to any one of the preceding claims, wherein the plant raw material (20) is selected from a group comprising hemp plants, flax plants, nettle plants, ramie plants, kenaf plants, jute plants, banana plants, palm lily plants and pineapple plants.

11. Device (1) for treating a plant raw material (20), the device (1) comprising a reactor (2) with: at least one reactor chamber (3) which can be filled with a fluid (13), an opening (6; 6a, 6b) designed to feed the plant raw material (20) into the reactor chamber (3), a closure device (17; 17a, 17b) designed to close the opening (6; 6a, 6b) such that an anaerobic environment can be formed in the reactor chamber (3), a fluid removal device (27) designed to remove the fluid (13) from the reactor chamber (3), and a fluid supply device (28) designed to supply the fluid (13) to the reactor chamber (3).

12. Device (1 ) according to claim 11 , comprising: a filter (4) designed to filter the Fluid extraction device (27) for the fluid (13) to be extracted.

13. Device (1) according to claim 11 or 12, comprising a control device (12) which is designed to generate and output control signals (26a, 26b, 26c, 26d) based on a pH value of a fluid (13) present in the reactor chamber (3), which bring about an at least partial removal of the fluid (13) from the reactor chamber (3) and an addition of further fluid (13) into the reactor chamber (3) and / or to generate and output control signals (26a, 26b, 26c, 26d) based on a temperature of the fluid (13) present in the reactor chamber (3), which bring about a heating or cooling of the fluid (13) in the reactor chamber (3).

14. Device (1) according to one of claims 11 to 13, comprising: a circulation pump (9) designed to circulate the fluid (13) in the reactor space (3).

15. Device (1) according to one of claims 11 to 14, wherein the closure device (17; 17a, 17b) is a gas lock with a gas connection (23), wherein the nitrogen content in the gas lock (22; 22a, b) can be regulated via the gas connection (23)

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