EP0145515B1 - Fluid heating installation comprising an absorption heat pump associated cycle - Google Patents

Abstract

The invention pertains to improvements brought to a heating facility which includes an associated absorbing heat pump cycle. The facility is designed for direct thermosiphon heating of the absorption solution to be regenerated upon contact with a panelling (15) which surrounds the combustion chamber (9). The separation of the solution to be regenerated is performed inside a separation column (14) which is connected to a dephlegmator (16) which improves the yield of the separation, the yield of the absorbing cycle and the recovery yield of heat supplied by the burner. Furthermore a heat exchanger (8) enables the operation of the facility with a de-activation of the absorbing cycle. The invention applies especially to central heating and to the heating of hygienic water.

Description

The present invention relates to improvements in a heating installation equipped with an absorption heat pump.

In certain installations for heating a fluid, such as for example water, in particular for heating buildings and producing domestic hot water, installations comprising at least one solid, liquid and / or gaseous fuel burner producing smoke at a relatively high temperature, an absorption heat pump is sometimes used to improve the thermal efficiency of the heating.

In such a case usually, the burner is used to boil the absorption solution used in the absorption cycle of the heat pump so as to separate the constituents of the solution and regenerate the absorption fluid used in the cycle.

At the level of the heat exchange of smoke / absorption solution to be regenerated, the efficiency is poor because, taking into account the conditions of the heat exchange, the smoke leaves the installation at a generally high temperature above 200 ° C causing large amounts of energy to be lost through the chimney.

In most cases this unfavorable situation is tolerated because at the heat pump cycle, we recover in the ambient environment at the cycle evaporator much more energy than we let escape from the chimney, so that the overall performance of the installation appears relatively good. However, this is only true if the operating conditions of the evaporator are satisfactory, that is to say generally if the level of the "cold source" into which the heat delivered to the installation is "pumped" is high enough. This well-known phenomenon leads the installers to install in parallel on the heating installation equipped with a heat pump a boiler of conventional type which will directly heat the fluid to be heated when the operating conditions of the cold source are unfavorable. (generally in cold weather more particularly if the evaporator borrows its heat from the ambient air).

• 1) Le surcoût de l'installation que leur utilisation entraîne n'est pas du point de vue économique rentable;
• 2) l'aménagement de circuits d'échange, nécessitant de longues dimensions de canalisations fait qu'on reperd par pertes en ligne dans ces canalisations la plus grande partie de la chaleur que l'on a tenté de récupérer.

In order to reduce the heat losses to the chimney, it has also been proposed to have heat recovery exchangers on the smoke circuit, which recovery heat exchangers will be in heat exchange with the fluid to be heated. In practice, however, these exchangers are not satisfactory, essentially for the following two reasons.

• 1) The additional cost of the installation that their use entails is not economically profitable;
• 2) the arrangement of exchange circuits, requiring long dimensions of pipes, means that most of the heat that we have tried to recover is lost by losses in line in these pipes.

In the previous patent application EP-A-0110 763 (published on 13.06.84) by the same applicant, an improved installation has been proposed which makes it possible to solve some of the difficulties exposed.

To this end, in this previous application, the heat exchanger comprises two stages arranged in series, the first forming a heat pump boiler serving to bring the absorption solution to the appropriate temperature, the second forming a recuperator serving to heat the fluid of heating in the vicinity of its entry into the installation. The two exchangers are constituted in an original way by two twin tubes arranged in series, the inner tube of the two twin tubes serving as an outlet passage for the fumes produced in the combustion chamber of the installation. In addition, a connection is provided at the level of the first exchanger at the place where the solution to be regenerated leaves this exchanger after heating, this connection opening into a separator flask in which the separation of the volatile enriched solution and the depleted solution takes place. heavier for the use of these two separate solutions in the absorption cycle of the installation.

The present invention uses the general principles of this earlier application to which it provides specific improvements, more particularly in terms of the heating device for the boiler of the heat pump and for the recovery of the heating fluid while ensuring much more implementation. "Efficient" and greater flexibility of use.

• - recevant les retours de la solution d'absorption à régénérer avant leur introduction dans une colonne de séparation formant le séparateur précité et qui est disposée juste au-dessus dudit chemisage, et
• - étant au moins partiellement encastrée dans la seconde chambre, laquelle communique directement avec le résidu présent à la base de ladite colonne par des conduits de large section favorisant une circulation fermée en échange thermique par thermosiphon dudit résidu autour de ladite chambre de combustion.

To this end, an installation for heating a fluid such as for example water, in particular for heating buildings and producing domestic hot water according to the invention, of the type comprising at least one burner with solid, liquid and / or gaseous fuel producing fumes at relatively high temperature and comprising a first heat exchanger forming the boiler of a heat pump and a second heat recovery exchanger placed in series with the first and serving to heat said fluid , said first heat exchanger communicating with a separator in which the separation of the "distillate" and the "residue" of the absorption solution to be regenerated is characterized in that said burner opens into a central combustion chamber in contact of which is disposed substantially annularly a liner divided by a wall into two contiguous chambers, the first chamber:

• receiving the returns of the absorption solution to be regenerated before their introduction into a separation column forming the aforementioned separator and which is arranged just above said liner, and
• - Being at least partially embedded in the second chamber, which communicates directly with the residue present at the base of said column by wide section conduits promoting closed circulation in heat exchange by thermosyphon of said residue around said combustion chamber.

For ease of expression and understanding of the text, the term "distillate" designates the more volatile part or "enriched" solution of the absorption solution after its regeneration and the term "residue" the heavier part constituting the solution "Depleted" of the absorption solution after its regeneration.

By operating in the manner indicated above, it is improved. considerably reduces the operating conditions of the installation because this not only improves heat recovery at the burner and for the benefit of the installation, but also increases the temperature of the absorption solution to be regenerated and simultaneously improve the efficiency of the separation, therefore the thermal efficiency of the absorption cycle, such a construction design, of simple technique naturally and automatically ensuring excellent homogeneous heating of the absorption solution to be regenerated directly at the level of the base of the separation column.

It should be noted that document US-A-2290532 describes an installation with a burner heating two chambers arranged one behind the other annularly to a combustion chamber, these chambers communicating respectively with the hot departures and the cold returns of a refrigeration cycle. However, this installation, which does not relate to a heating installation, neither shows nor suggests the particular compact, partly nested, arrangement of the chambers according to the invention, nor the circulation in thermosyphon with the boiler-separator of the heat pump and n ' the advantages of it. A somewhat comparable arrangement is also found in document US-A-2479062 in which the boiler of the refrigeration installation is formed annularly around a long tube of fumes.

• la figure 1 est un schéma d'ensemble d'une installation conçue selon l'invention,
• la figure 2 montre de façon plus détaillée une partie de l'installation comprenant le brûleur et la colonne de séparation,
• la figure 3 est une vue en coupe verticale montrant une des parties de l'installation constituant le «déflegmateur»,
• la figure 4 est une vue par dessus faite selon la flèche IV de la figure 3,
• la figure 5 montre de façon schématique en vue par devant avec arrachements partiels un mode de regroupement préféré des principaux organes de l'installation,
• la figure 6 montre en vue par dessus et schématiquement l'implantation des différents organes de l'installation visibles à la figure 5.

Other features and advantages of the invention will appear more clearly with the aid of the description which follows, given with reference to the appended drawings in which:

• FIG. 1 is an overall diagram of an installation designed according to the invention,
• FIG. 2 shows in greater detail a part of the installation comprising the burner and the separation column,
• FIG. 3 is a view in vertical section showing one of the parts of the installation constituting the "de-phlegmator",
• FIG. 4 is a top view taken along arrow IV of FIG. 3,
• FIG. 5 schematically shows in front view with partial cutaway a preferred method of grouping the main components of the installation,
• FIG. 6 shows in top view and schematically the location of the various members of the installation visible in FIG. 5.

Reference will first be made to FIG. 1 illustrating the overall diagram of an installation designed according to the invention.

According to this diagram, the installation essentially comprises the cycle of the absorption pump comprising the boiler-regenerator 1, the condenser 2, the holder 3, the evaporator 4, the absorber 5, a circulation pump 6 for the solution, a heat exchanger 7 and an additional exchanger 8.

The regenerator boiler 1 consists essentially of a burner with its combustion chamber 9 comprising two heat exchangers 10 and 11 respectively, consisting of two bitubes mounted in series, the inner tube 12 common to the two exchangers being traversed by the fumes produced in the combustion chamber 9 and which escape at 13 to the chimney (not shown).

The regenerative boiler 1 further comprises a separation column 14 which receives after their heating, in particular in the heat exchanger 10 and at the level of the part 20 of the lining 15 surrounding the combustion chamber 9, returns of the solution to be regenerated from the absorber 5. The regenerative boiler 1 also comprises a so-called de-phlegmator apparatus 16 which receives the distillates produced at the head of the separation column 14 with a view to their drying in order to improve the efficiency of the absorption cycle.

The installation being thus described as a whole, reference will now be made to FIGS. 2, 3 and 4 with the help of which some specific apparatus used in the installation will be described in more detail.

Referring first to Figure 2 we will describe the constitution of the burner 9 surrounded by its liner 15 in connection with the separation column 14.

The burner (not shown), the flame of which has only been shown diagrammatically at 16 ′, comprises a combustion chamber 17 surrounded by a liner 15. In the illustrated embodiment, the liner 15 is divided by a partition 18 into two chambers respectively 19 and 20. The chamber 19 is in communication by two pipes of relatively large section 21, 22 with the base of the column 14. In this way it is established under the effect of the heating which takes place in the combustion chamber 17 efficient circulation in thermosyphon of the solution to be regenerated present up to the level marked 23 in column 14. This gives good homogenization of the temperature of the solution to be regenerated in column 14.

Most of the lining 20 surrounding the combustion chamber 17 receives, as will appear more clearly below the returns of the absorption solution coming from the absorber 5 and after they have passed through the heat exchanger 10 in view of their admission via line 24 into column 14. In this way a more efficient and higher temperature heating of the absorption solution is obtained, improving the regeneration process of the quality on which the yield of the cycle largely depends. absorption.

As it appears in FIG. 2, the conduit 24 opens through its upper orifice 25 at substantially mid-height of the column 14, which comprises a number of baffles 26, 27, 28 forming simplified distillation plates in this column. Thus a more efficient separation is obtained between the “distillate” and the “residue” separated in this column from the absorption solution coming from the absorber 5. Thus also the entrainment by the distillate of residue fractions liquids in the form of fine droplets.

The liquid residue leaves the separation column through line 29 at the base of the column, while the distillate leaves at the top of the column through line 30.

Reference will now be made to FIGS. 3 and 4 to describe the construction of the "de-phlegmator".

The distillates leaving the column 14 through the conduit 30 enter the deflegmator 16 at the upper part of a volume 31 formed between the vertical circular cylindrical wall 32 of the dephlegmator 16, and a more internal concentric wall 33. Inside the volume 31 is also arranged a tubular helix 34 in which circulates as indicated by the arrows the fluid to be heated penetrating into the de-phlegmator via the conduit 35 and leaving it through the conduit 36 which forms the heating start of the installation .

The distillates introduced at 30 into the de-phlegmator are therefore channeled along a peripheral helical path descending against the current with the fluid to be heated traversing the propeller 34 and open towards the base of the apparatus in the volume marked 37. The distillates are thus subjected both a centrifugation effect and a refrigeration effect which tend to condense the entrained residue parts with the distillates and to separate them from the lighter distillates. Under these conditions, the condensed residues escape from the de-phlegmator through the conduit 38 located at the base of the apparatus while the distillates in gaseous form escape from the apparatus through the conduit 39, the outlet of which is placed at 40 in upper part of the appliance.

As it appears in FIG. 1, the separated residues collected at 38 in the de-phlegmator are returned to the separation column 14 towards the upper part of this column. In this way, the separation of the absorption solution into its light distillates and heavy residues is very markedly improved, which improves the functioning of the absorption cycle.

Referring now to Figures 5 and 6, we see a particularly efficient layout thermally and convenient in terms of compactness of the installation.

It can be seen that the separation column 14, the de-phlegmator 16, the heat exchangers 7 and 8 have all been housed inside the two twin-tube propellers constituting the heat exchanger 10 for the heat pump boiler and the heat exchanger 11 forming a heat recovery unit for the fluid to be heated. In this way, the heat exchanges in the installation are improved, all the “hot” exchangers being placed inside the two hot exchangers 10, 11.

The absorber 5 and the condenser 2 find their place outside the exchangers 10, 11, the entire installation, excluding the evaporator 4, which can thus be housed in an envelope forming an outer casing (not shown).

Referring now more particularly to FIGS. 1 and 5, the operation of the installation and the various circulation circuits will be described.

1) Circulation of distillates forming heat transfer fluid.

The distillates are produced as mentioned above in the separation column 14 from the absorption solution coming from the absorption column 5. The distillates escape at the top of the column 14 through the conduit 30 entering the de-phlegmator 16. After passing through the de-phlegmator which provides centrifugation and counter-current cooling with the fluid to be heated, the distillates rid of their "humidity" (the heavy parts of "residue" entrained being returned to column 14 through the conduit 38) are brought by the conduit 39 inside the condenser 2 cooled against the current by the fluid circuit to be heated in which the condensation takes place. The condensed distillates are then admitted via line 41 into the pressure reducer 3 in which their expansion and subsequent cooling takes place. They heat up in the evaporator 4 which can be an air exchanger exchanging heat with the ambient medium or for example water exchanging heat with waste water. It is at this device, as it is known that the heat is borrowed from the outside environment. The distilled distilled thus warmed at the outlet of the evaporator 4 penetrate through the conduit 43 at the top of the absorption column. In this column, the distillates are absorbed by the heavy residues brought by line 44 into the absorber and with which they mix, releasing heat, which is partly exchanged with the fluid to be heated as will be described below in relationship with this circuit. The mixing solution leaves the absorber via the conduit 45 from where it is taken up by the pump 6 to be brought back after crossing the heat exchanger 7 in counter current with the hot residues coming from the column 14, before entering in the exchanger 10 then the chamber 20 formed around the combustion chamber 17 before being introduced into the separation column 14 through the conduit 24.

2) Circulation of residues.

The residues of the absorption cycle leaving the base of the column 14 via the conduit 29 are brought by a circuit marked 46 in the exchanger 7 in counter-current with the solution to be regenerated which they heat. Then what residues pass through the conduit 47 in the additional heat exchanger 8 which is cooled against the current by the circuit of the fluid to be heated. At the outlet of the exchanger 8, the cooled residues penetrate via the conduit 44 at the head of the absorption column 5 to mix therewith the distillates brought to the column by the conduit 43.

3) Circulation of the fluid to be heated.

The cold inlet of the fluid to be heated which can constitute, for example, the cold returns of a central heating takes place at 48 at the end of the exchanger 11 by which the fumes 13 from the installation are evacuated. In 49 is shown the evacuation of condensates from the fumes, the temperature of the cold returns generally making it possible to recover at least a large part of the heat of condensation of the fumes.

At the outlet of the exchanger 11, the heating fluid gains via a conduit 49 the absorber 5, which allows optimal cooling of the condensates improving the working conditions of the absorption cycle. After the absorber 5, the heating fluid is brought through a conduit 50 into the heat exchanger 8, which in the normal operating position of the installation hitherto described makes it possible to recover extract some of the heat from the residues before entering the absorption column 5. At the outlet of the exchanger 8, the fluid to be heated gains via a conduit 51 the condenser 2 in which most of the the heat supplied by the absorption circuit. At the outlet of the condenser 2, the fluid to be heated gains via a conduit 52 the de-phlegmator 16 in which a final heating operation takes place, which allows, as described above, to improve the purification and the separation into light distillate. and heavy residue of the absorption solution at the outlet of the absorption column 5.

When the operating conditions of the absorption cycle are not favorable, that is to say for example when the temperature of the cold source from which the external heat is drawn is too low, the operation of the cycle d can be stopped. absorption, that is to say the operation of the de-phlegmator 16, the condenser 2, the regulator 3 and the evaporator 4, as well as the operation of the exchanger 7 which is short-circuited by a conduit 53 arranged in parallel on the exchanger 7 and controlled by a valve 54.

Under such operating conditions, it can be seen that the fluid to be heated is heated essentially in the exchanger 11 then in the exchanger 8, which is heated by the circuit of the solution passing through the exchanger 10, the base of the column 141e conduit 29, the bypass 53, the exchanger 8 and returning to the exchanger 10 after passing through the absorber 5 (which no longer functions as an absorber) and the return conduit 45 via the circulation pump 6.

From the foregoing description, it appears that the installation designed according to the invention and using few and simple apparatuses has very great flexibility of use, allows great compactness of construction, and allows the operation of the installation with switching off or on according to the most favorable conditions of the absorption cycle forming the heat pump. In addition, in its operation associated with the heat pump, the installation makes it possible to obtain improved yields compared to known installations, thanks to better separation of the distillates and residues produced in the absorption cycle, allowing better yields of this cycle and at the same time better recovery of the latent heat and condensation of the fumes and also latent and of condensation at the level of the absorption cycle and in particular of the distillates in the separation column 14 and in the de-phlegmator 16.

Claims (9)

1. Installation for heating fluids such as for example water, particularly for the heating of buildings and the production of hot water for domestic sanitary purposes, comprising at least one burner (9) for gas and/or liquid and/or solid fuel producing smoke at relatively high temperature and comprising a first heat exchanger (10) constituting the boiler of a heat pump and a second heat recovery exchanger (11) placed in series with the first and serving to heat the said fluid, the said first heat exchanger (10) communicating with a separator (14) in which separation of the «distillate» from the «residue» of the absorption solution to be regenerated is carried out, the said installation being characterised in that the said burner (9) discharges into a central combustion chamber (17) in contact with which there is a substantially annularly disposed jacket (15) divided by a wall (18) into two contiguous chambers (19, 20), the first chamber (20):

- receiving the returns of absorption solution to be regenerated before they are introduced into a separation column (14) forming the aforesaid separator and disposed just above the said jacket and

- being at least partially flush-fitted in the second chamber (19), which communicates directly with the residue present at the base of the said column (14) through ducts (21, 22) of large cross-section favouring a closed thermosyphon-induced heat exchange circulation of the said residue around the said combustion chamber (17).

2. Installation according to Claim 1, characterised in that the separation column (14) is of vertical and generally cylindrical shape comprising a certain number of chicanes (26, 28) disposed substantially horizontally and forming a simplified plate column.

3. Installation according to Claim 1 or Claim 2, characterised in that it comprises at the outlet from the separation column (14) on the path (30) of the distillates separated in the column an apparatus (16) referred to as a dephlegmator or fractionating column for at least partial drying of the distillates, the liquid parts separated in the dephlegmator being returned (at 38) to the said separation column (14).

4. Installation according to Claim 3, characterised in that the dephlegmator (16) comprises a substantially cylindrical flask or still having a vertical axis and comprising at least one peripheral helical descending path into which the said distillates are introduced, the said path being disposed so as to enter into a heat exchange with the fluid to be heated.

5. Installation according to Claim 4, characterised in that the said helical path is formed between the inner wall (32) of the said flask and a concentric and more inwardly disposed wall (33), an annular space being disposed between them and within which there is a tubular helix (34) in which the said refrigerant circulates.

6. Installation according to any one of the preceding Claims, characterised in that on the path of the residues emerging from the separation column (14) there is a heat exchanger (7) into which the returns of the solution to be regenerated are admitted in a counter-current pattern after passing through the absorber (5).

7. Installation according to any one of the preceding Claims, characterised in that a supplementary heat exchanger (8) is provided into which the fluid to be heated and the residues prior to their entry into the absorber (5) are admitted in a counter-current pattern.

8. Installation according to Claim 7, characterised in that a by-pass circuit (53) is provided which short circuits the heat exchanger (7) between residues and returns of the absorption solution so that the installation can be operated without the absorption cycle functioning.

9. Installation according to any one of the preceding Claims, characterised in that the separation column (14), the heat exchangers (7, 8) and the dephlegmator (16) are housed in the centre of a helix having a vertical axis forming the aforesaid first and second heat exchangers (10, 11) located on the smoke circuit.

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