System Overview

Dilute phase pneumatic conveying is mainly divided into negative pressure suction system and positive pressure blowing system
Dilute phase conveying is the use of air flow generated by fans or vacuum pumps in pipelines, using positive or negative pressure and high speed to push or pull materials to flow in the pipeline, thereby conveying the materials to the corresponding equipment. Therefore, this conveying method is also known as a low-pressure high-speed system, which has a lower material to gas ratio m (usually classified as a low-pressure high-speed system with a material to gas ratio m=0.1-20, pressure p=0.01-0.1MPa or vacuum degree pv=-0.01-0.06MPa, and velocity v=5-30m/s).
The initial starting speed of the system is about 10m/s, and the final speed reaches about 22m/s, resulting in a higher airflow velocity. The initial pressure of the conveying pipeline is usually below 0.1 MPa, while the tail end is close to atmospheric pressure. The medium for dilute phase transportation is generally air or nitrogen, and the power is usually provided by a Roots blower or vacuum pump. During the dilute phase transportation of Roots blower and vacuum pump, the material is suspended in the pipeline, with an equivalent distance of up to 100 meters.
Its main components include mixing chamber, suction nozzle, star shaped feeding valve, cyclone separator, dust collector, Roots blower, electric control cabinet, etc.
The negative pressure system mainly utilizes the vacuum generated by a vacuum type Roots blower (or vacuum pump) in a sealed pipeline, with an air flow lower than the external atmospheric pressure, fed through a suction nozzle (or star shaped feeding valve and mixing acceleration chamber unit), mixed with air, and sucked along the conveying pipeline to a cyclone separator (commonly known as a shaker) for gas-solid separation, achieving material transportation from multiple points at low or bulk locations to one or more points at high locations. Its characteristics are that the materials do not leak out, do not cause environmental problems, and the feeding device is relatively simple.
The positive pressure blowing system blows compressed air (or nitrogen) into the pipeline at a pressure higher than the external atmospheric pressure, forming a mixture of material and gas at the mixing acceleration chamber. The material is then transported to the corresponding equipment through the pipeline, completing the entire conveying process. Its characteristics are large conveying capacity, long distance, low flow rate, and stability. The impact on materials is relatively small. And the separated gas is purified and directly discharged into the atmosphere, extending the service life of the Roots blower.
Negative pressure suction and positive pressure blowing can also be combined appropriately to form a comprehensive system, which can meet some complex production process requirements due to its advantages of both negative pressure conveying and positive pressure conveying.

Note: The material to gas ratio m refers to the ratio of the weight of material passing through the pipeline to the weight of air (or nitrogen) during the same time period. The material to gas ratio is also known as the mixing ratio.

System Process Flow Diagram

Positive pressure dilute phase blowing

Negative pressure dilute phase suction

Positive and negative pressure combined conveying