Wheat pneumatic conveying is the process of using the energy generated by the airflow to suspend or move wheat particles in a closed pipeline, achieving the transportation of materials from one place to another. Its core working process can be summarized as the formation of aerodynamic force → mixing of gas and material → pipeline transportation → separation of gas and material → purification of exhaust gas, which can be divided into two main forms. The principles are as follows:

Power generation: The vacuum pump (negative pressure fan) works to make the pressure inside the conveying pipeline lower than the external atmospheric pressure, forming a negative pressure zone.

Inhalation of air: Under the pressure difference, external air is sucked into the pipeline with wheat through the suction nozzle (feed inlet).

Transportation process: Wheat particles are suspended and transported in the pipeline with the airflow, and then sent to the unloading point.

Separation and exhaust: After reaching the endpoint, the gas mixture enters the cyclone separator, and the wheat is separated from the air by centrifugal force and gravity and falls into the silo; After being purified by a dust collector, the dusty exhaust gas is discharged by a fan.

Power generation: The Roots blower (positive pressure blower) works by introducing high-pressure air into the conveying pipeline, forming a positive pressure zone.

Gas mixing: Wheat enters the high-pressure pipeline through a feeder (such as a rotary feeder) and is thoroughly mixed with high-speed airflow.

Transportation process: The thrust generated by high-pressure airflow pushes wheat particles along the pipeline to the unloading point.

Unloading and exhaust: After the wheat enters the silo, the airflow is discharged through the ventilation holes or dust collector at the top of the silo, completing the transportation.

Whether it is suction or compression, the essence is to use the relative motion between the airflow and wheat particles to generate friction and thrust, overcome the gravity and frictional resistance of wheat in the pipeline, and make the wheat move together with the airflow. Finally, the material is separated from the air through a gas-solid separation device, achieving non-destructive and sealed transportation of wheat.

A county-level grain purchasing station needs to receive scattered wheat sold by farmers on a daily basis. The feeding points are scattered across three unloading stations, and the dust problem is prominent during the peak purchasing period. At the same time, all wheat needs to be transported to the central reserve warehouse.

This project adopts a negative pressure suction pneumatic conveying system, with feeding suction ports set up at three unloading stations, which are connected to the gas material separation and dust removal system through closed pipelines. When farmers unload grain, wheat is sucked into the pipeline through the suction port and transported to the separation equipment outside the central storage bin with negative pressure airflow. The wheat is stored in the bin, and the dust containing gas is purified and discharged in compliance with standards.

After application, the purchasing station completely solved the problem of dust pollution in the unloading process, without the need for additional personnel to clean up scattered wheat on site. At the same time, it achieved simultaneous feeding and unified transportation of three unloading stations, greatly improving the operational efficiency of wheat purchasing and reducing material loss.

A medium-sized flour processing plant has a raw material warehouse located on the west side of the plant area and a production workshop located on the east side. The wheat in the raw material warehouse needs to be transported to six production stations in the workshop, including a milling machine, a flour cleaning machine, and a wheat blending warehouse. The feeding requirements of each station are different and need to be flexibly switched.

The project adopts a positive pressure pneumatic conveying system, with the raw material warehouse as the single feeding point. The wheat is fed into the main conveying pipeline through a gas locking feeding device, and the pipeline end is connected to a branch switching device, which is connected to 6 production stations. When the system is running, the airflow pushes the wheat to the main pipeline, and according to production needs, the unloading direction is switched through the branching device to accurately deliver the wheat to the corresponding workstation.

This solution realizes the automated transportation of wheat from the raw material warehouse to the production station, without the need for manual transfer, and the entire process is sealed to avoid moisture and pollution of wheat in the workshop. At the same time, through flexible branch switching, it adapts to the intermittent feeding requirements of different production stations, ensuring the continuous and orderly processing of flour.

A large-scale grain reserve warehouse at the provincial level is responsible for the collection, storage, and allocation of wheat in the region. The warehouse has 8 receiving and feeding points, and the received wheat needs to be transported to 12 different storage warehouses. The distance between the feeding points and the storage warehouses is relatively long, and the requirements for on-site environmental protection dust and overall transportation efficiency are extremely high.

The project adopts a suction pressure hybrid pneumatic conveying system, with negative pressure suction devices installed at 8 feeding points at the front end to uniformly suck and transport wheat to the transfer separation equipment; After the transfer separation, the wheat is transferred to the positive pressure conveying system through the air lock device, and then transported to 12 storage warehouses as needed through the positive pressure main pipeline and multiple branching devices. The dusty airflow of the entire system is centrally purified and treated through a comprehensive dust removal device.

This solution combines the advantages of negative pressure suction and positive pressure suction. The front-end negative pressure suction completely solves the dust problem of multiple feeding points, while the back-end positive pressure suction meets the transportation needs of long-distance and multiple unloading points. After application, the reserve warehouse has achieved automated operations of "multi-point receiving and multi-point allocation" of wheat, greatly reducing manual input, while complying with environmental dust control standards, ensuring the quality and safety of wheat storage process.