Heated replacement air system for commercial applications

Abstract

Apparatus and a method for providing heated replacement air to a paint spray booth or other commercial process which requires heated make-up air to replace exhausted air. A blower draws outside air through a filter and an injection chamber prior to delivering the air to the process. Hot gases from a burner are injected into the injection chamber and mixed with the replacement air to adjust the temperature of the replacement air. The burner uses combustion air which is separate from the replacement air. The flow rate of the exhaust air and the replacement air can be adjusted to meet changing needs of the process. The BTU output from the burner is adjusted to maintain a desired replacement air temperature.

1 . An apparatus for supplying heated replacement air to a process in which air is exhausted, the apparatus comprising:
 an air intake connected to an injection chamber from which an adjustable volume of replacement air flows to the process,   a source of BTU energy positioned outside and connected to the injection chamber and configured to inject heated gas into the injection chamber, wherein the adjustable volume of air through the injection chamber can change without affecting the air-to-fuel ratio of said source of BTU energy; and,   at least one process fan configured to:
 i) draw the replacement air through the air intake and into the injection chamber based upon the variable requirements of the process, and 
 ii) deliver a predetermined and adjustable volume of the heated replacement air to the process 
   
   
   
       2 . The apparatus for supplying heated replacement air to a process, as set forth in  claim 1 , further including a mixing device located between the injection chamber and the at least one fan. 
   
   
       3 . The apparatus for supplying heated replacement air to a process as set forth in  claim 1 , wherein the source of heated gas is a gas burner positioned outside the injection chamber, the gas burner including a dedicated blower connected to the gas burner to supply the combustion air and inject heated gases from the gas burner into the injection chamber. 
   
   
       4 . The apparatus for supplying heated replacement air to a process, as set forth in  claim 1 , further including an adjustable mode changing damper configured to be moveable between a first position, wherein replacement air from a first location is drawn by the at least one fan from the air intake into the injection chamber, and a second position, wherein air from a second location is drawn by the at least one fan into the injection chamber. 
   
   
       5 . An apparatus for supplying heated replacement air to a process in which air is exhausted, the apparatus comprising:
 an air intake connected to an injection chamber for supplying a desired volume of replacement air to the process;   a source of BTU energy positioned outside and connected to said injection chamber and configured to inject heated gas into said injection chamber;   at least one delivery fan configured to:
 i) draw replacement air through the air intake and into said injection chamber, 
 ii) mix the heated gas with the replacement air to form the heated replacement air, and, 
 iii) deliver a predetermined adjustable volume of the heated replacement air to the process, 
   wherein the volume of the heated replacement air is substantially the same volume as the exhaust air from the process, and wherein the volume of the replacement air does not affect the air-to-fuel ratio of the BTU energy that is injected into said injection chamber.   
   
   
       6 . The apparatus for supplying heated replacement air to a process, as set forth in  claim 5 , and further including multiple gas burners positioned outside the injection chamber wherein the gas burners would each have a dedicated blower with the gas burners having the same or different BTU output with controls to engage the gas burners adjust the injected BTU energy. 
   
   
       7 . The apparatus for supplying heated replacement air to a process, as set forth in  claim 5 , and further including an indirect heat exchanger mounted in the injection chamber configured to be moveable between first and second positions during the operation of the apparatus,
 wherein when the indirect heat exchanger is in the first position heated gas is injected directly into replacement air drawn through the injection chamber; and,   wherein when the indirect heat exchanger is in the second position heated gas flows through the indirect heat exchanger and out through a vent in the apparatus which is engaged as the indirect heat exchanger is moved into the second position and replacement air drawn through the injection chamber is indirectly heated by the indirect heat exchanger.   
   
   
       8 . The apparatus for supplying heated replacement air to a process, as set forth in  claim 7 , and further including an adjustable intake damper mounted between the air intake and the injection chamber; the adjustable intake damper having a position permitting an unrestricted flow of air from the first location through the air intake when the indirect heat exchanger is in its first position and the intake damper blocking air flow from the first location through the air intake when the indirect heat exchanger is in its second position to force the flow of air from a second location. 
   
   
       9 . The apparatus for supplying heated replacement air to a process, as set forth in  claim 5 , wherein the source of BTU energy is a gas burner, the gas burner including a dedicated blower connected to develop a proper air-to-fuel ratio and inject hot combustion gases from the gas burner into the injection chamber thereby preventing a change in the volume of replacement air from directly affecting the air-to-fuel ratio in said gas burner. 
   
   
       10 . The apparatus for supplying either direct heated replacement air to a process or indirect heated air as set forth in  claim 5 , the apparatus further including:
 a mode changing damper having a first position, wherein replacement air from a first location is drawn by the at least one fan from the air intake into the injection chamber, and having a second position,   wherein air from a second location is drawn by the at least one fan into the injection chamber across a movable indirect heat exchanger mounted in the injection chamber,
 the indirect heat exchanger being in the first position when the damper is in the first position and heated gas is injected directly into replacement air drawn through the injection chamber; and, 
 the indirect heat exchanger being in the second position when the damper is in the second position and heated gas flows through the indirect heat exchanger and replacement air is drawn through the injection chamber and is indirectly heated by the indirect heat exchanger. 
   
   
   
       11 . A method for providing heated replacement air to a process in which air is exhausted comprising the steps of:
 a) drawing an adjustable volume of replacement air through an air intake and an injection chamber;   b) injecting a flow of hot gas from a BTU source located outside the injection chamber into the replacement air as it is drawn through said injection chamber to heat the replacement air to the desired temperature where the injected hot gas is produced with an optimum air-to-fuel ratio not affected by changes in the replacement air volume, and,   c) mixing the replacement air and the injected hot gas to provide a substantially uniform temperature to the heated replacement air.   
   
   
       12 . The method for providing heated replacement air at variable air volumes to a process, as set forth in  claim 11 , and further including the steps of:
 d) sensing the temperature of the heated replacement air after it is mixed; and,   e) adjusting the BTU's output in the injected flow of hot gas to maintain a desired temperature in the heated replacement air delivered at different air volumes to the process.   
   
   
       13 . The method for providing heated replacement air to a process at variable air volumes, as set forth in  claim 12 , and further including the steps of:
 adjusting a flow of replacement air delivered to the process in response to changes in the amount of air exhausted from the process; and   adjusting the BTU's in the flow of hot gas injected into the injection chamber by the engagement of a plurality of burners with the same or differing output levels where the burners would be located outside the injection chamber and each burner would have a dedicated blower to produce a BTU output at an optimal air-to-fuel ratio where the burners are engaged to maintain a desired temperature in the heated replacement air.   
   
   
       14 . The method for providing heated replacement air to a process, as set forth in  claim 12 , including converting from directly heating replacement air to indirectly heating replacement air with the use of a mode changing damper and a moveable heat exchanger in the injection chamber, injecting the hot gas into the heat exchanger, and heating the replacement air with the heat exchanger.