NO2 Emissions Mitigation Technical and Economic Evaluation

Project Synopsis

Project Summary

The client, a world-wide producer of industrial gases, is currently storing pressurized NO₂ cylinders outdoors at a northeast US production plant, unenclosed, but distant from plant personnel.  A protective sealed dome over the cylinder valve must be removed to access valves and fittings.  PPE and a portable gas detector are used when the protective dome is unsealed.  Any fugitive emissions contained within the dome or released during cylinder handling are released to the environment untreated.

The client would like the ability to access the large main cylinder valve and valve manifold such that cylinder valves may be cycled while connected to the manifold as well as to have the ability to transfer NO₂ between cylinders.  The client has identified an industrial gas storage cabinet that will serve this purpose.  The enclosure is kept slightly sub-atmospheric by continuous air sweep.  The cabinet allows plant personnel to safely access cylinder and manifold, make/break pigtail connections to the manifold, and provides emergency handling of NO₂ gas in the event of a valve, fitting, or tubing failure.

The valve manifold within the proposed cabinet enclosure will have periodic and expected vent gas purges containing high concentrations of NO₂.  There is also the remote possibility that a hardware failure or operator error may result in a rapid, high-flow gaseous release of high NO₂ concentration.  These releases must be routed to an emission mitigation system to protect plant personnel.  Process Engineering Associates, LLC (PROCESS) was contracted by the client to evaluate applicable technology solutions to treat/mitigate NO₂ emissions from the proposed storage cabinet.  The emission specification leaving the mitigation device is 10 ppmv.

PROCESS evaluated several competing NO₂ mitigation technologies.  These included wet scrubbing utilizing an aqueous solution of NaOH, H₂O₂, and NaSH, selective catalytic reduction (SCR), dry scrubbing (sorbent injection followed by a baghouse), and a dry solid bed (sorbents evaluated included activated carbon and zeolite).  PROCESS rated the proposed solutions based on ability to satisfy emission constraint and cost.  PROCESS recommended a wet scrubbing process to the client.

The recommendation was accepted by the client.  PROCESS contacted several technology suppliers and obtained competitive bids. A bid tab was developed and submitted to the client.  PROCESS also recommended a specific technology. The client reviewed documentation and agreed with PROCESS’ recommendation.  At present, the client is in the process of completing a capital expenditure request to proceed with purchase and installation of the recommended scrubber system.

Industry Type

Utilized Skills

• Process alternative evaluations