JP2542037B2 - Oil free screw compressor pre-curler - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a precooler for an oil-free screw compressor, and more particularly to a precooler for a compressor that can relieve thermal stress under high temperature conditions. Used in screw compressors.

[Conventional technology]

As a conventional device, for example, a structure using a water-cooling type precooler (heat exchanger) is known as described in JP-A-60-85286.

The oil-free screw compressor using this water-cooling type precooler has a problem that scales are accumulated as the operating time elapses due to the quality of the cooling water and the cooling effect is reduced.

[Problems to be Solved by the Invention]

In the above prior art, the cooling of the precooler is a water cooling type or a liquid cooling type. The water-cooled type has the drawback that the cooling function is significantly deteriorated due to the accumulation of scale due to the quality of the cooling water over the operating time, which is a problem in the operation management of the compressor.

In addition, the liquid cooling type precooler (which cools with a coolant, etc.) has a large cooling device (cooler and fan) for the cooling liquid that has undergone heat exchange by liquid cooling, and is therefore applicable to small capacity screw compressors. However, there is a problem that it is difficult to apply to a large capacity screw compressor.

In addition, the need for commercialization of air-cooled oil-free screw compressors is increasing, and air cooling of pre-coolers and after-coolers is being promoted. It has been recognized that when the precooler is air-cooled, the thermal stress due to the temperature difference during the air-cooling under a high temperature condition becomes particularly large, and that a large thermal stress is generated due to the load variation of the compressor, as new problems.

An object of the present invention is to provide a small and compact air-cooling type precooler suitable for solving the above problems and producing a large-capacity air-cooled oil-free screw compressor. An object of the present invention is to provide a precooler for an oil-free screw compressor, in which thermal stress due to a temperature difference during air cooling in an air-cooling type precooler having a high inlet temperature is relaxed and reliability of a piping system is improved.

[Means for solving the problem]

In order to achieve the above object, the configuration of the precooler of the oil-free screw compressor according to the present invention, the discharge piping system from the compressor body, the air-cooled type that temporarily cools the high temperature air discharged from the compressor body. In the precooler in an oil-free screw compressor including a precooler, a check valve, and an air-cooled aftercooler, an inlet header connected to the discharge port of the compressor body of the precooler, and the aftercooler side. An outlet header that is connected to the outlet header is provided close to the same side, and a plurality of rows of cooling pipes that connect the inlet header and the outlet header are connected to each other by the inlet header and the outlet header. The U-shaped cooling pipe with a width that does not interfere with this U-shaped cooling pipe
The inlet side header, the connecting side with the outlet part header is fixed,
The U-shaped side is a free end of support that is not constrained in the direction of the apex of the U-shape.

[Action]

 The functions of the above technical means are as follows.

The air-cooled precooler is composed of an inlet header, an outlet header and a cooling pipe connecting them.

Extremely high temperature air (about 300-350 ° C) discharged from the oilless rotary compressor enters the precooler and is air-cooled, so it is necessary to reduce the thermal stress due to the temperature difference.

Therefore, the inlet header and the outlet header of the precooler are arranged close to each other on the same side, and this is the fixed side of the cooling pipe. That is, the cooling pipe connecting the two headers is U-shaped, and the inlet header and the outlet header are fixed in the same direction. On the other hand, since the U-shaped cooling pipe is free in the apex direction (U-shaped side), it thermally expands in this direction. The direction of thermal expansion is free, and because it is not restrained, the thermal stress due to thermal expansion is relaxed for the entire precooler, and it can be used as an air-cooled precooler suitable for practical use.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a system diagram of a general air-cooled oil-free screw compressor, FIG. 2 is a diagram showing a configuration of an air-cooled precooler according to an embodiment of the present invention, and (a) is a top view,
(B) is a front view and (c) and (d) are left and right side views.

First, the overall configuration and operation of the air-cooled oil-free screw compressor and the function of the precooler will be described with reference to FIG.

Compressed air flow is through a suction filter (not shown)
The air sucked in from is increased to a predetermined pressure of 7 kg / cm ² g by the compressor body 1 of the oil-free screw compressor. Due to this, the discharge air heated to about 300 to 350 ° C. enters the air-cooling type precooler 8 via the discharge pipe 7.
The discharge air is cooled here to about 100 to 150 ° C., enters the aftercooler 10 via the check valve 9, and further about 50
It is cooled to ℃ and discharged. The check valve 9 is the compressor body 1
Is to prevent backflow of air from the aftercooler 10 side when there is no load.

The compressor body 1 is driven by increasing the rotational force of the motor 2 by the V-belt 3 to the gear shaft 4 in the gear case 14 and transmitting it, and by rotating the pair of screws at high speed by the speed increasing gear 5. .

A lubricating device is provided to lubricate gears and bearings (not shown) of the compressor body 1. That is, the oil pump 16 is attached to the shaft end of the gear shaft 4, and the gear case
Lubricating oil 15 stored in the lower part of this oil pump 16
Is sucked up, cooled by an air-cooled oil cooler 17, and this lubricating oil is supplied to the bearings and gears of the compressor body 1.

A jacket 11 is arranged around a casing (not shown) of the compressor body 1, and a coolant is supplied to the jacket 11 for cooling. This coolant is circulated by a dedicated coolant pump 12 and cooled by a coolant cooler 13 for use.

The after cooler 10, the oil cooler 17, the coolant cooler 13, and the air-cooling type precooler 8 are air-cooled by the ventilation fan 19. 18 is a solenoid valve for control, 20
Indicates an exhaust port.

The capacity is adjusted by the suction throttle valve 6 with respect to the load fluctuation of the compressor.

Next, referring to FIG. 2 in addition to FIG. 1, the air-cooling type precooler of this embodiment will be described.

In FIG. 2, 21 is a precooler inlet connected to the discharge pipe 7 of the compressor body 1, 22 is an inlet header, 24 is an outlet header, and 25 is an aftercooler 10 via a check valve 9.
Is the precooler outlet connected to. As shown in FIG. 2A, the inlet header 22 and the outlet header 24 are displaced in the longitudinal direction of the U-shaped pipe so as not to interfere with each other, and are arranged close to each other on the same side.

Reference numeral 23 denotes a plurality of rows of cooling pipes that connect the inlet header 22 and the outlet header 24. The cooling pipe 23 has a U-shape having a width such that the inlet header 22 and the outlet header 24 do not interfere with each other.
The connecting side with the outlet header 24 is fixed in the same direction, and the U-shape is a free end of support that is not constrained in the direction of the apex of the U-shape. That is, the cooling pipe 23 is supported by the support 26, but is not fixed. As the material of each tube of these air-cooled precoolers, stainless steel is used in consideration of the high inlet temperature, the air passing through the tube being oil-free and free of oil.

High-temperature (about 300 to 350 ° C.) air discharged from the compressor body 1 enters the air-cooled precooler from the precooler inlet portion 21 via the discharge pipe 7. The hot air entering from here is branched into a plurality of rows of cooling pipes 23 from the inlet header 22 to cool the hot air in the pipes.

The cooled air reaches about 100-150 ℃, and the outlet header
Collected at 24, it is sent from the precooler outlet 25 to the aftercooler 10 via the check valve 9.

As described above, the cooling pipe 23 has a U-shape and is fixed to the inlet header 22 and the outlet header 24 in the same direction.

However, the apex direction of the U-shape of the cooling pipe is free from elongation and is not fixed.

Therefore, with respect to the thermal expansion due to the high inlet air temperature of the cooling pipe 23, one side is made free so that it does not receive excessive thermal stress.

 According to this embodiment, there are the following effects.

(1) The thermal stress under high temperature conditions is reduced, and the life of the air-cooled cooler is significantly extended.

(2) It is possible to follow the load variation of the compressor, and the thermal stress due to the temperature difference can be reduced.

(3) Since the inlet header and the outlet header are arranged close to each other on the same side so as not to interfere with each other, a thin, compact and compact precooler can be realized.

(4) The downsizing of the air-cooled precooler has made it possible to apply it to large-capacity screw compressors that could not be realized with the liquid-cooled precooler.

〔The invention's effect〕

As described in detail above, according to the present invention, in an air-cooled precooler having a high inlet air temperature, an oil-free screw compression that alleviates thermal stress due to a temperature difference during air cooling and enhances reliability of a piping system is provided. A machine pre-cooler can be provided.

Further, as a result, it is possible to provide a small and compact air-cooling type precooler that contributes to the commercialization of a large-capacity air-cooled oil-free screw compressor.

[Brief description of drawings]

FIG. 1 is a system diagram of a general air-cooled oil-free screw compressor, and FIG. 2 is a diagram showing a configuration of an air-cooled precooler according to an embodiment of the present invention. 1 ... Compressor body, 2 ... Motor, 6 ... Suction throttle valve,
7 ... Discharge pipe, 8 ... Air-cooled precooler, 9 ... Check valve, 10 ... Aftercooler, 12 ... Coolant pump,
13 …… Coolant cooler, 16 …… Oil pump, 17 ……
Oil cooler, 19 ... Ventilation fan, 21 ... Precooler inlet, 22 ... Inlet header, 23 ... Cooling pipe, 24 ... Outlet header, 25 ... Precooler outlet, 26 ... Support.

Claims (1)

(57) [Claims] 1. An oil system comprising an air-cooling type precooler for primarily cooling high temperature air discharged from the compressor body, a check valve, and an air-cooling type aftercooler in a discharge piping system from the compressor body. In the precooler of a free screw compressor, an inlet header connected to the discharge port of the compressor body and an outlet header connected to the aftercooler side of the precooler are provided on the same side in close proximity to each other. The plurality of rows of cooling pipes that connect between the section header and the outlet header are U-shaped with a width such that the inlet header and the outlet header do not interfere with each other. An oil-free screw characterized in that a connecting side of the inlet header and the outlet header is fixed, and a U-shaped side is a supporting free end that is not constrained in a vertex direction of the U-shaped. Pre-cooler of the compressor.