FIELD

The present teachings relate to a flow diverter. The present teachings also relate to a waste heat recovery system including a flow diverter.

BACKGROUND

There are a number of systems in which a flow of fluid is required to be diverted through an approximate right angle. On such example is in a waste heat recovery system for an industrial gas turbine or diesel engine. Typically, these systems include a waste heat recovery unit (WHRU) with a vertically arranged flow path connected to a horizontally arranged exhaust outlet of the turbine/engine.

Typical flow diverter arrangements include a conduit formed of a section of pipe which is fabricated from a series of straight pipe segments angled relative to each other (often called a "lobster back elbow"). Such conduits are configured to form a right angle between an inlet direction and an outlet direction. A disadvantage of this arrangement is that fluid is not spread evenly as it flows through the conduit. For example, there is a faster flow of fluid on the outer side of the bend in the conduit than on the inner side, which results in higher component loadings along this side of the bend. If the fluid is a hot, high pressure and/or fast flowing fluid (e.g. gas turbine exhaust gases), this could lead to the damage of the conduit on this outer side of the bend that would require additional engineering design and attendant cost to mitigate.

In addition, such a conduit adds height to an apparatus it is placed above/below and/or adds width to an apparatus it is placed next to. This may be undesirable for space- constrained environments, such as in a gas turbine waste heat recovery system for an oil platform.

Furthermore, such a conduit is unsuitable for supporting a load (e.g. the weight of a WHRU). Therefore, typical flow diverter arrangements require a frame to support the conduit and/or any apparatus connected thereto, which add to cost and complexity.

Finally, such conduits are often required to convert a rectangular inlet to a circular outlet, which further adds to the complexity of the fabrication.

The present invention seeks to overcome, or at least mitigate, one or more problems of the prior art. SUMMARY OF THE INVENTION

According to a first aspect of the invention, a flow diverter for diverting a flow of fluid through an approximate right angle is provided, the flow diverter comprising: one or more inlets each defining an inlet direction; an outlet defining an outlet direction substantially orthogonal to the or each inlet direction; and a concentrically arranged plenum chamber and diversion region; wherein the diversion region comprises a plurality of vanes each defining a height extending substantially in the outlet direction, wherein the plurality of vanes are arranged generally radially to define a plurality of corresponding segments of the diversion region and to direct a proportion of fluid entering the plenum chamber from the inlet into said plurality of segments of the diversion region; and wherein the diversion region further comprises a plurality of guide surfaces arranged in the segments to guide the fluid in the segments from a flow generally in the inlet direction to a flow generally in the outlet direction.

Such a plenum chamber and diversion region both facilitate an even spread of fluid leaving the outlet. This is particularly beneficial when the fluid is a high-velocity fluid (e.g. exhaust gases) since it reduces the formation of relatively higher and lower velocity regions in components downstream of the flow diverter (e.g. a waste heat recovery unit) which could lead to reduced performance of such components.

In addition, such a flow diverter configuration can achieve an even flow spread with a smaller height than typical flow diverter arrangements which require a casing with a lobster back elbow or the like. Having a reduced height is particularly beneficial when the flow diverter is used in applications with constrained space requirements (e.g. a waste heat recovery system on an oil platform).

Furthermore, prior art flow diverters including a lobster back elbow or the like require an additional frame to support a load placed thereon (e.g. the weight of a waste heat recovery unit). In contrast, the plenum chamber of the subject flow diverter may be suitable for bearing a load, which removes the need for such an additional supporting frame.

It will also be understood that an even spread of fluid leaving the outlet minimises a pressure drop across the flow diverter. In exemplary embodiments, the or each inlet direction is a horizontal direction and the outlet direction is a vertical direction.

Such a configuration makes the flow diverter particularly suitable for use in an industrial gas turbine waste energy recovery system, which typically include horizontally arranged exhaust pipes and a vertically arranged waste heat recovery unit.

In exemplary embodiments, the or each inlet is of rectangular cross section and the outlet is of circular cross section.

Such a configuration makes the flow diverter particularly suitable for use in an industrial gas turbine waste energy recovery system, which typically include exhaust pipes of rectangular cross section and a waste heat recovery unit of cylindrical construction.

In exemplary embodiments, a longitudinal axis of the or each inlet intersects a centre point of the concentrically arranged plenum chamber and diversion region.

Having a longitudinal axis of the or each inlet intersecting a centre point of the concentrically arranged plenum chamber and diversion region (i.e. the inlet(s) not being offset from the plenum chamber and diversion region) encourages an even spread of fluid around the plenum chamber and diversion region in two directions (i.e. clockwise and anticlockwise) rather than a swirling flow in one direction. This improves the flow spread of fluid leaving the diversion region.

In exemplary embodiments, the diversion region is located concentrically within the plenum chamber.

The purpose of the plenum chamber is to encourage even spread of fluid prior to leaving the outlet. The vanes and guide surfaces also encourage even spread of fluid leaving the diversion region. Therefore, locating the diversion region concentrically within the plenum chamber improves the flow spreading capabilities of the plenum chamber.

In exemplary embodiments, one or more of the plurality of vanes defines an at least partially curved profile.

Having an at least partially curved profile may help to direct fluid (e.g. exhaust gases) into the plurality of segments of the diversion region more easily. In exemplary embodiments, each of the plurality of vanes comprises a radially inner end connected to a common central point; optionally, wherein each of the plurality of vanes further comprises a radially outer end, wherein one or more of the radially outer ends defines a curved profile.

The radially outer ends of the vanes define the inlets to the segments of the diversion region. Therefore, having a curved profile at the radially outer end helps to capture fluid (e.g. exhaust gases) flowing around the diversion region within the corresponding segment. This improves the flow spread of fluid leaving the diversion region.

In exemplary embodiments, the flow diverter comprises a single inlet and wherein the or each curved profile is curved towards the inlet; or wherein the flow diverter comprises a plurality of inlets and wherein the or each curved profile is curved towards the nearest inlet.

Having a vane profile curved towards the inlet allows the vanes to more effectively intersect a flow of fluid (e.g. exhaust gases) and capture a portion of the flow within the corresponding segment. This improves the flow spread of fluid leaving the diversion region.

In exemplary embodiments, the inlet defines a longitudinal axis, wherein a first group of the plurality of vanes is arranged on a first side of the longitudinal axis and a second group of the plurality of vanes is arranged on a second side of the longitudinal axis, wherein one or more of the vanes of the first group defines a profile at least partially curved towards the inlet in a first direction (e.g. clockwise), and wherein one or more of the vanes of the second group defines a profile at least partially curved towards the inlet in a second direction opposite to the first direction (e.g. anti-clockwise).

Fluid (e.g. exhaust gases) flowing from the inlet around the diversion region will effectively be split into two flow paths on either side of the longitudinal axis. These flow paths will be in opposite directions (e.g. a first clockwise flow path, and a second anti-clockwise flow path). Therefore, the or each curved profile of the first group curving in an opposite direction to the or each profile of the second group ensures that the vanes can more effectively intersect the two fluid flows around the diverter and capture them within the corresponding segments. This improves the flow spread of fluid leaving the diversion region.

In exemplary embodiments, each of the vanes of the first group defines a profile at least partially curved towards the inlet in a first direction (e.g. clockwise), and wherein each of the vanes of the second group defines a profile at least partially curved towards the inlet in a second direction opposite to the first direction (e.g. anti-clockwise).

Each of the vanes of the first and second groups being curved (e.g. as opposed to only a subset of the vanes of the first and second groups being curved) allows the advantages of the curved profile outlined above to be provided around the circumference of the diversion region. This ensures that the vanes can more effectively intersect the flow of fluid (e.g. exhaust gases) around the diverter and capture them within the corresponding segments, which improves the flow spread of fluid leaving the diversion region.

In exemplary embodiments, the flow diverter comprises a plurality of inlets each defining a respective inlet direction, wherein the inlet directions of the plurality of inlets are coplanar and substantially orthogonal to the outlet direction of the outlet; optionally, wherein the flow diverter comprises two inlets; optionally, wherein the inlets are distributed around a circumference of the flow diverter.

In exemplary embodiments, the or each vane defining an at least partially curved profile comprises one or more ribs arranged on an inner circumference of a curved portion of the vane.

Such inner ribs offers a structural support to the curved portion. Where the curved portion is at a radially outer end of the vane, this is the end which is likely to receive the greatest forces due to exhaust gases flowing faster at this end.

In exemplary embodiments, each guide surface comprises a ramp extending from an outer radial end to an inner radial end; optionally, wherein a gradient of the ramp increases from the outer radial end to the inner radial end.

Having a ramp extending from the outer radial end to the inner radial end provides facilitates a smooth transition in a flow of fluid from the inlet(s) to the outlet, since fluid entering the diversion region along the inlet direction(s) does not have to suddenly change direction to the outlet direction orthogonal to the inlet direction(s).

Having a ramp gradient which increases from the outer radial end to the inner radial end further facilitates a smooth transition in a flow of fluid from the inlet(s) to the outlet, since fluid changes direction gradually as it is directed along the guide surface. In exemplary embodiments, the diversion region is located concentrically within the plenum chamber, wherein the flow diverter further comprises a housing comprising a substantially cylindrical portion defining said plenum chamber; optionally, wherein the substantially cylindrical portion comprises one or more apertures for input of fluid to the plenum chamber.

Having a plenum chamber defined by a substantially cylindrical portion of the housing encourages a flow of fluid within the plenum chamber to move around any formations located within the plenum chamber (e.g. the vanes and guide surface of the diversion formation) more easily than other shapes (e.g. cuboid chambers).

Having one or more aperture in the substantially cylindrical portion provides a means for introducing fluid to the plenum chamber (e.g. in one or more horizontal inlet directions).

In exemplary embodiments, the or each aperture comprises a first edge at a first position along a circumference of the substantially cylindrical portion, and a second edge at a second position along a circumference of the substantially cylindrical portion, and wherein the distance between the first edge and the second edge is greater than 50% of the diameter of the substantially cylindrical portion; optionally, wherein the distance between the first edge and the second edge is greater than 70% of the diameter of the substantially cylindrical portion.

Having a distance between the first and second edges of the aperture(s) (i.e. an aperture width) greater than 50% of the diameter of the substantially cylindrical portion encourages a flow of fluid (e.g. exhaust gases) entering the plenum chamber to spread around the circumference of the plenum chamber. This facilitates an even flow of fluid into all of the radial segments of the diversion region when the diversion region is provided within the plenum chamber.

In exemplary embodiments, the housing further comprises one or more inlet portions each comprising a first end configured for connection to a conduit (e.g. an exhaust pipe) and a second end connected to a respective aperture of the substantially cylindrical portion, and wherein the or each inlet portion tapers outwardly from the first end to the second end.

The inlet portion(s) tapering outwardly from the first end (where fluid enters the inlet portion from a conduit) to the second end (where fluid flows from the inlet portion into the plenum chamber) allows the first end to be appropriately shaped and sized for standard conduit geometry (e.g. standard exhaust pipe sizes) whilst having a larger width plenum chamber, which increases the flow spreading capabilities of the plenum chamber.

Furthermore, this tapered inlet portion shape also encourages a flow of fluid (e.g. exhaust gases) to spread outwardly as it flows along the inlet portion prior to entering the plenum chamber. This encourages a flow of fluid to spread around the circumference of the plenum chamber, which facilitates an even flow of fluid into all of the radial segments of the diversion region when the diversion region is provided within the plenum chamber.

In exemplary embodiments, the housing further comprises one or more inlet portions each comprising a first end configured for connection to a conduit (e.g. an exhaust pipe) and a second end connected to a respective aperture of the substantially cylindrical portion, wherein the first end defines a rectangular opening.

Industrial gas turbine exhaust pipes are typically of rectangular cross section. Therefore, having a rectangular opening at the first end of the inlet portion(s) makes the flow diverter suitable for attachment to a typical gas turbine exhaust pipe.

In exemplary embodiments, the or each inlet portion comprises four straight walls extending from the first end of said inlet portion to the second end of said inlet portion.

Having four straight walls provides a simple means of manufacturing the inlet portion(s). Furthermore, the combination of such an inlet portion being connected to the aperture of the substantially cylindrical portion (which defines a circular outlet) provides a simple means of converting from a rectangular conduit (e.g. exhaust gas pipe) to a circular outlet (e.g. for connection to a cylindrical waste heat recovery unit (WHRU)). In contrast, prior art apparatus for converting from a rectangular inlet to a circular outlet typically require a complex shaped conduit which tapers from a rectangular cross section to a circular cross section, which is more complex to manufacture.

In exemplary embodiments, the flow diverter further comprises an annular flange extending radially inwards from the substantially cylindrical portion of the housing and defining a central opening, wherein the annular flange is positioned downstream of the diversion region in the outlet direction and is connected to each of the plurality of vanes of the diversion region, thereby separating the plenum chamber into an upstream portion containing the diversion region and a downstream portion after the diversion region; optionally, wherein the annular flange is connected to each of the plurality of vanes of the diversion region via an annular skirt. Positioning the annular flange downstream of the diversion region in the outlet direction (e.g. above the diversion region when the flow diverter is arranged to divert flow from a horizontal inlet direction to a vertically upwards outlet direction) and connecting the annular flange to the plurality of vanes ensures that a flow of fluid (e.g. exhaust gases) entering at the inlet has to travel via the diversion region and through the central opening to the outlet. In other words, this prevents fluid from travelling along an outer circumference of the plenum chamber to the outlet (i.e. it prevents fluid from bypassing the diversion region). This improves the flow spread of fluid leaving the outlet.

Having the annular flange connected to the vanes via an annular skirt (i.e. the annular flange being spaced apart from the vanes in the outlet direction) increases the volume of the upstream portion of the plenum chamber over embodiments where the annular flange is connected directly to the vanes. This improves the spread of fluid within the plenum chamber prior to being directed through the diversion region, and thus improves the flow spread of fluid leaving the outlet.

In exemplary embodiments, the outlet is configured for connection to a waste heat recovery unit; optionally, wherein the size and shape of the outlet corresponds to a crosssection of a waste heat recovery unit.

Typical the diameter of a waste heat recovery unit (WHRU) is wider than the diameter of the piping in a standard flow diverter apparatus. This necessitates a tapered connecting component between the flow diverter and the WHRU, which adds height, cost and complexity to the assembly. In contrast, by having the size and shape of the outlet correspond to a cross-section of a WHRU, such a tapered connecting component is no longer required, which reduces the height and number of components in the assembly.

In exemplary embodiments, the flow diverter further comprises a dome proximal the outlet, wherein the dome is arranged concentrically within the outlet; optionally, wherein the dome is connected to the or a housing of the flow diverter by a plurality of circumferentially-distributed arms.

Having a dome arranged concentrically within the outlet provides a further formation for encouraging a flow of fluid (e.g. exhaust gases) to spread evenly towards a flow path downstream of the flow diverter (e.g. an annular flow chamber of a waste heat recovery unit). Having a plurality of circumferentially-distributed arms allows the dome to be supported around its circumference. Having a plurality of circumferentially-distributed arms also allows a WHRU or components thereof (e.g. a heat exchanger coil) to be supported radially inwardly from the housing of the flow diverter. Having a plurality of arms also reduces the thickness of each arm required to support the dome over other arrangements (e.g. those with just one arm), which reduces the impact of the arms on a flow of fluid (e.g. exhaust gases) passing around the dome. Furthermore, since the arms are circumferentially distributed, any effect of the arms on a flow of fluid passing around the dome would be the same around the circumference of the flow path, which encourages an even circumferential spread of flow.

In exemplary embodiments, the dome comprises an upstream side defining a convex surface; optionally, wherein the dome further comprises a downstream side defining a connection formation for connection to an inner tubular member of a waste heat recovery unit.

Having a convex surface on an upstream side of the dome encourages a flow of fluid (e.g. exhaust gases) to spread radially outwards prior to leaving the outlet. This is advantageous for typical waste heat recovery units (WHRUs) which include an inner tubular member (often called a "bullet") and an annular flow chamber therearound, since the convex surface directs fluid leaving the outlet of the flow diverter towards the annular flow chamber of the WHRU.

Having such a connection formation (e.g. a flanged rim, annular groove/recess etc) allows the dome to form a bottom end of an inner tubular member (i.e. a "bullet" as it is known in the field). This may also help to locate a waste heat recovery unit on top of the flow diverter (e.g. via engagement with the connection formation) and may also help to support the weight of the inner tubular member when the flow diverter is placed below the waste heat recovery unit.

In exemplary embodiments, the flow diverter is configured to be load-bearing; optionally, wherein the flow diverter is configured to support a load greater than 1 tonne.

The flow diverter being load bearing means that an additional frame or the like is not necessary for supporting a component located on top of the flow diverter (e.g. a waste heat recovery unit). In exemplary embodiments, the flow diverter comprises an inner housing and an outer housing surrounding the inner housing, wherein the outer housing is configured to be load bearing; optionally, wherein a profile of the outer housing is complementary to a profile of the inner housing; optionally, wherein the outer housing comprises one or more supporting ribs configured to increase its load-bearing capacity.

Having an inner housing and an outer housing allows insulation to be placed between the inner and outer housing for thermal insulation and noise attenuation.

According to a second aspect of the invention, a waste heat recovery system is provided, the waste heat recovery system comprising a waste heat recovery unit connected to the outlet of a flow diverter according to the first aspect of the invention; optionally, wherein the waste heat recovery unit is provided on top of the flow diverter and is supported by the flow diverter; or optionally, wherein the flow diverter is provided on top of the waste heat recovery unit.

Typically, waste heat recovery units are arranged vertically, whereas exhaust pipes (e.g. a gas turbine exhaust pipe) are arranged horizontally. Therefore, having a waste heat recovery system with a flow diverter according to the first aspect of the invention (i.e. a flow diverter for diverting a flow of fluid through an approximate right angle) makes the advantages described above particularly applicable to this type of application.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure la is an isometric view of a waste heat recovery unit coupled at a bottom end to a prior art flow diverter;

Figure lb is an isometric view of a waste heat recovery unit coupled at a bottom end to a flow diverter according to an embodiment;

Figures 2a and 2b are side views of the apparatus of Figures la and lb respectively;

Figures 3a and 3b are schematic cross sections of the apparatus of Figures la and lb respectively;

Figure 4a is a cross section of a waste heat recovery unit coupled at a top end to a prior art flow diverter; Figure 4b is a cross section of a waste heat recovery unit coupled at a top end to a flow diverter according to an embodiment;

Figure 5a and 5b are plan and side cross sections showing fluid flow paths through a flow diverter according to an embodiment;

Figure 6 is an isometric view of a diversion region of the flow diverter of Figures 5a and 5b;

Figure 7 is an isometric view of the flow diverter of Figures 5a and 5b;

Figure 8 is a vertical cross section through the flow diverter of Figure 7 along a longitudinal axis of the inlet;

Figures 9a and 9b are isometric views of a lower and upper portion of the flow diverter of Figure 7;

Figures 10a and 10b are plan and side cross sections showing flow rates through the flow diverter of Figures 5a to 9b;

Figures Ila and 11b are isometric and plan views of a flow diverter having two inlets, according to an embodiment;

Figures 12a and 12b are plan and side cross sections showing flow rates through the flow diverter of Figures Ila and 11b, when the inlet fluid flow is split 50:50 between the two inlets; and

Figures 13a and 13b are plan and side cross sections showing flow rates through the flow diverter of Figures Ila and 11b, when the inlet fluid flow is split 75:25 between the two inlets.

DETAILED DESCRIPTION

Referring firstly to Figures la, 2a and 3a, a prior art waste heat recovery system is indicated at 10. The waste heat recovery system 10 includes a waste heat recovery unit (WHRU) 12 and a flow diverter 14 coupled to a lower end 16 of the WHRU 12. In alternative prior art systems, the flow diverter 14 may be coupled to an upper end 18 of the WHRU 12 (e.g. as depicted in Figure 4a).

The WHRU 12 is of a known type (e.g. of the kind described in EP1088194) and includes one or more heat transfer elements 20 (e.g. coiled pipes) for transfer of heat from fluid flowing through the WHRU 12 to fluid in the heat transfer elements 20. For example, heat from exhaust gases flowing through the WHRU 12 may be transferred to fluid within the heat transfer elements 20 for use in steam generation or as a process fluid on an oil platform or the like. The WHRU 12 may also include an axial sliding inner sleeve 21 to control a flow of fluid through concentrically arranged bypass duct 23 and heat exchange duct 25 containing the heat transfer elements 20 (as shown in Figures 4a and 4b and described in EP1088194), or some other flow diversion arrangement such as rotating dampers.

The flow diverter 14 of the prior art includes an inlet 22 and an outlet 24 connected via a series of angled pipe segments 26 arranged to form a "lobster back elbow" (i.e. an approximately curved conduit). The inlet 22 is tapered from a square cross-section to a round cross-section for connecting square and round conduits (e.g. for connecting a square gas turbine exhaust pipe to a round WHRU 12). The outlet 24 is tapered radially outwards for connecting a conduit to a wider diameter apparatus (e.g. for connecting a series of angled pipe segments 26 to a relatively wider WHRU 12).

Such a prior art flow diverter 14 is unsuitable for supporting a load (e.g. the weight of the WHRU 12). Therefore an additional frame 28 is provided to support the WHRU 12 and the flow diverter 14.

Referring now to Figures lb, 2b, 3b and 4b, a waste heat recovery system including a flow diverter 114 according to an embodiment is indicated at 110. Components of the waste heat recovery system 110 described so far in relation to the prior art Figures la, 2a, 3a and 4a are given the same numerals with the prefix "1". As will be described in more detail below, the flow diverter 14 includes an inlet 122 defining an inlet direction (e.g. a horizontal direction in the views of Figures 2b, 3b and 4b), and an outlet 124 defining an outlet direction substantially orthogonal to the inlet direction (e.g. a vertical direction in the views of Figures 2b, 3b and 4b).

As will be described in more detail below, the flow diverter 114 is considerably shorter than the prior art flow diverter 14, which reduces the height of the waste heat recovery system 110 over the prior art system 10. Furthermore, in the embodiment illustrated in Figures lb, 2b and 3b, the size and shape of the outlet 124 corresponds to a cross-section of the WHRU 112. Specifically, the diameter of the outlet 124 of the flow diverter 114 is approximately equal to the diameter of the WHRU 112, as will be described in more detail below. This removes the need for the flow diverter outlet 124 to taper radially outwards as in the prior art, which reduces the height of the waste heat recovery system 110 further. As will also be described in more detail below, the flow diverter 114 is also configured to be load-bearing (e.g. configured to support a load greater than 1 tonne, such as the weight of the WHRU 112), which removes the need for the frame 28 of the prior art flow diverter 14.

While the flow diverter 114 is connected to a WHRU 12 in Figures lb, 2b, 3b and 4b, it may also be used with other types of apparatus such as once-through steam generators (OTSGs), HVAC systems, emission/noise abatement systems etc.

Referring now to Figures 5a to 6, the flow diverter 114 includes a concentrically arranged plenum chamber 130 and diversion region 132, as will be described in more detail below. The diversion region 132 includes a plurality of vanes 134 each defining a height extending substantially in the outlet direction (e.g. extending vertically in the view of Figure 5a). The plurality of vanes 134 are arranged generally radially to define a plurality of corresponding segments 136 of the diversion region 132. The plurality of vanes 134 are configured to direct a proportion of fluid entering the plenum chamber 130 from the inlet 122 into the plurality of segments 136 (e.g. as shown by the dotted lines of Figure 5a). The diversion region 32 also includes a plurality of guide surfaces 138 arranged in the segments 136 to guide the fluid in the segments 136 from a flow generally in the inlet direction to a flow generally in the outlet direction (e.g. as shown by the dotted lines of Figure 5b).

Such a plenum chamber 130 and diversion region 132 both facilitate an even spread of fluid leaving the outlet 124. This is particularly beneficial when the fluid is a high-velocity fluid (e.g. exhaust gases) since it reduces the formation of relatively higher and lower velocity regions in components downstream of the flow diverter 114 (e.g. the WHRU 112) which could lead to reduced performance of such components. In addition, such configuration can achieve an even flow spread with a smaller height than typical flow diverter arrangements (e.g. flow diverter 14 of Figures la, 2a, 3a and 4a). Having a reduced height is particularly beneficial when the flow diverter is used in applications with constrained space requirements (e.g. a waste heat recovery system on an offshore oil platform).

The diversion region 132 is arranged concentrically within the plenum chamber 130. The purpose of the plenum chamber 130 is to encourage even spread of fluid prior to leaving the outlet 124. The vanes 134 and guide surfaces 138 also encourage even spread of fluid leaving the diversion region 132. Therefore, locating the diversion region 132 concentrically within the plenum chamber 130 improves the flow spreading capabilities of the plenum chamber 130. Referring to Figures 5a and 6, each of the plurality of vanes 134 has a radially inner end 140 connected to a common central point 142. Each of the vanes 134 also includes a radially outer end 144. Furthermore, one or more of the plurality of vanes 134 defines an at least partially curved profile, as will be described in more detail below. This helps to direct fluid (e.g. exhaust gases) into the plurality of segments 136 of the diversion region 132 more evenly.

In the illustrated embodiment, the longitudinal axis of the inlet 122 intersects a centre point 142 of the concentrically arranged plenum chamber 130 and diversion region 132. In other words, the inlet is not offset from the plenum chamber 130 and diversion region 132. This encourages an even spread of fluid around the plenum chamber 130 and diversion region 132 in two directions (i.e. clockwise and anticlockwise), which improves the flow spread of fluid leaving the diversion region 132. In alternative embodiments, the longitudinal axis of the inlet 122 is offset from the centre point 140 so that fluid entering the plenum chamber 130 flows in a swirling direction around the diversion region 132.

In the illustrated embodiment, each of the vanes 134 which are not aligned with a longitudinal axis of the inlet 122 defines a curved profile. In alternative embodiments, only some of the vanes 134 which are not aligned with the longitudinal axis of the inlet 122 define a curved profile. In alternative embodiments, one or more of the vanes 134 are aligned with a longitudinal axis of the inlet 122 and also define a curved profile.

In the illustrated embodiment, each of the curved profiles is defined by one of the radially outer ends 144 of the vanes 134. Such radially outer ends 144 define inlets to the segments 136 of the diversion region 132. Therefore, having a curved profile at the radially outer ends 144 helps to capture fluid (e.g. exhaust gases) flowing around the diversion region 132 within the corresponding segment 136, which improves the flow spread amongst segments 136. In alternative embodiments, the curved profiles may be defined by an entire vane 134 (e.g. at least some of the vanes 134 may be curved along their entire length).

In alternative embodiments the vanes 134 may be formed with curves having multiple radii of curvature (compound curves) or may be formed with radially outer ends that are planar, but angled with respect to the radially inner ends by virtue of one or more distinct edges or creases and intermediate planar faces to form a quasi-curve. In alternative embodiments the vanes 134 may project radially outwardly by different amounts. For example the vanes 134 furthest from the inlet 122 may project radially outwardly further than those closer to the inlet.

In the illustrated embodiment, each of the curved profiles of the vanes 134 is curved towards the inlet 122, as will be described in more detail below. This allows the vanes 134 to more effectively intersect a flow of fluid around the diversion region 132 (e.g. exhaust gases) and capture a portion of the flow within the corresponding segment 136. This improves the flow spread amongst segments 136. In alternative embodiments, one or more of the curved profiles may be curved away from the inlet 122 (e.g. the vane(s) 134 closest to the inlet 122 may be curved away to direct fluid around the diversion region 132 to segments 136 further from the inlet 122).

A first group 146 of the plurality of vanes 134 is arranged on a first side of the longitudinal axis of the inlet 122, and a second group 148 of the plurality of vanes 134 is arranged on a second side of the longitudinal axis of the inlet 122. In the illustrated embodiment, each of the vanes 134 of the first group 146 has a radially outer end 144 which is curved towards the inlet in a first direction (e.g. clockwise in Figure 5a) and each of the vanes 134 of the second group 148 has a radially outer end 144 which is curved towards the inlet in a second direction opposite to the first direction (e.g. anti-clockwise in Figure 5a). This ensures that the vanes 134 can effectively intersect two fluid flows around the diverter region 132 and capture them within the corresponding segments 136. This improves the flow spread amongst the segments 136. In alternative embodiments, only a subset of the vanes 134 in the first group 146 is curved towards the inlet 122 in the first direction and/or only a subset of vanes 134 in the second group 148 is curved towards the inlet 122 in the second direction.

Referring now to Figure 6. Each of the vanes 134 having an at least partially curved profile includes a rib 150 arranged on an inner circumference of the curved portion of the vane 134 (e.g. on the radially outer ends 144 in the illustrated embodiment). This rib 150 offers a structural support to the curved portions, which are likely to receive the greatest forces due to exhaust gases flowing faster at the radially outer ends 144. In alternative embodiments, a plurality of ribs 150 are arranged on the inner and/or an outer circumference of the curved portion of the vane 134.

In the illustrated embodiment, each rib 150 also extends beyond the curved portion of the vane 134 to an adjacent straight portion of the vane 134. This further strengthens the vane 134. In alternative embodiments, such ribs 150 may be provided along all or any portion (including curved and/or straight portions) of some or all of the vanes 134.

Referring now to figures 5b and 6, each guide surface 138 is a ramp extending from an outer radial end 152 to an inner radial end 154. In the illustrated embodiment, a gradient of the ramp increases from the outer radial end 154 to the inner radial end 156. This facilitates a smooth transition in a flow of fluid from the inlet 122 to the outlet 124, since fluid changes direction gradually as it is directed along the guide surfaces 138. In alternative embodiment, the ramp may have a constant gradient along its length.

In the illustrated embodiment, the diversion region 132 is provided as a separate component for locating within a plenum chamber 130 or other chamber (e.g. via screws, bolts or the like). In this way, the diversion region 132 is suitable for positioning within any type of flow diverter housing. In alternative embodiments, the diversion region 132 may be integral with the plenum chamber 130.

Referring now to Figures 7 to 9b, the flow diverter 122 includes a housing 156 having a substantially cylindrical portion 158 defining said plenum chamber 130. Such a shape encourages a flow of fluid within the plenum chamber 130 to move around the diversion region 132 more easily than other shapes (e.g. cuboid chambers), which improves flow spread.

As will be described in more detail below, the substantially cylindrical portion 158 includes an aperture 160 for input of fluid to the plenum chamber 130. This provides a means for introducing fluid to the plenum chamber 130 (e.g. in the inlet direction).

The aperture 160 has a first edge 162 at a first position along a circumference of the substantially cylindrical portion 158, and a second edge 164 at a second position along a circumference of the substantially cylindrical portion 158. In the illustrated embodiment, the distance between the first edge 162 and the second edge 164 (i.e. the width of the aperture 160) is greater than 70% of the diameter of the substantially cylindrical portion 158. This encourages a flow of fluid (e.g. exhaust gases) entering the plenum chamber 130 to spread around the circumference of the plenum chamber 130, which facilitates an even spread of fluid into the segments 136 of the diversion region 132. In alternative embodiments, a suitable flow spread may achieved with a short distance between the first edge 162 and the second edge 164 (i.e. a shorter aperture width), for example, 50% of the diameter of the substantially cylindrical portion. The housing 156 also includes an inlet portion 166 having a first end 168 configured for connection to a conduit (e.g. an exhaust duct), and a second end 170 connected to the aperture 160 of the substantially cylindrical portion 158. In the illustrated embodiment, the inlet portion 166 tapers outwardly from the first end 168 to the second end 170. This allows the first end 168 to be appropriately shaped and sized for standard conduit geometry (e.g. standard exhaust duct sizes) whilst having a larger width plenum chamber 130, which increases the flow spreading capabilities of the plenum chamber 130. Furthermore, this tapered inlet portion 166 also encourages a flow of fluid (e.g. exhaust gases) to spread outwardly as it flows along the inlet portion 166 prior to entering the plenum chamber 130. This encourages a flow of fluid to spread around the circumference of the plenum chamber 130, which facilitates an even flow of fluid into all of the segments 136 of the diversion region 132. In alternative embodiments, the inlet portion 166 may not be tapered (i.e. the width of the first end 168 may be the same as the width of the second end 170).

In the illustrated embodiment, the first end 168 of the inlet portion 166 defines a rectangular opening 172. Industrial gas turbine exhaust ducts are typically of rectangular cross section. Therefore, having a rectangular opening 172 makes the flow diverter 114 suitable for attachment to a typical gas turbine exhaust pipe. In alternative embodiments, the first end 168 may define a non-rectangular opening (e.g. a round opening) for connection to alternative conduit types.

In the illustrated embodiment, the outlet 124 is of circular cross section. This makes the flow diverter suitable for connection to cylindrical apparatus, such the WHRU 112. In alternative embodiments, the outlet 124 may be of polygonal or irregular shape for connection to a suitable apparatus.

In the illustrated embodiment, the inlet portion 166 has four straight walls 174 extending from the first end 168 of the inlet portion 166 to the second end 170 of the inlet portion 166. The combination of such an inlet portion 166 being connected to the aperture 160 of the substantially cylindrical portion 158 (which defines a circular outlet) provides a simple means of converting from a rectangular conduit (e.g. exhaust gas duct) to a circular outlet (e.g. for connection to a cylindrical WHRU 112). This removes the need for the rectangular- to-round tapered inlet 22 of the prior art (as shown in Figure la), which defines a complex shape that is difficult to manufacture.

Referring now to Figures 5b, 8 and 9b, the flow diverter 114 includes an annular flange 176 extending radially inwards from the substantially cylindrical portion 158 of the housing 156. The annular flange 176 defines a central opening 178. The annular flange 176 is positioned downstream of the diversion region 132 in the outlet direction (i.e. vertically upwards in the illustrated embodiment) and is connected to each of the plurality of vanes 134 of the diversion region 132. The separates the plenum chamber 130 into an upstream portion 180 containing the diversion region 132 (i.e. a region below the annular flange 176) and a downstream portion 182 after the diversion region 132 (i.e. a region above the annular flange 176). This arrangement ensures that a flow of fluid (e.g. exhaust gases) entering at the inlet 122 has to travel via the diversion region 132 and through the central opening 178 to the outlet 124. In other words, this prevents fluid from travelling along an outer circumference of the plenum chamber 130 to the outlet 124 (i.e. it prevents fluid from bypassing the diversion region 132). This improves the flow spread of fluid leaving the outlet 124.

The annular flange 176 defines a surface which is substantially parallel to the inlet direction (i.e. arranged horizontally in the illustrated embodiment). In alternative embodiments, annular flange 176 may be angled (e.g. defining a frustoconical surface) and/or define an undulating surface.

In the illustrated embodiment, the annular flange 176 is connected to the each of the plurality of vanes 134 of the diversion region 132 via an annular skirt 184. This increases the volume of the upstream portion 180 of the plenum chamber 130, which improves the spread of fluid within the plenum chamber 130 prior to being directed through the diversion region 132, and thus improves the flow spread of fluid leaving the outlet 124. In alternative embodiments, the annular flange 176 is connected directly to each of the vanes 134 (i.e. the annular skirt 184 may be omitted). In alternative embodiments, the annular skirt 184 extends close to the vanes 134 but is not in contact with the vanes 134. In other words, the annular skirt 184 may have a free end (e.g. the bottom end of the annular skirt 184 if the flow diverter 114 is oriented as in the illustrated embodiment) which is spaced apart from the plurality of vanes 134 towards the outlet 124. In alternative embodiments, the annular skirt 184 may be omitted, and the central opening 178 of the annular flange 176 may be positioned close to the vanes 134 but not in contact with the vanes 134 (i.e. the central opening 178 may be spaced apart from the plurality of vanes 134 towards the outlet 124).

In the illustrated embodiment, the annular skirt 184 is substantially cylindrical (i.e. it has a constant diameter along its length). In alternative embodiments, the annular skirt 184 may be frustoconical (e.g. having a diameter increasing or decreasing along its length). In alternative embodiments, the annular skirt 184 may define an undulating and/or irregular surface of varying diameter/width.

Referring now to Figures 7 and 8, the outlet 124 is configured for connection to the WHRU 112 (i.e. the size and shape of the outlet 124 corresponds to a cross-section of the WHRU 112). In addition, the flow diverter 114 also includes a dome 186 proximal the outlet 124 and arranged concentrically within the outlet 124. This provides a further formation for encouraging a flow of fluid (e.g. exhaust gases) to spread evenly towards a flow path downstream of the flow diverter 114 (e.g. an annular flow chamber of the WHRU 112).

In the illustrated embodiment, the dome 186 is connected to the housing 156 of the flow diverter 114 by a plurality of circumferentially-distributed arms 188. This allows the dome 186 to be supported around its circumference and reduces the thickness of each arm 188 required to support the dome 186 over other arrangements (e.g. those with just one arm 188). This reduces the impact of the arms 188 on a flow of fluid (e.g. exhaust gases) passing around the dome 186, and encourages an even circumferential spread of flow. In alternative embodiments, only one arm 188 may be provided to connect the dome. In alternative embodiments, the dome 186 may be connected to the housing 156 via a mesh or the like.

In certain embodiments the arms 188 may also be utilised to support the heat transfer element 120.

In the illustrated embodiment, the arms 188 extend radially with respect to the dome 186. In other words, the arms extend from the dome 186 to the cylindrical portion 158 of the housing 156. In alternative embodiments, the arms 188 may extend axially (e.g. to the annular flange 176) or at an angle (e.g. to the joint between the annular flange 176 and the cylindrical portion 158 of the housing 156). In yet further embodiments, the arms 188 may extend axially or at an angle beyond the outlet 124 so that the dome 186 extends beyond the outlet 124 (e.g. into a downstream apparatus such as a WHRU 112).

In the illustrated embodiment, the dome 186 has an upstream side defining a convex surface 190. This encourages a flow of fluid (e.g. exhaust gases) to spread radially outwards prior to leaving the outlet 124. This is advantageous for typical WHRUs 112 which include an inner tubular member 192 (often called a "bullet") and an annular flow chamber 123, 125 therearound. The dome also has a downstream side defining a connection formation 194 for connection to an inner tubular member 192 of the WHRU 112. In the illustrated embodiment, the connection formation 194 includes a rim of the dome 186. In alternative embodiments, the connection formation 194 may include other formations in addition or instead of the dome rim (e.g. flange extending from the dome 186 or an annular groove in the rim of the dome 186). In the illustrated embodiment, the dome 186 forms a bottom end of the inner tubular member 192 when the WHRU 112 and flow diverter 114 are assembled. In alternative embodiments, the connection formation 194 of the dome 186 may be a concave surface for receiving an end of a fully formed inner tubular member 192.

The dome 186 with suitable connection formation 194 helps to support the weight of the inner tubular member 192 when the flow diverter 114 is placed below a WHRU 112 (e.g. as in Figures lb, 2b, and 3b). However, in alternative embodiments, the dome 186 may be omitted entirely and the inner tubular member 192 may be supported only by the WHRU 112.

Referring again to figures 7 to 9b, the housing 156 includes an inner portion 196 and an outer portion 198 surrounding the inner portion 196. Such an arrangement defines a space between the inner portion 196 and the outer portion 196, which may be filled with heat and/or sound insulation material, for example.

In the illustrated embodiment, a profile of the outer portion 198 is complementary to a profile of the inner portion 196. Specifically, the outer portion 198 is substantially the same shape as the inner portion 196, but is of larger size. In alternative embodiments, the outer portion 198 may be of different shape to the inner portion 196.

As mentioned above, the flow diverter 114 is configured to be load bearing. In particular, the outer portion 198 is configured to be load-bearing. For example, the outer portion includes a plurality of supporting ribs 1100 configured to increase its load-bearing capacity. In alternative embodiments, the inner portion 196 may be configured to be load-bearing (e.g. it may include supporting ribs 1100) in addition to, or instead of the outer portion 198.

As illustrated in Figures 10a and 10b, when fluid is input to the flow diverter 114 via the inlet 122, the flow of fluid is distributed evenly around the circumference of the flow diverter 114. This then leads to an even distribution of flow through the WHRU 112 mounted to the flow diverter 114. Referring now to Figures Ila and 11b, a waste heat recovery system including a flow diverter 214 according to a further embodiment is indicated at 210. Corresponding components between the flow diverter 114 of Figures 5a to 10b are labelled with the prefix "2", and only differences are discussed.

The flow diverter 214 includes two inlets 222a and 222b each defining a respective inlet direction. The inlet directions of the inlets 222a, 222b are co-planar. In other words, the inlet direction of each inlet 222a, 222b is substantially orthogonal to the outlet direction of the outlet 224 of the flow diverter 214 (not shown). Having two inlets 222a, 222b allows a single flow diverter 214 to be used to connect multiple fluid flows (e.g. coming from multiple pieces of equipment, such as industrial gas turbines) to a single WHRU 212.

In the illustrated embodiment, the two inlets 222a, 222b are distributed around a circumference of the flow diverter 214, so that an obtuse angle is formed between the inlet directions of the two inlets 222a, 222b. In alternative embodiments, the two inlets are positioned directly opposite each other (i.e. so that the inlet directions of the two inlets 222a, 222b are substantially parallel). In alternative embodiments, the two inlets 222a, 222b may be positioned closer together, so that a right angle or acute angle is formed between the inlet directions of the two inlets 222a, 222b.

It will be understood that in alternative embodiments, the flow diverter includes three or more inlets. In such embodiments, the inlets are appropriately dispersed around the circumference of the flow diverter. For example, the inlets may be distributed evenly or unevenly around the circumference, depending on the requirements of the overall waste heat recovery system (e.g. dictated by the position of equipment attached thereto).

As illustrated in Figures 12a and 12b, when fluid is input to the flow diverter 214 via the inlets 222a, 222b in an approximately 50:50 split (i.e. 50% of the total inlet flow flowing through each inlet 222a, 222b), the flow of fluid is distributed evenly around the circumference of the flow diverter 214. This then leads to an even distribution of flow through the WHRU 212 mounted to the flow diverter 214.

Similarly, as illustrated in Figures 13a and 13b, when fluid is input to the flow diverter 214 via the inlets 222a, 222b in an approximately 75:25 split (i.e. 75% of the total inlet flow flowing through the first inlet 222a and 25% of the total inlet flow flowing through the second inlet 222b), the flow of fluid is distributed evenly around the circumference of the flow diverter 214. This then leads to an even distribution of flow through the WHRU 212 mounted to the flow diverter 214. It will be understood that the ratio of the fluid flowing through inlets 222a, 222b may vary from the ratios illustrated in Figures 12a to 13b, whilst still maintaining an even distribution of flow around the circumference of the flow diverter 214. In exemplary embodiments, flow through each inlet 222a, 222b is at least 10% of the overall flow. In exemplary embodiments, either of the flows through inlets 222a, 222b can be shut off entirely (e.g. when a minimum flow rate of 10% of the overall flow rate cannot be achieved).

It will also be understood that while Figures 12a to 13b illustrate inlets 222a, 222b with respective inlet directions at an obtuse angle to each other, an even spread of fluid would be achieved regardless of where the inlets 222a, 222b are positioned. For example, an even spread of fluid would also be achieved in embodiments where the inlets 222a, 222b are provided opposite each other, or in embodiments where the inlets 222a, 222b have respective inlet directions at a right angle or acute angle to each other.

It will be understood that in embodiments with more than one inlet, some or all of the vanes of the diversion region will be straight (rather than having a curved profile at the outer end 144, as illustrated in Figure 6). In such embodiments, removal of the curved profiles of some or all of the vanes results in a more even spread of fluid around the diversion region. In the embodiment illustrated in Figures 12a to 13b, all of the vanes of the diversion region are straight (i.e. there are no curved profiles at the outer ends of the vanes, in contrast to the vanes illustrated in Figure 6). In alternative embodiments, the outer ends of the vanes may be curved towards the closest inlet.

It will be appreciated that various changes or modifications can be made without departing from the scope of the teachings as defined in the appended claims. For example: the flow diverter 114 may be coupled to a different type of apparatus, such as; the flow diverter 114 may be coupled to a different type of WHRU 112 than depicted in the figures, or may be coupled to a different type of apparatus altogether (e.g. a HVAC, or emissions abatement component); the inlet 122 may be non-rectangular and the outlet 124 may be non-circular; two or more flow diverters 114 may be used in tandem to divert flow through two or more right angles; the flow diverter 114 may be provided within a frame to support a load (e.g. WHRU 112 weight) greater than the load-bearing capability of the flow diverter 114; the vanes 134 may be of different shape or configuration (e.g. curved along the entire length, angled with respect to the outlet direction etc.); the guide surfaces 138 may be of different size or shape (e.g. the distance between the outer radial end 154 and inner radial end 156 of the guide surfaces 138 may be shorter than depicted in the figures); the plenum chamber 130 may be non-cylindrical; the annular flange 176 and/or annular skirt 184 may be of different shape or configuration or may be omitted entirely; and the dome 186 may be of different shape or configuration or may be omitted entirely.