JPH0748000B2 - Rotary fluid transport machine shaft seal leakage detection device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pump for fluid transportation,
The present invention relates to a device for detecting leakage of fluid from a shaft seal portion of a rotary fluid transport machine such as a blower for gas transport and a compressor.

[0002]

2. Description of the Related Art In pumps, blowers, compressors, etc., which are rotary, so-called rotary fluid transporters, rotor blades that directly contact fluid to move fluid, casing for housing rotor blades, torque A drive device that generates a torque and a structure that includes a rotating shaft that transmits a rotating force to a rotating blade are often used.

In this structure, a drive device is often placed outside the vehicle compartment, and a shaft seal device for preventing fluid from leaking from the vehicle compartment is attached to a portion where the rotary shaft projects from the vehicle compartment. ing. For example, the gland seal is the most general-purpose shaft seal device, and is a high-performance mechanical seal with little leakage and other types.

In addition to the above examples, there are many types and structures of these shaft sealing devices based on various ideas for minimizing fluid leakage. The rotary type structure as described above is used. It is difficult for a fluid transporter to completely prevent a fluid from leaking, and it is currently the case that a minute leak is allowed and used. There is also a rotary fluid transporter that has a structure in which the rotor and the drive are housed in the same chamber and does not use a shaft sealing device, but it is expensive and it is difficult to manufacture a large-capacity one. Not not.

On the other hand, since the shaft sealing device of these rotary fluid transport machines deteriorates with time, leakage of fluid increases after a certain period of operation. Moreover, the leakage may suddenly increase due to an unexpected failure. For this reason, in chemical plants, etc. that operate a large number of rotary fluid transporters that have these shaft sealing devices for handling highly dangerous substances, monitoring the leakage of dangerous substances from these shaft sealing parts is necessary for operation management. It is an important task for the personnel, and much time is spent on these monitoring tasks.

[0006]

There is a method of installing a gas sensor around the shaft sealing device as a means for assisting the leakage monitoring work from the shaft sealing portion of the rotary fluid transporting machine as described above. In a rotary fluid transport machine, in which the circumference of the shaft sealing device is open to the outside atmosphere, simply installing them will be affected by the weather such as wind, so normal minute leakage will occur. It was difficult to determine the leakage to the extent that treatment is required.

A method of installing a cover for avoiding the influence of wind may be considered for the rotary fluid transporter having such a structure. However, in this case and also in the rotary fluid transport machine having a structure in which the opening to the outside atmosphere around the rotary shaft and the shaft seal device is small, the air flow around the gas sensor is not constant and the gas concentration is uniform. Therefore, it is possible to grasp the qualitative magnitude of the leak scale, but it is difficult to quantitatively know the leak scale, and it is difficult to distinguish between a normal minute leak and a leak that requires treatment.

An object of the present invention is to provide a leak detecting device for a shaft seal portion of a rotary fluid transport machine, which can quantitatively know the magnitude of gas leak.

[0009]

A leak detection device for a shaft seal portion of a rotary fluid transporter according to the present invention is arranged between a vehicle compartment and a drive unit, and gas or liquid leaked from the vehicle compartment is vaporized. Between the gas sensor and the gas sensor that detects the generated gas and outputs an analysis value signal that indicates its concentration,
Attached to the rotating shaft part, the air suction blades that forcibly direct the atmosphere around the passenger compartment toward the drive unit as the rotating shaft rotates, the analysis value signal from the gas sensor, and the rotating shaft And a processing unit for inputting a signal indicating the number of revolutions and calculating the amount of gas leakage.

[0010]

Since the atmosphere around the passenger compartment is forcibly sent to the gas sensor, the gas leakage amount (= ventilation amount × gas concentration) can be measured with high accuracy from the ventilation amount and gas concentration.

When the rotary shaft and the shaft seal device are open to the atmosphere, the rotary shaft and the air suction blade are surrounded, and the atmosphere is introduced and discharged between the vehicle compartment and the drive device, respectively. The effect of wind is reduced by installing a cylindrical windshield with a gap for

[0012]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a block diagram of a rotary fluid transporter equipped with a leak detection device according to an embodiment of the present invention.

The rotary fluid transport machine shown in FIG. 1 is a liquefied ethylene pump, the pump type is a vertical centrifugal type, the capacity is 360 cubic meters per hour, the rotation speed is 1800 per minute, and it is in direct contact with liquefied ethylene. The rotating blade 8 for moving the same, the vehicle compartment 9 that houses the rotating blade 8, the drive device 6 that is placed outside the vehicle interior 9 and generates a rotational force, and the rotational force generated by the drive device 6 The rotary shaft 7 that is transmitted to the
And a mechanical seal 10 which is attached to the protruding portion and prevents liquefied ethylene from leaking from the passenger compartment 9.

A gas sensor 2 is provided near the drive device 6 to detect a gas in which liquefied ethylene that has leaked from the passenger compartment 9 is vaporized and output an analysis value signal indicating its concentration. The gas sensor 2 is of a semiconductor type and has a detection sensitivity of 5 to 10 ppm with respect to ethylene gas. Also, the rotating shaft 7
In the portion between the drive device 6 and the vehicle interior 9, the air suction blades 1 for forcibly directing the atmosphere around the vehicle interior 9 toward the drive device 6 with the rotation of the rotating shaft 7 are attached. Has been.
This air intake blade 1 has a diameter of 12 cm, and the intake amount of air is 60 cubic meters per hour when the rotation speed of the rotating shaft 7 is 1800 per minute, and the relationship between the intake amount of air and the rotation speed of the rotating shaft 7 is It is designed to be volume (cubic meter per hour) = (1/30) x rotation speed (per minute). Further, a tubular windshield 4 is provided so as to surround the rotary shaft 7, the air suction blades 1 and the gas sensor 2 with a gap maintained between the vehicle compartment 9 and the drive device 6. The arithmetic processing unit 3 inputs the analysis value signal from the gas sensor 2 and the signal from the drive unit 6 indicating the number of rotations of the rotating shaft 7 via the signal line 5, and the gas leakage amount =
Calculate the ventilation volume x gas concentration. Here, the gas sensor 2
The air suction blade 1, the windshield 4, and the arithmetic processing device 3 constitute a leak detection device.

As a result of actually operating the rotary fluid transporter equipped with the above-mentioned leak detection device and actually measuring the leak amount of ethylene gas, the output from the arithmetic processing unit 3 is the intake air amount: hourly. 60 cubic meters, ethylene gas concentration: 4
At 0 ppm, the amount of ethylene gas leaked was 2.4 liters per hour.

Next, while operating the fluid transport machine, the ethylene gas was blown into the connecting portion of the mechanical seal 10 and the rotary shaft 7 at a flow rate of 10 liters per hour through a pipe having a diameter of 4 mm, and the result was calculated. The output from the processing device 3 is an intake air amount: 60 cubic meters per hour, an ethylene gas concentration: 210 ppm, and an ethylene gas leakage amount: 1 per hour.
It was 2.6 liters.

Further, FIG. 2 shows the result of measurement by changing the flow rate of ethylene gas. It can be seen that the ethylene gas injection amount and the detected ethylene gas concentration are in a proportional relationship. Here, a comparative example is shown below. Comparative Example 1 The measurement was performed in the same manner as in the example except that the air suction blade 1 and the windshield 4 were not attached. When ethylene gas was not blown in, the detected concentration of the gas sensor 2 showed almost 0, and although there were occasional instructions, it did not show a stable value.

Next, ethylene gas was blown in at a flow rate of 10 liters per hour as in the case of the example, but the detected concentration of the gas sensor 2 showed almost 0, and although there were occasional instructions, it did not show a stable value. Comparative Example 2 The measurement was performed in the same manner as in Example except that the air suction blade 1 was not attached. When not blowing ethylene gas,
The detection concentration of the gas sensor 2 was 200 to 400 ppm.

Next, FIG. 3 shows the results of measurement by blowing ethylene gas at different flow rates as in the example. It can be seen that the detected ethylene gas concentration fluctuates.

[0021]

As described above, according to the present invention, the atmosphere around the passenger compartment is forcibly forced toward the drive unit by the rotation of the rotating shaft between the passenger compartment and the gas sensor. By installing an air suction vane that can be turned over, the amount of gas leakage can be measured with high accuracy, and remote centralized monitoring of leakage from the shaft seal part of a rotary fluid transport machine in a chemical factory that handles highly hazardous substances. It is possible to contribute to human labor saving in these factories and facilities.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a rotary fluid transporter including a leak detection device according to an embodiment of the present invention.

FIG. 2 is a graph showing a gas leak measurement result in the embodiment of FIG.

FIG. 3 is a graph showing gas leak measurement results in a comparative example with respect to the example of FIG.

[Explanation of symbols]

 1 Air Suction Blade 2 Gas Sensor 3 Processing Device 4 Windshield 5 Signal Line 6 Drive Device 7 Rotating Shaft 8 Rotor Blade 9 Cabin 10 Mechanical Seal

Claims (2)

[Claims] 1. A rotary vane for moving the fluid in direct contact with the fluid, a casing for accommodating the rotary vane, a drive device disposed outside the casing for generating a rotational force, and the drive device. A rotary fluid transport having a rotary shaft for transmitting the generated rotary force to the rotary vanes, and a shaft sealing device which is attached to a portion where the rotary shaft projects from the casing and prevents the fluid from leaking from the casing. A device for detecting leakage of fluid from a shaft sealing part in a machine, the device being arranged between the vehicle compartment and the drive device, for detecting gas leaking from the vehicle compartment or gas vaporized from the leaking liquid. , A gas sensor that outputs an analysis value signal indicating the concentration, and is attached to a portion of the rotating shaft between the vehicle compartment and the gas sensor, and is attached to the periphery of the vehicle compartment as the rotating shaft rotates. Force the atmosphere towards the drive A rotary fluid transporter shaft seal having an air suction vane, an analysis value signal from the gas sensor, and an arithmetic processing unit for inputting a signal indicating the rotation speed of the rotation shaft to calculate the amount of gas leakage. Part leak detection device. 2. When the rotary shaft and the shaft sealing device have a structure that is open to the atmosphere, the rotary shaft and the air suction blade are surrounded, and between the vehicle compartment and the drive device. The device according to claim 1, wherein the device has cylindrical windshields each having a gap for introducing and exhausting air.