Whether a fully automatic oil (gas) burner (Burner) with good performance still has the same good combustion performance when installed on a boiler depends largely on whether the gas dynamic characteristics of the two match. Only good matching can bring out the performance of the burner, ensure the stable combustion of the furnace, achieve the expected heat energy output, and obtain good thermal efficiency of the boiler.
1. Matching of gas dynamic characteristics
A single fully automatic burner is like a flame thrower, which sprays flame into the furnace (combustion chamber) to achieve complete combustion and output heat in the furnace; the burner manufacturer measures the completeness of combustion of the product in carried out in a specific standard combustion chamber. Therefore, the conditions of standard experiments are generally used as the selection conditions for burners and boilers. These conditions can be summarized as follows:
(1)Power;
(2) Air flow pressure in the furnace;
(3) The space size and geometry (diameter and length) of the furnace.
The so-called matching of gas dynamic characteristics refers to the degree to which these three conditions are met.
2. Power
The power of the burner refers to how much mass (kg) or volume (m3/h, under standard conditions) of fuel it can burn per hour when it is fully burned. It also gives the corresponding thermal energy output (kw/h or kcal/h). ). The boiler is calibrated for steam production and fuel consumption. The two must match when selecting.
3. Gas pressure in the furnace
In an oil (gas) boiler, the hot gas flow starts from the burner, passes through the furnace, heat exchanger, flue gas collector and exhaust pipe and is discharged to the atmosphere, forming a fluid thermal process. The hot air flow generated after combustion flows in the furnace channel depending on the pressure head upstream, just like water in a river, flowing downstream depending on the head height difference (drop, water head). Since the furnace walls, channels, elbows, baffles, gorges and chimneys all have resistance to the flow of gas (called flow resistance), this will cause pressure loss. If the pressure head cannot overcome the pressure losses along the way, flow will not be achieved. Therefore, a certain flue gas pressure must be maintained in the furnace, which is called back pressure for burners. For boilers without draft devices, the furnace pressure must be higher than atmospheric pressure after considering the head loss along the way.
The size of the back pressure directly affects the output of the burner. The back pressure is related to the size of the furnace, the length and geometry of the flue. Boilers with large flow resistance require high burner pressure. For a specific burner, its pressure head has a maximum value, which corresponds to the maximum damper and maximum air flow state. When the intake throttle changes, the air volume and pressure also change, and the output of the burner also changes. The pressure head is small when the air volume is small, and the pressure head is high when the air volume is large. For a specific pot, when the incoming air volume is large, the flow resistance increases, which increases the back pressure of the furnace. The increase of the back pressure of the furnace inhibits the air output of the burner. Therefore, you must understand when choosing a burner. Its power curve is reasonably matched.
4. The influence of the size and geometry of the furnace
For boilers, the size of the furnace space is first determined by the selection of the heat load intensity of the furnace during design, based on which the volume of the furnace can be preliminarily determined.
After the furnace volume is determined, its shape and size should also be determined. The design principle is to make full use of the furnace volume; try to avoid dead corners, have a certain depth and reasonable flow direction, and ensure sufficient reaction time so that the fuel can be completely burned in the furnace and replaced. In other words, let the flame ejected from the burner have enough residence time in the furnace, because although the oil mist particles are very small (<0.01mm), the gas mixture has been ignited and started to burn before it is ejected from the burner, but it is not sufficient. If the furnace is too shallow and the residence time is not enough, incomplete combustion will occur. In the smallest case, the exhaust CO will exceed the standard, and in the worst case, black smoke will be emitted, and the power will not meet the requirements. Therefore, when determining the depth of the furnace, it should be as consistent as possible with the length of the flame. For the central backfire type, the diameter of the outlet should be increased to ensure the volume occupied by the return gas.
The geometry of the furnace mainly affects the flow resistance of the air flow and the uniformity of radiation. A boiler must undergo repeated debugging before it can match well with the burner.
Whether a fully automatic oil (gas) burner (Burner) with good performance still has the same good combustion performance when installed on a boiler depends largely on whether the gas dynamic characteristics of the two match. Only good matching can bring out the performance of the burner, ensure the stable combustion of the furnace, achieve the expected heat energy output, and obtain good thermal efficiency of the boiler.
1. Matching of gas dynamic characteristics
A single fully automatic burner is like a flame thrower, which sprays flame into the furnace (combustion chamber) to achieve complete combustion and output heat in the furnace; the burner manufacturer measures the completeness of combustion of the product in carried out in a specific standard combustion chamber. Therefore, the conditions of standard experiments are generally used as the selection conditions for burners and boilers. These conditions can be summarized as follows:
(1)Power;
(2) Air flow pressure in the furnace;
(3) The space size and geometry (diameter and length) of the furnace.
The so-called matching of gas dynamic characteristics refers to the degree to which these three conditions are met.
2. Power
The power of the burner refers to how much mass (kg) or volume (m3/h, under standard conditions) of fuel it can burn per hour when it is fully burned. It also gives the corresponding thermal energy output (kw/h or kcal/h). ). The boiler is calibrated for steam production and fuel consumption. The two must match when selecting.
3. Gas pressure in the furnace
In an oil (gas) boiler, the hot gas flow starts from the burner, passes through the furnace, heat exchanger, flue gas collector and exhaust pipe and is discharged to the atmosphere, forming a fluid thermal process. The hot air flow generated after combustion flows in the furnace channel depending on the pressure head upstream, just like water in a river, flowing downstream depending on the head height difference (drop, water head). Since the furnace walls, channels, elbows, baffles, gorges and chimneys all have resistance to the flow of gas (called flow resistance), this will cause pressure loss. If the pressure head cannot overcome the pressure losses along the way, flow will not be achieved. Therefore, a certain flue gas pressure must be maintained in the furnace, which is called back pressure for burners. For boilers without draft devices, the furnace pressure must be higher than atmospheric pressure after considering the head loss along the way.
The size of the back pressure directly affects the output of the burner. The back pressure is related to the size of the furnace, the length and geometry of the flue. Boilers with large flow resistance require high burner pressure. For a specific burner, its pressure head has a maximum value, which corresponds to the maximum damper and maximum air flow state. When the intake throttle changes, the air volume and pressure also change, and the output of the burner also changes. The pressure head is small when the air volume is small, and the pressure head is high when the air volume is large. For a specific pot, when the incoming air volume is large, the flow resistance increases, which increases the back pressure of the furnace. The increase of the back pressure of the furnace inhibits the air output of the burner. Therefore, you must understand when choosing a burner. Its power curve is reasonably matched.
4. The influence of the size and geometry of the furnace
For boilers, the size of the furnace space is first determined by the selection of the heat load intensity of the furnace during design, based on which the volume of the furnace can be preliminarily determined.
After the furnace volume is determined, its shape and size should also be determined. The design principle is to make full use of the furnace volume; try to avoid dead corners, have a certain depth and reasonable flow direction, and ensure sufficient reaction time so that the fuel can be completely burned in the furnace and replaced. In other words, let the flame ejected from the burner have enough residence time in the furnace, because although the oil mist particles are very small (<0.01mm), the gas mixture has been ignited and started to burn before it is ejected from the burner, but it is not sufficient. If the furnace is too shallow and the residence time is not enough, incomplete combustion will occur. In the smallest case, the exhaust CO will exceed the standard, and in the worst case, black smoke will be emitted, and the power will not meet the requirements. Therefore, when determining the depth of the furnace, it should be as consistent as possible with the length of the flame. For the central backfire type, the diameter of the outlet should be increased to ensure the volume occupied by the return gas.
The geometry of the furnace mainly affects the flow resistance of the air flow and the uniformity of radiation. A boiler must undergo repeated debugging before it can match well with the burner.