WO1998000175A1

WO1998000175A1 - Sterilizer equipment for fluids in continuous flow by very fast heating in a solid matrix

Info

Publication number: WO1998000175A1
Application number: PCT/EP1997/003279
Authority: WO
Inventors: Andres Hirschfeld; María Juliana ROOSEN
Original assignee: Andres Hirschfeld; Roosen Maria Juliana
Priority date: 1996-06-28
Filing date: 1997-06-23
Publication date: 1998-01-08
Also published as: BR9715057A; AR007454A1; AU3343297A; ZA975712B

Abstract

The invention concerns an equipment for sterilizing in continuous flow any kind of liquids, said equipment being portable and of autonomous operation and comprising a feeding hopper (1), a pumping device (2), an energy recuperator interchanger (3), a fast heating block (4), a temperature expansion unit (5), a cooling interchanger (6), a temperature measure and control device (7), a flow measuring and control device (8), a continuous energetic use control device (9) and a measuring device for the registration of the sterilizing temperature (10). In the fast heating block (4), flow experiments a quick rise in temperature because it is propelled by means of ducts, being heat transferred to the inner section of these ducts by conduction within a solid matrix or block of high thermal conductivity.

Description

STERILIZER EQUIPMENT FOR FLUIDS IN CONTINUOUS FLOW BY VERY FAST HEATING IN A SOLID MATRIX

Disclosure of the Invention

The main objective of this invention is the developing of an equipment capable of sterilizing any kind of liquids in order to obtain a product with a longer useful life and with a minimum alteration of its original properties, in a greater grade than the one achieved with the present existing equipments.

Sterilization is based on a thermal short time - high temperature process, being able to adapt itself to the ideal temperature cycle for each product.

By means of this termal process a double effect can be achieved: elimination of the microbiologic activity and enzymatic inactivation, due to the fact that enzymes are responsible for the numerous alterations on the properties of products of natural origin. The system used for heating the product eliminates all the resistance to the transfer of heat that is possible to eliminate, allowing a perfect control of the Liquid's temperature at all times.

In the fast heating unity of the equipment, the heat generated in the heating elements is transferred by the conduction mechanism through a solid matrix of high thermal conductivity towards the internal surface of ducts pierced in said matrix, through which the fluid is made to circulate continuously.

Said system enables to take the liquid to the desired temperature in an extremely short period of time, achieving in this way the destruction of all kinds of microorganisms and spores, without allowing the oportunity for the enzymatic alteration of the product's qualities, even in very delicate products intended for human feeding and consumption, such as, fruit juices, milk and wines, preserving their colour, flavour and original nutritional properties.

Another objective of the present invention is the development of an equipment capable of sterilizing liquids which turns out to be small and lightweight, which is easier to transport and to use in situ, with less needs of services and annex equipment.

It also constitutes another objective of the present invention, the development of an equipment with the preceding characteristics, which should be easier and cheaper to build, and which requires neither of special technologies nor of costly materials.

Brief Description of Drawings

Drawing 1 briefly shows the fluid sterilizing equipment of the present invention. Drawing 2 shows a longitudinal section of the fast heating block. Drawing 3 shows a transversal section of the heating block.

Best Mode of Carrying Out the Invention

The fluid sterilizer equipment of the present invention, comprises an integrated collection of process unities and flow regulation and control devices as well as fluid temperature regulation and control devices. Said process unities are placed in series along the circuit that is continously traversed by the fluid and they are connected among them by external tubing.

The fluid sterilizer equipment of the present invention is capable of sterilizing fluids intended for human feeding and consumption, such as, fruit juices, milk and wines, thereby maintaining unaltered their nutritional and organoleptic properties.

These fluids may also be compounds or solutions of a compound having a chemical structure that is altered if exposed to temperatures higher than 90°C during a certain period of time.

The term "fluids", as used herein, also includs non-explosive and non flammable gases under pressure and temperature conditions present in any of the equipment units, more specifically in the fast heating unit.

As it can be seen in drawing 1, the fluid sterilizing equipment of the present invention consists of the following parts:

( 1) Feeding hopper (2) Pumping device

(3) Energy recuperator interchanger

(4) Fast heating block

(5) Temperature expansion

(6) Cooling interchanger (7) Temperature measuring and control device

(8) Flow measuring and control device

(9) Continuous energetic use control device

(10) Measuring device for the registration of the sterilizing temperature Now passing on to a more detailed description of each of the constitutive parts or unities of the fluid sterilizing equipment of the present invention, always referring to drawing 1, the feeding hopper ( 1) is built of appropriate material for the liquid it will hold and has both appropriate geometry and disposition in order to ensure an adequate continuous feeding of the equipment as well as the priming of the pumping unit.

The pumping device (2) consists of any mechanism that ensures an adequate volume of liquid for the operation of the equipment and that provides said volume at a gage pressure superior in 1 Kgf./cm2 to the minimum pressure necessary to avoid the liquid to boil at the working temperature.

Said mechanism may consist of any class of kinetics pump or of positive setover with the afore-mentioned characteristics.

The energy recuperator interchager (3) consists of an interchanger of any kind which supplies sufficient interchange surface so as to elevate the temperature of the ingoing volume to no more than 60°C using the heat extracted to the outgoing volume of the unity (5), (Temperature expansion), causing a small loss of load.

The fast heating block (4) consists of a monoblock or solid matrix of high thermal conductivity material and chemically inert respect of the product to process, as for example a metallic monoblock or one made of a metallic alloy, e.g., stainless steel.

As it is shown in drawing 2, the fast heating block has ducts for the passing of fluids and places for the heating elements, both with such geometric distribution so as to enable an efficient transfer of energy to the fluid, as well as an effective temperature control. Said ducts for the passage of the fluid and the places for the heating elements are longitudinally pierced in the solid matrix of the block, a characteristic of the design that enables to ensure that the heat transfer to the fluid is performed with the least thermal resistance possible, as well as to achieve an homogeneous temperature on the interior wall of the fluid ducts.

The longitudinally pierced ducts through which fluid circulates present a diameter between 1 and 6 millimeters and a total lenght between 1 and 2,5 meters.

The heating elements in the fast heating block are shielded electrical resistances.

The location of the temperature sensors is important to ensure an adequate control of the wall temperature. These are located in places also pierced directly in the block. The fast heating block (4) also has thermal insulation and mechanic shield.

The fluid temperature when coming out of the fast heating unit may range between 90°C and l50°C.

The diameter of the fluid ducts and the flow through the same must be such so as to ensure a regime of turbulent flow (Reynolds number more than 10000).

Always referring to drawing 2, on the extremes of the fast heating block there are headstocks which connect the main external tubing to the block, with the interior fluid ducts. The input distribution headstock and the output headstock collector, consist both of a main tube that is subdivided into secondary ducts, that allow for the feeding and disposal of liquid, respectively to and from the fluid circulation ducts pierced or inserted in the monoblock.

As it can be seen on drawing 3, the geometric configuration preferred for the relative position of the fluids ducts (1) and of the heating elements (2) in the fast heating block, is the circular concentric disposition respect to the central axis of said block. In this configuration, the heating elements are placed forming an external circle, and the fluid ducts forming a circle interior to it.

We now continue with reference to drawing 1, the temperature expansion unit (5), consists of a duct of such dimensions as to ensure:

- a piston-like flow, and

- an appropriate volume so as to supply a stay time not inferior to 110% and not superior to 200% of the necessary period for the sterilization at the selected temperature according to the range of fluid flows.

This unity has thermal insulation that ensures a constant temperature from the entrance to the exit of the fluid, and it also has a temperature sensor at the entrance, so as to measure and control the sterilization temperature.

The cooling interchanger (6), consists of an interchanger of any kind with interchange surface sufficient so as to cool the liquid emergent from the energy recuperator unit (3 ), up to a temperature of between 40 and 60°C, using water as cooling fluid.

The sterilizing system of the present invention has also a final fluid cooling.

All the afore-mentioned units shall be built with the appropriate material to be in contact with the fluid to be processed in all its parts in contact with the same.

The temperature measuring and control device (7), consists of an electronic device, whose response to the measurement carried out is of the type proportional- differential, this electronic device being able to receive the signal coming from the temperature sensors of the block, to supply an instantaneous value of the block's temperature, and to dosify the energy given to the heating elements so as to ensure a constant temperature in the heating block with a maximum variation of 1°C in more or in less.

The flow measuring and control device (8), consists of a device able to measure the fluid volume without generating an important loss of load, combined with a volume of flow control system.

The latter may be atomatic or of manual operation, consisting in this last case of a restriction valve of the regulable volume of flow. This element must be the system's main load loss.

The continuous energetic use control device (9), consists of any electronic device which allows to visualize independently the state on-off of each heating element, enabling the identification of the same with insignificant energetic consumption.

It consists, for example, for the case of heating based on electric energy, in a collection of toroidal cores supplied with secondary coilings able to generate an electromotive force sufficiently induced so as to feed each L.E.D. elements, that will be the luminous indicators. Each of these cores shall be crossed by each of the ducts that feed a heating element. Whenever the heating element receives energy, the indicator element shall be illuminated and viceversa. The collection of this indicating elements shall be located in the control panel and their location shall allow the easy indentification of the heating element that corresponds to each indicating element.

The measuring device for the registration of the sterilizing temperature (10), consists of an electronic device able to receive the signal coming from the temperature sensors of the temperature expansion unit (5), to supply an instantaneous value of the temperature of the fluid contained in said unit and to leave record of said value, for a continuous control or for later analysis of the sterilization temperature.

It shall be understood that minor variations may be introduced in any of the units and devices that in whole comprise the sterilizing equipment of the present invention, without it meaning to draw away from the objectives and scope of the invention, as it is defined in the enclosed claims.

Claims

1. An equipment for the sterilization of a fluid in continuous flow, that in a joint and combined way has the following devices and process units:

a) a fluid-pumping device, b) a fluid preheating unit, c) a very fast fluid-heating unit, d) a unit for keeping fluid at a constant temperature during a certain time interval (Temperature expansion unit), e) a saving-energy unit by means of fluid precooling, f) a final fluid cooling unit, g) a device for measuring and controlling fluid flow, h) a device for verifying the funcional status of heating elements, i) a device for measuring and controling fluid temperature in unit d),

characterized in that,

- in the heating unit c), flow experiments a quick rise in temperature because it is propelled by means of ducts, and heat is transferred to the inner section of these ducts by conduction within a solid matrix or block of high thermal conductivity, and; - the equipment maintains unaltered its original properties during a very prolonged time, is portable and of autonomous operation.

2. An equipment for the sterilization of a fluid in a continuous flow, according to claim 1 , characterized in that said very fast fluid heating unit c) has, -in a joint and combined way, the following features: a - a solid matrix or monoblock of high thermal conductivity as well as chemically inert regarding the fluid to be sterilized, b - longitudinally pierced ducts or ducts inserted in said monoblock, through which fluid circulates, c- longitudinally pierced ducts or ducts inserted in said monoblock, within which heating elements can be found, d.- heating elements, e.- headstocks for incoming and outgoing fluids, f- block temperature measuring system and block heating control, g - thermal insulation, h - external mechanical protection.

3. An equipment for the sterilization of a fluid in continuous flow, according to claim 2, wherein said very fast fluid-heating unit has a metallic monoblock or one made of a metallic alloy.

4. An equipment for the sterilization of a fluid in continuous flow, according to claim 2, wherein said very fast fluid-heating has a monoblock of solid material of high thermal conductivity, and is chemically inert regarding the fluid in which said ducts b. and c. either pierced or inserted in the same are set in concentrical circles regarding the monoblock' s central axis.

5. An equipment for the sterilization of a fluid in continuous flow, according to claim 2, wherein said very fast fluid-heating unit has a monoblock of solid material of high thermal conductivity, and is chemically inert regarding the fluid in which ducts b. pierced or inserted in the same for fluid circulation present a diamenter between 1 and 6 millimeters, and a total length between 1 and 2,5 meters.

6. An equipment for the sterilization of a fluid in continuous flow, according to claim 2, wherein said heating elements d. are shielded electrical resistances.

7. An equipment for the sterilization of a fluid in continuous flow, according to claim 2, wherein said headstocks e., for incoming and outgoing fluid are constituted by a main tube that is subdivided in secondary ducts that allow for the feeding and disposal of liquid respectively to and from the fluid circulation ducts pierced or inserted in the monoblock.

8. An equipment for the sterilization of a fluid in continuous flow, according to claim 2, wherein said system f. for measuring the block temperature and for controlling the heating of the block is electronically operated, and whose response to the measurement carried out is of the type proportional-differential.

9. An equipment for the sterilization of a fluid in continuous flow, according to claims 1 and 2, wherein the fluid sterilized with the said equipment is considered to be apt for human or animal feeding and maintains unaltered its nutritional and organoleptic properties.

10. An equipment for the sterilization of a fluid in continuous flow, according to claim 7, wherein said fluid apt for human feeding and consumption is selected from the group consisting of: fruit juices, milk and wines.

11. An equipment for the sterilization of a fluid in continuous flow, according to claims 1 and 2, wherein said fluid is a compound or a solution of a compound having a chemical structure that is altered if exposed to temperatures higher than 90°C during a cetain period of time.

12. An equipment for the sterilization of a fluid in continuous flow, according to claims 1 and 2, wherein said fluid is a non-explosive and non flammable gas under pressure and temperature conditions of any of the equipment units, more specifically in the fast heating unit.

13. An equipment for the sterilization of a fluid in continuous flow, according to claims 1 and 2, wherein the fluid temperature when coming out of the fast heating unit is between 90°C and 150°C.

14. An equipment for the sterilization of a fluid in continuous flow, according to claims 1 and 2, characterized also by the fact that fluid sterilization is also carried out during the following successive stages, and in the established order:

a) during fluid passage throughout pierced ducts or ducts inserted in a monoblock or solid matrix, said matrix being at a higher average temperature than the outgoing fluid temperature in said ducts, the result being a very quick rise in fluid temperature in the fast heating unit,

b) in the temperature expansion unit, during the period of time at which the fluids maintain the exit temperature of said ducts, being said period of time not less than 110% and not more than 200% of the necessary time for sterilization at the chosen temperature according to the fluid flow range.

15. An equipment for the sterilization of a fluid in continuous flow, according to claims 1 and 2, wherein the signal generated by the temperature sensors of the block in the fast heating unit is processed in an analogue or analogue-digital way to module the electric signal that controls the flow-regulation device, thereby obtaining an equipment with automatic operation.

16. An equipment for the sterilization of a fluid in continuous flow, characterized by the application of a solid matrix, according to claim 2, the said matrix consisting of a mass made up of adequate materials, preferably of high thermal conductivity to transfer heat to Uquids that go through ducts of shapes and sizes adequate to each type of liquid, and constructed in the interior of such solid mass, for periods of time, and with rise and reduction temperature curves adequate enough to obtain as a result the elimination of microbiologic activity and enzymatic inactivation in it with a minimum alteration of the original properties.