Flint Hills’ Minnesota refinery due technology, efficiency upgrades

Flint Hills Resources Pine Bend LLC, a subsidiary of Flint Hills Resources LLC (FHR), Wichita, Kan., is proposing a collection of projects designed to increase energy efficiency, reduce air emissions, and improve processing capabilities at its 339,000-b/d Pine Bend refinery in the city of Rosemount, Dakota County, Minn.

Known collectively as the Pine Bend Technology and Efficiency Improvement Projects (TEIP), the undertaking will include three independent but time-related projects involving improvements to the refinery’s processing efficiency by means of heat recovery, replacement and modernization of aging equipment, and more efficient use of existing equipment, the Minnesota Pollution Control Agency (MPCA) said in a public notice.

As proposed by FHR Pine Bend, TEIP specifically would entail execution of the following three projects:

• The Coker Replacement Project (CRP), which includes replacing two older, less efficient delayed coking units as well as the refinery’s largest nitrogen oxide (NOx)-emitting heaters with one delayed coker and a single, more-efficient heater to reduce overall NOx emissions at the site by more than 350 tonnes/year.

• The Diesel Selectivity Project (DSP), which involves installation of equipment and modifications to existing equipment to enable the refinery’s flexibility to increase production volumes of ultralow-sulfur diesel (ULSD) from its distillate hydrocracker.

• The Naphtha-Processing Improvement Project (NPIP), which includes modifying existing equipment to improve the refinery’s capability for naphtha hydrotreating (gasoline-blendstock desulfurization).

While TEIP intends to boost output of ULSD from the Pine Bend manufacturing site, the refinery’s nameplate crude capacity will not change as a result of the individual projects, according to an environmental assessment worksheet (EAW) prepared by MPCA for public review.

The public comment period on the EAW for FHR Pine Bend’s TEIP ends on Oct. 26.

TEIP details

In its submission to MPCA for the EAW, FHR Pine Bend provided detailed descriptions for TEIP’s three separate projects that, pending necessary approvals, are all due for startup by yearend 2020.

The CRP, which aims to increase operating efficiency and reduce NOx emissions from the refinery, will consist of the following components:

• Replacing delayed coking process units No. 1 Coker (21-1 Unit) and No. 2 Coker (21-2 Unit) with the single delayed coking unit No. 4 Coker (24 Unit).

• Installing an integrated gas recovery unit—which is currently separate from the existing coker—to achieve a more energy-efficient design.

• Installing a No. 4 Coker Process Heater (24H1) that will fire natural gas and fuel gas, use low-NOx burners, and include selective catalytic reduction (SCR) as a control technology system. Alongside eliminating emissions associated with periodic heater decoking, the heater also will help to improve product yields, FHR Pine Bend said.

• Decommissioning of the 21H1 and 21H2 process heaters.

• Repurposing of the existing coker gas-recovery unit, 15 Unit, associated with No. 1 and No. 2 Cokers, into a saturated gas-recovery unit to support other existing process units that produce refinery gas.

If approved, the modular construction of CRP’s No. 4 Coker is scheduled to begin in second-quarter 2017, with projected commissioning of the unit to occur sometime in 2020.

As part of FHR Pine Bend’s goal to improve the refinery’s production of diesel without requiring installation of combustion sources, the DSP will include installation of a gas oil vacuum fractionator within the 38 Unit Gas Oil Hydrotreater (GOHT) to process desulfurized gas oil from both the 38 Unit and 33 Unit GOHT, as well as improvements to the refinery’s existing distillate hydrocracker, 29 Unit, to increase its productivity and yield.

The gas oil vacuum fractionator will help lift light gas oil (distillate-cut material) out of the gas oil before heavier gas oil is fed to the fluid catalytic cracker, 17 Unit; recovered distillate cut will then feed either a distillate hydrotreating unit (desulfurization) or the 29 Unit to increase the refinery’s yield of ULSD.

Once modified, the 29 Unit will be able to hydrotreat feed for production of low-sulfur fuels and crack feed to increase liquid-volume yield.

While FHR Pine Bend will not modify GHOT heaters as part of the DSP, the operator does plan to increase utilization of the heaters when capacity is available, MPCA said.

Because the DSP will require additional hydrogen to support increased hydrotreating and cracking activities, FHR Pine Bend also plans to install equipment designed to increase hydrogen yield via energy integration at the refinery’s No. 4 Hydrogen Plant, eliminating the need for installation of additional fired-heater capacity at the site.

The DSP also will include an amine efficiency project that consists primarily of switching the amine chemical from monoethanolamine to diglycolamine to more efficiently remove sulfur from refinery fuel gas via use of less steam for amine regeneration.

The amine-efficiency portion of DSP additionally will involve pumping improvements at the upstream hydrotreaters to increase amine circulation for proper sulfur removal, the EAW said.

Construction on DSP is scheduled to begin in second-quarter 2017, and while some project components will start up in 2017-18 due to a relatively short construction timeframe required for modifying existing process units, FHR Pine Blend plans to commission the entirety of DSP in early 2019 upon completion of the gas oil vacuum fractionator.

With the goal of equipping the refinery to operate more efficiently and closer to its capacity by increasing its production of diesel, gasoline, and other products, the NPIP will involve the following:

• Installation of piping to reroute distillate and gas oil hydrotreater naphtha to the 29 Unit’s fractionation section, which will allow the stream to avoid reprocessing as well as create additional capacity in the naphtha desulfurization units and splitters.

• Installation-modification of equipment in volatile organic compounds (VOC) service at the refinery’s smallest naphtha hydrotreater (31-5 Unit) to help increase overall naphtha processing capabilities.

• Installation of new and upgrading of existing equipment at two of the refinery’s naphtha hydrotreaters (28 Unit, 37 Unit) to increase runtimes between catalyst-replacement outages to result in increased annual utilization of the units.

Aside from the addition of fugitive equipment in VOC service, FHR Pine Bend does not plan to modify existing emissions units (i.e., heaters) as part of the NPIP, MPCA said.

With start of construction on NPIP also slated for second-quarter 2017, FHR Pine Bend said primary elements of individual projects at the 31-5, 28, and 37 Units are due to be completed and commissioned in conjunction with their respective unit turnarounds scheduled between 2018-20.

Future splitter project

In addition to the TEIP, FHR Pine Bend also is assessing a separate project at the Minnesota refinery that would involve adding a unit for production of polymer-grade propylene (PGP), according to the TEIP’s EAW.

Still under consideration by the operator, the potential PGP unit at Pine Bend would include installation of a PGP splitter, a de-ethanizer column, an electric heat pump compressor, as well as associated pumps and piping, MPCA said.

If built, the PGP unit would upgrade the refinery’s existing production of refinery-grade propylene (RGP) to higher-priced PGP product, using the refinery’s existing RGP storage and rail infrastructure to store and transport PGP.

While a timeframe for FHR Pine Bend’s decision on the proposed project remains unclear, if approved, the company would begin construction in 2018 for a targeted startup of the PGP unit sometime in 2019, MPCA said.

Contact Robert Brelsford at rbrelsford@ogjonline.com.

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