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Pressure drop control
Having to shut down a hydroprocessing unit unexpectedly is never good news for a refinery, where maximum on-stream time and uninterrupted cycle lengths are critical for meeting production and profit targets. Yet pressure drops caused by particles in the feed or crust build-up in catalyst beds can put any refinery at risk of an unplanned shutdown.
At Topsoe, decades of experience have given us unique insight into pressure drop formations and the fouling that causes them. Based on this insight, we’ve developed a wide range of solutions that can stop fouling before it stops production at your refinery.
Applications within this area
- Pressure drop controlFrom our proven grading strategies to our shape-optimized toppings, particulate traps and high void fraction ring-shaped catalysts, Topsoe offers a wide range of solutions for combating reactor bed fouling.
- Pressure drop controlTopsoe’s catalyst grading solutions prevent crust formation by gradually increasing the catalytic activity from low in the inert topping to higher, the further down the bed you go.
Grading solutions tailored to your feedstock
Match your catalyst grading to your feedstock for minimum pressure drop build-up and maximum demetallization with tailor-made catalyst grading solutions.
As today’s opportunity crudes and heavier feedstocks become more economically viable, the oil fractions you refine are posing new challenges. Creating the optimal grading solution for your individual feedstock is essential to minimize pressure drop build-up, increase metals pick-up, and reduce downtime and catalyst replacement.
Catalyst grading - An overlooked advantage
The importance of catalyst grading is often underestimated when evaluating the overall efficiency of a unit. With focus only on the main catalysts, you may be unaware of the dramatic difference a well-designed grading solution offers.
Different feedstocks, different grading solutions
All oil fractions are unique, with their own profile of inorganic particulates and dissolved contaminants. Our specifically matched grading solutions deliver the most efficient hydrogenation activity, traps poisons and metals, and converts coke precursors. As a result, your highly active main catalyst lasts longer, requiring fewer turnarounds, giving you more productive run days.
Controlling activity for optimal catalyst performance
In hydroprocessing, refiners are often faced with pressure drop build-up in the catalyst bed. This shortens the catalyst cycle length. Our graded bed solutions are individually designed to maximize the catalyst cycle length. This is achieved by ensuring that the pressure drop across the reactor is not limiting the throughput until the activity of the main bed catalysts has reached End-Of-Run (EOR). By integrating the effect of inert grading layers and active grading layers, you obtain a smooth transition in catalyst activity.
More grading choices, better feedstock match
Creating the optimal match for your specific feed requires a wide range of grading products. We have the industry’s widest range of sizes, shapes, and variety of inert grading solutions and active grading solutions. These differ in pore sizes, pore volumes, surface areas, activities, and affinity for specific poisons. This means we can design the perfect match for your specific feedstock – or even blends of feeds.
Maximize trapping capacity by managing catalyst void fractions
By using grading materials of various shapes and sizes to create a loading with a differentiated filtering effect, you will trap the largest inorganic feedstock contaminants in the upper layers and the smaller particles in the lower layers.
Our grading products are designed with different void fractions and different void sizes. The volume of each catalyst layer is created to retain the various sizes of inorganic particulates and reaction products in the graded bed system throughout the life cycle of the hydrotreating unit.
Avoid catalyst milling with a high-density hold-down layer
Catalyst milling sometimes occurs, particularly in naphtha units, when the gas rate is high, and no gas-liquid distributor is installed. It is also seen in units, where the inlet diffuser is poorly designed.
To avoid catalyst milling, we have specifically designed TK-15: Its optimized shape and high density deliver an effective hold-down function and a high void fraction.
Prevent crust formation by grading catalytic activity
Crust formation usually occurs at the top of the catalyst bed. This causes an increased pressure drop, flow maldistribution, and difficulties during catalyst unloading. It is often caused by “over-activity” of the catalyst. By grading catalytic activity, you can incrementally increase activity from the inert topping down to the main bed. This way you can control the level of catalytic reaction and avoid crust formation.
Some feedstocks contain corrosion products not trapped by your feed filters. These can cause severe pressure drop build-up in your catalyst bed. TK-26 TopTrap™ is an inert grading material designed to pick up iron scale and other inorganic contaminants. It contains a large internal pore volume which picks up contaminants without adding to the bed pressure drop. Thanks to its optimized shape, large void fraction, and macroporous material, TK-26 TopTrap™ traps even very small solid particles.
Solid particulates in feedstock:
- Iron scale (iron oxides/sulfides)
- Coke fines
- Catalyst fines or dust
- Large carbonaceous scales
- Salts (sodium, potassium, calcium, etc.)
Commercial experience and know-how are keys to optimal hydrotreater performance
Naphtha hydrotreaters can experience severe fouling of the catalyst bed. This can be caused by carbonaceous material spalling from the heater and heat exchangers. The installation of a graded bed solution will remove this bottleneck and extend the cycle length. By avoiding three unit turnarounds, including replacement catalyst cost savings, the financial impact at the refinery will be significant.
Reduce metal deposition on main catalysts by customizing pore sizes in grading
Certain metal compounds, such as organic nickel and vanadium, penetrate into the pores of hydrotreating catalysts. Here they rapidly react to form metal sulfides, plugging the pore mouth and decreasing catalyst life
Thanks to their high hydrodemetallization (HDM) activity and high-tolerance for metals deposition, our ring products trap metals inside the pore system. They simultaneously retain interstitial material in the void fraction. By using the different pore sizes of the grading products – with large pores for metal deposition in the top of the first catalyst bed – the lifetime of your main catalyst can be significantly extended.
Stop contaminants and poisons with specialty traps and guards
Crude oils have become more diverse and can contain compounds of arsenic, silicon, and phosphorous. These are severe catalyst poisons that significantly deactivate the catalyst. Trapping these feed contaminants is essential to the protection and efficiency of your main catalyst throughout the cycle. Our specialty guards, such as TK-49, which features a high arsenic uptake, TK-453 SiliconTrap™ for high silicon feeds or TK-455 MultiTrap™ for a high overall level of contaminants can be tailored to your specific unit for maximum catalyst protection.
Catalyst contaminants and poisons:
- Coke (hard or soft)
- Vanadium and nickel
- Mercury, calcium, lead, and other heavy metals