Positive Pressure Multi-Pump Conveying System

The positive-pressure multi-pump conveying system is a dense-phase positive-pressure pneumatic ash removal system widely used in the fly ash treatment field of coal-fired power plants. It is a mature technical branch of positive-pressure pneumatic conveying. Through the coordinated operation of multiple bin pumps, it realizes efficient and long-distance conveying of high-temperature fly ash, meeting the ash removal requirements of large generator sets.

Core Features

Simplified system configuration: Several bin pumps form one conveying unit. The bin pumps in the same unit operate synchronously. The overall control logic is consistent with that of a single bin pump. Only one set of air inlet valves and discharge valves needs to be equipped. The design of pipelines and control system is more concise with lower initial investment.

Flexible operation switching: Operation switching between different units is convenient. The overall reliability of the system is much higher than that of the traditional single-pump system. Maintenance of a single bin pump will not affect the overall operation of the system, delivering high stability for continuous operation.

Lower operation and maintenance cost: The maintenance workload and cost are 15%-20% lower than those of conventional positive-pressure systems, making it suitable for the long-term continuous operation requirements of large power plants.

Excellent conveying performance: Falling into the category of dense-phase conveying, its ash-air ratio can reach 30~100 kg/kg (while conventional dilute-phase conveying is only 5-15 kg/kg). It features low conveying velocity (average flow velocity of 8~12 m/s, which is 1/3~1/2 of dilute-phase conveying), greatly reduced pipeline wear. The single-stage conveying distance can reach 1500 m, and longer distances can be achieved through relay at intermediate stations, fully satisfying the long-distance ash conveying demands of large power plants.

Complete Working Process

The system consists of four major links: air source treatment, multi-bin pump conveying execution, dust collection treatment and intelligent control. A complete conveying cycle is divided into four stages:

Feeding stage: The feed valve and exhaust valve open. High-temperature fly ash falls from the dust hopper of the dust collector into each bin pump. When the material inside the pump reaches the preset material level, the feed valve and exhaust valve close automatically, completing feeding.

Fluidization and pressurization stage: Compressed air evenly enters the pump body through the diffusion device at the bottom of the bin pump, fully mixing with fly ash to fluidize the powder. Meanwhile, pressure keeps rising until the preset conveying pressure is reached, and the system is ready for conveying.

Conveying stage: The discharge valve opens. Fluidized fly ash is pushed by high-pressure air and conveyed at a constant speed along the conveying pipeline to the terminal ash silo. Multiple bin pumps in the same unit discharge synchronously to guarantee continuous conveying.

Purging cycle: After the material inside the bin is conveyed, compressed air is continuously introduced to purge the pipeline and remove residual fly ash to prevent caking and blockage. After purging, all valves close, and the system automatically enters the next feeding cycle to achieve continuous automatic operation.

Comparison of Core Advantages (Compared with Other Conveying Solutions)

| Comparison Dimension | Positive-pressure Multi-pump Conveying System | Traditional Negative-pressure Conveying System | Single-pump Positive-pressure Dilute-phase Conveying System |

| ---- | ---- | ---- | ---- |

| Maximum Conveying Distance | 1500 m (extendable by relay) | Up to 200 m | Around 500 m |

| Conveying Capacity | 10-200 tons per hour | 25~40 tons per hour | 10-60 tons per hour |

| Pipeline Wear Level | Low (low-velocity dense-phase conveying) | High (high-velocity dilute-phase conveying) | Medium to high |

| Automation Level | High, supporting unattended operation | Medium | Relatively high |

| Applicable Unit Scale | Large / Super-large coal-fired generator sets | Small units / Distributed working conditions | Medium-sized generator sets |

Main Application Scenarios

This technology was originally developed to meet the demand of positive-pressure dense-phase pneumatic ash removal for large coal-fired power plants. At present, it has also been extended to powder material conveying in cement, metallurgy, chemical and other industries. It is especially suitable for fly ash / powder conveying scenarios with multi-point feeding, long distance and large output.

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