JPH0979140A - Vacuum pump device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly efficient, inexpensive and simple fixed speed multistage vacuum pump device. SOLUTION: A turbo type vacuum pump 2 is arranged as a first stage, and a positive displacement vacuum pump 4 is arranged as a second stage. Therefore, the turbo type vacuum pump 2 of the first stage is always operated in the constant pressure ratio with high efficiency, and the positive displacement vacuum pump 4 of the second stage absorbs a delivery pressure change in the turbo type vacuum pump 2 of the first stage since an efficiency change is small to a pressure ratio change.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum pump device for sucking gas from a tank or the like, and is useful when applied to a vacuum pump device used in a vacuum type PSA gas manufacturing device or the like.

[0002]

2. Description of the Related Art FIG. 5 is a system diagram showing an example of a conventional vacuum pump device. FIG. 5 shows an example of a fixed speed two-stage positive displacement (roots) vacuum pump device.

In FIG. 5, reference numeral 1 denotes a tank, and the gas in the tank 1 is suction-compressed by the positive displacement vacuum pump 12 in the first stage, and the high temperature and high pressure gas in the first stage is cooled by the intercooler 3. After being compressed, it is suction-compressed by the second-stage positive displacement vacuum pump 4 and discharged into the atmosphere or a desired location such as an air storage tank.

FIG. 6 is a system diagram showing another example of a conventional vacuum pump device. FIG. 5 shows an example of a fixed speed two-stage turbo vacuum pump device. In the fixed-speed two-stage turbo vacuum pump device shown in FIG. 5, the first-stage and second-stage vacuum pumps are turbo vacuum pumps 22 and 24. The fixed-speed two-stage positive displacement vacuum pump device (see FIG. 5). But the function is the same. The turbo vacuum pumps 22 and 24 are operated at a fixed speed / constant pressure ratio, and a damper (inlet throttle) 5 provided between the first-stage turbo vacuum pump 22 and the tank 1 is accompanied by decompression of the tank 1. The opening is increased, and when the final degree of vacuum is reached, it is adjusted so as to be fully opened.

[0005]

FIG. 7 shows a graph of the first stage inlet pressure and efficiency ratio in the conventional fixed speed two-stage positive displacement vacuum pump apparatus and fixed speed two-stage turbo vacuum pump apparatus. In this figure, as an example, the final ultimate pressure of the tank is 0.3 ata and the vacuum pump inlet pressure is 0.45 ata.
~ 0.3 ata (pressure ratio: 2.31 to 3.47, discharge pressure: 1.04 ata) is shown.
In FIG. 7, a solid line is a graph of a fixed speed two-stage positive displacement vacuum pump device, and a broken line is a graph of a fixed speed two-stage turbo vacuum pump device.

As shown in FIG. 7, the fixed-speed two-stage positive displacement vacuum pump device has a lower maximum efficiency than the fixed-speed two-stage turbo vacuum pump device, and particularly the volume efficiency in a low pressure (high pressure ratio) region. However, there is a drawback in that the pump efficiency is lowered because On the other hand, in the fixed speed two-stage turbo vacuum pump device, although the maximum efficiency is high, since it is a fixed speed, the constant pressure ratio operation is performed by controlling the damper (inlet throttle), and the damper opening is high and the high pressure (low pressure ratio) is small. There is a drawback that the efficiency reduction in the area is large. Although it is conceivable to use a variable speed in order to solve this second point, this causes a problem that the equipment cost of the control device such as the frequency converter increases and the configuration becomes complicated.

Therefore, in view of the above-mentioned prior art, it is an object of the present invention to provide a fixed-speed multistage vacuum pump device which is efficient, low-cost and simple.

[0008]

A vacuum pump device of the present invention for solving the above problems is a fixed-speed multistage vacuum pump device for sucking gas from a tank or the like, and is one or more turbo type vacuum pumps. Are arranged as a front stage or a front stage group, and 1
One or two or more positive displacement vacuum pumps are arranged as a rear stage or a rear stage group.

As shown in FIG. 7, although the displacement type vacuum pump has a lower maximum efficiency than the turbo type vacuum pump,
It is characterized in that the change in efficiency is relatively small with respect to the change in inlet pressure. Generally, the change in flow rate and efficiency with respect to change in pressure ratio is smaller than that of the fixed speed turbo vacuum pump, and the characteristics are flat. On the other hand, the fixed-speed turbo vacuum pump has a high maximum efficiency, but the efficiency changes largely with the fluctuation of the inlet pressure. This is a turbo vacuum pump with a constant pressure ratio,
This is because it is operated with high efficiency, but since the pressure ratio is adjusted by damper (inlet throttle) control, the pressure loss of the damper is large in the high pressure (low pressure ratio) region. Further, in the fixed-speed turbo vacuum pump, even if the pressure ratio is changed without a damper, the efficiency fluctuation with respect to the change of the pressure ratio becomes large, and it is difficult to achieve high efficiency.

Therefore, the vacuum pump device is constructed as described above.

According to the vacuum pump device having the above structure, FIG.
As described in detail below (details will be described later), the turbo vacuum pump of the preceding stage (or the preceding stage group) operates at a constant pressure ratio without an inlet throttle, and the discharge pressure decreases as the inlet pressure decreases, that is,
The inlet pressure of the latter-stage (or latter-stage group) positive displacement vacuum pump decreases, but since the discharge pressure of this positive displacement vacuum pump is constant, the pressure ratio increases as the inlet pressure decreases. For this reason, the turbo vacuum pump in the front stage (or the front stage group) always operates at a constant pressure ratio and high efficiency, and the volumetric vacuum pump in the rear stage (or the rear stage group) has small fluctuations in efficiency with respect to pressure ratio fluctuations. Absorbs the discharge pressure fluctuation of the turbo vacuum pump (or the former group). Therefore, the present vacuum pump device has high efficiency and is simple because it does not require a control device such as a damper (inlet throttle).

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a system diagram of a vacuum pump device according to an embodiment of the present invention. FIG. 1 shows an example of a fixed speed two-stage vacuum pump device.

As shown in FIG. 1, a turbo vacuum pump 2
Is arranged as a first stage and connected to the tank 1, and the positive displacement vacuum pump 4 is arranged as a second stage by interposing the intercooler 3. Therefore, the gas in the tank 1 is suction-compressed by the turbo vacuum pump 2 in the first stage, and the high temperature and high pressure gas in the first stage is cooled by the intercooler 3 and then by the positive displacement vacuum pump 4 in the second stage. It is suction-compressed and released into the atmosphere or to the intended location such as an air storage tank.

As shown in FIG. 7, the maximum efficiency of the displacement type vacuum pump is lower than that of the turbo type vacuum pump,
It is characterized in that the change in efficiency is relatively small with respect to the change in inlet pressure. Generally, the change in flow rate and efficiency with respect to change in pressure ratio is smaller than that in the fixed-speed turbo vacuum pump, and the characteristics are flat. On the other hand, the fixed-speed turbo vacuum pump has a high maximum efficiency, but the efficiency changes largely with the fluctuation of the inlet pressure. This is a turbo vacuum pump with a constant pressure ratio,
This is because it is operated with high efficiency, but since the pressure ratio is adjusted by damper (inlet throttle) control, the pressure loss of the damper is large in the high pressure (low pressure ratio) region. Further, in the fixed-speed turbo vacuum pump, even if the pressure ratio is changed without a damper, the efficiency fluctuation with respect to the change of the pressure ratio becomes large, and it is difficult to achieve high efficiency.

Therefore, as described above, the turbo vacuum pump 2 is provided as the first stage and the positive displacement vacuum pump 4 is provided as the second stage.

FIG. 2 shows a graph of the first stage inlet pressure, the pressure ratio and the discharge pressure in the vacuum pump apparatus according to this embodiment. In this figure, as an example, the final ultimate pressure of the tank is 0.
At 3ata, the vacuum pump inlet pressure is 0.45ata ~
The case where operation is performed at 0.3 ata (pressure ratio: 2.31 to 3.47, discharge pressure: 1.04 ata) is shown.
In FIG. 2, the broken line is a graph of the first stage turbo vacuum pump 2 and the solid line is a graph of the second stage positive displacement vacuum pump 4.

As shown in FIG. 2, the first stage turbo vacuum pump 2 operates at a constant pressure ratio without an inlet throttle, and the discharge pressure of the first stage decreases as the inlet pressure decreases, that is, the volume of the second stage. Although the inlet pressure of the positive vacuum pump 4 decreases, the positive pressure type vacuum pump 4 has a constant discharge pressure, so that the pressure ratio increases as the inlet pressure decreases. Therefore, the first-stage turbo vacuum pump 2 is constantly operated at a constant pressure ratio and high efficiency,
Since the volumetric vacuum pump 4 in the latter stage has a small efficiency variation with respect to the pressure ratio variation, it absorbs the discharge pressure variation of the first stage turbo vacuum pump 2.

FIG. 3 shows a graph of the first stage inlet pressure and the efficiency ratio in the vacuum pump device according to this embodiment. FIG. 3
Is an example of operation similar to FIG. In FIG. 3, the solid line is shown in FIG.
6 is a graph of the conventional fixed speed two-stage positive displacement vacuum pump device, the broken line is the graph of the conventional fixed speed two-stage turbo vacuum pump device shown in FIG. 6, and the alternate long and short dash line is the vacuum pump device according to this embodiment. Is a graph of. As shown in FIG. 3, the vacuum pump device according to the present embodiment has a small efficiency change with respect to the fluctuation of the first stage inlet pressure, and is highly efficient.

In the above description, the case of the two-stage vacuum pump device in which one turbo-type vacuum pump 2 is arranged in the front stage and one positive-displacement vacuum pump 4 is arranged in the rear stage has been described. However, the configuration may be as shown in FIG. 4, for example.

In the vacuum pump device shown in FIG. 4, two turbo vacuum pumps 2a and 2b connected in series are arranged as a pre-stage group, and an intercooler 3 is sandwiched between the two pumps connected in series. The vacuum pumps 4a and 4b are arranged as a rear stage group. Although there are many variations in the number of connected turbo vacuum pumps in the front stage group, the number of inserted intercoolers, and the number of connected positive displacement vacuum pumps in the rear stage group, they are omitted here.

As described above, this embodiment has the following effects. (1) The efficiency of the fixed speed vacuum pump device is improved, and the power consumption can be reduced. (2) The combination of the turbo vacuum pump and the positive displacement vacuum pump eliminates the need for a control device such as a damper (inlet throttle), which simplifies the configuration and reduces the cost. (3) Since the turbo vacuum pump is the front stage or the front stage group, the volumetric vacuum pump of the rear stage or the rear stage group can be downsized, and the entire apparatus can be downsized.

[0023]

As described above in detail with the embodiments of the invention, according to the present invention, one or more turbo type vacuum pumps are arranged as a front stage or a front stage group, and one or two turbo vacuum pumps are provided. The following effects can be obtained by arranging the positive-displacement vacuum pumps of the number of stages or more in the latter stage or the latter stage group. (1) The efficiency of the fixed speed vacuum pump device is improved, and the power consumption can be reduced. (2) The combination of the turbo vacuum pump and the positive displacement vacuum pump eliminates the need for a control device such as a damper (inlet throttle), which simplifies the configuration and reduces the cost. (3) Since the turbo vacuum pump is the front stage or the front stage group, the volumetric vacuum pump of the rear stage or the rear stage group can be downsized, and the entire apparatus can be downsized.

[Brief description of drawings]

FIG. 1 is a system diagram of a vacuum pump device according to an embodiment of the present invention.

FIG. 2 is a graph of a first stage inlet pressure, a pressure ratio, and a discharge pressure in the vacuum pump device shown in FIG.

FIG. 3 is a graph of the first stage inlet pressure and efficiency ratio in the vacuum pump device shown in FIG.

FIG. 4 is a system diagram of a vacuum pump device according to another embodiment of the present invention.

FIG. 5 is a system diagram showing an example of a conventional vacuum pump device.

FIG. 6 is a system diagram showing another example of a conventional vacuum pump device.

7 is a graph of the first stage inlet pressure and efficiency ratio in the vacuum pump device shown in FIG. 5 and the vacuum pump device shown in FIG.

[Explanation of symbols]

 2,2a, 2b Turbo type vacuum pump 4,4a, 4b Positive displacement type vacuum pump

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masafumi Kawashima, 1-1 Masatoura-cho, Nagasaki-shi, Nagasaki Nagasaki Shipyard, Mitsubishi Heavy Industries, Ltd. (72) Hiroyuki Iwayoshi 1-1, Atsunoura-cho, Nagasaki-shi, Nagasaki Nagahishi Design stock company

Claims (1)

[Claims] 1. A fixed-speed multi-stage vacuum pump device for sucking gas from a tank or the like, wherein one or more turbo type vacuum pumps are arranged as a pre-stage or a pre-stage group, and 1 or 2
A vacuum pump device comprising a plurality or positive displacement vacuum pumps arranged in a rear stage or a rear stage group.