JPS6358242B2 - - Google Patents

Description

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

Prior Art Screw-type fluid (gas) machines have been used as compressors for a long time, and many lubricating methods have been proposed for this, but there are few cases where they are used as expanders. The means of refueling at that time has not 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. Lubricating means injects a large amount of cooled lubricating oil to lubricate the rotors, directly cool the compressed gas, and seal each part, all of which are used to increase the efficiency of gas compression. This was not necessarily an appropriate refueling method for this purpose. 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.

Purpose Therefore, when using a screw-type fluid machine as an expander, the present invention aims to (a) supply high-pressure fluid to the suction side, so unless the end face of the suction side is securely sealed, the efficiency will be greatly affected; There is an impact.

(b) Since this is a prime mover that draws high-pressure gas fluid sucked in from the suction side into the working chamber (inside the cylinder) and expands it to obtain power, the machine must ensure a seal between the working chambers and the working chambers. Affects efficiency.

(c) If the liquid that lubricates and seals the sliding surfaces between the component parts is heated appropriately beforehand,
Lubricating and sealing each sliding surface that partitions the working chamber has the effect of adding energy to the gas in the polytropic process within the chamber, thereby improving mechanical efficiency.

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

Configuration The oil supply device of the present invention includes: (1) In an expander of a screw-type fluid machine, in order to seal the end face on the high-pressure gas fluid suction side, a seal is injected to the fluid side through a nozzle opened in the wall surface of the high-pressure gas fluid suction chamber.・The lubricating liquid is injected into the cylinder inside to seal and lubricate the sliding surfaces that partition the working chamber. ・The lubricating liquid has a temperature that is approximately the same as that of the high-pressure gas fluid at the injection position of the liquid. A refueling device for a screw expander, characterized in that the fuel is injected while maintaining a heated state or a higher temperature state than the temperature of the high-pressure gas fluid at each injection position.

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 gas is The refrigerant gas is separated from the lubricating oil, and the refrigerant gas passes through the condenser 8 installed in the heat exchanger _S2 , liquefies it, and is then sucked in from the suction side of the pump _P1 to become a pressurized fluid. ₁
is fed into the evaporator 2 of.

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 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. It 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 action chamber of the expander, and it is used to lubricate the low-pressure side bearing of the screw rotation shaft of the expander. It is fed into the end plate of the expander for use, and is press-fitted for the mechanical seal of the expander. The lubricating oil fed into those expanders is
As mentioned above, the lubricant moves inside the expander while being mixed with the refrigerant gas, and is discharged from the discharge port 6 and stored in the separation tank 7, where gas-liquid separation is performed. Oil is sucked from the bottom of the tank 7 by a pump P ₂ , pressurized and delivered to the lubricating oil heating pipe 3 of the heat exchanger S ₁ . The subsequent operation of the high temperature lubricating oil passed through the heating pipe 3 of the heat exchanger _S1 is as described above.

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

The screw expander of the present invention, particularly its oil supply device, is a technology related to the effect of the lubricating oil on the screw expander of the above system. Specifically, it constitutes a part of a lubricating oil circulation system including the above-mentioned five systems of lubrication means, and will be explained in detail below.

FIG. 2 shows a cross-sectional view of the screw expander of the present invention, and in the figure, 10 indicates a vertical cross-section (a cross-sectional view taken along a plane perpendicular to the screw rotor rotational axis shown) forming the outer wall of the working chamber. It is a spectacle-shaped or weight-shaped cylinder, and end plates 11 and 12 are screwed to both ends in the longitudinal direction of the cylinder to seal the end faces, and the rotating shafts of female and male screw rotors 13 and 14 rotate within the cylinder chamber, respectively. It holds bearings 17 and 18 that pivotally support the rotors 15 and 16, while making a contact seal with each end face of the rotor, and a high-pressure gas suction chamber 19 is provided in one of them, and a gas discharge chamber 20 is provided in the other. There is.

The seal 21 on the suction side end face (first system) is a high temperature seal provided on the high pressure side end plate 11.
A lubricating oil injection nozzle that opens toward the high-pressure gas suction chamber 19, is provided close to the gas suction port 5 of the working chamber, is pressurized by the pump _P2 , and is heated by the heat exchanger _S1 . The lubricating oil is injected into the high-temperature, high-pressure gas in the form of a mist, and the gas is sucked into the working chamber through the suction port 5 formed in the end plate 11.

Working chamber is female, male screw rotor 13,1
4 tooth engagement line, cylinder 10 inner wall and end plate 11
The working chamber is defined by a space defined by an end surface 22 of the rotor 13 and the end surface 22 of the rotor 13, and is provided so that its volume gradually expands as the rotors 13 and 14 rotate. 5, the volume is narrow, and as the communication is cut off, i.e., closed, and progresses toward the low-pressure side end plate 12, the volume expands, and eventually the discharge hole bored in the low-pressure side end plate 12 expands. It communicates with the outlet 6 and releases the high-temperature, high-pressure gas sucked into the working chamber through the discharge port 6 into the discharge chamber 20 on the low-pressure side.

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 turns into low-temperature, low-pressure gas, generating 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 gas flow, it cannot necessarily ride the flow of gas, and collides with and adheres to the inner wall surface of the cylinder that divides the working chamber, the high pressure side end surface 22, and the screw surfaces of the rotors 13 and 14, lubricating these surfaces, and It lubricates each other, the sliding surfaces of the high-pressure side end face of the screw rotor, and the screw engagement line, and penetrates into the gap created in the same area to perform an efficient sealing action.

In connection with the process of high-pressure refrigerant gas flowing into the suction chamber 19, when high-temperature lubricating oil heated in the heat exchanger _S1 is injected into the suction gas, the temperature of the lubricating oil is adjusted to that of the high-pressure gas. It is designed to raise the temperature of the gas to the same or higher temperature 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 described above, the working chamber is divided by the screw surfaces of the female and male rotors, the inner wall of the cylinder, and the end surface 22 of the high-pressure end plate 11.
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 lubricating oil mixed in the high-temperature gas seals the gap and prevents gas leakage. , to prevent the efficiency of the expander from decreasing. Particularly in the working chamber near the suction port 5, the gas pressure is high, so even a small amount of gas leakage has a large effect on efficiency, so the gap between the sliding surfaces must be reliably sealed. 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, and 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 bearing (second system) FIG. 3 shows a plan cross-sectional view of the screw expander of the present invention, in which 11 is the high-pressure side end plate,
Parallel ball bearings 17 _-1 , 17 _-1 , 1
7 _-2 and 17 _-2 , and the bearings pierce the high-pressure end plate from the inside and pivotally support the necks of the rotors 13 and 14, at which the rotating shafts 15 of the rotors 13 and 14 extend. 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 communicates with an oil supply passage 24 via an oil groove provided on the circumferential surface of the bushing to lubricate the bearing that supports the rotating shaft 15 of the rotor on the other side. It is connected to an oil groove cut into the circumferential surface of the structural bush. A cover plate 25 is screwed to the outer end surface of the high-pressure side end plate 11.
A high pressure side bearing chamber 26 is formed between the end plate 11 and serves as a lubricating oil storage chamber, and the bearings 17 _-1 and 17 _-2 are exposed within the same chamber. The bearing chamber 26 is an oil recovery hole 27
(See FIG. 2)
It communicates with a recovery hole A opened in the inner wall surface.

FIG. 4 is a developed view of the inner wall and working chamber of the cylinder 10, 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 and the discharge port 6 side. , the center line is the intersection line of the circular arcs of the cross section of the cylinder glasses, and the diagonal lines are the sliding contact lines between the screw tooth tip and the cylinder inner wall surface, and each section indicates the space of the working chamber. Further, the direction of the arrow indicates the advancing direction of the rotor, that is, the moving direction of the working chamber, and the dashed line diagonal line indicates the end position of the working space for expansion. A opens into the inner wall of the cylinder and is connected to the high pressure side bearing chamber 2.
6. A lubricating oil recovery hole that communicates with the working chamber through 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. The lubricating oil used on the one hand lubricates and seals the labyrinth structure 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. , overflows to the high-pressure side bearing side, forcibly lubricates each of the parallel ball bearings 17 _-1 and 17 _-2 , absorbs the heat generated by the rotation of the bearings, and then flows out and accumulates in the high-pressure side bearing chamber 26. do. As mentioned earlier, the lubricating oil accumulated in the high-pressure side belling chamber 26 is guided 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. Eventually, it is discharged to the outside of the expander through the discharge port 6 and the discharge chamber 20.

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 flows from the recovery hole A. When the oil is collected in the low-temperature, low-pressure working chamber, dissolved gas evaporates from the oil, exerting a gas expansion action within the working chamber, and plays 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 whose longitudinal section is a spectacle or weight shape, forming the outer wall of the action chamber, as described above. A plurality of lubricating oil injection holes 29 are drilled through the cylinder wall surface near the intersection line of the circular arcs, each 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 outside the cylinder 10, into which oil is heated through a heating pipe in the heat exchanger _S1 and pressurized by the pump _P2. The high-temperature lubricating oil is supplied through the oil supply hole 28, and the 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.
Provides lubrication and sealing effects on meshing and sliding surfaces.

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;
29 is a female rotor, 29 is a lubricating oil injection hole provided diagonally through the cylinder wall, 30 is a projection of the tip of the screw tooth of the female rotor, and the arrow indicates the direction of movement of the screw tooth as the rotor rotates. show. 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 downstream side, the lower the temperature and pressure.

As shown in the figure, the lubricating oil injected from the injection hole 29 is injected between the cylinder inner wall surface and the screw tooth tip surface from the rear side in the advancing direction of the protrusion 30 of the screw tooth to form a high-pressure working chamber and a low-pressure working chamber. It lubricates and seals the sliding surface of the protrusion 30 that separates the two from each other 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, resulting in an oil film on the high-pressure side. In order to avoid a tendency that the ridges cannot be maintained, the spray is made along the direction of movement of the protrusions.

In addition to the high-temperature lubricating oil injected into the working chamber, it also heats the gas medium, which has become low temperature and low pressure due to polytropic expansion, to prevent a drop in gas pressure and increase efficiency. After the lubricating oil performs the lubrication and sealing function in the expansion chamber,
It mixes with the gas medium and is discharged from the discharge port 6 together with the gas.

Low pressure side bearing lubrication (fourth system) Referring to Figures 2 and 3, 12
is the low pressure side end plate, and the roller bearing 1
8, 18, and the bearing passes through the low-pressure side end plate from the inside and pivotally supports the neck portion of the rotor 13, 14 from which the rotating shaft 16 extends. Low pressure side end plate 1
The structure of the second 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, the shaft and the cover plate 32 forming the low-pressure side bearing chamber 33 are connected to each other. There are some differences in that a mechanical seal 36 is provided between them, and that the low-pressure side end plate 12 has a discharge port 6 on its inner end surface that communicates with the discharge chamber 20.

The oil supply hole 31 is provided through the end plate 12 until it hits the bushing of the rotary shaft 16, and the high temperature and high pressure lubricating oil supplied from the hole 31 is applied to the bushing peripheral surface of each rotor rotating shaft and the end plate 12. While lubricating and sealing the sliding surface between the two, the lubricant 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 through an oil recovery hole 34, and the lubricating oil accumulated in the chamber 33 passes through the recovery hole 34 and B into the low-pressure side working chamber. The gas is injected, mixed with a 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. A sealing material 35 is packed in between, and a mechanical seal mounting plate 38 is further screwed to the outside to seal the space between the plate 38 and the shaft 16 with a mechanical seal 36. The mounting plate 38 has an oil supply hole 37.
A high-temperature, high-pressure lubricating oil is press-injected here from the heating pipe 3 of the heat exchanger S ₁ to lubricate the mechanical seal 36, and then it fills the mechanical seal chamber and permeates through the sealing material 35, and the low-pressure side It moves to the bearing chamber 33, accumulates there, and combines with the low-pressure side bearing lubricating oil.

The lubricating/sealing oil supply means in the screw expander has the configuration as described above, but the embodiment of the oil supply device of the present invention mainly includes the seal on the suction side end face, that is, the first system, and This is realized by a circulation system for lubricating oil for expansion chamber injection, that is, belonging to the third system.

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 bearings.

Further, the range of use of the screw expander of the present invention is not limited to the explanation of the above-mentioned embodiments, and in short, as long as a large amount of high-pressure gas fluid source can be constantly obtained, there is no particular problem. as long as
It can be carried out at any time and under any environment, and the oil supply device of the present invention has the effect of improving the efficiency of the screw expander and greatly extending its service life.

Effects 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
For the sealing of the sliding surface at the end face, at least the gas fluid is not cooled, but rather energy is injected into the gas to prevent the pressure drop of the same fluid in the suction chamber, while the lubricant is injected into the inside of the cylinder. Together with the sealing liquid, it ensures lubrication and sealing of the sliding surfaces that separate the working chambers, minimizes gas leakage between the working chambers, and also reduces mechanical rotational resistance of the screw rotor. In particular, by injecting preheated sealing and lubricating fluid directly into the high-pressure gas filling the suction chamber or the working chamber, it is possible to add energy to the polytropic process in the working chamber and reduce the gas pressure. By making effective use of energy in various ways, such as preventing the expansion of gas, we have realized a highly efficient screw expander, and we have also reduced the amount of wear on the sliding surfaces in the entire expander mechanism, allowing for continuous operation without opening. It is possible to provide a refueling device which results in an extension of operating time and service life.

[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 plan 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 female rotor of the expander. FIG. 3 is a partial cross-sectional view taken along a plane perpendicular to the screw teeth of the screw. 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 an expander of a screw-type fluid machine, in order to seal the end face on the high-pressure gas fluid suction side, a sealing/lubrication liquid or an action chamber is defined to be injected to the fluid side through a nozzle opened in the wall surface of the high-pressure gas fluid suction chamber. The sealing/lubrication liquid injected into the cylinder for sealing and lubrication of the sliding surfaces is heated to approximately the same temperature as the high-pressure gas fluid at the injection position of the liquid, or
A refueling device for a screw expander, characterized in that the oil is injected while maintaining a higher temperature state than the temperature of the high-pressure gas fluid at each injection position.