EP3447256B1 - System for cooling a process fluid from a heat producing installation - Google Patents

Description

Field of invention

The invention relates to a system for cooling a process fluid of a heat-generating device.

State of the art

There are currently numerous applications in industry (e.g. cooling of compressed air compressors, food industry, chemical industry), in power generation (e.g. cooling of engine cooling water in stationary engines, transformers) or in transport (internal combustion engines, e.g. trucks), in which, for example, electrical (or mechanical ) Energy is used to drive a cooler, for example an air cooler. The medium to be cooled is usually passed into a heat exchanger through which ambient air flows. The air flow is generated, for example, using electrically or mechanically driven fans. The medium to be cooled (hereinafter referred to as process fluid) releases the energy into the ambient air and returns to the process cooled. The disadvantage here is that electrical or mechanical energy is used to extract thermal energy from the process.

The document EP 2 320 058 A1 describes the use of waste heat for combustion engines. The waste heat utilization device includes a cooling water cycle with a circulation path for circulating cooling water and a Rankine cycle with a circulation path for circulating a working fluid.

Description of the invention

The object of the invention is to avoid or at least mitigate the disadvantages mentioned.

The invention describes the solution to the above-mentioned problem by, among other things, using a thermodynamic cycle device to partially convert the heat removed from the medium into mechanical and/or electrical energy.

The solution according to the invention is defined by a device with the features according to claim 1.

Further developments of the system according to the invention are presented in the dependent claims.

Further, additional features and exemplary embodiments, some of which are embodiments of the invention and some of which are not embodiments of the invention, but which contribute to its understanding, as well as advantages of the present invention are explained in more detail below with reference to the drawings. It is to be understood that the embodiments do not exhaust the scope of the present invention, which invention is defined solely by the appended independent claim 1.

drawings

Fig. 1

shows a first embodiment not according to the invention (variant 1) of the device.

Fig. 2

shows a second embodiment (variant 2A) of the device not according to the invention.

Fig. 3

shows a third embodiment (variant 2B) of the device not according to the invention.

Fig. 4

shows a temperature-heat flow diagram (TQ diagram)

Fig. 5

shows a fourth embodiment (variant 2C) of the device not according to the invention.

Fig. 6

shows a fifth embodiment (variant 3A) of the device not according to the invention.

Fig. 7

shows a non-inventive sixth embodiment (variant 3B) of the device.

Fig. 8

shows a seventh embodiment (variant 4) of the device not according to the invention.

Fig. 9

shows a non-inventive eighth embodiment (variant 5) of the device.

Fig. 10

shows a ninth embodiment (variant 6) of the device according to the invention, the invention being defined by the appended independent claim 1.

Fig. 11

shows a tenth embodiment (variant 7) of the device not according to the invention.

Like reference numbers in the drawings refer to identical or corresponding components.

Embodiments

In numerous applications of air coolers (see section: State of the art), a medium is cooled at temperatures >50°C. This temperature level is sufficient to operate a thermodynamic cycle, e.g. an Organic Rankine Cycle process (ORC process). In addition to the cooling function, usable mechanical and/or electrical energy can also be provided. This energy can, for example, drive an air cooler or be used for other purposes (operation of process-related consumers, pumps, energy storage...).

The thermodynamic cycle therefore at least partially replaces the air cooler originally used in the respective application, which is why in the case of an Organic Rankine Cycle process, for example, one can speak of an ORC cooler for the application.

Specific ORC Cooler Preferred Requirements:

• The cooling performance should be guaranteed even if the ORC circuit fails.
• In some applications, excess electricity should not be generated because direct feed-in to the grid may increase the technical and legal complexity disproportionately. Therefore, in such a case, no connection to the power grid is required.
• There should be as little maintenance as possible and there should be no increase in maintenance costs compared to conventional coolers.
• If necessary, a temperature level of the main process / the process to be cooled should be maintained, i.e. a temperature of the returned process fluid should be achieved or fallen below. By adding at least one further heat exchanger, a further temperature difference is present between the working medium or the process fluid and the cooling fluid of a cooler (e.g. ambient air or cooling water), so that the target temperature of the process to be cooled cannot be maintained. The problem of the additional temperature difference is solved using the connections listed below.
• Modularity of the system is preferred in order to be able to provide higher cooling capacities if required.
• There should be no influence on the existing control system of the main process.

In general, within and outside of the present invention, the ORC cooler can be used for all processes in which the fluid to be cooled can be returned to the process with a sufficiently large temperature distance from the ambient temperature (e.g. with a temperature above 40 ° C).

Example applications for processes to be cooled (not complete):

• Engines (train, truck, construction machinery, crane, marine)
• Air compressors
• Industrial processes (automotive, chemicals, printing, electrical and electronics, glass, rubber, plastics, lasers, food, pharmaceuticals, textiles, environment, packaging,...)
• Transformer stations
• Data center (server cooling)

Detailed description related to the drawings Variant 1 - basic wiring

Fig. 1 shows a first embodiment 100 of the thermodynamic cycle device not according to the invention.

The system 100 for cooling a process fluid (e.g. water) of a heat-generating device 10 comprises: an output 11 of the heat-generating device, the output 11 being provided for discharging process fluid to be cooled from the heat-generating device 10; an inlet 12 of the heat generating device 10, the inlet 12 being provided for supplying cooled process fluid to the heat generating device 10; and a thermodynamic cycle device, in particular an ORC device, wherein the thermodynamic cycle device comprises: an evaporator 20 with an inlet 21 for supplying the process fluid to be cooled from the outlet 11 of the heat-generating device 10 and with an outlet 22 for discharging the cooled process fluid to the inlet 12 the heat-generating device 10, wherein the evaporator 20 is designed to evaporate a working medium of the thermodynamic cycle device using heat from the process fluid; an expansion machine 30 for expanding the evaporated working medium and for generating mechanical and/or electrical energy, for example by means of an electrical generator 40; a condenser 50 for liquefying the expanded working medium, in particular an air-cooled condenser 50; and a pump 60 for pumping the liquefied working medium to the evaporator.

The implementation is carried out according to Fig. 1 as follows. In the evaporator 20, the hot process fluid with the process temperature T _{Proz,out is cooled to the target temperature T Proz,} on, while the heat absorbed is used to evaporate the working medium in the ORC circuit. The live steam generated in this way is expanded while producing work in the expansion machine 30, whereby a generator 40, for example, can be driven. The exhaust steam is liquefied in the condenser 50 and is then available in liquid form at the pump 60. The pump 60 then brings the working medium back to the desired pressure. Through the device in Fig. 1 The previously used conventional air cooler of process 10 is replaced and additional useful power is generated. As explained above, however, due to the additional circuit of the working medium, the target temperature T _Proz,a cannot be as low as without the ORC circuit. Furthermore, in this first embodiment there is one The system does not have emergency running capability. This means that if the ORC system fails, the temperature T _Proz,off cannot be lowered and it cannot be cooled.

Variant 2A - Parallel connection

Fig. 2A shows a second embodiment 200 of the device not according to the invention. In this second embodiment 200 of the system, a cooler 70 (here an air cooler 70) is additionally provided for cooling at least part of the process fluid to be cooled. The system 200 includes a branch 71, which is provided, for example with respect to a flow direction of the process fluid, downstream of the outlet 11 and upstream of the inlet 21 for dividing the process fluid to be cooled into a first and a second partial flow of the process fluid, the branch 71 being in this Example includes a valve V. The system 200 further includes a merge 72, which is provided with respect to a flow direction of the process fluid downstream of the outlet 22 and upstream of the inlet 12 for combining the second partial flow of the process fluid cooled by the cooler 70 and the first partial flow of the process fluid cooled by the evaporator 20 is; wherein the branch 71 is designed to supply the first partial flow to the evaporator 20 and to supply the second partial flow to the cooler 70. Thus, with respect to the flow of the process fluid, a parallel connection of the components (evaporator 20, cooler 70) that remove heat from the process fluid is implemented. The cooler 70 is here formed in a structural unit with the condenser 50, and a common fan can be provided for air cooling.

The connection according to Fig. 2A thus solves the problem of emergency running properties. The bypass option (via valve V) of the ORC circuit ensures cooling if the ORC circuit fails. The target temperature T _Proz,in can be achieved by a partial flow bypassing the ORC circuit, being cooled directly in the air cooler (e.g.: V cooler, table cooler) and then being mixed back into the partial flow from the ORC evaporator 20. The electricity generated in the ORC circuit by the generator 40 can be used directly to supply the air cooler 70 (or the Combination of evaporator 50 and air cooler 70) can be used, whereby its electricity costs are significantly reduced, which in turn leads to increasing the economic efficiency of the cooler 70 (evaporator 50). In addition, with this connection it is possible to always achieve the target temperature T _Proz,on .

Fig. 2B represents a modification of the execution Fig. 2A in that the flow of ambient air is not as in Fig. 2A passes in parallel through the condenser 50 and the cooler 70, but one after the other first through the cooler 70 and then through the condenser 50. This has the advantage of a compact design, with the lowest air temperature being present at the cooler 70, so that a low temperature of the process fluid can be achieved while the cooling of the working medium in the condenser 50 is less effective.

Fig. 2C represents an alternative to the modification according to Fig. 2B Here, with regard to the air flow, the order of cooler 70 and condenser 50 is reversed, so that the ambient air first flows through the condenser 50 and then through the cooler 70. As a result, the lowest air temperature is present at the capacitor 50, so that higher electricity generation via the generator 40 is possible with the ORC circuit.

In the modifications according to Figures 2B and 2C remains the in relation to Fig. 2A described emergency running capability.

Variant 2B - Serial connection

Fig. 3 shows a third embodiment 300 of the device not according to the invention.

In the third embodiment, the cooler 70 is disposed downstream of the outlet 22 of the evaporator 20 and upstream of the inlet 12 of the heat generating device 10 with respect to a flow direction of the process fluid for further cooling the process fluid cooled by the evaporator. This creates a series connection of the components (evaporator 20, cooler 70), which remove heat from the process fluid. In a modified version, (similar to Embodiment according to Fig. 2 a valve may be provided which only leads part of the process fluid via the cooler 70.

The process fluid/water return from the ORC evaporator 20 is sent through the air cooler 70 to allow further cooling. In a further development, the heat input to the air cooler 70 can be regulated by intelligent control (for example with the help of the valve mentioned) in order not to cool down any further than necessary. The aim is to achieve the required T _process without consuming electricity. This is shown in the temperature-heat flow diagram Fig. 4 shown (TQ diagram).

If the cooling T ₁ that can be achieved through the ORC cycle process is above a required limit, a lower temperature T _proz,in can be achieved through additional cooling using water or air in the downstream cooler.

Variant 2C - Independent interconnection

Fig. 5 shows a fourth embodiment 400 of the device not according to the invention.

The fourth embodiment essentially corresponds to the second embodiment Fig. 2 . The difference is that the cooler 70 is provided separately from the condenser 50.

The advantage of this variant is that the ORC cooler (with components 20, 30, 40, 50, 60) and the air cooler (emergency cooler) 70 can be operated completely independently of each other and can provide emergency cooling for the process even if the ORC cooler fails is guaranteed. In addition, the systemic separation of the ORC cooler and the air cooler facilitates easy integration into existing cooling systems. After integration, the existing cooler acts as an emergency cooler and the ORC cooler acts as an additional module (“backpack module”) for retrofits or expansions.

Variant 3A - Parallel connection in the water circuit

Fig. 6 shows a fifth embodiment 500 of the device not according to the invention.

The fifth embodiment is essentially based on the second embodiment according to Fig. 2 .

According to the fifth embodiment, the system 500 for thermally connecting the condenser 50 and the cooler 70a, 70b, however, further comprises an intermediate circuit with a heat transfer fluid (here water), the capacitor 50 being provided for transferring heat from the expanded working medium to the heat transfer fluid and wherein the cooler 70a, 70b is provided for cooling the heat transfer fluid. For example, useful heat can be dissipated to a useful heat device 80 from a branch of the heat transfer fluid flowing from the condenser 50 to the cooler 70a, 70b.

Variant 3B - Serial connection in the water circuit

Fig. 7 shows a non-inventive sixth embodiment 600 of the device.

The sixth embodiment is based on the third embodiment according to Fig. 3 and was modified analogously to the fifth embodiment. The (chemical) composition of the heat transfer fluid is identical to the composition of the process fluid.

It is often difficult to integrate air coolers (e.g. table coolers) into existing systems due to their large installation area. The wiring variants 3A and 3B reduce this problem by inserting a further heat exchanger 75 and an intermediate circuit with a heat transfer fluid (e.g. water) between the ORC capacitor 50 and the cooler 70. This means that the installation locations of the heat source and the cooler are decoupled from each other and a great deal of flexibility is achieved when setting up the ORC process. Furthermore, the water intermediate circuit can supply additional heat consumers. Variants 3A and 3B can also be permuted with regard to the heat source and the heat sink.

Variant 4 - combination cooler - preheater - ORC

Fig. 8 shows a seventh embodiment 700 of the device not according to the invention.

According to the seventh embodiment 700 of the system according to the invention, a further heat exchanger 25 is provided, which is provided (with respect to a flow direction of the process fluid downstream of the evaporator 20) for transferring heat from the process fluid cooled by the evaporator 20 to a heat transfer fluid.

The system includes a valve 26 for regulating the mass flow of the heat transfer fluid through the further heat exchanger 25. Furthermore, by way of example, a temperature measuring device 27 is provided here for measuring the temperature of the process fluid downstream of the further heat exchanger 25, the control of the valve 26 depending on the measured temperature takes place. In this version, it is possible to reduce the temperature T _Proz,in to the same temperature level as without ORC by additionally using a partial flow of a cold process medium to be warmed up (heat transfer fluid, here water) for cooling. The heat is then removed in a first step by the ORC circuit. The pre-cooled heat-transferring process fluid then flows through the further heat exchanger 25 in which it is cooled down to the target temperature.

In order to set the target temperature, another partial flow of the cold process medium to be warmed up can be added to the process fluid in the flow direction after the further heat exchanger 25.

Variant 5 - 3-stage cooling of the heat-supplying medium

Fig. 9 shows a non-inventive eighth embodiment 800 of the device.

According to the eighth embodiment, a further evaporator 90 is provided between the outlet 22 and the inlet 12 for further evaporation of working medium from the process fluid using heat. In addition, a throttle valve 91 for lowering the pressure of the working medium in the further evaporator 90 and a liquid jet pump 92 and/or a steam jet pump 93 are arranged between the further evaporator 90 and the condenser 50 for lowering the pressure in the further evaporator 90, in particular a part of the liquefied working medium or part of the evaporated working medium serves as a propellant jet. This realizes a 3-stage cooling of the process fluid, as described below. The drawing shows both the version with the liquid jet pump 92 and with the steam jet pump 93. As a rule, only one of the two pumps is provided. With the liquid jet pump 92, the lower line after the pump 60 to the liquid jet pump 92 is required, while in the case of the vapor jet pump 93, the upper line is required for the working medium evaporated in the evaporator 20.

1st stage: Normal operation

After the heat has been released in the evaporator, the heat-supplying medium is returned to the process to be cooled.

2nd stage: cooling mode

A partial flow of the working medium is fed to the evaporator 90 via the throttle valve (throttle) 91. The throttle 91 is adjusted such that the pressure approximately corresponds to the pressure in the condenser 50. Due to the pressure reduction, the working medium in the evaporator 90 evaporates only minimally above the condensation pressure and the condensation temperature of the condenser 50, and thus enables the medium to be cooled to cool down to a temperature that is similarly low as the minimum achievable temperature in a direct heat exchanger to cool medium in air. In this way, even if the cooling system is retrofitted with an ORC system, you can ensure that the required temperatures of the medium to be cooled are maintained.

3rd stage: Throttling to a pressure below the condenser pressure

A liquid jet pump 92 or a vapor jet pump 93 lowers the pressure in the evaporator 90 to a pressure below the condensation pressure in the condenser 50. This can even achieve a lower boiling pressure than the condensation pressure in the condenser 50. As a result, the working medium is pumped with very little energy and raised back to the condensation pressure. The advantage here is that the working medium only has to be conveyed in small mass flows and with a small increase in pressure. Either part of the live steam or part of the feed fluid serves as a propellant jet.

Variant 6 - Expansion with an ORC module for existing coolers / without direct condensation

Fig. 10 shows a ninth embodiment 900 of the device corresponding to the present invention defined by independent claim 1.

According to this embodiment, the outlet 22 of the evaporator 20 is connected to an input 71 of the cooler 70, an output 72 of the cooler 70 is connected to an input 51 of the condenser 50 and an output 52 of the condenser 50 is connected to the input 12 of the heat-generating device 10. During operation, the process fluid is passed from the evaporator 20 through the cooler 70 for further cooling, then passed through the condenser 50 as a heat-absorbing medium and then again passed to the inlet 12 of the heat-generating device 10.

This connection solves the problem of emergency running properties because the cooler 70 is operated independently of the ORC circuit. Depending on the desired target temperature, the ORC circuit extracts heat, the necessary cooler performance is reduced and the downstream fan is relieved, which leads to a reduction in its maintenance intervals. This variant is characterized by its compactness (few components) and synergy effects of the common components. It can be used well to integrate existing cooling systems. In addition to evaporation, condensation also occurs in the ORC circuit against what is to be cooled Fluid takes place (in the other variants the condensation takes place against the ambient air).

Variant 7 - Expansion with an ORC module for existing coolers / with direct condensation

Fig. 11 shows a tenth embodiment 1000 of the device not according to the invention.

This embodiment is similar to the ninth embodiment 900 according to Fig. 10 , whereby the difference can be found in the capacitor 50 of the ORC circuit. In variant 7 shown here, direct condensation takes place between the ambient air and the ORC working medium. By structurally adapting the heat exchanger surfaces, the expansion of standard models in industry requires little effort. The measure differs depending on the cooler model.

Advantages/disadvantages of the systems described:

The following advantages can be mentioned: increasing operational safety (2 independent cooling systems, ORC + cooler); Use as many synergy components as possible from cooler and ORC; low maintenance; very good economic efficiency (saving of electrical energy); Reduction of CO ₂ emissions; Increase in efficiency (efficiency of the cooling process is increased, synergy effects between components). Furthermore, an existing cooler can be used to cool the ORC capacitor and with little design effort, a process that requires energy becomes an energy-neutral or energy-generating process.

The disadvantage is that adding additional components increases the complexity of the overall system (e.g. coordination of regulations, additional costs, additional interfaces,...).

The illustrated embodiments are merely exemplary and the full scope of the present invention is defined by the claims.

Claims (7)

1. System (200) for cooling a process fluid of a heat-producing apparatus (10), comprising:

   an outlet (11) of the heat-producing apparatus (10), the outlet (11) being provided for discharging process fluid to be cooled from the heat-producing apparatus (10);

   an inlet (12) of the heat-producing apparatus (10), the inlet (12) being provided for supplying cooled process fluid to the heat-producing apparatus (10); and

   a thermodynamic cycle device, in particular an ORC device, the thermodynamic cycle device comprising:

   an evaporator (20) having an inlet for supplying the process fluid to be cooled from the outlet (11) of the heat-producing apparatus (10) and having an outlet (22) for discharging the cooled process fluid to the inlet (12) of the heat-producing apparatus (10), wherein the evaporator (20) is adapted to evaporate a working medium of the thermodynamic cycle device by means of heat from the process fluid;

   an expansion machine (30) for expanding the evaporated working medium and for generating mechanical and/or electrical energy;

   a condenser (50) for liquefying the expanded working medium; and

   a pump (60) for pumping the liquefied working medium to the evaporator (20);

   wherein the system (200) further comprises a cooler (70) for cooling at least part of the process fluid to be cooled;

   characterized in that

   the outlet of the evaporator is connected to an inlet of the cooler, an outlet of the cooler is connected to an inlet of the condenser, and an outlet of the condenser is connected to the inlet of the heat-producing apparatus, so that in operation the process fluid is guided from the evaporator through the condenser for further cooling, is subsequently passed through the condenser as a heat-absorbing medium, and is in turn subsequently guided to the inlet of the heat-producing apparatus.
2. System according to claim 1, wherein the cooler is arranged downstream of the outlet of the evaporator with respect to a flow direction of the process fluid and upstream of the inlet of the heat-producing apparatus for further cooling the process fluid cooled by the evaporator.
3. System according to claim 1, wherein the cooler forms a structural unit with the condenser or is provided separately from the condenser.
4. System according to one of claims 1 to 3, further comprising a control device for controlling the heat input into the cooler, wherein in particular a set temperature of the process fluid returned to the inlet of the heat-producing apparatus can be achieved.
5. System according to one of claims 1 to 4, further comprising:
   a further heat exchanger (25) provided downstream of the evaporator with respect to a flow direction of the process fluid for transferring heat from the process fluid cooled by the evaporator to a heat transfer fluid.
6. System according to claim 5, further comprising:

   a valve (26) for controlling the mass flow of the heat transfer fluid through the additional heat exchanger;

   wherein preferably a temperature measurement device (27) is provided for measuring the temperature of the process fluid downstream of the further heat exchanger, wherein the control of the valve is effected depending on the measured temperature.
7. System according to one of claims 1 to 4, further comprising:

   a further evaporator (90) between the outlet of the evaporator and the inlet of the heat-producing apparatus for further evaporation of working fluid using heat from the process fluid;

   a throttle valve (91) for adjusting the size of a partial flow of the working medium through the further evaporator; and

   a liquid jet pump (92) or a vapor jet pump (93) between the further evaporator and the condenser for lowering the pressure in the further evaporator, wherein in particular a part of the liquefied working medium or a part of the evaporated working medium serves as a driving jet.

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