Working Principle of Bag Filter
A bag filter is a pressure-type filtration device whose core principle is to use filter bags as the filtration medium to separate solid particle impurities from fluids through interception, sieving, adsorption, and other processes, thereby achieving fluid purification or solid-liquid separation. It is widely used in chemical engineering, water treatment, food and beverage, pharmaceuticals, and fluid filtration scenarios supporting wire mesh factories.
Its specific working process can be divided into 4 steps:
1.Fluid Inlet and Pre-distribution
The liquid or gas to be filtered (collectively referred to as "fluid") enters the tank under pressure through the inlet port. The deflector or distributor inside the tank evenly guides the fluid into the filter bags, preventing excessive local flow velocity from impacting the bags.
2.Impurity Interception by Filter Bags (Core Filtration Stage)
Filter bags are the core components of filtration, usually made of non-woven fabric, nylon, polyester, and other materials with a microporous structure of specific pore sizes.
When the fluid passes through the filter bag, solid particles with a particle size larger than the micropores of the filter bag are trapped inside the bag (for liquid filtration) or outside the bag (for gas filtration);
Fluid molecules with a particle size smaller than the micropores pass through the filter bag smoothly and enter the filtrate chamber of the filter.
As filtration time increases, a filter cake layer gradually forms on the surface of the filter bag. This layer further improves filtration accuracy and intercepts finer impurities.
3.Discharge of Purified Fluid
The purified fluid filtered by the filter bag collects in the filtrate chamber of the filter tank and is then discharged through the outlet port for delivery to subsequent processes (such as product production, recycling, etc.).
4.Filter Bag Cleaning and Regeneration
When impurities accumulate on the filter bag surface to a certain extent, the filtration resistance increases significantly, and the filter bag needs maintenance:
Manual Cleaning: After shutdown, open the top cover of the filter, remove the filter bag, backwash it with clean water, perform chemical cleaning (for viscous impurities), or directly replace it with a new one;
Automatic Cleaning (for some models): For example, pulse-jet bag filters use high-pressure gas to spray the filter bag in the reverse direction, causing the filter cake to fall off. Cleaning can be completed without shutdown, which is suitable for continuous production scenarios.
Supplementary Features
Flexible Filtration Precision: By replacing filter bags with different pore sizes, precise filtration ranging from 1μm to 200μm can be achieved to meet the needs of different industries;
Easy Operation and Maintenance: The replacement and cleaning process of filter bags is simple and does not require professional tools;
Large Processing Capacity: A single device can be equipped with 1–20 filter bags to adapt to working conditions with different flow rates.
