Apparatus for sterilizing, pasteurizing, and/or disinfecting a pumpable or free flowing medium

Apparatus for sterilizing, pasteurizing, and/or disinfecting a pumpable or free-flowing medium includes at least one heating source, a temperature holding device which is monitored by means of a thermal sensor, and an outlet. The pressure required for the treatment is maintained within the temperature holding device by at least one unit conveying member in opposition to a resistance pressure. Two conduit branches are connected to a conduit located downstream of the temperature holding device. A restriction member and a shut-off member are disposed in each of the two conduit branches, with one conduit branch extending to the outlet while the other conduit branch leads to the feed conduit upstream from the heating source as a return conduit. The restriction member is hereby part of a heat exchanger which guides medium from the temperature holding device in counterflow to a flow of medium to the heating source.

BACKGROUND OF THE INVENTION

The present invention relates, in general, to an apparatus for sterilizing, pasteurizing, and/or disinfecting pumpable or free flowing medium.

Nothing in the following discussion of the state of the art is to be construed as an admission of prior art.

Austrian Pat. No. AT 399 658 B describes an apparatus of this type including a microwave unit forming a treatment chamber for receiving contaminated medium, and a temperature holding device for maintaining the medium at a desired temperature. A three-way valve is disposed upstream of a medium outlet and downstream of a pump and includes one port connected via a return conduit to the inlet for incoming contaminated medium. Depending on the process stage, either contaminated medium or already pasteurized, disinfected or sterilized medium is intended to flow through the conduit leading downstream of the holding device so that during change of the medium flow from return flow to outflow through appropriate actuation of the three-way valve, contaminated or insufficiently treated medium may reach the outlet.

It would therefore be desirable and advantageous to provide an improved apparatus for sterilizing, pasteurizing, and/or disinfecting a pumpable or free flowing medium to obviate prior art shortcomings and to prevent vapor formation and ingress of contaminated medium into the outlet.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, an apparatus for sterilizing, pasteurizing and/or disinfecting a pumpable or free-flowing medium, includes at least one heating source receiving medium via a feed conduit, a temperature sensor for monitoring a temperature of the medium along a temperature holding device downstream of the heating source, an outlet, a conveying member moving the medium to the temperature holding device and maintaining a feed pressure in the temperature holding device, and at least two conduits routed downstream from the temperature holding device, with one of the conduits communicating with the outlet, and with the other one of the conduits constituting a return conduit for returning the medium to the feed conduit, each one of the conduits including a flow restriction member generating a resistance pressure in opposition to the feed pressure of the conveying member by restricting a passage for flow of medium, and a shutoff member for controlling a flow of fluid through the conduit, wherein the restriction member is part of a heat exchanger which guides medium from the temperature holding device in counterflow to a flow of medium to the heating source.

According to another feature of the present invention, the restriction member may include a heat exchanging coil having a flow cross section which is smaller than a flow cross section of the conduit upstream of the restriction member.

According to another feature of the present invention, a flowmeter may be disposed in the feed conduit. As a result, the apparatus can be operated at different flow rates so as to maintain the desired temperature of the medium within the temperature holding device for a required retention time. This is especially of relevance when different processes are involved, such as sterilizing, pasteurizing or disinfecting.

According to another feature of the present invention, a further temperature sensor may be disposed downstream of the restriction member in the conduit that leads to the outlet. In this way, the medium temperature can be monitored, when reaching the outlet, and steps can be undertaken to prevent the medium temperature from exceeding 60° C. and thereby prevent damage to outlet conduits or other downstream conduits.

According to another feature of the present invention, a pressure sensor may be disposed in a passageway between the conveying member and the restriction member, thereby providing an added monitoring option of the apparatus.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Turning now to the drawing, and in particular toFIG. 1, there is shown a schematic flow diagram of one embodiment of an apparatus for sterilizing, pasteurizing, and/or disinfecting pumpable or free flowing medium in accordance with the present invention, including a supply conduit1for incoming contaminated liquid medium which flows through a filter1′ into a storage tank2. A feed conduit3connects a bottom discharge of the tank2with a pump4which forces medium from the tank2via a heating unit, generally designated by reference numeral5, to a temperature holding device6of coiled configuration. The heating unit5may be of any suitable construction or energy source known to the artisan and may, optionally, include a microwave heater, as indicated, by way of example, by reference numeral5′. The holding device6terminates in a conduit portion24which is split in two conduit branches13and14, with the conduit branch13routed back to the storage tank2, and the conduit branch14leading to a decontaminated medium outlet15. Disposed in the conduit branch13is a pump7, and disposed in the conduit branch14is a pump8to force medium along the intended path.

Placed upstream of the temperature holding device6is a heat sensor9and placed downstream of the temperature holding device6is a heat sensor10. Both temperature sensors9,10monitor the medium temperature directed through the holding device6to maintain the temperature constant. Provided in the conduit portion24upstream of the pump7is a pressure sensor11for measuring a medium pressure in an area between the pump4and the pump7and8, respectively. A shut-off member16is disposed in the conduit branch13, downstream of the pump7, and a shut-off member17is disposed in the conduit branch14, downstream of the pump8. In this way, the flow of medium can be regulated by closing one or the other of the conduit branches13,14. Of course, the pumps7,8may be constructed to be self-locking, i.e. the pumps7,8are constructed to cut a flow through the associated conduit branches, so that the provision of shut-off members may be omitted.

Reference numeral18designates a heat exchanger to pre-heat incoming medium from the storage tank2and flowing to the heating unit5, by medium exiting the temperature holding device6.

Disposed in feed conduit3upstream of the pump4is a flowmeter for monitoring the actual medium flow rate in order to compute a retention time of the medium within the temperature holding device6.

The apparatus operates as follows: When starting the apparatus, incoming contaminated medium is circulated by the pump4to flow from the storage tank2via the heating unit5, temperature holding device6, conduit branch13, pump7and shut-off member16back to the storage tank2. Pump8in conduit branch14is shutdown, and shut-off member17is closed. As a result, no medium can flow trough conduit branch14, not even in the zone upstream of the pump8. The apparatus is operated in this mode until the temperature sensor9, upstream of the holding device6, and the temperature sensor10, downstream of the holding device6, show a constant temperature. By means of the flowmeter12, the required retention time of the medium to be treated in the holding device6is determined and controlled to a desired value by appropriately operating the pumps4and7.

As soon as the desired temperature of the medium in the holding device6is kept constant and the desired retention time is reached, pump7in conduit branch13is shut down, and pump8in conduit branch14is operated. At the same, shut-off member16is closed and shut-off member17is opened. In both operating modes, the pressure sensor11ascertains the pressure in the system and thus is able to monitor the necessary pressure for maintaining the operating parameters. Suitably, a further temperature sensor19is disposed in conduit branch14in immediate proximity of the outlet15for monitoring the temperature of outflowing medium. The apparatus is so constructed that a temperature above 60° C., as registered by the temperature sensor19, results in a shutdown of the apparatus or in a medium circulation, or in an activation of a further heat exchanger (not shown), so as to prevent a discharge of excessively heated medium and thereby damage to the system.

Turning now toFIG. 2, there is shown a schematic flow diagram of another embodiment of an apparatus for sterilizing, pasteurizing, and/or disinfecting pumpable or free flowing medium in accordance with the present invention. Parts corresponding with those inFIG. 1are denoted by identical reference numerals and not explained again. The description below will center on the differences between the embodiments. In this embodiment, provision is made for the arrangement of a heat exchanger20, instead of the pumps7,8, for generating a resistance pressure to thereby regulate a flow of medium through one or the other conduit branches13,14. The heat exchanger20includes a heat exchanging coil21disposed in a portion of the conduit branch13and having a flow cross section which is smaller than the cross section of the conduit branch13upstream of the heat exchanging coil21. Likewise, the heat exchanger20includes a heat exchanging coil22disposed in a portion of the conduit branch14and having a flow cross section which is smaller than the cross section of the conduit branch14upstream of the heat exchanging coil22. Both heat exchanging coils21,22guide incoming medium in counterflow to the flow of medium through a heat exchanging region23of the feed conduit3, whereby the heat exchanging region23is hereby not reduced in cross section in relation to the feed conduit3.

Operation of the apparatus ofFIG. 2is similar to the operation of the apparatus ofFIG. 1, with the difference residing in the buildup of the resistance pressure, which in the embodiment ofFIG. 2is realized by the configuration of the heat exchanging coils21,22which generate a pressure acting in opposition to the conveying pressure of the pump4, as a result of the restriction, and measured by the pressure sensor11. When starting the apparatus, shut-off member17in the conduit branch14to the outlet15is closed, whereas the shut-off member16in the conduit branch13to the storage tank2is open. Thus, the medium circulates until the medium has reached the desired temperature, as registered by the temperature sensor10, and the desired pressure, as measured by the pressure sensor11, to ensure that medium exiting the temperature holding device6is sufficiently decontaminated, i.e. sterilized, pasteurized or disinfected. Subsequently, the shut-off member16in the conduit branch13is closed and the shut-off member17in the conduit branch14is opened to allow a discharge of the decontaminated medium through the outlet15. The temperature of outflowing medium is hereby monitored by the temperature sensor19to prevent overheating, when the medium exits through the outlet15, and thereby prevent damage to the system.

It will be understood by persons skilled in the art that the temperature sensor9may be omitted in the apparatus according to the invention, by using the temperature, as determined by the temperature sensor10, optionally also the pressure, as measured by the pressure sensor11and the flow rate, as determined by the flowmeter, to realize a sufficient supervision of the treatment temperature and treatment time.