METHOD FOR ADJUSTING THE DRY MASS CONTENT OF CONCENTRAES IN QUARK PRODUCTION AND DEVICE FOR EXECUTING THE METHOD

Description

[0001] The present invention relates to a method for adjusting the dry matter content of concentrates in curd production, as well as a correspondingly equipped device with a nozzle separator.

[0002] DE 10 2004 035 215 A1 describes a process in which a constant feed quantity is specified. If a fluctuation in the dry matter content of the curd is detected through random measurements, the feed quantity is adjusted manually.

[0003] Furthermore, EP 0 440 208 B1 discloses a method for controlling the production of cream cheese with a double cream stage. Here, a measurement is performed at the whey outlet. Unlike in quark production, however, in cream cheese, the whey represents the heavy phase. Therefore, the mass flow of the heavy phase is also determined here. The dry matter is also determined by measuring the heavy phase, which in this case is the whey and, in the case of quark production, corresponds to the quark fraction.

[0004] DE 32 38 462 A1 is also known. Here, the amount of cream produced per unit of time is measured and the feed rate is adjusted accordingly.

[0005] DD 2 77 583 A3 discloses a method for determining dry matter by measuring conductivity. The dry matter content is determined using a computer based on the conductivity of the curd after passing through a curd funnel. The problem with this is that a change in the feed rate results in a long dead time before detection. The dry matter feed is measured in the laboratory and is assumed to be constant. Furthermore, the conductivity measurement depends on the pH and fat content of the medium being measured. Therefore, these values ​​must be known or additionally determined.

[0006] A generic method for adjusting the dry matter content of fresh cheese, especially quark, is also known from DE 10 2004 035 215 A1. This method is based on pressure measurement, with a corresponding pressure sensor or transducer arranged in the discharge line of the heavy phase upstream of a cooling device. The pressure measurement serves as a control variable for adjusting the feed rate of the initial product into the separator.

[0007] The difference between cream cheese and quark is well known. Basically, quark is a special form of cream cheese. For this application, the difference can be reduced to the fact that when quark is centrifuged, the whey is the light phase. When cream cheese is centrifuged, the whey is the heavy phase. This can generally be explained by the different fat content of the other phase.

[0008] The dry matter content (DM) of the curd produced depends largely on the DM of the vat milk, the whey, the separator nozzle configuration, and the feed volume to the separator. The rule of thumb is that a larger feed volume results in a higher DM of the curd.

[0009] The dry matter content of milk and whey, as well as the dry matter content of curd, is usually determined by sampling and analysis using a rapid method, as already introduced as state-of-the-art in DE 10 2004 035 215 A1. The dry matter content analysis of these samples has a tolerance of at least ±0.1%.

[0010] However, because the dry matter is only determined in the final product (quark concentrate), intervention in the process can only be delayed. This results in an undesirable deviation in the final product before countermeasures can be taken into account by adjusting the feed rate. In addition, a dead time for the product to concentrate in the separator drum must be taken into account in the control system, and the controller must be set accordingly. In a test conducted for this purpose, the control time delay was approximately 3 minutes.

[0011] Based on the above-mentioned problem, the object of the present invention is to provide a method which allows a faster and thus more precise adjustment of the dry content in quark production.

[0012] The present invention solves the above-mentioned problem by a method having the features of claim 1 and in a constructive manner by a device having the features of claim 8.

[0013] A method according to the invention for adjusting the dry matter content in quark is carried out using a device for centrifugally separating a starting material into quark and whey. The core component of the device is a nozzle separator. The device may also include, for example, inlet and outlet lines, as well as one or more measuring devices, control elements, and / or a control and / or evaluation unit.

[0014] The method according to the invention comprises at least the following steps: a. Feeding the starting product into a nozzle separator of the device via an inlet line while determining the dry matter and / or protein content and determining, in particular measuring, the mass flow of the starting product. Skimmed milk, for example, can be used as the starting product. The dry matter and / or protein content in the starting product can be determined, for example, by microwave measurement or by infrared measurement, in particular NIR measurement (near-infrared measurement). Corresponding inline measuring devices are known which measure directly in an inlet line or in a bypass pipe of the inlet line without separate sampling. Determination by sampling is also possible, but less preferred. b. Centrifugal separation of the starting material by the nozzle separator into a whey fraction and a curd fraction; A nozzle separator is used for centrifugal separation.While a number of applications prefer a two-phase separator, a jet separator has proven to be significantly more efficient in this case. c. Separate discharge of the whey fraction and the curd fraction from the jet separator and determination, in particular measurement, of the mass flow of the whey fraction; then, to create a mass balance, the mass flow of the whey fraction is determined during the adjustment of the dry matter content of the curd. It is assumed that, with a corresponding separation efficiency of the separator, the dry matter content of the whey is approximately constant, regardless of how much the DM content of the starting product fluctuates. The same applies to the protein content. d. Adjustment of the mass flow of fed-in starting product depending on the values ​​determined in steps a) and c).

[0015] Finally, the mass flow of the supplied starting product is adjusted as a function of the determined mass flows and the DM content or protein content of the starting product. The dependency consists in particular in the fact that the mass flows determined in steps a) to c) serve as controlled variables for adjusting the mass flow in step d), e.g. by adjusting the opening cross-section of a feed valve of the device according to the invention. However, variables derived from the mass flow can also be used as controlled variables. This can be done, for example, from mass flow given known physical variables of the medium and / or the device according to the invention, such as density and / or temperature and / or pipe cross-section, also the volume flow, flow velocity and other process variables.The person skilled in the art is aware of the interdependencies of these measured variables and, based on the above, can also consider various controlled variables derived from the mass flows.

[0016] According to the invention, the dry matter content or the protein content of the quark fraction is determined on the basis of the determined mass flow of the starting product and the mass flow of the whey fraction and the determined dry matter content or protein content of the starting product.

[0017] The method according to the invention achieves, in particular, a minimization of the dead time, with more precise control as close as possible to desired specifications, for example legal specifications or manufacturer specifications.

[0018] Advantageous embodiments of the invention are the subject of the subclaims.

[0019] For display and manual monitoring of the process parameters, it is advantageous if the mass flow of the curd fraction is determined based on the determined mass flow of the starting product and the mass flow of the whey fraction.

[0020] To ensure fluctuation-free determination of the nozzle discharge, it is advantageous to smooth the temporal progression of the determined nozzle discharge values ​​over a period of at least 20 seconds, preferably 30-90 seconds. The nozzle discharge corresponds in particular to the discharge of the heavy phase from the nozzle separator.

[0021] The time difference between measuring the dry matter content or protein content in step a and adjusting the feed rate in step d is advantageously less than 2 minutes. This allows for more precise adjustment of the dry matter or protein content, and allows for efficient processing of starting products with highly fluctuating compositions.

[0022] According to the invention, the mass flows of the starting product introduced into the nozzle separator and the discharged whey fraction are determined, preferably continuously, as control variables, and the mass flow in the quark fraction's outlet line is calculated from this. This determined mass flow in the outlet line can be used as a value to determine a control variable for the automatic, and preferably continuous, control of the feed rate of the starting product. This control is typically achieved by a control valve. However, all other devices for adjusting the feed rate are also conceivable.

[0023] Advantageously, the starting product is continuously fed into the jet separator during curd production, and the whey and curd are continuously removed. This eliminates process interruptions for sample analysis.

[0024] The dry matter content is also determined continuously.

[0025] Also advantageous is a device for producing quark comprising a nozzle separator and a control and / or evaluation unit equipped to carry out the method according to the invention. In particular, it has corresponding control electronics and a control software product stored on a memory unit.

[0026] The device can in particular have an inlet line for supplying starting product into the nozzle separator, as well as a first outlet line for discharging the whey from the nozzle separator and a second outlet line for discharging curd from the nozzle separator.

[0027] The mass flow of the whey can be determined by a flow meter, in particular a Coriolis flow meter, wherein at least one sensor of the measuring device is arranged in or along the first discharge line.

[0028] The mass flow of the starting product can advantageously be determined by a mass flow meter, in particular a Coriolis flow meter, wherein at least one sensor of the meter is arranged in or along the feed line.

[0029] The dry matter content and / or protein content can be determined by a measuring device with a sensor for emitting and / or receiving electromagnetic radiation, in particular by a microwave measurement or an infrared measurement, in particular NIR measurement, with at least the sensor of the measuring device being arranged in or along the feed line. This measurement is independent of fluctuating values ​​in pH or fat content.

[0030] Furthermore, according to the invention, the device comprises a control element, in particular a control valve, for adjusting the feed quantity and / or the mass flow of the starting product, which is arranged along the feed line.

[0031] The present process thus continuously measures the product quality and also continuously adjusts the dry matter content of the curd via the feed.

[0032] Further advantages, features, and details of the invention will become apparent from the following description, in which an exemplary embodiment of the invention is explained in more detail with reference to the accompanying drawings. Those skilled in the art will expediently consider the features disclosed in the drawings, the description, and the claims individually and combine them into useful further combinations. In particular, there are numerous possibilities for modifying and further developing the inventive method for adjusting the dry matter content within the scope of the present invention. They show: Fig. 1 is a schematic illustration of a device with a nozzle separator for carrying out the method according to the invention; and Fig. 2 is a block diagram illustrating the process flow of the method according to the invention.

[0033] The dry matter of the produced quark concentrate Q (hereinafter TM3) depends significantly on the fluctuating dry matter (TM1) of the starting product A and the mass flow of the light whey phase M with an approximately constant dry matter content TM2.

[0034] Another factor that can have a certain influence on the dry matter content is the separator's nozzle configuration, which, however, remains constant throughout the process. However, clogging of the nozzles or a reduction in the nozzle diameter can have a certain effect.

[0035] The clogging of nozzles can be detected by the method according to the invention because in such a case the mass flow ṁ3 of the quark would decrease proportionally to the number of clogged nozzles.

[0036] The feed rate is the only parameter that can be actively influenced during production to affect the DM3 of the quark. The rule of thumb is that a larger feed rate results in a higher DM of the quark concentrate.

[0037] To adjust, and in particular to regulate, the dry matter in the quark concentrate, the appropriate feed quantity can be calculated using the mass balance (Formula 1) and taking into account the theoretical flow rates of the nozzles. For this purpose, the difference between the target dry matter DM3, expressed here as c concentrate, and the approximately constant dry matter DM2 of the whey, expressed here as c whey, is set in relation to the difference between the dry matter DM1 of the starting product used, e.g., skimmed milk or fermented milk, expressed here as c starting material, and the dry matter DM2 of the whey, which is then multiplied by the nozzle flow rate.

[0038] This calculation is based on the assumption that the nozzle flow rate is precisely known. Practice has shown that this approach provides a good initial indicator of the required feed rate, although this usually needs to be adjusted after sampling the quark. m ˙ Zulauf = m ˙ D ü sen ∗ c Konzentrat − c Molke c Ausgangsprodukt − c Molke

[0039] The method described below and the correspondingly designed device compensate for the uncertainty of the unknown nozzle flow rate by measuring it via the difference in the mass flow of the starting product to the separator and the whey. For this purpose, mass flow meters are used in the inlet and outlet of the whey (see Fig. 1 ). The nozzle discharge is calculated using (Formula 2), taking into account that the measured values ​​should preferably be smoothed for approximately 60 seconds in order to determine the most constant nozzle discharge possible. m ˙ D ü sen = m ¯ ˙ Zulauf − m ¯ ˙ Molke

[0040] The dashes within the formula represent the smoothing or averaging over a specific period of time, e.g., 60 seconds. Experts will be familiar with the corresponding terms for specifying averages from the literature.

[0041] The Fig. 1 The illustrated embodiment schematically shows a device with a nozzle separator 3, preferably with a disc stack (not shown in detail), and with a rotatably mounted drum (also not shown in detail), which has a drum volume. The drum can have a vertical axis of rotation. The separator 3 has a drum volume. This drum volume results from the design-related specifications of the separator 3 and simultaneously defines a dead time.

[0042] The device 10 has an inlet line 1 leading to the nozzle separator 3, along which a control element 2 is arranged. A flow meter 9 is also arranged along the inlet line 1.

[0043] A starting product A, preferably skimmed milk or curdled milk, is fed into the nozzle separator 3, where the starting product is separated into whey M as the liquid phase and curd Q as the (solid) concentrate. While the whey is discharged from the nozzle separator 3 via the discharge line 4, the concentrate Q is discharged via nozzles through the discharge line 5. The concentrate can be discharged continuously. The concentrate Q can then be further processed and, for example, cooled.

[0044] In the device according to the invention, a flow meter 8, or at least the measuring sensor of a flow meter, is arranged in or along the outlet line 4 of the whey M. The flow of the whey M from the nozzle separator 3 can be determined, for example, as a mass flow. The measured values ​​recorded by the flow sensors 8 and 9 and the measured value of the measuring device 6 for determining the dry matter content are transmitted directly via the signal lines 11, 13, 14 to a control and / or evaluation unit 7, where the measured flow value is used as a controlled variable to determine a manipulated variable S, which is used to adjust the control element 2 via a signal line 12 between the control and / or evaluation unit 7 and the control element 2.

[0045] The dry matter content is adjusted according to the present method by determining the flow rate, in particular the mass flow rate or mass flow, of whey M in the light phase outlet line 4. In curd production, the light phase is whey. Due to the separation in the separator, the whey M always has approximately the same dry matter content and can therefore be assumed to be constant.

[0046] In addition, the mass flow in the feed line is determined. This also varies with the dry matter content of the feed product. Since the feed product can sometimes have a highly fluctuating dry matter content, the concentrate will also have a correspondingly fluctuating dry matter content. The operation of the separator and the feed flow rate must be adjusted accordingly by the control and / or evaluation unit.

[0047] If, for example, a starting product with too little dry matter is fed to the separator 3, the control element 2, e.g. a control valve, must be opened further so that more dry matter enters the separator and a sufficient amount of concentrate Q is in front of the nozzles of the separator.

[0048] By controlling the inlet flow rate of the jet separator and automatically increasing and decreasing it depending on the flow balance of the feed product and the discharged whey, the curd is adjusted to the desired dry matter content. A higher inlet flow rate results in an increase in dry matter, and vice versa.

[0049] Suitable measuring devices, especially for determining the mass flow of the starting product and the whey, are Coriolis flow meters. It is also possible to use a combination of a volume flow meter and a density meter to determine mass flow, although these are less preferred.

[0050] In the inlet of the starting product A, a sensor can also be arranged as a measuring transducer of a measuring device 6 for determining the dry matter content of the starting product. Such a sensor can, for example, be a sensor based on the measurement of electromagnetic waves. Suitable sensors for moisture measurement include microwave measuring devices, infrared measuring devices, UV-visible measuring devices, and the like. In particular, the FT 120 and FT 1 measuring devices from Foss GmbH for liquid products are worth mentioning here. For the present application, the corresponding sensor is preferably part of an inline measuring device. The use of in-line measuring technology for the direct determination of the current process states enables direct control. The requirements for this are ±0.1% measuring accuracy for the dry matter. Possible devices for this purpose are the microwave measuring devices from Berthold and ProFoss.

[0051] Measuring the dry matter, especially in the feed milk, in combination with the previously described system allows for automatic process control for different (concentrated) skim milk batches. Measuring the dry matter of the feed milk also eliminates the dead time until the new concentration is adjusted. This measurement in the feed to the separator is also suitable, as the dry matter can fluctuate there (e.g., due to sedimentation in the tank, tank changes, etc.).

[0052] Fig. 2 shows again the sequence of steps of a variant of the method according to the invention for controlling the dry matter content of concentrates in fresh cheese production, in particular in quark production by means of the Fig. 1 device shown.

[0053] In a first step 101, a starting product A is fed to the nozzle separator 3 of the device 10. This is done via the Fig. 1 shown inlet line 1.

[0054] The mass flow ṁ1 of the supplied starting product A and the dry matter content TM1 of the starting product are determined.

[0055] In the nozzle separator 3, in a second step 102, a separation takes place into an aqueous light phase, the whey M, and a solid concentrate Q, the curd, which, with respect to the whey M, represents the heavy or heavier phase.

[0056] In a third step 103, the separated phases M and Q are discharged from the separation device by means of separate discharge lines 4 and 5. The mass flow ṁ2 of the light phase, i.e. the whey M, is measured.

[0057] Based on the determined dry matter content TM1 and depending on the measured mass flow rates ṁ1 and ṁ2, in a fourth step 104 the feed quantity of starting product is adjusted by the control and / or evaluation unit 7 by generating a control signal S and ultimately also the dry matter content TM3 in the solid concentrate Q, i.e. the quark.

[0058] The measurement is preferably carried out continuously and also preferably with the aid of mass flow measuring devices in the inlet line 1 and in an outlet line 4 from the nozzle separator.

[0059] The determined dry matter content of the starting product A serves as a control variable for setting a suitable mass inflow m1 of starting product A depending on the amount of effluent whey M, whereby an intended dry matter content TM3 in the solid concentrate Q can be set.

[0060] From the mass flows of the starting product m1 and the whey m2, the mass flow m3 of curd Q in the outlet line 5 can be calculated. Using the determined dry mass TM1 of the starting product A and a known and essentially constant dry mass TM2 of the whey M, the dry mass TM3 of the curd can be calculated. This determined mass flow m3 in the outlet line 5 can be used as a control variable to determine a manipulated variable S for the continuous and automatic control of the feed quantity of the starting product.

[0061] Alternatively or for redundancy, the dry matter content of the whey can also be measured and used in the determination in step d.

[0062] With regard to EP 0 440 208 B1, the present case concerns a completely different machine which has different separation characteristics.

[0063] This process therefore ensures that there is no significant dead time and any concentration deviation in the final product is counteracted in advance.

[0064] It is possible to monitor nozzle wear via the increase in the determined discharge quantity ṁ3 of the nozzles and an indication for a necessary nozzle replacement can be generated.

[0065] A reduction in the measured nozzle discharge ṁ3 during production can also be an indicator for a blocked nozzle. For example, a change in Δ m ˙ D ü sen > 1 12 m ˙ D ü sen ¯ a possible limit.

[0066] Instead of or in addition to dry matter, protein mass can also be measured inline. The mass balance is also valid for protein, thus allowing standardization of the concentrate for protein as well. Reference symbol

[0067] 1Inlet line 2Control element 3Nozzle separator 4Outlet line (whey) 5Outlet line (curd) 6Measuring device (dry matter content determination) 7Control and / or evaluation unit 8Flow meter 9Flow meter 10Device 11Signal line 12Signal line 13Signal line 14Signal line TM1Dry matter content of starting product TM2Dry matter content of whey TM3Dry matter content of curd ṁ1Mass flow or flow of the starting product ṁ2Mass flow or flow of the whey fraction ṁ3Mass flow or flow of the curd fraction AStarting product QSolid concentrate (quark) MWhey SSetriggered variable 101First step (feeding + measuring - starting product) 102Second step (separation of fractions) 103Third step (measurement - whey) 104Fourth step (determination of dry matter content - curd)

Claims

1. Method for adjusting the dry matter content (DM3) in curd (Q) in a device (10) for centrifugally separating a starting product (A) into curd (Q) and whey (M), wherein the device (10) comprises a nozzle separator (3) and wherein the method is characterized by the following steps: a. feeding (101) the starting product (A) into a nozzle separator (3) of the device (10) via a feed line (1) while determining a content of dry matter (DM1) and / or protein, and determining, in particular measuring, the mass flow (ṁ1) of the starting product (A); b. centrifugal separation (102) of the starting product (A) by the nozzle separator (3) into a whey fraction (M) and a curd fraction (Q); c. separate discharge of the whey fraction (M) and the curd fraction (Q) from the nozzle separator (3) and determination (103), in particular measurement, of the mass flow (ṁ2) of the whey fraction (M); and d. adjusting (104) the mass flow (ṁ1) of supplied starting product (A) as a function of the values determined in steps a and c, wherein a determination of the dry matter content (DM3) and / or the protein content of the curd fraction (Q) is carried out on the basis of the determined mass flow (rh1) of the starting product (A) and the mass flow (m2) of the whey fraction (M) and the determined dry matter content (DM1) and / or protein content of the starting product (A) characterized in that the mass flows (ṁ1, ṁ2) of the starting product (A) introduced into the nozzle separator (3) and of the whey fraction (M) discharged are determined and the mass flow (ṁ3) in the discharge line (5) of the curd fraction (Q) is calculated therefrom and, in that this determined mass flow (ṁ3) in the discharge line (5) is used as a value for determining a manipulated variable for automatically controlling the feed quantity of the output product (A) and wherein the device (10) has a control element (2) for setting the mass flow (rh1) of the output product (A), which is arranged along the feed line (1).

2. Method according to claim 1, characterized in that a determination of the mass flow (ṁ3) of the curd fraction (Q) is carried out on the basis of the determined mass flow (rh1) of the starting product (A) and the mass flow (m2) of the whey fraction (M).

3. Method according to one of the preceding claims 1 or 2, characterized in that the time difference between the measurement (101) of the dry matter content (DM1) or protein content in step a and an adjustment (104) of the mass flow rate (ṁ1) in step d is less than 2 min.

4. Method according to one of the preceding claims, characterized in that the mass flows (ṁ1, ṁ2) of the starting product (A) introduced into the nozzle separator (3) and of the whey fraction (M) discharged are determined, continuously, and from this the mass flow (ṁ3) in the discharge line (5) of the curd fraction (Q) is calculated, and, in that this determined mass flow (ṁ3) in the discharge line (5) is used as a value for determining a manipulated variable for automatic, and continuous, regulation of the feed quantity of the starting product (A).

5. Method according to one of the preceding claims, characterized in that the starting product is continuously fed to the nozzle separator during curd production and that continuous discharge of whey and curd takes place.

6. Method according to one of the preceding claims, characterized in that the determination (104) in step d is carried out assuming a constant dry matter content (DM2) of whey (M) while the dry matter (DM1) of the starting product (A) varies.

7. Method according to one of the preceding claims, characterized in that the dry matter content (DM2) of the whey (M) is measured and used in the determination (104) in step d.

8. Method according to one of the preceding claims, characterized in that a clogging and / or a degree of clogging of the nozzles of the nozzle separator is determined on the basis of the determined, preferably calculated and / or measured mass flow (ṁ3) of the curd.

9. Device (10) for producing curd comprising a nozzle separator (3) and a control and / or evaluation unit (7) which is equipped for carrying out a method according to one of the preceding claims.

10. Device according to claim 9, characterized in that the device (10) comprises a feed line (1) for feeding starting product (A) into the nozzle separator (3), as well as a first discharge line (4) for discharging whey (M) from the nozzle separator (3) and a second discharge line (5) for discharging curd (Q) from the nozzle separator (3).

11. Device according to one of the preceding claims 9 or 10, characterized in that the mass flow (m2) of the whey (M) is determined by a flowmeter (8), in particular a Coriolis flowmeter, wherein at least one measuring sensor of the measuring device (8) is arranged in or along the first discharge line (4).

12. Device according to claim 11, characterized in that the mass flow (ṁ1) of the starting product (A) is determined by a flowmeter (9), in particular a Coriolis flowmeter, wherein at least one measuring sensor of the measuring device (9) is arranged in or along the feed line (1).

13. Device according to claim 11 or 12, characterized in that the dry matter content (DM3) and / or the protein content is determined by a measuring device (6) having a measuring sensor for emitting and / or receiving electromagnetic radiation, in particular by a microwave measurement or an infrared measurement, in particular NIR measurement, wherein at least the measuring sensor of the measuring device (6) is arranged in or along the feed line (1).

14. Device according to one of the preceding claims, characterized in that the device (10) comprises the regulating element (2) designated as a regulating valve.