How the Inverting Filter Centrifuge Works
The Inverting Filter Centrifuge is specifically designed to optimize challenging solid-liquid separation processes within API (active pharmaceutical ingredient), pharmaceutical, and fine chemical industries. Now an industry standard, and known for its reliability and advanced design, the inverting centrifuge provides efficient isolation and washing of APIs in a safe, enclosed environment, ensuring no residual heel remains.
Why Use an Inverting Filter Centrifuge for API Filtration
For facilities in the chemical, pharmaceutical, and petrochemical industries, cryogenic condensation offers safer handling of high-solvent concentrations than adsorption or carbon beds, which are challenging to manage at high levels. Unlike thermal oxidizers, which destroy solvents, cryogenic condensers preserve high-value solvents for recovery, maximizing efficiency and minimizing waste.
Hyperbaric Centrifugation System (HCS) for Low Moisture
For products that are sticky, compressible, or have low moisture content requirements, the inverting centrifuge offers a solution that traditional designs cannot. The filter cloth inverts to push the filter cake out of the horizontally rotating drum, leaving no residual material behind. It also protects the product by minimizing crystal destruction. Therefore, the centrifuge’s unique construction maximizes recovery and purity, even for the most complex materials.
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Design Advantages & No Residual Heel
Overview
The next few slides will walk through the entire Production Cycle, showing feeding, cake washing, the final deliquoring (centrifugation), further deliquoring with an HCS, solid discharge, the CIP and washing machine effect, and the final cleaning with spray balls. This slide shows all 7 at one time before we zoon in to each. After that, there will also be slides showing the basket, and some design advantages.
Feeding
The solid-liquid suspension (slurry) is fed through the feed pipe into the centrifuge. The slurry moves towards the filter cloth under the action of centrifugal force, and onto on a perforated basket. The solid part of the suspension is retained by the filter cloth, forming a cake, while the liquid filters through the cake. The liquid is discharged through the holes of the basket. The feed pipe is located at the center of the basket. A load cell measures the product weight and stops the feeding when the desired weight is reached.
Cake Washing
The washing liquid is fed through the feed pipe. The shape of the basket and the feed pipe position agitate (increase turbulence) the washing liquid and distribute it uniformly throughout the cake.
Final Deliquoring (Centrifugation)
Once the washing phase is complete, the centrifuge accelerates to the maximum speed and maintains that speed for a given amount of time to achieve the desired level of residual humidity in the product. (Settings are both customizable and programmable.)
Further Deliquoring (with Hyperbaric Centrifugation System – HCS)
If the centrifugal force cannot further deliquor the capillaries inside the cake (especially for those products with poor filtration), a Hyperbaric Centrifugation System (HCS) can reduce residual moisture by blowing nitrogen at a high pressure (up to 6 barg) into the basket. The nitrogen pressure and flow reduces the capillary height and the liquid around the product crystals, decreasing the residual moisture. If the nitrogen is also heated up, an additional evaporation effect is achieved.
Solid Discharge
At the end of the centrifugation, the centrifuge reaches the discharging speed and the product is discharged. The mobile part of the basket is moved to the front part of the machine by the axial movement of the inverting shaft. This movement generates the inversion (inside out) of the filter cloth and the discharge of the product.
CLEAN IN PLACE (C.I.P.) Washing Machine Effect (WME)
The centrifuge is filled with the washing liquid up to a predetermined height and put into rotation. During the sequence, the basket rotates clockwise and counterclockwise. The mobile drum moves in and out so the washing liquid reaches all the points of the process area.
Cleaning with Spray Balls
The cleaning liquid is sprayed through the spray balls on all the process area surfaces to completely remove any residue of product.
Basket
The basket in both the extended and retracted position.
Design Advantages
- Process area has full and easy access – the door can be completely opened giving access even to the rear of the basket and the front shaft seal
- Filtrate outlet behind the wall – which allows inspection and sampling without being in the way in the cleanroom
- Open/close automatic locking ring – using a pneumatic device system to open and close the door automatically and quickly
- Feed and wash pipe – allows for homogenous product and wash liquid distribution along the basket with low vibrations
- Hyperbaric Centrifugation System (Option) – allows for sensible residual moisture reduction with respect to the standard filtration by Hyperbaric Centrifugation System (HCS System)
- CIP (Cleaning in Place) – which is a proven and dedicated centrifuge cleaning system to avoid cross-contamination between different products
Typical Applications:
APIs, HPAPIs & Pharmaceutical Synthesis
- Pharmaceutical and fine chemical products
- Active Pharmaceutical Ingredients (APIs)
- Pharmaceutical intermediate products
- High Potent Active Products (HPAPI)
- Pharmaceutical synthesis products
- Ideal for slow filtering and compressible products
- High separation efficiency for products with fine particles, compressible products (low filterability), and fine chemical/API (Active Pharmaceutical Ingredients)
- No residual heel
- Gentle product discharge
- Hyper centrifugation available for fixed bed drying
- 100% access to solids and filtrate housing
- No contact between the operator and product during operation makes it ideal for the production of pharmaceutical synthesis products
- Sizes range from 300mm (11.8 in.) diameter to 1000mm (39.4 in.) diameter – See charts below
- Inertia pad with dampers allows installation directly on the floor
- Through-the-wall installation for clean rooms
- Even cake distribution due to the horizontal design
- Gently handles crystals: the solids discharge is achieved by means of filter cloth inversion (reversible bag), allowing soft crystals to be recovered without breaking
- Electromechanical filter cloth inversion (oil-free execution)
- The short discharge time and complete elimination of the heel cake at every cycle result in high yield. Ultra-thin cakes can be processed efficiently. Even products with low filtering properties (those with fine particles and high compressibility) can be separated, resulting in uniform cake washing.
- Various levels of containment options are available for solids discharge
Specifications, Containment & Technical Services
- Complete PLC controls with touch-screen interface
- Switch between automatic and manual operation
- Variable frequency drive (VRD) speed control
- ATEX (Europe) electrical enclosures or NEC (North America)
- Optional instrumentation integrated into the control system including oxygen monitoring, temperature, pressure, liquid feed flow, and N2 purge
- Its highly effective C.I.P. system (Clean-in- Place) uses a W.M.E. (Washing Machine Effect) and spray balls
- Removal of bound moisture is achieved by dry or heated gas at up to 6 barg differential pressure across the cake (Hyperbaric Centrifugation System – HCS)
- The front casing can be fully opened, allowing the process area to be completely inspected
- Cake volumes from 7 (pilot unit) to 210 liters – See charts below
- High G factors from 1018 to 1663 (pilot unit) – See charts below
- Basket load setting via load cell system
- Filter cloths available in polypropylene, HALAR, or PTFE
- Gas tightness at 400 mm H2O
- High surface finishes
- Complete FDA validation documentation
- Construction materials
- Parts in contact with the product: all stainless steels and special alloys are available, such as AISI 316L, AISI 904L, hastelloy, monel, alloy 59, 254 SMO, nickel, titanium, and SAF 2205
- Surface coating option: Halar (ECTFE)
- Elastomers: antistatic and FDA certified, Teflon ETFE, and hard rubber
- Field service and technical support available
- Mechanical and electrical parts
- Process control and maintenance manuals
- Certifications and construction documentation
- Mechanical and electrical upgrades
Standard Sizes and Technical Data
| Centrifuge model: HT/GMPUnit |
Basket Diameter (mm) |
Basket Length (mm) |
Filtering Surface (m2) |
Cake Volume (liter) |
Slurry Density (kg/dm2) |
Max Load (kg) |
Max Speed (RPM) |
G Factor (xg) |
Centrifuge Weight (kg) |
|---|---|---|---|---|---|---|---|---|---|
| 300/110 | 300 | 110 | 0.1 | 7 | 1.25 | 9 | 3150 | 1663 | 1400 |
| 470/180 | 470 | 180 | 0.27 | 27 | 1.25 | 34 | 2300 | 1390 | 3000 |
| 600/225 | 600 | 225 | 0.45 | 52 | 1.25 | 65 | 2000 | 1340 | 4000 |
| 700/225 | 700 | 225 | 0.52 | 65 | 1.25 | 81 | 1850 | 1338 | 4600 |
| 800/350 | 800 | 350 | 0.90 | 122 | 1.25 | 152 | 1600 | 1144 | 8500 |
| 900/350 | 900 | 350 | 1 | 145 | 1.25 | 181 | 1500 | 1131 | 8700 |
| 1000/430 | 1000 | 430 | 1.35 | 210 | 1.25 | 262 | 1350 | 1018 | 9400 |
| 300/110* | 300 | 110 | 0.1 | 7 | 1.25 | 9 | 3150 | 1663 | 1400 |
| 470/180* | 470 | 180 | 0.27 | 27 | 1.25 | 34 | 2300 | 1390 | 3000 |
*Pilot centrifuges
The smaller machines are considered pilot centrifuges and are used for both research and development laboratories, as well as small productions of high-added value products. These machines, while smaller, have the same features as the industrial scale module plus can be skid mounted for easier mobility.