As a company that has been deeply engaged in the production and supply of industrial boilers for many years, we know better than anyone else that boiler ignition and commissioning is the most critical and risky part of the equipment delivery. Industrial boiler as the core thermal energy equipment, ignition fuel, electricity, water vapor system synchronization linkage, even a small negligence, not only will damage the equipment itself, but also may cause safety accidents, affecting the customer's production schedule.
Many people think that “pre-ignition inspection” is to go through the process, too much trouble to save steps, but do not know, this step is precisely the key to save life and equipment. Today, combined with my years of hands-on experience, to talk to you about those things before the boiler ignition inspection.
First of all, to tell you a concept: industrial boiler ignition commissioning, not daily startup so simple. It specifically refers to the boiler installation, maintenance after the first ignition, or long-term shutdown after the resumption of ignition, the entire boiler system to do a comprehensive test and debugging, the purpose is to ensure that the boiler can be normal ignition, stable combustion, to achieve the designed operating parameters.
Daily start furnace is a boiler after normal shutdown, according to a fixed process to resume operation, the system would have been in a stable state, the operation is relatively routine; but ignition debugging is different, either new equipment, or overhaul of the equipment, the components, the system has not been the actual operation of the coordination of the test, the uncertainty is particularly large.
Because of this, the system check before ignition must be done. Otherwise, a little deviation in the installation, a small failure of a component, or a little clogging in the pipeline, ignition may become a big hidden danger, and even cause safety accidents.
I have seen too many accidents caused by the lack of checking before ignition, which is heartbreaking to say. For example, the residual combustible gases in the furnace, did not clean up, a little fire on the occurrence of deflagration; there is because the water level did not check the water level is too low, ignition of the heating surface after dry burning, directly to the furnace tube burned deformed, burned cracked.
The root cause of these accidents, in fact, is a small negligence, think “should be fine” “never checked before”, save a few checking steps, and finally have to pay a terrible price. Insufficient inspection before ignition brings many risks, not only may damage the equipment, delay production, and more importantly, will threaten the life safety of the operators on site.
For us to do operation and maintenance people, pre-ignition inspection, is to give the boiler ignition commissioning on a “safety lock”. Do this step, both to avoid accidents when ignition, but also to ensure the stability of the subsequent operation of the boiler to reduce the cost of operation and maintenance of the latter, is “twice the result with half the effort” thing.
Before ignition, the first thing to check is the water level, which is the most basic and most easily overlooked point. The water level must be controlled between 1/2 and 2/3 of the water level meter, and at the same time, make sure that the water level meter is clear, not clogged, and the displayed value is accurate, so don't misjudge the problem because of the water level.
Then the water pump, start a try, listen to whether there is no abnormal noise, there is no obvious vibration, sealing is good, can not stabilize the water supply. There are also a variety of valves for the water supply system, to check one by one to ensure that the switch is flexible, the position is correct, there is no leakage, the water flow should also be able to meet the demand for boiler ignition and initial operation.
Here is a reminder: check the water level and water supply system, the core is to prevent the boiler from dry burning. After the boiler ignition, the heating surface will heat up quickly, if the water level is not enough at this time, or the water supply system failure, can not make up water in time, the furnace tube is easy to overheat and damage, maintenance and costly and time-consuming.
Before ignition, you must enter the furnace chamber and combustion chamber to take a look at the inside, there can not be any debris, nor can there be residual fuel, especially flammable and explosive things, must be cleaned up. Otherwise, after ignition, these debris will burn up and easily lead to localized overheating and even cause a fire.
The manholes and inspection doors of the furnace and combustion chamber should also be checked in place to ensure that they are well sealed and cannot leak air or gas. If the seal is not tight, cold air will seep in, affecting the stability of the furnace chamber temperature and combustion, while the flue gas may also leak out, polluting the environment, not to mention the potential safety hazards.
In addition, the flue gas passage should be confirmed to be smooth, not blocked, and not too much ash accumulation. Only if the flue gas can be discharged smoothly, the normal negative pressure can be maintained in the furnace chamber, so as to provide sufficient space for fuel combustion and avoid the situation of flue gas backflow.
The fuel types of the boiler are different, and the focus of the check is also different, but the core is to ensure that the fuel supply is stable and free of leakage. If it is a gas boiler, the gas pipeline should be carefully inspected to see if there is any breakage or leakage, and the gas pressure gauge should be normal, and the pressure should be stabilized within the design range.
If it is an oil-fired boiler, we should check the fuel storage tank level is enough, the oil pipeline is not smooth, the fuel filter is not clogged, the position of the various valves is not correct, can be normal switch to ensure that the fuel can be a continuous supply, not interrupted. Coal-fired boilers, then we need to check the coal system and coal storage silo, to ensure that the coal is sufficient to ensure that the transportation equipment can operate normally.
Fuel supply problems, ignition will certainly fail, and may even be due to fuel leakage, triggering deflagration, poisoning and other safety accidents, so this step must be careful, not sloppy.
Ignition device is the “key player” of the boiler ignition, whether it can ignite at once, it all depends on it. To focus on checking the ignition electrode and igniter, to see if the electrode is damaged, there is no carbon buildup, the igniter can produce normal sparks, ignition energy enough.
Also check the ignition electrode and igniter installation position, if the position is not right, the spark can not point to the fuel, also can not light the fire. In addition, the electrode and the pilot surface of the ash, oil, should also be cleaned up, otherwise it will affect the ignition effect, resulting in ignition failure.
Burner can not forget, check it installed firmly, there is no loosening, nozzle is not clogged, wear, can not normally spray fuel, and the air is fully mixed. Only fuel and air mixed evenly, the success rate of ignition is high, but also to avoid the situation of incomplete combustion.
Fuel combustion cannot be separated from air, so the inspection of air supply and induced air system is also very critical. Before ignition, start the air supply fan and induced draft fan, listen to whether there is any abnormal noise, see whether the vibration is normal or not, whether the temperature of the bearing is in a reasonable range, whether the motor is running smoothly or not, and whether it can start and stop normally.
Then the baffle of the air supply and induced draft system, make sure that the opening of the baffle meets the design requirements, the switch is flexible, and the air volume can be adjusted according to the demand of combustion. Also check the negative pressure of the furnace chamber to ensure that the negative pressure in the normal range, negative pressure is too high or too low, will affect the stability of combustion.
Here to tell you a little common sense: insufficient air supply, the fuel will not be burned fully, and waste of fuel, but also produce harmful gases; insufficient induced draft, the smoke can not be discharged, the pressure in the furnace chamber is too high, which will lead to flue gas leakage. So the ventilation system check, must be done.
Furnace blowing is an important safety step before ignition, which must not be saved. According to the specification requirements, the blowing time should not be less than 5 minutes, and it must be blown thoroughly to exhaust all the residual combustible gases and dust in the furnace chamber and flue.
When blowing, but also check the blowing air volume is enough, if the air volume is not enough, it will not be able to exhaust all the combustible substances in the furnace chamber. These combustible gases accumulate in the furnace chamber, and once the fire is ignited, deflagration will occur, with unimaginable consequences.
Pre-ventilation is also very important to make sure that the ventilation system is operating properly and can provide sufficient fresh air to the furnace chamber, on the one hand, to prepare for ignition and combustion, and on the other hand, it can also further discharge the residual combustible gases, which doubly guarantees the safety of ignition.
boiler ignition commissioning, a variety of instruments and control systems, is our “eyes” and “brain”, must be accurate and reliable. To comprehensively check the pressure, temperature, water level and other instruments to confirm that the meter display is accurate, no deviation, and calibration qualified, within the validity period.
Also check the signal transmission of the instrumentation to ensure that the instrumentation can be timely and accurate boiler operating parameters, feedback to the control system; control system should also be normal, can smoothly receive and process signals, response in a timely manner, there can be no jamming, malfunctioning of the situation.
Only the instrumentation and control system ready, we can real-time monitoring of the parameters in the ignition process, once found that the water level is abnormal, the pressure is too high or too low, we can take timely measures to avoid accidents.
safety interlocks and protection devices, is the boiler's “life-saving defense”, before ignition must be carefully checked, test. Focus on checking the low water level protection, overpressure protection, flame failure protection of these devices, to confirm that they are intact, sensitive, and can play a normal role.
You can simulate anomalies, such as simulating low water level, overpressure, flameout, to see if these protective devices can trigger timely interlocking actions, such as cutting off fuel supply, stopping the boiler operation. Only in this way can we ensure that the boiler can automatically shut down in the event of an emergency to avoid the expansion of the accident.
Here must emphasize a sentence: ignition commissioning period, safety interlocks and protection devices, absolutely can not be arbitrarily withdrawn, no matter what the situation, to maintain a normal working condition, this is the bottom line, can not be broken.
boiler of various equipment, are inseparable from the power supply, so the power system check can not be ignored. To check the main power supply and standby power supply, confirm that the voltage is stable, no fluctuations, the main and standby power supply can be switched normally, to avoid power failure, resulting in equipment shutdown, affecting the ignition commissioning.
Also confirm the boiler control mode, whether local control or remote control, to meet the needs of ignition commissioning, the operator can control panel, normal operation of various equipment, such as starting the feed pump, fan, ignition device.
In addition, the electrical wiring should be checked to see if there are any broken or loose places, to avoid short-circuiting and leakage due to wiring failures, resulting in ignition failure, or even damage to the equipment, threatening personal safety.
The last step is to confirm the site conditions and ignition permits, which is the final confirmation before ignition, and can not be missing. First of all, we must confirm that the boiler ignition commissioning of the operation ticket has been completed, ignition permit procedures are complete, the operator has been authorized to ignite, strictly prohibit the operation of no ticket, illegal ignition.
Then check the ignition site environment, clean up the site of debris, especially flammable and explosive substances, divided into safe operating areas, set up warning signs to ensure that no unrelated personnel stay on site. Operators should also be equipped with complete personal protective equipment, with the appropriate operating qualifications and emergency response capabilities.
Summarize the inspection results of all the above systems to confirm that there is no omission, no abnormality, and that all preparations are in place before starting the ignition procedure, so as to ensure ignition safety.
Combined with the usual hands-on experience, to tell you a few easily overlooked check items, are summarized in the bloody lessons. For example, the corners of the flue gas channel, elbow, easy to accumulate ash, residual debris, many people check only look at the main road, ignoring these dead ends; and ignition electrode carbon, clean up in a timely manner, affecting the ignition energy; standby power supply switching test, many people think it's too much trouble not to do, wait until the main power supply failure, the standby power supply can not be switched, the complete panic.
In fact, most of these omissions are due to the operator's lack of responsibility, unfamiliarity with the inspection standards, or the existence of a fluke mentality, thinking that “it's all right to do it before”. There is also a lack of standardized inspection procedures and checklists, so the inspection is disorganized and it is easy to miss items.
Therefore, I have always recommended that we must develop a detailed boiler pre-ignition checklist, the inspection items, inspection standards, inspection responsibilities, are clearly written. Operators against the list, check, confirm and sign one by one, to ensure that each item is not missed, do not go through the motions, so as to fundamentally avoid hidden dangers.
Many newcomers will ask, cold boiler and hot boiler, is the pre-ignition inspection the same? In fact, the core requirements are the same, but because the state of the boiler is different, the inspection focus is still different. Simply put, the cold boiler is a long-term shutdown, the first commissioning, or overhaul of the boiler did not warm up; hot boiler is a short-term shutdown, the furnace chamber has a certain temperature of the boiler.
Cold boiler before ignition, we should pay more attention to the integrity of the heating surface, check the furnace tube has no corrosion, deformation, the state of the expansion joint is normal or not. Because when the cold boiler is warming up, the uneven heating of the components can easily lead to damage to the furnace tube. In addition, the cold boiler water supply system, ignition device, should also do a more comprehensive debugging, to adapt to the needs of temperature and pressure.
The risk of cold ignition lies mainly in the speed of temperature rise. If the temperature rises too quickly, the uneven thermal expansion and contraction of the components will generate stress, leading to leakage or damage. Therefore, before cold ignition, in addition to the routine inspection, we should also focus on confirming the state of the heating surface and expansion system, as well as whether the process of heating and pressurization is reasonable.
Before hot ignition, the inspection focus is different, mainly on water level maintenance, fuel supply stability and furnace temperature control. To confirm that the water level in the normal range, to avoid because of the residual heat of the furnace chamber, resulting in the water level dropped too quickly; fuel supply should be stable, can quickly ignite, and at the same time to control the temperature rise rate, do not let the furnace chamber temperature suddenly rise and fall, damage to the equipment.
Many peers have encountered repeated ignition, flameout, both delayed, but also the loss of equipment, in fact, most of the problems in the check before ignition. If the check is done, the system is normal, fuel and air ratio is reasonable, the ignition device is working properly, basically can be a one-time ignition success.
Ignition success rate, in fact, is the wind, fuel, control system of the three synergistic effect. Air supply, wind system check in place, can provide the right amount of wind, fuel can be fully combusted; fuel supply system is not a problem, a stable supply of fuel, will not be due to fuel shortage or leakage led to ignition failure; control system is normal, can adjust the parameters in a timely manner, the ignition process can be stable and controllable.
On the contrary, if the inspection is not in place and a certain item is missed, something may go wrong. For example, the ignition electrode is bad not found, can not light the fire; furnace blowing is not thorough, a little fire on the deflagration, forced to shut down; water level anomalies are not investigated, the ignition immediately after the shutdown. These situations, not only affect the success rate of ignition, but also delay the progress of commissioning, increase the cost of operation and maintenance, the loss is not worth it.
wrote this blog, is to share with your peers a little practical experience: the safety of industrial boiler ignition commissioning, never by luck, but by every meticulous pre-ignition inspection.
Boiler ignition inspection, really not go through the process, go through the motions, it is related to equipment safety, personnel safety, but also related to the stability of production, is the basis for safe ignition, but also the premise of the boiler's long-term stable operation and maintenance. Many accidents, in fact, can be avoided in advance through a serious inspection.
