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The Three T s of Combustion






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The Three T s of Combustion

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1. The Three T?s of Combustion This slide collage is also moved forward from the combustion section. Time Temperature and Turbulence. There is a limited amount of time for fuel and air to mix through turbulation before ignition. This is critical and establishes time, temperature and pressure constraints as gas passes through the orifice and in transformation out of the heat exchange and venting system. Interruptions or deviations in time and pressure passage requirements can lead to imbalanced fuel/air/temperatures and CO is generated. There is a limited amount of time for the combustible mixture to be in flame or heat. There is a limited amount of time for heat exchange and venting of combustion gases. The fuel is under pressure, the ?Timekeeper?. The steady flow of combustion gases is critical through all phases of the action. It has been suggested that a fluctuating chimney or draft pressure is acceptable specifically on warmer days. The point is always to remember that if you change the exhaust pressure, you can destabilize combustion pressure and generate foreseeable harmful carbon monoxide gases. The meter size should be established with reference to the load, perhaps foreseeable load. The fuel gas piping should be appropriately sized to handle the load as well.This slide collage is also moved forward from the combustion section. Time Temperature and Turbulence. There is a limited amount of time for fuel and air to mix through turbulation before ignition. This is critical and establishes time, temperature and pressure constraints as gas passes through the orifice and in transformation out of the heat exchange and venting system. Interruptions or deviations in time and pressure passage requirements can lead to imbalanced fuel/air/temperatures and CO is generated. There is a limited amount of time for the combustible mixture to be in flame or heat. There is a limited amount of time for heat exchange and venting of combustion gases. The fuel is under pressure, the ?Timekeeper?. The steady flow of combustion gases is critical through all phases of the action. It has been suggested that a fluctuating chimney or draft pressure is acceptable specifically on warmer days. The point is always to remember that if you change the exhaust pressure, you can destabilize combustion pressure and generate foreseeable harmful carbon monoxide gases. The meter size should be established with reference to the load, perhaps foreseeable load. The fuel gas piping should be appropriately sized to handle the load as well.

2. Combustion needs: Air Fuel Ignition (Heat) A look at our chemistry of heat: What components are needed for Combustion to occur? Fuel Air/Oxygen Heat/Ignition Air contains oxygen (O2) and nitrogen (N). Oxygen reacts to heat, Nitrogen does not. 20.9% of our air is Nitrogen while 79% is Nitrogen.A look at our chemistry of heat: What components are needed for Combustion to occur? Fuel Air/Oxygen Heat/Ignition Air contains oxygen (O2) and nitrogen (N). Oxygen reacts to heat, Nitrogen does not. 20.9% of our air is Nitrogen while 79% is Nitrogen.

3. Controlling Combustion Burners require controlled fuel to be mixed with specific amounts of air. Controlled combustion requires. A specific and controlled amount of fuel. (Known BTU values, specific pipe, manifold and orifice pressures, pipe sizing, meters and regulators sized to load predictions.) Specific amounts of air to mix with the fuel. (Fuel without air will not heat in the chemical reaction or ?burn?.) (Air contains oxygen (O2) and nitrogen (N). Oxygen reacts to heat, Nitrogen does not though absorbs heat.) 20.9% of our air is Nitrogen while 79% is Nitrogen. 3. And ignition sources. (Pilot, hot surface igniter, spark ignition) Heat is a chemical reaction of the C?s (carbon fuels), the H?s (hydrogen) and the O?s (oxygen) and the N?s (nitrogen). Our chemical map is complete for this type of fuel structure. We can explore measuring these gases in the temperatures they react in and discover the sources and generative causes of CO. Complete Combustion, note by products of O2, CO2 (the same thing humans breathe out; humans are combustion systems that eat fuel, convert it to energy & heat and exhaust CO2 as a by-product.) H2O water vapor and N (nitrogen). There may be instances where NO or NO2 would be formed as well. Incomplete Combustion, includes all of what is in complete combustion but because of some varying or maladjusted condition CO is also generated. In this controlled combustion setting, fuel is known, piping and fuel line pressures are complete and verified to appropriate code and manufacturer specifications. Orifice and nozzle size is installed to fuel type and elevation requirements. A complete sweep of fuel & air into the heat, chemically changed and out of the heat occurs without interruption. This process remains in this controlled state until there is an interruption of the fuel, air or heat and combustion stops. Controlled combustion requires. A specific and controlled amount of fuel. (Known BTU values, specific pipe, manifold and orifice pressures, pipe sizing, meters and regulators sized to load predictions.) Specific amounts of air to mix with the fuel. (Fuel without air will not heat in the chemical reaction or ?burn?.) (Air contains oxygen (O2) and nitrogen (N). Oxygen reacts to heat, Nitrogen does not though absorbs heat.) 20.9% of our air is Nitrogen while 79% is Nitrogen. 3. And ignition sources. (Pilot, hot surface igniter, spark ignition) Heat is a chemical reaction of the C?s (carbon fuels), the H?s (hydrogen) and the O?s (oxygen) and the N?s (nitrogen). Our chemical map is complete for this type of fuel structure. We can explore measuring these gases in the temperatures they react in and discover the sources and generative causes of CO. Complete Combustion, note by products of O2, CO2 (the same thing humans breathe out; humans are combustion systems that eat fuel, convert it to energy & heat and exhaust CO2 as a by-product.) H2O water vapor and N (nitrogen). There may be instances where NO or NO2 would be formed as well. Incomplete Combustion, includes all of what is in complete combustion but because of some varying or maladjusted condition CO is also generated. In this controlled combustion setting, fuel is known, piping and fuel line pressures are complete and verified to appropriate code and manufacturer specifications. Orifice and nozzle size is installed to fuel type and elevation requirements. A complete sweep of fuel & air into the heat, chemically changed and out of the heat occurs without interruption. This process remains in this controlled state until there is an interruption of the fuel, air or heat and combustion stops.

4. Visualize the combustion triangle on every system. Top Picture 1. Open flame, fuel air mixture without interruption, and limited amount of CO production. (Test one in your lab.) Left Picture 2. Pot of cold water placed over flame, creates a smaller zone for the combustion process interrupting the reaction and pushing unburned fuel from the hot combustion zone. Cold surface of the pot absorbs heat increasing the amount of time needed to burn all fuel. Measure CO along side pan with hose & probe attachment, see high CO in PPM. Picture 3. With an increase in the surface temperature of the pot additional heat is added back into the flame and a more complete burning of the fuel occurs. Test for CO again with hose & probe assembly attachment and note reduction in CO generation.Visualize the combustion triangle on every system. Top Picture 1. Open flame, fuel air mixture without interruption, and limited amount of CO production. (Test one in your lab.) Left Picture 2. Pot of cold water placed over flame, creates a smaller zone for the combustion process interrupting the reaction and pushing unburned fuel from the hot combustion zone. Cold surface of the pot absorbs heat increasing the amount of time needed to burn all fuel. Measure CO along side pan with hose & probe attachment, see high CO in PPM. Picture 3. With an increase in the surface temperature of the pot additional heat is added back into the flame and a more complete burning of the fuel occurs. Test for CO again with hose & probe assembly attachment and note reduction in CO generation.

5. COMBUSTION 101 for EVERYONE The basic scenario: The wick is lit and heat transforms the wax to a gas that drafts around, up and through the wick. The gas around the wick enters the heat of the flame, is ignited and combustion is maintained as long as this process continues with the fuel, air and heat. There is quality of fuel and its? regulated delivery is consistent. There is limited CO production. There is an un-interrupted sweep of this combustion activity.The basic scenario: The wick is lit and heat transforms the wax to a gas that drafts around, up and through the wick. The gas around the wick enters the heat of the flame, is ignited and combustion is maintained as long as this process continues with the fuel, air and heat. There is quality of fuel and its? regulated delivery is consistent. There is limited CO production. There is an un-interrupted sweep of this combustion activity.

6. Combustion Maintained & Clean

7. AIR REDUCTION By lowering a jar over the flame just to the point where the flame weakens but stays lit, an increase in CO production occurs. (Measure CO with test instrument) ?What happens to the gas production and the draft through the wick & flame as the flame begins to flatten?? To burn completely, this fuel needs more air. In homes & buildings air for combustion may be taken from inside the living space and may not be replaced or replenished at the same rate as it is being used up for combustion and human use. Solving one problem (sealing up a home to save energy) can create another one (CO production and the flame?s search for combustion air). I enter into a discussion about homes, recreation habitats, buildings, etc. being jars. Get the scientist to think about what happens when you tighten up a home to save energy and then turn on motorized exhaust fans and run a gas water heater all at the same time. The main point of the slide is to show the process of air requirements in combustion, how CO can be generated and how homes & buildings can play a part.By lowering a jar over the flame just to the point where the flame weakens but stays lit, an increase in CO production occurs. (Measure CO with test instrument) ?What happens to the gas production and the draft through the wick & flame as the flame begins to flatten?? To burn completely, this fuel needs more air. In homes & buildings air for combustion may be taken from inside the living space and may not be replaced or replenished at the same rate as it is being used up for combustion and human use. Solving one problem (sealing up a home to save energy) can create another one (CO production and the flame?s search for combustion air). I enter into a discussion about homes, recreation habitats, buildings, etc. being jars. Get the scientist to think about what happens when you tighten up a home to save energy and then turn on motorized exhaust fans and run a gas water heater all at the same time. The main point of the slide is to show the process of air requirements in combustion, how CO can be generated and how homes & buildings can play a part.

8. FUEL, AIR, HEAT; TAKE ONE AWAY AND COMBUSTION STOPS With the jar completely over the candle combustion stops once the air is totally used up. Time Temperature Turbulence Fuel, air and ignition heat are all needed for combustion to occur; take one away & combustion stops.With the jar completely over the candle combustion stops once the air is totally used up. Time Temperature Turbulence Fuel, air and ignition heat are all needed for combustion to occur; take one away & combustion stops.

9. How Many Potential Sources of CO? How tight is our jar? Solve one problem, create another! CO may be generated from one or several sources, perhaps from outside the building. Air that moves through ductwork can pick up CO from any of these sources. Measuring air in duct work does not mean pollutants are coming from the furnace, just that they are distributed by the duct system. Perhaps the pressures in the duct work conflict with building pressures and compromise combustion system exhaust pressures which result in CO generation through the disruption of the flow of the Combustion Triangle.CO may be generated from one or several sources, perhaps from outside the building. Air that moves through ductwork can pick up CO from any of these sources. Measuring air in duct work does not mean pollutants are coming from the furnace, just that they are distributed by the duct system. Perhaps the pressures in the duct work conflict with building pressures and compromise combustion system exhaust pressures which result in CO generation through the disruption of the flow of the Combustion Triangle.

10. Why wait for the alarm or injury? Entry testing may decrease the frequency of CO poisoning. Always test air outside before entering; establish base reference. Pro-active testing; the more you test, the more you will find to fix. Pro-active testing; the more you test, the more you will find to fix.

11. Major Sources of Carbon Monoxide For years, gas companies, fire departments, HVACRE companies and others have gone on CO source investigations as a result of CO alarms or other complaints. Often time mechanical equipment is examined, adjusted or replaced even though the generating source could be the combination of automobile exhaust and competing building pressures. One study out of Minnesota at the former Minnegasco Company showed that around 60% of their CO responses to their customers were due to automotive exhaust influences in the building. People often have habits that include leaving their cars running inside an attached garage with the doors open for only a few minutes before the car exits and the large doors are automatically closed by a visor switch of some kind. CO laden auto exhaust is enclosed inside that now vacant space. Building pressure influences where it works its way inside the living structure because of natural convection currents of airflow. The Fyrite Pro 125 has a differential pressure sensor and the positive or negative or neutral pressure of a home or building can be determined within moments of entering and then through out the time in the building.For years, gas companies, fire departments, HVACRE companies and others have gone on CO source investigations as a result of CO alarms or other complaints. Often time mechanical equipment is examined, adjusted or replaced even though the generating source could be the combination of automobile exhaust and competing building pressures. One study out of Minnesota at the former Minnegasco Company showed that around 60% of their CO responses to their customers were due to automotive exhaust influences in the building. People often have habits that include leaving their cars running inside an attached garage with the doors open for only a few minutes before the car exits and the large doors are automatically closed by a visor switch of some kind. CO laden auto exhaust is enclosed inside that now vacant space. Building pressure influences where it works its way inside the living structure because of natural convection currents of airflow. The Fyrite Pro 125 has a differential pressure sensor and the positive or negative or neutral pressure of a home or building can be determined within moments of entering and then through out the time in the building.

12. 2nd leading common cause of CO found in homes and buildings; Unvented combustion systems Regardless of the size of the combustion system, the dynamics are the same. Air & fuel mix before combustion, it is ignited and the burner fills with flame. The flame contacts a flame spreader. The cooking oven area heats up, we cook our food with combustion gases and the combustion gas then exits out of the oven, into the kitchen air and if the home has a forced air distribution system, the gases get pulled through the return air and then distributed throughout the structure. This temperature shock at start-up in this turbulent flow of pressurized gases disrupts combustion and impingement caused carbon monoxide is usually generated. This can go away as the surface heats up sufficiently or continuous relatively high levels of CO can be generated. Combustion gas tests are always taken in undiluted flue gases. As air is drawn in so can dust balls, spiders get in there. Moisture of combustion gases or other sources can help plug burners over time, so can grease & oil or food carbon deposits. The burner can begin to have problems. Non-professional installations, bought over the counter, bounced out of vehicles, up stairs, gas lines attached, fired and they heat up and cook food; never to be looked at by a service professional (until it doesn?t work right). These unvented systems have demonstrated to be randomly high generators and distributors of carbon monoxide. It is not uncommon to ?peg? a carbon monoxide test instrument at the start-up of a gas cooking oven. If CO levels do not drop soon after start-up and continue to producer high levels of CO, the unit should be repaired. High levels can be referenced to local Authority Having Jurisdiction levels. The levels that the paying customer wants may be lower than what the Authority says is allowable. Remember, we are not all of equal health and one level of CO is not necessarily the best for everyone. Regardless of the size of the combustion system, the dynamics are the same. Air & fuel mix before combustion, it is ignited and the burner fills with flame. The flame contacts a flame spreader. The cooking oven area heats up, we cook our food with combustion gases and the combustion gas then exits out of the oven, into the kitchen air and if the home has a forced air distribution system, the gases get pulled through the return air and then distributed throughout the structure. This temperature shock at start-up in this turbulent flow of pressurized gases disrupts combustion and impingement caused carbon monoxide is usually generated. This can go away as the surface heats up sufficiently or continuous relatively high levels of CO can be generated. Combustion gas tests are always taken in undiluted flue gases. As air is drawn in so can dust balls, spiders get in there. Moisture of combustion gases or other sources can help plug burners over time, so can grease & oil or food carbon deposits. The burner can begin to have problems. Non-professional installations, bought over the counter, bounced out of vehicles, up stairs, gas lines attached, fired and they heat up and cook food; never to be looked at by a service professional (until it doesn?t work right). These unvented systems have demonstrated to be randomly high generators and distributors of carbon monoxide. It is not uncommon to ?peg? a carbon monoxide test instrument at the start-up of a gas cooking oven. If CO levels do not drop soon after start-up and continue to producer high levels of CO, the unit should be repaired. High levels can be referenced to local Authority Having Jurisdiction levels. The levels that the paying customer wants may be lower than what the Authority says is allowable. Remember, we are not all of equal health and one level of CO is not necessarily the best for everyone.

13. Unvented Systems, Living in a chimney! How much carbon dioxide CO2 is too much? Un-vented systems allow people to live in chimneys and witness firsthand the combustion process. Some systems burn dirty to look pretty. Please note that combustion gases are now in breathable air. The displacement of fresh air with a combustion gas may be harmful to the health of some people particularly anyone with heart or respiratory disease, elderly, infants and women pregnant, perhaps others. How do we control combustion? What do we measure and how do we control the process? How do we measure it?Un-vented systems allow people to live in chimneys and witness firsthand the combustion process. Some systems burn dirty to look pretty. Please note that combustion gases are now in breathable air. The displacement of fresh air with a combustion gas may be harmful to the health of some people particularly anyone with heart or respiratory disease, elderly, infants and women pregnant, perhaps others. How do we control combustion? What do we measure and how do we control the process? How do we measure it?

14. CO2 LEVELS OF COMFORT IN PARTS PER MILLION Normal outside levels 380-450 PPM Acceptable levels indoors less than 600 PPM Increased complaints of stuffiness and odors 600 to 1000 PPM ASHRAE and OSHA standards 1000 PPM Increased complaints of general drowsiness 1000 to 2500 PPM Adverse health effects 2500 to 5000 PPM Max allowable concentration for 8 hour period 5000 PPM PLEASE NOTE: Combustion analyzers traditionally only calculate CO2 in flue gasses and are not designed for ambient CO2 measurement unless designated as such by the manufacturer. QUESTION: Do you know what levels of CO2 you live, work, go to school or experience everyday during your indoor time? Want to be surprised? It is not uncommon for single family residences to contain over 2000 PPM of CO2 when occupied to normal household levels. The leakier the house, the lower the levels. The more ?energy efficient? the structure, the more likelihood the CO2 levels will also be higher. The house as a jar example.It is not uncommon for single family residences to contain over 2000 PPM of CO2 when occupied to normal household levels. The leakier the house, the lower the levels. The more ?energy efficient? the structure, the more likelihood the CO2 levels will also be higher. The house as a jar example.


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