Summary:
All you need to know about Spiral continuous ship unloader
What is Spiral continuous ship unloader?
What are the types of spiral continuous ship unloaders?
The characteristics of spiral continuous ship unloaders
The operational capacity of spiral continuous ship unloaders
Spiral continuous unloader suitable for ship types
Structure of spiral continuous ship unloader
What is Spiral continuous ship unloader?
Spiral continuous ship unloader is a type of efficient and continuous bulk cargo unloader that utilizes horizontal screw conveyors, vertical screw conveyors, and specially designed material retrieval devices as the main working mechanisms. An efficient continuous ship unloader that uses a mechanical rotation mechanism to lift and transport materials to the rear dock.
The screw unloader mainly consists of vertical arms, horizontal arms, rotating towers, end screw conveyors, and gantry components. The vertical arms include box shaped covers and vertical screw conveyors. The vertical screw conveyor is composed of an inner screw and an outer screw of the casing. The inner screw is used for vertical lifting of materials, and the outer screw is used for material loosening and feeding. The horizontal arm includes two parts: a box shaped arm frame and a horizontal screw conveyor.
When unloading the ship, the reverse spiral feeding device is first lowered into the material to be unloaded. The material is pushed downwards under the action of the forward spiral in the feeding device, and then the material is lifted towards the center by the feeding screw and squeezed at the reverse spiral. The reverse spiral transports the material to the spiral lifting pipe, and then the inner spiral lifts the material vertically. The material is then transported to the predetermined feeding point through a horizontal conveyor.
Advantages: Lightweight structure, completely sealed, good performance, can effectively prevent dust leakage and noise pollution, easy operation, low labor intensity of on-site personnel, and more suitable for unloading materials with poor fluidity (such as agglomerated materials). Compared with unloading ships with the same productivity, it has the lightest self weight.
What are the types of spiral continuous ship unloaders?
Spiral unloaders can be divided into three types based on whether the entire machine can be moved and the installation position: self-propelled, fixed, and floating. They are suitable for different dock loading and unloading process systems.
The characteristic of a self-propelled spiral ship unloader is that it has a walking mechanism and can walk along the track laid at the forefront of the dock. It uses the coordination of walking, turning, pitching, and swinging actions to unload the cargo hold of a seagoing ship. The unloaded materials can not only be unloaded onto the belt conveyor parallel to the dock shoreline, but can also be transferred onto the belt conveyor that can pitch around the hinge point at the end of the gantry, directly delivering the materials to the yard.
The self-propelled spiral unloader is suitable for coastal and inland ports with upright quay walls, targeting various bulk cargo ships. In the loading and unloading process system of specialized terminals for bulk cargo such as cement, fertilizers, grains, and coal, self-propelled screw unloaders have had many successful experiences and are increasingly proving to be an economical and efficient unloading equipment. Self propelled screw unloaders are also widely used in coal unloading operations at power plant docks.
The fixed screw unloader is directly installed on the pier pier pier. The ship unloader utilizes the coordinated actions of the rotating, pitching, and swinging mechanisms for unloading operations. The fixed spiral unloader is suitable for unloading materials from open barges in inland ports, and its operating range should meet the requirements of the ship’s width direction. The arrival of the unloading position in the captain’s direction can be achieved by moving the ship.
Floating screw unloaders are installed on barges and can be either fixed or mobile depending on their mobility. A floating movable screw unloader is installed on a floating flat bottomed pontoon dock or a floating transfer dock, and can move along the longitudinal track attached to the floating dock to unload or transfer ocean going cargo ships.
The characteristics of spiral continuous ship unloaders
Efficient: The unloading quota efficiency ranges from 100T/H to 2700T/H, meeting the needs of bulk cargo operations at various ports along the river and coastal areas. Due to the use of a special forced feeder and high-speed spiral, the material is rapidly lifted, resulting in a large unloading capacity, and the actual unloading capacity is greater than the rated unloading capacity.
Strong adaptability: Strong adaptability to goods and ship types. Spiral unloaders can be used to unload various powdered, granular, and blocky materials. When unloading certain materials that have been compacted or even formed into hard shells after sea transportation, such as fertilizers, cement, potassium salts, etc., due to the function of loosening the materials by the reverse reclaiming screw or loosening knife installed outside the reclaiming device, it can well meet the unloading requirements. The vertical section size of the screw unloader is small, and auxiliary mechanisms such as walking, turning, pitching, and swinging ensure the flexible operation of the machine. It can be suitable for various types of barges and seagoing vessels.
Energy consumption: High energy consumption. During the operation of the conveying screw, due to the friction between the material and the spiral surface, the friction between the material and the material groove or conveying pipe wall, as well as the friction and stirring between the materials, the unit length transport resistance of the material is relatively high, making the unit energy consumption of the screw unloader higher than other mechanical continuous unloaders, comparable to the grab unloader, but much lower than the pneumatic unloader. The average power consumption is 20-28% of the same pneumatic unloading ship.
For materials such as cement, grains, and coal with low weight, good fluidity, and low grinding ability, the unit energy consumption is lower, while for materials with high weight and grinding ability such as phosphate and iron ore powder, the unit energy consumption will significantly increase.
Due to the light weight of the transmission components, it can work continuously and can also be processed by whole machine frequency conversion, which can save electricity consumption. The power consumption varies depending on the type of cargo being unloaded and the rated unloading capacity. For every 1 ton of cement unloaded, the power consumption is 0.50-0.0 79 kilowatt hours. Significant energy-saving effect. Moreover, the use of clearance machines is minimal, and their fuel consumption is about 30% of that of grab ship unloaders. Small wheeled rake machines are commonly used now, with some achieving electric drive.
Environmental protection: The material conveying system of the screw unloader is fully enclosed, and all connection points are designed to be enclosed, eliminating the phenomenon of dust and material overflow. During the unloading operation, there was no dust flying and no leakage of materials or material odors.
The feeder is buried inside the material, thereby reducing the amount of dust generated during the material retrieval. For materials such as cement, coal powder, chalk powder, potassium salt, ammonium phosphate, etc. that are prone to air pollution, using a screw unloader is particularly advantageous. The noise of the screw unloader is also relatively low.
The main components have been tested and calibrated for static and dynamic balance, and the equipment operates smoothly and reliably without causing noise pollution to the surrounding environment. The sound level can be controlled below 60dB (A).
Simple structure: The screw unloader has a small mass and a simple structure. The material conveying system of the screw unloader is composed of a screw conveyor without flexible traction components.
The conveyor has no return branch, and its structure is relatively simple. The cross-sectional dimensions of the vertical and horizontal arms are relatively small. Under the same productivity as the target ship, the mass of the screw unloader is much smaller than that of the grab unloader, and it is also the least mass among various mechanical continuous unloaders. Therefore, the cost of screw unloaders is relatively low, and the requirements for the dock’s load-bearing capacity are relatively low.
Cost reduction: Energy conservation and work reliability greatly reduce the long-term operating costs of ship unloaders. Reduce labor, only require one person to operate, while observing the material situation in the cabin and operating the portable remote control. The continuous and efficient unloading performance of the ship unloader greatly shortens the unloading time, saving tens of thousands or even tens of thousands of yuan in shipping costs in a day.
Fully functional: The overall electromechanical integration design is adopted, and all controls are controlled by imported PLC programmable controllers. The program can be easily modified, with a high degree of automation. At the same time, it has various safety protection functions such as mechanical protection, hydraulic automatic protection, speed limit protection, overload protection, electromagnetic and variable frequency combined braking system.
Technical characteristics of spiral ship unloaders: widely used in building materials transfer terminals, power, chemical, food and other industries, suitable for conveying powdered, granular, and small materials such as cement, coal ash, mineral powder, fertilizer, grains, etc. horizontally, vertically or at any angle; Its working environment temperature is -20-+40 ℃, and the conveying material temperature is -20-+80 ℃. It is not suitable for conveying materials with high viscosity.
The operational capacity of spiral continuous ship unloaders
The efficiency of unloading quota ranges from 100T/H to 2700T/H, meeting the needs of bulk cargo operations at various ports along the river and coastal areas.
High unloading efficiency: mainly manifested in the high filling coefficient of materials in the spiral conveying pipeline, often working close to full load. Due to the installation of a unique feeding device (reverse feeding spiral head), the filling coefficient can reach 70-90%.
Secondly, the spiral machine can often work close to full load, and its vertical arm can rise, fall, and swing with the boom’s pitch, and can rotate left and right 100 degrees with the rotating tower. With the walking function of the unloading machine, the material retrieval head can flexibly reach various corners of the warehouse.
The material taking device also has the function of automatic loosening and excavation, so regardless of the fluidity of the material, the ship unloader can continuously work close to full load until there is only a 30cm~50cm thick material layer left from the bottom of the cabin.Therefore, continuous unloading operations can be achieved, with an average productivity utilization coefficient of 75% and a cement unloading rate of up to 95%.
The remaining material is about 20-30cm, and the clearance amount is relatively small. The actual amount that requires the assistance of a push rake machine for unloading only accounts for less than 5% of the total loading at the hatch, while the amount that a grab bucket unloader requires the assistance of a push rake machine for clearing accounts for about 50%. Therefore, under the same rated unloading efficiency conditions, the actual capacity of a screw type unloader is about 20% larger than that of a grab bucket unloader, and the average efficiency coefficient of unloading operations can reach 75%, while the bridge type grab bucket unloader is only 50-60%.
This stable working nature can reduce the configuration capability of the rear conveyor system, thereby also reducing costs.
Spiral continuous unloader suitable for ship types
Spiral unloaders are widely used in unloading operations at port bulk cargo terminals, as well as in other dock types and unloading process systems.
According to the tonnage of the target ship and the type of materials unloaded, the vertical conveying screw diameter range is 260mm~790mm, and the production rate of the unloading machine ranges from 100t/h to 2700t/h.
The screw unloader is suitable for various ship types ranging from 1000 ton barges to 150000 ton ocean going ships. It can be used to unload various loose materials such as cement, grains, coal, various fertilizers and chemical raw materials, feed, bauxite, phosphate rock powder, sugar, etc. Small and medium-sized screw unloaders generally require material particle size not to exceed 50mm, while the maximum allowable particle size for large screw unloaders can reach 350mm.
Due to its high level of intelligence, the software and hardware of the electrical PLC control system of the spiral continuous ship unloader adopt products from well-known companies. The use of PLC control can achieve the functions of equipment control, data monitoring, data processing, and data transmission. The working status, loading and unloading ship data, fault information, etc. are displayed in the electrical room, driver’s cab, and central control room of the system, achieving information management of the loading and unloading ship system.
Due to the fully enclosed structure of its vertical arm feeding device and horizontal arm conveying structure, and the independent operation of the dust-proof aggregate system at the rear discharge point, the entire process is pollution-free, leak free, and dust-free, which can reduce dust pollution during unloading operations at the dock by 90%.
The grab bucket ship unloader is prone to causing dust flying during the discharge of the grab bucket, aerial operation, and unloading of the grab bucket. Nowadays, the country’s requirements for environmental protection are increasing, and the pressure on environmental protection is very high. The screw unloader is very in line with the government’s requirements for environmental protection.
Structure of spiral continuous ship unloader
The machine is mainly composed of metal structure, conveying system, auxiliary working mechanism, operation control system, and other parts.
The metal structure includes a gantry and supporting cylinder, a turntable on the cylinder, horizontal support arms, vertical support arms, etc. The gantry adopts a box shaped structure, and the support legs of the gantry often use one rigid and one flexible support leg to avoid the phenomenon of wheel biting caused by the deformation of the gantry. The rotary support device adopts a rolling bearing type rotary support, and the horizontal and vertical arms can adopt a tubular or box structure.
Secondary trusses should be added to horizontal arms with longer horizontal conveying distances to enhance their rigidity. The tail end of the horizontal arm is equipped with a live counterweight to balance the self gravity of the vertical arm and the vertical screw conveyor.
The conveying system of the screw unloader consists of a vertical arm screw conveyor, a relative rotating reclaiming device, a horizontal arm screw conveyor, and a gantry screw conveyor. Belt conveyor systems are generally used behind the dock.
The auxiliary working mechanism of the ship unloader includes the walking mechanism of the ship unloader, the rotating mechanism of the rotating part, the pitch hydraulic cylinder of the horizontal arm and its upper horizontal arm screw conveyor, the vertical arm and its upper vertical arm screw conveyor, and the swing hydraulic cylinder of the reclaiming device.
When the screw unloader is in operation, the reclaimer head is inserted into the material pile in the cabin, and the reverse rotating reclaimer device supplies the material into the vertical arm screw conveyor. On the other hand, it also prevents the material from being thrown out due to the centrifugal force generated by the rapid acceleration along the circumference after entering the conveying pipe.
The material entering the vertical arm screw conveyor is lifted and then transferred to the horizontal arm screw conveyor through the discharge port. It is then transported to the transfer funnel at the rotation center, and then transferred to the leading edge belt conveyor parallel to the dock through the gantry screw conveyor.
Peralatan screw unloader utilizes a material reclaiming device to automatically loosen and excavate materials. It utilizes the movement of the frame, rotation of the body, and pitch and swing hydraulic cylinders to allow the machine head to reach various positions inside the cabin, ensuring that materials flow continuously and continuously in the unloader conveying system with a high filling rate.
The transportation method of materials on the dock can be determined according to the specific requirements of the loading and unloading process. The materials can be transported to the storage yard or silo for temporary storage through a belt conveyor system, or directly loaded onto a truck through a loading funnel. Materials can also be transported to the loading machine and loaded onto a barge through a belt conveyor.