FIELD OF THE INVENTION

[0001] The present invention relates to a thermomechanical pulp process, and particularly to processing of wood chips in connection with production of thermomechanical pulp.

BACKGROUND OF THE INVENTION

[0002] Thermomechanical pulp (TMP) is pulp made from wood fibres by processing. Barked timber is usually first reduced to small wood chips. In a thermomechanical pulp process, the wood chips are preheated prior to a refining process. Wood chip refining refers to beating of wood chips, wherein the wood chips are subjected to a mechanical force during a crushing or refining activity. In such a case, heat and steam are formed, softening wood lignin and other molecular bonds between fibres and thus separating single fibres from one another. The formed steam may also be used for preheating the wood chips under pressure or at a normal air pressure. In preheating, lignin softens, whereby the fibres detach more easily from one another and are more intact and longer.

[0003] TMP may be used e.g. for producing newsprint, LWC (light weight) and SC (supercalandered) papers as well as cardboard.

[0004] A problem with the aforementioned arrangement is that the production of thermomechanical pulp consumes quite a large amount of energy.

BRIEF DESCRIPTION OF THE INVENTION

[0005] An object of the invention is thus to provide a method and an apparatus for implementing the method so as to alleviate the aforementioned problem. The object of the invention is achieved by a method, a system, an impregnating device, a dosing unit, an optimizing unit, and a use that are characterized by what is stated in the independent claims. Preferred embodiments of the invention are disclosed in the dependent claims.

[0006] The invention is based on using one or more ligninolytic enzymes or one or more enzymes having an otherwise decomposing effect on a wood-based material for preprocessing the wood-based material in an impreg- nating device prior to an actual refining process. The method comprises enzyme recycling, wherein an enzyme being discharged from the impregnating device is at least partly recycled back to the impregnating device by recycling means. The system further comprises measuring means for measuring en- zyme(s) activity. A measurement result is communicated to control means configured to control dosing means for dosing the enzyme on the basis of the measurement result.

[0007] An advantage of the present arrangement is that it provides a biological method for processing a wood-based material prior to the actual thermomechanical process, thus making the system more environment-friendly as compared e.g. with a situation wherein a wood-based material is processed with chemicals (cTMP or chemi-ThermoMechanical Pulp) or with a situation involving no processing of the wood-based material prior to the actual thermomechanical process.

BRIEF DESCRIPTION OF THE FIGURES

[0008] The invention is now described in closer detail in connection with the preferred embodiments and with reference to the accompanying drawing, in which

Figure 1 shows a system according to an exemplary embodiment of the present solution.

DETAILED DESCRIPTION OF THE INVENTION

[0009] The present solution relates to a method and a system for optimizing preprocessing of fibre-containing pulp, wood chips and/or other wood-based material by using enzymes in an impregnating apparatus. In the method, the activity of enzymes may be measured continuously by means of enzyme-selective sensors (e.g. by biosensors or by ordinary sensors, such as by means of pH measurement or pH sensors). In the method, an enzyme mixture (or at least a part of it) is recycled preferably in an impregnating device. The recycling may take place e.g. such that an enzyme or an enzyme- containing liquid is recovered from a bottom part of the device and it is recycled to an upper part thereof.

[0010] In an exemplary embodiment of the present solution, enzymes are dosed in to an impregnating device by pumping, and the dosing of the enzymes is optimized for processing of wood (wood chips, wood shavings or the like) for the production of eTMP (enzyme ThermoMechanical Pulp). The purpose of enzyme dosing is to soften the pulp or wood chips so as to facilitate the actual thermo-refining process, enabling energy costs caused by the production of thermomechanical pulp to be reduced. In such a case, the enzymes to be used are ligninolytic or pectinolytic ones and/or ones having an otherwise decomposing effect on the wood-based material. Optimization of the amount of enzymes in the process by recycling and dosing an enzyme mixture in to an impregnating apparatus is based on measuring the enzyme activity in an impregnating container and/or in a recycling line e.g. by means of appropriate biosensors. The activity of different enzymes may be measured by using different sensors such that the activity of a particular enzyme may be measured separately by using a certain sensor specific to the particular enzyme in question. In the present context, an enzyme having a decomposing effect may refer e.g. to an enzyme having a softening effect on wood cells/wood structure and/or a separating effect on wood fibres.

[0011] The production of thermomechanical pulp consumes quite a large amount of energy. In an exemplary embodiment of the present solution, it may be possible to reduce the energy consumption of the production of TMP up to 24% by employing enzymes and enzyme recycling in the system. In addition, the use of enzymes for preprocessing wood chips/pulp may have other effects that improve the properties of the enzyme thermomechanical pulp (eTMP) being produced e.g. such that the amount of cooking pulp necessary for making paper may be reduced in the pulp mass. The present solution enables paper making costs to be reduced and thus the industry of paper making to be made more profitable. In other words, the present solution may decrease the energy consumption of an eTMP process significantly, it may have a positive effect on the properties of the eTMP pulp, and/or it may be used for minimizing the amount of rejects during refining.

[0012] Figure 1 illustrates a system (S) according to an exemplary embodiment of the present solution. In Figure 1 , components of the system (S) according to an exemplary embodiment of the present solution include a "fresh" enzyme (mixture) dosing unit EAS, a dosing pump P1 , and a dosing line (L1) for dosing an enzyme, a sensor(s) A for measuring enzyme(s) activity, and a recycling unit (including e.g. a recycling pump P2 and/or a recycling line L2) for recycling an enzyme-containing liquid to an impregnating container I2. The sensors A may comprise biosensors developed particularly for the present solution and/or existing biosensors and/or ordinary sensors. The amounts of enzymes to be dosed may be calculated automatically on the basis of parameters of an optimizing unit O. The optimizing unit O is in data connection with the sensors A and the enzyme dosing unit EAS in order to enable the optimizing unit to control the dosing means EAS, P1 on the basis of information received from the sensors. The optimizing unit O may also be configured to control the enzyme recycling means P1 on the basis of information received from the sensors A. Furthermore, the optimizing unit O may be connected with a factory/ production plant process control and/or the Internet. The optimizing unit O may be configured to use data it has received from the process control and/or the Internet for controlling the dosing and/or recycling means. The optimizing unit O may further be configured to relay parameters relating to control of the dosing and/or recycling means to the process control and/or the Internet. Appropriate enzyme dosing is carried out by the enzyme dosing unit EAS on the basis of the parameters relayed by the optimizing system O. The dosing pump P1 may be connected to the enzyme dosing unit EAS for pumping the enzyme(s) to the impregnating device I2 (e.g. via the dosing/recycling line L1+L2).

[0013] Thus, the exemplary embodiment of the present solution comprises the enzyme activity control unit O and the recycling pump P2 for enzyme processing. The enzyme(s) may be fed to the impregnating container I2 by the dosing pump P1 via the recycling pump P2 in order to achieve better mixing. The system comprises the enzyme dosing pump P1 and the enzyme dosing line L1 (e.g. one pump and/or one line per enzyme), the recycling pump P2 (and a possible recycling line L2) for the impregnating device (e.g. impregnating container) I2 for recycling liquid in the impregnating device (e.g. from the bottom of the container I2 to the upper part of the impregnating device I2), the sensors A for measuring enzyme activity (e.g. one sensor A per one enzyme), and the computer/logic unit O for controlling and optimizing the enzyme dosing.

[0014] In the exemplary embodiment of the present solution, the dosing means EAS, P1 are configured to dose one or more ligninolytic enzymes or one or more enzymes having an otherwise decomposing effect on a wood-based material (e.g. wood chips and/or fibrous pulp) from the dosing means EAS, P1 for the purpose of being fed to the impregnating device I2. In the method, at least some of the liquid which contains one or more ligninolytic enzymes or one or more enzymes having an otherwise decomposing effect on the wood-based material and which is being discharged from the impregnating device 12 is, via the recycling means P2, recycled back to the impregnating device 12. The measuring means A are configured to measure the activity of one or more ligninolytic enzymes or one or more enzymes having an otherwise decomposing effect on a wood-based material in the liquid contained in the impregnating device 12 and/or in the liquid to be fed to the impregnating device 12. The control means O are configured to control the dosing means EAS, P1 on the basis of measurement information describing the activity of one or more ligninolytic enzymes or one or more enzymes having an otherwise decomposing effect on a wood-based material and received from the measuring means A so as to keep the activity of the enzyme in the impregnating device I2 at a level enabling a sufficient impregnation of the wood-based material with the enzyme to be achieved.

[0015] Further, the system S according to an exemplary embodiment of the present solution may comprise a pre-steaming container C1 to which wood chips (and/or fibrous pulp and/or another corresponding wood- based material) is fed in order to wet the wood chips. The pre-steamed wood chips are conveyed e.g. via an RT conveyor K1 , a rotary valve V, and a conveyor K2 (horizontally) to a compregnating device 11 (impregnating screw). The compregnating device 11 is configured to press excess moisture out of the wood chips that were impregnated with steam prior to the wood chips being fed to the vertical impregnating device 11 , wherein the wood chips are impregnated with an enzyme or an enzyme mixture according to the present solution. The wood chips impregnated with enzyme(s) are recovered e.g. from the upper and/or middle part of the impregnating device, and the wood chips are conveyed e.g. by a screw conveyor K3 to a storage container C2 for temporary storage. From the storage container C2, the impregnated wood chips are supplied to a buffer container/press C3 for smooth refining and, therefrom, further to primary refining and/or to the actual refining process (wood chip refining). The enzyme solution may be left in an absorption vessel (not shown) subsequent to the impregnator I2.

[0016] The present enzyme preprocessing solution is based on the idea of processing wood chips with an enzyme solution prior to refining the wood chips in a TMP process. The enzyme processing may be carried out at a normal temperature or at a raised temperature (e.g. at about 60 °C). The purpose of the preprocessing is to improve the properties of mechanical pulp ob- tained by refining and to save energy during the refining process. The enzyme processing enables production of mechanical pulp of higher quality in a more cost-efficient manner and with smaller amounts of chemicals than the known techniques. The present solution provides means for dosing and measuring a required enzyme mixture.

[0017] In order to be able to adapt the present solution to suit different factories, the wood chips samples/fibrous pulp samples in question (to be used in the factory in question) may first be tested in laboratory conditions and/or by pilot equipment, when necessary. This enables the enzyme processing to be pre-optimized specifically for different factories. The purpose is to find the most suitable enzyme combination for each case by testing the wood chips. When data for the enzyme mixture and control parameters is available, the enzyme mixture and the optimizing unit O, including the control parameters, may be communicated to the factory for a test run. In the test run, the wood chips are refined into mechanical pulp, in which case the resulting pulp may be tested by laboratory measurements e.g. in terms of fibre length distribution, brightness and/or roughness. On the basis of the test run and measurement results, the final factory-scale enzyme mixture and mixture composition may be selected. It is thus possible to provide the factory-scale enzyme mixture composition customer- and factory-specifically for a certain type of wood chips. At the same time, it is possible to set the control parameters of the optimizing unit (i.e. the enzyme activity control unit O) that control enzyme dosing in order to dose the enzyme mixture suitable for the wood chips. The parameters are stored in memory units, and the parameters are employed in the programs of the optimizing unit O. The programs may be installed as part of a factory process. In addition to factory scale, the enzyme activity control unit O may also be implemented to suit laboratory or pilot scales for pre- optimizations.

[0018] According to an exemplary embodiment of the present solution, it is also possible that in addition to/instead of the recycling means P2, L2 connected to the impregnating device I2, the system comprises enzyme recycling "internally" in the impregnating device I2. This may mean e.g. efficient mixing of an enzyme-containing liquid inside the impregnating device I2. It is also possible that the system is provided with enzyme activity measuring but with no enzyme recycling. If the system S comprises no "external" recycling of an enzyme-containing liquid (via L2 and P2), enzyme activity is measured from the impregnating device 12.

[0019] The optimizing unit O according to an exemplary embodiment of the present solution comprises means for receiving from the measuring means A a signal relating to measurement information describing the activity of one or more ligninolytic or pectinolytic enzymes and/or one or more other enzymes affecting the structure of wood/wood cells, such as hemicellulase, in the impregnating device I2 and/or in a feed flow of the impregnating device I2, means for generating a signal in response to receiving the measurement information describing the activity of the enzyme from the measuring means A, and means for transmitting a signal to the enzyme dosing means EAS for controlling the dosing of the enzyme in to the impregnating device I2 on the basis of the information so as to keep the activity of the enzyme in the impregnating device I2 at a predetermined level. The optimizing unit O may further comprise means for transmitting a signal to the enzyme recycling means P2 for controlling the recycling of the enzyme in the impregnating device I2 on the basis of the measurement information describing the activity of the enzyme so as to keep the activity of the enzyme in the impregnating device I2 at a predetermined level. The enzyme dosing unit EAS according to an exemplary embodiment of the present solution comprises means for receiving from the control means A a signal relating to the activity of the enzyme in the impregnating device I2 and/or in the feed flow of the impregnating device 12, and means for dosing the enzyme in to the impregnating device I2 on the basis of the information so as to keep the activity of the enzyme in the impregnating device I2 at a predetermined level.

[0020] The object is to provide a system which is configured to measure and control as well as dose a correct enzyme mixture in to an eTMP process. The dosing and the correct/optimized mixture of enzymes reduces enzyme consumption and operation costs of enzyme processing. The idea is to dose a sufficient amount of enzymes in order to achieve a desired softening effect on the wood chips. However, the amount of enzyme is optimized such that no enzyme is used in excess, i.e. enzyme dosing in excess is to be avoided, since enzymes are typically quite expensive. Therefore, the process also comprises enzyme recycling and trying to find the most suitable enzyme or enzyme mixture for each wood chips/fibre type. Pilot tests may be employed in order to check the operation of the system and the enzyme mixture, and in continuous operation it is possible to check the energy saving potential. At the same time, a testing unit of the enzyme activity control unit O and the sensors A may be tested technically in each production environment. Devices suitable for the eTMP process can be developed and provided. The enzyme activity control unit O is installed in process equipment and the dosing and measuring processes are integrated into process machinery.

[0021] The development of the enzyme activity control unit O is carried out in relation to the development of the eTMP process. The pilot units may be tested already during eTMP process pilot runs and, therefore, the schedule for developing the enzyme activity control unit follows closely the development of the eTMP process. Table 1 shows stages of eTMP process design.

Table 1

Project stage Operation

development of enzyme activity control unit preliminary design

development of dosing unit connected to pilot scale testing

enzyme activity control unit - preparation of mixture dosing

- measurements and results for construction of enzyme activity control unit

- development of (bio)sensors

- development of enzyme activity control unit development of enzyme activity control unit pilot scale unit development for testing

pilot scale unit manufacture

development of enzyme activity control unit industrial scale testing

- production scale testing of enzyme activity control unit

- enzyme line measurements

- dosing and preparation of mixture development of enzyme activity control unit commercial unit production

development of enzyme activity control unit experience-based continuous development and improvements

development of enzyme activity control unit commercial distribution eTMP and enzyme activity control unit [0022] A suitable enzyme or enzymes is/are developed, and a final refining of the wood chips into mechanical pulp eTMP (at a pilot plant) is carried out. Enzyme dosing parameters are coded at the optimizing unit by means of tests of a testing plant. A dosing system is designed and built. The dosing system may be the same at different pilot plants and the parameters of the dosing systems may also be the same. The capacity of the dosing system is dimensioned according to a pilot process. The arrangement comprises building and coding an enzyme activity control unit O. It may be contemplated that the optimizing unit O comprises the part of the enzyme activity control unit O that includes information on the use and mixing of the enzyme in the production of TMP. An optimizing unit O delivery may contain the following articles: hardware

• PLC logic (e.g. Siemens S7)

• Internet connection

• process inputs in to enzyme activity control unit and process outputs from enzyme activity control unit

• customer interface

• local control panel software

• programming for process control

• program for controlling enzyme activity

• program for remote-controlling and updating

• protection protocol

[0023] According to an exemplary embodiment of the present solution, it is possible to make different enzyme mixtures for different types of wood. After subjecting enzyme mixtures to laboratory testing, enzyme mixture recipe information may be communicated to a client's pilot plant. In order to ensure the efficiency of a mixture at the pilot plant, a change in scale between the enzyme activity control devices has to be correct. The device may comprise measuring means for estimating the efficiency of an enzyme mixture. The information is programmed on the device for optimizing the recipe. For instance 5 to 10 enzymes of different types may be used in the tests. The main stages of determining a correct recipe may include e.g. the following ones: • protocol for mixing enzymes

• measuring method for estimating enzyme efficiency

• changing scale between pilot plant and client's plant

• programming of optimizing unit O

[0024] The principle of the wood chips impregnating system is to fill wood cells with an enzyme mixture. This is achievable by suitable process means in a manner wherein first, the cells are filled with water in a pre- steaming container C1 and, thereafter, they are squeezed empty mechanically and then filled with an enzyme mixture in the impregnating device I2. The recycling pump P2 recycles the enzyme mixture and excess water back to the impregnating container I2. The impregnation for the most part takes place during the flowing through the storage container C2 and partly in the buffer container C3. It may take the wood chips e.g. one to two hours to flow through the system. Subsequently, the wood chips are ready to be fed for refining.

[0025] The purpose is to prepare an enzyme mixture according to a particular protocol, which enables a database to be created and maintained about the delivered mixtures and process parameters associated therewith.

[0026] In the present solution, enzyme activity measurements may be analyzed by employing modern analyzers and a modern laboratory. It is also possible to take samples from raw materials for quality control according to the specifications of the raw material supplier.

[0027] In the present solution, the sensors A are used for analyzing enzyme activity in the impregnating device I2 and recycling L2, L1+L2. The present solution may utilize sensors A selective exclusively for the online enzyme combinations in question. Therefore, attention is paid to the purity of the recycling solution in order to make the enzyme activity measurement reliable.

[0028] The present solution comprises development of an enzyme activity control unit O, including design, installation and implementation of a dosing system EAS, P1.

[0029] The development of the optimizing unit O includes design, manufacture, programming and implementation according to parameters of optimizing calculations and laboratory tests. The present solution comprises coding and setting of parameters for dosing for controlling the dosing unit EAS.

[0030] A laboratory-scale pilot process may be built by purchasing or leasing the process equipment. Enzyme mixtures for pilot and factory testing are delivered. Analysis and enzyme activity sensor A development, fibre analysis and refining testing, a fibre and particle technology laboratory, process equipment, a laboratory and/or pilot dosing apparatus EAS, implementation and start-up, an optimizing unit O, logic (e.g. Siemens S7), design, installation, programming are needed. In factory testing, the amount of enzymes consumed is about 1000 kg/day, for instance.

[0031] The enzyme mixture has to function technically in the impregnating system. In the present solution, it is possible to find and select the most effective mixture for different types of wood chips. The present solution enables a reliable method and/or development/testing process to be provided for producing an optimal enzyme mixture.

[0032] The principle of the process is that wood cells are filled with water, the water is squeezed out, and the water is replaced by an enzyme mixture in the wood cells (a so-called "sponge effect"). A reaction between an enzyme and a lignin takes place in a storage container, and this stage takes about 0.5 to 1 hour. The storage container is dimensioned for a pulp flow enabling a continuous process. Hence, cooperation and testing with the equipment supplier is necessary.

[0033] The present solution may employ different ligninolytic (i.e. decomposing and/or softening wood lignin) enzymes and/or other enzymes affecting wood cells and fibres, such as pectinases, laccases, resinases and/or other lipases, hemicellulases and/or cellulases, depending on the wood type, wood raw material, growing place or the like. As to their chemical composition, the enzymes are typically naturally-occurring proteins.

[0034] The amounts of enzyme to be used depend on the wood type and raw material quality as well as on the enzyme used. In an exemplary embodiment, the amount of enzyme used is about 1 to 3 litres/1000 kg of dry matter.

[0035] For instance temperature, pH and reactor volume may be used as process parameters. In an exemplary embodiment, pressure is substantially atmospheric pressure. In eTMP, e.g. the temperature, pH and specificity of the process for particular wood chips may change as compared with a cTMP process and/or a "mere" TMP process.

[0036] In addition to the amount of enzyme, enzyme activity depends on the nature of the enzyme. Enzymes are catalysts, i.e. they may exert a plurality of reactions in succession. Being protein molecules, some of the enzymes present in the eTMP process become inactivated, i.e. unable to operate. Some of the enzyme is discharged from the process in the wood chips proceeding to the storage container C2.

[0037] Enzyme activity is influenced by process conditions, and enzyme activity is not necessarily directly proportional to enzyme content. Enzyme activity may be determined e.g. by standard methods according to the EC classification. However, the determination according to the standard takes place in standard conditions that do not directly apply to process conditions in practice, so for the process conditions in practice, the activity determination methods are optimized according to the present solution process-specifically. This means e.g. that for each process, an appropriate enzyme(s) activity level may be determined which is sufficient for achieving a sufficient impregnation of the wood chips with the enzyme(s) in the process. This also means that it is possible to avoid any excess use of enzyme, which means savings in enzyme consumption.

[0038] Different types of sensors A may be used in the present solution. The sensors A are based on the idea of measuring the effect of enzyme activity on the content of different volatile compounds, such as volatile aldehydes, organic acids, alcohols, in a gasified (evaporated) aqueous phase. Further, immobilized substrates (such as different sugars) may be used as sensors, whose decomposition rate is measured by measuring emergence of end products of decomposition in connection with a decomposition process.

[0039] In addition to the eTMP, the present solution may also be considered to be applied to other industrial processes that are based on enzymatic reactions (enzyme solution process or pure enzyme process), such as to industrial (e.g. cellulose, paper, food and/or chemical industry) and waste management (e.g. sewage plant and/or refuse dump) side flows.

[0040] An advantage of the present solution is that the composition and dosing of the enzyme mixture may be (pre)optimized for each factory separately.

[0041] In an exemplary embodiment of the present solution, enzyme recycling and dosing are based on a pump, since the pump enables an accurate dosing to be achieved, but also another dosing manner may is also feasible, such as a gravitational arrangement.

[0042] Thus, the present solution provides a method of preprocessing wood chips with one or more enzymes, the method comprising employing a sensor (sensors) for measuring the activity of an enzyme (enzymes), and a recycling pump and lines for homogenizing an enzyme-containing liquid in an impregnating container and for reducing enzyme consumption.

[0043] The purpose of the following implementation examples is to further clarify the invention.

Example 1

[0044] Three different enzyme mixtures (a, b, and c) were tested. The mixtures contain pectinase, laccase, lipase, hemicellulase, and cellulase in different proportions.

[0045] 300 mL of the enzyme mixtures were dosed in to impregnating water (568 L) and the effect on specific energy consumption was tested. The energy consumption was most effectively reduced by enzyme mixture b, which gave 8% energy savings as compared with a reference impregnated with water. With energy mixture c, the energy consumption was reduced 4%, and with mixture a the savings were 1 %.

[0046] Further, halving the dosage was tested with mixture b. The halved dosage gave 6% energy savings.

Example 2

[0047] Enzyme mixture d optimized on the basis of experience from Example 1 was tested, the mixture containing pectinase, laccase, lipase, hemicellulase, and cellulase. Laccase, cellulase, and two different hemicellulases were measured for enzyme activities.

[0048] 300 mL of the enzyme mixture was dosed in to impregnating water (568 L) and the effect on specific energy consumption was tested. Owing to the processing, the specific energy consumption was reduced 15.5% as compared with a reference impregnated with water.

[0049] In order to assess process management and recycling, the process water was measured for enzyme activities for laccase, cellulase, and two different hemicellulases, achieving the following results (activity unit/litre):

- laccase 5.4 U/L

- cellulase 7.2 U/L

- hemicellulase-1 3.1 U/L

- hemicellulase-2 17.5 U/L [0050] The designations and functions shown in Figure 1 are simplified, and they are only intended to describe the idea of the present invention. The functions described in Figure 1 are in no absolute time order, and some of the steps/points may be carried out simultaneously or in an order other than the given one. Other functions may also be carried out between the steps/points or in the steps/points. Some of the steps/points or parts of the steps/points may also be omitted or integrated together or replaced by an equivalent step/point or part of a step/point. The hardware functions illustrate a procedure that may be implemented in one or more physical or logical units. The signalling messages are only exemplary and they may even contain a plurality of separate messages for sending the same information. The messages only serve as examples, and they may contain only some of the aforementioned information. The messages may also contain other information.

[0051] In addition to prior art devices, the system or system network nodes implementing the functionality according to the present solution comprise means for optimizing the above-described enzyme dosing. Existing network nodes and user terminals comprise processors and memory that may be utilized in the functions of the present solution. Changes necessary for implementing the present solution may be carried out by updating or complementing software routines and/or routines contained in ASICs (Application-Specific Integrated Circuits) and/or programmable circuits, such as EPLDs (Electrically Programmable Logic Devices) or FPGAs (Field Programmable Gate Arrays).

[0052] It is apparent to those skilled in the art that as technology advances, the basic idea of the invention may be implemented in many different ways. The invention and its embodiments are thus not restricted to the above-described examples but may vary within the scope of the claims.