Patent Description:
Our prior European Patent Application No. <CIT> describes a pasteurisation apparatus, in which there is a holding tube and control components that ensure that milk has a sufficient dwell time at a certain temperature. <CIT>) describes a method and apparatus for determining the time taken for a fluid to flow through a length of conduit. <CIT>) describes an apparatus for timing the passage of a liquid.

The present invention is directed towards providing an improved pasteurisation apparatus.

We describe a pasteurization apparatus comprising a line through a heater, a pump, a holding tube, a temperature sensor at or downstream of an outlet of the dwell tube, a controller, a first product sensor at or near an inlet of the holding tube, and a second product sensor at or near an outlet of the holding tube, wherein the controller is configured to perform a method comprising a dwell time test by:.

Preferably, at least one of the sensors is a conductivity sensor and the controller is configured to perform includes conductivity sensing. Preferably, the holding tube is at least partly in a spiral configuration. Preferably, the controller is configured to monitor temperature at the end of the holding tube at least, to verify the elevated temperature for the determined time.

Preferably, the sensors are conductivity sensors, and the controller is configured to recognize water by conductivity being in the range of <NUM> and <NUM>,<NUM>/m. Preferably, the controller is configured to perform the dwell time test only when the flow rate in the line exceeds a threshold.

Preferably, the controller is configured to automatically perform the dwell time test at the start of every batch and the end of every batch. Preferably, the controller is configured to integrate the dwell time test with detection of product line purging data.

In various examples, the sensors include sensors for one or more of turbidity, pH, fats, and protein sensing.

Preferably, the controller is configured to store a calibration time duration for opening or closing of a valve for diverting liquid coming from the dwell tube to a diversion route according to whether a required temperature and dwell time has been achieved, to monitor operation of said valve, and to raise an alert if the operating time is excessively long. Preferably, the controller is configured to perform a pasteurization unit PU Value calculation in real time by determining a product dwell time and combining the dwell time with an elevated temperature value. Preferably, the controller is configured to relate a quantity of product with the PU value according to pump (<NUM>) output.

Preferably, the apparatus comprises a diversion valve for diversion of liquid to a recovery tank, and the controller is configured to divert waste liquid to said tank via said valve.

Preferably, the controller is configured to determine that a liquid flowing in the apparatus is waste on the basis of conductivity sensing of the liquid, a category of waste being determined if a conductivity value is between that for water and that for the product.

Preferably, the controller is configured to determine a transition to waste liquid immediately before a product batch and immediately after a product batch.

Preferably, the controller is configured to store a pre-set volume value for a flow path in the apparatus between a conductivity sensor (CS2) at which it detects a transition to waste liquid and the diversion valve, and to predict according to said volume value and the pump flow rate how long it will take for the waste liquid to reach the diversion valve, and to actuate the diversion valve at an estimated time for he waste liquid to reach the diversion valve to cause diversion of the waste liquid to the recovery tank.

We also describe a method of operation of a pasteurization apparatus of any example described herein, the method comprising the controller performing the steps of:.

We also describe 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.

In some examples, the sensing includes conductivity sensing. In some examples, the holding tube is at least partly in a spiral configuration. In some examples, the method comprises monitoring temperature 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 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. In some examples, 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.

In some examples, the sensing is conductivity sensing, and the controller is configured to recognize water by conductivity being in the range of <NUM> and <NUM>,<NUM>/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 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.

We also describe 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 tube, and a controller, wherein the controller is configured to perform a dwell time test of a method of any example described herein.

The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only with reference to the accompanying drawings in which:
<FIG> is a flow diagram illustrating a pasteurization apparatus of the invention and its operation.

Referring to <FIG>, a pasteurization apparatus <NUM> of the invention comprises a constant level tank <NUM> which receives raw milk from a supplier. The stages of the apparatus <NUM> are as follows in order of flow through:.

In use, the apparatus <NUM> is operated by circulating water at the start of production. When this water reaches pasteurization temperature by heating in the heater <NUM> the water is sent to drain via the valves V3A and V3B. The pump <NUM> is then operated to pump milk into the apparatus <NUM>, purging the water from it until all of the water is purged from the pasteuriser and only milk remains. The pump <NUM> is a lobe-type pump that is used for the purging. There are two pumps <NUM>, 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 <NUM>.

The controller <NUM> is configured with the conductivity of the water being approximately <NUM> Siemens per meter (s/m) (this can vary between <NUM> and <NUM>,<NUM>/m depending on the water supply) and with the conductivity of milk, say <NUM>,<NUM>/m (this can also slightly vary). The controller <NUM> therefore can calculate the holding time of the milk in the holding tube <NUM> during the purging process at the start and finish of pasteurising.

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 <NUM>,<NUM>/h (litres per hour). Milk enters the pasteuriser via an automatic valve (it can enter the pasteurizer in other ways for 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 <NUM>,<NUM>/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 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 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.

The normal position for the diversion valves V1A and V1B is at the end of the holding tube <NUM>, however, in other cases they (or a single valve performing this function) may be positioned at the cold product outlet (downstream of the stage <NUM>).

After holding the product in the holding tube <NUM>, a temperature sensor TS detects if the product is at the correct pasteurisation temperature. If so, the diversion valves V1A/V1B activate, allowing product to enter the pasteurised product section <NUM> of the PHE for sending the product via the stage <NUM> to the coupler <NUM>.

The diversion valves V1A/V1B prevent raw product from entering the pasteurised section <NUM>. The default position for them is normally open so that all product is returned to the balance tank <NUM> or the product supply pipe if this valve is not operating correctly. Such incorrect operation may be due to lack of air, electricity, other mechanical issues or has not achieving the correct pasteurisation temperature as set on the pasteurising temperature sensor TS/<NUM>. This sensor includes a digital reference thermometer (DRT) <NUM>.

On commissioning or a subsequent setup of the apparatus <NUM>, two proximity switches are installed on the valves V1A/V1B to detect the correct open and closed positions for them. These proximity switches record when the valves turn to the open and closed positions and may be built in at valve manufacture. Then a test is carried out to check the time it takes for this valve to travel between its normally open and closed positions. This is indicated by the proximity switches opening and closing. This time is calculated by the PLC controller <NUM> or another time-detecting apparatus. Then this time is calibrated into the controller <NUM> to monitor the correct operational time for this valve. This valve is set to operate with a maximum time error setting of, in one example, <NUM>%. Therefore, if this valve operates outside the set time allowed an alarm is given to check this valve as it may be faulty.

On start-up, with the pasteuriser running on water, the water begins to heat up. When it reaches the pre-set pasteurisation temperature, after a time delay the diversion valve V1A/V1B will activate to send the "pasteurised" water into the pasteurised section of the pasteuriser. Before any product is allowed to enter the balance tank <NUM> to commence production, the heating supply to the pasteuriser is stopped and the pasteuriser begins to fall in temperature. When this temperature falls below the pre-set pasteurisation temperature, the valves V1A/V1B will deactivate, returning water to the balance tank. This valve activation and deactivation is recorded on the PLC <NUM> to ensure that this valve is operating correctly within the allocated operational time allowed and at the correct temperature.

The above valve time check may be also installed into other single or multiple valve manifolds to detect if a valve is operating correctly/incorrectly, outside the allocated time set for correct operation of this valve.

For some products, especially alcoholic beverages such as beer, an important parameter is "pasteurization unit" or "PU" value, which is a measure of the heat received by the product during pasteurization. The controller <NUM> is programmed to dynamically calculate a PU value by initially determining as described above the dwell time using the conductivity sensors CS1 and CS2 and combining the dwell time with the elevated temperature. This calculation provides the base PU value of the product with a value of one being at a temperature of at least <NUM>° for one minute, in one example. So, it is at this elevated temperature for <NUM> minutes the PU value is <NUM>. The value is related to quantity of product by the controller <NUM> using the flow rate according to pump <NUM> output to relate the PU value to kg of product.

In one example the outlet coupler <NUM> includes a diversion valve for diversion of liquid to a recovery tank. Immediately before and after product batches there is a time period during which the liquid is neither product nor water but is rather a waste liquid such as milky water. This waste liquid cannot be delivered to the drain and nor is it useful, and hence it must be treated. The system <NUM> accurately controls the amount to be treated by the controller <NUM> determining the transition to waste liquid using the conductivity sensors CS1 and CS2. Also, the controller <NUM> stores a pre-set volume for the line between the second sensor CS2 and the outlet coupler <NUM>, say <NUM> litres. When the controller <NUM> automatically senses a transition from water to product or vice versa it predicts according to the stored volume value and the pump flow rate how long it will take for the waste liquid to reach the output coupler <NUM>. At the estimated time (with a pre-set safety margin) the diversion valve at the outlet <NUM> is actuated to cause diversion of the waste liquid to the recovery tank for treatment before disposal. The treatment may for example include spray drying, or an ultra-filtration (UF) or a reverse osmosis (RO) plant to recover the protein.

In another example the controller performs this processing according to a third conductivity sensor at the outlet <NUM>, in which case the diversion is immediate without processing of estimate time to the outlet <NUM>.

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.

Claim 1:
A pasteurization apparatus (<NUM>) comprising a line through a heater (<NUM>), a pump (<NUM>), a holding tube (<NUM>), a temperature sensor (<NUM>) at or downstream of an outlet of the dwell tube, a controller (<NUM>), a first product sensor (CS1) at or near an inlet of the holding tube, and a second product sensor (CS2) at or near an outlet of the holding tube, wherein the controller (<NUM>) is configured to perform a method comprising a dwell time test by:
pumping a liquid product through the heater (<NUM>) and then through the holding tube (<NUM>) at an elevated temperature for a target dwell time period,
detecting a first time stamp upon passage of the product at the start of the holding tube by way of sensing of the product by the first sensor (CS1),
detecting a second time stamp upon passage of the product at the end of the holding tube by way of sensing of the product by the second sensor (CS2), and
calculating a dwell time according to time difference between the time stamps;
characterized in that, the controller (<NUM>) is configured to:
perform the dwell time test without interruption between initial purging of the line with water and the start of pasteurizing the product, the sensing being used by the controller to differentiate between water and the product, and
perform the dwell time test without interruption between completion of product pasteurizing and purging of the line with water at the end of pasteurizing the product, the sensing being used by the controller to differentiate between water and the product.