JPS6291705A - Condensate recovery pump device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a condensate recovery pump device that combines an electric pump and a jet pump, which is used when recovering condensate (high temperature liquid) generated in steam-using equipment to a boiler. .

Since the condensate re-evaporates when it is led to a low-pressure area, cavitation occurs and the electric pump cannot pump the condensate under pressure, so it is necessary to apply pressure to the electric pump.

Therefore, we combined the electric pump with a jet pump with an ejector structure to guide the liquid coming out of the discharge port of the electric pump to the nozzle of the jet pump through the circulation passage, and to direct the liquid coming out of the diffuser of the jet pump to the suction port of the electric pump. The condensate is guided through an inlet passage to the suction of a jet pump, and the pressurized liquid is sent to a destination such as a boiler through a pressure passage branched from a circulation passage on the discharge port side.

However, in this case, when the amount of condensate flowing in from the inflow passage decreases, the force of the jet stream from the nozzle of the jet pump becomes weak, and the pressure at the suction port of the electric pump is insufficiently increased, resulting in cavitation.

Conventional Technology Therefore, the technology disclosed in Japanese Patent Publication No. 59-41039 has been used in the past. This guides the liquid coming out of the discharge port of the electric pump to the nozzle of the jet pump through the circulation passage, and also guides the liquid coming out of the diffuser of the diene 1 pump to the suction port of the electric pump, and jets the condensate through the inflow passage. The pressurized liquid is guided to the suction chamber of the pump and sent to the destination through a pressure passage branched from the circulation passage on the discharge port side, and a control valve is arranged in the pressure passage, so that the suction port of the electric pump is at a higher pressure than the inflow passage by a desired pressure. It is necessary to adjust the opening of the control valve so that the

When the inflow amount of condensate from the inflow passage decreases, the control valve reduces its opening degree. The pressure in the circulation passage on the discharge port side increases because the amount of liquid flowing out from the pressure passage decreases, and the force of the jet stream from the nozzle increases, increasing the pressure at the suction port of the electric pump. Conversely, when the inflow of condensate increases, the control valve increases its opening and lowers the pressure at the suction port of the electric pump.

In this way, the pressure difference between the suction port and the inflow passage of the electric pump always ensures the pushing pressure necessary for the electric pump, thereby eliminating problems such as dry running of the pump and cavitation.

Problems to be Solved by the Invention The above-mentioned structure operates on a constant electric pump lift-head characteristic curve depending on changes in the amount of condensate flowing into the inlet passage. In other words, even if the inflow amount of condensate from the inflow passage changes, the opening degree of the control valve is adjusted, and if the inflow rate decreases, the opening degree of the control valve is reduced and the flow rate from the discharge port side is adjusted. The pressure in the circulation passage is increased, the lift of the electric pump decreases, and the lift rises. Conversely, when the inflow increases, the lift of the electric pump increases and the head decreases.

Therefore, when the amount of condensate flowing into the inlet passage decreases, the electric pump is operated at a higher head than the head required to pump the condensate, which increases the power consumption of the electric pump.

The technical problem of the present invention is to prevent the electric pump from running dry, cavitation, or other inconveniences even if the pressure or inflow amount of condensate in the inlet passage changes, and to prevent the electric pump from operating at a head higher than necessary. It is to do so.

Means for Solving the Problems The technical means of the present invention taken to solve the above-mentioned technical problems is to guide the liquid discharged from the discharge port of the electric pump through the circulation passage to the nozzle of the jet pump. The liquid discharged from the diffuser of the pump is guided to the suction port of the electric pump, the condensate is guided to the suction chamber of the jet pump through the inflow passage, and the pressurized liquid is sent to the destination through the pressure passage branched from the circulation passage on the discharge outlet side. In a system in which a control valve is arranged in the pressure passage and the opening degree of the control valve is adjusted so that the suction port of the electric pump is maintained at a desired pressure higher than the inflow passage, the discharge port side circulation passage or control valve is A pressure detection means is attached to the pressure feeding passage on the inlet side of the pump, and the detected pressure value from the pressure detection means is compared with the specified discharge pressure value of the electric pump.If the detected pressure value is larger/smaller than the specified discharge pressure value. The system is equipped with a sequencer that controls the rotation of the electric pump by lowering/increasing the rotation speed of the electric pump via an inverter.

action The operation of the above technical means is as follows.

When the amount of condensate flowing in from the inflow passage decreases, the control valve is driven to decrease the opening degree, and the suction port of the electric pump is maintained at a pressure higher than that of the inflow passage by a desired pressure. At this time, the pressure in the circulation passage on the discharge port side increases because the amount of liquid flowing out from the pressure passage decreases. This pressure increase is detected by the pressure detection means, and the detected pressure value is input to the sequencer.

The sequencer compares this detected pressure value with the specified discharge pressure value, and if the detected pressure value is greater than the specified discharge pressure value,
Sends a signal to the inverter to lower the rotation speed of the electric pump.

Conversely, when the amount of inflow condensate increases, the control valve is driven to increase its opening, and the suction port of the electric pump is maintained at a desired pressure Cp higher than that of the inflow passage. At this time, the pressure in the circulation passage on the discharge port side decreases because the amount of liquid flowing out from the pressure passage increases. This pressure drop is detected by the pressure detection means, and the detected pressure value is input to the sequencer. The sequencer compares the detected pressure value with the specified discharge pressure value, and if the detected pressure value becomes smaller than the specified discharge pressure value, sends a signal to the inverter to increase the rotation speed of the electric pump.

Therefore, the control valve adjusts the opening degree according to changes in the amount of inflow condensate and maintains the suction port of the electric pump at a desired pressure higher than the inflow passage, preventing dry operation of the electric pump and cavitation. Moreover, since the rotation speed of the electric pump is controlled and the lift-head characteristic curve of the electric pump is changed according to the river of inflowing condensate, the electric pump is not operated at an unnecessarily high head. This reduces power consumption.

Effect of the invention The present invention produces the following unique effects.

The drive horn of the pump is proportional to the cube of the pump's rotational speed, and the head of the pump is proportional to the square of the rotational speed. Therefore, by controlling the rotational speed of the electric pump to reduce the head of the pump, the power consumption of the pump can be significantly reduced.

Embodiment An embodiment illustrating a specific example of the above technical means will be described (see FIGS. 1 and 2).

An electric pump 3 is configured by connecting an electric motor 2 to the pump 1. The pump 1 may be of a spiral type, cascade type, or other type depending on the purpose. The discharge port 4 of the pump 1 and the nozzle 6 of the jet pump 5 having an ejector structure are connected by a circulation passage 7 on the discharge port side, and a diffuser 8 of the jet pump 5 is connected.
and the suction port 9 of the pump 1 are connected by a suction port side circulation passage ]O. The circulation passages 7 and 10 are formed of pipe members. An inlet passage 12 that introduces condensate generated in steam-using equipment, etc. is connected to a suction line 11 around the nozzle 6 of the jet pump 5, and is branched from a circulation passage 7 on the discharge port side to send pressurized liquid to a boiler, etc. A pressure feeding passage 13 leading out first is provided.

A control valve 14 is arranged in the pressure feeding passage 13. The pressure at the suction port 9 and the pressure at the inflow passage 12 of the suction side circulation passage 10 are taken out through thin tubes 15 and 16, respectively, and guided to the differential pressure transmitter 17. The signal value of the differential pressure transmitter 17 is guided to the adjustment signal 18. Controller 18
compares the value received from the differential pressure transmitter 17 with the set value, and sends a valve operation signal to the operating section 19 of the control valve 14 in accordance with the differential pressure to drive the valve to open or close. The set value is a value that ensures sufficient pushing pressure when the pump 1 pumps condensate.

A pressure gauge 20 is installed in front of the control valve 14 in the pressure feeding passage 13. The pressure detected by the pressure gauge 20 is input to the sequencer 21. The sequencer 21 compares the detected pressure value with the specified discharge pressure value and outputs an operation signal to the inverter 22. The inverter 22 supplies the electric motor 2 with a voltage having a frequency corresponding to the operation signal, and controls the rotation speed of the electric motor 2.

The adjustment unit 18 outputs the received value from the differential pressure transmitter 17 to the sequencer 21. The sequencer 21 receives this received value, that is,
Pressure at the suction port 9 of the suction port side circulation passage 10 and the inflow passage 12
When the differential pressure becomes extremely small, the operation of the electric motor 2 is stopped.

Incidentally, reference numeral 23 denotes an air central valve that discharges air accumulated in the circulation passage 7.10 before starting the electric motor 2 in response to a signal from the sequencer 21.

Next, the operation of this embodiment will be explained.

When the electric motor 2 is started and the pump 1 is driven, the pressure of the condensate in the suction port 9 is increased by the pump 1 and is pushed out from the discharge port 4, passes through the discharge port side circulation passage 7, is injected from the nozzle 6, and is injected into the condensate water in the inflow passage 12. Water is drawn into suction 11 and passes through diffuser 8 to suction 9 . At this point, the pressure of the condensate in the suction port 9 is increased by the action of the ejector, and the control valve 14 remains closed in the same way until the differential pressure between the suction port 9 and the inflow passage 12 reaches the set value. Circulation passage 7゜10
cycle. When the pressure difference between the inflow passage 12 and the suction port 9 of the suction side circulation passage 10 reaches a predetermined set value, the control valve 14 opens and a portion of the pressurized condensate is transferred to the pressure feeding passage 1.
3 and is sent to a destination such as a boiler.

Here, when the inflow amount of condensate from the inflow passage 12 decreases, the amount of condensate supplied to the electric pump 3 decreases, the force of the jet stream from the jet pump 5 also weakens, and the suction port of the electric pump 3 decreases. 9 pressure decreases.

That is, the differential pressure between the inflow passage 12 and the suction port 9 of the electric pump 3 becomes smaller. Therefore, the differential pressure transmitter 1 that detected this
7, the opening degree of the control valve 14 becomes smaller. Then, the pressure in the circulation passage 7 on the discharge port side increases because the flow of condensate from the discharge passage 13 decreases, the force of the jet from the nozzle 6 increases, and the pressure at the suction port 9 of the electric pump 3 increases. Rise.

At this time, the pressure value detected by the pressure gauge 20 that detects the pressure in the discharge port side circulation passage 7 is input to the sequencer 21. The sequencer 21 compares the detected pressure value with the specified discharge pressure and outputs an operation signal to the inverter 22. The inverter 22 generates a voltage at a frequency corresponding to the operation signal! l! Supplies it to electric motor 2 and lowers the rotation speed of electric motor 2. On the contrary, when the condensate m increases, the control valve 14 increases the opening degree and increases the rotation speed of the electric motor 2.

FIG. 2 shows a head m-head characteristic diagram of the condensate recovery pump device. The vertical axis is the inlet side of the control valve 14, that is, the pump 1
The horizontal axis is the head Q at the pressure P on the discharge side. In addition, the dotted line is a lift-lift characteristic curve depending on the rotation speed of the electric motor 2, and Pl
is the specified discharge pressure value of the electric pump.

The condensate recovery pump device of the present invention compares the detected pressure value of the discharge port side circulation passage 7 detected by the pressure gauge 20 with the specified discharge pressure value by the sequencer 21,
Since the rotational speed of the electric motor 2 is controlled, the motor 2 is operated on a characteristic curve as shown by the thick solid line.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a condensate recovery pump device according to an embodiment of the present invention, and FIG. 2 is a rod-lift characteristic diagram of the condensate recovery pump device of the present invention. 1: Pump 2: Electric motor 4: Discharge port 5 Nijet pump 7: Discharge port side circulation passage 9: Suction port 10: Suction port side circulation passage 12 Second flow passage 13: Pressure feeding passage 14: Control valve 17: Differential pressure transmitter 1
8: Controller 20: Pressure gauge 21 Pressure gauge 22: Inverter

Claims (1)

[Claims] 1. Guide the liquid coming out of the discharge port of the electric pump to the nozzle of the jet pump through the circulation passage, guide the liquid coming out of the diffuser of the jet pump to the suction port of the electric pump, and draw the condensate through the inflow passage to the jet pump suction. The pressurized liquid is introduced into the chamber and sent to the destination through a pressure feeding passage branched from the circulation passage on the discharge port side, and a control valve is disposed in the pressure feeding passage.
When adjusting the opening degree of a control valve so that the suction port of an electric pump is maintained at a desired pressure higher than the inflow path, pressure is detected in the circulation path on the discharge port side or the pressure feeding path on the inlet side of the control valve. The detected pressure value from the pressure detection means is compared with the specified discharge pressure value of the electric pump, and when the detected pressure value is greater/lower than the specified discharge pressure value, the rotation speed of the electric pump is determined via the inverter. A condensate recovery pump device equipped with a sequencer that controls the rotation of an electric pump to lower/raise the water.