Complex Processing Vessel Fabrication Calls for Grace Under Pressure

Engineering Meets Craftsmanship to Address Manufacturing’s Most Acute Needs

Chemical, oil & gas refinery and petrochemical facilities use complex processing vessels such as heat exchangers, chemical reactors, distillation columns, and pressure equipment that operate under extremely intense environments.  

These vessels must endure high temperatures and high pressure over decades of grueling use. They are critical pieces of operating equipment that often function as the central processing units of an entire manufacturing facility. As a result, any equipment downtime can be extremely costly to the operator.

Supporting the many industries that depend on these high-performance vessels is a marketplace of equipment designers and engineers, specialized in metallurgy, vessel fabricators, maintenance and repair services, advanced product testing technologies and certification and accreditation organizations. Given the performance and safety requirements for a complex processing vessel, leading fabricators certify their vessels with the American Society of Mechanical Engineers (ASME) to indicate that their products fulfill the requirements of relevant ASME codes and standards.

Eighty years ago, the roots of the complex processing vessel sector started with boiler manufacture and repair shops and has now grown to include off-the-shelf heat exchanger and pressure vessel fabricators and highly sophisticated and credentialed design and manufacturing specialists. These specialist fabricators work with customers to design, engineer, manufacture, and test ASME Division I and II code vessels of every size, material, and finish including rare and challenging alloys selected for their superior performance and durability.

One of the challenges facing industries that require specialized complex processing vessels is the relatively small number of these specialist fabricators.  There are still relatively few worldwide who provide the in-house design and engineering expertise to craft vessels that can withstand high intensity environments.

Manufacturing processes that involve high temperatures and high pressures require equipment that is constructed from specialized alloys and that are custom-designed to the operator’s unique needs. Far from off-the-shelf, clients often turn to a specialist fabricator to design custom equipment based on a profile of their operating criteria. The fabricator then needs to create a design, engineer, manufacture and test to ASME codes.

Tate & Lyle is a global supplier of ingredients to food and beverage markets. When constructing their plant in McIntosh, Alabama they required custom-designed distillation columns, pressure vessels and heat exchangers. Because of high operating temperatures and pressure, specialized solutions were required for performance and durability. Moreover, the company needed equipment that could run 24/7 with only two shutdowns a year.

“At the time, the engineering team only provided a fabricator with a data sheet of the requirements – things like how many gallons for the vessels, operating temperatures, pressure levels, and how many nozzles were needed. From there, we needed the vendor to come up with the equipment design and be able to build it to ASME Section VIII Div. 1 code,” says Linda Rutherford, a member of the Quality Control department at Tate & Lyle. “Because of the criticality of the equipment to our manufacturing process, we needed equipment that would not break down and stand the test of time. And at this plant, we measure durability in decades.”

Based on a combination of capability, quality, service and price criteria, the company partnered with Alabama-based Mitternight, a fabricator specialist that holds certifications in ASME Div. I and II stamps as well as a Chinese License for Pressure Vessels A2. Mitternight designed and engineered the plant’s original separators, heat exchangers, storage tanks, and pressure vessels. Given the operating parameters, the company built the equipment, which included fabricating pressure vessels more than 100 feet tall, using stainless, specialized alloys.

Complexity Starts with Design & Engineering

The work of fabricating a specialized processing vessel first begins with design and engineering. While an industrial customer will have a finished and approved drawing package for a standard heat exchanger, customers will also seek specialized expertise in designing and engineering vessels for custom processes with unique code parameters. This requires the fabricator to create a piece of equipment that meets their unique and challenging specifications.

As in the case of Tate & Lyle’s plant, complexity can start with the original design request. A process engineer will draw up a concept and then turn to a company like Mitternight to determine how to create it. According to Lance Covan, owner of Mitternight, “Our clients will look to us for the code specifications, identify what’s allowable, define what will meet the certifications of the given parameters they have in their plan and also what will not.”

The design of a new complex processing vessel is a product of material selection which itself is based on temperature and pressure considerations. A fabricating specialist will identify all the parameters based on ASME, metallurgical and temperature requirements to meet a client’s process needs.

Once a vessel is designed and engineered, fabricating to meet the performance specifications requires expertise and craftsmanship in metallurgy. And specialized alloys selected for their performance attributes can themselves be inherently challenging. Welding specialized high-grade nickel alloys of up to 99% nickel, such as Nickel 200 for example, is a demanding process.

There may not even be a weld procedure in existence for the client’s specifications. It then is up to the fabricator to define and achieve the weld parameters that have never before been made. Says Covan, “we’ve had to literally write the manual through the process of fabricating the vessel. We will work with metallurgists on the client side who require certain things without the benefit of any real precedent in the market because the weld has never been made before.”

Staying in Code

Metallurgical craftsmanship is also called upon in the repair of corroded vessels. According to Covan, “a lot of highly corrosive chemical catalysts move in and out of exchangers. We can apply overlays of weld metal with a process that build up the thickness lost to corrosion given the caustic environment. It’s one thing to do this with carbon steel, but when you deal with specialty noble metals, this kind of work is highly specialized.”

Industrial quality control specialists like Tate & Lyle’s Linda Rutherford regularly monitor the thickness of vessels to ensure they remain in specification. “A key to durability is selecting the right metals in the first place”, says Rutherford. “Then when repairs and maintenance are needed, the code work needs to be completed and recertified. We’ve asked Mitternight to repair and complete replacements of pressure vessels and heat exchangers.” 

Vertical Integration Supports Long-Term Success

With so much invested in the performance, safety and durability of complex process vessels, operators can find a lot of value in working with a fabricator who not only has expertise in specialized metal alloys but who can partner with them through the entire design-engineer-fabricate-test-support continuum. Not only do fewer handoffs protect the intellectual property of a client’s process design and custom vessel needs, but there is less risk of fabricating delays.

According to Covan, “Vertical integration means more control and control means making deadlines. Delivery is critical because we can be talking about millions of dollars a day at risk for a client. When you can control the entire process, you have a much better chance of meeting delivery deadlines.”

Tate & Lyle has had a 20-year relationship with Mitternight at their plant which is now the only one of its kind in the U.S. Ongoing support includes the fabrication of new vessels, repairs (including rerolling exchanger tubes). replacements of pressure vessels and heat exchangers and fabricating alterations such as cutting in extra nozzles on 2:1 elliptical heads.

Having a trusted relationship with a specialist fabricator who can support an industrial client from design to service is key to long-term success. In the case of the 12-foot diameter specialized alloy column, Mitternight worked with Tate & Lyle’s senior plant personnel including their QA & Engineering teams to plan, design and schedule in-house fabrication, field work, installation, final welding and testing – all within a scheduled plant shutdown of 8 days.

For more information, contact Mitternight, 5301 US-43,  Satsuma, AL, 36572; visit www.mitternight.com; call (251) 675-2550; email info@mitternight.com.

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DuPont Introduces DuPont™ ConvEx℠ HF Alkylation Conversion and Expansion Technology

DuPont Clean Technologies (DuPont) has announced the launch of the DuPont™ ConvEx℠ HF alkylation conversion technology, the first cost-effective solution that enables refiners to convert volatile and toxic hydrofluoric acid (HF) alkylation units to the safer sulfuric acid alkylation technology. This new technology also offers refiners the opportunity for significant capacity increases at minimal additional cost.

Historically, the expense of converting from HF to sulfuric acid alkylation was estimated by the industry at 80 percent of the cost of a grassroots sulfuric acid alkylation unit of a similar size. This perceived high conversion cost and the lack of any other economic benefits deterred refiners from committing to this change. By reusing much of the existing equipment, conversion with DuPont™ ConvEx℠ technology is estimated to be significantly lower. At approximately 40-60 percent of the cost of a grassroots sulfuric acid alkylation unit, this new technology from DuPont represents a step-change reduction in cost. In situations where plot space is available near the existing facility, downtime can be reduced by installing new equipment during normal operations. With new equipment installation already complete, the remainder of the conversion work can be finalized within a typical 30-45 day turnaround window.

The suite of HF conversion technologies offered by DuPont was developed with flexibility in mind to adapt to the strategic objectives of refiners currently operating HF alkylation units. One of the options that was developed utilizes conventional STRATCO® Contactor™ reactors in order to achieve optimum product quality. A second option incorporates a novel reactor design, allowing for significant cost savings with only a minor performance debit. By taking into consideration the current HF alkylation unit technology and configuration, DuPont’s customized solutions can be tailored to meet the specific business needs of the refinery.

“We are excited to bring this game-changing technology to market,” said Eli Ben-Shoshan, global business director, DuPont Clean Technologies. “For the first time, refiners truly have cost-effective options to ensure the safety of their refinery personnel and surrounding communities, while simultaneously producing high-quality alkylate at increased rates to meet market demand.”

Fundamental to the expansion aspect of the DuPont™ ConvEx℠ technology is the difference in the way in which isobutane is recycled between the HF and sulfuric acid alkylation technologies. HF alkylation units provide all isobutane to the reaction zone by recycling it from the fractionation section, while sulfuric acid alkylation units provide half of the required isobutane from fractionation and half from the refrigeration section (see illustration). This difference is significant, as conversion from HF to sulfuric acid alkylation means isobutane required from fractionation is cut in half, freeing up fractionation space and, therefore, effectively doubling the capacity of the alkylation unit without requiring any significant changes to the fractionation equipment.

HF alkylation conversion using DuPont’s ConvEx℠ technology is unique and innovative, but the design elements and know-how that have made STRATCO® alkylation the leading global alkylation technology are incorporated in these conversion solutions. The resulting product includes proven technology applications, a robust design, and equipment that is familiar to refinery operators.

Cool Planet locates their first renewable gasoline refinery in Louisiana

Cool Planet Energy Systems, a developer of small scale biorefineries which convert non-food biomass into gasoline, jet fuel, and soil enhancing biochar, announced the location of their first commercial biorefinery in Alexandria, Louisiana.

This location on the Port of Alexandria in Rapides Parish will serve as a showcase facility leading the way for hundreds of additional small scale biorefineries that Cool Planet plans to build across the United States. The site was chosen with tremendous support from the city of Alexandria, and the economic development team from the state of Louisiana. The location provides access to an abundance of renewable biomass feedstock, the ability to load fuel onto barges, rail lines and trucks, and excellent local talent to operate the facility.

“Louisiana is known for its substantial oil interests, but now will also have the distinction of being home to the first, of what is planned to become many, production facilities for Cool Planet’s renewable, high-performance gasoline and soil enhancing biochar,” said CEO Howard Janzen. “Our goal for the Alexandria facility is to be economically competitive with conventional fuels made from non-renewable crude oil.”

It is believed that Cool Planet will have one of the lowest capital costs per plant in the refining industry, with project economics that work at facilities 100 times smaller than conventional refineries, while being able to use a wide variety of renewable biomass materials as inputs. With a distributed plant business model at the heart of Cool Planet, the construction is expected to be complete before the end of 2014.

“Cool Planet’s utilization of biomass to create fuel offers opportunities for Southeast U.S. states with vast renewable biomass resources to create local jobs and income while enhancing energy security,” said former Arkansas Lt. Governor and board member Bill Halter

BioGeoChemical-Cycle-Plus-CP-Pyrolysis

The illustration above shows how plants absorb CO2 from the atmosphere as part of the natural carbon cycle. During plant respiration and decomposition, the CO2 is released back into the atmosphere (left image). By using plant biomass as the source of our fuel cycle, the fuel created is considered carbon neutral when it is burned, as it only releases back into the atmosphere the same CO2 that was originally captured by the biomass (right image).

AkzoNobel applies unique caustic soda evaporation system

AkzoNobel Industrial Chemicals will apply a unique caustic soda evaporation system to its new membrane electrolysis plant at the Industry Park Höchst in Frankfurt, Germany.
The system will enable 20% energy savings and will be supplied by Alfa Laval. The evaporation system which will concentrate caustic soda from 32 wt% solution to 50 wt% solution based on evaporation and condensation heat exchangers. By combining the advantages of different types of heat exchangers it is, for the first time, feasible to concentrate caustic soda in a 4-effect evaporation system. This unique Alfa Laval design will enable energy savings of 20% compared to the best traditional designs. The installation will be built at AkzoNobel’s new membrane plant in Frankfurt which will have a capacity of 275,000 ton caustic soda per year. The start-up of the installation is foreseen for the fourth quarter of 2013.
In the contract AkzoNobel and Alfa Laval have agreed that both companies will work closely together to further optimize the installation in order to achieve the lowest possible energy consumption. “The installation of this unique system will boost our ambition to become the sustainability leader in the chlor-alkali industry”, said Martin Riswick, General Manager of AkzoNobel’s Chlor-Alkali business.