High pressure naturally aspirated tube heater

Abstract

A heater unit assembly designed for enhanced combustion efficiency and low maintenance. The heater unit assembly comprises a heat distribution assembly connected to a burner assembly. The burner assembly comprises a gas outlet orifice aligned to a burner venturi, wherein the gas outlet orifice comprises internally a channel formed by two constricted sections with reduced diameters for controlling the pressure of the gas flowing to the burner venturi. The burner venturi is paired with an air restrictor and a burner outlet adaptor for complete naturally aspirated combustion.

What is claimed is: 
     
         1 . A heater unit assembly comprising:
 a. a burner assembly configured to provide a flow of heated air, the burner assembly comprising a gas outlet orifice aligned with a burner venturi, wherein:   the gas outlet orifice is positioned in a gas line leading to the burner venturi;   the gas outlet orifice comprises, internally from an inlet end to an outlet end, a gas channel comprising a wide section having a first diameter, a first constricted section having a second diameter, and a second constricted section having a third diameter, wherein the third diameter is larger than the second diameter but smaller than the first diameter; and   the burner venturi comprises, internally from an inlet end to an outlet end, a gas channel comprising an inlet portion, a throat portion, and an outlet portion, wherein the throat portion is narrower than the inlet portion and the outlet portion; and   b. a heat distribution assembly connected to the burner assembly and configured to distribute the heat from the flow of heated air provided by the burner assembly.   
     
     
         2 . The heater unit assembly of  claim 1 , wherein the third diameter is about 1.1 to about 1.6 times the second diameter, and about 0.1 to about 0.2 times the first diameter. 
     
     
         3 . The heater unit assembly of  claim 1 , wherein the third diameter is about 1.425 times the second diameter. 
     
     
         4 . The heater unit assembly of  claim 1 , wherein the gas channel of the gas outlet orifice further comprises a tapered section between the wide section and the first constricted section, wherein the tapered section has a diameter gradually decreased from the first diameter to the second diameter. 
     
     
         5 . The heater unit assembly of  claim 1 , wherein the gas outlet orifice is not physically connected to the burner venturi. 
     
     
         6 . The heater unit assembly of  claim 1 , wherein the burner venturi further comprises an air restrictor mounted at an inlet end thereof, configured to regulate air entering the burner venturi, and an outlet adaptor mounted at an outlet end thereof, configured to generate sufficient back pressure to maintain stable combustion, wherein the air restrictor and the outlet adaptor each have a hollow cylindrical shape with an internal cavity. 
     
     
         7 . The heater unit assembly of  claim 1 , wherein the burner assembly further comprises a pilot and a pilot orifice positioned in a gas line leading to the pilot, wherein the pilot orifice comprises, from an inlet end to an outlet end, a gas channel comprising at least one wide section and an orifice hole, wherein the orifice hole has a diameter smaller than that of the at least one wide section. 
     
     
         8 . The heater unit assembly of  claim 7 , wherein the orifice hole has a diameter of about 1/40 to about 1/50 of the diameter of the at least one wide section. 
     
     
         9 . The heater unit assembly of  claim 1 , wherein the heat distribution assembly comprises a radiant tube with a proximal end connected to the burner assembly. 
     
     
         10 . The heater unit assembly of  claim 1 , wherein the burner assembly is configured as a burner box divided into a sealed side and an unsealed side, wherein the sealed side is fully closed, and the unsealed side comprises openings for airflow and cooling. 
     
     
         11 . The heater unit assembly of  claim 10 , wherein the sealed side of the burner box comprises a pilot safety control, wherein the pilot safety control comprises a first valve configured to receive high pressure gases from an external source, a second valve configured to control flow of gas to the burner venturi through the gas outlet orifice, a third valve configured to control flow of gas to the pilot through the pilot orifice, and a fourth valve connected to a thermocouple that is configured to continuously monitor presence and stability of the pilot flame. 
     
     
         12 . The heater unit assembly of  claim 10 , wherein the sealed side of the burner box comprises an auto reset configured to automatically reset the heater unit assembly after a temporary interruption or fault. 
     
     
         13 . The heater unit assembly of  claim 11 , wherein the unsealed side of the burner box comprises the gas outlet orifice. 
     
     
         14 . The heater unit assembly of  claim 13 , wherein the inlet end of the burner venturi is mounted in a side wall of the burner box, and the remaining portion of the burner venturi extends outwardly from the burner box into the heat distribution assembly. 
     
     
         15 . The heater unit assembly of  claim 14 , wherein the pilot and the thermocouple are arranged parallel to the burner venturi. 
     
     
         16 . The heater unit assembly of  claim 15 , wherein the heat distribution assembly comprises a radiant tube with a proximal end connected to the side wall of the burner box, the radiant tube housing the burner venturi, pilot, and thermocouple extending outwardly from the burner box. 
     
     
         17 . The heater unit assembly of  claim 16 , wherein the proximal end of the radiant tube is welded to an adaptor ring that is mounted on an exterior surface of the side wall of the burner box, with an insulator positioned between the adaptor ring and the side wall.