EP0115452A2 - Installation for producing a hot fluid by recovering waste heat from a refrigerator - Google Patents

Abstract

1. Apparatus for producing a heated liquid, such as water supplying apparatus which consumes this liquid such as a warming tank (1), in which the liquid is heated by recycling at least the superheating heat from the vapour of a refrigerant which, to this end, after emerging from the compressor (5) and before returning to the condenser (7) of refrigerating apparatus (2) is diverted towards a main heating station (28) which contributes to the raising of the temperature of the liquid to be heated, which is tapped from at least one source (36) then heated and stored in a reservoir (43) before being sent to the apparatus (1) which consumes it via a distribution means (34) and/or being sent to the entrance to the main station (28) via a channel (44) by passing through a circulator (47), the apparatus for producing a heated liquid being characterised in that : - on the route taken by the liquid to be heated, the apparatus comprises, in addition to the main heating station (28) and upstream therefrom, a pre-heating station (18) comprising a supplementary exchanger (14) which, on the route of the vapours of the refrigerant, is mounted in series with the exchanger (13) of the main heating station (28) ; - the source (36) which re-supplies the apparatus with liquid to be heated is connected to the entrance of the pre-heating station (18) ; - in order to control the divertion of the refrigerant liquid towards at least one of the primary exchangers of the main heating station and the pre-heating station, a plurality of solenoid valves (15, 16) are provided ; - each of the exchangers (13, 14) known as primary, because they are passed through by the refrigerant liquid, penetrates into an enclosure (17, 18) which receives a certain volume of liquid (19, 20) such as water which is only an intermedary liquid between the refrigerant liquid and the liquid to be heated, the apparatus also comprising for the route of this liquid two secondary exchangers (21, 22) which, to this end, also penetrate respectively into one of the enclosures (17, 18).

Description

The invention relates to an installation for producing a fluid, such as in particular water, which is heated by recovering at least the superheating heat from the vapor of a refrigerant before it returns to the condenser of a refrigeration system.

It is indeed common for heating, particularly water, and product refrigeration needs to arise simultaneously.

For example, in a poultry slaughterhouse, prior to a phase during which the said poultry will be plucked, these must generally be immersed in a scalding tank filled with water at about fifty-one degrees celsius whereas, after this phase during which they will have been plucked, these poultry should otherwise be frozen, at least be cooled to about three degrees celsius above zero.

Thus, such a slaughterhouse must have both refrigeration facilities for cooling poultry and heating facilities for the water in the scalder, which water, for obvious health reasons, must also be constantly replenished.

When such refrigeration and heating needs arise simultaneously, it appears advantageous to use the heat extracted from the products cooled in the refrigeration installation in order to heat the water in the heating installation.

In conventional refrigeration systems, the heat is extracted from the products by means of the refrigerant which, by vaporizing at low temperature in an evaporator, absorbs the heat available in the enclosure housing the cooled products and the evaporator .

After its complete vaporization, the refrigerant is then, by a compressor, brought to a relatively high pressure ensuring its circulation and incidentally its reheating, after which, the compressed gas obtained is brought to a condenser in which, by condensation, the refrigerant is returned to the at least part of its heat to a cooling agent such as air.

Obviously, by cooling, the refrigerant returns from the gaseous state to the liquid state and it can then, after passing through a pressure reducer, be brought back to the evaporator for a new circuit.

From such a conventional installation, it is already known to recover the heat thus extracted by the vaporization of the refrigerant, and this, by acting either upstream of the condenser, or during its passage through the condenser (FR-A-2.346 .644).

Obviously, on the one hand, the operating cycle of the refrigeration system and that of the hot water demands do not necessarily match and, on the other hand, the refrigeration system cannot be stopped or started depending on the only heating needs; Also, to make up for the inadequacies of the recovery possibilities, conventional means of auxiliary heating are generally necessary but, if not to cancel, at least to strongly limit the use, of such an auxiliary heating encumbering the cost price, the recovery facility must be efficient enough.

• - tant au plan des moyens de récupération qui doivent pouvoir prélever un maximum de chaleur mais pas trop pour ne pas nuire au fonctionnement du condenseur, par exemple, par une pré-cnndensation du frigorigène,
• - qu'au plan des moyens en vue de stocker l'eau chaude tout en lui conservant sa chaleur.

For this, such a hot water production installation by recovery must be effective:

• - both in terms of recovery means which must be able take a maximum of heat but not too much so as not to harm the operation of the condenser, for example, by a pre-cnndensation of the refrigerant,
• - that in terms of means for storing hot water while retaining its heat.

In addition, the installation must also be able to respond quickly to a very significant need for hot water and in all cases to provide quality water and in particular protected from any contamination by the refrigerant even in the event of failure such as a leak of his circuit.

A result that the invention aims to obtain is an installation which allows to take a maximum of heat but not too much so as not to harm the proper functioning of the condenser and to store hot water while retaining its heat.

Another result which the invention aims to obtain is an installation which makes it possible to quickly respond to a very significant need for hot water and to supply in all hypotheses quality water and in particular protected from any contamination by the refrigerant.

To this end, it relates to an installation of the type mentioned above, in particular characterized in that, at the outlet of the storage tank, a water return pipe is connected to the inlet of the exchanger.

• - figure 1 : une vue d'ensemble de l'installation,
• - figure 2 : une vue en perspective de l'échangeur principal,
• - figure 3 : une vue en coupe d'un échangeur annexe.

It will be clearly understood with the aid of the description below, given by way of nonlimiting example, with reference to the attached drawing which schematically represents:

• - Figure 1: an overview of the installation,
• - Figure 2: a perspective view of the main exchanger,
• - Figure 3: a sectional view of an annex exchanger.

Referring to the drawing, we see that the installation serves at least one equipment 1 consuming hot water, such as a scalding tank, and at least one equipment 2 for producing cold, such as a refrigeration cabinet, by evaporation of a refrigerant in an evaporator 3.

In known manner, at the outlet of the evaporator, the vapors are conducted by a pipe 4 to a compressor 5 which carries them at relatively high pressure.

After possible passage through an oil separator, the compressed gas is, by a pipe 6, brought to a condenser 7 in which, by condensation, it returns at least part of its heat to a cooling agent 8 such as air.

From the gaseous state, the refrigerant returns to the liquid state and a line 9 then leads to a pressure reducer 10 before, via a line 11, it returns to the evaporator 3 for a new circuit.

In order for the water 12 supplied to the scalding tank 1 to be heated by recovering the superheating heat from the vapor of the refrigerant which normally circulates from the compressor 5 to the condenser 7 via the line 6, this vapor is diverted to at least the main exchanger 13 in series with which an annex exchanger 14 is mounted.

This bypass takes place under the control of solenoid valves 15, 16.

Each exchanger 13, 14 enters an enclosure 17, 18 which is filled with a certain volume of an intermediate fluid 19, 20, such as water, which in closed circuit, is set in motion so that only after having passed through the exchanger 13, 14, traversed by the refrigerant vapors, this intermediate fluid can pass through a secondary exchanger 21, 22 which, for this purpose, also enters the aforementioned enclosure 17, 18 and which, for its part, is traversed by the fluid to be heated, such, in the example shown, the water which will feed the scalding tank 1.

Thanks to this arrangement, even in the event of a refrigerant leak, it could only mix with the intermediate fluid. The disturbance which would then result in the refrigerating machine, would be immediately detected and the leak could therefore always be repaired before the secondary exchanger is itself attacked and the fluid to be heated is contaminated.

Obviously, in the case where the final fluid is not "edible", the use of the intermediate fluid could be neglected and this would reduce the cost price. Thanks to the closed-circuit circulation of the intermediate fluid, it is already a hot fluid which is passed back the main exchanger or annex 13, 14 and, as a result, this fluid quickly reaches a high temperature.

Pl _'us, this fluid removal once and for all its limestone and, therefore, no reason to fear the disadvantages associated with scaling.

The intermediate fluid can be set in motion by natural convection or by a circulation pump 23 interposed in a circuit 24 for the return of the secondary exchanger 21.

The main exchanger 13 (FIG. 2) is advantageously composed of several elements 25 each housed at the bottom of one of the cells 26 which the enclosure 17 has for this purpose. At the entrance to each of the cells 26, under the control solenoid valves, the intermediate fluid is distributed between the only elements 25 in which the refrigerant vapor is at sufficient temperature.

At the outlet of the elements 25, the enclosure has walls 27 capable of grouping the intermediate fluid of the various cells to lead it to the inlet of a compartment 28 housing the secondary exchanger 21. It is at the outlet of this compartment 28 that the return line 24 housing the circulation pump is connected.

The quantity of intermediate fluid circulating through this main exchanger will preferably be relatively large and for example of about one thousand two hundred liters to offer good thermal inertia which places both the water and the refrigerant away from sudden changes in temperature.

The annex exchanger 14 (FIG. 3) also includes several elements 29 arranged near the base of the enclosure 18. Heated by the elements 29, the intermediate fluid 20 tends to rise by natural convection to the top of the enclosure which has a shape, for example substantially in a heap of stones, capable of causing the movement of the intermediate fluid 20 to accelerate.

Arrived at the top of the enclosure, this intermediate fluid falls behind lateral partitions 30 that said enclosure presents for this purpose.

Behind these partitions are mounted the elements 31 of the secondary exchanger 22 on which the intermediate fluid then flows before returning to the base of the enclosure for a new circuit.

The quantity of intermediate fluid flowing through this annex exchanger 14 will be for example from six hundred to seven hundred liters.

As can be seen from FIG. 1, as soon as they exit at approximately ninety-five or one hundred degrees celsius, the refrigerant vapors pass through the main exchanger 13 from which they emerge at approximately fifty or seventy degrees celsius to pass this time 'Annex 14 exchanger and come out at around forty degrees Celsius before returning to the condenser.

• - l'échangeur annexe 14 concourre au préchauffage de l'eau qui de dix ou douze degrés celsius environ est portée à environ vingt cinq ou vingt huit degrés celsius alors que,
• - l'échangeur 13 concourre au chauffage final de l'eau qui, par exemple, de vingt cinq ou vingt huit degrés celsius est portée à cinquante ou soixante degrés celsius.

In this assembly, via their intermediate fluid 19, 20:

• - the exchanger annex 14 contributes to the preheating of the water which by ten or twelve degrees celsius approximately is brought to approximately twenty five or twenty eight degrees celsius whereas,
• - the exchanger 13 contributes to the final heating of the water which, for example, from twenty five or twenty eight degrees celsius is brought to fifty or sixty degrees celsius.

The maximum of the superheat heat and the latent heat of the vapor is thus recovered and. used to heat water without the condenser having to suffer from too great a drop in temperature as would be the case if, instead of two successive exchangers, there was a single more powerful exchanger, collecting in one times a significant part of the superheat heat.

In order to remain available in large quantities and at times which do not necessarily correspond with the periods of operation of the refrigerating machine, the water thus heated must of course be stored.

To this end, at the outlet of the secondary exchanger 21 of the main heating station 28, the heated water is, by a pipe 32, led to a tank 43, for example of twenty thousand liters, at the outlet of which a pipe 33 leads to a network 34 distributing water under the control of solenoid valves 35.

The entire installation is connected to a water source, such as a distribution network, by a pipe 36 also controlled in particular by solenoid valves 37 and means 38 for regulating the pressure.

This inlet pipe 36 is connected to one end of the secondary exchanger 22 of the preheating station 18, the other end of which is itself connected by a pipe 39, to the inlet of the secondary exchanger 21 of the main station of heating.

The preheating station can be short-circuited by a pipe 40 controlled by a three-way motorized valve 41 controlled by a temperature probe 42 immersed in the intermediate fluid 20 of the preheating station 18. At the outlet of the storage tank 43 is also connected a water return pipe 44 to the inlet of the secondary exchanger 21 of the main heating station 28, which return takes place in particular under the control of valves or solenoid valves 45 and of a non-return valve 46 as well as under the possible control of a circulation pump 47. The reservoir is divided into compartments 48, 49, 50 by partitions 51, 52 leaving only a narrow passage 53, 54 between the adjoining compartments.

For each compartment, the inlet and outlet of the fluid are located opposite one another, one at the bottom, the other at the top of the tank to create a baffle. In each compartment 48, 49, 50, a probe 55, 56, 57 for measuring the temperature is immersed.

In the first compartment 48 plunges a pipe 58 for withdrawing the fluid to bring it back to the secondary exchanger 22 of the main station 28 of the heating either directly or via the above-mentioned pipe 44.

Therefore, during the refilling of the installation, it is possible to recycle only the first compartment until it reaches the temperature of the following, which avoids cooling the water of the following compartments by a passage from one to the other.

• - le matin, une horloge jour-nuit/hebdomadaire avec réserve de marche ouvrira les électrovannes 37 d'arrivée d'eau de ville et 35 de sortie de cuve de stockage 43. Le bac échaudoir se remplira alors avec l'eau qui était stockée dont la température est d'environ cinquante degrés celsius. Automatiquement, un chauffage d'appoint, tel une chaudière au fuel ou des résistances électriques, se mettra en marche pour porter cette température de l'eau à celle souhaitée soit, dans cet exemple, à cinquante et un degrés celsius. Evidemment, l'installation de récupération est dimensionnée de manière à limiter au maximum sinon annuler totalement le recours à ce chauffage d'appoint. De ce fait, dans l'exemple précité, l'installation de récupération tend à porter l'eau à cinquante cinq degrés celsius soit légèrement au dessus de la température souhaitée. Eventuellement, les horloges pourront avoir pour mission de shunter les thermostats des installations frigorifiques afin de les faire fonctionner au moment où il y a une forte demande en eau.
• - pendant le travail, au travers des échangeurs et de la cuve de stockage 43, le bac échaudoir sera alimenté par de l'eau de ville à raison d'environ trois mille litres par heure. Cette alimentation pourra, par exemple, être gérée pour un flotteur.
• - le soir, le poste principal de chauffage et la cuve de stockage fonctionneront en circuit fermé. A cet effet, les électrovannes 37 d'arrivée d'eau de ville seront fermées. L'eau de la cuve de stockage 43 sera alors constamment recyclée ce qui lui permettra de récupérer les calories et de monter en température.

In a poultry slaughterhouse benefiting from such an installation, the water heating process will be by the following example:

• - in the morning, a day / night / weekly clock with power reserve will open the solenoid valves 37 for city water supply and 35 for storage tank outlet 43. The scalding tank will then fill with the water that was stored whose temperature is around fifty degrees celsius. Automatically, a backup heater, such as an oil boiler or electric resistances, will start to bring this water temperature to that desired, in this example, to fifty-one degrees Celsius. Obviously, the recovery installation is dimensioned so as to limit as much as possible if not completely cancel the use of this auxiliary heating. Therefore, in the above example, the recovery installation tends to bring the water to fifty five degrees Celsius, slightly above the desired temperature. Eventually, the clocks may have the task of shunting the thermostats of the refrigeration installations in order to operate them at a time when there is a high demand for water.
• - During work, through the exchangers and the storage tank 43, the scalding tank will be supplied with tap water at the rate of approximately three thousand liters per hour. This supply could, for example, be managed for a float.
• - in the evening, the main heating station and the storage tank will operate in a closed circuit. To this end, the city water inlet solenoid valves 37 will be closed. The water in the storage tank 43 will then be constantly recycled, which will allow it to recover the calories and increase the temperature.

The closed circuit could of course, instead of a clock, be obtained by action on a manual control in particular if it is difficult to predict the time of end of the use of the scalding tank.

This bet. in a closed circuit will cause the circulation pump to start only with a delay of fifteen to thirty minutes.

In the closed circuit position, the installation will be controlled by a differential regulator: information on the temperature will be taken at the inlet of the secondary exchanger and at the storage tank; the two items of information will be compared and the circulation pump stopped if the temperature of the storage tank is greater than or equal to that of the main heating station. The regulator will not restore the operating order to the pump unless the temperature of the storage tank becomes lower than that of the main heating station.

In the event of a prolonged shutdown, at noon for example, the installation can be operated in the same way as for the evening.

Claims (7)

1. Installation for producing a hot fluid, such as water supplying an installation consuming this fluid such as a scalding tank (1), in which installation the fluid is heated by recovering at least the superheating heat of the steam a refrigerant which, for this purpose, after its exit from the compressor (5) and before its return to the condenser (7) of a refrigeration installation (2) is diverted to the exchanger (13) of a main station of heating (28) which contributes to the rise in temperature of the fluid to be heated which is taken from at least one source (36) then heated and stored in a tank (43) before being sent to the installation (1) consuming it via a distribution means (34), this installation for producing a hot fluid being CHARACTERIZED in that, to control the bypass, solenoid valves (15, 16) are provided and in that, at the outlet of the storage tank (43 ), is connected a pipe (44) for returning the water to the inlet of the exchanger in passing through a circulator (47). 2. Installation according to claim 1 characterized on the one hand, in that the reservoir is divided into compartments (48, 49, 50) by partitions (51, 52) leaving only a narrow passage (53, 54) between the adjoining compartments, and, on the other hand, in that, for each compartment, the inlet and outlet of the fluid are located opposite one another, one at the bottom, l other at the top of the tank to create a baffle. 3. Installation according to claim 1 or 2, characterized in that, in the first compartment (48), plunges a pipe (58) for withdrawing the fluid to return it to the exchanger of the main station (28) of the heating. 4. Installation according to any one of claims 1 to 3, characterized in that on the path of the refrigerant vapors, in series with the exchanger (13) of the main heating station (28), is mounted an annex exchanger ( 14). 5. Installation according to any one of claims 1 to 4, the exchanger (13, 14) through which the refrigerant penetrates into an enclosure (17, 18) which receives a certain volume of a fluid (19, 20) like water, characterized in that this fluid is only an intermediate fluid between the refrigerant and the fluid to be heated for the path of which the installation comprises a secondary exchanger (21, 22) which for this purpose penetrates also in the said intermediate fluid. 6. Installation according to any one of claims 1 to 5, characterized, on the one hand, in that the main exchanger (13) is composed of several elements (25) each housed at the bottom of one of the cells (26) that presents for this purpose the enclosure, and, on the other hand, in that it comprises at the entry of each of the cells (26), solenoid valves controlling the distribution of intermediate fluid between the only elements ( 25) in which the refrigerant vapor is at a sufficient temperature. 7. Installation according to any one of claims 1 to 6, characterized in that the annex exchanger (14) comprises several elements (29) arranged near the base of the enclosure (18), and internally has side partitions (30) giving it a shape capable of causing the acceleration of the upward movement of the intermediate fluid which, reaching the top of the enclosure, falls behind said side partitions (30) where the elements (31) of the exchanger are mounted secondary 22).

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