WO2008151730A1

WO2008151730A1 - Device and method for generating electricity from heat

Info

Publication number: WO2008151730A1
Application number: PCT/EP2008/004310
Authority: WO
Inventors: Hermann Helmbold; Franz Wimmer
Original assignee: Conpower Energieanlagen Gmbh & Co Kg
Priority date: 2007-06-14
Filing date: 2008-05-30
Publication date: 2008-12-18
Also published as: DE102007027349A1; DE102007027349B4; DE202007018628U1; EP2156019A1

Abstract

The invention relates to a device and a method for generating electricity from heat. Said device comprises a generator and a turbine that absorbs the dynamics of a moved medium, according to the preamble of claims 1 and 15. In order to do away with said mechanical drawbacks when the turbine and the generator are coupled to each other and be able to more effectively utilize power absorption and ultimately power conversion from the medium, the turbine (3) or the turbine wheel (11) and the generator (4) are arranged on a joint and/or jointly mounted shaft (A).

Description

Device and method for generating electricity from heat

The invention relates to a device and a method for generating electricity from heat, with a generator and the dynamics of a moving medium receiving turbine, according to the preamble of claim 1 and 15.

In the generation of electrical energy from the dynamics of a moving medium, the dynamics of the medium receiving turbine wheel is often connected via a gearbox with the power generator. This applies both to slow-running turbine wheels such as in the wind energy intake, but also in steam power plants. There are used equally gear for motion coupling. These should lead to a homogenization between turbine speed and generator speed by appropriate reduction or translation.

It is already known to dispense with a turbine-generator coupling in the case of a gas turbine to a gear arranged therebetween. Such a device is known from EP 1 367 690 B1 for a specific application.

The invention is therefore the object of a device of the generic type to that effect develop further that the coupling between the turbine and generator is free of said mechanical disadvantages, and the energy consumption and ultimately the energy conversion from the medium is more effectively usable.

The stated object is achieved according to the invention in a device of the generic type by the characterizing features of claim 1.

Further advantageous embodiments are specified in the dependent claims 2-14.

With regard to a method, the object is achieved according to the invention by the characterizing features of claim 15.

Further advantageous embodiments are given in the dependent dependent claims.

The core of the invention is that the turbine and the

Generator are arranged on a common and jointly mounted axis. This is a significant functional difference from the subject matter of the cited EP 1 367 690 B1 from which it is only known to rotate the axles and thus couple them with each other without transmission. However, in the prior art, this leads to the fact that each component, namely the generator and the turbine, each have a separately supported axis, which are coupled to one another by means of a single contact. However, since each axis is stored for itself, this leads to a mechanical over-determination of the bearing or support points. Thus, an absolute unbalance-free synchronization would only be achievable if the connection of the turbine axis and the generator axis rotationally rotatable, but axially balancing, ie axial Balancing would compensate. Although the connection would be gearless, but this axle compensation would be subject to wear and also swallows friction energy.

All of these disadvantages are eliminated by the construction according to the invention, in which the turbine and the generator are arranged on a common and jointly supported axis. Axis compensations are completely eliminated and only then is there an absolute smooth synchronization.

In a further advantageous embodiment, it is stated that the turbine is a radial centripetal turbine, which flows laterally to the axis of rotation with the medium and the medium in the axial direction can be centrally flowed out of the turbine. This is structurally particularly for compact systems of considerable advantage. Another advantage lies in the optimal efficiency of such a turbine wheel construction, which is provided with curved laterally approaching blades.

In a further advantageous embodiment, it is stated that the generator is a brushless, preferably a generator with permanent magnets. The friction resistances are significantly lower than with a generator with brushes.

Also advantageous is an embodiment in which the axis is mounted with magnetic or air bearings. This leads to a further reduction of the frictional resistance, which in turn increases the efficiency of energy conversion. Air bearings are sections on bearing shafts that are surface-textured. This leads to a higher speed Air cushion on which the bearing shaft or the supported shaft then runs.

All of these advantages already achieved correspond particularly well with an embodiment in which the turbine-generator arrangement according to the invention is integrated in a low-temperature ORC system. Here, the compact and extremely quiet turbine-generator arrangement and the measures to reduce friction losses are particularly effective.

In an advantageous embodiment, it is stated that the low-temperature ORC plant (Organic Rankine Cycle) also has at least one evaporator stage, at least one condensation stage, and a pump for returning the condensed medium from the condenser stage to the evaporator stage. Thus, all components are integrated in a closed circuit, in particular the turbine-generator arrangement works optimized.

A particular embodiment is that the pump is also arranged on the common and / or jointly mounted axis together with the generator and the turbine. The ORC system can be built extremely compact. For structural realization, only the wiring must be made accordingly, but this is completely easy. Due to the co-arrangement of the return pump for the circulating medium on the same axis as the turbine and generator, thus eliminating conversion losses of otherwise existing electrical components. The pump is mechanically taken directly to the power consumption of the impinged turbine. Overall, this increases the overall efficiency, which is clearly visible in the energy balance. In a further advantageous embodiment, it is stated that low-temperature evaporating fluorinated hydrocarbons are used as the medium. These media evaporate at room temperature or below. When the system is operated at an evaporation temperature well above room temperature, it works with good pressure values to generate an effective flow to the turbine.

A particularly advantageous material for use as a medium is 1, 1, 1,33-pentafluoro-propane.

Another equally useful alternative is butane as a medium.

In order to operate the ORC plant in an optimal ecological principle, i. with alternative energy sources for heating the evaporator, in one embodiment, the evaporator can be heated via a heat exchanger, which consists of a heat transfer medium (water or thermal oil)

Solar panels is operable. Systems of this kind even have an enormous utility value for private applications in residential buildings. Thus, the solar heat of conventional solar panels can at least partially exude the heat, and feed the electricity into the power grid. An inventive device according to this embodiment has a very good efficiency. It may be competitive with semiconductor solar cell systems as a combined facility for either low wattage or combined heat and power generation.

A further advantageous embodiment is that the evaporator can be heated via a heat exchanger, which in turn can be heated from waste heat. So the said device can also be used and used there be where energy is generated in the form of waste heat, which is then emitted via this ORC technological design.

In a further advantageous embodiment, it is stated that the evaporator and the solar collector or the solar panels have a common closed medium circuit, such that the evaporator medium can be heated directly without heat exchanger in the tubes of the solar panels. As a result, there is no need for a heat exchanger, because in the tubes of the solar panels no more water, but already the evaporator medium flows and the temperature is absorbed directly. Make sure that the pipes are designed for the pressure and are leak-proof. By eliminating the evaporator heat exchanger efficiency is further increased because the thermal energy losses omitted.

A last advantageous embodiment is that while the capacitor stage is designed as a tube bundle or as a kind of heat sink with a folded surface through which the heat transfer to the environment, to a house heating, in a district heating network or in a heat storage can be issued.

In other words, the cooling of the capacitor is carried out by heat exchange with the environment, or in the manner specified above.

A device of this type has a considerable benefit in terms of climate-friendly energy production.

With regard to a method of the generic type, the essence of the invention is that the evaporation temperature T2 in the evaporator during operation between 50 ⁰ C and 130 ⁰ C and is set, and that after passing through the medium through the turbine, a cooling by at least 30 K takes place.

In a further embodiment of the invention

Method is specified that the evaporation temperature T2 is preferably set at about 70 ⁰ C.

In a further advantageous embodiment, a temperature control is specified, in which the

Condensation cooling in the condenser is cooled by a heat exchanger approximately to the return temperature Tl of the medium to the evaporator, such that the temperature differences .DELTA.T between return temperature Tl and evaporator temperature T2, are the same in both directions.

In the last advantageous embodiment, it is stated that the waste heat produced in the condensation cooling is used as heating energy or is separately nachverstromt on the temperature level obtained.

The invention is illustrated in the drawing and explained in more detail below.

It shows:

Figure 1: embodiment with turbine and generator on one axis.

Figure 2: Radial centripetal turbine.

FIG. 3: exemplary embodiment with turbine,

Generator and recirculation pump on one axis. Figure 4: embodiment with integration of the evaporator stage directly in solar panels.

Figure 1 shows a first embodiment in which the turbine of the turbine 3 are arranged with the generator on a physically common axis A. It should be noted here that, in contrast to the prior art described above, the turbine and the

Generator does not have two separate axes, which are coupled with each other. Because this leads to a bearing over-determination and thus to a LaufrüheStörung of these two components. According to the invention, the extended axis A of the

Generator 4 one with the axis of the turbine 3 and the turbine wheel 11. Thus, the device is extremely smooth running and the coupling leads to the efficiency of the entire device increasing technical measure. The turbine wheel of the turbine 3 is using the effluent from the evaporator 1 evaporator medium, in this example

1, 1, 1, 33-pentafluoro-propane, which is brought in the evaporator by supplying heat via the evaporator heat exchanger 40 to an evaporation temperature Tl and the

Turbine wheel of the turbine 3 flows. The so-flowed turbine wheel absorbs this energy and through the rotationally fixed connection via the common axis A with the generator 4, and the rotor of the generator 4, this is driven. The generator is designed, for example, as a brushless permanent-magnet-excited generator. The generated electrical energy is then at the output 10. The turbine 3 is equipped as a radial centripetal turbine with a turbine wheel 11 shown in more detail later in FIG. 2, in which the medium flows tangentially onto the turbine wheel 11 and is then centrally discharged by means of a corresponding lamination. The medium flows into a condenser 2, which cools down the medium again via a heat exchanger 7. The heat absorbed in turn can be used again, or nachverströmt, or recycled.

The cooled and condensed medium is cooled down to a condensation temperature of T2 and pumped via a return pump 5 back into the evaporator 1. This is externally supplied with heat and the process then continues. This means that the medium is in a closed cycle.

At the heat exchanger 7, a coolant is passed through a heat exchanger pipe at a low temperature. The heat absorbed by the heat exchanger 7 is either used or recycled in the said manner.

Via a control valve 6, the cycle is regulated in total.

Generator 4 and turbine 3 can also be housed in an assembly 20.

An exemplary temperature control will vary depending on the pressure and medium used, such that T1, i. the

Output temperature is about 70 ⁰ C, in the condenser 2 then back to T2, that is cooled down about 40 ⁰ C and condensed, and at about this temperature level of T4 = T2 is approximately returned to the evaporator 1. At the entrance of the heat exchanger 7, a coolant is supplied at about T3 equal to 10 ⁰ C and discharged to about T4 equal to 40 ⁰ C again.

Figure 2 shows in detail, but only schematically the

Turbine wheel 11. This is flowed at the edge in approximately tangential to the vaporized medium. The medium is conducted through the lamellar guide to the center of the turbine wheel and can flow out there centrally, before it is then fed to the capacitor as in Figure 1.

FIG. 3 shows a particularly advantageous embodiment, in which not only generator 4 and turbine 3 or turbine wheel 11 and rotor are arranged on a common physical axis A, but additionally the

Return pump 5. This has not only the advantage that the energy for the return pump 5 is applied directly from the generated mechanical energy of the turbine wheel, which further increases the efficiency, but the design of the entire device is characterized even more compact.

It can, as indicated here, the entire assembly turbine, generator and return pump are placed upright between the evaporator 1 and capacitor 2. Due to the more compact design are only short

Media lines necessary, which reduces heat losses and thus also increases the efficiency again. In addition, there is a small-scale device.

Figure 4 shows an embodiment in which instead of a separate evaporator 1, the bottom side as shown in Figure 1 thermal energy must be supplied through the evaporator heat exchanger 40, instead now the evaporator 30 is integrated into the tubes of a solar collector immediately. The tubes of the solar collector must be installed only pressure resistant and designed so that the absorbed solar energy, the medium, for example, the said penta-fluoropropane is immediately evaporated in the tubes of the solar collector 30, and the steam is then fed directly to the turbine.

The further embodiment can then be formed again according to FIG. 1 or FIG. In both cases, the evaporator 1 need only be exchanged for a pressure-resistant solar collector 30.

In all embodiments, the bearings of the common axis may also be magnetic or air bearing, which both increases the smoothness, and greatly reduces the friction losses. Overall, this feature also increases the achievable in the overall process efficiency.

The use of butane or penta-fluoro-propane are exemplary only. Possible are all media with correspondingly low boiling point.

Reference numerals;

1 evaporator 2 condenser

3 turbine

4 generator

5 pump, return pump

6 control valve 7 heat exchanger

10 output of electrical energy

11 turbine wheel

20 assembly

30 solar panel

40 evaporator heat exchanger

A axis

Tl outlet temperature evaporator

T2 Return temperature to evaporator T3 Input temperature heat exchanger

T4 outlet temperature heat exchanger

Claims

claims

1. A device for generating electricity from heat, with a generator and the dynamics of a moving medium receiving turbine, wherein the

Turbine and the generator are gearless coupled together, characterized in that the turbine (3) or the turbine wheel (11) and the generator (4) on a common and / or jointly mounted axis (A) are arranged.

2. Device according to claim 1, characterized in that the turbine (3) has a radial centripetal

Turbine is, which flows laterally to the axis of rotation with the medium and the medium in the axial direction can be flowed out of the turbine centrally.

3. Device according to claim 1 or 2, characterized in that the generator (4) is a brushless, preferably a generator with permanent magnets.

4. Device according to one of the preceding claims, characterized in that the axis (A) is mounted with magnetic or air bearings.

5. Device according to one of the preceding claims, characterized in that the turbine-generator assembly is integrated in a low-temperature ORC system.

6. Device according to claim 5, characterized in that the low-temperature ORC plant also at least one evaporator stage (1), at least one condensation stage (2), and a pump (5) for returning the condensed medium from the condenser stage (2) Evaporator stage (1).

7. Device according to claim 6, characterized in that the pump (5) also on the common and / or jointly Axis A along with the generator (4) and the turbine (3) or the turbine wheel (11) of the turbine (3 ) is arranged.

8. Device according to one of the preceding claims, characterized in that are used as medium low-temperature vaporizing fluorinated hydrocarbons.

9. Device according to claim 8, characterized in that 1, 1, 1, 33-pentafluoro-propane is used as the medium.

10. Device according to claim 8, characterized in that butane is used as the medium.

11. Device according to one of the preceding claims

1 to 10, characterized in that the evaporator (1) is heatable via a heat exchanger which is operable from a heat transfer medium (water or thermal oil) from solar panels.

12. Device according to one of the preceding claims 1 to 10, characterized in that the evaporator (1) can be heated via a heat exchanger, which in turn can be heated from waste heat.

13. Device according to one of the preceding claims 1 to 10, characterized in that the evaporator (1) and the solar collector (30) or the solar panels have a common closed medium circuit, such that the evaporator medium without heat exchanger directly in tubes of the solar panels (30) is heatable.

14. The device according to claim 13, characterized in that in this case the capacitor stage (2) is designed as a tube bundle or as a kind of heat sink with a folded surface over which the heat transfer to the environment, vornehmbar to a house heating, in a district heating network or in a heat storage is.

15. A method of operating a device according to any one of claims 1 to 14, characterized in that the evaporation temperature T2 in the evaporator in operation between 50 ⁰ C and 13O ⁰ C is set and adjusted, and that after passing through the medium through the turbine cooling about 30 K takes place.

16. The method according to claim 15, characterized in that the evaporation temperature T2 is preferably set at about 70 ⁰ C.

17. The method according to claim 15 or 16, characterized in that the condensation cooling in the condenser via a heat exchanger in about the

Return temperature Tl of the medium to the evaporator is cooled, such that the

Temperature differences ΔT between return temperature Tl and evaporator temperature T2, are the same in both directions.

18. The method according to any one of claims 15 to 17, characterized in that the heat generated during the condensation cooling waste heat is used as heating energy or nachverstromt separately on the temperature level obtained.