IE87298B1 - Pasteurisation apparatus improvements - Google Patents

Abstract

A method of pasteurising a milk product includes integrated line purging, dwell time testing, and final purging. It is carried out by an apparatus (1) with a heater (12), a pump (13), a temperature sensor (24), a holding tube (15), conductivity sensors (CD1, CS2) at the start and end of the holding tube (15). and a controller (20). The method includes performing a dwell time test by pumping the product through the heater and then through the holding tube at an elevated temperature for a target dwell time period. The controller detects a first time stamp upon passage of the product at the start of the holding tube by way of conductivity sensing by a sensor (CS1), detects a second time stamp upon passage of the product at the end of the holding tube by a sensor (CS2), and calculates a dwell time according to time difference between the time stamps.

Description

“Pasteurisation Apparatus Improvements” Introduction The present invention relates to pasteurisation apparatus’, especially to monitoring of dwell times for adequate treatment.

Our prior European Patent Application No. EP3740078A describes a pasteurisation apparatus, in which there is a holding tube and control components that ensure that milk has a sufficient dwell 10 time at a certain temperature.

The present invention is directed towards providing an improved apparatus.

Summary The invention provides a method of pasteurising a liquid product, the method being carried out by an apparatus comprising a line through a heater, a pump, a temperature sensor, a holding tube and a controller, the method comprising performing a dwell time test by pumping the product through the heater and then through the holding tube at an elevated temperature for a target dwell time period, the method including detecting a first time stamp upon passage of the product at the start of the holding tube by way of sensing by a sensor, detecting a second time stamp upon passage of the product at the end of the holding tube by a sensor, and calculating a dwell time according to time difference between the time stamps, wherein the sensing includes conductivity sensing, and wherein the dwell time test is carried out without interruption between initial purging of the line 25 with water and the start of pasteurizing the product, the sensors being used by the controller to differentiate between water and the product.

The invention also provides a pasteurization apparatus comprising a heater, a pump, a temperature sensor, a holding tube, a sensor at the start of the holding tube, a sensor at the end of the holding 30 tube, and a controller, wherein the controller is configured to perform a dwell time test of a method as described above.

In some examples, the holding tube is at least partly in a spiral configuration. -219/04/2022 In some examples, the method comprises monitoring temperate at the end of the holding tube at least to verify the elevated temperature for the determined time.

In some examples, the dwell time test is carried out without interruption between completion of 5 product pasteurizing and purging of the line with water at the end of pasteurizing the product, the sensors being used by the controller to differentiate between water and the product.

In some examples, the sensing is conductivity sensing and the controller is configured to recognize water by conductivity being in the range of 100 and 1,000 s/m.

In some examples, the controller carries out the dwell time test only when the flow rate in the line exceeds a threshold.

In some examples, the controller automatically carries out the dwell time test at the start of every 15 batch and the end of every batch.

In some examples, the controller integrates the dwell time test with detection of product line purging data.

In some examples, the sensing includes one or more of turbidity, pH, fats, and protein sensing.

Detailed Description of the Invention The invention will be more clearly understood from the following description of some 25 embodiments thereof, given by way of example only with reference to the accompanying drawings in which: Fig. lisa diagram illustrating a pasteurization apparatus of the invention.

Referring to Fig. 1, a pasteurization apparatus 1 of the invention comprises a constant level tank which receives raw milk from a supplier. The stages of the apparatus 1 are as follows in order of flow through: 11. Regenerator heat exchanger to pre-heat the raw milk by treated and pasteurized milk giving up some of its heat. 19/04/2022 12. A heater heat exchanger for elevating temperature of the raw milk to a desired target level for pasteurization, by transfer of heat from a heating medium received on a heat media supply HMS and return HMR. The heat transfer medium is in this case water.

. A holding tube, in this case configured with a spiral. The holding tube starts at the outlet of the pasteurizing section (hot water section 12) and finishes at the diversion valve VIA. The holding tube diameter is in the range of 10mm to 200mm and the length in the range of 0. Im to 500m in length, depending on the flow rate of the pasteuriser and the total holding time required for the product that is being pasteurized. This holding time length varies from pasteuriser to pasteuriser depending the type of product being pasteuriser. For dairy products the target dwell time is from 1 second to 5,000 seconds. For beer this is calculated on a PU Value (pasteurizer units), which is a calculation between the desired pasteurizing and the dwell time required for the type of beer being pasteurised.

The milk, or other product, is pumped through the heater 12 and the holding tube 15 by a pump 13 which is controlled by the controller 20 with use of pressure sensors PS and configured parameters to achieve a dwell time of at least 15 seconds at the elevated temperature.

CS1 and CS2. Conductivity sensors, one at each end of the holding tube 15. The sensors that are used for this test are IFM LDL 100™ and LDL 200™, but there are many different types of sensors that can also be used for this test. They are mounted to the tube by a sanitary Tri Clamp fixture. Both CS1 and CS2 are positioned in the holding tube 15 by a sanitary mounting fixture, both sensors protruding into the holding tube to detect the difference between the product and water as it passes both sensors. CS1 is mounted as near as possible to where the product enters the holding tube and CS2 is mounted as near as possible to where the product exits the holding tube, to accurately calculate the total time that the product is in the complete holding tube. They detect conductivity across the full diameter of the tube. CS1 and CS2 are positioned in the holding tube to protrude into the product to easily detect the difference between water and the product.

. Controller with a safety thermal limit recorder linked to the conductivity sensors CS1 and CS2, and also to a digital reference thermometer TS 24. 19/04/2022 22, 23. Flow diversion valves for onward routing of the heated milk according to results of integrity checking of the dwell test. The main flow from the first valve 22 (VIA) is to the second valve 23 (V1B), the rej ection alternative being to the raw product tank 10. The main flow from the second valve 23 is to the regenerator 11, the rejection alternative being to the tank 10. The valve 23 is a fail safe for the first valve 22. Providing for a scenario in which the first valve seal leaks.

. Heat exchanger cooler, to further cool pasteurized milk after it has already given up some of its heat in the regenerator 11. 50. Product outlet controller. This delivers the final product (pasteurized milk) to a coupler 70 from the apparatus 1. It includes a vacuum breaker 51 which is at a level of at least 30cm above the tank 10, a temperature sensor 52, a back-pressure valve 53, a final valve 54 for delivery of the final product, and a waste return valve 60 for routing of waste product back to the un-treated supply milk tank 10. The outlet 50 components 51-54 operate in conjunction with each other for monitoring pressure and the operation of the pasteuriser and provide over-pressure detection and control.

In use, the apparatus 1 is operated by circulating water at the start of production. When this water reaches pasteurization temperature by heating in the heater 12 the water is sent to drain via the valvesV3A and V3B. The pump 13 is then operated to pump milk into the apparatus 1, purging the water from it until all of the water is purged from the pasteuriser and only milk remains. The pump 13 is a lobe-type pump that is used for the purging. There are two pumps 13, and either or both may be used. A different type of pump, such as a centrifugal pump, may be used. During this purging process a holding time test is simultaneously carried out at the start and finish of pasteurizing. This is performed by monitoring readings from the conductivity meters CS1 and CS2, located before and after the holding tube 15.

The controller 20 is configured with the conductivity of the water being approximately 800 Siemens per meter (s/m) (this can vary between 100 and 1,000 s/m depending on the water supply) and with the conductivity of milk, say 4,500 s/m (this can also slightly vary). The controller 20 therefore can calculate the holding time of the milk in the holding tube 15 during the purging process at the start and finish of pasteurising. 19/04/2022 - 5 For the test to commence, the pasteurizer is started and run with water as described above. When it reaches the required pasteurization temperature and flow rate of 10,000 L/h (litres per hour). Milk enters the pasteuriser via an automatic valve (it can enter the pasteurizer in other ways for 5 example via pump gravity feed from a tank). During purging both of the conductivity sensors CS1 and CS2 and a flow meter are monitored. If a setting of say 4,000 s/m is set as the triggering signal for both the conductivity sensors, then this will detect the arrival of the milk at the start conductivity sensor CS1, starting the clock; and when the conductivity sensor CS2 at the end of the holding tube detects the milk it stops the clock, calculating the holding time test at the flow 10 rate monitored.

This test can also be run at the end of production when water is used to purge the milk from the pasteuriser. Instead of milk triggering the test, the water is used but the procedure is the same, only the triggering settings are different for the milk and the water.

The testing process involves the following controller operations: The flow rate is determined by way of flow meters FM1, 80, positioned between the balance tank 10 and the start of the regenerator 11. The flowmeter may alternatively be 20 positioned in many other positions suitable to the process requirement sin the line.

The conductivity sensor at the start of the holding tube 15 detects the changeover from water to milk (using a configured threshold of for example 2,500 s/m).

This triggers the clock to start the time calculation.

When the sensor CS2 at the end of the holding tube 15 also detects this changeover from water to milk the clock is stopped. This provides the time duration in addition to the flow rate data, for example 25 seconds at a flow rate of 20,000 L/h. This time and flow rate can 30 vary significantly depending on the size of the holding tube, 5 to 5000 seconds (this is determined by the length of the holding tube) and pasteuriser's flow rate, for example 100 to 100,000 L/h.

At the end of pasteurizing the opposite occurs, the changeover being from milk to water. -619/04/2022 The test will log data including the trigger time between both sensors CS1 and CS2 and the flowrate on the flow meter during this time.

Such an automatic holding time (or “dwell time”) test can be carried out as described daily at the start and finish of production. It is very advantageous that it is part of the integral procedures at the start and end of production. By monitoring the purging process with the two conductivity sensors it is possible to also recover the purging water that is normally sent to drain. It eliminates the need for specialist personnel such as outside contractors to carry out dwell time tests.

Components of embodiments can be employed in other embodiments in a manner as would be understood by a person of ordinary skill in the art. The invention is not limited to the embodiments described but may be varied in construction and detail. The product may be other than milk, for example beer, wine, or fruit juice.

In examples of the disclosure not included in the scope of the claims the test can also be carried out using sensors other than conductivity sensors at the start and finish of the holding tube. While this is not as effective as conductivity sensing as described above, the system would have the benefit of the in-line dwell time testing achieved before and after a product process. Such sensors 20 include turbidity sensors to detect a change of colour, pH sensors, fats sensors, protein sensors, for example. These liquid parameters are very different between water and products being pasteurized such as milk.

Claims (10)

Claims

1. A method of pasteurising a liquid product, the method being carried out by an apparatus (1) comprising a line through a heater (12), a pump (13), a temperature sensor (24), a holding tube (15) and a controller (20), the method comprising performing a dwell time test by pumping the product through the heater and then through the holding tube at an elevated temperature for a target dwell time period, the method including detecting a first time stamp upon passage of the product at the start of the holding tube by way of sensing by a sensor (CS1), detecting a second time stamp upon passage of the product at the end of the holding tube by a sensor (CS2), and calculating a dwell time according to time difference between the time stamps, wherein the sensing includes conductivity sensing, and wherein the dwell time test is carried out without interruption between initial purging of the line with water and the start of pasteurizing the product, the sensors being used by the controller to differentiate between water and the product.

2. A method as claimed in claim 1, wherein the holding tube is at least partly in a spiral configuration.

3. A method as claimed in claims 1 or 2, comprising monitoring temperate at the end of the holding tube at least, to verify the elevated temperature for the determined time.

4. A method as claimed in any preceding claim, wherein the dwell time test is carried out without interruption between completion of product pasteurizing and purging of the line with water at the end of pasteurizing the product, the sensors being used by the controller to differentiate between water and the product.

5. A method as claimed in claims 3 or 4, wherein the sensing is conductivity sensing and the controller is configured to recognize water by conductivity being in the range of 100 and 1,000 s/m.

6. A method as claimed in any of claims 1 to 5, wherein the controller carries out the dwell time test only when the flow rate in the line exceeds a threshold.

7. A method as claimed in any of claims 1 to 6, wherein the controller automatically carries out the dwell time test at the start of every batch and the end of every batch.

8. A method as claimed in claims 1 to 7, wherein the controller integrates the dwell time test 5 with detection of product line purging data.

9. A method of any preceding claim, wherein the sensing includes one or more of turbidity, pH, fats, and protein sensing.

10. 10. A pasteurization apparatus comprising a heater (12), a pump (13), a temperature sensor (24), a holding tube (15), a sensor at the start of the holding tube, a sensor at the end of the holding tube, and a controller (20), wherein the controller is configured to perform a dwell time test of a method of any preceding claim.