Systems Overheads: Finding the Right One for Your Process

distillation overheadsOverheads are components that, when integrated with your reactor (or other type of vessel), create a system to efficiently carry out reactions, distillations, and other process operations.

There is a library of choices to select from for your overhead needs, including individual process components, equipment/process arrangements and material of construction options. This selection is critical because it will determine the functionality of your system to meet current and potentially future needs/ capabilities.

In this post we’ll define the various components that make up system overheads and arrangement options. While most of this information relates directly to overheads offered by De Dietrich Process Systems, there is also generic data that is applicable to overheads available from other equipment vendors.


Overhead Components

While the individual items selected to make up your overhead arrangement are dictated by your process objectives and requirements, here’s a breakdown of the multitude of elements that can be incorporated into an overhead configuration:

  • Condenser – A form of heat exchanger, condensers are used to condense hot medium from the vapor phase to the liquid phase.
  • Phase Separation Vessel – Phase separators are used primarily for separating two liquid phases but can also be used for the separation of the liquid and gaseous phases of a solution.
  • Column (with internals) – The principal role of a column is to aid in purifying a feed via mass transfer.
  • Cooler – This term represents heat exchangers used for subcooling distillate or lowering product temperature for handling/further processing.
  • Reflux Divider – A reflux divider is a piece of equipment that allows the system to be switched between reflux and distillation configuration. They can be manually operated or automated.
  • Process Piping – Piping provides a means for contained transfer/flow of product between various process components.
  • Instrumentation – Various instrumentation devices are available to measure various conditions/properties and input for controlling the process. Some common parameters for overheads instrumentation include temperature, pressure and flow(s).

Identifying your process goals early in the selection process will make it easier to determine what overhead components are needed for your system.


Materials of Construction

There are many options available for your overhead’s material of construction. MOC selection is typically the same as or compatible to other portions of the plant/process in terms of corrosion resistance, pressure and temperature requirements and constructability (with regards to purpose, economics, design restraints, etc.). While the material of construction selection is driven by many factors, ultimately the most important is the process requirements. However, secondary concerns such as ease of use for the operator and maintenance can make a world of difference and should be taken into consideration.


Overhead Configurations

Overheads come in many shapes, forms, and purposes which, when combined together or installed in series, can greatly enhance your process. Reaction and distillation processes form the backbone of most chemical and pharmaceutical systems and are frequently executed together in order to elevate the process and improve overall efficiency. Since overhead arrangements are customizable, there is an extensive variety of layouts available to meet a wide range of applications. Popular options include:

  • Boiling under Reflux & Distillation
  • Distillation with Phase Separation
  • Vacuum Distillation
  • Rectification

For more information and to see illustrated examples of these the overhead options, visit our system overheads page.

Once you have assessed what type of overheads your process calls for and the best material of construction for the process, it is time to calculate the size of the equipment and layout. De Dietrich Process Systems can take the hassle out of overhead design with a team of experts who can properly select, size, and layout your overheads to ensure your process is optimized for efficiency and production. Contact us today to review your application.


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