Candle-type filter

Candle-style Filter

Introduction

Candle filter is a relatively safe and pollution-free filtration method. Candle filters are characterized by tight sealing, high precision, easy maintenance, reliability, and high degree of automation. They are suitable for solid-liquid separation filtration in industries such as oil, plastic, electroplating, chemical, ceramics, and sugar production.

Candle filter has gradually replaced pressure filter and bag filter to become the mainstream filtration method. The multiple reuse of the filtration medium saves a significant amount of filtration consumables; the tightly sealed cylinder ensures no leakage during the production process; microcomputer automation controls the entire process, not only maintaining the continuity of corporate production but also greatly reducing the risk of production accidents while improving production efficiency and saving labor.

Structure

A Candle Filter is an automated pressure filter device, primarily composed of a cylinder, filter core, filter cloth, auxiliary filter aids, a computer control system, and accessories. Additional auxiliary equipment includes air compressors and pressure sensors. The cylinder and filter core are mainly made of stainless steel (304/316/321), carbon steel, and titanium. The filter cloth is mainly made of PP (polypropylene), PE (polyester), PPS (polysulfone), PTFE, and nylon fibers. The auxiliary filter aids are configured according to the filtration standards required in the production process, with activated carbon and diatomite being common. As a large-scale equipment on a production line, the Candle Filter is also commonly referred to as a Candle Filter Machine.

Operating Principle

The filter housing is equipped with 1 to multiple filter cores, each core fitted with a specialized filter cloth selected based on the characteristics of the feed liquid (some special feed liquids require the addition of filter aids, such as activated carbon, diatomite, etc.). As the liquid passes through the filter cloth, solid particles from the liquid gradually accumulate on the surface. When these solids reach a certain thickness, they form what is known as the "filter cake." Due to the small gaps between the particles in the filter cake, it retains the escape of particulate impurities in the liquid, thereby clarifying the filtrate and achieving the required filtration effect for production. (Hence, candle filters are also referred to as filter cake filters).

After normal filtration for a period, the filter cake layer exceeds a certain thickness, the rate of filtrate passing through the cake layer decreases, and the filtration efficiency worsens. It is then necessary to remove the "filter cake layer." At this point, the system will initiate backflushing to remove the cake based on signals from the pressure sensor, while simultaneously opening the bottom valve of the cylinder to discharge the solids. Afterward, a new "filter cake layer" is reconstructed to start a new filtration cycle.

The control of cake layer thickness, cleaning of filter residue, reconstruction of new cake layer, and monitoring of filtrate quality are the four key technical points, and also the four technical challenges, of candle filter cake layer filters.