Project Synopsis

Assist an plant client in optimizing the operation of several wet scrubbers including ammonia scrubbers, a nitrogen dioxide (NO2NO2) scrubber, and an organic acid gas scrubber.

Project Summary


The client owns and operates a facility that manufactures catalytic inserts for automotive and industrial emission control applications.  The production lines are equipped with pollution control systems for abatement of constituents generated in the process.  The client contracted Process Engineering Associates, LLC (PROCESS) to assist them in optimizing the operation of five wet scrubbers: three ammonia scrubbers, a nitrogen dioxide (NO2) scrubber, and an organic acid gas scrubber.  Current operation of the scrubbers was not in alignment with performance criteria and the chemical usage and blowdown rates needed to be evaluated in detail to optimize the process setpoints while minimizing operating costs.  Major project tasks included the following:

  • Setting up models of the scrubbers using PROCESS‘ licensed commercial simulation software CHEMCAD to produce mass and energy balances at peak loading conditions.  Using the models, the performance of each scrubber was evaluated relative to changes in pH, system temperature, scrubber recycle flow rate, and total solids concentration in the scrubber recycle water.  Based on this information, PROCESS provided the client with specific recommendations on changing operating setpoints.  Some of the recommendations included reducing the pH setpoint for the ammonia to improve the overall system performance and minimize the effect of changes in process offgas temperature, and reducing the pH setpoint for the NO2 scrubber to reduce the caustic usage rate while not adversely affecting the NO2 removal efficiency.
  • Preparing a detailed sketch of a new/improved nozzle configuration to improve scrubbing liquid distribution for two of the ammonia scrubbers.  The current configuration resulted in insufficient wetting of the packing.
  • Reviewing the design of the chevron type mist eliminator in one of the ammonia scrubbers to make recommendations to improve its performance.  Based on PROCESS‘ review, it was determined that the existing unit was designed for a higher average system flow rate and, that under current operating conditions, the mist eliminator was operating at less than 10% of flooding.  PROCESS recommended a new/modified mist eliminator with a reduced open surface area to improve performance.

Industry Type

  • Catalyst Manufacturing

Utilized Skills

  • Process troubleshooting
  • Scrubber systems design

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