JPH09137799A - Ejector vacuum pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a cavitation phenomenon in a centrifugal pump. SOLUTION: An ejector 1, a tank 2 and a centrifugal pump 3 are sequentially connected to each other. A condensed water suction passage 30 is connected to a suction chamber 5 of the ejector 1. A pressure sensor 7, a noncondensable gas supply pipe 9 and a discharge pipe 13 are connected to an upper part of the tank 2. A temperature sensor 15 is installed on a lower part of the tank 2 and connected to a controller 16. The controller 16 is connected to automatic valves 8, 10, 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ejector vacuum pump in which an ejector and pump means are combined. The ejector vacuum pump circulates a fluid in the ejector by a pump means to generate a suction force in the ejector portion, and has been conventionally used as a condensate suction / discharge device from a steam heating device or a low-pressure steam using device.

[0002]

2. Description of the Related Art A conventional ejector vacuum pump is disclosed in, for example, Japanese Patent Laid-Open No. 7-253100. This is achieved by combining an ejector, a tank, and a centrifugal pump, connecting a pressure control valve to the suction passage for condensate, and making the suction force of the ejector lower by a predetermined value than the saturation pressure of the suction fluid by this pressure control valve. The cavitation phenomenon at the ejector section is prevented.

[0003]

SUMMARY OF THE INVENTION In the above prior art,
Cavitation can be prevented in the ejector section, but there is a problem that the cavitation phenomenon still occurs in the centrifugal pump section. When the temperature of the suction fluid from the tank to the centrifugal pump becomes high, the pushing pressure required for the centrifugal pump is insufficient and cavitation occurs. The cavitation phenomenon is a phenomenon in which bubbles are generated in a high temperature fluid in a pump and the bubbles are further collapsed, resulting in remarkable noise and vibration. The noise and vibration not only become noise to the surroundings, but also cause vibration and damage to the equipment, which causes deterioration and damage.

Therefore, a technical object of the present invention is to obtain an ejector vacuum pump which does not cause a cavitation phenomenon in a liquid pressure pump.

[0005]

The technical means of the present invention taken to solve the above-mentioned technical problem is to form a suction chamber around the nozzle portion of an ejector, and to provide a liquid pressure pump means for the nozzle portion. In the case of being connected to a tank via a non-condensable gas supply pipe for supplying a non-condensable gas into the tank via a valve means, a pressure detection means for detecting the pressure in the tank is provided, and a liquid pressure pump means. A temperature detecting means for detecting the temperature of the fluid flowing downward is attached, and the valve means is controlled so that the tank internal pressure becomes higher by a predetermined value than the saturation pressure of the fluid with respect to the temperature value detected by the temperature detecting means. A control unit is provided.

[0006]

The operation of the above technical means is as follows. By increasing the pressure in the tank by a predetermined value by the noncondensable gas above the saturation pressure corresponding to the temperature value of the fluid flowing down to the liquid pressure pumping means, the pushing pressure to the liquid pressure pumping means is secured, and the high temperature fluid in the pump No bubbles are generated even when sucked into the chamber, and therefore, no cavitation phenomenon occurs.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment showing a specific example of the above technical means will be described. In FIG. 1, an ejector 1, a tank 2, and a spiral pump 3 as a liquid pressure pump means constitute an ejector vacuum pump. The suction chamber 5 of the ejector 1 is connected to a condensate suction passage 30 from a low-pressure steam using device (not shown).

The ejector 1 is constructed by connecting a suction chamber 5 having a nozzle (not shown) inside and a diffuser 6, and the outlet side of the diffuser 6 is connected to the tank 2. Tank 2
A pressure sensor 7 as a pressure detecting means for detecting the pressure in the tank 2, a non-condensable gas supply pipe 9 via an automatic valve 8 as a valve means, and a cooling fluid likewise via an automatic valve 10 above A supply pipe 11 and a non-condensable gas discharge pipe 13 via an automatic valve 12 are attached. Compressed air, nitrogen gas, or the like can be used as the non-condensable gas.

A temperature sensor 15 as a temperature detecting means for detecting the liquid temperature of the fluid in the tank 2 is attached to the lower portion of the tank 2 and is connected to the controller 16. Controller 1
6 is the actuator of each automatic valve 8, 10, 12
And the pressure sensor 7. Controller 16
The actuator of the automatic valve 8 constitutes the control unit of this embodiment.

In this embodiment, the non-condensable gas exhaust pipe 1
Although the example in which 3 is provided is shown, this is not always necessary. For example, when the inside of the tank 2 is maintained at a predetermined pressure by exhausting the minute gas from the minute orifice while supplying a constant amount of non-condensable gas, It becomes unnecessary.

The suction port 17 of the centrifugal pump 3 is connected to the lower part of the tank 2, and the discharge port 18 is connected to the ejector 1 via a circulation path 19. Automatic valve 2 by branching a part of circulation path 19
0 is set as an excess fluid discharge part in the tank 2. The ejector vacuum pump of the present embodiment is a pump that circulates the liquid in the tank 2 into the ejector 1 by the spiral pump 3 to generate suction force in the suction chamber 5 and suck low-pressure condensate from the condensate suction passage 30. . In this case, the vacuum suction force generated in the suction chamber 5 is
The saturation pressure becomes almost equal to the temperature of the liquid passing through the ejector 1. Therefore, the vacuum suction force in the suction chamber 5 can be adjusted by adjusting the liquid temperature in the tank 2 according to the amount of cooling fluid supplied from the cooling fluid supply pipe 11.

Next, the operation will be described. The controller 16 controls the opening and closing of the automatic valves 8 and 12 so that the pressure in the tank 2 becomes higher than the saturation pressure for the fluid temperature in the tank 2 detected by the temperature sensor 15 by a predetermined value. The pressure in the tank 2 is fed back to the controller 16 by the pressure sensor 7. The pressure in the tank 2 is maintained higher than the saturation pressure with respect to the temperature of the fluid in the tank 2 sucked by the centrifugal pump 3 by a predetermined value, so that a necessary pushing pressure is constantly applied to the centrifugal pump 3. Even if the high-temperature fluid is sucked by the spiral pump 3, no air bubbles are generated inside it, and a cavitation phenomenon does not occur.

When the temperature of the condensate flowing down from the condensate suction passage 30 changes from 100 ° C. or below to above, that is, the saturation pressure of the fluid is equal to or higher than the vacuum pressure below atmospheric pressure and equal to atmospheric pressure. When changing to a positive pressure state, tank 2
When the pressure inside is atmospheric, a cavitation occurs when a fluid of 100 ° C. or more flows into the spiral pump 3, but as in this embodiment, the pressure inside the tank 2 is higher than the saturation pressure of the fluid. By constantly raising it by a predetermined value,
Cavitation can be prevented.

When the temperature of the fluid is 100 ° C. or less and the saturation pressure does not exceed the vacuum pressure, the automatic valve 12 is opened and the pressure in the tank 2 is set to the atmospheric pressure state. Is constantly above saturation pressure and does not cause cavitation.

[0015]

As described above, according to the present invention, the non-condensable gas is supplied into the tank to secure the pushing pressure of the liquid pressure pump, thereby preventing the cavitation phenomenon in the liquid pressure pump section. As a result, it is possible to obtain an ejector vacuum pump that does not generate significant noise or vibration.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of an ejector vacuum pump of the present invention.

[Explanation of symbols]

 1 Ejector 2 Tank 3 Swirl Pump 5 Suction Chamber 7 Pressure Sensor 8 Automatic Valve 9 Noncondensable Gas Supply Pipe 11 Cooling Fluid Supply Pipe 13 Noncondensable Gas Discharge Pipe 15 Temperature Sensor 16 Controller 30 Condensate Suction Passage

Claims (1)

[Claims] 1. A non-condensable gas supply pipe for supplying non-condensable gas into a tank, wherein a suction chamber is formed around a nozzle part of an ejector, and the nozzle part is connected to a tank through a liquid pressure pump means. The temperature detected by the temperature detecting means is provided through the valve means, the pressure detecting means for detecting the pressure in the tank is provided, and the temperature detecting means for detecting the temperature of the fluid flowing down to the liquid pressure pumping means is attached. An ejector vacuum pump comprising a control unit for controlling the valve means so that the tank internal pressure becomes higher by a predetermined value than the fluid saturation pressure with respect to the value.