JPH0914868A - Air extractor - Google Patents

Abstract

PURPOSE: To prevent the deterioration of the extracting performance due to icing by cooling air due to the expansion of operating air at the time of restarting an air extractor. CONSTITUTION: This air extractor comprises a pressure equalizing means installed in an operating air tube 4 between an air ejector 3 and an operating air shut-off valve 5 to communicate the operating section of the so-called ejector 3 in the ejector 3 with the atmosphere in a tube partitioned by a shut-off valve 9 and a water ring vacuum pump 7 at the time of stopping the extractor 10 for closing the valve 5 and an extracted air shut-off valve 2 with the atmosphere to hold it substantially at the atmospheric pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention makes an air ejector working section partitioned by an operating air shutoff valve, an extraction air shutoff valve, and a sealed water type vacuum pump communicate with the atmosphere when the operation is stopped, and the air ejector working section is exposed to atmospheric pressure. The present invention relates to an air extraction device configured to have a substantially uniform pressure.

[0002]

2. Description of the Related Art FIG. 2 shows an air extraction device that has been conventionally used in an air extraction device such as a condenser that is operated under a vacuum of atmospheric pressure or less. As shown in the figure,
The conventional air extraction device 010 has one end connected to an air extraction device such as a condenser (not shown) that is operated under a vacuum of atmospheric pressure or less, extracts air in the air extraction device, and an air ejector described later. Air extraction pipe 01 transferred to 03, extraction air cutoff valve 02 interposed in air extraction pipe 01, one end connected to the compressed air source, and air ejector 0 connected to the other end
Working air pipe 04 for supplying working air to 3, working air pipe 0
4, a working air cutoff valve 05, a discharge pipe 06 having one end connected to the exhaust port of the air ejector 03 and discharging working air and bleed air to the atmosphere, and sealing water interposed in the discharge pipe 06. Mold vacuum pump 07.

During the operation of the air extracting device 010, the extracted air extracted from the air-extracted equipment is the extraction air cutoff valve 02, the air ejector 03, and the sealed water vacuum pump 0.
It is released to the atmosphere through 7 and the degree of vacuum in the air extraction equipment is increased. Further, the working air that drives the air ejector 03 is introduced from the working air cutoff valve 05, drives the air ejector 03, and generates a suction force, and the air ejector 03 passes through the extraction air cutoff valve 02 and the air extraction pipe 01. Along with the extracted air from the air extraction equipment that has been sucked into the inside of 03,
It is discharged to the atmosphere and the like through the sealed water vacuum pump 07.

When the air extraction device 010 is not operated, the exhaust air cutoff valve 02 is closed so that the vacuum in the air extraction equipment is maintained, and then the operation air cutoff valve 05 is turned on. The air ejector 03 is closed and the operation of the air ejector 03 is stopped.
Therefore, in a state where the operation of the air extraction device 010 is stopped, the extraction air pipe 01 communicating with the air ejector 03, which is partitioned by the extraction air cutoff valve 02, the working air cutoff valve 05, and the sealed water type vacuum pump 07, respectively. , Working air pipe 0
4 and the inside of the exhaust pipe 06 and the inside of the air ejector 03, the pressure of the air ejector working section is normally kept at atmospheric pressure.

However, the extraction air cutoff valve 02 provided in the air extraction pipe 01, which connects the air ejector 03 with the inside of the air extraction device such as a condenser that is at atmospheric pressure or less, is not completely closed, or If a small amount of leakage occurs due to a defect in the seal portion, the pressure in the air ejector operating section becomes a negative pressure that is approximately the same as that in the air extraction device, and the sealing water type vacuum pump 07 operates the operating water in this portion. May be sucked up to form a water pool.

As described above, when the air extractor 010 is restarted in the state where the water pool is generated in the air ejector working section, the air ejector is operated by the working air whose temperature becomes low due to the adiabatic expansion driven by the air ejector 03. The pooled water in the compartment is cooled and freezes, which significantly reduces the air extraction performance.

Further, in order to eliminate such a problem,
Even when the air extraction device 010 is stopped, it may be considered that the operating air cutoff valve 05 is kept open to prevent the air ejector operating section from becoming negative pressure and prevent water pooling. In such a case, since the working air cutoff valve 05 having a large diameter is used, if the extraction air cutoff valve 02 is opened by mistake, or the extraction air cutoff valve 02 has a damaged seal portion or the like. In the case of the above problem, a large amount of air will flow into the air extraction device such as a condenser, and the vacuum in the air extraction device will be instantly broken. is there. For this reason, it is not possible to adopt this problem solving measure by opening the working air cutoff valve 05 while the air extraction device 010 is stopped.

[0008]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the conventional air extraction device. Therefore, even if the extraction air cutoff valve is operated erroneously, a large amount of air may flow into the air extraction equipment. In addition, the air ejector operating section can be kept at atmospheric pressure even when there is a small amount of leakage in the extraction air shutoff valve that holds the vacuum of the air extraction equipment when the air extraction device is not operating. An object of the present invention is to provide an air extraction device that does not cause performance degradation when the device is restarted.

[0009]

Therefore, the air extraction apparatus of the present invention has the following means. The working air cutoff valve installed in the working air pipe that supplies working air to the air ejector, and the extraction air cutoff valve installed in the air extraction pipe that sucks the extraction air from the air extraction equipment by the air ejector. When shut down, the working air shutoff valve, the extraction air shutoff valve, and the working air pipe partitioned by a water-sealed vacuum pump,
The inside of each of the extraction air pipe and the exhaust pipe that discharges the exhaust air of the air ejector to the atmosphere and the inside of the air ejector operating section that is composed of the inside of the air ejector are connected to the atmosphere, and the pressure inside the air ejector operating section is set to the atmospheric pressure. A pressure equalizing means that is substantially equal to is provided in the working air pipe between the working air cutoff valve and the air ejector.

The pressure equalizing means has a small amount of leakage from the air ejector operating section to the air extraction equipment when the extraction air cutoff valve is closed, so that the inside of the working air pipe is open to the atmosphere. It is preferable that the pressure pipe and the shut-off valve provided in the pressure equalizing pipe are used.

Further, even if the shut-off valve is opened / closed by manual operation before (after) the operation of the air extractor to equalize the pressure in the air ejector operating section, the air ejector can be operated only when the air extractor is stopped. The pressure may be equalized by detecting the pressure in the working section and opening and closing it.

In addition to the above-mentioned shutoff valve, the pressure equalizing pipe is
By installing the throttle mechanism such as the orifice and the check valve individually or collectively, the additional function of the pressure equalizing means can be increased.

[0013]

In the air extractor, the operation of the air extractor is stopped by closing the upstream piping, that is, the working air pipe, the working air shutoff valve installed in each of the air extraction pipes, and the extraction air shutoff valve. In the above, the air ejectors arranged downstream of these shutoff valves are normally maintained at atmospheric pressure, and no water pool is generated in the air ejector operating section. On the other hand, when a slight amount of leakage occurs from the extraction air cutoff valve, the air ejector operating section gradually becomes negative pressure, and a water pool is generated in the air ejector operating section.

However, in the air extracting device of the present invention, the air ejector operating section does not have a negative pressure for equalizing the atmospheric pressure and the water pool does not occur due to the above-mentioned means.

As a result, at the time of re-operation of the air extraction device,
It is possible to prevent deterioration of the air extraction performance of the air extraction device due to freezing of pooled water in the air ejector working section. This means
To put it the other way around, the extraction air cutoff valve used in the conventional air extraction device is required to be a complete one that does not cause leakage and sufficiently cuts off the air extraction pipe, whereas the air extraction valve of the present invention is required. In the device, it is possible to use a device that allows a minute amount of leakage.

Further, even if the extraction air cutoff valve is erroneously opened when the air extraction device is stopped, the vacuum of the air extraction equipment will not be lost instantaneously. Further, since the pressure equalizing pipe is installed in the working air pipe, the air flowing from here is consumed as a part of the working air of the air ejector even in a normal operating state even when the shutoff valve is left open. , It does not affect the air extraction performance.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the air extraction device of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram showing an embodiment of the air extraction device of the present invention.

In the figure, reference numeral 1 denotes a condenser or the like, one end of which is connected to an air extraction device (not shown), which discharges air from the inside and operates by making the inside close to a vacuum state. , Extraction air B discharged from inside the air extraction equipment
The air extraction pipe 2 for transferring the air to the air ejector 3 is disposed in the middle of the air extraction pipe 1, and flows inside the air extraction pipe 1.
It is an extraction air cutoff valve that shuts off the extraction air B or the air flowing from the air ejector 3 side to the air extraction target equipment.

One end of the working air pipe 4 is connected to a pressure air source (not shown), and a working air pipe 5 for supplying the working air D to the air ejector 3 is arranged in the middle of the working air pipe 3 to connect the working air pipe 4 with the working air pipe 4. It is a working air cutoff valve that shuts off working air flowing inside. In some cases, instead of the above-mentioned working air D, steam may be used.

Reference numeral 3 denotes an air ejector, which expands the working air D supplied from the working air pipe 4 by means of a nozzle to increase the speed thereof, thereby generating a vacuum in the peripheral portion of the flow of the working air D and extracting air B. Is sucked from the air extraction device via the extraction air pipe 1, and is discharged to the discharge pipe 6 together with the working air D.

Reference numeral 7 denotes a water-sealed vacuum pump, which is arranged in the middle of the discharge pipe 6, eccentrically rotates the impeller in the cylindrical casing, and causes an empty space to be formed in the center by the centrifugal force of the sealed water inside. The air is sucked and discharged by using the air, and the working air and the extracted air from the air ejector 3 are discharged to the atmosphere.

Reference numeral 8 denotes a pressure equalizing tube which constitutes a pressure equalizing means together with a shutoff 9 which will be described later, and is installed in the working air pipe 4 between the working air shutoff valve 5 and the air ejector 3, and the inside of the working air pipe 4 is exposed to the atmosphere. Communicate with. The pressure equalizing pipe 8 is composed of a pipe having a remarkably small diameter as compared with the working air pipe 4. A cutoff valve 9 is provided in the middle of the pressure equalizing pipe 8 and shuts off the communication with the atmosphere in the working air pipe 4.

The air extraction device 10 of this embodiment is constructed as described above, but in addition to this, a check valve or a throttling mechanism such as an orifice is provided in the pressure equalizing pipe to function as a pressure equalizing means. You may raise it. It is also possible to detect the operation signals of the working air cutoff valve 5, the extraction air cutoff valve 2, and the pressure in the working air pipe 4, and to operate the cutoff valve 9 by these detection signals. .

Since the air extraction apparatus 10 of this embodiment is constructed as described above, the operation air cutoff installed in the upstream piping of the air extraction apparatus 10, that is, the operation air pipe 4 and the extraction air pipe 1 is cut off. When the valve 5 and the extraction air cutoff valve 2 are closed and the air extraction device is stopped, the extraction air pipe 1 from the extraction air cutoff valve 2 to the air ejector 3
The so-called air ejector working section consisting of the inside, the working air pipe 4 from the working air shutoff valve 5 to the air ejector 3, the exhaust pipe 8 from the air ejector 3 to the water-sealed vacuum pump, and the inside of the air ejector 3, Since there is no inflow or outflow of air, it is normally maintained at atmospheric pressure.

However, in this state, when leakage occurs in the closed extraction air cutoff valve 2, the pressure in the air ejector operating section is the upstream pressure of the extraction air cutoff valve 2, that is, the extraction air pipe 1. Attempts to reach a negative pressure that is about the same as the pressure in the air extraction device such as a condenser communicated with the air, but the atmosphere is operated from the pressure equalizing pipe 8 provided in the working air pipe 4 through the shutoff valve 9. As it flows into the air tube 4, the pressure in the air ejector working compartment is still maintained at atmospheric pressure.

As a result, water is not sucked up by the sealed water type vacuum pump 7 or the like into the pneumatic ejector working section due to the decompression, and a water pool is not generated. When the air extraction device is started, the air ejector ejects the water. The low temperature air does not cause freezing, which significantly reduces the air extraction performance. Further, the extraction air cutoff valve 2 used in this embodiment can be one that allows a slight amount of leakage.

Further, in this embodiment, the equalizing pipe 8 having a remarkably smaller diameter than that of the working air pipe 4 is provided, so that the extraction air cutoff valve 2 is erroneously opened when the air extracting device is stopped. Even if this happens, a large amount of air will not be injected into the air extraction equipment and the vacuum will not be lost instantaneously. Further, by installing the pressure equalizing pipe 8 in the working air pipe 4, even if the air extraction device 10 is operated with the shutoff valve opened in the normal operation state, the air flowing in from here is the air ejector. Since it is discharged from the exhaust pipe 6 as a part of the working air, the air extraction performance is not affected.

[0028]

According to the air extraction apparatus of the present invention, the following effects can be obtained by the constitutions set forth in the claims. (1) Even if a small amount of leakage occurs in the extraction air cutoff valve of the upstream side pipe while the air extraction device is stopped, the air ejector operating section keeps the atmospheric pressure. The performance of the extractor does not deteriorate. (2) The extraction air cutoff valve installed in the upstream pipe of the air extraction device can tolerate a slight amount of leakage. (3) Even if the extraction air shut-off valve is accidentally opened while the air extraction device is stopped, the vacuum inside the air extraction device is maintained, and various changes are accompanied by a momentary vacuum break of the air extraction device. The problem of can be solved. (4) Even if the air extraction device is operated with the shutoff valve open, the performance of the air extraction device is hardly affected.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of an air extraction device of the present invention.

FIG. 2 is a system diagram of a conventional air extraction device.

[Explanation of symbols]

 1 air extraction pipe 2 extraction air cutoff valve 3 air ejector 4 working air pipe 5 working air cutoff valve 6 exhaust pipe 7 water-sealed vacuum pump 8 pressure equalizing pipe 9 cutoff valve 10 air extraction device

Claims (1)

[Claims] 1. An air ejector for extracting air in an air extraction device to reduce the pressure to atmospheric pressure or less, a working air cutoff valve interposed in a working air pipe for supplying working air to the air ejector,
Air having an extraction air cutoff valve installed in an air extraction pipe that communicates the air extraction device with the ejector, and a sealed water vacuum pump installed in an exhaust pipe that discharges the exhaust air of the air ejector to the atmosphere. In the extraction device, installed in the working air pipe between the air ejector and the working air cutoff valve,
An air extraction device, characterized in that, when the working air cutoff valve and the extraction air cutoff valve are closed, a pressure equalizing means is provided which communicates with the atmosphere to make the air ejector working section have a pressure substantially equal to atmospheric pressure.