Design of Atmospheric Gas Burners

Robert P. Jackson, P.E.

Course Outline

This eight hour course is intended to provide an in depth discussion for the design of atmospheric gas burners.  We will discuss the various burner parts, their function and how those individual parts interact with each other.  We will also discuss the overall burner relationships within an assembly of components; i.e. gas distribution system, support structure(s), ignition system etc.  The basic design principals are governed by formulas developed over the years for defining the following relationships:

• Gas pressure vs. profile of converging / diverging passageways.
• Flame speed vs. flame ejection velocity
• Port loading vs. number of ports
• Percent primary air vs. percent carbon dioxide in products of combustion
• Primary air vs. flame appearance
• Gas type vs. flexibility of burner deign.
• Throat diameter to port area ratio
• The effects of gas/air temperature on complete combustion
• The distance of the orifice from the burner throat vs. the ability of the burner to aspirate the gas/air mixture
• Port spacing vs. lifting, flashback and floating of individual burner flames.
• Orifice alignment vs. ability of burner to eject mixture at ports and achieve complete combustion.

We will demonstrate the formulas governing these relationships by working an example where a burner is designed from start to finish.

This course includes a multiple choice quiz at the end, which is designed to enhance the understanding of the course materials.

Learning Objective

Upon completion of this course, the student will:

• Fully understand the operation of atmospheric gas burners including the entrainment of air and how a homogeneous mixture of gas and air is accomplished within the burner itself;
• Know the benefits of using an atmospheric burner over a power burner or other types of gas burners;
• Know the basic rules governing the design and use of atmospheric burners;
• Be able to recognize “ideal burner characteristics”;
• Be able to recognize a burner operating improperly and have solutions for a “fix”;
• Understand the terms “primary air”, “secondary air” and “excess air”;
• Become aware of the different types of atmospheric burners; i.e. power burner, inshot burner, slotted-port burner, ribbon burner, etc;
• Understand the importance of orifice design and the “K” factor defining that design;
• Will know the burner classifications by the type of port designed into the burner system;
• Be able to calculate and select the proper orifice diameter, depth and spacing so that good combustion and a desirable flame appearance may be had;
• Be able to calculate orifice flow rates given heating value, specific gravity and gas pressure;
• Be able to use the gas tables given to select orifice diameters relative to gas flow rates and desired burner inputs;
• Understand the importance of spacing from the orifice to the throat and what that means for the percentage of primary air entrainment;
• Understand the various burner components and their function relative to the overall burner assembly; i.e. air shutters, throat, mixing tubes, burner head, burner ports, etc;
• Understand the relationship between burner components and how design changes for one can effect operation of the burner itself;
• Be able to recognize the difference between “blowing” and “flashback”;
• Understand how the gas type, specific gravity and heating value can affect burner design consequently burner performance;
• Understand how a burner can be designed to accommodate interchangeability of gasses; i.e. natural to propane, natural to manufactured, etc;
• Understand why the relationship between port area and venture throat area is so important;
• Understand why port loading; i.e. Btu/Hr-in² , important relative to flashback, yellow-tipping and lifting of burner flames;
• Be able to calculate the percentage of primary air injected relative to port area, throat area and port depth;
• Be able to calculate port loading;
• Understand the effect external conditions; i.e. gas pressure, gas temperature, availability of primary air, etc, will have on burner operation;
• Be able to select the best burner material for given applications and conditions;
• Understand the relationship between primary air and burner sooting;
• Understand why pressure drop in a gas distribution system is “the enemy”;
• Understand relationships between burner port design and “blow-off”, “lifting” and “flashback”;
• Have enough knowledge to troubleshoot problems with burners and burner systems;
• Be able to design a burner; ( NOTE:  We will demonstrate the design process from start to finish;)
• Understand the basic differences between atmospheric burners and power burners; and
• Be able to calculate the inner cone height.

Intended Audience

This course is designed to be a companion course to “Fundamentals of Gas Combustion”, M273; although both courses stand alone and one does not depend upon the other for understanding.  “Fundamentals” is not a prerequisite for this course though both would give a clearer understanding of basic principals relative to gas-fired products.  The following professional disciplines will benefit from completion of this eight (8) hour course:

• Engineers interested in obtaining a better understanding of how atmospheric gas burners operate and the basic design principals upon which successful operation depends.
• Engineering managers responsible for personnel dealing with gas burners and gas-fired products.
• Laboratory technicians involved with testing products using gas burners.
• Laboratory managers.
• Service personnel required to diagnose problems with products incorporating gas burners.
• Quality control specialists who wish to broaden their understanding of gas burner design.
• Sales and marketing personnel who deal with products incorporating gas burners. ( NOTE:  This is a technical course using mathematical formulas to describe basic design principals and principals of operation. )
• Reliability specialists interesting in obtaining a better understanding of gas burner design and operation.
  

Benefit to Attendees

This course is designed to provide an in-depth look at atmospheric gas burners and those design principals governing their proper use and operation.  The text, figures, formulas and tables will provide concepts critical to understanding the operation of a burner and those design relationship governing the individual components.  An individual taking this course will come away with a much better appreciation for the methodology of design.  Once knowing these various relationships, an ability to spot, diagnose and correct improper burner operation will result.  This ability may eliminate issues resulting from incomplete combustion, sooting ( carboning ) or the production of carbon monoxide in the kitchen, on the shop floor or in the office building.  With this in mind, insights into how to correct problems with burner operation will result. 

Course Introduction

Atmospheric gas burners are used in a tremendous variety of domestic and commercial applications.  Kitchen ranges, outdoor barbeque grills, gas lamps, fireplace logs, HVAC systems, gas “fan packs” for industrial heating, clothes dryers, laboratory “Bunsen” burners are just a few of the residential or domestic applications.   Many commercial applications such as “heat tunnels” for drying paint, glass-lining furnaces for baking enamel to steel substrates, generating heat to keep liquids at desired temperatures for degreasing and cleaning applications are every-day uses for high input atmospheric  power burners.  The basic operation of a burner has been well-defined and quantified over the years so that much of the “black magic”, as well as the cut-and-try, has been removed.   There are formulas to calculate orifice flow rates, primary air injection, burner flame heights, proper venturi throat diameters and other critical characteristics of burner operation.  We will investigate what makes an atmospheric gas burner perform properly and identify the “rules of the road” relative to good burner design.  We will also take a look at a burner operating improperly and discuss how to identify and fix the various problems.  The burner types and classifications will be discussed so that the student will understand the wide range of possibilities when selecting the right burner for any one given application.  We will provide enough knowledge so that an engineer, engineering manager or quality control specialist can carry on an intelligent conversation with a burner manufacturer when discussing the ins and outs of burner design and burner application to a specific product.

Course Content

The course content is in a PDF file:

Design of Atmospheric Gas Burners

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Course Summary

Gas burners are used in a wide variety of consumer and industrial products.   Practically all domestic gas burner applications and many industrial gas applications employ atmospheric gas burners.  There are basically four classifications of gas-fired burners; 1.) Normally aspirated atmospheric 2.) Power  3.) Forced and Induced Draft  4.) Premix and Pressure Power.  These are distinguished from each other solely by design.   Atmospheric gas burners use primary air, at atmospheric pressure, to combine with delivered gas, resulting in a homogenous mixture of gas and air ready for combustion. This type of burner is, by far, the most prevalent type used in today’s residential products.  The other dominant burner type, power burner, is generally dependent upon a blower to provide the necessary primary air for combustion.  An optimal ratio of gas and air is achieved to control the mixture ratio injected into the combustion chamber for eventual ignition.

Atmospheric gas burners provide an extremely reliable, inexpensive and safe method for heating, cooking, lighting and producing hot water.  We will explore and discuss how this comes about by virtue of gas burner design. 

Quiz

Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.

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DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.

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