WO2017014027A1 - Rankine cycle system - Google Patents

Abstract

[Problem] To prevent contamination of gas into a liquid pump in order to improve the pump efficiency. [Solution] This Rankine cycle system is provided, in a circulation path 2 through which a working medium circulates, with: an evaporator which uses waste heat to vaporize the working medium; an expander which extracts energy from the working medium by allowing the evaporated working medium to expand; a condenser which cools and liquefies the working medium that has passed through the expander; a receiver tank 7 which subjects the working medium that has passed through the condenser to vapor-liquid separation and discharges the liquid working medium; and a pump 3 which feeds the working medium under pressure from the receiver tank 7 toward the evaporator. The pump 3 is disposed below the receiver tank 7, and a pipe 10, which is the part of the circulation path 2 between the receiver tank 7 and the pump 3, is horizontal or is inclined downward from the receiver tank 7 toward the pump 3, over the entire length of the pipe 10.

Description

Rankine cycle system

The present invention relates to the configuration of the Rankine cycle system.

Conventionally, Rankine cycle systems have been widely used as devices for recovering waste heat and using it for power generation and the like. For example, a waste heat power generation apparatus disclosed in Patent Document 1 includes a pump (liquid pump), an evaporator, a turbine generator (expander), a condenser, and a reservoir tank (receiver) in a circulation path of a working medium that is a fluid. It has a Rankine cycle system installed in order. In the Rankine cycle system in Patent Document 1, the working medium is pumped to the evaporator by a pump, and the working medium is evaporated by waste heat by the evaporator to form a gas. The working medium that has become gas is rotated in the turbine generator while rotating the turbine to generate power, and is cooled in the condenser to become liquid. The working medium cooled by the condenser is stored in a reservoir tank, and a liquid working medium is supplied to the pump.

JP 2013-7370 A

In the Rankine cycle system adopted in the above-mentioned Patent Document 1, even if the working medium is separated into liquid and gas in the reservoir tank, for example, the pressure drops in the circulation path between the receiver and the pump, or heat is generated in the pump. In some cases, a part of the working medium is vaporized and gas may be mixed into the pump chamber. And in such a state where gas is mixed in the pump chamber of the liquid pump, the operating efficiency of the pump is lowered.

The present invention has been made in view of such problems, and an object of the present invention is to provide a Rankine cycle system that suppresses gas mixing into a liquid pump and improves pump efficiency.

In order to achieve the above object, a Rankine cycle system of the present invention includes an evaporator that vaporizes a working medium by waste heat in a circulation path through which the working medium circulates, and an expansion that extracts energy by expanding the evaporated working medium. , A condenser that cools and liquefies the working medium that has passed through the expander, a receiver that gas-liquid separates the working medium that has passed through the condenser and discharges the liquid working medium, and the receiver A Rankine cycle system including a liquid pump that pumps the working medium from the receiver toward the evaporator, wherein the liquid pump is disposed below the receiver, and the circulation path includes the receiver, the liquid pump, and the like. In the section between, it is inclined horizontally or downward from the receiver toward the liquid pump.

Preferably, the ratio of the length of the horizontal portion in the circulation path in the section between the receiver and the liquid pump to the cross-sectional diameter of the circulation path is 10 or less.

Preferably, the introduction path of the liquid pump for introducing the working medium from the circulation path to the pump chamber of the liquid pump is inclined downward from the circulation path toward the pump chamber.

Preferably, the liquid pump includes a suction port portion connected to the circulation path via a connection joint, the main body portion of the liquid pump is disposed at an inclination, and the connection joint side of the suction port portion is It is good to incline upward from the horizontal.

Preferably, the liquid pump includes a suction port connected to the circulation path via a connection joint, and the suction port is above the horizontal on the connection joint side with respect to the main body of the liquid pump. It is good to be inclined to.

Further, preferably, a tapered portion that expands from the pump chamber side toward the receiver side is provided in a horizontal portion in the circulation path between the receiver and the pump chamber of the liquid pump.

According to the present invention, the liquid pump is disposed below the receiver, and the circulation path is inclined horizontally or downward from the receiver toward the liquid pump in the entire section between the receiver and the liquid pump. Even if a part of the working medium that is liquid is vaporized in the section between the pump or the pump and the receiver, the gas in the working medium returns to the receiver. Thereby, it can suppress operating a pump in the state in which gas is mixed in the pump chamber, it can improve the startability of a pump, and can improve pump efficiency.

It is a schematic structure figure of a Rankine cycle system concerning one embodiment of the present invention. It is a figure which shows the shape of piping between the receiver tank and pump in 1st Embodiment. It is a figure which shows the shape of piping between the receiver tank and pump in 2nd Embodiment. It is a graph which shows the operating range of the pump based on the ratio of the length and the internal diameter in a horizontal section, and a supercooling degree. It is explanatory drawing which shows the state which the bubble collected in the horizontal area. It is a figure which shows the shape of piping between the receiver tank and pump in 3rd Embodiment. It is a figure which shows the shape of piping between the receiver tank and pump in 4th Embodiment. It is a figure which shows the shape of piping between the receiver tank and pump in 5th Embodiment. It is a figure which shows the shape of piping between the receiver tank and pump in 6th Embodiment. It is a figure which shows the shape of piping between the receiver tank and pump in 7th Embodiment. It is an internal block diagram of the pump in 8th Embodiment. It is an internal block diagram of the pump in 9th Embodiment. It is an internal block diagram of the pump in 10th Embodiment. It is an internal block diagram of the pump in 11th Embodiment.

Hereinafter, a Rankine cycle system 1 according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a Rankine cycle system 1 according to an embodiment of the present invention.

Rankine cycle system 1 is used, for example, in an apparatus that recovers waste heat from a factory or the like. As shown in FIG. 1, the Rankine cycle system 1 includes a pump 3 (liquid pump), an evaporator 4, an expander 5, a condenser 6, and a receiver tank 7 in order in a circulation path 2 through which a refrigerant (working medium) circulates. (Receiver).

For example, HFC-R245fa is used as the refrigerant.
The pump 3 is a liquid pump such as a gear pump. The pump 3 may be a pump capable of pumping liquid, such as a vane pump, a diaphragm pump, or a piston pump, other than the gear pump.

The evaporator 4 is a heat exchanger that exchanges heat between waste heat such as exhaust heat and the refrigerant, and vaporizes the liquid refrigerant by the waste heat to be in a high-temperature and high-pressure superheated steam state.
The expander 5 expands the refrigerant in the superheated steam state generated by the evaporator, and converts the thermal energy of the refrigerant into torque (rotational force) and outputs it, for example, like a turbine. The torque output from the expander 5 is transmitted to the generator 8 to drive the generator 8 and generate electric power.

The condenser 6 is a heat exchanger that exchanges heat between cooling water if water-cooled and air and refrigerant if air-cooled, and cools and liquefies the refrigerant.
The receiver tank 7 is a tank that stores the refrigerant cooled by the condenser 6. The receiver tank 7 has a function of gas-liquid separation of a refrigerant in which gas and liquid are mixed and discharging only the liquid refrigerant to the pump 3.

In addition, the circulation path 2 is comprised by piping or a hose.
In the Rankine cycle system 1 of the present embodiment, the pump 3 is arranged at the lowermost part of the circulation path 2. Further, the circulation path 2 in the section between the receiver tank 7 and the pump 3 is constituted by a pipe 10.

FIG. 2 is a diagram illustrating the shape of the pipe 10 between the receiver tank 7 and the pump 3 in the first embodiment.
As shown in FIG. 2, in the first embodiment, the pipe 10 is inclined downward from the horizontal toward the pump 3 from the receiver tank 7 in the entire section between the receiver tank 7 and the pump 3. .

As described above, the pump 3 is arranged at the lowermost part of the circulation path 2, and the pipe 10 between the receiver tank 7 and the pump 3 is inclined downward from the horizontal in the entire section from the receiver tank 7 toward the pump 3. Thus, even if bubbles are included in the liquid refrigerant in the pipe 10, the bubbles move upward and return to the receiver tank 7 without remaining in the pipe 10.

Therefore, even if bubbles are generated from the liquid refrigerant due to generation of frictional heat in the sliding portion inside the pump 3 or pressure drop due to pressure loss in the pipe 10 from the receiver tank 7 to the pump 3, this bubble, that is, gas The shaped refrigerant moves upward in the pipe 10 and returns to the receiver tank 7, where it is separated again in the receiver tank 7.
Thereby, mixing of gas into the pump 3 can be prevented, and even if gas is generated in the pump 3, the gas can be discharged from the pump 3. Therefore, while suppressing the startability fall of the pump 3, it can improve efficiency, the discharge amount from the pump 3 can be improved, and the performance of the apparatus which employ | adopted Rankine cycle system 1 can be improved.

FIG. 3 is a diagram illustrating the shape of the pipe 10 between the receiver tank 7 and the pump 3 in the second embodiment.
As shown in FIG. 3, in the second embodiment, the pipe 10 between the receiver tank 7 and the pump 3 has a horizontal section 11 (horizontal portion) that extends horizontally at the connection portion with the pump 3. . Note that the piping 10 between the receiver tank and the pump is inclined downward from the horizontal toward the pump 3 from the receiver tank 7 side, as in the first embodiment, except for the horizontal section 11.
Further, the ratio L / D between the length L and the inner diameter D (cross-sectional diameter) in the horizontal section 11 is set to a predetermined ratio a or less. The predetermined ratio a may be set to 10 or less.

FIG. 4 is a graph showing the operating range of the pump 3 based on the ratio L / D between the length L and the inner diameter D and the degree of supercooling S in the horizontal section 11. The degree of supercooling S is the amount of temperature decrease from the saturation temperature of the refrigerant temperature at the inlet of the pump 3. The region where the degree of supercooling is larger than the line b shown in FIG. 4 is the normal operating region of the pump 3, and the region where the degree of supercooling is smaller than the line b is the malfunctioning region of the pump 3.
Moreover, FIG. 5 is explanatory drawing which shows the state which the bubble collected in the horizontal area 11 in this embodiment. In addition, the oblique line in FIG. 5 shows a liquid refrigerant.

As shown in FIG. 4, when the ratio L / D between the length L and the inner diameter D in the horizontal section 11 is equal to or greater than a predetermined ratio a, the pump is used even if the degree of supercooling S increases as the ratio L / D increases. It becomes easy to generate a malfunction. If the ratio L / D is equal to or less than the predetermined ratio a, the pump operates normally even if the degree of supercooling is 0 degree, that is, the refrigerant temperature at the inlet of the pump 3 is the same as the vaporization temperature of the refrigerant. The predetermined ratio a is confirmed to be about 10 by the applicant's experiment.

As shown in FIG. 5, if the ratio L / D between the length L and the inner diameter D in the horizontal section 11 is suppressed to 10 or less, only a small amount of bubbles are accumulated in the horizontal section 11, for example, the horizontal section Even if the number of bubbles increases at 11, the bubbles overflow from the horizontal section 11 and return to the receiver tank 7 side in the pipe 10. Even if the pump 3 is started in a state where air bubbles are accumulated in the horizontal section 11, the thickness of the air bubble portion is smaller than the inner diameter D in the horizontal section 11 of the pipe 10. The amount of gas inflow relative to the amount of inflow of liquid refrigerant is suppressed, and malfunction of the pump 3 can be prevented.

6 is the third embodiment, FIG. 7 is the fourth embodiment, FIG. 8 is the fifth embodiment, and FIG. 9 is the shape of the pipe 10 between the receiver tank 7 and the pump 3 in the sixth embodiment. FIG. In all of the third to sixth embodiments shown in FIGS. 6 to 9, the pipe 10 is connected to the pump 3 via a connecting joint 12 for piping.
The third embodiment shown in FIG. 6 differs from the second embodiment shown in FIG. 3 in that a connection joint 12 is provided in the horizontal section 11.

In the fourth embodiment shown in FIG. 7, the mounting angle of the pump 3 is inclined, and the pipe 13 which is the suction port portion of the pump 3 is horizontally oriented from the main body portion 14 side of the pump 3 toward the connection joint 12 side. Also extends upwardly. The pipe 13 and the straight connection joint 12 are connected to the pipe 10 that extends downwardly from the receiver tank 7.

In the fifth embodiment shown in FIG. 8, the mounting angle of the pump 3 is not inclined, but the pipe 13 at the suction port of the pump 3 is inclined with respect to the main body 14 of the pump 3. The main body 14 extends from the main body 14 toward the connection joint 12 while inclining upward from the horizontal. The pipe 13 is connected to the pipe 10 extending obliquely downward from the receiver tank 7 through a straight connection joint 12.

In the sixth embodiment shown in FIG. 9, the mounting angle of the pump 3 is not inclined, the pipe 13 extends horizontally from the pump 3, and the pipe 10 extends obliquely downward from the tip and the receiver tank 7. The connection joint 12 that connects the two uses a bent elbow joint.

With the configuration as described above, in the fourth and fifth embodiments, the pipe 10 between the receiver tank 7 and the pump 3 is connected from the receiver tank 7 to the pump 3 as in the first embodiment. Since all the sections are inclined downward from the horizontal in all sections, it is possible to prevent bubbles from staying in the pipe 10 and to prevent the bubbles from being mixed into the pump 3, thereby improving the efficiency of the pump 3. Can be made.
In the third embodiment and the sixth embodiment, the ratio L / D between the length L and the inner diameter D of the horizontal section 11 including the connection joint 12 may be set to 10 or less. Thereby, the efficiency of the pump 3 can be improved similarly to 2nd Embodiment.

FIG. 10 is a diagram illustrating the shape of the pipe 10 between the receiver tank 7 and the pump 3 in the seventh embodiment.
In the seventh embodiment, as compared with the third embodiment, in the horizontal section 11 of the pipe 10, the inner diameter of the pipe 10 increases in a tapered shape from the tip connected to the connection joint 12 toward the receiver tank 7 side. The taper portion 15 is different.

In the seventh embodiment, by providing the tapered portion 15 in this manner, the upper portion of the inner wall surface of the pipe 10 in the horizontal section 11 is inclined upward from the connection joint 12 toward the receiver tank 7 side. become.
Therefore, also in the seventh embodiment, bubbles are less likely to accumulate in the horizontal section 11, and the efficiency of the pump 3 can be improved.

FIG. 11 is an eighth embodiment, FIG. 12 is a ninth embodiment, FIG. 13 is a tenth embodiment, and FIG. 14 is an internal configuration diagram of the pump 3 in the eleventh embodiment.
The eighth to eleventh embodiments are characterized by the shape of the suction port side in the pump 3.
In the pump 3 of the eighth embodiment shown in FIG. 11, the introduction path 22 for introducing the refrigerant into the pump chamber 21 in which the pair of rotating gears 20 is housed is upward from the pump chamber 21 toward the suction port 23 side. It is inclined to.
In the pump 3 of the ninth embodiment shown in FIG. 12, the suction port portion 24 connected to the pipe 10 is inclined upward.

Therefore, in the eighth embodiment and the ninth embodiment, the air is inclined downward in the pump 3 from the suction port 23 side, that is, the receiver tank 7 side toward the pump chamber 21. Is less likely to accumulate, and bubbles can be discharged to the receiver tank 7 side. Therefore, by adopting the eighth embodiment and the ninth embodiment as the configuration of the pump 3, it is difficult for bubbles to accumulate in the pump 3, and the efficiency of the pump 3 can be improved.

In the pump 3 of the tenth embodiment shown in FIG. 13, a tapered portion 25 is formed in which the inner diameter of the introduction path 22 is increased from the pump chamber 21 toward the suction port 23 side.
In the pump 3 of the eleventh embodiment shown in FIG. 14, a tapered portion 25 is formed in which the inner diameter of the suction port portion 24 increases from the pump chamber 21 toward the suction port 23 side.
Therefore, in the tenth embodiment and the eleventh embodiment, the upper portion of the inner wall surface of the tapered portion 25 extends from the pump chamber 21 to the suction port 23 in the pump 3 from the pump chamber 21 toward the suction port 23 side. It will incline upward between.
As a result, even if the tenth embodiment and the eleventh embodiment are employed in the configuration of the pump 3, bubbles are less likely to accumulate in the pump 3, and the efficiency of the pump 3 can be improved.

Furthermore, it is preferable to apply a coating process or the like for reducing the frictional force to the introduction wall 22, the suction port 24, the pipe 10, and the inner wall surface of the connection joint 12 of the pump 3. As a result, bubbles are less likely to accumulate between the receiver tank 7 and the pump chamber 21 of the pump 3 and can be easily returned to the receiver tank 7.

Although the description of the embodiment of the present invention has been completed above, the present invention is not limited to this form, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above-described embodiment, the receiver tank 7 and the pump 3 are connected by the pipe 10. However, other pipes that can form a fluid flow path such as a hose may be used.
Further, a plurality of the above embodiments 1 to 11 may be combined.
The Rankine cycle system 1 of the present embodiment is not limited to factory waste heat, and can be widely applied to Rankine cycles of various heat utilization devices.

1 Rankine cycle system 2 Circulation path 3 Pump (liquid pump)
4 Evaporator 5 Expander 6 Condenser 7 Receiver tank (receiver)
10 Piping 11 Horizontal section (horizontal part)
12 Connection joint 13 Piping (suction port)
15 and 25 Taper portion 21 Pump chamber 22 Introduction path 24 Suction port portion

Claims (6)

An evaporator that vaporizes the working medium by waste heat, an expander that expands the vaporized working medium to extract energy, and the working medium that has passed through the expander are cooled in a circulation path through which the working medium circulates. A condenser for liquefying, a receiver for gas-liquid separation of the working medium that has passed through the condenser and discharging the working medium in liquid, and a liquid pump for pumping the working medium from the receiver toward the evaporator A Rankine cycle system with
The liquid pump is disposed below the receiver;
The Rankine cycle system, wherein the circulation path is inclined horizontally or downward from the receiver toward the liquid pump in a section between the receiver and the liquid pump. The Rankine cycle system according to claim 1, wherein a ratio of a length of a horizontal portion in the circulation path between the receiver and the liquid pump to a cross-sectional diameter of the circulation path is 10 or less. The introduction path of the liquid pump for introducing the working medium from the circulation path to the pump chamber of the liquid pump is inclined downward from the circulation path toward the pump chamber. The described Rankine cycle system. The liquid pump includes an inlet port connected to the circulation path via a connection joint,
The Rankine cycle system according to any one of claims 1 to 3, wherein a main body portion of the liquid pump is inclined and the connection joint side of the suction port portion is inclined upward from the horizontal. . The liquid pump includes an inlet port connected to the circulation path via a connection joint,
The Rankine cycle according to any one of claims 1 to 3, wherein the suction port portion is provided so that the connection joint side is inclined upward from the horizontal with respect to the main body portion of the liquid pump. system. The taper part which expands from the said pump chamber side toward the said receiver side was provided in the horizontal part in the said circulation path between the said receiver and the pump chamber of the said liquid pump. The Rankine cycle system according to any one of the above.

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