WO2010100080A1

WO2010100080A1 - Method and equipment for refrigerating and/or moving fluids using liquefied cryogenic gases

Info

Publication number: WO2010100080A1
Application number: PCT/EP2010/052443
Authority: WO
Inventors: Tommaso Bucci; Maurizio Frati
Original assignee: L'air Liquide Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude; Air Liquide Italy S.P.A.
Priority date: 2009-03-03
Filing date: 2010-02-25
Publication date: 2010-09-10
Also published as: IT1393250B1; EP2404103A1; ITMI20090308A1

Abstract

A method and equipment for refrigerating and/or moving a fluid, for example a multiphase fluid or a fluid containing fluid or solid agglomerations, this fluid being present in its own storage reservoir and being introduced into a loading chamber (2) and being subsequently subjected to the action of a different working fluid. Provision is made for the creation of a pressure drop in the loading chamber (2) to draw the multiphase fluid into it from the reservoir and subsequently to transfer it into a chamber (1) where it is refrigerated by means of cryogenic fluids, while in this chamber (1) the working fluid is used to generate a pressure greater than atmospheric pressure in the chamber (1), thereby enabling the multiphase fluid to be transferred subsequently towards a further use, said fluid thus being moved from the reservoir and towards the further use without subjecting this fluid to the action of moving mechanical members.

Description

METHOD AND EQUIPMENT FOR REFRIGERATING AND/OR MOVING FLUIDS USING LIQUEFIED CRYOGENIC GASES

The present invention relates to a method for refrigerating and/or moving fluids according to the preamble of the principal claim. The present invention also relates to equipment for applying this method according to the corresponding independent claim.

In particular, the present invention concerns a method and equipment for collecting fluids, refrigerating them with liquefied cryogenic gases and moving them, where these fluids may be multiphase or fluid agglomerations, that is to say fluid mixtures composed of substances in the liquid or solid state, without using moving mechanical members in contact with them. Specific examples of multiphase fluids that may be cited, without limiting the generality of the invention, are crushed grapes, that is to say the fluid produced by crushing the fruit, olive paste, that is to say the fluid produced by crushing olives, and any other fluids produced by crushing plant substances to which other liquid components may be added as required. In the case of crushed grapes, this product can be described as a multiphase fluid whose liquid component is similar to a sugar solution and whose solid parts are the partially crushed fruits, skins and pips.

With reference to this fluid, it is usually moved from a collecting or containing reservoir to a refrigeration system where, depending on the form of refrigeration, it may come into contact with a liquefied cryogenic gas or with surfaces at lower temperatures such as the walls of tubes forming parts of the heat exchanger. This movement is usually provided by using mechanical systems such as pumps or the like whose operation is dependent on contact between moving mechanical parts and the fluid. In the case of crushed grapes, if the fluid is handled by the usual transfer members such as pumps of various types and designs, its solid parts may be crushed and broken, causing deterioration of its qualitative properties which detract from the quality of the subsequent end product.

Consequently, in order to avoid undesired crushing and mechanical stresses in the aforesaid fluid, many wine producers commonly make use of the force of gravity to move the fluid by transferring it from one stage of processing to the next by allowing it to fall, achieving this by installing the components used for the different conversion processes at different heights .

It will be clear from the preceding paragraph that this gives rise to problems, which may be serious, in terms of space management and the limits imposed on the configuration of the equipment as a whole.

The object of the present invention is to propose a method and equipment for applying the method which enables a fluid, which may be multiphase, of the aforesaid type to be collected, refrigerated and transferred without coming into contact with moving mechanical parts such as those present in ordinary pumping means or similar means used at the present time to provide the aforesaid movement, for example movement from a collecting or containing reservoir to a refrigeration installation.

A further object is to propose an invention for moving a multiphase fluid of the aforesaid type which can also make use of benefits similar to those provided by gravity transfer without requiring the machines of the equipment used for the overall process of converting this fluid to be placed in particular positions or at particular heights. These and other objects, which will be evident to those skilled in the art, are achieved by a method and equipment according to the appended claims.

To facilitate the understanding of the present invention, the following drawings are attached, purely by way of non-limiting examples. In these drawings, Figure 1 shows a schematic view of a first embodiment of equipment according to the invention; and Figure 2 shows a view similar to that of Figure 1 but portraying a variant of the invention.

The present invention makes innovative use of known concepts (such as those described in patent applications MI99A002399 and MI2003A002367) relating to cooling by heat exchange using direct contact between fluids, in which the refrigerant fluid is a cryogenic fluid which, in the conditions of use, changes its state from liquid to vapour, thus removing heat from the fluid to be treated. Use is also made of existing knowledge relating to the use of compressed gases as motive fluids in equipment known as Venturi tubes.

With reference to Figure 1, this shows a block diagram identifying the principal components used in a general application of the invention which operates discontinuously by a cyclic succession of stages in which a multiphase fluid to be refrigerated is loaded, is refrigerated, and is transferred. Figure 1 shows schematically the measurement, shut-off and regulation members (such as valves) required for the operation of the invention: these members are not described further, since this is unnecessary for the understanding of the invention and in any case they are known in the existing art.

No description has been given of other instruments which are commonly used to measure variables relating to operation such as pressure, temperature and level, since this is unnecessary for the understanding of the invention, and in any case these instruments are known in the existing art.

In Figure 1, the number 1 indicates a container, hereinafter termed a "refrigeration chamber", for receiving a multiphase fluid which is to be refrigerated therein and is supplied thereto via a line 5 and which, after refrigeration, is transferred by means of a duct 6 for subsequent known forms of processing such as, in the case of crushed grapes, pressing, cold soaking or fermentation. Shut-off valve members 5A and 6A are provided, respectively, on the line (or duct) 5 and on the duct 6.

A duct 7 (with its own valve member 7A) connected to a cryogenic fluid reservoir (not shown) also runs to the insulated refrigeration chamber (or treatment chamber in general) 1. Said fluid is kept in the liquid state in this reservoir and at a pressure greater than atmospheric pressure. The cryogenic fluid is preferably chosen from CO2, N₂ and Ar.

This cryogenic fluid (or more generally a gas, as described below) is preferably, but not exclusively, injected through a pipe which is located inside the chamber 1 and coaxial therewith and which is provided with one or more holes for the passage of the aforesaid cryogenic fluid. This solution is not shown in the drawings. Thus the cryogenic fluid (or other fluid introduced into the chamber 1) can contact the fluid to be treated at a plurality of points and on a plurality of sides, so as to act on it more effectively.

A duct 8 runs from the refrigeration chamber 1 and is connected to two other ducts 9 and 10, provided with valve members 9A and 1OA; the duct 9 is open at one end

(to the atmosphere, for example) , while the duct 10 is connected to a Venturi tube 3 (advantageously soundproof) from which runs a duct 11 and to which runs a duct 12 running from a container 2 hereinafter termed the "loading chamber", from which there also runs a line 5 connecting the chamber 2 to the chamber 1. A valve member 12a is present on said duct 12.

The loading chamber 2 (which is also insulated, as are the ducts 4, 5, 6 and 7) is connected to a duct 4, which in turn is connected to a reservoir (not shown) containing the multiphase fluid to be treated and/or moved, and to a duct 13, into which gases or vapours under pressure are introduced from suitable reservoirs or generators (not shown) . The ducts 4 and 13 are also provided with valve members 4A and 13A.

The duct 6 can be connected, as shown in Figure 1, to an insulated duct 14 (provided with a valve member 14A) connected to a source of gaseous fluid; this duct 6 can also comprise a portion 6K which is undulating, in other words which has small variations of height

(indicated by 15) , in such a way that the contained gas separates from the fluid present in this duct and naturally forms gas pockets which are spaced apart by portions containing only the fluid to be moved.

All the valve members which have been described, and other members (even if they have not been described) which are commonly used in fluid refrigeration and movement equipment (such as members for controlling the pressure, flow rate and temperature) are advantageously operated automatically by programmable logic controllers (PLCs) or similar units capable of reading the values recorded by the aforesaid members and of acting on the valve members by suitable control operations.

The use of the equipment of Figure 1, that is to say the application of the method according to the invention, comprises a first stage in which a (motive) fluid is sent into the duct 10: this fluid can be pressurized by means of the duct 7 (by opening the valve members 7A and 1OA, and closing the valve members 6A, 5A and 9A) , or by using a source, of compressed air for example, connected to the duct 10 between the valve member 1OA and the Venturi tube 3, indicated in the drawing by 24 and provided with a valve member 24A. The motive fluid enters the Venturi tube 3 and passes into the duct 11. By its passage, it creates a pressure drop in the duct 12, and, if the valve members 12A and 4A have been opened and the valve members 13A and 5A closed appropriately, this pressure drop is transferred to the loading chamber 2 and to the duct 4 connected to the containing reservoir of the multiphase fluid. Consequently, said fluid is drawn from the containing reservoir and reaches the chamber 2 without being subjected to any action by moving mechanical members such as those of a pump or screw or the like.

When the fluid has reached a predetermined level in the chamber 2, the members 12A and 4A are closed. The fluid is then transferred to the refrigeration chamber 1. This transfer can be carried out by gravity if the chamber 2 is placed at a higher level than the chamber 1, or by sending fluid in the gaseous state into the duct 13, under pressure, and from there into the chamber 2. In this case, the transfer is carried out by opening the valve member 5A (as in the case of a gravity transfer) and the member 13A.

In this case also, the fluid is transferred towards the chamber 1 without being subjected to the action of moving mechanical members such as those of a pump, a screw, or the like.

When the chamber 1 has been filled to a predetermined level (monitored and determined by the usual sensors present in the chamber) , the valve member 5A is closed and the cryogenic fluid is introduced into the chamber 1 by opening the valve member 7A. The cryogenic fluid, in the liquid state and under pressure, enters the chamber 1, contacts the multiphase fluid and cools it.

The introduction of cryogenic fluid continues until the multiphase fluid has reached the desired temperature.

The cooling of the multiphase fluid causes the cryogenic fluid to enter the gaseous state, thus pressurizing the chamber 1 and causing a gas under pressure to flow out of it through the ducts 8 and 10, this gas acting as a motive fluid for the Venturi tube 3 in such a way that a partial vacuum is created, through the duct 12, in the loading chamber 2, reaching a level such that this chamber can draw in the multiphase fluid through the duct 4, by a process similar to that described above.

The duct 9, provided with a shut-off and regulation valve member 9A, serves to allow excess gas to flow to the outside if necessary, to maintain the optimal pressure in the refrigeration chamber during the refrigeration stage.

When the fluid to be refrigerated has reached the required temperature, the duct 7 is closed by means of the valve member 7A, and, at the same time, the valve member 1OA is closed, if it has not already been closed for the correct control of the filling of the chamber 2, and the member 9A is positioned in a specific way to set the pressure of the fluid in the chamber 1 at suitable levels to enable the fluid to be transferred from the aforesaid chamber 1 to another destination by means of the line 6.

When the pressure in the chamber 1 has reached a suitable level for transfer, the valve member 6A is opened; the multiphase fluid is thus driven, by the pressure present in the chamber 1 generated by the cryogenic fluid (or working fluid) , into the duct 6 and is transferred towards a further processing station.

In this case also, therefore, the (cooled) multiphase fluid is transferred solely as a result of the pressure present in the chamber 1, without being subjected to any mechanical action such as that of a pump or the like.

When all the multiphase fluid has been transferred into the duct 6, and after the total or partial emptying of the latter if necessary, the valve member 6A is closed and the member 9A is opened in such a way that the chamber 1 is then at atmospheric pressure and can receive the multiphase fluid to be refrigerated from the chamber 2 into which it had been loaded during the preceding stage of cooling in 1.

Thus the full treatment cycle, that is to say the refrigeration and movement, of the multiphase fluid continues as described above.

Clearly, the operation of the invention is made possible by the fact that the treatment of the multiphase fluid in the refrigeration chamber 1 takes place under pressure, and therefore, because of the pressure present in this chamber, the gas flowing out of it and sent into the Venturi tube 3 has a suitable energy content to be used as a motive fluid for the Venturi tube.

Operating the refrigeration chamber 1 at a pressure greater than atmospheric pressure also increases the refrigerating capacity by comparison with the case in which operation takes place at atmospheric pressure with the same geometrical characteristics, especially as regards the cross section through which the gas passes as it flows out of the refrigeration chamber 1. This is easily understood if it is considered that the refrigerating capacity of a given refrigerator using heat exchange by direct contact between fluids, one of which is an evaporant, is evidently a function of the quantity of refrigerant fluid supplied, this fluid being converted into a gas as a result of the heat exchange and passing through the chamber at a velocity dependent on the passage cross section and the quantity supplied.

For correct operation, for example in order to avoid the entrainment of some of the fluid being treated, this velocity must not exceed specified levels which depend on the nature of the fluid to be refrigerated and of the refrigerant fluid, especially its density.

By operating at pressures greater than atmospheric pressure, therefore, the density of the gaseous state increases, making it possible, by providing a suitable combination of velocity and density, to use higher flow rates of refrigerant fluid without causing the entrainment of the refrigerated fluid; that is to say, greater refrigerating capacity is achieved by comparison with the case of operation at atmospheric pressure.

In other words, and expressed in a simplified form, an increase in the working pressure, for the same flow velocity, provides a higher flow rate of the cryogenic fluid used, that is to say a greater refrigerating capacity. Clearly, therefore, the result achieved in the above way makes it possible to construct equipment of smaller dimensions, thus saving space and materials.

Thus the method according to the invention is applied by initially filling the loading chamber 2 and carrying out successive cycles, repeated in time, in each of which the multiphase fluid is sent into the chamber 1 and the working (cryogenic) fluid is then sent into the chamber .

The cycle, repeated in time, is thus composed of the following stages:

A- transfer of the fluid to be refrigerated from the loading chamber 2 to the refrigeration chamber 1, B- heat exchange in the refrigeration chamber 1, causing the cooling of the fluid to be refrigerated and, preferably, the simultaneous formation of the vacuum in the loading chamber 2 and the loading of the latter with the fluid to be refrigerated,

C- discharge and transfer of the refrigerated fluid from the refrigeration chamber 1 through the duct 6, D- repetition of the cycle from stage A.

The invention yields considerable benefits in all cases in which the fluid, which may be multiphase, cannot withstand mechanical stress or impact, or in cases in which it contains solid components which might cause excessive wear on the pumping systems used or even make them unusable.

For example, if the fluid originates from harvested grapes, the present invention makes it possible to move the crushed grapes in any direction without the aid of the conventional moving systems such as various types of pump with moving mechanical parts in direct contact with the crushed grapes. Furthermore, with the possible exception of the chambers 1 and 2 between which the crushed grapes may be transferred by gravity, there is no need for the equipment proposed by the invention to place the machinery used for the overall grape processing at specific positions or heights, thus making it possible to construct a whole system with a performance similar to that which would be obtained with a wine processing plant constructed to use the force of gravity, without the need to place the components at suitable heights. Moreover, it is evident that the invention can also be used solely for the purpose of transferring the multiphase fluid, or for the controllable removal of gases which are soluble in the fluid, a non-limiting example of such a process being the total or partial removal of dissolved oxygen. This can be done, for example, by using an oxygen-free gas or mixtures of gases (such as mixtures composed of N₂, H₂, Ar or CO₂) as the removal fluid in the refrigeration chamber 1.

In this case, the working fluid used in the refrigeration chamber 1 does not have to have refrigerating properties, and can therefore be any gaseous substance, provided that its composition is compatible with the removal of the desired dissolved gas, or can be any gaseous substance, including air, if the only requirement is to move the multiphase fluid.

If the fluid to be treated, that is to say refrigerated and/or moved, is characterized by high levels of viscosity and/or density, it is possible to introduce an additional quantity of refrigerant fluid or gas into the duct 6, before or during discharge, by means of the duct 14 with the valve member 14A opened, in order to promote the transfer of the multiphase fluid.

Because of this arrangement, the introduction of said additional fluid or gas into the duct 6 makes the multiphase fluid compressible, that is to say it imparts elasticity, thus permitting a continuous exchange of kinetic and potential energy, that is to say between pressure and velocity, and facilitating the flow of this fluid in the transfer duct.

Said refrigerant gas or liquid can be injected either directly into the duct 6, at a plurality of points if necessary, or into the part of the refrigeration chamber 1 adjacent to the duct 6, in such a way that the refrigerant gas or fluid is entrained into the transfer duct 6.

In a further procedure which is also possible with the invention shown in Figure 1 and which is useful for optimising the flow, a quantity of driving gas is made to flow from the refrigeration chamber 1 into the duct 6 at the end of each discharge of the chamber, in such a way that, when the refrigeration chamber 1 is next discharged, the fluid entering the duct 6 encounters a space which is partially or completely filled with gas, thus limiting the pressure level required to initiate the movement of the fluid contained in the aforesaid duct .

A variant of the invention is shown in Figure 2, where parts identical or corresponding to those of Figure 1 are indicated by the same reference numerals. In Figure 2, the refrigeration chamber (indicated by 1 in Fig. 1) and the loading chamber (indicated by 2 in Fig. 1) form a single chamber 21 connected to the duct 4 for the fluid, for example a multiphase fluid, to be treated, and to the duct 7 for the working fluid, for example a cryogenic fluid. The duct 6 which removes the treated fluid from the chamber 21, and the duct 8 which removes the working fluid in the gaseous state, both run from the chamber 21.

The Venturi tube 3 receives the motive fluid from the duct 10 which is connected to a source of motive fluid (such as compressed air) .

The invention shown in Figure 2 uses a single chamber 21 into which the fluid to be treated is initially loaded by using the partial vacuum created in the chamber by the Venturi tube 3; the fluid is then refrigerated and transferred to the outside of chamber 21, using the refrigerant fluid for the refrigeration and using the gaseous state of the refrigerant fluid for the formation of the internal pressure in this chamber 21 which is required for the aforesaid transfer to the outside by means of the duct 6.

Clearly, the above arrangement can also be used solely to move the fluid to be treated, where there is no need to refrigerate it; in this case, it is sufficient to use a gas to create the internal pressure in the chamber 21 required for the transfer.

The invention makes it possible to provide treatment, by refrigeration and/or movement, of a fluid which may be multiphase, in which the fluid is not subjected to contact with moving mechanical parts; in the case of a fluid containing both a liquid and a solid component

(as in the case of crushed grapes) , this prevents the crushing of the solid component, particularly the pips, which would cause undesired substances to leak out of them and consequently damage the end product.

Claims

1. Method for cooling and/or moving a fluid, for example a multiphase fluid, said fluid being present in its own storage reservoir and being introduced into a loading chamber (2, 21) and being subsequently subjected to the action of a different working fluid in order to refrigerate and/or move it, characterized in that a pressure drop is created in the loading chamber

(2, 21) to draw thereinto the multiphase fluid from the reservoir, this fluid then being refrigerated, by the supply of a cryogenic working fluid, in such a way as to generate, in said chamber, a pressure such that the multiphase fluid can be transferred subsequently towards a further use, the movements of said fluid from the reservoir and towards the further use being therefore obtained without movable mechanical parts contacting said fluid.

2. Method according to Claim 1, characterized in that the pressure drop in the fluid to be treated is generated in the loading chamber (2, 21) .

3. Method according to Claim 1, characterized in that the pressure drop in the fluid to be treated is generated in a treatment chamber (1) which is different from the loading chamber, a cryogenic fluid for refrigerating the fluid to be treated being introduced into said treatment chamber (1), said cryogenic fluid being under pressure.

4. Method according to Claim 3, characterized in that a fluid in the gaseous state and under pressure is introduced into the treatment chamber (1), said fluid under pressure being preferably introduced at a plurality of points of the treatment chamber (1) .

5. Method according to Claim 1, characterized in that the fluid to be treated is transferred by falling, that is to say by gravity, from the loading chamber (2) to the treatment chamber (1) .

6. Method according to Claim 1, characterized in that the fluid to be treated is transferred from the loading chamber (2) to the treatment chamber (1) by being driven by a fluid under pressure, said fluid under pressure being a gaseous fluid directly introduced into the loading chamber (2) .

7. Method according to Claim 1, characterized in that the working fluid flows out of the treatment chamber (1) and is used to create the pressure drop in the loading chamber (2) so as to draw thereinto the fluid to be treated.

8. Method according to Claim 1, characterized in that provision is made to send a fluid in the gaseous state to a Venturi tube (3) connected to the loading chamber (2) to create the pressure drop therein, the working fluid flowing out of the treatment chamber being sent into the Venturi tube (3) connected by means of a duct (12) to said loading chamber (2), the passage of said fluid within said Venturi tube (3) causing a pressure drop in said duct (12) and in the above mentioned loading chamber (2) connected to the reservoir of the fluid to be treated through a duct

(4) .

9. Equipment for treating a fluid, for example a multiphase fluid or a fluid containing agglomerated fluids, said fluid to be treated being contained in a reservoir connected to a loading chamber (2, 21) into which it is introduced before being subjected to the action of a working fluid, characterized in that there are provided draw-off means (3) for creating a pressure drop in said chamber (2) to draw thereinto the fluid to be treated from its reservoir, and drive means for generating a pressure in the fluid to be treated such that the fluid can be subsequently transferred towards a further use, said draw-off and drive means thus moving the fluid to be treated without movable mechanical parts contacting said fluid.

10. Equipment according to Claim 9, characterized in that the draw-off means are a Venturi tube (3) , preferably soundproof, connected to the loading chamber (2, 21) by means of a duct (12), a gaseous or motor fluid being sent into said tube to create the pressure drop in said duct (12) and thus in said chamber (2, 21), said Venturi tube being connected to an inlet duct (10) wherein the gaseous or motor fluid flows.

11. Equipment according to Claim 10, characterized in that said inlet duct (10) is connected, by way of a duct (24), to a source of motor fluid under pressure.

12. Equipment according to Claim 10, characterized in that said inlet duct (10) is connected to at least a further duct (8) and, through this duct, to at least a treatment chamber (1) to which the fluid to be treated flows from the loading chamber (2), a working fluid under pressure being introduced into said treatment chamber (1) to form the drive means for subsequently moving the fluid to be treated, said working fluid flowing out of said treatment chamber (1) being directed into said inlet duct.

13. Equipment according to Claim 12, characterized in that the working fluid is a cryogenic fluid flowing, under pressure, from its own reservoir and supplied through a duct (7) provided with regulating valve members (7A) to said treatment chamber (1), said treatment chamber (1) being connected to an outlet duct (8) forming said further duct connected to the inlet duct (10) of the Venturi tube (3) and to a transfer duct (6) to transfer the fluid to be treated to a further use.

14. Equipment according to Claim 13, characterized in that the transfer duct comprises at least a portion (6K) with variations of height (15) .

15. Equipment according to Claim 12, characterized in that the treatment chamber (1) is placed at a level below the loading chamber (2) so that the fluid to be treated can pass from the latter to the former by means of gravity.

16. Equipment according to Claim 12, characterized in that the loading chamber (2) is connected to a source of fluid under pressure by means of a corresponding duct (13) for driving the fluid to be treated into the treatment chamber (1) .

17. Equipment according to Claim 9, characterized in that the loading chamber (2) is also a treatment chamber (1) for the fluid to be treated.

18. Equipment according to Claim 10, characterized in that the motor fluid sent to the member (3) is drawn from an outside source at a suitable pressure.

19. Equipment according to Claim 13, characterized in that the outlet duct (8) and the transfer duct (6) run from the treatment chamber at different heights from the latter.