GB2479130A

GB2479130A - Fluid decontamination

Info

Publication number: GB2479130A
Application number: GB1005232A
Authority: GB
Inventors: Richard Geoffrey John Franklin
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-03-29
Filing date: 2010-03-29
Publication date: 2011-10-05
Also published as: GB201005232D0

Abstract

A thermal fluid decontamination apparatus comprises a decontamination vessel 2 having contaminated liquid ingress means 10 and decontaminated liquid egress means 14, and means for the removal of one or more contaminants of the liquid from the vessel by a reduced pressure in the decontamination vessel. Preferably a pressure pump 6 maintains the reduced pressure in the vessel 2 to encourage the separation of contaminants. The reduced pressure may be maintained typically between 800 and 900 mBar absolute pressure. Advantageously thermal heating fluid from a thermal fluid system is introduced into a cavity 4 of the vessel through the ingress pipe 10, which in use is arranged to be connected to a thermal fluid system such as a central heating system or a system for heating reaction ingredients in an industrial chemical process.

Description

Improvements relating to oil decontamination and method therefor

Technical field of the Invention

This invention relates to organic liquid decontamination apparatus and a method of decontaminating liquid, in particular apparatus and methods for decontaminating thermal fluid. The invention further extends to apparatus and methods for decontaminating thermal fluid in situ without the need to shut down the heating system.

Backciround to the invention Thermal fluid, otherwise known as heat transfer fluid, is used in many processes whereby prolonged periods of heating are required at constant temperatures. In particular thermal fluid is used in process heating such as cooking vessels, ovens and chemical processes, for instance as oil baths or in heating oil jackets for performing chemical reactions at elevated temperatures.

Typically in such systems and processes the thermal fluid is required to be heated to an elevated temperature and continuously pumped around a piping system at this elevated temperature.

The use of thermal fluid at such elevated temperatures has certain advantages over conventional hot water or steam-based systems. A particular advantage of thermal fluid over hot water/steam-based systems is that thermal fluid does not require the application of high pressures in order to attain elevated temperatures above 10000. High pressure equipment is relatively expensive to purchase and the equipment used is thermal fluid heating processes is generally cheaper.

Thermal fluid systems suffer from certain disadvantages over conventional water-based systems. Typical thermal fluids include minerals oils distilled from crude oil and as such are flammable materials. Common mineral oil used in thermal oil-based heating systems include BP TRANSCAL N, SHELL THERMIA B and ESSOTHERM 500, which all have auto ignition temperatures of around 35000. During prolonged heating of such mineral oils, build up of volatile materials can occur.

As volatile compounds are produced, the flashpoint of the mixture decreases, and in some cases can fall as low as around 50°C. The lower flashpoint coupled with the high operating temperatures further exacerbates the fire and/or explosion risks.

Other contaminants such as water, glycol, process fluids, etc. can also be present.

The fire and explosion risks posed by the lowering flashpoints leads to users needing to replace the entire liquid content of the system periodically to minimise problems -in a typical 8000 litre heating oil system, the cost of replacing the liquid can be in the order of tens of thousands of pounds per year.

Replacing the entire liquid content of a system can also bring the system off-line for the length of time it takes to change the liquid. The new liquid must then be heated to operating temperature, which further increases the time for which the system must be off-line.

In some industrial scale chemical reaction processes, even a short period of time off-line can lead to substantial losses in revenue.

After the degraded liquid has been removed there is also a problem in the environmentally acceptable disposal of the liquid in such large quantities.

An oil decontamination apparatus and a method of decontaminating oil are disclosed in GB-A-2 375 056, but the system described there is expensive to build and maintain. A problem is also encountered that there is a carryover of host fluid so prolonged use will affect the host system.

It is therefore an aim of preferred embodiments of the present invention to reduce at least one of the problems described above, or other problems.

Summary of the invention

According to a first aspect of the present invention there is provided a thermal fluid decontamination apparatus comprising a decontamination vessel having contaminated liquid ingress means and decontaminated liquid egress means, and wherein the apparatus further comprises means for the removal of one or more contaminants of the liquid from the vessel by a reduced pressure in the decontamination vessel.

The decontamination apparatus works on liquid phase thermal fluid systems.

A reduced pressure is below atmospheric pressure.

Suitably, the reduced pressure is between 800 mBar absolute pressure and 900 mBar absolute pressure.

Achieving the separation of the contaminants by a reduced pressure to achieve vaporisation of the component is desirable in this case because it is far cheaper and more controllable than the system described in GB 2 375 056.

The apparatus can be used to remove volatile and other contaminants.

By volatile contaminant, we include a volatile compound having a tendency to pass into the vapour state at the operating temperatures of the apparatus.

Such volatile compounds include hydrocarbons with a vapour pressure equal to or greater than 0.1mm Hg. It will be appreciated that removal of the one or more volatile contaminants of the liquid includes removal of volatile contaminants which are only partly vaporised at the operating temperature of the apparatus. When the vapour portion of the contaminant is removed, the equilibrium of the volatile contaminant shifts, forming more vapour from the remaining portion of the contaminant, which vapour can then be removed. It will be appreciated that not all of the or each contaminant may be removed.

The apparatus may include egress means from the vessel for the or each contaminant.

Suitably, the contaminated liquid ingress means comprises an ingress conduit in fluid communication between the vessel and a thermal fluid system.

Preferably the ingress conduit is arranged to deliver thermal fluid to the vessel at an elevated pressure or at an elevated temperature, for instance above ambient temperature, or both.

The apparatus preferably comprises means to adjust the flow rate of liquid to the vessel. Suitably the flow rate adjustment means of the ingress means comprises a flow valve. The flow valve may, alternatively or additionally be arranged to allow complete cessation of the flow of liquid into the vessel.

Alternatively or additionally the ingress means may comprise a separate flow shut-off valve.

Advantageously, the liquid ingress means extends into the cavity defined by the vessel.

Suitably, the vessel is a generally sealed vessel. Preferably the vessel is constructed from any suitable material which can withstand reduced pressure.

Preferably, the vessel has a volume capacity of under 20 litres, preferably under 15 litres and more preferably under 12 litres.

The decontaminated liquid egress means may comprise an egress conduit in fluid communication between the vessel and the thermal fluid system.

The egress means preferably comprises means to adjust the flow rate of liquid from the vessel. Suitably the flow rate adjustment means of the egress means comprises a flow valve. The flow valve is preferably arranged to allow complete cessation of the flow of liquid from the vessel. Alternatively or additionally the egress means may comprise a separate flow shut-off valve.

The apparatus may be arranged to operate such that liquid ingresses into the vessel under conditions wherein the or part of this liquid remains in a substantially liquid state within the vessel whereas the, or part of the or each contaminant present is in a substantially gaseous state within the vessel.

Preferably the liquid entering the vessel is at a temperature of at least 10000.

More preferably, the liquid entering the vessel is at a temperature between 120°C and 140°C.

In order to further effect conditions whereby the liquid remains in a substantially liquid state within the vessel whereas the or each contaminant present remains in a gaseous state within the vessel, the liquid ingress means preferably further comprises a restricted diameter aperture in fluid communication with the cavity formed by the vessel, such that liquid entering the vessel may be in the form of a liquid mist or spray.

Preferably the means for the egress of contaminants from the vessel comprises a contaminant egress conduit. Suitably the contaminants egress means comprises means to adjust the flow rate of contaminants from the vessel. Preferably the compound adjustment means of the compound egress means comprises a flow valve. Suitably the flow valve may, alternatively or additionally be arranged to be able to effect complete cessation of the flow of compounds from the vessel. Alternatively or additionally the contaminant egress means may comprise a separate contaminant shut-off valve.

The contaminant egress means may be connected to waste disposal means.

Preferably the waste disposal means may comprise a vessel such as a collection vessel. Suitably the contaminant egress means is connected to a contaminant liquefying means which is in turn connected to the waste disposal means. Preferably the contaminant liquefying means comprises a condenser, more preferably a water condenser.

Thus in use, contaminants passing through the contaminant egress means may pass through the condenser, and the contaminants will be condensed from substantially gaseous form to substantially liquid form within the condenser before entering the waste tank in substantially liquid form.

Suitably, the waste disposal means comprises a drainage means for draining the or each contaminant, from the waste disposal means, which drainage means may be in the form of a drainage valve.

As the liquid enters the cavity of the vessel and any contaminants are vaporised by virtue of the reduced pressure maintained in the vessel., Suitably the apparatus comprises means for adjusting the temperature inside the vessel.

Suitably the decontaminated liquid egress means comprises a liquid egress conduit in fluid communication between the vessel and the thermal fluid system. Preferably the liquid egress conduit is connected to a pump arranged to pump liquid from the vessel, through the liquid egress conduit and to the thermal fluid system. Thus the thermal fluid may be decontaminated in the decontamination vessel and returned to the thermal fluid system for use in the relevant process.

According to a second aspect of the invention there is provided a decontamination apparatus as described herein, arranged to be connected to a thermal fluid system, wherein connection is effected during normal operation of the thermal fluid system.

Thus connection is effected without the need to shut down or slow down the thermal fluid system, and thus the flow of the thermal fluid to and from the relevant process of the system can continue unhindered.

According to a third aspect of the invention there is provided a method of removing one or more contaminants from thermal fluid, the method comprising providing thermal fluid to a decontamination vessel, exposing thermal fluid to conditions in which contaminants can be separated, separating at least some of the contaminants from the liquid removal of one or more contaminants of the liquid from the vessel by a reduced pressure in the decontamination vessel and returning the decontaminated oil to a thermal fluid system.

The method may comprise determining the level of contamination of a thermal fluid by monitoring the amount of contaminated and decontaminated liquid.

The method may comprise monitoring the amount of contaminants in the liquid.

The method may comprise causing at least part of the liquid in a thermal fluid system to pass through a region where contaminants are separated from the liquid. The method may comprise selectively causing the liquid to pass through that region.

The method may comprise selectively attaching and detaching means to cause separation of contaminants from contaminated liquid to a thermal fluid system whilst the thermal fluid system is operating.

Preferably the method further comprises the steps of condensing the or each gaseous contaminant into a liquid state after removal from the decontamination apparatus.

The present invention includes any continuation of features or limitations as herein referred to including a method of removing contaminated compounds from thermal fluid when using apparatus as herein referred to.

Brief description of the drawings

For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings, in which: Figure 1 illustrates a vertical cross-section of a preferred embodiment of the thermal fluid decontamination apparatus of the invention; and Figure 2 is a functional flow diagram illustrating a method of operation of the apparatus of Figure 1.

Description of the preferred embodiment

With reference to Figure 1 of the accompanying drawings, a preferred thermal fluid decontamination apparatus comprises a decontamination vessel 2 in the form of a closed tank. The decontamination vessel comprises means to adjust the pressure of the cavity 4 within the vessel 2, by way of pressure pump 6, and also includes means to adjust the temperature of the cavity 4 within the vessel 2, by way of a thermostat 8 connected to suitable heating and/or cooling apparatus (not shown).

The pressure pump 6 maintains a reduced pressure in the vessel 2 to encourage the separation of contaminants. The reduced pressure is maintained typically between 800 mBar absolute pressure and 900 mBar absolute pressure.

Thermal heating fluid from a thermal fluid system is introduced into the cavity 4 of the vessel 2 through a contaminated oil ingress means in the form of liquid ingress pipe 10, which in use is arranged to be connected to a thermal fluid system (not shown) such as a central heating system or a system for heating reaction ingredients in an industrial chemical process. The liquid ingress pipe includes liquid flow rate adjustment means in the form of flow valve 12. The flow valve 12 can be operated to adjust the flow rate of liquid entering the vessel 2, and if necessary can be oriented to completely stop the flow of liquid down the liquid ingress pipe 10 into the vessel 2.

The vessel includes decontaminated liquid egress means in the form of a liquid egress pipe 14. The liquid egress pipe 14 is arranged in use to carry decontaminated liquid from the vessel 2 back to the thermal fluid system which the decontamination apparatus is connected to. Included on the liquid egress pipe 14 is a liquid egress flow adjustment means in the form of a flow valve 16.

The flow valve 16 can be operated to adjust the flow rate of decontaminated liquid leaving the vessel 2 via the oil egress pipe 14, back to the thermal fluid system. The flow valve 16 can also be operated to completely stop the flow of liquid from the vessel 2 down the liquid egress pipe 14. Also connected to the liquid egress pipe 14 is a pump 18. The pump 18 operates to draw decontaminated liquid from the vessel 2 down the liquid egress pipe 14 and to the thermal fluid system. The operation of the pump 18 can be altered to increase or decrease the rate of flow of liquid from the vessel 2 down the liquid egress pipe 14, and this may be operated separately to or in conjunction with the flow valve 16.

In order to remove any gaseous chemicals from the cavity 4 of the vessel 2, such as gaseous contaminants removed from the liquid, the inert gas, or mixtures thereof, a removed compound egress means is provided in the form of gas egress pipe 20, connected to the vessel 2. The gas egress pipe 20 is provided with a means to adjust the rate of flow of gas from the vessel 2, in the form of flow valve 22, which can also be operated to completely stop the flow of gas from the vessel 2 down the gas egress pipe 20.

The end of the gas egress pipe 20, is connected to a gas condensing means in the form of a water-cooled condenser 24. The condenser 24 is connected to a collection vessel 26 via an intermediate pipe 28. The collection vessel 26, in use, collects the condensed contaminants which pass out from the condenser 24 and through intermediate pipe 28.

The decontamination vessel 2 includes a number of subsidiary features for controlling and monitoring the process of decontamination within the cavity of the vessel 2. A liquid sample egress outlet 30 is provided, which in use enables samples of liquid, which have passed into the cavity 4 of the vessel 2, to be transported to diagnostic equipment (not shown) in order to determine the state of contamination of the liquid. Suitable diagnostic equipment for determining contamination of the liquid could include flashpoint determination apparatus, viscosity determination apparatus, vapour pressure determination apparatus, auto ignition temperature determination apparatus and such like.

After the sample has been tested, it can be discarded or returned to the vessel 2 through a sample ingress inlet (not shown).

Additionally a thermostat 40 monitors the temperature of the egressing liquid.

A pressure gauge 42 monitors the pressure in the vessel 2. A programmable logic controller 44 is used to control and monitor the operation of the system.

A manual key start 46 and emergency stop 48 are also provided.

A typical operation of the decontamination apparatus illustrated in Figure 1 will now be described with reference to the functional flow diagram in Figure 2 of the accompanying drawings.

In step 100, the decontamination apparatus is detachably secured directly to a thermal fluid system (not shown) via the liquid ingress pipe 10 and liquid egress pipe 14. The apparatus is designed so that the thermal fluid system does not need to be shut down during connection or removal of the apparatus, and during operation of the apparatus. The liquid ingress pipe 10 and liquid egress pipe 14 can be connected to the thermal liquid system by any suitable means including to outlets and inlets already present on the thermal fluid system.

In step 102, after the decontamination apparatus has been connected, contaminated liquid from the thermal fluid system is allowed to flow through the liquid ingress pipe 10, by opening the flow valve 12 on the liquid ingress pipe to achieve the desired flow rate. In typical thermal fluid systems the liquid coming from the system will be at a temperature of about 2000C3000C. The liquid flows through the liquid ingress pipe 10 into the heat exchanger 50 in which the liquid temperature is reduced to 120°C-140°C until it reaches the distal end of the liquid ingress pipe at which is located a spray nozzle 11 of the ingress pipe 10. The spray nozzle 11 of the liquid ingress pipe 10 comprises an opening within the cavity 4 which allows liquid to be sprayed into the cavity 4. The spray nozzle is formed such that oil leaving the liquid ingress pipe 10 is sprayed into the cavity in liquid form. As the liquid is sprayed into the cavity 4 into a reduced pressure environment contaminants present in the liquid become vaporised, evaporating off from the liquid. The decontaminated liquid then drops to the bottom of the decontamination vessel 2. The pressure pump 6 and thermostat 8 can also be used to optimise conditions for the evaporation of contaminants from the liquid within the vessel 2. Generally the temperature of the ingressing liquid will be kept constant and the reduced pressure adjusted to fine tune the fractionation of contaminants.

At this point the vessel 2 will contain vapour in the form of gaseous contaminants. These contaminants may leave the vessel by way of the gas egress pipe 24. The flow valve 22 on the gas egress pipe 20 is opened to allow any vapour within the cavity 4 of the vessel 2 to leave.

In step 104, all the gases leaving the vessel 2 through the gas egress pipe 20 travel through a water condenser 24. The water condenser 24 acts to cool down the gases and liquefy the gaseous compounds passing through. The resultant liquid and any inert gas present, pass through the condenser 24, through intermediate pipe 38 and into the collection vessel 26. When the collection vessel 26 becomes full the waste can be drained into a suitable disposal container through drain pipe 52.

In step 106, the liquid which collects at the bottom of the vessel 2 is recycled back to the thermal fluid system by way of a liquid egress pipe 14, and a pump 18. The flow valve 16 on the oil egress pipe 14 is opened to allow liquid from the vessel 2 to enter the liquid egress pipe 14. The pump 18 is activated to provide suction which assists in the removal of liquid from the vessel 2, down the liquid egress pipe 14. The liquid egress pipe 14 is connected at one end to the thermal fluid system, and the liquid moving down the liquid egress pipe 14 is eventually returned to the system.

During or prior to operation of the apparatus the decontaminated liquid which collects at the bottom of the vessel 2 maybe sampled, for instance to see if it is necessary to separate out the contaminants. A sample of liquid can be withdrawn through the sample egress outlet 40, using the flow valve 42 on the outlet to control the flow. The liquid can then be tested to determine any relevant characteristics such as flashpoint, auto ignition temperature, and dissolved gases, before being returned to the vessel 2, if desired, through sample ingress outlet 44, controlled by the flow valve 46 on the outlet.

It will be appreciated that the apparatus can be used continuously to decontaminate thermal fluid within a system, or be used to clean liquid then be disconnected from the system once the decontamination process is complete, to be reconnected at a later time, if desired.

For ease of use the entire apparatus is mounted on a stage (not shown), which is easily transportable on a suitable vehicle.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s).

The invention extend to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

CLAIMS1. A thermal fluid decontamination apparatus comprising a decontamination vessel having contaminated liquid ingress means and decontaminated liquid egress means, and wherein the apparatus further comprises means for the removal of one or more contaminants of the liquid from the vessel by a reduced pressure in the decontamination vessel.
2. The thermal fluid decontamination apparatus of claim 1, wherein the reduced pressure is between 800 mBar absolute pressure and 900 mBar absolute pressure.
3. The thermal fluid decontamination apparatus of claim 1 or claim 2, wherein the apparatus includes egress means from the vessel for the or each contaminant.
4. The thermal fluid decontamination apparatus of claim 3, wherein the contaminated liquid ingress means comprises an ingress conduit in fluid (\J communication between the vessel and a thermal fluid system.
5. The thermal fluid decontamination apparatus of claim 4, wherein the ingress conduit is arranged to deliver thermal fluid to the vessel at an elevated pressure or at an elevated temperature, for instance above ambient temperature, or both.
6. The thermal fluid decontamination apparatus of any preceding claims, wherein the apparatus comprises means to adjust the flow rate of liquid to the vessel.
7. The thermal fluid decontamination apparatus of claim 6, wherein the flow rate adjustment means of the ingress means comprises a flow valve.
8. The thermal fluid decontamination apparatus of claim 6, wherein the flow valve is arranged to allow complete cessation of the flow of liquid into the vessel.
9. The thermal fluid decontamination apparatus of claim 3, wherein the liquid ingress means extends into the cavity defined by the vessel.
10. The thermal fluid decontamination apparatus of any preceding claim, wherein the vessel is a generally sealed vessel.
11. The thermal fluid decontamination apparatus of any preceding claim, wherein the vessel is constructed from any suitable material which can withstand reduced pressure.
12. The thermal fluid decontamination apparatus of any preceding claim, Q wherein the vessel has a volume capacity of under 20 litres, preferably under 15 litres and more preferably under 12 litres. Co

C\J
13. The thermal fluid decontamination apparatus of claim 1, wherein the decontaminated liquid egress means comprises an egress conduit in fluid communication between the vessel and the thermal fluid system.
14. The thermal fluid decontamination apparatus of any preceding claim, wherein the egress means comprises means to adjust the flow rate of liquid from the vessel.
15. The thermal fluid decontamination apparatus of claim 14, wherein the flow rate adjustment means of the egress means comprises a flow valve.
16. The thermal fluid decontamination apparatus of claim 15, wherein the flow valve is arranged to allow complete cessation of the flow of liquid from the vessel.
17. The thermal fluid decontamination apparatus of claim 15, wherein the egress means may comprise a separate flow shut-off valve.
18. The thermal fluid decontamination apparatus of any preceding claim, wherein the apparatus is arranged to operate such that liquid ingresses into the vessel under conditions wherein the or part of this liquid remains in a substantially liquid state within the vessel whereas the, or part of the or each contaminant present is in a substantially gaseous state within the vessel.
19. The thermal fluid decontamination apparatus of claim 18, wherein the liquid entering the vessel is at a temperature of at least 10000.
20. The thermal fluid decontamination apparatus of claim 18, wherein the liquid entering the vessel is at a temperature between 120°C and 140°C.
21. The thermal fluid decontamination apparatus of any preceding claim, CO wherein the liquid ingress means further comprises a restricted diameter C\I aperture in fluid communication with the cavity formed by the vessel, such that liquid entering the vessel may be in the form of a liquid mist or spray.
22. The thermal fluid decontamination apparatus of any preceding claim, wherein the means for the egress of contaminants from the vessel comprises a contaminant egress conduit.
23. The thermal fluid decontamination apparatus of claim 22, wherein the contaminants egress means comprises means to adjust the flow rate of contaminants from the vessel.
24. The thermal fluid decontamination apparatus of claim 23, wherein the compound adjustment means of the compound egress means comprises a flow valve.
25. The thermal fluid decontamination apparatus of claim 24, wherein the flow valve may, alternatively or additionally be arranged to be able to effect complete cessation of the flow of compounds from the vessel.
26. The thermal fluid decontamination apparatus of claim 22, wherein the contaminant egress means comprises a separate contaminant shut-off valve.
27. The thermal fluid decontamination apparatus of any preceding claim, wherein the contaminant egress means is connected to waste disposal means.
28. The thermal fluid decontamination apparatus of claim 27, wherein the waste disposal means may comprise a vessel such as a collection Q vessel.

CO
29. The thermal fluid decontamination apparatus of claim 27 or claim 28, C\J wherein the contaminant egress means is connected to a contaminant liquefying means which is in turn connected to the waste disposal means.
30. The thermal fluid decontamination apparatus of claim 29, wherein the contaminant liquefying means comprises a condenser.
31. The thermal fluid decontamination apparatus of claims 27 to 30, wherein the waste disposal means comprises a drainage means for draining the or each contaminant, from the waste disposal means.
32. The thermal fluid decontamination apparatus of any preceding claim, wherein the apparatus comprises means for adjusting the temperature inside the vessel.
33. The thermal fluid decontamination apparatus of any preceding claim, wherein the decontaminated liquid egress means comprises a liquid egress conduit in fluid communication between the vessel and the thermal fluid system.
34. The thermal fluid decontamination apparatus of claim 33, wherein the liquid egress conduit is connected to a pump arranged to pump liquid from the vessel, through the liquid egress conduit and to the thermal fluid system.
35. A decontamination apparatus according to any one of the preceding claims, arranged to be connected to a thermal fluid system, wherein connection is effected during normal operation of the thermal fluid system.

Q
36. A method of removing one or more contaminants from thermal fluid, the method comprising providing thermal fluid to a decontamination vessel, CO exposing thermal fluid to conditions in which contaminants can be C\J separated, separating at least some of the contaminants from the liquid removal of one or more contaminants of the liquid from the vessel by a reduced pressure in the decontamination vessel and returning the decontaminated oil to a thermal fluid system.
37. The method of removing one or more contaminants from thermal fluid of claim 36, wherein the method comprises determining the level of contamination of a thermal fluid by monitoring the amount of contaminated and decontaminated liquid.
38. The method of removing one or more contaminants from thermal fluid of claim 37, wherein the method comprises monitoring the amount of contaminants in the liquid.
39. The method of removing one or more contaminants from thermal fluid of claims 36 to 38, wherein the method comprises causing at least part of the liquid in a thermal fluid system to pass through a region where contaminants are separated from the liquid.
40. The method of removing one or more contaminants from thermal fluid of claim 39, wherein the method comprises selectively causing the liquid to pass through that region.
41. The method of removing one or more contaminants from thermal fluid of claims 36 to 40, wherein the method comprises selectively attaching and detaching means to cause separation of contaminants from contaminated liquid to a thermal fluid system whilst the thermal fluid system is Q operating.

Q
42. The method of removing one or more contaminants from thermal fluid of claim 36 to 41, wherein the method further comprises the steps of CO condensing the or each gaseous contaminant into a liquid state after C\J removal from the decontamination apparatus.
43. A thermal fluid decontamination apparatus substantially as described herein, with reference to the accompanying drawings.
44. A method of removing one or more contaminants from a thermal fluid substantially as described herein, with reference to the accompanying drawings.