Why does the exhaust of diesel generator emit black smoke?

The reasons for the black smoke from the exhaust of diesel generators are poor fuel atomization, low compression in the cylinder, insufficient fresh air in the cylinder, incorrect valve phase, excessive carbon deposition, wrong fuel grade, poor lubrication, overheating or overloaded operation , The plunger of the fuel injection pump is worn, the fuel supply time and fuel supply amount are incorrect, etc. How did this cause come about?

 

The black smoke from diesel generator exhaust is caused by incomplete combustion of fuel. The main causes of black smoke from diesel generators are as follows:

 

(1) Poor fuel atomization. The fuel atomization is poor, and it takes a long time to form a mixture after being injected into the cylinder, which leads to a longer combustion time, and the fuel is discharged from the cylinder before it is fully burned, so the diesel engine emits black smoke. The main reasons for poor fuel atomization are: 1. The pressure adjustment of the injector is too low; 2. The pressure regulating spring of the injector is broken or stuck; Excessive wear; 4. The decompression ring belt of the fuel injection pump outlet valve is worn too much, causing the injector to drip oil.

 

(2) The compression in the cylinder is low. The compression in the cylinder is poor, and the compression pressure is reduced. This may be due to excessive wear of the piston and cylinder liner, excessive wear of the piston ring or the opening in the same direction, causing the cylinder to leak. It may also be that the valve seal is not tight and leaks. The compression in the cylinder is poor, the temperature at the end of the compression is low, and the air leakage reduces the air, the diesel cannot be completely burned, and black smoke is emitted. The main reasons for poor cylinder compression are: 1. Excessive wear of the cylinder liner and piston ring, incorrect installation of the piston ring or loss of elasticity, resulting in air leakage of the cylinder; Ablation and carbon deposition cause the cylinder to be not tightly sealed; 3. Air leakage at the joint surface between the cylinder head and the body, the injector and the cylinder head; The gap between the big end and the connecting rod journal is too large, which increases the volume of the combustion chamber and reduces the compression ratio.

 

(3) The fresh air in the cylinder is insufficient. The air filter or intake pipe is blocked, which reduces the amount of air entering the cylinder, the diesel combustion is incomplete, and the exhaust emits black smoke. If the fuel injector is normal, the compression in the cylinder is good, and the diesel engine emits black smoke after loading at high and low speeds, after removing the air filter, the black smoke disappears immediately, and the air filter needs to be cleaned. The main reasons are: 1. Excessive dust accumulation in the air filter element; 2. The muffler is corroded, coke or oily; 3. The gap between the intake and exhaust valves is too large, which reduces the valve opening 4. Parts of the valve train Looseness, wear, deformation, the relative position of the camshaft gear and the crankshaft timing gear changes, and the valve opening and closing time is incorrect.

Diesel generators

 

(4) The gas distribution phase is incorrect. Excessive valve clearance, serious wear on the tip of the valve cam, etc., will reduce the intake air volume of the cylinder, and the exhaust gas in the cylinder will not be discharged cleanly, which will also cause incomplete diesel combustion and black smoke from the exhaust. Check and adjust the valve train.

 

(5) Too much carbon deposits. Too much carbon deposits in the combustion chamber and exhaust port, the temperature of the combustion chamber is too high, the resistance of the intake and exhaust increases, the intake is insufficient, and the exhaust is not clean, resulting in incomplete combustion and black smoke from the exhaust.

 

(6) The fuel grade is incorrect. The diesel grade used is wrong, the viscosity is too high, or the quality of the diesel is too poor, it is not easy to catch fire, and the exhaust gas emits black smoke. At the same time, the combustion chamber and exhaust pipe are also prone to carbon deposition.

 

(7) Poor lubrication. The diesel engine is poorly lubricated, or the crank connecting rod mechanism is too worn, and the running resistance increases, which makes the diesel engine overloaded, the diesel combustion is incomplete, and the exhaust gas emits black smoke.

 

(8) Overheating or overload operation. When the diesel engine is working, the temperature is too high, which reduces the inflation density, the air intake in the cylinder is insufficient, and the mixture is poorly formed, resulting in incomplete combustion of the diesel and black smoke from the exhaust. Long-term overload operation, the fuel injection amount is too large, resulting in an excessively rich mixture, and the diesel engine emits black smoke (most obvious when a heavy-duty vehicle climbs a hill with a heavy load).

 

(9) The plunger of the fuel injection pump is worn. The plunger of the fuel injection pump is seriously worn, which makes the fuel supply pressure of the high-pressure pump rise slowly, which affects the normal fuel supply time, prolongs the fuel injection process, and affects the fuel injection atomization quality. This is the black exhaust of diesel engine. Common faults of smoke. Therefore, when the oil pump is seriously worn, it should be replaced in time.

 

(10) The fuel supply time and fuel supply amount are incorrect. If the fuel supply time is too late, the fuel injected into the cylinder misses the best time for the formation and combustion of the mixture, and a large amount of unburned fuel is discharged from the cylinder, causing the diesel engine to emit black smoke. If the amount of fuel injection is too large, the mixture will be too rich, which will also prevent the fuel from being fully burned. The main reasons for the incorrect fuel supply time and amount are: 1. The fuel supply time is too late; 2. In the early stage of starting, the gas pressure and temperature are low, and the fuel supply time is too early; 3. The fuel injection pump plunger coupler is worn Then increase the fuel supply stroke; 4. The stroke of the fuel injection pump adjustment rod is too large, resulting in excessive fuel supply.