FR3036178A1 - METHOD FOR COOLING A HOT SOURCE FOR EXCHANGING WITH A WORKING FLUID OF A THERMODYNAMIC SYSTEM, INSTALLATION USING THE METHOD AND THERMODYNAMIC SYSTEM - Google Patents

Abstract

The invention relates to a method of cooling a hot source for exchanging heat with a working fluid (Fw) of a thermodynamic system, in particular a thermodynamic system implementing a Rankine cycle, said thermodynamic system comprising a heat exchanger (21), said method comprising the following steps: - a step of heat exchange between a main flow (F2) of said hot source and said working fluid (Fw), and - a mixing step of a first stream (F1) of said hot source and a second stream (F4) of said hot source to constitute at least in part said main stream (F2), said second stream (F4) being taken from said hot source downstream said heat exchanger (21). The invention also relates to an installation implementing this method. The invention also relates to a corresponding thermodynamic system.

Description

The invention relates to a method for cooling a hot source intended to exchange with a working fluid of a thermodynamic system, an installation using this method and a thermodynamic system. heat with a working fluid of a thermodynamic system, in particular a thermodynamic system implementing a Rankine cycle. The invention also relates to an installation implementing this method. The invention also relates to a corresponding thermodynamic system. Known thermodynamic systems often operate by heat exchange with one or more external heat sources. However, the elements in contact with these heat sources, or the working fluids of said systems, may suffer from too high temperatures which could damage them. Thus, when these sources of heat are flue gases, it is known to ventilate them with rotating blades, or even to derive a portion to the outside environment, for the main purpose of lowering the temperature. However, the efficiency of the thermodynamic systems comprising a lowering of temperature of their hot source (s), such as the solutions cited by way of example, is not optimal. An object of the present invention is to provide a method and / or an installation for limiting the temperature of hot springs used to operate a thermodynamic system, without the performance of such a system is affected. Thus, the invention relates to a method of cooling a hot source for exchanging heat with a working fluid of a thermodynamic system, in particular a thermodynamic system implementing a Rankine cycle, said thermodynamic system comprising a heat exchanger. heat. According to the invention, the method comprises the following steps: a step of exchanging heat between a main flow of said hot source and said working fluid, and a step of mixing a first flow of said hot source and a second flow of said hot source to at least partially form said main stream, said second stream being taken from said hot source downstream of said heat exchanger. Here, the main flow consists of a first and a second flow, which allows to control the temperature. In fact, the mixing of two streams, one colder than the other, makes it possible to limit the temperature of the main stream obtained. Thus, the temperature of the main flow which is intended to exchange heat with the working fluid of the thermodynamic system will be limited, on demand. The method of the invention thus advantageously makes it possible to prevent the potential deteriorations of the thermodynamic system, and more specifically of its working fluid. In addition, since the temperature control is by recirculation of a fraction of the hot source, the method of the invention allows to operate without its performance is affected.

According to various embodiments of the invention, which may be taken together or separately: said first and second streams of the hot source are in the gaseous state, the method of the invention further comprises a filtering stage of said hot source after passing through said heat exchanger and before mixing said first and second streams of the hot source, the method of the invention further comprises a step of separating said main stream, downstream of said heat exchanger, from so as to define at least said second stream and a third stream of said hot source intended to be discharged to the outside, - said separation step takes place downstream of said filtering step, - the method of the invention comprises in in addition to a step of generating said first stream of said hot source which consists of the combustion, in a combustion chamber, of fossil energy, biomass, mineral matter and / or waste s.

The invention also relates to an installation implementing said method. The invention also relates to a cooling installation of a hot source for exchanging heat with a working fluid of a thermodynamic system, in particular a thermodynamic system implementing a Rankine cycle, said installation comprising a heat exchanger. heat of said thermodynamic system, said exchanger being configured to allow a heat exchange between a main flow of said hot source and said working fluid, said installation further comprising means for mixing a first and a second flow of said hot source so as to constitute at least in part said main stream, said installation being configured so that said second stream is taken from said hot source downstream of said heat exchanger.

According to various embodiments of the invention, which may be taken together or separately: the installation of the invention further comprises a filtering means of said hot source, said filtering means is positioned at the outlet of said exchanger the installation of the invention further comprises an exhaust stack intended to evacuate downstream of said exchanger a fraction of said hot source, said exchanger comprises a circulation beam of said hot source, said beam being in steel.

The invention also relates to a thermodynamic system implementing a thermodynamic Rankine cycle, said system comprising the heat exchanger of said installation.

The invention will be better understood, and other objects, details, features and advantages thereof will become more clearly apparent from the following detailed explanatory description of at least one embodiment of the invention 3036178 4 given by way of purely illustrative and nonlimiting example, with reference to the appended schematic drawings as follows: FIG. 1 is a diagrammatic representation of an exemplary embodiment of an installation according to the invention, said installation implementing the 5 process according to the invention - Figure 2 is also a schematic representation of an embodiment of an installation according to the invention, illustrating in particular the flow of the hot source.

The invention relates to a method of cooling a hot source for exchanging heat with a working fluid of a thermodynamic system. The hot source is illustrated in FIG. 2 in the form of several flows F1-F6 flowing inside branches 31-35 diagrammatically shown in FIG. 1. The working fluid is marked Fw in FIG. Moreover, said thermodynamic system is not illustrated in detail in Figures 1 and 2. Only a heat exchanger 21 of said system is shown here. By "thermodynamic system" is meant a thermodynamic system employing a Rankine cycle, or even any other thermodynamic system employing an expansion of a gaseous fluid. According to the invention, said method first comprises a step of heat exchange between a main flow F2 of said hot source and said working fluid Fw 25 (see FIG. 2). This exchange is done at the level of the heat exchanger 21. Said heat exchanger 21 will include, for example, a circulation beam of said hot source, here its main flow F2. Said beam will advantageously be made of steel. The method according to the invention further comprises a step of mixing a first stream F1 of said hot source and a second stream F4 of said hot source to form at least part of said main stream F2, said second stream F4 being taken from said hot source downstream of said heat exchanger 21. In other words, the hot source of the outlet is recirculated to the inlet of the exchanger 21. The main stream F2 thus constituted will have a temperature less higher than if it consisted of the first single stream F1, which itself comes directly from a combustion chamber 10, or equivalent. In other words, the mixing of the first stream F1 with the second stream F4, which is taken from it after the exchange of heat in the exchanger 21, makes it possible to lower the temperature of the main stream F2 thus obtained.

Accordingly, and advantageously, the heat exchanger 21 should not be of a particular design in the context of the process of the invention; it may be provided from standard type beams, steel, or even metals having a melting point lower than that of steel.

The closed loop use of the hot source, in particular during the first two steps described above, also has the advantage of optimizing the efficiency of said heat exchanger 21. In fact, the temperature of heat exchange within this exchanger 21 can be kept relatively constant, which allows an optimal heat exchange.

It should be noted that the mixing step is preferably performed at a mixing device 51 (see FIG. 2), more precisely in a dilution chamber 51. FIG. 1 schematically represents this dilution chamber 51 in the form of a point.

It should also be noted that the combustion chamber 10 makes it possible to carry out a step of the method of the invention, namely the generation of said first stream F1 of said hot source. This stage consists of the combustion of fossil energy, mineral matter and / or waste. The first F1 flow may also be generated by several combustion chambers, without departing from the scope of the invention. On the other hand, the working fluid Fw circulating in said thermodynamic system will not be damaged, either, by too high temperatures. Thus, the method of the invention also has the advantage of allowing the use of a working fluid Fw without predicting it resistant to high temperatures. For example, a temperature of the order of 1000 ° C for the first stream F1 at the outlet of the combustion chamber 10 and a temperature of about 200 ° C for the second stream F4 at the outlet of the exchanger 21 Depending on the respective flow rates chosen, after mixing, they may be driven at a temperature of the order of 500 ° C for the main flow F2. This temperature is indicated for the heat exchange with a working fluid Fw intended to circulate in a system using the Rankine thermodynamic cycle, for example.

In other words, the method of the invention comprises a step of collecting said hot source within a feed, or branch 31, at the outlet of the combustion chamber 10 (see FIG. 1). Said hot source is then in the form of a fluid in the gaseous state, called first stream F1.

The branch 31 is advantageously configured to guide said first stream F1 to the mixer 51 described above. The method of the invention further comprises a step of bypassing a portion of the hot source after it passes through the heat exchanger 21. This derivation step is carried out using a chamber schematically illustrated on Figures 1 and 2 by the element 52. This element 52 is a flow separation chamber. Said separation chamber 52 divides the flow at the outlet of the exchanger 21 into two streams: the second stream F4 and a third stream F5.

The second flow F4 is thus a recirculated flow, in particular via the branch identified 34 in FIG. 1. This second flow F4 is recirculated towards said branch 31, so as to lower the temperature of the first flow F1 which circulates there, as it comes to be described. Said first F1 and second stream F4 are then mixed in the mixing chamber 51 to become the main flow F2, which is then directed to the heat exchanger 21, in particular via the branch marked 32 in FIG. on the other hand, the flow directly after the exchanger 21 - referenced F3 in FIG. 2 - is circulated by the branch 33 of FIG. 1, towards the separation chamber 52.

It should be noted that said third stream F5 is intended to be rejected externally, preferably via an exhaust stack 60. This stack 60 is therefore intended to evacuate, downstream of said exchanger 21, a fraction of said source 3036178 7 hot, namely the third stream F5. This third stream F5 passes to said stack 60, via the branch 35 of FIG. 1. In an embodiment not shown here, the third stream F5 may be used for a device belonging to an installation distinct from that of the invention. for example for a heat exchanger or a carbon dioxide separation system. Said third stream F5 is then not rejected to the outside. The first stream F1 is thus mixed here in the chamber 51 with the second stream F4, which is colder, to give the main stream, or mixed stream F2. The mixed flow F2 then has a temperature intermediate between that of the first and second flows F1 and F4. The mixed flow F2 then gives heat to the fluid Fw, in particular at the exchanger 21.

Thus, the mixed flow F2 leaves the exchanger 21 colder than it enters, especially in the form of the flow F3. Said stream F3 is then divided between said second stream F4 and said third stream F5, at the separation element 52. It should also be noted that the method of the invention will advantageously comprise a filtering step of said hot source after passage of the hot source through said heat exchanger 21 and before mixing said first F1 and second flow F4 of the hot source. This filtering step is provided so as to avoid deterioration of said exchanger 21 by the second flow F4, or recirculated flow F4. In other words, as illustrated in FIG. 2, the installation of the invention will comprise filtering means 40 for filtering the flow F3 directly after the exchanger 21, and before the separation chamber 52. In other words, the filtering stage makes it possible to limit the fouling of the installation according to the invention, in particular of the heat exchanger 21.

It should be noted, again, that said filtering step will be provided before the process separation step described above. It should also be noted that the method of the invention may comprise an additional separation step concerning, in particular, said second flux F4.

This additional separation step of the second stream F4 will define a fourth stream F6 to be rejected, especially outside. This separation step is provided to lower the temperature of said second stream F4, more precisely so as to control the temperature prior to the step of mixing said process. According to a variant not illustrated here, temperature sensors may then be provided for measuring the temperature of the second stream F4 in order to make the decision to derive a part, or not, especially after calculation by an automaton. Recirculation of said fourth stream F6 may also be to the combustion chamber 10 (see Figure 2), so internally of said installation, this having the advantage of reusing the thermal inertia of the cooled part of the source hot on all floors of said installation. In other words, this has the advantage of not losing the thermal inertia that potentially represents said fourth F6 stream by rejecting it directly to the outside.

As mentioned above, the invention also relates to an installation implementing said method. Said installation comprises in particular the heat exchanger 21 and mixing means 51 of said first F1 and second flux F4 of said hot source so as to constitute at least partly said main stream F2. Said plant is configured so that said second stream F4 is taken from said hot source downstream of said heat exchanger 21. As also mentioned above, the invention also relates to a thermodynamic system implementing the Rankine thermodynamic cycle, said system comprising the heat exchanger 21 of said installation. It should be noted that said streams of the hot source are in the gaseous state. Thus, the branches 31-35 will be configured to contain such gaseous fluid streams.

In other words, said branches 31-35 will be pipes, ducts, channels and / or tubes capable of supporting such flows of gaseous fluid. In addition, the installation of the invention may advantageously comprise a ventilation means (not shown here) to ensure the flow of said flows F1-F6.

It should also be noted that said streams of the hot source comprise, for example, flue gases.

It should also be noted that the method of the invention makes it possible to ensure the safety of the installation implementing it, in particular by lowering the temperature of said fumes. It should also be noted that the method of the invention advantageously allows the use of working fluids Fw, commonly called heat recovery fluids, which must not exceed a certain temperature. It should be noted, on the other hand, that the combustion chamber of the plant of the invention will advantageously be a biomass boiler.

Claims (9)

REVENDICATIONS1. A method of cooling a hot source for exchanging heat with a working fluid (Fw) of a thermodynamic system, in particular a thermodynamic system employing a Rankine cycle, said thermodynamic system comprising a heat exchanger (21 ), said method comprising the steps of a step of heat exchange between a main flow (F2) of said hot source and said working fluid (Fw), and a step of mixing a first flow (F1) of said hot source and a second flow (F4) of said hot source to constitute at least partly said main stream (F2), said second stream (F4) being taken from said hot source downstream of said heat exchanger (21). 2. Method according to the preceding claim, wherein said first (F1) and second flow (F4) of the hot source are in the gaseous state. 3. Method according to any one of claims 1 or 2, further comprising a step of separating said main flow (F3), downstream of said exchanger (21), so as to define at least said second flow (F4) and a third stream (F5) of said hot source to be rejected externally. 4. Method according to any one of the preceding claims, further comprising a step of filtering said hot source after passing through said heat exchanger (21) and before mixing said first (F1) and second flow (F4) of the hot spring. 5. Method according to any one of the preceding claims, further comprising a step of generating said first flow (F1) of said hot source which consists of the combustion, in a combustion chamber (10), of fossil energy, of biomass, mineral matter and / or waste. 3036178 11 6. Installation implementing the method according to any one of the preceding claims. 7. Cooling plant of a heat source for exchanging heat with a working fluid (Fw) of a thermodynamic system, in particular a thermodynamic system implementing a Rankine cycle, said installation comprising a heat exchanger (21) said thermodynamic system, said exchanger (21) being configured to allow heat exchange between a main flow (F2) of said hot source and said working fluid (Fw), said apparatus further comprising mixing means (51) a first (F1) and a second flow (F4) of said hot source so as to constitute at least in part said main flow (F2), said installation being configured so that said second flow (F4) taken from said hot source downstream of said heat exchanger (21). 8. Installation according to the preceding claim, further comprising a filtering means (40) of said hot source, said filtering means (40) being positioned at the outlet of said heat exchanger (21). 20 9. Installation according to any one of claims 7 or 8, further comprising an exhaust chimney (60) for discharging downstream of said exchanger (21) a fraction (F5) of said hot source.