KR20000045101A - Centrifugal pump mounted with real gas case for conveying liquified gas of low temperature - Google Patents

Abstract

PURPOSE: A centrifugal pump mounted with a real gas case for conveying liquefied gas of a low temperature is provided to prevent permeation of moisture by continuous distribution of dry gas from inside to outside and reduce heat transfer toward a driving part since the dry gas forms a blocking film in the real gas case, thereby preventing frosting generated around a pumping part. CONSTITUTION: A centrifugal pump mounted with a real gas case for conveying liquefied gas of a low temperature including a pumping part for pumping liquefied gas of a low temperature and a driving part, includes a back plate(5), a bearing housing(3) and a real gas case(9) mounted between the back plate and the bearing housing, wherein the real gas case includes an induction film for separating a gas of a low temperature from a gas of room temperature, wherein dry real gas is distributed to a sealed space at a rear surface of the back plate and the real gas is first distributed around a driving shaft(4) along the real gas induction film to prevent freezing of a rotation shaft, a real gas of a high temperature is discharged outside to prevent freezing of the driving part, permeation of moisture from outside is prevented, and heat transfer from outside to the pumping part is prevented by the gas of low temperature inside the induction film.

Description

Centrifugal pump for low temperature liquefied gas transfer with seal gas case

The present invention relates to a centrifugal pump for transporting low temperature liquefied gas, and in particular, a seal gas case is installed to prevent moisture from entering into the pumping portion between the back plate and the drive shaft to freeze water in the mechanical seal of the pumping portion. The present invention relates to a low-temperature liquefied gas transfer centrifugal pump that prolongs the life of the pump and reduces maintenance costs.

Centrifugal pumps that deliver low temperature liquefied gas (eg, liquefied nitrogen at -196 ° C) often break mechanical seals, unlike general pumps operating at room temperature.

The mechanical seal, which is mounted inside the pumping part and prevents liquefied gas from leaking out of the pumping part, consists of a main body part and a ring seal.

The ring seal of the mechanical seal is in close contact with the impeller rotating at a high speed of about 5000 rpm or more on one side to prevent leakage of liquefied gas, and the ring seal of the mechanical seal is pressed against the main body of the mechanical seal on the other side. At this time, the part that is in close contact with the main body is replaced with a cycle of about 1 year when it is operated normally with graphite or Teflon-based synthetic resin.

However, when impurities are present in the pumping part, the impurities seriously damage the surface of the mechanical seal, thereby making it impossible to repair them. Particularly, in the case of water, it can be easily penetrated by diffusion into the pumping part, and once frozen, it freezes quickly, which is a major cause of damaging the mechanical seal and the parts inside the pumping part.

Therefore, in the pump for transporting low temperature liquefied gas, preventing water from penetrating into the pumping part is a big variable that determines the life and performance of the pump.

In order to prevent moisture penetration, the back plate is drilled and a small amount of dry gas is blown around the mechanical seal, and dry gas is continuously sprayed around the back plate and the drive shaft during operation and while the drive shaft rotates. The method of preventing the invasion of moisture through is commonly used.

In the former case, nitrogen gas or dry air is used, and gas can be continually blown because the gas is liquefied due to the temperature drop in the connecting pipe during the long-term operation at the ultra low temperature. Therefore, moisture penetrates between the drive shaft and the back plate. Done.

In the latter case, nitrogen gas or dry air is continuously sprayed between the back plate and the drive shaft to prevent the access of water, which is difficult to prevent intrusion by partial pressure or diffusion of water, and a large amount of gas must be used. Low economic feasibility In addition, during operation, moisture on the surface of the pumping portion condenses and extends to the entire pump.

An object of the present invention is to install a seal gas case for preventing the ingress of moisture into the pumping portion through the back plate and the drive shaft to solve the above problems by preventing the water freezing in the mechanical seal of the pumping portion It is to provide a low-temperature liquefied gas transfer centrifugal pump equipped with a real gas casing that extends the service life and reduces maintenance costs.

The centrifugal pump of the present invention is composed of a pumping unit and a driving unit for pumping low temperature liquefied gas, and is equipped with a real gas case between the back plate and the bearing housing, and the real gas case has an induction membrane separating the low temperature gas from the gas at room temperature. Have

The present invention is equipped with a real gas casing on the back plate back to spray dry real gas in a closed space on the back of the back plate, primarily spray the real gas around the drive shaft along the real gas induction film to prevent freezing of the rotating shaft In order to prevent the freezing of the driving part and prevent the penetration of moisture from the outside, the relatively low temperature gas exists inside the induction membrane to reduce heat transfer from the outside to the pumping part. It provides a method to increase the efficiency of the pump.

1 is a cross-sectional view showing the configuration of a low-temperature liquefied gas transfer centrifugal pump equipped with a real gas case of the present invention.

Fig. 2 is a side sectional view showing the actual gas case of the present invention.

Figure 3 is a front view of the seal gas case of the present invention

4 is a rear view of the seal gas case of the present invention;

<Description of Symbols in Drawings>

1: impeller 2: casing 3: bearing housing

4: drive shaft 5: backplate 6: mechanical seal

7: Teflon seal 8: Insulation material 9: Seal gas case

10: gearbox 11: motor housing 12: ring seal

13: Real gas line 21: Real gas induction film 22: Real gas connector

The present invention will be described in detail with reference to the accompanying drawings.

Fig. 1 is a cross-sectional view showing the configuration of a low temperature liquefied gas transfer centrifugal pump equipped with a real gas casing of the present invention, wherein 1 is an impeller, 2 is a casing, 3 is a bearing housing, 4 is a drive shaft, and 5 is a back plate, 6 is a mechanical seal, 7 is a Teflon seal, 8 is a heat insulator, 10 is a gearbox, 11 is a motor housing, and 12 is a ring seal.

The mechanical seal 6 in the low temperature liquefied gas centrifugal pump is one of the most important parts. If an abnormality occurs in the mechanical seal, the liquefied gas leaks through the hole of the rotating shaft, and in more severe cases, the parts may be severely damaged by contact between the components inside the pumping part A rotating at high speed.

In addition, mechanical seals are very expensive to repair or replace if damaged with high value-added components. Therefore, in order to keep the centrifugal pumps running smoothly and at low cost, the mechanical seals should be kept in good condition at all times.

The centrifugal cryogenic liquefied gas pump of the present invention is equipped with a separate seal gas case 9 on the back plate back surface to prevent moisture from entering between the back plate 5 and the drive shaft 4.

2 shows a real gas case of the present invention as a side cross-sectional view, FIG. 3 shows a front view, and FIG. 4 shows a rear view, where the real gas case 9 is a real gas connector 22 and a real gas induction. The film 21 is comprised. The real gas induction film 21 has a function of separating low-temperature gas from normal-temperature gas.

Referring to FIG. 1, external nitrogen gas or dry air is connected to a real gas connector 22 through a real gas line 13 to supply real gas.

The real gas fills the inside of the real gas case 9 and the surplus gas exits along the driving shaft 4. The gas in the space contacting the back plate 5 inside the case has a very low temperature due to heat exchange with the pump. While present in the state, the gas in the outer space is relatively high in temperature so that the temperature of the real gas exiting through the hole of the back plate 5 is much higher than the gas temperature in the conventional pump.

Therefore, the cooling amount transmitted to the driving unit B side is reduced to prevent damages caused by the cooling of the parts including the O-ring of the driving unit, and the efficiency of the pump is reduced because the amount of heat transferred from the back plate 5 back to the inside of the pumping unit is reduced. Will be higher.

Since the gap between the hole through which the drive shaft 4 passes in the real gas case 9 and the drive shaft is very small, there is no possibility of moisture invading from the outside even when a small amount of the real gas escapes to the outside. Therefore, the present invention uses less actual gas, completely prevents water ingress, and improves the pumping efficiency of the pump.

The actual gas case 9 of the present invention is characterized in that it can be installed without changing the shape of the centrifugal pump currently in use or a special tool. In general, the vaccum insulation 8 is used to reduce the heat conduction from the driving part between the bearing housing 3 and the back plate 5 during assembly of the pump. It is easy to install and detach when assembling and disassembling because it is inserted first.

The present invention is equipped with a real gas case (9) on the back of the back plate (5) by spraying the dry real gas in the space sealed on the back of the back plate, the real gas around the drive shaft (4) along the real gas induction film primarily To prevent freezing of the rotating shaft, and to prevent the freezing of the driving unit by allowing the real gas of relatively high temperature to go out, to prevent the penetration of water from the outside, and relatively low temperature gas inside the induction membrane It provides a method for increasing the efficiency of the pump by reducing heat transfer from the outside to the pumping unit.

The centrifugal pump of the present invention configured as described above is equipped with a real gas casing, so that dry gas is continuously injected from the inside to the outside through a hole through which moisture may penetrate, so that the possibility of water infiltration is rare.

In addition, the dry gas in the real gas case behind the back plate forms a blocking film, thereby reducing the transfer of cool air to the driving unit side and reducing the frost phenomenon occurring around the pumping unit.

Therefore, when the anti-freezing seal gas case of the present invention is mounted on the centrifugal pump for liquefied gas, the number of repairs of the mechanical seals, which are frequently frequent as in the present invention, can be greatly reduced, and the love around the pumping part can be reduced.

Claims (3)

In the centrifugal pump consisting of a pumping unit and a driving unit for pumping low temperature liquefied gas, A low-temperature liquefied gas transfer centrifugal pump having a seal gas case 9 mounted between the back plate 5 and the bearing housing 3. The method of claim 1, The real gas case (9) is a low-temperature liquefied gas transfer centrifugal pump having an induction membrane (21) for separating the low-temperature gas and the gas at room temperature. The real gas case 9 is mounted on the rear of the back plate 5 to inject dry real gas into a space enclosed at the rear of the back plate, and primarily sprays real gas around the drive shaft 4 along the real gas induction film. It prevents freezing of the rotating shaft, prevents freezing of the driving part by letting out the relatively high temperature real gas to the outside, and prevents penetration of moisture from the outside, and relatively low temperature gas exists inside the induction membrane. To increase the efficiency of the pump by reducing heat transfer from outside.