Variable Frequency Drive for Dredging Ship

Sand is one of the most basic materials in the construction industry, it has a huge market demand. How to get sufficient sand to meet the needs of modern architecture? Among various sand acquisition equipment, sand suction ship is one of the most widely used equipment.

Working principle of sand suction ship: through the power of hydraulic power, silver sand and sea sand washed by water column of high-pressure water gun are transported to the destination with the help of pump.  
The equipment consists of hull, conveying system, water supply system and exhausting system, the conveying system includes power, clutch and sand pump, the exhausting system includes high pressure water pump and vacuum extractor.
Working process: suck sand→filter→wash in the first sand washing chamber→transport by tippers→wash in the second sand washing chamber→transport by tippers→sand hopper→belt output→sand carrier

According to the working process, tipper transportation and belt output require speed regulation. Previous speed regulation was completed by gear box.
But there are many disadvantages for using the gear box, including:

• Unable for linear speed regulation.
• Difficult to replace the belt pulley, high labor intensity
• Great mechanical wear and energy waste
  

Operation methods of traditional dredging ship

1. Before starting, check the transmission system and oil of the whole machine, then pull the conveyor belt and pull on the clutch, start the diesel engine, pull down the clutch slowly to regulate the rotation speed to normal value. Then Start the diesel engine of front chain bucket.
2. After two diesel engines are started, adjust the speed to required value. Loosen the arm brake and pull it down slowly, when the sand in the hopper is more than 2/3, stop pulling down. When the sand is about 1/3, pull down the arm. When the arm is at a 45-degree angle to the water surface (about 5 meters), stop pulling down the arm. At this time, switch to traction control depending on the amount of sand in the bucket. In case of sand collapse, the machine can’t pull, loosen the traction rope and make the ship backward till it can’t dig. In case of stone or muddy layer under water, pull up the arm immediately to avoid the barrier.
   

It can be seen that above mentioned dredging ship still uses the diesel engine, which has the disadvantages of large noise, high energy consumption and complex operation. With the popularized application and easy operation of motor, as well as the vigorous promotion and application of VFD, most dredging ships also adopt the VFD motor drive system at present, and next this paper introduces the solution of variable frequency speed regulation with VFD in the dredging ship.

4 sets of sand hopper motor (132kw) use the 185kw VFD, 2 sets of belt conveyor motor (110kw) use the 132kw VFD, 1 set of gravel conveyor belt motor (90kw use the 110kw VFD, 4 sets of rolling screen motor (22kw) use a 75kw VFD for per two motors.
Notice: due to long wires in the ship, it’s easy to cause interference, so reactors are suggested.

After the VFD energy-saving modification, the dredging ship operates more conveniently and simply, parameter settings are reduced. 
The most important thing is to protect the modified equipment and solve the current shock when the motor starts. (when staring at power frequency in the past, the contactors and motor were burned out frequently)
Oil price keeps increasing. Electricity on the ship is provided by the diesel generator. After variable frequency drive modification, more electricity can be saved, namely saving the diesel oil. The ship costs less and works more efficient within a same working period. 
The modified equipment operates safely and reliably, meet the technology requirements of dredging ship. Meanwhile, it reduces the labor intensity and improves the production efficiency, energy saving and environmental protection. Get a VFD and enjoy all the amazing benefits that come with it!