Fully Automatic Candle Filter for Viscose Fiber Process Water (Flash/Second Bath) - PVDF Filter Elements

Product Introduction

In the viscose fiber production process, the purification and recycling of flash water (initial rinse water) and second bath water (fine wash water) are critical for ensuring product quality, improving resource efficiency, and reducing operating costs.

Our candle filter system is specifically engineered to handle these complex industrial process water streams. With its fully enclosed design, high filtration precision, and fully automated operation, it ensures reliable performance while minimizing operational costs.

The system utilizes a precoat filtration method with specialized filter aids to achieve deep removal of solid impurities, guaranteeing the quality of the recycled water. Its unique advantage lies in its ability to minimize the moisture content of the filter cake through pressing and drying procedures at the end of each filtration cycle. The resulting cake is easy to dislodge and quick to discharge. The fully automated regeneration control system significantly reduces manual maintenance requirements and system downtime, ensuring continuous and efficient production operation.

Key Advantages

1. High-Efficiency Filtration:

Specifically designed for viscose fiber process water, ensuring consistent filtration performance

2. Enhanced Precision:

• Precoat filtration method with PVDF elements delivers superior solids removal.
• Extended Cycle Times: High dirt-holding capacity reduces regeneration frequency, lowering operational costs.
• Complete Cake Discharge: Efficient gas back-blowing ensures clean regeneration, restoring full flow capacity.

3. Automated Operation:

Fully integrated PLC/DCS control for minimal manual intervention

4. Easy Maintenance:

A simple regeneration process involving pressing, drying, and rapid cake discharge effectively reduces downtime

5. Durable Construction:

Carbon steel with hard rubber liner and PVDF components for corrosion resistance

6. Customizable Solutions:

Available as standalone units or complete systems with auxiliary equipment

Technical Specifications

Structure Overview and Working Principle

The candle filter operates using a filter aid precoat method specifically optimized for viscose fiber process water treatment:

The filtration system typically comprises filters, a precoat tank, a precoat pump, a dosing tank, a metering pump, instruments, valves, piping, and a control system.

Working Principle：

Prior to filtration, the filter elements are precoated with diatomaceous earth filter aid. After precoating is completed, the normal filtration cycle begins. The feed liquid enters the filter through the inlet and passes through the precoated filter elements, where suspended solids are retained. The clean filtrate is discharged through the outlet into a clean liquid storage tank.

During the filtration process, filter aid is metered and injected into the feed stream at adjustable time intervals to maintain filterability. Meanwhile, the metering pump is activated to inject filter aid from the dosing tank into the feed stream at a controlled, metered rate.

As filtration continues, the filter cake layer progressively thickens, leading to increased filtration resistance. When a preset filtration time is reached (alternatively, when a preset inlet pressure is exceeded), the filter elements require cleaning. The cleaning cycle begins with closing the feed inlet valve and introducing compressed air into the vessel to blow down the residual liquid. For backwashing, compressed air is introduced through the filtrate outlet to pulse the filter cloth, dislodging the accumulated cake and entrapped impurities from the fabric gaps. The dislodged solids are then discharged through the bottom drain.

After the cake is fully purged, the filter elements can be thoroughly washed with cleaning agents, such as hot cleaning water, to complete the regeneration process.

System Control：

The filtration system is fully automated and can be equipped with a local PLC control panel or integrated directly into the customer’s DCS system for centralized control.

Three control modes are available:

1)Differential pressure control
2)Time-based control
3)Manual control

Core Components

PVDF Grouped Outlets

PVDF Filter Candles---High Chemical Resistance

PVDF Filter Elements---High Chemical Resistance

Raw Material Fiber and Seamless Filter Cloth

Typical Applications

Spinning Bath Circulation Filtration

In viscose spinning, the cellulose dope is extruded through spinnerets into a spinning bath containing sulfuric acid, sodium sulfate, and zinc sulfate, where cellulose precipitates into fibers. The bath is continuously circulated and gradually accumulates sulfides, fiber debris, and other suspended solids. Our side-stream automatic candle filter, equipped with PVDF filter elements and precoated filter aid, continuously removes these impurities. The clean bath liquid is returned to the main tank, while residue is automatically discharged via back-pulse. This maintains stable bath composition, prevents spinneret and pump clogging, reduces downtime, and minimizes sulfuric acid consumption.

With chemically resistant PVDF filter media, automated back-pulse regeneration, and high-precision solids removal, our candle filter systems are the proven choice for maintaining product quality and operational efficiency throughout the fiber manufacturing process.

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