Process Control Systems And Methods For Use With Filters And Filtration Processes

What is this patent about?

’404 is related to the field of process control systems, specifically those used in filtration processes within biopharmaceutical manufacturing. The background involves preparing cell-derived products like monoclonal antibodies, which require multiple filtration steps for cell debris removal, purification via chromatography, and final concentration/desalting. Tangential flow filtration (TFF), especially single-pass TFF (SPTFF), offers advantages over dead-end filtration for continuous processing due to reduced membrane fouling.

The underlying idea behind ’404 is to actively control the concentration of a product stream using a single-pass tangential flow filtration (SPTFF) unit by manipulating the permeate flow rate. This is achieved by varying the flow reduction factor (FRF), which is the ratio of feed flow to retentate flow, to achieve a desired volume reduction factor (VRF). The key insight is that by adjusting the permeate pump speed based on the changing product concentration, a target VRF can be reached even with a variable feed concentration.

The claims of ’404 focus on a process control system and method that uses a microfiltration unit coupled with a single-pass tangential flow filter . A feed pump moves fluid from the microfiltration unit to the SPTFF, while a permeate pump controls the permeate flow. The core of the invention lies in a control system that adjusts the permeate pump to vary the flow reduction factor (feed flow/retentate flow) to achieve a target volume reduction factor (cumulative feed volume/cumulative retentate volume).

In practice, the system uses a control loop to monitor the permeate flow rate and adjust the permeate pump speed accordingly. Initially, when the product concentration is high, a lower target FRF is used. As the product concentration decreases, the target FRF is increased, either in discrete steps or continuously. This allows for efficient concentration of the microfiltration harvest fluid while maintaining a desired final volume.

This approach differs from traditional TFF systems, which often operate at a fixed feed crossflow rate. By actively controlling the permeate flow, ’404 enables the integration of SPTFF with upstream processes like chromatography, where maintaining a consistent flow rate is crucial. This integration minimizes the need for large intermediate holding tanks and streamlines the overall biomanufacturing process, leading to a more efficient and cost-effective production workflow.