Driving Spray Drying towards Better Yield: Tackling a Problem That Sticks Around

Area of Science:

• Chemical Engineering
• Materials Science

Background:

• Powder deposition on spray dryer walls is a known issue affecting yield and process continuity.
• Existing research focuses on factors influencing deposition extent and rate in chemical and food industries.

Purpose of the Study:

• Investigate an atypical spray drying yield loss occurring in consecutive batches.
• Identify key mechanisms responsible for yield reduction in repeated spray drying cycles.

Main Methods:

• Analyzed the interplay between process parameters, material properties, and equipment.
• Examined factors including inner wall surface roughness and gas flow variations.
• Assessed the impact of start-up/shutdown parameters on deposited powder's thermal properties.

Main Results:

• Identified specific mechanisms causing yield loss in subsequent batches.
• Found that surface roughness, gas flow changes, and thermal exposure of deposited powder contribute to increased wall accumulation.
• Demonstrated that correcting these factors mitigates yield reduction.

Conclusions:

• Atypical yield loss in spray drying is linked to cumulative effects of wall deposition over batches.
• Surface characteristics, process dynamics, and thermal history of deposited material are critical.
• Process optimization by addressing identified factors significantly improves spray drying efficiency and yield consistency.