JP5910122B2 - Heat recovery generator - Google Patents

Description

  The present invention relates to a heat recovery power generation apparatus that generates power using recovered heat.

  The following Patent Document 1 discloses a rotor in which a heat exchanger (evaporator) that generates heat by exchanging heat between a predetermined heat source and a supplied refrigerant and a turbine that obtains rotational force by supplying steam are connected. A generator that condenses the vapor that has passed through the turbine and liquefies the generator, and a part of the refrigerant that is supplied from the condenser to the heat exchanger is supplied to the generator for cooling. A generator system is disclosed that includes an apparatus and a first refrigerant supply device that supplies the refrigerant having passed through the generator and recovered heat to the evaporator. Such a generator system improves the overall efficiency of the system by diverting the refrigerant to cool the generator.

JP 2011-106316 A

  By the way, the generator cooling device in the said generator system cools a generator by vaporizing a refrigerant | coolant with the heat | fever of a generator. That is, in this generator cooling device, the heat of vaporization of the refrigerant is used for cooling the generator. Moreover, in the said generator system, the structure which supplies the refrigerant | coolant vaporized with the generator to an evaporator, and heat-exchanges with a heat source is employ | adopted.

  However, in such a configuration of the prior art, the refrigerant (gas) vaporized by the evaporator and the refrigerant vaporized by the heat of the generator are mixed. At this time, when the refrigerant vaporized by the heat of the generator is lower than the heat source, the temperature of the refrigerant vaporized by the heat source may be lowered in the evaporator. This is because the heat source temperature may change or the amount of heat generated may change depending on the power generation state. Moreover, since the refrigerant in the gas-liquid mixed state is exchanged with the heat source, the heat exchange efficiency is deteriorated. Under such circumstances, the generator system has a problem that the efficiency of heat recovery from the heat source, which is the most important performance item, is not always sufficient.

  This invention is made | formed in view of the situation mentioned above, and aims at improving the heat recovery efficiency from a heat source rather than before.

  In order to achieve the above object, the present invention uses, as a first solution, an evaporator that vaporizes a liquid working medium by heat exchange with a heat source, and a vaporized working medium supplied from the evaporator. An expansion turbine generator that generates electric power, a condenser that condenses the vaporized working medium discharged from the expansion turbine generator, and a pump that discharges the liquid working medium from the condenser and supplies the working medium to the evaporator A power converter that converts power output from the expansion turbine generator, and a generator cooler that cools the expansion turbine generator by using a liquid working medium. A means is adopted in which the flow rate of the supplied working medium in a liquid state is set to a flow rate that is not vaporized by the generator cooler.

  As a second solving means, in the first solving means, further comprising a power converter cooler that cools the power converter using a working medium in a liquid state, and the liquid state supplied to the power converter cooler The means that the flow rate of the working medium is set to a flow rate that is not vaporized by the cooler for the power converter is adopted.

  As a third solution, in the second solution, a part of the liquid working medium supplied from the pump to the evaporator is individually supplied to the generator cooler and the power converter cooler. Adopt the means.

  As a fourth solution, in any one of the first to third solutions, a thermometer for measuring the temperature of the expansion turbine generator and a thermometer so that the temperature of the expansion turbine generator maintains the target temperature. And a control valve that adjusts the flow rate of the liquid working medium supplied to the generator cooler based on the measured value.

  According to the present invention, since the flow rate of the liquid working medium supplied to the generator cooler is set to a flow rate that does not vaporize in the expansion turbine generator, the vaporized refrigerant (gas) and the condenser in the evaporator The heat recovery efficiency from the heat source can be improved in comparison with the prior art in which the refrigerant (liquid) supplied from the heat exchanger exchanges heat with the heat source.

It is a system configuration figure showing the functional composition of the heat recovery power generator concerning one embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the waste heat recovery power generator according to this embodiment includes an evaporator 1, an expansion turbine generator 2, a condenser 3, a reservoir tank 4, a pump 5, a control valve 6, and an AC-DC converter 7. And a DC-AC converter 8. Among these devices, the expansion turbine generator 2 is a main machine of the present waste heat recovery power generation apparatus, and the other is an auxiliary machine for the main machine.

  The waste heat recovery power generation device is a device that recovers thermal energy of waste gas as electric energy (three-phase AC power). This waste heat recovery power generation device is provided in a facility such as a factory, for example, and generates three-phase AC power having the same specifications as commercial power from waste gas generated at the facility of several hundred degrees Celsius. This three-phase AC power is fed to each part of the facility and consumed. That is, this waste heat recovery power generation apparatus is provided in the facility in order to improve the overall energy efficiency of the facility.

  The evaporator 1 is a kind of heat exchanger that vaporizes a working medium by heat exchange with the waste gas (heat source). In this evaporator 1, a flow path through which waste gas (gas) circulates and a flow path through which a working medium circulates are provided adjacent to and opposed to each other, and the heat of the waste gas on the high temperature side is on the low temperature side. Conducts efficiently to the working medium. The working medium is a fluorine-based medium having a boiling point of 100 ° C. or less (for example, about 80 ° C.) and is vaporized by the heat of waste gas. In such an evaporator 1, the vaporized working medium (gas medium MG) whose pressure has been increased by vaporizing the liquid working medium (liquid medium ML) supplied from the pump 5 is supplied to the expansion turbine generator 2. Supply.

  The expansion turbine generator 2 generates three-phase AC power using the vaporized working medium supplied from the evaporator 1. The expansion turbine generator 2 includes a turbine 2a, a generator 2b, a cooling jacket 2c, and a temperature sensor 2d (thermometer) as shown in the figure, and is configured, for example, in a substantially cylindrical shape as a whole.

  The turbine 2 a is a rotating machine that is driven by the gas medium MG supplied from the evaporator 1. That is, the turbine 2a includes a receiving port for receiving the gaseous medium MG from the evaporator 1, an outlet for discharging the gaseous medium MG to the condenser 3, a turbine impeller whose shaft (turbine shaft) is coupled to the generator 2b, and the like. The turbine impeller is rotated by spraying the gas medium MG onto the turbine impeller. Such a turbine 2a is provided, for example, in the upper part of the substantially cylindrical expansion turbine generator 2, and is axially coupled to, for example, a substantially cylindrical generator 2b provided in the lower part.

  The generator 2b is a rotating machine that is driven by the rotational power of the turbine 2a to generate three-phase AC power. That is, the generator 2b is coupled to the turbine shaft of the turbine 2a and includes a substantially cylindrical rotor (field) and a stator (armature winding) provided in an annular shape on the outer periphery of the rotor. It is configured. In such a generator 2b, an electromotive force is generated in the stator (armature winding) when the rotor (field) is rotationally driven by the turbine 2a. The three-phase AC power output from the generator 2b is different in frequency or / and output voltage from commercial power (system power) specifications.

  The cooling jacket 2c is provided so as to cover the entire outer periphery of the cylindrical generator 2b, and cools the generator 2b using the liquid medium ML. In other words, the cooling jacket 2c includes a receiving port for receiving the liquid medium ML and a discharge port for discharging the liquid medium ML, and transfers the heat of the generator 2b to the liquid medium ML to cool the generator 2b. To do. Since such a cooling jacket 2c is provided adjacent to the outer periphery of the generator 2b, that is, adjacent to the stator (armature winding), the stator that generates the most heat during operation can be cooled particularly effectively.

  Here, the flow rate of the liquid medium ML received by the cooling jacket 2c is set to a flow rate at which the liquid medium ML discharged from the cooling jacket 2c is not vaporized. Details of such flow rate setting will be described later. The temperature sensor 2d detects the internal temperature of the generator 2b, for example, the temperature of the part (stator winding) where the temperature is highest. Such a temperature sensor 2 d is, for example, a thermocouple, and outputs a measured value to the control valve 6.

  The condenser 3 is a kind of heat exchanger that condenses (liquefies) the gaseous medium MG received from the turbine 2a using cooling water. In the condenser 3, the flow path through which the gas medium MG flows and the flow path through which the cooling water flow are provided adjacent to and opposed to each other, and the heat of the gas medium MG on the high temperature side is on the low temperature side. Conducts efficiently to water. The cooling water is, for example, about 30 to 40 ° C. water discharged from a cooling facility in a factory. Such a condenser 3 changes the state of the gaseous medium MG to the liquid medium ML and supplies it to the reservoir tank 4.

  The reservoir tank 4 is a container that temporarily stores the liquid medium ML, and is appropriately provided as necessary. The pump 5 discharges the liquid medium ML from the reservoir tank 4 and supplies it to the evaporator 1, the cooling jacket 2c, and two coolers 7b and 7c described later. That is, the pipe connected to the discharge port of the pump 5 is branched into three as shown in the figure. The first branch pipe (main pipe) is connected to the evaporator 1 and the second branch pipe (sub pipe) is connected. The cooling jacket 2c and a third branch pipe (sub pipe) are connected to the two coolers 7b and 7c, respectively. Most of the liquid medium ML discharged from the pump 5 is supplied to the evaporator 1 through such a pipe, but a part of the liquid medium ML is supplied to the cooling jacket 2c and the two coolers 7b and 7c through the pipe. And distributed. The pump 5 is rotationally driven by, for example, an electric motor.

  Here, the discharge flow rate of the pump 5 is set such that the cooling jacket 2c and the two coolers 7b and 7c are set to a necessary amount (first necessary amount) corresponding to the amount of waste heat in the evaporator 1 (that is, the amount of heat per unit time). The flow rate is set in consideration of the amount necessary for cooling to the predetermined target temperature (second necessary amount). The second required amount, that is, the flow rate of the liquid medium ML supplied from the pump 5 to the cooling jacket 2c and the two coolers 7b and 7c, respectively, is the same as the liquid medium ML in the cooling jacket 2c and the two coolers 7b and 7c. It is set above the minimum flow rate that does not vaporize.

  That is, in the cooling jacket 2c and the two coolers 7b and 7c, when the flow rate of the liquid medium ML is small, a part of the liquid medium ML is vaporized, but the flow rate of the liquid medium ML is secured to a certain amount or more (minimum flow rate or more). If so, the liquid medium ML accepts heat as a liquid without vaporization. Such a minimum flow rate depends on the performance of the liquid medium ML as a heat medium, the heat generation amount of the cooling jacket 2c or the two coolers 7b and 7c, etc., but can be estimated as a design value.

  The control valve 6 is an adjustment valve or an ON / OFF valve that adjusts the flow rate of the liquid medium ML discharged from the cooling jacket 2c based on the measured value of the temperature sensor 2d. That is, the control valve 6 adjusts the flow rate of the liquid medium ML used for cooling the expansion turbine generator 2 (main machine). As shown in the drawing, the outlet of the cooling jacket 2c and the first branch pipe It is provided in a pipe that connects According to such a control valve 6, the discharge flow rate (= inflow flow rate) of the liquid medium ML from the cooling jacket 2c is adjusted so that the internal temperature of the generator 2b maintains a predetermined target temperature. As described above, the flow rate (inflow rate) is adjusted in a flow rate region equal to or higher than the minimum flow rate at which the liquid medium ML does not vaporize.

  The AC-DC converter 7 and the DC-AC converter 8 are three-phase AC power (for example, 50/60 Hz, 200 V class) in which the three-phase AC power generated by the generator 2b is adapted to the specifications of commercial power (system power). Is to convert to Of the AC-DC converter 7 and the DC-AC converter 8, the previous-stage AC-DC converter 7 converts the three-phase AC power input from the generator 2 b into DC power and converts it into DC-AC. Output to the converter 8. The subsequent DC-AC converter 8 converts the DC power into three-phase AC power that conforms to the specifications of commercial power (system power).

  Such an AC-DC converter 7 includes an AC-DC conversion circuit 7a and a cooler 7b. The AC-DC conversion circuit 7a is a main body of the AC-DC converter 7, and is a power circuit that rectifies the three-phase AC power of the generator 2b and converts it into DC power. The cooler 7b cools the AC-DC conversion circuit 7a using the liquid medium ML supplied via the third branch pipe. In other words, the cooler 7b includes a receiving port that receives the liquid medium ML and a discharge port that discharges the liquid medium ML. The cooler 7b transfers the heat of the AC-DC conversion circuit 7a to the liquid medium ML to generate AC− The DC conversion circuit 7a is cooled.

  The DC-AC converter 8 includes a DC-AC conversion circuit 8a and a cooler 8b. The DC-AC conversion circuit 8a is the main body of the DC-AC converter 8, and converts the DC power input from the AC-DC conversion circuit 7a into three-phase AC power that conforms to the specifications of commercial power (system power). Power circuit. The cooler 8b cools the AC-DC conversion circuit 7a using the liquid medium ML supplied in parallel with the cooler 7b via the third branch pipe. In other words, the cooler 7b includes a receiving port that receives the liquid medium ML and a discharge port that discharges the liquid medium ML. The cooler 7b transfers the heat of the AC-DC conversion circuit 7a to the liquid medium ML to generate AC− The DC conversion circuit 7a is cooled.

  In addition, the liquid medium ML discharged from the cooling jacket 2c, the cooler 7b of the AC-DC converter 7 and the discharge port of the cooler 8b of the DC-AC converter 8 is connected to the first branch pipe as shown in the figure. It joins the flowing liquid medium ML and is supplied to the evaporator 1. That is, a part of the liquid medium ML discharged from the pump 5 is supplied to the cooling jacket 2c and the two coolers 7b and 8b, heated so as to keep the liquid body, and supplied to the evaporator 1.

Next, the operation of the waste heat recovery power generator configured as described above will be described in detail.
First, the power generation operation (main operation) of the waste heat recovery power generation apparatus will be described. In the waste heat recovery power generation apparatus, the working medium circulates in the order of the evaporator 1 → the expansion turbine generator 2 → the condenser 3 → the reservoir tank 4 → the pump 5 → the evaporator 1, and the liquid medium ML and the gas medium MG. The expansion turbine generator 2 generates power by changing the state.

  That is, the gaseous medium MG generated in the evaporator 1 by the heat of the waste gas is supplied to the expansion turbine generator 2 and then converted into the liquid medium ML by the cooling water in the condenser 3, and the liquid medium ML is The state is supplied to the evaporator 1 through the reservoir tank 4 and the pump 5 and is converted into a gaseous medium MG. In the process of the cyclic state change of the working medium, power is generated by the expansion turbine generator 2 by the action of the gas medium MG. Then, the three-phase AC power generated in the expansion turbine generator 2 passes through the AC-DC converter 7 and the DC-AC converter 8 to become three-phase AC power that conforms to the specifications of commercial power (system power). It is converted and supplied to the outside.

Next, the cooling operation (auxiliary operation) of the waste heat recovery power generator will be described.
In the waste heat recovery power generation apparatus, a part of the liquid medium ML discharged from the pump 5 in the above-described working medium circulation process is supplied to the cooling jacket 2c of the expansion turbine generator 2 via the first and second branch pipes. And supplied to the respective coolers 7 b and 8 b of the AC-DC converter 7 and the DC-AC converter 8 and used for cooling the expansion turbine generator 2, the AC-DC converter 7 and the DC-AC converter 8. The

  In the cooling jacket 2c, the heat of the generator 2b is transferred to the liquid medium ML in a flow rate state in which the liquid medium ML maintains the liquid state, and as a result, the generator 2b is cooled. On the other hand, in the cooler 7b of the AC-DC converter 7, the heat of the AC-DC conversion circuit 7a is transferred to the liquid medium ML in a flow rate state in which the liquid medium ML maintains the liquid state, and as a result, the AC-DC conversion circuit. 7a is cooled. Further, in the cooler 8b of the DC-AC converter 8, the heat of the DC-AC conversion circuit 8a is transferred to the liquid medium ML in a flow rate state in which the liquid medium ML maintains a liquid state, and as a result, the DC-AC conversion circuit. 8a is cooled.

According to such an embodiment, the expansion turbine generator 2, the AC-DC converter 7, and the DC-AC converter 8 are cooled using the liquid medium ML at a flow rate setting that maintains the liquid state. Is supplied with only the liquid medium ML (liquid working medium). Therefore, the efficiency of heat recovery from the waste gas (heat source) can be improved in comparison with the prior art in which the working medium partially vaporized is supplied to the evaporator.
Further, according to the present embodiment, the liquid medium ML is used for cooling the expansion turbine generator 2, the AC-DC converter 7, and the DC-AC converter 8 without using an external power source such as system power. The energy efficiency of the device is good.

  Moreover, according to this embodiment, since the temperature sensor 2d and the control valve 6 are provided, it adjusts so that the internal temperature of the generator 2b which comprises the expansion turbine generator 2 (main machine) maintains target temperature. . That is, in the present embodiment, the flow rate of the liquid medium ML used for cooling the expansion turbine generator 2 (main machine) is more positive than the AC-DC converter 7 and the DC-AC converter 8 that are auxiliary machines. Control. According to this embodiment, it is possible to more reliably cool the expansion turbine generator 2 (main engine).

  Furthermore, according to the present embodiment, by using the second and third branch pipes, a part of the liquid medium ML supplied from the pump 5 to the evaporator 1 is transferred to the cooling jacket 2c of the expansion turbine generator 2 (main machine). Are supplied individually (in parallel) to each of the coolers 7b and 8b of the AC-DC converter 7 and the DC-AC converter 8 which are auxiliary machines, and in the cooling jacket 2c and each of the coolers 7b and 8b It is relatively easy to keep the body.

  That is, if the cooling jacket 2c and the coolers 7b and 8b are connected in series by piping, for example, the liquid medium ML discharged from the cooling jacket 2c is supplied to the cooler 7b and further discharged from the cooler 7b. When the liquid medium ML is supplied to the cooler 8b, the liquid medium ML gradually increases in the order of the cooling jacket 2c → the cooler 7b → the cooler 8b. It may be difficult to keep the liquid. Since the present embodiment is based on supplying the evaporator 1 while keeping the liquid state without vaporizing the liquid medium ML subjected to cooling, a part of the liquid medium ML is supplied to the cooling jacket 2c and each cooling medium. A configuration is adopted in which the units 7b and 8b are supplied individually (in parallel).

In addition, this invention is not limited to the said embodiment, For example, the following modifications can be considered.
(1) In the above embodiment, the AC-DC converter 7 and the DC-AC converter 8 that are auxiliary machines are also cooled by the liquid medium ML in addition to the expansion turbine generator 2 (main machine). However, the present invention is not limited to this. Only the main machine may be cooled by the liquid medium ML, and in some cases, only the auxiliary machine may be cooled by the liquid medium ML.

(2) In the above embodiment, the liquid medium ML is configured to be supplied individually (in parallel) to the cooling jacket 2c and the coolers 7b and 8b, but the present invention is not limited to this. For example, by increasing the flow rate of the liquid medium ML supplied to the cooling jacket 2c and each of the coolers 7b and 8b, the temperature increase width of the liquid medium ML due to cooling can be suppressed to be small, and therefore the cooling jacket 2c and each cooler 7b and 8b may be connected in series by piping.

(3) In the above embodiment, the temperature sensor 2d and the control valve 6 are provided only for the expansion turbine generator 2 (main engine), but the present invention is not limited to this. For example, the AC-DC converter 7 and the DC-AC converter 8 which are auxiliary machines may be provided with temperature sensors and control valves corresponding to the temperature sensor 2d and the control valve 6 to adjust the flow rate.

(4) In the above embodiment, the thermal energy of the waste gas is recovered as electric energy, but the present invention is not limited to this. For example, waste hot water at about 100 ° C. may be used as a heat source instead of waste gas. Further, the heat source is not limited to waste heat such as the waste gas and waste warm water.

(5) In the above embodiment, the fluorine-based medium is used as the working medium (liquid medium), but the present invention is not limited to this.

  DESCRIPTION OF SYMBOLS 1 ... Evaporator, 2 ... Expansion turbine generator, 2a ... Turbine, 2b ... Generator, 2c ... Cooling jacket, 2d ... Temperature sensor (thermometer), 3 ... Condenser, 4 ... Reservoir tank, 5 ... Pump, 6 ... Control valve, 7 ... AC-DC converter, 8 ... DC-AC converter, ML ... Liquid medium, MG ... Gas medium

Claims (4)

An evaporator that vaporizes a liquid working medium by heat exchange with a heat source;
An expansion turbine generator for generating electricity using a working medium vaporized state supplied from the evaporator,
A condenser for condensing the vaporized working medium discharged from the expansion turbine generator;
A pump for discharging the working medium in a liquid state from the condenser and supplying the working medium to the evaporator ;
A generator cooler for cooling the expansion turbine generator by using a liquid working medium;
The working medium in a liquid state is supplied to the generator cooler, the flow rate is adjusted by the minimum flow or more flow area not vaporized in the generator cooler, characterized in that it is supplied to the evaporator Heat recovery power generator. A power converter for converting the power output from the expansion turbine generator;
It said power converter further comprises a power transducer cooler for cooling using a working medium in the liquid state,
2. The heat recovery power generator according to claim 1, wherein the flow rate of the liquid working medium supplied to the power converter cooler is set to a flow rate that is not vaporized by the power converter cooler.   3. The heat recovery according to claim 2, wherein a part of the liquid working medium supplied from the pump to the evaporator is separately supplied to the generator cooler and the power converter cooler. Power generation device. A thermometer for measuring the temperature of the expansion turbine generator;
A control valve that adjusts the flow rate of the liquid working medium supplied to the generator cooler based on the measured value of the thermometer so that the temperature of the expansion turbine generator maintains a target temperature. The heat recovery power generator according to any one of claims 1 to 3.

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