JPS6136443B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for degassing seal oil of a turbo compressor that compresses gas containing high molecular weight hydrocarbon components such as natural gas.

Generally, the seal oil of turbo compressors that handle natural gas etc. is partially exposed to the gas being handled.
High molecular weight components in natural gas dissolve into seal oil, lowering the viscosity of the oil and lowering the flash point temperature of the oil, which adversely affects the compressor.

Therefore, a device for degassing the high molecular weight components dissolved in the seal oil, that is, a degassing device is required. This degumming device is often implemented by blowing and bubbling an inert gas such as nitrogen into a seal oil tank containing high molecular weight components to degump the high molecular weight components in the oil. The reason why an inert gas is used is because the flash point temperature of the seal oil is low as mentioned above and because gas containing oxygen cannot be used to prevent oxidation of the oil. Furthermore, in the absence of an inert gas such as nitrogen, a method of reducing the pressure (vacuum) of the seal oil in a tank has been implemented, but this method has the disadvantage of being extremely expensive.

The present invention was developed out of the need to perform degumming in the absence of an inert gas at a low cost, to the same extent as inert gas bubbling, without using a separate vacuum pump, as described above. be. For example, it is desirable to reduce the number of equipment required for natural gas compressors installed on offshore platforms and to perform in-house processing.

FIG. 1 shows a conventional degumming device. Nitrogen gas is supplied through a pipe 2 from a nitrogen gas supply device having a nitrogen tank 5, and is bubbled within the degumming tank 1. Seal oil containing a high molecular weight gas component that has come into contact with the gas handled by the compressor is led from pipe 3 to degutting tank 1. In tank 1, the seal oil is heated by heater 6, and is heated by inert gas from pipe 2. It is bubbled and degutted. This oil returns to the seal oil system of the compressor from pipe 4, and
It is again supplied for compressor seals.

FIG. 2 shows an embodiment of the present invention, in which the degassing tank 1 is the same as that in FIG. While nitrogen gas was supplied to the piping 2 in FIG. 1, in the present invention the gas discharged from the compressor 7 is used for degassing. The outlet gas of a discharge cooler 10 provided on the discharge side of the compressor 7 is branched and introduced into a tank 14 via a pipe 13. The tank 14 is connected to the tank 17 by a relatively long nozzle 15, and the tank 17 is maintained at the atmospheric pressure level by a vent pipe 18. On the other hand, a pipe 16 opens at an appropriate position inside the nozzle 15, and the pipe 16 is connected to a mist separator 19 outside the nozzle 15. The condensed gas passes through a pipe 16 opening into the nozzle 15 from the tank 14, expands adiabatically, and the high molecular weight components are condensed into a mist. It is led to the pipe 2 via the valve 22 and used for bubbling.

Next, the operation of the present invention will be explained with reference to the drawings. The compressor 7 sucks natural gas containing high molecular weight components from the pipe 8, compresses it, discharges it to the discharge side pipe 9, and sends it to the discharge cooler 10. 11 is a cooling water pipe. The gas leaving the cooler 10 flows out from the pipe 12 to the pipe 23 and is used, but a part of the gas is sent to the pipe 13 branched from the pipe 12 and introduced into the tank 14. . Since the tank 17 is open to atmospheric pressure through the vent pipe 18, gas flows at a considerably high speed through the nostle 15 connecting both the tanks 14 and 17. At this time, since the gas expands rapidly, the gas expands adiabatically and its temperature drops. That is, tank 14
temperature T ₀ , temperature T ₂ inside the nozzle 15, and flow rate W ₂
Then, Cp (T ₀ - _{T 2} ) = AW ₂ ² /2g However, Cp: constant pressure specific heat of gas, A: heat equivalent of work, g: gravitational acceleration, and since T ₀ can be considered constant, the velocity The temperature T ₂ inside the nozzle 15 decreases according to W ₂ .

A tube 16 is built into the nozzle 15, and its opening is located close to the tank 14. Therefore, the gas temperature at the opening of the tube 16 is T ₀ and the pressure is quite high, based on the same principle as the full pressure port of a pitot tube. , a relatively slow flow rate can be achieved. The gas in the pipe 16 is cooled to a level of T ₂ by passing through the nozzle 15 and sent to the mist separator 19 . The high molecular weight components of the gas sent to the mist separator 19 reach a saturated state in gaseous form, and are collected as mist by the mist separator and discharged to the outlet 20.
is discharged from. Therefore, only the gas from which high molecular weight components have been removed is sent to the pipe 2 via the heater 21 and the valve 22 and used for bubbling the seal oil. The temperature necessary for bubbling in the pipe 2 is regulated by a heater 21, and the pressure is regulated by a valve 22.

As can be understood from the above explanation, conventionally, when degumming the seal oil of a turbo compressor by bubbling, it has been possible to simply heat the oil. However, when reusing seal oil that has been used in a compressor with gas containing high molecular weight components, the high molecular weight components cannot be removed simply by heating, and in the end, the inert gas used for degassing causes bubbling and heating. There are two methods: degassing by using a vacuum pump, and removing high molecular weight components by heating and reducing the pressure in the seal oil tank with a vacuum pump. The present invention does not employ any of these methods, but instead uses the compressed gas itself for bubbling to perform degumming. In order to do this, a part of the gas at the outlet of the cooler for discharged gas from the compressor is adiabatically expanded and cooled. However, since this is a degumming device that has a device that removes high molecular weight components contained in the gas by turning them into liquid, degumming can be performed without using an inert gas, and high molecular weight components can be removed by inexpensive means. It is something that can be degushed.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing an example of a conventional degumming device, and FIG. 2 is a side sectional view showing an embodiment of the degumming device for explaining the present invention. 1...Degassing, 5...Nitrogen cylinder, 6...
... Heating tube, 7 ... Compressor, 10 ... Cooler, 1
4, 17...Tank, 15...Nozzle, 16...
Pipe, 19...Mist separator.

Claims (1)

[Claims] 1 A device that degushes the seal oil of a turbo compressor by bubbling, which adiabatically expands and cools a part of the exhaust gas of a cooler placed on the discharge side of the compressor, and removes high molecular weight components contained in the gas. 1. A degassing device characterized by having a device for liquefying and removing high molecular weight components, and using the gas after removing high molecular weight components by the device for bubbling.