JPH06331104A - Steam drain discharging device - Google Patents

Abstract

PURPOSE:To secure the discharging property of a steam trap at all times by a method wherein the inlet pipeline of the steam trap is communicated with the outlet pipeline of the same when the inlet pressure of the steam trap has become negative. CONSTITUTION:When the inlet pipeline pressure of a steam trap 8 has become negative, a pressure in the pipeline is detected by a detector 9 and the control signal of valve opening is outputted to a pressure equilibrium valve 11 on a pressure equilibrium pipeline 12. According to this operation, the inlet port and the outlet port of the steam trap 8 become a same pressure and the condition of a negative pressure is eliminated whereby drain is discharged by the pressure of water head in the steam trap 8 even when the drain is generated by the condensation of remaining steam. According to this method, the drain discharging performance in the steam trap 8 can be secured at all times.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam drain discharge device in a heat exchanger using steam as a heating source, and more particularly to maintaining a steam trap inlet pressure at a positive pressure so that the steam trap always operates properly. The present invention relates to a drain discharge device.

[0002]

2. Description of the Related Art In the basic prior art configuration shown in FIG. 6, a process inflow pipe 2 as a pipe system connected to a heat exchanger 1 and a process temperature after being heated by the heat exchanger are detected. A process outlet pipe 4 having a temperature detector 3 for receiving the temperature signal from the process temperature detector 3 so that the heat exchanger outlet temperature can be automatically adjusted to a temperature regulated by the process condition. Steam supply pipe 7 having a steam supply amount control valve 6 installed in the computer via a calculator 5
And a steam return pipe 9 having a steam trap 8 for collecting steam drain that has released heat by latent heat heating in the heat exchanger 1.

An example of application of the prior art relating to the vapor drain discharge treatment method is the technique shown in FIG. 7 and the technique described in Japanese Patent Application Laid-Open No. 4-125396.

In the prior art shown in FIG. 7, a bypass passage 7 having a valve means 2 in a steam trap 6, a pressure sensor 3 as a pressure detecting means attached to the inlet side of the valve means 2,
A temperature sensor 4 as a temperature detecting means, a control unit 5 incorporating a conversion unit for converting a pressure signal from the pressure sensor 3,
There is a steam trap device composed of signal lines 15, 16 and 17 connecting these.

[0005]

By the way, in the prior art, when the process inflow temperature to the heat exchanger is lower than the specified value and heating is required, the steam supply amount control valve is under control, that is, in the open state. Since the steam is continuously supplied, the pressure at the steam trap inlet is maintained at a positive pressure. As a result, the steam drain that has released heat by latent heat heating in the heat exchanger and has been condensed into water is normally discharged to the outside of the system through the steam trap. However, when the process inflow temperature is higher than the specified value and flows into the heat exchanger, heating is not necessary, the steam supply amount control valve is fully closed, and the steam supply is stopped. As a result, the steam piping system from the steam supply control valve to the steam trap is in a state of being isolated while containing the steam. In these piping systems, the pressure on the steam trap inlet side tends to drop for a while as the temperature drops due to heat dissipation.At this time, generally the vent hole of the steam trap body has a pressure equalizing effect with the steam trap outlet. However, when the vapor condensation rate is faster than the inflow of replacement air from the outside, a negative pressure is reached, and the drain discharge performance of the steam trap is significantly hindered and the drain accumulates at the steam trap inlet. It will be. Also, when other steam system pipes are connected to the steam trap outlet pipe, a steam backflow phenomenon from the downstream side occurs due to negative pressure on the steam trap upstream side,
Since these vapors condense on the steam trap inlet side, the amount of retained drain increases. Drain stagnation at the steam trap inlet side prevents proper heating when the process inflow temperature into the heat exchanger falls below the specified value and steam is required again, so it is installed in the latter stage of the heat exchanger. Drain retention at the steam trap inlet must be eliminated in order to avoid affecting the process treatment.

In the technique described in Japanese Patent Laid-Open No. 4-125396 shown in FIG. 7, when a drain is generated which cannot be discharged by the steam trap, or the drain cannot be discharged due to a failure of the steam trap, etc. It is considered that the main purpose is to discharge the steam drain itself through the steam trap bypass flow path as a measure to improve the response when the steam trap body side is abnormal.

The object of the present invention is to pay attention to the pressure at the inlet of the steam trap during operation, and to eliminate the negative pressure condition in which the steam trap becomes inoperable or the negative pressure condition occurs in advance. It is an object of the present invention to provide a steam drain treatment device capable of always ensuring drain discharge performance in a steam trap by causing it to operate so as to avoid it.

[0008]

According to the present invention, there is provided a steam drain treatment method capable of establishing communication between the steam trap inlet pipe and the outlet pipe when the steam trap inlet pressure becomes negative. It

Further, according to the present invention, the steam trap inlet pipe and the outlet pipe can communicate with each other when the steam supply amount control valve is fully closed, which is the main cause of the steam trap inlet pressure becoming a negative pressure. A drain treatment method is provided.

Next, according to the present invention, there is provided a steam drain treatment method capable of flowing external air into the steam trap inlet pipe when the steam trap inlet pressure becomes negative.

Furthermore, according to the present invention, there is provided a steam drain treatment method capable of injecting external air into the trap inlet pipe at the time of a fully closed event of the steam supply control valve, which is the main cause of the steam trap inlet pressure becoming a negative pressure. To be done.

According to the present invention, there is provided a vapor drain treatment method capable of forcibly injecting air so that the steam trap inlet pressure is always positive.

[0013]

According to the present invention, when the steam trap inlet pressure becomes a negative pressure, the steam trap inlet pressure and the outlet pipe are communicated with each other, so that the steam trap outlet pressure which is always in the positive pressure state becomes the steam trap inlet pressure. In addition, since the pressure on the inlet side is increased by the head pressure of the drain in the steam trap, drain discharge performance is secured.

Further, according to the present invention, when a full-closed event of the steam supply amount control valve, which is the main cause of the negative pressure of the steam trap inlet, occurs, the steam trap inlet pipe and outlet before the pressure drop occurs. By connecting the pipes, the steam trap outlet pressure, which is always in the positive pressure state, is applied to the steam trap inlet side, and it is possible to prevent the negative pressure phenomenon from occurring and ensure drainage discharge.

Next, according to the present invention, when the steam trap inlet pressure becomes a negative pressure, the external air is introduced into the system by forming a flow path into the steam trap inlet pipe into which the external air can flow. The drainage is secured because the negative pressure is released by flowing in.

Further, according to the present invention, in the case where the steam trap inlet valve is fully closed, which is the main cause of the steam trap inlet pressure becoming a negative pressure, a pressure drop occurs in the steam trap inlet pipe before a pressure drop occurs. By forming the flow path into which the external air can flow, the external air flows into the system and the negative pressure is released, so that drainage is ensured.

Further, according to the present invention, the air is forcibly injected so that the inlet pressure of the steam trap is always a positive pressure, so that drainage in the steam trap is secured.

[0018]

【Example】

(Embodiment 1) FIG. 1 is a first system diagram showing an embodiment of the present invention.

As a pipe system connected to the heat exchanger 1, a process inflow pipe 2, a process outlet pipe 4 having a temperature detector 3 for detecting a process temperature after being heated by the heat exchanger, and a process A steam supply amount installed via a calculator 5 so as to receive the temperature signal from the temperature detector 3 and automatically adjust the amount of steam at the process outlet temperature of the heat exchanger to a temperature regulated by the process processing conditions. A steam supply pipe 7 having a control valve 6, a steam trap 8 for collecting a steam drain that has released heat by latent heat heating in the heat exchanger 1, and a detection for detecting an operating pressure of a steam trap inlet pipe part. Steam return pipe 10 having a container 9 and an automatic interlock system provided with an interlock that automatically opens upon receipt of a signal from the detector 9 when the steam trap inlet pipe pressure becomes negative. The steam trap inlet and equalizing pressure pipe 12 that connects the outlet side with a pressure equalizing valve 11 closed constituting the steam drain discharge device.

The temperature of the object to be heated which flows into the heat exchanger 1 through the process inflow pipe 2 is detected by the temperature detector 3 installed on the process outlet pipe 4 so that the temperature becomes a temperature specified by the process treatment conditions. The amount of steam is automatically adjusted by the steam supply amount control valve 6 via the calculator 5. Here, when the inflow temperature of the process is lower than the specified value and is flowing into the heat exchanger 1, heating is necessary, and the steam supply amount control valve 6 is in an open state in proportion to the required steam amount. Steam return pipe 1
The pressure within 0 is a positive pressure corresponding to the pressure of the heating steam. On the other hand, the outlet pipe of the steam trap 8 is normally connected to a drain recovery tank or the like, and the operating pressure is in a weak positive pressure state near atmospheric pressure. Under this pressure condition, the drain which is latently heated by the heat exchanger 1 to release heat and condensed is normally discharged to the outside of the system through the steam trap. However, the inflow temperature of the process is higher than the specified value and the heat exchanger 1
When the gas flows into the heat exchanger 1, the heating is not necessary, the steam supply amount control valve 6 is fully closed, and the steam supply to the heat exchanger 1 is stopped. As a result, the steam piping system from the steam supply control valve 6 to the steam trap 8 is in a state of being isolated while containing steam. Since these pipe systems do not supply new heat, the temperature and pressure gradually drop. At this time, generally, the vent hole of the steam trap body works to have a pressure equalizing effect between the steam trap outlet and the steam trap outlet, but the vapor condensation rate is faster than the inflow of the replacement air from the outside. If the pressure is early, a negative pressure will be reached, causing a phenomenon in which the inlet pressure and the outlet pressure of the steam trap reverse to those in the normal state, and drain discharge is significantly hindered.
According to the present embodiment, when such a state occurs and the inlet pipe pressure of the steam trap 8 reaches a negative pressure, the pressure inside the pipe is detected by the detector 9 and the pressure equalizing pipe 12 is detected.
A control signal for opening the valve is issued to the pressure equalizing valve 11 installed above. As a result, the inlet and outlet of the steam trap 8 have the same pressure, and the negative pressure state is eliminated. Therefore, even if drainage occurs due to condensation of residual vapor, the drainage is discharged by the water head pressure in the steam trap 8.

(Embodiment 2) FIG. 2 is a system diagram of a second embodiment of the present invention.

As a pipe system connected to the heat exchanger 1, a process inflow pipe 2, a process outlet pipe 4 having a temperature detector 3 for detecting a process temperature after being heated by the heat exchanger, and a process A steam supply amount installed via a calculator 5 so as to receive the temperature signal from the temperature detector 3 and automatically adjust the amount of steam at the process outlet temperature of the heat exchanger to a temperature regulated by the process processing conditions. The steam supply pipe 7 having the control valve 6, the steam return pipe 10 having the steam trap 8 for collecting the steam drain that has released heat by latent heat heating in the heat exchanger 1, and the steam supply amount control valve 6 A steam drain discharge device is provided with a pressure equalizing valve 11 of the other force type automatic opening / closing type provided with an interlock that automatically opens upon receipt of a closing signal, and a pressure equalizing pipe 12 connecting the trap inlet side and the outlet side Constitution That.

The temperature of the object to be heated flowing into the heat exchanger 1 through the process inflow pipe 2 is detected by the temperature detector 3 installed on the process outlet pipe 4 so that the temperature becomes a temperature specified by the process treatment conditions. The amount of steam is automatically adjusted by the steam supply amount control valve 6 via the calculator 5. Here, when the inflow temperature of the process is lower than the specified value and is flowing into the heat exchanger 1, heating is necessary, and the steam supply amount control valve 6 is in an open state in proportion to the required steam amount. Steam return pipe 10
The internal pressure is a positive pressure corresponding to the pressure of the heating steam. On the other hand, the outlet pipe of the steam trap 8 is normally connected to a drain recovery tank or the like, and the operating pressure is in a weak positive pressure state near atmospheric pressure. Under this pressure condition, the drain which is latently heated by the heat exchanger 1 to release heat and condensed is normally discharged to the outside of the system through the steam trap. However, the inflow temperature of the process is higher than the specified value and the heat exchanger 1
When the gas flows into the heat exchanger 1, the heating is not necessary, the steam supply amount control valve 6 is fully closed, and the steam supply to the heat exchanger 1 is stopped. As a result, the steam piping system from the steam supply control valve 6 to the steam trap 8 is in a state of being isolated while containing steam. Since these pipe systems do not supply new heat, the temperature and pressure gradually drop. At this time, generally, the vent hole of the steam trap body works to have a pressure equalizing effect between the steam trap outlet and the steam trap outlet, but the vapor condensation rate is faster than the inflow of the replacement air from the outside. If the pressure is early, a negative pressure will be reached, causing a phenomenon in which the inlet pressure and the outlet pressure of the steam trap reverse to those in the normal state, and drain discharge is significantly hindered.
According to the present invention, when the steam supply amount control valve 6 fully-closed event, which is the main cause of the negative pressure on the inlet side of the steam trap 8, occurs, the output signal of the control valve opening from the calculator 5 or the steam supply amount. A valve closing control signal is issued to the pressure equalizing valve 11 installed on the pressure equalizing pipe 12 by detecting the valve fully closed from the opening instruction contact of the main body of the control valve 6 or the like. As a result, the inlet and outlet of the steam trap 8 have the same pressure, and the phenomenon of negative pressure at the inlet of the steam trap 8 can be avoided in advance.

(Third Embodiment) FIG. 3 is a system diagram of a third embodiment of the present invention.

As a pipe system connected to the heat exchanger 1, a process inflow pipe 2, a process outlet pipe 4 having a temperature detector 3 for detecting a process temperature after being heated by the heat exchanger, and a process A steam supply amount installed via a calculator 5 so as to receive the temperature signal from the temperature detector 3 and automatically adjust the amount of steam at the process outlet temperature of the heat exchanger to a temperature regulated by the process processing conditions. A steam supply pipe 7 having a control valve 6, a steam trap 8 for collecting a steam drain that has released heat by latent heat heating in the heat exchanger 1, and a detector for detecting an operating pressure of a trap inlet pipe section. Steam return line 10 with 9 and check valve 13
Also, when the trap inlet pipe pressure becomes a negative pressure, steam is generated by the vent pipe 15 having the other force type automatic opening / closing type vent valve 14 provided with an interlock that automatically opens upon receiving a signal from the detector 9. Configure a drain discharge device.

The object to be heated which flows into the heat exchanger 1 through the process inflow pipe 2 is temperature-detected by the temperature detector 3 installed on the process outlet pipe 4, so that the temperature becomes a temperature specified by the process treatment conditions. The amount of steam is automatically adjusted by the steam supply amount control valve 6 via the calculator 5. Here, when the inflow temperature of the process is lower than the specified value and is flowing into the heat exchanger 1, heating is necessary, and the steam supply amount control valve 6 is in an open state in proportion to the required steam amount. Steam return pipe 1
The pressure within 0 is a positive pressure corresponding to the pressure of the heating steam. On the other hand, the outlet pipe of the steam trap 8 is normally connected to a drain recovery tank or the like, and the operating pressure is in a weak positive pressure state near atmospheric pressure. Under this pressure condition, the drain which is latently heated by the heat exchanger 1 to release heat and condensed is normally discharged to the outside of the system through the steam trap. However, the inflow temperature of the process is higher than the specified value and the heat exchanger 1
When the gas flows into the heat exchanger 1, the heating is not necessary, the steam supply amount control valve 6 is fully closed, and the steam supply to the heat exchanger 1 is stopped. As a result, the steam piping system from the steam supply control valve 6 to the steam trap 8 is in a state of being isolated while containing steam. Since these pipe systems do not supply new heat, the temperature and pressure gradually drop. At this time, generally, the vent hole of the steam trap body works to have a pressure equalizing effect between the steam trap outlet and the steam trap outlet, but the vapor condensation rate is faster than the inflow of the replacement air from the outside. If the pressure is early, a negative pressure will be reached, causing a phenomenon in which the inlet pressure and the outlet pressure of the steam trap reverse to those in the normal state, and drain discharge is significantly hindered.
According to the present invention, when such a state occurs and the inlet pipe pressure of the steam trap 8 reaches a negative pressure, the pressure in the pipe is detected by the detector 9 and the vent pipe 1
A control signal for opening the valve is issued to the vent valve 14 which is installed on the valve 5 and is in a fully closed state for the purpose of isolating the steam system pipe that is high pressure during normal operation from the facility. As a result, external air can flow into the inlet side of the steam trap 8 and the negative pressure state is eliminated. Therefore, even if drainage occurs due to condensation of residual vapor, the drainage is discharged by the water head pressure in the steam trap 8. The check valve 13 installed on the vent pipe 15 prevents the outflow of steam from the steam pipe to the outside when the vent valve is opened.

(Embodiment 4) FIG. 4 is a system diagram of a fourth embodiment of the present invention.

As a pipe system connected to the heat exchanger 1, a process inflow pipe 2, a process outlet pipe 4 having a temperature detector 3 for detecting a process temperature after being heated by the heat exchanger, and a process. A steam supply amount installed via a calculator 5 so as to receive the temperature signal from the temperature detector 3 and automatically adjust the amount of steam at the process outlet temperature of the heat exchanger to a temperature regulated by the process processing conditions. A steam supply pipe 7 having a control valve 6, a steam return pipe 10 having a steam trap 8 for collecting steam drain that has released heat by latent heat heating in the heat exchanger 1, a check valve 13 and a steam supply amount. Vent valve 1 of other force type automatic opening and closing type which is provided with an interlock that automatically opens in response to a fully closed signal of the control valve 6.
A steam drain discharge device is configured with the vent pipe 15 having the number 4. The object to be heated which flows into the heat exchanger 1 through the process inflow pipe 2 is temperature-detected by the temperature detector 3 installed on the process outlet pipe 4, and the temperature is regulated according to the process treatment condition. The amount of steam is automatically adjusted by the steam supply amount control valve 6 via 5. Here, when the inflow temperature of the process is lower than the specified value and is flowing into the heat exchanger 1, heating is necessary, and the steam supply amount control valve 6 is in an open state in proportion to the required steam amount. The pressure in the steam return pipe 10 is a positive pressure corresponding to the pressure of the heating steam. on the other hand,
The outlet pipe of the steam trap 8 is usually connected to a drain recovery tank or the like, and the operating pressure is in a weak positive pressure state near atmospheric pressure. Under this pressure condition, the drain which is latently heated by the heat exchanger 1 to release heat and condensed is normally discharged to the outside of the system through the steam trap. However, the inflow temperature of the process is higher than the specified value and the heat exchanger 1
When the gas flows into the heat exchanger 1, the heating is not necessary, the steam supply amount control valve 6 is fully closed, and the steam supply to the heat exchanger 1 is stopped. As a result, the steam piping system from the steam supply control valve 6 to the steam trap 8 is in a state of being isolated while containing steam. Since these pipe systems do not supply new heat, the temperature and pressure gradually drop. At this time, generally, the vent hole of the steam trap body works to have a pressure equalizing effect between the steam trap outlet and the steam trap outlet, but the vapor condensation rate is faster than the inflow of the replacement air from the outside. If the pressure is early, a negative pressure will be reached, causing a phenomenon in which the inlet pressure and the outlet pressure of the steam trap reverse to those in the normal state, and drain discharge is significantly hindered.
According to the present invention, when a steam supply amount control valve 6 fully-closed event, which is a basic factor leading to a negative pressure on the inlet side of the steam trap 8, occurs, the output signal of the control valve opening from the calculator 5 or the steam supply amount. It is installed on the vent pipe 15 by detecting the valve full closure from the opening indicating contact of the control valve 6 main body, etc., and it is in the fully closed state for the purpose of isolating the steam system pipe that becomes high pressure during normal operation from the facility. A control signal for opening the vent valve 14 is issued. As a result, external air can flow into the inlet side of the steam trap 8 and the negative pressure state is eliminated. Therefore, even if drainage occurs due to condensation of residual steam, the drainage is discharged by the water head pressure in the steam trap 8.
The check valve 13 installed on the vent pipe 15 prevents the steam from flowing out of the steam system pipe when the vent valve is opened.

(Fifth Embodiment) FIG. 5 is a system diagram of a fifth embodiment of the present invention.

As a pipe system connected to the heat exchanger 1, a process inflow pipe 2, a process outlet pipe 4 having a temperature detector 3 for detecting a process temperature after being heated by the heat exchanger, and a process A steam supply amount installed via a calculator 5 so as to receive the temperature signal from the temperature detector 3 and automatically adjust the amount of steam at the process outlet temperature of the heat exchanger to a temperature regulated by the process processing conditions. A steam supply pipe 7 having a control valve 6, a steam trap 8 for collecting a steam drain that has released heat by latent heat heating in the heat exchanger 1, and a detection for detecting an operating pressure in a trap inlet pipe section. A steam return pipe 10 having a vessel 9 and a calculator 16 for automatically adjusting the air amount so that the inlet pipe of the steam trap 8 receives a pressure signal from the detector 9 so as to always have a positive pressure. Constituting the steam drain discharge device in the air injection pipe 18 having an installed air supply amount regulating valve 17.

The object to be heated which flows into the heat exchanger 1 through the process inflow pipe 2 is temperature-detected by the temperature detector 3 installed on the process outlet pipe 4 so that the temperature becomes a temperature specified by the process treatment conditions. The amount of steam is automatically adjusted by the steam supply amount control valve 6 via the calculator 5. Here, when the inflow temperature of the process is lower than the specified value and is flowing into the heat exchanger 1, heating is necessary, and the steam supply amount control valve 6 is in an open state in proportion to the required steam amount. Steam return pipe 10
The internal pressure is a positive pressure corresponding to the pressure of the heating steam. On the other hand, the outlet pipe of the steam trap 8 is normally connected to a drain recovery tank or the like, and the operating pressure is in a weak positive pressure state near atmospheric pressure. Under this pressure condition, the drain which is latently heated by the heat exchanger 1 to release heat and condensed is normally discharged to the outside of the system through the steam trap. However, the inflow temperature of the process is higher than the specified value and the heat exchanger 1
When the gas flows into the heat exchanger 1, the heating is not necessary, the steam supply amount control valve 6 is fully closed, and the supply of steam to the heat exchanger 1 is stopped. As a result, the steam piping system from the steam supply control valve 6 to the steam trap 8 is in a state of being isolated while containing steam. Since these pipe systems do not supply new heat, the temperature and pressure gradually drop. At this time, generally, the vent hole of the steam trap body works to have a pressure equalizing effect between the steam trap outlet and the steam trap outlet, but the vapor condensation rate is faster than the inflow of the replacement air from the outside. If the pressure is early, a negative pressure will be reached, causing a phenomenon in which the inlet pressure and the outlet pressure of the steam trap reverse to those in the normal state, and drain discharge is significantly hindered. According to the present invention, when such a state occurs and the inlet pipe pressure of the steam trap 8 reaches a negative pressure,
A control signal is issued to detect the pressure in the pipe by the detector 9 and to inject the air flow control valve 17 installed on the air injecting pipe 18 with the air suitable for eliminating the negative pressure. As a result, air is introduced into the inlet side of the steam trap 8 and the negative pressure state is eliminated, so that even if drainage occurs due to condensation of residual vapor, the drainage is discharged by the water head pressure in the steam trap 8.

[0032]

EFFECTS OF THE INVENTION According to the present invention, it is possible to avoid a negative pressure phenomenon on the steam trap inlet side that occurs when the steam supply to the heat exchanger is stopped, etc., and drain accumulation on the steam trap inlet side is prevented. It can be resolved.

[Brief description of drawings]

FIG. 1 is a system diagram showing a first embodiment of the present invention.

FIG. 2 is a system diagram showing a second embodiment of the present invention.

FIG. 3 is a system diagram showing a third embodiment of the present invention.

FIG. 4 is a system diagram showing a fourth embodiment of the present invention.

FIG. 5 is a system diagram showing a fifth embodiment of the present invention.

FIG. 6 is a system diagram showing a first example of a conventional technique.

FIG. 7 is a system diagram showing a second example of the prior art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Heat exchanger, 2 ... Process inflow piping, 3 ... Temperature detector, 4 ... Process exit piping, 5 ... Temperature calculator, 6 ... Steam supply amount control valve, 7 ... Steam supply piping, 8 ... Steam trap, 9 ... pressure detector, 10 ... steam return pipe, 11 ... pressure equalizing valve, 12 ... pressure equalizing pipe, 13 ... check valve, 14 ... vent valve,
15 ... Vent pipe, 16 ... Pressure calculator, 17 ... Air inflow control valve, 18 ... Air injection pipe.

Claims (5)

[Claims] 1. A steam supply amount control valve for controlling a process temperature on a steam supply pipe which is a primary side of a steam using device, wherein steam is used as a heating source for raising a process to a specified temperature. In a heat exchanger having a steam trap for the purpose of discharging steam drain after latent heat heating on the secondary side of the equipment used, a detector for detecting an operating pressure in the steam trap inlet pipe section, and the steam trap inlet side And a pressure equalizing pipe connecting the outlet side, a pressure equalizing valve of the other force type automatic opening and closing on the pressure equalizing pipe, and when the pipe pressure at the steam trap inlet becomes negative pressure, the detector A steam drain discharge device having an interlock for automatically opening the pressure equalizing valve in response to a signal. 2. The pressure equalizing pipe connecting the inlet side and the outlet side of the steam trap, the other force type automatic opening / closing type pressure equalizing valve on the pressure equalizing pipe, and the steam supply amount according to claim 1. A steam drain discharge device provided with an interlock that automatically opens the pressure equalizing valve when the control valve is fully closed and the supply of steam to the equipment using steam is stopped. 3. A detector for detecting an operating pressure in the steam trap inlet pipe section according to claim 1, and a connection of a vent pipe having a check valve and the pressure equalizing valve to the steam trap inlet side pipe, A steam drain discharge device provided with an interlock for automatically opening the pressure equalizing valve on the vent pipe in response to a signal from the detector when the pressure in the steam trap inlet pipe becomes negative. 4. The steam according to claim 1, wherein the steam trap inlet side pipe is connected to a vent pipe having a check valve and the pressure equalizing valve, and the steam supply control valve is fully closed. A vapor drain discharge device provided with an interlock that automatically opens the pressure equalizing valve on the vent pipe when the supply is stopped. 5. The detector for detecting an operating pressure in the steam trap inlet pipe section according to claim 1,
Connection of an air injection pipe having the pressure equalizing valve to the steam trap inlet side pipe, and a control circuit for automatically injecting an air amount so that the pressure of the steam trap inlet is always positive pressure by a pressure signal of the detector is installed. Completed steam drain discharge device.