Refractory “Terminator”

Many new cement production facilities that have been commissioned within the last ten years have experienced many “unpredictable” refractory problems. These refractory problems have been a major issue because of the lost production time, huge repair costs, on-going litigation and a general misunderstanding of the refractory problems. We can compare these refractory problems to the original movie “The Terminator”.

The Refractory Terminator

In the Year of Darkness, 1999, the refractory engineers of this planet devised the ultimate plan. They would reshape the Future by changing the Past. The plan required something that felt no pity. No pain. No fear. Something unstoppable. They created 'THE REFRACTORY TERMINATOR'.

Each new cement pyro-processing system is a potential “terminator”. It may not rest until it destroys production goals, ruins the plant staff’s every weekend, annihilates maintenance budgets, devastates morale, wrecks havoc, creates “hellish environments” and finally “terminates” the Production Manager before he can fix all the problems.

Terminator’s Arsenal

Most common refractory problems associated with new construction usually surface from 1 to 3 years after commissioning or after numerous thermal cycles.

Some of the common problems encountered are:

  • Anchor Failures
  • Anchor Corrosion
  • Shell Corrosion
  • Sulfur / Alkali problems
  • Buildups and Kiln Rings
  • Non-reversible vessel movement
  • Mechanical expansion joint problems
  • Refractory expansion joint problems
  • Non-reversible refractory expansion
  • Insulation phenomena (Skamol)
  • Unsuitable refractory compositions
  • Inadequate refractory design
  • Improper installation techniques
  • Effects of severe thermal cycles
  • Problems related to Kiln Mechanics
  • Effects of Alternative Fuels (See Sept. 2008 International Cement Review)
  • Combustion problems in the Tower and/or Kiln

Hellish Cooler Stalagmites

Some of these refractory failures may seem straight forward to detect, howevermost refractory failures are a result of a complex combination of multiple variables and process conditions.To a trained refractory expert, the condition of the refractory can be used as clues to problems with the process or mechanical systems.

Damage Control

These problems usually begin to fester immediately upon commissioning but may take time until the catastrophic effects are seen as refractory failures. Many plants just ignore the Terminator in hopes that he may go away or tend to adopt some of the following strategies:

  • Failed refractory linings are acceptable without question.
  • Failed refractory linings are considered “consumables”.
  • Only “unexpected” lining failures are questioned

Plants seldom perform the following analyses to investigate problems:

  • Proper post-mortem analysis.
  • Reverse-engineer failed refractory to calculate the thermal stress / conditions.
  • Correlate lining failures with the process / process changes.

Most refractory failures represent a headache in assigning blame. There are refractory material manufacturers who can prove that their materials were correctly manufactured, refractory contractors who can show that they installed the materials per the engineered drawings, refractory engineers who can show that they followed the owner’s specifications, all these people blaming the process conditions and plant operations.

Many refractory issues are currently “solved” with the following methodology;

  • Gather all involved parties together
  • Point fingers at each other
  • Never determine the real reason for the failure
  • Let the other parties speculate on a solution
  • Point more fingers on who is going to pay
  • Complete the project status quo
  • Repair the refractory again….and again
  • Meet in court a few months later (truly a “hellish environment”)

Refractory Negotiations

As a result of spending hundreds of millions of dollars for a new pyro-processing system, the owner (or owner’s insurance company) usually gets stuck with the bill for all the ongoing outage refractory repairs and lost production in the battle against the “terminator”.

Independent refractory engineers capable of correctly identifying the failure mechanisms are a rare commodity so the plant often uses their own judgment or depends on the refractory manufacturer, OEM or installer representatives for evaluation. Usually none of these people are qualified to determine the root-cause analysis of the failure and are usually biased in some manner. Since a correct failure analysis is not performed, it becomes difficult to address the optimum solution to the problem.

Battle Strategy

Resolutions to refractory issues are currently based on trial and error, rules-of-thumb or refractory mythology. This is because few people truly understand the non-linear properties of the refractory, the thermo-chemical (corrosion) reactions of the refractory/anchor with the process environment and the thermo-mechanical interactions of the refractory and steel shell.

Of course, the ultimate solution to resolving refractory problems is to take proactive steps during the original design and specification procedures. Once beyond this stage and the owner realizes that they are dealing with a “Terminator”, a battle strategy must be developed to combat the pitiless enemy and “stop the bleeding”.

The first step in the strategy should be to enlist the assistance of an independent refractory expert. (Note that having a refractory “craftsman” watch the installation has not served to relieve any of the refractory related problems). The refractory consultant should be able to spearhead any aspect of refractory related problems:

  • Provide leadership in problem resolution
  • Identify the problem (root-cause refractory failure analysis)
  • Propose the solution (refractory engineering)
  • Orchestrate all processes in obtaining the solution
  • Take steps to avoid project delays
  • Take steps to avoid (or prepare for) legal actions

Fire and Brimstone – Signs of Damnation

“I’ll be back”

Even if the plant has been successful at solving some of the refractory problems and keeping the “Terminator” at bay, refractory problems can (and will) still arise. Changes in process, fuel, refractory, or seemingly unrelated conditions could result in compounding problems that will disturb the Terminator into the next round of battles. So if Sarah Conner is not available to help fight off the refractory terminator, I suggest you contact a Cement Industry Refractory Consultant to assist in the battle.

Andy Porterfield