FR2935783A1 - Heating system for use in building, has internal and external heat exchangers recovering calories in vat and using calories in heat pump, where vat is emptied by overflowing waste water through waste water outlet - Google Patents

Abstract

The system has a waste water containing vat (10) defining a waste water containing volume (36) for containing waste water. The vat comprises a waste water inlet (38) opened on the volume and a waste water outlet (40) opened on the volume. An internal heat exchanger (26) and external heat exchangers (28) recover calories in the vat, and use the calories in a heat pump. The vat is emptied by overflowing the waste water through the outlet. An independent claim is also included for a heating installation comprising a heating system.

Description

The present invention relates to a heating system with heat recovery of wastewater, of the type comprising a heat pump, a wastewater holding tank defining a volume of wastewater. wastewater reservoir, the holding tank comprising a wastewater inlet leading to the holding volume and a wastewater outlet leading to the holding volume, and a heat exchanger for recovering calories in the holding tank and use them in the heat pump.

FR-A-2,885,406 discloses a heating system with heat recovery of wastewater comprising a wastewater holding tank providing vertical thermal stratification of wastewater and a heat pump whose evaporator is integrated in the tank of retained, and receives wastewater from the hottest part of the wastewater from the holding tank. The waste water outlet is located at the bottom of the tank and is closed by a valve. Nevertheless, there is a risk of valve failure. An object of the invention is to provide a heating system with heat recovery of wastewater that is reliable.

For this purpose, the invention relates to a heating system of the aforementioned type, characterized in that the holding tank empties by overflow of wastewater through the outlet. According to particular embodiments, the heating system according to the invention comprises one or more of the following characteristics, taken separately or in any technically possible combination: the wastewater inlet opens into the volume at the same height or at a higher level than the outlet of wastewater, the height of the outlet of wastewater in the holding volume defining the maximum level of wastewater in the holding volume from which wastewater overflows from the holding volume through the outlet of wastewater; the wastewater inlet opens into the holding volume at the same height as the outlet of wastewater; - the system includes a wastewater settling tank; the settling tank is arranged at the bottom of the holding volume; the system comprises an inlet baffle guiding the wastewater from the wastewater inlet to the settling tank, the inlet baffle extending preferably facing the settling tank; - the entry baffle is vertical; the system comprises at least one horizontal baffle downstream of the inlet baffle, in the direction of flow of the wastewater, the horizontal baffle extending preferably opposite the settling tank; - The exchanger is formed by at least one baffle defining an inner conduit for circulating a heat transfer fluid. The subject of the invention is also a heating installation comprising a wastewater source, a heating system with heat recovery of the wastewater and a heating application such as a central heating or domestic hot water circuit, fed by the heating system, characterized in that the heating system is according to any one of the preceding claims, the wastewater source being connected to the wastewater inlet of the holding tank. The invention will be better understood on reading the description which follows, given solely by way of example, and with reference to the appended drawings, in which: FIG. 1 is a diagram showing a heating installation comprising a heating system with heat recovery of waste water, according to the invention; Figure 2 is a vertical sectional side view of a wastewater holding tank and a heat exchanger of the heating system of Figure 1; - Figure 3 is a partial side view of the holding tank of Figure 2, in which an insulating layer of the tank has not been shown; - Figure 4 is a schematic vertical sectional view along the line IV-IV of Figure 2; - Figure 5 is a view similar to Figure 1 of a holding tank of a heating system according to a second embodiment of the invention; - Figure 6 is a schematic view illustrating a heat exchanger formed by several baffles internal to the holding tank of Figure 5; Figure 7 is a sectional view of one of the baffles of Figure 6; - Figure 8 is a view similar to Figures 2 and 5 of a holding tank of a heating system according to a third embodiment of the invention, the holding tank being provided with a settling tank; and FIG. 9 is a schematic view of an exchanger formed by a horizontal baffle internal to the holding tank of FIG. 8. FIG. 1 illustrates an individual heating installation 2 comprising a heating system 4 with heat recovery of wastewater and a heating application 6 supplied with heat by the heating system 4. The heating application 6 is for example a radiator circuit, domestic hot water, a floor heating, or a hot air network. The heating installation 2 also comprises one or more sources 8 of warm wastewater, receiving wastewater from, for example, a shower, a washing machine, a dishwasher, a bath . The heating system 4 comprises a holding tank 10, supplied by the source 8, and a heat pump 12 using the heat supplied by the wastewater of the tank 10.

The heating installation 2 also comprises a central control unit 7 controlling the heat pump 12 and the final application 6. The heat pump 12 conventionally comprises an evaporator 14, a compressor 16, a condenser 18 and an expander 20 connected in series by a primary circuit 22 of refrigerant.

The holding tank 10 comprises an internal exchanger 26 and an external exchanger 28 connected in parallel to the evaporator 14 by a secondary circuit 30 for circulating a heat transfer fluid. The secondary circuit 30 comprises a pump 30A ensuring the circulation of the heat transfer fluid, a bypass duct 30B of the exchangers 26 and 28 and a three-way valve 30C selectively closing the bypass duct 30B or the exchangers 26 and 28. secondary circuit 30 also comprises a control and regulation unit 30D driving the three-way valve 30C and the pump 30A, and a temperature sensor 30E of the coolant circulating in the secondary circuit 30. The control and regulation unit 30D receives a temperature measurement signal supplied by the temperature sensor 30E, and is connected to the central unit 7.

The secondary circuit 30 is further connected to an expansion tank 30F. The tank 10 for retaining wastewater will now be described in more detail with reference to FIGS. 2 to 4. The tank 10 is emptied by overflow: the water enters the tank 10 and leaves it discharging through an outlet when the water level in the tank reaches that of the outlet. The tank 10 comprises an envelope 34 delimiting an internal volume 36 for retaining wastewater, a wastewater inlet 38 in the holding volume 36, and a wastewater outlet 40 from the holding volume 36. 34 comprises a cylindrical wall 41 of horizontal axis, and two vertical walls 42 closing the cylindrical wall 41 at its respective ends. The holding volume 36 is delimited by the internal surface of the walls 41 and 42. The holding volume 36 has a length of between 1 m and 4 m, preferably between 1.4 m and 2.5 m, and a diameter of between 0, 4m and 2m, preferably between 0.4m and 1m. The dimensions are chosen according to the final application 6. The wastewater inlet 38 and the wastewater outlet 40 are formed respectively in the opposite vertical walls 42, each through an orifice passing through the wall 42 and opening into the holding volume 36. The inlet 38 and the outlet 40 are situated in an upper part of the holding tank 10, at the same height. The height of the outlet 40 in the holding volume 36 defines the maximum level of wastewater in the holding volume 36 from which the wastewater overflows from the holding volume 36 through the outlet 40. The tank 10 comprises a plurality of deflection baffles 44 extending into the retaining volume 36. The baffles 44 are arranged to modify the direct path of water between the inlet 38 and the outlet 40, by imposing a sinuous path bypassing the baffles 44.

The tank 10 comprises several baffles 44 regularly distributed along the axis of the tank 10. The baffles 44 divide the holding volume of the tank 10 into a plurality of compartments 46.

Each baffle 44 in fact forms on each side two compartments 46. In the example shown, the tank has three baffles 44 defining four compartments 46. Each baffle 44 has a general shape of plate, more precisely of truncated disk. They each delimit a continuous surface.

Each baffle 44 comprises an edge 48 of junction with the envelope 34, of complementary shape of the envelope 34, and a free edge 50 defining a flow passage 52 with the envelope 34. The edge 50 is horizontal. The flow passages 52 are located at a lower level than the waste water outlet 40.

The baffles 44 are parallel to each other and are arranged head to tail alternately. The baffles 44 are vertical. The flow passages 52 are alternately formed in the bottom and in the upper part of the holding volume 36. In the illustrated example, one of the baffles 44 projects upwardly from the bottom of the casing 34 while two other baffles 44 are arranged on either side and extend projecting downwards from the top of the casing 34. The baffles 44 define with the casing 34 a path for the sewage flow of the 38 to and 40. The tracking path passes successively in each compartment 46. It includes several changes in the direction of the flow of wastewater, to bypass the baffles 44. These changes of direction are, in the illustrated example, between 90 ° and 180 °.

The volume of the tank 10 is greater than 20 times the passage section per unit length of the inlet and outlet pipes, preferably greater than or equal to 40 times. In the example shown, this ratio is 45.

The travel time of the wastewater along the path of travel is therefore equivalent to the flow time of the wastewater in a passage section conduit identical to the inlet 38 and the outlet 40, and whose length would be 45 times higher.

The heat exchangers 26 and 28 are arranged to recover calories in the holding tank 10. The exchangers 26 and 28 are connected in parallel to the secondary circuit 30 and each have a manual flow control valve 58. The internal heat exchanger 26 comprises a plurality of ducts 60 extending inside the retaining volume 36. Each duct 60 passes successively through each of the compartments 46. The internal exchanger 26 is thus able to recover calories in each of the compartments. defined by the baffles 44. The conduits 60 are connected in parallel. They are also arranged parallel to each other. Each duct 60 comprises two vertical sections 62 and a horizontal section 64 connecting the two vertical sections 62 at their lower ends. Each duct 60 thus forms a U. The horizontal section 64 extends in the bottom of the tank 10, over substantially the entire length of the tank 10. The horizontal section 64 extends in the flow passages 52 defined by the upper baffles 44 and through the lower baffle 44. The external exchanger 28 comprises a helical duct 66 extending helically around the casing 34, over substantially the entire length of the casing 34. The external exchanger 28 is arranged in an insulating layer 68 surrounding the outer casing 34. The insulating layer 68 avoids the heat loss of the tank 10. The holding tank 10 further comprises two access hatches 72 formed respectively in the vertical walls 42 of the outer casing 34. The diameter of the hatches Access 72 is important, of the order of half the diameter of the tank 10, for easy cleaning.

Finally, the holding tank 10 is provided with a temperature sensor 73 and a water level sensor 74 connected to the central control unit. The operation of the invention will now be described. The heating installation 2 is started by means of the central control unit 7. The central control unit 7 sends a start-up signal to the final application 6, to the heating pump. 12 and the control and regulating unit 30D of the secondary circuit 30. The control and regulation unit 30D controls the pump 30A and the three-way valve 30C according to the control signals provided by the central unit 7 and / or the temperature value provided by the temperature sensor 30E. In a variant, the control and regulation unit 30D also controls the flow control valves 58 of the heat exchangers 26 and 28. The circulation of the coolant in the heat exchangers 26 and 28 heats the coolant. The coolant passes through the evaporator 14 by giving heat to the refrigerant. It cools in the condenser 18 by supplying heat to the final application 6. For reasons of safety and energy saving, the central control unit 7 stops the installation if the temperature value provided by the temperature sensor 73 of the tank 10 is too low and / or if the water level sensor 74 detects a water level too low in the tank 10. With the invention, the baffles 44 impose on the water used a path of travel successively in several compartments 46 from which the heat exchangers 26 and 28 recover heat. The wastewater arriving through the inlet is forced to pass through each compartment 46, which ensures a significant recovery of the heat of these inlet waters by the exchangers 26 and 28. The energy efficiency of the installation 2 is high. The volume required for the holding tank 10 is small. The importance of the wastewater flow time around the baffles 44 ensures optimal recovery of their heat by the exchangers 26 and 28. The baffles 44 prevent vertical thermal stratification of the wastewater in which the hottest waters would be in the water. upper part of the tank 10, which would lead to a rapid flow of the hottest waters. In addition, the baffles 44 do not induce a risk of obstruction of the tank 10.

The arrangement of the exchangers 26 and 28 provides a large heat exchanger surface with the wastewater present in the holding tank 10. The overflow of the tank 10 limits the risk of obstruction of the tank 10. Indeed the presence of a valve 10 at the outlet 40 is unnecessary.

The tank is reliable. In addition, the risk of obstruction of the outlet 40 by an aggregate of particles is very low. The use of a secondary circuit 30 for circulating a heat transfer fluid connecting the exchangers 26 and 28 to the evaporator 14 makes it possible to adapt the holding tank 10 to pre-existing heat pumps 12. In addition, the heat pump 12 is removable without intervention on the holding tank 10, which facilitates assembly and maintenance of the installation 2. Alternatively, the heating installation 2 is that of a building .

Figures 5 to 7 illustrate a heating system 4 according to a second embodiment of the invention, of which only the differences with respect to the first embodiment will be described below. In Figures 5 to 7, elements similar to the first embodiment are designated by like reference numerals.

The heating system 4 according to the second embodiment differs essentially by the holding tank 10. The internal exchanger 26 and the external exchanger 28 have been replaced by a single exchanger 76 formed by the baffles 44 of the tank 10. In FIG. Indeed, as illustrated in Figures 6 and 7, each baffle 44 defining an inner conduit 78 for circulating a heat transfer fluid. The internal duct 78 itself comprises baffles making it possible to impose a long path and a long circulation time on the heat-transfer fluid in the internal duct 78, favoring heat exchanges.

The inlet of each duct 78 of each baffle 44 is connected to the outlet of the adjacent baffle 44. The baffles 44 are thus connected in series to form the exchanger 76. The baffles 44 are attached in orifices 79 formed in the cylindrical wall 41 of the casing 34, and connected to each other outside the casing 34. In addition, the number of baffles 44 has been increased. The number of baffles 44 is now such that the passage section of the sewage flow path between the baffles 44 is substantially constant in the tank 10. The exchange surface of the exchanger 76 is very important. Figures 8 and 9 illustrate a heating system 4 according to a third embodiment of the invention, in which only the differences with respect to the second embodiment of the invention will be described below. The identical reference elements designate analogous elements. The heating system 4 according to the third embodiment differs essentially from the heating system 4 according to the second embodiment in that the tank 10 comprises horizontal baffles imposing a sinuous path from the bottom of the tank 10 to the outlet 40 at the top of the tank 10 and in that the tank 10 comprises a tank 82 for decanting the wastewater. The horizontal baffles 44 have a complementary contour of the envelope 34. They thus have a rectangular general outline, which facilitates their manufacture. Some horizontal baffles 44 have an internal duct 78 and form the exchanger 76. In the example illustrated, only one horizontal baffle 44 on two forms the exchanger 76, the other horizontal baffles 44 being devoid of a heat-transfer fluid circulation duct and arranged alternately with the baffles 44 forming the exchanger 76. This reduces the bulk of the tank 10 and the cost of the exchanger 76. Nevertheless, alternatively, each horizontal baffle 44 forms the exchanger 76. In addition, as illustrated in FIG. 9, the baffles 44 comprise a through orifice 80 forming a flow passage 52 of the wastewater.

The settling tank 82 is disposed in the bottom of the tank 10. It is disposed on the side of the wastewater inlet 38. The settling tank 82 is convergent downwards, more precisely tapered downwards. The tank 82 has, at its lower end, a drain valve 84. The tank 14 comprises a vertical inlet baffle 86 imposing the wastewater entering the tank 10 to descend towards the bottom towards the tank 82, and before go back to exit 40 following the path defined by the horizontal baffles 44.

The operation of the settling tank 82 is simple. To clean the tank 10, simply open the drain valve 84. The particles accumulated in the tank 82 are then discharged. The settling tank 82 facilitates maintenance operations. The arrangements of the reservoir 82 and the baffles 86 and 44 improve the guiding of the particles present in the wastewater towards the reservoir 82. These arrangements also limit the rise of particles.

Claims (1)

CLAIMS1.- Heating system (4) with heat recovery of wastewater, of the type comprising: - a heat pump (12); a wastewater holding tank (10) defining a wastewater holding volume (36), the holding tank (10) comprising a wastewater inlet (38) opening onto the holding volume (36) and an outlet (40) of wastewater opening on the holding volume (36); and - a heat exchanger (26, 28; 76) for recovering calories from the holding tank (10) and using them in the heat pump (12), characterized in that the holding tank (10) is emptied by overflow of wastewater through the outlet (40). 2. Heating system (4) according to claim 1, wherein the wastewater inlet (38) opens into the holding volume (36) at the same height or at a level higher than the outlet of waste water (40), the height of the wastewater outlet (40) in the holding volume (36) defining the maximum level of wastewater in the holding volume (36) from which the wastewater overflows from the holding volume (36) through the wastewater outlet (40). 3. Heating system (4) according to claim 2, wherein the wastewater inlet (38) opens into the holding volume (36) at the same height as the waste water outlet (40). 4. Heating system (4) according to any one of the preceding claims, comprising a settling tank (82) wastewater. 5. Heating system (4) according to claim 4, wherein the settling tank (82) is disposed at the bottom of the holding volume (36). 6. Heating system (4) according to claim 4 or 5, comprising an inlet baffle (86) guiding the wastewater from the wastewater inlet (38) to the settling tank (82), the inlet baffle (86) extending preferably facing the settling tank (82). 7. Heating system (4) according to claim 6, wherein the inlet baffle (86) is vertical. 8. A heating system (4) according to claim 6 or 7, comprising at least one horizontal baffle (44) downstream of the inlet baffle (86), in the flow of wastewater, the horizontal baffle ( 44) extending preferably opposite the settling tank (82). 9. Heating system (4) according to any one of claims 6 to 8, wherein the exchanger (26; 76) is formed by at least one baffle (44) defining an inner duct (78) for circulation a heat transfer fluid. Heating plant (2) comprising a wastewater source (8), a heating system (4) with heat recovery of the wastewater and a heating application (6) such as a central heating circuit. or domestic hot water, supplied with calories by the heating system (4), characterized in that the heating system (4) is according to any one of the preceding claims, the source of wastewater (8) being connected to the wastewater inlet (38) of the holding tank (10).