DE1567295A1 - Process for regulating the crystallization process of sucrose and device for its implementation - Google Patents

Description

PATENTA

'UVALTB

: / I »P7 ^ TELE«. ^ "*" PROP ₁ NOUS T _ELE F ON: 2 ₂ «85 - T EL _E G _B AMM E: PROP, N DUS

Berlin, June 5, 1965

Societe Des Raffineries De Sucre De Saint-Louis, 3, rue de la Republique, Marseille 2il / France

"Procedure for regulating the crystallization process of sucrose and device to his

Execution"

The invention has a method for controlling the crystallization process of sucrose in a cooking apparatus, its heating as a function of the dry matter content (Brix degrees) of the mother syrup is regulated in the fresh water be injected and into which a variable inflow of top-up syrup can take place «

The crystallization of sucrose, starting from sucrose syrup, The essential technological process of any decay is purely for the production of cane or beet sugar. The crystal, isat.ions- or "cooking process" is under different Conditions and performed with changing goals, depending after whether many starting from the mother liquors, raw sugar

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intends to separate or, starting from syrups of medium and high purity, refined sugar are produced or whether one intends to exhaust residual syrups of low purity.

However, this Saver driving all agree on one point, namely in the development of sucrose crystals from a syrup which vird held by the vaporization of its water at reduced pressure at a certain saturation state _e The ideal goal of the process is to produce a maximum quantity of granulated sugar, with simultaneous Consideration of the criteria of quality (in particular the size of the crystals, their purity and their crystallinity), the thermal efficiency (in particular the reduction of heat losses) and the technological ease (in particular the duration of the operation, flowability of the cooking mass).

The production of granulated sugar, starting from a sucrose syrup, takes place by means of vacuum distillation of this syrup in a cooking apparatus which is heated and maintained at negative pressure by known means. The purpose of this distillation is the thickening of the syrup by evaporation of the Water, although its ßindickiinvj is kept at a low value becomes, .ier the crystal nuclei that are present in it to grow

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required oversaturation guaranteed. This process takes place in several phases

1. At the beginning, the cooking apparatus contains a ^{starting material from a topping syrup that forms the "grain foot" (H} pied de cuite ") and the process begins with the thickening of the" grain foot "by means of distillation;

2. In the thickened syrup called mother syrup, either the crystallization or the crystal growth initiated by shock or by partial or full vaccination (Crystal formation);

3. The mother syrup is used for the purpose of crystal growth subjected to ripening, the swelling necessary to effect the homogeneity of ripening, if any by adding a certain amount of pure water ody of water vapor ("fresh water") is maintained;

4 · While crystal formation is actively progressing, it increases refilling the cooking apparatus, d. H. a feeding of topping up syrup into the cooker, before;

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5. After the cooking apparatus is filled and the required If the size of the crystals is reached, the "concentration" of the cooking mass is carried out, a process which consists in continuing the distillation in such a way that the crystalline sugar mass increases, without increasing the volume of the cooking mass j

6. When the binning process is complete, the boiling is stopped and the cooking apparatus emptied.

The adjustable sizes, d. H. those to maintain the Thickening of the mother syrup, necessary heat supply, the supply of the top-up syrup, the supply of fresh water, etc., are often regulated empirically by the worker supervising the cooking process according to his experience. at further developed method one takes a programmed automation of the cooking process, i. H. the setting of the different sizes in a predetermined sequence to help. This is how the syrup evaporation control of the cooking material is regulated generally made at the beginning of the operation while the supply of the replenishment syrup based on a measurement the apparent viscosity of the cooking strain is regulated. This method is especially useful for those working with forced circulation punching devices, since the extent of the

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motor absorbed energy as an indirect measure for can use the viscosity of the cooking mass. However, this method is inadequate except for the essential ones Properties of the syrup are invariable, which is rare is the case, or external means are provided for this To compensate for changes, which leads to an increase and complication of the accessories.

The proposed method according to the invention offers the ability to control the cooking process as a function of the actual physicochemical conditions prevailing during the process, this method is thereby characterized in that, at least at certain times, the supply and the dry matter content (Brix degree) of the Topping up syrups, the dry matter content (Brix degree) of the Mother syrups, the amount of water evaporated and the amount of water injected are measured that the mass of the The mother syrup involved in this crystallization process as well as the mass of the crystallized state in the cooking apparatus contained sugar is determined by starting from these measured quantities and from the initial mass and the dry matter content (Brix degree) of the grain base, their Quantities have been determined beforehand »two mass balances are carried out, that one also uses the mass of the syrup as a radio-

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tion of the mass of the crystal sugar expressing relationship establishes that one further, proceeding from the measured Mass of granulated sugar and with the help of this relationship determines a reference value for the mother syrup mass and regulates the supply of topping syrup so that the mother syrup mass is kept equal to this reference value.

The invention also relates to a device for carrying out the aforementioned method for controlling a cooking appliance, which regulates its heating as a function of the dry matter content (Brix degree) of the mother syrup Device and a pipe for injecting water is provided, the »fliit is equipped with an automatic valve is that the arbitrary change of the top-up syrup dispenser and a (group of sensors which the supply and the dry matter content (Brix degree) of the top-up syrup, the dry matter content (urix degree) of the mother syrup;?, the amount of evaporated water and the amount of injected water can deliver appropriate signals.

Even if the above discussed rage method already leads to inadequate results when used to regulate the cooking process, a considerable improvement can still be achieved if this regulation is carried out with the aid of a

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A device suitable for applying the method without human intervention is automated. This goal is achieved achieved with the aid of the device forming the second object of the invention. This device is characterized by that it contains an arithmetic unit with two summing circuits, which are set up in such a way that they emit a first signal corresponding to the crystalline sugar mass at a first output and form a second signal corresponding to the mother syrup mass at a second output, furthermore a function generator, which, based on the first signal and according to the relationship, can form an output signal corresponding to the reference value and a comparison circuit which generates a signal corresponding to the difference between the second signal and the signal corresponding to the reference value Can generate error signal, the input of the function generator at the first output of the arithmetic unit, which both inputs of the comparison circuit to the output of the function generator or are connected to the second output of the arithmetic unit, and further in that the device is connected to connected to the cooker via a group of lines is, one of which is the output of the comparison circuit with the automatic valve connects so that the error signal his Controls the opening state, and from deen the other controls the inputs of the calculator with the group of sensors.

BADC-L

The invention is described below in terms of the method and on the basis of an exemplary embodiment of the device its implementation explained in more detail. Bs show:

Fig. 1 is a schematic representation of the device for performing the method and the cooking apparatus existing unit,

2 shows a more detailed circuit diagram of a particular circuit of the device,

Figs. 3 and 4 are explanatory diagrams.

The control method forming the subject of the invention consists in acting on the supply of the topping syrup in a manner. that the mother syrup mass contained in the cooking apparatus is constantly equal to a variable reference value for the entire course of the cooking process, is calculated according to a previously established relationship and expresses the mother syrup mass that should be in the cooking apparatus as a function of the actual crystal sugar mass in it .

For measuring the actual granulated sugar range contained in the cooking apparatus as well as the actual mother syrup mass

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one proceeds indirectly by setting up two mass balances »

The first mass balance is obtained by

- the product of the initial syrup mass contained in the grain base m · and its dry matter content (Brix degree) B ^ determined, d, h. of sizes before starting the cooking process have been determined in advance, this product giving the initial sugar mass contained in the cooking foot;

Adds the sugar mass brought in by the topping-up syrup, which is determined by measuring the topping-up weight ro _r and the dry matter content (Brix degree) B of this topping syrup allowed since the start of the cooking process and determining the product of these quantities (if the dry matter content (Brix degree) of the top-up syrup is variable, the inflow q of the top-up syrup and its dry matter content (Brix degree) B _r is measured continuously, the product of these quantities is determined and the product is integrated in relation to the time since the start of the cooking process, which is / q _r · B _r dt results);

of this sum, the sugar mass contained in the mother syrup subtracting by the dry matter content (Brix degree)

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B _{g of} the mother syrup multiplied by its mass m.

This first mass balance that is spread through the relationship

(1) m _c »(m _si . B _si ) + (m _r .

can be expressed, thus results in the mass m of in crystal form sugar in the cooking apparatus.

The second mass balance consists in adding the initial syrup mass m · the topping up syrup mass allowed in the cooking appliance m and the injected Prischvassermass m. add, and from this sum the evaporated water mass m and the crystal 1 zucker rmas se ra deducts. This gives the sugar mass m contained in the mother syrup, which is determined by the relationship

expresses.

Bs is easy to solve the system of equations (1) and (2) and to take the values of m _c and ra from them. The rule process described above makes it possible " to control the cooking process exactly as soon as you add the mother syrup mass to the Kri-

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stallZUCkermass related matching relationship has set up. This relationship is empirically a for always determined on the basis of a few previous experiments on the cooking apparatus and can be determined by a relationship between the values m and m

The relationship between m and m can be, for example, a choose a linear relationship that is represented by an equation of the type m * m. + «Can express Xm and its graphic representation has the course illustrated in FIG. 3. One can also use the relationship shown in FIG. 4, which corresponds to a sequence of linear relationships, each of which corresponds to the phases of the operation, i. H. the maturation M, the replenishment N or the narrowing S, relate. In this case it can be advantageous, the inclination of one or both of the linear corresponding to the maturation phase M and the narrowing phase S, respectively Lines representing relationships are given such a negative value that this linear relationship or linear relationships express the constancy of the volume of the grain base and / or the cooking mass during the corresponding phase.

In any event, the choice of the equation relating m to m is dictated by each specific case, its course being determined from experiments carried out beforehand on the cooking apparatus.

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The control method described above is suitable for a complete automation of the control of the cooking process, since the solution of the system of equations (1) and (2) with the help of an arithmetic unit, namely an analog arithmetic unit, can be done.

The device for carrying out the control method described above is illustrated in FIG. 1 in a schematic representation.

The cooking apparatus 1 is via a line 2, the throughput of which • is controlled with the aid of a valve 3, with top-up syrup r fed. It is heated with heating steam ν, which is supplied via a pipeline 4, the throughput of which is controlled with the aid of a valve 5, is admitted into a heating coil 41. Finally will it is fed with fresh water j via a pipe 6, the throughput of which is controlled with the aid of a valve 7. The pipelines 2 and 6 are provided with throughput sensors 8 and 9, respectively, which measure the inflow q of topping up syrup and the inflow q.

r j

to be able to convert fresh water into electrical signals. There is also a dry matter content (Brix degree) sensor on line 2 10 arranged, the an electrical signal corresponding to the dry matter content (Brix degree) B of the topping syrup supplies. Am throughput sensor 11, one of the throughput

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q of the water vapor discharged via a line 42 connected to a vacuum pump (not shown) supplies the corresponding electrical signal, and a dry matter content (Brix degree) sensor 12, which supplies an electrical signal corresponding to the dry matter content (Brix degree) B of the mother syrup , complete the equipment of the cooking apparatus. The signal B is fed via a line 13 to a comparison circuit 14 which has the task of this signal B to be compared with a pilot signal B (cons) "The ^v from the difference between B and B existing error signal is the one hand, to an opening condition of the valve 5 controlling electropneumatic converter 15 and on the other hand applied to a measuring instrument 16 which enables its value to be read off. The sensor 12, the line 13, the comparison circuit 14 and the electropneumatic converter 15 thus form a means for regulating the heating of the cooking apparatus as a function of the value of the dry matter content (Brix degree) B of the mother syrup. In the present particular case this means has the Form of a local control circuit that regulates the throughput of heating steam ν in such a way that the dry matter content (Brix degree) B _{g of the mother syrup is a conductance value B s} ^ ^cons ' set for all times at the comparison circuit at the beginning of the operation. Injecting fresh water j by actuating the valve 7 is an additional

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Additional means for regulating the value of the dry matter content (Brix degree) B ₃ , which can be activated if the regulation of the heating of the cooking appliance is not sufficient to make this dry matter content (Brix degree) equal to the conductivity value _B ^ (. cons; _{to nalterle Z} to monitor the value of B, the measuring instrument 16 is provided, whereby it is incumbent on the worker (cooker) supervising the cooking process to inject fresh water j manually by operating the valve 7, if the measuring instrument 16 detects this inadequacy, ie the insufficient control of the heating of the cooking appliance.

The actual control device 20 contains an arithmetic unit 21 which, in the present example, is an analog arithmetic unit and which, starting from the input lines 22, 23, 24, 25 or respectively, coming from the sensors 8, 10, 9, 11 and 12 respectively 26 supplied signals q, B, q., Σ and B and proceeding from the initial syrup mass m. and signals corresponding to their dry matter content (Brix degree) B ₃ ^, which can establish and solve both of the mass balances represented by equations (1) and (2) discussed above. On its output line 29, this arithmetic unit delivers a _{signal corresponding at any time to the total mass m g of} the mother syrup contained in the cooking apparatus 1 and, at an output line 30, a signal of the sugar mass m, which is in crystal form in the cooking apparatus, at any time.

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Speaking signal · The values m · and B ₃ -Jt, which are the initial values for each operation, are ascertained or determined at the beginning of the cooking process and displayed with the help of any means shown schematically by the lines 27 and 28.

The control device 20 also contains a function generator 35 which is set up so that, based on the at the output 30 of the arithmetic unit 21, a signal corresponding to the reference ground in ^ 'and at the output 37 occurring signal generated, and a comparison circuit 36,

(ref) which always determines the difference between this reference signal m ^v ' and the signal m. The comparison circuit 36 is therefore connected on the one hand to the output 29 of the arithmetic unit 21 which supplies the signal m and on the other hand to the output 37 of the function generator 35. The output of the comparison circuit 36 is connected via a line 38 to an electropneumatic converter 39, which has the task of regulating the opening state of the valve 3 controlling the throughput of the topping syrup r, which is illustrated by the line 39.

The arithmetic unit 21 is shown in detail in FIG. His essential elements are two summing circuits 51 and 52, three multiplying circuits 53 »54 and 55 and an integration

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gate circuit 56. They are auxiliary integrator circuits 57, 58 and 59 provided for forming the integrals of the signals q,

q. or α with respect to the time and the delivery

m in the cooking apparatus since the beginning of the cook / embedded AuffÜllsirupmasse, the current injected into the cooking apparatus of water m- or the evaporated water mass m corresponding signals m, m. or m. These signals m, m and m are applied to the inputs of the summing circuit 51, but the last one after it has been reversed in sign in an inversion circuit 60. This summing circuit 51 also receives the signal m · supplied via a line 6t and the signal -m, which is the same as the signal m appearing at the output of the summing circuit 52, but has been reversed with regard to its sign by an inversion circuit 62 and is supplied via a line 63 .

The summing circuit 52 receives three input signals. The first signal fed in via a line 64 is formed by the multiplication circuit 53, the output of which is the product (m *. B.) Of the input signals ic. and B. provides the corresponding signal. The second signal is the integral of the product q _r formed by the integrator circuit 5c. B ^ from the signals q and B applied to the input of the multiplication circuit 54 with respect to time. The third signal will

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m formed by the MuItiplikationsschaltung 55 and corresponds to the product _s. B ₃ from the signals m and B applied to the input of the multiplication circuit 55, the signal Jn _{3 being} that signal which occurs at the output of the summing circuit 51 and is fed from it via a line 65. Before it is transmitted to the summing circuit 52, this third signal is reversed with the aid of an inversion circuit 66,

The apparatus described above for carrying out the method according to illustrate the invention operates as follows ι

After the initial mass m. of the grain root and its dry matter content (Brix degree) B. determined and the corresponding values have been set at the inputs 27 and 28 of the device, the grain root attenuation phase begins ₀ The valve 5 is open so that part of the water contained in the grain root evaporates until the dry matter content (Brix degree) B. _{3 of the syrup reaches the value B 3} ^ ^GCms ■ 'previously set at the input of the comparison circuit 14. The vaccination is then carried out, followed by the maturation phase. During this ripening phase, maintaining a surge to cause the mother syrup to swirl and maintain its homogeneity is un-

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Admissible, This surge causes the evaporation of water, so that the tendency to increase the dry matter content (Brix degree) B ₃ exists even if the valve regulating the flow of steam ν is under the action of the control circuit 13, 14 and 15 in its smallest opening position. During this ripening phase, it can be used to prevent an increase in the dry matter content (Brix level) B des

(cons)
Mother syrups above the value B ^ 'become necessary to inject fresh water, the flow rate of which is q. with the help of

Sensor 9 is geraessen in the form of an electrical signal.

While the initiated crystal formation is progressing, one goes on to the filling phase. That the influx of top-up syrup The regulating valve 3 comes into operation, its degree of opening being controlled by the regulating device 20. During The dry matter content (Brix degree) B of the mother syrup has the tendency to crystallize as a result of the decrease in the Sugar content of the syrup and its dilution by released

(cons) set water of crystallization to drop below the value B ^v . The injection of fresh water j is interrupted, the dry matter content (Brix degree) B of the mother syrup being regulated by the single control circuit 13, 14 and 15.

The summing circuit 51 forms by summing the input signals

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nale Bi _5. , m »ro» -πι and -m a. output signal m corresponding to equation (2) discussed above, so that this solar circuit performs the second of the mass balances discussed above.

The summing circuit 52 forms a signal corresponding to equation (1) discussed above by summing the input signals (m _si . B _si ), (Jm _p . B _r dt) and - (m _s . B _3). So it performs the first of the mass balances discussed above. (It is assumed that the dry substance content (Brix degree) B of the topping syrup r is not constant. This also shows that of the output signals formed by the two summing circuits is or «m is the first of the one in the cooking apparatus 1 (Fig. 1) contained mother syrup total mass and the second corresponds to the sugar mass in it in crystal form.

The function generator 35 supplies, on the basis of the signal m _c and in accordance with the established relationship, a reference value

(r £ f )

m ^v ', ie the signal corresponding to the theoretical total parent mass. This signal is taken off as a reference value so that the comparator circuit 36 with the aid of ice el: - tropneumatischen 3S converter which controls the inflow of the refill syrup regulating valve 3, namely _r in the manner that the value of

f r & f)
of m is assigned to the value of m ^v '«

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The device thus effects the automatic control of a cooking appliance by acting on the inflow of the topping syrup as a function of variables automatically measured on this cooking apparatus and as a function of a relationship established between the granulated sugar mass and the mother syrup mass.

This relationship corresponds to an equation of changing the ratio K «m / m, it being used to monitor the operation of the cooking apparatus can be useful if the device continuously achieves the value effectively achieved by this ratio R determined. Accordingly, it is provided according to the invention the arithmetic unit 21 with an auxiliary circle, for example with the Circle 67 (Fig. 2), which is arranged so that he the quotient of the signals fed in via lines 63 and 65 determined and a ratio R corresponding and over a line 31 supplies a signal transmitted to the outside. This is useful, but useful for the operation of the control device is not an indispensable addition, so that this feature left to discretion in FIG. 2 can be recognized as such has been made that the circle 67 »its input lines and its output line 31 as well as in Fig. 1 the line 31, at which the signal R occurs, are shown in dashed lines.

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Bs 1 establishes that the arithmetic unit can be connected to the cooking apparatus without the control chain consisting of the function generator 35, the comparison circuit 36, the line 38 and the electropneumatic converter 39 being closed. which takes place in the same way as the automatic control described above, but in which an operator is required to control the valve 3 ₀ In this case, only the arithmetic unit al is used, and the control device becomes a measuring device that accurately measures the degree of crystallization of the sugar inside the cooking apparatus 1. It is then expedient to provide the arithmetic unit 21 with measuring instruments such as the measuring instruments 68 and 69 _S , which are connected to the lines 29 bair * 30 and with scales 70 and 71 for reading the Values of the sizes m ^. And m are providedo The same applies to the size R, whose numerical value is too know may be of interest «Except there? Possibility of reading the values of \ n _c9 in., And R their recording can be correct even if the control is automatic »The measuring instruments 68 and 69 are then supplemented accordingly, cL h _a replaced by recording devices . This is not the case haiten to significant e ■ island since the incorporation of this Zubelxreinriehtungen at the discretion of the person skilled liegte

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The control device described above is an analog control device. It is clear that, within the scope of the invention, they can also be wholly or partly a digital control device can. In this case it contains an analog-digital group or digital-to-analog converters, which convert, in particular, the analog signals supplied by the sensors into digital or vice versa. It is essential that the

Device forms signals M and m by converting the signals through the Equations (1) and (2) sets up mass balances shown. Likewise, the device can also solve these equations in their explicit version, while they are in the example described causes their solution in the implicit version.

Finally: the invention provides that the measurement of the sizes

m, B ₁ , in-, Hi ₄ and B instead of, as in the previous example, konr ι * jes

to take place continuously, at certain times, so that the regulation of the punching apparatus at certain times according to the in the control of processes known technique of "sampling" causes j / ird. In this faxle a single central The device regulates a group of punching devices, based on the assumption that they are connected to the sensors Lines concurrently operating dialing devices are provided which are set up so that they the device

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periodically with the sensors attached to the individual cooking appliances, and that this dialing device Memory elements are assigned that store the signals coming from the sensors and that they save during the Wählzylclusabschnitts, since the sensors are not connected to the device, they can integrate with respect to time «

Claims ι

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Claims (1)

June 5, 1965 Societe Des Raffineries De Sucre De Saint-Louis, 3, rue de la Republique, Marseille 2 <* / France Claims ί I. Process for regulating the crystallization process of sucrose in a cooking device, the heating of which is regulated as a function of the dry matter content (Brix degree) of the mother syrup into which fresh water can be injected and into which the inflow of top-up syrup can be changed, characterized in that, at least at certain times, the supply and the dry matter content (Brix degree) of the topping syrup, the dry matter content (Brix degree) of the mother syrup, the amount of evaporated water and the amount of injected water can be measured that the mass of the mother syrup involved in this crystallization process as well as the The mass of the crystallized sugar contained in the cooking apparatus is determined by starting from this measured sizes and the initial mass and the dry matter content (Brix degree) of the grain base, the sizes of which are determined beforehand are present, two mass balances are carried out, that one further measures the mass of the syrup as a function of the mass of the crisis - ρ - 009851/0340 FERNECHRElBfR: 01X097 BAD OFUGINAL stable sugar expressing relationship establishes that one further, starting from the measured mass of the crystal sugar and with Using this relationship, a reference value for the mother syrup mass is determined and the supply of topping syrup is regulated so that the mother syrup mass is kept equal to this reference value. 2. The method according to claim 1, characterized in that one selects a relationship of direct proportionality that can be represented linearly as the relationship. 3 »Method according to claim 1, characterized in that the relationship chosen is one which is defined by a group of linear relationships can be represented, each one of the three phases, ie. the maturation phase (M), the filling phase (N) or »correspond to the narrowing phase (S) of the crystallization process, 4. The method according to claim 1 and 3, characterized in that at least one of the linear relationships of a relationship corresponding to the maturation phase (M) or the narrowing phase (S) which expresses that the volume of the Kora foot or the cooking mass is constant during the corresponding phase. 5, device for performing the method according to claim 1 - 3 0098 ^ 1/0340 up to 4 to regulate a toch apparatus, which is provided with a device that regulates its heating as a function of the dry matter content (Brix degree) of the mother syrup and a pipe for injecting water with an automatic valve that allows the top-up syrup supply to be changed as required, and is equipped with a group of sensors which can supply signals corresponding to the supply and the dry matter content (Brix degree) of the top-up syrup, the dry matter content (Brix degree) of the mother syrup, the amount of evaporated water and the amount of injected water, characterized in that that it contains an arithmetic unit (21) with two summing circuits (51, 52) which are set up so that they receive a first signal corresponding to the iris sugar mass at a first output (30) and a first signal corresponding to the mother syrup mass at a second output (29) form a corresponding second signal, a function generator (35) »which starting from the first signal un d can form an output signal corresponding to the reference value according to the relationship, and a comparison circuit (36) which can generate an error signal corresponding to the difference between the second signal and the signal corresponding to the reference value, the input of the function generator to the first output of the arithmetic unit , the two inputs of the comparison circuit are connected to the output of the function generator or, respectively, to the second output of the arithmetic unit, - 4 - 0 0 9 8 51/03 4 0 ^ bad or, _{g / Nal} and in that the device is connected to the cooking apparatus a group of lines is connected, of which one (38) the output of the comparison circuit with the automatic valve (3) connects so that the error signal controls its opening state, and of which the others (22-26) connect the inputs of the calculator to the group of sensors. 6. Apparatus according to claim 5, characterized by an auxiliary circuit which is connected to the two outputs of the arithmetic unit is connected and can form the quotient of the first signal by the second signal, so that a ratio (.R) the crystal sugar mass corresponding to the mother syrup mass Signal is generated « 7. Apparatus according to claim 5 and 2, characterized in that they provide rat reading and / or recording instruments which is the reading and / or recording of the values of the granulated sugar mass and / or the mother syrup mass and / or enable signals corresponding to their ratio. 8. Apparatus according to claim 5, characterized in that the Arithmetic unit is an analog arithmetic unit » 009851/0340 9. Apparatus according to claim 5t, characterized in that the Rechenverk is a digital Rechenverk. Vb / Mo - 16 957 009861/0340