JP5592305B2 - Power generator - Google Patents

Description

  The present invention relates to a power generator, and more particularly to a power generator using a Rankine cycle.

  In recent years, from the viewpoint of energy saving, there is an increasing need for a power generation apparatus that recovers so-called “waste heat” from various facilities such as factories and generates power using the recovered “waste heat” energy. . Since “exhaust heat” is often not high enough to generate steam for driving a steam turbine used in a general power generator, a power generator capable of generating power with low-temperature heat is required.

  As such a power generator, an evaporator that evaporates a low-boiling working medium, for example, as described in Patent Document 1, and an expander such as a turbine that drives the generator by causing the working medium vapor to perform expansion work And a Rankine cycle heat engine that circulates the working medium in a closed loop in which a condenser for condensing the working medium vapor and a circulation pump for pressurizing the working medium and re-supplying the working medium are connected in series. Binary power generators are known.

  In such a binary power generator, the circulation pump is usually driven by an electric motor. Therefore, in order to increase the efficiency of the entire power generation apparatus, it is necessary to maintain the efficiency of the motor of the circulation pump high. The electric motor generates heat due to its power loss, but the efficiency decreases when the temperature rises excessively, so it needs to be cooled.

  In general thermal cycles, a part of a low-temperature operating medium is diverted and inserted into the motor to cool the motor. In the Rankine cycle heat engine, the electric motor can be cooled by supplying a part of the working medium condensed by the condenser and discharged by the circulation pump to the electric motor.

  However, in this case, the working medium that has cooled the electric motor has a pressure drop due to pressure loss in the electric motor, so that it can no longer be supplied to the downstream side of the circulation pump and thus to the evaporator. Therefore, the working medium that has cooled the electric motor can only be circulated to the upstream side of the condenser, which causes a problem that the flow rate of the working medium that drives the expander decreases. In this case, the heat received by the heat medium from the electric motor is also discarded by the condenser.

Japanese Patent Laid-Open No. 10-103030

  In view of the above problems, an object of the present invention is to provide a power generation apparatus that recovers heat by cooling an electric motor of a circulation pump and can be used for power generation.

In order to solve the above-mentioned problem, a first aspect of the power generator according to the present invention is to expand the working medium by a heating medium supplied from the outside in the evaporator, and use the evaporated working medium as an expander connected to the generator. Introducing and generating power by driving the generator by converting the thermal expansion force of the working medium into rotational force in the expander, introducing the working medium discharged from the expander into the condenser, and condensing condensed by cooling the working medium by the cooling medium supplied from the outside in the vessel, the condensed working medium to the evaporator is pressurized by a circulation pump in the power generator resupplying, of the working medium in which the circulation pump is discharged the part shall be supplied to the evaporator through a motor for driving the circulation pump.

Further, the second aspect of the power generator according to the present invention is such that the working medium is evaporated by a heating medium supplied from the outside in the evaporator, and the evaporated working medium is introduced into an expander connected to the generator, so that the expansion is performed. The generator is driven to generate electric power by converting the thermal expansion force of the working medium into rotational force in the machine, the working medium discharged from the expander is introduced into the condenser, and is supplied from the outside in the condenser. that the cooling medium to cool the working medium is condensed, in the re-supplying power generator the condensed working medium to the evaporator is pressurized by a circulation pump, the part of the working medium condensed in the condenser, the circulating The circulating pump is sucked through an electric motor that drives the pump.

In the power generation apparatus of the first and second aspects of the present invention, part of the working medium circulating in the Rankine cycle, so it passes through the electric motor of the circulation pump, to supply the working medium and the electric motor is cooled to the evaporator it can. Thereby, the thermal energy recovered from the electric motor can also be used to drive the expander, so that the thermal efficiency is high.

It is a block diagram of the electric power generating apparatus of the reference example 1. FIG. It is a block diagram of the electric power generating apparatus of the reference example 2. FIG. It is a lineblock diagram of the power generator of a 1st embodiment of the present invention. It is a block diagram of the electric power generating apparatus of 2nd Embodiment of this invention.

Embodiments of the present invention will now be described with reference to the drawings. First, FIG. 1 shows a configuration of a power generator 1 of Reference Example 1 . The power generation apparatus 1 includes a working medium (for example, a CFC-based heat medium such as R245fa) in a closed channel in which an evaporator 2, a screw expander 4 to which a generator 3 is connected, a condenser 5 and a circulation pump 6 are interposed. ) Is a binary power generation system consisting of a Rankine cycle heat engine.

  The evaporator 2 is a heat exchanger that evaporates the working medium by exchanging heat with a heating medium (for example, steam collected from a well or steam produced by a boiler) supplied from a heat source outside the apparatus.

  The working medium evaporated in the evaporator 2 is introduced into the screw expander 4 to which the generator 3 is connected, and is expanded in the screw expander 4 to rotate the screw expander 4 and rotate the generator 3. To generate electricity. The working medium that is expanded by the screw expander 4 and discharged in a state where the pressure is reduced is introduced into the condenser 5.

  The condenser 5 is a heat exchanger that cools and condenses the working medium by exchanging heat with a cooling medium (for example, cooling water supplied from a river or a cooling tower) supplied from a cooling source outside the power generation apparatus 1. .

  The working medium condensed into a liquid in the condenser 5 is pressurized by the circulation pump 6 and re-supplied to the evaporator 2. The working medium discharged from the circulation pump 6 is entirely in the circulation pump 6. It passes through the electric motor 7 that drives, and is re-supplied to the evaporator 2.

  Since the circulation pump 6 needs to be pressurized to a predetermined pressure, the circulation pump 6 is preferably a non-positive displacement pump such as a centrifugal pump provided with an impeller as a rotor, or a positive displacement pump such as a gear pump. Further, the rotation speed of the electric motor 7 may be controlled. For example, the heat energy of the working medium supplied to the screw expander 4 is kept constant by feedback-controlling the rotation speed of the electric motor 7 so that the liquid level of the working medium in the evaporator 2 is kept constant. be able to.

In this reference example 1 , since the entire amount of the working medium is re-supplied to the evaporator 2 through the electric motor 7, the electric motor 7 is cooled by the working medium cooled by the condenser 5, thereby preventing a decrease in efficiency due to overheating of the electric motor 7. it can.

  Further, since the working medium supplied to the evaporator 2 recovers thermal energy from the electric motor 7 by cooling the electric motor 7, thermal energy necessary for evaporating the working medium in the evaporator 2 correspondingly. Is less. That is, the amount of power generation can be increased by increasing the circulating flow rate of the working medium that drives the screw expander 4 by the amount of thermal energy recovered from the electric motor 7.

  In the electric motor 7, the working medium may flow through an internal space that houses the stator and the rotor, or the working medium may flow through a jacket provided in the casing.

Next, FIG. 2 shows a configuration of the power generation device 1a of Reference Example 2 . In the description of the present embodiment 2, the same components as in Reference Example 1 is omitted and the same reference numerals, and redundant description.

In the power generator 1a of the present reference example 2 , the entire amount of the working medium condensed by the condenser 5 is sucked into the circulation pump 6 through the electric motor 7, and the working medium discharged by the circulation pump 6 is directly supplied to the evaporator 2. It comes to be supplied.

Similarly to the power generation device 1 of the first reference example , the power generation device 1a of the second reference example prevents a reduction in efficiency due to overheating of the electric motor 7 and uses the thermal energy obtained by cooling the electric motor 7 for driving the screw expander 4. Power generation efficiency is high.

The total amount of the working medium discharged from the circulation pump 6 in the power generation apparatus 1 of Reference Example 1 described above, and the total amount of the working medium condensed in the condenser 5 in the power generation apparatus 1a of Reference Example 2 passes through the motor 7. However, only part of each working medium may pass through the electric motor 7.

For example, FIG. 3 shows a configuration of the power generation device 1b according to the first embodiment of the present invention. The present embodiment has almost the same configuration as the power generation device 1 of Reference Example 1 described above, but in addition to the configuration of the power generation device 1, the upstream and downstream flow paths of the motor 7 are connected and the orifice 8 is interposed. A bypass channel 9 is provided.

  Although there is a slight risk of power loss inside the electric motor 7 due to the working medium passing through the electric motor 7, not only the entire amount of the working medium discharged by the circulation pump 6 but also a part of it is transferred to the electric motor 7. By configuring to communicate, it is possible to reduce the power loss.

In FIG. 4, the structure of the electric power generating apparatus 1c of 2nd Embodiment of this invention is shown. In this embodiment, in addition to the configuration of the power generation apparatus 1a of Reference Example 2 , a bypass flow path 9 that connects the upstream and downstream flow paths of the electric motor 7 and has an orifice 8 interposed therebetween is also provided. Also in the present embodiment, it is possible to reduce power loss by configuring not only the entire amount of the working medium condensed by the condenser 5 but also a part thereof to the electric motor 7.

  Instead of the orifice 8 interposed in the bypass flow path 9, an on-off valve or a flow rate adjustment valve whose opening degree can be adjusted may be provided. By opening / closing control of the opening / closing valve and the flow rate adjusting valve, it is possible to appropriately change the flow rate of the working medium that communicates with the electric motor 7 and the flow rate of the working medium that passes through the bypass passage 9 without passing through the electric motor 7.

DESCRIPTION OF SYMBOLS 1, 1a, 1b, 1c ... Power generation device 2 ... Evaporator 3 ... Generator 4 ... Screw expander 5 ... Condenser 6 ... Circulation pump 7 ... Electric motor 8 ... Orifice 9 ... Bypass flow path

Claims (2)

In the evaporator, the working medium is evaporated by a heating medium supplied from the outside, the evaporated working medium is introduced into an expander connected to a generator, and the thermal expansion force of the working medium is converted into a rotational force in the expander. Thus, the generator is driven to generate electric power, the working medium discharged from the expander is introduced into a condenser, and the working medium is cooled and condensed by a cooling medium supplied from the outside in the condenser, and condensed. In the power generation device that pressurizes the working medium with a circulation pump and re-supplies it to the evaporator,
Power generator, characterized in that the circulation pump is a part of the discharged working medium is supplied to the evaporator through a motor for driving the circulation pump. In the evaporator, the working medium is evaporated by a heating medium supplied from the outside, the evaporated working medium is introduced into an expander connected to a generator, and the thermal expansion force of the working medium is converted into a rotational force in the expander. Thus, the generator is driven to generate electric power, the working medium discharged from the expander is introduced into a condenser, and the working medium is cooled and condensed by a cooling medium supplied from the outside in the condenser, and condensed. In the power generation device that pressurizes the working medium with a circulation pump and re-supplies it to the evaporator,
Power generator for causing sucked part of the working medium condensed in the condenser, the circulating pump through the motor for driving the circulation pump.

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