Troubleshooting Distillation Controls

Topic Process Operations

CPD Hours 11.5

Price IChemE member £720 + VAT, non-member £864 + VAT


Live online course – starts on 20 October 2020.

Join recognised expert Henry Kister online to learn how to get the best performance from a distillation column control system. 

Through Henry's extensive experience, you will learn how to troubleshoot a distillation control system and identify causes of poor performance, evaluate existing column control performance, avoid common causes of instability, and develop improvements to your column control system. Henry will use case studies throughout to illustrate the principles and illustrate control systems that did not work. 

Teaching will be delivered via two live modules (approximately three hours in length each) and will include Q&A sessions.

An e-certificate will be issued at the end of the course to confirm attendance and CPD hours logged.

Learning outcomes

By the end of this course you will understand how to:

  • troubleshoot a distillation control system and identify causes of poor performance
  • evaluate existing column control performance and develop new designs
  • avoid common causes of instability, off-spec products, excessive energy consumption, hammering, fouling, and other operating issues resulting from deficiencies in the control system
  • incorporate lessons from past experience for developing or improving a column control system

Who will benefit

  • engineers and operation personnel responsible for operating, troubleshooting, designing and revamping distillation columns in the chemical, petrochemical and oil refining industries
  • process control engineers engaged in control system optimisation and improvements
  • managers and supervisors endeavouring to get the best performance from an existing or new distillation unit 

Course outline

Distillation control overall schemes troubleshooting

Assembling control loops into an overall scheme: what works, what causes instability, and what impairs efficiency. The three most common causes of control assembly failure: no material balance control, fighting between temperature controllers, and level control on a small stream. What may happen in the absence of adequate material balance control? The three most common column control schemes: pros and cons. Is it better to connect the column temperature (or composition) control to the boilup or to the reflux? Is there a control scheme that can handle ambient disturbances better? What can go wrong with controlling a liquid level on a small stream? What makes violation of this principle the No. 1 control problem in refineries (and in many chemical plants)? Is your fractionator immune?

Troublesome temperature controls and sidedraw controls

How does subcooling affect internal reflux flow rate and its control? Is internal reflux control useful? Why distillation control schemes often break down in the presence of a side draw and what can be done to make them work. Can internal reflux control help? Temperature control: is it better to have the control thermocouple in the liquid or in the vapour? Best temperature control tray location: is there a reliable method that can find? Using simulations to search and find. Application to several case studies: what does this method reveal about the tower in each case, and how it can guide the solutions. What is the effect of non-key components? Issues with enhanced distillation column controls: azeotropic distillation and extractive distillation, and what has achieved success in controlling them. Analyser controls: is it the panacea for composition control? What has been the experience with an analyser control cascading onto a temperature control?

Pressure and condenser process controls troubleshooting

What makes good pressure control so critical? A vapour top product: how pockets in vapour lines destabilise pressure controls. Flooded condenser pressure controls for total condensers: how can the piping connections to the reflux drum make or break the control stability. Why can flooded condenser pressure controls break down in the presence of non-condensables, undersized equalizing lines, slots in the dip pipe entering the reflux drum, and what can help avoid these issues. Does inert padding help, and at what cost? Understanding hot vapour bypasses: why some work while others don’t. Hot vapour bypass good and bad practices. Flooded reflux drums: pros and cons. Manipulating the coolant rate: when can it be troublesome? How manipulating the cooling water flow can accelerate fouling and corrosion. Liquid product with a small vapour vent stream: why controlling the cooling water may sometimes be unavoidable, and what can be done to overcome shortcomings. Interference between vacuum and coolant controls.

Reboiler process controls troubleshooting

Reboilers heated by condensing steam or vapour: a control valve is in the steam inlet line versus valve in the condensate outlet line. Is the dynamic response with the steam inlet valve always better? Reboiler seal loss with the condensate outlet valve and how avoided. When does the condensate outlet valve scheme have a major energy-efficiency advantage? Fouling, corrosion, and thermal stresses: which of the schemes can handle each of these issues better? Steam trap unreliability issues with the steam inlet valve scheme: how to overcome. Startup and low rate operation with the steam inlet valve scheme: reboiler “stall”, instability, how to prevent. Hammering: how a scheme incompatible with your condensate system can lead to instability and hammering. Equalising lines to the condensate pot: checking out for poor configurations that can induce instability, hammering. Tube leaks: which scheme is better suited to handle a potential tube leak in different circumstances? Reboilers heated by sensible heat: why are the controls of these far less troublesome, and a brief discussion of their few issues.

Q&A sessions

These are primarily intended to answer questions on the presentation. However, if time permits, these sessions may provide an opportunity to briefly discuss plant issues with Henry and with other participants.

Please note:

The following topics are outside the scope of this course and will not be covered: advanced controls of distillation columns, constraints controls, batch distillation controls, reactive distillation controls, controls of dividing wall columns, setting tuning constants, control valve selection, actuators, and control hardware. 

Module dates and times

Module 1

Tuesday 20 October 2020, 18:00–21:00 BST.

Module 2

Thursday 22 October 2020, 18:00–21:00 BST.

Not available then? Register your interest in future course dates.


  • IChemE member: £720 + VAT
  • Non-member: £864 + VAT


Discounts are available to companies booking more than one place:

  • 2 places–10% discount
  • 3 places–15% discount
  • 4 or more places–20% discount.

Bookings must be made at the same time to receive the discount.


Modules will be delivered via GoToWebinar®check system requirements >>

You are advised to join the session at least ten minutes before the scheduled start time, to allow for your computer to connect.

In-company training

This can also be delivered as a virtual in-company course. Contact us for more details.

Henry Kister


Henry Kister

FIChemE, Fluor

Henry, 'the tower doctor', is a recognised specialist with a vast background in all phases of distillation, including operation, troubleshooting, controls, design, start-up, and research.

At Fluor he designs, revamps and advises on distillation processes, equipment and controls for the chemical, petrochemical and oil industries. He is also extensively involved in field consulting, start-up and troubleshooting assignments and in developing Fluor’s in-house distillation technology.

He is the author of three textbooks - Distillation Operation and Distillation Design (McGraw-Hill Inc., 1990 and 1992) and Distillation Troubleshooting (Wiley Interscience 2006) - the Distillation Equipment chapter in Perry's Handbook (2008, 2018), over 120 technical articles, and has presented IChemE's Practical Distillation Technology course over 500 times.

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