Device for recovering thermal energy from a flow of waste water

Abstract

Device for recovering thermal energy from a flow of wastewater from a basin includes a plate heat exchanger traversed by two separate fluid flows and a bypass conduit providing a hydraulic connection. A first inlet of the heat exchanger is placed in a fluid communication with the wastewater outflow opening of the basin to provide a first flow passing through the heat exchanger between the first inlet and a first outlet of the heat exchanger connected to the sewer. A second inlet of the heat exchanger is placed in a fluid communication with a clean water conduit under a water supply network pressure to provide a second flow passing through the heat exchanger without mixing with the first flow, and between the second inlet and a second outlet of the heat exchanger. The bypass conduit provides a bypass between the first inlet of the heat exchanger and the sewer.

Claims

1. A device for recovering thermal energy from a flow of wastewater from a basin, comprising: a plate heat exchanger traversed by two separate fluid flows: a first inlet of the heat exchanger, placed in a fluid communication with a wastewater outlet of the basin, to provide a first flow passing through the heat exchanger between the first inlet and a first outlet of the heat exchanger, the first outlet being connected to a sewer; a second inlet of the heat exchanger, placed in a fluid communication with a clean water conduit of a pressurized water supply network, to provide a second flow passing through the heat exchanger, without mixing with the first flow, between the second inlet and a second outlet of the heat exchanger; a bypass conduit to provide a hydraulic connection between the first inlet of the heat exchanger and the sewer; and a controlled connector configured to provide a temporary hydraulic connection, wherein the controlled connector connects the clean water conduit of the pressurized water supply network and the first outlet of the heat exchanger to provide a purge flow through the heat exchanger between the clean water conduit and the sewer via the bypass conduit.

2. The device according to claim 1, wherein the controlled connector comprises a flow stopper pinch valve between the first outlet of the heat exchanger and the sewer.

3. The device according to claim 2, further comprising a purge valve configured to place the pressurized water supply network in communication with the first outlet of the heat exchanger, and to place a controller of the flow stopper pinch valve for closing off the flow stopper pinch valve in communication with a shutting pressure.

4. The device according to claim 3, wherein the purge valve comprises: a hydraulically controlled mono-stable valve closed and opened under a predetermined pressure to place the first inlet of the heat exchanger in communication with the pressurized water supply network upstream and of the sewer; and a conduit utilizing a purge controller valve to place a controller of the hydraulically controlled mono-stable valve in fluid communication with the controller of the flow stopper pinch valve and the pressurized water supply network.

5. The device according to claim 3, wherein the purge valve comprises: a purge controller valve and a conduit configured to place the controller of the flow stopper pinch valve and the first outlet of the heat exchanger with the pressurized water supply network; and a regulator configured to create a pressure drop in the conduit of the pressure valve in a fluid communication with the first outlet of the heat exchanger.

6. The device according to claim 5, wherein the purge controller valve is a programmable valve.

7. A method for water filling a device for recovering thermal energy from a flow of wastewater from a basin, the device comprises: a plate heat exchanger traversed by two separate fluid flows: a first inlet of the heat exchanger, placed in a fluid communication with a wastewater outlet of the basin, to provide a first flow passing through the heat exchanger between the first inlet and a first outlet of the heat exchanger, the first outlet being connected to a sewer; a second inlet of the heat exchanger, placed in a fluid communication with a clean water conduit of a pressurized water supply network, to provide a second flow passing through the heat exchanger, without mixing with the first flow, between the second inlet and a second outlet of the heat exchanger; a bypass conduit to provide a hydraulic connection between the first inlet of the heat exchanger and the sewer; a controlled connector configured to provide a temporary hydraulic connection, wherein the controlled connector connects the clean water conduit of the pressurized water supply network and the first outlet of the heat exchanger to provide a purge flow through the heat exchanger between the clean water conduit and the sewer via the bypass conduit, the controlled connector comprises a flow stopper pinch valve between the first outlet of the heat exchanger and the sewer; a purge valve configured to place the pressurized water supply network in communication with the first outlet of the heat exchanger, and to place a controller of the flow stopper pinch valve for closing off the flow stopper pinch valve in communication with a shutting pressure; a progressive return conduit to place the controller of the flow stopper pinch valve in fluid communication and in parallel with the sewer, the progressive return conduit comprises a regulator to create a pressure drop in the progressive return conduit; and the method comprises the steps of filling the heat exchanger with water and expelling air trapped in passages of the heat exchanger where the wastewater flows by actuating the purge valve.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is described below in its preferred embodiments, in no way limiting, and with reference to FIGS. 1 to 8, in which:

(2) FIG. 1 shows a hydraulic diagram of an embodiment of the device of the invention;

(3) FIG. 2 shows a perspective view of an embodiment of a heat exchanger having hydraulic connections equipped with pinch valves on its first inlet and first outlet;

(4) FIG. 3 is a section view of a pinch valve in non-passing position;

(5) FIG. 4 shows a hydraulic circuit diagram corresponding to another embodiment of the device according to the invention;

(6) FIG. 5 shows a perspective view of embodiment of the device according to the invention and the flows that occur depending on the situation, FIG. 5A, in the case of nominal operation, FIG. 5B case of clogging of the heat exchanger and 5C in the case of using a purge flow;

(7) FIG. 6 is a hydraulic diagram of another embodiment of the device according to the invention using the configuration of FIG. 5;

(8) FIG. 7 shows a diagrammatic top view in cross-section, an exemplary embodiment of a purge using the device of FIG. 6; and

(9) FIG. 8 shows schematically the implementation stages of the water filling method according to the invention, 8A, in situations of normal operation without implementation of the method of the invention, 8B during filling of the exchanger according to the method of the invention and FIG. 8C in normal operation after the implementation of the water filling method according to the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(10) FIG. 1, according to an exemplary embodiment, a bathroom facility embodying the device according to the invention comprises a supply (110) of domestic cold water under pressure and a conduit (120) for collecting waste water to the sewer. The domestic cold water feeds a tap (115), such as a shower mixer, where it is mixed with hot water, before discharging into a basin (125).

(11) The basin is hydraulically connected to the sewer (120) by a conduit (121) for discharge. To get to the sewer, wastewater collected by the basin (125) passes through a plate heat exchanger (130) in which it enters through a first inlet (131) and exits through a first outlet (133). The same exchanger (130) comprises a second inlet (132) to which is connected an incoming domestic cold water and a second outlet (134) for the supply of the clean water to the tap (115). Thus, through this heat exchanger (130) the cold domestic water heading to the tap (115) is heated by the flow of wastewater.

(12) The heat exchanger (130) comprises corrugated plates which encourage the development of a turbulent flow inside thereof, thus limiting the risks of fatty depot or debris in said exchanger (130). However, despite these characteristics, it happens that the heat exchanger becomes clogged or that plugs, in particular hair, are formed, in particular to the first inlet (131) of the exchanger (130). According to an embodiment of the device according to the invention, the exchanger (130) is placed with its inlets (131, 132) and outlets (133, 134) horizontally oriented which increases the exchange surface of the exchanger without too significantly increasing its overall height, in order to place it, for example, in the joisting of a floor.

(13) According to the embodiment of FIG. 1, the device according to the invention comprises hydraulic fittings to blow a plug that would clog the exchanger (130). To this end, the device comprises valves (151, 141, 142, 111) hydraulically controlled and the operation of which is triggered by a 4-way valve (140).

(14) A first valve (151), called bypass valve, hydraulically controlled is located between the first inlet (131) of the exchanger and a conduit (150), called bypass conduit, in parallel with this first inlet to the sewer (120).

(15) A second valve (141) is placed on the pipe (121) connecting the flow coming from the basin (125) with the first inlet (131) of the exchanger. This hydraulically controlled valve (141) becomes blocked when the controller is in communication with the water supply network (110) pressure.

(16) A third hydraulically controlled valve (142), called flow stopper valve, is placed on the conduit (122) putting the first outlet (133) of the exchanger (130) in communication with the sewer (120). A valve (111), called supply valve, is placed on a conduit (112) mounted in parallel between the second inlet (132) and the first outlet (133) of the exchanger.

(17) This supply valve (111) is preferably manually operated, for example by means of a pushbutton. Alternatively, said valve (111) is hydraulically operated and in such a case it is open when the controller is in communication with the water supply network pressure (110).

(18) In nominal operation, the controller of the first valve (151) is placed in communication with the water supply network pressure via the 4-way valve (140) so that this first valve blocks the bypass conduit (150).

(19) Controllers of other valves (141, 142, 111) are put into communication with the sewer (120) via the 4-way valve (140) so that the second (141) and third (142) valves are open, the supply valve (111) being closed.

(20) Thus, the collected wastewater from the basin (125) passes through the heat exchanger (130) before joining the sewer and warms the clean water flow heading to the tap (115).

(21) By moving the 4-way valve (140), the controller of the second (141) and third (142) valves are fed, which has the effect of closing said valves.

(22) The bypass valve controller (151) is put into communication with the sewer so that the first valve (151) is open. By operating the supply valve (111), cold water at water supply network pressure (110) is sent to the exchanger (130) at its first outlet (133), causing a flow in reverse to that of the normal flow of waste water in said exchanger. Thus, the fresh water flow under pressure passes through the heat exchanger (130) from its first outlet (133) to its first inlet (131) and then flows to the sewer (120) through the bypass conduit (150).

(23) This back flow under the pressure of the water supply network allows popping the plug obstructing the exchanger inlet and sending said plug to the sewer. Thus, the fresh water flow (240) passing through the exchanger (130) in reverse to the nominal flow is a true purge flow.

(24) FIG. 2, according to an embodiment of the device according to the invention, the exchanger (130) is placed with its inlets (131, 132) and outlets (132, 134) horizontally oriented which increases the exchange area of the heat exchanger without increasing too much its height (h) dimension, in order to place it, for example, in the joisting of a floor.

(25) According to this embodiment, the first inlet (131) and the first outlet (133) are placed in the upper part of the exchanger (130), it then acts as a siphon in the plumbing and the siphon of the basing connected to said exchanger are eventually removed to limit pressure drop in gravity flow of waste water. According to this embodiment, an unfilled portion of the heat exchanger is always at the top thereof, at a height corresponding to the height of the inlet lines (131) and outlet (133) of waste water, so a portion of the potential heat exchange area of the heat exchanger is not used, said exchanger being filled up to a height substantially equal to h1 (hd) where d is the diameter of the pipe carrying wastewater. However, this diameter must be sufficient to meet the standards depending on the nature of the basin feeding the exchanger. Usually d=40 mm.

(26) In order to maintain a sufficient flow section, the controlled valves (141, 142, 151) installed on the pipe receiving wastewater are pinch type valves having a controller (241, 242, 251) able to introduce hydraulic pressure between the sleeve and the body of said valve.

(27) FIG. 3, a pinch valve (340) is shown in the closed position, non-passing. When hydraulic pressure is applied to the controller, the sleeve (341) obstructs the passage in the valve. When the controller is in communication with the sewer, the elasticity of the sleeve (341) expels, through the controller, the fluid between said sleeve (341) and the wall of the valve, reopening the passageway. The valve is then open.

(28) FIG. 4, according to another embodiment of the device according to the invention, a bypass conduit (461) on the water supply network connects said network to the inlet of a pinch valve (142), called flow stopper valve, able to close off the first outlet (133) of the exchanger (130). A valve (460), called the purge controller valve, for example a push button, normally closed, is placed on this parallel conduit of the domestic water supply network. Thus, said bypass comprises two conduits, a first conduit (461) communicates the pressure of the domestic water supply network to the purge controller valve (460) and to a second conduit (462), between the purge controller valve (460) and the controller of the flow stopper pinch valve (142).

(29) When the purge controller valve (460) is at rest, that is to say that the pushbutton is not actuated, the second conduit (462) of the bypass is not energized, and the flow stopper pinch valve (142) leaves wastewater flowing to the sewer. The second conduit (462) of this bypass from the water supply network, including the purge controller valve (460), comprises a conduit (463) to bypass the controller of the flow stopper pinch valve (142). This branch (463) includes a narrowing (464) able to create a significant pressure drop in the said conduit (463). By way of non-limiting example, this narrowing (464) is formed by a disc with a small diameter hole, for example a diameter between 1 mm and 1.5 mm. Alternatively the pressure drop is produced by an adjustable throttle valve by means known from the prior art.

(30) A second derivation branch (466) connected to the water supply network, puts in fluid communication said network to the first outlet (133) of the exchanger upstream of the flow stopper pinch valve (142). This second derivation branch includes two bypass conduits (466, 467), as the hydraulic communication between these conduits passes through a hydraulically controlled monostable valve (465), normally closed (not passing). The controller of said valve is in fluid communication with the second conduit (462) of the first branch. Thus, when the purge controller valve (460) is open, and when the pinch valve is closed, the pressure rises in the second conduit (462) of the first branch, until said pressure is sufficient to actuate the controller of the hydraulically controlled monostable valve (465), which then becomes open, putting the first outlet (133) of the exchanger (130) in communication with the water supply network, thus creating a reverse flow in said heat exchanger, from the first outlet (133) to the first inlet (131). This reverse flow can unclog the exchanger (130). To this end the device according to the invention is adjusted, firstly by the pressure drop created by the narrowing means (464) and secondly by the calibration of the controller of the hydraulically controlled monostable valve (465). Thus, the means (464) able to create the pressure drop are adjusted so that the pressure reached in the second conduit (462) when the purge controller valve (460) is actuated, is sufficient to make the hydraulically controlled monostable valve open (465) once the flow stopper pinch valve (142) is closed, but never completely close off the bypass conduit (463).

(31) Thus, when the pushbutton of the purge controller valve (460) is released, the pressure in the second bypass conduit (462) gradually decreases because of the flow limited by the narrowing means (464). Thus, the flow stopper pinch valve (142) opens again and the hydraulically controlled monostable valve (465) resumes its non-passing position, the whole apparatus resuming its nominal operation. The order in which this return to nominal operating conditions is made and the time required for it to complete, are set by the characteristics of the pressure drop means (464) and settings of the controller of the monostable valve (465).

(32) As a non-limiting example, the controller of the monostable valve (465) is calibrated to 2 bar (210.sup.5 Pa) and the pressure drop means (464) consists of a disc with a diameter of 1 mm hole in its center, put in the bypass conduit (463).

(33) FIG. 5, according to another embodiment of the device object of the invention, the bypass means do not include a valve. According to this embodiment, the bypass conduit (150) and the conduit collecting water from the shower or bath drains (121) are connected in series and are connected in parallel to an inlet conduit (531), which is itself linked to the first inlet (131) of the exchanger (130). As wastewater flows by gravity, it always takes the most direct way, i.e. creating the least pressure drop.

(34) FIG. 5A, in nominal operation, the flow (541) of waste water passes through the exchanger, arriving via the conduit collecting water from the shower plug (121), then flowing through the inlet conduit (531). Said flow (541) then passes through the heat exchanger to the first exit (133) and then to the sewer (120).

(35) FIG. 5B, in case of clogging of the heat exchanger (130), entry to the exchanger (130) is not the most direct path for the flow (542) of waste water from the basin, because of the existence of a pressure drop due to clogging. Thus, said wastewater flow (542) passes through the bypass conduit (150) to the sewer without going through the exchanger (130).

(36) FIG. 5C in order to unclog the exchanger (130), a flow (540) under pressure is injected at the first outlet (133) of the exchanger via a bypassing conduit (565) in parallel with the conduit (122) connecting said first outlet (133) to the sewer (120). This parallel connection is performed upstream of the flow stopper valve (142) considering nominal flow direction. Said purge flow (540) is injected while said flow stopper pinch valve (142) is closed.

(37) Thus, the stream (540) for cleaning enters the exchanger (130) by its first (133) outlet and undergoes a pressure drop when passing through the exchanger, so that on leaving the exchanger through its first inlet (131), pressure of said stream (540) is not sufficient to go up the conduit (121) connected to the basin, up to said basin. Thus, the stream (540) takes the most direct path and passes via the bypass conduit (150) and discharge into the sewer.

(38) FIG. 6, in another simplified embodiment of the purge, the device of the invention does not comprise a monostable valve. The conduit (462) in communication with the water supply network (110) through the purge controller valve (460), is on the one hand connected to the controller of the flow stopper valve (142) placed on the first (133) outlet of the exchanger (130) and on the other hand in fluid communication with said outlet (133) of the exchanger, through a conduit (565) in parallel, which is connected to the conduit, upstream of the flow stopped pinch valve (142) in the direction of the nominal flow. This bypass conduit (565) comprises means (665) for performing a pressure drop of between 1 and 1.5 bar, according to an exemplary embodiment, for instance using a pipe (665) of reduced diameter for this conduit (565). Said conduit (565) comprises a check valve (666) avoiding pollution of the water supply network with the contents of the exchanger (130). The purge controller valve (460), according to an alternative embodiment, is electrically controlled in order to achieve automation of the purging operation.

(39) FIG. 7, when the purge control is actuated, the fresh cold water arrives at the controller of the flow stopper pinch valve (142) through a bypass conduit (762), at the same time it passes through the conduit (565) connecting it to the first inlet (133) of the exchanger (130). Thus, the shutting pressure applied to the sleeve (341) of the flow stopper pinch valve (142) is equal to the pressure generated by the pressure drop means (665) in the conduit (565) supplying the heat exchanger by its first outlet (133), so that the more the heat exchanger is clogged, the more shutting pressure on the controller of the flow stopping pinch valve (142). Calibrating said pressure drop, an adequate balance is found between the purge flow rate and the pinch valve shutting rate for all possible conditions of use. Thus, according to an embodiment using a purge rate of 27.2 liters/min (4.5310.sup.4 m.sup.3.Math.s.sup.1), the pressure applied to the sleeve (341) of the pinch valve (142) is 2.62 bar (2.6210.sup.5 Pa) and leads to a 99.1% shutting rate of the flow stopper pinch valve (142). According to another exemplary embodiment using a purge flow of 23.9 liters/min (3.9810.sup.4 m.sup.3.Math.s.sup.1), the pressure on the sleeve is 1.98 bar (1.9810.sup.5 Pa) and the shutting rate of the pinch valve is 96.7%.

(40) According to a third embodiment, the purge rate is 19.3 liters/min (3.2210.sup.4 m.sup.3.Math.s.sup.1), the control pressure of the sleeve valve (142) is 1.28 bar (1.2810.sup.5 Pa) and the shutting rate of the pinch valve is 83.6%.

(41) The pressure drop (665) is controlled, for example, through the variation of cross-section and length of the conduit (565) connected to the first inlet (133) of the exchanger (130).

(42) FIG. 8, according to an embodiment of the method according of the invention, the heat exchanger (130) acts as a siphon in the plumbing and siphon drains of the basin connected to said exchanger are removed to limit pressure drop in the flow of waste water. According to this embodiment, an unfilled portion of the heat exchanger is always on top of it, at a height corresponding to the height of the wastewater inlet (131) and outlet (133), so that a portion of the potential heat exchange area is not used, the exchanger being filled only up to a height h1. In order to use the unfilled volume in the exchanger, according to an exemplary embodiment, the first inlet (131) and the first outlet (133) of the exchanger are advantageously placed in the lower part of the exchanger (130).

(43) FIG. 8A, in the absence of implementation of the filling method according to the invention, the heat exchanger and the discharge conduit act as a siphon, and a portion (830) of the exchanger (131) is never filled.

(44) FIG. 8B, in a first stage of the filling method according to the invention, cold water is supplied to the first outlet (133) of the heat exchanger by operating the purge controller valve (460). The water pressure (p) chases the bubble (830) and fills the exchanger (130).

(45) FIG. 8C, then by placing the heat exchanger under nominal operating conditions, that is to say, releasing the purge controller valve (460), provided the water seal height h2 remaining in the corresponding pipe is sufficient, air does not enter the exchanger whose interior is now in depression and said exchanger remains fully filled. Thus, the efficiency of the system is very much improved.

(46) The above description and the exemplary of embodiments show that the invention achieves the objectives; in particular it allows making the system less susceptible to clogging, maintaining remotely the exchanger in the system and improving its efficiency by optimizing the filling of the exchanger.