GB2231407A

GB2231407A - Monitoring condensate traps

Info

Publication number: GB2231407A
Application number: GB9010029A
Authority: GB
Inventors: Richard Q Carmichael
Original assignee: Spirax Sarco Ltd
Current assignee: Spirax Sarco Ltd
Priority date: 1989-05-03
Filing date: 1990-05-03
Publication date: 1990-11-14
Anticipated expiration: 2010-05-03
Also published as: GB2231407B; GB9010029D0; GB8910146D0

Abstract

A condensate trap (such as a steam trap) is monitored by means of a sensor chamber 4, disposed upstream of the trap. The chamber 4 is divided by a partition 10 pierced by a pressure equalising aperture 16, into inlet and outlet compartments 6, 8. A level sensor 18 extends into the inlet compartment 6 and a thermoelectric (eg Peltier effect) generator 20 is disposed on the wall of the outlet compartment 8. In use, the status of the steam trap is displayed as a function of the temperature and level of condensate in the monitor, electrical power for operating the monitor being generated by the thermoelectric generator 20. The monitor is thus self-contained and requires no external power source. In alternative embodiments, the peltier generator 20 may be located in the steam trap or the level sensor may comprise a float carrying an actuating element which operates switches. <IMAGE>

Description

MONITORING CONDENSATE TRAPS This invention relates to the monitoring of condensate traps, such as steam traps.

Steam traps are employed to collect condensate forming in steam systems and to discharge the condensate from the system without permitting the escape of steam. Under abnormal circumstances, it is possible for a steam trap to permit the leakage of steam from the system in which it is installed, or for the steam trap to become waterlogged, and so become incapable of discharging further condensate. Either circumstance can have undesirable consequences, for example energy wastage or the presence of excessive water within the steam system.

It is therefore desirable for steam traps to be equipped with means providing a visual indication of their the operative condition.

It is also desirable for any such means to provide automatic indication of any failure of the indicating means itself.

In a broad aspect of the present invention, there is provided a self-contained condensate trap installation comprising a condensate trap and a monitor for the condensate trap, the monitor being disposed in line with the condensate trap and having read-out means for indicating the condition of the condensate trap.

According to another aspect of the present invention, there is provided a condensate trap installation comprising a condensate trap and a monitor for the condensate trap, the monitor comprising a chamber for collecting condensate, the chamber being divided by a partition into an inlet compartment and an outlet compartment which communicate with each other at their lower regions, and into which open, respectively, inlet and outlet ducts, the partition having, at a level above the normal level of condensate in the chamber, a pressure equalising aperture, the monitor comprising sensing means responsive to the level of condensate in the monitor and to the temperature of fluid in the condensate trap, the monitor further comprising read-out means which is responsive to the sensing means for displaying the operative condition of the condensate trap without the monitor requiring any external power supply.

According to a third aspect of the present invention there is provided a condensate trap monitor comprising a chamber for collecting condensate, the chamber being divided by a partition into an inlet compartment and an outlet compartment which communicate with each other at their lower regions, and into which open, respectively, inlet and outlet ducts, the partition having, at a level above the normal level of condensate in the chamber, a pressure equalising aperture, the monitor comprising sensing means responsive to the level of condensate in the monitor and to the temperature of fluid in the chamber, the monitor further comprising read-out means which is responsive to the sensing means for displaying the operative condition of the condensate trap without the monitor requiring any external power supply.

The detector may comprise a thermo electric generator responsive to the temperature differential between fluid in the condensate trap or the monitor and the ambient surroundings.

The sensing means may comprise a thermo electric generator responsive to the temperature differential between fluid in the condensate trap or the monitor and the ambient surroundings.

Thus, the monitor may be powered by electricity generated by the temperature differential between the fluid in the condensate trap or the monitor and the ambient surroundings. For example, the thermo electric generator may comprise a Peltier cell or Seebeck device, or other means for converting thermal energy into electrical energy.

The thermo electric generator may be positioned so that, in normal operation of the condensate trap, it is responsive to the temperature differential between condensate in the monitor, for example in the outlet compartment, and the ambient surroundings.

Alternatively, the thermo electric generator may be positioned so as to be responsive to the temperature differential between vapour in the monitor and ambient surroundings. Another possibility is for the thermo electric generator to be responsive to the temperature differential between fluid in the condensate trap and the ambient surroundings.

In an embodiment in accordance with the present invention, the outlet duct from the chamber communicates with the interior of the condensate trap so that condensate collected initially in the monitor chamber is passed to the condensate trap and then discharged, for example to be returned to a boiler, when the condensate in the condensate trap reaches a predetermined level. In such an embodiment, the thermo electric generator may be provided on the wall of the condensate trap in such a position as to be responsive, in normal operation, to the temperature of vapour within the condensate trap. The condensate trap may be actuated by a float movable in a float chamber of the condensate trap in response to the level of condensate in the float chamber.

The monitor may comprise a rechargeable accumulator or battery for powering the monitor when the thermo electric generator is not effective (for example when the temperature differential across it is too small). The accumulator or battery may be charged by the thermo electric generator.

According to a fourth aspect of the present invention there is provided a condensate trap monitor comprising a chamber for collecting condensate, the chamber being divided by a partition into an inlet compartment and an outlet compartment which communicate with each other at their lower regions, and into which open, respectively, inlet and outlet ducts, the partition having, at a level above the normal level of condensate in the chamber, a pressure equalizing aperture, a monitor float being provided in the chamber, the monitor float having an actuating element which actuates read-out means in dependence on the position of the float such that, when the float is above a first predetermined level, the read-out means signifies that the trap may be waterlogged and when the float is below a second predetermined level the readout means signifies vapour leakage through the condensate trap.

In such a monitor, the position of the monitor float will depend both on the level of condensate, for example in the inlet chamber, and on the presence of vapour in the condensate. Thus, even if the inlet compartment is full of condensate, the presence of vapour in the condensate, signifying vapour leakage through the condensate trap, will reduce the buoyancy of the monitor float to cause the read-out means to signify vapour leakage.

For a better understanding of the present invention , and to show how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a diagrammatic sectional view of a steam trap monitor; Figure 2 is a circuit diagram representing processing circuitry of the steam trap monitor of Figure 1; Figure 3 is a diagrammatic sectional view of a second embodiment of steam trap monitor; and Figure 4 is a diagrammatic sectional view of a steam trap and a third embodiment of a steam trap monitor.

The steam trap monitor shown in Figure 1 comprises a body 2 defining a sensor chamber 4 which is divided into inlet and outlet compartments 6, 8 by a partition 10. An inlet duct 12 opens into the inlet compartment 6, and an outlet duct 14 extends from the outlet compartment 8 for connection to the inlet of the steam trap. There is a pressure equalising aperture 16 in the partition 10 to enable pressure equalization between the inlet and outlet compartments 6 and 8 without permitting excessive flow of steam between the inlet and outlet ducts 12 and 14.

A level sensor 18 is supported by the body 2 so as to project into the inlet compartment 6. The sensor 18 is positioned at a level such that, in normal operation of the steam trap, it is submerged in condensate collected within the chamber 4.

A thermo electric generator 20 in the form of a Peltier cell is secured to the body 2 at the outlet compartment 8. Thus, one surface of the Peltier cell 20 is substantially at the temperature of fluid within the outlet compartment 8, while the other surface of the cell is at substantially ambient temperature and is cooled by means of a finned heat exchanger 22.

Processing circuitry 24 is mounted on the heat exchanger, although the heat exchanger 22 and the control circuitry 24 are separated by a layer of insulating material 26. The processing circuitry controls read-out means in the form of an electromechanical display 28, represented only diagrammatically in Figure 1. The display comprises two windows 30 and 32 behind which moves a flag to present either an "OK" signal, represented by a / or a "fault" signal represented by an X.

The basic principles underlying the control circuitry are represented diagrammatically in Figure 2.

The circuit comprises two loops having a common branch including a variable resistor 34.

One loop includes the Peltier cell 20, a relay 36 actuating the flags at the window 32, a relay 38 operating a latch 40, the variable resistor 34 and a relay 42 operating volt-free contacts for providing signals to external monitoring equipment. The second loop includes the sensor 18, a relay 44, corresponding to the relay 42, for providing signals to external monitoring equipment, the variable resistor 34, and a relay 46 for operating the flag corresponding to the window 30.

If the temperature of the fluid within the outlet compartment 8 is represented by t5 and the ambient temperature is represented by ta, the circuitry operates as follows: a) if tS-ta is greater than the temperature required to generate a useful voltage at the Peltier cell, for example 50 C, current will flow in the loop containing the Peltier cell 20 so as to energise the solenoids 36, 38 and 42. The solenoid 36 causes the flag in the window 32 to be displaced to expose the /, indicating that power is "on" and that the monitoring system is therefore functioning. The solenoid 38 holds open the latch 40, permitting free displacement of the flag at the window 30, depending on the state of energisation of the solenoid 46.

b) if tS-ta is less than 50 C, no current is generated by the Peltier cell 20, and the flag at the window 32 is displaced to reveal the X, indicating that there is an insufficient temperature differential to power the monitoring system. This, in turn, could indicate abnormal operation of the steam trap, for example the fact that the chamber 4 contains cold condensate, signifying that the trap is waterlogged or airlocked. Furthermore, because the solenoid 38 is not energised, the latch 40 is closed, preventing displacement of the flag at the window 30. The flag at the window 30 thus displays the /, signifying that no steam is leaking through the steam trap.

c) if the level sensor 18 is submerged in condensate, current flows in the associated circuit loop, and the solenoid 46 displaces the flag at the window 30 to display the /, signifying no leakage of steam.

d) if the level sensor 18 is above the level of condensate in the inlet compartment 6, no current will flow in the associated circuit loop and, provided that the latch 40 is open, the flag at the window 30 will be displaced to reveal the X signifying steam leakage.

It will be appreciated that the solenoid coils 36, 38, 42, 44 and 46 will damp the current flowing in the circuitry, so preventing rapid oscillation of the flags at the windows 30 and 32 should, for example, bubbles of vapour be passing through condensate in the chamber 4.

The embodiment of Figure 3 includes a sensor chamber similar to that shown in Figure 1, and so the same reference numbers are used to identify the same parts.

The outlet duct 14 is connected to an inlet duct 47 of a steam trap 49. The inlet duct 47 opens into a float chamber 48, which accommodates a float 50. The float 50 is pivotably mounted within the chamber 48. A float operated valve 52 is opened when the level of condensate in the float chamber 48, as detected by displacement of the float 50, rises to a predetermined level. Opening of the valve 52 allows condensate to flow from the float chamber 48 to a return line 54.

The float chamber 48 is also provided with a thermostatic air valve 56, for venting air from the float chamber 48 during initial start-up from cold.

A Peltier cell 58 is provided on the wall of the float chamber 48 at a level above that at which the float-operated valve 52 opens. Thus, this Peltier cell 58 is normally responsive to the temperature differential between vapour within the float chamber 48 and the ambient surroundings. As in the embodiment of Figure 1, heat is removed from the surface of the Peltier cell 58 away from the wall of the float chamber 48 by means of a finned heat exchanger 60. Signals from the level sensor 18 and the Peltier cell 58 are conveyed to a local read-our means 62, comprising processing circuitry which may be the same as that shown in Figure 2. Means is also provided for relaying signals to remote monitoring equipment, if desired.

The read-out means 62 shown in Figure 3 provides an indication of the operating condition of the steam trap by means of an array of indicating lamps 64.

In both of the embodiments of Figures 1 and 3, the Peltier cells 20 and 58 provide the electrical power necessary to operate the processing circuitry.

Consequently, the monitoring means requires no external power source, nor does it rely on batteries except for back-up purposes when the Peltier cells are inoperative. In normal operation of the steam traps, electrical power is generated by the Peltier cells 20 and 58, and the display device consequently provides an immediate indication of normal functioning both of the steam trap and of the monitor.

The embodiment of Figure 4 shares several features with that of the embodiments of Figures 1 and 3, and, again, the same reference numbers are used to represent the same parts.

In this embodiment, a monitor float 66 is provided within the inlet compartment 6. A rod 68 projects upwardly from the float 66 and carries an actuating element 70. The actuating element 70 may, for example, be a magnet or may be made from a magnetically susceptible material, in order to actuate, for example, reed switches 72 or other proximity devices, such as Hall effect devices. Where electrical power is required to operate the read-out means, a Peltier cell or other thermo electric generator may be used, as the previous embodiments. Alternatively, or in addition, the actuating element 17 may actuate read-out means such as a magnetic strip indicator 74 for providing a local display of the operative condition of the steam trap, in which case no electrical power generation is required.

In operation, under normal conditions, the float will be at an intermediate position, with the actuating element 70 opposite the "G" (or green section) of the magnetic strip indicator 74. If the condensate level in the steam trap rises, so that the steam trap becomes waterlogged, the float will also rise until the actuating element 70 reaches the "Y", or yellow region of the magnetic strip indicator 74. Alternatively, should vapour bubble through the condensate in the chamber 2, as shown in FIgure 4, the average specific gravity of the fluid within the chamber 2 will fall, and the float 66 will sink within the condensate to carry the actuating element 70 to the "R" or red region of the magnetic strip indicator 74.

The embodiment of Figure 4 thus provides, in a simple way, an indication of the operating condition of the steam trap, without requiring any electronic control circuitry.

Claims

1. A self-contained condensate trap installation comprising a condensate trap and a monitor for the condensate trap, the monitor being disposed in line with the condensate trap and having read-out means for indicating the condition of the condensate trap.

2. A condensate trap installation comprising a condensate trap and a monitor for the condensate trap, the monitor comprising a chamber for collecting condensate, the chamber being divided by a partition into an inlet compartment and an outlet compartment which communicate with each other at their lower regions, and into which open, respectively, inlet and outlet ducts, the partition having, at a level above the normal level of condensate in the chamber, a pressure equalising aperture, the monitor comprising sensing means responsive to the level of condensate in the monitor and to the temperature of fluid in the condensate trap, the monitor further comprising readout means which is responsive to the sensing means for displaying the operative condition of the condensate trap without the monitor requiring any external power supply.

3. A condensate trap monitor comprising a chamber for collecting condensate, the chamber being divided by a partition into an inlet compartment and an outlet compartment which communicate with each other at their lower regions, and into which open, respectively, inlet and outlet ducts, the partition having, at a level above the normal level of condensate in the chamber, a pressure equalising aperture, the monitor comprising sensing means responsive to the level of condensate in the monitor and to the temperature of fluid in the chamber, the monitor further comprising read-out means which is responsive to the sensing means for displaying the operative condition of the condensate trap without the monitor requiring any external power supply.

4. An installation or a monitor as claimed in claim 2 or 3, wherein the sensing means comprises a thermoelectric generator responsive to the temperature differential between the vapour and/or condensate in the condensate trap on the chamber and the ambient surroundings such that, when the temperature differential is less than a predetermined value, the read-out means indicates that the trap may be waterlogged.

5. An installation or a monitor as claimed in claim 4, wherein the monitor is powered by electricity generated by the temperature differential between the vapour and/or condensate and the ambient surroundings.

6. An installation or a monitor as claimed in claim 4 or 5, wherein the thermoelectric generator comprises a Peltier cell or Seebeck device.

7. An installation or a monitor as claimed in any one of claims 4 to 6, wherein a rechargeable battery is connected so as to be charged by the thermoelectric generator when the temperature differential is greater than the predetermined value and so as to power the monitor when the temperature differential is less than the predetermined value.

8. A condensate trap monitor comprising a chamber for collecting condensate, the chamber being divided by a partition into an inlet compartment and an outlet compartment which communicate with each other at their lower regions, and into which open, respectively, inlet and outlet ducts, the partition having, at a level above the normal level of condensate in the chamber, a pressure equalizing aperture, a monitor float being provided in the chamber, the monitor float having an actuating element which actuates read-out means in dependence on the position of the float such that, when the float is above a first predetermined level, the read-out means signifies that the trap may be waterlogged and when the float is below a second predetermined level the read-out means signifies vapour leakage through the condensate trap.

9. A monitor as claimed in claim 8, wherein the monitor float is disposed in the inlet compartment.

10. A steam trap monitor substantially as shown in, and described herein with reference to, Figures 1 and 2, 3 or 4 of the accompanying drawings.