Air emissions for TAR depressurization and chemical decontamination

The beginning of a turnaround (TAR) sets the tone for the next 30-45 days of facility shutdown maintenance activities.

Years of planning come to the forefront the minute a unit or facility goes into deinventory and depressurization. Every minute a unit is offline is money lost, which is why the investment in planning and scheduling is so critical. During the planning phase, discussions focus on optimizing the sequence of events needed to efficiently shut down a unit or facility. Key questions addressed include:

• What is the flare system’s availability?

• Does sulfur content limit the use of the flare?

• What is the Flare Gas Recovery (FGR) capacity?

• Do we have to stagger unit shutdown due to high loading of VOCs, nitrogen gas or steam?

• Are there environmental and air permit constraints?

• Is there a better way, and have we looked at air compliance alternatives?

If you have engaged in discussions concerning any of these questions, you know that sequencing and optimization are vital for setting the stage for the TAR. Let’s address alternatives to each of these scenarios that may provide new perspectives on sequencing and optimization. Flares can be a potential option. However, this is a bit of a gray area as recent EPA decisions aim to limit their use in emergency situations. If the facility’s permit and environmental team approve this method, it can be effective for depressurization and decontamination during the TAR.

FGR is a viable alternative for those who have constraints due to flare usage. Reviewing past TAR data can provide insights into issues like high nitrogen gas and steam loading, which can cause FGR compressors to trip. When choosing a combustion control device, it’s essential to consider sulfur dioxide and hydrogen sulfide levels, with key metrics being 162 ppm on a three-hour rolling average. If your stream exceeds this level for flare use or after amine treatment in FGR, you’ll need to seek an alternative control device solution.

Vapor Point offers temporary applications for each of these scenarios to optimize your TAR in terms of depressurization and decontamination. Our extensive fleet of thermal combustors can be combined with state-of-the-art condensing systems, pressure regulator skids, detonation arrestors and scrubbers, all controlled by centralized programmable logic controller systems. These systems effectively handle high sulfur dioxide and hydrogen sulfide laden VOC streams during depressurization and route them from the flare or FGR and into thermal combustion equipment for optimal unit shutdown.

For chemical decontamination, Vapor Point provides many alternatives to FGR, including blowdown and scrubber systems that manage all material from the decontamination header, ensuring an FGR and flare-free cleaning process. These tools can be implemented to prevent staggered shutdowns due to FGR and flare limitations. Vapor Point helps bridge the gap between operations and environmental compliance on complicated TAR activities while providing predictable shutdown schedules and costs.

For more information, visit vaporpoint.net.