Natural Draft Combustion Mixer
A natural draft combustion mixer in which the primary air intake is positioned downstream from the point of fuel introduction and also consists of a heat return port for orifice freeze protection that is located adjacent to the orifice, as well as a removable orifice holder for ease of access to the orifice during maintenance and set-up of a combustion system.
As per 35 USC §119(e), this application is related to the provisional application filed on Nov. 27, 2012. Application No. 61/730,455 (Confirmation Number: 5768)
STATEMENT REGARDING FEDERALLY SPONSERED RESEARCH OR DEVELOPMENTNot Applicable
THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENTNot Applicable
INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISCNot Applicable
BACKGROUND OF INVENTIONA natural draft combustion mixer is a device that is utilized in processes where heat is required and achieved by means of heat release from the combustion reaction of fuel and air in a combustion chamber. The mixer is used to perform the mixing of the fuel and air to achieve a mixture above the LEL (lower explosive limit) and below the UEL (upper explosive limit). The primary air shutter is used to control the amount of air that is entering the mixer to attain the required combustion properties. An orifice, of various sizes depending on capacity requirements, is used to calculate the actual volume of fuel per unit time that passes through from a point of predetermined pressure to an area of atmospheric pressure. It is also the point where the well known physics principle of high velocity creating a low pressure area is used to cause atmospheric pressure to push air into the mixer or induce air. The mixture exits through a nozzle at which point the ignition actually occurs and the combustion reaction takes place. Traditionally, the primary air shutter has been located at a point upstream from the point of fuel introduction. Thus, the flow of cold primary air must pass by the orifice and, as a result, strips heat away from the orifice. The orifice is prone to freezing due to the varying composition/water content of the fuel being used in conjunction with the pressure drop that occurs at this point. In order to change the capacity of the mixer, the orifice needs to change in size and/or the pressure adjusted. This typically involves the dismantlement of the mixer assembly to provide access to the orifice.
SUMMARY OF THE INVENTIONThe object of this invention is to prevail over the drawbacks relating to prior art in this field as stated above.
The primary air intake has been relocated to a position downstream of the fuel gas point of introduction. Now the stream of fuel leaving the orifice is at its highest velocity, and thus, lowest pressure, at the point of air induction rather than the traditional upstream location. This design allows for a greater volume of air to be introduced than on a similarly sized traditional mixer.
A removable orifice holder has been designed to allow for the removal of only the holder to access the orifice for maintenance and set-up. This allows the rest of the assembly to remain stationary as it is not required to be removed from the combustion chamber.
A port has been positioned adjacent to the orifice location to allow the use of an orifice preheat line to be installed. This port provides a point of entrance for the high temperature, products of combustion (POC) from the mixing chamber into the mixer housing. These POC can be drawn back and directly across the orifice, using the same physics principle as previously discussed, to further prevent the freeze off issues traditionally encountered.
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A line, such as a piece of stainless steel tubing, may be connected between the orifice preheat port 4 and the flame front where the POC are produced. As the high velocity fuel enters the mixer, the low pressure created draws high temperature POC down and across the adjacent orifice, effectively heating the orifice well above the temperature at which ice will form.
Claims
1. The relocation of the primary air introduction being downstream of the orifice will prevent heat loss from the orifice due to very cold combustion air passing over and striping valuable heat from the orifice.
2. The relocation of the orifice preheat port, to a position directly adjacent to the orifice, draws high temperature POC directly down and across the orifice which heats the orifice preventing the build-up and accumulation of ice, thus, preventing freeze-off of the orifice.
3. A removable orifice holder that allows the user to perform maintenance or set-up on the orifice without dismantling the assembly and removing it from the combustion chamber.
Type: Application
Filed: Sep 9, 2013
Publication Date: Mar 12, 2015
Inventors: Robbie Warren Lundstrom (Edberg), Derek Lloyd Herder (Camrose)
Application Number: 14/022,158
International Classification: F23D 14/04 (20060101); F23D 14/66 (20060101);