JPWO2011118000A1 - Rankine cycle system - Google Patents

Abstract

The Rankine cycle system 100 includes a superheater 8 and an expander 10 that is driven by steam that is a vaporized refrigerant supplied from the superheater 8 to recover energy. The expander 10 includes a first discharge port 10a1 that discharges steam, and a second discharge port 10a2 that discharges liquefied refrigerant generated by condensation of the steam inside the expander 10. The Rankine cycle system 100 is connected to a first discharge port 10a1, and a first discharge passage 11 that discharges steam from the expander 10 and steam is introduced through the first discharge passage 11, and the introduced steam is condensed. Thus, a capacitor 12 is provided as a liquefied refrigerant. The liquefied refrigerant generated in the condenser 12 is stored in the condensed water tank 14. The second discharge port 10 a 2 and the condensed water tank 14 are connected by a second discharge passage 15.

Description

  The present invention relates to a Rankine cycle system.

  Conventionally, a Rankine cycle that recovers waste heat associated with the operation of an internal combustion engine is known. In such Rankine cycle, for example, boiling cooling is performed by using a water cooling cooling system of the engine as a closed structure, and an expander such as a steam turbine is driven by refrigerant evaporated by waste heat in the engine, that is, steam, There is one that recovers heat energy of the steam by converting it into electrical energy or the like. As an example of improving such a Rankine cycle system, there is Patent Document 1, for example.

JP 2009-103060 A

  However, in the proposal of Patent Document 1, for example, the following inconvenience may occur when the internal combustion engine is cold started. When the internal combustion engine is cold, the temperature of the expander is usually low. When steam is supplied to the expander in a low temperature state, the steam is condensed in the expander and returned to the liquefied refrigerant. The liquefied refrigerant generated in the expander is stored in the expander and becomes resistance for driving the expander, which may cause deterioration or breakage of the expander. When a Rankine cycle system is mounted on a vehicle, it frequently visits when the expander is in a cold state, so it is essential to solve the above-described problems of deterioration and breakage of the expander. In order to suppress such deterioration and breakage of the expander, it is conceivable to provide a control valve for suppressing the inflow of steam to the expander when the internal combustion engine is warmed up. However, in order to realize these controls, it is essential to construct an actuator that operates the control valve, a temperature sensor for setting the control timing, or a logic for estimating the temperature, which increases costs.

  Accordingly, an object of the Rankine cycle system disclosed in this specification is to suppress deterioration and breakage of an expander due to generation of a liquefied refrigerant in an expander such as a steam turbine.

  In order to solve such a problem, the Rankine cycle system disclosed in this specification is driven by a superheater and steam that is a vaporized refrigerant supplied from the superheater, performs energy recovery, and discharges the steam. An expander having a discharge port and a second discharge port for discharging the liquefied refrigerant generated by the condensation of the steam therein; and connected to the first discharge port, the steam from the expander A first discharge passage that discharges; a condenser in which the steam is introduced through the first discharge passage to condense the steam into a liquefied refrigerant; and a condensed water tank that stores the liquefied refrigerant generated in the condenser; And a second discharge passage for connecting the second discharge port and the condensed water tank and discharging the liquefied refrigerant from the expander.

  By providing the second discharge port, the expander can discharge the liquefied refrigerant generated by condensation inside the expander when the expander is in a cold state. If the liquefied refrigerant can be discharged from the inside of the expander, the driving load of the expander can be reduced. As a result, deterioration and breakage of the expander can be suppressed.

  The second discharge port is preferably provided at a lower portion of the expander. This is intended to efficiently discharge the liquefied refrigerant in consideration of the internal shape of the expander and the like. Usually, a liquefied refrigerant can be flowed out by providing a 2nd discharge port in the lower part of an expander.

  The liquid level in the condensed water tank has a difference between the liquid level and the lowest liquid level in the second discharge passage as Δh, and the vapor passes through the first discharge passage and the expander. It is desirable to satisfy the relationship of Δh> ΔPto / ρg, where ΔPto is the pressure loss when flowing into the condenser from ρ, ρ is the density of the liquefied refrigerant, and g is the acceleration of gravity.

  If the liquid level in the condensed water tank is maintained in a state satisfying such a relationship, it is possible to suppress the passage of steam through the second discharge port.

  In addition, the connection position of the second discharge passage to the condensed water tank can be higher than the lowest liquid level in the second discharge passage. For example, when the second discharge passage is formed by a U-shaped tube, the lowest liquid level of the second discharge passage becomes a U-shaped portion of the U-shaped tube, and Δh can be set large. If Δh can be set large, the passage of steam through the second outlet can be effectively suppressed.

  Further, the diameter of the second discharge port may be smaller than the diameter of the first discharge port. By setting the relationship between the diameter of the first outlet and the diameter of the second outlet in this way, the passage of steam through the second outlet can be effectively suppressed. Further, if the diameter of the first discharge port is increased, the pressure loss ΔPto can be reduced, which is effective in suppressing the passage of steam through the second discharge port.

  In addition, it is desirable that the flow passage area of the second discharge passage is smaller than the flow passage area of the first discharge passage. For example, the relationship represented by the above equation can be realized by setting the inner diameter of the pipe forming the second discharge passage to be smaller than the inner diameter of the pipe forming the first discharge passage. By setting the relationship between the flow passage area of the second discharge passage and the flow passage area of the first discharge passage in this manner, the passage of steam through the second discharge port can be effectively suppressed. Further, if the flow path area of the first discharge passage is increased, the pressure loss ΔPto can be reduced, which is effective in suppressing the passage of steam through the second discharge port.

  According to the Rankine cycle system disclosed in this specification, it is possible to suppress deterioration and breakage of the expander due to generation of the liquefied refrigerant in the expander.

FIG. 1 is a schematic configuration diagram of a Rankine cycle system according to an embodiment. FIG. 2 is an explanatory view showing an A portion in FIG. 1 in an enlarged manner. FIG. 3 is an explanatory view showing another shape of the second discharge passage.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

  A schematic configuration of the Rankine cycle system 100 will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic configuration diagram of a Rankine cycle system 100. FIG. 2 is an explanatory view showing an A portion in FIG. 1 in an enlarged manner. The Rankine cycle system 100 includes an engine 1 that is cooled by boiling a refrigerant therein. The engine 1 is an example of an internal combustion engine corresponding to a steam generator. The engine 1 includes a cylinder block 1a and a cylinder head 1b. A water jacket is formed in the cylinder block 1a and the cylinder head 1b, and the engine 1 is cooled by boiling the refrigerant in the water jacket. At this time, the engine 1 generates steam. The engine 1 further includes an exhaust pipe 2. One end of the steam passage 3 is connected to the cylinder head 1 b of the engine 1.

  A gas-liquid separator 4 is disposed in the steam passage 3. The refrigerant that has flowed into the gas-liquid separator 4 in the gas-liquid mixed state from the engine 1 side is separated into a gas phase (vapor) and a liquid phase (liquefied refrigerant) in the gas-liquid separator 4. One end of the refrigerant circulation path 5 is connected to the lower end of the gas-liquid separator 4. The other end of the refrigerant circulation path 5 is connected to the cylinder block 1a. A first water pump 6 that pumps the liquefied refrigerant into the engine 1 is disposed in the refrigerant circulation path 5. The first water pump 6 is a so-called mechanical type and uses a crankshaft provided in the engine 1 as a drive source. The first water pump 6 circulates the liquefied refrigerant between the engine 1 and the gas-liquid separator 4.

  A superheater 8 is provided in the steam passage 3. The superheater 8 includes an evaporation unit 8a on the lower side and a superheating unit 8b on the upper side. The exhaust pipe 2 is drawn into the superheater 8. Inside the exhaust pipe 2, exhaust gas generated by the engine 1 circulates. The exhaust pipe 2 penetrates the superheater 8 so that the exhaust gas passes through the superheater 8b and the evaporator 8a in this order. One end of the liquefied refrigerant passage 7 is connected to the evaporation unit 8a. The exhaust gas exchanges heat with the steam that has passed through the gas-liquid separator 4. The other end of the liquefied refrigerant passage 7 is connected to the lower end of the gas-liquid separator 4. The liquefied refrigerant passage 7 is provided with an on-off valve 7a. The supply state of the liquefied refrigerant from the gas-liquid separator 4 to the evaporation unit 8a is determined by the open / close state of the open / close valve 7a. The liquefied refrigerant supplied to the evaporation unit 8a can be vaporized by the heat of the exhaust gas after the vapor is superheated by the superheating unit 8b. Thereby, while generating amount of steam increases, the superheat degree of steam improves and waste heat recovery efficiency improves. A steam exhaust pipe 3a is provided at the upper end of the superheated part 8b. A nozzle 9 is provided at the tip of the steam discharge pipe 3a.

  An expander 10 is disposed on the downstream side of the superheater 8. The expander 10 is driven by vaporized refrigerant supplied from the superheater 8, that is, steam, and performs energy recovery. The expander 10 is a steam turbine including a case 10a and a turbine blade 10b provided in the case 10a. The nozzle 9 is attached to the case 10a so that the steam supplied through the steam passage 3 is injected toward the turbine blade 10b. Thereby, the turbine blade 10 b is rotationally driven by the steam supplied through the steam passage 3. The rotational force of the turbine blade 10b assists the rotation of the crankshaft provided in the engine 1 or drives the generator. Thereby, recovery of waste heat is performed.

  The case 10a of the expander 10 includes a first discharge port 10a1 that discharges steam and a second discharge port 10a2 that discharges liquefied refrigerant generated by condensation of the steam inside. Here, the 2nd discharge port 10a2 is provided in the lower part of case 10a of the expander 10 so that the liquefied refrigerant | coolant in case 10a of the expander 10 can be discharged | emitted. The diameter D2 of the second outlet 10a2 is smaller than the diameter D1 of the first outlet 10a1. That is, a relationship of D2 <D1 is established.

  One end of the first discharge passage 11 is connected to the first discharge port 10a1. The other end of the first discharge passage 11 is connected to the capacitor 12. The first discharge passage 11 discharges the steam from the expander 10 and introduces the discharged steam into the condenser 12. The condenser 12 is condensed by cooling the vapor to generate a liquefied refrigerant. The condenser 12 receives the air blown by the fan 13 and can efficiently cool and condense the steam. A condensed water tank 14 for storing the liquefied refrigerant generated in the capacitor 12 is installed below the capacitor 12.

  One end of the second discharge passage 15 is connected to the second discharge port 10a2. The other end of the second discharge passage 15 is connected to the condensed water tank 14. Such a second discharge passage 15 discharges the liquefied refrigerant from the expander 10 to the condensed water tank 14. In the condensed water tank 14, the liquefied refrigerant cooled by the condenser 12 is stored. The liquefied refrigerant condensed in the expander 10 is discharged into the condensed water tank 14 and mixed with the liquefied refrigerant cooled in the condenser 12 to lower the temperature. The flow passage area S2 of the second discharge passage 15 is smaller than the flow passage area S1 of the first discharge passage 11. That is, the relationship is S2 <S1.

  A refrigerant recovery path 16 is provided on the downstream side of the condensed water tank 14 for recirculating the liquefied refrigerant once stored in the condensed water tank 14 to the engine 1 side. The refrigerant recovery path 16 is connected to the upstream side of the first water pump 6 in the refrigerant circulation path 5. A second water pump 17 is disposed in the refrigerant recovery path 16. The second water pump 17 is an electric vane pump. When the second water pump 17 is activated, the liquefied refrigerant in the condensed water tank 14 is supplied to the refrigerant circulation path 5. In addition, a one-way valve 18 for avoiding the back flow of the refrigerant is disposed downstream of the second water pump 17. As described above, the Rankine cycle system 100 includes a path through which the refrigerant circulates.

  As described above, the diameter D1 of the first outlet 10a1 and the diameter D2 of the second outlet 10a2 included in the Rankine cycle system 100 have a relationship of D2 <D1. Further, the flow passage area S1 of the first discharge passage 11 and the flow passage area S2 of the second discharge passage 15 provided in the Rankine cycle system 100 have a relationship of S2 <S1 as described above. Maintaining these relationships is effective in suppressing the passage of steam through the second outlet 10a2. In the Rankine cycle system 100, it is desirable that the steam supplied into the expander 10 is discharged from the first discharge port 10a1 as much as possible. If the vapor, which is a vaporized refrigerant that has not been condensed, is discharged from the second discharge port 10a2, the vapor passes through the second discharge passage 15 and the condensed water tank 14 and flows into the condenser 12. That is, the steam flows from a direction different from the original inflow direction to the condenser 12. Thus, when steam flows into the condenser 12 from a direction different from the original direction, the function of the condenser 12 is impaired. That is, the condenser 12 cools and condenses the steam by heat exchange until the steam introduced from the upper side reaches the condensed water tank 14 to generate a liquefied refrigerant. When high-temperature steam flows from the condensed water tank 14 side, the function of the condenser 12 is impaired. Moreover, the temperature of the liquefied refrigerant in the condensed water tank 14 will also rise. The liquefied refrigerant in the condensed water tank 14 is supplied again to the engine 1 and used for cooling the engine 1. For this reason, there is also a demand for keeping the temperature of the liquefied refrigerant in the condensed water tank 14 as low as possible.

In order to avoid the steam being discharged from the second outlet 10a2, the Rankine cycle system 100 satisfies the relationship of the following expression (1).

Δh> ΔPto / ρg Formula (1)

Δh: difference between the liquid level in the condensed water tank 14 and the lowest liquid level in the second discharge passage 15 ΔPto: when steam flows from the expander 10 to the condenser 12 through the first discharge passage 11 Pressure loss ρ: Density of liquefied refrigerant g: Gravity acceleration

Here, Δh in this embodiment is Δh = Δh1, as shown in FIGS. Further, ΔPto in the present embodiment is a pressure loss in the range indicated by B in FIGS. 1 and 2.

  By satisfy | filling the relationship of such Formula (1), it can avoid that a vapor | steam is discharged | emitted from the 2nd discharge port 10a2. In order to satisfy the relationship of the expression (1), it is effective to set the value of Δh as large as possible and set the value of ΔPto as small as possible. The value of ΔPto can be reduced by setting the diameter D1 of the first discharge port 10a1 large or by setting the flow path area S1 of the first discharge passage 11 large.

  On the other hand, in order to set Δh large, the second discharge passage 15 can be replaced with a second discharge passage 151 as shown in FIG. As shown in FIG. 3, the connection position P <b> 1 of the second discharge passage 151 to the condensed water tank 14 is above the lowest liquid level 151 a in the second discharge passage 151. By making the shape of the second discharge passage 151 U-shaped, the lowest liquid level 151a is lowered. Thereby, Δh2 is secured. As is apparent from FIG. 3, Δh2 is larger than Δh1 when the second discharge passage 15 is used. As a result, Δh2 tends to satisfy the condition of Expression (1).

  As described above, according to the Rankine cycle system disclosed in this specification, the liquefied refrigerant generated in the expander 10 can be efficiently discharged. As a result, it is possible to suppress deterioration and breakage of the expander due to the generation of the liquefied refrigerant in the expander 10. At this time, a special control device for discharging the liquefied refrigerant from the expander 10 is unnecessary, which is advantageous in terms of cost.

  The above-described embodiments are merely examples for carrying out the present invention, and the present invention is not limited thereto. Various modifications of these embodiments are within the scope of the present invention. It is apparent from the above description that various other embodiments are possible within the scope.

DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Exhaust pipe 3 ... Steam passage 3a1 ... Steam discharge pipe 4 ... Gas-liquid separator 5 ... Refrigerant circuit 6 ... 1st water pump (W / P)
DESCRIPTION OF SYMBOLS 7 ... Liquefied refrigerant path 8 ... Superheater 8a ... Evaporating part 8b ... Superheating part 9 ... Nozzle 10 ... Expander 10a ... Turbine case 10b ... Turbine blade 11 ... First discharge passage 12 ... Condenser 13 ... Fan 14 ... Condensed water tank 15, 151 ... second discharge passage 16 ... refrigerant recovery passage 17 ... second water pump (W / P)
18 ... One-way valve 100 ... Rankine cycle system

[0002]
In order to realize this, it is essential to construct an actuator for operating the control valve, a temperature sensor for setting the control timing, or a logic for estimating the temperature.
[0005]
Accordingly, an object of the Rankine cycle system disclosed in this specification is to suppress deterioration and breakage of an expander due to generation of a liquefied refrigerant in an expander such as a steam turbine.
Means for Solving the Problems [0006]
In order to solve such a problem, the Rankine cycle system disclosed in this specification is driven by a superheater and steam that is a vaporized refrigerant supplied from the superheater, performs energy recovery, and discharges the steam. An expander having a discharge port and a second discharge port for discharging the liquefied refrigerant generated by the condensation of the steam therein; and connected to the first discharge port, the steam from the expander A first discharge passage that discharges; a condenser in which the steam is introduced through the first discharge passage to condense the steam into a liquefied refrigerant; and a condensed water tank that stores the liquefied refrigerant generated in the condenser; And a second discharge passage for connecting the second discharge port and the condensed water tank and discharging the liquefied refrigerant from the expander.
[0007]
By providing the second discharge port, the expander can discharge the liquefied refrigerant generated by condensation inside the expander when the expander is in a cold state. If the liquefied refrigerant can be discharged from the inside of the expander, the driving load of the expander can be reduced. As a result, deterioration and breakage of the expander can be suppressed.
[0008]
The second discharge port is preferably provided at a lower portion of the expander. This is intended to efficiently discharge the liquefied refrigerant in consideration of the internal shape of the expander and the like. Usually, a liquefied refrigerant can be flowed out by providing a 2nd discharge port in the lower part of an expander.
[0009]
The liquid level in the condensed water tank has a difference in height between the liquid level and the lowest liquid level in the second discharge passage as Δh, and the steam passes through the first discharge passage and is

Claims (6)

A superheater,
It is driven by steam, which is a vaporized refrigerant supplied from the superheater, recovers energy, and discharges the vapor, and a second outlet that discharges the liquefied refrigerant generated by condensation of the vapor inside. An inflator with a discharge outlet of
A first discharge passage connected to the first discharge port for discharging the steam from the expander;
A condenser in which the steam is introduced through the first discharge passage, and the steam is condensed into a liquefied refrigerant;
A condensed water tank for storing the liquefied refrigerant generated in the capacitor;
A second discharge passage connecting the second discharge port and the condensed water tank, and discharging the liquefied refrigerant from the expander;
A Rankine cycle system characterized by having   The Rankine cycle system according to claim 1, wherein the second discharge port is provided at a lower portion of the expander. The liquid level in the condensed water tank has a difference between the liquid level and the lowest liquid level in the second discharge passage as Δh, and the vapor passes through the first discharge passage and the expander. When the pressure loss when flowing into the capacitor from ΔPto, the density of the liquefied refrigerant is ρ, and the acceleration of gravity is g,
Δh> ΔPto / ρg
The Rankine cycle system according to claim 1, wherein the relationship is satisfied.   4. The connection position of the second discharge passage to the condensed water tank is above the lowest liquid level in the second discharge passage. 5. Rankine cycle system.   The Rankine cycle system according to any one of claims 1 to 4, wherein a diameter of the second discharge port is smaller than a diameter of the first discharge port.   The Rankine cycle system according to any one of claims 1 to 5, wherein a flow passage area of the second discharge passage is smaller than a flow passage area of the first discharge passage.

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