The Difference Between Internal Reflux and External Reflux in the Distillation Column

In a distillation column, internal reflux is the downward - flowing liquid from the top, formed by a pump at the bottom drawing overhead liquid and re - injecting it. It can reduce top - column concentration, improve distillation liquid efficiency and product quality, but it increases equipment cost and maintenance expenses, and improper control may cause negative effects. External reflux is the upward - flowing liquid from the bottom, achieved by a separator or level regulator. It can improve separation efficiency and save equipment and maintenance costs, yet it increases the liquid's bubble point, may reduce distillation efficiency, and excessive reflux can cause problems. Both internal and external reflux have pros and cons, and the choice depends on specific operational needs; for demanding distillation, a combination of the two is often used for optimal separation.

Technological Innovation of Continuous Flow Microchannel Reactors in the Pharmaceutical Industry

The text focuses on the quality control and regulatory framework for continuous flow pharmaceuticals. The ICH Q13 guidelines have core requirements including batch definition adaptable to market demands, Process Analytical Technology for online parameter monitoring, and equipment validation for over 100 - hour continuous operation. A typical case is the continuous synthesis of tetrazoles with optimization strategies to increase yield and ensure process safety. There are technical challenges such as reaction system compatibility, equipment congestion and high maintenance costs, and regulatory lag. Solutions involve modular design, innovative materials, clean - in - place systems, FDA's CQA database, and industry collaboration. Future trends include intelligent integration with AI, expansion of green chemistry, biopharmaceutical fusion, and the development of modular factories.

Application Progress of Continuous Flow Microchannel Reactors in the Pharmaceutical Industry

Continuous Flow Technology (CFT) achieves chemical reaction process continuity via equipment like microchannel reactors and fixed beds. Its core advantages are process intensification and precise control, different from traditional batch production. Continuous flow microreactors can solve user pain - points, including increased safety, efficiency breakthrough, consistent quality, and green manufacturing. In pharmaceutical production, CFT can be classified according to reaction systems: gas - liquid reaction system (e.g., carbonylation reactions with a tube - in - tube device for mixing), solid - liquid reaction system (e.g., palladium - catalyzed Suzuki coupling with a long - life catalyst in a fixed - bed reactor), gas - liquid - solid reaction system (e.g., continuous hydrogenation with integrated water electrolysis hydrogen production and extended to deuterated drug synthesis), liquid - liquid reaction system (e.g., Bucherer - Bergs reaction with high - pressure intensification), and multi - phase integrated system (e.g., SPS - FLOW system for automated production of Prexasertib and synthesis of tetrazoloid derivatives).

Continuous Flow Microchannel Reactors in the New Materials Industry（2）

Continuous flow technology has significant advantages but faces challenges like high equipment investment and solid - liquid system clogging in the new materials industry. Continuous flow microreactors offer intelligent integration with PID precise process control and multi - level linkage control, a disc shear flow channel for high - speed shear flow and efficient mass and heat transfer in gas - liquid - solid three - phase reactions, and modular design with industrial - grade skid - mounted features that save floor space and enable full - process automation. Continuous flow technology and microreactors are driving the new materials industry towards efficiency, greenness and customization, covering key fields such as electronics, energy and environmental protection. It's expected that by 2030, continuous flow technology will take over 50% of the market share of the new materials' core process.