JPH08576Y2 - Condensate recovery device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a condensate recovery device for pumping condensate generated in a steam-using device such as a heat exchanger to a high-pressure location such as a boiler.

<Prior Art> Therefore, conventionally, a condensate water recovery device as shown in FIG. 2 has been proposed by the present applicant and widely used in industry. This device will be described with reference to the drawings. The discharge port 6 and the suction port 4 of the electric pump 2 are connected by a circulation passage 8, and an ejector unit 10 for generating a jet flow is provided between the circulation passage 8 and the suction port 4. Inflow passage 14 that opens to the ejector unit 10
Is connected to a condensate recovery pipe 16 and a branched discharge passage 12 is provided in the middle of the circulation passage 8. A full water detector 18 for detecting the presence or absence of condensed water in the circulation passage 8 is arranged, and a pressure switch 20 is arranged in the discharge passage 12. Condensate returning from the condensate recovery pipe 16 is pressurized by the electric pump 2 through the inflow passage 14 and the ejector unit 10, and is pressure-fed to the high-pressure portion (boiler) through the discharge passage 12.

The pressure switch 20 is for ensuring the capacity of the ejector unit 10. In other words, if the discharge pressure of the electric pump falls below the set pressure of the pressure switch due to a decrease in the amount of condensate collected, the pressure switch 20 operates and stops the electric pump. It is the one to be confused. Therefore, the set pressure of the pressure switch is set high. Further, even when the amount of condensed water is small from the beginning and the discharge pressure does not reach the set pressure of the pressure switch within a predetermined time even if the pump is started, the pump is controlled to stop. The electric pump is started by the full water detector detecting that the circulation passage 8 is filled with condensed water. Reference number 2
Numerals 2 and 24 are pressure regulating valves, which open when the primary pressure of the valve becomes equal to or higher than a predetermined set pressure and allow the fluid to flow to the secondary side. 26 is a control device for operating the condensate recovery device.

<Problems to be solved by the invention> As described above, the pressure switch provided in the discharge passage 12
When the pressure of the condensate recovery pipe 16 is high, the set pressure of 20 may be set to a considerably high value by adding the discharge pressure of the electric pump 2 to the pressure. In this case, when condensate exists in the initial stage of operation but the pressure has not reached the predetermined high pressure, the full water detector detects that the circulation passage 8 is filled with condensate, and the electric pump is started. The discharge pressure does not reach the set pressure of the pressure switch, and as a result the pump stops. Even if the pump is stopped, the circulation passage is restarted because it is filled with low-pressure condensate. If the pressure in the recovery pipe is not increased even after starting, the pump will stop again. Every time this is repeated, the magnet for driving the motor of the pump operates and leads to damage. If the set pressure of the pressure switch is lowered, this problem will be solved, but this will reduce condensate during normal operation and reduce the discharge pressure of the pump,
The problem remains that the pump does not stop easily even if the ejector's ability deteriorates.

Therefore, the technical problem of the present invention is to prevent the electric pump from repeatedly starting and stopping even when the set pressure of the pressure switch is increased in order to guarantee the capacity of the ejector.

<Means for Solving the Problem> The technical means of the present invention taken to solve the above problem is to connect an electric pump and a discharge port and a suction port of the electric pump to create a condensate jet flow inside. Detects the presence of condensate inside the circulation passage, the inflow passage that opens to the jet flow section of the circulation passage, the condensate recovery pipe that communicates with the inflow passage, the discharge passage that opens in the middle of the circulation passage, and the condensate inside the circulation passage. Equipped with a full water detector and a pressure switch arranged in the discharge passage, and when the amount of condensed water collected decreases and the discharge pressure of the electric pump falls below the set pressure of the pressure switch, it operates to stop the electric pump. If the discharge pressure does not reach the set pressure of the pressure switch within a predetermined time even if the amount of condensate is small and the pump starts up from the beginning, the pump is controlled to stop. Hand detecting pressure A step is provided so that the electric pump starts when the pressure in the condensate recovery pipe reaches a predetermined pressure or higher and the circulation passage is filled with condensate.

<Operation> Since the pressure in the recovery pipe reaches a predetermined sufficiently high pressure when the electric pump is started, the discharge pressure can exceed the set pressure of the pressure switch, and the pump can continue to operate. Then, when the amount of condensed water decreases and the discharge pressure becomes lower than the set pressure, the pump operates so as to stop.

<Example> An example showing a specific example of the above technical means will be described with reference to FIG. The schematic flow is the same as that in FIG.

A discharge port 6 of the electric pump 2 and a suction port 4 are connected by a circulation passage 8, and an ejector section 10 for generating a jet flow is provided between the circulation passage 8 and the suction port 4. The condensate in the circulation passage 8 circulates due to the operation of the electric pump 2, and a high-speed flow is created in the ejector section 10 to give velocity energy to the condensate that flows in, and then the diffuser section 36 increases the pressure to an overpressure state to condense the condensate. Prevent cavitation in the pump even with high temperature water.

The inflow passage 14 opening to the ejector unit 10 communicates with the condensate water recovery pipe 16 via the header 30, and the pressure detector 32 is arranged in the header 30 to detect the pressure in the recovery pipe. Header 30
A pressure regulating valve 24 is provided by communicating a pipe 34 from the upper part of the. The pressure regulating valve has a piston inside, the primary side fluid acts on the lower surface, the elastic force of an elastic body such as a coil spring acts on the upper side, and the primary side fluid pressure becomes higher than the set elastic force. In this case, the main valve is opened to allow the fluid to flow to the secondary side and maintain the pressure on the primary side at the set pressure.

A branched discharge passage 12 is provided in the middle of the circulation passage 8, a pressure adjusting valve 22 is arranged, and a pressure switch 20 is provided to detect the pressure in the discharge passage 12. A part of the condensed water pressurized by the electric pump 2 flows into the circulation passage 8 and the other flows into the discharge passage 12. Then, when the pressure is higher than the set pressure of the adjusting valve 22, the fluid is discharged from the adjusting valve 22 to the high pressure portion.

The pressure switch 20 is for securing the capacity of the ejector unit 10, that is, when the condensate recovery amount decreases and the discharge pressure of the electric pump decreases and becomes lower than the set pressure of the pressure switch, the pressure switch 20 is activated to drive the electric motor. It stops the pump. Further, even when the amount of condensed water is small from the beginning and the discharge pressure does not reach the set pressure of the pressure switch within a predetermined time even if the pump is started, the pump is controlled to stop. Therefore, the set pressure of the pressure switch is set slightly lower than the set pressure of the pressure control valve 22. That is, as will be described later, when the condensate recovery pressure is high and the set pressure of the pressure regulating valve 24 is high, the pressure is set high.

The circulation passage 8 is provided with a full water detector 18 for detecting the presence or absence of condensate therein, and a pipe for discharging initial air and a motor-operated valve 28 are provided. Reference numeral 26 is a control device for operating the condensate recovery device. When the electric pump is started, the full water detector detects that the circulation passage 8 is filled with condensate, and the pressure detector 32 detects the inside of the recovery pipe. When the pressure reaches a predetermined pressure, it is performed. Here, the predetermined pressure is almost the same value as the set pressure of the pressure switch 20, and is set high when the condensate recovery pressure is high and the set pressure of the pressure regulating valve 24 is high.

The operation and control are performed as follows. In order to collect the condensate discharged from the steam trap (not shown) at a pressure as high as possible rather than opening it to the atmosphere, the pressure regulating valve 24 is set to a value slightly lower than the primary pressure of the steam trap. Therefore, if the primary pressure of the trap is high, the higher the pressure is, the higher the condensate can be collected. Condensate returning from the condensate recovery pipe 16 is separated into re-evaporated steam and condensate by the header 30, the re-evaporated steam is sent to the destination through the adjusting valve 24, and the condensate is passed through the inflow passage 14 to the ejector unit 10 Flow into.

As the condensate flows into the pump and the circulation passage 8, the gas inside is discharged from the motor-operated valve 28 to the outside through the full-water detector 18, and when the full-water detector detects the full-water, the motor-operated valve 28 is closed.

At this time, since the pressure in the condensate recovery pipe 16 has not increased at the start-up of the operation, the pump has not started yet. After that, when the pressure in the condensate recovery pipe 16 rises and reaches the set pressure, the condition of the signal of the full water detector 18 is satisfied at this time, the electric pump 2 is activated, and the condensate is discharged at a high pressure point. To discharge. Since the pressure in the recovery pipe is high, the set pressure of the pressure switch can be easily exceeded, and the pump can continue to operate.

Reference numeral 20 is a pressure switch, but it is also possible to provide a pressure detector in addition to the pressure switch and control it to act in the same manner based on the detected pressure.

<Effect of the Invention> According to the present invention, it is possible to prevent the electric pump from being repeatedly started and stopped, and prevent damage to the magnet for driving the motor. Especially when the motor capacity is large and the star delta is started, the effect is great.

[Brief description of drawings]

FIG. 1 is a system diagram of a condensate recovery device according to an embodiment of the present invention, and FIG. 2 is a system diagram of a conventional condensate recovery device. 2: Electric pump, 8: Circulation passage 10: Ejector part, 12: Discharge passage 14: Inflow passage, 16: Condensate recovery pipe 18: Full water detector, 20: Pressure switch 22, 24: Pressure control valve, 32: Pressure Detector

Claims (1)

[Scope of utility model registration request] 1. An electric pump, and a circulation passage which connects a discharge port and a suction port of the electric pump to create a condensate jet flow inside thereof.
An inflow passage that opens to the jet flow section of the circulation passage, a condensate recovery pipe that communicates with the inflow passage, a discharge passage that opens in the middle of the circulation passage, and a full water detector that detects the presence or absence of condensate in the circulation passage. And a pressure switch arranged in the discharge passage, which acts to stop the electric pump when the amount of condensed water is reduced and the discharge pressure of the electric pump is lower than the set pressure of the pressure switch, or In this system, the pressure in the condensate recovery pipe is detected when the discharge pressure does not reach the set pressure of the pressure switch within a predetermined time even if the pump starts with a small amount of condensate. A condensate recovery device is provided with a means for activating the electric pump when the pressure in the condensate recovery pipe reaches a predetermined pressure or higher and the circulation passage is filled with condensate.