Combustion chart natural gas
I want to hear from you. Tell me how we can improve. In this issue, we look at the trends affecting the development and use of rooftop and air handling units. We also examine the ways that contractors can use portable technology to grow profit and keep customers happy. This website requires certain cookies to work and uses other cookies to help you have the best experience. By visiting this website, certain cookies have already been set, which you may delete and block.
Air Fuel Ratio Effect Combustion Efficiency and Air Fuel Ratio
All substances contain varying amounts of captive energy depending on the substance and how it exists; that is, solid, liquid, or gas. Combustion is a chemical reaction. This reaction is for the purpose of releasing heat. Perfect combustion is simply a mixture of fuel and oxygen, with both being completely consumed in the burning process.
The ideal situation would be to provide just enough air in the combustion chamber to insure complete burning of the fuel. This would be true if it were physically possible to bring each atom of fuel in direct contact with the amount of air required to complete its combustion. To date, no method has been devised in a combustion chamber so that air and fuel come in complete contact in just the right proportions.
If we reduce the amount of oxygen, in a perfect mixture, we would have a fuel-rich condition. However, if we increase the amount of oxygen, in a perfect mixture, we now have excess, which does not contribute to the burning process. Having just the right amount of oxygen no more, no less is called the stoichiometric point, or stoichiometric combustion. Stoichiometric combustion is important since it is the reference point from which we can measure the efficiency of a heating unit.
Air contains Keep in mind that air consists of two parts oxygen 0 2 , along with 7. Note that. In the flue, due to the burning process, we now have:. Theoretical 0 2. Therefore, a C0 2 point of 9. For natural gas, we have an ultimate or maximum C0 2 level of:. Figure 1. For a graphical explanation of excess air, refer to Figure 1. This graph shows a typical theoretical air curve, showing the relationship between the combustion air setting on the boiler and various fuels. Figure 2. Figure 2 is known as a theoretical air curve.
The fuel lean side is a safe side. Additional measurements of either smoke or CO are recommended. In other words, a given C0 2 value can occur on either side of the stoichiometric. Excess air is the preferred term to describe the combustion setting on the safe side of the stoichiometric.
In order to arrive at the excess air value, an 0 2 measurement is performed. Figure 3. Figure 3 is a theoretical air curve chart for fuel oil. Again, C0 2 can appear on both the fuel rich and excess airsides of stoichiometric. This is a very important point worth repeating. Avoid the fuel rich side since partially burned fuel will result in carbon monoxide C0 , a gas that in large enough concentration can kill! See Figure 1 again. Note that testing for oxygen, 0 2 , insures being on the excess airside of combustion and correlates directly to C0 2 readings, regardless of the fuel being burned.
All modern electronic portable combustion analyzers use an 0 2 cell. They may be able to display C0 2 , but it will be calculated or computed from the 0 2 reading.
It should be clear that we could test a heating unit with some instruments that can measure the products of combustion, and find out how efficiently the unit is using its fuel. A combustion analysis can also diagnose problems with the burner. There is nothing mysterious about combustion efficiency. Combustion efficiency calculations start with assuming complete combustion and then applying three basic factors:. The Net Stack Temperature is the temperature that the gases are raised above the temperature of the primary and secondary air, usually ambient air temperature.
In some commercial-industrial applications, the primary air will be pre-heated. If we only want to know the efficiency of a particular burner, we need only an instrument to find percent 0 2 , a thermometer, and a combustion efficiency calculator or chart for the fuel being used. Combustion efficiency calculators, such as the Bacharach , or combustion efficiency charts see Figure 4 , have taken into consideration the heating value of a fuel, so it is only necessary to find the net stack temperature, percent 0 2 , and insert these figures into the chart or calculator.
Figure 4. Another way to look at it is to say that for about every dollar of fuel spent, 80 cents is returned as usable heat and 20 cents is going out the stack. For combustion analysis, we want to know more than just net stack temperatures and percent 0 2. Tuning a burner using those devices was very time consuming. Modern electronic combustion analyzers let you see the results of changes made during a burner tune-up immediately. They are accurate and much easier to use than oristats.
A prime example of a modern analyzer is the Bacharach Model A fully equipped can display on large LED readouts:. It can print out the data and can transfer the data to a computer. The can do all this for seven selectable fuels:. With the addition of a smoke tester, draft gauge, manometer, and oil pressure gauge, the service technician would have every instrument needed to do a complete combustion analysis, tune-up, or diagnose problems of any burner.
Using our instruments, these problems can be isolated, and through interpreting the readings, the problems can be corrected.
Only the manufacturer of a piece of equipment knows what the recommended 0 2 , net temperature, draft, etc. Government or utility regulators often set excess air settings and allowable C0 concentrations. Over fire draft of. Net stack temperatures vary according to the fuel used.
Non-condensing units are not designed to withstand condensation, so the stack temperatures must be maintained above the dew point. Rough guidelines for minimum net stack temperatures are:. A 0 PPM C0 reading is ideal, but not practical. No code or manufacturer specification allows PPM or more C0. One can reasonably expect to achieve C0 readings below PPM. A general procedure would be to complete all maintenance.
Clean the heat exchange surfaces, oil equipment, replace defective parts, etc. For burners using heavy oils, check the preheat temperature. If unknown start at o F and reduce the temperature until best combustion is achieved. Check and adjust fuel input. Operate the burner for at least 15 minutes. If a modulating burner, operate at high fire until the unit is at normal operating temperature. Check and set excess air settings. Check for C0 and smoke, if an oil burner. Reset air settings until C0 and smoke are acceptable levels, check net stack temperatures.
On modulating burners, check all settings at low fire and at several points over the firing range. Adjust as necessary. If a dual fuel burner, repeat the procedures for both fuels. The modulating boiler is a combustion system that adjusts its firing level and steam production to meet a changing output demand.
A process steam boiler is a good example of a system that has this modulating or variable firing rate capability. The Model is capable of measuring combustion efficiency at each firing rate or combustion load point. To put it simply, the Model measures all the necessary combustion process parameters and in turn automatically calculates and displays the actual combustion efficiency for each boiler operating point.
To optimize efficiency at any boiler point is quite simple. Next, plot a curve efficiency vs. Repeat the procedure at various boiler load points over the normal operating range. The procedure merely consists of adjusting the boiler in order to obtain the maximum safe combustion efficiency.
To assure continued maximum safe efficiency, regular tests are repeated to ensure proper handling of the key parameter variations. A random variation in the humidity, for example, can cause the concentration of oxygen in the air to vary from This humidity factory will cause a variation in the oxygen measurement of. This difference will result in a corresponding change in combustion efficiency of.
Using the Model to spot check these combustion parameters ensures that the process does not change and become unsafe. Knowing the amount of combustibles present, determining the operating conditions over a range of fuel compositions, noting ambient temperature variations, and knowing the current humidity will allow the boiler set points to be maintained. The correct operating parameters must be determined at each load condition.
Graphing efficiency vs. In small automatic control systems, a jackshaft is used for modulating control. A modulating motor controls each load position in order to automatically adjust to air and fuel linkage. Here again, use the Model to determine the correct operating conditions.
This procedure, in other words, is repeated for each desired load point.
Water (H2O) is always present in natural gas and oil combustion in residential generalized by the following chart and guidelines provided the installation is. 5 - 10% for natural gas; 5 - 20% for fuel oil; 15 - 60% for coal. Carbon dioxide - CO2 - is a combustion product and.
With the introduction of new and improved combustion test instruments, many technicians are asking what the real difference is between measuring oxygen and measuring carbon dioxide. Is one method better than the other? Is the end result the same? To answer these questions, we will present a simple comparison, and will discuss the differences and similarities that exist.
In part two of this series on combustion control of industrial heat sources, we consider the air fuel ratio and the balance of using excess air to consume combustibles while minimizing energy from going up the stack in industrial heating sources.
Natural gas also called fossil gas is a naturally occurring hydrocarbon gas mixture consisting primarily of methane , but commonly including varying amounts of other higher alkanes , and sometimes a small percentage of carbon dioxide , nitrogen , hydrogen sulfide , or helium. The energy that the plants originally obtained from the sun is stored in the form of chemical bonds in the gas. Natural gas is a non-renewable [3] hydrocarbon used as a source of energy for heating, cooking, and electricity generation.
Flue Gas Analysis Table
All substances contain varying amounts of captive energy depending on the substance and how it exists; that is, solid, liquid, or gas. Combustion is a chemical reaction. This reaction is for the purpose of releasing heat. Perfect combustion is simply a mixture of fuel and oxygen, with both being completely consumed in the burning process. The ideal situation would be to provide just enough air in the combustion chamber to insure complete burning of the fuel.
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COVID update , learn more. Natural gas is a naturally occurring gas mixture, consisting mainly of methane. While the gas from these sources has a similar analysis, it is not entirely the same. The table below outlines the typical components of natural gas on our system and the typical ranges for these values allowing for the different sources. Note that there is no guarantee of the following composition at your location or as an overall system average. Since the different gas supplies enter the Enbridge Gas system at different locations, the exact composition at any site will vary among the different regions and over time. The system average heating value will depend on the mix of gas supplies which is increasingly controlled by our customers , and therefore can vary from the typical value listed below. Note that there is no guarantee that the combustion properties at your location will be exactly as shown. The properties shown are an overall average on the Enbridge Gas system.
To ensure complete combustion of the fuel used combustion chambers are supplied with excess air. Excess air increase the amount of oxygen to the combustion and the combustion of fuel.
A gas burner is a device that produces a controlled flame by mixing a fuel gas such as acetylene , natural gas , or propane with an oxidizer such as the ambient air or supplied oxygen , and allowing for ignition and combustion. The flame is generally used for the heat, infrared radiation, or visible light it produces. Some burners, such as gas flares , dispose of unwanted or uncontainable flammable gases.
