Apparatus and methods for boosting efficiency on recuperative radiant tube systems

A method of improving a thermal efficiency of a recuperative radiant tube system, comprising:

• producing a stream of products of combustion (POC) through a combustion process in a burner of a radiant tube;
• passing the stream of POC to an exhaust leg of the radiant tube, through a recuperator assembly and subsequently through a booster assembly coupled to the recuperator assembly;
• recirculating a portion of the stream of POC exiting the recuperator assembly at a first exit into the burner;
• flowing rest of the stream of POC exiting the booster assembly at a second exit;
• passing a stream of combustion air through the booster assembly and subsequently through the recuperator assembly, the stream of combustion air flows from a colder end to a hotter end;
• and
• reversing a flow direction of the stream of combustion air to flow from the hotter end to the colder end, exiting the recuperator assembly at a third exit, and recirculating it to the burner, wherein the recuperator assembly comprises a first heat exchanger to facilitate heat exchange between the stream of combustion air and the stream of POC in a recirculation loop, and the booster assembly comprises a second heat exchanger to facilitate additional heat exchange between the stream of POC and the stream of combustion air outside the recirculation loop.

A booster assembly configured to couple to recuperator assembly in a recuperative radiant tube system, the recuperator assembly having a cold end and a hot end, the booster assembly comprising:

• an outer casing couplable to an outer casing of the recuperator assembly on the cold end, wherein the outer casing comprises an inlet and an exhaust;
• an outer tube disposed within the outer casing comprising a first opening and a second opening, wherein a first passage is formed between the outer casing and the outer tube;
• and
• a displacement tube that is closed on at least one end and is disposed within the outer tube, wherein a second passage is formed between the displacement tube and the outer tube, the inlet of the outer casing is in fluid communication with the second passage and the exhaust of the outer casing is in fluid communication with the first passage, and wherein the booster assembly is configured to pass a stream of combustion air from the inlet through the second passage into the cold end of the recuperator assembly;
• and receive a least a portion of a stream of products of combustion (POC) from the recuperator assembly and pass it through the first passage and exit the booster assembly from the exhaust.