Forge ahead, there is a long way to go -The improvement process of the new Silk Road 1Key
words: M/E 6320 propeller reduction gearbox Speed change ratio Turbocharger tail fin Exhaust branch Scavenging pressure Exhaust temperature
New Silk Road 1 is a ship designed and built by our company. Since its maiden voyage, there have been many problems, especially the slow sailing speed, which caused headaches. Specifically, when the main engine speed at 400 rpm, the exhaust temperature reaches 420 ℃, and the sailing speed is only 7 knots. And the turbocharger scavenging pressure is only 0.03-0.04Mpa or so, the company's chairman Mr. Lipu and the technical department have been trying to take various measures to try to change these problems.
We have adopted the following programs is Try to reduce the load to the main engine to improve the speed, so as to improve the scavenging pressure to reduce the exhaust temperature method, the specific method is to change the propeller disk ratio, that is, the blade width cut off 1.5 cm, we looking for expert cut off it , at this time the M/E increase to 460rpm, exhaust temperature 380 ℃, but the speed not increase , and that slightly decreased, about 6.5-7knots, Fuel consumption changed from 3.6T/ day to 3.3T/ day, with little economic benefit.
For the second time, we explored the main line of increasing the speed of the main engine to increase scavenging pressure so as to reduce exhaust temperature, so we asked experts to redesign the propeller, changed the tight cap into tail fin, and changed the transmission speed ratio from the previous 3:1 to 3.36 after changing the gear , the main engine turbocharger is replaced by the old model into the new model of ABB, so the effect is good, the main engine speed is increase to 420 rpm, the speed is 8.5, the scavenging air is 0.5-0.6Mpa, the exhaust temperature is 420℃, the fuel consumption is 3.6T/day, after the improvement, in addition to the high exhaust temperature, the effect is relatively good, after the improvement for the high exhaust temperature worry that the valve is easy to burn, Therefore, the exhaust valve material was changed from nitride to high temperature resistant Ni80, and the burn frequency of the valve was also reduced, and the overall feeling was relatively satisfactory.
For the third time, that is, recently, I talked with the technical staff about "why the main engine under the same sea conditions, the 6320 type of main engine exhaust temperature at 400-420℃, 8320 type of main engine exhaust temperature at 380℃", the technical staff of revealed, The exhaust branch pipe of the old 6320 main engine has been improved and replaced ( based on changing the scavenging pressure of the supercharger to change the exhaust temperature of the main engine). After the replacement, the exhaust temperature of the 6320 main engine is reduced by about 40 degrees, Therefore, we made a decisive decision and resolutely carried out the transformation according to the suggestions of engineers. The company's technology department closely assisted and contacted with an new exhaust branch pipe, after replacement, the speed of 420 RPM, scavenging air 1.4Mpa, exhaust temperature is only about 380℃, the only thing is that the turbocharger sometimes surge, so the maintenance and replaced the flow of a large nozzle ring to improve the surge phenomenon, the result is very effective, The scavenging pressure of the turbocharger is also up to about 1 Mpa, ， the whole machine is improved, and the speed is stable at about 8.5 knots.
Three times improvements are always around mainline of improve the scavenging pressure of the turbocharger to reduce the exhaust temperature of the M/E, but for a given M/E, to improve it is subject to many restrictions, such as: Surge, exhaust temperature, speed, etc., how to squeeze out effective space to improve it, so as to improve the ship speed, to maximize the shipping benefit, will be a permanent topic, worth every seafarer to think, to explore, to forge forward
This vessel has been running for 13 years, and I have learned and corrected for 13 years. Now it has finally reached the normal and satisfactory effect. I am very pleased!!
Hong Kong New Silk Road Shipping Co., LTD. Chairman li pu and superintendent department