JPS6056105A - Oil supply device for screw expansion apparatus - Google Patents

Abstract

PURPOSE:To improve the mechanical efficiency by receiving in bearing chambers a lubricating oil which forcedly lubricates bearing parts, withdrawing the oil in a working space from positions prior to a part communicated with an outlet, and utilizing refrigerant gas contained in the lubricating oil as a part of the driving source. CONSTITUTION:In a screw expansion apparatus wherein male and female screw rotors 13 and 14 engaged with each other are housed in a cylinder chamber of a cylinder 10 and each of rotating shafts 15 and 16 of the rotors is supported by each of bearings 17 and 18, a bearing chamber 26 on the high-pressure side and a bearing chamber 33 on the low-pressure side are formed between both end plates 11 and 12 and cover plates 25 and 32, respectively, so that a lubricating oil can be received therein after lubrication of the bearings 17 and 18. Further, withdrawing holes A and B are opened at the inner wall face of the cylinder in positions prior to a part where a working chamber is communicated with an outlet 6 and are communicated with the bearing chambers 26 and 33 by means of oil-withdrawing holes 27 and 34, respectively. By utilizing evaporation of the refrigerant gas dissolved in the lubricating oil withdrawn in the working chamber, the motive power is generated.

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 technique 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 purpose, but when used as expanders... However, 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.
In this device, the lubricating means injects a large amount of cooled lubricating oil into the casing to lubricate the rotors, directly cool the compressed gas, and seal each part, all of which are designed to increase the efficiency of gas compression. However, it was not necessarily an appropriate method for refueling the expander sump. That is, even if we consider one direction of injection of the cooling lubricant oil injected into the casing, the compressor and the expander cannot be discussed in the same way.

Purpose Therefore, the present invention aims to solve the problem that when a screw type fluid machine is used as an expansion machine, in a screw expansion machine that uses refrigerant gas as the working fluid (high pressure fluid), a large amount of refrigerant gas is dissolved in the lubricating oil that lubricates the bearings. Therefore, if this refrigerant gas can be utilized within the working chamber, mechanical efficiency can be greatly improved. Taking this into consideration, the present invention aims to provide an optimal oil supply means for screw expanders.

Configuration The present invention provides the following features: (1) In an expander for a screw-type fluid machine, the rotor rotating shaft is sealed from the action chamber, and the lubricating oil that forcibly lubricates each of the bearings is stored in the bearing chamber and then applied to the inner wall of the cylinder. When the oil is collected into the gas fluid in the working chamber through the oil recovery hole opened in the cylinder, the contained gas is released into the working chamber, and then the gas and fluid are discharged to the outside of the machine, and the oil recovery hole moves inside the cylinder chamber. 1. An oil supply device characterized in that a working space opens in a cylinder wall before communicating with a discharge port.

One 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 the expander of a screw-type gas fluid machine equipped with the oil supply system of the present invention as the prime mover.
SL) is equipped with a pipe 1 on one side for passing high-temperature fluid discharged from the factory, and a liquid refrigerant (in this case, Freon gas R-114) is supplied from the other side via a pump (Pl).
) is installed in the evaporator 2, which heats and vaporizes the gas, converting it into high-temperature, high-pressure gas. The heat exchanger (S, ) further includes:
A pipe 3 is provided for heating the lubricating oil fed via the pump (P2) 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 (Sl) for vaporizing and heating the refrigerant, increasing the pressure, and heating the lubricating oil, and becomes a low-temperature fluid. more excreted.

The refrigerant gas that is vaporized in the heat exchanger (Sl) and becomes 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 and lubricating oil are separated, and the refrigerant gas is passed through a heat exchanger (
It is liquefied through the condenser 8 installed in the heat exchanger (S2), and then sucked in from the suction side of the pump (P,) to become a pressurized fluid and sent to the evaporator 2 of the heat exchanger (Sl). be done.

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 (S2) 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 (Sl) and is heated to a high temperature is divided into five systems and supplied to the expander to lubricate the sliding surfaces. It is also used for sealing functions, etc. In other words, (2) injects high-temperature, high-pressure refrigerant gas into the waste fluid in the suction chamber of the expander in order to seal the end face of the suction side of the screw expander 4, and (2) injects high-temperature, high-pressure refrigerant gas into the waste fluid in the suction chamber of the expander. Supplied into the end plate of the expander for side bearing lubrication;
The part (2) is fed into the expander end plate for lubricating the low-pressure side bearing of the screw rotating shaft of the expander, and the part (2) 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 while the gases are discharged from the discharge port 6 and stored in the separation tank 7. Gas-liquid separation is performed, and the lubricating oil separated here is sucked from the bottom of the tank 7 by a pump (P2), pressurized, and sent to the lubricating oil heating pipe 3 of the heat exchanger (Sl). Ru. The subsequent operation of the high temperature lubricating oil that has passed through the heating pipe 3 of the heat exchanger (Sl) is as described above.

Thus, the flow of refrigerant scum and lubricating oil is closed.
It makes up the 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 lubricating means, and will be explained in detail below in order.

FIG. 2 shows a cross-sectional view of the screw expander of the present invention,
In the figure, 10 is a cylinder that forms the outer wall of the working chamber and has an eyeglass-shaped or weight-shaped longitudinal section (a sectional view taken along a plane perpendicular to the rotational axis of the screw rotor shown in the figure), and has end surfaces at both ends in the longitudinal direction. Each end plate 1.11, 12 is screwed and carries a bearing 17.18 which pivots on the axis of rotation 15.16 of a female and male screw rotor 13.14 rotating in the cylinder chamber, respectively. , are in contact with each end face of the rotor, and one side is provided with a high pressure gas suction chamber 19 and the other side is provided with a waste discharge chamber side.

■ Seal on the suction side end face (first system) 2] 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.

A pump (P
2), the lubricating oil pressurized by the heat exchanger (Sl) and heated by the heat exchanger (Sl) is injected into the high-temperature, high-pressure gas in the form of a mist, and is injected together with the gas into the working chamber through the suction port 5 formed in the end plate 11. Inhaled.

The working chamber is a space defined by the meshing line of the teeth of the female and male screw rotors 13.14, the inner wall of the cylinder 10, and the end surface 22 of the end plate 11.As the rotors 13.14 rotate, The working chamber is provided so that its volume gradually expands, and when the working chamber communicates with the suction port 5 provided in the high-pressure side end plate 11, the volume is small, and when the communication is cut off, that is, it is closed, and the working chamber is closed to the low-pressure side. The volume expands as it advances toward the end plate 12, and eventually the discharge port 6 formed in the low pressure side end plate 12
The high-temperature, high-pressure gas sucked into the working chamber is released to the low-pressure side discharge chamber 2 through the discharge port 6.

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

Now, the high-temperature lubricating oil injected into the suction chamber 19 becomes a mist, mixes with the high-pressure gas, and flows into the action chamber from the suction port 5 along with the flow of dregs, but the specific gravity of the lubricating oil is Because it is larger than that of the gas flow, it cannot necessarily ride the flow of gas, and collides with and adheres to the cylinder inner wall surface that partitions the working chamber, the high pressure side end surface 22, and the screw surface of the rotor 13, 14, lubricating these surfaces. It provides lubrication between the surfaces of the screws, the sliding surfaces of the high-pressure side end faces of the screw and the rotor, and the screw engagement line, and penetrates into the gaps that occur in these areas to provide an efficient sealing effect.

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 (Sl) is injected into the suction gas, the temperature of the lubricating oil is lowered to that of the high-pressure gas. The plan is to set the temperature to a temperature equal to or higher than that, and increase the temperature of the gas by injecting lubricating oil, so that at least the pressure of the suction gas does not decrease as a result.

As mentioned above, the working chamber is divided into the screw surfaces of the female and male rotors, the inner wall of the cylinder, and the end surface n of the high-pressure end plate 11.The high-temperature and high-pressure gas filled in the same chamber moves the rotor to the low-pressure end plate. 12 side, which tends to create a gap between the high-pressure side end face 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 and 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, 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 bearings (second system) Figure 3 shows a cross-sectional plan view of the screw expander of the present invention.
1.17, 17-2.172, said bearings pierce the high-pressure end plate from the inside and support the neck of the rotor 13, 14, from which the axis of rotation 15 extends. 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 n for high-pressure side bearing lubrication is drilled through the end plate 11.The oil supply hole % is further connected to the rotation of the rotor on the other side through an oil groove provided on the circumferential surface of the bushing. In order to lubricate the bearing that supports the shaft 15, an oil supply passage U is provided.
It is connected to an oil groove cut into the circumferential surface of a bushing having a structure similar to that described above. A cover plate 5 is screwed to the outer end surface of the high-pressure side end plate 11, and a high-pressure side bearing chamber is formed between the end plate 11 and the lubricating oil storage chamber, and the bearing 17-, ．． 17-2 are exposed in the same room. The bearing chamber A 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, where the upper horizontal line is the high-pressure end face n and the suction port 5III, and the lower horizontal line is the low-pressure end face and the discharge port 6 side. C, the center line is the intersection line of the circular arc of the cross section of the cylinder glasses, and the diagonal line is
It is a sliding contact line between the screw tooth tip surface and the cylinder inner wall surface, and each section represents the space of the working chamber. 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 indicates the end position of the expansion working space. 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 Figure 3 again, in the figure, the high-pressure lubricating oil supplied to the oil supply hole Z3 passes through the oil supply hole, etc., and is guided to the oil groove provided in the bush of each rotor rotating shaft, from which it overflows. The lubricating oil lubricates and seals the labyrinth structure of the sliding surface between the peripheral surface of the bush and the shaft hole bored in the end plate 11 on the one hand to prevent leakage of high pressure gas from the working chamber, and on the other hand , each ball bearing 17 that overflows to the high pressure side bearing side and is arranged in parallel.
−、．． 17-2 is forcibly lubricated to absorb the heat generated by the rotation of the bearing, which then flows out and accumulates in the high-pressure side bearing chamber 26. As mentioned earlier, the lubricating oil accumulated in the cylinder pressure side bearing chamber 26 is guided through the oil recovery hole 27 to the recovery hole A opened in the inner wall of the cylinder 10, where it is mixed with the gas medium in the low pressure side working chamber. , and is eventually discharged from the discharge port 6 to the discharge chamber side and out of the expander.

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

In addition, 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 surface.

■ Expansion chamber injection (third system) Referring to Fig. 2, numeral 10 denotes 7, which forms the outer wall of the action chamber and has a spectacle-shaped or weight-shaped longitudinal section, as described above.
A plurality of lubricating oil injection holes 29 are formed by a ring that penetrates the cylinder wall surface near the intersection line of the circular arcs of the glasses-shaped cross section, 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. to be drilled. Oil injection hole 2
The outer end of 9 opens into a lubricating oil storage chamber provided outside the cylinder 10, which is heated through a heating pipe in a heat exchanger (Sl) and pressurized by a pump (P2). Lubricating oil is supplied through the oil supply hole array, and high-temperature lubricating oil is injected into the working chamber through the injection holes 29 in the direction in which the screw teeth advance as the rotor rotates. The injection hole 29 is
In addition, some of the lubricating oil injected into the working chamber opens on the cylinder wall near the engagement line of the rotor screw teeth.
It is also guided to the meshing line side and performs a lubricating and sealing action on the meshing 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, 14 is a female rotor, and 29 is a cylinder wall. The lubricating oil injection hole (9) is diagonally provided through the
The protrusions and arrows on the top surface of the screw teeth of the female rotor indicate the direction of movement of the screw teeth 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 space is filled with a gas medium. The lower the downstream side, the lower the temperature and pressure.

The lubricating oil injected from the injection hole row is injected between the cylinder inner wall surface and the screw tooth tip surface from the rear side of the protrusion (9) of the screw teeth in the direction of movement as shown in the figure, and is then injected into the high-pressure working chamber and the low-pressure working chamber. It lubricates and soles the sliding surface of the protrusion 30 that separates it from the working chamber 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 blades, resulting in an oil film on the high-pressure side. Inject along the direction of movement of the protrusions to avoid a tendency to fail.

In addition, the high-temperature lubricating oil injected into the working chamber also has the effect of heating the gas medium, which has become low temperature and low pressure due to polytropic expansion, preventing a drop in gas pressure and increasing efficiency.

After the lubricating oil performs the lubrication and sealing functions in the expansion chamber, it is mixed with the gas medium and discharged together with the gas from the discharge port 6 to the outside of the machine.

■ Lubricating the low pressure side bearing (fourth system) Referring to Figures 2 and 3, 12 is the low pressure side end plate,
It carries a roller bearing 18.18 which passes through the low-pressure end plate from the inside and pivots on the neck from which the axis of rotation 16 of the rotor 13.14 extends. The structure 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, a low-pressure side bearing chamber 33 is formed with the shaft. There are some differences in that a mechanical seal 36 is provided between the cover plate 32 and the low-pressure side end plate 12 has a discharge port 6 on its inner end surface, which is connected to the discharge chamber side. be.

The oil supply hole 31 is provided until it penetrates the end plate 12 and hits the bushing of the rotating shaft 16, and the high-temperature, high-pressure lubricating oil supplied from the recessed hole 31 reaches the peripheral surface of the bushing of each rotor rotating shaft and the end plate. While lubricating and sealing the sliding surface between the bearing 12 and the bearing 12 , the lubricant passes through the low-pressure side bearing 18 , forcibly lubricates it, and accumulates 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 accumulated in the chamber 33 passes through the recovery hole and B into the low-pressure side working chamber. The gas is injected, mixed with the gas medium, and discharged from the discharge port 6 to the discharge chamber side.

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

■ Mechanical seal lubrication (fifth system) Referring to FIG.
A sealing material 35 is filled between the through hole drilled in the cover plate and the rotating shaft, and the mechanical seal mounting plate is further screwed to the outside to seal the space between the plates. A mechanical seal 36 seals between the shaft 16 and the shaft 16. The mounting plate 38 is provided with an oil supply hole 37, into which high-temperature, high-pressure lubricating oil is pressurized from the heating pipe 3 of the heat exchanger (Sl) to lubricate the mechanical seal 36, and then fill the mechanical seal chamber. It permeates through the sealing material 35, moves to the low-pressure side bearing chamber 33, accumulates there, and combines with the low-pressure side bearing lubricating oil.

The means for supplying lubricating and sealing oil in the screw expander are as described above, but the embodiment of the oil supply device of the present invention mainly uses (1) lubrication of the high-pressure side bearing (second system) and (2) low-pressure side bearings. This is embodied by the lubricating oil circulation system that belongs to the side bearing lubrication (fourth system).

Although the above technology has been described with reference to a refueling system for a screw expander that uses refrigerant gas as the operating fluid and as the prime mover for a power generation device that utilizes factory waste heat, the scope of use of the screw expander does not necessarily extend beyond the scope of use described above. The present invention is not limited to the explanation of the technology used in the embodiment.

However, consideration must be given to the relationship between the working fluid and the lubricating oil, where high-pressure working gas dissolves into the lubricating oil.

Effects Since the oil supply device of the present invention has the configuration described above, the high-pressure lubricating oil that lubricates and seals the sliding surfaces that partition the working chambers is used to lubricate the screw/rotor rotating shaft. is sealed from the working chamber to prevent high-pressure gas from leaking from the working chamber, and each bearing is forcibly lubricated to minimize the mechanical rotational resistance of the rotor, and the bearings are cooled to extend their service life. Further, the used lubricating oil is stored in the bearing chamber and collected in the working space at the previous position communicating with the discharge port to perform lubrication and sealing, and at that time, the lubricating oil is absorbed. The refrigerant gas is released into the working chamber, used as part of the power source, and then discharged to the outside of the machine. Furthermore, the present invention provides an oil supply device that realizes a screw expander that can be operated continuously without opening and has a long service life.

[Brief explanation of drawings]

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 female 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 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...Suction port, 6...
Discharge port, 10... cylinder, 11... high pressure side end plate,
12...Low pressure side end plate, 13...Male rotor, 14...
・Female rotor, 15. 16...Rotating shaft, 17...High pressure side bearing, 18...Low pressure side bearing, 19...
- Suction chamber, gas discharge chamber, 21. Injection nozzle, 23.
28. 31 and 37...Oil supply hole, 26...High pressure side bearing chamber, 27.34, A and B...Oil collection hole, 29.Oil injection hole, Machining...Protrusion, 33...・Low pressure side bearing chamber, 35...Seal L36...Mechanical seal agent Patent attorney Eiji 1) Hiroshi -

Claims (1)

[Claims] (1) In an expander for a screw-type fluid machine, the rotor rotating shaft is sealed from the action chamber, and the lubricating oil that forcibly lubricates each of its bearings is stored in the bearing chamber and then collected through an opening on the inner wall of the cylinder. When the oil is collected into the gas fluid in the working chamber through the hole, the contained gas is released into the working chamber, and then the gas and fluid are discharged to the outside of the machine. An oil supply device characterized by having an opening in the cylinder wall before communicating with the cylinder.