WO2016151381A1

WO2016151381A1 - Apparatus and method for flushing aseptic chambers of a high-pressure homogenizer or pump

Info

Publication number: WO2016151381A1
Application number: PCT/IB2015/059176
Authority: WO
Inventors: Fabio Gioberti; Stefano ANTONINI; Michele Madureri; Fabio Gandolfi
Original assignee: GEA Mechanical Equipment Italia SpA
Current assignee: GEA Mechanical Equipment Italia SpA
Priority date: 2015-03-24
Filing date: 2015-11-27
Publication date: 2016-09-29
Anticipated expiration: 2017-09-24

Abstract

A flushing apparatus (1) for flushing aseptic chambers (100) of a highpressure homogenizer or pump, comprising: a steam injector (2), in which non-sterile water and aqueous vapour are mixed; a double-wall heat exchanger (15) having a sterile side (15b) that receives water leaving the injector (2) and supplies sterile water to the aseptic chambers (100); a first temperature transducer (3) that detects the temperature of the superheated water leaving the injector (2); a first controller (4) which, based on the temperature detected by the first transducer (3), controls a first regulating valve (5) regulating the flow rate of aqueous vapour entering the injector (2); a second temperature transducer (17) that detects the temperature of the sterile water leaving the heat exchanger (15); a second controller (18) which, in response to the temperature detected by the second transducer (17), controls a second regulating valve (19) regulating the flow rate of water to a non-sterile side (15a) of the exchanger (15).

Description

DESCRIPTION

APPARATUS AND METHOD FOR FLUSHING ASEPTIC CHAMBERS OF A HIGH-PRESSURE HOMOGENIZER OR PUMP Technical field

The object of the present invention relates to an apparatus and method for flushing aseptic chambers of a high-pressure homogenizer or pump. The proposed apparatus and method find use in the food industry (particularly in the dairy sector) and in the chemical or pharmaceutical sector.

Background art

Condensed steam is known to have been used by several manufacturers for flushing the aseptic chambers of high-pressure homogenizers or pumps.

The Applicant has instead developed a system for flushing aseptic chambers with sterilized water and that comprises the use of two separate heat exchangers: a double-wall heat exchanger and a shell and tube heat exchanger.

In this solution, which is disclosed in Italian patent no. 1410858 filed by the Applicant, the non-sterile water at ambient temperature (15°-20°C) first enters the double-wall exchanger (non-sterile side) and then the shell and tube exchanger, where it is heated to about 130°-150°C owing to the effect of the steam. The water thus superheated re-enters the double-wall exchanger (sterile side) and surrendering heat to the incoming non-sterile water, it is cooled to about 40°-60°C.

Though less wasteful in terms of energy compared to the use of condensed steam, the solution described above is not free of drawbacks, mainly related to the costs and complexity of managing two heat exchangers - one being of the double-wall type and the other of the shell and tube type.

Disclosure of the invention

In this context, the technical task underlying the present invention is to offer an apparatus and a method for flushing aseptic chambers of a high- pressure homogenizer or pump that are able to overcome the drawbacks of the prior-art solutions cited hereinabove.

In particular, an aim of the present invention is to offer a flushing apparatus for flushing aseptic chambers of a high-pressure homogenizer or pump which is structurally less complex compared to the solutions of the prior art.

A further aim of the present invention is to make available an apparatus and a method for flushing aseptic chambers of a high-pressure homogenizer or pump which make it possible to further reduce wasted energy, with respect to solutions of the prior art.

In the field of UHT sterilization systems (i.e., "Ultra High Temperature" sterilization systems), the technique of sterilizing milk by direct exchange of heat between the milk and the aqueous vapour is also known in the prior art and it can take place by direct injection or direct infusion.

In a direct injection system, the milk is pre-heated to a temperature of about 80°C through heat recovery from the cooling milk and is then pumped into the injector at a pressure of about 5 bars. Inside the injector, the milk is mixed with saturated steam at about 150°C. Owing to direct contact with the steam, the milk reaches a temperature of about 142°C in a few seconds, as the steam condenses given that it supplies the latent heat of condensation.

Direct injection UHT systems process very high milk flow rates (thousands of litres/h).

The defined technical task and the specified aims are substantially achieved by a flushing apparatus for flushing aseptic chambers of a high- pressure homogenizer or pump, comprising:

- a steam injector having a first inlet for the aqueous vapour, a second inlet for non-sterile water and an outlet for the superheated water obtained by mixing the aqueous vapour with the non-sterile water; - a heat exchanger of the double-wall type having a non-sterile side receiving non-sterile water, and a sterile side receiving water from the outlet of the injector and supplying sterile water to the aseptic chambers;

- first means for detecting and regulating the temperature of the superheated water leaving the injector for the purpose of maintaining a water temperature of at least 135°C;

- second means for detecting and regulating the temperature of the sterile water leaving the heat exchanger for the purpose of maintaining a water temperature within the range of 30°-80°C;

- a positive displacement vane pump that distributes water to the non- sterile side of the heat exchanger and to the second inlet of the injector;

- a first regulating valve that regulates the flow rate of aqueous vapour to the first inlet of the injector based on the temperature detected by the first temperature detecting and regulating means when the apparatus is in a flushing configuration;

- a second regulating valve that regulates the flow rate of non-sterile water to the non-sterile side of the heat exchanger based on the temperature detected by the second temperature detecting and regulating means.

Preferably, the first flow-rate regulating valve supplies a maximum steam flow rate of about 1 1 kg/h to the first inlet of the injector.

In the embodiment described and illustrated herein, the first means for detecting and regulating the temperature comprises:

- a first temperature transducer that detects the temperature of the superheated water leaving the injector;

- a first controller which, in response to the temperature detected by the first temperature transducer when the apparatus is in the flushing configuration, controls the first flow-rate regulating valve.

The first controller is preferably a Proportional-lntegrative-Derivative (PID) or a programmable logic controller (PLC).

The second flow-rate regulating valve is preferably an inclined-axis modulating valve.

The second means for detecting and regulating the temperature preferably comprises:

- a second temperature transducer that detects the temperature of the sterile water leaving the heat exchanger;

- a second controller which, in response to the temperature detected by the second temperature transducer, controls the second flow-rate regulating valve.

The second controller is preferably a Proportional-lntegrative-Derivative (PID) or a programmable logic controller (PLC).

A holding tube for the sterile water is preferably provided, interposed between the outlet of the injector and the sterile side of the heat exchanger.

The defined technical task and the specified aims are substantially achieved by a method for flushing aseptic chambers of a high-pressure homogenizer or pump and that employs the flushing apparatus described hereinabove. This method comprises the steps of:

mixing aqueous vapour and non-sterile water inside the steam injector so as to obtain superheated water of a temperature of at least 135°C; - cooling the superheated water thus obtained to 30°-80°C, surrendering heat to non-sterile water inside the double-wall heat exchanger;

sending to the injector the pre-heated non-sterile water coming from the heat exchanger.

Brief description of drawings

Further characteristics and advantages of the present invention will become more apparent from the approximate and thus non-limiting description of a preferred, but not exclusive, embodiment of an apparatus and method for flushing aseptic chambers of a high-pressure homogenizer or pump, as illustrated in the accompanying drawings, of which:

- Figure 1 illustrates the simplified layout of a flushing apparatus for flushing aseptic chambers of a high-pressure homogenizer or pump, according to the present invention;

Figure 2 illustrates a more detailed layout of the flushing apparatus appearing in Figure 1 .

Detailed description of preferred embodiments of the invention

With reference to the figures, a flushing apparatus for flushing aseptic chambers 100 of a high-pressure homogenizer or pump is indicated by the number 1 .

The flushing apparatus 1 comprises a steam injector 2 having a first inlet 2a for the aqueous vapour, a second inlet 2b for non-sterile water and an outlet 2c for the superheated water obtained by mixing the aqueous vapour with the non-sterile water.

The temperature of the superheated water leaving the injector 2 is set and monitored by first detecting and regulating means 3, 4.

In particular, the superheated water leaving the injector 2 is maintained at a temperature of at least 135°C.

The first temperature detecting and regulating means 3, 4 preferably comprises a first temperature transducer 3 and a first controller 4.

In particular, the first temperature transducer 3 detects the temperature of the superheated water leaving the injector 2.

In response to the temperature thus detected, the first controller 4 controls a first regulating valve 5 that regulates the flow rate of aqueous vapour to the first inlet 2a of the injector 2 when the apparatus 1 is in a flushing configuration.

In the embodiment described and illustrated here, the first controller 4 is a Proportional-lntegrative-Derivative (PID) controller. As this is a known type of controller, it is not described in further detail.

In a second embodiment (unillustrated), the first controller 4 is a programmable logic controller (PLC).

In particular, the first flow-rate regulating valve 5 supplies a maximum steam flow rate of about 1 1 kg/h to the first inlet 2a of the injector.

The first flow-rate regulating valve 5 is preferably a modulating valve. The technical features of the injector 2 are chosen as a function of the saturated aqueous vapour flow rate (in kg/h) needed to heat the water, in relation to the steam pressure (in bars).

The first flow-rate regulating valve 5 is located on a steam inlet line L1 , which preferably comprises other components.

For example, the following are recognizable in the detailed layout appearing in Figure 2:

- a first manual shut-off valve 6;

- a "Y" strainer, indicated by number 7;

- a first analog pressure indicator 8;

- a first pressure reducing valve 9;

- a second analog pressure indicator 10;

- a first disc check valve 1 1 ;

- a third analog pressure indicator 12.

Preferably, all the components found along the steam inlet line L1 are made of stainless steel.

Preferably, a first drain line L1 1 for the condensate branches off from the steam inlet line L1 and comprises a second manual shut-off valve 13 and a first float steam trap 14.

The apparatus 1 comprises a heat exchanger 15 of the double-wall type. For example, the heat exchanger 15 has one or more modules in parallel, each of which comprises two plates separated by an interspace of air. The advantage to using this exchanger is that of ensuring intrinsic safety with respect to cross contamination.

The heat exchanger 15 has a non-sterile side 15a that receives non-sterile water, and a sterile side 15b that supplies sterile water to the aseptic chambers 100.

The non-sterile side 15a of the exchanger 15 receives water from a positive displacement vane pump 16.

The sterile side 15b of the exchanger 15 receives water from the outlet 2c of the injector 2 and supplies it to the aseptic chambers 100. The temperature of the sterile water leaving the heat exchanger 15 is set and monitored by means of second detecting and regulating means 17, 18.

In particular, the sterile water leaving the heat exchanger 15 is maintained preferably at a temperature of 60°C. For example, the temperature of the sterile water leaving the exchanger 15 is within the range of a minimum value of 30°C to a maximum value of 80°C. Alarms are generated when the temperature exceeds this range of permissible values.

The second temperature detecting and regulating means 17, 18 preferably comprises a second temperature transducer 17 and a second controller 18.

In particular, the second temperature transducer 17 detects the temperature of the sterile water leaving the heat exchanger 15.

In response to the temperature thus detected, the second controller 18 controls a second regulating valve 19 that regulates the flow rate of non- sterile water to the non-sterile side 15a of the exchanger 15. In the embodiment described and illustrated here, the second controller 17 is a Proportional-lntegrative-Derivative (PID) controller. As this is a known type of controller, it is not described in further detail.

In a second embodiment (unillustrated), the second controller 17 is a programmable logic controller (PLC).

The second flow-rate regulating valve 19 is preferably an inclined-axis modulating valve.

The positive displacement pump 16 is located on a water inlet line L2, which preferably comprises other components.

As can be seen in the figures, the vane pump 16 distributes the non-sterile water in two branches of the water inlet line L2: a first branch L21 connecting to the non-sterile side 15a of the heat exchanger 15 and a second branch L22 connecting to the second inlet 2b of the injector 2. For example, in the detail layout shown in Figure 2, on the water inlet line

L2, upstream of the positive displacement pump 16, there are: - a second manual shut-off valve 20;

- a first inclined-axis pneumatic on/off valve 21 ;

- a fourth analog pressure indicator 22;

- a second pressure reducing valve 23;

- a fifth analog pressure indicator 24.

The pump 16 is controlled by a dedicated feedback loop comprising a third controller 25, such as a PID or PLC type for example, and a flowmeter 26. On the second branch L22 of the water inlet line L2, downstream of the second flow-rate regulating valve 19 and upstream of the second inlet 2b of the injector 2, there are:

- a sixth analog pressure indicator 27;

- an analog temperature indicator 28;

- a second disc check valve 29.

There is second inclined-axis pneumatic on/off valve 30 on the first branch L21 of the water inlet line L2.

The superheated water leaving the injector 2 preferably passes into a holding tube 31 before reaching the sterile side 15b of the heat exchanger 15.

In the embodiment described and illustrated here, a third temperature transducer 32 is present between the holding tube 31 and the heat exchanger 15 and it serves the purpose of monitoring the temperature so that it does not drop below a pre-established minimum value ensuring sterile conditions. For example, this pre-established minimum value is equal to 135°C approximately.

Exiting from the sterile side 15b of the heat exchanger 15, a flushing line

L3 begins and leads to the aseptic chambers 100.

Preferably, a pressure transducer 33 is located on the flushing line L3 upstream of the second temperature transducer 17.

There is flow switch 34 on the same flushing line L3, downstream of the second temperature transducer 17 and upstream of the aseptic chambers

100. Downstream of the aseptic chambers 100 there is, instead, a diverter valve 35 with a needle valve 36 for regulating the flow rate.

The Applicant does not consider it necessary to explain in detail the state of the valves and other components optionally present in the apparatus 1 , as a person skilled in the art is capable of understanding effortlessly the overall operation of the apparatus 1 from the figures attached hereto and from the description of the method reported herein below.

The method for flushing aseptic chambers of a high-pressure homogenizer or pump, according to the present invention, is described below.

When the flushing cycle is activated, the flow rate of the positive displacement pump 16 follows a linear ramp until it reaches the normal operating value, for example 100-150 l/h. During this initial transient, the temperature of the water leaving the injector 2 is monitored by the first transducer 3 for the purpose of preventing it from dropping below a predetermined value, for example 125°C, which would lead to the loss of sterile conditions.

Simultaneously, the first controller 4 forces the first flow-rate regulating valve 5 to open so that the flow of steam is in excess with respect to the theoretical value defined by the flow rate of the water.

Once normal operating conditions have been reached, during the flushing cycle, the flow rate of non-sterile water (e.g. at a temperature of 15°-20°C) is maintained at the nominal value (e.g. 100-150 litres/h) by the feedback loop of the positive displacement pump 16.

A model with vanes was selected for the positive displacement pump 16 so as to process flow rates of water on the order of a few hundred litres/h, thereby preventing the vaporization thereof.

The flow rate of non-sterile water is distributed unequally in the first branch L21 and in the second branch L22 of the water inlet line L2, through the second inclined-axis pneumatic on/off valve 30 and the second flow-rate regulating valve 19, respectively.

Inside the injector 2, the water is mixed with the steam at a temperature of about 140°C. The flow-rate of the aqueous vapour entering the injector 2 is determined by the first flow-rate regulating valve 5, which is managed by means of the feedback loop made up of the first controller 4 and the first temperature transducer 3.

It should be noted that the first temperature transducer 3 is located upstream of the holding tube 31 for the purpose of increasing the responsiveness of the apparatus 1 , that is, for the purpose of reducing the inertia thereof.

Leaving the holding tube 31 , the sterile water enters the heat exchanger 15, where it surrenders part of the heat to the non-sterile water. In this manner, the sterile water is cooled and reaches a temperature of 60°C, which is monitored by the second temperature transducer 17. The maximum temperature of the sterile flushing water was selected so as not to jeopardize the intactness of the static and dynamic seals of the aseptic chambers 100.

The heat surrendered by the sterile water is absorbed by the non-sterile water, pre-heating it before it reaches the injector 2. After it has reached the aseptic chambers 100, the water is drained by means of the diverter valve 35 and the relative needle valve 36.

In the present flushing apparatus 1 , it is also possible to perform SIP cycles (SIP being the acronym for Sterilization In Place) and CIP cycles (CIP being the acronym for Cleaning In Place).

For example, the SIP cycle is activated prior to each new flushing cycle. During the SIP cycle, the steam inlet line L1 is active, whereas the water inlet line L2 proves to be inactive (the positive displacement pump 16 is off).

The aqueous vapour flows into the injector 2 and into the heat exchanger 15 and then reaches a second drain line for the condensate L4 located downstream of the aseptic chambers 100. A third inclined-axis pneumatic on/off valve 37 and a second float steam trap 38 for example are present along this drain line for the condensate. During this step, the first regulating valve 5 regulating the flow rate of aqueous vapour is controlled by a fourth temperature transducer 39 that is set with a value of about 128°C.

During the CIP cycle as well, the water inlet line L2 is inactive while the steam is flowing in the steam inlet line L1 . A washing solution is introduced into the apparatus 1 through a washing solution inlet line L5, on which a fourth inclined-axis pneumatic on/off valve 40 is installed.

During this step, the first flow-rate regulating valve 5 is governed by the second temperature transducer 17 so that the steam is at a temperature of about 60°C. The aim of steam injection is to heat the washing solution so as to increase its descaling capacity on the plates of the exchanger 15. The steam and the washing solution thus pass through the various components of the apparatus 1 and reach a CIP drain line, indicated by L6.

The characteristics of an apparatus and a method for flushing aseptic chambers of a high-pressure homogenizer or pump, according to the present invention, prove to be clear from the description, as do the advantages thereof.

In particular, owing to the use of the injector, the steam is injected directly into the non-sterile water, thus simplifying the overall structure of the apparatus. In fact, the shell and tube heat exchanger present in the solution disclosed in Italian patent no. 1410858 is no longer necessary. Moreover, the solution offered also achieves a more efficient heat exchange.

The temperature of the sterile flushing water is kept constant regardless of external disturbances such as fluctuations in the flow-rate or temperature of the incoming non-sterile water or incrustation of the injector or heat exchanger. This takes place due to the fact that the flow rate of incoming non-sterile water to the injector is regulated by means of the second flow- rate regulating valve, based on the temperature of the sterile water leaving the heat exchanger. The overall logic managing the apparatus makes use of dedicated loops for controlling the various units (steam inlet modulating unit, non-sterile water inlet modulating unit, and positive displacement pump). This makes it possible to reduce the overall inertia related to relatively low product flows (several hundred litres/h) and to improve stability even in the presence of external disturbances.

Lastly, the use of live steam at low pressure for sterilization (SIP cycles) increases the useful life of the seals of the aseptic chambers with respect to the use of superheated water and it does not require back-pressure valves downstream of the aseptic chambers, thus further simplifying the components of the apparatus.

Claims

1 . Flushing apparatus (1 ) for flushing aseptic chambers (100) of a high- pressure homogenizer or pump, comprising:

a steam injector (2) having a first inlet (2a) for the aqueous vapour, a second inlet (2b) for non-sterile water and an outlet (2c) for the superheated water obtained by mixing the aqueous vapour with the non- sterile water;

a heat exchanger (15) of the double-wall type having a non-sterile side (15a) receiving non-sterile water, and a sterile side (15b) receiving water from the outlet (2c) of the injector (2) and supplying sterile water to said aseptic chambers (100);

first means (3, 4) for detecting and regulating the temperature of the superheated water leaving said injector (2) for the purpose of maintaining a water temperature of at least 135°C;

second means (17, 18) for detecting and regulating the temperature of the sterile water leaving said heat exchanger (15) for the purpose of maintaining a water temperature within the range of 30°-80°C;

a positive displacement vane pump (16) that distributes water to the non- sterile side (15a) of said heat exchanger (15) and to the second inlet (2b) of said injector (2);

a first regulating valve (5) that regulates the flow rate of aqueous vapour to said first inlet (2a) of the injector (2) based on the temperature detected by said first temperature detecting and regulating means (3, 4) when the apparatus (1 ) is in a flushing configuration;

a second regulating valve (19) that regulates the flow rate of non-sterile water to the non-sterile side (15a) of said heat exchanger (15) based on the temperature detected by said second temperature detecting and regulating means (17, 18).

2. Flushing apparatus (1 ) according to claim 1 , wherein said first flow-rate regulating valve (5) supplies a maximum steam flow rate of about 1 1 kg/h to the first inlet (2a) of the injector (2).

3. Flushing apparatus (1 ) according to claim 1 or 2, wherein said first means (3, 4) for detecting and regulating the temperature comprises:

a first temperature transducer (3) that detects the temperature of the superheated water leaving said injector (2);

a first controller (4) which, in response to the temperature detected by said first temperature transducer (3) when the apparatus (1 ) is in the flushing configuration, controls said first flow-rate regulating valve (5).

4. Flushing apparatus (1 ) according to claim 3, wherein said first controller (4) is a Proportional-lntegrative-Derivative or a programmable logic controller.

5. Flushing apparatus (1 ) according to any one of the preceding claims, wherein said second flow-rate regulating valve (19) is an inclined-axis modulating valve.

6. Flushing apparatus (1 ) according to any one of the preceding claims, wherein said second means (17, 18) for detecting and regulating the temperature comprises:

a second temperature transducer (17) that detects the temperature of the sterile water leaving said heat exchanger (15);

a second controller (18) which, in response to the temperature detected by said second temperature transducer (17), controls the second flow-rate regulating valve (19).

7. Flushing apparatus (1 ) according to claim 6, wherein said second controller (18) is a Proportional-lntegrative-Derivative or a programmable logic controller.

8. Flushing apparatus (1 ) according to any one of the preceding claims, further comprising a holding tube (31 ) for the sterile water, which is interposed between the outlet (2c) of said injector (2) and the sterile side (15b) of said heat exchanger (15).

9. Method for flushing aseptic chambers (100) of a high-pressure homogenizer or pump that employs a flushing apparatus (1 ) according to one of the preceding claims, comprising the steps of: - mixing aqueous vapour and non-sterile water inside said steam injector (2) so as to obtain superheated water of a temperature of at least 135°C;

- cooling the superheated water thus obtained to 30°-80°C, surrendering heat to non-sterile water inside said double-wall heat exchanger (15);

- sending to said injector (2) the pre-heated non-sterile water coming from said heat exchanger (15).