JPH0988502A - Screw turbine and binary generating device therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase output of a screw turbine by reducing suction loss of working medium. SOLUTION: A screw turbine consists of a casing 10 having a suction port 15 and a discharge port 16 and a pair of screw rotors 13, 14 which are stored in the casing 10 rotatably and engage each other. By prolonging L/D of the screw rotors 13, 14 and opening an inner end 15a of the suction port 15 toward an outer peripheral face in the vicinity of an end on the high pressure side of the screw rotor 13, working medium flows in a rotor engaging part directly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw turbine and a binary power generator using the same as an expansion engine for a working medium.

[0002]

2. Description of the Related Art A screw turbine is constructed such that a pair of screw rotors are rotatably accommodated in a casing while meshing with each other, and supplies a working medium to a tooth-shaped space (working chamber) formed between the screw rotors. Is a positive displacement expansion engine in which the rotor is rotated by the expansion work of the working medium to obtain power.

A binary power generator using a screw turbine as an expansion engine for a working medium is known (Japanese Patent Laid-Open Nos. 60-56104 and 60-14459).
No. 4, JP-A-2-252901, etc.).

In Japanese Patent Laid-Open No. 60-56104, FIG.
As shown in 0, a binary power generation system constructed by utilizing waste heat from a factory is shown, and a pipe (1) for passing a high temperature heat source fluid discharged from the factory is provided on one side of the heat exchanger (S1). An evaporator (2) is installed which heats and vaporizes the liquid working medium fed from the other side through the pump (P1) and converts it into a high temperature / high pressure gas. The heat exchanger (S1) is further provided with a pipe (3) for heating the lubricating oil fed via the pump (P2) to a high temperature.

The high temperature heat source fluid passing through the pipe (1) is
Vaporization and heating of the working medium by the heat exchanger (S1)
The heat energy is exhausted to raise the pressure and heat the lubricating oil, and the heat is discharged from the heat exchanger (S1).

The working medium gas vaporized in the heat exchanger (S1) to a high temperature and high pressure is guided to the suction port (15) side of the screw turbine (4), and is paired with a pair of screw rotors (13, 14) expands in the tooth space (action chamber) formed by 14), is discharged from the discharge port (16) side, and is sent into the separation tank (7) where the working medium gas and the lubricating oil are separated. The working medium gas is liquefied through the condenser (8) installed in the heat exchanger (S2), and then fed into the evaporator (2) of the heat exchanger (S1) by the pump (P1). .

A screw rotor (1) of a screw turbine (4) driven by a high temperature and high pressure working medium gas
3, 14) turn the generator (9) to generate electricity.

A low temperature heat source fluid is separately introduced into the heat exchanger (S2) to cool the condenser (8) through which the working medium gas passes and to condense and liquefy it.

On the other hand, the lubricating oil heated in the heat exchanger (S1) and heated to a high temperature in the lubricating oil heating pipe (3) is supplied into the screw turbine (17) to lubricate the sliding surface. Also used for sealing and the like.

The screw turbine (4) has a suction port (1
5) and a casing (10) having a discharge port (16), a pair of screw rotors (13,
14) is rotatably accommodated. The tooth space (working chamber) formed between the screw rotors (13, 14) and the casing (10) is sealed with lubricating oil.
The working medium vapor gives a rotational force to the screw rotor in the process of expansion in the working chamber.

That is, in the tooth-shaped space (working chamber) generated between the male screw rotor (13) and the female screw rotor (14) by meshing with each other and the casing inner wall (including the end plate), both screw rotors rotate. The tooth profile of both screw rotors (13, 14) is set so that the capacity increases as the meshing moves from the suction side to the discharge side. In addition, a suction port (15) provided on the high-pressure side end plate (11) attached to one end of the casing (10) and a discharge port (16) provided on the low-pressure side end plate (12) at the other end.
Is open to the end faces of the male screw rotor (13) and the female screw rotor (14), and
The outer circumferences of the male screw rotor (13) and the female screw rotor (14) are surrounded by the inner wall of the casing (10).

The inlet (1) of the screw turbine (4)
The working medium that has flowed into the 5) is the male screw rotor (1
3), the female screw rotor (14), and the casing inner wall (including the end plate), flow into a tooth-shaped space formed to act to expand the volume of the space, and thus the male screw rotor ( 13) and the female screw rotor (14) are rotated to expand in the tooth space and then discharged from the discharge port (16), during which power recovery is performed.

In the working chamber of the screw turbine (4),
Lubricating oil is supplied for lubrication of the screw turbine (4) and sealing of the working chamber. Therefore, the heat exchanger (S1) described above is provided at an arbitrary position of the suction port (15).
Oil jet nozzle (17) for jetting lubricating oil heated to the same extent as the working medium sent from the heater (2) of
Is provided. This lubricating oil lubricates the male / female screw rotors (13, 14) and the sliding surfaces between the casing inner wall and the end plate and seals each part, and at the same time,
The working medium is directly contacted with the working medium supplied from the suction port (15) to heat the working medium.

[0014]

Since the conventional screw turbine is generally a screw type compressor which is simply used as an expansion engine, it is not always appropriate from the viewpoint of the efficiency of the expansion engine. .

That is, the conventional screw turbine is
The working medium is expanded from the working medium suction port (15) corresponding to the injection port of the turbine into the working chamber for expanding the working medium. The injection port opens in the direction of the rotation axis toward the end surface of the screw rotor (13, 14), and its shape is determined by the internal volume ratio of the screw turbine (4). Therefore, the working medium passes through the injection port having a limited area and flows into the working chamber, and the loss of the working medium at that time increases, resulting in a decrease in expansion efficiency.

Therefore, an object of the present invention is to reduce the loss due to the suction of the working medium.

[0017]

A screw turbine according to the present invention comprises a casing having a fluid suction port and a fluid discharge port, and a screw-shaped male rotor and female rotor rotatably housed in the casing and meshed with each other. , Increasing the ratio of the effective length L of the screw to the outer diameter D of the male rotor and the female rotor, that is, L / D, and making the inner end of the suction port close to the high-pressure side end of the male rotor and the female rotor. It is characterized in that it is opened toward the outer peripheral surface of.

By opening the inner ends of the suction ports toward the outer peripheral surfaces near the high-pressure side ends of the male rotor and the female rotor, the working medium can directly flow into the rotor meshing portion. Therefore, the inflow loss of the working medium is smaller than that in the conventional case where the working medium flows into the working chamber through the injection port having a limited area. Then, by increasing the L / D of the screw rotor, the opening area of the suction port can be made wider, so that the loss due to the suction of the working medium is further reduced. In this case, the shape of the inner end opening of the suction port is preferably a substantially triangular shape including two sides extending at an angle substantially equal to the lead angles of the screws of the male rotor and the female rotor.

In the binary power generator according to the present invention, the screw turbine having the above structure, the evaporator for evaporating the working medium supplied to the screw turbine, and the heating for heating the lubricating oil supplied to the screw turbine are provided. And the air discharged from the screw turbine
The screw includes a means for separating the liquid mixed fluid, a condenser for condensing and liquefying the separated working medium, and two pumps for circulating the working medium and the lubricating oil, respectively. The generator is driven by a turbine.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. Note that for simplification of description, substantially the same elements are denoted by the same reference numerals throughout the drawings, including those showing conventional examples, in the accompanying drawings.

2 to 4 are cross-sectional views illustrating the construction of the screw turbine, and FIG. 5 is a partially cutaway perspective view. As shown, the screw turbine (4) includes a casing (10) having a suction port (15) and a discharge port (16), and a male screw rotor (13) and a female rotatably housed in the casing (10). And a screw rotor (14). In the illustrated screw turbine, the casing (10) is a cylinder (10) that houses the screw rotors (13, 14).
a), a high pressure side end plate (11) attached to one end of the cylinder (10a), and a low pressure side end plate (12) attached to the other end of the cylinder (10a).

The suction port (15) is provided in the high pressure side end plate (11) attached to one end of the cylinder (10a), and the inner end (15a) is near the high pressure side end of the screw rotor (13, 14). At the screw rotor (13,14)
Is open toward the outer peripheral surface. Therefore, the working medium supplied to the suction port (15) of the screw turbine (4) is discharged from the inner end (15a) of the suction port to the male screw rotor (13), the female screw rotor (14), the casing inner wall (end plate). (Including the)) directly flows into the tooth space formed between and, and acts to expand the volume of the space,
Therefore, the male screw rotor (13) and the female screw rotor (14) are rotated, and power is recovered during this period. The exhaust gas flowing out from the tooth space is stored in the casing (1
0) and is discharged to the discharge port (16) provided in (0).

The male screw rotor (13) and the female screw rotor (14) have their axes of rotation parallel to each other, and their tooth shapes mesh with each other to rotate. As shown in FIG. 1, which is a schematic view of a pair of screw rotors in a meshed state, the ratio of the effective length L of the screw of the screw rotor to the outer diameter D, that is, L / D, is calculated by the conventional screw rotor (FIG. 1B). Longer than (Fig. 1
(A)). The figure illustrates a case in which it is approximately twice as large as the conventional one.

The outer circumferences of the male screw rotor (13) and the female screw rotor (14) are surrounded by the inner wall of the cylinder (10a). As can be seen from the developed views of the inner wall surface of the cylinder shown in FIGS. 6 and 7, the suction port (15)
Of the inner end (15a) of the screw rotor extends at one side perpendicular to the rotation axis of the screw rotor and at the same angle as the lead angle (θ) of the screw of the screw rotor (13, 14).
It has a triangular shape consisting of sides. Screw rotor L
As / D becomes longer, the lead angle of the screw becomes smaller and the length of the two sides becomes longer, resulting in a larger opening area. By the way, the L / D is 1.2 to 1.6 in the screw turbine that uses the conventional screw compressor.
Is generally set, but this is made larger than 1.6.

FIG. 8A shows the relationship between the rotation angle of the male rotor and the volume of the tooth profile space (working chamber), and FIG. 8B shows the volume (V) on the horizontal axis and the pressure (P) on the vertical axis. The PV diagram which took is shown. Further, FIG. 9 illustrates the operating principle of the screw turbine in time series. The operation principle of the screw turbine will be described below with reference to these drawings. FIG. 9A shows the state at the start of the suction process, and the suction process is represented by the numeral 1 → 2 in FIGS. 8A and 8B. Expansion process (2 →
3) is entered (c), and when the expansion step is completed, the discharge step (3
→ 4) starts. In FIG. 8, the portion indicated by satin represents the working medium, and as shown in FIG. 8A, the inner end of the suction port opens toward the outer peripheral surface of the screw rotor and has a substantially triangular shape. Recognize.

At any position of the suction port (15),
A lubricating oil jet nozzle (17) for jetting heated lubricating oil is provided. This lubricating oil not only lubricates the male / female screw rotors (13, 14) but also the sliding surfaces between the casing inner wall and the end plate and seals each part, and at the same time, from the suction port (15) into the casing (10). The working medium is heated in direct contact with the supplied working medium.

The screw turbine having the above construction is shown in FIG.
It can be used as an expansion engine for a working medium in a binary power generator as already described with reference to (a).

In the figure, (2) is an evaporator provided in the heat exchanger (S1) for heating and evaporating the working medium by a heat source such as hot waste water, (3) is a screw turbine (4)
A heating device for heating the lubricating oil supplied to the lubricating oil is heated to the same extent as the working medium generated in the evaporator (2).

As the heat source of the heater (3), the same heat source as that supplied to the evaporator (2) may be used as shown, or
Other heat sources may be used. (4) is a screw turbine to which the working medium generated in the evaporator (2) and the lubricating oil heated to the same degree as the working medium in the heater (3) are supplied.

(9) is a generator connected to the output shaft of the screw turbine (4), and (7) separates the working medium and lubricating oil discharged from the discharge port (16) of the screw turbine (4). The separation tank (8) for operating the heat exchanger (S2) is a condenser provided in the heat exchanger (S2) for condensing the working medium vapor separated by the separation tank (7). Is supplied with cooling water such as seawater.

(P1) is an operation for circulating the working medium separated into gas and liquid in a closed circuit between the evaporator (2), the screw turbine (4), the separation tank (7) and the condenser (8). The medium pump (P2) is a lubricating oil pump for circulating the lubricating oil in a closed circuit between the heater (3), the screw turbine (4) and the separation tank (7).

In order to generate electricity, for example, hot waste water serving as a heat source is used as an evaporator (2) and a heater (3) of a heat exchanger (S1).
At the same time, the cooling water is supplied to the condenser (8) in the heat exchanger (S2). In this state, the working medium pump (P1) and the lubricating oil pump (P2) are driven to circulate the working medium and the lubricating oil.

Then, the liquid-phase working medium discharged from the working medium pump (P1) and sent to the evaporator (2) is heated by the hot waste water in the evaporator (2) and becomes vapor to become a screw turbine (4). ) Is sent to the suction port (15).

Further, the lubricating oil discharged from the lubricating oil pump (P2) and sent to the heater (3) is also heated in the heater (3) to a higher temperature than the above-mentioned working fluid vapor by hot drainage. , Is supplied to a nozzle (17) provided near the suction port (15) of the screw turbine, and is injected into the suction port (15) from the tip of the nozzle.

Therefore, the working medium supplied to the suction port (15) of the screw turbine (4) is in direct contact with the lubricating oil heated to a high temperature, and the male screw rotor (13) and the female screw rotor (13) of the screw turbine (4) are connected. Screw rotor (1
4) It flows into the tooth-shaped space (working chamber) formed between the two and the inner wall of the casing (including the end plate) by the engagement with the lubricating oil.

When the working medium expands in the tooth space, it acts so as to spread the tooth space. As a result, the male screw rotor (13) and the female screw rotor (14) are rotated, and then the operation is performed. The medium and the lubricating oil flow out from the discharge port (16) of the screw turbine (4) and into the separation tank (7).

When the male screw rotor (13) and the female screw rotor (14) of the screw turbine (4) rotate as described above, the generator (9) connected to the output shaft of the screw turbine (4). Also rotates, so electricity is generated.

Further, the working medium and the lubricating oil flowing into the separation tank (7) are separated in the tank (7). And
The working medium is sent to the condenser (8) of the heat exchanger (S2),
After being cooled by the cooling water in the condenser (8) and condensed to become a condensed liquid, it is sent to the evaporator (2) again through the working medium pump (P1). On the other hand, the lubricating oil separated from the steam in the separation tank (7) is discharged from the same tank, and is sent to the heater (3) again by the lubricating oil pump (P2) and heated.

By continuously repeating the above-mentioned operation, power is recovered from the heat source such as hot waste water.

[0040]

As described above, in the screw turbine of the present invention, the working medium is rotatably meshed with each other by opening the inner end of the suction port toward the outer peripheral surfaces near the high pressure side end portions of the male rotor and the female rotor. Since it can be directly flown into the tooth space (working chamber), it is a loss due to suction of the working medium compared to the case where it flows into the tooth space (working chamber) after passing through a nozzle with a limited area as in the past. Is considerably reduced, and the expansion efficiency is improved. L / of screw rotor
By increasing D, the opening area of the inner end of the suction port becomes wider, so that the loss due to the suction of the working medium is further reduced.

Further, by adopting the screw turbine having such a structure as the expansion engine for the working medium of the binary power generator, the expansion efficiency of the screw turbine is improved, so that the output of the binary power generator is increased.

[Brief description of drawings]

FIG. 1A is a schematic diagram of a pair of screw rotors in a screw turbine according to the present invention, and FIG. 1B is a schematic diagram of a pair of screw rotors in a conventional screw turbine.

FIG. 2 is a cross-sectional view of a screw turbine taken along a plane including a rotation axis of a male screw rotor.

FIG. 3 is a cross-sectional view of the screw turbine taken along a plane including the rotation axis of the male screw rotor and the rotation axis of the female screw rotor.

FIG. 4 is a sectional view of the screw turbine taken along a plane perpendicular to the rotation axis of the screw rotor.

FIG. 5 is a schematic perspective view of a partially cut screw turbine.

FIG. 6 is a development view of an inner wall surface of a cylinder that houses a male screw rotor.

FIG. 7 is a development view of an inner wall surface of a cylinder that houses a female screw rotor.

8A is a graph showing the relationship between the rotation angle and the volume of the working chamber, and FIG. 8B is a PV diagram.

FIG. 9 is a perspective view showing the operating principle of the screw turbine.

FIG. 10A is a system diagram of a binary power generator that uses a screw turbine as an expansion engine, and FIG. 10B is a cross-sectional view of a screw turbine showing a conventional example.

[Explanation of symbols]

 2 Evaporator 3 Heater 4 Screw turbine 7 Separation tank 8 Condenser 9 Generator 10 Casing 10a Cylinder 13 Male screw rotor 14 Female screw rotor 15 Suction port 15a Inner end 16 Discharge port 17 Lubricating oil injection nozzle

Claims (3)

[Claims] 1. A L / D of the male rotor and the female rotor, comprising a casing having a fluid suction port and a fluid discharge port, and a screw-shaped male rotor and female rotor rotatably accommodated in the casing and meshed with each other. Lengthen
The screw turbine is characterized in that an inner end of the suction port is opened toward outer peripheral surfaces near the high-pressure side end portions of the male rotor and the female rotor. 2. The shape of the inner end opening of the suction port is a substantially triangular shape including two sides extending at an angle substantially equal to the lead angles of the screws of the male rotor and the female rotor. The screw turbine according to claim 1. 3. The screw turbine according to claim 1, an evaporator for evaporating a working medium supplied to the screw turbine, a heater for heating lubricating oil supplied to the screw turbine, and a screw turbine. And a condenser for condensing and liquefying the separated working medium, and two pumps for circulating the working medium and the lubricating oil, respectively. A binary power generator is characterized in that the generator is driven by the screw turbine.