Whether a fully automatic oil (gas) burner with good performance is installed on a boiler still has the same good combustion performance depends largely on whether the gas dynamic characteristics of the two match. Only a good match can give full play to the performance of the burner, ensure the stable combustion of the furnace, achieve the expected heat output, and obtain good thermal efficiency of the boiler.
1. Matching of gas dynamic characteristics
A single fully automatic burner is like a flamethrower, which sprays flames into the furnace (combustion chamber) to achieve complete combustion and output heat in the furnace; the burner manufacturer measures the combustion completeness of the product in It is carried out in a specific standard combustion chamber. Therefore, the conditions of standard experiments are generally used as the selection conditions of burners and boilers. These conditions can be summed up as follows:
(1) power;
(2) Airflow pressure in the furnace;
(3) The space size and geometry (diameter and length) of the furnace.
The so-called matching of aerodynamic 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, and also gives the corresponding heat output (kw/h or kcal/h ). The boiler is calibrated for steam production and fuel consumption, and the two must match when selected.
3 Gas pressure in the furnace
In an oil (gas) boiler, the hot air flow starts from the burner and is exhausted to the atmosphere through the furnace, heat exchanger, flue gas collector and exhaust pipe, forming a fluid thermodynamic process. The hot air flow generated after combustion, the pressure head upstream flows in the furnace channel, just like the water in the river, and flows downstream with the potential difference (drop, water head). Because the furnace wall, channel, elbow, baffle, gorge and chimney have resistance to the flow of gas (called flow resistance), it will cause pressure loss. If the pressure head cannot overcome the pressure loss along the way, the flow will be can not achieve. Therefore, a certain flue gas pressure must be maintained in the furnace, which is called back pressure for the burner. For boilers without air induction devices, the furnace pressure must be higher than the atmospheric pressure after considering the pressure head loss along the way.
The size of the back pressure directly affects the output of the burner, and the back pressure is related to the size of the furnace, the length and geometry of the flue. A boiler with a large flow resistance requires a high pressure of the burner. For a specific burner, the pressure head has a maximum value, which corresponds to the maximum damper and the 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 boiler, when the incoming air volume is large, the flow resistance will increase accordingly, which will increase the back pressure of the furnace, and the increase of the back pressure of the furnace will restrain the air output of the burner. Therefore, you must understand when choosing a burner. Its power curve is reasonably matched.
4 Influence of furnace size and geometry
For boilers, the size of the furnace space is firstly determined by the selection of the heat load intensity of the furnace during design, and the volume of the furnace can be initially determined according to it.
After the volume of the furnace is determined, its shape and size should also be determined. The design principle is to make full use of the volume of the furnace; try to avoid dead ends, have a certain depth and reasonable flow direction, and ensure sufficient reaction time to make the fuel burn completely in the furnace. In other words, let the flame sprayed out of the burner have enough residence time in the furnace, because although the oil mist particles are small (<0.01mm), the mixed gas has been ignited and started to burn before it is sprayed out of 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 lighter case, the exhaust CO will exceed the standard, and in the severe case, black smoke will be emitted, and the power will not meet the requirements. Therefore, when determining the depth of the furnace, it should conform to the length of the flame as much as possible. For the central back-burning type, the diameter of the outlet should be increased to ensure the volume occupied by the back-flowing gas.
The geometry of the furnace mainly affects the flow resistance of the airflow and the uniformity of the radiation. A boiler has to go through repeated debugging to have a good match with the burner.
Whether a fully automatic oil (gas) burner with good performance is installed on a boiler still has the same good combustion performance depends largely on whether the gas dynamic characteristics of the two match. Only a good match can give full play to the performance of the burner, ensure the stable combustion of the furnace, achieve the expected heat output, and obtain good thermal efficiency of the boiler.
1. Matching of gas dynamic characteristics
A single fully automatic burner is like a flamethrower, which sprays flames into the furnace (combustion chamber) to achieve complete combustion and output heat in the furnace; the burner manufacturer measures the combustion completeness of the product in It is carried out in a specific standard combustion chamber. Therefore, the conditions of standard experiments are generally used as the selection conditions of burners and boilers. These conditions can be summed up as follows:
(1) power;
(2) Airflow pressure in the furnace;
(3) The space size and geometry (diameter and length) of the furnace.
The so-called matching of aerodynamic 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, and also gives the corresponding heat output (kw/h or kcal/h ). The boiler is calibrated for steam production and fuel consumption, and the two must match when selected.
3 Gas pressure in the furnace
In an oil (gas) boiler, the hot air flow starts from the burner and is exhausted to the atmosphere through the furnace, heat exchanger, flue gas collector and exhaust pipe, forming a fluid thermodynamic process. The hot air flow generated after combustion, the pressure head upstream flows in the furnace channel, just like the water in the river, and flows downstream with the potential difference (drop, water head). Because the furnace wall, channel, elbow, baffle, gorge and chimney have resistance to the flow of gas (called flow resistance), it will cause pressure loss. If the pressure head cannot overcome the pressure loss along the way, the flow will be can not achieve. Therefore, a certain flue gas pressure must be maintained in the furnace, which is called back pressure for the burner. For boilers without air induction devices, the furnace pressure must be higher than the atmospheric pressure after considering the pressure head loss along the way.
The size of the back pressure directly affects the output of the burner, and the back pressure is related to the size of the furnace, the length and geometry of the flue. A boiler with a large flow resistance requires a high pressure of the burner. For a specific burner, the pressure head has a maximum value, which corresponds to the maximum damper and the 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 boiler, when the incoming air volume is large, the flow resistance will increase accordingly, which will increase the back pressure of the furnace, and the increase of the back pressure of the furnace will restrain the air output of the burner. Therefore, you must understand when choosing a burner. Its power curve is reasonably matched.
4 Influence of furnace size and geometry
For boilers, the size of the furnace space is firstly determined by the selection of the heat load intensity of the furnace during design, and the volume of the furnace can be initially determined according to it.
After the volume of the furnace is determined, its shape and size should also be determined. The design principle is to make full use of the volume of the furnace; try to avoid dead ends, have a certain depth and reasonable flow direction, and ensure sufficient reaction time to make the fuel burn completely in the furnace. In other words, let the flame sprayed out of the burner have enough residence time in the furnace, because although the oil mist particles are small (<0.01mm), the mixed gas has been ignited and started to burn before it is sprayed out of 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 lighter case, the exhaust CO will exceed the standard, and in the severe case, black smoke will be emitted, and the power will not meet the requirements. Therefore, when determining the depth of the furnace, it should conform to the length of the flame as much as possible. For the central back-burning type, the diameter of the outlet should be increased to ensure the volume occupied by the back-flowing gas.
The geometry of the furnace mainly affects the flow resistance of the airflow and the uniformity of the radiation. A boiler has to go through repeated debugging to have a good match with the burner.