Tube choice matters. Indeed, selecting the right alloy for heat exchangers in a biorefinery can extend your equipment lifetime and enhance safety.
Whether you are producing renewable diesel, or sustainable aviation fuel, there is always a risk of corrosion, cracks, and leaks due to aggressive conditions in the feed, effluent or reactor – leading to unscheduled maintenance.
Advanced Materials Expertise
As a leading manufacturer of stainless steels and special alloys, with roots dating back to 1862 in Sandviken, Sweden, Alleima brings extensive experience (along with a diverse product range) to address some of the world’s toughest material challenges.
Alleima envisions a future of clean, high-performing fuels for cars, trucks, and even aircraft. Whether it is HEFA/ HVO (hydroprocessed esters & fatty acids) or Fisher Tropsch, alcohol to jet or sythetic fuel (CO2 to liquid fuel) the Alleima vision is to advance the entire biofuel industry.
Safe and efficient hydro processing
Some companies are already utilizing 100% renewable raw materials, such as vegetable oil, used cooking oil, and animal fat, to reduce greenhouse gas emissions by up to 75-95% compared to fossil-based fuels. Alleima assists them in identifying the optimal corrosion-resistant materials for various types of heat exchangers such as feed/effluent, reactor effluent air cooler (REAC) and fractionator – for most hydroprocessing steps.
Alleima supports Biofuels International Conference & Expo
Alleima is sponsoring this year’s Biofuel International conference and expo, on June 18 & 19 in Brussels, and experts from the company will be available to discuss biorefining goals with customers.
Sanicro® 35: a cost-efficient alternative for biorefineries
Today, many biorefineries often resort to costly Alloy 625 or Haste alloy C-276 to safeguard against corrosion. Now, there is another option. Alleima has developed a new
grade called Sanicro® 35 that bridges the gaps between high -alloyed stainless grades and nickel alloys – a cost-effective and superb corrosion-beater.
Sanicro® 35 has been proven to match the pitting resistance of Alloy 625 and outperforms the same when it comes to crevice corrosion. Sanicro® 35 is also an excellent option to Alloy 625 in case of ammonium chloride corrosion.
Solving corrosion challenges from feedstock conversion: hear Jonas Höwing, Technical Marketing Specialist, EMEA, Alleima, at Biofuel International
Converting from fossil fuel to renewable feedstock can create significant corrosion challenges for refineries. On day one of Biofuel International, Jonas Höwing, Technical Marketing Specialist, EMEA, Alleima, will deliver a presentation discussing these important challenges.
Moving the biofuels industry forward with advanced materials
The hydroprocessing of renewable feedstock to produce renewable diesel and sustainable aviation fuel puts a high demand on materials.
Depending on the feedstock, processing can include a pretreatment step but is always followed by hydrotreating to remove heteroatoms such as sulfur, nitrogen, oxygen, from the hydrocarbons. Any chlorides present in the hydrotreater will form hydrochloric acid.
After processing the renewable feedstock, the remaining product is a fuel that is chemically identical to that based on fossil feedstock. But, while hydrotreating is a standard process also used for fossil-based feedstock, there are important differences for renewable feedstock that put high demands on the corrosion resistance of the materials used in piping and heat exchangers.
In comparison with the hydroprocessing of fossil feedstock, renewable feedstock will lead to more acidic processes, as it contains more oxygen that can form carbon dioxide and carbonic acid and less nitrogen that can form ammonia. In addition, depending on the source of the renewable feedstock, the chloride content can be high. The effluent from the hydrotreating unit will contain little or no ammonia to buffer the acidity from carbonic and hydrochloric acid, leading to acidic streams with a pH as low as 2. This low pH combined with the presence of chlorides places high performance requirements on the materials used for piping and heat exchangers to avoid pitting and stress corrosion cracking.
Feed/effluent heat exchangers have traditionally used stainless steel grades TP321 or TP347 for tubing in both fossil-based and renewable feedstock plants. However, these grades are prone to stress corrosion cracking and pitting corrosion in high chloride environments.
Alloy 625 has commonly been used as an upgrade to replace cracked TP321 and TP347 steels. REACs in renewable hydro processing plants are in principle exclusively made from alloy 625 due to the risk of stress corrosion cracking, although the even higher alloyed C-276 has also been used.
Where a nickel-based alloy is considered due to the risk of stress corrosion cracking, SanicroÒ 35 offers a new effective solution.
Sanicro 35 also has similar pitting corrosion resistance as Alloy 625 and has better crevice corrosion resistance than alloy 625 (critical crevice temperature 45°C compared to 25°C for alloy 625 tested to ASTM G48F)
It's no surprise that Sanicro® 35 is already proving to be a cost-effective alternative to nickel-based alloys, enabling large cost savings when building new hydroprocessing units or upgrading existing ones.
Advance renewable diesel refining with Sanicro® 28
Another material from Alleima that is moving the industry forward is Sanicro® 28. This high alloy multi-purpose austenitic stainless steel is designed for highly aggressive and corrosive environments. It is a proven successful alternative to alloy 304 and alloy 825 for the replacement of failed tubes in feed/ effluent heat exchangers in fossil hydrotreating units.
Sanicro® 28 has high corrosion resistance in strong acids, very good resistance to stress corrosion cracking, and intergranular corrosion in various environments. It also has high resistance to pitting and crevice corrosion better than 904L, although not as good as super austenitic grades such as 254 SMO.
Sanicro® 28 is currently being used in the REACs of the hydro processing unit at one of the largest renewable diesel refineries in the US Gulf Coast.
Quality and sustainability
Alleima supports its customers’ quality and sustainability goals. Its fully integrated manufacturing process ensures full traceability from research and development to end-product, and it holds most quality certificates. Alleima has joined the Science Based Targets initiative and uses 80% recycled material and more than 96% fossil-free energy at its production sites, among other initiatives.
By using engineering as a force for sustainable good, Alleima works with its customers to make innovative changes that bring about the biggest difference. By offering more than 900 advanced alloys, Alleima can make a change globally.
Raised productivity. More efficient energy production. Renewable technologies. Reduced environmental impact. Lighter materials. By advancing technologies, Alleima products and materials are tackling the challenges of today and tomorrow.
With a successful history in supporting the biofuels industry with the absolute best in materials technology, Alleima will never stop innovating, creating the best quality materials, and putting its customers first. The company believes that when it advances materials its customers benefit too, helping to raise productivity, energy efficiency, and minimizing environmental impact.