of plugging has been observed in microreactors suffering from plugging and improper flow distribution across various reactors in the setup, producing inconclusive results. Pilot plant vs commercial operation There are fundamental operational differences between commercial hydroprocessing units and pilot plants that must be understood when interpreting catalyst performance . Table 4 summarises the key parameters and contrasts how they are handled in both environments. The pilot plant oper- ates under isothermal conditions, allowing for better con - trol over catalyst evaluation, whereas commercial units are adiabatic, using heat management and quench injections to control temperature. To compare the two meaningfully, the weighted average bed temperature (WABT) in the com - mercial unit is matched to the pilot operating temperature. The pilot plant uses highly pure hydrogen (99.99 vol%) and adjusts the hydrogen partial pressure to match the average seen in the commercial unit, ensuring comparability. In terms of product recovery, the pilot plant applies sharp fractionation cut points, ensuring precise product yield assessment. In contrast, commercial units may experience product overlap due to broader cut ranges and tray efficien - cies in distillation columns. However, pilot units, which are not equipped with online stripping or continuous vapour-liquid separation, can expe- rience inconsistencies in the reported product sulphur. Overstripping during offline sample preparation can artifi - cially increase measured product density and underestimate sulphur content, whereas insufficient stripping or cooling may lead to elemental sulphur (S₈) reprecipitation, causing erratic analytical results. Ensuring consistent sample han- dling and implementing controlled online stripping are there- fore essential to avoid false interpretation of catalyst activity and selectivity. Regarding catalyst particle size, the pilot plant uses smaller particles to reduce internal diffusion resistance and increase the length-to-particle diameter ratio (L/D pe ). While commercial units can use larger or mixed particle sizes to manage pressure drop, it remains important to match the weight hourly space velocity (WHSV) in the pilot plant with commercial conditions to compare intrinsic catalyst activity on a per-mass basis. To ensure plug flow in the pilot plant reactor, diluent addition is used to improve catalyst wetting and thereby maximise catalyst utilisation. Testing configurations Catalyst evaluation in pilot plants can follow three distinct configurations, each offering unique benefits and limitations, depending on the testing objective, feedstock type, and reactor capabilities. u R&D units (quick-screening) : Conducted at Topsoe’s in-house research facilities, these ‘quick-screening’ bench- scale reactors are used primarily to evaluate catalyst activity with real feedstocks. Depending on the test scope, product and gas recycle systems or fractionation units may or may not be integrated. These units are ideal for rapid compari- sons under controlled conditions but may have limitations in simulating complex refinery operations.
Solutions at Your Service. Tower & Reactor Internals, Custom Fabrication
Woven Metal Products (WMP) is your answer for mass transfer internals . Regardless of your original equipment manufacturer (OEM), our team will help determine what works best for your project, whether replacement-in-kind or improvement options.
Mass transfer products:
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