Field of the Invention The invention relates to heat recovery system for recovering heat from an autoclave or oven.

Background to the Invention In the use of autoclaves and ovens, for example in the manufacture of composite materials, high temperatures are required, typically over 300°C. When the autoclave or oven has been heated to the required temperature for the required period, it is often vented at a known rate to reduce the temperature and pressure. Usually the vented gas is released into the atmosphere. In such a system, the energy taken to heat the gas to such a high temperature is wasted as the heat is vented to the atmosphere. Therefore, when repeated cycles are undertaken, the systems become energy inefficient

Summary of the Invention Accordingly, the present invention is directed to an autoclave and/or oven heat storage system, the heat storage system comprising an inlet connected in fluid communication to a control feed, wherein: the control feed is in fluid communication with a plurality of storage vessels;

the control feed is arranged to direct fluid from the inlet to the storage vessels; and wherein the storage vessels are in fluid communication with at least one outlet;

wherein the system comprises uplift means to increase the temperature of fluid contained therein.

Storing the vented heat from an autoclave and/or oven allows one to reintroduce that stored heat back into an autoclave or oven later on, thereby reducing energy losses.

Additionally, because of the uplift means, where the fluid is below a required temperature, it can be heated up to that required temperature, which requires less energy than heating ambient temperature fluid to the same required temperature. Therefore, the system is able to reduce the energy usage of an autoclave or oven arrangement by storing and re-using heated gas. Alternatively, the heat may be used elsewhere rather than being used in the autoclave and/or oven.

The use of a plurality of storage vessels allows for the storage of fluid at different temperatures, or temperature ranges, so that it can be used or uplifted according to the requirements on the system. The control feed is able to direct the fluid to the relevant storage vessel in order that it is stored correctly prior to being reused.

Preferably, the uplift means is provided at a position between the control feed and the end of the outlet distal from the at least one storage vessel to which the outlet is connected, and, more preferably, the uplift means is provided in the at least one storage vessel to heat the fluid therein. Whilst the uplift means can be arranged anywhere from the inlet of the hot fluid into the storage system to the exit from the storage system, a convenient and efficient location for such uplift means is in the storage vessel. Such an arrangement allows for the stored fluid to be heated to a predetermined temperature and that temperature may be maintained by topping up the temperature, where necessary. By holding the fluid in the storage vessel, losses involved in moving the fluid to another location can be reduced. Other locations for the uplift means include, but are not limited to, the outlet from the heat storage system or adjacent either the entrance to or the exit from the heat storage vessel. This may be undertaken through a system wherein the fluid is passed into narrow diameter conduits and heated before being passed back to a common, larger diameter conduit.

Advantageously, the uplift means to increase the temperature of the fluid comprises a heat pump. This provides a relatively efficient source of heat for the system.

Preferably, a temperature sensor is provided in either the inlet and/or the control feed to monitor the temperature of the fluid therein. Monitoring the fluid temperature allows the system to determine to where the fluid should be directed. The temperature may be monitored at the inlet, the control feed or both in order to determine the correct location to which it should be sent.

It is advantageous that the control feed is provided with valves to direct the fluid from the inlet to a particular storage vessel according to the temperature of the fluid. The use of valves enables the system to direct the fluid in a simple manner. The valves may be automated or manual according to the requirement of a particular system.

In one arrangement a central processing unit is provided to receive the signal from the temperature sensor and control the valves to direct the fluid to the particular storage vessel. The use of a central processing unit allows for the system to be automated and for the temperatures to be monitored and fluid directed quickly and efficiently.

It is preferable that each storage vessel is provided with a temperature sensor to monitor the temperature of fluid contained therein. Providing a temperature sensor in each storage vessel allows one to determine whether the fluid therein needs heating and/or whether it is suitable for use in a particular application. The system may pass fluid from one vessel to another should it be more efficient to move the fluid rather man attempt to maintain it at a particular temperature. Furthermore, it may be necessary to vent the vessel should the temperature therein become too high and the temperature sensor allows for such a safety system to be employed.

In one arrangement, the outlet is a common outlet to which all of the storage vessels are connected. Alternatively, a plurality of outlets are provided. The storage vessels may be connected to individual outlets or to one or more shared outlets. The single outlet may be preferable where the system is connected to a single autoclave or oven, whilst a plurality of outlets may be desirable where a plurality of autoclaves and/or ovens are connected to the system.

The invention extends to an arrangement comprising a heat storage system according to any preceding claim and at least one autoclave and/or oven connected to the inlet of the heat storage system. It is preferable that a plurality of autoclaves and/or ovens are connected to the heat storage system. This allows a single heat storage system to be employed for several autoclaves and/or ovens, which may assist in distributing heat where required rather than storing it for extended periods. Therefore, the heat recovered from one device may be used in another device sooner than waiting for the next cycle of the first device.

The invention further extends to a method of storing heat from one or more autoclaves and/or ovens comprising the steps of:

providing one or more autoclaves and/or ovens connected to the inlet of a heat storage system in accordance the present invention;

directing fluid from the at least one autoclave and/or oven into the inlet of the heat storage system;

monitoring the temperature of the fluid entering the inlet;

directing the fluid to a storage vessel of the heat storage system according to its temperature.

The method provides a way to recover the heat from an autoclave or oven that would normally be released into the atmosphere and for it to be stored in vessels until it may be needed again. The heated fluid can be separated into the temperature ranges and directed to a suitable storage vessel, wherein it can be heated and/or stored.

Preferably, the vessel to which the fluid is directed is chosen in accordance with a threshold value such that fluid is directed to a first storage vessel and then when the temperature of the incoming fluid drops below a predetermined temperature, the fluid is directed to a second storage vessel. The control feed of the present invention directs the fluid to an appropriate location.

It is advantageous that the volume and/or pressure of the fluid stored in the storage vessels is monitored to ensure that the pressure within the vessel remains below a predetermined threshold value. The amount of fluid and the characteristics of that fluid may be monitored to ensure that the vessels are not overfilled or over heated. Where one vessel may be close to being overfilled, the fluid may be directed to a different vessel containing lower temperature fluid, which may be used to uplift the temperature of the lower fluid, thereby reducing the input energy required to uplift the fluid.

In one arrangement, the heated fluid is directed from the autoclave and/or oven to the inlet of the heat storage system at a predetermined rate, in accordance with the curing process therein, and the control feed of the heat storage system directs the arriving fluid accordingly depending upon the temperature of the fluid. By employing the system in accordance with a predetermined and known rate, the system can be set to predict or anticipate the heat coming from the autoclave or oven and can be prepared accordingly. As such, it might be that where a particular vessel is full, or close to being full, the system can either mix the fluid with cooler fluid and direct it to another vessel or direct part of the fluid to another vessel or location to reduce heat losses.

The present invention also extends to a method of supplying heat to an autoclave or oven from a heat storage system, comprising the steps of:

providing a heat storage system according to the present invention and connecting an outlet of the heat storage system to an autoclave or oven, wherein the heat storage system comprises a temperature sensor in its outlet; and

determining the temperature and flow rate requirements of the autoclave or oven and providing heated fluid from a storage vessel of the heat storage system at the temperature required by the autoclave and at the required flow rate.

The present invention allows the stored heated fluid to be used in the heating of an autoclave or oven, thereby reducing the need for the device to heat fluid from a lower temperature. This makes the system more efficient and requires less energy to be used in getting the autoclave or oven up to an operational temperature.

In such a system it is advantageous that the method comprises a first phase wherein the autoclave or oven takes heated fluid from the heat storage system in preference to heating the fluid itself.

Preferably, the method comprises a second phase wherein the internal heating system of the autoclave or oven is activated in parallel with supplying heated fluid from the heat storage system.

Additionally, the method may comprise a third phase wherein the supply of fluid from the heat storage system is halted and the autoclave or oven heats itself. This allows for a situation wherein the fluid provided by the heat storage system is at a temperature lower than that required by the autoclave or oven. Therefore, heat supply from the storage system is halted and the autoclave or oven takes over to prevent cold fluid being provided, which may decrease the efficiency of the system.

The invention extends to an autoclave or oven having an internal chamber, the autoclave or oven being connected to an external heated fluid source to provide heated fluid to the internal chamber of the autoclave or oven, wherein the fluid provided at a temperature above ambient temperature. In such an arrangement it may be particularly advantageous that the fluid supplied to the autoclave or oven is heated in the external source prior to entering into the internal chamber of the autoclave or oven. Whilst it is traditional to heat the- fluid in an autoclave within the internal chamber, it may be advantageous to provide the heated fluid from an external source. This is particularly advantageous where the external heating may be undertaken in a more efficient manner, for example, wherein it has been captured and stored.

Brief Description of the Drawing An embodiment of the invention will now be described, by way of example only, and with reference to the accompanying drawing, in which Figure 1 is a diagram showing an embodiment of the present invention. Detailed Description of Exemplary Embodiments

Figure 1 shows a system 10 comprising an inlet conduit 12 that is connected to three storage vessels 14, 16 and 18 via respective conduit connections 12a, 12b and 12c.

Valves (not shown) are positioned between the inlet conduit 12 and the storage vessels 14, 16 and 18 to allow or prevent fluid communication between the inlet conduit 12 and the storage vessels 14, 16 and 18.

Each of the storage vessels 14, 16 and 18 are connected to an outlet conduit 20 via conduit connections 20a, 20b and 20c, with these conduit connections being provided with valves to allow or prevent fluid communication between the storage vessels 14, 16 and 18 and the outlet conduit 20. The valves and the conduit connections 12a, 12b and 12c constitute a control feed to control the feed of heated fluid to the required location. The inlet conduit 12 and the outlet conduit 20 are both connected to an autoclave 22. One of the storage vessels 14 is provided with uplift means in the form of a heat pump 24. The heat pump 24 is arranged to provide heat to fluid within vessel 14. All of the vessels 14, 16 and 18 comprise sensors, for example temperature and pressure sensors, to monitor the fluid therein. The inlet conduit 12 and the outlet conduit 20 are each provided with valves (not shown) at their ends to allow and prevent flow of fluid into and out of the system 10 when not required.

A central processing unit 26 is connected to, among other things, a temperature sensor in the inlet conduit 12 to monitor the temperature of the fluid therein, the valves in the inlet conduit 12 and the outlet conduit 20, the sensors in the storage vessels 14, 16, and 18, and the heat pump 24. In use, heated fluid from autoclave 22 is vented into the inlet conduit 12 of the system 10. The temperature of the incoming fluid is monitored by the temperature sensor and the central processing unit 26 directs the fluid into one of the three storage vessels 14, 16 and 18 according to its temperature. Fluid having the highest temperature is directed into a first storage vessel 16 from the inlet conduit 12 via the conduit connection 12b. The central processing unit 26 continues to monitor the temperature of the fluid as it enters the conduit and, as the temperature of the fluid entering the inlet conduit 12 decreases, after a time a threshold is crossed that triggers redirection of the fluid to a different storage vessel. When the threshold is crossed, the central processing unit 26 triggers to closure of the valve in the connection conduit 12b and the opening of a second valve 12c. The heated fluid is thus directed into storage vessel 18. Again the temperature of the fluid in the inlet conduit is monitored and when a second threshold is crossed by the declining temperature of the fluid, the valve in connection conduit 12c is closed and that in connection conduit 12a is opened. The fluid then passes into storage vessel 14.

The fluid entering into storage vessel 14 is at a significantly lower temperature than that in storage vessel 16 and the temperature is monitored by the sensors connected to the respective storage vessels. To be of additionaly benefit, the cooler fluid in storage vessel 14 is heated using the heat pump 24. Therefore, the central processing unit 26 triggers the activation of the heat pump 24 and the temperature of the fluid therein is heated to a predetermined level. Once the level has been reached, the central processing unit 26 deactivates the heat pump 24.

When the autoclave 22 enters another cycle, the heat storage system 10 enters a first stage wherein heat from the storage vessels 14, 16 and 18 is provided to the internal chamber of the autoclave 22 via the outlet conduit 20. The valves in the connection conduits 20a, 20b and 20c are opened and closed according to the needs of the autoclave 22. The heating requirements within the autoclave are provided to the central processing unit 26 and heated fluid is provided as required. Often, this will initially involve providing fluid from the coolest storage vessel containing the coolest fluid. Depending on the demands of the autoclave 22, the coolest fluid may require cooling further to reach the required temperature. As the temperature of the fluid required by the autoclave increases, the vessel containing the next coolest fluid is opened to allow for hotter fluid to be provided to the autoclave 22. The fluid from two vessels may be mixed to reach a particular required temperature. When the temperature required by the autoclave exceeds the temperature of a storage vessel the valve to that storage vessel is closed to prevent that fluid from entering the outlet conduit 22.

As the temperature of fluid required by the autoclave 22 increases subsequent storage vessels provide hotter fluid to the autoclave. In some circumstances, the level of heat required by the autoclave may exceed the temperature provided by the heat storage system 10. In such a situation, a second stage of heating the autoclave is employed that involves either the temperature of the fluid within the storage vessel to which the heat pump 24 is connected being increased further, or the autoclave 22 heating system is engaged. The autoclave heating system may heat the fluid provided from the outlet conduit 20, or it may provide heated fluid to the internal chamber separately from the heat storage system 10. Thus, a combination of the autoclave 20 and the heated fluid from the heat storage system 10 is employed in the autoclave 20. Should heated fluid be required that is above that provided by the heat storage system, a third stage may be engaged, wherein the outlet conduit 20 is closed and the autoclave operates as it would without the heat storage system 10, thereby heating the fluid internally itself. By providing pre-heated fluid, the autoclave 22 becomes more efficient. This is because either the autoclave does not need to heat the fluid at all, or the autoclave is heating fluid that is already above ambient temperature, thereby requiring less energy to heat to the required level. A temperature sensor may be provided in the outlet conduit to monitor any losses from the vessel(s) to the end of the outlet

The storage vessels are provided with safety measures to allow venting of fluid should the pressure within the vessel(s) become too high.

More than one storage vessel may be provided with heat uplift means and it may be desirable to provide each storage vessel with heat uplift means. It should be noted that the heat uplift means may be shared between vessels so that one heat pump is employed to heat the fluid in two vessels.