Project Synopsis

Provide process design, project management, and startup assistance for the installation and modification of improved sulfuric acid scrubber systems at a specialty metals manufacturing facility.

Project Summary


The client, a specialty metals manufacturer, contracted Process Engineering Associates, LLC (PROCESS) to provide process engineering services in the alternative evaluation and process design for one (1) new sulfuric acid (H2SO4) scrubber and modifications to three (3) existing H2SO4 scrubbers.  In addition, PROCESS provided oversight during detail design of the systems, as well as construction management services during the installation of the new system and modification to the existing systems.

Specifically, the project tasks involved:

  • Performing an evaluation for each scrubber system to define specific design criteria required to meet a more stringent performance standard.  The client operates a non-Title V facility and was proactive in selecting a performance standard for the scrubbers that represents a limit being considered as best available control technology (BACT) for their specific operation.  PROCESS assisted the client in review of applicable regulatory standards as well as applicable exposure limits to help the client select the specific emissions limit.  PROCESS then developed a summary of the specifications required for each scrubber system to meet the more stringent requirement.
  • Developing emissions estimates for each process.  The scrubbers were designed to control emissions from various acid pickling operations in the facility.  PROCESS generated worst-case emission estimates for each process using vapor-liquid equilibrium and mass transfer calculations.  These emission estimates formed the basis for defining the overall acid removal efficiency required for each scrubber.
  • Preparation of piping and instrumentation (P&ID) diagrams for each of the existing scrubber systems so that the design changes could be defined in the contractor’s work scope.  No P&IDs existed at the start of this project for any of the scrubbers.
  • Performing and documenting a hazard and operability (HAZOP) study of each of the existing scrubber systems.
  • Preparation of equipment and instrument specifications for one (1) new scrubber system to replace two (2) older, less effective units tied to one acid pickling operation.  These specifications were used to solicit bids from vendors.
  • Preparation of ductwork specifications for the new scrubber system to effectively capture emissions from the process.  Due to the nature of the process, the company has in place a specified minimum ductwork velocity requirement for these operations. PROCESS generated an hydraulic model of the system to define ductwork sizes required in each branch and in the main headers to maintain this velocity throughout the system.
  • Preparation of equipment and instrument specifications to modify three (3) existing scrubber systems to improve their performance and help ensure that they meet the more stringent standard.  Specifications were generated for new recycle pumps, mist eliminators, caustic addition systems, flow meters, and pressure transmitters.  These specifications were used to solicit vendor bids.
  • Providing oversight during detail design of the systems. PROCESS worked with the client’s engineers and subcontractors to assist in defining the civil, mechanical, and electrical details necessary to install the new scrubber and make the required modifications to existing scrubbers.
  • Development of a functional specification for each system so that it could be programmed by the client process controls integrator.  This included generation of consequence of deviation (COD) tables that could be used as training tools for the operators.
  • Generating contractor work scope documents to define the civil, mechanical, and electrical tasks to be executed by the selected contractor for each system.  This work scope document was used to solicit cost proposals from various contractors.  PROCESS assisted the client in reviewing the proposals and selecting contractors.
  • Providing construction management services during the course of construction for all 4 scrubber systems.  Construction had to be coordinated and completed during scheduled downtimes for each process.
  • Completing the commissioning and startup of each system.  This included system pressure testing, water testing, controls checkout, and final startup to bring the system on line with the process.

Stack tests were conducted on each scrubber after completion of the work and all 4 scrubbers met and/or exceeded the required performance standard.

Industry Type

  • Metals Manufacturing

Utilized Skills

  • Scrubber systems evaluation and design
  • Emissions estimating
  • Project management
  • Detail design and construction oversight
  • Commissioning and startup assistance

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