WO2018220358A1

WO2018220358A1 - System for cleaning processing equipment

Info

Publication number: WO2018220358A1
Application number: PCT/GB2018/051460
Authority: WO
Inventors: Ian STERRITT; Nicholas Watson; Elliot WOOLLEY
Original assignee: Martec Of Whitwell Limited; The University Of Nottingham; Loughborough University
Priority date: 2017-05-31
Filing date: 2018-05-30
Publication date: 2018-12-06
Also published as: GB201708672D0

Abstract

A system for cleaning the interior surfaces of tanks and piping of industrial processing equipment (5a), the system being in fluid communication with one or more inlets of the processing equipment and one or more outlets of the processing equipment. The system has cleaning fluid supply means (15) that supplies one or more cleaning fluids selected from rinsing fluid, chemical washing fluid, sanitising fluid and sterilizing fluid to the interior of the processing equipment, surface fouling detection means (20, 30) that directly detects fouling on one or more sections of the interior surfaces of the processing equipment in real-time, and control means (60) that controls the supply of said one or more cleaning fluids in response to signals from the surface fouling detection means. The system optimizes cleaning, for example by reducing the unnecessary use of water, energy and chemicals and/or reducing the loss of production time.

Description

SYSTEM FOR CLEANING PROCESSING EQUIPMENT

Field of the invention

The present invention relates to cleaning the interior surfaces of industrial processing equipment, for example the equipment used to manufacture food, beverages, chemicals, personal care products, cosmetics or pharmaceutical products. More specifically the present invention relates to a system and a method for cleaning the interior surfaces of industrial processing equipment that employs novel sensor and control technologies that measure fouling on such surfaces to optimize cleaning, for example by reducing the unnecessary use of water, energy and/or chemicals and/or reducing the loss of production time.

Background of the Invention

Many food, beverage and pharmaceutical products are manufactured at an industrial scale using a variety of processing equipment, including liquid processing equipment and dry powder equipment, which is interconnected by pipes and other conduits. The internal surfaces of such equipment and piping must be cleaned regularly and effectively to maintain necessary standards of hygiene and product quality. This can be especially challenging when the equipment is used to manufacture a variety of products.

For many years effective cleaning meant having to disassemble the equipment in order to have suitable access to the internal surfaces that needed to be cleaned. Such disassembly was time- consuming and required skilled staff to perform this. In the meantime the equipment was not available for manufacturing any products. Another problem was inaccurate reassembly could detrimentally affect safety and disrupt production. Furthermore, continually disassembling and reassembling increased wear to the equipment and thereby reduced its safe and effective working life.

In more recent times various methods have been developed for cleaning the interior surfaces of equipment and related piping without requiring any disassembly, such cleaning methods and associated cleaning equipment being generally known as "clean-in-place" (CIP) technology. Such technology provides automated, consistent and validated cleaning whilst maximising safe and productive use of the equipment.

An example of such a system is described in United States patent US 6767408. It discloses a method for cleaning apparatus using a clean-in-place system that involves supplying a cleaning and rinsing composition having measurable physical properties into the apparatus to be cleaned, sensing the measurable physical property versus time for fluids exiting the apparatus, determining suitable circulation time for the cleaning composition, determining a cleaner return valve closing time and subsequently supplying the rinsing composition.

While CIP has brought many benefits to manufacturing, there is a tendency to conduct the cleaning in a manner that assumes the worst case scenario in order to avoid the possibility of under cleaning, which for example could mean failing to meet regulatory and/or customer requirements. That, however, usually involves over-cleaning to minimise risk and therefore using unnecessarily high amounts of water, energy and chemicals. It can also mean disrupting production for longer than might otherwise have been needed to provide effective cleaning.

There is therefore a need to clean the interior surfaces of industrial processing equipment in a more efficient manner that provides effective cleaning, for example by minimising the use of water, energy and/or chemicals and/or reducing loss of production time.

The present inventors have a devised a system and a method for cleaning the interior surfaces of industrial processing equipment that employs novel sensor and control technologies that measure fouling on such surfaces to optimize the cleaning process. In certain preferred embodiments the system uses artificial intelligence software that further optimizes the cleaning process. It has been estimated that for a medium-sized diary this system can reduce annual water and energy consumption by 270,000 litres and 2,400 megawatt hours respectively.

Statement of the invention

In a first aspect, the present invention provides a system for cleaning the interior surfaces of tanks and piping of industrial processing equipment, the system being in fluid communication with one or more inlets of the processing equipment and one or more outlets of the processing equipment, the system comprising: a) cleaning fluid supply means that supplies one or more cleaning fluids selected from rinsing fluid, chemical washing fluid, sanitising fluid and sterilizing fluid to the interior of the processing equipment;

b) surface fouling detection means that directly detects fouling on one or more sections of the interior surfaces of the processing equipment in real-time; and

c) control means that controls the supply of said one or more cleaning fluids in response to signals from the surface fouling detection means.

In a second aspect, the present invention provides a method for cleaning the interior surfaces of tanks and piping of industrial processing equipment, said method comprising the steps of: a) supplying one or more cleaning fluids selected from rinsing fluid, chemical washing fluid, sanitising fluid and sterilizing fluid to the interior of the processing equipment;

b) directly detecting fouling on one or more sections of the interior surfaces of the

processing equipment in real-time using surface fouling detection means;

c) controlling the supply of said one or more cleaning fluids in response to signals from the surface fouling detection means.

Preferably the surface fouling detection means are arranged to detect fouling on said one or more sections a plurality of times during a cleaning operation.

Preferably the control means controls the supply of cleaning fluids in multiple cleaning stages selected from a pre-rinse stage, a chemical wash stage, an intermediate rinse stage, a sanitation stage, a sterilisation stage and a final rinse stage.

Preferably the control means includes artificial intelligence software that learns the interaction of process variable detected by the surface fouling detection means in order to optimise cleaning of the processing equipment. Preferably the surface fouling detection means comprises an optical fouling detector that optically detects fouling on one or more sections of the interior surfaces of the processing equipment in real-time

Preferably the optical fouling detector comprises a lamp that illuminates a section of the interior surface of the processing equipment with light; an optical sensor that captures images of the illuminated section; and an image processor that processes those images in real-time to estimate the degree of fouling on the section.

Preferably the lamp produces ultraviolet light, visible light or infrared light. Preferably the lamp is an ultraviolet lamp.

Preferably the optical fouling detector is located within or adjacent to a tank of the processing equipment and is formed to optically detect fouling on one or more sections of the interior surface of the tank.

Preferably the optical sensor of the optical fouling detector provides two-dimensional images that the image processor that processes to estimate the average thickness and/or the surface area of the fouling and/or the rate of removal of the fouling.

Preferably the optical fouling detector determines when the removal of fouling reaches a plateau and then sends a signal to the control means to cease the supply of one cleaning fluid and to initiate the supply of another cleaning fluid.

Preferably the optical fouling detector includes a vapour extractor that extracts vapour from within the processing equipment to optimize visibility of the relevant section of the interior surface and to optimize the quality of images captured by the optical fouling detector.

Preferably the vapour extractor is an extractor fan.

Preferably the optical fouling detector includes a fluid droplet remover that removes vapour from within the processing equipment to optimize visibility of the relevant section of the interior surface and to optimize the quality of images captured by the optical fouling detector.

Preferably the fluid droplet remover is an air-knife. Preferably the surface fouling detection means comprises an acoustic fouling detector that acoustically detects fouling on one or more sections of the interior surfaces of the processing equipment in real-time

Preferably the acoustic fouling detector comprises an ultrasonic transducer and a data processor, said ultrasonic transducer being brought into contact with an exterior wall of the processing equipment and used to emit an ultrasonic signal through said wall to a section of the interior surface of the processing equipment and to receive any signal that is returned due to the presence of fouling on said interior surface, and said data processor determining the degree of fouling by correlating the received signals during cleaning to previously recorded signals for known fouling levels and operating conditions.

Preferably the acoustic fouling detector determines predicts when the fouling will be removed from the interior surface and sends a signal to the control means to cease the supply of one cleaning fluid and to initiate the supply of another cleaning fluid.

Preferably the acoustic fouling detector determines when the removal of fouling reaches a plateau and then sends a signal to the control means to cease the supply of one cleaning fluid and to initiate the supply of another cleaning fluid .

Preferably the surface fouling detection means comprises one or more of the aforementioned optical fouling detectors and one or more of the aforementioned acoustic fouling detectors.

Terms

Terms used in the specification have the following meanings:

The term "directly detecting" as used herein means detecting by "viewing" (sensing) a surface using an optical method or in some other way. This contrasts with a proxy on non-localised method, such as a pressure difference method, which may not result in the fouled surfaces themselves being identified and cleaned.

The term "clean-in-place" or its acronym "CIP" as used herein means the method of cleaning the interior surfaces of pipes, vessels, process equipment, filters and associated fittings, without disassembly. The cleaning involves removing soil from product contact surfaces in the process position by circulating, spraying, or flowing chemical detergent solutions and water rinses onto and over the surfaces to be cleaned. CIP cleaning was once known as "mechanical cleaning".

The terms "industrial processing equipment" and "processing equipment" as used herein means any equipment that is useful in the manufacture food, beverages, personal care products, cosmetics or pharmaceutical products, particularly industrial scale manufacture. The processing equipment can include a wide variety of equipment such as tanks and piping.

The term "fouling" as used herein means including any remaining product, ingredients or other matter that could contaminate any further manufactured products. Fouling tends to accumulate on the interior surfaces of the processing equipment.

The term "cleaning fluid supply means" as used herein means any equipment that is suitable for supplying one or more cleaning fluids to the interior of the processing equipment in order to clean the interior of the processing equipment i.e. remove any fouling from the interior of the equipment, especially the interior surfaces of the processing equipment.

The term "surface fouling detection means" as used herein means any equipment that is suitable for detecting fouling on one or more sections of the interior surfaces of the processing equipment. Preferably the equipment detects such fouling in real-time. The surface fouling detection means can, for example, take the form of one or more optical fouling detectors and/or one or more acoustic fouling detectors.

The term "control means" as used herein means any equipment and any associated software that is suitable for controlling the supply of cleaning fluids in response to signals from the surface fouling detection means. For example, the control means can cease the supply of one cleaning fluid and initiate the supply of another cleaning fluid in a CIP cleaning cycle

The term "optical fouling detector" as used herein means any equipment that uses optical technology to detect fouling on one or more sections of the interior surfaces of processing equipment. Preferably the optical fouling detector detects such fouling in real-time.

The term "acoustic fouling detector" as used herein means any equipment that uses acoustic technology, for example ultrasonic technology, to detect fouling on one or more sections of the interior surfaces of processing equipment. Preferably the acoustic fouling detector detects such fouling in real-time. The term "rinsing fluid" as used herein means a liquid or a gas that is useful in rinsing fouling from the interior surfaces of processing equipment. Rinsing fluid could be used, for example, in a pre-rinse stage, intermediate rinsing stage and/or a final rinsing stage in a CIP cleaning cycle. Suitable rinsing fluid includes water, which can be in the form of steam.

The term "chemical washing fluid" as used herein means a liquid or a gas that is useful in chemically washing fouling from the interior surfaces of processing equipment. Suitable chemical washing fluid includes caustic solutions (e.g. 1-2% sodium hydroxide) and acidic solutions.

The term "sanitising fluid" as used herein means a liquid or a gas that is useful in sanitising or sterilizing the interior surfaces of processing equipment. Suitable sanitising fluid includes sanitising solutions such as acidic solutions, caustic solutions or water. When the sanitising solution is water it is typically used at an elevated temperature.

Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients used herein are to be understood as modified in all instances by the term "about".

Throughout this specification and in the claims that follow, unless the context requires otherwise, the word "comprise" or variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other stated integer or group of integers.

Description of the drawings

The present application includes Figures 1 to 5. In the drawings:

Figure 1 is a diagrammatic representation of a test rig that was constructed to carry out and test the system and method of the present invention. It is discussed in Example 1.

Figure 2 shows an image that was captured by an optical fouling detector as an RGB image but transformed to grayscale in order to visualise fouling on inner surfaces of the tank 5a of the test rig shown in Figure 1. Figure 3 shows a black and white image transformed from the grayscale image depicted in Figure 2 that is used to quantify the amount of fouling and its removal rate over time.

Figure 4 shows the results obtained when using the optical fouling detector of the system of present invention in the testing of the removal of white chocolate (see Example 1).

Figure 5 shows the results obtained when using the acoustic fouling detector of the system of present invention in the testing of the removal of white chocolate (see Example 1).

Detailed description of the invention

The present invention provides a system and a method for cleaning the interior surfaces of processing equipment that optimizes cleaning, for example by reducing the unnecessary use of water, energy and/or chemicals and/or reducing the loss of production time.

The system and method cleans the interior surfaces of processing equipment without requiring the processing equipment to be disassembled i.e. by using clean-in-place system that is in fluid communication with one or more inlets of the processing equipment and one or more outlets of the processing equipment.

The processing equipment can take any form that includes interior surfaces and is appropriate for the product or range of products that it has been designed to manufacture. The processing equipment may, for example, be used to manufacture food products (e.g. cheese, soups, fruit concentrates, jams and the like), beverage products (e.g. milk, smoothies, ready-to-drink tea, ready-to-drink coffee and the like), chemicals (e.g. paints, coating compositions and the like), personal care products (e.g. shampoos, sun tan lotions and the like), cosmetics (e.g. face creams and the like) or pharmaceutical products (e.g. pharmaceutically active formulations, biopharmaceutical drugs and the like). It is not uncommon in the food industry in particular that the same processing equipment is used to manufacture a variety of products over a week or even a day and all of the interior surfaces of the processing equipment need to be cleaned thoroughly between products and often between batches of products. Removing contaminants such as traces of nuts and other potentially allergic substances can be especially important for consumer safety and quality control. The need for effective cleaning of the interior surfaces of processing equipment is especially critical when it is used to manufacture pharmaceutical products that will contain pharmaceutically active ingredients and sometimes microbiological substances or when it is used to manufacture any aseptic products, i.e. those that need to be free from contamination caused by harmful bacteria, viruses or other microorganisms. For such aseptic products the cleaning method usually requires at least one sterilization stage. For certain products it will be necessary to remove or at least significantly minimize the presence of allergens (e.g. nuts) within the processing equipment.

In broad terms, CIP cleaning involves cleaning the interior surfaces of processing equipment in multiple cleaning stages or phases typically selected from one or more of a pre-rinse stage, a chemical wash stage, an intermediate rinse stage, a sanitation stage, a sterilisation stage and a final rinse stage. The selection of stages is based on the products that are manufactured and the assessed risks.

In the pre-rinse stage the interior of the processing equipment is flushed with a pre-rinsing solution to remove the majority of the readily soluble or otherwise removable soil from those surfaces. The pre-rinsing solution is preferably water and preferably supplied at a suitably elevated temperature. It is often recovered from one or more of the other cleaning stages to conserve resources.

In the chemical wash stage, the interior of the processing equipment is washed with at least one chemical washing solution containing one or more chemical substances that has been formulated to remove substantially all soil from the interior surfaces of the processing equipment that was not removed by the pre-rinse stage. The chemical washing solution may be a sodium hydroxide solution, e.g. containing 1 to 2% sodium hydroxide. The chemical wash stage is sometimes referred to as the detergent stage or the caustic stage.

In the intermediate rinse stage, the interior of the processing equipment is flushed with an intermediate rinsing solution to remove any chemical washing solution from the processing equipment. The intermediate rinsing solution is preferably water and preferably supplied at a suitable temperature, e.g. room temperature or a suitably elevated temperature.

In the sanitation stage, the interior of the processing equipment is flushed with one or more sanitising solutions to disinfect the interior surfaces of the processing equipment. The sanitising solution is typically an acid solution, a caustic solution or water, e.g. at an elevated temperature. The sanitisation stage may be carried out over an extended period of time, e.g. for several hours or overnight to provide effective sanitisation. Sanitation reduces the number of disease-causing organisms to non-threatening levels but may not kill or eliminate some spores and viruses.

In the final rinse stage, the interior of the processing equipment is flushed with a final rinsing solution to remove any of the sanitising solution that might remain in the processing equipment after the sanitation phase. The final rinsing solution is preferably water and preferably supplied at a suitable temperature, e.g. room temperature or a suitably elevated temperature.

For some products CIP cleaning includes at least one sterilization stage, which can be performed before or after any one or more of the aforementioned cleaning stages. Sterilization eliminates, removes, kills, or deactivates all forms of life and other biological agents such as fungi, bacteria, viruses, spore forms, prions and unicellular eukaryotic organisms present in a specified location, e.g. on a surface or a volume of fluid. Various sterilization methods are known in the art.

The system and method of the present invention applies artificial intelligence to clean-in-place technology to optimize cleaning and reduce the unnecessary use of water, energy and chemicals and the loss of production time. This is achieved by detecting fouling on certain sections of the interior surfaces of the processing equipment and controlling the cycle of the cleaning stages and the operating parameters thereof to optimize the cleaning process by ensuring effective cleaning whilst avoiding over-cleaning. In this way the system of the present invention can minimise the amount of water, energy, chemicals and/or the time needed to safely and efficiently clean the interior surfaces of the processing equipment. The system also offers a level of measured and proven due diligence that is not provided by conventional CIP systems.

In broad terms the present invention provides a system for cleaning the interior surfaces of tanks and piping of industrial processing equipment, the system being in fluid communication with one or more inlets of the processing equipment and one or more outlets of the processing equipment. The system comprises: (a) cleaning fluid supply means that supplies one or more cleaning fluids selected from rinsing fluid, chemical washing fluid and sanitising fluid to the interior of the processing equipment; (b) fouling detection means that detects fouling on one or more sections of the interior surfaces of the processing equipment in real-time; and (c) control means that controls the supply of said cleaning fluids in response to signals from the surface fouling detection means. The cleaning fluid supply means is any equipment that supplies one or more cleaning fluids to the interior of the processing equipment in order to clean the interior of the processing equipment i.e. remove any fouling including any remaining product, ingredients or other matter that could contaminate any further manufactured products. Fouling tends to accumulate on the interior surfaces of the processing equipment hence it is especially important that the cleaning fluids remove all fouling from the interior surfaces of the processing equipment or at least as much fouling as is possible. The processing equipment can include a wide variety of equipment such as tanks and piping.

Cleaning fluids can include rinsing fluid, chemical washing fluid and sanitising fluid. Preferably the rinsing fluid is water, the chemical washing fluid is a caustic solution or an acidic solution, and/or the sanitising fluid is a sanitising solution, a rinsing fluid at elevated temperature or steam. One skilled in the art of clean-in-place technology would recognise various rinsing fluids, chemical washing fluids and sanitising fluids are available and suitable for use in one or more of the CIP cleaning phases.

The system of the present invention comprises surface fouling detection means that detects fouling on one or more sections of the interior surfaces of the processing equipment in realtime. The surface fouling detection means can, for example, take the form of one or more optical fouling detectors and/or one or more acoustic fouling detectors. Preferably multiple surface fouling detection means are strategically placed at various points in the processing equipment to detect fouling where fouling is most likely to occur. The processing equipment can be designed and constructed to include the system of the present invention i.e. as part of a new installation of processing equipment. Alternatively, the system of the present invention can be retro-fitted to existing processing equipment.

Preferably the surface fouling detection means determines when the removal of fouling reaches a plateau and then sends a signal to the control means to cease the supply of one cleaning fluid and to initiate the supply of another cleaning fluid .

Optical fouling detectors and acoustic fouling detectors are described in more detail below.

The system of the present invention comprises control means that controls the supply of cleaning fluids in response to signals from the surface fouling detection means and optionally from other sensors provided within the processing equipment, for example sensors that measure the acidity of fluids at one or more locations within the processing equipment.

Preferably the control means controls the supply of rinsing fluid in a pre-rinse stage, the supply of chemical washing fluid in a chemical washing stage, the supply of further rinsing fluid in an intermediate rinsing phase, the supply of sanitising fluid in a sanitisation phase, and the supply of yet further rinsing fluid in a final rinsing stage. One skilled in the art of computer-controlled automation and artificial intelligence would know that various software and associated IT equipment can be used to control the operation of processing equipment. The control means preferably includes artificial intelligence software that learns the interaction of various process variables detected by the surface fouling detection means and optionally other detection equipment that is provided in order to optimize cleaning of the processing equipment. The artificial intelligence software can for example control the duration and/or the intensities of the various cleaning stages.

Preferred forms of surface fouling detection means of the system of the present invention include optical fouling detectors. Optical fouling detectors employ optical technology to detect fouling on one or more sections of the interior surfaces of processing equipment and/or in, adjacent or downstream from one or more of the outlets of the processing equipment.

Preferably the optical fouling detector detects such fouling in situ i.e. on the relevant interior surfaces of the processing equipment. Preferably the optical fouling detector detects such fouling in real-time.

Preferably the optical fouling detector comprises a lamp that illuminates a section of the interior surface of the processing equipment with light, an optical sensor that captures images of the illuminated section, and an image processor that processes those images in real-time to estimate the degree of fouling on the section and/or the rate of removal of fouling from this section. The lamp can produce ultraviolet light, visible light or infrared light. Preferably the lamp is a UV lamp that produces ultraviolet light. The UV lamp provides ultraviolet light that will typically cause fouling to fluoresce by virtue of the presence of fluorescing material, e.g. protein, in the fouling. This fluorescence is detected by the optical sensor. Preferably the optical sensor, which is for example a digital camera, captures the image as a RGB image, the wavelength of interest from the RGB image produced by the optical sensor is extracted to provide an image which is then processed to assess the presence and extent of fouling on the inner surface of the processing equipment. For example, when using a UV lamp fluorescing material such as protein fluoresces green so the green channel is suitably extracted from the RGB image.

Preferably the optical fouling detector is located within or adjacent to a tank or other vessel of the processing equipment and is formed to optically detect fouling on multiple sections of the interior surfaces of the tank. This can be achieved, for example, by locating the optical fouling detector in a moveable housing, by providing for the optical sensor within the tank to detect fouling on multiple sections of the interior surface of the tank, or by providing the optical sensor on an external surface of the tank but providing a window in the tank through which the optical sensor can detect fouling one or more sections of the interior surfaces of the tank.

Preferably the optical sensor of the optical fouling detector provides two-dimensional images and the image processor processes those images using suitable software that estimates the average thickness of the fouling and/or the rate of removal of fouling. Preferably the software measures the rate of removal of fouling and predicts the time by which all or at least substantially all of the fouling will be removed from the relevant surface. Certain software is commercially available for such purpose, although the skilled person may choose to develop bespoke software form that purpose.

The use of optical systems to assess the extent of fouling in clean-in-place processes, including suitable imaging and imaging processing equipment and software, is described in more detail by A. Simeone, N. Watson, I. Sterritt, and E. Woolley, "A multi-sensor approach for fouling level assessment in clean-in-place processes", Procedia CIRP 55 (2016), pages 134-139.

Preferably the optical fouling detector includes a vapour extractor that extracts vapour from within the processing equipment to optimize visibility of the relevant section of the interior surface and to optimize the quality of images captured by the optical fouling detector. Such a vapuor extractor can take a variety of forms but is suitably formed and suitably located to maximise the visibility of the relevant section of interior surface of the tank or other piece of processing equipment to the optical sensor, e.g. the lens of a digital camera, of the optical fouling detector. Preferably the vapour extractor is an extractor fan. Preferably the optical fouling detector includes a fluid droplet remover that removes vapour from within the processing equipment to optimize visibility of the relevant section of the interior surface and to optimize the quality of images captured by the optical fouling detector. Such a fluid droplet remover can take a variety of forms but is suitably formed and suitably located to maximise the visibility of the relevant section of interior surface of the tank or other piece of processing equipment to the optical sensor, e.g. the lens of the digital camera, of the optical fouling detector. Preferably the fluid droplet remover is an air-knife.

Preferred forms of surface fouling detection means of the system of the present invention include acoustic fouling detectors. Acoustic fouling detectors use acoustic technology, for example ultrasonic technology, to detect fouling on one or more sections of the interior surfaces of processing equipment. Preferably the acoustic fouling detector detects such fouling in realtime.

Preferably the acoustic fouling detector comprises an ultrasonic transducer and a data processor. In certain embodiments the ultrasonic transducer is located in contact with an exterior wall of the processing equipment and used to emit an ultrasonic signal through that wall to a desired section of the interior surface of the processing equipment and to receive any signal that is returned due to the presence of fouling on that interior surface where fouling may be present. In certain embodiments the ultrasonic transducer is integrated into an exterior wall of the processing equipment. At this interior surface the signal is reflected and received by the same transducer. The characteristics of the reflected signal will be affected by the degree of fouling on the interior surface. The ultrasonic transducer emits an ultrasonic frequency signal at a specific frequency, for example from 1 to 10 MHz. The data processor determines the degree of fouling by correlating the received signals during cleaning to previously recorded signals for known fouling levels and operating conditions, e.g. temperature.

In some embodiments the acoustic fouling detector determines when the removal of fouling reaches a plateau and then sends a signal to the control means to indicate that the current phase of CIP cleaning is complete.

In other embodiments the artificial intelligence software of the control means works in combination within the optical fouling detector(s) to predict the time by which all or at least substantially all of the fouling will be removed from the relevant interior surfaces of the processing equipment and control the initiation of the next cleaning stage to optimize cleaning.

The use of acoustic systems to assess the extent of fouling in clean-in-place processes, including suitable ultrasonic equipment and software, is described in more detail by A. Simeone, N. Watson, I. Sterritt, and E. Woolley, "A multi-sensor approach for fouling level assessment in clean-in-place processes", Procedia CI P 55 (2016), pages 134-139.

In certain preferred forms of the system of the present invention the surface fouling detection means comprises one or more of the aforementioned optical fouling detectors and one or more the aforementioned acoustic fouling detectors. Such optical fouling detectors and acoustic fouling detectors are preferably strategically placed at various points in the processing equipment to detect fouling where fouling is most likely to occur. In certain preferred embodiments an optical fouling detector is located in one or more tanks or vessels that form part of the processing equipment and an acoustic fouling detector is located on one or more pipes, pumps or sections with smaller internal volumes that form part of the processing equipment. Alternatively in certain other embodiments an acoustic fouling detector is located in one or more tanks that form part of the processing equipment and an optical fouling detector is located on one or more pipes that form part of the processing equipment.

The present invention also provides a method for cleaning the interior surfaces of tanks and piping of industrial processing equipment. In broad terms the method comprises the steps of: (a) supplying one or more cleaning fluids selected from rinsing fluid, chemical washing fluid and sanitising fluid to the interior of the processing equipment; (b) detecting fouling on one or more sections of the interior surfaces of the processing equipment in real-time using surface fouling detection means; and (c) controlling the supply of said one or more cleaning fluids in response to signals from the surface fouling detection means. The cleaning fluids, rinsing fluid, chemical washing fluid, sanitising fluid, surface fouling detection means are described previously.

Various modifications and variations of the described methods and uses of the present invention will be apparent to those skilled in the art. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments.

The present invention will now be further described by way of examples. EXAMPLES

Example 1

A test rig was constructed that includes a system of the present invention processing equipment. The test rig is depicted in Figure 1.

The test rig 1 comprised two 90 litre insulated stainless steel dished tanks 5a (the process tank) and 5b (the CIP tank) having lids 10a and 10b respectively. Lid 5a of tank 5a had been modified to allow the installation of cleaning fluid supply means in the form of a spray ball 15 and an optical fouling detector comprising a digital camera 20 and a set of ultraviolet lights 25. The test rig included a bespoke mounting bracket for attaching an optical fouling detector in the form of an ultrasonic transducer 30 that is mountable within a removable pipe section 35. Water can enter the test rig 1 through inlets 40a and 40b and be pumped through the test rig by the action of pumps 45a and 45b as needed. A vapour extractor in the form of an extractor fan 50 was mounted in the lid 10a adjacent the digital camera 20 to optimize visibility of the relevant section of the interior surface of the tank 5a and thus the quality of images captured by the digital camera 20. A fluid droplet remover in the form of an air knife 55 but was provided to optimize visibility of the relevant section of the interior surface of the tank 5a and thus the quality of images captured by the digital camera 20. The test rig has various valves 60 to control the passage of fluids around the test rig.

Fouling application

In order to carry out the experimental campaign it was necessary to produce artificial layers of fouling. Two different fouling agents were individually utilised for these experiments:

• White chocolate. 150 g melted and manually applied to the base of the tank 5a.

• Peanut butter. 150 g manually applied to the base of the tank 5a.

For the present experimental procedure, a manual application method was used. The lid 10a of the tank 5a was temporary removed and the fouling agents were placed inside of the tank 5a (the process tank) and manually applied on the bottom and side surfaces of that tank, in order to simulate actual conditions of a tank after a batch of industrial production. For ultrasonic measurements to be performed the removable pipe section 35 was removed from the piping that enters the tank 5a, the transducer 30 was mounted within the removable pipe section 35, and the removable pipe section 35 was replaced in the piping.

Washing

In this experimental campaign, washing cycles were carried out using a dynamic spray ball 15 with a 180° downward coverage. The spray ball 15 was positioned in the tank lid 10a and straightened so the fluid flow coming out covered the tank uniformly.

90 litres of warm water (nominally at 60 °C) was introduced into the test rig 1 via the water inlet 40b, pumped into the tank 5a though the operation of pump 45b and recirculated through the tank 5a via the removable pipe section 35 and the spray ball 15 to simulate an industrial cleaning process. The length of the investigation depended upon the rate of removal of fouling.

Image acquisition by the optical fouling detector

For the acquisition of images, a NIKON™ D3100 digital camera 20 and a set of 18 W 370 nm fluorescent UV lights 25 were installed in the lid 10a of the tank 5a (see Fig. 1)

In order to maximise the tank surface included in a single image, a wide angle SIGMA™ 10-20 mm zoom lens was used on the digital camera. The UV light set was the only source of light in the tank so it was not necessary to apply a UV filter on the lens. The campaign of experimental tests was carried out using a time-lapse technique.

Image processing

The RGB image appears as a 2000 x 2992 x 3 elements matrix, where the first two dimensions (2000 x 2992) represent the image resolution, and the third dimension (3) is represented by the three colours channels red, green and blue respectively. Due to the reaction (fluorescence of protein) to the UV light, in the RGB image, the fouling appears as a series of cyan-like coloured stains, while the tank surface is blue-purple. In order to isolate the fouling image, it was necessary to isolate the green channel (G) of the image.

After this transformation, the green channel image corresponds to a 2000 x 2992 matrix whose elements values range from 0 (black) to 255 (white) and it appears as a grayscale image (see Figure 2). The RGB to grayscale transformation allows the visualisation of the fouling on the tank surface.

In order to be able to quantify the amount of fouling and its removal rate over time, it is necessary to transform the grayscale image into a black and white (BW) image.

This transformation requires the computation of the global threshold which was computed according to the Otsu's method which chooses the threshold to minimise the infraclass variance of the black and white pixels.

The output binary BW image replaces all pixels in the input image with luminance greater than the threshold with the value 1 (white) and replaces all other pixels with the value 0 (black). An example of a BW image is shown in Figure 3.

After this transformation, the fouling is represented by the white pixels while the background is black.

The total amount of detectable surface fouling can be then computed by summing all the black pixels within each image. On the other hand, black pixels show that the fouling is below the detection level.

Figure 4 illustrates the results of one of the tests for cleaning white chocolate. In the first 20 seconds of the washing cycle the apparent surface fouling value rapidly increased due to the water flow which removed part of the fouling allowing it to float on the water surface. As the washing cycle continued, the fouling amount decreased until it reached zero per cent shortly before 500 seconds. In this case, the tank results clean to the sensitivity of the system. Ultrasonic signal acquisition by the acoustic fouling detector

A SONATEST™ 5 MHz immersion transducer (Sonatest Ltd, UK) was used for all measurements. This was connected to a LECOEUR™ US scan ultrasonic transmitting and receiving device (Lecoeur Electronique, France) which in turn was connected to a PC for equipment control and data collection. The LECOEUR™ ultrasonic device was used to send an excitation pulse to the transducer and record the subsequent reflected signal. The signal acquisition rate was approximately 10 Hz.

Ultrasonic data processing

To determine the level of fouling and fouling removal rate initially a received waveform was recorded for a clean pipe. This will be referred to as the clean baseline waveform. During the experiments as the pipe was cleaned ultrasonic waveforms in a region of interest (ROI) were recorded. The root mean square error (RMSE) between the clean baseline waveform and the recorded waveforms was recorded and plotted as a function of experimental time. Figure 5 illustrates an example of these results when testing of the removal of white chocolate. It clearly shows monitoring of the cleaning processes occurring within the first 40 seconds of the experiments.

Claims

1. A system for cleaning the interior surfaces of tanks and piping of industrial processing equipment, the system being in fluid communication with one or more inlets of the processing equipment and one or more outlets of the processing equipment, the system comprising: a) cleaning fluid supply means that supplies one or more cleaning fluids selected from

rinsing fluid, chemical washing fluid, sanitising fluid and sterilizing fluid to the interior of the processing equipment;

2. The system according to claim 1, wherein the surface fouling detection means are arranged to detect fouling on said one or more sections a plurality of times during a cleaning operation.

3. The system according to claim 1 or claim 2, wherein the control means controls the supply of cleaning fluids in multiple cleaning stages selected from a pre-rinse stage, a chemical wash stage, an intermediate rinse stage, a sanitation stage, a sterilisation stage and a final rinse stage.

4. The system according to any of preceding claim, wherein the control means includes artificial intelligence software that learns the interaction of process variables detected by the surface fouling detection means in order to optimise cleaning of the processing equipment.

5. The system according to any preceding claim, wherein the surface fouling detection means comprises an optical fouling detector that optically detects fouling on one or more sections of the interior surfaces of the processing equipment in real-time

6. The system according to claim 5, wherein the optical fouling detector comprises a lamp that illuminates a section of the interior surface of the processing equipment with light, an optical sensor that captures images of the illuminated section, and an image processor that processes those images in real-time to estimate the degree of fouling on the section.

7. The system according to claim 6, wherein the lamp is a lamp that produces ultraviolet, visible or infrared light.

8. The system according to claim 7, wherein the lamp is an ultraviolet lamp.

9. The system according to any one of claims 5 to 8, wherein the optical fouling detector is located within or adjacent to a tank of the processing equipment and is formed to optically detect fouling on one or more sections of the interior surface of the tank.

10. The system according to any one of claims 5 to 9, wherein the optical sensor of the optical fouling detector provides two-dimensional images that the image processor processes to estimate the average thickness and/or the surface area of the fouling and/or the rate of removal of the fouling.

11. The system according to any one of claims 5 or 10, wherein the optical fouling detector determines when the removal of fouling reaches a plateau and then sends a signal to the control means to cease the supply of one cleaning fluid and to initiate the supply of another cleaning fluid.

12. The system according to any one of claims 5 to 11, wherein the optical fouling detector includes a vapour extractor that extracts vapour from within the processing equipment to optimize visibility of the relevant section of the interior surface and to optimize the quality of images captured by the optical fouling detector.

13. The system according to claim 12, wherein the vapour extractor is an extractor fan.

14. The system according to any one of claims 5 to 13, wherein the optical fouling detector includes a fluid droplet remover that removes vapour from within the processing equipment to optimize visibility of the relevant section of the interior surface and to optimize the quality of images captured by the optical fouling detector.

15. The system according to claim 14, wherein the fluid droplet remover is an air knife.

16. The system according to any preceding claim, wherein the surface fouling detection means comprises an acoustic fouling detector that acoustically detects fouling on one or more sections of the interior surfaces of the processing equipment in real-time

17. The system according to claim 16, wherein the acoustic fouling detector comprises an ultrasonic transducer and a data processor, said ultrasonic transducer being brought into contact with an exterior wall of the processing equipment and used to emit an ultrasonic signal through said wall to a section of the interior surface of the processing equipment and to receive any signal that is returned due to the presence of fouling on said interior surface, and said data processor determining the degree of fouling by correlating the received signals during cleaning to previously recorded signals for known fouling levels and operating conditions.

18. The system according to claim 16 or 17, wherein the acoustic fouling detector predicts when the fouling will be removed from the interior surface and sends a signal to the control means to cease the supply of one cleaning fluid and to initiate the supply of another cleaning fluid.

19. The system according to claim 16 or 17, wherein the acoustic fouling detector determines when the removal of fouling reaches a plateau and then sends a signal to the control means to cease the supply of one cleaning fluid and to initiate the supply of another cleaning fluid ,

20. The system according to any one of claims 1 to 4, wherein the surface fouling detection means comprises one or more optical fouling detectors of any one of claims 5 to 15 and one or more acoustic fouling detectors of any one of claims 16 to 19.

21. A method for cleaning the interior surfaces of tanks and piping of industrial processing equipment, said method comprising the steps of: a) supplying one or more cleaning fluids selected from rinsing fluid, chemical washing fluid, sanitising fluid and sterilizing fluid to the interior of the processing equipment;

processing equipment in real-time using surface fouling detection means;