The working principle of a positive pressure dense phase pneumatic conveying system: Dense coherent ash conveying is based on the pneumatic conveying principle of solid gas two-phase flow, utilizing the static and dynamic pressure of compressed air to transport materials with high concentration and efficiency. Fly ash must be fully fluidized in the bin pump and transported while fluidized. The entire system consists of five parts: gas source, conveying, pipeline, ash storage, and control. The conveying part is composed of conveyors (bin pumps) of corresponding specifications according to the requirements of ash conveying capacity. Each conveyor is an independent unit that can operate either as a single machine or as a system composed of multiple units.
Bin pump
It is the core part of the system, through which dry ash and compressed air are fully mixed and fluidized, enabling smooth operation in the system. It is a closed steel tank, equipped with supporting equipment such as inlet and outlet valves, fluidization plates, level gauges, safety valves, etc.
Working principle of warehouse pump:
The warehouse pump is a pressure vessel with an air nozzle, which has the characteristics of long ash conveying distance, reliable operation, high degree of automation, and requires compressed air with relatively high pressure as the conveying medium. It should be equipped with a set of air compressors. Its working process is to first open the exhaust valve and feed valve for loading, then close the feed valve and exhaust valve when the material is full, open the cylinder pressurization valve, and compress the air to take away the dust inside the cylinder. In such a cyclic manner, dust can be transported out.
1. Feeding stage: The feeding valve is in an open state, and the primary inlet and outlet valves are closed. The upper part of the bin pump is connected to the ash hopper. The fly ash collected by the dust collector freely falls into the bin pump by gravity or through the discharge machine. When the ash level is high enough to send a full signal from the material level gauge, or according to the system feeding setting time, the feeding valve is closed, the exhaust valve is closed, and the feeding state ends.
2. Pressurized fluidization stage: After the feeding stage is completed, the system automatically opens the inlet valve once. The processed compressed air enters the fluidization cone at the bottom of the bin pump through the flow control valve, and passes through the fluidization cone to evenly surround each fly ash particle. At the same time, the pressure inside the bin pump increases. When the pressure reaches the point where the pressure sensor sends a signal, the system automatically opens the discharge valve, and the pressurized fluidization stage ends.
3. Transportation stage: The discharge valve and secondary inlet valve are opened, while the primary inlet valve is not stopped. At this time, the bin pump continues to intake air, and the mixture of gas and ash enters the ash conveying pipe through the discharge valve. The fly ash is always in the fluidized state and enters the conveying pipeline for transportation. After the fly ash in the bin pump is transported, the pipeline pressure decreases, and the pressure inside the bin pump decreases. When the pressure sensor sends a signal, the secondary inlet valve is closed. When the pressure inside the bin pump continues to decrease, When the pressure sensor sends a signal, the conveying phase ends, and the inlet and outlet valves remain open, entering the blowing phase.
4. Purging stage: The inlet and outlet valves are kept open, compressed air is used to purge the bin pump and ash conveying pipeline. After a certain period of time, the purging is completed, and the inlet valve is closed. When the pressure inside the bin pump drops to normal pressure, the outlet valve is closed, and the inlet and exhaust valves are opened to enter the feeding stage. At this point, the system completes one conveying cycle and automatically enters the next conveying cycle.
