JPH0329962B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a screw expander in a fluid machine, and particularly to a lubricating technology for a screw expander.

[Conventional technology]

Screw-type fluid (gas) machines have been used as compressors for a long time, and many lubricating methods have been proposed for this purpose, but there are only a few cases in which the above-mentioned machines have been used as expanders. However, the means of refueling at that time has not necessarily been disclosed.

According to the literature, a screw compressor can also be used as an expander, and for example, the specific structure of an injection oil-cooled screw compressor is explained. A lubrication means that injects a large amount of cooled lubricating oil to lubricate the casing and rotor, directly cools the compressed gas, and seals each part, all of which are intended to increase the efficiency of gas compression. This was not necessarily an appropriate method of refueling aircraft.

In other words, even when considering one direction of injection of cooling lubricant oil injected into the casing, a compressor and an expander cannot be considered the same.

[Problem to be solved by the invention]

Therefore, when using a screw-type fluid machine as an expander, the present invention provides the following advantages: (a) Since high-pressure fluid is supplied to the suction side, efficiency will be greatly affected unless the end face of the suction side is securely sealed. be.

(b) Since the high-pressure gas fluid sucked from the suction side is taken into the working chamber (inside the cylinder) and expanded to generate power, it is a prime mover, so mechanical efficiency must be ensured unless the working chambers are sealed securely between the working chambers. have a negative impact on

(c) When injecting liquid to lubricate and seal the sliding surfaces of mechanical parts, the lubrication area should be divided appropriately according to the configuration of the sliding surfaces to be lubricated in advance, and the sliding surfaces should be properly distributed in each section. Lubricating and sealing the surfaces has the effect of not wasting the energy of the gas in the polytropic process within the same chamber, resulting in improved mechanical efficiency.

Taking the above points into consideration, it is an object of the present invention to provide an optimal oil supply means for a screw expander.

[Means to solve the problem]

In order to achieve the above object, the present invention has the following constituent elements.

(1) In screw-type fluid machines, seal lubrication is injected into the inside of the cylinder through a nozzle to seal and lubricate the sliding surfaces of the members that define the working chamber that accepts the high-pressure gas fluid that is sucked in and changes its volume. The liquid supply system is divided and supplied into five systems: at least the end face of the high-pressure gas fluid suction chamber, the high-pressure side bearing that supports the screw rotor, the low-pressure side bearing, the action chamber, and the mechanical seal. Lubricating device for screw expander.

[Effect]

The screw expander of the present invention, particularly its oil supply device, is a technology related to the effect of lubricating oil on the screw expander of the above-mentioned system.

Specifically, it constitutes a lubricating oil circulation system including the following five systems of lubrication means, and the functions thereof will be explained in detail below.

FIG. 2 shows a cross-sectional view of the screw expander of the present invention. It is a cylinder in the form of a cylinder or a weight, and end plates 1 and 12 are screwed to both ends in the longitudinal direction to seal the end faces, and a female screw rotor 1 and a male screw rotor 1 rotate in the cylinder chamber, respectively.
The bearings 17 and 18 that support the rotating shafts 15 and 16 of the rotors 3 and 14 are held, and the bearings 17 and 18 are held in contact with each end face of the rotor, and a high-pressure gas suction chamber 19 is provided in one of them, and a high-pressure gas suction chamber 19 is provided in the other. Gas discharge chamber 20
has been established.

Seal 21 on the suction side end face is a lubricating oil injection nozzle that opens toward the high temperature/high pressure gas suction chamber 19 provided on the high pressure side end plate 11, and is located close to the gas suction port 5 of the action chamber. The lubricating oil pressurized by the pump P ₂ and heated by the heat exchanger S ₁ is injected into the high-temperature, high-pressure gas in the form of a mist, and is perforated in the end plate 11 together with the gas. The liquid is sucked into the action chamber through the suction port 5.

The working chamber consists of female and male screw rotors 13,1
It consists of a space defined by the engagement line of the teeth of No. 4, the inner wall of the cylinder 10, and the end surface 22 of the end plate 11,
The working chamber is provided so that its volume gradually expands as the rotors 13 and 14 rotate, and when the working chamber is in communication with the suction port 5 provided in the high-pressure side end plate 11, its volume is narrow; cut off, that is,
As it closes and advances toward the low-pressure side end plate 12, the volume expands, and eventually it communicates with the discharge port 6 formed in the low-pressure side end plate 12, and the high-temperature gas drawn into the working chamber.
The high pressure gas is passed through the discharge port 6 to the discharge chamber 20 on the low pressure side.
to be released.

During this time, the high-temperature, high-pressure gas sucked in from the suction port 5 continues polytropic expansion while rotating the rotors 13 and 14 in the working chamber, and changes into low-temperature, low-pressure gas to generate power.

The high-temperature lubricating oil injected into the suction chamber 19 now becomes a mist, mixes with the high-pressure gas, and flows into the action chamber from the suction port 5 along with the gas flow, but the specific gravity of the lubricating oil is that of the gas. Because it is larger than the above, it cannot necessarily ride the flow of gas, and the inner wall surface of the cylinder that partitions the working chamber, the high pressure side end surface 22, and the rotors 13, 14
It collides with and adheres to the screw surface to lubricate said surface, as well as lubricate each other, the sliding surface of the high pressure side end surface of the screw rotor, and the screw engagement line, and penetrate into the gaps created in the same area to improve efficiency. Works well as a seal.

In connection with the process of high-pressure refrigerant gas flowing into the suction chamber 19, if necessary, when high-temperature lubricating oil heated in the heat exchanger _S1 is injected into the suction gas, the temperature of the lubricating oil is increased to a high pressure. It is designed to have a high temperature equal to or higher than that of the gas, and to increase the temperature of the gas by injecting lubricating oil, so that at least no pressure drop in the suction gas occurs.

As mentioned above, the action chamber includes the screw surfaces of the female and male rotors, the inner wall of the cylinder, and the high-pressure end plate 111.
Since the rotor is divided by the end face 22 of the rotor, the high temperature and high pressure gas filled in the same chamber is
2 side, which tends to create a gap between the high-pressure side end plate 22 and the end face of the rotor, but the mist-like lubricant oil mixed in the high-temperature gas seals the gap and prevents gas leakage. , to prevent the efficiency of the expander from decreasing.

Since the gas pressure is high in the working chamber near the suction port 5, even a small amount of gas leakage has a large effect on efficiency, so it is necessary to reliably seal the gap between the sliding surfaces. This is also the reason why lubricating oil is sprayed into the high pressure gas in the suction chamber 19 prior to the suction process.

The first system of lubrication means is as described above,
The lubricating oil injected here will be involved in the lubrication of all sliding surfaces and sealing of gaps in subsequent steps.

Lubrication of High Pressure Side Bearings (Second System) Fig _. 3 shows a plan cross-sectional view of the screw expander of the present invention. _1,17-
2 , _17-2 , and the bearing passes through the high-pressure end plate from the inside and connects to the rotating shaft 1 of the rotor 13, 14.
5 extends, supporting its neck.

A bush is fitted on the rotating shaft between the high-pressure side end surface 22 of the rotor and the inner ring of the ball bearing, and a labyrinth is cut on the sliding surface between the outer periphery and the end plate shaft hole. An oil supply hole 23 for lubrication of the high-pressure side bearing is bored through the end plate 11. The oil supply hole 23 further lubricates the bearing that supports the rotating shaft 15 of the rotor on the other side via an oil groove provided on the circumferential surface of the bush.
It communicates with the oil supply passage 24 and is connected to an oil groove cut into the circumferential surface of a bushing having the same structure as described above.

A cover plate 25 is screwed to the outer end surface of the high-pressure side end plate 11, and a high-pressure side bearing chamber 26 is formed between the end plate ₁₁ and the lubricating oil storage chamber. , _17-2 are exposed in the same room. The bearing chamber 26 communicates with a recovery hole A opened in the inner wall surface of the cylinder 10, which will be described later, via an oil recovery hole 27 (see FIG. 2).

FIG. 4 is a developed view of the inner wall of the cylinder 10 and the working chamber, in which the upper horizontal line is the high pressure side end face 22 and the suction port 5 side, and the lower horizontal line is the low pressure side end face,
It is on the discharge port 6 side, the center line is the intersection line of the circular arc of the cylinder glasses cross section, the diagonal line is the sliding contact line between the screw tooth tip surface and the cylinder inner wall surface, and each section indicates the space of the working chamber. .

Further, the direction of the arrow indicates the moving direction of the rotor, that is, the moving direction of the working chamber, and the dashed line diagonal line indicates the completion position of the working space for expansion.

A is a lubricating oil recovery hole that opens in the inner wall of the cylinder and communicates with the working chamber through the high-pressure side bearing chamber 26 and the oil recovery hole 27, and is provided at a position before the working chamber communicates with the discharge port 6.

Similarly, B is a hole for collecting lubricating oil, etc. of the low pressure side bearing 18 accumulated in the low pressure side bearing chamber 33, which will be described later. do.

The plurality of oil injection holes 29 drilled on both sides of the central intersection line are lubricant injection holes for lubricating and sealing the sliding surface between the cylinder inner wall and the screw tooth tip. be.

Returning to FIG. 3 again, in the figure, the high-pressure lubricating oil supplied to the oil supply hole 23 is guided to the oil groove provided in the bush of each rotor rotating shaft through the oil supply hole 24, etc., and overflows from there. On the one hand, the lubricating oil lubricates and seals the labyrinth of the sliding surface between the bushing peripheral surface and the shaft hole bored in the end plate 11 to prevent leakage of high pressure gas from the working chamber, and on the other hand, Each ball bearing 17 overflows to the high pressure side bearing side and is arranged in parallel.
_-1 and _17-2 are forcibly lubricated to absorb the heat generated by the rotation of the bearings, and then flow out and stay in the high pressure side bearing chamber 26.

As mentioned earlier, the high pressure side bearing chamber 26
The lubricating oil accumulated in the tank is led through the oil recovery hole 27 to the recovery hole A that opens on the inner wall of the cylinder 10, where it mixes with the gas medium in the low-pressure side working chamber, and eventually flows through the discharge port 6 and the discharge chamber 20 to the expander. Expelled outside.

Since a large amount of high-pressure gas medium is dissolved in the lubricating oil accumulated in the high-pressure side bearing chamber 26 (when refrigerant gas is used as the working fluid), the lubricating oil accumulated in the same chamber is released from the recovery hole A at a low temperature. - When the oil is collected in the low-pressure working chamber, dissolved gas evaporates from the oil and causes gas expansion within the working chamber, playing a role in energy recovery.

Furthermore, since the lubricating oil is injected into the working chamber from the recovery hole A, a lubrication and sealing action is produced on the sliding surface between the cylinder inner wall and the screw tooth tip.

For expansion chamber injection (third system) Referring to Fig. 2, numeral 10 in the figure is a cylinder with a spectacle-shaped or weight-shaped longitudinal section that forms the outer wall of the action chamber as described above; A plurality of lubricating oil injection holes 29 are drilled through the wall surface near the intersection line of the circular arcs and are inclined in the direction of movement of the teeth of the screw provided on the rotor, preferably in the direction of movement of the tips of the screw teeth.

The outer end of the oil injection hole 29 opens into a lubricating oil storage chamber provided on the outside of the cylinder 10, which is heated if necessary through a heating pipe in the heat exchanger _S1 , and is heated by the pump _P2. Pressurized lubricating oil is supplied through the oil supply hole 28, and high-temperature lubricating oil is injected into the working chamber through the injection hole 29 in the direction in which the screw teeth advance as the rotor rotates. Injection hole 2
9 also opens on the cylinder wall near the meshing line of the screw teeth of the rotor, so a part of the lubricating oil injected into the working chamber is also guided to the meshing line side, providing lubrication and sealing effects on the meshing sliding surface. play.

Referring to FIG. 5, the drawing is a partial sectional view taken along a plane orthogonal to the screw teeth of the female rotor 14, in which 10 is a cylinder, 14 is a female rotor, and 29 is a cylinder. A lubricating oil injection hole 30 diagonally provided through the wall is a protruding line on the top surface of the screw tooth of the female rotor, and an arrow indicates the direction of movement of the screw tooth as the rotor rotates. The space defined by the groove between the teeth and the inner wall of the cylinder is the working chamber, and each is filled with a gas medium. The lower the temperature on the downstream side, the lower the temperature.
It's getting low pressure.

As shown in the figure, the lubricating oil injected from the injection hole 29 is injected from the rear side in the advancing direction of the protrusion 30 of the screw tooth between the cylinder inner wall surface and the screw tooth tip surface to partition it from the high pressure action chamber. The sliding surface of the protrusion 30 is lubricated and sealed to prevent leakage of high-temperature and high-pressure gas, and as the rotor rotates at high speed, the lubricating oil cannot follow the movement of the protrusion 30 and maintain an oil film on the high-pressure side. The injection is made along the direction of movement of the protrusions so as not to cause a tendency for the protrusions to move.

The high-temperature lubricating oil injected into the action chamber performs a lubricating and sealing action in the expansion chamber, then mixes with the gas medium and is discharged from the discharge port 6 to the outside of the machine together with the gas.

Lubrication of Low Pressure Side Bearing (Fourth System) Referring to FIGS. 2 and 3, 12 is a low pressure side end plate, and roller bearings 18, 1
8, and the bearing passes through the low-pressure side end plate from the inside and pivotally supports the neck portion of the rotor 1314 from which the rotating shaft 16 extends. The configuration of the low-pressure side end plate 12 side is almost the same as that of the high-pressure side end plate, but since the rotating shaft 16 of the male rotor 13 extends outside the machine, it forms a low-pressure side bearing chamber 33 with the shaft. cover plate 3
There are some differences in that a mechanical seal 36 is provided between the low-pressure end plate 12 and the low-pressure side end plate 12, and that the discharge port 6 is connected to the discharge port 6 on the inner end surface of the low-pressure end plate 12, and the discharge port 20 is connected to the discharge port 6.

The oil supply hole 31 is provided until it penetrates the end plate 12 and hits the bushing of the rotary shaft 16. Lubricates the sliding surfaces between
While sealing, the oil is forcibly lubricated through the low-pressure side bearing 18 and accumulated in the low-pressure side bearing chamber 33. The low-pressure side bearing chamber 33 is communicated with a recovery hole B opened in the inner wall of the cylinder 10 via an oil recovery hole 34, and the lubricating oil stagnant in the chamber 33 is transferred to the recovery hole 3.
4 and B into the low-pressure side working chamber, where it is mixed with the gas medium and discharged from the discharge port 6 into the discharge chamber 20.

Its action and effect are almost the same as in the case of high-pressure side bearing lubrication.

Mechanical seal lubrication (fifth system) With reference to FIG. Seal material 35 between
The mechanical seal mounting plate 38 is screwed to the outside, and the mechanical seal mounting plate 38 and the shaft 1 are
6 is sealed by a mechanical seal 36.

The mounting plate 38 is provided with an oil supply hole 37, into which high-temperature and high-pressure lubricating oil is pressurized if necessary from the heating pipe 3 of the heat exchanger _S1 , and after lubricating the mechanical seal 36, the mechanical seal chamber is filled. and permeates into the sealing material 35 and moves to the low pressure side bearing chamber 33.
It stays and combines with the low-pressure side bearing lubricating oil.

〔Example〕

An embodiment of the present invention will now be described with reference to the drawings.

FIG. 1 shows a schematic diagram of a power generation system configured using factory waste heat, with an expander of a screw-type gas fluid machine equipped with the oil supply device of the present invention as the _prime mover. A pipe 1 is installed on one side for passing high-temperature fluid discharged from the factory, and a liquid refrigerant (Freon gas, R-114 in this case), which is supplied from the other side via a pump P ₁ , is heated and vaporized to reach a high temperature.・An evaporator 2 is installed to convert into high-pressure gas. The heat exchanger S ₁ is further provided with a pipe 3 for heating the lubricating oil fed via the pump P ₂ to a high temperature.

Note that the thermal energy of the high-temperature fluid that has passed through the pipe 1 is used up by the heat exchanger S ₁ to vaporize, heat, and pressurize the refrigerant, and to heat the lubricating oil, and becomes a low-temperature fluid from the heat exchanger S ₁ . be discharged.

The refrigerant gas vaporized in the heat exchanger S ₁ to a high temperature and high pressure is guided to the suction port 5 side of the screw expander 4 . The high-temperature, high-pressure refrigerant gas that expands in the action chamber and rotates the screw rotor becomes low-temperature and low-pressure and is discharged from the discharge port 6 side of the expander and sent into the separation tank 7, where the refrigerant is The gas and lubricating oil are separated, and the refrigerant gas passes through the condenser 8 installed in the heat exchanger S ₂ and liquefies, and then is sucked in from the suction side of the pump P ₁ to become a pressurized fluid, and the refrigerant gas is liquefied through the condenser 8 installed in the heat exchanger S 2.
It is fed into the evaporator 2 of _S1 .

The screw rotor of the expander 4, which is driven by high-temperature, high-pressure refrigerant gas, turns the generator 9 and generates electricity.

A fluid using seawater or the like as a low-temperature heat source is separately introduced into the heat exchanger S ₂ to cool the condenser 8 through which the refrigerant gas passes, and condense and liquefy it.

On the other hand, the lubricating oil that flows through the lubricating oil heating pipe 3 installed in the heat exchanger _S1 and is heated to a high temperature is divided into five systems and supplied to the expander to lubricate the sliding surfaces and Used for sealing, etc.

That is, in order to seal the suction side end face of the screw expander 4 of high temperature and high pressure refrigerant gas, it is injected into the gas fluid in the suction chamber of the expander, and the high pressure side bearing of the screw rotation shaft of the expander is injected into the gas fluid in the suction chamber of the expander. is fed into the end plate of the expander for lubrication, and is injected into the same chamber to lubricate and seal the sliding surfaces in the working chamber of the expander, and is used to lubricate the low-pressure side bearing of the screw rotation shaft of the expander. It is fed into the expander end plate for use, and the V is press-fitted for the mechanical seal of the expander. The lubricating oil fed into the expanders moves inside the expanders while being mixed with the refrigerant gas as described above, and is discharged from the discharge port 6 and stored in the separation tank 7. Gas-liquid separation is performed, and the separated lubricating oil is sucked in from the bottom of the tank 7 by a pump _P2 and pressurized.
It is fed to the lubricating oil heating pipe 3 of the heat exchanger _S1 .

The subsequent operation of the hot lubricating oil passed through the pipe 3 of the heat exchanger S ₁ is as described above.

The flow of refrigerant gas and lubricating oil thus constitutes a closed cycle.

The means for supplying lubricating and sealing oil in the screw expander is constructed as described above.

The above technology has been explained using refrigerant gas as the working fluid and is based on an example of a refueling device for a screw expander used in a power generation device that utilizes factory waste heat. The source is not necessarily limited to refrigerant gas.

For example, when compressed air is used, "water" can be selected as the lubricating and sealing liquid supplied to the suction side end seal and the working chamber. However, in this case, it is necessary to use a separate system for lubricating the bearing rig.

Further, the range of use of the screw expander of the present invention is not limited to the explanation of the above embodiments, and in short, it is particularly important to use the screw expander under conditions where a large amount of high-pressure gas fluid source is constantly available. It can be carried out at any time and under any environment unless
Accordingly, the oil supply device of the present invention has the effect of improving the efficiency of the screw expander and significantly extending its service life.

〔Effect of the invention〕

Since the device of the present invention has the configuration as described above, it effectively prevents leakage of high-temperature, high-pressure gas fluid from the action chamber at the suction side end face, and also seals the sliding surface at the end face. This prevents unnecessary pressure drop of the same fluid in the suction chamber, and together with the lubricating and sealing liquid injected into the cylinder, it ensures the lubrication and sealing of the sliding surfaces that separate the working chambers. We aim to utilize energy effectively in various ways, such as minimizing gas leakage between each other, minimizing the mechanical rotational resistance of the screw rotor, and preventing gas pressure drops as much as possible. To provide a lubricating device which realizes a highly efficient screw expander and further reduces the amount of wear on sliding surfaces in the entire mechanism of the expander, thereby extending the continuous operation time without opening and the service life. Can be done.

In addition, if a heat exchanger is attached to this oil supply device and the preheated seal/lubrication oil liquid is injected directly into the suction chamber or the action chamber, energy will be added to the polytropic process of the high-pressure gas in the action chamber, and the gas will be It is also possible to prevent the pressure drop as much as possible and aim for effective use of energy.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of a power generation system using factory waste heat that uses an expander of a screw-type fluid machine equipped with the device of the present invention as a prime mover, and Fig. 2 shows the rotating shaft of the male rotor of the expander. 3 is a cross-sectional view of the expander, FIG. 4 is a developed view of the cylinder inner wall and working chamber of the expander, and FIG. 5 is a cross-sectional view of the female rotor of the expander. FIG. 3 is a partial cross-sectional view taken along a plane perpendicular to the screw teeth. 4...screw expander, 5...intake port, 6...
...Discharge port, 10...Cylinder, 11...High pressure side end plate, 12...Low pressure side end plate, 13...Male rotor, 1
4... Female rotor, 15, 16... Rotating shaft, 17...
...High pressure side bearing, 18...Low pressure side bearing, 19...Suction chamber, 20...Discharge chamber, 21...
Injection nozzle, 23, 28, 31 and 37... Oil supply hole, 26... High pressure side bearing chamber, 27, 3
4, A and B...Oil recovery hole, 29...Oil injection hole, 30...Protrusion, 33...Low pressure side bearing chamber, 35...Seal material, 36...Mechanical seal.

Claims (1)

[Claims] 1 In a screw-type fluid machine, a seal lubricating liquid that is injected into the inside of a cylinder through a nozzle to seal and lubricate the sliding surfaces of the members that define the working chamber that accepts the high-pressure gas fluid to be sucked in and changes its volume. A screw expansion system characterized by dividing and supplying the supply system into at least five systems: an end face of a suction chamber for high-pressure gas fluid, a high-pressure side bearing that supports the screw rotor, a low-pressure side bearing, an action chamber, and a mechanical seal. Aircraft refueling system.