IE893232L

IE893232L - A process for automatically flushing an apparatus for¹removing bacteria from milk

Info

Publication number: IE893232L
Application number: IE323289A
Authority: IE
Inventors: Karlheinz Zettier
Original assignee: Anne Maeve O Sullivan
Priority date: 1988-10-07
Filing date: 1989-10-06
Publication date: 1990-04-07
Also published as: DE3834133C1; IE63040B1; SE8903169L; CH677430A5; AR243060A1; NL8902393A; SE500425C2; FR2637464B1; NL192075C; NL192075B; ATA202589A; AT397185B; FR2637464A1

Abstract

In the removal of bacteria from milk with the aid of a bacteria removal centrifuge (ultracentrifuge), two liquid streams arise of which one comprises milk from which bacteria have been removed and the other comprises the bacterial concentrate which is then sterilised and mixed with a part-stream of the milk from which bacteria have been removed. This mixture is then remixed with the remaining milk from which bacteria have been removed. When the unit is rinsed, the rinsing liquid is fed at two positions of the unit staggered in time, as a result of which the liquid streams flowing through the milk path and the concentrate path arrive at the same time at the mixing position for milk from which bacteria have been removed and sterilised concentrate. From this point, the mixture is no longer returned into the outlet line for milk from which bacteria have been removed, but is passed into the effluent duct. This avoids bacterial concentrate from having to be passed into the effluent duct because rinsing liquid has already been passed into the mixing position via the milk path, while bacterial concentrate is still flowing to the mixing position via the concentrate path. [DE3834133C1]

Description

63040 A PROCESS FOR AUTOMATICALLY FLUSHING AN APPARATUS FOR REMOVING BACTERIA FROM MILK The invention relates to a process for automatically flushing an apparatus for removing bacteria from milk, in which the bacteria-containing milk is supplied to the inflow of a bacteria-removing centrifuge in which the bacteria are separated from the milk, the bacteria-free milk is outlet from the centrifuge via an outflow line, bacteria-rich concentrate is periodically fed from the centrifuge into a concentrate vessel and low-bacteria concentrate is likewise supplied to the concentrate vessel via a concentrate outflow, from which concentrate vessel the concentrate is discharged and supplied to a heated sterilising container which is provided with an outlet pipe in which the outflowing, sterilised concentrate is mixed with a sub-stream of the bacteria-free milk outflowing from the centrifuge, and this mixture is then recombined with the line for bacteria-free milk.

An apparatus of this type for removing bacteria from milk has been described, for example, in the publication 9997-8274-000 in the name of the Applicant. After the product treatment such apparatus must be flushed with a flushing fluid for sterilisation prior to the next product cycle. This generally takes place in that firstly the product residues are removed by supplying the apparatus with flushing fluid whereupon the actual purification is carried out using chemical agents. During the removal of the product using flushing fluid, on the one hand no flushing fluid is to enter the product and on the other hand, however, as little of the product as possible is to flow into the drains together with the flushing fluid.

In the present case the fluid which is supplied to the centrifuge is divided into two sub-streams, namely the bacteria-free milk which is discharged via the outflow line and the bacteria concentrate which is forwarded from the 5 concentrate vessel into the sterilising container. In the sterilising container the bacteria concentrate is heated to a'high temperature by direct steam before being discharged via the outlet pipe. To reduce the temperature .of the bacteria concentrate, a sub-stream of the bacteria-free 10 milk is mixed with the bacteria concentrate in the outlet pipe. This mixture is then returned to the outflow line for bacteria-free milk.

During the flushing of the apparatus the mixture discharged from the outlet pipe can be returned to the 15 outflow line for bacteria-free milk only until flushing fluid appears in one of the sub-streams being mixed in the outlet pipe. This occurs first in the outflow line for bacteria-free milk because the latter is passed through at a higher speed whereas on the concentrate side the entire 20 contents of the concentrate vessel and also of the sterilising container must be displaced. This means that very soon following the supply of flushing fluid into the inflow of the centrifuge, the mixture being discharged from the outlet pipe can no longer be fed into the outflow line 25 for bacteria-free milk although on the concentrate side bacteria concentrate is still flowing into the outlet pipe. As a result not only is an undesired product loss unavoidable but in addition the disposal of this concentrate, mixed with flushing fluid, presents problems. 30 The aim of the present invention is to provide a process for flushing such apparatus whereby the product losses are reduced to a minimum.

This aim is fulfilled in that prior to the flushing of the apparatus, the line for the low-bacteria concentrate is connected to the inflow of the centrifuge, the periodic discharge of the bacteria-rich concentrate is suspended and flushing fluid is supplied to the concentrate vessel for a predetermined interval of time before flushing fluid is fed into the inflow of the centrifuge, this interval of time being contrived to be such that the flushing fluid which is fed through the outflow line for bacteria-free milk and the flushing fluid which is fed through the concentrate vessel arrive simultaneously at the outlet pipe of the sterilising container and only at this point in time is the outlet pipe separated from the line for bacteria-free milk.

The fact that the low-bacteria concentrate is returned to the inflow of the centrifuge and that the discontinuous discharge of bacteria-rich concentrate is interrupted means that no more concentrate flows into the concentrate vessel. The time now required to convey the concentrate contained in the system to the outlet pipe is dependent upon the concentrate quantity and the volume flow on the concentrate side. From this data it is possible to calculate the time interval during which flushing fluid must be fed initially only into the concentrate vessel. Before the concentrate has been completely displaced, the product inflow to the centrifuge is also blocked and instead flushing fluid is fed into the centrifuge. The time calculation should ensure that flushing fluid arrives in the outlet pipe from both line systems simultaneously.

An exemplary embodiment of the invention is illustrated in the drawing and will be explained in detail in the following. - 4 Via the inflow 1 bacteria-containing milk is supplied to a bacteria-removing centrifuge 2. The bactejria separated in the centrifuge 2 are conducted into a concentrate vessel 5 on the one hand intermittently via a 5 line 3 in the form of a bacteria-rich concentrate and on the other hand continuously via a concentrate line 4 in the form of a low-bacteria concentrate. The bacteria concentrate is then pumped via a pump 6 and a line 7 into a sterilising container 8 in which it is heated by the 10 introduction of super heated steam. The sterilised bacteria concentrate is discharged from the sterilising container 8 via an outlet pipe 9 in which the concentrate is mixed with a sub-quantity of the bacteria-free milk outflowing from the centrifuge 2 via an outflow line 10, in 15 order to reduce further the temperature of the bacteria concentrate. Via a control element 11 connected to the output end of the outlet pipe 9 the mixture either can be returned to the outflow line 10 or fed into a waste channel 12.

If the apparatus is to be flushed, firstly an control element 13 is actuated whereby the low-bacteria concentrate is returned to the inflow 1 exclusively via a line 14. The intermittent discharge of bacteria-rich concentrate via the line 3 is interrupted. Then flushing 25 fluid is supplied to the concentrate vessel 5 initially only via a flushing line 15 whereby the concentrate is displaced from the concentrate vessel 5 and from the line 7 into the sterilising container 8. After a predetermined interval of time the product supply through the inflow 1 is 30 interrupted and instead flushing fluid is fed via a flushing line 16 into the inflow 1 of the centrifuge 2.

This flushing fluid is discharged from the centrifuge 2 via the outflow line 10 and is fed relatively rapidly via a sub-stream line 17 to the outlet pipe 9 of the sterilising container 8. In the meantime the bacteria concentrate 5 contained in the sterilising container 8 has also been completely displaced so that two streams of flushing fluid meet in the outlet pipe 9. As a result of the actuation of the control element 11 these two flushing fluid streams are fed into the waste channel 12. In this way it is possible 10 to flush the apparatus without product loss.

Claims

1- A process for automatically flushing an apparatus for removing bacteria from milk, in which the bacteria-containing milk is supplied to the inflow of a 5 bacteria-removing centrifuge in which the bacteria are separated from the milk, the bacteria-free milk . is ..discharged from the centrifuge via an outflow line, bacteria-rich • concentrate is periodically fed from the centrifuge into a concentrate vessel and low-bacteria concentrate is likewise 10 supplied to the concentrate vessel via a concentrate outflow, from which concentrate vessel the concentrate is discharged and supplied to a heated sterilising container which is provided with an outlet pipe in which the outflowing, sterilised concentrate is mixed with a 15 sub-stream of the bacteria-free milk outflowing from the centrifuge, and this mixture is then recombined with the line for bacteria-free milk, characterised in that prior to the flushing of the apparatus the line for the low-bacteria concentrate is connected to the inflow of the centrifuge, 20 the periodic discharge of the bacteria-rich concentrate is discontinued, and flushing fluid is supplied to the concentrate vessel for a predetermined interval of time before flushing fluid is introduced into the inflow of the centrifuge, this interval of time being contrived to be 25 such that the flushing fluid which is conducted through the outflow line for bacteria-free milk and the flushing fluid which is conducted through the concentrate vessel arrive simultaneously at the outlet pipe of the sterilising r container and only at this time Is the outlet pipe 30 separated from the line for bacteria-free milk.

2. A process for automatically flushing an apparatus for removing bacteria from milk according to claim 1, substantially as hereinbefore described with reference to the accompanying drawings. F. R. KELLY & CO., AGENTS FOR THE APPLICANTS.