BASF Project: Integrated Candle Filter and Three-in-One Filter Dryer System
Project Background: Process Upgrades for High Purity and Operational Safety
As a leading global chemical company, BASF maintains stringent requirements for product purity, solvent recovery efficiency, and Environment, Health, and Safety (EHS) during the production of high-performance specialty chemicals and fine chemical raw materials. The project involved high-value, oxidation-sensitive materials containing VOCs.
Traditional open filtration equipment could not adequately address the requirements for material cleanliness, solvent containment, and safe operation. BASF therefore required an automated and enclosed process system covering the complete route from pre-filtration through final product drying.
This application is closely aligned with UNITE’s chemical industry filtration and separation solutions, which are designed for complex chemical operating environments and can combine filtration, separation, and drying to improve process stability, protect downstream equipment, and support the recovery of high-value materials.
Core Challenges
1. High-Precision Front-End Clarification and Automatic Cake Recovery
The process material contained trace solid impurities. The front-end stage therefore required precise solids retention while minimizing the contamination, material loss, and operator exposure associated with manual filter-element handling. Stable and automatic filter-cake recovery was also essential.
2. Fully Enclosed Processing under Inert-Gas Protection
Because the process media were volatile and oxygen-sensitive, filtration, material transfer, and drying had to be carried out under nitrogen protection. The equipment needed to minimize the risk of leakage and oxygen ingress while meeting the sealing and EHS requirements of high-purity chemical production.
3. Multi-Stage Process Integration with Fewer Material Transfers
If filtration, multiple washing stages, vacuum drying, and automatic discharge are performed in separate pieces of equipment, the process requires more material transfers and may incur higher risks of cross-contamination, solvent loss, waiting time, and footprint. BASF needed the key operations to be integrated into a more compact process unit to improve consistency.
Customized Solution: Candle Filter + Three-in-One Filter Dryer
Front-End Precision Clarification: Fully Enclosed Candle Filter
The system uses a candle filter as the front-end precision clarification unit. After the slurry enters the enclosed pressure vessel, liquid passes through tubular filter elements while solid impurities accumulate on the element surfaces to form a filter cake. The clarified liquid is then collected and discharged through the outlet piping.
When the cake reaches the preset thickness or differential-pressure condition, the system initiates a backwash or gas blowback cake-discharge sequence. The cake is loosened and discharged automatically. The enclosed design and automated operation help reduce manual intervention, leakage risk, and contamination, making the equipment suitable for fine chemical applications where purity and safety are critical.
Filtration, Washing, and Drying: Agitated Nutsche Filter Dryer
The concentrated slurry from the upstream stage is transferred to an Agitated Nutsche Filter Dryer (ANFD). The equipment performs the following operations sequentially within one enclosed vessel:
1.Pressure filtration: External pressure drives solid-liquid separation, forming a filter cake on the filter plate;
2.Spray washing: The filter cake is spray-washed to remove residual mother liquor and soluble impurities;
3.Reslurry washing: Agitation redistributes the cake in the washing liquid, improving washing uniformity and product purity;
4.Vacuum drying: Drying under vacuum reduces product moisture and residual solvent;
5.Automatic discharge: After drying, a sealed side-discharge mechanism and reverse agitator rotation convey the product out of the vessel.
Combining filtration, washing, and drying in a single vessel reduces intermediate transfer steps and therefore helps lower the risk of cross-contamination and material loss. UNITE describes its ANFD as an enclosed solid-liquid separation system for batch processes requiring high cleanliness, safety, and operating efficiency. The actual filtration area, pressure, temperature, and drying conditions must be confirmed through material characterization and process testing.
Automated Control: Closed-Loop Parameter Management from Feeding to Discharge
The project includes an automated control system designed to meet BASF’s standards. It enables automatic transitions between feeding, filtration, washing, drying, and discharge. Key process parameters—including pressure, temperature, and moisture—are monitored in real time and uploaded to the central control system to support process traceability, alarm management, and production oversight.
The solution also reflects the integration approach used in UNITE’s skid-mounted filtration and separation systems. Filtration equipment, piping, valves, instrumentation, and control systems can be configured according to process conditions, while modular construction helps improve installation, commissioning, and maintenance efficiency. For complex applications, the system can be further customized according to filtration precision, material selection, automation level, and enclosed-operation requirements.
Project Value and Results
After the integrated system entered production, BASF achieved improvements in both production efficiency and operational safety:
•Higher product purity: Product purity reached a historic high, supporting the stringent requirements of high-performance specialty chemical production;
•Improved solvent recovery: According to the project information, solvent recovery increased by 25%, helping reduce solvent consumption and production costs;
•More reliable enclosed operation: Fully enclosed processing effectively eliminated odor leakage and reduced the risks of operator exposure and environmental emissions;
•Shorter production cycles: Integrating filtration, washing, drying, and discharge reduced material transfers and process waiting time;
•Higher automation and traceability: Real-time monitoring and central-system integration improved process stability and operational visibility.
The 25% improvement in solvent recovery, together with the reported gains in product purity and production-cycle performance, represents the result of this specific BASF project. These figures should not be interpreted as universal performance guarantees for all materials or operating conditions. Actual system design should be validated against slurry concentration, particle-size distribution, solvent system, thermal sensitivity, allowable oxygen level, filtration cycle, and target final moisture content.
Conclusion
For fine chemical manufacturers processing high-value, oxidation-sensitive materials containing VOCs, a single filtration device may not be sufficient to meet simultaneous requirements for purity, containment, solvent recovery, and automation. The BASF project combines front-end precision clarification through a candle filter with downstream filtration, washing, and drying through an ANFD, bringing critical solid-liquid separation and post-treatment steps into one enclosed process system.
The project demonstrates a practical system-integration approach for high-purity fine chemical production. If your process involves precision clarification, filter-cake washing, vacuum drying, VOC containment, or nitrogen protection, contact the UNITE engineering team with your material and process data to discuss a customized filtration and separation solution.
Related Pages
•Chemical Industry Filtration and Separation Solutions
•Solid-Liquid Separation Series
•Agitated Nutsche Filter Dryer
