Project Synopsis

Complete a Reasonably Available Control Technology (RACT) evaluation for scrubbing nitrogen oxides (NOx) from a metals cleaning and etching operation vent gas stream in support of Title V air permit compliance.

Project Summary

NITROGEN OXIDES (NOX) SCRUBBER ALTERNATIVES EVALUATION

The client owns and operates a specialty metals manufacturing facility and contracted with Process Engineering Associates, LLC (PROCESS) to complete a Reasonably Available Control Technology (RACT) evaluation for scrubbing nitrogen oxides (NOx) from a metals cleaning and etching operation vent gas.  The client operates under a Title V air permit and was required to perform a RACT evaluation for modifications to the metal cleaning process.  There are no source-specific RACT determinations for this application; therefore, the process was evaluated by a case-by-case technology evaluation to determine if any NOx control techniques would be both technically and economically feasible in accordance with RACT standards. 


The process was equipped with an existing acid gas scrubber to control hydrofluoric acid (HF) and nitric acid (HNO3) emissions from the process.  The technology review focused on selection of a technically and economically feasible control alternative to use in conjunction with the existing acid gas scrubber to remove NOx and maintain the acid gas scrubbing capabilities. 

Specific project tasks and deliverables included the following:

  • Characterization of the process vent gas emission rates (both average hourly and peak hourly) for all three components using actual process data and historical stack test data.
  • Detailed review of the technical feasibility of potential new control alternatives to operate in conjunction with the existing acid gas scrubber to control NOx.  Technologies reviewed included Wet Scrubbing (singe-stage and dual-stage), Selective Catalytic Reduction (SCR), Selective Non-Catalytic Reduction (SNCR), and Wet Phase Catalyst.  Based on the review, Wet Scrubbing and SCR were considered the two technically feasible control alternatives for this application.   
  • Generation of a scrubber specification and submittal of the specification with a request for budget level quotes to three vendors. 
  • Review of vendor bids to develop an economic comparison of each technically feasible control alternative.  The economic evaluation included installed capital costs as well as annual operating costs for each alternative and a comparison of these costs with the expected NOx control performance of each system.  For the Wet Scrubbing system, both single-stage and dual-stage systems were evaluated to determine the economic benefit (from an emissions reduction standpoint) of the additional capital expenditure. 
  • Preparation of a RACT Summary Report to be submitted by the client to the state air permitting agency. 

Industry Type

  • Specialty Metals Production

Utilized Skills

  • Emissions system design
  • Emissions systems alternative evaluations
  • Technical and economic alternative evaluations
  • Air permit compliance process engineering assistance

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