GB2576427A

GB2576427A - Closed-loop pipework system de-aeration apparatus

Info

Publication number: GB2576427A
Application number: GB1910339.9A
Authority: GB
Inventors: Derek Barrett Peter
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-07-19
Filing date: 2019-07-19
Publication date: 2020-02-19
Anticipated expiration: 2039-07-19
Also published as: GB201910339D0; GB2576427B

Abstract

De-aeration apparatus 500 with a water inlet 102 to an expansion pipework 106 receiving water from a closed-loop pipework system, the diameter of the outlet end 110 being larger than the inlet end. The outlet end opens below a normal operating level in a water tank 104 open to the atmosphere. The diameter of the outlet end section may increase towards the outlet end which may be dome-shaped. The tank may contain Raschig rings 202 and/or mesh to disrupt flow. The tank may have a partition to define an inlet area, the partition having a number of apertures which may be below the normal operating level and above the pipework outlet. There may be a flow-limiter 502 and pump 520 which are configured to maintain the level in the tank, potentially using a controller 530 and two level sensors 510,512. A heat exchanger connected to the closed-loop pipework system is also claimed.

Description

CLOSED-LOOP PIPEWORK SYSTEM DE-AERATION APPARATUS

Technical Field

The invention relates to a closed-loop pipework system de-aeration apparatus and to a heat exchanger comprising the closed-loop pipework system de-aeration apparatus.

Background

Closed-loop pipework systems, such as heating pipework systems or cooling pipework systems, such as air-conditioning systems, are filled with water during normal operation. During the process of filing a closed-loop pipework system with water air can become trapped within the system, both as dissolved and undissolved air. Dissolved oxygen in the water can give rise to corrosion within the pipework system and undissolved air in the water can cause operational problems and mechanical damage to the pipework system. Air trapped within a closed-loop pipework system is traditionally removed by flushing the water within the system to drain, which results in large volumes of effluent being disposed of to drain and wastes large volumes of water.

Summary

It is an object to provide an improved closed-loop pipework system de-aeration apparatus. It is a further object to provide an improved heat exchanger.

An aspect of the invention provides closed-loop pipework system de-aeration apparatus comprising a water inlet, a water tank and expansion pipework. The water inlet is adapted to receive water at operating pressure from a closed-loop pipework system. The water tank is open to atmosphere. The expansion pipework has an inlet end and an outlet end. The inlet end is adapted to receive water from the water inlet. The outlet end is located within the water tank at a position below a normal operating water level of the water tank. The expansion pipework comprises an end section at the outlet end, a diameter of the end section being larger than a diameter of the expansion pipework at the inlet end.

The de-aeration apparatus enables both dissolved and undissolved air to be removed from water within a closed-loop pipework system during circulation of water within the system. The expansion pipework enables water to be taken from the closed-loop pipework system at operating pressure and released to atmospheric pressure allowing both dissolved and undissolved air to be liberated, as bubbles and microbubbles. Introducing the water into the tank below the normal operating water level of the tank, via the larger diameter end section, minimises re-aspiration as the water enters the tank.

In an embodiment, the diameter of the end section increases from a first end to the outlet end. This may increase the amount of air that is liberated and minimise re-aspiration.

In an embodiment, the end-section has a generally domed shape. This may increase the amount of air that is liberated and minimise re-aspiration.

In an embodiment, the closed-loop pipework system de-aeration apparatus further comprises at least one flow disrupting element provided within the water tank below the normal operating water level. This may enhance the removal of bubbles and microbubbles from the water.

In an embodiment, the at least one flow disrupting element comprises a plurality of Raschig rings. The large total surface area of the Raschig rings may enhance the removal of bubbles and microbubbles from the water.

In an embodiment, the at least one flow disrupting element comprises an open mesh.

In an embodiment, the closed-loop pipework system de-aeration apparatus further comprises a partition provided within the water tank, the partition defining an inlet area of the water tank within which the outlet end of the expansion pipework is located. The partition has a plurality of apertures provided through it connecting the inlet area to a remaining area of the water tank, the apertures being located below the normal operating water level. The partition advantageously separates the incoming water from the at least one flow disrupting element, allowing bubbles and microbubbles within the water to rise to the surface before the incoming water flow arrives at the at least one flow disrupting element.

In an embodiment, the apertures in the partition are located higher within the water tank than the outlet end of the expansion pipework. This may reduce the occurrence of turbulence in the water tank due to incoming water and allow microbubbles within the incoming water to be released in that region of the tank.

In an embodiment, the closed-loop pipework system de-aeration apparatus further comprises a flow-limiter between the water inlet and the inlet end of the expansion pipework. The flow-limiter advantageously enables the apparatus to operate with closed-loop pipework systems having differing operating pressures. The flow-limiter may also advantageously reduce the pressure of water received at the water inlet, assisting in the release of dissolved and undissolved air within the water.

In an embodiment, the water tank comprises a water outlet. The closed-loop pipework system de-aeration apparatus further comprises a pump connected to the water outlet. The pump and the flow limiter are configured to have substantially the same flow rate. The apparatus may advantageously process water from a closed-loop pipework system at a constant flow rate, and may continuously receive water from the closed-loop pipework system and return deaerated water back into the closed-loop pipework system.

In an embodiment, the closed-loop pipework system de-aeration apparatus further comprises first and second level probes and a controller. The first level probe is configured to detect a first water level within the water tank. The second level probe is configured to detect a second, lower water level within the water tank. The controller is configured to generate at least one pump control signal. The pump control signal is configured to cause the pump to run in response to the first level probe detecting the first water level. The pump control signal is configured to cause the pump to stop in response to the second level probe detecting the second water level. The level probes and controller together advantageously operate so that the water tank does not overflow and so that the water level within the tank does not become so low that the pump cannot operate to return water to the closed-loop pipework system.

In an embodiment the controller comprises interface circuitry and processing circuitry. The interface circuitry is configured for communication with the first and second level probes and with the pump. The processing circuitry is configured to generate the at least one control signal.

In an embodiment, the level probes are located in an opposite corner of the water tank to the expansion pipework. This may ensure that the level probes are not damaged by the incoming water.

Corresponding embodiments apply equally to the heat exchanger described below.

A further aspect of the invention provides a heat exchanger comprising a closed-loop pipework system and closed-loop pipework system de-aeration apparatus. The closed-loop pipework system de-aeration apparatus comprising a water inlet, a water tank and expansion pipework. The water inlet is adapted to receive water at operating pressure from a closed-loop pipework system. The water tank is open to atmosphere. The expansion pipework has an inlet end and an outlet end. The inlet end is adapted to receive water from the water inlet. The outlet end is located within the water tank at a position below a normal operating water level of the water tank. The expansion pipework comprises an end section at the outlet end, a diameter of the end section being larger than a diameter of the expansion pipework at the inlet end.

The heat exchanger is advantageously able to operate to remove dissolved and undissolved air from water within its closed-loop pipework system during circulation of water within the system.

Brief Description of the drawings

Figures 1 to 6 and 9 are schematic illustrations of closed-loop pipework system deaeration apparatus according to embodiments of the invention; and

Figures 7 and 8 are schematic illustrations of heat exchangers according to embodiments of the invention.

Detailed description

The same reference numbers will used for corresponding features in different embodiments.

Referring to Figure 1, an embodiment of the invention provides closed-loop pipework system de-aeration apparatus 100 comprising a water inlet 102, a water tank 104 and expansion pipework 106.

The water inlet 102 is adapted to receive water at operating pressure from a closedloop pipework system. The water tank 104 is open to atmosphere. It will be appreciated by the skilled person that while the water tank is illustrated here as being completely open at the top, it may be partially covered and still be considered to be open to the atmosphere.

The expansion pipework 106 has an inlet end and an outlet end. The inlet end is adapted to receive water from the water inlet. The outlet end is located within the water tank at a position below a normal operating water level 108 of the water tank. The expansion pipework comprises an end section 110 at the outlet end. The end section has a diameter which is larger than the diameter of the expansion pipework at the inlet end.

The expansion pipework produces a controlled reduction in the water pressure, from full operating pressure to atmospheric pressure, causing dissolved and undissolved air in the water to be liberated, as bubbles and microbubbles. The larger diameter end section and the release of the water into the tank below the normal operating water level minimises re-aspiration as the water enters the tank.

In an embodiment, the diameter of the end section 110 increases from a first end, where it is connected to the rest of the expansion pipework, to its outlet end. This causes a controlled change in the water pressure. As illustrated here, the diameter of the end section may increase in a graded manner, to give the end section a generally domed shaped, as illustrated here.

In an embodiment, as illustrated in Figures 2 and 3, the closed-loop pipework system de-aeration apparatus 200, 300 additionally comprises at least one flow disrupting element 202, 302 provided within the water tank below the normal operating water level. In one embodiment, illustrated in Figure 2, the at least one flow disrupting element comprises a plurality of Raschig or Pall rings 202. In another embodiment, illustrated in Figure 3, the at least one flow disrupting element comprises an open mesh. The Raschig rings and the mesh disrupt the flow of water delivered into the water tank from the expansion pipework as the water impinges on their surfaces. This assists in the creation and release of bubbles and micro-bubbles.

In an embodiment, illustrated in Figure 4, the closed-loop pipework system de-aeration apparatus 400 additionally comprises a partition 402 provided within the water tank. The partition defines an inlet area 406 of the water tank within which the outlet end of the expansion pipework is located. The partition has a plurality of apertures 404 provided through it connecting the inlet area to a remaining area of the water tank. The apertures are located below the normal operating water level of the water tank.

The partition separates the incoming water, and recently arrived water, from the Raschig rings 202 or the mesh 302. This allows bubbles and microbubbles already existing within the water to rise to the surface, and escape, before the water reaches the Raschig rings or mesh, where the flow is disrupted and more bubbles are created, as dissolved air starts to come out of the water.

In an embodiment, the apertures 404 in the partition are located higher within the water tank than the outlet end of the expansion pipework, so that water cannot flow directly from the expansion pipework to the Raschig rings or the mesh.

In an embodiment, illustrated in Figures 5 and 6, the closed-loop pipework system deaeration apparatus further comprises a flow-limiter 502 and a solenoid value 504, 506 provided between the water inlet and the inlet end of the expansion pipework 106. The flow-limiter 502 is configured to limit the water flow into the water inlet, and thereby reduces the water pressure entering the water inlet. The solenoid valve 504, 506 is controllable to open or close the water inlet. In this example, a soft close solenoid valve is used to mitigate water-hammer effects.

The water tank 104 is provided with a water outlet 518 and a bleed line 524. The apparatus 500 additionally comprises a water pump 520 connected to the water outlet and a non-return valve 522. The bleed line connects between the pump and the non-return valve. The outlet of the non-return valve is adapted to be coupled to a return pipe, to return de-aerated water to the closed-loop pipework system.

The water pump operates to pump de-aerated water from the water tank, via the water outlet 518 and the non-return valve 522, back into the closed-loop pipework system. The water pump and the flow limiter are configured to have substantially the same flow rate, so that water is removed, de-aerated and returned to the closed-loop pipework system at a steady rate.

As can be seen in Figure 6, the level probes are enclosed by a second partition 516, to separate and protect them from contact with the Raschig rings 202. The level probes 510, 512, 514 are located in an opposite comer of the water tank to the expansion pipework 106, to mitigate damage due to high flow rates of incoming water.

The purpose of the de-aeration apparatus 500 is to remove air from a closed-loop pipework system during circulation. During filling of a closed-loop pipework system, air often becomes trapped in the pipework as a result of the filling activity. Conventionally, the trapped air would be removed from the pipework system by flushing the water in the pipework system to drain. In situations where it is not desirable to flush the water to drain this presents a problem, with potentially increased levels of dissolved oxygen in the pipework system water giving rise to corrosion and operational problems.

The closed-loop pipework system de-aeration apparatus 500 receives water from a closed-loop pipework system at full, operating pressure. The water passes through the flowlimiter 502 and the soft close solenoid valve 504, and enters the water tank through the expansion pipework 106, the end section 110 of which has an enlarged diameter and outlets below the normal operating water level 108 of the water tank. By allowing the water to enter in this manner two things happen. Firstly, the close-loop pipework system water is released from full operating pressure to atmospheric pressure, allowing both dissolved and undissolved air to be liberated, as bubbles and micro-bubbles. Secondly, by introducing the water into the tank below the normal operating level of the tank, through the enlarged diameter expansion pipework, re-aspiration is minimised.

The perforated partition 402 allows the incoming water and the level probes 510, 512,

514 to be separated from Raschig rings, which enhance the removal ofthe bubbles. The water is pumped back into the closed-loop pipework system through the pump 520 and the non-return valve 522.

The controller 530 is configured to cause the solenoid valve to open, to allow water to enter the tank. The controller 530 is also configured to, when the water reaches a pre-set level, detected by the first level probe 514, cause the pump 520 to start. The controller 530 is also configured to cause the solenoid valve to shut if the water tank starts to overfill. The controller is therefore configured to control the water tank levels so that the pump does not run out of water and the tank does not overflow.

Referring to Figure 7, another embodiment ofthe invention provides a heat exchanger 600 comprising a closed-loop pipework system 610 and closed-loop pipework system deaeration apparatus 100, as described above. It will be appreciated that any ofthe closed-loop pipework system de-aeration apparatus 200, 300, 400, 500 may be used.

Referring to Figure 8, an embodiment ofthe invention provides a heat exchanger 700 comprising a closed-loop pipework system 610 and closed-loop pipework system de-aeration apparatus 500, as described above. The outlet ofthe non-return valve 522 is connected back to the closed-loop pipework system 610 via return pipework 612.

Referring to Figure 9, an embodiment ofthe invention provides closed-loop pipework system de-aeration apparatus 800 which may additionally be used for filling a closed-loop pipework system. The apparatus 800 is similar to the apparatus 500 of Figure 5, with the following modifications.

In this embodiment, the apparatus additionally comprises a 2-way valve 802 and pressure switch 806. The 2-way valve has a first outlet which connects to the expansion pipework, to deliver water into the tank 104 through the end-section 110, as described above. The 2-way valve has a second outlet which connects to an outlet pipe 804 which delivers water into the tank but ata level above the normal operating water level. The 2-way valve is configured to switch between the first outlet and the second outlet in response to a valve control signal received from the controller 530.

The pressure switch 806 has a set pressure at which the pressure switch activates; the set pressure corresponds to the pressure in the closed-loop pipework system when the system is full. The pressure switch is configured to transmit a pressure control signal to the controller 530 when the set pressure is reached within the system, indicating that the system is full.

The controller 530 is configured to transmit a valve control signal to the 2-way valve in response to receiving a pressure control signal from the pressure switch.

To fill a closed-loop pipework system, the water inlet 102 is connected to a water supply, such as a mains water system. The pressure within the closed-loop pipework system is initially less than the set pressure of the pressure switch, no pressure control signal is transmitted by the pressure switch and the 2-way valve is therefore set to the second outlet and water is delivered into the water tank 104 via the outlet pipe 804. The water pump 520 operates as described above to deliver water into the closed-loop pipework system. When the pressure within the closed-loop pipework system reaches the set pressure, the pressure switch transmits a pressure control signal to the controller, causing the controller to transmit a valve control 5 signal to the 2-way valve, to cause the 2-way valve to switch from the second outlet to the first outlet. The water inlet 102 is then decoupled from the water supply and is connected to the closed-loop pipework system. The apparatus 800 can then be operated as described above to remove any air within the water in closed-loop pipework system as a result of filling the system, and can periodically be operated to remove any air that has entered the system.

Claims

1. Closed-loop pipework system de-aeration apparatus comprising:

a water inlet adapted to receive water at operating pressure from a closed-loop pipework system;

a water tank open to atmosphere; and expansion pipework having an inlet end and an outlet end, the inlet end adapted to receive water from the water inlet and the outlet end located within the water tank at a position below a normal operating water level of the water tank, and wherein the expansion pipework comprises an end section at the outlet end, a diameter of the end section being larger than a diameter of the expansion pipework at the inlet end.

2. Closed-loop pipework system de-aeration apparatus as claimed in claim 1, wherein the diameter of the end section increases from a first end to the outlet end.

3. Closed-loop pipework system de-aeration apparatus as claimed in claim 2, wherein the end-section has a generally domed shape.

4. Closed-loop pipework system de-aeration apparatus as claimed in any preceding claim, further comprising at least one flow disrupting element provided within the water tank below the normal operating water level.

5. Closed-loop pipework system de-aeration apparatus as claimed in claim 4, wherein the at least one flow disrupting element comprises an open mesh or a plurality of Raschig rings.

6. Closed-loop pipework system de-aeration apparatus as claimed in any preceding claim, further comprising a partition provided within the water tank, the partition defining an inlet area of the water tank within which the outlet end of the expansion pipework is located, wherein the partition has a plurality of apertures provided through it connecting the inlet area to a remaining area of the water tank, the apertures being located below the normal operating water level.

7. Closed-loop pipework system de-aeration apparatus as claimed in claim 6, wherein the apertures in the partition are located higher within the water tank than the outlet end of the expansion pipework.

8. Closed-loop pipework system de-aeration apparatus as claimed in any preceding claim, further comprising a flow-limiter between the water inlet and the inlet end of the expansion pipework.

9. Closed-loop pipework system de-aeration apparatus as claimed in claim 8, wherein the water tank comprises a water outlet and further comprising a pump connected to the water outlet, wherein the pump and the flow limiter are configured to have substantially the same flow rate.

10. Closed-loop pipework system de-aeration apparatus as claimed in claim 9, further comprising:

a first level probe configured to detect a first water level within the water tank;

a second level probe configured to detect a second, lower water level within the water tank; and a controller configured to generate at least one pump control signal configured to cause the pump to run in response to the first level probe detecting the first water level and configured to cause the pump to stop in response to the second level probe detecting the second water level.

11. Closed-loop pipework system de-aeration apparatus as claimed in claim 9 or claim

10, further comprising:

a 2-way valve having a first outlet and a second outlet, the first outlet connecting the 2-way valve between the water inlet and the outlet end of the expansion pipework and the second outlet connected to an outlet pipe having an outlet end located at a position above the normal operating level of the water tank; and a pressure switch provided after the pump, the pressure switch configured to transmit a pressure control signal to the controller when the pressure within the closed-loop pipework system reaches a set pressure, and wherein the controller is configured to generate a valve control signal in response to the pressure control signal, the valve control signal configured to cause the 2-way valve to switch from the second outlet to the first outlet.

12. A heat exchanger comprising:

a closed-loop pipework system; and closed-loop pipework system de-aeration apparatus according to any preceding claim.