FR2492068A1 - Heat pump installation for heating water - has steam ejectors to compress water vapour and direct-contact condensers - Google Patents

Abstract

The installation has three stages of evaporation, compression and condensation. Water (1), at low temperature, is supplied to a low pressure evaporator (2) where some is produced. The residual water passes via an expansion valve (7) to the next stage (3) of evaporation and finally into a third evaporator (4). The flash steam from the evaporators is fed to the three stages of condensation (17,18,23) through three corresponding steam ejectors (14,19,21). The flash steam is compressed by the ejectors which use high pressure steam from a boiler (16). Water to be heated enters the condensers through the sprays (25,27,29) and is supplied to the heating circuit using a circulating pump (30).

Description

DESCRIPTION
The present invention relates to a ceded proS and to a heat pump installation by ejecto-compression of water vapor for water heating.

 Heat pumps are processes that allow the temperature level of a heat source to be raised at low temperature, in order to use it at a higher temperature, thus ensuring its recovery, whereas it is generally rejected. in the atmosphere without use.

 It is thus known to use an organic fluid cycle as a heat pump.

both an evaporator which absorbs the heat energy transmitted by the low temperature heat source to be exploited, a mechanical compressor which compresses the organic fluid which has evaporated in the evaporator, thus increasing the condensation temperature, a condenser which condenses the organic fluid, yielding heat from the heat source at a high temperature level, an expansion valve which is used to introduce the organic fluid into the evaporator.

 These organic fluid heat pumps have the drawbacks of using an expensive fluid, the thermal stability of which is poor at high temperature, that the exchange coefficients of evaporation, condensation and convection are low, and that a mechanical compressor is used comprising moving parts, therefore subject to wear, and which transmits to the system only the mechanical compression energy, whereas at least two and a half times more energy was required in the form heat (fuel, coal) to produce this mechanical energy.

 The present invention aims to remedy these drawbacks and for this purpose, it relates to a heat pump process by ejectobcompression of water vapor for heating water in which the heat is recovered from a circuit d water by evaporation of water at low temperature, this water vapor is compressed in a static device using high pressure water vapor as compression energy, the compressed water vapor is condensed to yield the recovered heat and that coming from high pressure water vapor to the water to be heated, evaporation, compression and condensation being able to take place in different successive stages.

 It also relates to a heat pump installation by ejecto # compression of water vapor for water heating comprising one or more water evaporators placed on the water circuit on which the heat is recovered, one or several static compression devices of the ejector type for compressing the water vapor from the evaporation by high pressure water vapor from a boiler, one or more condensers which condense all or part of the compressed vapor leaving the ejectors to reheat water.

 This method and this installation have the advantage that water vapor is used as the heat transfer fluid, that the water vapor is compressed in a static device, transmitting to the system all the heat of the vapor d 'high pressure water used for compression, which is used depending on the case several stages of evaporation, comw pressure, condensation to increase the heat recovered and decrease the exchangers.

Other characteristics and advantages of the in ~ vent ion will appear during the description which follows
The accompanying drawings are given only as examples
Figure 1 is a schematic view of an installation according to a first embodiment according to the invention.

 Figure 2 is a schematic view of another embodiment according to the invention.

 The installation shown in FIG. 1 is used to recover the heat from a water circuit (1), to increase the temperature level of this heat by the static compressors (2) and (3) and to transfer this heat by the intermediate of the condensers (4) and (5) with the cooked water wax (6).

 The water circuit (1) passes through the evaporator (7) yielding its heat by means of tubes, the exterior of which is sprayed by a water circuit (8) comprising an expansion device (9) and a system of watering. The steam leaving the evaporator - (7) through the circuit (10) is connected to the static compression device (2) of the ejector type comprising a high pressure steam jet nozzle arriving through the circuit (ll) from from the boiler (12), a chamber for mixing the expanded high-pressure steam and the sucked steam, a pressure venturi of this mixture which is connected to the condenser (4).

The condenser (4) is crossed by the water circuit (6) which heats up by means of tubes (13).

The water coming from the condensation of the vapor is taken up by the pipe (14) to be partly directed towards the evaporator (7) by the pipe (8), in
part directed towards the boiler (12) via the pump (15). The vapor which has not been condensed in the condenser (4) is taken up by the pipe (16) and directed towards the ejector which is analogous to the previous ejector (2) and which is supplied with high pressure steam by the pipe (17) and the boiler (12). The discharge of this ejector is connected to the condenser (5) which is crossed by the same water circuit (6) and which includes exchange tubes (18). The vapor is completely condensed and the condensates are taken up by the pipe ( 19) to be mixed with condensate from the condenser (4) in the canaliaau tion (14) by means of a trap or a U-tube. The operating principle of this installation is as follows
The heat recovered in the circuit (1), which can come from a water circuit from solar collectors, from a cooling circuit for the refrigeration unit, from geothermal drilling, from discharges of water to the sewer, ... is used to evaporate water at a temperature slightly lower than that of the circuit (1). The steam produced is compressed in the static ejector (2) to raise its condensation temperature and be used to heat a water circuit (6). It therefore condenses in the condenser (4) and a second compression stage has been provided in the example with the ejector (3) and the condenser (5) so as to raise the temperature of condensa to an even higher level. tion of the vapor recovered, therefore the temperature of the water to be heated.

 The two ejectors (2) and (3) operate using high pressure steam from the boiler (12). This boiler is supplied by a part of the condensates coming from the condensers (4) and (5).

The other part of the condensate is directed to the evaporator (7) and expanded by the device (9) because the pressure of the condensates is higher than that of the evaporator.

 The installation shown in Figure 2 is another embodiment according to the invention. It has three stages of evaporation, three stages of compression and three stages of condensation.

 In this example the condensers and the e ..

 evaporators have no exchange walls separating the circuits, evaporation taking place by expansion of the water from which the heat is recovered, condensation taking place by contact between the water to be heated and the steam.

 The circuit (1) of water from which the heat is recovered passes into an expansion chamber having three stages (2), (3) and (4). The passage from one stage to another is done by the pipes (5) and (6) and the expansion members (7) and (8) after being taken up by the pump (10).

 The steam escapes through the line (11) of stage two, through the line (12) of stage three, through line (13) of stage four.

The pipe (13) is connected to the ejector (14), supplied with high pressure steam by the pipe (15) and the boiler (16) and discharging into the direct contact condenser (17). The pipe (12) is connected to this same condenser (17). The pipe (11) flows back into the condenser (18), as does the ejector (19) which sucks the uncondensed steam from the condenser (17) and which is supplied with high pressure steam through the pipe (20) and the boiler (16).

 The non-condensed steam in the condenser (is) is sucked by the ejector (21) supplied with high pressure steam by the pipe (22) and the boiler (16), and which discharges into the condenser (23).

 The condensers (17), (18) and (23) are supplied with water to be heated by the circuit (24). Water first enters the condenser (17), is contacted with the vapor, is sprayed by the device (25) to improve this contact and is taken up by the pump (26) to enter the condenser (18 ). This water is sprayed by the device (27) into the condenser (18), then taken up by the pump (28) to be sprayed into the condenser (23) by the device (29).

It is taken up again by the pump (30) which transfers it to the operating circuit.

The operating principle of this installation is as follows
The water (1) from which the heat is recovered is sent to an evaporator (2) where the pressure is lower than that corresponding to the liquid / vapor equilibrium pressure. She relaxes and a little par ..

tie water evaporates so that the temperature drops to that of the liquid / vapor balance corresponding to the pressure of the evaporator (2). It is the same in the evaporator (3) where the pressure is lower than in the evaporator (2), and in the evaporator (4) where the pressure is lower than in the evaporator (3).

 These three evaporators therefore produce water vapor which will be used to heat a water circuit (24). In the example in figure 2, the vapor at the highest pressure, therefore at the highest temperature, leaving the evaporator (2) heats the water by contact in the condenser (in), the vapor condensing on contact. with the water sprayed into the device (27).

Steam at a slightly lower pressure leaving the evaporator (3) heats the water in the condenser (17) by contact. This condenser (17) is at a speed, therefore at a lower temperature than that of the condenser (18). The vapor produced at the lowest pressure leaving the evaporator (4) is compressed by the ejector (14) to be introduced into the condenser (17). In the condenser (17) the non-condensed vapor is taken up by the ejector (19) to be compressed and injected in the condenser (18). The non-condensed vapor in the condenser (lys) is taken up by the ejector ( 21) to be condensed in the condenser (23) whose temperature and pressure are higher than that of the condenser (18), thus making it possible to have the temperature of the water circuit to be heated as high as possible. The ejectors (14), (19) and (21) operate by means of high pressure steam from the boiler (16) and which also heats the water circuit (24). As the pressures in the condensers (17), (18) and (23) increase, it is necessary to have the pumps (26) and (28) to ensure the circulation of the water. The pump (30) provides a water pressure ensuring the circulation of hot water for use.

 In the two preceding examples, if the temperatures of the water from which the heat is recovered and those of the water which is heated are less than 1000 ° C., the evaporators and the condensers operate under vacuum and a known device is used to extract the incondensables which would increase the operating pressures and interfere with the operation of heat recovery.

 The applications of this invention relate to establishments which have a low temperature heat source such as the cooling water circuit of a refrigeration unit, an oil circuit, equipment such as solar collectors, a geothermal water circuit, polluted lukewarm water discharges ... and which seek to recover this heat at a higher temperature to produce hot water usable for space heating, for sanitary or cleaning needs , for heat input to equipment ...

 The process and the installation described in the patent are of energetic interest because they make it possible to reduce consumption from 20% to 80%.

 calorific tion of hot water production devices according to the temperature of the heat source to be recovered and the pressure of the steam coming from the boiler.

 Applied to a slaughterhouse which needs water at 600 C and which has a cooling water circuit for a refrigeration unit at 300 C, this invention ensures an annual fuel saving of 50 91 by using a boiler. pressure steam 10 bar.

 Compared to the mechanical compression system, the invention has the advantage of using a static device without a moving part #. # - therefore without mechanical wear and of requiring, as compression energy, high pressure water vapor whose heat is fully transmitted to the water to be heated. A mechanical compressor only transmits mechanical energy to water in the form of heat, whereas it took about 2.5 times more thermal energy (fuel or coal) to produce this mechanical energy.

 The use of steam is very advantageous because the exchange coefficients in condensation, evaporation and convection are very high, thus reducing the exchange surfaces. The cost of water is also negligible compared to the cost of the organic fluid often used with mechanical compression processes. The steam allows the use of expansion chambers which have the advantage of avoiding the exchange surfaces, with intermediate walls, of reducing the cost of the evaporators and of avoiding the fouling and corrosions of the surfaces in the heat is recovered on a polluted water circuit.

 Water vapor also allows the use of direct contact condensers, without an exchange surface with intermediate walls, # iminu.ant the cost of tales.

 densities, avoiding fouling and corrosion.

 The use of several stages of evaporation, condensation and compression makes it possible to obtain the highest amount of recovered heat while ensuring heating at the highest temperature.

Claims (10)

1) Ejectocompression heat pump method  water vapor for heating dan type water  which recovers heat from a water circuit at  low temperature, characterized in that one performs  this recovery by evaporation of water, we understand  me this water evaporated by the action of high water vapor  pressure you into a static device and condense  getting compressed water vapor to heat a circuit  of water. 2) heat pump method according to claim 1  characterized in that evaporation takes place at  several stages corresponding to temperatures and  different evaporation pressures. 3) Heat pump method according to any one  claims 1 and 2 characterized in that  performs compression in several stages with  different pressures. 4) Heat pump method according to any one  of claims 1 to 3 characterized in that rea  reads condensation on multiple # rs corresponding floors  at temperatures and pressures different from  condensation. 5) Heat pump method according to any one  of claims I to 4 characterized in that-l'.ávaff  poration takes place by relaxing the water in the water circuit to  low temperature by introducing water to relax  in a lower pressure evaporator  that the liquid / vapor equilibrium pressure corresponds  at the temperature of the incoming water. 6) Heat pump method according to any one  claims 1 to 5, characterized in that the  condensation takes place by contact between water vapor  and the water in the water circuit to be heated without dry walls  adorning the two fluids. 7) Installation (fig 1) for implementing the process  die according to any one of claims 1 to 6  characterized in that it comprises at least one evapo  rator (7) recovering heat from a water circuit  (1), at least one static compression device  (2) using high pressure steam to  compressing the water vapor from  evaporators, and at least one condenser (4) yielding  to the water circuit to be heated (6) the heat from  from the condensation of water vapor coming out of th  vaporizers and static compression devices. 8) Installation (fig 1) according to claim 7 ca  characterized in that the compression device  static is an ejector (2) comprising a nozzle  of high pressure water vapor, a  mixing chamber of the sucked water vapor and  expanded high pressure steam, and a ventu  laughed at compression of the mixture.  9) Installation (fig 2) according to any of the re  vendications 7 and 8 characterized in that the evaporator  tor is a relaxation room (2) supplied by the  water circuit (1) from which heat is recovered. 10) Installation (fig 2) according to any of the re  vendications 7 to 9 characterized in that the conden  seur (17) is a room in which the exchange  thermal takes place by direct contact between the steam leaving the ejectors (19) and (21) and the evaporators. (2), (3) and (4) and the water in the circuit to be heated (24).