US 11,940,178 B2
Condensing, ultra-low NOx gas-fired humidifier
James M. Lundgreen, Lakeville, MN (US); Cole K. Farley, Long Lake, MN (US); Alvin J. Klisch, Eden Prairie, MN (US); David Pflum, Eden Prairie, MN (US); and Daniel W. Celotta, Circle Pines, MN (US)
Assigned to DRI-STEEM Corporation, Eden Prairie, MN (US)
Filed by DRI-STEEM Corporation, Eden Prairie, MN (US)
Filed on Jun. 30, 2022, as Appl. No. 17/855,156.
Application 17/855,156 is a continuation of application No. 16/251,938, filed on Jan. 18, 2019, granted, now 11,421,899.
Claims priority of provisional application 62/619,701, filed on Jan. 19, 2018.
Prior Publication US 2022/0404041 A1, Dec. 22, 2022
Int. Cl. F24F 6/18 (2006.01); F22B 9/00 (2006.01); F22B 31/08 (2006.01); F22B 37/06 (2006.01); F22D 1/00 (2006.01); F23D 14/22 (2006.01); F24F 6/00 (2006.01)
CPC F24F 6/18 (2013.01) [F22B 9/00 (2013.01); F22B 31/08 (2013.01); F22B 37/06 (2013.01); F22D 1/00 (2013.01); F23C 2900/09002 (2013.01); F23D 14/22 (2013.01); F24F 2006/008 (2013.01); F24F 2221/34 (2013.01)] 7 Claims
OG exemplary drawing
 
1. A gas-fired humidifier comprising:
a) an atmospheric pressure storage tank for holding a volume of water, the storage tank having a make-up water inlet and a steam outlet;
b) a gas-fired burner and combustion blower assembly;
c) a primary heat exchanger connected to the gas-fired burner and combustion blower assembly, the primary heat exchanger being located within the storage tank and configured to heat the volume of water to generate steam;
d) a make-up water heat exchanger configured to receive exhaust gases generated and discharged by the gas-fired burner and combustion blower assembly to pre-heat make-up water delivered to the storage tank, the make-up water heat exchanger having a combustion gas side through which exhaust gases flow in an upward direction, and a water side in which the make-up water flows in a downward direction;
e) a first conduit connecting a first port of the make-up water heat exchanger to the storage tank make-up water inlet;
f) a second conduit connecting an exhaust gas inlet port of the make-up water heat exchanger to an outlet of the primary heat exchanger;
g) a pressure equalization line connecting a second port of the make-up water heat exchanger to the storage tank at a location above the make-up water inlet, the second conduit including a trap section to block steam from the storage tank from entering the make-up water heat exchanger;
h) a make-up water valve assembly including a solenoid valve and an orifice for controlling a net flow rate of an inlet water stream into the make-up water heat exchanger, the make-up water valve assembly being directly connected to a third port of the make-up water heat exchanger; and
i) an electronic controller configured to send a pulse-width-modulated output signal to the solenoid valve to supply make-up water to the make-up water heat exchanger.