Direct fired heaters with in-shot burners, tubular combustion chambers, and/or variable venturi

Abstract

Exemplary embodiments of the present disclosure include direct fired heaters and methods relating to the operation of direct fired heaters. An exemplary embodiment of a direct fired heater generally includes one or more in-shot burners and one or more combustion tubes configured to receive combustion air emanating from the one or more in-shot burners. The direct fired heater includes a passageway having an inlet configured to receive or intake a circulating air flow. The passageway may include a venturi portion downstream of the inlet in fluid communication with the exit ends of the combustion tubes. The flow of circulating air through the venturi portion may induce flow of combustion air through the one or more combustion tubes.

1 . A direct fired heater comprising:
 one or more in-shot burners;   one or more combustion tubes configured to receive combustion air emanating from the corresponding one or more in-shot burners, each combustion tube having an exit end; and   a passageway having an inlet configured to intake circulating air, and a venturi portion downstream of the inlet in fluid communication with the exits ends of the one or more combustion tubes, the passageway configured such that flow of circulating air through the venturi portion induces flow of combustion air through the one or more combustion tubes.   
     
     
         2 . The direct fired heater of  claim 1 , wherein the passageway is configured such that flow of circulating air through the venturi portion induces flow of combustion air through the one or more combustion tubes, without any blower for exclusively providing combustion air flow. 
     
     
         3 . The direct fired heater of  claim 1 , wherein the passageway further includes an outlet downstream of the venturi portion and the exit ends of the one or more combustion tubes, the outlet operable for discharging combustion air and circulating air out of the direct fired heater. 
     
     
         4 . The direct fired heater of  claim 1 , wherein the venturi portion defines a constriction having a reduced cross-sectional area that is configured such that air flow through the venturi portion produces a reduction in fluid pressure downstream of the venturi portion, which induces combustion air flow through the one or more combustion tubes. 
     
     
         5 . The direct fired heater of  claim 1 , further comprising a circulating air blower in communication with the inlet of the passageway and operable for forcing circulating air through the venturi portion, to create a venturi effect that induces flow of combustion air through the one or more combustion tubes. 
     
     
         6 . The direct fired heater of  claim 5 , wherein the direct fired heater is configured such that combustion air flow is induced through the one or more combustion tubes without operation of any blower other than the circulating air blower. 
     
     
         7 . The direct fired heater of  claim 1 , wherein the venturi portion includes an element that is movable for varying the cross-sectional opening area of the venturi portion. 
     
     
         8 . The direct fired heater of  claim 7 , wherein the direct fired heater is configured to control the movement of the element for varying the fluid pressure downstream of the venturi portion and/or for maintaining carbon monoxide and nitrogen dioxide levels below a predetermined amount. 
     
     
         9 . The direct fired heater of  claim 1 , further comprising a gas valve in communication with the one or more in-shot burners and operable for varying the flow rate of gas to the one or more in-shot burners. 
     
     
         10 . The direct fired heater of  claim 1 , further comprising a baffle movable between at least a first configuration in which the venturi portion has a first cross-sectional area and a second configuration in which the venturi portion has a second cross-sectional area larger than the first cross-sectional area. 
     
     
         11 . The direct fired heater of  claim 10 , further comprising an actuator for moving the baffle between the first and second positions. 
     
     
         12 . The direct fired heater of  claim 11 , wherein the actuator is a two-position actuator that controls the height of the baffle with a rotating cam device, to move the baffle between the first and second positions. 
     
     
         13 . The direct fired heater of  claim 10 , wherein the direct fired heater is configured to control the movement of the adjustable baffle for varying the fluid pressure downstream of the venturi portion, to thereby allow for regulation of the level of combustion air flow through the one or more combustion tubes to maintain carbon monoxide and/or nitrogen dioxide below a predetermined amount. 
     
     
         14 . The direct fired heater of  claim 10 , further comprising a gas valve in communication with the one or more in-shot burners, and configured to vary the rate of gas flow between a first gas flow rate and at least one reduced gas flow rate, wherein the direct fired heater is configured to control the gas valve to establish the first gas flow rate when the baffle is in first configuration and to establish the at least one reduced gas flow rate when the baffle is in the second configuration. 
     
     
         15 . The direct fired heater of  claim 1 , wherein the passageway comprises a plenum. 
     
     
         16 . A direct fired heater comprising:
 one or more combustion chambers each having an exit end;   a circulating air blower configured to establish a flow of circulating air; and   a passageway having an inlet in communication with the circulating air blower, a venturi portion downstream of the inlet in fluid communication with the exit ends of the one or more combustion chambers, the passageway configured such that circulating air flow through the venturi portion creates a venturi effect that induces flow of combustion air through the one or more combustion chambers, without requiring operation of any blower other than the circulating air blower.   
     
     
         17 . The direct fired heater of  claim 16 , further comprising an adjustable element for varying the cross-sectional opening area of the venturi portion. 
     
     
         18 . The direct fired heater of  claim 16 , further comprising a baffle movable between at least a first configuration in which the venturi portion has a first cross-sectional area and a second configuration in which the venturi portion has a second cross-sectional area larger than the first cross-sectional area. 
     
     
         19 . The direct fired heater of  claim 16 , further comprising one or more in-shot burners configured such that the one or more combustion chambers receive combustion air emanating from the corresponding one or more in-shot burners. 
     
     
         20 . The direct fired heater of  claim 16 , wherein the one or more combustion chambers comprise tubes. 
     
     
         21 . The direct fired heater of  claim 16 , wherein the passageway comprises a plenum and an outlet through which combustion air and circulating air are discharged. 
     
     
         22 . A direct fired heater comprising:
 a passageway having an inlet configured to intake circulating air and a venturi portion downstream of the inlet;   a baffle movable between at least a first height in which the venturi portion has a first cross-sectional area and a second height lower than the first height such that the venturi portion has a second cross-sectional area larger than the first cross-sectional area;   a rotating cam device pivotably coupled to the baffle for pivotal movement between a first position in which the baffle is at the first height and a second position in which the baffle is at the second height; and   an actuator coupled to the rotating cam device for rotating the rotating cam device between the first and second positions to selectively change the height of the baffle between the first and second heights.   
     
     
         23 . The direct fired heater of  claim 22 , wherein the direct fired heater includes:
 one or more in-shot burners, each in-shot burner having an inlet end and an outlet end;   one or more combustion tubes, each combustion tube having an inlet end and an exit end, the inlet ends of the one or more combustion tubes being configured to receive combustion air emanating from the corresponding outlet ends of the one or more in-shot burners, the exit ends in fluid communication with the venturi portion such that circulating air flow through the venturi portion creates a venturi effect that induces flow of combustion air through the one or more combustion tubes.   
     
     
         24 . The direct fired heater of  claim 23 , wherein the direct fired heater includes a circulating air blower in communication with the inlet of the passageway and operable for forcing circulating air through the venturi portion, to create a venturi effect that induces flow of combustion air through the one or more combustion tubes, without requiring the use of an additional blower specifically provided to induce combustion air flow. 
     
     
         25 . The direct fired heater of  claim 22 , wherein the direct fired heater is configured such the height of the baffle between the first and second height is varied based on burner input. 
     
     
         26 . A direct fired heater comprising:
 one or more in-shot burners;   one or more combustion tubes configured to receive combustion air emanating from the corresponding one or more in-shot burners, each combustion tube having an exit end; and   a passageway having an inlet configured to intake circulating air and an outlet downstream of the exit ends of the one or more combustion tubes, the passageway configured such that combustion air and circulating air are mixed downstream of the exit ends of the combustion tubes and discharged from the outlet of the passageway.   
     
     
         27 . The direct fired heater of  claim 26 , wherein the passageway includes a venturi portion downstream of the inlet in fluid communication with the exit ends of the one or more combustion chambers, the passageway configured such that circulating air flow through the venturi portion creates a venturi effect that induces flow of combustion air through the one or more combustion chambers. 
     
     
         28 . The direct fired heater of  claim 26 , wherein the direct fired heater includes a circulating air blower in communication with the inlet of the passageway and operable for forcing circulating air through the passageway to induce flow of combustion air through the one or more combustion tubes, without requiring the use of an additional blower specifically provided to induce combustion air flow. 
     
     
         29 . The direct fired heater of  claim 26 , further comprising an adjustable element for varying the cross-sectional opening area of a portion of the passageway. 
     
     
         30 . The direct fired heater of  claim 26 , further comprising a baffle movable between at least a first configuration in which a portion of the passageway has a first cross-sectional area and a second configuration in which the portion of the passageway has a second cross-sectional area larger than the first cross-sectional area. 
     
     
         31 . The direct fired heater of  claim 26 , wherein the passageway comprises a plenum. 
     
     
         32 . The direct fired heater of  claim 26 , further comprising:
 a baffle movable between at least a first height in which a portion of the passageway has a first cross-sectional area and a second height lower than the first height such that the portion of the passageway has a second cross-sectional area larger than the first cross-sectional area;   a rotating cam device pivotably coupled to the baffle for pivotal movement between a first position in which the baffle is at the first height and a second position in which the baffle is at the second height; and   an actuator coupled to the rotating cam device for rotating the rotating cam device between the first and second positions to selectively change the height of the baffle between the first and second heights.   
     
     
         33 . A method relating to operation of a direct fired heater, the method comprising inducing combustion air flow through one or more combustion chambers by forcing circulating air through a venturi portion in fluid communication with the exit ends of the one or more combustion chambers. 
     
     
         34 . The method of  claim 33 , further comprising varying the venturi portion to adjust the rate of combustion air flow induced through the one or combustion chambers when circulating air is forced through the venturi portion. 
     
     
         35 . The method of  claim 33 , further comprising varying the cross-sectional opening area of the venturi portion. 
     
     
         36 . The method of  claim 33 , wherein the method includes operating a circulating air blower to force circulating air through the venturi portion. 
     
     
         37 . The method of  claim 33 , wherein the direct fired heater does not include a draft inducer fan, and wherein the method includes operating a circulating air blower to force circulating air through the venturi portion to create a venturi effect for inducing combustion air flow through one or more combustion chambers. 
     
     
         38 . A method relating to operation of a direct fired heater, the method comprising:
 operating one or more in-shot burners configured to fire into the one or more combustion tubes having exit ends;   mixing combustion air and circulating air downstream of the exit ends of the one or more combustion tubes; and   discharging combustion air and circulating air from an outlet of a passageway that is downstream of the exit ends of the one or more combustion tubes.   
     
     
         39 . The method of  claim 38 , further comprising inducing combustion air flow through the one or more combustion chambers by forcing circulating air through a venturi portion of the passageway that is in fluid communication with the exit ends of the one or more combustion chambers.