JP5054597B2 - Steam expander driven air compressor - Google Patents

Description

  The present invention relates to a steam expander driven air compressor.

  In a plant that uses steam generated in a boiler, high pressure (for example, 1.2 to 1.6 MPa) steam generated by the boiler is reduced by a pressure reducing valve, and low pressure (for example, 0.8 to 0.9 MPa) steam is demanded. It is common to supply equipment. When the pressure of the steam is reduced by the pressure reducing valve, the pressure difference energy of the steam is discarded, and it is desired to recover this energy.

  Patent Document 1 describes a device that compresses air by driving a screw air compressor with a screw steam expander. Although not described in the cited document 1, the screw steam expander requires additional equipment such as an oil pump and an oil cooler in order to lubricate and cool the bearing. Further, in the air compressor, an oil-cooled type in which lubricating oil is sucked together with the intake air or the lubricating oil is supplied to the low pressure portion of the rotor chamber is used, but in the oil-cooled air compressor, An oil separator or the like for separating the lubricating oil from the discharged compressed air is necessary.

  Since the lubricating oil separated by the oil separator of the oil-cooled air compressor is sent out with the pressure of the compressed air discharged from the oil-cooled air compressor, an oil pump is unnecessary. Therefore, it seems to be sufficient to lubricate the steam expander with the lubricating oil of the oil-cooled air compressor, but the pressure of the lubricating oil of the oil-cooled air compressor is higher than the service pressure of the seal of the steam expander. Risk of damaging the seal.

For this reason, in a steam expander-driven air compressor that drives an oil-cooled air compressor with a steam expander, there is incidental equipment for circulating the lubricant for the steam expander, and the lubricant is discharged from the discharge of the air compressor. Two types of lubrication systems, which are ancillary equipment that is separated and circulated to the air compressor, are necessary, and the apparatus is disadvantageous.
Japanese Patent Laid-Open No. 1-285692

  In view of the above-described problems, an object of the present invention is to provide a steam expander-driven air compressor having a simple lubricating system configuration.

  In order to solve the above problems, a steam expander-driven air compressor according to the present invention includes a steam expander, an oil-cooled air compressor driven by the steam expander, and the oil-cooled air compressor discharging An oil separator that separates lubricating oil from the compressed air, and the oil-cooled air compressor that separates the lubricating oil separated by the oil separator by the pressure of the compressed air discharged by the oil-cooled air compressor. A lubricant supply line that supplies the bearing space of the steam expander via a shut-off valve that shuts off the flow path when the engine stops, and a check valve that supplies the lubricant from the bearing space of the steam expander. And a lubricating oil recirculation line for supplying to the rotor chamber of the oil-cooled air compressor.

  According to this configuration, since the lubricating oil is also supplied to the steam expander by the discharge pressure of the oil-cooled air compressor, no additional equipment such as an oil pump or oil cooler dedicated to the steam expander is required, and the device configuration is simple. It is. In addition, since the lubricating oil is supplied to the steam expander via the shut-off valve and is circulated to the oil-cooled air compressor via the check valve, the apparatus stops and the suction force of the oil-cooled air compressor is reduced. Even if it disappears, the supply of lubricating oil by air pressure is cut off, so that the pressure in the bearing space can be prevented from significantly increasing.

  The steam expander-driven air compressor of the present invention connects the steam expander housing and the oil-cooled air compressor housing, bearing space at one end of the rotor shaft of the steam expander, and You may provide the connection housing which forms the connection space sealed integrally with the bearing space of the end of the rotor axis | shaft of the said oil-cooled type air compressor.

  According to this configuration, since the rotor shafts of the steam expander and the oil-cooled air compressor are not exposed to the outside, there is no fear that the lubricating oil leaks out from the periphery of the shaft, and the seal structure of the rotor shaft can be simplified.

  In the steam expander-driven air compressor of the present invention, the rotor shaft of the steam expander and the rotor shaft of the oil-cooled air compressor are connected via a gear accommodated in the connection space. Also good.

  According to this configuration, the mechanical efficiency is increased by selecting the gear ratio according to the load torque of the oil-cooled air compressor. Moreover, since the gear is accommodated in the connection space, the gear can also be lubricated by the lubricating oil supplied to the bearing space of the steam expander.

  In the steam expander-driven air compressor of the present invention, the steam expander may be a screw expander, and the oil-cooled air compressor may be a screw compressor.

  According to this configuration, since the torque fluctuation of the screw expander and the screw compressor is small, the operable pressure range is wide and stable operation can be performed.

  According to the present invention, since the lubricating oil is supplied to the bearing space of the steam expander by the discharge pressure of the oil-cooled air compressor, a dedicated lubrication system for the steam expander is unnecessary. In addition, lubricating oil is supplied via a shut-off valve and recirculated to the oil-cooled air compressor via a check valve, so that when the device stops, the bearing space of the steam expander becomes high pressure. Can be prevented.

Embodiments of the present invention will now be described with reference to the drawings.
FIG. 1: shows the outline | summary of the steam expander drive air compression apparatus 1 of one Embodiment of this invention. The steam expander-driven air compressor 1 includes a screw expander (expander) 2 that is a positive displacement steam expander and a screw compressor 3 that is a positive displacement air compressor.

  In the screw expander 2, a pair of male and female screw rotors 6 are accommodated in a rotor chamber 5 formed in a housing 4. The rotor shaft 7 of the screw rotor 6 is supported by bearings 9 and 10 disposed in the bearing space 8 on the intake side (high pressure side) and bearings 12 and 13 disposed in the bearing space 11 on the exhaust side (low pressure side). Has been. The space between the rotor chamber 5 and the bearing space 8 on the intake side is sealed with a seal member 14, and the space between the rotor chamber 5 and the bearing space 11 on the exhaust side is sealed with a seal member 15. The exhaust-side bearing space 11 is sealed by the housing 4, but the intake-side bearing space 8 is open in the axial direction, and the rotor shaft 7 protrudes from the housing 4.

  In the screw compressor 3, a pair of male and female screw rotors 18 are accommodated in a rotor chamber 17 formed in the housing 16. The rotor shaft 19 of the screw rotor 18 is supported by a bearing 21 disposed in the bearing space 20 on the suction side (low pressure side) and a bearing 23 disposed in the bearing space 22 on the discharge side (high pressure side). The bearing space 22 on the discharge side is sealed by the housing 16, but the bearing space 20 on the suction side is opened in the axial direction, and the rotor shaft 19 protrudes from the housing 16.

  The steam expander-driven air compressor 1 has a connection housing 24 that connects the open end of the housing 4 of the screw expander 2 and the open end of the housing 16 of the screw compressor 3. The housing 4, the housing 16, and the connection housing 24 define a connection space 25 that is sealed together with the bearing space 8 of the screw expander 2 and the bearing space 20 of the screw compressor 3.

  A drive gear 26 is disposed at the end of the screw expander 2 that protrudes from the housing 4 of the rotor shaft 7, and the end of the screw compressor 3 that protrudes from the housing 16 of the rotor shaft 19 is connected to the drive gear 26. A driven gear 27 having a greater number of teeth than the drive gear 26 is arranged. That is, the drive gear 26 and the driven gear 27 are accommodated in the connection space 25, and the rotation of the rotor shaft 7 of the screw expander 2 is decelerated and transmitted to the rotor shaft 19 of the screw compressor 3. ing.

  In the steam expander-driven air compressor 1, high-pressure steam is supplied from a boiler (not shown) to the screw expander 2 via the steam trap 28 and the capacity adjustment valve 29, and is expanded by the screw expander 2 to be predetermined. Low-pressure steam depressurized to pressure is supplied to a demand facility (not shown). Further, in the steam expander-driven air compressor 1, the high-pressure steam is decompressed by the pressure reducing valve 30 and can be supplied to the demand facility without going through the screw expander 2.

  The expansion force of the steam in the screw expander 2 is converted into the rotational force of the rotor shaft 7 by the screw rotor 6 and drives the rotor shaft 19 of the screw compressor 3 via the drive gear 26 and the driven gear 27 to drive the screw rotor. 18 is rotated. The screw compressor 3 generates a negative pressure on the suction side of the rotor chamber 17 by the rotation of the screw rotor 18 and sucks the outside air through the air filter 31. The compressed air compressed by the screw rotor 18 and discharged from the screw compressor 3 is introduced into the oil separator 32, the lubricating oil contained therein is separated, cooled by the aftercooler 33, and then supplied to the demand facility. Supplied.

  The lubricating oil separated by the oil separator 32 is supplied to the bearing space 8 of the screw expander 2 and the rotor chamber 17 of the screw compressor 3 via the automatic temperature control valve 34, the oil cooler 35 and the oil filter 36. It has become so. However, the lubricating oil supply line 37 that supplies lubricating oil to the bearing space 8 of the screw expander 2 is provided with a shut-off valve 38 that is an electromagnetic valve that shuts off the flow path when the screw compressor 3 stops. Further, the lubricating oil supplied to the bearing space 8 of the screw expander 2 leaks into the connection space 25 and lubricates the drive gear 26 and the driven gear 27. Excess lubricating oil flowing into the connection space 25 is supplied to the rotor chamber 17 of the screw compressor 3 via a lubricating oil circulation line 40 in which a check valve 39 is interposed.

  Further, the steam expander-driven air compressor 1 has a pressure detector 41 that detects the pressure of the compressed air in the outlet pipe of the oil separator 31 and a detection value of the pressure detector 41 that is a predetermined set value. And a PID controller 42 for controlling the opening degree of the capacity adjustment valve 27 on the intake side of the screw expander 2.

  In this embodiment, the lubricating oil separated by the oil separator 32 is supplied to the bearing space 8 of the screw expander 2 and the rotor chamber 17 of the screw compressor 3 by the pressure of the compressed air discharged by the screw compressor 3. Further, it is not necessary to separately provide ancillary equipment for supplying the lubricating oil between the screw expander 2 and the screw compressor 3, and a pump for pumping the lubricating oil is also unnecessary. For this reason, the steam expander-driven air compressor 1 has a simple configuration and can be provided at low cost.

  In the steam expander drive air compressor 1, the lubricating oil circulation line 40 is configured so that the flow path resistance is sufficiently small, and if the screw compressor 3 is operated, the suction pressure of the screw compressor 3 Lubricating oil is sucked from the bearing space 8 and the connection space 25 of the screw expander 2 so that the internal pressure of the bearing space 8 and the connection space 25 can be maintained at a low pressure close to atmospheric pressure.

  Further, in the steam expander-driven air compressor 1, even if the screw compressor 3 is stopped, the pressure inside the oil separator 32 immediately before the screw compressor 3 is stopped is maintained at a high pressure. Unless the valve 38 is closed, the lubricating oil is supplied to some extent to the bearing space 8 via the lubricating oil supply line 37 due to the pressure inside the oil separator 32. However, in this embodiment, since the shutoff valve 38 provided in the lubricating oil supply line 37 is closed, the supply of the lubricating oil to the bearing space 8 of the screw expander 2 is stopped.

  Furthermore, when the screw compressor 3 stops, the pressure on the suction side of the rotor chamber 17 increases due to leakage in the screw compressor 3, and there is a concern that the lubricating oil from the rotor chamber 17 to the connection space 25 may flow backward. However, in the present embodiment, the check valve 39 is provided in the screw lubricating oil circulation line 40, so that even if the pressure on the suction side of the rotor chamber 17 is increased due to leakage in the screw compressor 3, the screw compression is performed. The lubricating oil does not flow backward from the rotor chamber 17 of the machine 3 to the connection space 25.

  Due to the action of the shut-off valve 38 and the check valve 39, in the steam expander-driven air compressor 1, even when the screw compressor 3 is stopped, the lubricating oil to the bearing space 8 and the connection space 25 of the screw expander 2 is stopped. Therefore, the internal pressure of the bearing space 8 and the connection space 25 can maintain the pressure when the steam expander drive air compressor 1 is operated, and the internal pressure of the bearing space 8 and the connection space 25 can be maintained. Can be prevented from becoming higher than the permissible pressure (pressure close to atmospheric pressure restricted by the serviceable pressure of the seal member 14 or the like).

  Further, in the steam expander-driven air compressor 1, the connection space 25 integral with the bearing space 8 of the screw expander 2 and the bearing space 20 of the screw compressor is sealed. That is, the rotor shaft 7 of the screw expander 2 and the rotor shaft 19 of the screw compressor 3 are sealed by the housing 4 of the screw expander 2, the housing 16 of the screw compressor 3, and the connection housing 24. For this reason, in the steam expander-driven air compressor 1, lubricating oil is supplied from a portion where the rotor shaft 7 of the screw expander 2 passes through the housing 4 and a portion where the rotor shaft 19 of the screw compressor 3 passes through the housing 16. Do not leak outside. Thereby, the shaft seal structure of this part can be extended in life by adopting a non-contact seal, for example, or the shaft seal structure can be simplified or omitted. Further, unlike the prior art, a device for collecting the lubricating oil leaked from around the shaft is unnecessary.

  In the present invention, lubricating oil separated from the compressed air discharged from the screw compressor 3 is supplied to the bearing chamber 11 on the exhaust side of the screw expander 2 through the shut-off valve 38 or an independent shut-off valve by the pressure of the compressed air. Or sprayed directly onto the drive gear 26 and the driven gear 27 in the connection space 25 and circulated to the rotor chamber 17 of the screw compressor 3 via the check valve 39 or an independent check valve. Also good. The lubricating oil circulation line 40 may introduce the lubricating oil into the suction flow path from the air filter 31 to the rotor chamber 17 in addition to directly introducing the lubricating oil into the rotor chamber 17.

1 is a schematic diagram of a steam expander-driven air compression device according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Steam expander drive air compressor 2 ... Screw expander (steam expander)
3 ... Screw compressor (oil-cooled air compressor)
DESCRIPTION OF SYMBOLS 4 ... Housing 7 ... Rotor shaft 8 ... Bearing space 16 ... Housing 19 ... Rotor shaft 20 ... Bearing space 24 ... Connection housing 25 ... Connection space 26 ... Drive gear 27 ... Drive gear 32 ... Oil separator 35 ... Oil cooler 37 ... Lubricating oil supply line 38 ... Shut-off valve 39 ... Check valve 40 ... Lubricating oil recirculation line

Claims (4)

A steam expander,
An oil-cooled air compressor driven by the steam expander;
An oil separator for separating lubricating oil from the compressed air discharged by the oil-cooled air compressor;
The lubricating oil separated by the oil separator is passed through a shutoff valve that shuts off the flow path when the oil-cooled air compressor stops due to the pressure of compressed air discharged by the oil-cooled air compressor. A lubricating oil supply line that supplies the bearing space of the steam expander,
A steam expander drive air, characterized by having a lubricating oil recirculation line for supplying the lubricant from the bearing space of the steam expander to the rotor chamber of the oil-cooled air compressor through a check valve. Compression device.   The housing of the steam expander and the housing of the oil-cooled air compressor are connected, the bearing space of one end of the rotor shaft of the steam expander, and the bearing of one end of the rotor shaft of the oil-cooled air compressor The steam expander-driven air compressor according to claim 1, further comprising a connection housing that forms a sealed connection space integrally with the space.   The steam expander according to claim 2, wherein the rotor shaft of the steam expander and the rotor shaft of the oil-cooled air compressor are connected via a gear accommodated in the connection space. Driving air compressor.   The steam expander-driven air compressor according to any one of claims 1 to 3, wherein the steam expander is a screw expander, and the oil-cooled air compressor is a screw compressor.

Images