Batch vs. Continuous

Session Chair & Co-Chair:

• Ross Topliff, Tops Engineering
• Barry Perlmutter, BHS-Filtration Inc.

Session Description:

Many manufacturing processes are initially designed to run in a batch mode, often in laboratory glassware. As they move to commercialization, there are many considerations that inform the decision to keep them as batch or move to a continuous process. This session will explore some of these concerns and how they impact this decision. Examples of the considerations include: yield improvement, temperature control, co-product/by-product minimization, plant capacity, and equipment economics.

Schedule:

A Continuous Diethanolamine Dehydrogenation Fixed Bed Catalyst and Reactor System

Glyphosate is currently the largest volume commodity agricultural chemical. One key reaction step in the cost-efficient route for glyphosate synthesis is the dehydrogenation of diethanolamine (DEA) to form disodiumiminodiacetic acid (DSIDA).  Early process technology reportedly utilized a Raney copper catalyst in a slurry reactor. To reduce processing costs, we sought to develop a continuous fixed bed process that would provide long catalyst lifetime, high DEA conversions, and high DSIDA selectivity, eliminating the operational costs associated with catalyst attrition, catalyst recovery, and catalyst recycle using slurry reactor technology, and increasing the operational efficiency relative to slurry-based batch processing.  In this summary of our development program, we highlight key findings converting from a batch to a continuous oriented process while reviewing the scale-up methodology.

Continuous Pressure and Vacuum Filtration Technologies as Alternatives to Batch Filtration Operations  

This presentation will discuss lab testing, pilot testing and scale-up for converting chemical processes to continuous filtration technologies from batch filtration operations.  The overall scheme can be used by process engineers to develop optimum continuous pressure or vacuum filtration solutions for high-solids slurry applications. In this first process a liquefied gas slurry is used to produce a specialty chemical.  A liquefied gas is a clean, colorless gas that is easy to liquefy and transport.   It is gaseous at normal temperature and pressure, but changes to a liquid when subjected to modest pressure or cooling.  The most important point is to keep these gases, under pressure, so they behave as a liquid during filtration, cake washing and drying.  The presentation discusses the process testing in the laboratory and in the field to evaluate continuous pressure filtration as an alternative to batch pressure filtration. In this second pharmaceutical process, the objective is to replace the current batch centrifuge with a technology that would be suitable for conversion to a continuous process.  The initial lab tests suggested a vacuum belt filter would achieve cake quality equal to or better than the current centrifuge with a major reduction in processing time.  The decision, after the lab testing, was to select a vacuum belt filter for pilot testing. The presentation includes technology descriptions, discussion of specifications and general guidelines for performance guarantees.

Advantages and Limitations of a Nitration Reaction Performed in Batch vs. Continuous Mode

Nitration reactions are commonly utilized in the pharmaceutical industry to synthesize aromatic amines.  Developing safe, scalable nitrations can be challenging since these reactions are generally highly exothermic and result in the production of energetic, nitro containing compounds.  While incorporating a continuous configuration for these reactions may help address some of the safety concerns due to a reduced in-process volume of reactive species and greater heat transfer, batch configurations may also offer significant advantages.  This presentation will provide a comparative case study on the advantages and limitations of continuous and batch configurations for the nitration of a pharmaceutically relevant pyrrole.  Included will be details of the laboratory scale process development activities and process demonstrations conducted at scales from 500g to 2.5 kg.