Whether a fully automatic biomass burner with good performance can still have the same good combustion performance when installed on a boiler depends largely on whether the gas dynamic characteristics of the two are matched. Only with a good match can the performance of the biomass burner be brought into play, the stable combustion of the furnace can be ensured, the expected heat output can be achieved, and the good thermal efficiency of the boiler can be obtained.
1. Matching of gas dynamic characteristics:
A single-type fully automatic biomass burner is like a flamethrower, which sprays the flame into the furnace (combustion chamber), achieves complete combustion and outputs heat in the furnace. The biomass burner manufacturer determines the completeness of the product's combustion in a specific standard combustion chamber. Therefore, the conditions of the standard experiment are generally used as the selection conditions for the burner and the boiler. These conditions can be summarized 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 gas dynamic characteristics matching refers to the degree to which these three conditions are met.
2. Power:
The power of a biomass burner refers to how much mass (kg) or volume (m3/h, under standard conditions) of fuel it can burn per hour when 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, passes through the furnace, heat exchanger, flue gas collector and exhaust chimney to the atmosphere, forming a fluid thermal process. The hot air flow generated after combustion flows in the furnace channel with the pressure head upstream, just like water in a river, flowing downstream with the potential difference (drop, head). Because the furnace wall, channel, elbow, baffle, gorge and chimney of the furnace 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 cannot be achieved. Therefore, a certain flue gas pressure must be maintained in the furnace, which is called back pressure for the burner. For boilers without induced draft 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 biomass 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 pressure of the burner. For a specific burner, its pressure head has a maximum value, corresponding to the maximum air door and the maximum air flow state. When the air intake throttle changes, the air volume and pressure also change, and the output of the burner also changes. When the air volume is small, the pressure head is small, and when the air volume is large, the pressure head is high. For a specific boiler, when the incoming air volume is large, the flow resistance increases, which increases the back pressure of the furnace. The increase in the back pressure of the furnace suppresses the air output of the burner. Therefore, when choosing a biomass burner, you must understand its power curve and make a reasonable match.
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, and the volume of the furnace can be preliminarily determined based on 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 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. In other words, let the flames ejected by the burner have enough residence time in the furnace, because although the oil mist particles are very small (<0.01mm), they have been mixed with gas and ignited and started to burn before being 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 case of excessive exhaust CO, 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 center backfire type, the diameter of the outlet should be increased to ensure the volume occupied by the backflow gas.
The geometry of the furnace mainly affects the flow resistance and radiation uniformity of the airflow. A boiler needs to be debugged repeatedly to be well matched with the biomass burner.
Filter-For oil-fired steam boiler burners, it is required to clean the basket filter between the oil tank and the oil pump. Regular cleaning of the filter can keep the fuel from reaching the oil pump smoothly and reduce the possibility of potential component failure. Also check the filter for signs of excessive wear or damage.
Pressure regulating valve-Check the fuel pressure regulating valve or pressure reducing valve to determine whether the surface of the locking nut on the adjustable bolt is clean and removable. If the surface of the screw and nut is found to be too dirty or rusted, the regulating valve should be repaired or replaced. A poorly maintained fuel regulating valve may cause the burner to work.
Oil pump-Check the oil pump of the steam boiler burner to determine whether its sealing device is intact and whether the internal pressure can be maintained stable, and replace damaged or leaking sealing elements. If hot oil is used, it is necessary to determine whether all oil pipes are well insulated; if there are long oil pipes in the oil circuit, it is necessary to check whether the installation route is appropriate. Replace damaged and poorly insulated oil pipes.
Burners - For oil-fired steam boiler burners, clean the "y" filter. Good heavy oil and residual oil filtration is the key to preventing nozzles and valves from clogging. Check the pressure difference on the burner to see if it is working properly and the oil pressure is within the appropriate range, so that the fuel pressure can be accurately read after adjusting the burner. Adjust the atomizer extension length on the nozzle, adjust and test the low oil pressure switch.
When using heavy oil, check the oil-fired steam boiler heating and control device, and check the oil temperature switch on the burner tube group. Consult the manufacturer for the required oil viscosity to ensure the normal operation of the burner, and regularly check whether the viscosity of the heavy oil or residual oil used meets the requirements.
It is also necessary to clean and lubricate the oil valve joints. If the joints are sticky or too rough, repair or replace the steam boiler parts.
Finally, clean the nozzles regularly according to the manufacturer's requirements.
Whether a fully automatic biomass burner with good performance can still have the same good combustion performance when installed on a boiler depends largely on whether the gas dynamic characteristics of the two are matched. Only with a good match can the performance of the biomass burner be brought into play, the stable combustion of the furnace can be ensured, the expected heat output can be achieved, and the good thermal efficiency of the boiler can be obtained.
1. Matching of gas dynamic characteristics:
A single-type fully automatic biomass burner is like a flamethrower, which sprays the flame into the furnace (combustion chamber), achieves complete combustion and outputs heat in the furnace. The biomass burner manufacturer determines the completeness of the product's combustion in a specific standard combustion chamber. Therefore, the conditions of the standard experiment are generally used as the selection conditions for the burner and the boiler. These conditions can be summarized 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 gas dynamic characteristics matching refers to the degree to which these three conditions are met.
2. Power:
The power of a biomass burner refers to how much mass (kg) or volume (m3/h, under standard conditions) of fuel it can burn per hour when 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, passes through the furnace, heat exchanger, flue gas collector and exhaust chimney to the atmosphere, forming a fluid thermal process. The hot air flow generated after combustion flows in the furnace channel with the pressure head upstream, just like water in a river, flowing downstream with the potential difference (drop, head). Because the furnace wall, channel, elbow, baffle, gorge and chimney of the furnace 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 cannot be achieved. Therefore, a certain flue gas pressure must be maintained in the furnace, which is called back pressure for the burner. For boilers without induced draft 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 biomass 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 pressure of the burner. For a specific burner, its pressure head has a maximum value, corresponding to the maximum air door and the maximum air flow state. When the air intake throttle changes, the air volume and pressure also change, and the output of the burner also changes. When the air volume is small, the pressure head is small, and when the air volume is large, the pressure head is high. For a specific boiler, when the incoming air volume is large, the flow resistance increases, which increases the back pressure of the furnace. The increase in the back pressure of the furnace suppresses the air output of the burner. Therefore, when choosing a biomass burner, you must understand its power curve and make a reasonable match.
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, and the volume of the furnace can be preliminarily determined based on 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 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. In other words, let the flames ejected by the burner have enough residence time in the furnace, because although the oil mist particles are very small (<0.01mm), they have been mixed with gas and ignited and started to burn before being 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 case of excessive exhaust CO, 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 center backfire type, the diameter of the outlet should be increased to ensure the volume occupied by the backflow gas.
The geometry of the furnace mainly affects the flow resistance and radiation uniformity of the airflow. A boiler needs to be debugged repeatedly to be well matched with the biomass burner.
Filter-For oil-fired steam boiler burners, it is required to clean the basket filter between the oil tank and the oil pump. Regular cleaning of the filter can keep the fuel from reaching the oil pump smoothly and reduce the possibility of potential component failure. Also check the filter for signs of excessive wear or damage.
Pressure regulating valve-Check the fuel pressure regulating valve or pressure reducing valve to determine whether the surface of the locking nut on the adjustable bolt is clean and removable. If the surface of the screw and nut is found to be too dirty or rusted, the regulating valve should be repaired or replaced. A poorly maintained fuel regulating valve may cause the burner to work.
Oil pump-Check the oil pump of the steam boiler burner to determine whether its sealing device is intact and whether the internal pressure can be maintained stable, and replace damaged or leaking sealing elements. If hot oil is used, it is necessary to determine whether all oil pipes are well insulated; if there are long oil pipes in the oil circuit, it is necessary to check whether the installation route is appropriate. Replace damaged and poorly insulated oil pipes.
Burners - For oil-fired steam boiler burners, clean the "y" filter. Good heavy oil and residual oil filtration is the key to preventing nozzles and valves from clogging. Check the pressure difference on the burner to see if it is working properly and the oil pressure is within the appropriate range, so that the fuel pressure can be accurately read after adjusting the burner. Adjust the atomizer extension length on the nozzle, adjust and test the low oil pressure switch.
When using heavy oil, check the oil-fired steam boiler heating and control device, and check the oil temperature switch on the burner tube group. Consult the manufacturer for the required oil viscosity to ensure the normal operation of the burner, and regularly check whether the viscosity of the heavy oil or residual oil used meets the requirements.
It is also necessary to clean and lubricate the oil valve joints. If the joints are sticky or too rough, repair or replace the steam boiler parts.
Finally, clean the nozzles regularly according to the manufacturer's requirements.