The essence of grain unloading pneumatic conveying is negative pressure suction pneumatic conveying, which uses air as the conveying medium and utilizes the airflow generated by negative pressure in the pipeline to "suck" grain particles from the ship to the dock side, and then completes the unloading operation through gas-solid separation and unloading buffer. The entire process relies on closed pipelines for operation, which can not only avoid the scattering and loss of grain, but also control dust from the source, making it the mainstream environmental protection solution for grain unloading in ports.

The system power source is arranged at the end of the dock shore, and after starting, it creates a negative pressure environment inside the entire conveying pipeline that is lower than the external atmospheric pressure. At this point, a pressure difference is formed between the external atmosphere and the interior of the pipeline, which is the core driving force for the movement of grain particles and the essence of "suction".

The dock operators operate the adjustable and extendable unloading arm, and insert the front suction nozzle into the grain pile inside the cabin. Due to the negative pressure inside the pipeline, external air will pass through the suction nozzle at high speed, and at the same time, it will "wrap" the grain particles around the suction nozzle, completing the initial mixing of gas and material at the suction nozzle, forming a two-phase flow of gas and grain, and entering the conveying pipeline. For the leftover materials in the corners of the cabin, they can be collected from the entire cabin without blind spots by moving the suction nozzle or using an auxiliary scraping device.

Under the driving force of negative pressure airflow, the two-phase flow of gas and grain flows along the unloading arm pipeline and the shore side fixed pipeline towards the end of the shore side. During the transportation process, the kinetic energy of the airflow is transferred to the grain particles, pushing them forward along with the airflow. Grain particles move in a suspended or slightly sliding state inside the pipeline, completely enclosed in a closed space, with no grain leakage or dust flying.

When the two-phase flow of gas and grain reaches the separation equipment on the shore, the velocity of the airflow slows down, and the grain particles separate from the air under the action of gravity and centrifugal force:

Grain particles: They settle from the airflow and fall into the storage bin or unloading equipment below;

Dust laden air: continues to enter the subsequent dust removal system, completes dust purification, and meets emission standards.

The separated grains are temporarily stored in the buffer warehouse, and then transported to the dock yard, silo or subsequent transport vehicles through the unloading device, completing the entire unloading process.

Low crushing design: By optimizing the structure of the suction nozzle and controlling the flow rate of the pipeline, it avoids severe collisions and friction of grain particles during suction and transportation, minimizes the generation of crushed grains, and ensures grain quality;

Anti clogging design: Grain particles have no adhesion and are not easily blocked by sedimentation. The system will also install a supplementary air device at key positions in the pipeline. If material accumulation occurs locally, it can be eliminated by supplementary air flow to ensure smooth transportation.

Thorough dust control: In a negative pressure environment, even if there is a small leak in the pipeline, it will only inhale external air and will not leak food or dust, which is suitable for port environmental protection requirements;

Flexible homework: The unloading arm can be flexibly raised, retracted, and adapted to different ship types, different draft depths, and the material retrieval needs at different positions inside the cabin;

Low grain loss: Closed conveying avoids the scattering loss of grain caused by traditional grab bucket unloading ships, while low crushing design reduces the quality loss of grain itself.

1. The equipment is docked at the edge of the work vessel and the suction nozzle is placed in the cabin.

2. Start the negative pressure system to suck the grain ashore and complete the gas grain separation in this machine.

3. The separated grains are directly fed into the mobile belt conveyor at the dock through the discharge port at the tail of the machine.

4. Short distance transportation by belt conveyor to the rear silo or loading point.

1. Use the mobile scraper (auxiliary equipment) in the cabin to scrape the grain towards the suction nozzle.

2. The negative pressure system sucks the grain into the separator at the head of the unloader, completing the preliminary separation.

3. Grain falls into a large capacity buffer bucket on the shore.

4. The feeder under the buffer hopper feeds the grain into the positive pressure conveying pipeline or large angle belt conveyor, and transports it to the silo group several kilometers away from the rear.

1.抓斗照常抓取粮食，向料斗卸料。

2.卸料瞬间产生的粉尘被料斗上方的负压罩强力吸走。

3.含尘气流进入负压系统，粉尘被分离收集。

4.收集下来的物料通过小型输送装置，重新送回主料流中。