Cleaning monitoring with surface area sensors

Description

Stand der Technik

[0001] The invention relates to a system of the type specified in the preamble of patent claim 1 and a method of the type specified in the preamble of patent claim 9.

[0002] The cleaning of plants or process equipment, e.g., food production equipment, is an essential step for product safety. Therefore, plants are traditionally cleaned according to specified cleaning programs at set times.

[0003] In order to determine the degree of contamination or the degree of cleaning of a system, capacitive sensors are used in particular to measure the formation of deposits.

[0004] For example, EP 1 376 112 B1 describes a capacitive sensor that measures deposit formation via a specially shaped capacitor. Its operation is based on the fact that the electrical impedance of the capacitor depends on the dielectric properties of the deposit deposited on the capacitor. Other known means and methods for detecting deposits on system components are described in WO 2009 / 135507 A1 and US 2013 / 003048 A1. An exemplary method for calibrating thermoelectric sensors is described in WO 2016 / 122351 A1.

[0005] A disadvantage of the known sensor technology and methodology for determining the degree of contamination or the degree of cleaning of a plant or food processing plant is, among other things, that the coating layer structure can only be measured for limited coating layer thicknesses and, for example, effective monitoring of the hygiene status of the plant across the production and cleaning cycle is not possible.

[0006] This can lead, among other things, to ineffective and inefficient cleaning processes and shortened production times, since in the absence of more accurate data on the hygiene status of the plant and due to the application of excessive safety margins, unnecessarily long cleaning times can arise, as well as an associated unnecessary consumption of resources such as water, chemicals and energy.

[0007] This can also result in incorrectly scheduled cleaning processes, i.e. those scheduled too early or too late, since it is not possible to check precisely whether cleaning is necessary.

[0008] A cleaning process can be understood, for example, as all methods or process sequences known from the state of the art for freeing a food processing plant from any contamination without significant dismantling. In particular, this includes the so-called "cleaning in place" (CIP) and the so-called "sterilization in place" (SIP) processes. CIP processes can be carried out as follows: rinsing the plant with water, cleaning the plant with an alkaline agent, e.g., at elevated temperature, rinsing the plant, cleaning the plant with an acidic cleaning agent, e.g., at elevated temperature, rinsing the plant with water. If additional sterilization (SIP), for example, is required, the plant can be treated with a sterilizing agent such as water at a temperature greater than 120°C or a chemical sterilizing agent. Depending on the requirements, alkaline cleaning alone may be sufficient.For products that are particularly difficult to clean, acid cleaning can also be carried out before alkaline cleaning. Aufgabe

[0009] It is therefore an object of the invention to provide means with which the monitoring of the hygiene status of a plant or process plant, e.g. a plant for food production, can be improved, in particular, for example, with regard to the efficiency and effectiveness of the monitoring of the hygiene status, as well as with regard to the efficiency and effectiveness of the cleaning of the plant. Lösung

[0010] This is achieved according to the invention by a system according to claim 1 and a method according to claim 9. Advantageous embodiments and further developments are the subject of the subclaims.

[0011] A system for monitoring the hygiene status of a processing plant, e.g., a food processing plant, and for monitoring and controlling a cleaning process of the processing plant, e.g., a food processing plant, comprises at least two deposit sensors for measuring deposits on parts of the processing plant, e.g., a food processing plant, wherein the at least two deposit sensors have different measuring ranges. Furthermore, the at least two deposit sensors can be configured to operate according to different measuring principles.

[0012] Deposits can be understood as any undesirable deposits on plant components, in particular, for example, on the internal walls of plants (in particular, for example, the internal walls of pipes), such as, for example, mineral, organic and mixed organic-mineral deposits.

[0013] Typical deposits or contaminants such as mineral substances, proteins or starch can be deposited particularly on parts or surfaces with a higher temperature than the ambient temperature, such as heat exchangers.

[0014] The measurement of coverings refers to measurements of the covering layer thickness.

[0015] However, the measurement of deposits may also include the measurement of other physical properties of the deposit and / or the environment of the process plant, e.g. food plant, in which the deposit forms and / or a product of the process plant, e.g. food plant, for example a product or cleaning medium flowing through the process plant, e.g. food plant.

[0016] A property to be measured or a physical property to be measured can be, for example, an electrical or thermal conductivity, an electrical capacitance, a heat capacity, and / or optical absorption and / or emission properties, e.g. fluorescence properties, and / or one or more of the following properties such as flow velocity, flow rate, turbidity, colour, pH value, temperature, pressure orPressure loss in the system, thermal conductivity of a pipe's outer wall, concentration of certain particles in the cleaning medium and / or in the product, presence of volatile components; product properties of the processed product, for example viscosity, composition, measured values ​​from online titrations, transmission or reflection measurements, measured values ​​of reactions from various online flow injection analyses, UV adsorption measurements, vibration and damping properties, ultrasonic measurements, wavelength-dependent light scattering, and / or optical activity (change in polarization angle).

[0017] The use of deposit sensors with different measuring ranges and / or that operate according to different measuring principles can enable reliable, more comprehensive, and continuous monitoring of the system's hygiene status throughout production and cleaning cycles. In particular, the level of contamination of the system during production and the level of cleaning or decontamination during a system cleaning process can be better monitored and controlled.

[0018] Instead of cleaning according to rigidly specified parameters or, for example, only depending on a single unreliable capacitive deposit sensor that only measures a limited deposit layer thickness, a system according to the invention can make it possible to clean the system as needed.

[0019] In other words, the time at which cleaning is useful or necessary and / or the time at which cleaning can be stopped can be better determined and, for example, unnecessary cleaning can be avoided, which causes unnecessary costs and unnecessary energy consumption.

[0020] This can also increase the efficiency and effectiveness with which a cleaning process can be monitored. This can, among other things, lead to minimizing downtime and the consumption of resources such as cleaning agents.

[0021] By cleaning the system as required depending on the contamination as production progresses, as well as by a cleaning program that can be precisely adapted to the contamination, the time required for cleaning can be reduced to a minimum and at the same time product safety can be increased.

[0022] For example, the system can be designed such that at least one pavement sensor can be configured to measure virtually unlimited pavement layer thicknesses, or can be configured to measure thicker or stronger pavement layer thicknesses than, for example, a capacitive pavement sensor. For example, such a pavement sensor can be an ultrasonic pavement sensor.

[0023] For example, the system can be designed such that at least one pad sensor can be a capacitive pad sensor and at least one pad sensor can be an ultrasonic pad sensor.

[0024] It is also conceivable that, alternatively or additionally, at least one deposit sensor could be an optical deposit sensor, a thermal deposit sensor, a deposit sensor with conduction measurement, a deposit sensor with fluorescence measurement, or a deposit sensor with absorption measurement. These types of deposit sensors can also be configured to measure virtually unlimited deposit layer thicknesses, or can be configured to measure thicker or stronger deposit layer thicknesses than, for example, a capacitive deposit sensor.

[0025] A thermal deposit sensor can, for example, comprise a temperature sensor and at least one temperature emitter configured to couple thermal energy, e.g. to apply a time-varying temperature profile, into a location of the process plant to be examined, e.g. a food plant.

[0026] The variety of deposit sensors that can be used can increase the accuracy with which deposit formation can be measured.

[0027] Furthermore, the measuring ranges of the pavement sensors can complement each other. This can mean, for example, that the measuring ranges of different pavement sensors are complementary to each other, although the measuring ranges may partially overlap. However, it is also possible that the measuring ranges of the different pavement sensors do not overlap. It is also conceivable, however, that the measuring range of one pavement sensor also includes the measuring range of another.

[0028] For example, the measuring range of at least one pavement sensor can comprise pavement layer thicknesses close to or equal to zero and / or the measuring range of at least one further pavement sensor can comprise pavement layer thicknesses with a maximum tolerable pavement layer thickness.

[0029] In other words, one pavement sensor can measure thin pavement thicknesses, while another pavement sensor can measure thick pavement thicknesses. Thin pavement thicknesses can be understood as pavement thicknesses from 0 to 0.5 mm, thick pavement thicknesses, for example, from 0.5 mm to 5 mm, and a maximum tolerable pavement thickness, for example, up to 5 mm.

[0030] However, said exemplary coating layer thicknesses or coating layer thickness values ​​can also depend on the type of coating or the coating hardness, since, for example, softer coatings can be easier to remove than harder coatings, softer coatings can, for example, have a greater maximum tolerable coating layer thickness than comparatively harder coatings.

[0031] For example, it is conceivable that two different pavement sensors measure different pavement layer thicknesses, for example a capacitive pavement sensor measures thin pavement layers or thin pavement layer thicknesses, and for example a second pavement sensor is used by means of an ultrasonic measuring method to measure thicker pavement layers or thicker pavement layer thicknesses.

[0032] This can, for example, make it easier to determine whether and when cleaning of the process plant, e.g. food plant, is necessary, for example when the deposit sensor detects that a maximum tolerable deposit layer thickness has been exceeded, the measuring range of which includes the maximum tolerable deposit layer thickness.

[0033] Furthermore, it is conceivable that different pavement sensors could perform measurements with different resolutions. For example, it would be conceivable that a pavement sensor for thin pavement thicknesses could be equipped or operated with a higher spatial or layer thickness resolution than a pavement sensor for thick pavement thicknesses.

[0034] This can, for example, enable more precise monitoring of the cleaning process of the process plant, e.g. food plant, since it can be determined more precisely whether and when a reduction in the coating layer thickness due to the cleaning process has been achieved, the coating layer thickness to zero or almost zero within a specified tolerance, and thus the part of the process plant to be cleaned or the entire process plant, e.g. food plant, can be regarded as clean and hygienically clean.

[0035] Depending on the type of pavement and the type of pavement sensor, typical resolutions for measuring pavement thickness can be between + / - 0.5 and + / - 5 µm for thin pavements and between + / - 5 and + / - 50 µm for thicker pavements.

[0036] As already mentioned, at least one coating sensor can be configured, in addition to measuring a coating layer thickness, to measure another physical property(ies) of the coating to be examined and / or the environment of the process plant, e.g. food plant, in which the coating forms and / or a product of the process plant, e.g. food plant.

[0037] For example, a coating sensor can be configured to measure a physical property of a medium flowing through the point to be examined, in particular, for example, be configured to measure the electrical conductivity of a medium or fluid or fluid mixture flowing through the point to be examined, for example by means of electrically capacitive measurement of changes in the electrical conductivity of the medium flowing through the point to be examined.

[0038] This can, for example, allow the cleaning process to be monitored more effectively, as the rinsing of a cleaning medium with water can be better observed and timed.

[0039] In a system for monitoring the hygiene status of a process plant, e.g. food plant, and for monitoring and controlling a cleaning process of the process plant, e.g. food plant, at least one deposit sensor, for example in particular at least one deposit sensor which is configured to be able to measure thin deposit layer thicknesses, can be attached to a location which is difficult to clean or to the location of the process plant, e.g. food plant, which is most difficult to clean.

[0040] Examples of locations in the process plant that are difficult or most difficult to clean, e.g. food plant, can include high-temperature areas of heat exchangers, pre-denaturation stages, ring vessels or central vessels of a filling device, filling valves, buffer tanks, dead spots, undercuts, pipe extensions, transitions from seals to materials, heated surfaces, surfaces for heat transfer or with a temperature difference.

[0041] Furthermore, additionally or alternatively, at least one deposit sensor, for example, in particular at least one deposit sensor configured to measure thicker or greater deposit layer thicknesses, can also be mounted at a location with increased deposit formation compared to other locations in the process plant, e.g., a food plant, e.g., at a location with maximum deposit formation. The increased deposit formation can be caused, for example, by a temperature difference prevailing at said location compared to surrounding locations, which promotes deposit formation.

[0042] This area with increased deposit formation can be different from an area that is difficult to clean, i.e. it can be comparatively easy to clean.

[0043] Such an exemplary arrangement can, for example, help to ensure that the process plant, e.g. food plant, has been reliably hygienically cleaned, since it can be assumed, for example, that if a difficult or most difficult to clean point is found to have been satisfactorily cleaned and / or if a particularly heavily soiled point in the process plant, e.g. food plant, compared to other points in the process plant, e.g. food plant, is found to have been satisfactorily cleaned, the entire process plant, e.g. food plant, has been completely and satisfactorily cleaned.

[0044] This makes it easier to ensure that the system has been satisfactorily cleaned, especially in cases where the process plant, e.g. food plant, is heavily soiled.

[0045] Furthermore, the at least one deposit sensor can be heated. This can be used, for example, to simulate a location in the process plant, such as a food processing plant, that has a higher temperature than other parts of the plant and may therefore be more susceptible to increased deposit formation.

[0046] In this way, even in the event that the deposit sensor cannot be attached directly to such a location in the process plant, e.g. food plant, with an elevated temperature, it can be ensured that the deposit formation or the hygiene status and / or cleaning process for the location in the process plant, e.g. food plant, with an elevated temperature can be monitored and controlled.

[0047] A method for monitoring the hygiene status of a process plant, e.g. food plant, and for monitoring and controlling a cleaning process of the process plant, e.g. food plant, comprises the following steps: Monitoring the hygiene status during production by monitoring the formation of deposits on at least one part of the process plant, e.g. food plant, during production, by means of at least one deposit sensor whose measuring range includes deposit layer thicknesses with a predetermined maximum tolerable deposit layer thickness, initiating or initiating a cleaning process of the process plant, e.g. food plant, when the at least one deposit sensor determines that the deposit layer thickness exceeds or has exceeded the predetermined maximum tolerable deposit layer thickness, monitoring the hygiene status during production and / or monitoring and / or ending the initiated cleaning process by at least one further deposit sensor whose measuring range is different from the measuring range of the first deposit sensor, in particular whose measuring range can include, for example, deposit layer thicknesses of close to or equal to zero.

[0048] For example, flexible monitoring of the hygiene status of the process plant, e.g. food plant, during production and during a cleaning process can be ensured as needed, and the times for the start and end of cleaning can be better determined, thus allowing the start and end of cleaning to be controlled in a targeted and precise manner.

[0049] This can, for example, improve the accuracy with which a cleaning process can be monitored, since, in particular, the end of cleaning can be determined better and more accurately.

[0050] It is also conceivable that the second deposit sensor, whose measuring range can encompass deposit thicknesses close to or equal to zero, for example, could have a higher resolution than the deposit sensor, whose measuring range encompasses deposit thicknesses with a predetermined maximum tolerable deposit thickness. This could further increase the accuracy with which a cleaning process can be monitored and, for example, the end of cleaning can be determined.

[0051] The at least one deposit sensor, the measuring range of which can comprise deposit layer thicknesses with a predetermined maximum tolerable deposit layer thickness, and / or the optional at least one deposit sensor, the measuring range of which comprises deposit layer thicknesses close to or equal to zero, can be, for example, a deposit sensor of the type described above, i.e., for example, a capacitive deposit sensor, or an ultrasonic deposit sensor, or an optical deposit sensor, or a thermal deposit sensor, or a deposit sensor with conduction measurement, or a deposit sensor with fluorescence measurement, or a deposit sensor with absorption measurement.

[0052] Furthermore, it is possible, for example, that the monitoring of the deposit formation on at least one part of the process plant, e.g. food plant, during production is initially carried out by the deposit sensor, the lower measuring range of which includes deposit layer thicknesses of close to or equal to zero, and only when the upper end of the measuring range of the deposit sensor with the lower measuring range of deposit layer thicknesses of close to or equal to zero is reached, the monitoring of the hygiene state during production is switched over to the deposit sensor, the measuring range of which includes deposit layer thicknesses with a predetermined maximum tolerable deposit layer thickness.

[0053] It is also possible, for example, that the monitoring of the initiated cleaning process is initially carried out by the deposit sensor whose lower measuring range includes deposit layer thicknesses with a predetermined maximum tolerable deposit layer thickness, and only when the lower end of the measuring range of the deposit sensor with measuring range for deposit layer thicknesses with a predetermined maximum tolerable deposit layer thickness is reached or when its lower detection limit for deposits or deposit layer thicknesses is reached, the monitoring of the initiated cleaning process is switched to the deposit sensor whose lower measuring range includes deposit layer thicknesses close to or equal to zero, and which can, for example, have a higher resolution.

[0054] If, for example, the lower detection limit or a specified tolerance limit of the deposit sensor, whose lower measuring range covers deposit layer thicknesses close to or equal to zero, is reached, the cleaning process can be terminated at the instigation of the deposit sensor or deposit sensor system. For this purpose, a signal can also be output, for example, indicating the end of the cleaning process.

[0055] In addition, the monitoring and / or control of the / an initiated cleaning process can additionally comprise the monitoring of a rinsing, e.g. with water, of a cleaning medium, wherein the monitoring of the rinsing can be carried out by means of a sensor which can be configured to measure a physical property of a medium flowing through the location to be cleaned, thus for example can be configured to measure the electrical conductivity of a medium flowing through the location to be cleaned.

[0056] This can, for example, improve the control of the cleaning process and make it easier to detect when the cleaning process has been completed.

[0057] As mentioned, these exemplary process steps can improve hygiene and product safety, as well as minimize production downtime of the process plant, e.g. food plant.

[0058] As mentioned, a system for monitoring the hygiene status of a process plant, e.g. food plant, and for monitoring and controlling a cleaning process of a process plant, e.g. food plant, may also include a thermal deposit sensor.

[0059] This optional exemplary thermal deposit sensor can comprise at least one temperature sensor and at least one temperature emitter, and can be configured to couple thermal energy into a location to be examined in the process plant, e.g. a food plant, which may be contaminated with a deposit.

[0060] For example, the thermal deposit sensor can be configured to apply a time-varying, e.g. periodically changing, temperature profile to a location of the process plant to be examined, e.g. food plant.

[0061] The thermal energy coupled, for example, by the temperature emitter at the point / area of ​​the process plant under investigation, e.g., a food plant, or the time-varying temperature profile applied, can trigger a delayed temperature change or a delayed time-varying temperature profile at the point of the plant under investigation. The magnitude or amplitude and delay, or phase or phase difference, of this change can be measured, for example, by the temperature sensor of the thermal deposit sensor. From these measurements of the magnitude or amplitude and delay (phase or phase shift or phase difference) of the temperature change(s) triggered at the point of investigation, conclusions can be drawn about the presence and thickness of a deposit.

[0062] This type of heat flow thermography can also contribute to more accurate and improved monitoring of the level of contamination of the plant during production and the monitoring of the level of cleaning or decontamination during a plant cleaning process.

[0063] The exemplary optional thermal deposit sensor or an exemplary temperature emitter of the thermal deposit sensor, comprising e.g. heat radiators and / or heating or cooling element(s) and / or ultrasonic transmitter, can be configured as follows: that the application of a time-varying, e.g. periodically changing, temperature profile to a point of the process plant to be examined, e.g. food plant, can be carried out by periodic heating and cooling of a medium, e.g. cleaning medium, by heating or cooling elements in front of the point to be examined, for example with a constant media flow, and / or that the application of a time-varying temperature profile to a point of the process plant to be examined, e.g. food plant, can be carried out by heat irradiation from a point opposite the point to be examined, the irradiation point, through a medium, e.g. product or cleaning medium, whereby the irradiation point can be designed, for example, in such a way that a reduced formation of deposits takes place or is present there, whereby this can be achieved if necessary by cooling the irradiation point, e.g.Peltier cooling, and / or that the application of a time-varying temperature profile to a point of the process plant to be examined, e.g. food plant, can be achieved by exciting the point to be examined with ultrasound through a medium, e.g. product or cleaning medium.

[0064] In other words, alternatively or additionally, a method for monitoring the hygiene status of a process plant, e.g. food plant, and for monitoring and controlling a cleaning process of the process plant, e.g. food plant, may comprise one, some or all of the following steps: an application of a time-varying temperature profile to a part of the process plant to be examined, e.g. food plant, a measurement of the temperature change triggered by the application to the part of the process plant to be examined, e.g. food plant, with amount and delay to determine the presence and strength of the deposit formation, e.g. the strength of the deposit layer thickness.

[0065] For this purpose, in particular, a periodic temperature profile can be applied with a frequency in the range of 10 mHz to 1 Hz, or with an experimentally determined frequency depending on the mechanical dimensioning of the point of the process plant to be examined, e.g. food plant.

[0066] In addition, for example, the temperature profile measurement of the triggered temperature change can be carried out by a specially designed point or measuring point to be examined.

[0067] For example, it is conceivable that an outer wall of the measuring point is tapered and, if necessary, mechanically reinforced. This can simplify the measurement of the induced temperature change without compromising the homogeneity of the measuring point.

[0068] In particular, this can be done without impairing the homogeneity of an inner wall of the measuring point, so that the measuring point can exhibit the same deposit behavior for deposits as the normal wall points.

[0069] The exemplary steps described can exploit the following two physical effects.

[0070] On the one hand, existing deposits at the point to be examined will cause a delay, i.e. a phase shift of the heat conduction to the sensor, ie to the temperature sensor of the thermal deposit sensor, which increases with the thickness of the deposit.

[0071] On the other hand, a coating (exemplary emissivity for thermal infrared radiation ~ 0.9) will absorb the heat input or heat impact much more than the construction material of the system at the point to be examined, for example brightly polished stainless steel (e.g. with emissivity < 0.1), which essentially reflects away the incoming thermal radiation, and thus the amplitude of the measured temperature curve measurement of the triggered temperature change is increased by the coating compared to a part of the system without or with less coating.

[0072] For the sake of completeness, it should be mentioned that when cleaning a system, it is important to ensure that the entire surface is thoroughly cleaned. However, depending on the complexity of the components or system components, the difficulty of cleaning surfaces varies. Therefore, cleaning should be carried out in such a way that even the most inappropriate component, the one that is most contaminated or most difficult to clean, is completely cleaned, thus minimizing any potential hygiene risks.

[0073] The most difficult-to-clean area is usually characterized by a complex mechanical structure, such as undercuts, transitions from seals to materials, surfaces for heat transfer, or surfaces with a temperature difference. This can be determined, among other things, through empirical determination through cleaning tests or through a theoretical evaluation of the system's design, taking into account the respective environmental and operating conditions.

[0074] Therefore, alternatively or additionally, a method for monitoring the hygiene status of a process plant, e.g. food plant, and for monitoring and controlling a cleaning process of the process plant, e.g. food plant, may comprise one, some or all of the following steps: a direct measurement of the degree of contamination or hygiene or degree of cleaning or decontamination of the process plant, e.g. food plant, on a part of the process plant, e.g. food plant, e.g. a direct measurement of deposits on a part of the process plant, e.g. food plant, whereby the measurement can be carried out directly on a part of the process plant, e.g. food plant, that is difficult to clean, e.g. high-temperature areas of heat exchangers, pre-denaturation stages, ring boilers or central boilers of a filling device, filling valves, buffer tanks, dead spots, undercuts, pipe extensions, transitions from seals to materials, heated surfaces, surfaces for heat transfer or with a temperature difference, and / or a measurement of the degree of contamination or hygiene or degree of cleaning or decontamination of the process plant, e.g.Food processing plant, by measuring the degree of contamination or hygiene status on an indicator component, whereby the indicator component can simulate a difficult-to-clean area of ​​the process plant, e.g. food processing plant, and / or the indicator component can simulate a area of ​​the process plant, e.g. food processing plant, with increased deposit formation.

[0075] The indicator component or reference component can also be heated to improve the simulation of a location that is difficult to clean, e.g. to simulate a heat exchanger, or to simulate a location with increased deposit formation.

[0076] The steps described can increase the efficiency and effectiveness of monitoring the hygiene status of a process plant, e.g. food plant, and the monitoring and control of a cleaning process of the process plant, e.g. food plant, since it can be assumed, for example, that if the difficult or most difficult to clean area or the simulated difficult to clean area is clean, e.g. without deposits, the rest of the plant is also clean or hygienically clean.

[0077] The measurement of the degree of contamination or hygiene status of the process plant, e.g. food plant, by measuring the degree of contamination or hygiene status on an indicator component, can also include a step in which a ratio factor is determined from deviations in the cleanability or contamination of the indicator component compared to the cleanability or contamination of the difficult-to-clean area of ​​the process plant, e.g. food plant, which is taken into account when carrying out a cleaning process.

[0078] To determine or measure the degree of contamination or hygiene status, coating sensors of the type described above can be used, for example capacitive coating sensors, or ultrasonic coating sensors, or optical coating sensors, or thermal coating sensors, or coating sensors with conduction measurement, or coating sensors with fluorescence measurement, or coating sensors with absorption measurement.

[0079] The above-mentioned exemplary pavement sensors can be integrated into the area to be examined or into the surface to be measured.

[0080] Alternatively or additionally, optical measurement methods with different wavelength ranges can be used. For this purpose, at least one inspection glass or an optical opening can be installed so that the area under investigation or the indicator component can be observed using an evaluation unit (e.g., an optical unit, e.g., an optical deposit sensor). Wavelength ranges for such optical checks or measurement methods can be, for example, in the UVA / UVB range between 300 and 400 nm, and / or in the visible range between 400 and 700 nm, and / or in the NIR range between 700 and 1000 nm, and / or in the SWIR range between 1000 and 2500 nm.

[0081] During cleaning, it is then possible, for example, to monitor the cleanliness level of the area under investigation or the indicator component using the optical unit, and cleaning can be continued until it is completely clean. Optical evaluation can be carried out using the principle of direct observation (e.g., via video camera), reflection (e.g., using fluorescence measurement), or transmitted light.

[0082] Since, as mentioned, the optional indicator component may correspond to the component that is most difficult to clean and / or the area with increased deposit formation, it can be assumed that the entire system is in the desired condition when this component is clean.

[0083] The means and method steps described here can all be combined with one another and can work synergistically to improve the monitoring of the hygiene status of a processing plant, e.g., a food plant, and the monitoring and control of a cleaning process within the processing plant, e.g., a food plant. In particular, for example, the plant can be cleaned as needed or adapted to the current level of contamination. This can ensure, among other things, safe production with the lowest possible use of cleaning media. The invention, or rather the means described, are particularly important, for example, in potentially shortening the cleaning time, which can maximize the plant's production time.

[0084] The following figures are examples: Fig.1a: Example measuring ranges of two example pad sensors Fig.1b: Another example of measuring ranges of two exemplary pad sensors Fig. 2: Example arrangement of an example thermal deposit sensor Fig. 3: Example of applied temperature profile and example of triggered measured time-varying temperature profile Fig. 4: Example arrangement of an example optical coating sensor

[0085] The Fig. 1a shows, by way of example, a possible measuring range division 100 of exemplary measuring ranges 105, 106 of two exemplary pad sensors, wherein the pad sensors (not shown) can be constructed according to one of the types described above or can operate according to the various measuring principles described above.

[0086] In addition, an exemplary contamination profile 107 of a part of a process plant to be examined, e.g., a food plant, is shown. This profile 107 can, for example, represent the progression or change in the layer thickness 102 of a coating as a function of time 101.

[0087] For example, two different process or time periods 103, 104 are shown, wherein the first process or time period 103 can represent, for example, the change in the coating thickness when coatings form in a process plant, e.g. food plant, during production, and the second process or time period 104 can represent the change in the coating thickness when coatings are broken down or removed during cleaning.

[0088] As shown, the pad sensors, for example, which operate according to different measuring principles, can have measuring ranges 105, 106 that do not overlap.

[0089] In this case, an exemplary first measuring range 105 of a first pavement sensor can comprise pavement layer thicknesses with a maximum tolerable pavement layer thickness 108.

[0090] For example, if it is determined that the coating layer thickness exceeds the specified maximum tolerable coating layer thickness 108, cleaning 104 can be initiated.

[0091] The illustrated exemplary second measuring range 106 of a second pavement sensor can, for example, comprise pavement layer thicknesses close to or equal to zero.

[0092] Both measuring ranges 105, 106 can also be further divided into various sub-ranges (not shown). For example, measuring range 105 can contain an upper and lower measuring range. Likewise, measuring range 106 can contain an upper and lower measuring range.

[0093] For example, the progress of cleaning or deposit removal can be monitored and, if satisfactory removal or sufficient reduction of the deposit is determined, cleaning 104 can be terminated and the process plant, e.g. food plant, can return to production operation 103.

[0094] The Fig. 1b represents by way of example a further possible measuring range division 200 of exemplary measuring ranges 205, 206 of two exemplary pad sensors, wherein the pad sensors (not shown) can again be constructed according to one of the types described above or can operate according to the various measuring principles described above.

[0095] Analogous to Fig.1a For example, two different process or time periods 203, 204 are shown, wherein the first process or time period 203 can, for example, represent the change in the coating thickness when a coating forms in a process plant, e.g. a food plant, during production, and the second process or time period 204 can represent the change in the coating thickness when the coating is removed during cleaning.

[0096] As shown, for example, the pad sensors, which operate according to different measuring principles, can be used in contrast to Fig. 1a but have measuring ranges 205, 206 that overlap.

[0097] In this case, an exemplary first measuring range 205 of a first pavement sensor can in turn comprise pavement layer thicknesses with a maximum tolerable pavement layer thickness 208.

[0098] For example, if it is determined that the coating layer thickness exceeds the specified maximum tolerable coating layer thickness 208, cleaning 204 can be initiated.

[0099] The illustrated exemplary second measuring range 206 of a second pavement sensor can, for example, include pavement layer thicknesses close to or equal to zero.

[0100] Both measuring ranges 205, 206 can also be analogous to Fig. 1a be further divided into various sub-ranges (not shown). For example, measuring range 205 may contain an upper and lower measuring range. Likewise, measuring range 206 may contain an upper and lower measuring range.

[0101] The exemplary possible overlap of the measuring ranges 205, 206 can, among other things, enable more precise or more seamless monitoring of the hygiene status of a process plant, e.g. a food plant.

[0102] The Fig. 2 represents by way of example a possible arrangement of an exemplary thermal deposit sensor 310 for a system for monitoring the hygiene status of a process plant, e.g. food plant, and for monitoring and controlling a cleaning process of a process plant, e.g. food plant, which can have, for example, a temperature sensor 302 and at least one temperature emitter 301, configured for coupling thermal energy, e.g. for applying a time-varying, e.g. periodically changing, temperature profile, into a location 306 to be examined of a part 304, e.g. a pipe wall, of the process plant, e.g. food plant.

[0103] Instead of a heat radiator, it is also conceivable to use an ultrasonic transducer to couple heat energy or to apply a time-varying temperature profile.

[0104] The temperature profile measurement of the temperature change triggered by the application of a time-varying temperature profile can be carried out at a specially designed point to be examined or measuring point 306.

[0105] For this purpose, it is conceivable, for example, that an outer wall of the measuring point is tapered, as shown. This can simplify the measurement of the triggered temperature change without impairing the homogeneity of the measuring point, in particular without impairing the homogeneity of an inner wall of the measuring point, so that the measuring point can exhibit the same deposition behavior for deposits 310 as on the surrounding normal components.

[0106] As shown, for example, the temperature emitter 301 may be arranged opposite the temperature sensor 302 of the exemplary thermal deposit sensor 310.

[0107] Alternatively and / or additionally, the application of a time-varying temperature profile to a location 306 of the process plant to be examined, e.g. food plant, can be carried out by periodically heating and cooling a medium 308, e.g. cleaning medium, by optional heating or cooling elements 303.

[0108] Said optional heating or cooling elements 303 can be arranged in front of the location to be examined, so that, for example, the medium 308 can be subjected to a time-varying temperature profile before reaching the locations to be examined.

[0109] In addition, for example, the time-varying temperature profile can be applied at a constant media flow 307.

[0110] When using the optional heating or cooling elements 303, the thermal deposit sensor 310 can, under certain circumstances, also be operated without an (additional) temperature emitter opposite the temperature sensor 302.

[0111] The application of a time-varying temperature profile to a point 306 of the process plant to be examined, e.g. food plant, by means of heat irradiation can take place from a point 305 opposite the point to be examined, the irradiation point, through a medium 308, e.g. product or cleaning medium, wherein the irradiation point can be designed, for example, in such a way that a reduced formation of deposits occurs or is present there, wherein this can be achieved if necessary by cooling the irradiation point, e.g. Peltier cooling (not shown).

[0112] The Fig. 3 represents exemplary heat profiles or temperature profiles 400, i.e. the dependence of heat or temperature 402 on time 401.

[0113] The profile 403 represents, for example, a time-varying temperature profile 403, which is applied, for example, by means described above, and which can be applied to a point to be examined in a process plant (not shown), for example a food plant.

[0114] Profile 403 can also be referred to as an exemplary excitation profile.

[0115] As shown, the exemplary variable temperature profile 403 or excitation profile is periodically variable and has an exemplary amplitude 406.

[0116] The profile 404 represents, for example, the temperature change measured by a thermal deposit sensor and triggered by the excitation profile 403, or the temperature profile measured by a thermal deposit sensor and triggered by the excitation profile 403, for example, at the part / location of the process plant to be examined, e.g. food plant.

[0117] Profile 404 can also be referred to as an exemplary measurement profile.

[0118] As described above, the presence and intensity of the deposit formation or the thickness of the deposit layer can be determined from the exemplary measurement profile 404 by measuring the amount or amplitude 407 and the delay or phase difference 405 of the measurement profile 404 in comparison to the excitation profile.

[0119] For example, the relationship between the measured amplitude 407 and the measured phase difference 405 can be a function of the thermal conductivity of the coating and / or the coating thickness and / or the measurement profile 404. For example, with a comparatively lower thermal conductivity, a reduction in the amplitude and a larger phase shift or phase difference 405 can be expected. Likewise, a greater coating thickness can reduce the amplitude 407 and increase the phase shift or phase difference 405.

[0120] The Fig. 4 illustrates an example of a possible arrangement 500 of an exemplary optical deposit sensor together with an exemplary indicator component 505.

[0121] The indicator component 505 can, for example, be mounted at a location in the process plant that is difficult to clean, e.g., a food plant.

[0122] Alternatively, the indicator component 505 can be attached to any location 507 of the process plant to be examined, e.g., a food plant, for example, at a location on a pipe wall 501, and the indicator component 505 can be configured to simulate a location of the process plant, e.g., a food plant, that is difficult to clean and / or a location with increased deposit formation.

[0123] To improve the simulation of an area that is difficult to clean or an area with increased deposit formation, the indicator component 505 can optionally also be heated via a heating element.

[0124] It is also conceivable that, for example, the indicator component 505 can be heated with a time-varying temperature profile.

[0125] To measure the degree of contamination or hygiene status, or to measure the formation of deposits at the point of the process plant to be examined, e.g. food plant, the indicator component 505 can be observed using optical measuring methods.

[0126] For this purpose, for example, an optical deposit sensor 503, e.g. a camera, which can be arranged opposite the indicator component 505, can optically detect and measure the deposit formation on the indicator component via a measuring light beam 504.

[0127] The measuring light beam 503 can detect the indicator component, for example, via an optical opening, e.g. a sight glass, mounted in / on a part of the system location to be examined opposite the indicator component 505.

[0128] There follow 5 sheets with figures Fig. 1a , Fig. 1b , Fig. 2 , Fig. 3 and Fig. 4 .

[0129] The reference symbols are assigned as follows. 100Example measuring range division 101 Example abscissa axis, e.g. time axis 102 Example ordinate axis, e.g. axis that measures the degree of soiling or cleaning, e.g. the coating layer thickness and / or other physical properties of a coating or product 103 Example (first) plant process section, e.g. food plant process section, e.g. production section 104 Example (second) plant process section, e.g. food plant process section, e.g. cleaning section 105 Example (first) measuring range of a (first) pad sensor 106 Example (second) measuring range of a (second) pad sensor 107 Example of a contamination progression of a part of a process plant to be examined, e.g. food plant, example of a contamination progression of the formation or removal of the contamination, e.g. progression of the contamination layer thickness 108Example of maximum tolerable pavement thickness 200 Example measuring range division 201 Example abscissa axis, e.g. time axis 202 Example ordinate axis, e.g. axis that measures the degree of soiling or cleaning, e.g. the coating layer thickness and / or other physical properties of a coating or product 203 Example (first) plant process section, e.g. food plant process section, e.g. production section 204 Example (second) plant process section, e.g. food plant process section, e.g. cleaning section 205 Example (first) measuring range of a (first) pad sensor 206 Example (second) measuring range of a (second) pad sensor 207Example of a contamination progression of a part of a process plant to be examined, e.g. food plant, example of a contamination progression of the formation or removal of the contamination, e.g. progression of the contamination layer thickness 208 Example of maximum tolerable pavement thickness 300 Example arrangement of an example thermal deposit sensor 301 Example part of an example thermal deposit sensor, e.g. temperature emitter, e.g. heat radiator and / or ultrasonic transducer 302 Example part of an example thermal pad sensor, e.g. temperature sensor 303 Example heating and / or cooling elements, e.g. also to be understood as part of the temperature emitter 304 Example part of the food plant to be examined, e.g. pipe wall 305 Example location for coupling / irradiation / application of thermal energy 306Example measuring point / example point to be examined 307 Example media flow 308 Example medium, e.g. product and / or cleaning medium 309 Contamination, e.g. coating 310 Example thermal deposit sensor 311 Contamination, e.g. coating 400 Example temperature profiles 401 Example abscissa axis, e.g. time axis 402 Example ordinate axis, e.g. temperature axis or heat energy axis 403 Example of a time-varying temperature profile, example of an excitation profile 404 Example measured temperature profile triggered by excitation, e.g. excitation profile 403, on the part / location of the system to be examined, example measurement profile 405 Example delay, example phase difference between excitation profile and measurement profile 406Example amplitude of the applied time-varying temperature profile 407 Example amplitude of the measured temperature profile triggered by excitation, e.g. excitation profile 403 500 Example arrangement of an example optical coating sensor 501 Example part to be examined, e.g. pipe wall, of a process plant, e.g. food plant 502 Example location for coupling / irradiation of a measuring beam, e.g. a light beam, example optical opening or sight glass 503 Example pad sensor, e.g. optical pad sensor 504 Example measuring beam, e.g. light beam 505 Example indicator component or reference component 506 Example optional heating element 507 Example of an area to be examined, e.g. an area that is difficult to clean:

Claims

1. A system for monitoring the hygienic status of a process plant and for monitoring and controlling a cleaning process of the process plant comprising: at least two film sensors for measuring the thickness of films on parts of the process plant (304) wherein the at least two film sensors have different measuring regions (105, 106).

2. The system according to claim 1, wherein at least one film sensor is a capacitive film sensor and at least one film sensor is an ultrasonic film sensor and / or wherein alternatively or additionally at least one film sensor is an optical sensor or a thermal film sensor or a film sensor using conductivity measurement or a film sensor using fluorescence measurement or a film sensor using absorption measurement.

3. The system according to any one of the preceding claims, wherein the measuring regions (205, 206) of the film sensors partially overlap.

4. The system according to any one of the preceding claims, wherein the measuring region (106) of at least one film sensor comprises film thicknesses near or equal to 0 and / or the measuring region (105) of at least one film sensor comprises film thicknesses including a maximum tolerable film thickness.

5. The system according to any one of the preceding claims, wherein at least one film sensor is alternatively or additionally configured to measure a physical property of a medium (308) flowing through the position to be inspected, and is, for example, configured to measure the electric conductivity of a medium (308) flowing through the position to be inspected.

6. The system according to any one of the preceding claims, wherein at least one film sensor is mounted at a hard-to-be cleaned position such as high-temperature regions of heat exchangers, pre-denaturation stages, ring bowls or central bowls of a filling apparatus, filling valves, buffering tanks, wake spaces, pipe expansions, undercuts, interfaces between sealings and materials, and / or wherein at least one film sensor is mounted at a position having stronger film formation than other positions of the process plant, for instance a food processing plant.

7. The system according to any one of the preceding claims, wherein at least one film sensor can be heated.

8. The system according to any one of the preceding claims, wherein the process plant is a food processing plant.

9. A method for monitoring the hygienic status of a process plant and for monitoring and controlling a cleaning process of the process plant comprising: monitoring the hygienic status during production by monitoring the formation of films on at least a part of the process plant during production by means of at least one film sensor for measuring the film thickness the measuring region (105) of which comprises film thicknesses including a predetermined film thickness (108), initiating a cleaning process of the process plant when the at least one film sensor determines that the film thickness exceeds the predetermined film thickness (108), monitoring and / or stopping the initiated cleaning process by at least one further film sensor for measuring the film thickness the measuring region of which differs from the measuring region of the first film sensor.

10. The method according to the preceding claim, wherein the film sensor for measuring the film thickness the measurement region (105) of which comprises film thicknesses including a predetermined film thickness (108) comprises a measuring region including a predetermined maximum tolerable film thickness (108) and / or wherein the further film sensor has a measuring region near or equal to 0.

11. The method according to the preceding claim, wherein the monitoring the film formation on at least a part of the process plant during production is first carried out by the film sensor the lower measuring region of which comprises film thicknesses near or equal to 0, and wherein only after reaching the upper end of the measuring region of the film sensor having the lower measuring region of film thicknesses near or equal to 0 monitoring the hygienic status during production is switched to the film sensor the measuring region (105) of which comprises film thicknesses including a predetermined maximum tolerable film thickness.

12. The method according to any one of the preceding method claims, wherein the monitoring the initiated cleaning process is first carried out by the film sensor the lower measuring region of which comprises film thicknesses including a predetermined maximum tolerable film thickness, and wherein only after reaching the lower end of the measuring region of the film sensor having the measuring region (105) for film thicknesses including a predetermined maximum tolerable film thickness (108) the monitoring of the initiated cleaning process is switched to the film sensor the lower measuring region of which comprises film thicknesses near or equal to 0.

13. The method according to any one of the preceding method claims, wherein the monitoring of the initiated cleaning process further comprises monitoring a purging of a cleaning medium for instance with water, wherein monitoring the purging is carried out by means of a sensor configured to measure a physical property of the medium (308) flowing through the position to be cleaned, for instance being configured to measure the electric conductivity of a medium (308) flowing through the position to be cleaned.

14. The method according to any one of the preceding claims, wherein the process plant is a food processing plant.