Fluid flow diverter using purge fluid to create a positive pressure fluid barrier

A fluid flow diverter comprising:

• a diverter body comprising a first port, a second port, a third port, and a fourth port;
• a rotating plenum located within the diverter body, the rotating plenum having a first stop position that defines a first fluid flow path through the diverter and a second stop position that defines a second fluid flow path through the diverter, each of the fluid flow paths defining first and second fluid streams;
• high operating temperature brush seals or high operating temperature flexible material lining outside edges of the plenum that make clearance with communicating surfaces of the diverter body;
• and
• a purge fluid assembly supplying a purge fluid to the rotating plenum,
• wherein in the first fluid flow path, the first fluid stream goes between the first port and the second port, and the second fluid stream goes between the fourth port and the third port,
• in the second flow path, the first fluid stream goes between the first port and the third port, and the second fluid stream goes between the fourth port and the second port, and
• the purge fluid supplied to the rotating plenum creates a positive pressure fluid barrier that prevents or minimizes cross-contamination of the first and second fluid streams in the first and second fluid flow paths.

A regenerative thermal oxidizer comprising:

• a combustion chamber;
• first and second heat exchangers in flow communication with the combustion chamber;
• and
• a fluid flow diverter in flow communication with the first and second heat exchangers, the fluid flow diverter including:
• a diverter body comprising an inlet port that receives process gases, a second port in flow communication with first heat exchanger, a third port in flow communication with second heat exchanger, and an outlet port;
• a rotating plenum located within the diverter body, the rotating plenum having a first stop position that defines a first fluid flow path through the regenerative thermal oxidizer, and a second stop position that defines a second fluid flow path through the regenerative thermal oxidizer;
• a motor that repeatedly rotates the plenum 90° in the same direction in timed increments, so as to repeatedly switch between the first and second fluid flow paths;
• and
• a purge fluid assembly supplying a purge fluid to the rotating plenum,
• wherein in the first fluid flow path, the process gases received at the inlet port pass through the second port, then the first heat exchanger, then the combustion chamber, then the second heat exchanger, then the third port, and then exit the outlet port of the diverter,
• in the second flow path, the process gases received at the inlet port pass through the third port, then the second heat exchanger, then the combustion chamber, then the first heat exchanger, then the second port, and then exit the outlet port of the diverter, and
• the purge fluid supplied to the rotating plenum creates a positive pressure fluid barrier that prevents or minimizes bypass leakage from the inlet port to the outlet port of the diverter.