Improvements to waste heat recovery units

Abstract

A waste heat recovery unit includes a duct for hot gas. The duct is divided into first, second and third adjacent and parallel channels each with an inlet and an outlet. A heat exchanger is located in each of the first and third channels. The second channel is located between the first and third channels and provides a bypass channel. A damper system is operable to selectively open and close the inlets of the three channels. This provides a more compact waste heat recovery unit configuration which is more straightforward to manufacture and maintain.

1 - 14 . (canceled) 
     
     
         15 . A waste heat recovery unit, comprising: a duct for hot gas, wherein the duct is divided into first, second and third adjacent and parallel channels each with an inlet and an outlet, a heat exchanger is located in each of the first and third channels, and the second channel is located between the first and third channels and provides a bypass channel, and further comprising a damper system operable to selectively open and close the inlets of the first, second and third channels, wherein the damper system comprises a plurality of rotatable blades mounted to walls dividing the duct into the first, second and third channels, and connected to a common actuator. 
     
     
         16 . A waste heat recovery unit as claimed in  claim 15 , wherein the actuator is operable to rotate the blades simultaneously and in opposite directions, whereby the blades are rotated towards one another to close the inlet to the bypass channel and are rotated away from one another to close the inlets to the heat exchanger channels. 
     
     
         17 . A waste heat recovery unit as claimed in  claim 15 , wherein the cross-section of each channel is substantially rectangular. 
     
     
         18 . A waste heat recovery unit as claimed in  claim 16 , wherein the cross-section of each channel is substantially rectangular. 
     
     
         19 . A waste heat recovery unit as claimed in  claim 15 , wherein each heat exchanger comprises an array of tubing for circulating fluid to be heated, the tubing supported by a support structure and extending across the respective heat exchanger channel, wherein a portion of the array extends through the support structure such that a plurality of tubing portions are located outside a main flow channel, the tubing portions arranged adjacent to and spaced from one another, and further comprising a plurality of baffles each located between adjacent tubing portions to at least partially fill the spacing therebetween. 
     
     
         20 . A waste heat recovery unit as claimed in  claim 19 , wherein the tubing comprises a portion of larger outer diameter extending across the duct and through the support structure, and a portion of smaller outer diameter located external to the support structure, such that a smaller spacing is provided between adjacent larger outer diameter tubing portions, and a larger spacing is provided between adjacent smaller outer diameter tubing portions, and wherein the baffles are provided in the larger spacings. 
     
     
         21 . A waste heat recovery unit as claimed in  claim 19 , wherein each baffle comprises a rigid plate within an outer insulating blanket. 
     
     
         22 . A waste heat recovery unit as claimed in  claim 21 , wherein the rigid plate is formed of metal and the blanket is formed of ceramic fibres. 
     
     
         23 . A waste heat recovery unit as claimed in  claim 20 , wherein each baffle comprises a rigid plate within an outer insulating blanket. 
     
     
         24 . A waste heat recovery unit as claimed in  claim 23 , wherein the rigid plate is formed of metal and the blanket is formed of ceramic fibres. 
     
     
         25 . A waste heat recovery unit as claimed in  claim 15 , wherein the damper system comprises a plurality of rotatable blades, each blade comprising an upstream plate spaced from a downstream plate, and means to supply pressurised gas into the spacing between the upstream and downstream plates, wherein a plurality of apertures are formed in at least some of the downstream plates to allow leakage of pressurised gas. 
     
     
         26 . A heat exchanger for a waste heat recovery unit, comprising a duct defining a main flow channel for hot gas, an array of tubing supported by a support structure and extending across the duct for circulating fluid to be heated, wherein part of the array extends through the support structure such that a plurality of tubing portions are located outside the main flow channel, adjacent to and spaced from one another, and further comprising a plurality of baffles each located between adjacent tubing portions so as to at least partially fill the spacing between them. 
     
     
         27 . A heat exchanger as claimed in  claim 26 , wherein the tubing comprises a portion of larger outer diameter extending across the duct and through the support structure, and a portion of smaller outer diameter located external to the support structure, such that a smaller spacing is provided between adjacent larger outer diameter tubing portions, and a larger spacing is provided between adjacent smaller outer diameter tubing portions, and wherein the baffles are provided in the larger spacings. 
     
     
         28 . A heat exchanger as claimed in  claim 26 , wherein each baffle comprises a rigid plate within an outer insulating blanket. 
     
     
         29 . A heat exchanger as claimed in  claim 28 , wherein the rigid plate is formed of metal and the blanket is formed of ceramic fibres. 
     
     
         30 . A heat exchanger as claimed in  claim 26 , wherein each baffle comprises a rigid plate within an outer insulating blanket. 
     
     
         31 . A heat exchanger as claimed in  claim 30 , wherein the rigid plate is formed of metal and the blanket is formed of ceramic fibres. 
     
     
         32 . A waste heat recovery unit comprising at least one duct for directing hot gas to a heat exchanger unit and at least one bypass duct to bypass hot gas around the heat exchanger unit, and a damper system comprising a plurality of rotatable blades, each blade comprising an upstream plate spaced from a downstream plate, and means to supply pressurised gas into the spacing between the upstream and downstream plates, wherein a plurality of apertures are formed in at least some of the downstream plates to allow leakage of pressurised gas into the or each heat exchanger duct. 
     
     
         33 . A waste heat recovery unit as claimed in  claim 32 , further comprising a heat exchanger comprising a heat exchanger duct defining a main flow channel for hot gas, an array of tubing supported by a support structure and extending across the heat exchanger duct for circulating fluid to be heated, wherein part of the array extends through the support structure such that a plurality of tubing portions are located outside the main flow channel, adjacent to and spaced from one another, and further comprising a plurality of baffles each located between adjacent tubing portions so as to at least partially fill the spacing between them.