US 12,331,992 B2
Method for controlling a recycle gas stream utilizing an ejector for the cooling of a unit operation
William J Scharmach, Grand Island, NY (US); Richard M Kelly, East Amherst, NY (US); Mohammad Abdul-Aziz Rashad, Clarence, NY (US); Yi Ma Lenhert, Tomball, TX (US); and Matthew Thomas, Spring, TX (US)
Assigned to PRAXAIR TECHNOLOGY, INC., Danbury, CT (US)
Filed by William J Scharmach, Grand Island, NY (US); Richard M Kelly, East Amherst, NY (US); Mohammad Abdul-Aziz Rashad, Clarence, NY (US); Yi Ma Lenhert, Tomball, TX (US); and Matthew Thomas, Spring, TX (US)
Filed on Dec. 19, 2016, as Appl. No. 15/382,823.
Prior Publication US 2018/0172322 A1, Jun. 21, 2018
Int. Cl. F25D 3/10 (2006.01); F17C 5/02 (2006.01); F17C 9/02 (2006.01); F28C 3/08 (2006.01)
CPC F25D 3/10 (2013.01) [F17C 5/02 (2013.01); F17C 9/02 (2013.01); F28C 3/08 (2013.01); F17C 2227/0135 (2013.01)] 12 Claims
OG exemplary drawing
 
1. A method for direct cooling of a unit operation with a combination of a vaporized motive fluid stream and at least a portion of an effluent gas stream from the unit operation, wherein the direct cooling method comprises:
a. circulating a portion of said effluent gas stream from the unit operation with one or more non-mechanical pumps where the vaporized motive fluid stream is provided as a motive force wherein said unit operation is under a fixed heat load having a temperature in the range of 300 to 500° F.;
b. providing the vaporized motive fluid stream to the one or more non-mechanical pumps at a temperature in the range of −452° F. to 50° F.;
c. forming a cooling stream by combining said effluent gas stream from the unit operation and the vaporized motive fluid in the one or more non-mechanical pumps, wherein the cooling stream has a temperature in the range of −50° F. to 300° F.;
d. adjusting a recycle ratio of mass flow rates of said effluent gas stream from the unit operation to the vaporized motive fluid stream combined in the one or more non-mechanical pumps wherein the recycle ratio is determined by:

OG Complex Work Unit Math
where,
the Recycle Ratiomass is the ratio of the mass flow rate of the effluent to the mass flow rate of the vaporized motive fluid stream;
CMot is the specific heat of the vaporized motive fluid stream;
CEff is the specific heat of the unit operation effluent stream entering the one or more non-mechanical pumps;
TC is the temperature of the cooling stream or a target temperature of the cooling stream exiting the one or more non-mechanical pumps;
TMot is the temperature of the vaporized motive fluid stream, and is selected by the operator;
TEff is the temperature of the unit operation effluent stream entering the one or more non-mechanical pumps; and
direct cooling of said unit operation under the fixed heat load to a lower temperature by routing the cooling stream to the unit operation.