Operators and contractors are continually pressing the technology envelope in efforts to improve the reliability and efficiency of refineries.
Two of the main areas of focus are the engineering design and turnaround stages, as they provide the best opportunities to build in reliability.
Other main focus areas are process efficiencies, monitoring and diagnostics solutions, advanced instrumentation and controls technologies, and continuing improvements in catalyst selectivity and activity design.
Refinery plant design
The current high demand for equipment and materials and the reduced number of suppliers has made it more difficult to get fast equipment fabrication schedules and good pricing for both equipment and materials, notes James Turner, director, process technology & engineering for Fluor Corp.’s energy and chemicals division.
“To deal with this challenge, Fluor has worked with our clients to qualify alternative equipment suppliers for critical items such as coke drums for delayed coking units,” he says.
Modern design tools such as 3D computer-aided design (CAD) have revolutionized the process for designing new refinery units, says Turner.
“Tools such as Material Manager and Construction Progress have been linked with the 3D CAD model so that items can be tracked through engineering, procurement, receipt onsite, construction, and commissioning, and the status of items can be displayed in the 3D model,” he points out.
Turner also cites increased use of computational fluid dynamic modeling, which is helping to improve design methods and troubleshoot existing problems.
Such advances in simulation technology will enable more efficient plant design and engineering, says Mark Opheim, director of marketing for oil and gas for Honeywell Process Solutions.
“Honeywell works with both owners and contractors to integrate simulation technology-which features operator training and advanced control modeling solutions-to enable faster start-ups and validate processes while optimizing the entire plant life cycle,” he says. “These advanced applications help visualize future process behavior and improve decision making and performance. Users can develop advanced control, conduct tests, and verify strategies during the design phase within the simulation environment to reduce risk and accelerate payback by an average of 6 months. This also seamlessly transfers essential knowledge into the operations phase and allows operators to apply optimization strategies as soon as they go online.”
Proper selection of process technologies also optimizes refinery operations, contends Odette Eng, vice-president of refining for KBR Energy & Chemicals.
“The traditional means of separating resid from gas oil has been through vacuum distillation. One game-changing alternative would be to use KBR ROSE technology in place of a vacuum column to lift more convertible resid without being constrained by the high temperature in a vacuum column. This is also an environmental issue.”
She also cites the use of selective hydrocracking, which produces high-octane gasoline from light cycle oil with minimum hydrogen consumption, and moderate pressure, high conversion hydrocracking, which can help bring a better return on investment.
Game-changing new technologies in the area of plant design, says Jeff Hazle, technical director, National Petrochemical & Refiners Association, include reliability modeling, life-cycle costing for equipment selection, the addition of instrumentation to enable predictive maintenance, and automated unheading for coker drums.
Turnarounds
Turnaround planning has always been a major effort for refineries, but with the significant loss of flexibility due to the stringent clean fuels specifications, planning for optimal operation during planned and unplanned unit outages is even more important, says Turner.
“Determining which units to shut down together is a challenge in itself-processing requirements suggest shutting more units down at the same time, but this makes shutdown staffing and logistics more challenging,” he says.
Turner cites the big challenge of managing a refinery when key units are down: “As an example, a refinery that relies on FCC feed hydrotreating for compliance with gasoline sulfur specifications will need to figure out how to run the refinery when the hydrotreater comes down for catalyst changeout and the FCC is still operating.”
Turner ticks off these possible refinery responses to an outage:
- Processing stored hydrotreated gas oil (while storing sour gas oil) as the crude feed switches to lower-sulfur crudes.
- Possibly switching services of other units (such as temporarily switching a kerosine hydrotreater into gasoline service).
- Producing higher-sulfur gasoline blendstocks for blending off later.
“Determining the optimum combination of these actions for a refinery is a challenging problem,” notes Turner. “Piping infrastructure to accomplish the optimum plan may not exist, so planning must take place far enough in advance to add the necessary infrastructure.”
Hazle thinks that refiners are focusing more on how well they conduct turnarounds: “They are planning earlier, being more disciplined with respect to ‘scope creep,’ thinking about whether turnarounds should be larger or smaller, paying more attention to the time required to start up and shut down, and moving more work out of the turnaround window.”
Process efficiencies
The increased use of process simulation tools by unit optimization engineers can have a noticeable impact on unit profitability, according to Turner.
“I know of one case where an engineer with strong simulation skills was hired in as a crude unit operations engineer,” he recalls. “He created a simulation of the unit and used it to figure out how to increase throughput by optimizing operating conditions. The refinery cancelled a planned debottlenecking project, since the unit was now running at a higher capacity than the planned revamp capacity.”
On Hazle’s wish list for technology advances to improve process efficiencies are “better measurement technologies, e.g., measurement of radial temperature profiles in hydrocracking reactors; and better reactor internals to improve liquid/vapor distribution in catalyst beds, which improves catalyst usage.”
One game-changing process efficiency is the ability to use low-grade coal in a low-cost transport reactor to meet refinery energy needs, using technology such as KBR’s transport gasification technology, says Eng.
Monitoring, diagnostics
More technology advances are occurring in the area of refinery unit monitoring and diagnostics, says Hazle.
“There seem to be many new technologies for inspection, non-destructive testing, etc.,” he says. “Many companies are giving tools to the process operators that enable them to monitor the condition of equipment (especially rotating).”
Turner notes that low-cost, nonintrusive level detection equipment-which can locate interface levels (gas-liquid, liquid-liquid, and whether there is any foam or emulsions) through the vessel wall using sonic techniques-is taking hold in the market.
“These devices are mounted on the outside of the vessel and do not need any vessel penetrations,” he adds. “These devices are being integrated into the wholesale LPG markets.”
Furthermore, refineries increasingly are using online analyzers to optimize plant performance, says Turner, “led by requirements to understand sulfur levels in hydrotreater products designed for clean fuels specifications.”
Honeywell’s Opheim contends that wireless technology provides “endless possibilities” in the area of refinery unit monitoring and diagnostics.
“Sensors can gather data where traditional devices cannot reach, providing more real-time data to make knowledgeable decisions,” he points out. “A wireless network could, for example, help improve overall refinery and asset reliability by assisting mobile workers with device commissioning and configuration. To do this, the network can enable automated field operator rounds and provide mobile workers access to online data, reports and manuals.
“Another wireless network benefit is the ability to provide equipment health management visualization through features such as a computerized maintenance management system, inventory management, and document management.
“Additionally, an effective system would include input/output modules and sensors to monitor real measurements in refineries versus the use of inferred values.”
Wireless networks also can help refineries comply with industrial and environmental standards through emissions monitoring and leak detection and repair support, Opheim adds.
Instrumentation and control systems
Opheim sees “robust and secure” wireless technology advances as having a transformative effect on the refining industry “by enabling the workforce to be more safe and efficient.”
He notes that wireless enables mobile operators to perform rounds more efficiently and allows better collaboration between field operators and control room operators.
“Real-time data collection allows mobile operators to perform actions in the field and get immediate feedback on results as opposed to radioing back to the control room,” he adds.
Industrial wireless will also drive greater operational benefits, says Opheim: “Additional sensing capabilities can be used to drive more efficient refinery performance. It also provides more visibility into equipment health monitoring, which allows maintenance shops to be more proactive.”
Turner expects to see increased use of HIPPS (high-integrity pressure protection systems) that will help minimize plant upsets that lead to flaring-“an area that many environmental monitoring agencies are beginning to focus on.”
Catalysts
Among the most critical new technology advances in the refining industry has been the nano-engineering of tailored catalysts that have optimized refinery processes across the board.
“The advances in hydroprocessing catalysts over the last 20 years have been amazing,” claims Turner. “It is safe to say that clean fuels regulations would have cost the refining industry at least an order of magnitude more using technology from 15-20 years ago.
“The nano-scale techniques used for research and catalyst development indicate that this improvement in catalyst performance should continue in the near future. Increased use of high-throughput screening techniques will help advance catalyst selectivity and activity improvements for a shorter time to market.”
Refiners are increasingly looking for an integrated approach to managing the catalysts and operations of the FCC pretreater and the FCC units, notes Chuck Olsen, worldwide technical service manager for Advanced Refining Technologies (ART), the hydroprocessing catalysts joint venture of Chevron Corp. and Grace Davison.
“FCC and hydroprocessing operations can be continuously optimized throughout the course of the hydrotreater run to significantly increase refiner revenue.”
ART developed the ApART Catalyst System in 2001, which increases hydrodesulfurization conversion while simultaneously providing significant upgrading of FCC feeds.
“Through its relationship with partner Grace Davison Refining Technologies, ART continues to develop a better understanding of the effects of hydrotreating on FCC unit performance,” Olsen adds. “Grace Davison and ART scientists are exploring the complexity of combinations of catalyst design and operating conditions for both the FCC feed hydrotreater and FCC unit. This scenario presents a major optimization opportunity for refiners to drive the combined operation to maximum product value.”
R&D focus
Several key factors are driving refining technology R&D, according to Rajeev Gautam, vice-president and chief technology officer of UOP LLC.
Among them, he lists the following:
- “Environmental regulations have and continue to drive the need for new technology solutions.
- Low-sulfur fuels technology is pretty much in place now but there is a need to address benzene regulations and Rvp (Reid vapor pressure) limits as ethanol is blended into the gasoline pool. Very novel technology will be required to address these needs cost-effectively.
- The crude slate is getting heavier, and focus is needed on developing better heavy ends upgrading technology.
- Energy security and sustainability issues are driving increasing use of biofuels. Technology is possible and is being developed to process biofeedstocks in existing refineries.
- Increasing demand for diesel and propylene is driving increasingly more efficient conversion technologies, both hydrocracking and catalytic cracking.
- Finally, even though the current focus is on adding capacity, we need to continue to focus on increasing the utilization of our existing assets through process and catalyst improvements.”
New opportunities
Unlike many in the refining industry who fret about government mandates to expand the market share of biofuels in the world’s transportation fuels mix, Gautam sees an opportunity.
“Refiners are best positioned to utilize renewable feedstocks and to create a product slate that is desirable and economical,” he says. “Today, plant oils are converted to biodiesel (FAME), a product that has poor performance in today’s automotive fleet.”
UOP has developed a process that converts plant oils to a diesel indistinguishable from conventional petroleum-derived diesel, Gautam notes.
“This ‘green diesel’ has many advantages over biodiesel, including better CCOP (cash cost of production) and the possibility to blend this product to upgrade LCO (light cycle oil) and other low-quality fuels.
“In the future, we will continue to develop processes for the efficient conversion of biologically derived feedstocks, but these processes will be based on cellulosic waste rather than vegetable oils or greases. The use of waste will improve the economics of the processing of biomass as well as enable access to a broader feedstock supply.
“We believe that in the long term, the integration of renewable feedstocks into existing petroleum refineries creates an opportunity for refiners.”
