Faults Of Diesel Generating Equipment And Their Countermeasures
Faults of diesel generating equipment and Their Countermeasures
1、Beginning
With the development of the times, the function, performance and structure of power generation equipment have been improved by leaps and bounds. However, since someone is involved in maintenance, human errors will often occur. Take the failure cases as knowledge. When you arrive at the site, please take a breath before work. It would be great if you could improve the safety of everyone and guests.
2、Flue fire
(1) What is a flue fire? This refers to the phenomenon of combustion (explosion) during the opening of the atmosphere (flue) after leaving the prime mover, which is contrary to the operator’s meaning.
(2) Occurrence mechanism
For unburned fuel, due to low temperature starting and long-term operation under low load, the combustion temperature is low, the preparation is inappropriate, the fuel injection timing deviates, and it cannot be burned into fog. It is discharged from the prime mover and stacked on the flue as unburned fuel. The unburned fuel has high temperature exhaust
Ignition and combustion after contact.
Especially in large-scale V-type engines, even if the fuel injection timing of a single group deviates, it is difficult to notice abnormal sound during operation, so attention should be paid to it. Special attention shall be paid to the confluence of flues of multiple power generation units and boilers.
(3) Victimization
① There are “Dong Dong” sounds such as impact sound and vibration.
② The chimney flew into the atmosphere. There are also examples seen from nearby pedestrians and moving vehicles.
③ The flue is damaged. In particular, the inspection port and thermal insulation materials are scattered, causing harm to human body. In addition, dust flies into eyes, nose and mouth. At the inspection port where the bolts are fastened, there are cases of bolt breakage, cover flying and falling.
④ The door of the generator room fell off and hit people or objects. Because the fire door is open outside, there are cases where the door fell down in the parking lot outside the building and almost hit the car. Because the area of the door is very large, it exerts a huge force to damage the hinge due to wind pressure. The iron door is very heavy, so the loss will expand.
⑤ The prime mover itself is rarely damaged. (because it is designed on the premise of internal combustion, it is certainly taken for granted)
(4) Countermeasures
① Use fuel that meets the outside air temperature. Especially a heavy oil with low cetane number needs attention.
② Heat the cooling water and lubricating oil (large capacity prime mover needs continuous heating from the day before startup).
③ After start-up, fully warm up the engine, and gradually dilute the unburned fuel left during start-up with low-temperature exhaust gas and discharge it into the atmosphere.
④ Pay attention to the exhaust temperature of each cylinder and investigate whether there is any unburned cylinder (in the engine where the exhaust temperature cannot be measured, use a radiation thermometer to measure the temperature of each exhaust pipe. In the absence of a detector, touch the exhaust pipe with your hand for confirmation. Of course, pay attention to burns).
⑤ Load operation gradually loads the load.
⑥ The timing of fuel injection after maintenance must be confirmed by the person in charge of operation.
⑦ Confirm the position of the operator, just in case. Do not stand directly under the flue inspection opening. Fire doors shall be opened.
⑧ Wear safety glasses and helmet to prevent flying.
- 3. power failure
(1) Relationship between power failure and self generating equipment
The accident that the power supply is cut off in the customer’s facility due to the operation error or error during maintenance operation. If it is only a fire load, the problem will not be obvious because there is usually no action. However, when there are life-related machines such as artificial respirators in important security loads such as hospitals, it will lead to major accidents.
(2) Historical background
In the past, the test switch of emergency power generation equipment only simulated the power failure. If the test switch is not operated, the power switch will work and the load side will become the power failure state. The current test switch power supply switcher does not work. However, the emergency power generation equipment also has models 20 ~ 30 years ago, so the old models need special attention.
(3) Victimization
Computers without backup power supply stopped abnormally, and hospitals also stopped the artificial respirators without power supply.
(4) Countermeasures
① Be familiar with the manufacturer’s operating instructions and sequences before operation.
② Confirm the load condition with the electrical chief technician.
③ The electrical director and technicians are required to be present during the examination.
④ The power generation equipment room is not clear about the condition of the facilities
In order to confirm that the power supply at the load side does not drop beside the power generation equipment, lighting devices are connected to the load side of the power generation device for monitoring.
- 4. out of limit
(1) So called overrun operation
The engine cannot be operated at a speed above the rated speed. In serious cases, burning accidents and stampede accidents may occur (note).
(2) Occurrence mechanism
① Abnormal governor (governor) and governor linkage
The governor can not be controlled normally due to the unsuitable governor itself or the fixed or loose connecting rod connected with the governor.
② Residual fuel
When the unburned fuel remaining on the upper part of the piston catches fire due to poor startup and other reasons.
(3) Countermeasures
① Cut off fuel
Operate the fuel cock to cut off the fuel supply.
② Suction air shutoff
Block the suction port of the air filter with plywood and cut off the suction air. However, it is difficult to experience the operation in advance because of the large amount of air inhaled during the overrun operation.
③ Job location
Stand at a position where the fuel can be cut off quickly and the suction air can be cut off. To prevent foot accidents, do not stand on the side of the engine.
Note: the piston is damaged or the connecting rod fastening bolt is broken, and the connecting rod breaks through the crankcase wall and flies out. In rare cases, the piston pin will also fly out. When it happens, it often jumps out in the reverse thrust direction (the left side in the normal left turning engine of the output shaft), so please never stand on the left side.
5Improper fastening
(1) Necessity of torque wrench calibration
In order to prevent bolt breakage caused by over tightening and insufficient tightening, the bolts must be tightened with correct torque.
Please keep in mind that “the sword is the life of a warrior, and torque is the life of maintenance”.
(2) Frequency of occurrence
Generally, the products used at the service site have experienced about 10% of the nonconformity rate in the past. Especially since it has been used before, it doesn’t matter. Judge by the feeling of your own hands, so don’t believe it too much. “Bohr” torque wrench tester
The slack of the rope is relaxed. “Be sure to pay attention.
(3) Correction method
A torque wrench tester is required for periodic calibration. The calibration frequency depends on the frequency of use. Large or special things are used less frequently about once a year, and those used more frequently are used for a period of one to six months.
6, last
Honesty is the best. Even if you want to mend the situation when there is a dispute, there is only one truth. In the future, they will have wrong ideas and lose the trust of customers. In “Haste makes waste”, fault shooting is finally the fastest way to investigate according to the principles. After taking it, we will use FTA (error tree analysis) and other methods to consider carefully, and the “turtle school” who has been investigating tirelessly will eventually control the “rabbit school”.