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Controlling Refinery Emissions with a Holistic Scrubbing Solution

Refiners around the world are facing stricter emission limit requirements from national or regional bodies. The recent sulphur emission target changes in China are only one of the many examples. EU countries, as well as India are looking into the same matter. On the other side of the Atlantic, the United States Environmental Protection Agency (US EPA) is proposing a new Clean Air Act targeting the emissions of hazardous air pollutants from petroleum refineries. The suggested new rule - RIN 2060-AQ75 - would revise emission control requirements for flares, storage tanks and coking units at oil refineries, as well as eliminate emission limit exemptions during start-up, shutdown and malfunction (SSM) periods.

In the drive to continue satisfying market demand, the refining industry has also had to increase production from unconventional oil fields with heavy oil fractions. That has resulted in products with higher sulphur content, increasing the need for desulphurization technologies.

Refiners, therefore, now have to address a triple challenge: process increasingly sour crude while simultaneously reducing emissions and increasing output. That is not an easy task, particularly in the current market.

To tackle this challenge, DuPont Clean Technologies offers two complementary, proven scrubbing systems as a solution for refiners who need to cut SOx emissions and/or need to control particulate emissions efficiently. Common sources of airborne pollutants in a refinery are:

• FCCU regenerators (SOx, NOx, particulate)

• Claus plants – with or without TGTU (H2S, SOx)

• Sulphuric acid regeneration units (SOx)

• Fluid cokers (SOx, NOx, particulate)

• Fired heaters (SOx, NOx, particulate)

• H2S flares (H2S)

• Power plants and boilers burning HFO, coal, petroleum coke (SOx, NOx, particulate)

Many refiners struggle to control emissions effectively and efficiently. By reducing atmospheric emissions of H2S, SOx, NOx and particulate from major refinery sources, the BELCO® EDV® Wet Scrubbing and the MECS® DynaWave® Wet Scrubbing systems together provide a holistic solution that makes air pollution control easy and reliable. Refiners that have installed such scrubbing systems have been able to easily handle the liquid and solid by-products of scrubbing with their existing on-site facilities and practices.

The BELCO® EDV® Wet Scrubbing Technology (BELCO® Technology) is well suited and widely used for treating flue gas from fluid catalytic cracking units (FCCU) regenerators, fluid cokers, fired heaters and boilers. Its unique open-tower design and special non-plugging features control all emissions in a single upflow tower, eliminating the need for separate devices to individually control particulate, SOx and NOx emissions. The MECS® DynaWave® Wet Scrubbing Technology (DynaWave® Technology) is an excellent Claus tail gas treatment unit (TGTU) supplement or, in the case of small SRU’s (lower than 50TPD capacity), even an alternative to the Claus TGTU. By injecting the caustic liquid countercurrent to the gasflow, this scrubber type will work under much higher liquid to gas ratio’s than conventional caustic scrubbers. This unique feature allows to handle much higher acid levels and therefore operate even when the upstream TGTU is in start-up, shut down or malfunctioning (SSM) mode. In addition, the DynaWave® Technology is widely used in sulfuric acid regeneration units and perfectly suited to treat H2S flares. With the combination of these complementary refinery scrubbing technologies, DuPont Clean Technologies offers an integrated solution to refiners’ environmental needs.

1. Continuous emissions control for critical refinery processes:

An unscheduled shutdown of a major refinery process unit is not an option for the majority of refiners. Process units are expected to operate 24 hours a day, 365 days a year for multi-year operating campaigns. Whatever the scenario, emissions must be minimised while product is generated and sold to the market. The BELCO® Technology is a proven and robust technology that can reliably control FCCU regenerator flue gas emissions in a single upflow scrubber tower for years of uninterrupted operation. With over 140 units licensed on FCCUs worldwide and additional systems on other major refinery processes (fluid cokers, fired heaters and boilers), this low energy wet scrubbing system has been recognised by oil refineries around the world as the leading scrubbing technology in its field. The BELCO® Technology supports FCCU operating campaigns typically running 3 – 5 years or more of uninterrupted operation , providing continuous emission controls with no maintenance shut downs. This allows refiners to keep the FCCU running at all times, while controlling flue gas emissions and keeping emission control costs as low as possible, so they can focus on production.

2. Flexibility in use for SRUs:

As a result of the new regulations, oil refiners will not only have to meet air emission requirements for sulphur plants during normal operations, but now also during SSM periods. They must operate under these constraints while meeting production goals. In many regions that includes operating the facility continuously and reliably for a minimum cycle of four to five-years, and generating products that meet the market’s quality expectations in an economically viable way. This had led a large number of refiners to consider parallel trains to assure continuous reliability, but is this cost really a necessity?

The DynaWave® Technology is the only wet gas scrubber technology that makes it possible to fully bypass the Claus unit or the Claus TGTU directly to the incinerator and still meet emission limits at the stack. The DynaWave® Technology is >99% efficient in removing SO2, which can bring emissions down to ultra-low levels under any given circumstances at the upstream sulphur plant. It offers a very reliable and easy to operate, low capital investment solution with a minimal footprint. The high on-stream reliability is proven in more than 400 installations in various industries worldwide. The DynaWave® Technology combines gas quench, SO2 removal, particulate elimination and sulphite oxidation all in one vessel, making it ideal for some of the most demanding applications. Around two dozen installations were specifically designed for sulphur removal tail gas treatment applications within refineries. Recently, the DynaWave® Technology was integrated in an existing Claus unit design for a facility in the Middle East. Here, acid gas flaring in all possible operating scenarios, including start-up to shut-down and maintenance, will not lead to an increase of SO2 emissions. Other operating examples like this exist in other regions like East Asia and North America and more new designs are being engineered as we speak in those regions, as well as in North-Africa

New refineries in Africa and Asia are currently also being designed to include both wet scrubbing technologies from DuPont Clean Technologies to meet environmental requirements under any given circumstance and to achieve continuous and reliable operation.

A DynaWave® scrubber in a US-refinery, by now in operation for almost 15 years.
Controlling Refinery Emissions with a Holistic Scrubbing Solution

Conclusion

Emission control technologies must support refining production goals. Refineries must be able to operate continuously and reliably in order to meet market demand for quality and cost without generating emissions that violate regulations. By treating the main sources of SOx emissions in the refinery segment with BELCO® EDV® Wet Scrubbing and MECS® DynaWave® Wet Scrubbing technologies, DuPont Clean Technologies offers an integrated technical solution to SOx emissions control for both new and existing refineries all around the world.

DuPont (NYSE: DD) has been bringing world-class science and engineering to the global marketplace since 1802. DuPont’s Clean Technologies division applies real-world experience, history of innovation, problem-solving success, and strong brands to help organizations operate safely and with the highest level of performance, reliability, energy efficiency and environmental integrity. Our Clean Technologies portfolio includes STRATCO® alkylation technology for production of clean, high-octane gasoline; IsoTherming® hydroprocessing

technology for desulfurization of motor fuels; MECS® sulfuric acid production & regeneration technologies; BELCO® air quality control systems for FCCU flue gas scrubbing & other refinery scrubbing applications; MECS® DynaWave® technology for sulphur recovery and tail gas treating solutions; and a comprehensive suite of aftermarket service and solutions offerings.